Rapidly Determine the Maximum Power Point in the Parallel Configuration of the Photovoltaic System.

The maximum power point tracking (MPPT) solutions improve power generation efficiency, quickly stabilizing the output waveform of photovoltaic (PV) systems under variable operating conditions. Along with new algorithms, improved and adjusted methods to exploit energy from PV systems are increasingly being researched and proposed. However, the proposed solutions based on the traditional algorithms and their improvements have poor performance, while the advanced algorithms or hybrid methods bring high performance but need to be simplified, and the response speed is higher. Moreover, a suitable PV configuration makes choosing a simple but highly efficient algorithm, especially in low-power PV system applications such as rooftop solar power, traffic lights, and moving vehicles…where the number of PV panels is insufficient to implement flexible configurations. This paper proposes a modified version of the Perturb and Observe (MPO) algorithm to improve MPPT performance and increase convergence speed in the parallel structure of PV panels. The Short-Circuit Current (Isc) and Open-Circuit Voltage (Voc) are calculated directly at specific operating conditions to quickly determine the potential maximum power point (MPP) that will reduce power interruptions and increase power generation efficiency compared to periodic updates. Therefore, the proposed solution converges faster, with higher efficiency, and the output signal in static and dynamic MPPT situations is more stable. The results show that the highest efficiency in simulation and experiment is 99.99% and 99.93%, respectively, while the convergence speed is 0.01 s and 0.03 s, respectively. They are better than the traditional Perturb and Observe (P&O) algorithm, the Variable Step Size Perturb and Observe (VSSP&O) method, and the Particle Swarm Optimization (PSO) technique under the same operating conditions. In addition, its performance and convergence speed are also compared with the latest introduced algorithms. The results show that it is valuable and reliable for parallel PV configuration.

Frequencies and Association of CYP3A5 Polymorphism With Tacrolimus Concentration Among Renal Transplant Recipients in Vietnam.

BACKGROUND: This study aims to investigate the frequencies and association of CYP3A5 polymorphism with tacrolimus concentration among renal transplant recipients in Vietnam. METHODS: Sixty-eight kidney transplant recipients were included in this study from the department of nephrology and dialysis, Military Hospital 103. Blood samples were collected for monitoring of tacrolimus levels and determination of CYP3A5 genetic polymorphism. RESULTS: A total of 68 patients studied. The CYP3A5*3*3, CYP3A5*1*3, and CYP3A5*1*1 genotypes were detected in 48 (70.6%), 16 (23.5%), and 4 (5.9%), respectively. Tacrolimus concentrations were much lower in CYP3A5 expressors than in CYP3A5 nonexpressors on the first day, month 1, 3, 6, and 12 (5.98 ± 1.05 vs 6.57 ± 1.03, P = .03; 5.79 ± 1.13 vs 6.82 ± 1.05, P < .001; 4.76 ± 1.48 vs 6.73 ± 1.09, P < .001; 4.29 ± 1.64 vs 6.46 ± 1.23, P < .001; 4.20 ± 1.36 vs 6.04 ± 1.26, P < .001), respectively. Notably, the concentration/dose ratio in the CYP3A5 expressors was lower than in CYP3A5 nonexpressors at time points of follow up (P < .001). However, there were no significant differences in the age, sex, HLA mismatch, type of donors, acute rejection, and creatinine levels at time points between group of CYP3A5 expressors and those of CYP3A5 nonexpressors. CONCLUSION: In conclusion, this research indicated the significant association of CYP3A5 genetic polymorphism with daily dose and tacrolimus concentrations in renal transplant recipients. This study provided a closer step to individualize the dose of tacrolimus in renal transplant patients in Vietnam.

Serum dioxin concentrations in military workers at three dioxin-contaminated airbases in Vietnam.

An estimated 91,998,400 L of herbicides were stocked at three US airbases in Vietnam between 1962 and 1971. These herbicides were contaminated with 2,3,7,8-tetrachlorodibenzo-p-dioxin (2,3,7,8-tetraCDD). In 2017, we sampled blood from 120 male Vietnamese military workers in the three dioxin-contaminated airbases (Bien Hoa, Da Nang, and Phu Cat) and from 20 workers at an uncontaminated airbase. 2,3,7,8-tetraCDD concentrations were highest in samples from Bien Hoa (18.2 pg/g lipid), followed by samples from Da Nang (9.2 pg/g lipid), Phu Cat (3.7 pg/g lipid), and the reference base (2.1 pg/g lipid). In Bien Hoa, 31 of the 50 subjects had blood 2,3,7,8-tetraCDD levels in the range of 10-100 pg/g lipid and four subjects had 2,3,7,8-tetraCDD levels that exceeded 100 pg/g lipid. In Da Nang, almost half of the subjects had blood 2,3,7,8-tetraCDD concentrations in the range of 10-100 pg/g lipid. These findings suggest that military workers at contaminated bases are the population most vulnerable to dioxin exposure, especially at Bien Hoa.

A simple method for detection of a novel coronavirus (SARS-CoV-2) using one-step RT-PCR followed by restriction fragment length polymorphism.

A novel coronavirus associated with acute respiratory disease (named SARS-CoV-2) is recently identified in Wuhan city, China, spread rapidly worldwide. Early identification of this novel coronavirus by molecular tools is critical for surveillance and control of the epidemic outbreak. We aimed to establish a simple method for the detection of SARS-CoV-2 in differentiating with SARS-CoV. Primers of our in-house reverse transcription polymerase chain reaction (RT-PCR) assays were designed to target conserved regions of the RdRP gene and E gene, selected restriction enzymes EcoRI, Tsp45I, and AluI to distinguish between SARS-CoV-2 and SARS-CoV. In this report, a 396-bp fragment of the RdRp gene and 345-bp fragment of the E gene were amplified by one-step RT-PCR. Enzyme Tsp45I cuts the RdRP-amplified product of SARS-CoV-2 generating three fragments of 45, 154, and 197 bp, but it did not cut the amplicon of SARS-CoV. In contrast, the amplified product of SARS-CoV was digested with EcoRI producing two fragments of 76 and 320 bp, whereas the amplicon of SARS-CoV-2 was undigested by Tsp45I help to distinguish clearly SARS-CoV-2 from SARS-CoV on gel electrophoresis. In addition, AluI cut the amplicon of the E gene of SARS-CoV-2 generating two fragments of 248 and 97 bp without cutting to SARS-CoV. The accuracy of the assay was confirmed by sequencing and phylogenetic analysis. When evaluated on clinical samples showed a high sensitivity of 95%, specificity of our assay was 100% and clinical performance for detection of SARS-CoV-2 in comparison with other reference assays. In conclusion, in the present study, we successfully developed a simple method for molecular detection of SARS-CoV-2 in differentiating with SARS-CoV.

Association of dioxin exposure and reproductive hormone levels in men living near the Bien Hoa airbase, Vietnam.

Dioxins are endocrine-disrupting chemicals, and their effects on reproductive functions are well-documented. The aim of the present study was to measure the levels of reproductive hormones in 42 men residing near a dioxin-contaminated area in Vietnam. We measured levels of 17 2,3,7,8-substituted congeners of polychlorinated dibenzo-p-dioxins (PCDDs) and polychlorinated dibenzofurans (PCDFs) and four non-ortho polychlorinated biphenyls (PCBs) in blood. Levels of follicle-stimulating hormone, luteinizing hormone, progesterone, prolactin, estradiol, and total testosterone were measured in serum. Blood dioxin levels were elevated; the levels of 2,3,7,8-tetrachlorodibenzo-p-dioxin was 7.3pg/g fat. Seven of the men had testosterone levels below 250ng/dL, and nine men had prolactin levels above 9.7ng/mL. Four PCDD congeners, two PCDF congeners, one PCB congener, and the sum TEQ of PCDDs, PCDDs/Fs, and PCDDs/Fs/PCBs were positively and significantly correlated with prolactin levels. Two PCDD congeners, six PCDF congeners, two PCB congeners, and the TEQs of PCDFs and PCBs were negatively and significantly correlated with testosterone levels. There were no significant correlations between dioxin congeners and follicle-stimulating hormone, luteinizing hormone, or progesterone levels.