Three cases of dogs with osteosarcoma of the forelimb treated with liquid nitrogen for limb-sparing surgery using autologous bone

Osteosarcoma treatment with limb-sparing surgery using liquid nitrogen can be applied to canine patients experiencing diminished quality of life after leg amputation. In particular, forelimb amputation may affect gait more than hindlimb amputation. In this study, limb-sparing surgery using liquid nitrogen was applied to primary osteosarcomas arising in the proximal scapula of a Welsh Corgi, the proximal humerus of a Golden Retriever, and the distal radius of a Great Pyrenees, according to the protocol of Tsuchiya et al. In all cases, postoperative radiographic examination revealed bone union between the treated and matrix bones. All patients recovered their gait postoperatively. These results suggest that limb-sparing surgery using liquid nitrogen-treated autologous bone is an effective option for patients with osteosarcoma.

Exfoliation of Metal-Organic Frameworks to Give 2D MOF Nanosheets for the Electrocatalytic Oxygen Evolution Reaction

The structure and properties of materials are determined by a diverse range of chemical bond formation and breaking mechanisms, which greatly motivates the development of selectively controlling the chemical bonds in order to achieve materials with specific characteristics. Here, an orientational intervening bond-breaking strategy is demonstrated for synthesizing ultrathin metal-organic framework (MOF) nanosheets through balancing the process of thermal decomposition and liquid nitrogen exfoliation. In such approach, proper thermal treatment can weaken the interlayer bond while maintaining the stability of the intralayer bond in the layered MOFs. And the following liquid nitrogen treatment results in significant deformation and stress in the layered MOFs' structure due to the instant temperature drop and drastic expansion of liquid N2, leading to the curling, detachment, and separation of the MOF layers. The produced MOF nanosheets with five cycles of treatment are primarily composed of nanosheets that are less than 10 nm in thickness. The MOF nanosheets exhibit enhanced catalytic performance in oxygen evolution reactions owing to the ultrathin thickness without capping agents which provide improved charge transfer efficiency and dense exposed active sites. This strategy underscores the significance of orientational intervention in chemical bonds to engineer innovative materials.

Frozen inactivated autograft replantation for bone and soft tissue sarcomas

Background

The frozen inactivation of autologous tumor bones using liquid nitrogen is an important surgical method for limb salvage in patients with sarcoma. At present, there are few research reports related to frozen inactivated autograft replantation.

Methods

In this study, we retrospectively collected the clinical data of patients with bone and soft tissue sarcoma treated with liquid nitrogen-frozen inactivated tumor bone replantation, and analyzed the safety and efficacy of this surgical method. The healing status of the frozen inactivated autografts was evaluated using the International Society of Limb Salvage (ISOLS) scoring system. Functional status of patients was assessed using the Musculoskeletal Tumor Society (MSTS) scale.

Results

This study included 43 patients. The average length of the bone defect after tumor resection is 16.9 cm (range 6.3-35.3 cm). Patients with autograft not including the knee joint surface had significantly better healing outcomes (ISOLS scores) (80.6% ± 15% vs 28.2% ± 4.9%, P<0.001) and limb function (MSTS score) (87% ± 11.6% vs 27.2% ± 4.4%, P<0.001) than patients with autografts including the knee joint surface. The healing time of the end of inactivated autografts near the metaphyseal was significantly shorter than that of the end far away from the metaphyseal (9.8 ± 6.3 months vs 14.9 ± 6.3 months, P=0.0149). One patient had local recurrence, one had an autograft infection, five (all of whom had an autograft including the knee joint surface) had joint deformities, and seven had bone non-union.

Conclusion

Frozen inactivated autologous tumor bone replantation is safe and results in good bone healing. But this method is not suitable for patients with autograft involving the knee joint surface.

Complications and Outcome of Bone Sarcoma Patients with Limb Salvage using Liquid Nitrogen-treated Bone for Reconstruction

Introduction

The recommended treatment method for bone sarcoma is wide local excision and reconstruction to preserve limb function. Established methods of reconstruction are mega prosthesis or biological reconstruction. This study aimed to determine the complications and functional outcomes associated with limb salvage surgery using liquid nitrogen-treated bone.

Materials and Methods

We retrospectively observed the short-term outcome of limb salvage surgeries where liquid nitrogen bone was used for reconstruction. A total of 15 patients underwent reconstruction with liquid nitrogen auto graft from January 2018 to December 2020. We used the free freezing method of liquid nitrogen treatment after wide local excision of sarcoma. We observed short-term outcomes after liquid nitrogen-treated bone reconstruction in limb salvage surgery. Survival of the auto grafts was recorded using the Kaplan-Meier method with a 95% confidence interval.

Results

The mean follow-up was 19.83 ± 4.5 months. The mean musculoskeletal tumor society score was 62.4 ± 7.9%, while the average Toronto extremity score was 59.6 ± 5.7%. Three patients died during the study duration due to visceral metastasis. Skin necrosis and wound breakdown were major complications in 9 (60%) patients. Deep infection was observed in 4 (26.7%). Similarly, 4 (26.7%) patients had non-union at either the proximal or distal osteotomy site, while the average time of bone union in the rest of the patients was 6.3 ± 1.7 months. A total of 6 (40%) patients underwent reoperation after liquid nitrogen treatment, either due to infection or non-union at the osteotomy site. Recurrence was observed in 3 (20%) of patients.

Conclusion

We observed a high complication rate with liquid nitrogen-treated autograft reconstruction. Vascularized fibula with liquid nitrogen-treated autograft or endoprosthesis should be encouraged.

Current status of the cryopreservation of embryogenic material of woody species

Cryopreservation, or the storage at liquid nitrogen temperatures (-196°C), of embryogenic cells or somatic embryos allows their long-term conservation without loss of their embryogenic capacity. During the last decade, protocols for cryopreservation of embryogenic material of woody species have been increasing in number and importance. However, despite the large experimental evidence proved in thousands of embryogenic lines, the application for the large-scale conservation of embryogenic material in cryobanks is still limited. Cryopreservation facilitates the management of embryogenic lines, reducing costs and time spent on their maintenance, thus limiting the risk of the appearance of somaclonal variation or contamination. Somatic embryogenesis in combination with cryopreservation is especially useful to preserve the juvenility of lines while the corresponding clones are being field-tested. Hence, when tree performance has been evaluated, selected varieties can be propagated from the cryostock. The traditional method of slow cooling or techniques based on vitrification are mostly applied procedures. For example, slow cooling methods are widely applied to conserve embryogenic lines of conifers. Desiccation based procedures, although simpler, have been applied in a smaller number of species. Genetic stability of the cryopreserved material is supported by multiloci PCR-derived markers in most of the assayed species, whereas DNA methylation status assays showed that cryopreservation might induce some changes that were also observed after prolonged subculture of the embryogenic lines. This article reviews the cryopreservation of embryogenic cultures in conifers, fruit species, deciduous forest species and palms, including a description of the different cryopreservation procedures and the analysis of their genetic stability after storage in liquid nitrogen.

Processing and storage methods affect oral and gut microbiome composition

In microbiome studies, fecal and oral samples are stored and processed in different ways, which could affect the observed microbiome composition. In this study, we compared storage and processing methods applied to samples prior to DNA extraction to determine how each affected microbial community diversity as assessed by 16S rRNA gene sequencing. We collected dental swabs, saliva, and fecal samples from 10 individuals, with three technical replicates per condition. We assessed four methods of storing and processing fecal samples prior to DNA extraction. We also compared different fractions of thawed saliva and dental samples to fresh samples. We found that lyophilized fecal samples, fresh whole saliva samples, and the supernatant fraction of thawed dental samples had the highest levels of alpha diversity. The supernatant fraction of thawed saliva samples had the second highest evenness compared to fresh saliva samples. Then, we investigated the differences in observed community composition at the domain and phylum levels and identified the amplicon sequence variants (ASVs) that significantly differed in relative abundance between the conditions. Lyophilized fecal samples had a greater prevalence of Archaea as well as a greater ratio of Firmicutes to Bacteroidetes compared to the other conditions. Our results provide practical considerations not only for the selection of storage and processing methods but also for comparing results across studies. Differences in processing and storage methods could be a confounding factor influencing the presence, absence, or differential abundance of microbes reported in conflicting studies.

Comparison of the Results of Patients Treated With Limb-Sparing Treatment Options in Malignant Bone Tumors: Sharing the Experience of Twelve Bicentric Patients

OBJECTIVES

Extremity-sparing surgery should be the main objective if a functional extremity is to be obtained in cases of malignant bone tumors. After extensive resection, numerous techniques have been described to reconstruct bone defects. This study aimed to compare the outcomes of patients who underwent external radiation therapy and liquid nitrogen biological reconstruction at two different facilities.

METHODS

The study included 12 patients who received biological reconstruction therapy for bone sarcoma and had at least two years of follow-up. Demographic data, pathological diagnosis, presence of systemic metastasis, and recurrence during follow-up were among the information logged. Patients who used liquid nitrogen were placed in group 1, and those who underwent external irradiation were placed in group 2. After being contacted for their final follow-up appointments, the outcomes were compared by recording the Musculoskeletal Tumor Society Score (MSTSS).

RESULTS

For participants with a mean age of 10.75±3.6 (5-17), the follow-up period was 30.2±16.3 months in total. In contrast to the patients in group 1, who experienced union on average after 7.5±1.2 months, those in group 2 experienced union after 7.6±1.1 months. Patients in group 1 had an MSTSS of 75.5±11.8%, while those in group 2 had a score of 77±4.4. There was no discernible difference between the two groups' union times (p>0.05). There was no statistically significant difference between the two groups' MSTSS (p>0.05).

CONCLUSION

After tumor resection, extracorporeal radiation therapy and the application of liquid nitrogen are still useful treatment options and neither of them is superior to the other.

Free tissue reconstruction of a liquid nitrogen burn: a case report and literature review

Due to its boiling point of -196°C, liquid nitrogen is a cryogenic substance which is commonly used in many industries for its cooling properties. However, this extreme cooling capability means it also has the potential to inflict severe full-thickness burns. Despite its widespread use in the workplace, very little has been described in the literature regarding complex reconstruction of liquid nitrogen burns. We present a case that is unique, not only in its unusual mechanism of injury, but also in that it is the first described case of free tissue reconstruction of cryogenic burns.

Nanomaterial Production from Metallic Vapor Bubble Collapse in Liquid Nitrogen

Nanomaterials with unique structural and properties can be synthesized by rapid transition of the thermodynamic state. One promising method is through electrical explosion, which possesses ultrafast heating/quenching rates (dT/dt~10⁹ K/s) of the exploding conductor. In this study, experiments were performed with fine metallic wire exploding in liquid nitrogen (liq N2, 77 K) under different applied voltages. For the first time in the literature, the physical image of the electrical explosion dynamics in liq N2 is depicted using electro-physical diagnostics and spatial-temporal-resolved photography. Specifically, the pulsation and collapse processes of the vapor bubble (explosion products) have been carefully observed and analyzed. As a comparison, an underwater electrical explosion was also performed. The experimental results suggest that the vapor bubble behavior in liq N2 differs from that in water, especially in the collapse phase, characterized by secondary small-scale bubbles in liq N2, but multiple bubble pulses in water; correspondingly, the products' characteristics are discrepant.

Successful Treatment of Cutaneous Leishmaniasis With Cryotherapy

Leishmaniasis, a protozoal infection, is a growing health concern with 1.5 million new cases reported annually resulting in a wide spectrum of disease and clinical presentations. The disease is endemic in 98 countries with increasing prevalence in non-endemic areas. There are various treatment approaches that are often individualized based on host and parasite factors. Current treatment guidelines and data are variable and provide limited direction for specific treatment plans. Additionally, current recommended therapies are not benign, and are expensive and unavailable to most patients, especially in low-resource areas where leishmaniasis is most prevalent. Here, we report the diagnosis and successful treatment of cutaneous leishmaniasis in a 65-year-old male, who recently traveled to Mexico. Initial treatment with topical antifungals and oral antibiotics was ineffective. After successive treatment with local liquid nitrogen, the lesions completely resolved with no adverse effects or recurrence. Given there is limited evidence-based data supporting cryotherapy treatment as a first-line treatment, this report supports the efficacy of cryotherapy as a safe, cost-effective, and accessible treatment for cutaneous leishmaniasis.

Follow-up of biological reconstruction of epiphysis preserving osteosarcoma around the knee in children: A retrospective cohort study

Limb salvage treatment for malignant bone tumors in children includes prosthetic and biological reconstruction. Early function following prosthesis reconstruction is satisfactory; however, there are several complications. Biological reconstruction is another way to treat bone defects. We evaluated the effectiveness of reconstruction of bone defects by liquid nitrogen inactivation of autologous bone with preserving epiphysis in 5 cases of periarticular osteosarcoma of the knee. We retrospectively selected 5 patients with articular osteosarcoma of the knee who underwent epiphyseal-preserving biological reconstruction in our department between January 2019 and January 2020. Femur involvement occurred in 2 cases and tibia involvement occurred in 3 cases, with an average defect of 18 cm (12-30 cm). The 2 patients with femur involvement were treated with inactivated autologous bone by liquid nitrogen with vascularized fibula transplantation. Among the patients with tibia involvement, 2 were treated with inactivated autologous bone with ipsilateral vascularized fibula transplantation and 1 was treated with autologous inactivated bone with contralateral vascularized fibula transplantation. Bone healing was evaluated by regular X-ray examination. At the end of the follow-up, lower limb length, knee flexion, and extension function were evaluated. Patients were followed up for 24 to 36 months. Average bone-healing time was 5.2 months (3-8 months). All patients achieved bone healing with no tumor recurrence and no distant metastasis and all patients survived. The lengths of both lower limbs were equal in 2 cases, with shortening by ≤1 cm in 1 case and shortening by 2 cm in 1 case. Knee flexion was >90° in 4 cases and between 50 and 60° in 1 case. The Muscle and Skeletal Tumor Society score was 24.2 (range 20-26). Inactivation of autogenous bone with the epiphysis preserved by liquid nitrogen combined with vascularized fibula reconstruction for periarticular osteosarcoma of the knee in children is safe and effective. This technique supports bone healing. Postoperative limb length and function, and short-term effects were satisfactory.

A Comparative Study on the Effect of Euthanasia Methods and Sample Storage Conditions on RNA Yield and Quality in Porcine Tissues

Animals used in research often have to be euthanised, especially when tissue sampling is essential. Recently, a euthanasia method, utilizing an inhalant anaesthetic 'nitrogen gas in foam' in an anoxia box (ANOXIA^TM), has gained considerable interest as it claimed to be more animal-friendly. However, it is not clear whether the use of this euthanasia method has an influence on RNA measurements. Moreover, there are no studies on the interaction effect of different euthanasia methods on the tissue sample storage conditions. The current study compared RNA measurements from two euthanasia methods (ANOXIA^TM vs. T-61^® injection) and two storage conditions (RNAlater™ vs. snap freezing) in 12 male piglets. The nitrogen anoxia method had a significantly higher RNA yield (p < 0.01) compared to the T-61^® method. However, no effect of the euthanasia methods on the A260/230 ratio and RIN value was observed. Tissues stored in RNAlater™ had significantly higher RIN values (p < 0.001) compared to snap frozen samples. The present study could not find a significant difference between the two euthanasia methods in piglets, with regard to RNA quality measurements. Hence, the nitrogen anoxia technique (ANOXIA^TM) might be considered as a suitable alternative to T-61^® for euthanasia of piglets used in research.

Cryopreservation of Malus and Pyrus Wild Species in the 'Fruit Genebank' in Dresden-Pillnitz, Germany

A unique and valuable diversity of the Malus and Pyrus wild species germplasm is maintained ex situ in field collections in the 'Fruit Genebank' in Dresden-Pillnitz, Germany. (1) Background: The establishment of a duplicate collection is necessary to preserve this material safely from abiotic and biotic stress factors. (2) Methods: Two different techniques, cryopreservation using dormant buds and PVS2 vitrification using in vitro shoot tips, were applied and compared. (3) Results: In Malus altogether 180 accessions belonging to 32 species were processed with an average recovery rate of 39% within ten years using the dormant bud method. Accessions, 116 in number, achieved the criterion of 40% recovery which was 64.44% of all accessions tested. In the case of Pyrus germplasm a total of 35 accessions of 21 species and both techniques for cryopreservation were tested. In the results of these experiments the PVS2 method led to better results compared to the dormant bud method. (4) Conclusions: In Malus the dormant bud technique will be the method of choice for the future to build up the duplicate collection. Further experiments using both techniques are planned in the future to make a final decision for Pyrus.

Biomechanical Analysis of Bone Graft Treated With Pasteurization or Cryotherapy Using Liquid Nitrogen: A Study Using Sheep Bone Model

Osteosarcoma is a common primary malignancy of the bone. Osteosarcoma prognosis improves tremendously when chemotherapy is given in adjunct to surgical intervention. Limb reconstruction with sterilized autologous bone graft stabilized by orthopaedics implants has become a choice of treatment, but the biomechanical property of the bone treated with such sterilization method is a point of concern as a graft with inferior biomechanical property might lead to graft failure. This study compares the biomechanical properties of the bones treated with cryotherapy using liquid nitrogen and pasteurization in the form of four-point bending compression tests. Six sheep tibia bones were used for each group of treatment with one control group where no treatment was given. In the four-point bending test, osteotomy was performed at the tibia; the proximal tibia was treated with liquid nitrogen and pasteurization respectively. The treated bone is then reconstructed with the corresponding distal bone with locking plate and screws (Jiangsu Trauhiu Medical Instrument Co. Ltd., Changzhou, China). The four-point bending test was performed with an Electropulse® E3000 universal testing machine (Instron®, High Wycombe, United Kingdom) and results in the form of maximum compressive load, stress, and strain were collected. Photographic analysis of the fracture location and pattern were documented and analysed. We found that both methods of sterilization did not alter the biomechanical properties of the treated bone to the extent of statistical significance in comparison with the control group. However, other factors such as histological changes post treatment, equipment availability, and long-term outcome must be considered.

A Modified Spinal Reconstruction Method Reduces Instrumentation Failure in Total En Bloc Spondylectomy for Spinal Tumors

Introduction

Long-term spinal stability after total en bloc spondylectomy (TES) is challenging. The aim of this study was to examine whether the new method could reduce the incidence of instrumentation failure (IF).

Methods

We retrospectively compared 116 patients with spinal tumors who underwent TES between 2010 and 2019 and were followed up for >1 year. IF, cage subsidence, and complications were evaluated. Propensity score matching between conventional and new method groups was performed for age, sex, body mass index, preoperative radiotherapy, number of resected vertebrae, number of instrumented vertebrae, tumor level, and follow-up period. There were 25 cases each in the conventional and new method groups. The conventional method used a titanium mesh cage for anterior reconstruction and 5.5-mm-diameter titanium alloy rods for posterior fixation. The new method used a more robust cage for anterior reconstruction, bone grafting was performed around the cage, and 6.0-mm-diameter cobalt chromium rods were used for posterior fixation. We compared the incidence of IF and cage subsidence after TES between the conventional and new method groups.

Results

While 5 out of 25 patients (20.0%) in the conventional method group experienced IF, none from the new method group experienced IF. Three-year implant survival rates were 87.3% in the conventional and 100% in the new method groups. The new method group had a significantly higher implant survival rate (p<0.01). Cage subsidence was observed in 11 of 25 (44/0%) patients in the conventional method and 1 of 25 (4.0%; significantly lower, p<0.05) in the new method group.

Conclusions

The new reconstruction method significantly reduced IF incidence in patients with TES.

Long term follow up of patients with low grade chondrosarcoma in the appendicular skeleton treated by extended curettage and liquid nitrogen

BACKGROUND

Chondrosarcoma is the second most common sarcoma of bone, accounting for about 25% of primary bone tumors. Histological grading is the single most important determinant of local recurrence and metastases, where low grade chondrosarcoma (grade 1: atypical cartilaginous lesion) is associated with 10 years survival rate 79-100%. There has been always a debate about the need for wide resection in managing low grade chondrosarcoma, where several reports describe successful management with intralesional curettage and adjuvant therapy, minimizing the need for complex reconstructive procedures and improving the expected outcomes.

HYPOTHESIS

Grade 1 chondrosarcoma of the appendicular skeleton can be successfully treated through extended curettage and liquid nitrogen with favorable oncological and functional outcomes.

PATIENTS AND METHODS

We retrospectively assessed 113 patients with low grade chondrosarcoma in the appendicular skeleton, who were treated by extended curettage, adjuvant therapy using liquid nitrogen, reconstruction using polymethyl methacrylate and prophylactic fixation. Patients were assessed regarding incidence of recurrence, incidence of non-oncological complications and functional outcome.

RESULTS

The mean follow up period was 110 months. In three patients (2.7 %), local recurrence occurred. 5.3% of the patients got non-oncological complications that were successfully managed. The mean MSTS score was 95 %, with no evidence of distant metastases or disease related mortality.

CONCLUSION

Grade 1 chondrosarcoma in the appendicular skeleton can be effectively treated using extended curettage, liquid nitrogen as adjuvant, and cement as filler. Prophylactic fixation is required to avoid pathological fractures. When done properly, excellent functional outcome is expected.

LEVEL OF EVIDENCE

IV, Case series (retrospective comparative study).

Interim Storage of Biospecimen at Satellite Collection Centers: Dewar and Cryotube Choice Are Important for Temporary Storage in Liquid Nitrogen

One major goal of biobanks is to provide the best possible biospecimen quality for research use. This can be achieved, notably in accredited structures, by using standardized procedures for collection, processing, and storage of biosamples and associated data. Since tissue samples of a clinical biobank are commonly collected at surgical theaters in satellite locations or hospitals in remote areas, adequate temporary storage of the biosample is mandatory to maintain optimal sample quality. In cases where immediate snap freezing of the collected material is possible, interim storage of the samples in portable dewars filled with liquid nitrogen (LN₂) is a widely used method. Therefore, the ideal dewar size and maximum storage time need to be considered to maintain an optimal biospecimen quality. In addition, the nature of the cryotube material is an important aspect for keeping the biosample safe while storing it in LN₂. The objective of this study was to test different dewar vessels with respect to LN₂ volume and consumption and to analyze the impact of LN₂ contact on cryotube material through scanning electron microscopy.

Bryophyte Spores Tolerate High Desiccation Levels and Exposure to Cryogenic Temperatures but Contain Storage Lipids and Chlorophyll: Understanding the Essential Traits Needed for the Creation of Bryophyte Spore Banks

Understanding the desiccation and freezing tolerance of bryophyte spores is vital to explain how plants conquered land and current species distribution patterns and help to develop efficient ex situ conservation methods. However, knowledge of these traits is scarce. We investigated tolerance to drying (at 15% relative humidity [RH] for two weeks) and freezing (1 h exposure to liquid nitrogen) on the spores of 12 bryophyte species (23 accessions) from the UK. The presence of storage lipids and their thermal fingerprint, and the levels of unfrozen water content, were determined by differential scanning calorimetry (DSC). The presence of chlorophyll in dry spores was detected by fluorescence microscopy. All species and accessions tested tolerated the drying and freezing levels studied. DSC suggested that 4.1−29.3% of the dry mass is storage lipids, with crystallization and melting temperatures peaking at around −30 °C. Unfrozen water content was determined <0.147 g H2O g−1 dry weight (DW). Most of the spores investigated showed the presence of chlorophyll in the cytoplasm by red autofluorescence. Bryophyte spores can be stored dry at low temperatures, such as orthodox seeds, supporting the creation of bryophyte spore banks. However, the presence of storage lipids and chlorophyll in the cytoplasm may reduce spore longevity during conventional storage at −20 °C. Alternatively, cryogenic spore storage is possible.

Cryo-Treatment Enhances the Embryogenicity of Mature Somatic Embryos via the lncRNA-miRNA-mRNA Network in White Spruce

In conifers, somatic embryogenesis is uniquely initiated from immature embryos in a narrow time window, which is considerably hindered by the difficulty to induce embryogenic tissue (ET) from other tissues, including mature somatic embryos. In this study, the embryogenic ability of newly induced ET and DNA methylation levels was detected, and whole-transcriptome sequencing analyses were carried out. The results showed that ultra-low temperature treatment significantly enhanced ET induction from mature somatic embryos, with the induction rate from 0.4% to 15.5%, but the underlying mechanisms remain unclear. The newly induced ET showed higher capability in generating mature embryos than the original ET. DNA methylation levels fluctuated during the ET induction process. Here, WGCNA analysis revealed that OPT4, TIP1-1, Chi I, GASA5, GST, LAX3, WRKY7, MYBS3, LRR-RLK, PBL7, and WIN1 genes are involved in stress response and auxin signal transduction. Through co-expression analysis, lncRNAs MSTRG.505746.1, MSTRG.1070680.1, and MSTRG.33602.1 might bind to pre-novel_miR_339 to promote the expression of WRKY7 genes for stress response; LAX3 could be protected by lncRNAs MSTRG.1070680.1 and MSTRG.33602.1 via serving as sponges for novel_miR_495 to initiate auxin signal transduction; lncRNAs MSTRG.505746.1, MSTRG.1070680.1, and MSTRG.33602.1 might serve as sponges for novel_miR_527 to enhance the expression of Chi I for early somatic embryo development. This study provides new insight into the area of stress-enhanced early somatic embryogenesis in conifers, which is also attributable to practical applications.

Liquid Helium Enhanced Vitrification Efficiency of Human Bone-Derived Mesenchymal Stem Cells and Human Embryonic Stem Cells

Stem cells have the capacity to self-renew and differentiate to specialized cells, which are usually sensitive to cryopreservation. Therefore, the cell survival rate of stem cells using common cryopreservation protocol is generally not ideal. High cooling rates are crucial for decreasing the usage of cryoprotectants (CPAs) and promoting the successful vitrification of stem cells. In this study, we adopted liquid helium (LHe) instead of liquid nitrogen (LN2) as the cryogen to achieve high cooling rates for vitrifying stem cells with high viability and complete functions. A numerical model was established to simulate the cooling processes of vitrifying specimens by immersing them in LHe and LN2. The calculated results revealed higher cooling rates when plunging specimens into LHe than into LN2. The high viability of human bone-derived mesenchymal stem cells (hBMSCs) and human embryonic stem cells (hESCs) after vitrifying into LHe also shows the superiority of LHe as the cryogen. Furthermore, considerable cell viability was achieved by vitrification in LHe, even when decreasing the concentrations of CPAs. Additionally, post-vitrification, the cells still maintained high attachment and proliferation efficiency, normal stemness, and multipotential differentiation both for hBMSCs and hESCs. LHe is prospective to be employed as a universal cryogen for vitrification which has a great potential for widespread applications, including bioengineering and clinical medicine.

The Role of N-acetylcysteine in the Treatment of Accidental Submersion of the Hands in Liquid Nitrogen

N-acetylcysteine (NAC) is a compound with numerous uses, especially in cases which require prevention of cellular damage. To the authors’ knowledge, no reports of NAC as treatment for liquid nitrogen (LN2) injuries currently exist. We present a case in which a 40-year-old woman accidentally submerged her hands in LN2 while working in a lab. The patient was treated with NAC, antibiotics, and wound care. Six months post-injury, the patient had full range of motion, full sensation, full function, and no pain. Therefore, NAC, in combination with dressing changes and antibiotics, can be used to successfully treat patients with LN2 burns.

Self-Induced Type-I Band Alignment at Surface Grain Boundaries for Highly Efficient and Stable Perovskite Solar Cells

The open-circuit voltage (V_OC ) of perovskite solar cells (PSCs) is reported to be significantly weakened by carrier loss at the film surface. Here, the moisture condensation at only the upper surface of perovskite films is controlled by constructing an ultralow surface temperature. Then, type-I band alignment can be formed at the surface grain boundaries due to the etching effect of trace amounts of condensed moisture. The beneficially constructed surface type-I band alignment can effectively repel carriers and return them to the inside of the grain, significantly avoiding the carrier loss at films surface. As a result, a superior carrier lifetime exceeding 2.5 µs is obtained and the V_OC of PSC is remarkably boosted from 1.07 to 1.17 V. The minimum V_OC deficit of only 0.39 V enables a substantial gain in power conversion efficiency (PCE) from 20.2% to 22.4% in one-step spin-coating methods. Moreover, this innovation is versatile and a champion PCE of 23.2% is also achieved in two-step spin-coating methods.

Cryotherapy: Tips and Tricks

Cryotherapy using liquid nitrogen as cryogen is a well-established therapeutic modality in dermatology. In recent times, there have been many innovations and improvisation of cryotherapy for various dermatological disorders. In this article, we present a short comprehensive collation of practically useful points of cryotherapy covering the various aspects of procedure-planning, patient selection, storage and delivery techniques, and challenging clinical scenarios which can enhance the utility of this efficacious and economic treatment option.

In Vitro Effects of Leaf Extracts from Brassica rapa on the Growth of Two Entomopathogenic Fungi

This study aimed to determine the inhibitive or stimulatory effects of leaf extracts from two Brassica rapa subspecies on the hyphal growth of two well-known entomopathogenic fungi, Cordyceps fumosorosea and Beauveria bassiana. Extract concentrations of 50, 25, and 10% w/v based on leaf fresh weight were prepared from turnip (B. rapa subspecies rapa) and bok choy (B. rapa subspecies chinensis) leaves. Each concentration was individually incorporated into potato dextrose agar plates for in vitro bioassays. The center of each plate was inoculated with 20 µL of a fungal suspension that was allowed 24 h to soak into the agar before sealing the plates and incubating them at 25 °C under a 14-h photophase. The fungal colony perimeter was marked 5 days after inoculation on two perpendicular lines drawn on the bottom of each plate. Radial colony growth was measured from 4 marks per plate 5, 10, and 15 days later. Radial growth rates for both fungi were 1.3-2.0 and 0.9-1.4 times faster with bok choy and turnip extracts, respectively, at the 25% and 50% concentrations compared to the no-extract control treatment. Therefore, bok choy and turnip leaf extracts can stimulate entomopathogenic fungus growth within 15 days. Biochemical compounds in the extracts include sesquiterpenes, α-copaene, β-selinene, γ-gurjunene, calamenene, cubenene, and α-calacorene.

Preparation of Metal Nitride Particles Using Arc Discharge in Liquid Nitrogen

A simple process to synthesize metal nitride particles was proposed using submerged arc discharge plasma in liquid nitrogen. Gibbs standard free energy was considered for the selection of the nitride-forming materials. In this study, titanium (Ti) and aluminum (Al) electrodes were used as raw materials for nitride particle preparation. Liquid nitrogen acted as a dielectric medium as well as a nitridation source in this process. A copper electrode was also used as a non-reactive material for comparison with the reactive Ti and Al electrodes. As the operating conditions of the experiments, the arc discharge current was varied from 5 A (low-power mode) to 30 A (high-power mode). The formation of titanium nitride (TiN) and aluminum nitride (AlN) was confirmed in the particles prepared in all experimental conditions by X-ray powder diffraction (XRD). The observation using a field emission scanning electron microscope (FE-SEM) and a field emission transmission electron microscope (FE-TEM) indicated that the synthesized TiN particles showed a cubic morphology, whereas AlN particles containing unreacted Al showed a spherical morphology. The experiments using different metal electrode configurations showed that the anode generated most of the particles in this process. Based on the obtained results, a particle formation mechanism was proposed.

Preparation of Fine-Drugs Layered Spherical Particles with Good Micromeritic and Dissolution Properties through Ultra Cryo-Milling and Mechanical Powder Processing

The particles of phenytoin (Phe), a poorly water-soluble model drug, were bead-milled alone or co-milled with a hydrophilic waxy additive using an ultra cryo-milling technique in liquid nitrogen (LN₂) to improve its dissolution properties. However, the micronized drug particles adhered and aggregated, resulting in poor handling in manufacturing processes such as blending or tableting. To improve the dissolution profile and powder properties of the drug simultaneously, the milled products were secondarily processed together with larger spherical particles by mechanical powder processing. These secondary products were composite particles with a core-shell structure, with fine drug particles adhered and deposited on the core, based on order mixing theory. As a core, three types/sizes of spherical pharmaceutical excipient particles were applied. The resultant composite particles produced much faster release profiles than just milled or co-milled mixtures. In addition, the composite particles showed good micromeritic properties depending on the size of the core particles. These results indicate that the ultra cryo-milling and subsequent dry composite mixing is a potential approach for developing drug particles with improved dissolution.

A Multifaceted Approach for Cryogenic Waste Tire Recycling

One of the important aspects for degradation of the life quality is the ever increasing volume and range of industrial wastes. Polymer wastes, such as automotive tire rubber, are a source of long-term environmental pollution. This paper presents an approach to simplifying the rubber waste recycling process using cryogenic temperatures. The temperature of cryogenic treatment is ranged from 77 K to 280 K. Liquid nitrogen was used as a cryoagent for laboratory tests. Experimental and numerical studies have been carried out to determine the optimal conditions for the recycling process. Numerical studies were performed using the COMSOL Multiphysics cross-platform software. The optimal force of mechanical shock for the destruction of a tire which turned into a glassy state after cryoexposure was determined experimentally. The chemical and physical properties of the final product (crumb rubber) have been studied by scanning electron microscopy and energy dispersive X-ray spectroscopy. The analysis shows that the morphology and elemental composition of the samples remain practically unchanged, demonstrating environmental friendliness of the proposed process.

Successful Cryopreservation of Dormant Buds of Blackcurrant (Ribes nigrum L.) by Using Greenhouse-Grown Plants and In Vitro Recovery

The cryopreservation of dormant buds can be a feasible method for preserving germplasm of cold-tolerant woody plants. In the present study, we evaluated the effects of pre-desiccation, thawing method, and the rehydration of bud sections on the post-cryopreservation recovery of dormant blackcurrant buds in vitro. The estimated recovery of small- and medium-sized buds was 80.1 and 62.7% respectively for desiccated buds and 67.8 and 72.3% respectively for non-desiccated buds. The pre-desiccation of bud sections enhanced the number of the shoots regenerated from vegetative buds (2.3 vs. 4.7). The estimated recovery of fast-thawed buds was better after 14-day than after 7-day rehydration (85 vs. 59%). In slowly thawed buds the difference between 14-day and 7-day rehydration was not significant (73 vs. 62%). The estimated recovery of vegetative and flower buds was 77.7 and 41.1% respectively after 7-day rehydration, and 95.2 and 43.6% respectively after a 14-day rehydration period. The rehydration of bud sections was not necessary for the in vitro recovery of non-desiccated, fast-thawed buds. Of the 23 blackcurrant cultivars cryopreserved using non-desiccated dormant buds collected from a greenhouse, the estimated recovery of 22 cultivars ranged between 42 and 90%.

On Coolant Flow Rate-Cutting Speed Trade-Off for Sustainability in Cryogenic Milling of Ti-6Al-4V

Application of cryogenic fluids for efficient heat dissipation is gradually becoming part and parcel of titanium machining. Not much research is done to establish the minimum quantity of a cryogenic fluid required to sustain a machining process with respect to a given material removal rate. This article presents an experimental investigation for quantifying the sustainability of milling a commonly used titanium alloy (Ti–6Al–4V) by varying mass flow rates of two kinds of cryogenic coolants at various levels of cutting speed. The three cooling options tested are dry (no coolant), evaporative cryogenic coolant (liquid nitrogen), and throttle cryogenic coolant (compressed carbon dioxide gas). The milling sustainability is quantified in terms of the following metrics: tool damage, fluid cost, specific cutting energy, work surface roughness, and productivity. Dry milling carried out the at the highest level of cutting speed yielded the worst results regarding tool damage and surface roughness. Likewise, the evaporative coolant applied with the highest flow rate and at the lowest cutting speed was the worst performer with respect to energy consumption. From a holistic perspective, the throttle cryogenic coolant applied at the highest levels of mass flow rate and cutting speed stood out to be the most sustainable option.

Between-the-Holes Cryogenic Cooling of the Tool in Hole-Making of Ti-6Al-4V and CFRP

Lightweight materials are finding plentiful applications in various engineering sectors due to their high strength-to-weight ratios. Hole-making is an inevitable requirement for their structural applications, which is often marred by thermal damages of the drill causing unacceptable shortening of tool life. Efficient cooling of the tool is a prime requirement for enhancing the process viability. The current work presents a novel technique of cooling only the twist drill between drilling of holes with no effect of the applied cryogenic coolant transferred to the work material. The technique is applied in the drilling of two commonly used high-strength lightweight materials: carbon fibers reinforced polymer (CFRP) and an alloy of titanium (Ti-6Al-4V). The efficacy of the cooling approach is compared with those of conventionally applied continuous cryogenic cooling and no-cooling. The effectiveness is quantified in terms of tool wear, thrust force, hole quality, specific cutting energy, productivity, and consumption of the cryogenic fluid. The experimental work leads to a finding that between-the-holes cryogenic cooling possesses a rich potential in curbing tool wear, reducing thrust force and specific energy consumption, and improving hole quality in drilling of CFRP. Regarding the titanium alloy, it yields a much better surface finish and lesser consumption of specific cutting energy.

Construction of Position-Controllable Graphene Bubbles in Liquid Nitrogen with Assistance of Low-Power Laser

Graphene bubbles (GBs) are of significant interest owing to their distinguished electrical, optical, and magnetic properties. GBs can also serve as high-pressure reaction vessels to numerous chemical reactions. However, previous strategies to produce GBs are relatively elaborate and random. Therefore, their potential applications are severely restricted. Here, a facile and effective protocol is proposed to construct position-controllable GBs in liquid nitrogen (LN) with the assistance of laser and graphene wrinkles. Specifically, a film of graphene mounted on a SiO₂ substrate (G@SiO₂) is subjected to irradiation by a low-power laser in LN and then many GBs emerge from the surface of G@SiO₂. Most impressively, the domain where GBs arise is the position of the laser beam spot. Hence, we demonstrated that the high collimation of laser facilitates the position definition of GBs. The microscopic results indicate that some GBs split into three parts when they were subjected to irradiation by an electron. Meanwhile, some GBs degenerate into pores with a diameter of 500 nm when they are exposed to air. To grasp the properties of GBs in depth, the molecular dynamics (MD) simulations are performed, and the corresponding results indicate that temperature has very little impact on the GBs' shape. A phase transition process of the substance inside GBs is also revealed. Moreover, a two-dimensional (2D) solid nitrogen is discovered by MD simulations. The simplicity of our protocol paves the way to engineer high-pressure microreaction vessels and fabricate porous graphene membranes.

Effects of Processing Variables of Extrusion-Pultrusion Method on the Impregnation Quality of Thermoplastic Composite Filaments

Carbon fibre-reinforced polypropylene composite filaments were fabricated via the extrusion–pultrusion method. One of the important factors influencing composites’ filament processability and structural properties is the impregnation quality, which can be represented by interfacial adhesion between the matrix and fibre. To improve the interfacial shear strength (IFSS) of the filament, four processing variables—melt temperature, pulling speed, number of pins in the impregnation die and fibre treatment—have been optimised using the Box–Behnken response surface methodology (RSM). Analysis of variance (ANOVA) was conducted to evaluate the linearity of the response surface models. Three levels were set for each independent variable. The melt temperature was varied at levels 190, 210 and 230 °C, while the pulling speed was set at three levels, namely, 40, 47 and 50 cm/min. The number of spreader pins was varied at 1, 2 and 3 pins, and there were three variations of the fibre treatment, namely, vinyltrimethoxysilane (VTMS), γ-aminopropyltriethoxy silane (APTS) and liquid nitrogen. Twenty-seven experimental runs were conducted, and a significant regression for the coefficient between the variables was obtained. The filament IFSS was measured by a customised pull-out test, and its surface morphology was characterised using a scanning electron microscope. ANOVA showed that fibre treatment significantly affected the IFSS due to their surface roughness, followed by pulling speed and melt temperature in quadratic order. Liquid nitrogen is recommended for carbon fibre treatment because of the high surface roughness, thereby providing a better matrix–fibre bonding effect. The results demonstrated that a melt temperature of 190 °C, pulling speed of 40 cm/min, three spreader pins and treatment of the fibre with liquid nitrogen afforded the optimum impregnation quality. It is important to keep a reasonable low processing temperature to obtain the geometrical stability of the product.

Actual approaches to the transportation of biological samples at low temperatures

Taking into account the impact of shipment method of biosamples is necessary for obtaining high-quality biological samples in biobanking and laboratory research. The impact of liquid nitrogen, dry ice and cold accumulators on the quality of biological markers was considered, as well as recommendations to reduce the impact of these methods of shipment. The liquid nitrogen provides the best preservation of samples, however, dry ice is used much more often during their transportation. When transporting certain types of cells using dry ice, there is the way to use CryoStor CS1 and Cell Banker 1 cryoprotectors. The dry ice has a significant effect on both the pH of liquid biological samples and the coagulological parameters of plasma samples. The penetration of CO2 into the sample leads to changes in the parameters of PTT and APPT, as well as to decrease the protein C and fibrinogen level under certain conditions. Serum and plasma samples exposed to dry ice for more than 16 hours should be thawed open at room temperature, or instead of it should be kept at -80 °C for 24 hours to avoid changes in coagulation parameters, The use of cold accumulators is unacceptable for long-term shipment of serum and plasma containing unstable biomarkers because of insufficiently low temperature (increase over time to -25 °C and above). Besides, metal pellets can be used as cold storage batteries at low temperatures (up to -80 ° C), but they are not as effective as dry ice, since it is able to hold the required temperature for much longer.

Reflectance confocal microscopy in actinic keratosis-Comparison of efficacy between cryotherapy protocols

BACKGROUND

Actinic keratosis (AK) incidence is increasing. Due to the risk of progression to squamous cell carcinoma, early detection and treatment are essential. The method stated in the European Consensus is cryotherapy, but there is no standard protocol defined for better results.

OBJECTIVES

To compare two different cryotherapy protocols for AK using reflectance confocal microscopy (RCM) as a noninvasive imaging method for evaluation.

METHODS

A self-controlled clinical trial was proposed to compare the efficacy of cryotherapy in two different application protocols. Grade II AKs in the forearms were submitted to freezing and thawing time of 10 seconds for 1 cycle (group A) or 2 cycles (group B). At baseline and 4 weeks after treatment, the same dermatologists assessed RCM evaluation (thickness of horny layer, parakeratosis, dyskeratosis, atypia in spinous layer, fibrosis, and presence of inflammatory cells in epidermis and dermis).

RESULTS

We examined 24 AK lesions in each group. Statistical evaluation of the results evidenced superior response after 2 cycles of cryotherapy in parakeratosis and number of inflammatory cells in epidermis.

CONCLUSION

Both protocols are effective in clearing clinical AK. Two cycles are not generating more side effects (fibrosis) and could reduce the risk of recurrence (better "clearance" of parakeratosis).

Different freezing time of superficial liquid nitrogen cryotherapy in treatment of recalcitrant alopecia areata: Randomized clinical trial

Recalcitrant alopecia areata is not uncommon in clinical practice and some patients experienced either treatment failure or recurrence with most of the conventional therapies. Several studies have evaluated the efficacy of cryotherapy in the treatment of alopecia areata with controversial results. This study aimed to optimize the ideal timing of liquid nitrogen cryospraying to achieve the most favorable results. A total of 75 patients with recalcitrant alopecia areata were treated with superficial cryotherapy, two freeze-thaw cycles, each consisted of 3 to 5, 8 to 10, and 13 to 15 seconds in group A, B, and C, respectively. Good to moderate improvement was achieved in 65.2%, 76%, and 76.2% in groups A, B, and C, respectively, with no statistically significant difference. However, the mean percentage of improvement was significantly higher in group B and C compared to group A (P-value < .05 for each). Superficial liquid nitrogen cryotherapy is an effective therapeutic modality for recalcitrant alopecia areata. Moreover, using 8 to 10 seconds dual freeze-thaw cycles is the optimum timing.

Influence of pre-freezing conditions of octacalcium phosphate and collagen composite for reproducible appositional bone formation

Even though conventionally prepared octacalcium phosphate and collagen composite (OCP/Col) has exhibited excellent bone regeneration and has recently been commercialized for treating bone defects, reproducible appositional bone formation with OCP/Col has never been achieved. The present study investigated whether appositional bone formation could be achieved by altering the density of OCP/Col and applying liquid nitrogen during the preparation of OCP/Col. The prepared OCP/Col disks had eight variations and were divided into categories according to four different type of densities (1.0, 1.3, 1.7, and 2.0) of OCP/Col and two different pre‐freezing conditions of gas phase (G group: −80°C) and liquid phase (L group: −196°C). These disks were implanted into subperiosteal pockets in rodent calvaria, five samples per each eight variations. Radiomorphometric analysis was conducted at 4 and 12 weeks after implantation, and histological analysis was conducted at 12 weeks after implantation. OCP/Col samples in the L group tended to retain their height and shape and had enhanced appositional bone formation, whereas OCP/Col samples in the G group tended to lose their height and shape and had limited appositional bone formation. The appositional bone formation increased along with growing density of OCP/Col, and L2.0 demonstrated higher appositional bone formation than other samples. These results suggest that the pre‐freezing conditions and densities of OCP/Col affect the appositional bone formation.

An efficient and high-yielding method for extraction and purification of linamarin from Cassava; in vitro biological evaluation

During the last three decades, studies of linamarin extracted from cassava have received increased attention due to the presence of high cyanogenic compounds in these extracts. The methods that are utilized to isolate linamarin are either tedious or use acidic conditions resulting in poor yields. In this study, a novel cryocooled method of extraction has been developed to isolate linamarin from Cassava root peel. Approximately 18 g of linamarin was isolated from 1 kg of fresh Cassava root peel, which is the highest amount reported to date. Linamarin was fully characterized using NMR, IR and LCMS. The anti-cancer properties of pure linamarin and Cassava crude extract were evaluated by a comprehensive cytotoxic assay, using MCF-7, HepG2, NCI H-292, AN3CA and MRC-5 cell lines. The crude extract showed higher cytotoxicity compared to pure linamarin. The results of the biological evaluation are comparable to other reported studies in the literature.

The effects of soft cryotherapy on conjunctiva and cornea in isolated pig eyes and comparison with standard liquid nitrogen: A pilot ex vivo study

PURPOSE

To evaluate the immediate effects on cornea and conjunctiva of a cryosurgical method based on the application of a dimethyl ether, propane and isobutene solution (DMEPI, Histofreezer^® ), and of Liquid Nitrogen (LN₂ ; Cry-Ac Cryogun^® ).

METHODS

A total of 52 isolated pig eyes were obtained at the slaughterhouse, preserved for less than one hour in Ringer Lactate and divided into four groups. The first group included eyes treated with two applications of DMEPI in the center of the cornea, the second group eyes treated with DMEPI on the third eyelid's conjunctiva, the third group eyes treated with LN₂ on the third eyelid's conjunctiva and the fourth group included eyes treated with LN₂ on the central cornea. Each cryogen application (0.8 cm area) lasted 40 seconds. Each group included one (untreated) control eye. The eyes were submitted for routine histopathological evaluation. Histological alterations were recorded and scored with a semiquantitative scoring system.

RESULTS

No tissue alteration was detected on the conjunctiva, in any of the groups. Treated corneas showed mild to moderate cytoplasmic vacuolization of epithelial cells, shrinkage and hypereosinophilia of small groups of basal epithelial cells and stromal cleft formation.

CONCLUSIONS

Soft cryosurgery caused no severe acute histologically detectable damage to cornea and conjunctiva in isolated pig eyes, and no significant difference was observed when LN₂ and DMEPI treatments were compared. Further in vivo studies should be performed in order to verify possible delayed effects and the clinical efficacy of DMEPI cryosurgery in specific corneal and/or conjunctival diseases.

Efficacy of liquid nitrogen and electrocautery assisted gingival depigmentation in term of patient's perception, histological wound healing - A randomized triple blind clinical trial

BACKGROUND

Hyper-melanin pigmentation of the gingiva (GMP) is one of the imperative contributory factors for smile-sensitive individuals. Numerous gingival depigmentation (GD) procedures have been attempted in the literature to evaluate the clinical outcome mostly. Hence, a randomized clinical-histopathological triple-blinded trial was planned to evaluate the pain experienced by the patient, gingival wound healing, and density of melanocytes following liquid nitrogen-assisted GD (LNAGD) and electrocautery-assisted GD (ECAGD) procedures.

MATERIALS AND METHODS

Thirty-two arches with bilateral physiologic labial/buccal GMP extending from distal aspect tooth #14-24 and #34-44 in 16 healthy individuals were selected and were equally treated with LNAGD and ECAGD techniques. Dummett oral pigmentation index and Hedin melanin index were evaluated at baseline and 3 months' postoperatively (PO). The visual analog scale was utilized for the intensity of pain assessment at baseline (immediately after treatment) and 1st day and 7th day PO. Histological wound healing and density of melanocytes were evaluated using Gal et al.'s wound-healing assessment index and Patsakas et al.'s criterion, at baseline (0), 8, 24, 72, and 96 h; 1st, 2nd, 3rd, and 4th week; and 3 months and at 0 and 3 months' PO, respectively. Statistical analysis was done using one-way ANOVA, post hoc Tukey, unpaired, and paired "t" test.

RESULTS

Both groups showed a statistically significant influence on the parameters evaluated.

CONCLUSION

The LNAGD had a substantial superior result in terms of early wound healing, reduction in density of melanocytes, reduction in pain experienced by the patient, with reduction and delay in the recurrence of GMP.

Cryogenic Aerosol Generation: Airborne Mist Particles Surrounding Liquid Nitrogen

Aerosol mist particles generated near the surface of a liquid nitrogen container were measured and analyzed. The particles present at various distances from the boiling surface of liquid nitrogen were detected using an optical particle counter. In this experiment, 3 micrometer particles exhibited a more than 100-fold increase in concentration due to the liquid nitrogen surface. However, 0.3 micrometer and 10 micrometer particles showed smaller variations (2% to 79%) in their concentrations in the vicinity of liquid nitrogen. The distance from the boiling surface of the liquid nitrogen strongly affected the variations in particle concentration. The variations in aerosol concentrations were significant within 20 cm of the liquid nitrogen surface. These results can be considered as a useful quantitative environmental guideline in cryogenic studies that use liquid nitrogen, and this concept can be applied to cryogenic aerosol mist generation mechanisms.

Assessment of Test Portion Sizes after Sample Comminution with Liquid Nitrogen in an Improved High-Throughput Method for Analysis of Pesticide Residues in Fruits and Vegetables

In this study, sample processing of bulk commodities using an efficient one-step comminution procedure with liquid nitrogen (LN₂) was devised and assessed in the analysis of pesticide residues in fruits and vegetables. LN₂ was added to the fresh samples from a tank by opening a valve, and the standard food chopper was kept in a laboratory hood to reduce safety risks. Test portions of four replicates each of 0.25, 0.5, 1, 2, 5, 10, and 15 g were taken from eight fruits and vegetables (tomato, squash, broccoli, apple, grape, peach, green bean, and cucumber) individually comminuted with LN₂. For comparison without comminution, similar test portions of a reconstituted freeze-dried certified reference material of pesticides in cucumber were also analyzed by the same method. More than 100 pesticides were monitored by both ultra-high-performance liquid chromatography-tandem mass spectrometry (UHPLC-MS/MS) and instrument top sample preparation (ITSP) + fast low-pressure gas chromatography-tandem mass spectrometry (LPGC-MS/MS). A new version of QuEChERS-based sample preparation was followed, in which 5 mL of 4:1 (v/v) acetonitrile/water per gram of sample is used for extraction and 200 μL of initial extract is quickly evaporated, reconstituted in water, and ultracentrifuged for UHPLC-MS/MS analysis. For ITSP+LPGC-MS/MS, another portion of the initial extract undergoes salt-out partitioning with 4:1 (w/w) anhydrous MgSO₄/NaCl and the upper layer extract is transferred to an autosampler vial for automated cleanup and analysis in parallel. Quality control spikes were made during the comminution, extraction, cleanup, and analysis steps to isolate and estimate the individual and overall measurement uncertainties of the approach. The recommended test portion size is 2 g for routine monitoring by this approach, but results demonstrated that subsamples as low as 0.5 g typically gave overall biases and relative standard deviations of <10% for nearly all pesticides, commodities, and methods, which is 3-5% lower than previously evaluated sample processing and analytical methods. This approach can be used to improve data quality, laboratory efficiency, and sample throughput in routine monitoring programs for regulatory, risk assessment, and other purposes.

Using on-demand dry ice production as an alternative cryogenic cold chain for bovine artificial insemination outreach in low-resource settings

Artificial insemination (AI) is widely used in livestock industries to breed for desirable characteristics and increase yields. The standard practice of storing and transporting bovine semen uses liquid nitrogen (LN), a scarce commodity in many regions of the world. This study explored the feasibility of using dry ice, a more readily available alternative. We developed equipment that dispenses dry ice from widely available liquid carbon dioxide (LCO₂) tanks into an easily transportable device. In vivo fertility results with a dry ice cold chain showed no statistical difference to the conventional LN method. In vitro bovine semen analyses also showed that storage under these conditions minimally affects characteristics associated with fertility. A dry ice cold chain system could leverage the global availability of LCO₂ to expand the reach of AI and other cold storage applications of biological materials in low-resource settings.

Vitrified Wharton's jelly tissue as a biomaterial for multiple tissue engineering applications

Wharton's Jelly (WJ) tissue is a promising biomaterial, for tissue engineering applications. However, its preservation over a long period in order to be readily available needs further optimization. A possible solution could be the vitrification and storage of WJ tissue at low temperatures. The aim of this study is to evaluate the effect of low temperature in the WJ tissue, which was stored at -196 °C, either with the vitrification or conventional cryopreservation methods. WJ tissues were isolated from human umbilical cords, cryopreserved with the above methods and remained for 1 year at -196 °C. Histological analysis of tissue's extracellular matrix (ECM), isolation, and characterization of mesenchymal stromal cells (MSCs) were performed. Histological analysis revealed the presence of ECM components such as collagen, sulfated glycosaminoglycans (sGAGs), and the presence of cell nuclei only in vitrified samples. Furthermore, MSCs were isolated and expanded successfully from vitrified WJ tissues, whereas a few viable cells were obtained from conventionally cryopreserved tissues that were not further expanded. In conclusion, this study indicated the proper preservation of vitrified WJ tissues after 1 year of storage, which eventually could be used in tissue engineering and regenerative medicine approaches.

Improving the quality of rooster semen frozen in straws by screening the glycerol concentration and freezing rate

1. This study examined different glycerol concentrations (GC) and freezing rates to improve the quality of rooster spermatozoa frozen in straws, and to determine the effect of varying GC on post-thawed spermatozoa quality, as evaluated by fertility and hatchability.2.The experiment included two tests. In test 1, rooster semen straws containing 2, 4, 6, 8 and 11% glycerol were put in a rack (nine tiers with a 1 cm interval between every two tiers, 1 to 9 cm above liquid nitrogen (LN) source), and gradually frozen. The semen straws located in different tiers experienced different temperatures and freezing rates. The straws were then thawed and live sperm numbers determined. In test 2, rooster semen straws containing 2, 4, 6, 8 and 11% glycerol were put on optimal tiers (identified in test 1) for freezing, and stored at -196°C. Hens were inseminated with the frozen semen (post-thawed and glycerol removed, about 4.0 × 10⁸ sperm per hen), and eggs incubated.3. The numbers of live sperm in the 11% glycerol group was higher than that in 2, 4 or 6% glycerol group (P < 0.05) for the semen straws on tiers 1 to 9, while that on tiers 1 to 5 was lower than that on tier 6 to 8 (P < 0.05). GC, freezing rate and the interaction between GC and freezing rate had a significant effect on live sperm numbers (P < 0.01). The highest fertility was in the 6% glycerol group and occurred on day 5 after insemination. The lowest fertility occurred in the 2% glycerol group on day 10 after insemination.4. The optimal combination was 11% glycerol in straws located 6 cm above the LN surface (on tier 6). The 6% glycerol group achieved the highest fertility (77.6%), which surpassed that reported in recent years.

Nanometer Ammonium Perchlorate and Ammonium Nitrate Prepared with 2D Network Structure via Rapid Freezing Technology

Nanometer (nano) ammonium perchlorate (AP) and ammonium nitrate (AN) were prepared with 2D network structures by the ultra-low temperature spray method. Scanning electron microscopy (SEM), X-ray diffractometry (XRD), differential scanning calorimetry (DSC) and thermogravimetric analysis/infrared spectrometry (TG-IR) were employed to probe the micron structure, crystal phase, and thermal decomposition of nano AP and nano AN. SEM images revealed that the sizes of nano AP and AN were in the nanometer scale (<100 nm) in one dimension. XRD patterns showed that the crystal phases of nano AP and AN were in accordance with those of raw AP and raw AN, respectively. DSC traces indicated that the thermal decomposition process of AP depended on its particle size, while the thermolysis of AN was independent of the particle size of AN. TG-IR analyses illustrated that the decomposition products of nano AP were NO₂, N₂O, HCl and H₂O, with a small amount of NOCl, and the main decomposition products of nano AN were N₂O and H₂O, with a small amount of NH₃. The results of mechanical sensitivity tests indicated that nano AP was more sensitive than raw AP and both nano AN and raw AN were very insensitive to impact and friction stimuli.

Synthesis of High-performance LiNi0.6Co0.2Mn0.2O2 Cathode Material for Lithium-ion Batteries by Using a Four Times Liquid Nitrogen Quenching Method and an Al2O3 Coating Method

Based on the normal co-precipitation method to synthesize LiNi_0.6Co_0.2Mn_0.2O₂ cathode material, we propose a novel approach using a liquid nitrogen quenching method to synthesize Al₂O₃ coated LiNi_0.6Co_0.2Mn_0.2O₂ cathode material. In the whole process, liquid nitrogen was used four times to quench the materials from high temperatures (50 °C, 750 °C, 90 °C, 500 °C) to -196 °C rapidly in four stages. Various characterizations proved that this method could help to improve the electrochemical performance of lithium-ion batteries. Especially at 5 C rate current, after 100 cycles, the specific discharge capacities were 24.5 mAh/g (LNCM 622), 43.8 mAh/g (LNCM 622-LN), and 53.9 mAh/g (LNCM 622-LN@Al₂O₃). Liquid N₂ quenching increased the charge/discharge capacities and the Al₂O₃ layer increased the cycle stability at high current, to finally obtain improved electrochemical properties.

Review of 16 cases of aneurysmal bone cyst in the proximal femur treated by extended curettage and cryosurgery with reconstruction using autogenous nonvascularized fibula graft

BACKGROUND

Aneurysmal bone cyst (ABC) is an aggressive benign lesion that may sometimes be difficult to treat. Lesions that occur in the proximal femur require to be addressed aggressively because of the high rate of local recurrence and the risk of fracture. Few articles report the experience of management of ABC in the proximal femur. This location presents a surgical challenge due to its anatomical and biomechanical peculiarity.

METHODS

We retrospectively reviewed 16 cases with ABC in the proximal femur that were treated in our institution between 2005 and 2014, utilizing extended curettage and liquid nitrogen as adjuvant therapy and reconstruction using nonvascularized autogenous fibular strut graft. The mean follow-up period was 50.5 months. Five cases presented as recurrent cases, while four cases presented with pathological fractures.

RESULTS

The functional score ranged from 70 to 90 on modified Musculoskeletal Tumor Society score with a mean score of 81.25, which is considered to be excellent function. Time for graft incorporation ranged from 10 to 12 weeks. One case got local recurrence, and one case got early surgical site infection.

CONCLUSIONS

Extended curettage and cryotherapy represent a recommended approach for management of ABC in the proximal femur with favorable results.

Cryogenic Sample Processing with Liquid Nitrogen for Effective and Efficient Monitoring of Pesticide Residues in Foods and Feeds

With the monitoring of hundreds of pesticides in food and feed, the comminution step is equally crucial as any other to achieve valid results. However, sample processing is often underestimated in its importance and practical difficulty to produce consistent test portions for analysis. The scientific literature is rife with descriptions of microextraction methods, but ironically, sample comminution is often ignored or dismissed as being prosaic, despite it being the foundation upon which the viability of such techniques relies. Cryogenic sample processing using dry ice (-78 °C) is generally accepted in practice, but studies have not shown it to yield representative test portions of <1 g. Remarkably, liquid nitrogen has rarely been used as a cryogenic agent in pesticide residue analysis, presumably as a result of access, cost, and safety concerns. However, real-world implementation of blending unfrozen bulk food portions with liquid nitrogen (-196 °C) using common food processing devices has demonstrated this approach to be safe, simple, fast, and cost-effective and yield high-quality results for various commodities, including increased stability of labile or volatile analytes. For example, analysis of dithiocarbamates as carbon disulfide has shown a significant increase of thiram recoveries (up to 95%) using liquid nitrogen during sample comminution. This perspective is intended to allay concerns among working laboratories about the practical use of liquid nitrogen for improved sample processing in the routine monitoring of pesticide residues in foods and feeds, which also gives promise for feasible test sample size reduction in high-throughput miniaturized methods.