Gap junction channels span the membranes of two adjacent cells and allow the gated transit of molecules as large as second messengers from cell to cell. The structure of the gap junction channel pore is not resolved. For identification of pore determinants we used a chimera of two connexins, cx46 and cx32E 1 43, that form membrane channels with distinct unit conductances and channel kinetics. Exchange of the first transmembrane segment (M1) between these connexins resulted in a chimera that exhibited most of the channel properties of the M 1 donor, including single channel conductance, channel kinetics, and the preference to dwell at a subconductance level. The M 1 segment thus appears to be an important determinant of conductance and gating properties of connexin channels.z 1999 Federation of European Biochemical Societies.

Flexible sensors are required to be lightweight, compatible with the skin, sufficiently sensitive, and easily integrated to extract various kinds of body vital signs during continuous healthcare monitoring in daily life. For this, a simple and low-cost flexible temperature and force sensor that uses only two carbon fiber beams as the sensing layer is reported in this work. This simple, flexible sensor can not only monitor skin temperature changes in real time but can also extract most pulse waves, including venous waves, from most parts of the human body. A pulse diagnostic glove containing three such flexible sensors was designed to simulate pulse diagnostic methods used in traditional Chinese medicine. Wearable equipment was also designed in which four flexible sensors were fixed onto different body parts (neck, chest, armpit, and fingertip) to simultaneously monitor body temperature, carotid pulse, fingertip artery pulse, and respiratory rate. Four important physiological indicators—body temperature (BT), blood pressure (BP), heart rate (HR), and respiratory rate (RR)—were extracted by the wearable equipment and analyzed to identify exercise, excited, tired, angry, and frightened body states.

Gap junction channels are intercellular channels that mediate the gated transfer of molecules between adjacent cells. To identify the domain determining channel conductance, the first transmembrane segment (M1) was reciprocally exchanged between Cx46 and Cx32E(1)43. The resulting chimeras exhibited conductances similar to that of the respective M1 donor. Furthermore, a chimera with the carboxy-terminal half of M1 in Cx46 replaced by that of Cx32 exhibited a conductance similar to that of Cx32E(1)43, whereas the chimera with only the amino-terminal half of M1 replaced retained the unitary conductance of wild-type Cx46. Extending the M1 domain swapping to other connexins by replacing the carboxy-terminal half of M1 in Cx46 with that of Cx37 yielded a chimera channel with increased unitary conductance close to that of Cx37. Furthermore, a point mutant of Cx46, with leucine substituted by glycine in position 35, displayed a conductance much larger than that of the wild type. Thus, the M1 segment, especially the second half, contains important determinants of conductance of the connexin channel.

Glucose is used aerobically and anaerobically to generate energy for cells. Glucose transporters (GLUTs) are transmembrane proteins that transport glucose across the cell membrane. Insulin promotes glucose utilization in part through promoting glucose entry into the skeletal and adipose tissues. This has been thought to be achieved through insulin-induced GLUT4 translocation from intracellular compartments to the cell membrane, which increases the overall rate of glucose flux into a cell. The insulin-induced GLUT4 translocation has been investigated extensively. Recently, significant progress has been made in our understanding of GLUT4 expression and translocation. Here, we summarized the methods and reagents used to determine the expression levels of Slc2a4 mRNA and GLUT4 protein, and GLUT4 translocation in the skeletal muscle, adipose tissues, heart and brain. Overall, a variety of methods such real-time polymerase chain reaction, immunohistochemistry, fluorescence microscopy, fusion proteins, stable cell line and transgenic animals have been used to answer particular questions related to GLUT4 system and insulin action. It seems that insulin-induced GLUT4 translocation can be observed in the heart and brain in addition to the skeletal muscle and adipocytes. Hormones other than insulin can induce GLUT4 translocation. Clearly, more studies of GLUT4 are warranted in the future to advance of our understanding of glucose homeostasis.

Rayleigh–Taylor-instability (RTI) induced flow and mixing are of great importance in both nature and engineering scenarios. To capture the underpinning physics, tracers are introduced to make a supplement to discrete Boltzmann simulation of compressible RTI flows. By marking two types of tracers with different colors, the tracer distribution provides a clear boundary of two fluids during the evolution. Fine structures of RTI flow and thermodynamic non-equilibrium behavior around the interface in a miscible two-fluid system are delineated. Distribution of tracers in their velocity phase space makes a charming pattern showing quite dense information on the flow behavior, which opens a new perspective for analyzing and accessing significantly deep insights into the flow system. RTI mixing is further investigated via tracer-defined local mixedness. The appearance of Kelvin–Helmholtz instability is quantitatively captured by the abrupt increase in mixedness averaged along the direction of acceleration. The role of compressibility and viscosity on mixing are investigated separately, both of which show a two-stage effect. The underlying mechanism of the two-stage effect is interpreted as the development of large structures at the initial stage and the generation of small structures at the late stage. At the late stage, for a fixed time, a saturation phenomenon of viscosity is found that a further increase in viscosity cannot lead to an evident decline in mixedness. The mixing statues of heavy and light fluids are not synchronous and the mixing of an RTI system is heterogeneous. The results are helpful for understanding the mechanism of flow and mixing induced by RTI.

In this paper, we discuss the competition between the stimulated Raman scattering (SRS) and stimulated Brillouin scattering (SBS) instabilities under the strong damping condition. Based on a five-wave interaction model, relations of the stationary backscattering reflectivity between SRS and SBS are deduced in the case of homogeneous plasmas. Developments of the two coexistent instabilities are simulated with different parameters. The density and the temperature of plasma are found to be important in determining which instability dominates the backscattering in the regime of competition. Furthermore, the influence of inhomogeneous condition to the pattern of competition is analyzed. Numerical results consist with our theoretical results.

used to learn the signals of the human grasping motion in a recent report. [15] However, most kinds of these sensors are aimed at simulating one type of stimulation. The ultimate goal of an electronic skin system requires to integrate these different kinds of sensors into a flexible, light, and thin planar array; however, this is a great challenge so far. If a sensing material has multisensing capability and the signals from different stimuli could be distinguished effectively by constructing different sensing structures, similar to different electronic devices being integrated into one silicon chip, the number of the sensors would decrease, and the difficulty in the integration of the electronic skin would be reduced. Fortunately, carbonbased sensing materials (such as carbon nanotubes, [16][17][18][19][20] graphene, [21][22][23][24] and carbon fibers. [25,26] ) have been recently reported to have not only strain sensing but also temperature sensing properties. This inspired us to construct different sensing structures based on the same carbon-based material to simultaneously detect pressure and temperature changes from the outside environment, and this product can be referred to as a touch sensor.Here, we report the feasibility to use only one single carbon fiber beam (CFB) to simultaneously detect pressure and temperature changes from the outside environment, and the signals from pressure and temperature stimuli can be distinguished through its transverse piezoresistance and longitudinal thermal resistance respectively. The flexible pressure sensors, temperature sensors, and their integrated sensors can be easily constructed like blocks to use the same material CFBs. Results and DiscussionIn our design model (as shown in Figure 1), a CFB is used that is usually composed of thousands of carbon fibers (CFs), where thousands of gaps exist between the carbon fibers. Once the carbon fiber beam receives a transverse pressure, these gaps between the CFs decrease, and the transverse resistance of the CFB (R ⊥ ) exponentially decreases, which contributes to an increasing probability of electron quantum tunneling between Electronic skins require to integrate multiple-sensing functions to sense stimuli from the outside environment (such as pressure, temperature, and humidity), and to distinguish the signals from the different stimuli. Here, reported is the feasibility to use only one single carbon fiber beam (CFB) to simultaneously detect pressure and temperature changes from the outside environment, and the signals from pressure and temperature stimuli can be effectively distinguished through its transverse piezoresistance and longitudinal thermal resistance. This work also reveals that the transverse piezoresistance follows the electron quantum tunneling between the carbon fibers, while the longitudinal thermal resistance follows the impurity scattering mechanism. The flexible pressure sensors, temperature sensors, and their integrated sensors can be easily constructed like blocks to use the same material CFBs, and the...

In this article, multiple eigen-systems including linear growth rates and eigen-functions have been discovered for the Rayleigh-Taylor instability (RTI) by numerically solving the Sturm-Liouville eigen-value problem in the case of two-dimensional plane geometry. The system called the first mode has the maximal linear growth rate and is just extensively studied in literature. Higher modes have smaller eigen-values, but possess multi-peak eigen-functions which bring on multiple pairs of vortices in the vorticity field. A general fitting expression for the first four eigen-modes is presented. Direct numerical simulations show that high modes lead to appearances of multi-layered spike-bubble pairs, and lots of secondary spikes and bubbles are also generated due to the interactions between internal spikes and bubbles. The present work has potential applications in many research and engineering areas, e.g., in reducing the RTI growth during capsule implosions in inertial confinement fusion.