Self-Assembled Germanium Quantum-Dot Supercrystals in Silicon with Extremely Low Thermal Conductivities for Thermoelectrics

Superlattices with one-dimensional (1D) phonon confinement were studied to obtain a low thermal conductivity for thermoelectrics. Since they are composed of materials with a lattice mismatch, they often show dislocations. Like 1D nanowires, they also decrease heat transport in only one main propagation direction. It is therefore challenging to design superlattices with a thermoelectric figure of merit ZT higher than unity. Epitaxial self-assembly is a major technology to fabricate three-dimensional (3D) Ge quantum-dot (QD) arrays in Si. They have been used for quantum and solar-energy devices. Using the atomic-scale phononic crystal model, 3D Ge QD supercrystals in Si also present an extreme reduction of the thermal conductivity to a value that can be under 0.04 W/m/K. Owing to incoherent phonon scattering, the same conclusion holds for 3D supercrystals with moderate QD disordering. As a result, they might be considered for the design of highly efficient complementary metal–oxide–semiconductor (CMOS)-compatible thermoelectric devices with ZT possibly much higher than unity. Such a small thermal conductivity was only obtained for two-dimensional layered WSe₂ crystals in an experimental study. However, electronic conduction in the Si/Ge compounds is significantly enhanced. The 0.04 W/m/K value can be computed for different Ge QD filling ratios of the Si/Ge supercrystal with size parameters in the range of current fabrication technologies.     

In Situ Mine Water Treatment: Field Experiment at the Flooded Königstein Uranium Mine (Germany)

Within the WISMUT environmental remediation programme, the rehabilitation of the former uranium mine at Königstein is a very special case due to its use of underground leaching and its location near the Elbe River. The mine water is acidic, oxidizing, and polluted with uranium and other contaminants, and must be pumped to the surface and treated. In-situ water treatment approaches have been investigated to optimise further flooding and shorten the period of conventional water treatment. In 2010/2011, a field-scale experiment was carried out: about 120 t of alkalinity were successfully injected into the partially flooded mine. Tracer signals and geochemical reactions achieved general expectations. Based on the results, a site-specific technology concept was developed to flood the mine to its natural decant level.     

Efficient computation based on stochastic spikes

The speed and reliability of mammalian perception indicate that cortical computations can rely on very few action potentials per involved neuron. Together with the stochasticity of single-spike events in cortex, this appears to imply that large populations of redundant neurons are needed for rapid computations with action potentials. Here we demonstrate that very fast and precise computations can be realized also in small networks of stochastically spiking neurons. We present a generative network model for which we derive biologically plausible algorithms that perform spike-by-spike updates of the neuron's internal states and adaptation of its synaptic weights from maximizing the likelihood of the observed spike patterns. Paradigmatic computational tasks demonstrate the online performance and learning efficiency of our framework. The potential relevance of our approach as a model for cortical computation is discussed.     

Bee Bread Ameliorates Vascular Inflammation and Impaired Vasorelaxation in Obesity-Induced Vascular Damage Rat Model: The Role of eNOS/NO/cGMP-Signaling Pathway

Obesity and hyperlipidemia are major risk factors for developing vascular diseases. Bee bread (BB) has been reported to exhibit some biological actions, including anti-obesity and anti-hyperlipidemic. This study aims to investigate whether bee bread can ameliorate vascular inflammation and impaired vasorelaxation activity through eNOS/NO/cGMP pathway in obese rats. Forty male Sprague-Dawley rats were randomly divided into four groups (n = 10/group), namely: control (normal group), obese rats (OB group), obese rats treated with bee bread (0.5 g/kg/day, OB/BB group) and obese rats treated with orlistat (10 mg/kg/day, OB/OR group). The latter three groups were given a high-fat diet (HFD) for 6 weeks to induced obesity before being administered with their respective treatments for another 6 weeks. After 12 weeks of the total experimental period, rats in the OB group demonstrated significantly higher Lee obesity index, lipid profile (total cholesterol, triglyceride, low-density lipoprotein), aortic proinflammatory markers (tumor necrosis factor-α, nuclear factor-κβ), aortic structural damage and impairment in vasorelaxation response to acetylcholine (ACh). Bee bread significantly ameliorated the obesity-induced vascular damage manifested by improvements in the lipid profile, aortic inflammatory markers, and the impaired vasorelaxation activity by significantly enhancing nitric oxide release, promoting endothelial nitric oxide synthase (eNOS) and cyclic guanosine monophosphate (cGMP) immunoexpression. These findings suggest that the administration of bee bread ameliorates the impaired vasorelaxation response to ACh by improving eNOS/NO/cGMP-signaling pathway in obese rats, suggesting its vascular therapeutic role.     

A Cell-Free Multi-enzyme Cascade Reaction for the Synthesis of CDP-Glycerol

CDP-glycerol is a nucleotide-diphosphate-activated version of glycerol. In nature, it is required for the biosynthesis of teichoic acid in Gram-positive bacteria, which is an appealing target epitope for the development of new vaccines. Here, a cell-free multi-enzyme cascade was developed to synthetize nucleotide-activated glycerol from the inexpensive and readily available substrates cytidine and glycerol. The cascade comprises five recombinant enzymes expressed in Escherichia coli that were purified by immobilized metal affinity chromatography. As part of the cascade, ATP is regenerated in situ from polyphosphate to reduce synthesis costs. The enzymatic cascade was characterized at the laboratory scale, and the products were analyzed by high-performance anion-exchange chromatography (HPAEC)-UV and matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI-TOF-MS). After the successful synthesis had been confirmed, a design-of-experiments approach was used to screen for optimal operation conditions (temperature, pH value and MgCl₂ concentration). Overall, a substrate conversion of 89 % was achieved with respect to the substrate cytidine.     

Microtensile testing of submicrometer thick functional polymer samples

Organic electronic devices are currently being introduced in commercial applications such as flexible displays. Due to the mechanical loading of these devices during bending, it is important to know the mechanical properties in order to assess reliability. It is therefore essential to develop experimental setups for the mechanical characterization of submicrometer thick functional polymer layers. In this paper a new microtensile approach is presented along with first results for Young's modulus of polyimide (PI) and the conductive polymer PEDOT:PSS obtained using this method. The microtensile specimen are made of a bilayer consisting of PI as the substrate layer and of a submicron layer of PEDOT:PSS deposited on top of it. The mechanical properties are derived from comparison of measurements performed on samples with and without the functional layer and by varying this layer's thickness. A thorough error analysis is also presented to provide an overview of the precision inherent in this approach. The experiments yield Young's moduli of 3.28 ± 0.34 GPa for PI and of 4.51 ± 0.34 GPa for PEDOT:PSS.     

Effects of Microbial Utilization of Phenolic Acids and their Phenolic Acid Breakdown Products on Allelopathic Interactions

Reversible sorption of phenolic acids by soils may provide some protection to phenolic acids from microbial degradation. In the absence of microbes, reversible sorption 35 days after addition of 0.5–3 mol/g of ferulic acid or p-coumaric acid was 8–14% in Cecil A_p horizon and 31–38% in Cecil B_t, horizon soil materials. The reversibly sorbed/solution ratios (r/s) for ferulic acid or p-coumaric acid ranged from 0.12 to 0.25 in A_p and 0.65 to 0.85 in B_t horizon soil materials. When microbes were introduced, the r/s ratio for both the A_p and B_t horizon soil materials increased over time up to 5 and 2, respectively, thereby indicating a more rapid utilization of solution phenolic acids over reversibly sorbed phenolic acids. The increase in r/s ratio and the overall microbial utilization of ferulic acid and/or p-coumaric acid were much more rapid in A_p than in B_t horizon soil materials. Reversible sorption, however, provided protection of phenolic acids from microbial utilization for only very short periods of time. Differential soil fixation, microbial production of benzoic acids (e.g., vanillic acid and p-hydroxybenzoic acid) from cinnamic acids (e.g., ferulic acid and p-coumaric acid, respectively), and the subsequent differential utilization of cinnamic and benzoic acids by soil microbes indicated that these processes can substantially influence the magnitude and duration of the phytoxicity of individual phenolic acids.     

Design of an Ultrafast G Protein Switch Based on a Mouse Melanopsin Variant

The primary goal of optogenetics is the light-controlled noninvasive and specific manipulation of various cellular processes. Herein, we present a hybrid strategy for targeted protein engineering combining computational techniques with electrophysiological and UV/visible spectroscopic experiments. We validated our concept for channelrhodopsin-2 and applied it to modify the less-well-studied vertebrate opsin melanopsin. Melanopsin is a promising optogenetic tool that functions as a selective molecular light switch for G protein-coupled receptor pathways. Thus, we constructed a model of the melanopsin G_q protein complex and predicted an absorption maximum shift of the Y211F variant. This variant displays a narrow blue-shifted action spectrum and twofold faster deactivation kinetics compared to wild-type melanopsin on G protein-coupled inward rectifying K⁺ (GIRK) channels in HEK293 cells. Furthermore, we verified the in vivo activity and optogenetic potential for the variant in mice. Thus, we propose that our developed concept will be generally applicable to designing optogenetic tools.     

产品开发过程中的危机管理

产品开发过程的危机通常无法避免,而应对危机并非一件易事．欲使危机的负面影响降至最低,运用规范的方法应对危机尤显重要．针对目前产品开发的行为特征,提出产品开发过程中应对危机的行为模式．