Thermomechanical Properties of Carbon Nanocomposites PEGDA Photopolymers

In this work, UV-curable resin poly (ethylene glycol) diacrylate (PEGDA) was reinforced with three different types of nanofillers: pristine graphene (G), multiwalled carbon nanotubes (MWNTs), and a hybrid of MWNTs and graphene 70/30 in mass ratio (Hyb). PEGDA was mixed homogenously with the nanofiller oligomer by shear mixing and then photopolymerized, affording thin, stable films. The thermomechanical properties of the afforded nanocomposites indicated the superior reinforcing ability of pristine graphene compared with MWNTs and an intermediate behavior of the hybrid.     

Vibrational spectra of spinels with cation ordering on the octahedral sites

Infrared and Raman spectra are reported for compounds with 1 : 1, 1 : 3, and 1 : 2 mixed ordering on the octahedral sites of the spinel structure. The spectra of the superstructures are complex with many more bands observed than occur in the parent spinel structure, although less than were predicted by group theoretical analysis. A qualitative interpretation of the spectra can be made through the large Brillouin zone concept.     

Impact of protein flexibility on hydride-transfer parameters in thermophilic and psychrophilic alcohol dehydrogenases

The hydride transfer catalyzed by thermophilic alcohol dehydrogenase (htADH) exhibits sharply different kinetic and activation parameters from that catalyzed by the more flexible psychrophilic alcohol dehydrogenase (psADH). In addition, the hydride transfer in htADH is affected by mutating two distal residues that are suggested to be responsible for the decreased local protein flexibility in htADH. These observations provide support for the view that protein dynamics is tightly coupled to the hydrogen-transfer processes in these enzymes.     

Comparative analysis of ancient ceramics by neutron activation analysis,inductively coupled plasma-optical-emission spectrometry,inductively coupled plasma-mass spectrometry,and X-ray fluorescence

The accurate measurement of the maximum possible number of elements in ancient ceramic samples is the main requirement in provenance studies. For this reason neutron activation analysis (NAA) and X-ray fluorescence (XRF) have been successfully used for most of the studies. In this work the analytical performance of inductively coupled plasma-optical-emission spectrometry (ICP-OES) and inductively coupled plasma-mass spectrometry (ICP-MS) has been compared with that of XRF and NAA for the chemical characterization of archaeological pottery. Correlation coefficients between ICP techniques and XRF or NAA data were generally better than 0.90. The reproducibility of data calculated on a sample prepared and analysed independently ten times was approximately 5% for most of the elements. Results from the ICP techniques were finally evaluated for their capacity to identify the same compositional pottery groups as results from XRF and NAA analysis, by use of multivariate statistics.     

A facile preparation of 1-(6-hydroxyindol-1-yl)-2,2-dimethylpropan-1-one

An effective synthesis of 1-(6-hydroxyindol-1-yl)-2,2-dimethylpropan-1-one (4) was developed starting from 1H-indole (2). The key step involved suitable utilization of 4-(1-pyrrolidino)pyridine for the removal of the chloroacetyl moiety from chloroacetic acid 1-(2,2-dimethylpropionyl)-1H-indol-6-yl ester (3); a possible mechanism is, also, presented. Compound 4 might lead to selectively substituted derivatives, either on the phenolic-OH or the indolyl-NH, with putative biological interest. In this respect, we found that the core structure of 1H-indol-6-ol (1) possesses a degree of aldose reductase inhibitory potential, at a concentration of 100 microM.     

Anisotropic exchange interactions in hetero-one-dimensional Ln–M systems (Ln = Er,Yb; M = Cr,FeLS): Magnetometry and Dual Mode X-band Electron Paramagnetic Resonance spectroscopic studies

A recently introduced experimental and theoretical procedure is presented in order to calculate the magnitude and anisotropy of interaction between a lanthanide and a 3d-metal ion. The general formula of the hetero-one-dimensional molecular compounds is trans-[M(CN)₄(μ-CN)₂Ln(H₂O)₄(bpy)]_n·nH₂O · 1.5nbpy (M = Fe³⁺, Cr³⁺; Ln = Er³⁺, Yb³⁺), where bpy = 2,2′-bipyridine, abbreviated as [LnM] from now on. The main parts of this procedure are: (a) the evaluation of the effective g-parameters of the lanthanide ion with the help of EPR measurements; (b) the use of dual-mode EPR spectroscopy to define the anisotropic exchange interactions with the help of an anisotropic Hamiltonian model; (c) use of the same magnetic model to fit magnetization and susceptibility data in order to verify the EPR findings.     

Preparation and characterization of electrophoretically deposited high-temperature superconductor coatings

The high-temperature superconductor, YBa₂Cu₃O_7–x (x = 0.1–0.2) [YBCO], was prepared using an optimized calcination and sintering process. Thin layers of a few microns of this material were deposited on a silver substrate by applying a simplified electrophoretic deposition technique in a suspension of the fine, < 10 m, superconductor powder in a non-aqueous liquid. To get a uniform and strongly adherent coating, the deposition process is repeated several times, followed by an appropriate sintering procedure. The initially prepared YBCO powder and the coatings produced were characterized for their superconducting properties by X-ray diffraction analysis (XRD), magnetization measurements with a Superconducting Quantum Interference Device (SQUID) and electrical resistivity measurements. By scanning electron microscopy (SEM) and electron probe microanalysis (EPMA) the grain size of the YBCO film, its thickness and impurity content, respectively, were estimated.     

On a new edge function on complete weighted graphs and its application for locating Hamiltonian cycles of small weight

In this paper, we define a new combinatorial function on the edges of complete weighted graphs. This function assigns to each edge of the graph the sum of the weights of all Hamiltonian cycles that contain the edge. Since this function involves the factorial function, whose exact calculation is intractable due to its superexponential asymptotic rate of increase, we also introduce a normalized version of the function that is efficiently computable. From this version, we derive an upper bound to the weight of the minimum weight Hamiltonian cycle of the graph based on the weights of the graph edges. Then we investigate the possible algorithmic applications of this normalized function using the Nearest Neighbor Heuristic and a smallest edge first heuristic. As evidence for its applicability, we show that the use of this function as a criterion for the selection of the next edge, improves the performance of both heuristics for approximating the minimum weight Hamiltonian cycles in Euclidean plane graphs. Moreover, our experimental results show that the use of the function is more suitable with the structure of the smallest edge first heuristic since it provides a solution closer to the best known solution of known hard TSP instances but in \(O(n^3)\) time.     

Cytoprotective efficacy of amifostine against radiation- induced rectal toxicity: objective and subjective grading scales for radiomucositis

Curative radiation therapy of pelvic malignancies, frequently results in dose limiting toxicities such as serous, mucoid, or more rarely, bloody diarrhea. Several studies have evaluated the cytoprotective effects of amifostine in preventing rectal mucositis associated with radiation treatment. We searched Medline for published comparative studies that evaluated the use of amifostine to reduce radiation-induced toxicity associated with pelvic irradiation. In ten studies there was an evidence-based cytoprotection (P less than 0.05)by amifostine. Although results are variable, current evidence suggests that amifostine may have a radioprotective effect in the rectal mucosa, particularly when administered intrarectally. Significant improvements were seen in both symptomatic and objective(rectosigmoidoscopy) end points. There is a need to conduct well-designed clinical trials with sufficient numbers of participants to confirm these findings together with a cost benefit study. Objective measurements using rectosigmoidoscopy are superior to subjective measures such as WHO or RTOG/EORTC toxicity grading scales.     

A systematic investigation of the CuCl2/H2mal/phen reaction system (H2mal = malonic acid): Solution and solid state studies of its products

The systematic investigation of the parameter space of the CuCl₂/H₂mal/phen reaction system in MeOH resulted in the isolation of seven different complexes either as mixtures or in pure form, six of which have been structurally characterized. The molar ratios of the reactants and the crystallization methods have been systematically varied, leading to the isolation of compounds [Cu(H₂O)(phen)(mal)] (1), [Cu(MeOH)(phen)(mal)] (2), [Cu₂Li₂Cl₂(phen)₂(mal)₂(MeOH)₄] (3), [Cu₂(phen)₄(mal)][CuCl(phen)(mal)](OH) (4), [CuCl(phen)₂]Cl (5), and [CuCl(phen)(mal)][CuCl(phen)₂][Cu(phen)₂(Hmal)]Cl (6). The coordination versatility of the malonato ligand has been confirmed by the presence of three different coordination modes and its two deprotonation states in compounds 1–6. Solution studies on methanolic solutions of 2–4 and 6 by mass spectrometry revealed the absence of parent ion peak and the presence of fragment ions of low relative abundance not previously found in their crystal structure, thus indicating decomposition and rearrangement/reorganization of the complexes in solution and confirming the dynamic character of their solutions. Compounds 3 and 4 have been also studied in the solid state by EPR spectroscopy and magnetic measurements.