Computational Insight into Protein Tyrosine Phosphatase 1B Inhibition: A Case Study of the Combined Ligand- and Structure-Based Approach

Protein tyrosine phosphatase 1B (PTP1B) is an attractive target for treating cancer, obesity, and type 2 diabetes. In our work, the way of combined ligand- and structure-based approach was applied to analyze the characteristics of PTP1B enzyme and its interaction with competitive inhibitors. Firstly, the pharmacophore model of PTP1B inhibitors was built based on the common feature of sixteen compounds. It was found that the pharmacophore model consisted of five chemical features: one aromatic ring (R) region, two hydrophobic (H) groups, and two hydrogen bond acceptors (A). To further elucidate the binding modes of these inhibitors with PTP1B active sites, four docking programs (AutoDock 4.0, AutoDock Vina 1.0, standard precision (SP) Glide 9.7, and extra precision (XP) Glide 9.7) were used. The characteristics of the active sites were then described by the conformations of the docking results. In conclusion, a combination of various pharmacophore features and the integration information of structure activity relationship (SAR) can be used to design novel potent PTP1B inhibitors

Breath-, air- and surface-borne SARS-CoV-2 in hospitals

The COVID-19 pandemic has brought an unprecedented crisis to the global health sector. When discharging COVID-19 patients in accordance with throat or nasal swab protocols using RT-PCR, the potential risk of reintroducing the infection source to humans and the environment must be resolved. Here, 14 patients including 10 COVID-19 subjects were recruited; exhaled breath condensate (EBC), air samples and surface swabs were collected and analyzed for SARS-CoV-2 using reverse transcription-polymerase chain reaction (RT-PCR) in four hospitals with applied natural ventilation and disinfection practices in Wuhan. Here we discovered that 22.2% of COVID-19 patients (n = 9), who were ready for hospital discharge based on current guidelines, had SARS-CoV-2 in their exhaled breath (~10⁵ RNA copies/m³). Although fewer surface swabs (3.1%, n = 318) tested positive, medical equipment such as face shield frequently contacted/used by healthcare workers and the work shift floor were contaminated by SARS-CoV-2 (3–8 viruses/cm²). Three of the air samples (n = 44) including those collected using a robot-assisted sampler were detected positive by a digital PCR with a concentration level of 9–219 viruses/m³. RT-PCR diagnosis using throat swab specimens had a failure rate of more than 22% in safely discharging COVID-19 patients who were otherwise still exhaling the SARS-CoV-2 by a rate of estimated ~1400 RNA copies per minute into the air. Direct surface contact might not represent a major transmission route, and lower positive rate of air sample (6.8%) was likely due to natural ventilation (1.6–3.3 m/s) and regular disinfection practices. While there is a critical need for strengthening hospital discharge standards in preventing re-emergence of COVID-19 spread, use of breath sample as a supplement specimen could further guard the hospital discharge to ensure the safety of the public and minimize the pandemic re-emergence risk

The fourth order diffusion model for a bi-flux mass transfer

A abordagem discreta é empregada para a difusão com retenção para obter a equação de quarta ordem, o que sugere a introdução de um segundo fluxo levando à associação da teoria bi-fluxo com novos parâmetros: fração β e coeficiente de reatividade R. O objetivo desta tese é explorar a Embora comparando o comportamento da concentração e os dois fluxos com o modelo clássico, principalmente pelo método de elementos finitos de Galerkin. Mostra-se que o processo pode ser acelerado ou retardado dependendo da relação entre R e β, para o meio isotrópico. Dependendo da definição do segundo fluxo em função desses parâmetros e da relação β= β(R), o comportamento inesperado aumentando a concentração logo após a introdução de um impulso inicial que se opõe à tendência natural de dispersão, pode se desenvolver em uma recuperação restrita. O coeficiente de reatividade R considerado como um atrator variando no espaço e no tempo de acordo com uma lei de difusão é proposto para simular caixa de nutrientes atraindo partículas biológicas. Finalmente, são apresentados dois casos típicos de difusão não-linear que representam dinâmicas de reações químicas. O modelo bi-fluxo tende a regularizar as soluções.A abordagem discreta é empregada para a difusão com retenção para obter a equação de quarta ordem, o que sugere a introdução de um segundo fluxo levando à associação da teoria bi-fluxo com novos parâmetros: fração β e coeficiente de reatividade R. O objetivo desta tese é explorar a Embora comparando o comportamento da concentração e os dois fluxos com o modelo clássico, principalmente pelo método de elementos finitos de Galerkin. Mostra-se que o processo pode ser acelerado ou retardado dependendo da relação entre R e β, para o meio isotrópico. Dependendo da definição do segundo fluxo em função desses parâmetros e da relação β= β(R), o comportamento inesperado aumentando a concentração logo após a introdução de um impulso inicial que se opõe à tendência natural de dispersão, pode se desenvolver em uma recuperação restrita. O coeficiente de reatividade R considerado como um atrator variando no espaço e no tempo de acordo com uma lei de difusão é proposto para simular caixa de nutrientes atraindo partículas biológicas. Finalmente, são apresentados dois casos típicos de difusão não-linear que representam dinâmicas de reações químicas. O modelo bi-fluxo tende a regularizar as soluções

Calibration of Airborne Interferometric SAR with Single Corner Reflector in Two Converse Flights

Quite a few corner reflectors are essential for interferometric SAR in high precision terrain mapping applications,which limits its application in surveying and mapping industry.In this paper,we present a calibration algorithm of airborne interferometric SAR using single corner reflector in two converse flights.Firstly,based on principle of SAR interferometry,a three-dimensional calibration model considering horizontal and elevation positioning is constructed.Then several characteristic parameters which affect 3D location are analyzed and reduced to three parameters successfully.Finally,we extracted a number of tie points from two groups of complex image pairs in two converse flights by SIFT algorithm.New calibration functions can be developed from the tie points,which helps reduce number of control points.Real data experiments results confirmed the validity and rationality of the proposed algorithm

Forest Height Estimation Based on Constrained Gaussian Vertical Backscatter Model Using Multi-Baseline P-Band Pol-InSAR Data

In the case of low frequencies (e.g., P-band) radar observations, the Gaussian Vertical Backscatter (GVB) model, a model that takes into account the vertical heterogeneity of the wave-canopy interactions, can describe the forest vertical backscatter profile (VBP) more accurately. However, the GVB model is highly complex, seriously reducing the inversion efficiency because of a number of variables. Given that concern, this paper proposes a constrained Gaussian Vertical Backscatter (CGVB) model to reduce the complexity of the GVB model by establishing a constraint relationship between forest height and the backscattering vertical fluctuation (BVF) of the GVB model. The CGVB model takes into account the influence of incidence angle on scattering mechanisms. The BVF of VBP described by the CGVB model is expressed with forest height and a polynomial function of incidence angle. In order to build the CGVB model, this paper proposes the supervised learning based on RANSAC (SLBR). The proposed SLBR method used forest height as a prior knowledge to determine the function of incidence angle in the CGVB model. In this process, the Random Sample Consensus (RANSAC) method is applied to perform function fitting. Before building the CGVB model, iterative weighted complex least squares (IWCLS) is employed to extract the required volume coherence. Based on the CGVB model, forest height estimation was obtained by nonlinear least squares optimization. E-SAR P-band polarimetric interferometric synthetic aperture radar (Pol-InSAR) data acquired during the BIOSAR 2008 campaign was used to test the performance of the proposed CGVB model. It can be observed that, compared with Random Volume over Ground (RVoG) model, the proposed CGVB model improves the estimation accuracy of the areas with incidence angle less than 0.8 rad and less than 0.6 rad by 28.57 % and 40.35 % , respectively

Investigating the Relationship between Coupling Forces and Hand-Transmitted Vibration under Varying Excitation Levels

In this study, the vibration total value of the acceleration transmitted to the wrist and elbow was measured in the laboratory with a group of 13 male subjects holding a cylindrical handle while modifying the coupling force under varying levels of vibration. The results were used to establish the relationship between hand-transmitted vibration and coupling forces and to compare with the relations proposed as part of an ISO Technical Specification, ISO/TS 15230-2. This was done to determine the suitability of the proposed relationships when variations are introduced on the level of vibration on the handle. While tracing back the origins of the relations proposed in ISO/TS 15230-2, this paper further brings in evidence of the importance of considering the role of coupling forces when evaluating the exposure to hand-transmitted vibration and provides additional evidence to support the relationships which are proposed as part of the ISO Technical Specification. Irrespective of the level of broadband random vibration excitation considered, the agreement with these relationships was found to be best when setting the reference coupling force at 50, 75, 100 and 125 N and whenever the coupling forces applied on the handle were maintained below 150 N

Thermal behaviors and regeneration of activated carbon saturated with toluene induced by microwave irradiation

Microwave irradiation is an effective way to regenerate the activated carbon after adsorption and separation of waste. In this work, activated carbon saturated with toluene was efficiently regenerated by microwave irradiation. The maximum regeneration ratio of 77.2% was obtained under the following optimal operation conditions: saturated activated carbon of 5.01 g, microwave power of 500 W, carrier gas N₂ flow of 60 mL/min, and microwave irradiation time of 180 s. It was found that the higher microwave power may result in self-burning of activated carbon due to the presence of traces of oxygen, which might slightly deteriorate the pore structures of activated carbon. On the other hand, the lower microwave power cannot start desorption of toluene or might cause re-adsorption. The introduction of N₂ flow during regeneration was necessary to release the desorbed toluene from activated carbon, but it might cool the adsorption system under a much higher N₂ flow rate.5 page(s