Spatially selective p-type doping for constructing lateral WS2 p-n homojunction via low-energy nitrogen ion implantation.

The construction of lateral p-n junctions is very important and challenging in two-dimensional (2D) semiconductor manufacturing process. Previous researches have demonstrated that vertical p-n junction can be prepared simply by vertical stacking of 2D materials. However, interface pollution and large area scalability are challenges that are difficult to overcome with vertical stacking technology. Constructing 2D lateral p-n homojunction is an effective strategy to address these issues. Spatially selective p-type doping of 2D semiconductors is expected to construct lateral p-n homojunction. In this work, we have developed a low-energy ion implantation system that reduces the implanted energy to 300 eV. Low-energy implantation can form a shallow implantation depth, which is more suitable for modulating the electrical and optical properties of 2D materials. Hence, we utilize low-energy ion implantation to directly dope nitrogen ions into few-layer WS2 and successfully realize a precise regulation for WS2 with its conductivity type transforming from n-type to bipolar or even p-type conduction. Furthermore, the universality of this method is demonstrated by extending it to other 2D semiconductors, including WSe2, SnS2 and MoS2. Based on this method, a lateral WS2 p-n homojunction is fabricated, which exhibits significant rectification characteristics. A photodetector based on p-n junction with photovoltaic effect is also prepared, and the open circuit voltage can reach to 0.39 V. This work provides an effective way for controllable doping of 2D semiconductors.

Functional analysis of low-grade glioma genetic variants predicts key target genes and transcription factors.

BACKGROUND: Large-scale genome-wide association studies (GWAS) have implicated thousands of germline genetic variants in modulating individuals' risk to various diseases, including cancer. At least 25 risk loci have been identified for low-grade gliomas (LGGs), but their molecular functions remain largely unknown. METHODS: We hypothesized that GWAS loci contain causal single nucleotide polymorphisms (SNPs) that reside in accessible open chromatin regions and modulate the expression of target genes by perturbing the binding affinity of transcription factors (TFs). We performed an integrative analysis of genomic and epigenomic data from The Cancer Genome Atlas and other public repositories to identify candidate causal SNPs within linkage disequilibrium blocks of LGG GWAS loci. We assessed their potential regulatory role via in silico TF binding sequence perturbations, convolutional neural network trained on TF binding data, and simulated annealing-based interpretation methods. RESULTS: We built an interactive website (http://education.knoweng.org/alg3/) summarizing the functional footprinting of 280 variants in 25 LGG GWAS regions, providing rich information for further computational and experimental scrutiny. We identified as case studies PHLDB1 and SLC25A26 as candidate target genes of rs12803321 and rs11706832, respectively, and predicted the GWAS variant rs648044 to be the causal SNP modulating ZBTB16, a known tumor suppressor in multiple cancers. We showed that rs648044 likely perturbed the binding affinity of the TF MAFF, as supported by RNA interference and in vitro MAFF binding experiments. CONCLUSIONS: The identified candidate (causal SNP, target gene, TF) triplets and the accompanying resource will help accelerate our understanding of the molecular mechanisms underlying genetic risk factors for gliomas.

The Cancer-Associated Genetic Variant Rs3903072 Modulates Immune Cells in the Tumor Microenvironment.

Genome-wide association studies (GWAS) have hitherto identified several germline variants associated with cancer susceptibility, but the molecular functions of these risk modulators remain largely uncharacterized. Recent studies have begun to uncover the regulatory potential of noncoding GWAS SNPs using epigenetic information in corresponding cancer cell types and matched normal tissues. However, this approach does not explore the potential effect of risk germline variants on other important cell types that constitute the microenvironment of tumor or its precursor. This paper presents evidence that the breast-cancer-associated variant rs3903072 may regulate the expression of CTSW in tumor-infiltrating lymphocytes. CTSW is a candidate tumor-suppressor gene, with expression highly specific to immune cells and also positively correlated with breast cancer patient survival. Integrative analyses suggest a putative causative variant in a GWAS-linked enhancer in lymphocytes that loops to the 3' end of CTSW through three-dimensional chromatin interaction. Our work thus poses the possibility that a cancer-associated genetic variant could regulate a gene not only in the cell of cancer origin but also in immune cells in the microenvironment, thereby modulating the immune surveillance by T lymphocytes and natural killer cells and affecting the clearing of early cancer initiating cells.

[Etiological analysis of influenza surveillance data in Xuzhou from 2005 to 2011].

OBJECTIVE: To investigate the prevalence and subtypes of influenza viruses in Xuzhou city from 2005 to 2011 and to provide the scientific supports for influenza prevention and control in this religion. METHODS: The throat swab samples were collected from the influenza-like cases from national influenza like illness sentinel hospital in Xuzhou. The samples were used for influenza virus isolation and identification, sent on the national flu center to confirm according to the "national influenza surveillance program" and "influenza virus and experimental technology". RESULTS: From Oct. 2005 to Dec. 2011, a total of 9561 swab specimens were collected in which 1152 strains were identified for influenza viruses with total isolated rate of 12.0%. Among these strains, 708 strains were A1 (H1N1) subtype (14.2%), 466 strains were A3 (H3N2) subtype (40.5%), 78 strains were new H1N1 subtype (6.8%), 362 strains were BV (Victoia) subtype (31.4%) and 82 strains were BY (Yamagate) subtype (7.1%). The top detection rate (25.9%) arose in 2007, secondary detection rate (17.4%) occurred at 2009 and the lowest one (2.3%) appeared in 2011. From the winter of 2005 to the spring of 2006 A1 (H1N1) subtype had appeared as predominant strains but in the winter of 2006 the predominant strains were BV subtype. It changed to A3 subtype in 2007 to 2009 and the other three dominant strains were A1, BV and BY in 2008. In the winter of 2009, both A3 (H3N2) and new H1N1 subtype were predominant strains. BV subtype was predominant strains in 2010 to 2011. The prevalence of A3 subtype appeared in all the year while prevalence of BV only arose in the spring and winter. So the detection rate was high in January (34.4%) but low in August (2.2%). The influenza population is correlated with age, the highest detection rate arose in 5-age group and the lowest detection rate appeared in 25-age group. CONCLUSION: Influenza subtype A1, A3, New H1N1 are all appeared as predominant strains in Xuzhou city from 2005 to 2010. Besides, the prevalence of BV subtype is stronger in recently.

[Analysis on pathogen detection for 53 influenza outbreaks].

OBJECTIVE: In order to provide a scientific basis for influenza prevention and control, analyzing the epidemic characteristics and laws of influenza outbreaks in Xuzhou area during 2005-2011. METHOD: Using fluorescent-PCR method to detect influenza virus nucleic acid on Nasopharyngeal swab specimens collected from influenza outbreak cases during 2005-2011 and fast classifying influenza virus A1 (H1N1), A3 (H3N2), new H1N1 BV (Victoria) and BY (Yamagate) on subtypes. At the same time, isolating the influenza virus with MDCK cells, and sending them to the National Influenza Center for review, after the preliminary identification of the isolated influenza virus. RESULTS: During 2005-2011, there are 53 influenza outbreaks in Xuzhou area, which caused by influenza virus subtype BV accounting for 26.42% (14/53), A3 accounting for 49.1% (26/53), A3 and A1 mixture accounting for 3.77% (2/53) and the new H1N1 accounting for 20.75% (11/53). The outbreaks in 2007 and 2009 mainly caused by A3, and show that the winter spring (January) and summer autumn (September) as two popular peaks during 2005-2011; BV mainly causes the outbreaks from Feb. to Jun. CONCLUSION: In Xuzhou area, since the winter of 2005, influenza virus subtype BV, the A3, and new H1N1 has alternately as mainly predominant strain, caused local influenza outbreaks. In which BV has increased trend year by year during 2005-2011. The students in primary and secondary schools are the major crowd of influenza outbreaks. Fluorescent-PCR detection methods could be a preferred method for reliable and rapid diagnostic of epidemic influenza outbreaks.

[Research on the aetiology of suspected enterovirus infected patients in Xuzhou district in 2009].

OBJECTIVE: To understand and master the situation in which enterovirus caused hand-foot-and-mouth disease (HFMD) in Xuzhou district in 2009 so as to provide scientific basis for the control and prevention of hand-foot-and-mouth disease. METHODS: The researchers adopted fluorescence RT-PCR method to detect EV and EV71 as well as the CA16 specificity RNA from 222 samples of anal swabs and oropharyngeal swabs from the 240 cases who were diagnosed clinically as hand-foot-mouth disease infected by enterovirus. Also, the researchers conducted EV71-IgM antibody detection on 114 samples of acute phase serum with ELA method. RESULTS: Among the 240 enterovirus infected patients, the total EV infection rate is 72.50% (174/240), among which EV71 infection rate is 57.92% (139/240), CoxA16 infection rate is 9.17% (22/240), and other EV infection rate is 5.42% (13/240). The EV71-RNA positive rate of the samples of 222 anus swabs among the 240 suspected enterovirus infected patients is 45.94% (102/222), the samples of swallow swab EV71-RNA positive rate is 25.68% (57/222) and the EV71-IgM antibody positive rate of 114 samples of acute phase serum is 86.84% (99/114). The EV71-RNA positive rate of oropharyngeal swabs of 254 healthy children is 1.57% (4/254) , and no CoxA16-RNA was detected. In the oropharyngeal swabs of 54 close contacts (medical personnel), the EV-RNA detected is negative. The positive rate of EV71-IgM antibody of the 258 healthy children's serum samples is 2.71% (7/258). CONCLUSION: The widespreading of hand-foot-mouth disease in Xuzhou district is caused mainly by type 71 enterovirus. Inapparent infection of type 71 enterovirus exists among children under the age of 3 during the time of widespreading period and IgM antibody develops in them. It is difficult for adults to be infected by EV71 even if they contact the contagion source closely. The positive rate of EV71-IgM antibody in the samples of acute phase serum of suspected cases is the highest (86.84%), and the second highest is the positive rate of RNA of EV71 of anal swabs (45.94%) and of the EV71 of oropharyngeal swabs (25.68%). ELA reagent kit is used in the early diagnosis of EV71 infection for it is easy to operate, fast and economic, so, it is worth popularizing in the grass-root medical units.