Ectopic expression of BrIQD35 promotes drought stress tolerance in Nicotiana benthamiana

The plant IQD gene family is responsive to a variety of stresses. In this study, we studied the structural features and functions of the gene BrIQD35 in Chinese cabbage, a member of the IQD gene family. BrIQD35 was cloned and shown to contain an IQ motif. Transient expression of BrIQD35 indicated that it was localized on the plasma membrane and was significantly upregulated under drought and salt stress in Chinese cabbage. To further identify the function of BrIQD35, it was heterologously overexpressed in Nicotiana benthamiana. Although there was no significant difference between BrIQD35-overexpressed and wild-type (WT) plants under salt stress, WT N. benthamiana showed more wilting than the BrIQD35-overexpressed plants under drought stress. Since the IQ motif has been annotated as a CaM binding site, yeast two-hybrid assays were used to explore the interaction between BrIQD35 and CaM. The results indicated that BrIQD35 interacts weakly with CaMb, but not with CaMa, suggesting that BrIQD35 may function through the Ca2+ -CaMb pathway. The findings reveal a novel gene involved in drought tolerance, which is important for plant breeding and quality improvement for Chinese cabbage.

Dielectric barrier discharge-accelerated one-pot synthesis of sulfur quantum dots for fluorescent sensing of lead ions and L-cysteine

Here, we report a novel method for the one-pot facile synthesis of sulfur quantum dots (SQDs) based on a dielectric barrier discharge (DBD)-accelerated H₂O₂ etching strategy within merely 20 min. The formation mechanism of SQDs was investigated, with which an "ON-OFF-ON" fluorescence sensor was developed for the detection of Pb²⁺ ions and L-cysteine.

Novel "Turn-On" Luminescent Chemosensor for Arginine by Using a Lanthanide Metal-Organic Framework Photosensitizer

Arginine is considered as a biomarker of cystinuria and other diseases, and thus, it is of urgency to develop a simple and rapid method with high sensitivity and selectivity for arginine detection to meet the demand of on-site analysis and bedside diagnosis. In this work, a lanthanide metal-organic framework, La(TATB), was prepared using a triazine-based planar ligand, 4,4',4″-s-triazine-2,4,6-triyltribenzoate (H₃TATB), and lanthanide ion (La³⁺). La(TATB) can be used as a highly photosensitive agent to activate molecular oxygen to ¹O₂ to achieve efficient photosensitive oxidation of arginine accompanied by strong blue fluorescence emission under 302 nm UV irradiation. Due to the porous structure and high specific surface area of La(TATB), short-life ¹O₂ can effectively approach and react with amino acid substrate molecules, thus leading to higher sensitivity than other systems. Therefore, the "turn-on" fluorescence sensing of trace arginine can be realized, with a measured linear response range of 10-20,000 nM and a limit of detection as low as 7 nM. This method can be used for the detection of trace arginine in urine, which is conducive to the bedside diagnosis and rapid screening of cystinuria and other diseases. The proposed method not only expands the application scope of Ln-MOFs but also provides a new construction strategy for "turn-on" luminescence sensors.

Biomolecule-guided co-localization of intermolecular G-rich strands for the construction of a tetramolecular G-quadruplex sensing strategy

We herein introduce the principle of proximity assay into tetramolecular G-quadruplexes guided by various biomolecules for the construction of a sensing strategy. Our strategy is based on the co-localization of intermolecular G-rich strands guided by a recognition event of a specific biomolecule to its corresponding affinity ligand. In such case, the local concentration among intermolecular strands is significantly increased to trigger the following self-assembly that served as the peroxidase-mimicking activity. This strategy is versatile, homogenous and adaptable to different types of biomolecules.

Who are the real high-risk patients with pathological T2N0M0 non-small-cell lung cancer that can benefit from adjuvant chemotherapy?

Background

Methods

Results

Conclusions

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ACT could not improve long-term survival in pT2N0M0 NSCLC in general.

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ACT could only improve OS and DFS in pT2N0M0 NSCLC >4 cm.

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ACT could not improve CSS in any subgroup of pT2N0M0 NSCLC.

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For patients with other high-risk factors, ACT failed to improve long-term survival.

[CXCL5 inhibits tumor immune of lung cancer via modulating PD1/PD-L1 signaling]

Objective: To investigate the role of CXCL5 in tumor immune of lung cancer and to explore the potential molecular mechanisms. Methods: A total of 62 cases of patients with lung cancer admitted in the First Affiliated Hospital of Henan University from May 2018 to December 2019 were recruited as study object. Another 20 cases of patients with pulmonary infectious diseases and 20 cases of healthy control were selected as control. Enzyme-linked immunosorbent assay (ELISA) was used to determine serum levels of CXCL5 in patients with lung cancer, pulmonary infectious diseases and healthy control. Immunohistochemical staining (IHC) was used to detect the expressions of CXCL5 and PD-1/PD-L1 in tumor and paracarcinoma tissues of patients with lung cancer. Pearson correlation analysis was used to evaluate the correlation between CXCL5 and PD-1 in tumor and paracarcinoma tissues of patients with lung cancer. Lewis cells either expressing CXCL5 or vector plasmids were used to establish C57BL/6J mice model of lung cancer, and all mice were then divided into vehicle and PD-1 antibody treatment groups, 10 mice for each group. The mice survival and tumor growth curves were recorded. IHC was used to evaluate the expressions of CXCL5, PD-1 as well as the proportions of CD8(+) T and Treg cells in xenograft tumor tissues. Results: In patients with lung cancer, the serum level of CXCL5 [(351.7±51.5) ng/L] was significant higher than that in patients with pulmonary infectious diseases and healthy control [(124.7±23.4) ng/L, P<0.001]. The expression levels of CXCL5 (0.136±0.034), CXCR2 (0.255±0.050), PD-1 (0.054±0.012) and PD-L1 (0.350±0.084) in tumor were significant higher than those in paracarcinoma normal tissues [(0.074±0.022), (0.112±0.023), (0.041±0.007) and (0.270±0.043) respectively, P<0.001]. CXCL5 was significant positively correlated with PD-1 in tumor tissues of lung cancer (r=0.643, P<0.001), but not correlated with PD-1 in paracarcinoma tissues(r=0.088, P=0.496). The vector control group, CXCL5 overexpression group, vector control + anti-PD-1 antibody treatment group and CXCL5 overexpression + anti-PD-1 antibody treatment group all successfully formed tumors in mice, while CXCL5 overexpression increased the tumor growth significantly (P<0.01), which was abrogated by the treatment of anti-PD-1 antibody. CXCL5 overexpression decreased the mice survival time significantly (P<0.01), this effect was also abrogated by the treatment of anti-PD-1 antibody. The proportion of CD8(+) T cells in CXCL5 overexpression group [(10.40±2.00)%] was significant lower than that in vector control group [(21.20±3.30)%, P=0.002]. The proportion of CD4(+) Foxp3(+) Treg cells in CXCL5 overexpression group [(38.40±3.70)%] was significant higher than that in vector control group [(23.30±2.25)%, P<0.001]. After the treatment of anti-PD-1 antibody, no significant difference were observed for the proportion of CD8(+) T cells [(34.10±5.00)% and (33.40±4.00)% respectively] and Treg cells [(14.70±3.50)% and (14.50±3.30)% respectively] in xenograft tumor tissues between CXCL5 overexpression+ anti-PD-1 antibody treatment group and vector control + anti-PD-1 antibody treatment group (P>0.05). Conclusion: The expressions of CXCL5 and PD-1/PD-L1 are all increased significantly in the tumor tissues of patients with lung cancer, CXCL5 may inhibit tumor immune of lung cancer via modulating PD-1/PD-L1 signaling.

Microdischarge in Flame as a Source-in-Source for Boosted Excitation of Optical Emission of Chromium

A compact tandem excitation source-in-source was designed by arranging a point discharge (PD) ignited in argon/hydrogen (Ar/H₂) flame and utilized for boosted excitation for the optical emission of chromium. Through a tungsten coil (W-coil) electrothermal vaporizer (ETV) located right under the tandem source without any interface for sample introduction, a miniaturized optical emission spectrometer was realized. Because the discharge gaseous atmosphere of PD was activated in the flame, the energy consumption of PD for breaking down discharge gas and maintenance of plasma was greatly saved. In addition, the flame could partially atomize or keep the atomized state of analyte atoms through its reducing environment. Therefore, the excitation capability of the tandem source was greatly improved, owing to the synergistic effect of PD microplasma and Ar/H₂ flame. In addition, part of the analyte was atomized/excited on the W-coil, and thereby, dry, pure, and activated analyte species were released from the W-coil and swept into the tandem source for atomization/excitation. Through the collective effect of W-coil ETV, Ar/H₂ flame, and PD microplasma, analytical sensitivity for Cr was greatly enhanced. Under the optimized conditions, with 10 μL sample solution, a limit of detection of 1.5 μg L^-1 and a relative standard deviation of 3.6% (20 μg L^-1, n = 5) were achieved. Its accuracy was demonstrated by successful analysis of several certified reference materials. Owing to the advantages including high sensitivity, compactness, and cost effectiveness, it is promising to facilitate the miniaturized spectrometer for more elements and potential field analytical chemistry.

In situ optical spectroscopy for monitoring plasma-assisted formation of lanthanide metal-organic frameworks

A novel system was designed, which integrated in situ spectral monitoring with facile synthesis of lanthanide metal-organic frameworks in dielectric barrier discharge (DBD) plasma. It features miniaturization, cost-effectiveness and universality, for in situ spectral information of scattering and luminescence to gain insight into the reactive processes.

Exploring Lorentz Invariance Violation from Ultrahigh-Energy γ Rays Observed by LHAASO

Recently, the LHAASO Collaboration published the detection of 12 ultrahigh-energy γ-ray sources above 100 TeV, with the highest energy photon reaching 1.4 PeV. The first detection of PeV γ rays from astrophysical sources may provide a very sensitive probe of the effect of the Lorentz invariance violation (LIV), which results in decay of high-energy γ rays in the superluminal scenario and hence a sharp cutoff of the energy spectrum. Two highest energy sources are studied in this work. No signature of the existence of the LIV is found in their energy spectra, and the lower limits on the LIV energy scale are derived. Our results show that the first-order LIV energy scale should be higher than about 10^{5} times the Planck scale M_{Pl} and that the second-order LIV scale is >10^{-3}M_{Pl}. Both limits improve by at least one order of magnitude the previous results.

Highly sensitive determination of trace antimony in water samples by cobalt ion enhanced photochemical vapor generation coupled with atomic fluorescence spectrometry or ICP-MS

A method for highly sensitive determination of trace antimony was proposed by using cobalt ion enhanced photochemical vapor generation (PCVG) for sample introduction into atomic fluorescence spectrometry (AFS) or inductively coupled plasma-mass spectrometry (ICP-MS) for elemental detection. During the PCVG process, the sample introduction efficiency of Sb could be significantly improved by addition of 5 mg L^-1 Co²⁺ in the mixed acid medium of 10% (v/v) formic acid and 20% (v/v) acetic acid, with a final 12-fold and 133-fold enhancement of AFS and ICP-MS intensity, respectively. The experimental conditions including enhancement ions, acid medium, UV irradiation, working gas as well as potential interference were investigated in detail. Under the optimal experimental conditions, the limit of detection (LOD) for Sb was 0.05 and 0.001 μg L^-1 by using AFS and ICP-MS determination, respectively. The method was successfully used for analysis of real water samples, with satisfactory recoveries of 92-94%.

Sensitive detection of trace 4-methylimidazole utilizing a derivatization reaction-based ratiometric surface-enhanced Raman scattering platform

Herein, a facile and fast surface-enhanced Raman scattering (SERS) method with ratiometric strategy was developed for detection of 4-methylimidazole (4-MI). Via a chemical derivatization reaction with 3-amino-5-mercapto-1,2,4-triazole (AMTA) diazonium salts, 4-MI could be converted to SERS-sensitive species. The SERS intensity ratio between the peaks at 1243 cm^-1 and 1110 cm^-1 (I₁₂₄₃/I₁₁₁₀) was used for the quantification of 4-MI. In addition, the method sensitivity was further improved by the aggregation of beta-cyclodextrin-modified Ag nanoparticles (beta-CD-AgNPs). Under the optimal conditions, the limit of detection (LOD) and the limit of quantification (LOQ) for 4-MI were 1.7 nM (S/N = 3) and 5.7 nM (S/N = 10), respectively. The relative standard deviation (RSD) for 0.5 μM 4-MI was 8.2% (n = 20). This method was successfully used for the determination of 4-MI in cola samples with recoveries ranging from 92% to 106%. The present method is convenient, sensitive, selective, reliable and may have a promising application in determination of the compounds with an imidazole ring containing active hydrogen atoms.

Protein recognition-initiated exponential amplification reaction (PRIEAR) and its application in clinical diagnosis

The isothermal exponential amplification technology have rarely been fabricated as the universal sensing platform for the detection of various proteins. To broaden its application, we here developed a strategy named protein recognition-initiated exponential amplification reaction (PRIEAR) using protein recognition to induce the DNA assembly which converts protein recognition events into ssDNA amplicons and combining two-stage amplification to achieve exponential amplification technology. Taking advantage of this principle, diverse biomarkers can be quantified at sub-picomolar concentrations in the homogenous manner, making the PRIEAR suitable for clinical practice. Therefore, this strategy can expand the powerful isothermal exponential amplification technology to protein targets and thus provide a new toolbox into the clinical and biomedical applications.

Monitoring nucleic acid amplification process by UiO-66-NH2-based fluorescence sensor

Herein, we developed a nucleic acid amplification process monitoring scheme by use of UiO-66-NH2, in which pyrophosphate ion (PPi) released from the amplification can competitively coordinate with Zr to weaken...

Changes in bone mineral density in Down syndrome individuals: a systematic review and meta-analysis

Data evaluating changes in bone mineral density (BMD) in Down syndrome (DS) individuals remains controversial. Therefore, we conducted a systematic review and meta-analysis to better understand associations between BMD and DS. A systematic literature search of PubMed, EMBASE, Web of Science, and the Cochrane Library up until 1st January 2021 was conducted. We used the keywords "bone mineral density" and "Down Syndrome." Fifteen studies were included. Overall, our results showed a significant decrease in BMD of total body (TB BMD) [MD =  - 0.18; 95% CI (- 0.23 and - 0.12), P < 0.00001, I2 = 89%], total hip (TH BMD) [MD =  - 0.12; 95% CI (- 0.15 and - 0.10), P < 0.00001, I2 = 0%], lumbar spine (LS BMD) [MD =  - 0.12; 95% CI (- 0.14 and - 0.09), P < 0.00001, I2 = 18%], and femoral neck (FN BMD) [MD =  - 0.08; 95% CI (- 0.10 and - 0.06), P < 0.00001, I2 = 0%] in DS individuals when compared with controls. Moreover, the volumetric BMD of lumbar spine (LS vBMD) [MD =  - 0.01; 95% CI (- 0.02 and - 0.01), P = 0.0004, I2 = 19%] also showed a decreasing tendency while the volumetric BMD of the femoral neck (FN vBMD) [MD = 0.01; 95% CI (0.00 and 0.02), P = 0.02, I2 = 0%] was elevated in DS individuals versus controls. These findings demonstrated that individuals with DS had a decreased total and regional (TH, LS, and FN) BMD when compared with the general population. Additionally, when BMD was adjusted for skeletal volume, LS vBMD was also lower, while FN vBMD was elevated in DS individuals versus controls.

A water-soluble sensor for distinguishing D2O from H2O by dual-channel absorption/fluorescence ratiometry

A novel D2O optical sensor Cy with integrated great water-solubility, absorption/fluorescence dual-channel ratiometric response and even red-green-blue visual sensing application.

Genetic characterization and clinical characteristics of bovine viral diarrhea viruses in cattle herds of Heilongjiang province, China

BACKGROUND

Heilongjiang province is the main cattle-producing area in China, and molecular epidemiological studies of bovine viral diarrhea viruses (BVDV) in cattle have not been performed in the province.

AIMS

The objective of this research was to determine the genetic and clinical characteristics of BVDV in cattle.

METHODS

Fifty-three BVDV-positive clinical samples were collected from 22 cattle farms in Heilongjiang, and the 5´-untranslated region (5´-UTR) was used to carry out a phylogenetic analysis of the viruses.

RESULTS

The similarity of the 5´-UTR sequences among these BVDVs was 84.2%-100%, and the phylogenetic analysis showed that all viruses belong to the BVDV-1 species, which is classified into five subtypes: BVDV-1b (47.17%, n=25), 1c (15.09%, n=8), 1d (16.98%, n=9), 1 m (3.77%, n=2), and 1o (16.98%, n=9). The statistical results showed that the BVDV-1b subtype had a positive correlation with gastrointestinal disease (P<0.05; 95% CI: 1.19 to 3.34). There were up to three or four BVDV-1 subtypes in some dairy cattle farms, but farms with a single subtype were prevalent (5/10).

CONCLUSION

BVDV-1b is predominant in cattle herds of Heilongjiang province, China, and shows a positive correlation with gastrointestinal disease. BVDV-1o was found for the first time in Chinese cattle, which increased the complex distribution of BVDV-1 subtypes in cattle herds of China.

Simultaneous Detection of Ruthenium and Osmium by Photochemical Vapor Generation-Inductively Coupled Plasma-Mass Spectrometry

Efficient simultaneous photochemical vapor generation (PVG) of ruthenium (Ru) and osmium (Os) in the medium of formic acid was demonstrated. A flow-through photoreactor hyphenated to an inductively coupled plasma-mass spectrometer (ICP-MS) was used for the PVG and subsequent detection of the two elements. A similar synergistic enhancement from cobalt and cadmium ions on the PVG efficiency of both Ru and Os was discovered. Following the critical evaluation of the impacts of various transition metal ions, the concentrations of formic acid, cobalt, and cadmium ions, the flow rate of carrier gas, and the UV irradiation time, impressive limits of detection (LODs) of 5 and 0.5 ng L^-1 were achieved for Ru and Os, respectively. The accuracy of the proposed PVG-ICP-MS method was validated by the analysis of several water samples with desirable spike recoveries obtained. Furthermore, the volatile compounds of Ru were directed and cryogenically trapped in acetonitrile and generation of carbonyls of Ru was verified by high-resolution electrospray ionization-mass spectra (ESI-MS).

Utilizing phenotypic characteristics of metastatic brain tumors to improve the probability of detecting circulating tumor DNA from cerebrospinal fluid in non-small-cell lung cancer patients: development and validation of a prediction model in a prospective cohort study

Background

Circulating tumor DNA (ctDNA) in cerebrospinal fluid (CSF) has become a promising surrogate for genomic profiling of central nervous system tumors. However, suboptimal ctDNA detection rates from CSF limit its clinical utility. Thus precise screening of suitable patients is needed to maximize the clinical benefit.

Patients and methods

Between February 2017 and December 2020, 66 newly diagnosed non-small-cell lung cancer (NSCLC) patients with brain parenchymal metastases were prospectively enrolled as a training cohort and 30 additional patients were enrolled as an external validation cohort. CSF samples and matched primary tumor tissues were collected before treatment and subjected to next-generation sequencing (NGS). The imageological characteristics of patients’ brain tumors were evaluated by radiologists using enhanced magnetic resonance imaging images. The clinical and imageological characteristics were evaluated by complete subsets regression, Akaike information criteria, and Bayesian information criteria methods to establish the prediction model. A nomogram was then built for CSF ctDNA detection prediction.

Results

The somatic mutation detection rate of genes covered by our targeted NGS panel was significantly lower in CSF ctDNA (59.09%) than tumor tissue (91.84%). The T_size (diameter of the largest intracranial lesion) and LVD_min (minimum lesion–ventricle distance for all intracranial lesions) were significantly associated with positive CSF ctDNA detection, and thus, were selected to establish the prediction model, which achieved an area under the ROC curve (AUC) of 0.819 and an accuracy of 0.800. The model’s predictive ability was further validated in the independent external cohort (AUC of 0.772, accuracy of 0.767) and by internal cross-validation. The CSF ctDNA detection rate was significantly improved from 58.18% (32/55) to 81.81% (27/33) in patients after model selection (P = 0.022).

Conclusions

This study developed a regression model to predict the probability of detecting CSF ctDNA using the phenotypic characteristics of metastatic brain lesions in NSCLC patients, thus, maximizing the benefits of CSF liquid biopsies.

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Intracranial tumor size and distance to nearest ventricle were significantly correlated with positive CSF ctDNA detection.

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A prediction model incorporating T_size and LVD_min was developed and validated to evaluate the odds of CSF ctDNA positivity.

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The CSF ctDNA detection rate was significantly improved in patients after model selection.

Three-Dimensional Printed Dual-Mode Chemical Vapor Generation Point Discharge Optical Emission Spectrometer for Field Speciation Analyses of Mercury and Inorganic Selenium

Due to the large size and high energy consumption of instruments, field elemental speciation analysis is still challenging so far. In this work, a portable and compact system device (230 mm length × 38 mm width × 84 mm height) was fabricated by using three-dimensional (3D) printing technology for the field speciation analyses of mercury and inorganic selenium. The device comprises a cold vapor generator, photochemical vapor generator, and miniaturized point discharge optical emission spectrometer (μPD-OES). For mercury, inorganic mercury (IHg) was selectively reduced to Hg⁰ by cold vapor generation, whereas the reductions of both IHg and methylmercury (MeHg) were obtained by photochemical vapor generation (PVG) in the presence of formic acid. For selenium, Se(IV) and total inorganic selenium were converted to their volatile species by PVG in the presence and the absence of nano-TiO₂, respectively. The generated volatile species were consequently detected by μPD-OES. Limits of detection of MeHg, IHg, Se(IV), and Se(VI) were 0.1, 0.1, 5.2, and 3.5 μg L^-1, respectively. Precision expressed as the relative standard deviations (n = 11) were better than 4.5%. The accuracy and practicality of the proposed method were evaluated by the analyses of Certified Reference Materials (DORM-4, DOLT-5, and GBW(E)080395) and several environmental water samples with satisfactory recoveries (95-103%). This work confirms that 3D printing has great potential to fabricate a simple, miniaturized, easy-to-operate, and low gas and power consuming atomic spectrometer for field elemental speciation analysis.

Stimuli-Responsive Three-Dimensional DNA Nanomachines Engineered by Controlling Dynamic Interactions at Biomolecule-Nanoparticle Interfaces

Stimuli-responsive nanomachines are attractive tools for biosensing, imaging, and drug delivery. Herein, we demonstrate that the orientation of macromolecules and subsequent dynamic interactions at the biomolecule-nanoparticle (bio-nano) interfaces can be rationally controlled to engineer stimuli-responsive DNA nanomachines. The success of this design principle was demonstrated by engineering a series of antibody-responsive DNA walkers capable of moving persistently on a three-dimensional track made of DNA functionalized gold nanoparticles. We show that drastically different responses to antibodies could be achieved using DNA walkers of identical sequences but with varying number or sites of modifications. We also show that multiple interfacial factors could be combined to engineer stimuli-responsive DNA nanomachines with high sensitivity and modularity. The potential of our strategy for practical uses was finally demonstrated for the amplified detection of antibodies and small molecules in both buffer and human serum samples. Unlike many DNA-based nanomachines, the performance of which could be significantly hindered by the matrix of serum, our system shows a matrix-enhanced sensitivity as a result of the engineering approach at the bio-nano interface.

Flow injection hydride generation and on-line W-coil trapping for electrothermal vaporization dielectric barrier discharge atomic emission spectrometric determination of trace cadmium

A fast, low-cost and sensitive method for the determination of trace cadmium was developed by using a miniaturized dielectric barrier discharge microplasma atomic emission spectrometer coupled with a tungsten coil (W-coil) for on-line hydride generation trapping-electrothermal vaporization. Total sample throughput can be greatly improved through the adoption of a horizontally fixed W-coil and the flow injection mode. In addition, the horizontally fixed W-coil and an inserted quartz capillary for on-line trapping contributed to stable and good signal even at a high gas flow rate when volatile cadmium species were trapped, and less sample-consuming and time-saving can be realized in this work. Compared to direct injection, the sensitivity and the LOD were improved by 29- and 38-fold, respectively. The proposed method provides a promising approach to develop a miniaturized instrumentation for highly sensitive detection of trace elements.

Photochemical Vapor Generation of Halides in Organic-Acid-Free Media: Mechanism Study and Analysis of Water Samples

Herein, we report a discovery that photochemical vapor generation (PCVG) of halides (bromide, chloride, and fluoride) can be realized in organic-acid-free media, with figures of merit comparable to those in classical scenarios employing acetic acid. Metal acetates, copper salts, and mixtures of different acetates and copper salts were evaluated for their performance in facilitating PCVG of halides; the formation of copper acetate complexes turned out to play a crucial role. Methyl halides (CH₃X, X = Br, Cl, F) were identified by gas chromatography-mass spectrometry (GC-MS) as principal volatile compounds. Several important intermediate species, including cuprous ions (Cu⁺), methyl (^•CH₃), and hydroxyl (^•OH) free radicals, were confirmed using cuproine, 2,2,6,6-tetramethylpiperidin-1-oxyl (TEMPO), and coumarin as a chromogenic agent, radical tracer, and fluorescence probe based on UV-vis, GC-MS, and fluorescence spectroscopy, respectively. The ligand to metal charge transfer (LMCT) between acetate and copper and the charge transfer to solvent (CTTS) excitation of halides were considered to account for the generation of methyl halides in organic-acid-free media. The presence of 100 and 200 μg mL^-1 of CuAc₂, as well as sample delivery rates of 10.7 and 3.3 mL min^-1, yielded limits of detection of 0.03 and 3 μg L^-1 for Br^- and Cl^-, respectively, by inductively coupled plasma mass spectrometry (ICPMS). The method was applied to the analysis of bottled water and seawater, achieving spike recoveries between 92 and 101%.

Expression Level and Clinical Significance of Inflammatory Cytokines and Biochemical Markers in Gingival Crevicular Fluid During Different Crown Adhesion Patterns of Dental Implant

Objective

The aim of this study was to investigate the expression level and clinical significance of inflammatory factors and biochemical markers in gingival crevicular fluid during different crown-binding styles in dental implant patients.

Methods

A total of 38 patients with posterior tooth loss and implant repair were recruited and divided into two groups according to the different ways of crown bonding, including 19 prostheses (19 patients) in the adhesive retainer group and 19 prostheses (19 patients) in the modified adhesive retainer group. Moreover, the peri-implant gingival sulcus fluids of each group of patients were collected at 7, 15, 30, 60, and 90 d of post-treatment, and the expression level of each cytokine as well as biochemical marker were analyzed by enzyme-linked adsorption method, respectively.

Results

Compared with the control group, the peri-implant plaque index and gingival bleeding index were decreased in the observation group. In addition, the secretion of peri-implant gingival crevicular fluid in the observation group was significantly higher than that of the control group. The level of IL-6, TNF-α expressions in peri-implant gingival crevicular fluid were gradually decreased with follow-up time, and the rate of decline gets slow at 15 h after operation. The TGFα in peri-implant gingival crevicular fluid in the two groups began to increase at 7 d, reached a peak at about 15 d, then slowly decreased and stabilized after 60 d. While the OCN was gradually increased during the whole detection process, slowly released before 30 d, then increasingly released and maintained at a peak state after 60 d. All the above differences were statistically significant (P < 0.05).

Conclusion

Different crown-binding patterns of implant teeth have a significant effect on the secretion amount of peri-implant gingival crevicular fluid and the expression level of inflammatory cytokines as well as biochemical markers.

Miniaturized TOC analyzer using dielectric barrier discharge for catalytic oxidation vapor generation and point discharge optical emission spectrometry

Total organic carbon (TOC) is an important parameter describing organic pollution degree of waters. Due to the increasing need of field analysis and drawbacks of conventional TOC analytical instruments, miniaturized TOC analyzers are still demanding. In this work, a dielectric barrier discharge (DBD) microplasma was utilized for catalytic oxidation vapor generation (COVG) of organic compounds into CO₂, and a point discharge (PD) microplasma was employed to excite the carbon atomic emission spectra for quantification. Sample solution with phosphoric acid and persulfate solution was injected into the DBD-COVG reactor by a syringe to convert organic compounds into CO₂ efficiently and quickly, which was subsequently transported into the point discharge optical emission spectrometer (PD-OES) for detecting carbon at 193.09 nm. Under optimal experimental conditions, high oxidation efficiencies for several organic compounds were achieved, i.e., 96.4%, 95.1% and 94.3% for 50 mg L^-1 potassium hydrogen phthalate (KHP), sodium laurylsulfonate and phenol, respectively. A limit of detection (LOD) of 0.02 mg L^-1 (as C) was obtained, with a precision of 3.9% (relative standard deviation, RSD) at 15 mg L^-1 TOC standard (as C). The possible catalytic oxidation mechanism was proposed with the characteristic results of electron paramagnetic resonance (EPR). Its potential environmental application was demonstrated by successfully analyzing TOC in underground water, surface river water and surface sedimentary water samples from oil fields, with analytical results agreed well with those obtained by the commercial high-temperature combustion coupled nondispersive infrared absorption (HTC-NDIR) technique.

Peta-electron volt gamma-ray emission from the Crab Nebula

The Crab Nebula is a bright source of gamma rays powered by the Crab Pulsar's rotational energy through the formation and termination of a relativistic electron-positron wind. We report the detection of gamma rays from this source with energies from 5 × 10^-4 to 1.1 peta-electron volts with a spectrum showing gradual steepening over three energy decades. The ultrahigh-energy photons imply the presence of a peta-electron volt electron accelerator (a pevatron) in the nebula, with an acceleration rate exceeding 15% of the theoretical limit. We constrain the pevatron's size between 0.025 and 0.1 parsecs and the magnetic field to ≈110 microgauss. The production rate of peta-electron volt electrons, 2.5 × 10³⁶ ergs per second, constitutes 0.5% of the pulsar spin-down luminosity, although we cannot exclude a contribution of peta-electron volt protons to the production of the highest-energy gamma rays.

Prevalence of overweight and obesity in children and adolescents with intellectual disabilities in China

BACKGROUND

Overweight and obesity in children and adolescents has become a worldwide epidemic. There are several studies that have concentrated on the prevalence rate of children and adolescents with intellectual disabilities (ID), whereas data on such a population on the mainland of China remain unclear. The purpose of this study was to investigate the prevalence rate of overweight and obesity among school-aged children and adolescents with ID on China's mainland.

METHODS

This study employed a cross-sectional design to examine the body weight status of 1873 children and adolescents (ages 6-18 years old) with ID in 35 special education schools. Body mass index was calculated, and the concepts of overweight and obesity were defined according to the standard of the Working Group for Obesity in China.

RESULTS

Data indicated that 18.2% (95% CI: 16.5%-20.0%) of children and adolescents with ID were overweight and 14.4% (95% CI: 12.8%-16.0%) were obese. Boys with ID were more likely to be overweight than girls with ID (OR = 1.48[95% CI: 1.13-1.94], P < 0.05). Children and adolescents with Down syndrome or autism spectrum disorder had a trend to be classified as overweight (OR = 1.76[95% CI: 1.22-2.54], P < 0.05; OR = 1.57[95% CI: 1.17-2.09], P < 0.05, respectively) or obesity (OR = 1.82[95% CI: 1.23-2.69], P < 0.05; OR = 1.40 [95% CI: 1.02-1.93], P < 0.05, respectively) compared with those with ID without these conditions. Moreover, children and teenagers with ID living in urban areas had a predisposition to be overweight (OR = 2.16[95% CI: 1.14-4.09], P < 0.05) or obese (OR = 3.25[95% CI: 1.41-7.50], P < 0.05) relative to those who lived in rural areas.

CONCLUSION

Results indicated that in China, the prevalence rate of overweight and obesity among school-aged children and adolescents with ID was remarkably high. Therefore, future research should make every effort to focus on reducing and preventing overweight and obesity of this population in China.

Extended Very-High-Energy Gamma-Ray Emission Surrounding PSR J0622+3749 Observed by LHAASO-KM2A

We report the discovery of an extended very-high-energy (VHE) gamma-ray source around the location of the middle-aged (207.8 kyr) pulsar PSR J0622+3749 with the Large High-Altitude Air Shower Observatory (LHAASO). The source is detected with a significance of 8.2σ for E>25  TeV assuming a Gaussian template. The best-fit location is (right ascension, declination) =(95.47°±0.11°,37.92°±0.09°), and the extension is 0.40°±0.07°. The energy spectrum can be described by a power-law spectrum with an index of -2.92±0.17_{stat}±0.02_{sys}. No clear extended multiwavelength counterpart of the LHAASO source has been found from the radio to sub-TeV bands. The LHAASO observations are consistent with the scenario that VHE electrons escaped from the pulsar, diffused in the interstellar medium, and scattered the interstellar radiation field. If interpreted as the pulsar halo scenario, the diffusion coefficient, inferred for electrons with median energies of ∼160  TeV, is consistent with those obtained from the extended halos around Geminga and Monogem and much smaller than that derived from cosmic ray secondaries. The LHAASO discovery of this source thus likely enriches the class of so-called pulsar halos and confirms that high-energy particles generally diffuse very slowly in the disturbed medium around pulsars.

Methanol-Enhanced Liquid Electrode Discharge Microplasma-Induced Vapor Generation of Hg, Cd, and Zn: The Possible Mechanism and Its Application

Despite increased interest in microplasma-induced vapor generation (μPIVG) over the past several years, applications in real sample analyses remain limited due to their relatively low vapor generation efficiency and ambiguous mechanism. In this work, a novel method using methanol for significantly enhancing the liquid electrode discharge μPIVG efficiency was developed for the simultaneous and sensitive determination of Hg, Cd, and Zn by atomic fluorescence spectrometry (AFS). It is worth noting that the possible enhancement mechanism was investigated via the characterizations of volatile products by AFS, microplasma optical emission spectrometry, online gas chromatography, and gas chromatography-mass spectrometry, which involved the reductive species such as electrons, hydrogen radicals (·H), methyl radicals (·CH₃), and other intermediates in the argon plasma adding methanol. Under the optimized conditions, the limits of detection of 0.007, 0.05, and 0.5 μg L^-1 were obtained for Hg, Cd, and Zn, respectively, with relative standard deviations of 3.1, 3.7, and 5.2% for these elements, respectively. Vapor generation efficiencies of 90, 83, and 55% were achieved for Hg, Cd, and Zn, respectively, and improved 2.7-, 4.8-, and 7.9-fold, respectively, compared to those obtained in the absence of methanol. The accuracy and practicability of the proposed method were validated by the determination of Hg, Cd, and Zn in a certified reference material (CRM, Lobster hepatopancreas, TORT-3) and crayfish samples collected from three different provinces of China.

Microplasma-induced vapor generation for rapid, sample preparation-free screening of mercury in fruits and vegetables

A method for the rapid screening of toxic elements in fruits and vegetables is of significant importance to prevent human exposure to these elements. In this work, a simple method used for microplasma-induced vapor generation (μPIVG) was developed for the rapid screening and quantification of mercury in fruits and vegetables without sample preparation. A stainless-steel capillary was partly inserted into a juice droplet from the tested fruits and then the sample liquid automatically moved to the end of the capillary with the assistance of inherent capillary driving force. Subsequently, a high voltage was applied between the capillary and a tungsten electrode to generate microplasma wherein the juice was sprayed and the mercury ions contained in the juice were converted to mercury cold vapor (Hg0). The Hg0 was finally separated from the liquid phase and swept to an atomic fluorescence spectrometer (AFS) for rapid screening. A standard addition method coupled with μPIVG atomic fluorescence spectrometry was further used for the quantitative analysis of the suspected sample. Under the optimized conditions, the limits of detection (LODs) of 0.3, 0.5, and 0.4 μg L-1 were obtained for the tested tomato, lemon, and orange samples, respectively. The proposed technique provides a simple and cost-effective tool for the rapid screening of mercury in fruits and vegetables by atomic spectrometry.

A signal conversion system using binding-induced strand displacement for disease biomarker assay

Using the principle of binding-induced DNA strand displacement (BINSD), a DNAzyme-powered nanomachine biosensor for multiple biomarkers via magnetic beads-based signal conversion was designed. This sensor can convert multiple biomarker recognition into release of predesigned output nucleic acids tagged with streptavidin proteins (SA-DNA) for activation of DNA nanomachines. In general, we adopted complementary base pairing rules and affinity ligand specific recognition, and three types of signal conversion systems were constructed that realized universal, sensitive, accurate, and specific detection of multiple biomarkers. Taking the advantage of the strong anti-interference capability of magnetic separation, this strategy could be used for detection of various biomarkers in clinical practice.

AB0066 MECHANISMS OF TOTAL SAPONINS OF PANAX JAPONICUS MITIGATES COLLAGEN-INDUCED ARTHRITIS

Background:

Total saponins of Panax japonicus (TSPJ) are extracted from Panax japonicus (T.Nees) C.A.Mey and have achieved a good therapeutic effect in the treatment of rheumatoid arthritis (RA). Unfortunately, the mechanism of TSPJ acting on RA is not clear.

Objectives:

To investigate the potential mechanisms and key targets of TSPJ on RA.

Methods:

The raw data were downloaded from the Gene Expression Omnibus (GEO) database, and the RStudio3.6.1 software was used to identify differentially expressed genes (DEGs). The potential targets of active compounds from TSPJ were predicted by the Pharmmapper and SwissTargetPrediction databases. Based on the overlapping genes, we used Cytoscape 3.7.2 software to construct a protein-protein interactions (PPI) network and to determine the mechanisms of the treatment by Kyoto Encyclopedia of Genes and Genomes (KEGG) analysis. Collagen-induced arthritis (CIA) model was established and treated with different doses of TSPJ. Arthritis index (AI) and histology score were used to evaluate the symptoms of CIA. The levels of vascular endothelial growth factor (VEGF), hypoxia-inducible factor 1 (HIF-1), IL-1β, and IL-17A tested by enzyme linked immunosorbent assay and real time-quantitative Polymerase Chain Reaction.

Results:

A total of 2670 DEGs and 371 TSPJ targets were obtained, including 52 overlapping genes. 41 genes had protein interactions that are used to build the PPI network. The results of the KEGG enrichment analysis included VEGF and HIF-1 signaling pathway. Seven negative correlation genes and 16 positive correlation genes were obtained by correlational analysis of DEGs in VEGF and HIF-1 signaling pathway. SRC proto-oncogene, nonreceptor tyrosine kinase (SRC), and the signal transducer and the activator of transcription 3 (STAT 3) had a higher value of degree in PPI and showed a significant correlation in the pathways; they were regarded as key targets. Compared with the CIA model group, TSPJ significantly decreased the AI and histology scores. Moreover, the expression of VEGF-A, HIF-1α, IL-1β, and IL-17A in serum or spleens significantly reduced in a dose-dependent.

Conclusion:

Present study show that SRC and STAT 3 may be the key targets of TSPJ acting on the VEGF and HIF-1 signaling pathways, thus inhibiting angiogenesis and improving RA.

Disclosure of Interests:

None declared

Ultrahigh-energy photons up to 1.4 petaelectronvolts from 12 γ-ray Galactic sources

The extension of the cosmic-ray spectrum beyond 1 petaelectronvolt (PeV; 10¹⁵ electronvolts) indicates the existence of the so-called PeVatrons-cosmic-ray factories that accelerate particles to PeV energies. We need to locate and identify such objects to find the origin of Galactic cosmic rays¹. The principal signature of both electron and proton PeVatrons is ultrahigh-energy (exceeding 100 TeV) γ radiation. Evidence of the presence of a proton PeVatron has been found in the Galactic Centre, according to the detection of a hard-spectrum radiation extending to 0.04 PeV (ref. ²). Although γ-rays with energies slightly higher than 0.1 PeV have been reported from a few objects in the Galactic plane^3-6, unbiased identification and in-depth exploration of PeVatrons requires detection of γ-rays with energies well above 0.1 PeV. Here we report the detection of more than 530 photons at energies above 100 teraelectronvolts and up to 1.4 PeV from 12 ultrahigh-energy γ-ray sources with a statistical significance greater than seven standard deviations. Despite having several potential counterparts in their proximity, including pulsar wind nebulae, supernova remnants and star-forming regions, the PeVatrons responsible for the ultrahigh-energy γ-rays have not yet been firmly localized and identified (except for the Crab Nebula), leaving open the origin of these extreme accelerators.

Visual detection of S2- with a paper-based fluorescence sensor coated with CdTe quantum dots via headspace sampling

A simple method was developed in this work for facile and visual detection of S^2- using a paper-based fluorescence (FL) sensor coated with CdTe quantum dots (QDs) by headspace sampling. With the addition of hydrochloric acid, the target S^2- in the liquid phase would transform to H₂ S, which was released to headspace and quenched the FL of CdTe QDs in a linear manner through a gas-solid reaction, with any possible liquid-phase interference avoided. The regular quenching caused by S^2- in analyte solution with increased concentration could be easily observed by the naked eye, and the limit of detection (LOD) for this method was 0.13 μM and 0.93 μM for FL and visual sensing, respectively, comparable or not to that by other sensing probes. A relative standard deviation of 1.2% was accomplished from seven replicated measurements, implying the high reproducibility, and the recovery for the spiked water samples ranging from 94 to 103%, and illustrating the satisfactory reliability of this method. Moreover, the preparation of this paper sensor was facile and did not require any complicated or time-consuming procedures for additional modification or functionalization as for other probes previously reported.

Activation of catalytic DNAzyme by binding-induced DNA displacement for homogeneous assay

The sensitive assays for protein, especially for the DNA-based assay, are often dependent on the amplification procedure with assistance of enzyme. Compared with a protein enzyme, deoxyribozyme (DNAzyme) exhibits similar catalytic activity and specificity and better flexibility. In this work, we streamlined the binding induced DNA displacement (BINDD) strategy for the activation of DNAzyme cleavage. Since the intrinsic element of DNAzyme is the nucleic acids, it is easy to join the BINDD by hybridization with an affinity probe. The activity of DNAzyme was initiated by the BINDD reaction mediated by the recognition affinity probe with target proteins. Upon DNAzyme release, it was able to catalyze and cleave the predesigned substrates, generating the enhanced fluorescence signal indicating the protein concentration. Such a constructed homogeneous assay is available and effective in human serum when it was used for detection of platelet derived growth factor-BB (PDGF-BB) and prostate specific antigen (PSA), with detection limits of 100 pM and 200 pM, respectively.

A facile photochemical strategy for the synthesis of high-performance amorphous MoS2 nanoparticles

It is difficult to avoid the formation of polysulfides by traditional chemical methods, and the synthesis of high purity amorphous MoS₂ nanomaterials under ambient conditions is still a challenging task. Here we present a new and facile photochemical strategy for the synthesis of amorphous MoS₂ nanomaterials, which is achieved by irradiating a mixed solution containing ammonium molybdate, formic acid and sodium sulfide simply with a Xe lamp for 3 min. The mechanism study reveals that the key step in this synthesis is the photolysis of formic acid to produce free radicals which can rapidly reduce Mo⁶⁺ to Mo⁴⁺, which then combines with S^2- to form MoS₂ and inhibits the formation of S-S^2- by preventing S^2- from participating in the reduction reaction. In addition, the results of a series of experiments indicate that the as-prepared amorphous MoS₂ features a small particle size, uniform morphology and relatively large specific surface area, and shows excellent performance in the removal of inorganic heavy metal ions (mercury, lead and cadmium ions) and organic pollutants (rhodamine B and tetracycline), catalase catalysis and a lithium battery anode, showing its great potential and broad application prospects in the fields of environmental remediation, clean energy and green catalysis.

Headspace Solid-Phase Microextraction Following Chemical Vapor Generation for Ultrasensitive, Matrix Effect-Free Detection of Nitrite by Microplasma Optical Emission Spectrometry

A new chemical vapor generation method coupled with headspace solid-phase microextraction miniaturized point discharge optical emission spectrometry (HS-SPME-μPD-OES) for the sensitive and matrix effect-free detection of nitrite in complex samples is described. In an acidic medium, the volatile cyclohexene was generated from cyclamate in the presence of nitrite, which was volatilized to the headspace of the container, efficiently separated, and preconcentrated by HS-SPME. Consequently, the SPME fiber was transferred to a laboratory-constructed thermal desorption chamber wherein the cyclohexene was thermally desorbed and swept into μPD-OES for its sensitive quantification via monitoring the carbon atomic emission line at 193.0 nm. As a result, the quantification of nitrite was accomplished through the determination of cyclohexene. The application of HS-SPME as a sampling technique not only simplifies the experimental setup of μPD-OES but it also preconcentrates and separates cyclohexene from N₂ and sample matrices, thus eliminating the interference from water vapor and N₂ and significantly improving the analytical performance on the determination of nitrite. Under the optimum experimental conditions, a limit of detection of 0.1 μg L^-1 was obtained, which is much better than that obtained by conventional methods. The precision, expressed as relative standard deviation, was better than 3.0% at a concentration of 10 μg L^-1. The proposed method provides several advantages of portability, simplicity, high sensitivity, and low energy consumption and eliminates expensive instruments and matrix interference, thus retaining a promising potential for the rapid, sensitive, and field analysis of nitrite in various samples.

MnFe2O4 micromotors enhanced field digestion and solid phase extraction for on-site determination of arsenic in rice and water

Despite the increased interest and great progress obtained on arsenic test, it is still a challenge to accomplish the on-site determination of arsenic in rice due to the expensive instrumentation and harsh digestion process. In this work, MnFe₂O₄ micromotors were found to retain high catalytic activity to simultaneously produce large amounts of hydroxyl radicals and O₂ bubbles in the presence of H₂O₂. Interestingly, the generated bubbles autonomously propel the micromotors and prevent them from depositing, thus keeping their high catalytic activity. As a result, a MnFe₂O₄ micromotors enhanced digestion method was developed for the field digestion of rice samples within 100 min only using H₂O₂, which was further utilized to realize the on-site detection of arsenic in rice by coupling with the Gutzeit method followed headspace solid phase extraction. A quantification limit of 40 μg kg^-1 was obtained for the determination of arsenic in rice. Owing to their capabilities of the efficient and rapid adsorption of arsenic and continuous movement, a MnFe₂O₄ micromotors enhanced solid phase extraction was also established for the sensitive determination of arsenic in water with a 1 μg L^-1 of quantification limit. The accuracy of the developed method was validated via analysis of a Certified Reference Material of rice (GBW10043) and a series of rice and water samples with satisfactory results, showing promising potential in the sensitive on-site detection of arsenic in rice and water samples.

Recombinase Polymerase Amplification Coupled with a Photosensitization Colorimetric Assay for Fast Salmonella spp. Testing

Salmonella spp. is one of the most serious foodborne pathogens causing millions of infection cases annually, especially in resource-limited areas. The standard culture method (2-3 days) and current nucleic acid amplification-based testing are not suitable for on-site testing in rural areas with heavy Salmonella spp. burden. Here, we developed a colorimetric recombinase polymerase amplification (RPA) method for fast and sensitive Salmonella spp. testing in 1 h. Specifically, the invA gene from the genomic DNA of Salmonella spp. was amplified isothermally to produce double-stranded DNA (dsDNA) amplicons, which were directly quantified by a photosensitization colorimetric assay. The proposed method offered the lowest detectable concentration of 5 × 10³ colony-forming units/mL (cfu/mL), which is much lower than that of ELISA (10⁵-10⁷ cfu/mL). The detectable limit could be further pushed down to 3 cfu/mL upon coupling with bacteria pre-enrichment for 6 h. Analysis of synthetic milk samples confirmed the high precision (90%) and specificity (95%) of the method for Salmonella spp. testing. Moreover, use of a DNA releaser could further simplify the whole testing operation. Because RPA features low-temperature amplification (25-42 °C) without the need for specific instruments and the dsDNA-based photosensitization colorimetric assay served as a simple and facile readout for RPA, our method thus allows fast and low-cost Salmonella spp. testing in food samples.