Glycerolipids as Selective Thrombin Inhibitors from the Fungus Stereum Hirsutum

ABSTRACT

A dry extract of Stereum hirsutum exhibited a significant inhibitory activity on thrombin (34%). A bioassay oriented fractionation of the extract of Stereum hirsutum has led to the isolation of two active fractions. On the basis of spectroscopic data, chemical reactions, and GC-MS analysis, complex mixtures of diacylglycerophospholipids (DAGPs) and diacylglycerols (DGs) have been isolated and identified. Docking studies suggest that some isolated compounds could bind to the thrombin active site in a similar manner as previously reported phosphonate thrombin inhibitors.     

Characterization and modeling of transition edge sensors for high resolution X-ray calorimeter arrays

Characterizing and understanding, in detail, the behavior of a Transition Edge Sensor (TES) is required for achieving an energy resolution of 2 eV at 6 keV desired for future X-ray observatory missions. This paper will report on a suite of measurements (e.g. impedance and I–V among others) and simulations that were developed to extract a comprehensive set of TES parameters such as heat capacity, thermal conductivity, and R(T,I), (T,I), and β_i(T,I) surfaces. These parameters allow for the study of the TES calorimeter behavior at and beyond the small signal regime.     

Characterization of antioxidant activity of extracts from Flos Lonicerae

Antioxidants are emerging as prophylactic and therapeutic agents for various diseases. However, little is known about the antioxidant property of the extract from Flos Lonicerae, a medically useful traditional Chinese medicine herb. Here the antioxidant capacity of water, methanolic and 70% ethanolic extracts prepared from Flos Lonicerae to scavenge DPPH radical and reduce Fe³⁺ to Fe²⁺ is evaluated. Chlorogenic acid, a major component of Flos Lonicerae, is identified and further purified from 70% ethanolic extract with HPLC and its antioxidant capacity is also characterized. The content of total phenolic compounds and chlorogenic acid in Flos Lonicerae is determined. The present results demonstrate that all Flos Lonicerae extracts examined here exhibit antioxidant activity and chlorogenic acid is a major contributor to this activity, which implicates that the Flos Lonicerae extract may serve as potential source of natural antioxidants for treatment of some diseases.     

Lamb wave-based quantitative identification of delamination in CF/EP composite structures using artificial neural algorithm

Delamination in composite structures plays a major role in lowering structural strength and stiffness, consequently downgrading system integrity and reliability. A Lamb wave-based quantitative identification technique for delamination in CF/EP composite structures was established. Propagation of Lamb waves in a series of composite laminates, individually bearing a delamination, was evaluated using dynamic FEM analyses. Taking advantage of wavelet transform and artificial neural algorithms, an Intelligent Signal Processing and Pattern Recognition (ISPPR) package was developed, by which the spectrographic characteristics of simulated Lamb wave signals in the time-frequency domain were extracted and digitised as Digital Damage Fingerprints (DDF), to construct a Damage Parameters Database (DPD). The DPD was then used offline to train a multi-layer feedforward artificial neural network (ANN) under supervision of an error-backpropagation (BP) algorithm. Assisted by an active online structural health monitoring (AO-SHM) system with an active piezoelectric actuator/sensor network, the proposed methodology was validated online by identifying actual delaminations in CF/EP (T650/F584) quasi-isotropic composite laminates.     

Sustained release of Semaphorin 3A from α-tricalcium phosphate based cement composite contributes to osteoblastic differentiation of MC3T3-E1 cells

The reinforcement of calcium phosphate materials with silk fibroin (SF) has been one of the strategies to overcome the brittleness. However, the lack of osteoinductivity may still restrict their further use. This study aimed to investigate the biocompatibility and osteogenesis capacity of a novel Semaphorin 3A-loaded chitosan microspheres/SF/α-tricalcium phosphate composite (Sema3A CMs/SF/α-TCP) in vitro. Sema3A was first incorporated into CMs, and the Sema3A CMs/SF/α-TCP composite was then prepared. The morphology of the CMs was observed using SEM. The in vitro release kinetics, cytotoxicity, and cell compatibility were evaluated, and the real-time quantitative polymerase chain reaction (RT-qPCR) and activity of alkaline phosphatase (ALP) were used to evaluate the osteogenesis capacity of the composite. The in vitro release of Sema3A from the Sema3A CMs/SF/α-TCP composite showed a temporally controlled manner. The extract of the Sema3A CMs/SF/α-TCP composite presented no obvious side effect on the MC3T3-E1 cell proliferation, nor promote cell proliferation. The MC3T3-E1 cells were well-spread and presented an elongated shape on the Sema3A CMs/SF/α-TCP composite surface; the ALP activity and the osteogenic-related gene expression were higher than those seeded on the surface of the CMs/SF/α-TCP and SF/α-TCP composites. In conclusion, Sema3A CMs/SF/α-TCP has excellent biocompatibility and contributes to the osteoblastic differentiation of MC3T3-E1 cells.     

Mobility and Effective Electric Field in Nonplanar Channel MOSFETs

The universal relationship of effective carrier mobility (mu_eff ) versus effective perpendicular electric field (E _eff ) in the channel was studied in nonplanar channel (NPC) mosfets. In general, E _eff is determined by bulk charge density ( Q _B), inversion charge density ( Q _i), and eta . The variable eta was shown to have a dependence on channel structure and was extracted from several NPC mosfets, such as pure double-gate (DG), gate-all-around (GAA), and silicon-on-insulator (SOI) Fin mosfet s. We derived E _eff expressions for the NPC mosfets for a given channel doping concentration. It was shown that large parasitic source/drain (S/D) resistance should be corrected to obtain accurate mu_eff. In the GAA structure, extracted eta decreased with increasing radius of the body wire. Width weight sum was applied to extract eta in the SOI FinFETs that consist of DG and GAA structures. From the mu_eff versus E _eff relation obtained by the C- V method, we could verify the validity of our approach.     

碱性溶液中不同微观结构的Fe-N/C催化剂氧还原性能的稳定性对比研究

Fe-N/C催化剂在氧还原反应中的作用机理对于开发高效、可持续使用的非贵金属催化剂在聚合物电解质膜燃料电池中的应用至关重要, 但目前仍存在很多的难以攻克的问题。为了揭示纳米结构与电化学活性的关系, 本研究开发了一种具有高电化学活性的Fe-N/C氧还原催化剂, 该催化剂含有Fe-N_x位点和被氮掺杂的碳纳米管包裹的Fe/Fe₃C纳米晶体两种具有氧还原反应电化学活性的纳米结构。尽管不含贵金属铂, 本研究合成的Fe-N/C催化剂在碱性条件下仍显示出较高的ORR活性, 半波电势为0.86 V(vs RHE), 质量活性为18.84 A/g(0.77 V(vs RHE), 极限电流密度为-4.3 mA·cm ^-2。同时, 电子转移数为3.7(0.2 V(vs RHE), 说明Fe-N/C催化剂中4电子ORR反应的比例较高。石墨烯包覆的金属Fe/Fe₃C纳米晶生长N-CNTs后, 材料的导电性有所提高, 并且Fe-N_x活性位点在Fe/Fe₃C纳米颗粒表面分布均匀, 改善了材料的电化学活性。本研究为非贵金属氧还原电催化剂的继续深入研究以及广泛应用于商业化生产提供了一定的借鉴和依据。     

Radiation spectra in GaN-based LEDs under thermal-injection processes

The effects of series current magnitude (I) upon the intrinsic UV luminescence band (λ370 nm) and the impurity of the blue band (λ430 nm) of a GaN LED has been investigated. The excess device temperature (ΔT_AR) of the GaN LED active region has been determined over a wide range of working currents. It has a linear behaviour for currents over 15 mA. The weaker dependence ΔT_AR(i) at i<15 mA is due to the fact that at forward biases V<E_g/e all the power terminated to the device is released in the space charge region (w≤0.3 μm).     

Characterization of mechanical properties of thin films using nanoindentation test

Using finite element modeling (FEM), this work investigates using finite element modeling (FEM) the mechanical behavior of film on substrate composites during the penetration of a rigid tip. In order to understand the magnitude of the substrate effect, the difference of strain gradient through the thickness of a given layer, deposited first on a softer substrate and then on an harder substrate can be observed. In this specific case, up to a critical ratio (h/t) = 0.35 (with h the indentation depth and t the film thickness), the mechanical behavior of the layer is quite similar. But, for h/t > 0.35, two different behaviors may be observed: (i) in the first case H_f/H_S  1 (with H_f and H_S, respectively, the film and substrate hardness values), the total strain remains contained within the film thickness up to a ratio h/t close to 1 and (ii) in the second case H_f/H_S  1, the total strain extends deeply into the substrate. These results show that the empirical 10% rule is not valid, even for a hard film on a softer substrate. The main error is caused by a wrong estimation of the contact depth between the indenter tip and the film surface. Indeed, the simulation runs exhibit the formation of pile-up depending on the ratios (h/t) and Y_f/Y_S (with Y_f and Y_S, respectively, the film and substrate yield stress values). As a function of the used model for calculating the contact depth, at least three variation of hardness may be found from load–displacement curves obtained by FEM. In these conditions, it seems ambiguous to try to determine a weighting function to extract meaningful mechanical properties of the thin film. Another way to determine film properties consists in using the loading phase. A relationship between the applied load (P) and the indentation depth (h) is studied during the loading phase. For the case of a soft film on harder substrate (H_f/H_S  1), it is possible to determine the yield stress of the film, from the previous relationship. This approach is applied to experimental amorphous Al₂O₃ films formed by electron beam evaporation on silicon substrate.     

Inactivation of E. coli and Pseudomonas aeruginosa by electrochloration under bipolar pulsed polarization

This work is devoted to the biocides effects by electrochlorination under a pulsated bipolar polarization (PBP) of low potentials (− 1 V/cm to + 1.6 V/cm). Two working electrodes were used, one in platinum and the other in AISI 430 stainless steel, in two different electrolytes: sterilized distilled water and 0,9N sterilized NaCl solution, contaminated by E. Coli or by Pseudomonas Aeruginosa. The inactivation of these bacteria was established under the action of three biocide treatments: E.F (Electric Field); the combination of E.F and Active Chlorine (A.C) and the combination of E.F, A.C and Ions in Solutions (I.S). The synergistic effect of these treatments leads to a high efficiency in disinfection. The results showed that the total inactivation of the E. Coli stain is reached in half a minute, while that of P. aeruginosa is reached in 20 min. The use of an economic stainless steel electrode allowed us to observe that, for pulsate frequencies higher than 10³ s^− 1, the formation of active chlorine increased whereas the corrosion speed decreased.     

Differential evolution solution to transformer no-load loss reduction problem

After the completion of core manufacturing and before the assembly of transformer active part, 2N small individual cores and 2N large individual cores are available and have to be optimally combined into N transformers so as to minimise the total no-load loss (NLL) of N transformers. This complex combinatorial optimisation problem is called transformer no-load loss reduction (TNLLR) problem. A new approach combining differential evolution (DE) and multilayer perceptrons (MLPs) to solve TNLLR problem is proposed. MLPs are used to predict NLL of wound core distribution transformers. An improved differential evolution (IDE) method is proposed for the solution of TNLLR problem. The modifications of IDE in comparison to the simple DE method are (i) the scaling factor F is varied randomly within some range, (ii) an auxiliary set is employed to enhance the population diversity, (iii) the newly generated trial vector is compared with the nearest parent and (iv) the simple feasibility rule is used to treat the constraints. Application results show that the performance of the proposed method is better than that of two other methods, that is, conventional grouping process and genetic algorithm. Moreover, the proposed method provides 7.3% reduction in the cost of transformer main materials.     

Use of CACO-2 Cells as an in vitro Intestinal Absorption and Metabolism Model

The Caco-2 cell line, a human colorectal carcinoma cell line, is an established in vitro model for the study of drug transport in the human intestine. We have routinely utilized this in vitro model to 1) elucidate intestinal absorption mechanisms of small drug molecules and peptide-like therapeutic agents (e.g. paracellular/transcellular passive diffusion and carrier-mediated active transport), 2) screen and select orally active therapeutic agents, 3) identify optimum luminal pH's for drug absorptions, 4) address dissolution rate-related absorption problems, 5) assess mucosal toxicity of therapeutic agents, and 6) evaluate prodrug approaches for enhanced drug absorptions. We have also utilized this in vitro model to assess the metabolic stability of therapeutic agents in the intestinal epithelium. Demonstrated in this report are primarily the techniques for the elucidation of absorption mechanisms. Examples of the characterization of paracellular/ transcellular passive diffusion pathways and carrier-mediated active transport will be given. Application of the Caco-2 model to the process of drug development will also be discussed.     

Experimental Evidence in Support of the Formation of Anionic Endohedral Metallofullerenes During Their Extraction with N,N-Dimethylformamide

In an effort to test possibility of the formation of anions of endohedral metallofullerenes (EMF, M@C_2n) during their extraction from EMF containing soot we study different EMF extracts applying electrospray ionization mass spectrometry (ESI-MS). The ESI-MS (negative mode) analysis of Y@C_2n and La@C_2n extracted by either N,N-dimethylformamide (DMF) or CS₂ reveals that under DMF extraction diamagnetic monoanionic EMF can be successfully generated that was also substantiated by study of interaction between DMF extract of Y@C_2n and bis(triphenylphosphoranylidene)ammonium chloride.     

The WiZard/CAPRICE silicon-tungsten calorimeter

A silicon-tungsten calorimeter has been developed to be flown in the WiZard/CAPRICE balloon borne experiment to measure the flux of antiprotons, positrons and light nuclei in the cosmic radiation. The calorimeter is composed of 8 x, y silicon sampling planes [active area (48 × 48) cm²] interleaved with 7 tungsten absorbers (7 radiation lengths); it provides the topology of the interacting events together with an independent measurement of the deposited energy. Details of the front-end electronics and of the read-out system are given and the overall performances during pre-flight ground operations are described as well.     

An efficient technique for detecting catastrophic convolutional codes

Catastrophic convolutional codes (CC) cause an infinite number of decoded data bit errors when decoding a finite number of code symbols. A CC displays a catastrophic error propagation if the generating polynomials have a common factor. An efficient algorithm for polynomial factorization in GF(2^m) is used for detecting catastrophic CC for any rate n/m and constraint length k. A general formula is derived to calculate the number of catastrophic codes in any (m, n, k) CC.     

Electrodeposition under a time-dependent boundary condition

The behaviour of the diffusion equation that results from assuming the boundary condition C(0,t)=C_b exp(−bt), with C_b (bulk concentration) and b constant, was examined. This condition reflects the behaviour of the diffusion around isolated nuclei growing onto a substrate. The diffusion equation under this boundary condition was solved and compared the results with the current transients obtained during electrodeposition. An expression for the fractional surface area of the deposit, S(t) and other parameters are obtained. The system reproduces the electrodeposition current transients in the chosen Cu²⁺/Cu couple and gives the values of the measured parameters at least within one order of magnitude. Some discrepancies between the theory and experimental results are examined and possible causes are suggested.     

Surface sulfonation of silk fibroin film by plasma treatment and in vitro antithrombogenicity study

To improve the blood compatibility of Bombyx mori silk fibroin (SF) film, the film was modified by SO₂ gas plasma treatment, or by a two-step process including NH₃ gas plasma treatment and reaction with 1,3-propane sultone. XPS and ATR-FTIR were used to analyze the surface chemical elements. In vitro antithrombogenicity was determined by the method of the activated partial thromboplastin time (APTT), prothrombin time (PT) and thrombin time (TT) tests. Percents of sulfur element on the surfaces of both modified SF films were 4.03% and 3.30%, respectively, while that of the control film was only 0.32%. Moreover, the antithrombogencity of treated films was increased remarkably due to surface sulfonation. The results implied a potential use of sulfonated SF for blood-contacting biomaterials.     

Protein-protein interaction studies based on molecular aptamers by affinity capillary electrophoresis

Protein-DNA/protein-protein interactions play critical roles in many biological processes. We report here the investigation of protein-protein interactions using molecular aptamers with affinity capillary electrophoresis (ACE). A human alpha-thrombin binding aptamer was labeled with 6-carboxyfluorescein and exploited as a selective fluorescent probe for studying thrombin-protein interactions using capillary electrophoresis with laser-induced fluorescence. A 15-mer binding DNA aptamer can be separated into two peaks in CE that correspond to the linear aptamer (L-Apt) and the thrombin-binding G-quadruplex structure in the presence of K(+) or Ba(2+). In a bare capillary, the peak area of G-quadruplex aptamer (G-Apt) was found to decrease with the addition of thrombin while that of L-Apt remained unchanged. Even though the peak of the G-Apt/thrombin binding complex is broad due to a weaker binding affinity between aptamer and thrombin, we were still able to quantify the thrombin and anti-thrombin proteins (human anti-thrombin III, AT III) based on the peak areas of free G-Apt. The detection limits of thrombin and AT III were 9.8 and 2.1 nM, respectively. The aptamer-based competitive ACE assay has also been applied to quantify thrombin-anti-thrombin III interaction and to monitor this reaction in real time. The addition of poly(ethylene glycol) to the sample matrix stabilized the complex of the G-Aptthrombin. This assay can be used to study the interactions between thrombin and proteins that do not disrupt G-Apt binding property at Exosit I site of the thrombin. Our aptamer-based ACE assay can be an effective approach for studying protein-protein interactions and for analyzing binding site and binding constant information in protein-protein and protein-DNA interaction studies.     

Second harmonic generation in alternate non-linear Langmuir-Blodgett films

Second harmonic generation experiments are performed in alternate multilayers of two non-linear molecules, the hydrophobic chain being grafted onto the acceptor group of the first species A and onto the donor group of the second species B. Two families of non-linear molecules are studied: p-aminobenzoic acid derivatives and diazostilbene derivatives. High χ⁽²⁾ values (around 5×10^-10 SI) and β values (around 10^-37 SI) are obtained for the diazostilbenes. The variation in the second harmonic intensity with respect to the number N of active layers is interpreted in terms of the disorder appearing in the upper monolayer of the Langmuir-Blodgett film.     

Enantioselective recognition of a pair of novel receptors for amino acid zwitterions

A pair of artificial enantiotopic receptors 1a, 1b composed of (S,S) or (R,R) chiral bicyclic guanidinium, azacrown ether and (t-butyldiphenylsilyloxy)methyl group for amino acid zwitterions have been synthesized. The liquid–liquid competition extraction experiments and ¹H NMR studies indicate that the receptor 1a with (S,S) configuration and 1b with (R,R) configuration selectively recognize - and -aromatic amino acids, respectively.