商务办公必备,扫描笔的分类与选购

扫描笔是近年新兴的扫描产品,它又可以称为微型扫描仪或手刮式扫描笔,常见的扫描笔大小大约跟"折扇"差不多,甚者会更小。它最大的特点是携带方便,特别适合商务人士随身携带出差办公使用。一般购买它主要是用于扫描办公文件、身份证、名片或大型工程图等等。下面,小编带大家去深入了解扫描笔,让你能够知才善用。     

Molecular cloning, expression, and characterization of a functional single-chain Fv antibody to the mycotoxin zearalenone

The heavy-chain and kappa light-chain variable region genes of an antizearalenone hybridoma cell line (2G3-6E3-2E2) were isolated by PCR and joined by a DNA linker encoding peptide (Gly4Ser)3 as a single-chain Fv (scFv) DNA fragment. The scFv DNA fragment was cloned into a phagemid (pCANTAB5E) and expressed as a fusion protein with E tag and phage M13 p3 in Escherichia coli TG1. In the presence of helper phage M13K07, the scFv fusion protein was displayed on the surfaces of recombinant phages. High-affinity scFv phages were enriched through affinity selection in microtiter wells coated with zearalenone-ovalbumin conjugate. The selected recombinant phages were used to infect E. coli HB2151 for the production of soluble scFv antibodies. One selected clone (pQY1.5) in HB2151 secreted a soluble scFv antibody (QY1.5) with a high zearalenone-binding affinity (concentration required for 50% inhibition of binding, 14 ng/ml), similar to that of parent monoclonal antibody in a competitive indirect enzyme-linked immunosorbent assay. However, scFv QY1.5 exhibited higher cross-reactivity with zearalenone analogs and had greater sensitivity to methanol destabilization than the parent monoclonal antibody did. Nucleotide sequence analyses revealed that the light-chain portion of scFv QY1.5 had a nucleotide sequence identity of 97% to a mouse germ line gene VK23.32 in mouse kappa light-chain variable region subgroup V, whereas the heavy-chain nucleotide sequence was classified as mouse heavy-chain subgroup III (D) but without any closely related members having highly homologous complementarity-determining region sequences. The potential of soluble scFv QY1.5 for routine screening of zearalenone and its analogs was demonstrated with zearalenone-spiked corn extracts.     

Accelerated Aging of a Composite Explosive

A given formulation of a composite explosive was submitted to accelerated aging at 293 K, 333 K and 353 K for slightly over a year. Extensive determination of mechanical properties were conducted using an Instron Tester to characterize the aging process of the explosive as a whole. The change of elongation at maximum load can be fitted to a third-order reaction rate giving an enthalpy of activation (Δ Ha) for the aging process of (78 ± 5) kJ/mol. Although the change of stress at maximum load was a function of temperature, it could not be predicted by a simple correlation. Swelling, inverse gas chromatography and N₂O evolution by infrared were applied to the samples aged at 333 K. Swelling measurements show a regular increase with aging of the relative number of cross-linking. Inverse gas chromatography at 373 K in helium indicated a first-order kinetic aging process for every sample, but the rate constant (k) of the samples aged for 0, 30 and 60 days was slightly lower than the one for samples aged for 130, 250 and 375 days. The N₂O evolution measured at 338.5 K in vacuum by infrared absorption indicates an aging process consisting of two consecutive first-order reactions, the second one being ten times slower than the first one. The first stage, which was also studied by inverse gas chromatography, gives rate constants which are about half as large as those measured by chromatography and confirms the changes in behavior from the samples aged for 0, 30 and 60 days to the samples aged for 130, 250 and 375 days. These results are discussed in relation to an aging process by oxidative cross-linking of the binder and degradation of the solid explosive.     

Performance Analysis and Modeling of Thermally Sprayed Resistive Heaters

Many processes and systems require hot surfaces. These are usually heated using electrical elements located in their vicinity. However, this solution is subject to intrinsic limitations associated with heating element geometry and physical location. Thermally spraying electrical elements directly on surfaces can overcome these limitations by tailoring the geometry of the heating element to the application. Moreover, the element heat transfer is maximized by minimizing the distance between the heater and the surface to be heated. This article is aimed at modeling and characterizing resistive heaters sprayed on metallic substrates. Heaters were fabricated by using a plasma-sprayed alumina dielectric insulator and a wire flame-sprayed iron-based alloy resistive element. Samples were energized and kept at a constant temperature of 425 °C for up to 4 months. SEM cross-sectional observations revealed the formation of cracks at very specific locations in the alumina layer after thermal use. Finite-element modeling shows that these cracks originate from high local thermal stresses and can be predicted according to the considered geometry. The simulation model was refined using experimental parameters obtained by several techniques such as emissivity and time-dependent temperature profile (infra-red camera), resistivity (four-probe technique), thermal diffusivity (laser flash method), and mechanical properties (micro and nanoindentation). The influence of the alumina thickness and the substrate material on crack formation was evaluated.     

Geographical distribution of tuberculosis notifications in national surveys of England and Wales in 1988 and 1993: report of the Public Health Laboratory Service/British Thoracic Society/Department of Health Collaborative Group

Refractory hypotension with end-organ hypoperfusion is an ominous feature of inflammatory shock. In the past fifteen years, nitric oxide (a diffusible, short-lived product of arginine metabolism) has been found to be an important regulatory molecule in several areas of metabolism, including vascular tone control. Vascular endothelial cells constitutively produce low levels of nitric oxide that regulate blood pressure by mediating adjacent smooth-muscle relaxation. In an inflammatory shock state, cytokines, like interleukin-1 and tumor necrosis factor-alpha, induce a separate, high-output form of the enzyme that synthesizes nitric oxide in both endothelial and smooth-muscle cells. The ensuing high rates of nitric oxide formation result in extensive smooth-muscle relaxation, pressor refractory vasodilation, and--ultimately--shock. The concept of the pathogenesis of inflammatory shock explains many limitations of current therapies and may foster the development of new interventions to mitigate the effects of nitric oxide overproduction in this syndrome.     

Eosinophil markers in seasonal allergic rhinitis. Intranasal fluticasone propionate inhibits local and systemic increases during the pollen season

BACKGROUND: The purpose was to study activation markers of the eosinophil granulocytes in seasonal allergic rhinitis, and the impact of topical steroid therapy thereupon. METHODS: Sixty-three rhinitis patients with monoallergy to grass were examined before and at peak pollen season. Blood eosinophil count, eosinophil cationic protein (ECP), and eosinophil peroxidase (EPO) in serum and nasal lavage fluid were measured. During the season, patients were randomized to treatment with intranasal fluticasone propionate 0.1 mg o.d. (n=26), 0.2 mg o.d. (n=25), or placebo (n=12). Six healthy persons served as controls. RESULTS: During the season, all parameters, except nasal lavage ECP, increased in the placebo group (P<0.001-P<0.05). Significant differences were seen between the steroid groups and the placebo group for all parameters (P<0.001-P<0.05). Higher eosinophil count (P<0.05), serum EPO (P<0.02), and nasal lavage EPO (P<0.05) were found in patients before season than in controls. The following winter, 44 patients returned for repeated measurement. Lower levels of nasal lavage EPO were observed for patients than levels at the beginning of the season (P<0.0001). CONCLUSIONS: Intranasal fluticasone propionate reduced inflammation of the nasal mucosa, demonstrated locally by nasal lavage ECP and EPO, and systemically by blood eosinophils, serum ECP, and serum EPO. EPO seemed more sensitive than ECP as indicator of allergic inflammation. EPO demonstrated some perennial eosinophil activity in hay fever patients, increasing locally during spring.     

Early formation of sexually dimorphic glomeruli in the developing olfactory lobe of the brain of the moth Manduca sexta

The antennal lobes (ALs), the primary olfactory centers, of the moth Manduca sexta are sexually dimorphic. Only ALs of males possess the macroglomerular complex (MGC), the site of primary processing of information about the female's sex pheromone. To understand the development of identified, odor-specific olfactory glomeruli, we investigated the cellular events involved in the morphogenesis of the MGC by means of various fluorescence staining techniques and laser-scanning confocal microscopy. The MGC lies near the entrance of the antennal nerve into the AL of the adult male and comprises three glomeruli, the globular cumulus and two toroidal structures. The MGC forms during early stages of metamorphic adult development through a stereotyped sequence of coordinated changes in MGC-specific receptor axons, glial cells, and early-ingrowing projection neurons of the medial group of AL neurons. The MGC divisions are the earliest glomeruli to form in the male AL, and their basic organization is established within about 3 days after ingrowth of the first sensory axons. Despite their special anatomical features, the MGC glomeruli develop in a manner similar to that of the ordinary glomeruli. Comparison of the ALs of males and females reveals that two relatively large and early-developing glomeruli that are situated dorsolaterally in the female AL appear to be female-specific. Development of the sexually dimorphic glomeruli diverges immediately after the ingrowth of the first olfactory receptor axons, resulting in the formation of these large glomeruli in females and the MGC in males.     

Nutritional intervention and growth in children with chronic renal failure

During fifties there were at most few tens of persons in this country who believed in the future of computers and cybernetics. One group of such enthusiasts, headed by Antonín Svoboda, was working at a construction of the first Czech computer SAPO. The other group tried to analyse, anticipate, and prepare in advance various applications for the new systemic conceptions and for the information processing machines. Members of both groups met for discussions which opened prospects to the future and influenced many of other activities for a long time. At the early sixties, the Czechoslovak Cybernetic Society was established at the Czechoslovak Academy of Sciences and in 1962 the Main Problem Committee for the Medical Cybernetics was founded at the Department of Health. It coordinated majority of the research programmes in the medical cybernetics and informatics. In 1967-1969 the Committee prepared an extensive project of a medical information system (ZIS), but its accomplishment was finally blocked by the then authorities. However, interests for that topics kept growing and the new working places equipped with available computer technology were formed at the health and clinical centres. The first tentative lectures in medical cybernetics and biocybernetics at our faculty were introduced into the students curricula in the late sixties. Thematically, medical cybernetics subsequently differentiated into the medical informatics, simulations of biological and medical systems, and the biosignal analysis. The growing interest enabled to hold conferences since the middle of seventies, some of which were held periodically, sometimes with international participation. It is not possible in brevity to include the whole spectrum to those goal-directed activities nor to appraise adequately their future significance.