Influence of temperature and strain rate on cohesive properties of a structural epoxy adhesive

Effects of temperature and strain rate on the cohesive relation for an engineering epoxy adhesive are studied experimentally. Two parameters of the cohesive laws are given special attention: the fracture energy and the peak stress. Temperature experiments are performed in peel mode using the double cantilever beam specimen. The temperature varies from −40 to + 80°C. The temperature experiments show monotonically decreasing peak stress with increasing temperature from about 50 MPa at −40°C to about 10 MPa at + 80°C. The fracture energy is shown to be relatively insensitive to the variation in temperature. Strain rate experiments are performed in peel mode using the double cantilever beam specimen and in shear mode, using the end notch flexure specimen. The strain rates vary; for peel loading from about 10⁻⁴ to 10 s⁻¹ and for shear loading from 10⁻³ to 1 s⁻¹. In the peel mode, the fracture energy increases slightly with increasing strain rate; in shear mode, the fracture energy decreases. The peak stresses in the peel and shear mode both increase with increasing strain rate. In peel mode, only minor effects of plasticity are expected while in shear mode, the adhesive experiences large dissipation through plasticity. Rate dependent plasticity, may explain the differences in influence of strain rate on fracture energy between the peel mode and the shear mode.     

Active perception for autonomous sensor systems

We have considered the problem of active perception interacting with a complex environment. The concept of perception provides a different means of awareness in an artificial system; it offers a classification process of the relevant features of an occurrence in the environment. We used a multidisciplinary perspective to show three active perception techniques: Direct perception, Sequential perception, and Direct perception with memory capabilities. The three case studies show that the way a system perceives the environment is highly dependent on the time sequence for the sensations and perceptions. Currently, we have developed the perception capabilities and the individual sensors in an artificial system. We are now in the process of fully integrating the perception concept from these three examples into a general platform.     

Diagnostics design for steady-state operation of the Wendelstein 7-X stellarator

The status of the diagnostic developments for the quasistationary operable stellarator Wendelstein 7-X (maximum pulse length of 30 min at 10 MW ECRH heating at 140 GHz) will be reported on. Significant emphasis is being given to the issue of ECRH stray radiation shielding of in-vessel diagnostic components, which will be critical at high density operation requiring O2 and OXB heating.     

Three amino acids in the C-linker are major determinants of gating in cyclic nucleotide-gated channels

The activation of cyclic nucleotide-gated (CNG) channels is a complex process comprising the initial ligand binding and a consecutive allosteric transition from a closed to an open configuration. The cone and olfactory CNG channels differ considerably in cyclic nucleotide affinity and efficacy. In each channel, the cyclic nucleotide-binding site is connected to the last transmembrane segment of the channel by a linker peptide (C-linker) of approximately 90 amino acids. Here we report that replacement of three amino acids in the cone C-linker by the corresponding amino acids of the olfactory channel (I439V, D481A and D494S) profoundly enhanced the cAMP efficacy and increased the affinities for cAMP and cGMP. Unlike the wild-type cone channel, the mutated channel exhibited similar single-channel kinetics for both cGMP and cAMP, explaining the increase in cAMP efficacy. We thus conclude that the identified amino acids are major determinants of channel gating.     

聚氨酯增稠剂在水性涂料中的作用机理及应用

应用增稠剂的目的是赋予该体系所需要的流变性能，增稠作用的关键因素是分子中有疏水和亲水部分，理想的增稠效果取决于各种涂料组份的相互配合。     

用于排除质量故障的多功能助剂

产品质量极端重要的，油漆的产品质量是按照质量控制程序，经严格、仔细检验的。然而，对于没有满足预定要求的那些批次，如何进行校＂是一个重要问题。对于那些泡沫太多、干燥时间太长、有流挂或表面缺陷的产品，该如何补救呢？采用液体助剂校正是消除这些缺陷的现实办法，它无需额外的研磨步骤就能搅入其中，本文列举了实例。     

The cGMP-Dependent Protein Kinase 2 Contributes to Cone Photoreceptor Degeneration in the Cnga3-Deficient Mouse Model of Achromatopsia

Mutations in the CNGA3 gene, which encodes the A subunit of the cyclic guanosine monophosphate (cGMP)-gated cation channel in cone photoreceptor outer segments, cause total colour blindness, also referred to as achromatopsia. Cones lacking this channel protein are non-functional, accumulate high levels of the second messenger cGMP and degenerate over time after induction of ER stress. The cell death mechanisms that lead to loss of affected cones are only partially understood. Here, we explored the disease mechanisms in the Cnga3 knockout (KO) mouse model of achromatopsia. We found that another important effector of cGMP, the cGMP-dependent protein kinase 2 (Prkg2) is crucially involved in cGMP cytotoxicity of cones in Cnga3 KO mice. Virus-mediated knockdown or genetic ablation of Prkg2 in Cnga3 KO mice counteracted degeneration and preserved the number of cones. Analysis of markers of endoplasmic reticulum stress and unfolded protein response confirmed that induction of these processes in Cnga3 KO cones also depends on Prkg2. In conclusion, we identified Prkg2 as a novel key mediator of cone photoreceptor degeneration in achromatopsia. Our data suggest that this cGMP mediator could be a novel pharmacological target for future neuroprotective therapies.     

Energy-Balance Modeling and Discrete Control for Single-Phase Grid-Connected PV Central Inverters

This paper presents a two-control loop design considering the nonlinear time-varying characteristics of a single-phase grid-connected photovoltaic (PV) full-bridge central inverter. The control scheme design is based on the energy-balance modeling of the PV system and enables the design of a voltage loop linear discrete controller ensuring the stability of the system for the whole range of PV array operating conditions. A set of experimental results carried out on a laboratory prototype is provided to validate the proposed approach.