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321.
We obtained the output characteristics in wurtzite Al0.15Ga0.85N/GaN MODFETs with the full band Monte Carlo method. The gate length Lg and the channel length Los in the device are 0.2 μm and 0.4 urn, respectively. In the output characteristics we found a differential negative resistance effect. That is, as VDS is a constant, initially, VDS increases with increasing VDS. When VDS exceeds a certain critical value, IDS decreases with increasing VDS. The analysis for velocity-field characteristics in wurtzite CaN, the distributions of the electric field and the electron velocity in the two dimensional electron gas channel indicates that the differential negative resistance effect of the electron average velocity results in the differential negative resistance effect of the output characteristics. The transient transport also is related to the differential negative resistance effect of the output characteristics. This effect only can be observed in the devices with very short channel.  相似文献   
322.
The study was based on the inverse relationship between the effect of attention on reaction time (RT) and the size of the area over which focal attention is allocated. Independent occurrence of this in 2 locations in the opposite hemifields would be evidence of attention splitting. In Exp 1, in which the 2 locations were denoted by empty boxes, there was an inverse relationship between size of the stimulated box and RT. Exp 2 replicated the finding with different stimulation conditions. In Exp 3, no relationship was found between RT and length of a cuing line. In Exp 4, in which attention was manipulated by central cues, there was an effect of box size on valid and neutral trials but not invalid trials. Observers could split focal attention and manipulate simultaneously 2 independent attentional foci on objects located in the opposite hemifields. (PsycINFO Database Record (c) 2010 APA, all rights reserved)  相似文献   
323.
The creation of a cross-link containing a disulfide into hemoglobin has been accomplished with a site-directed reagent, N,N'-bis(Cbz-cystinyl)bis(methyl phosphate) (1). This is prepared from the reaction of the bis acid chloride of N-protected cystine with dimethyl phosphate followed by O-demethylation with methyl iodide in acetone. Reaction with deoxyhemoglobin produces two main products: cross-linked hemoglobin as the bis(cystinyl amide) of the epsilon-amino group of the side chain of Lys-82 of the two beta subunits as well as material that has each of the same amino groups modified as the cysteinyl amide but not cross-linked. Addition of 2-mercaptoethanol cleaves the disulfide in the material that is not cross-linked while leaving the disulfide intact in the cross-linked species. Dithiothreitol reduces the disulfide in the cross-linked species as well as in the species that is not cross-linked. Spontaneous oxidation in air converts all of the reduced material to the cross-linked bis(cystinyl amide) of hemoglobin. The reagent permits controlled introduction of cystinyl groups at lysyl residues, leading to formation of sulfhydryl groups by reduction and the possibility of re-forming the cross-links or forming conjugates.  相似文献   
324.
This study provides a kinematic comparison of the response of 12 older persons (ages 60–70) and 12 young persons (ages 20–26 ) to a perturbation of object size during a reach-to-grasp movement. For 80 out of 100 trials, each participant reached to grasp an illuminated cylinder of either small or large diameter (0.7 and 8.0 cm, respectively). For 20 out of 100 trials, a visual perturbation occurred at movement onset. This perturbation consisted of a switch of illumination from 1 to the other cylinder. For the switch from large to small cylinder, participants changed the distal grasp from whole-hand prehension to precision grip. For the opposite switch, participants changed from precision grip to whole-hand prehension. The older participants successfully adapted to these perturbations but showed a more conservative approach. Generally the approach time as the hand neared the object was prolonged, and the coordination between transport and manipulation components was maintained when comparing perturbed with nonperturbed trials. Young participants showed a more flexible pattern with a decrease or loss of temporal coupling between the components.… (PsycINFO Database Record (c) 2010 APA, all rights reserved)  相似文献   
325.
326.
This paper presents the results of a research project aimed at developing haptic tools for virtual shape modelling resembling real tools like rakes and sandpaper used by modelers and designers in the real workshop. The developed system consists of a CAD (computer aided design) system enhanced with intuitive designer-oriented interaction tools and modalities. The system requirements have been defined on the basis of the observation of designers during their daily work, and translating the way they model shapes using hands and craft tools into specifications for the modelling system based on haptic tools.  相似文献   
327.
Programmable coacervates based on zwitterionic polymers are designed as dynamic materials for ion exchange bioseparation. These coacervates are proposed as promising materials for the purification of soft nanoparticles such as liposomes and extracellular vesicles (EVs). It is shown that the stimulus-responsiveness of the coacervates and the recruitment of desired molecules can be independently programmed by polymer design. Moreover, the polymeric coacervates can recruit and release intact liposomes, human EVs, and nanoalgosomes in high yields and separate vesicles from different types of impurities, including proteins and nucleic acids. This approach combines the speed and simplicity of precipitation methods and the programmability of chromatography with the gentleness of aqueous two-phase separation, thereby guaranteeing product stability. This material represents a promising alternative for providing a low-shear, gentle, and selective purification method for EVs.  相似文献   
328.
在水、盐等多种因素的长期共同影响下,珍贵的交河故城本体普遍形成了表层结皮剥蚀病害,引发遗址不可逆转的破坏。非饱和土的特性与其吸力大小密切相关,因此准确确定土水特征曲线是深入研究土遗址劣化机理的基本前提。针对交河遗址土配制NaCl含量不同的泥浆,采用5种吸力测定方法(盐溶液蒸气平衡法、露点水势仪、滤纸法、压力膜仪和高容量张力计)获取被测土体干燥过程中的总吸力和基质吸力,开展不同方法所得吸力值之间的差异分析,借助van Genuchten(vG)和FredlundXing(FX)两种模型拟合基质吸力的土水特征曲线。结果表明,NaCl对遗址土基质吸力几乎没有影响,但由于引发渗透吸力而使总吸力在高含水率段显著增大。不同吸力测定方法反映的遗址土持水特性大体相似;综合多组试验数据可降低曲线拟合误差,在全吸力范围内获得可靠的土水特征脱湿曲线。vG模型和FX模型的拟合效果都比较好,结果为进一步定量化分析土遗址表层结皮开裂病害的形成演变过程提供了科学依据。  相似文献   
329.
This work aims to establish if the assays recently introduced by EMA (Guideline on quality of transdermal patches-draft) and USP (Specific tests for transdermal delivery systems) to characterize transdermal patches (TP) are suitable for medicated plasters (MP). Six approved MP differing for type and characteristics of adhesive and backing layer were selected and characterized in terms of adhesive performances by tack, shear adhesion, peel adhesion and release liner removal tests and in vitro skin permeation. As far as the adhesive properties are concerned, the major drawback is related to the measurement of shear adhesion of MP made of an adhesive hydrogel and/or a stretchable backing layer which could be solved by reducing the applied load. Moreover, a concern on the mass balance prescribed by EMA draft for the acceptance of the results of in vitro penetration studies remains. Indeed, the acceptance range is narrow than that reported by Ph. Eur. requirement for uniformity of content. Finally, a novel calculation for evaluating the in vitro efficiency of MP in releasing the loaded drug through the skin was proposed.  相似文献   
330.
The etiopathogenesis of depression is not entirely understood. Several studies have investigated the role of inflammation in major depressive disorder. The present work aims to review the literature on the association between C-Reactive Protein (CRP) and depression. A systematic review was performed for the topics of ‘CRP’ and ‘depression’ using the PubMed database from inception to December 2021. Fifty-six studies were identified and included in the review. Evidence suggested the presence of dysregulation in the inflammation system in individuals with depression. In most studies, higher blood CRP levels were associated with greater symptom severity, a specific pattern of depressive symptoms, and a worse response to treatment. Moreover, about one-third of depressed patients showed a low-grade inflammatory state, suggesting the presence of a different major depressive disorder (MDD) subgroup with a distinct etiopathogenesis, clinical course, treatment response, and prognosis, which could benefit from monitoring of CRP levels and might potentially respond to anti-inflammatory treatments. This work provides robust evidence about the potential role of CRP and its blood levels in depressive disorders. These findings can be relevant to developing new therapeutic strategies and better understanding if CRP may be considered a valuable biomarker for depression.  相似文献   
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