Background: Photovoltaic (PV) array which is composed of modules is considered as the fundamental power conversion unit of a PV generator system. The PV array has nonlinear characteristics and it is quite expensive and takes much time to get the operating curves of PV array under varying operating conditions. In order to overcome these obstacles, common and simple models of solar panel have been developed and integrated to many engineering software including Matlab/Simulink. However, these models are not adequate for application involving hybrid energy system since they need a flexible tuning of some parameters in the system and not easily understandable for readers to use by themselves. Therefore, this paper presents a step-by-step procedure for the simulation of PV cells/modules/ arrays with Tag tools in Matlab/Simulink. A DS-100M solar panel is used as reference model. The operation characteristics of PV array are also investigated at a wide range of operating conditions and physical parameters. Result:The output characteristics curves of the model match the characteristics of DS-100M solar panel. The output power, current and voltage decreases when the solar irradiation reduces from 1000 to 100 W/m 2 . When the temperature decreases, the output power and voltage increases marginally whereas the output current almost keeps constant. Shunt resistance has significant effect on the operating curves of solar PV array as low power output is recorded if the value of shunt resistance varies from 1000 ohms to 0.1 ohms. Conclusion:The proposed procedure provides an accurate, reliable and easy-to-tune model of photovoltaic array. Furthermore, it also robust advantageous in investigating the solar PV array operation from different physical parameters (series, shunt resistance, ideality factor, etc.) and working condition ( varying temperature, irradiation and especially partial shadow effect) aspects.

Since April 7, 2020, our COVID-19 diagnostic laboratory (CLIAHUB) has received samples from multiple counties in California — our RT-PCR protocol (1) employs N-gene (NIID_2019-nCov_N_F2/R2ver3/P2 (Japan) (2)) and E-gene (E_Sarbeco_F/R/P1 (Germany) (3)) simplex assays.…

CD4+ follicular helper T (Tfh) cells have been shown to be critical for the activation of germinal center (GC) B-cell responses. Similar to other infections, Plasmodium infection activates both GC as well as non-GC B cell responses. Here, we sought to explore whether Tfh cells and GC B cells are required to eliminate a Plasmodium infection. A CD4 T cell-targeted deletion of the gene that encodes Bcl6, the master transcription factor for the Tfh program, resulted in complete disruption of the Tfh response to Plasmodium chabaudi in C57BL/6 mice and consequent disruption of GC responses and IgG responses and the inability to eliminate the otherwise self-resolving chronic P. chabaudi infection. On the other hand, and contrary to previous observations in immunization and viral infection models, Signaling Lymphocyte Activation Molecule (SLAM)-Associated Protein (SAP)-deficient mice were able to activate Tfh cells, GC B cells, and IgG responses to the parasite. This study demonstrates the critical role for Tfh cells in controlling this systemic infection, and highlights differences in the signals required to activate GC B cell responses to this complex parasite compared with those of protein immunizations and viral infections. Therefore, these data are highly pertinent for designing malaria vaccines able to activate broadly protective B-cell responses.

Hypoxia-inducible factors (HIFs) are master regulators of angiogenesis and cellular adaptation in hypoxic microenvironments. Accumulating evidence indicates that HIFs also regulate cell survival, glucose metabolism, microenvironmental remodeling, cancer metastasis, and tumor progression, and thus, HIFs are viewed as therapeutic targets in many diseases. Epigenetic changes are involved in the switching 'on' and 'off' of many genes, and it has been suggested that the DNA hypermethylation of specific gene promoters, histone modifications (acetylation, phosphorylation, and methylation) and small interfering or micro RNAs be regarded epigenetic gene targets for the regulation of disease-associated cellular changes. Furthermore, the hypoxic microenvironment is one of the most important cellular stress stimuli in terms of the regulation of cellular epigenetic status via histone modification. Therefore, drug development and therapeutic approaches to ischemic diseases or cancer for targeting HIFs by modulation of epigenetic status become an attractive area. Here, the authors provide a review of the literature regarding the targeting of HIF, a key modulator of hypoxic-cell response under various disease conditions, by modulating histone or DNA using endogenous small RNAs or exogenous chemicals.

Background: Building capacity in hepatitis B virus prevention and management for medical students and health professionals is one of the pillars of the national viral hepatitis control strategy. Methods: A cross-sectional study was conducted at eight medical universities from the northern, central and southern regions of the country between May and November 2020 using a systematic random sampling technique. Results: Among 2000 participants, 84.2% reported they had been tested for hepatitis B and 83.9% had received the hepatitis B vaccine. The mean knowledge, attitude, practice score was 40.2 out of 54 (74.4%) with only 19.9% of the study participants obtaining a good score. In multivariate analysis, fifth year students, students from central universities, students who had tested positive for hepatitis B and students who had received hepatitis B vaccine or had encountered patients with chronic hepatitis B had significantly higher knowledge score (p < 0.05). The study showed lack of trust in the hepatitis B vaccine safety and lack of confidence in providing counselling, testing and management of patients with chronic hepatitis B. Conclusion: Findings from our research emphasized an immediate need to improve the medical schools’ training curriculum in Vietnam to enable students’ readiness in hepatitis B prevention and management.

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High field magnetic resonance imaging (MRI)-based delineation of the substantia nigra (SN)and visualization of its inner cellular organization are promising methods for the evaluation of morphological changes associated with neurodegenerative diseases; however, corresponding MR contrasts must be matched and validated with quantitative histological information. Slices from two postmortem SN samples were imaged with a 7 Tesla (7T) MRI with T 1 and T 2 * imaging protocols and then stained with Perl's Prussian blue, Kluver-Barrera, tyrosine hydroxylase, and calbindin immunohistochemistry in a serial manner. The association between T 2 * values and quantitative histology was investigated with a co-registration method that accounts for histology slice preparation. The ventral T 2 * hypointense layers between the SNr and the crus cerebri extended anteriorly to the posterior part of the crus cerebri, which demonstrates the difficulty with an MRI-based delineation of the SN. We found that the paramagnetic hypointense areas within the dorsolateral SN corresponded to clusters of neuromelanin (NM). These NM-rich zones were distinct from the hypointense ventromedial regions with high iron pigments. Nigral T 2 * imaging at 7T can reflect the density of NM-containing neurons as the metal-bound NM macromolecules may decrease T 2 * values and cause hypointense signalling in T 2 * imaging at 7T.Identifying and characterizing the anatomic architecture of the substantia nigra (SN) has important clinical implications for the evaluation of structural changes associated with neurodegenerative conditions, such as Parkinson's disease (PD) [1][2][3] . The SN is subdivided into two histologically distinct regions, the ventral pars reticulata (SNr) and the dorsal pars compacta (SNc). The SNc is composed of neuromelanin (NM)-containing dopaminergic neurons, which are affected early in PD [1][2][3] . Numerous attempts have been made to visualize substructure morphology of the SN and to assess the neurodegenerative changes using various magnetic resonance imaging (MRI) signal contrasts 2,3 . For example, iron-sensitive MR sequences have great potential to define the boundaries and shape of the SN 2-4 as the local deposition of iron alters magnetic field inhomogeneities and appears hypointense in T 2 or T 2 * -weighted images (T 2 *WI) due to the shortening of transverse relaxation times 2,5 . By taking advantage of region-specific iron content within the SN, the area of lower T 2 * -weighted signal intensity is assigned to the SNr based on the histological observation of elevated iron concentration in that region 3,5,6 . NM-sensitive T 1 -weighted fast spin echo technique in in vivo 3T MRI studies allows the visualization of the SNc via hyperintense areas 2,3,[7][8][9] . NM within the dopaminergic neurons is speculated to generate paramagnetic T 1 -shortening effects on combining with metals, such as iron and copper 2,3,7,10 . While NM-containing dopaminergic neurons are densely distributed in the SNc, they form clusters of cells that penetra...