差动放大器构成精密电流源的核心

许多应用利用精密电流源提供恒定电流,包括工业过程控制、仪器仪表、医疗设备和消费电子产品。例如,过程控制系统利用电流源提供电阻温度检测器（RTD）所需的激励电流; 数字万用表利用电流源测量未知电阻、电容和二极管; 长距离信息、传输广泛使用电流源来驱动4mA至20mA电流环路。     

PRMT5 Selective Inhibitor Enhances Therapeutic Efficacy of Cisplatin in Lung Cancer Cells

As a therapeutic approach, epigenetic modifiers have the potential to enhance the efficacy of chemotherapeutic agents. Protein arginine methyltransferase 5 (PRMT5), highly expressed in lung adenocarcinoma, was identified to be involved in tumorigenesis. In the current study, we examined the potential antineoplastic activity of PRMT5 inhibitor, arginine methyltransferase inhibitor 1 (AMI-1), and cisplatin on lung adenocarcinoma. Bioinformatic analyses identified apoptosis, DNA damage, and cell cycle progression as the main PRMT5-associated functional pathways, and survival analysis linked the increased PRMT5 gene expression to worse overall survival in lung adenocarcinoma. Combined AMI-1 and cisplatin treatment significantly reduced cell viability and induced apoptosis. Cell cycle arrest in A549 and DMS 53 cells was evident after AMI-1, and was reinforced after combination treatment. Western blot analysis showed a reduction in demethylation histone 4, a PRMT5- downstream target, after treatment with AMI-1 alone or in combination with cisplatin. While the combination approach tackled lung cancer cell survival, it exhibited cytoprotective abilities on HBEpC (normal epithelial cells). The survival of normal bronchial epithelial cells was not affected by using AMI-1. This study highlights evidence of novel selective antitumor activity of AMI-1 in combination with cisplatin in lung adenocarcinoma cells.     

Effects of chronic oral administration of levcromakalim on in vitro contractile responses of arterial smooth muscle

It has been shown that oral administration of 0.038-0.15 mg/kg levcromakalim elicits a dose-related antihypertensive response in spontaneously hypertensive rats (Clapham et al., Arzneim. Forsch. 41 (1991) 385). In the present study, we examined the effects of long term administration of a high dose of levcromakalim on in vitro vascular contractility. Levcromakalim (2.25 mg/kg/day) was administered to the rats for 2 weeks and the thoracic aorta was then isolated. The levcromakalim treatment markedly reduced the relaxant effect of levcromakalim itself on norepinephrine-induced contraction. Relaxant effects of sodium nitroprusside and 8-bromo-cGMP were also attenuated by the levcromakalim treatment, although the relaxant effects of verapamil and forskolin were unchanged. The levcromakalim treatment decreased the threshold concentration for KCl and norepinephrine to induce contraction. The chronic levcromakalim treatment did not affect the cGMP production due to 3-isobutyl-1-methylxanthine and/or sodium nitroprusside. The aorta isolated from spontaneous hypertensive rats did not exhibit spontaneous activity in normal solution. After treatment with levcromakalim, however, the aorta showed spontaneous rhythmic contractions. Verapamil (10 microM) completely suppressed the spontaneous activity and decreased the basal tension below the original level. Similar to the effects of chronic treatment with levcromakalim, high-K+ solution (15.4 mM) augmented the contractile response to norepinephrine in the aorta of normotensive rats and induced rhythmic contractions in the aorta of spontaneously hypertensive rats. These results suggest that chronic treatment with a high dose of levcromakalim attenuates not only the effects of levcromakalim itself but also the cGMP-mediated relaxation, possibly by desensitizing the K+ channel.     

Microbiological quality of sous and tamarind, traditional drinks consumed in Jordan

This study was conducted to evaluate the microbiological quality of sous (a drink prepared by extracting dried roots of Glycyrrhiza glabra) and tamarind (a drink prepared by infusing Tamarindus indica dried pulp), traditional drinks consumed in Jordan. Twenty-one samples of sous and 44 samples of tamarind were collected from the local market in Amman, Jordan. Water is the major component of the drinks. Sous drink is characterized by having an alkaline pH (range, 6.6 to 9.9; mean, 8.6), whereas tamarind drink has an acidic pH (range, 1.8 to 3.7; mean, 2.8). The drinks are not processed for safety before serving, and at some vendors drinks are not properly refrigerated. The mean counts for aerobic bacteria, lactic acid bacteria, and yeasts in sous drink samples were 5.9, 5.0, and 3.8 log CFU/ml, respectively; those in tamarind drink samples were 4.0, <1, and 5.8 log CFU/ml, respectively. The lactic acid bacteria isolated were Enterococcus raffinosus, Enterococcus hirae, Enterococcus durans, Lactobacillus acidophilus, and Lactobacillus buchneri. The yeast isolates in sous drink were from the genera Candida, Filobasidium, Hanseniaspora, Lodderomyces, Pichia, and Williopsis, and those in tamarind drink were from Arthroascus, Brettanomyces, Candida, Debaromyces, Filobasidiella, Hanseniaspora, Klavispora, Lodderomyces, Pichia, Saccharomycodes, Trichosporon, and Zygosaccharomyces. Enterobacteriaceae were detected in two sous samples and were identified as Enterobacter sakazakii and Erwinia sp., and in two tamarind samples and were identified as Citrobacter freundii and Klebsiella pneumoniae. Salmonella was detected in one sous and one tamarind sample. Pseudomonas aeruginosa was detected in only one sous sample. These findings highlight the importance of application of hygienic practices throughout preparation and vending of drinks, starting with raw ingredients and continuing through preparation, storage, display, and serving.     

An Improved Deep Structure for Accurately Brain Tumor Recognition

Brain neoplasms are recognized with a biopsy, which is not commonly done before decisive brain surgery. By using Convolutional Neural Networks (CNNs) and textural features, the process of diagnosing brain tumors by radiologists would be a noninvasive procedure. This paper proposes a features fusion model that can distinguish between no tumor and brain tumor types via a novel deep learning structure. The proposed model extracts Gray Level Co-occurrence Matrix (GLCM) textural features from MRI brain tumor images. Moreover, a deep neural network (DNN) model has been proposed to select the most salient features from the GLCM. Moreover, it manipulates the extraction of the additional high levels of salient features from a proposed CNN model. Finally, a fusion process has been utilized between these two types of features to form the input layer of additional proposed DNN model which is responsible for the recognition process. Two common datasets have been applied and tested, Br35H and FigShare datasets. The first dataset contains binary labels, while the second one splits the brain tumor into four classes; glioma, meningioma, pituitary, and no cancer. Moreover, several performance metrics have been evaluated from both datasets, including, accuracy, sensitivity, specificity, F-score, and training time. Experimental results show that the proposed methodology has achieved superior performance compared with the current state of art studies. The proposed system has achieved about 98.22% accuracy value in the case of the Br35H dataset however, an accuracy of 98.01% has been achieved in the case of the FigShare dataset.     

Structure,morphology, thermal,and sorption characteristics of epoxidized natural rubber conjugated spent coffee via one-pot synthesis

The present work highlights the preparation of the epoxidized natural rubber conjugated spent coffee biocomposites (ENR-g-SC) via one-pot synthesis to control petroleum oil spills. The structural determination of the spent coffee grafted epoxidized natural rubber (ENR-g-SC) was confirmed through FTIR and ¹H-NMR spectroscopic analyses. The thermal performance, tensile tests, and morphological properties of the synthesized (ENR-g-SC) biocomposites were performed. The data revealed that ENR-g-SC biocomposite with 20 phr of spent coffee (SC) exhibited the highest tensile properties due to maximal chemical linkages of spent coffee and epoxide groups in ENR. The epoxidized natural rubber conjugated spent coffee copolymers were evaluated as oil sorbers for oil absorbency applications in chloroform, toluene, and 10% crude petroleum diluted with toluene. The data revealed that the oil absorbency increased slightly with chloroform or toluene instead of 10% crude oil diluted with toluene. Furthermore, swelling and network parameters including the maximum oil absorbency (Q_max), swelling rate constant (k), polymer-solvent interaction (χ), effective crosslink density (ύe), equilibrium modulus of elasticity (G_T), and average molecular weight between crosslinks (M_c) and theoretical crosslink density (ύ_t) were determined, and correlated to the efficiency of the synthesized epoxidized natural rubber conjugated spent coffee.