Heterologous expression and characterization of a malathion-hydrolyzing carboxylesterase from a thermophilic bacterium, Alicyclobacillus tengchongensis

A carboxylesterase gene from thermophilic bacterium, Alicyclobacillus tengchongensis, was cloned and expressed in Escherichia coli BL21 (DE3). The gene coded for a 513 amino acid protein with a calculated molecular mass of 57.82 kDa. The deduced amino acid sequence had structural features highly conserved among serine hydrolases, including Ser204, Glu325, and His415 as a catalytic triad, as well as type-B carboxylesterase serine active site (FGGDPENITIGGQSAG) and type-B carboxylesterase signature 2 (EDCLYLNIWTP). The purified enzyme exhibited optimum activity with β-naphthyl acetate at 60 °C and pH 7 as well as stability at 25 °C and pH 7. One unit of the enzyme hydrolyzed 5 mg malathion l(−1) by 50 % within 25 min and 89 % within 100 min. The enzyme strongly degraded malathion and has a potential use for the detoxification of malathion residues

Prognosis of HIV Patients Receiving Antiretroviral Therapy According to CD4 Counts: A Long-term Follow-up study in Yunnan, China

We aim to evaluate the overall survival and associated risk factors for HIV-infected Chinese patients on antiretroviral therapy (ART). 2517 patients receiving ART between 2006 and 2016 were prospectively enrolled in Yunnan province. Kaplan-Meier analyses and Cox proportional hazard regression analyses were performed. 216/2517 patients died during a median 17.5 (interquartile range [IQR] 6.8-33.2) months of follow-up. 82/216 occurred within 6 months of starting ART. Adjusted hazard ratios were10.69 (95%CI 2.38-48.02, p = 0.002) for old age, 1.94 (95%CI 1.40-2.69, p < 0.0001) for advanced WHO stage, and 0.42 (95%CI 0.27-0.63, p < 0.0001) for heterosexual transmission compared to injecting drug users. Surprisingly, adjusted hazard ratios comparing low CD4 counts group (<50 cells/μl) with high CD4 counts group (≥500 cells/μl) within six months after starting ART was 20.17 (95%CI 4.62-87.95, p < 0.0001) and it declined to 3.57 (95%CI 1.10-11.58, p = 0.034) afterwards. Age, WHO stage, transmission route are significantly independent risk factors for ART treated HIV patients. Importantly, baseline CD4 counts is strongly inversely associated with survival in the first six months; whereas it becomes a weak prognostic factor after six months of starting ART

Ultra-Compact Power Splitters with Low Loss in Arbitrary Direction Based on Inverse Design Method

The power splitter is a device that splits the energy from an input signal into multiple outputs with equal or uneven energy. Recently, the use of algorithms to intelligently design silicon-based photonic devices has attracted widespread attention. Thus, many optimization algorithms, which are called inverse design algorithms, have been proposed. In this paper, we use the Direct Binary Search (DBS) algorithm designed with three 1 × 3 power splitters with arbitrary directions theoretically. They have any direction and can be connected to other devices in any direction, which greatly reduces the space occupied by the optical integrated circuit. Through the simulation that comes about, we are able to get the insertion loss (IL) of the device we designed to be less than 5.55 dB, 5.49 dB, and 5.32 dB, separately. Then, the wavelength is 1530–1560 nm, so it can be used in the optical communication system. To discuss the impact of the footprint on device performance, we also designed another device with the same function as the second one from the above three devices. Its IL is less than 5.40 dB. Although it occupies a larger area, it has an advantage in IL. Through the design results, three 1 × 3 power splitters can be freely combined to realize any direction, multi-channel, ultra-compact power splitters, and can be better connected with different devices to achieve different functions. At the same time, we also show an example of a combination. The IL of each port of the combined 1 × 6 power splitter is less than 8.82 dB

Hepatitis D: advances and challenges

Hepatitis D virus (HDV) infection causes the most severe form of viral hepatitis with rapid progression to cirrhosis, hepatic decompensation, and hepatocellular carcinoma. Although discovered > 40 years ago, little attention has been paid to this pathogen from both scientific and public communities. However, effectively combating hepatitis D requires advanced scientific knowledge and joint efforts from multi-stakeholders. In this review, we emphasized the recent advances in HDV virology, epidemiology, clinical feature, treatment, and prevention. We not only highlighted the remaining challenges but also the opportunities that can move the field forward

Regulated Entry of Hepatitis C Virus into Hepatocytes

Hepatitis C virus (HCV) is a model for the study of virus–host interaction and host cell responses to infection. Virus entry into hepatocytes is the first step in the HCV life cycle, and this process requires multiple receptors working together. The scavenger receptor class B type I (SR-BI) and claudin-1 (CLDN1), together with human cluster of differentiation (CD) 81 and occludin (OCLN), constitute the minimal set of HCV entry receptors. Nevertheless, HCV entry is a complex process involving multiple host signaling pathways that form a systematic regulatory network; this network is centrally controlled by upstream regulators epidermal growth factor receptor (EGFR) and transforming growth factor β receptor (TGFβ-R). Further feedback regulation and cell-to-cell spread of the virus contribute to the chronic maintenance of HCV infection. A comprehensive and accurate disclosure of this critical process should provide insights into the viral entry mechanism, and offer new strategies for treatment regimens and targets for HCV therapeutics

Tunable Broadband Terahertz Waveband Absorbers Based on Fractal Technology of Graphene Metamaterial

In this paper, a metasurface Terahertz absorber based on the fractal technology of a graphene geometry resonator to realize ultra-wideband, ultrathin, adjustable double-layer cross-fractal formation is introduced. This paper proposes a dynamically tuned graphene absorbing material. The structure is composed of one- to four-level-fractal graphene pattern layers, MgF2 layers and metal reflective layers to form a two-sided mirror of an asymmetric Fabry&ndash;Perot cavity. To confine the terahertz electromagnetic wave, four different fractals are integrated into a supercell, and the coupling and superposition of adjacent resonant cavities form a broadband high-absorption absorber. Using finite element-based full-wave electromagnetic simulation software to simulate the response frequency of 0.4&ndash;2.0 THz, we found that the absorber achieves a broadband 1.26 THz range (absorption &gt; 80%) and a relative bandwidth of 106.8%. By adjusting the Fermi energy, it can realize free switching and expand to wider broadband terahertz absorption, by adjusting the polarization angle (&Phi;) from 0 to 90&deg; to prove that the structure is not sensitive to polarization, the absorber provides a 60&deg; large angle of incidence, polarization for TE and TM the absorption pattern remains basically the same. Compared with the previous work, our proposed structure uses fractal technology to expand the bandwidth and provide dynamic adjustable characteristics with great degrees of freedom. The appearance of the fractal structure reduces the difficulty of actual processing

Performance analysis of acceleration effect on paraffin melting in finned copper foam

© 2021 Elsevier Ltd. All rights reserved. This is the accepted manuscript version of an article which has been published in final form at https://doi.org/10.1016/j.applthermaleng.2021.117826Phase change material (PCM) has great potential in thermal control of aircraft electronic components because of their excellent latent heat capacity. In the current work, a finned copper foam phase change energy storage unit (PCESU) was fabricated using n-eicosane, 97.2% porosity copper foam and 0.8 mm fins. The effects of four different heating power i.e. 40 W, 45 W, 50 W, 55 W corresponding to heat flux of 0.4 W/cm2, 0.45 W/cm2, 0.5 W/cm2, 0.55 W/cm2 at four different centrifugal acceleration magnitudes, i.e. 0 g, 5 g, 9 g, 13 g with three different acceleration directions on the thermal performance of PCESU were experimentally studied in a systematic manner. Experimental results indicated that: (1) the acceleration direction has a significant effect on the thermal performance of PCESU which can be improved for the cases of vertical and opposite direction, whereas restrained for the case of same direction. Under acceleration condition, the average melting time for the cases of opposite and same direction are 15.19% and 37.10% longer than that for the case of same direction, respectively. The temperature difference of PCESU while the melting is completed is 95.12% higher than that for the case of vertical direction on average. (2) the effect of acceleration magnitude on the heat transfer performance can be determined significantly when the acceleration direction is applied. The melting time decreases with the increase of the acceleration magnitude along vertical direction and increases along the same direction. The temperature difference decreases with the increase of the acceleration magnitude along vertical direction, whereas increases along opposite or same direction. Moreover, the melting time and temperature difference for acceleration magnitude changing from 0 g to 5 g have an obvious larger change rate than that from 5 g to 9 g and 9 g to13 g. (3) the melting time is negatively correlated to the heating power, whereas the temperature difference is positively correlated to the heating power. The proposed two-dimensional (2D) simplified model can be helpful to reveal the physical mechanism of the thermal performance of PCESU.Peer reviewe