The response of a chemoresistive gas sensor (CRGS) to the presence of a contaminant in the surrounding air can be substantially drifted by the fluctuations in the ambient humidity and temperature. ...This renders the appropriate compensation measures essential for the quantitative contamination level assessments. Here, the combined effect of the ambient humidity and temperature variations on the CRGS responses to different concentrations of a contaminant is experimentally investigated, and a systematic technique for the elimination of these drift-like terms is presented. The CRGS is considered as a nonlinear reverse multi-input-single-output system. The ambient humidity and temperature along with the as-measured steady-state value of the sensor's resistance are the inputs to the system, while the contaminant concentration is defined as the output. The system was analyzed based on the experimental data collected; the results facilitated the design and training of an artificial neural network which could determine the prevailing contamination level based on the sensor's resistance recorded at different ambient conditions. The effectiveness of the presented drift compensation technique was demonstrated by the verification tests carried out.
It has been theoretically established that the dynamic range of sensitivity in porous dielectric ceramic-based resistive or capacitive humidity sensors is mainly determined by the open pore size ...distribution in their sensing pallets. Here, we directly apply the concept on ceramic resistive humidity sensors and utilize the results for the experimental verification of the theoretical model. The open pore size distribution in a number of identical titanium dioxide pallets, fabricated by the sintering of the slip-cast powder at 1073K, is modified in two different directions: (a) impregnation with titanium tetraisopropoxide, followed by a heat treatment at 773K increases the proportion of the finer pores and (b) re-sintering the original pallets at 1223K closes the finer pores and substantially shifts the distribution towards larger pore dimensions. Sensitivity measurement results are consistent with the theoretically established concept: increasing the population of larger pores heightens the sensitivity to high relative humidity (RH) levels and shifts the dynamic range of the pallets from the original 20–85% to 50–95% RH. On the contrary, increasing the proportion of the finer pores in the microstructure of the ceramic pallet enhances the sensitivity at the lower RH range, shifting the dynamic range of the sensor to the 2–25% RH range.
Strategies to improve energy density in supercapacitors are mainly based on utilizing electrodes providing larger effective surfaces and electrolytes allowing op eration in wider voltage windows. ...Here, a water‐based, binder‐free, environmentally friendly, high voltage, and quasi‐solid‐state symmetric supercapacitor is presented comprising partially reduced graphene oxide active electrodes and concentrated NaCl: polyvinyl alcohol gel electrolyte. It is shown that the ionic diffusion through the electrode‐electrolyte interface is augmented by the partial reduction of the graphene oxide electrodes up to an optimum level. The safe operation voltage window is 4 V; the high field endurance is attributed to the ion‐saturated hydrogel electrolyte used. At a scan rate of 25 mV/s, the provided capacitance and stored energy are 0.1 F.cm−2 and 5.6 e−5 W.h.cm−2, respectively. The optimized device retains ~90 % of its initial capacitance after 1000 charge‐discharge cycles; no meaningful sign of degradation is detected afterwards up to the 2000 cycles examined. These results place further emphasis on the potentials of the gel polymer electrolytes in the fabrication of environmentally friendly supercapacitors. Our findings are anticipated to accelerate improvements in the properties of the graphene‐based electrodes, particularly in conjunction with the proposed electrolyte.
A high voltage, binder‐free, and environmentally friendly symmetric supercapacitor with low‐temprature reduced GO electrodes in air atmosphere is introduced, which utilizes a concentrated NaCl:PVA gel electrolyte for the first time. These devices withstand voltage windows up to 4 V while providing the areal capacitance of 0.1 F.cm−2 and the areal energy density of 5.6 e−5 W.h.cm−2.
Highly sensitive, micron‐size, lightweight, and cost‐effective pressure sensors and pressure sensor arrays are in demand for varieties of sonic, biomedical, tactile, and wearable microelectronic ...applications. Here, the electrical conduction through the interface between a metal oxide semiconductor nanocrystallite and graphene (Gr) formed in O‐rich conditions is shown to be highly pressure sensitive, and a novel class of pressure sensors operating based on the electronic features of heterointerfaces is introduced. First‐principle studies on ZnO/Gr interface attribute the observed pressure sensitivity to the spontaneous formation of a sparse layer of oxygen at the O‐terminated ZnO/Gr interface. Strained by the external force, this layer controls the electron conduction through the junction. In the reduced oxygen conditions, the formation of a stable and pressure insensitive Zn‐terminated ZnO/Gr junction is predicted, which reversibly transforms to the former upon annealing in air at 300 °C. The presented results concerning the spontaneity of adsorbing oxygen species to the O‐terminated metal oxide/Gr junctions are anticipated to assist understanding and engineering of the piezoresistivity and chemiresistivity in the metal oxide‐Gr composites.
Charge conduction through the interface between a ZnO crystallite and graphene formed in O‐rich conditions is highly sensitive to the externally exerted pressure. This sensitivity disappears in vacuum, and reappears upon a brief thermal annealing in air. First‐principles studies attribute the effect to the spontaneous diffusion and adsorption of the additional oxygen from the atmosphere to the O‐terminated ZnO/graphene interface.
Maximum response levels reported for chemoresistive sensors span from less than 10 to over 10
8. These differences are attributed to either the different micro- and nano-structured oxide pallets used ...or the properties of the metal–metal oxide junctions provided. Here, we report separate measurements and model-based estimations of the chemical responses arising from these different origins. The results quantitatively connect the observed responses to the parameters of the metal and metal oxide components of the device. It is shown that while the peak chemoresistive response is microstructure-dependent, the highest attainable Schottky-type gas sensitivity is almost microstructure-independent and is determined by the intrinsic properties of the materials involved. Measurements carried out on different Ag–TiO
2–Ti, Au–TiO
2–Ti and Ti–TiO
2–Ti structures verified the estimations: While chemoresistive responses in TiO
2 can hardly rise over 10
2, atmosphere-sensitive noble metal–TiO
2 junctions can cause responses as high as ∼10
7.
Evidence has been provided of the anti-proliferative activity of citalopram against some cancer cells.
The apoptotic impact of citalopram, an antidepressant, against liver hepatocellular carcinoma ...cell line HepG2 was investigated in relation to the oxidative pathway and nuclear factor (NF)κB activation.
The cytotoxic effects of citalopram on HepG2 cells were determined by MTT assay. Reactive oxygen species (ROS) formation and cytochrome c release were measured following treatment with citalopram. Apoptosis analysis and Bax and Bcl--2 mRNA and protein levels were also determined.
The cytotoxic effects of different concentrations of citalopram on HepG2 cells were observed as a reduction in cell viability and an increase in ROS formation. Citalopram caused an increase in mitochondrial Bax levels and a decrease in Bcl2 levels and also caused cytochrome c release. Moreover, DAPI staining and flow cytometry assays revealed citalopram-induced apoptosis in HepG2 cells. Oxidant scavengers and Bay 11-7082 (an irreversible inhibitor of NFκB activation) prevented the citalopram-associated cell death, increased BAX and decreased Bcl2.
Outcomes from current study suggest that citalopram might exhibit apoptotic effect against hepatocellular carcinoma cell line by induction of cell death through cytochrome c release and ROS-dependent activation of NFκB.
Despite the increasing industrial and domestic demand for gas analyzers, the unmanageable size and cost of the available devices prevent them from fulfilling this pervasive need. In this paper, we ...demonstrate that, monitored by a generic gas sensor, the progress rate of a gaseous analyte’s free diffusion through an air-filled centimeter-long microfluidic channel yields sufficient information for gas recognition. The installation of additional channels made from different materials provides more uncorrelated information, enabling more detailed gas analyses. This device classifies gases based on their physical features at room temperature, namely, diffusivity and interaction (physisorption/desorption) with channel walls. This process does not degrade the gas discriminating element of the instrument. Our prototype, featuring a 50 mm long 50 μm bore borosilicate glass channel, successfully differentiated between 24 analytes, including four butanol isomers, and estimated the compositions of their binary and ternary gas mixtures dispersed in air at different concentration levels. The findings presented here are directly applicable to the production of a new inexpensive, compact, portable, and durable generation of artificial olfaction system whose performance is almost entirely independent of the utilized gas sensor’s drift.
Background and Aims
Sexual dysfunctions are one of the health problems after natural disasters that are usually less attention. The purpose of this study was to evaluate the effect of the earthquake ...on men's sexual functions 1 year after the earthquake.
Methods
This study was a descriptive‐analytical cross‐section study that took place a year after the Kermanshah earthquake. The population studied was all men living in the Kermanshah earthquake. Demographic, socioeconomic, psychological, health situations, facilities availability, and environmental situations after the earthquake and International Index of Erectile Function (IIEF) were randomly distributed among men affected by the earthquake. Participants returned the questionnaires through the mail. Based on the IIEF cut‐point score, men were divided into two groups: those with sexual dysfunction (Group A) and without sexual dysfunction (Group B).
Results
In this study, 225 married men participated. The prevalence of sexual dysfunction in earthquake‐affected men was 44.9%. The mean total IIEF scores in the A and B groups were 43.47 ± 7.82 and 62.11 ± 6.39, respectively. There was a significant difference between the total and all subcategories IIEF scores in the two groups (p < 0.001). There was a statistically significant difference between the age (p < 0.001), child numbers (p < 0.017), current live location (p < 0.001), social support after the earthquake (p = 0.033), underlying disease (p < 0.001), availability of sanitary toilets (p < 0.001) and bathrooms (p = 0.002), and total IIEF scores between the two groups (p < 0.001).
Conclusions
Approximately half of the earthquake‐affected men had sexual dysfunctions. The men's age, child numbers, current live location, social support, underlying disease, and availability of sanitary toilets and bathrooms were influential in the severity of men's sexual dysfunctions after the earthquake. Therefore, crisis managers, policymakers, psychiatrists, and psychologists should pay enough attention to men's sexual dysfunction after earthquakes.
Rat aorta assay provides a low cost and rapid platform, especially for preclinical in vivo models. The signaling pathways of the analog on the vessels could be evaluated separately on the endothelium ...or smooth muscle cells by rings of the rat aorta in vitro. The rat aorta is used for angiogenesis modeling to integrate the benefits of the both in vivo and in vitro models. These explain the importance and usage of rat aorta in researches.
Furthermore, about 4503 articles have been published with the key word “rat aorta” in title or abstract from 1955 until the end of 2013 in Medline. In this review, these articles were organized into two main categories: in vivo and in vitro studies. The in vitro section focused on the rat aorta model, as a tool for evaluate the mechanism of vasodilation, vasoconstriction and angiogenesis. In the in vivo section, the most important usage of this tissue was evaluated. Also, the vasotonic signaling pathways in the vessel are explained briefly and some rat aorta applications in vitro and in vivo have been discussed.
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The pre-hospital emergency staff played a key role in transferring the injured patients to health centers. Usually, they reported changes in their decisions on the transfer of non-traumatic patients ...to hospitals. So, this study was aimed to explore the reasons for unnecessarily requesting an ambulance by non-traumatic patients after the acute responding-to-earthquake phase. This study was a qualitative study that data were analyzed by content analysis approach. Participants were eleven pre-hospital emergency technicians. Data were collected by three sessions of focus group discussion. Data analysis was led to emergence of a main theme: “feeling urgency due to turmoil and uncertainty.” This theme illustrates the basic approach of the inhabitants of the earthquake-stricken region when unnecessarily requesting an ambulance. This theme was derived from two main categories of “turbulent and uncertain conditions” and “psychological turmoil.” The category of “turbulent and uncertain conditions” was comprised of three subcategories: “unreliable care,” “inadequate facilities” and “turbulent living conditions.” The category of “psychological turmoil” was comprised of three subcategories: “psychological turmoil in survivors,” “healthcare providers deciding under pressure” and “turmoil in providing psychological and psychiatric services.” Ambulance dispatch may be unnecessarily performed owing to turbulent and unsure conditions and psychological turmoil in earthquake-stricken people and pre-hospital emergency staff. Providing earthquake-stricken people with psycho-medical services in their place of residence can significantly reduce the workload of pre-hospital emergency staff and consequently that of hospital staff and therefore save time and treatment costs and increase the quality of health services provided for the injured.
