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71.
The accurate knowledge of the elastic properties of single-stranded DNA (ssDNA) is key to characterize the thermodynamics of molecular reactions that are studied by force spectroscopy methods where DNA is mechanically unfolded. Examples range from DNA hybridization, DNA ligand binding, DNA unwinding by helicases, etc. To date, ssDNA elasticity has been studied with different methods in molecules of varying sequence and contour length. A dispersion of results has been reported and the value of the persistence length has been found to be larger for shorter ssDNA molecules. We carried out pulling experiments with optical tweezers to characterize the elastic response of ssDNA over three orders of magnitude in length (60–14 k bases). By fitting the force-extension curves (FECs) to the Worm-Like Chain model we confirmed the above trend:the persistence length nearly doubles for the shortest molecule (60 b) with respect to the longest one (14 kb). We demonstrate that the observed trend is due to the different force regimes fitted for long and short molecules, which translates into two distinct elastic regimes at low and high forces. We interpret this behavior in terms of a force-induced sugar pucker conformational transition (C3′-endo to C2′-endo) upon pulling ssDNA.  相似文献   
72.
The CD73 pathway is an important anti-inflammatory mechanism in various disease settings. Observations in mouse models suggested that CD73 might have a protective role in kidney damage; however, no direct evidence of its role in human kidney disease has been described to date. Here, we hypothesized that podocyte injury in human kidney diseases alters CD73 expression that may facilitate the diagnosis of podocytopathies. We assessed the expression of CD73 and one of its functionally important targets, the C-C chemokine receptor type 2 (CCR2), in podocytes from kidney biopsies of 39 patients with podocytopathy (including focal segmental glomerulosclerosis (FSGS), minimal change disease (MCD), membranous glomerulonephritis (MGN) and amyloidosis) and a control group. Podocyte CD73 expression in each of the disease groups was significantly increased in comparison to controls (p < 0.001–p < 0.0001). Moreover, there was a marked negative correlation between CD73 and CCR2 expression, as confirmed by immunohistochemistry and immunofluorescence (Pearson r = −0.5068, p = 0.0031; Pearson r = −0.4705, p = 0.0313, respectively), thus suggesting a protective role of CD73 in kidney injury. Finally, we identify CD73 as a novel potential diagnostic marker of human podocytopathies, particularly of MCD that has been notorious for the lack of pathological features recognizable by light microscopy and immunohistochemistry.  相似文献   
73.
Dermatophilus congolensis is a bacterial pathogen mostly of ruminant livestock in the tropics/subtropics and certain temperate climate areas. It causes dermatophilosis, a skin disease that threatens food security by lowering animal productivity and compromising animal health and welfare. Since it is a prevalent infection in ruminants, dermatophilosis warrants more research. There is limited understanding of its pathogenicity, and as such, there is no registered vaccine against D. congolensis. To better understanding the genomics of D. congolensis, the primary aim of this work was to investigate this bacterium using whole-genome sequencing and bioinformatic analysis. D. congolensis is a high GC member of the Actinobacteria and encodes approximately 2527 genes. It has an open pan-genome, contains many potential virulence factors, secondary metabolites and encodes at least 23 housekeeping genes associated with antimicrobial susceptibility mechanisms and some isolates have an acquired antimicrobial resistance gene. Our isolates contain a single CRISPR array Cas type IE with classical 8 Cas genes. Although the isolates originate from the same geographical location there is some genomic diversity among them. In conclusion, we present the first detailed genomic study on D. congolensis, including the first observation of tet(Z), a tetracycline resistance-conferring gene.  相似文献   
74.
Journal of Chemical Ecology - There is increasing evidence that microorganisms, particularly fungi and bacteria, emit volatile compounds that mediate the foraging behaviour of insects and therefore...  相似文献   
75.
Internally humidified, edge-air-cooled PEFC stacks are promising for portable systems in terms of specific power and specific cost. However, their main drawbacks are thermal power limitations due to limited heat removal from inside the stack. The aim of this work is to minimize the cooling limitation with a simultaneous cost and weight reduction by optimization of the stack geometry. A steady-state, thermal FE-model was developed and validated against experimental temperature distributions. The model includes anisotropic heat conduction and heat convection by the cooling air. Cell voltage, liquid water fraction and limiting temperature were experimentally determined for improved accuracy. Complex flowfield structures were approximated with the numerical volume averaging method to reduce computational cost. As a result of the optimization study specific power was improved by +86% with simultaneous reduction of specific cost by −3535%.  相似文献   
76.
A hardware neural network is presented that combines digital signalling with analog computing. This allows a high amount of parallelism in the synapse operation while maintaining signal integrity and high transmission speed throughout the system. The presented mixed-mode implementation achieves a synapse density of 4 k per mm2 in 0.35 μm CMOS. The current-mode operation of the analog core combined with differential neuron inputs reaches an analog precision sufficient for 10 bit parity while running at a speed of 0.8 Teraconnections per second.  相似文献   
77.
Gravity and magnetism are implemented to change the morphology of zinc oxide nanorod sensors during synthesis. The effects of gravity and magnetism can translate into future application of these nanorods through cost‐effective, environmentally friendly, and easy‐to‐use biosensor technology with the quickest available sensing. The sensors can pave the way toward detection of both bacteria and fungi present on the surface with high sensitivity. This ability to sense microorganisms in a “non‐solution‐based” environment represents a key step forward in the fields of health and food safety, as well as solid‐state nanomaterial biotechnology applications. Hundreds of thousands of people are affected each year by accidental contamination and current protocols are far from preventative. The results of the magnetic field studies when compared with previous results show that the following factors affect the outcome of applying magnetic field during the growth of nanorods on their morphology: the direction of growth with respect to gravity, the method of seeding, and the substrate.  相似文献   
78.
The energy level alignment between organic semiconductors (OSCs) and the respective (metal) electrodes in organic electronic devices is of key importance for efficient charge carrier injection. For many years, researchers have attempted to control this energy level alignment by means of functional self‐assembled monolayers or the insertion of thin injection layers (made, e.g., of doped OCSs or pure dopants). The present work demonstrates an alternative to these approaches, namely the use of phthalocyanine monolayers as contact primers, which are deposited onto noble metal electrodes by means of vacuum deposition. It is shown that polar as well as non‐polar phthalocyanines modify the work functions of clean Au(111) and Ag(111) surfaces as a function of their coverage and thus enable quantitative control of the metal work functions. This behavior is successfully replicated for the respective polycrystalline metal surfaces and it is found that full monolayers can even withstand air exposure when protected by sacrificial multilayers, which are afterward removed by thermal desorption.  相似文献   
79.
Scheduling algorithms play an important role for TDMA-based wireless sensor networks. Existing TDMA scheduling algorithms address a multitude of objectives. However, their adaptation to the dynamics of a realistic wireless sensor network has not been investigated in a satisfactory manner. This is a key issue considering the challenges within industrial applications for wireless sensor networks, given the time-constraints and harsh environments. In response to those challenges, we present SAS-TDMA, a source-aware scheduling algorithm. It is a cross-layer solution which adapts itself to network dynamics. It realizes a trade-off between scheduling length and its configurational overhead incurred by rapid responses to routes changes. We implemented a TDMA stack instead of the default CSMA stack and introduced a cross-layer for scheduling in TOSSIM, the TinyOS simulator. Numerical results show that SAS-TDMA improves the quality of service for the entire network. It achieves significant improvements for realistic dynamic wireless sensor networks when compared to existing scheduling algorithms with the aim to minimize latency for real-time communication.  相似文献   
80.
The stellarator Wendelstein 7-X is under construction at the Max-Planck-Institut für Plasmaphysik in Greifswald. Its superconducting coil system is fixed by a massive structure. During machine operation the coils exert high forces and moments against each other and the central support structure (CSS). Therefore, the detailed analysis of the coil to CSS connections, the so-called central support elements (CSE), is a critical item. The major details of the design have been frozen; nevertheless, there is still need for detailed analysis of the CSEs due to assembly issues, and later on for exploring operational limits of the machine. These analyses have to be performed quickly, reliably, and shall provide results in a standardized form to enable timely responses to the assembly team. Special numerical tools – finite element (FE) parametric models of CSEs – have been developed for the purpose of such analyses. In the models, the geometry, material properties, contact conditions, loads as well as results presentation are defined in a parametric way. The use of the developed models for the definition of the final weld parameters, bolt preloads, assessment of acceptable tolerances, and optimal positions of the CSE-wedges before welding is also discussed.  相似文献   
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