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841.
Contamination of water resources by toxic metals and opportunistic pathogens remains a serious challenge. The development of nano-adsorbents with desired features to tackle this problem is a continuously evolving field. Here, magnetic mesoporous carbon nanospheres grafted by antimicrobial polyhexamethylene biguanidine (PHMB) are reported. Detailed mechanistic investigations reveal that the electrostatic stabilizer modified magnetic nanocore interfaced mesoporous shell can be programmatically regulated to tune the size and related morphological properties. The core–shell nano-adsorbent shows tailorable shell thickness (≈20–55 nm), high surface area (363.47 m2 g−1), pore volume (0.426 cm3 g−1), radially gradient pores (11.26 nm), and abundant biguanidine functionality. Importantly, the nano-adsorbent has high adsorption capacity for toxic thallium (Tl(I) ions (≈559 mg g−1), excellent disinfection against Staphylococcus aureus and Escherichia coli (>99.99% at 2 and 2.5 µg mL−1), ultrafast disinfection kinetics rate (>99.99% within ≈4 min), and remarkable regeneration capability when exposed to polluted water matrices. The Tl(I) removal is attributed to surface complexation and physical adsorption owing to open ended mesopores, while disinfection relies on contact of terminal biguanidines with phospholipid head groups of membrane. The significance of this work lies in bringing up effective synchronic water purification technology to combat pathogenic microorganisms and toxic metal.  相似文献   
842.
This study focuses on both epitaxial growths of InxGa1?xN epilayers with graded In content, and the performance of solar cells structures grown on sapphire substrate by using metal organic chemical vapor deposition. The high resolution X-ray and Hall Effect characterization were carried out after epitaxial InGaN solar cell structures growth. The In content of the graded InGaN layer was calculated from the X-ray reciprocal space mapping measurements. Indium contents of the graded InGaN epilayers change from 8.8 to 7.1 % in Sample A, 15.7–7.1 % in Sample B, and 26.6–15.1 % in Sample C. The current voltage measurements of the solar cell devices were carried out after a standard micro fabrication procedure. Sample B exhibits better performance with a short-circuit current density of 6 mA/cm2, open-circuit voltage of 0.25 V, fill factor of 39.13 %, and the best efficiency measured under a standard solar simulator with one-sun air mass 1.5 global light sources (100 mW/cm2) at room temperature for finished devices was 0.66 %.  相似文献   
843.
A compact, reconfigurable antenna supporting multiple wireless services with a minimum number of switches is found lacking in literature and the same became the focus and outcome of this work. It was achieved by designing a Th-Shaped frequency reconfigurable multi-band microstrip planar antenna, based on use of a single switch within the radiating structure of the antenna. Three frequency bands (i.e., 2007–2501 MHz, 3660–3983 MHz and 9341–1046 MHz) can be operated with the switch in the ON switch state. In the OFF state of the switch, the antenna operates within the 2577–3280 MHz and 9379–1033 MHz Bands. The proposed antenna shows an acceptable input impedance match with Voltage Standing Wave Ratio (VSWR) less than 1.2. The peak radiation efficiency of the antenna is 82%. A reasonable gain is obtained from 1.22 to 3.31 dB within the operating bands is achieved. The proposed antenna supports Universal Mobile Telecommunication System (UMTS)-1920 to 2170 MHz, Worldwide Interoperability and Microwave Access (WiMAX)/Wireless Broadband/(Long Term Evolution) LTE2500–2500 to 2690 MHz, Fifth Generation (5G)-2500/3500 MHz, Wireless Fidelity (Wi-Fi)/ Bluetooth-2400 to 2480 MHz, and Satellite communication applications in X-Band-8000 to 12000 MHz. The overall planar dimension of the proposed antenna is 40 × 20 mm2. The antenna was designed, along with the parametric study, using Electromagnetic (EM) simulation tool. The antenna prototype is fabricated for experimental validation with the simulated results. The proposed antenna is low profile, tunable, lightweight, cheap to fabricate and highly efficient and hence is deemed suitable for use in modern wireless communication electronic devices.  相似文献   
844.
Human Action Recognition (HAR) is a current research topic in the field of computer vision that is based on an important application known as video surveillance. Researchers in computer vision have introduced various intelligent methods based on deep learning and machine learning, but they still face many challenges such as similarity in various actions and redundant features. We proposed a framework for accurate human action recognition (HAR) based on deep learning and an improved features optimization algorithm in this paper. From deep learning feature extraction to feature classification, the proposed framework includes several critical steps. Before training fine-tuned deep learning models – MobileNet-V2 and Darknet53 – the original video frames are normalized. For feature extraction, pre-trained deep models are used, which are fused using the canonical correlation approach. Following that, an improved particle swarm optimization (IPSO)-based algorithm is used to select the best features. Following that, the selected features were used to classify actions using various classifiers. The experimental process was performed on six publicly available datasets such as KTH, UT-Interaction, UCF Sports, Hollywood, IXMAS, and UCF YouTube, which attained an accuracy of 98.3%, 98.9%, 99.8%, 99.6%, 98.6%, and 100%, respectively. In comparison with existing techniques, it is observed that the proposed framework achieved improved accuracy.  相似文献   
845.
Binding of Zn2+ and Cd2+ cations to relatively young brown coals YBC (lignite), humic acids (HAs) and commercial humic acid (CHA) were studied in aqueous media at pH 2.7-6 by polarographic method. This study was conducted to evaluate the removal of heavy metals in an aquatic system without prior treatment. The general principles of cation binding to YBC and humic materials are discussed. Sorption of heavy metal ions (Zn2+ and Cd2+) on samples of YBCs from three areas (Ilgin, Beysehir, and Ermenek) in the vicinity of the city of Konya in Anatolia (Turkey) were compared with sorption of these metal ions on HAs, prepared from these YBCs. The ability of both types of sorbent to remove metals from aqueous solutions was studied as a function of pH and concentration of initial metal solutions. Sorption depends strongly on pH, the origin of the YBC and on the nature of the metal ion. Whereas, for YBCs the main ligand groups seem to be carboxylate ions, this is not the case for the HA polymers, prepared from three YBCs, which differ substantially from properties of commercial samples of "HA". The process is very efficient especially in the case of low concentrations of pollutants in water, where common methods are either economically unfavorable or technically complicated. Of the two metal ions examined, Cd2+ was found to form the most stable HA complexes, followed by Zn. Effective removal of metals was demonstrated at pH-values of 5-5.7. The adsorption isotherm was measured at 25 degrees C, using adsorptive solutions at the optimum pH-value to determine the adsorption capacity. An important aspect of the proposed method was that the removal was performed on several metals at a pH-range in which a given metal undergoes an adsorption process making the method useful for wastewater treatment.  相似文献   
846.
From August 1992 to July 1996, 57 patients with closed femoral fractures were treated by external fixator in the Orthopaedic and Traumatology Clinics, School of Medicine, Dicle University. The technique was applied to children with closed femoral fractures. Their mean age was 6 (range 4-12) years old. The mean hospitalisation period was 8 (range 5-15) days. Fixators were removed on an average of 55 (range 38-79) days. The mean follow-up period was 18 (range 9-36) months. Pintract infection was observed in 3 and refracture in 1 patient. Infection was controlled with oral antibiotics and local dressing. An external fixator was applied to a patient in whom refracture developed. No patient had malunion, nonunion, or leg length discrepancy. We propose that external fixation in closed femoral shaft fractures of children could be a rational alternative mode of therapy, since it has some advantages and can be easily removed without undergoing a second round of anaesthesia.  相似文献   
847.
Evaluation of a physical length scale for granular materials   总被引:1,自引:0,他引:1  
Classical continuum mechanics considers the interaction of microstructural units of the material through stresses and displacements of material points. Therefore, conventional continuum mechanics approaches can not incorporate any intrinsic material length scale. However in reality interaction of grains may include rotations and the corresponding couple stresses as well, and real materials have a number of important length scales (e.g., grains, particles, fibers, etc.). An equation for determining the length scale is proposed. The proposed length scale equations include the effect of plastic deformation (microrotation), the effect of normal stress and contact area. The proposed length scale is implemented into elastic–elastoplastic Cosserat formulation. The effect of length scale on the finite element simulation and yield surface was evaluated by using the proposed length scale equation. The importance of length scale on the constitutive modeling of granular materials is analyzed in numerical simulations.  相似文献   
848.
The hammerhead ribozyme is capable of cleaving RNA substrates at 5' UX 3' sequences (where the cleavage site, X, can be A, C, or U). Hammerhead complexes containing dC, dA, dI, or rG nucleotides at the cleavage site have been studied by NMR. The rG at the cleavage site forms a Watson-Crick base pair with C3 in the conserved core of the hammerhead, indicating that rG substrates inhibit the cleavage reaction by stabilizing an inactive conformation of the molecule. Isotope-edited NMR experiments on the hammerhead complexes show that there are different short proton-proton distances between neighboring residues depending upon whether there is a dC or dA at the cleavage site. These NMR data demonstrate that there are significant differences in the structure and/or dynamics of the active-site residues in these hammerhead complexes. Molecular dynamics calculations were used to model the conformations of the cleavage-site variants consistent with the NMR data. The solution conformations of the hammerhead ribozyme-substrate complexes are compared with the X-ray structure of the hammerhead ribozyme and are used to help understand the thermodynamic and kinetic differences among the cleavage-site variants.  相似文献   
849.
BACKGROUND/AIMS: In the Western world, primary sclerosing cholangitis (PSC) is a chronic cholestatic liver disease that is associated with inflammatory bowel disease (IBD), particularly chronic ulcerative colitis and, to a lesser degree, Crohn's disease. The goal of this study was to determine the prevalence of PSC in Turkish patients with IBD and chronic amebic colitis, a disease that is endemic in Turkey. METHODOLOGY: During a 10-year period, between 1986 and 1996, a total of 81 IBD (64 ulcerative colitis and 17 Crohn's disease) patients and 127 patients with chronic amebic colitis were seen and evaluated with radiologic, serologic, immunologic and pathologic tests. Whenever a clinical or biochemical finding suggested the presence of co-existent hepatic and/or biliary disease, the patient was further evaluated by liver biopsy, auto-antibodies and endoscopic retrograde cholangiopancreatography (ERCP) to determine whether they also had PSC or some other form of liver disease. As a disease control group, a total of 752 patients with clinical and/or laboratory evidence of pancreaticobiliary disease were also studied. In 86 of these 752 patients (10%), a primary disorder of the biliary tree was diagnosed by ultrasonography, computed tomography, peritoneoscopy, liver biopsy, ERCP and abdominal laparotomy. In addition, all 86 patients of the control group were evaluated endoscopically in order to determine whether they had any associated gastrointestinal condition of the upper or lower gastrointestinal tracts. After establishing final diagnoses of IBD, amebic colitis and PSC, these patients were evaluated with respect to their socio-economic status. A high protein diet (1.8 gram/kg/day) was administered to those patients with chronic amebic colitis and IBD during the active period of the disease. RESULTS: Of the 208 patients (81 with IBD and 127 with chronic amebic colitis), no cases of PSC were identified. Of the 86 patients in the control group with primary biliary tract disease, 45 had a biliary system malignancy, 14 had primary biliary cirrhosis (PBC), 16 had PSC, 3 had Caroli's disease, 6 had a common bile duct cyst, and 2 had gallbladder adenomatosis. All but 1 of the 16 patients with PSC were female. CONCLUSIONS: These data suggest that, in contrast to findings in Western Europe and the USA, in Turkey: 1) PSC is not regularly associated with idiopathic IBD; 2) most patients with PSC are female; 3) PSC accounts for only 18% of patients with a primary disorder of the biliary tree; 4) the incidence of small-duct primary sclerosing cholangitis is greater than that reported in the literature; and, 5) the incidence of IBD and PSC in Turkey is relatively lower than in other countries.  相似文献   
850.
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