高性能汽车中的电源设计

引言 高可靠性、低成本、极短的研发周期等等相互冲突的设计要求迫使电源设计人员采用新的具有突破性的技术方案,而这些技术是传统的汽车电源设计中不曾涉足的。     

Defining business model key performance indicators using intentional linguistic summaries

Software and Systems Modeling - To sustain competitiveness in contemporary, fast-paced markets, organizations increasingly focus on innovating their business models to enhance current value...     

Evaluation of antioxidant and antimicrobial potential of strawberry tree (<Emphasis Type="Italic">Arbutus Unedo</Emphasis> L.) leaf

In present study, antioxidant and antimicrobial activities of strawberry tree (Arbutus unedo L.) leaves were investigated. Antioxidant activity was determined by methods of DPPH scavenging, β-carotene bleaching, reducing power, metal chelating, superoxide anion scavenging, and hydrogen peroxide scavenging activity. Total phenolic content were determined to be 197.16±1.43 mg GAE/g extract in aqueous extract. The EC₅₀ value of methanolic extracts was found to be 0.423 mg/mL. The extracts of leaves showed nearly 1/4 metal chelating capacity of standard EDTA, high reducing power, superoxide anion scavenging, and hydrogen peroxide scavenging activities. While the strawberry tree leaves exhibited antibacterial activity against Staphylococcus aureus, there was no inhibitory effect against Escherichia coli and Salmonella enteritidis. The strawberry tree leaves exhibited antifungal effect against 2 aflatoxigenic molds namely Aspergillus parasiticus NRRL 2999 and NRRL 465. These results suggest that the strawberry tree leaves may be used as an antioxidant source for pharmaceutical application, nutraceutical and functional food industries.     

Radioluminescence of SrAl2O4:Ln (Ln = Eu, Sm, Dy) phosphor ceramic

Phosphors for radiation detection require efficient energy transfer from the ionization track to the luminescent centers. In this work, the radioluminescence (RL) spectra of SrAl₂O₄ phosphor ceramics doped with individual trivalent rare earth element (REE) ions (Sm, Eu and Dy) are reported at the room temperature. Although there is some intrinsic UV/blue emission from the host lattice, the dominant signals are from the rare-earth sites, with signals characteristic of the REE²⁺ and REE³⁺ states. The shapes of the emission bands are different for each dopant. The sharp emission properties show that the SrAl₂O₄ is a suitable host for rare-earth ion doped phosphor material.     

Air embolism following removal of hemodialysis catheter

Introduction: Air embolism (AE) is a rare, but serious complication that can occur in the practice of hemodialysis. In contrast to careful techniques and meticulous care during insertions and manipulations of the central catheters, awareness of the risk of AE following catheter removal is less. We aimed to analyze the clinical characteristics of the all case reports with AE after catheter removal and summarize the mechanisms, clinical consequences, treatment and prevention of AE. Methods: In addition to our case, MEDLINE database was searched for all case reports with AE following catheter removal, and the clinical, diagnostic and outcome data were analyzed. Findings: A total of 10 patients (including our case) (M/F 6/4; median age 50.5 years) were found for the analysis. Procedures for prevention of AE were reported in a few patients (Trendelenburg position 2, airtight dressing 1). The time that elapsed between catheter removals and onset of AEs was ranged from seconds to 6 hours. The most common findings were dyspnea (90%), hypoxemia (70%), and cerebral dysfunction (70%). The most common sites where air could be detected were the left ventricle (40%), pulmonary artery (30%) and right ventricle (30%). Mortality was reported in 4 (40%) cases and the remaining 6 patients had complete recovery. Blocking of air portal was not reported in any of the fatal cases. Discussion: AE following catheter removal carries a major risk of mortality. Great awareness and attention to preventive procedures and appropriate care after development of AE seem mandatory.     

Two-dimensional natural convection in a porous triangular enclosure with a square body

A two-dimensional numerical solution for steady-state buoyancy induced convection in a right-triangular enclosure with a square body is obtained using finite difference technique. The solid body is located far from the origin with the distance of 0.3 in both directions. It is considered that the temperature of the bottom wall of triangular enclosure is higher than that of inclined wall while the vertical wall is insulated. To obtain the effects of the presence of a square body on heat transfer and fluid flow inside the enclosure, four different temperature boundary conditions were applied for the body as heated, cooled, neutral and adiabatic at different Ra numbers. It is observed that fluid flow and temperature fields strongly depend on thermal boundary conditions of the body.     

Peptide-mediated constructs of quantum dot nanocomposites for enzymatic control of nonradiative energy transfer

A bottom-up approach for constructing colloidal semiconductor quantum dot (QDot) nanocomposites that facilitate nonradiative Fo?rster-type resonance energy transfer (FRET) using polyelectrolyte peptides was proposed and realized. The electrostatic interaction of these polypeptides with altering chain lengths was probed for thermodynamic, structural, and morphological aspects. The resulting nanocomposite film was successfully cut with the protease by digesting the biomimetic peptide layer upon which the QDot assembly was constructed. The ability to control photoluminescence decay lifetime was demonstrated by proteolytic enzyme activity, opening up new possibilities for biosensor applications.     

Molecular and Electrophysiological Role of Diabetes-Associated Circulating Inflammatory Factors in Cardiac Arrhythmia Remodeling in a Metabolic-Induced Model of Type 2 Diabetic Rat

Background: Diabetic patients have prolonged cardiac repolarization and higher risk of arrhythmia. Besides, diabetes activates the innate immune system, resulting in higher levels of plasmatic cytokines, which are described to prolong ventricular repolarization. Methods: We characterize a metabolic model of type 2 diabetes (T2D) with prolonged cardiac repolarization. Sprague-Dawley rats were fed on a high-fat diet (45% Kcal from fat) for 6 weeks, and a low dose of streptozotozin intraperitoneally injected at week 2. Body weight and fasting blood glucose were measured and electrocardiograms of conscious animals were recorded weekly. Plasmatic lipid profile, insulin, cytokines, and arrhythmia susceptibility were determined at the end of the experimental period. Outward K⁺ currents and action potentials were recorded in isolated ventricular myocytes by patch-clamp. Results: T2D animals showed insulin resistance, hyperglycemia, and elevated levels of plasma cholesterol, triglycerides, TNFα, and IL-1b. They also developed bradycardia and prolonged QTc-interval duration that resulted in increased susceptibility to severe ventricular tachycardia under cardiac challenge. Action potential duration (APD) was prolonged in control cardiomyocytes incubated 24 h with plasma isolated from diabetic rats. However, adding TNFα and IL-1b receptor blockers to the serum of diabetic animals prevented the increased APD. Conclusions: The elevation of the circulating levels of TNFα and IL-1b are responsible for impaired ventricular repolarization and higher susceptibility to cardiac arrhythmia in our metabolic model of T2D.     

Peppermint Drying Performance of Contact Dryer in Terms of Product Quality,Energy Consumption,and Drying Duration

Drying is a commonly used postharvest operation for medicinal and aromatic plants. Their high initial moisture contents, requirement of moderate drying temperatures, and quick deterioration of their quality attributes make their drying processes energy intensive and time consuming. These properties may also cause the dried product to be of heterogeneous quality. A contact dryer that transferred energy to drying plants mainly by heat conduction was developed and tested by mixing or not mixing batches of 15 kg of chopped peppermint plants. The contact dryer had three main operational units: a drying table, a mobile mixing/aeration car, and a control panel. The contact dryer was operated with one of four drying programs. All programs affected the completion duration of drying, essential oil content, and dried product color differently. The shortest drying time (15 h) was obtained using the drying program of gradually increased water temperature from 55–60 to 75–80°C in 6 h and mixing/aeration. However, mixing and aeration changed the product color slightly more and partially increased essential oil loss. These drawbacks can be alleviated by selecting the appropriate duration of mixing and aeration. The menthol and menthone percentages of fresh peppermint essential oil ranged from 31.02 to 34.02% (average value: 32.52%) and 23.23 to 26.47% (average value: 24.85%), respectively. The menthol and menthone percentages of dried peppermint essential oil ranged from 22.74 to 42.07% and from 8.95 to 21.76%, respectively. The significant variations in the essential oil composition of dried peppermint leaves within replications were possibly caused by the variations associated with the age and cutting order of fresh peppermint plants at harvest.     

Response surface study on production of explosively-welded aluminum-titanium laminates

This research was undertaken to produce strong and stiff, aluminum-titanium, multi-layered composites (laminates) by explosive welding, for applications requiring light-weight. The purpose of lamination is to create a material with superior mechanical properties resulting from plastic deformation produced by shock wave passage throughout each layer and from the presence of the explosively welded interfaces. A response surface study was performed on these laminates to investigate the mechanical behavior of the laminates with changes in two characteristic variables, abundance of interfaces and volume percentage of the more ductile component. For this purpose, a total of eighteen laminates, nine of which were the basis of a central composite design, were produced. One-step welding of these laminates was achieved by explosives-introduced pressuring; the material was supported by thicker steel plates on both sides to reduce the harmful effects of detonation and to produce smooth top and bottom surfaces. Yield strength, ultimate tensile strength, and elongation data were collected from tensile tests. A second-order model was fitted and a three dimensional response surface was built to define the relationship among the mechanical properties (yield strength) of the laminates and two design variables. The fitted second-order model clearly shows that the mechanical properties of the laminates depend strongly on the relative amounts of the components but only weakly on the abundance of interfaces within the selected operability region.