Determination of Ginsenosides (Ginseng Saponins) in Dry Root Powder from Panax ginseng, Panax quinquefolius, and Selected Commercial Products by Liquid Chromatography: Interlaboratory Study

Twelve collaborating laboratories assayed 4 products, namely, Panax ginseng, Panax quinquefolius, and 2 ginseng products, for 6 ginsenosides: Rb1, Rb2, Rc, Rd, Re, andRg1. Collaborators also received a negative control for the recovery study. Pure ginsenosides were provided as reference standards for the liquid chromatography (LC) analysis and the system suitability tests. The LC analyses were performed on the methanol extract using UV detection at 203 nm. For P. ginseng, individual ginsenosides were consistent in their means; repeatability standard deviations (RSDr)rangedfrom4.17to5.09% and reproducibility standard deviations (RSDR) ranged from 7.27 to 11.3%. For P. quinquefolius, the Rb1 and Rb2 ginsenosides were higher and lower in concentration than P. ginseng, with RSDr values of 3.44 and 6.60% and RSDR values of 5.91 and 12.6% respectively, and other analytes at intermediate precisions. For ginseng commercial products, RSDr values ranged from 3.39 to 8.12%, andRSDR values ranged from 7.65 to 16.5%. A recovery study was also conducted for 3 ginsenosides: Rg1, Re, andRb1. The average recoveries were 99.9, 96.2, and 92.3%, respectively. The method is not applicable for the determination of Rg1 and Re in ginseng product at levels <300 mg/kg.

[Prevalence and risk factors of Blastocystis hominis infection in inpatients in Jiangjin District, Chongqing City]

OBJECTIVE

To understand the prevalence and risk factors of Blastocystis hominis infection in inpatients in Jiangjin District, Chongqing City.

METHODS

A cross-sectional study was conducted in a community hospital in Jiangjin District, Chongqing City, and the inpatients were surveyed by questionnaires. After obtaining the informed consent from the inpatients or legal guardians, the stool and blood samples were collected and examined by microscopy and PCR from April 17 to May 1, 2018. The univariate analysis and logistic regression analysis were used to analyze the risk factors of the B. hominis infection.

RESULTS

A total of 198 hospitalized patients were investigated, and the infection rate of B. hominis was 10.61% (21/198), and the infection rate of the females (12.10%) was higher than that of the males (8.11%), but the difference was not statistically significant. The highest rate of infection was 19.23% in the age group of 10 to 20 years, followed by 17.74% in the age group of 60 years and above, and the lowest rate was 2.38% in the age group of 20 to 40 years. The difference in infection rates of B. hominis among the different age groups was statistically significant (P < 0.05). The infection rate of B. hominis in the people who used dry pail latrines was 33.30%, which was higher than that of the people who used water flush toilets (9.10%) (P < 0.05). The genotypes of B. hominis were ST1, ST3, ST6 and ST7, and ST6 and ST3 being the most predominant genotypes which accounted for 47.62% (10/21) and 38.10% (8/21) respectively, and among the infected males, the genotypes were only ST3 and ST6. The multiple logistic regression analysis showed that among the factors affecting B. hominis infection, only keeping pets was a risk factor [OR = 3.798, 95% CI (1.245, 11.581), P < 0.05].

CONCLUSIONS

A high prevalence of B. hominis infection is found in the inpatients in Jiangjin District, Chongqing City, the predominant genotypes are ST6 and ST3, and keeping pets may be one of the main risk factors.

[Epidemiological characteristics and risk factors of Blastocystis hominis infection among patients with HIV/AIDS in Fuyang City Anhui Province]

OBJECTIVE

To investigate the prevalence and risk factors of Blastocystis hominis infections among patients with HIV/AIDS in Fuyang City, Anhui Province.

METHODS

A cross-sectional study was conducted in Fuyang City, Anhui Province in 2016. The demographic and socioeconomic status, and the lifestyle and production style were collected using a questionnaire survey. B. hominis DNA was detected in subjects'stool samples using a PCR assay, and the CD4+ T lymphocyte count and HIV viral load were measured in the subjects' blood samples. The risk factors of B. hominis infections among patients with HIV/AIDS were identified using univariate and multivariate logistic regression analyses.

RESULTS

A total of 398 HIV/AIDS patients were enrolled in this study, with a mean age of 49.3 years, a mean body weight of 55.9 kg and a mean height of 164.4 cm. The prevalence of B. hominis infection was 6.78% in the study subjects, and no gender- (χ² = 1.589, P = 0.207), education level- (χ² =0.508, P = 0.776), marital status- (χ² = 0.419, P = 0.811) or occupation-specific prevalence (χ² = 2.744, P = 0.615) was detected. Among the patients with HIV/AIDS, there were no significant differences in the age (t = 0.370, P = 0.712), height (t = 1.587, P =0.113), body weight (t = 0.516, P = 0.606), CD4⁺ T lymphocyte count (t = 1.187, P = 0.230) or HIV viral load (t = 0.193, P =0.496) between B. hominis-infected and uninfected individuals. Dinking non-tap water [OR = 6.554, 95% CI: (1.876 to 22.903)] and keeping dogs [OR = 5.895, 95% CI: (2.017 to 17.225)] were identified as risk factors for B. hominis infection in patients with HIV/AIDS.

CONCLUSIONS

The prevalence of B. hominis infection is high in HIV/AIDS patients, and drinking non-tap water and keeping dogs are risk factors for B. hominis infection among HIV/AIDS patients.

Investigation of the Mechanism for Ohmic Contact Formation in Ti/Al/Ni/Au Contacts to β-Ga2O3 Nanobelt Field-Effect Transistors

The issue of contacts between the electrode and channel layer is crucial for wide-bandgap semiconductors, especially the β-Ga₂O₃ due to its ultra-large bandgap (4.6-4.9 eV). It affects the device performance greatly and thus needs special attention. In this work, the high-performance β-Ga₂O₃ nanobelt field-effect transistors with Ohmic contact between multilayer metal stack Ti/Al/Ni/Au (30/120/50/50 nm) and unintentionally doped β-Ga₂O₃ channel substrate have been fabricated. The formation mechanism of Ohmic contacts to β-Ga₂O₃ under different annealing temperatures in an N₂ ambient is systematically investigated by X-ray photoelectron spectroscopy. It is revealed that the oxygen vacancies at the interface of β-Ga₂O₃/intermetallic compounds formed during rapid thermal annealing are believed to induce the good Ohmic contacts with low resistance. The contact resistance (R_c) between electrodes and unintentionally doped β-Ga₂O₃ reduces to ∼9.3 Ω mm after annealing. This work points to the importance of contact engineering for future improved β-Ga₂O₃ device performance and lays a solid foundation for the wider application of β-Ga₂O₃ in electronics and optoelectronics.

[Differentiation of prostatitis and clinically significant prostate cancer in peripheral zone using the prostate imaging-reporting and data system]

Objective: To determine whether clinically significant prostate cancer (PCa) and prostatitis in the peripheral zone can be distinguished using prostate imaging reporting and data system version 1 (PI-RADS V1) and version 2(PI-RADS V2). Methods: Between September 2010 and August 2016, mpMRI data of 77 patients with PCa and 29 prostatitis obtained at 3.0 T were collected in Zhangjiagang Hospital Affiliated to Soochow University. Every lesion was scored according to PI-RADS (V1 and V2), as well as a sum score and a PI-RADS V2 score. The non-parametric Kruskal-Wallis test was used to assess differences between PCa and prostatitis regarding PS3, PS4 and PI-RADS V2 score. The diagnostic performance of PI-RADS V1 and V2 for detection of prostatitis in peripheral zone was compared by analyzing ROC curve. Results: The PI-RADS V1 score for PS3, PS4 and the PI-RADS V2-score were all significantly higher for PCa (PS3:12.1±2.1; PS4:16.2±2.9; V2:4.6±0.8) than for prostatitis (PS3:8.0±0.7; PS4:10.6±1.0; V2:3.0±0.5) (all P<0.01). Of these parameters, PS4 achieved the highest predictive value for the presence of prostatitis with an AUC of 0.937, sensitivity and specificity were 87.0%, 97.0% with a threshold of 12.5. Conclusion: Prostatitis can be differentiated from clinically significant PCa in peripheral zone on mpMRI using PI-RADS system, PS4 achieved better results compared to PS3 and V2.

Effect of length of apical root resection on the biomechanical response of a maxillary central incisor in various occlusal relationships

AIM

To investigate the stress distribution and tooth displacement of a maxillary central incisor with various apical root resection lengths and occlusal relationships using finite element (FE) analysis.

METHODOLOGY

A maxillary central incisor was scanned by micro-CT. First, the FE intact incisor model with dentine, enamel, pulp and root surrounded by alveolar bone and periodontal ligament was designed based on the micro-CT image data. Then, six FE models with varying lengths of apical root resection were established to simulate the clinical treatment and reveal the clinically applicable limit of apical root resection during endodontic microsurgery. For each model under different loading conditions, the maximum von Mises stress (σ max) at the root apex, root cervix, alveolar bone and periodontal ligament and the maximum tooth displacement (ΔR max) were calculated and compared.

RESULTS

In a normal occlusion, more than 6 mm of root resection resulted in a marked increase in the ΔR max values (>10%) and σ max values of alveolar bone (>50%); the stress levels at the root apex increased dramatically when the apical root was resected more than 7 mm. With increased overjet, apical root resection did not change the stress level markedly until it reached 8 mm, but the ΔR max increased markedly (>10%) if the root was resected more than 5 mm. With deep overbites, the σ max increased significantly (>50%) when the root was resected more than 4 mm whilst the ΔR max decreased. With increased overjet and deep overbite, more than 6 mm of resection resulted in a substantial σ max increase (>50%) of alveolar bone and the ΔR max increased markedly (>10%) when the root was resected 8 mm. Additionally, the σ max and the ΔR max values were greater with increased overjet and lower with deep overbites.

CONCLUSIONS

Using FE analysis, apical root resection of more than 6 mm resulted in a marked increase of stress distribution and tooth displacement in normal and increased overjet with deep overbite occlusal relationships. In increased overjets or deep overbites, more than 5 mm or 4 mm, respectively, stress distribution and tooth displacement increased markedly.

Multichannel continuous-wave fiber cavity ringdown gas sensing utilizing frequency-shifted interferometry

We present a multichannel continuous-wave (CW) fiber cavity ringdown (FCRD) gas sensing method based on frequency-shifted interferometry (FSI). This scheme detects gas concentration by measuring the intensity decay rates of continuous light from different ringdown cavities in the spatial domain, unlike conventional FCRD techniques, which measure the decay rates of pulse light in the time domain. This method shares one CW light source, one slow detector, and one slow data collector. In order to illustrate the theory, acetylene gas concentration measurement in a two-channel FSI-FCRD system was experimentally conducted in the range of 0%-1%. A linear relation was established between concentration and absorption loss, which is proportional to the intensity decay rate, and the measurement resolutions of 3.871%/dB and 3.658%/dB were achieved, respectively. The results reveal that the proposed system has the advantages of low cost, high sensitivity, high precision, and good stability in multichannel gas detection.

[Internal carotid artery aneurysms with the initial symptom of epistaxis: a case report]

The patient has complained of twice left nose bleeding. Nasal endoscope examination found bloodstain in recessus sphenoethmoidalis, while nasal sinuses MR examination showed moderate and slightly high signal in left sphenoid sinus on T₁WI and T₂WI. Then, she was underwent nasal endoscopic surgery to stop bleeding. A dark red, pulsating tissue was found above the lateral wall of the sphenoid sinus during the surgery. After the surgery, the patient did a cerebral digital vascular angiography and the diagnosis was internal carotid artery aneurysms rupture.

Second-harmonic imaging microscopy for identifying colorectal intraepithelial neoplasia

In this study, second-harmonic imaging microscopy was used to monitor precancerous colorectal lesions at different stages. It was found that the morphology of glands and lamina propria in mucosa changes with the progression of colorectal diseases from normal to low-grade intraepithelial neoplasia to high-grade intraepithelial neoplasia and this microscopy has the ability of direct visualization of these warning symptoms. Furthermore, two morphologic variables were quantified to determine the changes of glands and collagen in lamina propria during the development of colorectal intraepithelial neoplasia. These results suggest that second-harmonic imaging microscopy has the potential in label-freely and effectively distinguishing between normal and precancerous colorectal tissues, and will be helpful for early diagnosis and treatment of colorectal diseases.

Low-Temperature One-Step Growth of AlON Thin Films with Homogenous Nitrogen-Doping Profile by Plasma-Enhanced Atomic Layer Deposition

The AlON film with homogeneous nitrogen-doping profile was grown by plasma-enhanced atomic layer deposition (PEALD) at low temperature. In this work, the precursors of the NH₃ and the O₂ were simultaneously introduced into the chamber during the PEALD growth at a relatively low temperature of 185 °C. It is found that the composition of the obtained film quickly changes from AlN to Al₂O₃ when a small amount of O₂ is added. Thus, the NH₃:O₂ ratio should be maintained at a relatively high level (>85%) for realizing the AlON growth. Benefited from the growth method, the nitrogen can be doped evenly in the entire film. Moreover, the AlON films exhibit a lower surface roughness than the AlN as well as the Al₂O₃ ones. The Al 2p and N 1s X-ray photoelectron spectra show that the AlON film is composed of Al-N, Al-O, and N-Al-O bonds. Moreover, a three-layer construction of the AlON film is proposed through the Si 2p spectra analysis and reconfirmed by the transmission electron microscopy characterization. At last, the electrical and optical tests indicate that the AlON films prepared in this work can be employed as the gate dielectric in transistor application as well as the antireflection layer in photovoltaic application.

Label-free identification of the microstructure of rat spinal cords based on nonlinear optical microscopy

The spinal cord is a vital link between the brain and the body and mainly comprises neurons, glial cells and nerve fibres. In this work, nonlinear optical (NLO) microscopy based on intrinsic tissue properties was employed to label-freely analyze the cells and matrix in spinal cords at a molecular level. The high-resolution and high-contrast NLO images of unstained spinal cords demonstrate that NLO microscopy has the ability to show the microstructure of white and grey matter including ventral horn, intermediate area, dorsal horns, ventral column, lateral column and dorsal column. Neurons with various sizes were identified in grey matter by dark spots of nonfluorescent nuclei encircled by cytoplasm-emitting two-photon excited fluorescence signals. Nerve fibres and neuroglias were observed in white matter. Besides, the spinal arteries were clearly presented by NLO microscopy. Using spectral and morphological information, this technique was proved to be an effective tool for label-freely imaging spinal cord tissues, based on endogenous signals in biological tissue. With future development, we foresee promising applications of the NLO technique for in vivo, real-time assessment of spinal cord diseases or injures.

Measurement and simulation of the response function of time of flight enhanced diagnostics neutron spectrometer for beam ion studies at EAST tokamak

The 2.5 MeV TOFED (Time-Of-Flight Enhanced Diagnostics) neutron spectrometer with a double-ring structure has been installed at Experimental Advanced Superconducting Tokamak (EAST) to perform advanced neutron emission spectroscopy diagnosis of deuterium plasmas. This work describes the response function of the TOFED spectrometer, which is evaluated for the fully assembled instrument in its final layout. Results from Monte Carlo simulations and dedicated experiments with pulsed light sources are presented and used to determine properties of light transport from the scintillator. A GEANT4 model of the TOFED spectrometer was developed to calculate the instrument response matrix. The simulated TOFED response function was successfully benchmarked against measurements of the time-of-flight spectra for quasi-monoenergetic neutrons in the energy range of 1-4 MeV. The results are discussed in relation to the capability of TOFED to perform beam ion studies on EAST.

Label-free detection of fibrillar collagen deposition associated with vascular elements in glioblastoma multiforme by using multiphoton microscopy

Glioblastoma multiforme (GBM-WHO grade IV) is the most common and the most aggressive form of brain tumors in adults with the median survival of 10-12 months. The diagnostic detection of extracellular matrix (ECM) component in the tumour microenvironment is of prognostic value. In this paper, the fibrillar collagen deposition associated with vascular elements in GBM were investigated in the fresh specimens and unstained histological slices by using multiphoton microscopy (MPM) based on two-photon excited fluorescence (TPEF) and second harmonic generation (SHG). Our study revealed the existence of fibrillar collagen deposition in the adventitia of remodelled large blood vessels and in glomeruloid vascular structures in GBM. The degree of fibrillar collagen deposition can be quantitatively evaluated by measuring the adventitial thickness of blood vessels or calculating the ratio of SHG pixel to the whole pixel of glomeruloid vascular structure in MPM images. These results indicated that MPM can not only be employed to perform a retrospective study in unstained histological slices but also has the potential to apply for in vivo brain imaging to understand correlations between malignancy of gliomas and fibrillar collagen deposition.

Involvement of oxidative stress in tri-ortho-cresyl phosphate-induced liver injury in male mice

Tri-ortho-cresyl phosphate (TOCP) has been widely used as plasticizers, plastic softeners, and flame retardants in industry and reported to have delayed neurotoxicity and reproductive toxicology in animals. However, it remains to be elusive whether TOCP induces liver injury. In this study, male mice were orally administered different concentrations of TOCP (100, 200, or 400 mg/kg/day) for 28 days. Histological examination showed that TOCP led to serious hepatocellular injury. In addition, administration of TOCP induced a marked elevation in the serum alanine aminotransferase (ALT) and aspartate aminotransferase (AST) levels in mice. The content of malondialdehyde (MDA) was increased significantly in the liver after the mice were treated with TOCP; while there was a dramatic decrease in the content of glutathione (GSH) and the activities of antioxidative enzymes superoxide dismutase (SOD) and glutathione peroxidase (GSH-PX). TOCP inhibited viability of mouse liver cancer Hepa 1-6 cells in a dose-dependent manner. Meanwhile, TOCP significantly increased MDA content and inhibited GSH content and the activities of SOD and GSH-PX in the cells, respectively. Oxidative stress dramatically inhibited viability of Hepa 1-6 cells; while inhibition of oxidative stress by N-acetyl-l-cysteine could rescue the cell viability inhibited by TOCP to a certain extent. In summary, oxidative stress might be involved in TOCP-induced hepatocellular injury in male mice.

Effect of TIMP1 transfection on PTEN expression in human kidney proximal tubular cells

To explore the role of metalloproteinase-1 (TIMP-1) tissue inhibitor in the mechanisms of kidney aging, we observed the effects of sense and antisense transfection of TIMP-1 and of metalloproteinase (MMP) inhibitors on phosphatase and tensin homolog (PTEN), vascular endothelial growth factor (VEGF), and Flk-1 expression in TIMP-1 transgenic human proximal tubular epithelial cells (HKCs). Transfected HKCs were co-incubated with 100 μM MMP-2 and MMP-9 inhibitor III for 24 h to affect enzyme inhibition. TIMP-1, MMP-2, MMP-9, PTEN, VEGF, and Flk-1 mRNA expression was detected by reverse transcription-polymerase chain reaction. PTEN, VEGF, and Flk-1 protein expression in cells of each experimental group was measured by indirect immunofluorescence. We found that PTEN expression was up-regulated (P < 0.05) in the sense TIMP-1-transfected group (P < 0.05) compared with the non-transfected and empty vector groups, and that expression of VEGF and Flk-1 was down-regulated (P < 0.05). In contrast, the antisense TIMP-1 transgenic group showed the opposite results (P < 0.05). No significant differences in expression of PTEN, VEGF, or Flk-1 were observed among the MMP- 2/MMP-9 inhibitor III, non-transfected, and empty vector groups (P > 0.05). These results suggest that in the progression of renal aging, high expression of TIMP-1 up-regulates PTEN expression through an MMP-independent pathway, and subsequently down-regulates the expression of VEGF and Flk-1, indicating that PTEN and TIMP-1 are involved in the aging-associated impairment of renal angiogenesis. Our study provides a theoretical basis for further exploration of the mechanism underlying TIMP- 1 participation in renal aging progression.

Chemotherapy combined with target drugs in the treatment of advanced colorectal cancer: a meta-analysis based on Chinese patients

BACKGROUND

Colorectal carcinoma is one of most diagnosed solid malignant carcinoma. The chemotherapy combined with target drugs in the treatment of advanced colorectal cancer in not conclusive.

METHODS

The clinical studies reporting the activity and adverse events between chemotherapy alone versus chemotherapy combined with anti-epidermal growth factor receptor drugs were screened in the databases of Medline, the Cochrane Library, Wanfang and CNKI and included in this meta-analysis. The risk ratio (RR) and its 95% confidence interval (CI) for treatment response and adverse events were pooled by random or fixed effect model.

RESULTS

A total of 10 clinical studies reporting chemotherapy combined with the target in the treatment of advanced colorectal cancer were included in this study. The pooled RR was 3.26 (95% CI: 1.74-6.11, P < 0.05), 1.49 (95% CI: 1.23-1.80) and 1.65 (95% CI: 1.37-1.98) for complete response (CR), partial response and objective response rate, respectively. For nausea and vomiting events, the RR was 1.62 (95% CI: 1.33-1.97, P < 0.05) indicating higher incidence of nausea and vomiting was observed in the combined group compared with chemotherapy alone. However, the diarrhea (RR = 1.10, 95% CI: 0.86-1.42, P > 0.05), liver function damage (RR = 1.03, 95% CI: 0.74-1.42), myelosuppression (RR = 1.04, 95% CI: 0.83-1.31) and neurotoxicity (RR = 1.12, 95% CI: 0.93-1.35) were not different between the two groups.

CONCLUSION

For Chinese patients with advanced colorectal cancer, chemotherapy combined with target drug can improve the response rate, but also increase the risk of nausea and vomiting.

Differentiating the extent of cartilage repair in rabbit ears using nonlinear optical microscopy

Nonlinear optical microscopy (NLOM) was used as a noninvasive and label-free tool to detect and quantify the extent of the cartilage recovery. Two cartilage injury models were established in the outer ears of rabbits that created a different extent of cartilage recovery based on the presence or absence of the perichondrium. High-resolution NLOM images were used to measure cartilage repair, specifically through spectral analysis and image texture. In contrast to a wound lacking a perichondrium, wounds with intact perichondria demonstrated significantly larger TPEF signals from cells and matrix, coarser texture indicating the more deposition of type I collagen. Spectral analysis of cells and matrix can reveal the matrix properties and cell growth. In addition, texture analysis of NLOM images showed significant differences in the distribution of cells and matrix of repaired tissues with or without perichondrium. Specifically, the decay length of autocorrelation coefficient based on TPEF images is 11.2 ± 1.1 in Wound 2 (with perichondrium) and 7.5 ± 2.0 in Wound 1 (without perichondrium), indicating coarser image texture and faster growth of cells in repaired tissues with perichondrium (p < 0.05). Moreover, the decay length of autocorrelation coefficient based on collagen SHG images also showed significant difference between Wound 2 and 1 (16.2 ± 1.2 vs. 12.2 ± 2.1, p < 0.05), indicating coarser image texture and faster deposition of collagen in repaired tissues with perichondrium (Wound 2). These findings suggest that NLOM is an ideal tool for studying cartilage repair, with potential applications in clinical medicine. NLOM can capture macromolecular details and distinguish between different extents of cartilage repair without the need for labelling agents.

Down-regulation of miR-1246 in cervical cancer tissues and its clinical significance

OBJECTIVE

MicroRNAs (miRNAs) are non-coding RNAs that regulate the expression of mRNAs by binding to their 3'-untranslated regions (UTRs). Accumulating evidences show that miRNAs are involved in tumorigenesis such as lung cancer, liver cancer, colon cancer, and cervical cancer. In this study, we focused on the expression of miR-1246 in clinical cervical cancer tissues as well as the relationship between miR-1246 and HPV16E6 infection status.

METHODS

Real-time quantitative polymerase chain reaction technology was used to detect the expression of miR-1246 in 68 cervical cancer tissues and 52 normal tissues. The expression of miR-1246 also was tested in HPV16E6 negative cervical cell line (SiHa) or HPV16E6 positive cell line (C33A). Western blot was performed to detect the expression of DYRK1A after knocking down HPV16E6.

RESULTS

Our data showed that the expression of miR-1246 was dramatically decreased in cervical cancer tissue, compared with normal control group (p=0.0012), and miR-1246 was negatively correlated with clinical stage and HPV16E6 infected status (p=0.0410), but no correlation was observed with age, tumor diameter, cervical invasion depth, lymph node metastasis, or vascular invasion (p>0.05). Knock down of HPV16E6 significantly raised DYRK1A protein expression targeted by miR-1246.

CONCLUSIONS

The expression of miR-1246 is negatively correlated with cervical cancer procedure as well as HPV16E6 infection status and the miR-1246 may act as a diagnostic biomarker for cervical cancer. In addition, HPV16E6 infection may be a major reason leading to decrease the expression of miR-1246 in cervical cancer. This finding contributes to deep understanding of the miR-1246 function in cervical carcinogenesis.

Design of the radiation shielding for the time of flight enhanced diagnostics neutron spectrometer at Experimental Advanced Superconducting Tokamak

A radiation shielding has been designed to reduce scattered neutrons and background gamma-rays for the new double-ring Time Of Flight Enhanced Diagnostics (TOFED). The shielding was designed based on simulation with the Monte Carlo code MCNP5. Dedicated model of the EAST tokamak has been developed together with the emission neutron source profile and spectrum; the latter were simulated with the Nubeam and GENESIS codes. Significant reduction of background radiation at the detector can be achieved and this satisfies the requirement of TOFED. The intensities of the scattered and direct neutrons in the line of sight of the TOFED neutron spectrometer at EAST are studied for future data interpretation.

Light output function and assembly of the time-of-flight enhanced diagnostics neutron spectrometer plastic scintillators for background reduction by double kinematic selection at EAST

The 2.5 MeV neutron spectrometer TOFED (Time-Of-Flight Enhanced Diagnostics) has been constructed to perform advanced neutron emission spectroscopy diagnosis of deuterium plasmas on EAST. The instrument has a double-ring structure which, in combination with pulse shape digitization, allows for a dual kinematic selection in the time-of-flight/recoil proton energy (tof/Ep) space, thus improving the spectrometer capability to resolve fast ion signatures in the neutron spectrum, in principle up to a factor ≈100. The identification and separation of features from the energetic ions in the neutron spectrum depends on the detailed knowledge of the instrument response function, both in terms of the light output function of the scintillators and the effect of undesired multiple neutron scatterings in the instrument. This work presents the determination of the light output function of the TOFED plastic scintillator detectors and their geometrical assembly. Results from dedicated experiments with γ-ray sources and quasi-monoenergetic neutron beams are presented. Implications on the instrument capability to perform background suppression based on double kinematic selection are discussed.

Design of a magnetic shielding system for the time of flight enhanced diagnostics neutron spectrometer at Experimental Advanced Superconducting Tokamak

The novel neutron spectrometer TOFED (Time of Flight Enhanced Diagnostics), comprising 90 individual photomultiplier tubes coupled with 85 plastic scintillation detectors through light guides, has been constructed and installed at Experimental Advanced Superconducting Tokamak. A dedicated magnetic shielding system has been constructed for TOFED, and is designed to guarantee the normal operation of photomultiplier tubes in the stray magnetic field leaking from the tokamak device. Experimental measurements and numerical simulations carried out employing the finite element method are combined to optimize the design of the magnetic shielding system. The system allows detectors to work properly in an external magnetic field of 200 G.

Data acquisition system with pulse height capability for the TOFED time-of-flight neutron spectrometer

A new time-of-flight neutron spectrometer TOFED has been constructed for installation at Experimental Advanced Superconducting Tokamak. A data acquisition system combining measurements of flight time and energy from the interaction of neutrons with the TOFED scintillators has been developed. The data acquisition system can provide a digitizing resolution better than 1.5% (to be compared with the >10% resolution of the recoil particle energy in the plastic scintillators) and a time resolution <1 ns. At the same time, it is compatible with high count rate event recording, which is an essential feature to investigate phenomena occurring on time scales faster than the slowing down time (≈100 ms) of the beam ions in the plasma. Implications of these results on the TOFED capability to resolve fast ion signatures in the neutron spectrum from EAST plasmas are discussed.

Monte Carlo simulation of a Bonner sphere spectrometer for application to the determination of neutron field in the Experimental Advanced Superconducting Tokamak experimental hall

To assess the neutron energy spectra and the neutron dose for different positions around the Experimental Advanced Superconducting Tokamak (EAST) device, a Bonner Sphere Spectrometer (BSS) was developed at Peking University, with totally nine polyethylene spheres and a SP9 (3)He counter. The response functions of the BSS were calculated by the Monte Carlo codes MCNP and GEANT4 with dedicated models, and good agreement was found between these two codes. A feasibility study was carried out with a simulated neutron energy spectrum around EAST, and the simulated "experimental" result of each sphere was obtained by calculating the response with MCNP, which used the simulated neutron energy spectrum as the input spectrum. With the deconvolution of the "experimental" measurement, the neutron energy spectrum was retrieved and compared with the preset one. Good consistence was found which offers confidence for the application of the BSS system for dose and spectrum measurements around a fusion device.

Implication of polymorphisms in DNA repair genes with an increased risk of hepatocellular carcinoma

We explored the association between 4 XRCC1 (Arg194Trp and Arg399Gln) and XPD (Asp312Asn and Lys751Gln) polymorphisms with the development and prognosis of hepatocellular carcinoma (HCC). A total of 218 cases with HCC and 277 healthy controls were included in the study. Genotyping of the XRCC1 (Arg194Trp and Arg399Gln) and XPD (Asp312Asn and Lys751Gln) polymorphisms was performed in a 384-well plate format on the Sequenom MassARRAY platform. We found that individuals with the XRCC1 399AA genotype had a higher risk of HCC compared with the GG genotype (odds ratio, OR = 1.85, 95% confidence interval, CI = 1.03-3.23). Similarly, individuals carrying the XPD 751GG genotype showed a greatly increased risk of HCC (OR = 2.97, 95%CI = 126- 7.38). Cox regression analysis showed that individuals carrying XPD 751Gln/Gln genotypes had a 0.30-fold increased risk of death from HCC. These results suggest that polymorphisms in XRCC1 and XPD may have functional significance in HCC.