Search

Antiplatelet treatment (APT) has been reported to be used in some patients with aneurysmal subarachnoid hemorrhage (aSAH) after endovascular treatment, but there is controversy among different studies regarding its clinical effects. This study intends to conduct a meta-analysis to evaluate the impact of APT on aSAH patients after endovascular treatment. The PubMed, EMBASE, and Cochrane Library databases were systematically searched up to January 2022 for eligible English publications. Quality assessment was conducted for the included studies. Publication bias and heterogeneity were assessed by Egger's test and the I

During the manufacture of plastic micro-pipe, a certain volume of gas should be properly injected into the inner cavity to overcome the collapse and adhesion problems. In this work, the extrusion forming of plastic micro-tube under the role of inner cavity’s gas were numerically studied. At the same time, the effect of inner cavity’s gas flow rate on the extrusion deformation of plastic micro-pipe was also numerically investigated by using the finite element method. A kind of 2D two-phase fluid geometric model and finite element mesh were established and some reasonable boundary conditions and material parameters were imposed. Under a fixed volume flow rate of melt, different flow rates of inner cavity gas were imposed on the inlet of inner cavity’s gas. The extrusion deformation profile and deformation ratio of plastic micro-pipe under different flow rates of gas were all obtained. To ascertain the mechanisms of effect of inner cavity’s gas flow rate on the extrusion deformation of plastic micro-tube, the flow velocities, pressure, shear rate, normal stress, and the first normal stress difference of melt all obtained and analyzed. Numerical results show that with the increase of inner cavity’s gas flow rate, the radial velocity, axial velocity, pressure, shear rate, normal stress, and the first normal stress difference of melt all increase, which makes the extrusion deformation become more and more serious. In practice, reasonable controlling of the inner cavity’s gas flow rate is very important. In the other hand, it can adjust the size of extruded plastic micro-pipe.

The hexametric T7 helicase (gp4) adopts a spiral lock-washer form and encircles a coil-like DNA (tracking) strand with two nucleotides bound to each subunit. However, the chemo-mechanical coupling mechanism in unwinding has yet to be elucidated. Here, we utilized nanotensioner-enhanced Förster resonance energy transfer with one nucleotide precision to investigate gp4-induced unwinding of DNA that contains an abasic lesion. We observed that the DNA unwinding activity of gp4 is hindered but not completely blocked by abasic lesions. Gp4 moves back and forth repeatedly when it encounters an abasic lesion, whereas it steps back only occasionally when it unwinds normal DNA. We further observed that gp4 translocates on the tracking strand in step sizes of one to four nucleotides. We propose that a hypothetical intermediate conformation of the gp4–DNA complex during DNA unwinding can help explain how gp4 molecules pass lesions, providing insights into the unwinding dynamics of gp4.

To ascertain the influence of gases temperature on the viscosity and flow velocity of melt in the gas-assisted extrusion forming of plastic micro-tube, the three phase fluid geometric model was established and the finite element numerical simulation method was used in this paper. In the simulations, four different assisted-gases temperatures were imposed on the inlet boundaries of inner and outer assisted gas layers. Under a certain inlet volume flow rate of melt and assisted gases, as well as the thermal boundaries conditions, the numerical results about the effect of gases temperature on the viscosity and flow velocity of melt for the gas-assisted extrusion forming of the plastic micro-tube were obtained. Results show that with the increase of gases temperature, the viscosity distribution of melt in the radial direction of die channel decreases. However, at the axial direction of die channel, when the gases temperature is less than that of the melt, the viscosity of melt increases first and then decreases finally increases outside of die. When the gases temperature is larger than that of melt, the viscosity of melt decreases first and then increases finally increases outside of die. In addition, the flow velocity of melt increases with the gases temperature.

Thermodynamics and structural transitions on protein surfaces remain relatively understudied and poorly understood. Wrapping of DNA on proteins provides a paradigm for studying protein surfaces. We used magnetic tweezers to investigate a prototypical DNA-interacting protein, i.e., the single-stranded DNA binding protein (SSB). SSB binds DNA with distinct binding modes the mechanism of which is still elusive. The measured thermodynamic parameters relevant to the SSB-DNA complex are salt-dependent and discontinuous at the bind-mode transitions. Our data indicate that free SSB undergoes salt-induced first-order structural transitions. The conclusion was supported by the infrared spectroscopy of SSB in salt solutions. Ultrafast infrared spectroscopy further suggests that the transitions are correlated with surface salt bridges. Our work not only unravels a long-standing mystery of the different binding site sizes of SSB, but also would inspire interests in thermodynamics of protein surfaces.

The effects of four difference viscoelastic constitutive parameters, i.e., viscosity, relaxation time, ε and ξ on the extrudate swell of plastic micro-tubes were studied by using the numerical method. Numerical results show that the extrudate swell of plastic micro-tube increases with the increase of the relaxation time, but decreases with the increase of ε and ξ. In addition, the extrudate swell ratio of plastic micro-tube is not changed with the increase of the viscosity of melt. To ascertain the effect of four different viscoelastic constitutive parameters on the extrudate swell of plastic micro-tube, the physical field distributions, i.e., flow velocity, shear rate, shear stress, and first normal stress difference distributions of melt were obtained, respectively. Results show that the extrudate swell phenomenon of plastic micro-tube is closely dependent on the elastic energy storage of melt induced by the above mentioned physical field distributions, especially at the outlet of die.

Tracking membrane-interacting molecules and visualizing their conformational dynamics are key to understanding their functions. It is, however, challenging to accurately probe the positions of a molecule relative to a membrane. Herein, a single-molecule method, termed LipoFRET, is reported to assess interplay between molecules and liposomes. It takes advantage of FRET between a single fluorophore attached to a biomolecule and many quenchers in a liposome. This method was used to characterize interactions between α-synuclein (α-syn) and membranes. These results revealed that the N-terminus of α-syn inserts into the membrane and spontaneously transitions between different depths. In contrast, the C-terminal tail of α-syn is regulated by calcium ions and floats in solution in two conformations. LipoFRET is a powerful tool to investigate membrane-interacting biomolecules with sub-nanometer precision at the single-molecule level.

According to the properties of hollow square-typed polymer extrudate, the three dimensional numerical simulation of hollow square-typed polymer extrudate based on gas-assisted extrusion technology was performed by using finite element method. Meanwhile, four different gas-assisted modes imposed on the outer and inner wall of hollow square-type extrudate were considered. The extrudate swell ratios and field distributions, such as pressure drop, velocities and normal stresses of four different gas-assisted modes were obtained and compared with each other. Research results show that the extrudate swell ratios and field distributions of different gas-assisted modes are completely different. For the mode of gas-assisted on the single wall, the extrudate swell or shrink phenomena are large due to the non-symmetric properties of field distributions. For the no gas-assisted mode, although the physical field values are large, the extrudate swell ratio is not large due to the interaction role of both walls. For the mode of gas-assisted on both walls, the physical field values, such as pressure drop, normal velocities and stresses are all diminished, and the extrudate swell phenomenon was completely eliminated.

Homologous recombination (HR) which is important for maintaining the genetic stability of the cell is mainly mediated by recombinase. As a critical recombinase exists in prokaryotic organism, RecA has been widely studied. RecA could bind single strand DNA to form a filament structure to perform strand invasion and exchange with homologous DNA. The basic strand exchange step is a pathway to investigating the mechanism of strand exchange process. However, the specific step length is still controversial. The mainstream view is to regard the basic step as 3 bp, which sounds reasonable because the basic unit of RecA filament is a RecA monomer which binds 3 base pairs, but our previous study found that the most probable basic strand exchange step is 9 bp. In this research, we set up a series of experiments to demonstrate that the basic strand exchange step is 9 bp and how the mismatch base pairs in 9 bp affect the strand exchange process. We ues digestion protection to confirm whether the strand exchange process is completed and we employ a magnetic tweezer to measure how many base pairs are exchanged by strand exchange process. The digestion protection experiments show the strand exchange cannot overcome 33% mismatch sequence, but according to the result that strand exchange could overcome a single mismatch base pair, so that the step is not 3 bp. According to strand exchange length of 33% mismatch sequence, we find a 9 bp interval between the main peaks, which implies that the strand exchange step should be 9 bp rather than 3 bp. We also use continuous mismatch base pairs instead of periodic mismatch sequence to see whether the strand exchange process can be overcome. We find that the more the mismatch base pairs, the harder the strand exchange process passes across. Homology degree and its distribution both affect the strand exchange process. In general, the results suggest that the strand exchange step mediated by RecA is 9 bp, and the number of mismatched base pairs and their distribution influence the strand exchange process. The combination of digestion protection assay and magnetic tweezers can further take advantage of single molecule techniques to investigate mechanism of HR.

Touch interaction is usually implemented on a computer screen or a projected surface. However, tactile quality of paper is attractive and intuitive for people to manipulate in traditional paintings and storytelling. In order to enable touch interaction on paper, we present MagicPAPER, a shadow-art device that consists of a pen, kraft paper, a projector, a gesture sensing device, and a software system. With the purpose of illustrating how MagicPAPER effectively integrates the art-design process with the computer and communication technology, we have developed eight interactive applications simply based on kraft paper and mark pen: the Dimension Door, Balls, Palette, Flat Cube, Piano, Color potion, Fast mask- changing, and Candle. Finally, we experimented with MagicPAPER and demonstrated its interactive effects by detecting the gesture of a finger and pen on kraft paper and projecting it into eight interactive applications. Our research results show that MagicPAPER successfully carries out paper-based touch interactions.

Helicases harness the energy of nucleotide triphosphate hydrolysis to unwind double-stranded DNA (dsDNA) in discrete steps. In spite of intensive studies, the mechanism of stepping is still poorly understood. Here, we applied single-molecule fluorescent resonant energy transfer to characterize the stepping of two nonring helicases, Escherichia coli RecQ ( E. coli RecQ) and Saccharomyces cerevisiae Pif1 (ScPif1). Our data showed that when forked dsDNA with free overhangs are used as substrates, both E. coli RecQ and ScPif1 unwind the dsDNA in nonuniform steps that distribute over broad ranges. When tension is exerted on the overhangs, the overall profile of the step-size distribution of ScPif1 is narrowed, whereas that of E. coli RecQ remains unchanged. Moreover, the measured step sizes of the both helicases concentrate on integral multiples of a half base pair. We propose a universal stepping mechanism, in which a helicase breaks one base pair at a time and sequesters the nascent nucleotides and then releases them after a random number of base-pair breaking events. The mechanism can interpret the observed unwinding patterns quantitatively and provides a general view of the helicase activity.

Based on generalized non-Newtonian fluid with seven parameters Cross-WLF viscosity model and modified 2-domain Tait model, the injection process of short glass fiber-reinforced polypropylene is simulated with a true 3D model. The effects of gate location on clamp force, fiber orientation and parts deformation are investigated. The results show that: (1) Clamp force of the 3rd scheme that gate location is set on the center of long-side is the largest and that of the 1st scheme that gate location is set on the center of top is the smallest. (2)Because of shear stress, in the direction of thickness, the distributions of fiber orientation are layered orderly, namely, the degree of fiber orientation in core layer is the lowest, but that in subsurface layer is the highest. While perpendicular to the shear flow, the layering distribution isn’t obvious. (3) Compared the three schemes in respect of clamp force and parts deflection, the 3rd scheme is the poorest, which should not be adopted as can as possible, while the 1st scheme and 2nd scheme are reasonable.

Based on the incompressible smoothed particle hydrodynamics (ISPH) method, a program was developed to simulate the non-Newtonian fluid flow in the mixing section of a single screw extruder. The transverse flow in the extruder is mimicked by one 2-D lid-driven cavity flow. The mirror particles are used to treat boundary. The power-law model is used to calculate the viscosity of the fluid. The shear-thinning, the shear-thickening and Newtonian fluid in the single screw extruder are simulated and deeply analyzed. Through comparing the velocity profile along the centre of screw extruder with the theoretical solution, this method has been proven to be accurate and effective. It laid the foundation for the simulating of the more complex 3-D model.

Based on generalized non-Newtonian fluid with seven parameters Cross-WLF viscosity model and modified 2-double Tait model, the numerical simulation was carried out for the short glass fiber reinforced PP injection molding process of rectangular part. The influence of main process parameters on fiber orientation is investigated. The results show that fiber orientation can be generally divided into three-regional layers in injection molding, that is outer-surface, subsurface and core layer. The degree of fiber orientation in subsurface layer is the highest and that in core layer is the lowest. The influence of fibers interaction coefficient (Ci) and fibers aspect ratio (re) on fiber orientation is significant. There is obvious difference between simulation results and practical results without consideration of Ci. The effect of melt temperature, mold temperature and cooling tubes number on fiber orientation isn’t obvious.

One forced revolving moving boundary problem model was constructed and simulated by incompressible SPH (ISPH). The dummy particles are used to deal the moving boundary. The tensile instability is avoided by setting a reference pressure. Compared with the results produced by FLUENT, the method was proved to be more practical and effective. The method is applicable to the more complex 3D model.

How to deal with the relationship between the organization and employees is the core of Human Resource Management in today's society. In recent years employee dismission rate in IT industry in China is very high, one of the causes of which is their low organizational commitment. Therefore, it is of great strategic and practical significance to promote employees' organizational commitment in IT industry. Human resource practice has an obvious influence on organizational commitment and the latter in turn predicts business performance. Thus, this research will benefit IT enterprises by finding out the reason for employee's turnover and putting forward appropriate countermeasures.

Activity coefficients for rubidium chloride in the (RbCl + RbNO3 + H2O) ternary system were determined from electromotive force (emf) measurements of the cell: Rb - ion selective electrode ( ISE ) | RbCl ( m A ) , RbNO 3 ( m B ) , H 2 O | Ag | AgCl at T = 298.15 K and over total ionic strengths from (0.01 upto 3.50) mol · kg−1. The Rb+ ion selective electrode (Rb-ISE) and Ag|AgCl electrode used in this work were made in our laboratory and had reasonably good Nernst responses, which demonstrate that the emf method can be applied to measure the above system with high precision. The experimental data were analyzed using the Harned rule and Pitzer model. The Harned coefficients and the Pitzer binary and ternary ionic interaction parameters for the system have been evaluated. The experimental results obey the Harned rule, and the Pitzer model can be used to describe this aqueous system satisfactorily. The activity coefficients of RbNO3, the osmotic coefficients of the mixtures and the excess free energy of mixing were also calculated.

INF-lambda has anti-viral and anti-tumor activities. Its application in viral myocarditis (VMC) has not been reported. This study investigated the role of INF-lambda in acute VMC in mice.Forty mice were randomly divided into three groups: VMC (n=15), IFN-lambda2-treated VMC (n=15) and control (n=10). VMC was induced by an intraperitoneal injection of Coxsackievirus B3 (CVB3).The control group was intraperitoneally injected with 2% PBS. The IFN-lambda2-treated VMC group was administered with 400 ng IFN-lambda2 (0.1 mL) by subcutaneous injections daily, for 5 days. The control and the VMC groups were given equal amount of nomal saline.The surviving mice were sacrificed 9 days after IFN-lambda2 treatment. The pathological changes of heart tissues were examined under a light microscope. Bcl-2 and Bax expression in heart tissues was determined by immunohistochemistry.The control group presented normal heart tissues. The INF-lambda2-treated VMC group showed significantly a lower pathological score (1.5+/-0.5) than the untreated VMC group (2.8+/-0.8) (P0.01). Bcl-2 expression decreased (P0.01), in contrast, Bax expression increased (P0.01) in the untreated VMC group compared with that in the control group. INF-lambda2 treatment resulted in an increased Bcl-2 expression (P0.01) and a decreased Bax expression (P0.01) compared to the untreated VMC group.INF-lambda2 may alleviate myocardial injuries and inhibit cardiomyocytic apoptosis, thus providing protective effects on myocardial cells in mice with acute VMC.