A label-free H1N1 influenza virus immunosensor based on an N-LIG/Au laser induced graphene microelectrode.

A label-free immunosensor based on an N-doped laser direct graphene (N-LIG)/Au electrode was proposed for H1N1 influenza virus detection. By utilizing the instantaneous high temperature of laser irradiation, N atoms are generated by the decomposition of melamine dripped onto the surface of an LIG electrode to obtain N-LIG with higher conductivity. The doping of N atoms provides a large number of active sites for LIG microelectrodes. Combined with the electrodeposition of Au NPs, and covalently crosslinking antibodies, a simple, highly sensitive and stable immunosensing interface is constructed. The proposed H1N1 influenza virus immunosensor has a detection range of 0.01 fg mL-1 to 10 ng mL-1 with a detection limit as low as 0.004 fg mL-1. The constructed sensor has ultra-high sensitivity and good selectivity and can be used for complex biological sample analysis, with potential application prospects in preventing the large-scale spread of influenza. Taking advantage of N-LIG electrode's properties will provide opportunities for developing portable electrochemical biosensors for health and environmental applications.

Natural variation in OsSEC13 HOMOLOG 1 modulates redox homeostasis to confer cold tolerance in rice.

Rice (Oryza sativa L.) is a cold-sensitive species that often faces cold stress, which adversely affects yield productivity and quality. However, the genetic basis for low-temperature adaptation in rice remains unclear. Here, we demonstrate that 2 functional polymorphisms in O. sativa SEC13 Homolog 1 (OsSEH1), encoding a WD40-repeat nucleoporin, between the 2 subspecies O. sativa japonica and O. sativa indica rice, may have facilitated cold adaptation in japonica rice. We show that OsSEH1 of the japonica variety expressed in OsSEH1MSD plants (transgenic line overexpressing the OsSEH1 allele from Mangshuidao [MSD], cold-tolerant landrace) has a higher affinity for O. sativa metallothionein 2b (OsMT2b) than that of OsSEH1 of indica. This high affinity of OsSEH1MSD for OsMT2b results in inhibition of OsMT2b degradation, with decreased accumulation of reactive oxygen species and increased cold tolerance. Transcriptome analysis indicates that OsSEH1 positively regulates the expression of the genes encoding dehydration-responsive element-binding transcription factors, i.e. OsDREB1 genes, and induces the expression of multiple cold-regulated genes to enhance cold tolerance. Our findings highlight a breeding resource for improving cold tolerance in rice.

Models to assess imported cases on the rebound of COVID-19 and design a long-term border control strategy in Heilongjiang Province, China.

Since the outbreak of COVID-19 in Wuhan, China in December 2019, it has spread quickly and become a global pandemic. While the epidemic has been contained well in China due to unprecedented public health interventions, it is still raging or not yet been restrained in some neighboring countries. Chinese government adopted a strict policy of immigration diversion in major entry ports, and it makes Suifenhe port in Heilongjiang Province undertook more importing population. It is essential to understand how imported cases and other key factors of screening affect the epidemic rebound and its mitigation in Heilongjiang Province. Thus we proposed a time switching dynamical system to explore and mimic the disease transmission in three time stages considering importation and control. Cross validation of parameter estimations was carried out to improve the credibility of estimations by fitting the model with eight time series of cumulative numbers simultaneous. Simulation of the dynamics shows that illegal imported cases and imperfect protection in hospitals are the main reasons for the second epidemic wave, the actual border control intensities in the province are relatively effective in early stage. However, a long-term border closure may cause a paradox phenomenon such that it is much harder to restrain the epidemic. Hence it is essential to design an effective border reopening strategy for long-term border control by balancing the limited resources on hotel rooms for quarantine and hospital beds. Our results can be helpful for public health to design border control strategies to suppress COVID-19 transmission.

Multi-omics approach reveals the contribution of OsSEH1 to rice cold tolerance.

As low environmental temperature adversely affects the growth, development and geographical distribution, plants have evolved multiple mechanisms involving changing physiological and metabolic processes to adapt to cold stress. In this study, we revealed that nucleoporin-coding gene OsSEH1 was a positive regulator of cold stress in rice. Physiological assays showed that the activity of antioxidant enzymes showed a significant difference between osseh1 knock-out lines and wild type under cold stress. Metabolome analysis revealed that the contents of large-scale flavonoids serving as ROS scavengers were lower in osseh1 mutants compared with wild type under cold stress. Transcriptome analysis indicated that the DEGs between osseh1 knock-out lines and wild type plants were enriched in defense response, regulation of hormone levels and oxidation-reduction process. Integration of transcriptomic and metabolic profiling revealed that OsSEH1 plays a role in the oxidation-reduction process by coordinately regulating genes expression and metabolite accumulation involved in phenylpropanoid and flavonoid biosynthetic pathway. In addition, Exogenous ABA application assays indicated that osseh1 lines had hypersensitive phenotypes compared with wild type plants, suggesting that OsSEH1 may mediate cold tolerance by regulating ABA levels.

Government's subsidisation policy and utilisation of smoking cessation treatments: a population-based cross-sectional study in Taiwan.

OBJECTIVES: This study examined the associations between the Second-Generation Cessation Payment Scheme (SCPS) and the use of smoking cessation treatments. Furthermore, these associations were compared between light and heavy smokers in Taiwan. DESIGN: This study had a cross-sectional design. SETTING: Data were obtained from the Taiwan Adult Smoking Behaviour Surveillance System 2010-2011 and 2013-2014; data for each year consisted of a nationally representative sample of adults aged 18 years and older. PARTICIPANTS: Current smokers who had either quit or made a serious attempt to quit smoking were selected for the analysis. PRIMARY OUTCOME MEASURE: The primary outcome measure was the use of a smoking cessation clinic or pharmacy in a twice daily to quit smoking. RESULTS: According to multivariate analysis, the SCPS was positively associated with the combined use of a smoking cessation clinic and a pharmacy (OR=3.947; 95% CI: 1.359 to 11.463) when individual-level predictors (gender, age, education level, marital status, monthly household income, daily cigarette consumption, smoking status and self-reported health) were controlled. Heavy smokers showed a significant increase in the sole use of a pharmacy (OR=1.676; 95% CI: 1.094 to 2.569) and combined use of a smoking cessation clinic and pharmacy (OR=8.984; 95% CI: 1.914 to 42.173) after the SCPS was introduced. In addition, when related factors were controlled, the use of smoking cessation services was more frequent among heavy smokers than light smokers, including any treatment (OR=1.594; 95% CI: 1.308 to 1.942), a smoking cessation clinic (OR=1.539; 95% CI: 1.232 to 1.922), a pharmacy (OR=1.632; 95% CI: 1.157 to 2.302) and the combination of a smoking cessation clinic and pharmacy (OR=4.608; 95% CI: 1.331 to 15.949) . CONCLUSIONS: The SCPS subsidisation policy increased the use of smoking cessation treatments, particularly among heavy smokers.

Entry guidance for high-L/D hypersonic vehicle based on drag-vs-energy profile.

To steer a hypersonic vehicle of high Lift-to-Drag ratio (L/D) safely and accurately, a new entry guidance is proposed based on drag-vs-energy profile. Over the rotating Earth, by assessing the nonlinear inertial forces reasonably, an accurate analytical glide-range formula is derived for formulaic drag profile. Then the reference drag-vs-energy profile is planned by utilizing the new formula in the entry corridor satisfying stress and thermal constraints. In order to closely track the reference profile, the Trajectory Damping Control Technique (TDCT) is adopted to suppress the underdamped, phugoid trajectory oscillations. The key to this technique is that the Analytical Formula of Flight-Path Angle for Steady Glide (AFFPASG) can maintain a high accuracy even if the vehicle deviates from the steady-glide condition greatly. This paper attempts to take a theoretical analysis on this interesting phenomenon though the expression of AFFPASG is complicated. By reviewing the derivation process of the AFFPASG carefully, we dig out its error sources and evaluate their influence on accuracy. As a conclusion, the fundamental cause of that key characteristic is that the Steady-Glide Flight-Path Angle (SGFPA) is the flight-path angle keeping the minimum change rate of the vertical component of the resultant of the external forces including the centrifugal force resulting from the Earth curvature, instead of the one making the vertical net force zero.

Mechanotransduction of matrix stiffness in regulation of focal adhesion size and number: reciprocal regulation of caveolin-1 and ß1 integrin.

Focal adhesion (FA) assembly, mediated by integrin activation, responds to matrix stiffness; however, the underlying mechanisms are unclear. Here, we showed that ß1 integrin and caveolin-1 (Cav1) levels were decreased with declining matrix stiffness. Soft matrix selectively downregulated ß1 integrin by endocytosis and subsequent lysosomal degradation. Disruption of lipid rafts with methyl-ß-cyclodextrin or nystatin, or knockdown of Cav1 by siRNA decreased cell spreading, FA assembly, and ß1 integrin protein levels in cells cultured on stiff matrix. Overexpression of Cav1, particularly the phospho-mimetic mutant Cav1-Y14D, averted soft matrix-induced decreases in ß1 integrin protein levels, cell spreading, and FA assembly in NMuMG cells. Interestingly, overexpression of an auto-clustering ß1 integrin hindered soft matrix-induced reduction of Cav1 and cell spreading, which suggests a reciprocal regulation between ß1 integrin and Cav1. Finally, co-expression of this auto-clustering ß1 integrin and Cav1-Y14D synergistically enhanced cell spreading, and FA assembly in HEK293T cells cultured on either stiff ( > G Pa) or soft (0.2 kPa) matrices. Collectively, these results suggest that matrix stiffness governs the expression of ß1 integrin and Cav1, which reciprocally control each other, and subsequently determine FA assembly and turnover.

Omnidirectional autonomous entry guidance based on 3-D analytical glide formulas.

An autonomous entry guidance law is developed based on 3-D analytical glide formulas, where the downrange formula is used to plan the longitudinal reference profile in order to meet the downrange and final energy requirements, and the crossrange formula is used to regulate the bank reversals in order to eliminate the crossrange error. As the analytical glide formulas ignore the effects of the Earth׳s rotation, a series of strategies is proposed for compensating these effects, which provides the guidance with the capability of steering the hypersonic glide vehicle with high Lift to Drag ratio (L/D) to any place of the world accurately. The compensation strategies can be summarized into two parts: (1) the reference profiles are properly adjusted by roughly evaluating the effects of the Earth׳s rotation on the aerodynamic profiles over the whole flight, which can compensate most of the effects; (2) the current effects are accurately evaluated and then the guidance commands are slightly modulated for compensating the remaining effects. Due to careful design, the strategies will not result in drastic changes in the Angle of Attack (AOA) and can keep the bank angle almost constant during most of flight.

Matrix-Stiffness-Regulated Inverse Expression of Krüppel-Like Factor 5 and Krüppel-Like Factor 4 in the Pathogenesis of Renal Fibrosis.

The proliferation of mouse proximal tubular epithelial cells in ex vivo culture depends on matrix stiffness. Combined analysis of the microarray and experimental data revealed that Krüppel-like factor (Klf)5 was the most up-regulated transcription factor accompanied by the down-regulation of Klf4 when cells were on stiff matrix. These changes were reversed by soft matrix via extracellular signal-regulated kinase (ERK) inactivation. Knockdown of Klf5 or forced expression of Klf4 inhibited stiff matrix-induced cell spreading and proliferation, suggesting that Klf5/Klf4 act as positive and negative regulators, respectively. Moreover, stiff matrix-activated ERK increased the protein level and nuclear translocation of mechanosensitive Yes-associated protein 1 (YAP1), which is reported to prevent Klf5 degradation. Finally, in vivo model of unilateral ureteral obstruction revealed that matrix stiffness-regulated Klf5/Klf4 is related to the pathogenesis of renal fibrosis. In the dilated tubules of obstructed kidney, ERK/YAP1/Klf5/cyclin D1 axis was up-regulated and Klf4 was down-regulated. Inhibition of collagen crosslinking by lysyl oxidase inhibitor alleviated unilateral ureteral obstruction-induced tubular dilatation and proliferation, preserved Klf4, and suppressed the ERK/YAP1/Klf5/cyclin D1 axis. This study unravels a novel mechanism how matrix stiffness regulates cellular proliferation and highlights the importance of matrix stiffness-modulated Klf5/Klf4 in the regulation of renal physiologic functions and fibrosis progression.

Trajectory-Shaping Guidance with final speed and load factor constraints.

This paper describes the design of a guidance law used for guiding a hypersonic gliding vehicle against a ground target from a near-vertical orientation with a specified final speed and a near-zero final load factor. The guidance law consists of two terms: one is Trajectory-Shaping Guidance (TSG) used for steering the vehicle to the target from the specified orientation; the other is Final-Speed-Control Scheme (FSCS) used for controlling the vehicle to perform lateral maneuver to adjust the final speed. Further, the generalized closed form solutions of TSG are obtained from a more general linearized engagement model, where the speed of the vehicle can be an arbitrary positive function of time. By analyzing these solutions, the stability domain of the guidance coefficients is obtained such that the final load factor is zero. This domain is not affected by the change rate of the speed. Thus, according to this analysis, the proposed guidance law can achieve a near zero final load factor by properly selecting the guidance coefficients in the stability domain.

Regulation of proximal tubular cell differentiation and proliferation in primary culture by matrix stiffness and ECM components.

To explore whether matrix stiffness affects cell differentiation, proliferation, and transforming growth factor (TGF)-ß1-induced epithelial-mesenchymal transition (EMT) in primary cultures of mouse proximal tubular epithelial cells (mPTECs), we used a soft matrix made from monomeric collagen type I-coated polyacrylamide gel or matrigel (MG). Both kinds of soft matrix benefited primary mPTECs to retain tubular-like morphology with differentiation and growth arrest and to evade TGF-ß1-induced EMT. However, the potent effect of MG on mPTEC differentiation was suppressed by glutaraldehyde-induced cross-linking and subsequently stiffening MG or by an increasing ratio of collagen in the soft mixed gel. Culture media supplemented with MG also helped mPTECs to retain tubular-like morphology and a differentiated phenotype on stiff culture dishes as soft MG did. We further found that the protein level and activity of ERK were scaled with the matrix stiffness. U-0126, a MEK inhibitor, abolished the stiff matrix-induced dedifferentiation and proliferation. These data suggest that the ERK signaling pathway plays a vital role in matrix stiffness-regulated cell growth and differentiation. Taken together, both compliant property and specific MG signals from the matrix are required for the regulation of epithelial differentiation and proliferation. This study provides a basic understanding of how physical and chemical cues derived from the extracellular matrix regulate the physiological function of proximal tubules and the pathological development of renal fibrosis.

Neural network assisted inverse dynamic guidance for terminally constrained entry flight.

This paper presents a neural network assisted entry guidance law that is designed by applying Bézier approximation. It is shown that a fully constrained approximation of a reference trajectory can be made by using the Bézier curve. Applying this approximation, an inverse dynamic system for an entry flight is solved to generate guidance command. The guidance solution thus gotten ensures terminal constraints for position, flight path, and azimuth angle. In order to ensure terminal velocity constraint, a prediction of the terminal velocity is required, based on which, the approximated Bézier curve is adjusted. An artificial neural network is used for this prediction of the terminal velocity. The method enables faster implementation in achieving fully constrained entry flight. Results from simulations indicate improved performance of the neural network assisted method. The scheme is expected to have prospect for further research on automated onboard control of terminal velocity for both reentry and terminal guidance laws.

Detection of real sample DNA at a cadmium sulfide--chitosan/gelatin modified electrode.

Cadmium sulfide (CdS) was combined with chitosan (Chi) and gelatin (Gel) to prepare a CdS-Chi/Gel modified electrode. Chi exhibits a large positive charge density and was to provide a uniform of CdS surface. Gel exhibits high mechanical strength and low toxicity toward mammalian cells, and is non-antigenic biopolymer. CdS-Chi exhibits a lower contact angle than that of bare CdS, indicating that the hydrophilicity of the sample surface had increased. Electrochemical impedance spectroscopy (EIS) was used to determine diffusion coefficients and to characterize the electron transfer kinetics during the redox reactions. The surface morphologies of CdS-Chi and Gel were characterized using scanning electron microscopy (SEM) and atomic force microscopy (AFM). Differential pulse voltammetry (DPV) was used to detect the analytes. DPV not only increased the linear range of the electrocatalytic current, but also lowered the overpotential for oxidation interference in the measurements. The CdS electrode exhibited a enhanced electrocatalytic activity toward the analytes evaluated in this study. The presence of Gel enhanced the loading and stability of the electrode. The fabricated electrode was successfully used for the simultaneous electrochemical oxidation of guanine (G) and adenine (A).

Enhancement of renal epithelial cell functions through microfluidic-based coculture with adipose-derived stem cells.

Current hemodialysis has functional limitations and is insufficient for renal transplantation. The bioartificial tubule device has been developed to contribute to metabolic functions by implanting renal epithelial cells into hollow tubes and showed a higher survival rate in acute kidney injury patients. In healthy kidney, epithelial cells are surrounded by various types of cells that interact with extracellular matrices, which are primarily composed of laminin and collagen. The current study developed a microfluidic coculture platform to enhance epithelial cell function in bioartificial microenvironments with multiple microfluidic channels that are microfabricated by polydimethylsiloxane. Collagen gel (CG) encapsulated with adipose-derived stem cells (CG-ASC) was injected into a central microfluidic channel for three-dimensional (3D) culture. The resuspended Madin-Darby canine kidney (MDCK) cells were injected into nascent channels and formed an epithelial monolayer. In comparison to coculture different cells using the commercial transwell system, the current coculture device allowed living cell monitoring of both the MDCK epithelial monolayer and CG-ASC in a 3D microenvironment. By coculture with CG-ASC, the cell height was increased with columnar shapes in MDCK. Promotion of cilia formation and functional expression of the ion transport protein in MDCK were also observed in the cocultured microfluidic device. When applying fluid flow, the intracellular protein dynamics can be monitored in the current platform by using the time-lapse confocal microscopy and transfection of GFP-tubulin plasmid in MDCK. Thus, this microfluidic coculture device provides the renal epithelial cells with both morphological and functional improvements that may avail to develop bioartificial renal chips.

[Inhibition of remineralization by EDTA-soluble phosphate protein in dentin].

OBJECTIVE: To investigate the effect of removing EDTA-soluble phosphate protein in dentin on the later remineralization for the purpose of better understanding of mechanism of dentin phosphate proteins on dentin mineralization. METHODS: To remove soluble phosphate protein by EDTA dissolution, then the remineralization rate was monitored by a constant composition crystal growth technique. The results were compared with those from the normal dentin and the dentin partially demineralized by acetic acid. RESULTS: Faster remineralization rates were found with dentin demineralized by EDTA (0.5 and 2 h) compared with normal dentin powder, while a slower rate was found with dentin demineralized by acetic acid. The increase of remineralization rate by removing phosphate protein from dentin was 100% more at 200 min after the start of the reaction. CONCLUSION: EDTA-soluble phosphate protein in dentin has a great potential to inhibit remineralization.