Investigation of Oxidation-Reduction Properties of Growing Mediums for Cell Culture of Mammals under the Effect of Cosmo-Geophysical Factors

In model experiments were studied the effect of cosmo-geophysical factors of environment (hypomagnetic conditions during 2 days ≈ 1 mkT;electromagnetic irradiation (10 min - 2 MHz with amplitude 5 V/m and power 30 mkVt, background 2 - 4 mkVt), γ-quantum (10 min—from the source 137Cs) and its combined effect on the physic-chemical properties (ORP and pH) of growing medium for cell culture of mammals as nutrition medium 199 (PanEco, Russia). It was used a clear solution of medium (solution 1) and with the adding of 10% embryo bull serum—model of bio-medium (solution 2). Hypomagnetic conditions evoked the decreasing of ORP and pH value in both solutions, electromagnetic irradiation in the solution 1 which evoked the decreasing of ORP and the increasing of pH value, and in the solution 2, on the contrary, the increasing of ORP with the unchanging pH value. γ-radiation sharply decreased ORP value and didn’t change pH in solution 1, i.e. the reduction properties increased. There is insignificant increasing of ORP value and the decreasing of pH is noted in the solution 2, that it is characterized with the increasing of oxidative properties of solution. Under the combined effect of hypomagnetic conditions and electromagnetic irradiation, the values of investigating parameters in the solution 1 decreased and in the solution 2 increased. It was observed acute decreasing of ORP value in both solutions under the combined effect of hypomagnetic conditions and γ-radiation, i.e. the reductive properties of the solutions increased sharply. In this the concentration H+ significantly decreased, (p γ-radiation led to the decreasing of ORP and pH values in both solutions. Thus, the studying factors significantly change the oxidation-reduction properties of growing mediums. The investigation of the processes in biological mediums plays the important role in the assessment of environment effect during the flight in inter-planet space.

Oily Wastewater Treatment by Porous Ceramics Mediums with Surface Lipophilic Modification

Aiming at the treatment of difficult-to-handle oily wastewater, the ceramics filter mediums made from the iron and steel plant sludge were adopted to surface lipophilic modification so as to remove oil efficiently. The hydrolysis technique by FTIR and conductivity test indicated that under acid conditions hydrogen silicon oil did not hydrolyze but release hydrogen by chemical reaction under alkaline conditions. The results of the experiments including contact angle measurement, FTIR analysis, and SEM analysis illustrate that a layer of lipophile coating indeed exists evenly on the surface of filter mediums after modification. Furthermore, the hydrogen-containing silicone oil was combined through dehydration of Si-H bond with the-OH on the surface of ceramic filter medium.

Effects of mother tree ages, different rooting mediums, light conditions and auxin treatments on rooting behaviour of Dalbergia sissoo branch cuttings

Dalbergia sissoo Roxb. is one of the promising multipurpose tree species of South Asia. Most of the plantations of D. sissoo from seeds are facing severe threats due to the die-back disease, which ultimately causes death of this potential tree-species within a few months. Vegetative propagation could avoid the die-back disease. Thirty mother trees of different age-groups of D. sissoo were selected for evaluating the rooting behaviour of branch cuttings from D. sissoo as influenced by auxins （IAA or IBA at 100, 200, 500 mg·L^-1）, ages of mother trees （10, 4 and 2 years old） and different environment conditions, i.e., different mediums （soil and sand） or light conditions （in shade and open condition）. The results show that application of IAA and IBA induced more numbers of cuttings （collected from 10-year-old mother trees） to root compared to control. Branch cuttings of D. sissoo collected from 10-year-old mother trees and planted in soil bed in open conditions had 100.0% of cuttings to root in IAA （100 mg·L^-1） and IBA （200 mg·L^-1） treatments. Both rooting medium （Soil and sand） influenced significantly （p〈0.05） on rooting response of branch cuttings. Soil medium was found to achieve maximum no. of branch cuttings to root, compared to sand medium.

Effect of Heat Sink and Cooling Mediums on Ferrite Austenite Ratio and Distortion in Laser Welding of Duplex Stainless Steel 2205

In order to control the ferrite and austenite percentage in duplex stainless steel welding, many researchers try to change the laser welding parameters and cooling medium, but ignore to study the influence of heat sink effect on weld strength. In this work, the effect of aluminium heat sink and varying cooling medium on the laser welding of duplex stainless steel (DSS) 2205 is studied. The 2 mm thick DSS sheets welded with pulsed Nd: YAG laser welding machine by varying the cooling medium (air and oil) and an aluminium plate used as a heat sink. The welded specimens tested for tensile strength, micro-hardness, distortion, microstructure and radiography analysis. The faster cooling rate in the oil quenching process enhances the ferrite percentage compared with air-cooled samples. But the faster cooling rate in oil quenching leads to more distortion and using aluminium as a heat sink influenced positively the distortion to a small extent. The lower cooling rate in air quenching leads to a higher tensile strength of the welded specimen. The objective of this work is to analyse experimentally the effect of cooling medium and heat sink in the mechanical and metallurgical properties of laser welded duplex stainless steel.

Factors involved in the success of Castanea henryi stem cuttings in different cutting mediums and cutting selection periods

Chinquapin(Castanea henryi) is a dual-purpose tree species in China valued for as a source of timber and starch.We investigated the effect of four cutting mediums(pure vermiculite;peat:river sand at 3:1 v/v;peat:krasnozem at 1:1 v/v;and pure krasnozem) and three stem cutting periods(March,May,and July) on rooting performance of C.henryi cuttings.Different cutting periods and cutting mediums greatly influenced the rooting rate of C.henryi,ranging from 3.35 to 77.31%.Principal component analysis indicated that the best combination of cutting period and cutting medium was semi-hardwood cuttings(May cuttings)+krasnozem.Histological evidence indicated that adventitious root initials were present by week 5-6,and that the site of root primordia initiation was observed in the vascular cambium.Stem anatomical structures observed at different periods indicated that a xylem/radius ratio of29.90-37.42% and a fractured phloem fiber ring are indicative of rooting success.The relational model between rooting index and medium properties indicated that nutrient content and porosity significantly influenced callus production.However,pH strongly affected C.henryi root formation,with the Pearson correlation coefficients for May and July cuttings of-0.856 and-0.947,respectively.Our protocol is helpful to achieve mass clone propagation of improved C.henryi genotypes,thus overcoming a common hurdle in chinquapin breeding programs.

Nonreciprocal transmission of electromagnetic waves by three-layer magneto-optical mediums

We investigate the non-reciprocal transmission properties of a three-layer structure filled with magneto–optical medium and normal medium. Based on the transfer matrix method, we deduce the total transmission coefficient for a one-dimensional(1 D) structure with anisotropic mediums. When two-side layers with magneto–optical medium loaded in opposite external magnetic field, the time-reversal symmetry of transmission properties will be broken. Our numerical results show that the non-reciprocal transmission properties are influenced by external magnetic fields, incident angle, and thickness of the normal medium layer. Since the non-reciprocal properties can be easily realized and adjusted by the simple structure, such a design has potential applications in integrated circulators and isolators.

The Near-Field Microwave Focusing in the Layer Mediums

This paper deals with the microwave focusing in the layer mediums near the antenna aperture. Based on the plane-wave spectrum theory, the relationship between the Hertz potential and the electromagnetic field is discussed. An approach to the description of the field distribution in the layer mediums in case of an arbitary field source is proposed. Given the focusing current distribution over the antenna aperture, the field distribution of the focal region is worked out. In describing the field distribution over the focal region, the integration of spectrum functions in the spectrum domain (kx,ky) is carried out instead of the complicated Fresnel integral. The approximations are obtained by the saddle-point integration. Comparison with experimental results demonstrates the validity of the approach.

数字普惠金融发展、资源错配抑制与中小企业景气提升

金融歧视下的资源错配,已成为中小企业健康可持续发展的掣肘。如何突破这一约束,融合“普”与“惠”的数字普惠金融被寄予厚望。本文基于数字普惠金融的内涵与中小企业健康可持续发展对金融资源的诉求进行理论分析,然后构建链式多重中介效应模型,利用江苏省13个地级市的数字普惠金融指数及中小企业发展调研数据,检验数字普惠金融发展对中小企业景气提升的作用及其机制。结果发现:数字普惠金融对中小企业景气提升具有显著的正向作用,覆盖广度、使用深度和数字化程度的提高都能促进中小企业景气指数上升。机制分析表明,数字普惠金融的发展能降低中小企业融资成本,从而提高融资匹配度,由此提升中小企业景气指数。特别地,数字普惠金融发展对中小企业景气的提升作用具有“均衡器效应”,景气状况较差的中小企业能够从中获益更多。为此,应当持续推动数字普惠金融发展,借助其抑制金融资源错配功能,破解中小微企业融资约束,提升其发展中的景气度。

Influence of variable viscosity and double diffusion on the convective stability of a nanofluid flow in an inclined porous channel

The influence of variable viscosity and double diffusion on the convective stability of a nanofluid flow in an inclined porous channel is investigated.The DarcyBrinkman model is used to characterize the fluid flow dynamics in porous materials.The analytical solutions are obtained for the unidirectional and completely developed flow.Based on a normal mode analysis,the generalized eigenvalue problem under a perturbed state is solved.The eigenvalue problem is then solved by the spectral method.Finally,the critical Rayleigh number with the corresponding wavenumber is evaluated at the assigned values of the other flow-governing parameters.The results show that increasing the Darcy number,the Lewis number,the Dufour parameter,or the Soret parameter increases the stability of the system,whereas increasing the inclination angle of the channel destabilizes the flow.Besides,the flow is the most unstable when the channel is vertically oriented.

Review on the plastic instability of medium -Mn steels for identifying the formation mechanisms of Lüders and Portevin -Le Chatelier bands

Plastic instability,including both the discontinuous yielding and stress serrations,has been frequently observed during the tensile deformation of medium-Mn steels(MMnS)and has been intensively studied in recent years.Unfortunately,research results are controversial,and no consensus has been achieved regarding the topic.Here,we first summarize all the possible factors that affect the yielding and flow stress serrations in MMnS,including the morphology and stability of austenite,the feature of the phase interface,and the deformation parameters.Then,we propose a universal mechanism to explain the conflicting experimental results.We conclude that the discontinuous yielding can be attributed to the lack of mobile dislocation before deformation and the rapid dislocation multiplication at the beginning of plastic deformation.Meanwhile,the results show that the stress serrations are formed due to the pinning and depinning between dislocations and interstitial atoms in austenite.Strain-induced martensitic transformation,influenced by the mechanical stability of austenite grain and deformation parameters,should not be the intrinsic cause of plastic instability.However,it can intensify or weaken the discontinuous yielding and the stress serrations by affecting the mobility and density of dislocations,as well as the interaction between the interstitial atoms and dislocations in austenite grains.

Dynamic thermo-mechanical responses of road-soft ground system under vehicle load and daily temperature variation

A complete road-soft ground model is established in this paper to study the dynamic responses caused by vehicle loads and/or daily temperature variation.A dynamic thermo-elastic model is applied to capturing the behavior of the rigid pavement,the base course,and the subgrade,while the soft ground is characterized using a dynamic thermo-poroelastic model.Solutions to the road-soft ground system are derived in the Laplace-Hankel transform domain.The time domain solutions are obtained using an integration approach.The temperature,thermal stress,pore water pressure,and displacement responses caused by the vehicle load and the daily temperature variation are presented.Results show that obvious temperature change mainly exists within 0.3 m of the road when subjected to the daily temperature variation,whereas the stress responses can still be found in deeper places because of the thermal swelling/shrinkage deformation within the upper road structures.Moreover,it is important to consider the coupling effects of the vehicle load and the daily temperature variation when calculating the dynamic responses inside the road-soft ground system.

Conditioned medium from human dental pulp stem cells treats spinal cord injury by inhibiting microglial pyroptosis

Human dental pulp stem cell transplantation has been shown to be an effective therapeutic strategy for spinal cord injury.However,whether the human dental pulp stem cell secretome can contribute to functional recovery after spinal cord injury remains unclear.In the present study,we established a rat model of spinal cord injury based on impact injury from a dropped weight and then intraperitoneally injected the rats with conditioned medium from human dental pulp stem cells.We found that the conditioned medium effectively promoted the recovery of sensory and motor functions in rats with spinal cord injury,decreased expression of the microglial pyroptosis markers NLRP3,GSDMD,caspase-1,and interleukin-1β,promoted axonal and myelin regeneration,and inhibited the formation of glial scars.In addition,in a lipopolysaccharide-induced BV2 microglia model,conditioned medium from human dental pulp stem cells protected cells from pyroptosis by inhibiting the NLRP3/caspase-1/interleukin-1βpathway.These results indicate that conditioned medium from human dental pulp stem cells can reduce microglial pyroptosis by inhibiting the NLRP3/caspase-1/interleukin-1βpathway,thereby promoting the recovery of neurological function after spinal cord injury.Therefore,conditioned medium from human dental pulp stem cells may become an alternative therapy for spinal cord injury.

Deep bed filtration model for cake filtration and erosion

Many phenomena in nature and technology are associated with the filtration of suspensions and colloids in porous media. Two main types of particle deposition,namely, cake filtration at the inlet and deep bed filtration throughout the entire porous medium, are studied by different models. A unified approach for the transport and deposition of particles based on the deep bed filtration model is proposed. A variable suspension flow rate, proportional to the number of free pores at the inlet of the porous medium, is considered. To model cake filtration, this flow rate is introduced into the mass balance equation of deep bed filtration. For the cake filtration without deposit erosion,the suspension flow rate decreases to zero, and the suspension does not penetrate deep into the porous medium. In the case of the cake filtration with erosion, the suspension flow rate is nonzero, and the deposit is distributed throughout the entire porous medium. An exact solution is obtained for a constant filtration function. The method of characteristics is used to construct the asymptotics of the concentration front of suspended and retained particles for a filtration function in a general form. Explicit formulae are obtained for a linear filtration function. The properties of these solutions are studied in detail.

Nonlinear phenomena in vibrations of embedded carbon nanotubes conveying viscous fluid

Various nonlinear phenomena such as bifurcations and chaos in the responses of carbon nanotubes(CNTs)are recognized as being major contributors to the inaccuracy and instability of nanoscale mechanical systems.Therefore,the main purpose of this paper is to predict the nonlinear dynamic behavior of a CNT conveying viscousfluid and supported on a nonlinear elastic foundation.The proposed model is based on nonlocal Euler–Bernoulli beam theory.The Galerkin method and perturbation analysis are used to discretize the partial differential equation of motion and obtain the frequency-response equation,respectively.A detailed parametric study is reported into how the nonlocal parameter,foundation coefficients,fluid viscosity,and amplitude and frequency of the external force influence the nonlinear dynamics of the system.Subharmonic,quasi-periodic,and chaotic behaviors and hardening nonlinearity are revealed by means of the vibration time histories,frequency-response curves,bifurcation diagrams,phase portraits,power spectra,and Poincarémaps.Also,the results show that it is possible to eliminate irregular motion in the whole range of external force amplitude by selecting appropriate parameters.

Therapeutic advances in neural regeneration for Huntington’s disease

Huntington’s disease is a neurodegenerative disease caused by the expansion mutation of a cytosine-adenine-guanine triplet in the exon 1 of the HTT gene which is responsible for the production of the huntingtin (Htt) protein. In physiological conditions, Htt is involved in many cellular processes such as cell signaling, transcriptional regulation, energy metabolism regulation, DNA maintenance, axonal trafficking, and antiapoptotic activity. When the genetic alteration is present, the production of a mutant version of Htt (mHtt) occurs, which is characterized by a plethora of pathogenic activities that, finally, lead to cell death. Among all the cells in which mHtt exerts its dangerous activity, the GABAergic Medium Spiny Neurons seem to be the most affected by the mHtt-induced excitotoxicity both in the cortex and in the striatum. However, as the neurodegeneration proceeds ahead the neuronal loss grows also in other brain areas such as the cerebellum, hypothalamus, thalamus, subthalamic nucleus, globus pallidus, and substantia nigra, determining the variety of symptoms that characterize Huntington’s disease. From a clinical point of view, Huntington’s disease is characterized by a wide spectrum of symptoms spanning from motor impairment to cognitive disorders and dementia. Huntington’s disease shows a prevalence of around 3.92 cases every 100,000 worldwide and an incidence of 0.48 new cases every 100,000/year. To date, there is no available cure for Huntington’s disease. Several treatments have been developed so far, aiming to reduce the severity of one or more symptoms to slow down the inexorable decline caused by the disease. In this context, the search for reliable strategies to target the different aspects of Huntington’s disease become of the utmost interest. In recent years, a variety of studies demonstrated the detrimental role of neuronal loss in Huntington’s disease condition highlighting how the replacement of lost cells would be a reasonable strategy to overcome the neurodegeneration. In this view, numerous have been the attempts in several preclinical models of Huntington’s disease to evaluate the feasibility of invasive and non-invasive approaches. Thus, the aim of this review is to offer an overview of the most appealing approaches spanning from stem cell-based cell therapy to extracellular vesicles such as exosomes in light of promoting neurogenesis, discussing the results obtained so far, their limits and the future perspectives regarding the neural regeneration in the context of Huntington’s disease.

Prediction of subsurface settlement induced by shield tunnelling in sandy cobble stratum

This study focuses on the analytical prediction of subsurface settlement induced by shield tunnelling in sandy cobble stratum considering the volumetric deformation modes of the soil above the tunnel crown.A series of numerical analyses is performed to examine the effects of cover depth ratio(C/D),tunnel volume loss rate(h t)and volumetric block proportion(VBP)on the characteristics of subsurface settle-ment trough and soil volume loss.Considering the ground loss variation with depth,three modes are deduced from the volumetric deformation responses of the soil above the tunnel crown.Then,analytical solutions to predict subsurface settlement for each mode are presented using stochastic medium theory.The influences of C/D,h t and VBP on the key parameters(i.e.B and N)in the analytical expressions are discussed to determine the fitting formulae of B and N.Finally,the proposed analytical solutions are validated by the comparisons with the results of model test and numerical simulation.Results show that the fitting formulae provide a convenient and reliable way to evaluate the key parameters.Besides,the analytical solutions are reasonable and available in predicting the subsurface settlement induced by shield tunnelling in sandy cobble stratum.

THE INTERIOR TRANSMISSION EIGENVALUE PROBLEM FOR AN ANISOTROPIC MEDIUM BY A PARTIALLY COATED BOUNDARY

We consider the interior transmission eigenvalue problem corresponding to the scattering for an anisotropic medium of the scalar Helmholtz equation in the case where the boundary?Ωis split into two disjoint parts and possesses different transmission conditions.Using the variational method,we obtain the well posedness of the interior transmission problem,which plays an important role in the proof of the discreteness of eigenvalues.Then we achieve the existence of an infinite discrete set of transmission eigenvalues provided that n≡1,where a fourth order differential operator is applied.In the case of n■1,we show the discreteness of the transmission eigenvalues under restrictive assumptions by the analytic Fredholm theory and the T-coercive method.

Theoretical study on the effective thermal conductivity of silica aerogels based on a cross-aligned and cubic pore model

Aerogel nanoporous materials possess high porosity, high specific surface area, and extremely low density due to their unique nanoscale network structure. Moreover, their effective thermal conductivity is very low, making them a new type of lightweight and highly efficient nanoscale super-insulating material. However, prediction of their effective thermal conductivity is challenging due to their uneven pore size distribution. To investigate the internal heat transfer mechanism of aerogel nanoporous materials, this study constructed a cross-aligned and cubic pore model(CACPM) based on the actual pore arrangement of SiO_(2) aerogel. Based on the established CACPM, the effective thermal conductivity expression for the aerogel was derived by simultaneously considering gas-phase heat conduction, solid-phase heat conduction, and radiative heat transfer. The derived expression was then compared with available experimental data and the Wei structure model. The results indicate that, according to the model established in this study for the derived thermal conductivity formula of silica aerogel, for powdery silica aerogel under the conditions of T = 298 K, a_(2)= 0.85, D_(1)= 90 μm, ρ = 128 kg/m^(3), within the pressure range of 0–10^(5)Pa, the average deviation between the calculated values and experimental values is 10.51%. In the pressure range of 10^(3)–10^(4)Pa, the deviation between calculated values and experimental values is within 4%. Under these conditions, the model has certain reference value in engineering verification. This study also makes a certain contribution to the research of aerogel thermal conductivity heat transfer models and calculation formulae.

miRNA-21-5p is an important contributor to the promotion of injured peripheral nerve regeneration using hypoxia-pretreated bone marrow-derived neural crest cells

Our previous study found that rat bone marrow–derived neural crest cells(acting as Schwann cell progenitors)have the potential to promote long-distance nerve repair.Cell-based therapy can enhance peripheral nerve repair and regeneration through paracrine bioactive factors and intercellular communication.Nevertheless,the complex contributions of various types of soluble cytokines and extracellular vesicle cargos to the secretome remain unclear.To investigate the role of the secretome and extracellular vesicles in repairing damaged peripheral nerves,we collected conditioned culture medium from hypoxia-pretreated neural crest cells,and found that it significantly promoted the repair of sensory neurons damaged by oxygen-glucose deprivation.The mRNA expression of trophic factors was highly expressed in hypoxia-pretreated neural crest cells.We performed RNA sequencing and bioinformatics analysis and found that miR-21-5p was enriched in hypoxia-pretreated extracellular vesicles of neural crest cells.Subsequently,to further clarify the role of hypoxia-pretreated neural crest cell extracellular vesicles rich in miR-21-5p in axonal growth and regeneration of sensory neurons,we used a microfluidic axonal dissociation model of sensory neurons in vitro,and found that hypoxia-pretreated neural crest cell extracellular vesicles promoted axonal growth and regeneration of sensory neurons,which was greatly dependent on loaded miR-21-5p.Finally,we constructed a miR-21-5p-loaded neural conduit to repair the sciatic nerve defect in rats and found that the motor and sensory functions of injured rat hind limb,as well as muscle tissue morphology of the hind limbs,were obviously restored.These findings suggest that hypoxia-pretreated neural crest extracellular vesicles are natural nanoparticles rich in miRNA-21-5p.miRNA-21-5p is one of the main contributors to promoting nerve regeneration by the neural crest cell secretome.This helps to explain the mechanism of action of the secretome and extracellular vesicles of neural crest cells in repairing damaged peripheral nerves,and also promotes the application of miR-21-5p in tissue engineering regeneration medicine.

A Dual-Cluster-Head Based Medium Access Control for Large-Scale UAV Ad-Hoc Networks

Unmanned Aerial Vehicle(UAV)ad hoc network has achieved significant growth for its flexibility,extensibility,and high deployability in recent years.The application of clustering scheme for UAV ad hoc network is imperative to enhance the performance of throughput and energy efficiency.In conventional clustering scheme,a single cluster head(CH)is always assigned in each cluster.However,this method has some weaknesses such as overload and premature death of CH when the number of UAVs increased.In order to solve this problem,we propose a dual-cluster-head based medium access control(DCHMAC)scheme for large-scale UAV networks.In DCHMAC,two CHs are elected to manage resource allocation and data forwarding cooperatively.Specifically,two CHs work on different channels.One of CH is used for intra-cluster communication and the other one is for inter-cluster communication.A Markov chain model is developed to analyse the throughput of the network.Simulation result shows that compared with FM-MAC(flying ad hoc networks multi-channel MAC,FM-MAC),DCHMAC improves the throughput by approximately 20%~50%and prolongs the network lifetime by approximately 40%.