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121.
Managing protein–protein interactions is essential for resolving unknown biological events at the molecular level and developing drugs. We have designed and synthesized a side‐chain‐crosslinked helical peptides based on the binding domain of a pro‐apoptotic protein (Bad) that induces programed cell death. The peptide showed high helical content and bound to its target, Bcl‐XL, more strongly than its non‐crosslinked counterparts. When HeLa cells were incubated with the crosslinked peptide, the peptide entered the cytosol across the plasma membrane. The peptide formed a stable complex with Bcl‐XL localized at the outer mitochondrial membrane, and this binding event caused the release of cytochrome c from the intermembrane space of mitochondria into the cytosol. This activated the caspase cascade: 70 % of HeLa cells died by the apoptosis pathway (without evidence of necrosis).  相似文献   
122.
Rab11b, abundantly enriched in endocytic recycling compartments, is required for the establishment of the machinery of vesicle trafficking. Yet, no report has so far characterized the biological function of Rab11b in osteoclastogenesis. Using in vitro model of osteoclasts differentiated from murine macrophages like RAW-D cells or bone marrow-derived macrophages, we elucidated that Rab11b served as an inhibitory regulator of osteoclast differentiation sequentially via (i) abolishing surface abundance of RANK and c-Fms receptors; and (ii) attenuating nuclear factor of activated T-cells c1 (NFATc-1) upstream signaling cascades, following RANKL stimulation. Rab11b was localized in early and late endosomes, Golgi complex, and endoplasmic reticulum; moreover, its overexpression enlarged early and late endosomes. Upon inhibition of lysosomal function by a specific blocker, chloroquine (CLQ), we comprehensively clarified a novel function of lysosomes on mediating proteolytic degradation of c-Fms and RANK surface receptors, drastically ameliorated by Rab11b overexpression in RAW-D cell-derived osteoclasts. These findings highlight the key role of Rab11b as an inhibitor of osteoclastogenesis by directing the transport of c-Fms and RANK surface receptors to lysosomes for degradation via the axis of early endosomes-late endosomes-lysosomes, thereby contributing towards the systemic equilibrium of the bone resorption phase.  相似文献   
123.
The proton conduction and superionic phase transition of cesium dihydrogen phosphate, CsH2PO4 (CDP), were investigated under various humid conditions to evaluate the applicability of a CsH2PO4 solid electrolyte to an intermediate temperature fuel cell operating between 230 °C and 300 °C. The phase stability, superionic phase transition, and reversibility of dehydration of CsH2PO4 were evaluated under different ambient water vapor concentrations, from 0 to 90 mol%, through the measurements of conductivity. The dependence of conductivity on the water vapor concentration and the demonstrated reversibility of dehydration clearly showed the range in which CsH2PO4 is applicable to the intermediate temperature fuel cell. Additionally, we evaluated the protonic transport number of CsH2PO4, which was almost unity, and demonstrated fuel cell operation at 250 °C using a single cell fabricated with the CsH2PO4 electrolyte.  相似文献   
124.
The Fertile Crescent of the Middle East region, embracing Syria, eastern Turkey and Iraq, marks the region where settled agriculture began, and where the landscape has been shaped for millennia by human activities. The lacustrine and fluvial terraces of the Late Pleistocene and Holocene Eras are common geomorphic features in many areas around Lake Van in eastern Turkey, being sustainably used since the Urartian Period (800–400 years bc ). Fluctuations in the water levels of Lake Van have resulted in the development of widely distributed natural terraces around the Lake. The undulating slopes of these terraces have limited their cultivation, however, leading people to reconstruct terraces as a means for utilizing particular production sites, as anthroscapes (this concept is generally confined to situations where marked differences or deviations from the normal, natural landscapes are attributable to effects/shaping by humans). The region exhibits semiarid climatic conditions and a short crop‐growing season, currently being under the threat of land degradation. Recent mismanagement of these lands as a result of increasing population pressures has led to the degradation of both the natural and the man‐made terraces. Thus, there is an urgent need to conserve and understand the indigenous management and soil quality attributes of these man‐made terraces. To this end, this study examined soil profiles and analysed soil samples for their chemical, physical and mineralogical characteristics, in order to determine the human effects of leaching and/or accumulation. These analyses revealed significant differences between the physical, chemical, microbiological and mineralogical properties of the man‐made/reworked terraces and natural terraces under essentially similar parent materials and environment, thereby providing clues as to the sustainable management of these land surfaces in eastern Turkey. The approaches used in this study provide useful evidence for attempting to explain the historical evolution of land use in similar environments elsewhere, as well as the significance of terraces in combating coastal erosion in lake environments.  相似文献   
125.
Porous carbon was prepared by carbonization from agro-waste such as rice husk and barley straw to evaluate the adsorption of precious and base metals from metal solutions. The effects of hydrochloric acid concentration, metal ion concentration, and contact time on adsorption were examined. Rice husk carbon was found to be highly selective for Au(III) and inert to Pt(IV), Pd(II) and other base metals. Barley straw carbon adsorbed these three precious metal ions, but was inert to base metal ions such as Cu(II), Fe(III) and Ni(II). The maximum adsorption capacity of rice husk carbon for Au(III) was 0.76 mol/kg and the maximum adsorption capacity of barley straw carbon for Au(III), Pt(IV) and Pd(II) was 1.47, 0.39 and 0.64 mol/kg, respectively. The effectiveness of recovery of precious metals from industrial solution was also tested and barley straw carbon was found to be highly efficient and selective for the targeted metal ions in the presence of excess of other metal ions. Rice husk and barley straw carbon are thus potential alternatives to commercially available activated carbon as they have high selectivity and are efficient with low production costs.  相似文献   
126.
Study of the friction error for a high-speed high precision table   总被引:3,自引:0,他引:3  
Friction is one of the important factors resulting in the contour error of feed servo systems for high-speed, high precision CNC machine tools. A mathematical model of a high speed high precision feed servo table with PID controlling has been established with consideration of friction effects. The friction can be calculated according to the sliding speed and the oil film between the two contact surfaces by using a two-component mixed friction model. The protrusion error occurring at the quadrant boundary in the circular motion is profoundly studied by means of numerical simulation and experiments under different work conditions, and the conclusion that the quadrant protrusion error lags with the rising of the feed rate is obtained. Comparisons between the simulation results and the experimental results demonstrate that with the mathematical model, the dynamics of high speed high precision servo feed systems under PID controlling can be accurately simulated, and the friction error and its characteristics in the course of feeding can be precisely predicted.  相似文献   
127.
In this paper, an adaptive control method is proposed for systems whose structures can be divided into a known part and an unknown part. A non‐adaptive control design, such as H∞ control design can be introduced into the known part of the system, and adaptive control can cope with the unknown part to realize the property designed by non‐adaptive control. This is achieved by means of backstepping. This method is applied to the control design of an active suspension system for a railway vehicle, which is divided into two parts: a main car body part and an actuator part. Some simulation results of the control system designed using H∞ control for the body part and adaptive control for the actuator part are provided.  相似文献   
128.
Platinum nanowires and nanoparticles were selectively synthesized in mesoporous silicas FSM-16 and HMM-1. The nanowires are 3 nm in diameter and several hundred nm to μm in length with high crystallinity. Pt nanowires and nanoparticles can be isolated by dissolving silica matrix with HF. The Pt wires extracted from organosilica HMM-1 have a nanonecklace structure, while the wires from siliceous FSM-16 have a nanorod structure. The extracted Pt nanoparticles (3 nm in size) on HOPG show the Coulomb staircase phenomena in STM/STS analysis. The mechanism for formation of the Pt nanowires is based on the migration of Pt ions in the mesoporous channels.  相似文献   
129.
We performed a dynamical-atomistic study of radiation-induced amorphization in the NiTi intermetallic compound using in situ high-resolution high-voltage electron microscopy and molecular dynamics simulations in connection with image simulation. Spatio-temporal fluctuations as non-equilibrium fluctuations in an energy-dissipative system, due to transient atom-cluster formation during amorphization, were revealed by the present spatial autocorrelation analysis.  相似文献   
130.
The vortex-lattice method has been found very satisfactory in the case of steady subsonic wing theory, however, the discrete numerical methods, such as the vortex-lattice method, have not been studied in detail for supercavitating flows. One of the discrete numerical method, a vortex-lattice method, is developed in the present paper for cavitating flows around a two dimensional flat plate foil. The governing equations in the linear theory are represented as a set of coupled integral equations with Cauchy kernel, and there are unknown functions which are not under integral signs. For solving them, they are exchanged to an alternative set of coupled integral equations by a new variable, and the present vortex-lattice method is schemed for equal spacing of the vortices and sources in this new variable. The position of the collocation points is determined, and it is sufficient to treat unknown functions which are not integral signs as step functions. Moreover, the proof of the convergence of this method is shown and the accuracy is estimated.  相似文献   
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