The Response Of An Hyperpure Germanium Detector To Ionizing Radiation

A basic understanding of the response of semiconductor detectors to ionizing radiation is important for their proper usage and their further development. Such devices may also be used to explore the energy deposition process in semiconductors.;The detailed response of an HPGe detector ({dollar}\sim{dollar}1 cm{dollar}\sp3{dollar} hyperpure Ge with an ion-implanted front contact) to ionizing radiation has been studied with regard to the radiation ionization energy ratio, {dollar}\varepsilon\sb{lcub}\rm ion{rcub}{dollar}/{dollar}\varepsilon\sb0{dollar}, using radioactive {dollar}\alpha{dollar} and {dollar}\gamma{dollar} sources and accelerated ion beams ({dollar}\sp1{dollar}H, {dollar}\sp{lcub}3,4{rcub}{dollar}He, {dollar}\sp7{dollar}Li). The data span the energy range of a few hundred keV to a few MeV. Effects of temperature and bias voltage variation have been investigated. The response to charged particles and {dollar}\gamma{dollar}-rays have been measured simultaneously by using {dollar}\sp{lcub}152{rcub}{dollar}Eu, {dollar}\sp{lcub}60{rcub}{dollar}Co, and {dollar}\sp{lcub}137{rcub}{dollar}Cs {dollar}\gamma{dollar}-ray sources.;Analysis of the results reveals: (1) Contrary to earlier conclusions, a difference of {dollar}\sim{dollar}1% between {dollar}\varepsilon\sb0{dollar} and {dollar}\varepsilon\sb{lcub}\rm\alpha\ or\ p{rcub}{dollar} has been found in Ge, often showing {dollar}\varepsilon\sb{lcub}\rm\alpha,p{rcub}\u3c\varepsilon\sb0{dollar}--results that are qualitatively in accord with the observed behaviour for Si semiconductor detectors; these observations cannot be explained by trapping or recombination effects during the stopping of the ion in the sensitive volume. (2) The functional behaviour of {dollar}\varepsilon\sb\alpha{dollar}/{dollar}\varepsilon\sb0{dollar} and {dollar}\varepsilon\sb{lcub}\rm p{rcub}{dollar}/{dollar}\varepsilon\sb0{dollar} exhibits a non-linear response of the Ge detector as a function of ion energy for a given projectile, which is similar to results observed for Si detectors; the ratios approach unity as the particle energy increases--a result that is to be expected from fundamental considerations. (3) Where comparisons can be made with earlier works, the present results for {dollar}\varepsilon\sb{lcub}\rm ion{rcub}{dollar}/{dollar}\varepsilon\sb0{dollar} are in good quantitative agreement when similar assumptions are included, e.g. the apparent window thickness of the Ge detector is assumed to be independent of ion energy. (4) The energy loss in the window of the Ge detector is found to vary with the energy of the incident particle in a manner that does not agree with the stopping power curve. The apparent thickness of this window region is observed to decrease dramatically with increasing detector temperature ({dollar}\sim{dollar}30% decrease as T increases from 80K to 175K). This observation suggests that the surface layer of the Ge detector does not consist of a simple passive dead layer. The reasons for this behaviour are not presently understood. (5) Pronounced channeling effects are evident in the pulse height spectra as the incidence angle of the ions is rotated with respect to the detector surface normal. These features arise from ion channeling effects in the ion-implanted entrance window region. Monte Carlo calculations of the projectile energy loss under channeling conditions are in qualitative agreement with experimental observations. However, such channeling effects do not account for the deviations of {dollar}\varepsilon\sb{lcub}\rm ion{rcub}{dollar}/{dollar}\varepsilon\sb0{dollar} from unity

Structure and superconductivity of Mg(B1-xCx)2 compounds

In this paper, we reported the structural properties and superconductivity of Mg(B1-xCx)2 compounds. Powder x-ray diffraction results indicate that the samples crystallize in a hexagonal AlB2-type structure. Due to the chemical activity of Mg powders, a small amount of MgO impurity phase was detected by x-ray diffraction. The lattice parameters decrease slightly with increasing carbon content. Magnetization measurements indicate the non-stoichiometry of MgB2 has no influence on the superconducting transition temperature and the transition temperature width. The addition of carbon results in a decrease of Tc and an increase in the superconducting transition width, implying the loss of superconductivity.Comment: PDF files, 5 pages,3 figures, Accepted by Chinese Physics on Feb. 26, 2001(in press

A rapid and efficient method to express target genes in mammalian cells by baculovirus

863 Program [2001AA628120]AIM: To investigate the modification of baculovirus vector and the feasibility of delivering exogenous genes into mammalian cells with the culture supernatant of Spodoptera frugiperta (Sf9) cells infected by recombinant baculoviruses. METHODS: Two recombinant baculoviruses (BacV-CMV-EGFPA, BacV-CMV-EGFPB) containing CMV-EGFP expression cassette were constructed. HepG2 cells were directly incubated with the culture supernatant of Sf9 cells infected by recombinant baculoviruses, and reporter gene transfer and expression efficiencies were analyzed by flow cytometry (FCM). The optimal transduction conditions were investigated by FCM assay in HepG2 cells. Gene-transfer and expression efficiencies in HepG2 or CV1 cells by baculovirus vectors were compared with lipofectAMINE, recombinant retrovirus and vaccinia virus expression systems. Twenty different mammalian cell lines were used to investigate the feasibility of delivering exogenous genes into different mammalian cells with the culture supernatant of infected Sf9 cells. RESULTS: CMV promoter could directly express reporter genes in Sf9 cells with a relatively low efficiency. Target cells incubated with the 1: 1 diluted culture supernatant (moi=50) for 12 h at 37 could achieve the highest transduction and expression efficiencies with least impairment to cell viability. Under similar conditions the baculovirus vector could achieve the highest gene-transfer and expression efficiency than lipofectAMINE, recombinant retrovirus and vaccinia virus expression systems. Most mammalian cell lines could be transduced with recombinant baculovirus. In primate adherent culture cells the recombinant baculovirus could arrive the highest infection and expression efficiencies, but it was not very satisfactory in the cell lines from mice and suspended culture cells. CONCLUSION: Mammalian cells incubated with the culture supernatant of infected Sf9 cells could serve as a very convenient way for rapid and efficient expression of foreign genes in mammalian cells, but it might be more suitable for primate adherent culture cells

Outcomes and prognostic factors of simple partial cystectomy for localized bladder urothelial cell carcinoma

AbstractRadical cystectomy has remained the gold standard for recurrent superficial or muscle invasive bladder tumor. However, partial cystectomy still has a role in those who reject or have contraindications for radical cystectomy. In this study, we sought to identify predictors of bladder recurrence and overall survival after simple partial cystectomy. We included 27 patients with bladder tumor who received simple partial cystectomy without pelvic lymph node dissection between March 2000 and September 2013. Adjuvant chemotherapy or radiation therapy was prescribed according to the pathological results. Parameters were compared on the basis of bladder recurrence and overall survival. During a mean follow-up time of 39 months, five patients (18.5%) experienced bladder recurrence. An older age, a higher pathological stage, positive surgical margins, and distant metastases were significant predictors of overall survival (p = 0.031, p = 0.001, p = 0.001, and p = 0.011, respectively). Meanwhile, previous bladder instillation and positive surgical margins were significant predictors of bladder recurrence (p = 0.026 and p = 0.027, respectively). The rate of consecutive distant metastases (33.3%) was almost twice the rate of bladder recurrence (18.5%), and six patients developed consecutive distant metastases without first experiencing bladder recurrence. In patients who received a simple partial cystectomy as an alternative treatment, previous bladder instillation and positive surgical margins were significant predictors of bladder recurrence. Patients with an older age, positive surgical margins, and consecutive distant metastases had worse overall survival. Partial cystectomy with routine lymph node dissection may be a better option for achieving favorable long-term outcomes

Suppress HBV by therapeutic vaccine

乙肝预防性疫苗显著减少了乙肝新发感染，但目前全球仍有约2.5亿慢性乙肝感染者，若未得到有效治疗，可能发展为肝癌、肝硬化等终末期肝病并导致死亡。夏宁邵教授团队研究发展了一种新型的B细胞表位嵌合型类病毒颗粒乙肝治疗性疫苗（治疗性蛋白），在多种模型中证实了其对慢性乙肝感染的治疗潜力，为研发治疗慢性乙肝的原创药物提供了新思路。 我校博士后张天英、博士生郭雪染和博士生巫洋涛为该论文共同第一作者，夏宁邵教授、袁权副教授、张军教授为该论文的共同通讯作者。【Abstract】Objective: This study aimed to develop a novel therapeutic vaccine based on a unique B cell epitope and investigate its therapeutic potential against chronic hepatitis B (CHB) in animal models. Methods: A series of peptides and carrier proteins were evaluated in HBV-tolerant mice to obtain an optimized therapeutic molecule. The immunogenicity,therapeutic efficacy and mechanism of the candidate were investigated systematically. Results: Among the HBsAg-aa119-125-containing peptides evaluated in this study, HBsAg-aa113-135 (SEQ13) exhibited the most striking therapeutic effects. A novel immuno-enhanced virus-like particle carrier (CR-T3) derived from the roundleaf bat HBV core antigen (RBHBcAg) was created and used to display SEQ13, forming candidate molecule CR-T3-SEQ13. Multiple copies of SEQ13 displayed on the surface of this particulate antigen promote the induction of a potent anti-HBs antibody response in mice, rabbits and cynomolgus monkeys. Sera and purified polyclonal IgG from the immunized animals neutralized HBV infection in vitro and mediated efficient HBV/HBsAg clearance in the mice. CR-T3-SEQ13-based vaccination induced long-term suppression of HBsAg and HBV DNA in HBV transgenic mice and eradicated the virus completely in hydrodynamic-based HBV carrier mice. The suppressive effects on HBsAg were strongly correlated with the anti-HBs level after vaccination, suggesting that the main mechanism of CR-T3-SEQ13 vaccination therapy was the induction of a SEQ13-specific antibody response that mediated HBV/HBsAg clearance. Conclusions: The novel particulate protein CR-T3-SEQ13 suppressed HBsAg effectively through induction of a humoral immune response in HBV-tolerant mice. This B cell epitope-based therapeutic vaccine may provide a novel immunotherapeutic agent against chronic HBV infection in humans.This work was supported by the National Scientific and Technological Major project (2017ZX10202203-001), the National Natural Science Foundation of China (31730029, 81672023, 81871316 and 81702006) and the Xiamen University President Fund Project (20720160063). 该研究获得了“艾滋病和病毒性肝炎等重大传染病防治”科技重大专项、国家自然科学基金等资助

Robust in vitro assay for analyzing the neutralization activity of serum specimens against hepatitis B virus.

Anti-HBs is a well-known marker of protective capability against HBV. However, little is known about the association between the qAnti-HBs determined by immunoassays and the neutralization activity (NAT) derived from functional assays. We developed an in vitro assay for direct measurement of the NAT of human sera. The new assay was highly sensitive, with an analytical sensitivity of 9.6 ± 1.3 mIU/mL for the HBIG standard. For serum detection, the maximum fold dilution required to produce ≥50% inhibition (MDF50) of HBV infection was used as the quantitative index. In vitro NAT evaluations were conducted for a cohort of 164 HBV-free healthy individuals. The results demonstrated that the NAT positively correlated with the qAnti-HBs ( R 2 = 0.473, p < 0.001). ROC analysis indicated that the optimal cutoff value of the qAnti-HBs to discriminate significant NAT (MDF50 ≥ 8) was 62.9 mIU/mL, with an AUROC of 0.920. Additionally, we found that the qAnti-HBc was another independent parameter positively associated with the NAT ( R 2 = 0.300, p < 0.001), which suggested that antibodies against other HBV proteins generated by previous HBV exposure possibly also contribute to the NAT. In summary, the new cell-based assay provides a robust tool to analyse the anti-HBV NAT. Abbreviations: HBV: Hepatitis B virus; HBsAg: Hepatitis B surface antigen; Anti-HBs: Hepatitis B surface antibody; HBeAg: Hepatitis B e antigen; Anti-HBc: Hepatitis B core antibody; qAnti-HBs: quantitative hepatitis B surface antibody; qAnti-HBc: quantitative hepatitis B core antibody; qHBeAg: quantitative hepatitis B e antigen; NAT: neutralization activity; HBIG: hepatitis B immune globulin; NTCP: Na+-taurocholate cotransporting polypeptide; IRES: internal ribosome entry site; ccHBV: cell culture derived hepatitis B virus; GE/cell: genome equivalent per cell; MOI: multiplicity of infection; Dpi: day post infection; HepG2-TetOn: a HepG2-derived cell line that expresses the doxycycline-regulated transactivator; ROC: receiver operating characteristic curve; AUROC: area under receiver operating characteristic curve; LLOQ: the lower limits of quantification; MDF50: the maximum fold dilution required to produce ≥50% inhibition; IC50: half maximal inhibitory concentration

The Traitor

The proteolytic activation of protein kinase Cδ (PKCδ) generates a catalytic fragment called PKCδ-CF, which induces cell death. However, the mechanisms underlying PKCδ-CF-mediated cell death are largely unknown. On the basis of an engineering leukemic cell line with inducible expression of PKCδ-CF, here we employ SILAC-based quantitative phosphoproteomics to systematically and dynamically investigate the overall phosphorylation events during cell death triggered by PKCδ-CF expression. Totally, 3000 phosphorylation sites were analyzed. Considering the fact that early responses to PKCδ-CF expression initiate cell death, we sought to identify pathways possibly related directly with PKCδ by further analyzing the data set of phosphorylation events that occur in the initiation stage of cell death. Interacting analysis of this data set indicates that PKCδ-CF triggers complicated networks to initiate cell death, and motif analysis and biochemistry verification reveal that several kinases in the downstream of PKCδ conduct these networks. By analysis of the specific sequence motif of kinase-substrate, we also find 59 candidate substrates of PKCδ from the up-regulated phosphopeptides, of which 12 were randomly selected for <i>in vitro</i> kinase assay and 9 were consequently verified as substrates of PKCδ. To our greatest understanding, this study provides the most systematic analysis of phosphorylation events initiated by the cleaved activated PKCδ, which would vastly extend the profound understanding of PKCδ-directed signal pathways in cell death. The MS data have been deposited to the ProteomeXchange with identifier PXD000225