African swine fever virus (ASFV) genotype II is endemic to Vietnam. We detected recombinant ASFV genotypes I and II (rASFV I/II) strains in domestic pigs from 6 northern provinces in Vietnam. The ...introduction of rASFV I/II strains could complicate ongoing ASFV control measures in the region.
African swine fever (ASF) is a contagious and deadly viral disease affecting swine of all ages. ASF was first reported in Vietnam in February 2019, and it is now considered endemic in Vietnam. In ...this study, 122 ASF-positive samples collected from domestic pigs in 28 different provinces of northern, central, and southern Vietnam during outbreaks in 2019–2021 were genetically characterized. The findings confirmed that all ASF virus (ASFV) strains circulating in Vietnam belonged to p72 genotype II, p54 genotype II, CD2v serogroup 8, and CVR gene variant type I. However, further analysis based on the tandem repeat sequences located between I73R and I329L genes revealed that there were three different variants of ASFV, IGR I, II, and III, circulating in the domestic pig population in Vietnam. The IGR II variants were the most prevalent (117/122 strains) and were detected in pigs in all of the provinces tested, followed by IGR III (4/122 strains) and IGR I (1/122 strains). This study confirms for the first time the presence of IGR III variants in Vietnam.
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•A semi-nested, heptaplex RT-PCR assay for SARS-CoV-2 detection has been developed.•The complex melting spectrum was interpreted by an artificial intelligence algorithm.•The developed ...assay enables 96-sample pooled testing for increase of testing capacity.•About 8,000 pre-amplified samples could be screened in one realtime PCR run.
Asymptomatic transmission was found to be the Achilles’ heel of the symptom-based screening strategy, necessitating the implementation of mass testing to efficiently contain the transmission of COVID-19 pandemic. However, the global shortage of molecular reagents and the low throughput of available realtime PCR facilities were major limiting factors.
A novel semi-nested and heptaplex (7-plex) RT-PCR assay with melting analysis for detection of SARS-CoV-2 RNA has been established for either individual testing or 96-sample pooled testing. The complex melting spectrum collected from the heptaplex RT-PCR amplicons was interpreted with the support of an artificial intelligence algorithm for the detection of SARS-CoV-2 RNA. The analytical and clinical performance of the semi-nested RT-PCR assay was evaluated using RNAs synthesized in-vitro and those isolated from nasopharyngeal samples.
The LOD of the assay for individual testing was estimated to be 7.2 copies/reaction. Clinical performance evaluation indicated a sensitivity of 100% (95% CI: 97.83–100) and a specificity of 99.87% (95% CI: 99.55–99.98). More importantly, the assay supports a breakthrough sample pooling method, which makes possible parallel screening of up to 96 samples in one real-time PCR well without loss of sensitivity. As a result, up to 8,820 individual pre-amplified samples could be screened for SARS-CoV-2 within each 96-well plate of realtime PCR using the pooled testing procedure.
The novel semi-nested RT-PCR assay provides a solution for highly multiplex (7-plex) detection of SARS-CoV-2 and enables 96-sample pooled detection for increase of testing capacity.
.
African swine fever virus (ASFV), the causative agent of contagious hemorrhagic disease in domestic pigs and wild boars, has temporally regulated gene expression kinetics. The p30 and p72 major ...structural proteins are involved in viral entry each with different expression kinetics, but neither of their chronological expressions and distribution have been identified in virus-infected animals. Here, we found that both transcription and translation levels of p30 were significantly higher than those of p72 in target organs during the earlier infection-phase. Lymphocyte apoptosis/necrosis and angiectasia were observed as signs of early infection with acute African swine fever. These results show that the chronologically differential expression of ASFV structural proteins tends to be prominent in infected animals, and the p30 protein could play a role in the indication of acute lesions during early infection compared to the late-expressed p72 protein. In conclusion, we propose to consider the chronological expression dynamics of ASFV structural proteins in infected animals to understand virus pathogenesis and antigen targeting for vaccine development.
Heat engines provide most of our mechanical power and are essential for transportation on the macroscopic scale. However, although significant progress has been made in the miniaturization of ...electrostatic engines, it has proved difficult to reduce the size of liquid- or gas-driven heat engines below 107 μm3. Here we demonstrate that a crystalline silicon structure operates as a cyclic piezoresistive heat engine when it is driven by a sufficiently high d.c. current. A 0.34 μm3 engine beam draws heat from the d.c. current using the piezoresistive effect and converts it into mechanical work by expansion and contraction at different temperatures. This mechanical power drives a silicon resonator of 1.1×103 μm3 into sustained oscillation. Even below the oscillation threshold the engine beam continues to amplify the resonator's Brownian motion. When its thermodynamic cycle is inverted, the structure is shown to reduce these thermal fluctuations, therefore operating as a refrigerator. PUBLICATION ABSTRACT
Objective
To assess the magnitude of active and recovering COVID‐19 patients among at‐risk communities and to identify the factors associated with positive serology.
Methods
Four hundred and ...eighty‐three close contacts of COVID‐19 patients residing in Ho Chi Minh City, Vietnam, during the fourth wave of the COVID‐19 epidemic (September and October 2021) were included. Five weeks after exposure to a COVID‐19 patient, they underwent a serology test using the BIOSYNEX COVID‐19 BSS kit.
Results
The median age of participants was 37 years. A total of 34.6% individuals presented at least one clinical symptom between the time of contact with the COVID‐19 patient and inclusion in study. A total of 1.7% unvaccinated individuals tested positive for SARS‐CoV‐2 using real‐time PCR, and 9.5% had evidence of recent infection (positive PCR and/or IgM). A further 26.7% unvaccinated individuals presented evidence of a past infection (positive IgG only). Socio‐demographic characteristics, vaccination status and clinical symptoms were not associated with a positive IgM test.
Conclusion
This is the first serosurvey conducted during the fourth wave of the epidemic in Vietnam. It revealed a seropositivity rate higher than in previous studies and confirmed the hyperendemicity of SARS‐CoV‐2. Testing using rapid serological tests proved to be a reliable, easy‐to‐use method and enabled a rapid estimation of the burden of COVID‐19.
African swine fever is one of the most dangerous diseases of swine. We confirmed the 2019 outbreak in Vietnam by real-time reverse transcription PCR. The causative strain belonged to p72 genotype II ...and was 100% identical with viruses isolated in China (2018) and Georgia (2007). International prevention and control collaboration is needed.
This article presents a novel design of an attitude control system for fixed-wing unmanned aerial vehicles (UAV) based on inverse optimal control theory. The unknown disturbances and model ...uncertainties of the UAV system are estimated using a simple linear disturbance observer. Under reasonable assumptions and a suitable parameter design method, the estimation errors are ensured to be exponentially asymptotically stable. By appending the estimation errors to the state vector and creating a proper virtual control signal, we transformed the original system into disturbance-free linear systems. Thus, inverse optimal control theory is utilized to design an attitude controller by using the backstepping technique. With theoretical results that are mathematically proven, the proposed controller not only ensures asymptotic stability but also reduces the cost function that penalizes both stabilization errors and control inputs without solving the Hamilton-Jacobi-Bellman or Hamilton-Jacobi-Isaacs equation. Finally, simulation scenarios are set up to compare the performances of the proposed scheme with those of other techniques using sliding mode control and the classic PID controller. The simulation results show that the presented inverse optimal controller (IOC) guarantees the best performance in comparison with other approaches.
Sodium ternary layered oxides, typically NaNi
1/3
Mn
1/3
Co
1/3
O
2
(NMC), are layered structures analogous to LiNi
1/3
Mn
1/3
Co
1/3
O
2
, and have been utilized extensively in sodium-ion batteries ...(SIBs). The cathode material was successfully synthesized by a sol-gel process followed by a calcination step at 900 °C for 12 h. The triple-phase integration denoted as P2, O1 and O3 in the NMC sample was evidently revealed on XRD diagrams. The composite cathode material acted as an O3 purity phase that exhibited relatively good performance that delivered an initial capacity of 140 mAh g
−1
and sustained reversible capacities of nearly 110 mAh g
−1
after 100 cycles. The kinetics of sodium intercalation of sol-gel NMC upon reversible Na
+
insertion/de-insertion was evaluated via galvanostatic intermittence titration technique (GITT) and electrochemical impedance spectroscopy (EIS). The diffusion coefficients of Na
+
deduced from the GITT curve were found to lie within a wide range, 10
−9
–10
−12
cm
2
s
−1
for the charge process and 10
−13
–10
−17
cm
2
s
−1
for the discharge process. This implies that the kinetics of Na
+
extraction out of the Na
x
Ni
1/3
Mn
1/3
Co
1/3
O
2
host could be much more favored than Na
+
insertion. Additionally, the evolution of diffusion coefficient and charge transfer resistance are consistent with the complex phase transition generally observed in sodium layered oxides.
The focused confinement method (FCM) is a reaction coordinate-free simulation approach for the calculation of conformational free-energy differences in explicit solvent. The method uses reference ...states for the conformations of interest, partitions the solute into conformationally active and inactive regions, and requires the calculation of desolvation free energies of mixed harmonic–anharmonic states as part of its procedure. The reference states and partitioning affect the speed of convergence of FCM’s constituent simulations in opposing manners, but in the thermodynamic limit, they have no effect on calculated conformational free-energy differences. To aid fast convergence of large systems, a general procedure to quickly partition and construct reference states is introduced. With this, two sets of reference states and associated partitionings were constructed for the closed and open conformation of triosephosphate isomerase (TIM). Despite TIM’s size, highly converged desolvation free energies were readily obtained from standard free-energy perturbation simulations because the mixed harmonic–anharmonic states are heavily rigidified. FCM-calculated free-energy differences for loop closing matched the experimental value for both reference sets. The insensitivity to reference states and associated partitionings favors reference states that merely reflect main structural differences for which convergence is faster. The calculations demonstrate the accuracy and robustness of FCM for large systems.
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