Search

Epilepsy is a common neurological disorder characterized by hyperexcitability in the brain. Its pathogenesis is classically associated with an imbalance of excitatory and inhibitory neurons. Calretinin (CR) is one of the three major types of calcium-binding proteins present in inhibitory GABAergic neurons. The functions of CR and its role in neural excitability are still unknown. Recent data suggest that CR neurons have diverse neurotransmitters, morphologies, distributions, and functions in different brain regions across various species. Notably, CR neurons in the hippocampus, amygdala, neocortex, and thalamus are extremely susceptible to excitotoxicity in the epileptic brain, but the causal relationship is unknown. In this review, we focus on the heterogeneous functions of CR neurons in different brain regions and their relationship with neural excitability and epilepsy. Importantly, we provide perspectives on future investigations of the role of CR neurons in epilepsy.

Aims Epilepsy, frequently comorbid with depression, easily develops drug resistance. Here, we investigated how dorsal raphe (DR) and its 5‐HTergic neurons are implicated in epilepsy. Methods In mouse hippocampal kindling model, using immunochemistry, calcium fiber photometry, and optogenetics, we investigated the causal role of DR 5‐HTergic neurons in seizure of temporal lobe epilepsy (TLE). Further, deep brain stimulation (DBS) of the DR with different frequencies was applied to test its effect on hippocampal seizure and depressive‐like behavior. Results Number of c‐fos+ neurons in the DR and calcium activities of DR 5‐HTergic neurons were both increased during kindling‐induced hippocampal seizures. Optogenetic inhibition, but not activation, of DR 5‐HTergic neurons conspicuously retarded seizure acquisition specially during the late period. For clinical translation, 1‐Hz‐specific, but not 20‐Hz or 100‐Hz, DBS of the DR retarded the acquisition of hippocampal seizure. This therapeutic effect may be mediated by the inhibition of DR 5‐HTergic neurons, as optogenetic activation of DR 5‐HTergic neurons reversed the anti‐seizure effects of 1‐Hz DR DBS. However, DBS treatment had no effect on depressive‐like behavior. Conclusion Inhibition of hyperactivity of DR 5‐HTergic neuron may present promising anti‐seizure effect and the DR may be a potential DBS target for the therapy of TLE., Activity of the DR and its 5‐HTergic neurons remarkably increase during hippocampal kindling seizure. Either optogenetic inhibition of DR 5‐HTergic neurons or 1‐Hz DR DBS significantly retards seizure acquisition. The hyperactivity of the DR may serve as an underlying mechanism for propagation of seizure and the DR may be a potential DBS target for the treatment of epilepsy.

Previous studies show that infrared radiation temperature (IRT) abnormalities are always accompanied by the crack development in rocks under external loads. In this context, experiments were conducted on preflawed sandstone to investigate the infrared radiation characteristics during failure process. Two indicators were defined herein, i.e. coefficient of variation of IRT (CVIRT) and skewness of IRT (SIRT). The regression analysis shows that the IRT probability distributions during loading process fit the Gaussian model. The variations in the CVIRT are characterized by four stages: primary stage, steady stage, accelerating stage and post-peak stage. Besides, the variations in the SIRT are divided into three stages: primary stage, steady stage and failure and post-peak stage. The precursor point for preflawed rock failure is identified based on the CVIRT–time curve, with average precursor point of 83% of the peak stress. Compared with other IRT indicators, the proposed two IRT indicators have higher sensitivity to IRT abnormalities during failure process. Furthermore, the connection between the IRT indicators and the rock fracturing was investigated to interpret the IRT indicator abnormalities. Based on the Verhulst inverse function, a new quantitative model was presented to describe the primary stage, steady stage and accelerating stage of the CVIRT–time curve. The results obtained in this study can provide early-warning information for rock failure prediction.

Aims Temporal lobe epilepsy (TLE), often associated with cognitive impairment, is one of the most common types of medically refractory epilepsy. Deep brain stimulation (DBS) shows considerable promise for the treatment of TLE. However, the optimal stimulation targets and parameters of DBS to control seizures and related cognitive impairment are still not fully illustrated. Methods In the present study, we evaluated the therapeutic potential of DBS in the medial septum (MS) on seizures and cognitive function in mouse acute and chronic epilepsy models. Results We found that DBS in the MS alleviated the severity of seizure activities in both kainic acid‐induced acute seizure model and hippocampal‐kindled epilepsy model. DBS showed antiseizure effects with a wide window of effective stimulation frequencies. The antiseizure effects of DBS were mediated by the hippocampal theta rhythm, as atropine, which reversed the DBS‐induced augmentation of the hippocampal theta oscillation, abolished the antiseizure effects of DBS. Further, in the kainic acid‐induced chronic TLE model, DBS in the MS not only reduced spontaneous seizures, but also improved behavioral performance in novel object recognition. Conclusion DBS in the MS is a promising approach to attenuate TLE probably through entrainment of the hippocampal theta rhythm, which may be therapeutically significant for refractory TLE treatment., Here, we inferred that the DBS in the MS may be therapeutically significant for the treatment of refractory TLE. DBS in the MS not only alleviated seizures activities, but also improved behavioral performance in memory tests, via the enhancement of hippocampal theta rhythm.

Aims Pharmaco‐genetics emerges as a new promising approach for epileptic seizures. Whether it can modulate epileptogenesis is still unknown. Methods Here, parvalbumin neurons and pyramidal neurons of the seizure focus were transfected with engineered excitatory Gq‐coupled human muscarinic receptor hM3Dq and engineered inhibitory Gi‐coupled human muscarinic receptor hM4Di, respectively. And their therapeutic value in mouse hippocampal kindling‐induced epileptogenesis was tested. Results Pharmaco‐genetic activating parvalbumin neurons limitedly retarded the progression of behavioral seizure stage and afterdischarge duration (ADD) during epileptogenesis induced by kindling. Activating parvalbumin neurons delayed seizure development only in the early stage, but accelerated it in late stages. On the contrary, pharmaco‐genetic inhibiting pyramidal neurons robustly retarded the progression of seizure stages and ADDs, which greatly delayed seizure development in both early and late stages. Although both pharmaco‐genetic therapeutics efficiently alleviated the severity of acute kindling‐induced seizures, pharmaco‐genetic inhibiting pyramidal neurons were able to reverse the enhanced synaptic plasticity during epileptogenesis, compared with that of pharmaco‐genetic activating parvalbumin neurons. Conclusion Our results demonstrated that pharmaco‐genetic inhibiting pyramidal neurons retard hippocampal kindling‐induced epileptogenesis and reverse the enhanced synaptic plasticity during epileptogenesis, compared with that of pharmaco‐genetic activating parvalbumin neurons. It suggests that pharmaco‐genetics targeting pyramidal neurons may be a promising treatment for epileptogenesis., Pharmaco‐genetic activating parvalbumin neurons of the seizure focus limitedly retarded the progression of behavioral seizure stage and afterdischarge duration (ADD) during epileptogenesis in hippocampal kindling mice. On the contrary, Pharmaco‐genetic inhibiting pyramidal neurons of the seizure focus robustly retarded epileptogenesis.

The precise circuit of the substantia nigra pars reticulata (SNr) involved in temporal lobe epilepsy (TLE) is still unclear. Here we found that optogenetic or chemogenetic activation of SNr parvalbumin+ (PV) GABAergic neurons amplifies seizure activities in kindling- and kainic acid-induced TLE models, whereas selective inhibition of these neurons alleviates seizure activities. The severity of seizures is bidirectionally regulated by optogenetic manipulation of SNr PV fibers projecting to the parafascicular nucleus (PF). Electrophysiology combined with rabies virus-assisted circuit mapping shows that SNr PV neurons directly project to and functionally inhibit posterior PF GABAergic neurons. Activity of these neurons also regulates seizure activity. Collectively, our results reveal that a long-range SNr-PF disinhibitory circuit participates in regulating seizure in TLE and inactivation of this circuit can alleviate severity of epileptic seizures. These findings provide a better understanding of pathological changes from a circuit perspective and suggest a possibility to precisely control epilepsy. The neural circuits through which the substantia nigra pars reticulata (SNr) exerts its role in epilepsy control are not known. Here the authors reveal that a long-range SNr-parafascicular nucleus disinhibitory circuit participates in regulating seizures in temporal lobe epilepsy and inhibition of this circuit can alleviate severity of epileptic seizures.

Urban coach cabin is an important indoor environment for long journey, formaldehyde (HCHO) is a carcinogenic gas and damages indoor air quality of cabins. In order to control the HCHO pollution, the air samples inside cabins were analysed with a thermally desorbed gas chromatograph, and the HCHO diffusion was simulated with a methodology of computational fluid dynamics (CFD). Results show that through the experimental monitoring, the HCHO pollution level range from 33.6 to 142.3 μg/m3, decrease quickly with time, and the attenuation trendline is univariate cubic equation. Through the CFD simulation, the indoor temperature and HCHO level of cabin front and rear ends are higher than ones of other areas for the insufficient air supply and the unreasonable arrangement of air exhaust outlet. Moreover, through the CFD simulation, the HCHO level decreases with height growth of breathing zone and increasing air supply speed, and fresh air lead to diffusion of HCHO pollution from cabin seat area to the surrounding area. Through the CFD simulation, the HCHO pollution under the wind speeds of 3~5 m/s is higher than the HCHO limit level from indoor air standard of China vehicles, which shows that the HCHO emission of cabin seat has an important impact on airborne HCHO pollution inside vehicle cabins.

A technique of covalent bonding of grafted polymer brushes of poly(poly(ethylene glycol) monomethacrylate) (P(PEGMA)) on the surface of silicon quantum dots (SiQDs) and activation of the end hydroxyls with N-hydroxysuccinimide (NHS) esters were described in this work in detail. Firstly, a Si/SiQDs slice was disposed with hydrofluoric acid solution to produce surface Si-Hx (x = 1, 2 or 3) species, which combined with vinyl group of 1-undecenol covalently gives terminal hydroxyls. Such hydroxyls were initialized and were involved in atom transfer radical polymerization to construct grafted polymer brushes of P(PEGMA). Hence the density of the surface hydroxyls was enhanced extremely on account of the end hydroxyls of the side chains of the polymer brushes. Then carboxyl groups were introduced via terminal esterification with succinic anhydride, which were activated subsequently with NHS giving NHS esters under rather mild conditions. The reactivity of the terminal NHS esters was demonstrated by SDS-PAGE gel electrophoresis and fluorescence imaging. The SiQDs were demonstrated by transmission electron microscopy. The stepwise modifications on SiQDs were characterized by infrared and X-ray photoelectron spectra. The photoluminescence of the SiQDs was remained during the chemical modifications, proved by the measurements of fluorescence spectra. Keywords: Silicon quantum dots, Grafted polymer brushes, Poly(poly(ethylene glycol) monomethacrylate), N-hydroxysuccinimide esters

Epileptic networks are characterized as having two states, seizures or more prolonged interictal periods. However, cellular mechanisms underlying the contribution of interictal periods to ictal events remain unclear. Here, we use an activity-dependent labeling technique combined with genetically encoded effectors to characterize and manipulate neuronal ensembles recruited by focal seizures (FS-Ens) and interictal periods (IP-Ens) in piriform cortex, a region that plays a key role in seizure generation. Ca

Epilepsy is a circuit-level brain disorder characterized by hyperexcitatory seizures with unclear mechanisms. Here, we investigated the causal roles of calretinin (CR) neurons in the posterior intralaminar thalamic nucleus (PIL) in hippocampal seizures. Using c-fos mapping and calcium fiber photometry, we found that PIL CR neurons were activated during hippocampal seizures in a kindling model. Optogenetic activation of PIL CR neurons accelerated seizure development, whereas inhibition retarded seizure development. Further, viral-based circuit tracing verified that PIL CR neurons were long-range glutamatergic neurons, projecting toward various downstream regions. Interestingly, selective inhibition of PIL-lateral amygdala CR circuit attenuated seizure progression, whereas inhibition of PIL-zona incerta CR circuit presented an opposite effect. These results indicated that CR neurons in the PIL play separate roles in hippocampal seizures via distinct downstream circuits, which complements the pathogenic mechanisms of epilepsy and provides new insight for the precise medicine of epilepsy.

The synergistic control of resistance reduction and sealing poses challenges to enhancing the rapid dynamic response ability of servo hydraulic cylinders, the key to solving this problem is effectively controlling the sealing gap value. In this study, a micro-variation between the hydraulic cylinder and the piston based on the disadvantage of conventional seals, constant gap seals, and lip gap seals was constructed, MSMA assist support blocks were designed on the piston to form a gap seal strip, then, the sealing gap value could be changed by controlling the magnetic field intensity. Simultaneously, the effects of magnetic field strength, parts-manufacturing precision, temperature, and hysteresis on the micro-variation in the MSMA were analyzed, and effective solutions were proposed. Finally, experiments on the magnetic field, temperature, and hysteresis were conducted by the measurement system. The results showed that the variable value of the sealing gap with the MSMA is feasible under ideal conditions, and can effectively change the amount of MSMA expansion by controlling the magnetic field strength, temperature, preload, etc., and then change the amount of the sealing gap of the hydraulic cylinder. This is the key to achieving friction and sealing control, which plays a crucial and active role in improving the efficiency of hydraulic systems. However, the impact of hysteresis effects cannot be ignored, which will be the main problem to be solved in the future.

Stroke has become the first cause of death in China. The study on the relationship between stroke and the risk factors of carotid artery diameter and pulse rate is helpful to provide theoretical basis for the prevention and treatment of stroke. Stroke is usually associated with atherosclerosis, hypertension, and carotid artery stenosis, which is fundamentally related to carotid artery diameter and wall thickness, as well as blood pressure. A large number of studies have shown that the structural and functional parameters of carotid vascular wall can well reflect the mechanical properties of the vessels, and effectively understand the relationship between carotid artery and stroke. Based on the experimental results of carotid artery pressure and diameter, circumferential strain, cross-sectional area, compliance, dilatability, blood pressure and pulse rate, this paper introduces the relationship between carotid artery diameter and pulse rate and stroke in detail, in order to provide reference for the research and development of prevention and treatment of stroke.

As plenty of study have been done to investigate mechanical properties of arterial tissues from many aspects in order give a full description of the arterial tissues and to promote related clinical development, the mechanical behaviors of arterial tissues under physiological condition did not receive sufficient attention. In this study, we verified the nonlinearity, anisotropy and location dependent mechanical behaviors of porcine thoracic artery through planar uniaxial tests. We focused on the mechanical responses of the artery within the intra-vascular physiological blood pressure range of 60-120mmHg. Through the estimation of the strain and stress within the physiological range and the comparison of the anisotropy index, this study confirmed the anisotropic, location-dependent mechanical behaviors of the aortic tissues. The stiffness of the arterial tissues increases gradually from the proximal end to the distal end. Within the physiological range, the degree of nonlinearity of the arterial tissue is not obvious, although there are certain differences in the value of strain and stiffness of the arterial tissue under physiological condition. The stress range of the physiological range of different locations is relatively similar. We also found that within the range of physiological blood pressure, the degree of anisotropy of arterial tissue increases slightly from the proximal end to the distal end and increases gradually with the increase of blood pressure. Through the above research, this article is expected to increase the knowledge of the mechanical properties of arterial tissue under physiological conditions.

In this paper, a new singular Voronoi cell finite element method (S-VCFEM) is proposed to study the initiation and propagation of interfacial debonding and matrix cracking in particulate reinforced composite. Composites with large-scale inclusions and cracks can be easily simulated with this model. A new assumed stress hybrid variational functional is derived from the element energy function to accommodate the interface traction reciprocity on bonded interface and the interface traction-free on debonded interface and matrix crack surface. S-VCFEM is achieved through enhancements in stress functions in the assumed stress hybrid formulation. In addition to polynomial terms and interaction terms, singular stress terms of Williams expansion are added for stress functions, which are adaptively enriched to accurately capture the crack-tip stress concentrations. After obtaining the stress field, calculation of stress intensity factors is performed, using the least square method based on stress value obtained numerically in the S-VCFEM. The efficiency of the method is verified against numerical results obtained by ABAQUS with XFEM module for the same problem considering a matrix-crack and a debonded interface.

Temporal lobe epilepsy (TLE) is the most common type of epilepsy and is often medically refractory. Previous studies suggest that selective pharmaco-genetic inhibition of pyramidal neurons has therapeutic value for the treatment of epilepsy, however there is a risk of disrupting normal physical functions. Here, we test whether pharmaco-genetic activation of parvalbumin neurons, which are transgenetically transduced with the modified muscarinic receptor hM3Dq can attenuate TLE. We found that pharmaco-genetic activation of hippocampal parvalbumin neurons in epileptogenic zone not only significantly extends the latency to different seizure stages and attenuates seizure activities in acute seizure model, but also greatly alleviates the severity of seizure onsets in two chronic epilepsy models. This manipulation did not affect the normal physical function evaluated in various cognitive tasks. Further, the activation of parvalbumin neurons produced an inhibition on parts of surrounding pyramidal neurons, and the direct inactivation of pyramidal neurons via the viral expression of a modified muscarinic receptor hM4Di produced a similar anti-ictogenic effect. Interestingly, pharmaco-genetic inactivation of pyramidal neurons was more sensitive to impair cognitive function. Those data demonstrated that pharmaco-genetic seizure attenuation through targeting parvalbumin neurons rather than pyramidal neurons may be a novel and relatively safe approach for treating refractory TLE.

In this paper, a simultaneous measurement method of stress-optic constant and stress field of transparent plate is presented based on digital holographic interferometry. An image-plane digital holographic system is used to capture holograms and measure phase difference of object wave at different loading states. The relationship among the phase difference, the stress-optic constant and stress of transparent plate is given. The stress-optic constant and stress field of a polymethyl methacrylate (PMMA) specimen with a hole under uniform tensile force are measured by this method. The experimental results are in accordance with the existed and theoretical ones.

Epilepsy is a circuit-level brain disorder characterized by excessive or hypersynchronous epileptic seizures involving a complex epileptogenic network. Cumulative evidence suggests that the piriform cortex (PC) is a crucial site in seizure initiation, propagation, and generalization in epilepsy. The kindling model is a classic animal model of complex partial seizures with secondarily generalized tonic seizures, which is usually used for the study of epilepsy pathogenesis and preclinical anti-epilepsy drug evaluation. Various essential functions of the PC in epilepsy were discovered in the kindling model, therefore, this review focuses on discussing the role of the PC in the kindling model. We review what pathological changes happen in the PC in the kindling model, how the PC is involved in the kindling model through different interventions, and finally we also provide perspectives on some possible research directions for future studies.

In this paper, a new extended Voronoi cell finite element method (X-VCFEM), in which two new elements in the crack propagation process are proposed and a remeshing algorithm is constructed, is proposed to model the initiation and propagation of the interface crack and the matrix crack in particulate reinforced composites. In order to accurately capture crack-tip stress concentrations, some singular stress terms of Williams expansion in the vicinity of crack tips are introduced in the stress functions in X-VCFEM. The direction of the crack propagation in matrix is determined by the maximum energy release rate and the interface crack propagation along the interface or into the matrix is assessed on the base of a series of criteria relating to the critical normal stress and the critical hoop stress. Then several numerical examples are used to demonstrate the effectiveness of X-VCFEM by comparing with results obtained by the commercial software ABAQUS. At last, a numerical example is given for a complex structure with 20 randomly distributing inclusions to model the interfacial cracking and matrix cracking. It is certain that this method is a powerful way to model the interfacial and matrix damage of composites containing a great deal of inclusions and cracks.

In order to enhance the robustness of interdependent power grids and communication networks, a link addition strategy is proposed, which obeys the partial one-to-one correspondence between power nodes and communication nodes. In this method, the target value of node degree is set and then the number of addition links is determined according to its degree for each node. Our strategy aims to homogenize degree distribution of nodes. Case study on IEEE test systems based on the time-step failure model of nodes shows that the proposed method can obtain better robustness and synchronization of interdependent networks in the case of random and intentional attacks. The proposed strategy can provide guidance on current topic to improve robustness of interdependent networks.

A convenient approach of preparing silicon nanotubes (SiNTs) on a silicon substrate is described in this work in detail. Firstly, a porous silicon (PSi) slice is prepared by a galvanic displacement reaction. Then it is put into aqueous solutions of 20% (w%) ammonium fluoride and 2.5 mM cobalt nitrate for a predetermined time. The cobalt ions are reduced and the resulted cobalt particles are deposited on the PSi slice. After the cobalt particles are removed with 5 M nitric acid a plenty of SiNTs come out and exhibit disorderly on the silicon substrate, which are illustrated by scanning electron microscopy (SEM). The compositions of the SiNTs are examined by energy-dispersive X-ray spectroscopy. Based on the SEM images, a suggested mechanism is put forward to explain the generation of the SiNTs on the PSi substrate.

A generalized method for calculating the stress intensity factor from angular deflection of light rays is proposed. The method is based on 2D digital image correlation (DIC) to measure angular deflection of light rays, however, when a specimen is subjected to loading, deformation measurement from DIC is not perfect because of the existence of small in-plane and out-of-plane motions of the test sample surface that occurred after loading. These disadvantages will lead to errors in the measured angular deflections and fracture parameters. The influence of unavoidable in-plane and out-of-plane motions is discussed, and a generalized method to eliminate them to show the pure stress gradient of the crack tip of Polymethyl Methacrylate (PMMA) is demonstrated. At the same time, the fracture parameter of stress intensity was calculated. The experimental angular deflection of light rays was compared with the theoretical angular deflection predicted by generalized model using data points in an array around the crack tip region. To show the potential and efficacy of the method, K values were obtained from experimental data during tests conducted in a PMMA three-point-bend specimen. Results show an excellent level of agreement with K values predicted from FEM, highlighting the potential of the proposed methodology.

This paper introduces a new extended Voronoi cell finite-element method (X-VCFEM) for modelling the propagation of multiple cracks in brittle materials. The direction of the crack propagation is adaptively determined in terms of the maximum energy release rate near the crack tip, and we apply a remeshing strategy that a node at a last incremental crack tip in the crack advance process is replaced by a node pairs to realize the gradual crack propagation. In order to accurately capture crack-tip stress concentrations, some singular stress terms of Williams expansion in the vicinity of crack tips are introduced in the assumed stress hybrid formulation which also includes the polynomial terms and the reciprocal terms. Then several numerical examples are used to demonstrate the effectiveness and accuracy of X-VCFEM enriched by some singular stress terms of Williams expansion by comparing X-VCFEM results with those computed by the commercial finite element package ABAQUS or established results in the literature. At last, two numerical examples are given to simulate multiple crack propagation in brittle media. The effects of morphological distributions such as length, orientation and dispersion on the crack propagation are studied. It is obvious that the X-VCFEM has great advantage of analyzing large regions of the microstructure with multiple growing and interacting cracks.

A numerical-experimental hybrid method for the stress separation in the digital gradient sensing (DGS) method is proposed in this study. In the proposed hybrid method, boundary conditions for a local finite element model, that is, nodal force along boundaries are inversely determined from experimental values obtained by the digital gradient sensing method. The hybrid method follows two stages. In stage 1, the DGS method measures the Cartesian stress gradient components directly and, subsequently, the sum in Cartesian stresses at all interesting points on the surface; stress sum are used to compute the unknown boundary conditions for the local model. In stage 2, the individual stress components are calculated by the direct finite element method using the computed boundary conditions from stage 1. The effectiveness is demonstrated by applying the proposed method to a stress concentration problem involving concentrated load acting on an edge of a large planar sheet. The individual stress components thus determined are summed and compared with analytical stress sum, confirming the effectiveness and accuracy of the proposed technique.

Fluorescent silicon quantum dots (SiQDs) could be prepared by reduction of hydrogen silsesquioxane, etching of silicon powers with wetting chemistry techniques or electrolysis of a wafer catalyzed by polyoxometalates. Chemical modifications are indispensable for the stability of the SiQDs photoluminescence and wider applications of SiQDs. Facile routes of manufacturing SiQDs derived from a silicon wafer and its surface functionalization by N-hydroxysuccinimide (NHS) esters were described in this work in detail. Firstly, the porous silicon chip was prepared by nanosilver-assisted electroless chemical etching. Then the chip was etched successively with hydrofluoric acid/nitric acid solutions until it emitted dazzling red fluorescence which claimed the achieved SiQDs on silicon substrates (SiQDs/Si). Finally, surface NHS esters were fabricated on such an SiQDs/Si chipthrough stepwise modifications, which were tested by the amidation between the NHS esters and n-octylamine. The fluorescence emission of the SiQDs/Si chip almost remained unchanged during the successively chemical modifications, which indicated the SiQDs had capabilities of enduring the sustained high temperature and organic media. Meanwhile, the SiQDs did not leave from the silicon substrate during the surface tuning. The SiQDs obtained by ultrasonication of an SiQDs/Si chip in water were investigated by transmission electron and atomic force microscopies.

Due to the long time in vehicular cabins, people have high exposure to the airborne volatile organic compounds (VOCS), which will lead to negative effects on human health. In order to analyze the influencing factors of in-car VOCS pollution concentrations, 38 taxis were investigated on the static and closed conditions. The interior air of taxis was collected through activated Tenax adsorption tubes, and the air samples were analyzed with thermally desorbed gas chromatograph. The average concentrations of in-car benzene, toluene, ethylbenzene, xylenes, styrene, butyl acetate, undecane, and total VOCS (TVOC) were 82.7, 212.3, 74.7, 182.3, 24.7, 33.5, 61.3, and 1,441.7 μg/m(3), respectively. Furthermore, the VOCS and TVOC concentrations increase with the rise of in-car temperature and relative humidity, and decrease with the increase of car age and total mileage. In addition, the VOCS and TVOC concentrations are higher in vehicles with small cabins than in ones with big cabins, and change with different sampling sites and various vehicular grades. Finally, according to the multiple linear regression analysis and hierarchical cluster analysis, car age is the most important factor influencing airborne VOCS and TVOC pollution concentrations in vehicular cabins, followed by interior temperature and total mileage.

A facile approach of preparing well-dispersed silver nanoparticles (Ag NPs) which fabricated on surface of porous silicon (PSi) generating Ag NPs/PSi chip and the catalyses towards reduction of nitro aromatics are described in detail in this work. Aqueous silver ions are reduced readily by the surface Si H x ( x =1, 2 or 3) species of PSi within dozens of seconds at room temperature. The resulted Ag NPs are demonstrated by scanning and transmission electron microscopes, ultraviolet-visible spectrum and X-ray powder diffraction. A proposed mechanism of forming Ag NPs on PSi chip is discussed in light of the observed phenomena and the analyses of infrared and energy dispersive X-ray spectra. The stably porous architecture of PSi and the well-dispersed Ag NPs on PSi surface guarantee the highly catalytic activities of the Ag NPs/PSi chip. The progresses of reducing nitro aromatics catalyzed by the Ag NPs/PSi chip in the presence of sodium borohydride are traced by ultraviolet-visible measurements to estimate the catalytic performance of the Ag NPs/PSi chip.

Surface-grafted polymer brushes of methyl acrylate of graphite oxide (GO) have been constructed to anchor poly(amidoamine) 2.0G (PAMAM 2.0G) dendrites for the attachment of magnetite nanoparticles. Monomers of methyl acrylate were copolymerized on the GO sheets by atom transfer radical polymerization. Then the PAMAM 2.0G was attached via covalent bond at the end of the grafted chains. Thus the inexpensive Fe(III) of ferric trichloride could coordinate with the remaining amino groups of PAMAM 2.0G and were reduced by the added sodium borohydrite at appropriate pH value to obtain nano magnetite-decorated GO hybrid materials. The hybrids exhibited a powerful catalysis on the degradation of aqueous solutions of hydroquinone.