Photocatalytic self-assembled solid porphyrin microcrystals from water-soluble porphyrins: Synthesis,characterization and application

In this article, we report on the formation of a photocatalytic porphyrin crystalline structure using two oppositely charged commercially available low cost porphyrins, [meso-tetra(N-methy-4-pyridyl)porphyrin tetratosylate (TMPyP) and zinc-tetrakis(4-sulfonatophenyl)porphyrin (Zn-TPPS)], by self-assembly at room temperature without acidification. Using optical microscopy, the crystals were determined to have a length of 30–55 μm and width of 2–50 μm, depending on the molar ratio of the porphyrins in the starting solution. The porphyrin crystals were characterized by means of powder X-ray diffraction and UV–Vis, fluorescence, and optical microscopic techniques. The UV–Vis absorbance spectrum of the crystalline structure is different than those of the monomer solutions, involving a broadened Soret band that is split into two blue-shifted and red-shifted peaks and broadened red-shifted Q-bands. The crystals exhibit a different emission spectrum from those of the porphyrin solutions in that they are red-shifted, split, and show a dramatic decrease in intensities. A hypothetical model for the crystal structure of the porphyrin crystals is developed. Illumination of the crystals in a 2,4,6-trinitrotoluene solution with a tungsten lamp results in TNT reduction to 1,3,5-trinitrobenzene and 4-amino-2,6-dinitrotoluene.     

Approach to local thermodynamic equilibrium and the evolution to a glassy core following neutron/ion radiation impact

Using molecular dynamics simulations and statistical-mechanical metrics, we make quantitative predictions on the local thermodynamic and dynamic states following an ion or neutron impact in three materials – copper, silicon and solid argon. Through a two-energy distribution, we first capture the non-equilibrium temperature evolution and the approach to the local thermal equilibrium in three generic stages. By examining the time-resolved van Hove self-correlator, we then demonstrate that the impact core of all the three materials shows the dynamic characteristics of a jammed or glassy state. We delineate a dynamic atom-hopping mechanism that attests to a rapid defect recovery stage in copper; silicon, on the contrary, accommodates only small displacements which resist recovery. The dissimilitude between copper with a close-packed structure and silicon with an open network structure is further drawn out through an isoconfigurational analysis of displacements, which shows a compact dendritic-like condensation front for the mobile atoms in copper through atom hopping. In contrast, silicon portrays larger-scale spatial oscillations of dynamically separated regions, which appear to be a precursor to dynamic lattice instability and eventual amorphisation.     

An instantaneous replenishment model under the effect of a sampling policy for defective items

We propose to study a EOQ-type inventory model with unreliable supply, with each order containing a random proportion of defective items. Every time an order is received, an acceptance sampling plan is applied to the lot, according to which only a sample is inspected instead of the whole lot. If the sample conforms to the standards, i.e. if the number of imperfect items is below an “acceptance number”, no further screening is performed. Otherwise, the lot is subject to 100% screening. We formulate an integer non-linear mathematical program that integrates inventory and quality decisions into a unified profit model, to jointly determine the optimal lot size and optimal sampling plan, characterized by a sample size, and an acceptance number. The optimal decisions are determined in a way to achieve a certain average outgoing quality limit (AOQL), which is the highest proportion of defective items in the outgoing material sold to customers. We provide a counter-example demonstrating that the expected profit function, objective of the mathematical program, is not jointly concave in the lot and sample size. However, we show that for a given sampling plan, the expected profit function is concave in the lot size. A solution procedure is presented to compute the optimal solution. Numerical analysis is provided to gain managerial insights by analyzing the impact of changing various model parameters on the optimal solution. We also show numerically that the optimal profit determined using this model is significantly higher when compared to the optimal profit obtained using Salameh and Jaber (2000)’s [1] model, indicating much higher profits when acceptance sampling is used.     

Algèbre Pré-Gerstenhaber à homotopie près

This paper is concerned by the concept of algebra up to homotopy for a structure defined by two operations . and $[,]$. An important example of such a structure is the Gerstenhaber algebra (i.e. commutatitve structure with degree 0 and Lie structure with degree ?1). The notion of Gerstenhaber algebra up to homotopy ($G_{\infty }$ algebra) is known: it is a codifferential bicogebra.Here, we give a definition of pre-Gerstenhaber algebra (pre-commutative and pre-Lie) allowing a similar construction for a $\text{pre}{G}_{\infty }$ algebra.Given a structure of pre-commutative (Zinbiel) and pre-Lie algebra and working over the corresponding Koszul dual operads, we will give an explicit construction of the associated pre-Gerstenhaber algebra up to homotopy: it is a bicogebra (Leibniz and permutative) equipped with a codifferential which is a coderivation for the two coproducts.     

A Comparative Study of Fluorescein Isothiocyanate-Encapsulated Silica Nanoparticles Prepared in Seven Different Routes for Developing Fingerprints on Non-Porous Surfaces

Preparation of fluorescein isothiocyanate (FITC)-encapsulated silica nanoparticles (F-SiNPs) via seven different approaches to be used as developing agents for fingerprints detection is presented in this report. In this study, the suitability of each synthesis route toward incorporation of the selected fluorophore into silica matrix and its efficiency in fingerprints detection were systematically studied. The composition of the particles was designed to examine the hydrophobic and dipole-dipole interactions between the silicate backbone and both of the fluorescent reporter molecules and the fingerprint residues. F-SiNPs were prepared with two conventional sol-gel approaches; the Stöber method and the water in oil reverse microemulsion (WORM) method. The alkoxysilane precursor, tetraethoxyorthosilicate (TEOS) and its binary mixtures with phenyltriethoxysilane (PTEOS) or 3-aminopropyl triethoxysilane (APTES) have been used in preparing the F-SiNPs to study the effect of nanoparticles composition on fingerprints development. In addition, FITC was conjugated with APTES so it can be covalently bonded to the silica matrix and to be compared with non-covalently FITC-doped SiNPs. Moreover, the enhancement effect of introducing polyvinylpyrrolidone (PVP) onto the surface of the less hydrophobic F-SiNP on fingerprints detection on different non-porous surfaces was also investigated. The mean diameters of the F-SiNPs were between 4.1?±?0.6 and 110.4?±?31.1 nm as obtained from the TEM size measurement for the nanoparticles prepared by the WORM and Stöber methods, respectively. The obtained results clearly highlight the advantages of using a mixture of TEOS and PTEOS alkoxysilane precursors in preparing F-SiNPs with remarkable encapsulation efficiency and clear detection of fingerprints due to efficient embedding of the fluorophore inside the silica network even without conjugation. It was also observed that both the Stöber and WORM methods can be used in preparing the F-SiNPs developing agents and that PVP coated particles did not show any significant enhancement in fingerprints visualization.     

Improved LIBS limit of detection of Be, Mg, Si, Mn, Fe and Cu in aluminum alloy samples using a portable Echelle spectrometer with ICCD camera

Laser-induced breakdown spectroscopy (LIBS) is a laser-based technique that can provide non-intrusive, qualitative and quantitative measurement of metals in various environments. LIBS uses the plasma generated by a high-energy laser beam to prepare and excite the sample in one step. In the present work, LIBS has been applied to perform elemental analysis of six trace elements simultaneously in aluminum alloy targets. The plasma is generated by focusing a pulsed Nd:YAG laser on the target in air at atmospheric pressure. LIBS limit of detection (LOD) is affected by many experimental parameters such as interferences, self-absorption, spectral overlap and matrix effect. We aimed to improve the LIBS LOD by optimizing these experimental parameters as possible. In doing so, a portable Echelle spectrometer with intensified CCD camera was used to detect the LIBS plasma emission. This advanced Echelle spectrometer provides a constant spectral resolution (CSR) of 7500 corresponding to 4 pixels FWHM over a wavelength range 200–1000 nm displayable in a single spectrum. Then, the calibration curves for iron, beryllium, magnesium, silicon, manganese and copper as minor elements were achieved with linear regression coefficients between 98–99% on average in aluminum standard sample alloys. New LOD values were achieved in the ppm range with high precision (RSD 3–8%). From the application view point, improving LIBS LOD is very important in the on-line industrial process control to follow-up multi-elements for the correct alloying in metals.     

The Effect of Hemodialysis on Voice: An Acoustic Analysis

Because respiration is part of the well-coordinated process necessary for phonation, this study was conducted with the purpose of analyzing the effect of chronic hemodialysis on voice characteristics of patients with chronic renal failure. A total of 57 patients were recruited for the study, including 31 males and 26 females ranging in age from 16 to 85 years. Patients underwent evaluation of their voice directly before and after hemodialysis using the Kay Elemetric VISI Pitch (Model 330; Kay Elemetric Corporation, Lincoln Park, New Jersey). The vocal acoustic parameters studied include habitual pitch, pitch range, relative average perturbation, shimmer, noise-to-harmonic ratio, voice turbulence index, maximum phonation time, and voice energy. The data were analyzed using the paired t-test for the total sample and the nonparametric test for the female and male subgroups. The total sample analysis showed a statistically significant increase in the habitual pitch after the hemodialyis (p < 0.05), with a borderline increase in the pitch range and maximum phonation time (p < 0.10). In the female group, there was a statistically significant increase in the habitual pitch and a borderline increase in the relative average perturbation. In the male group, there was a significant increase in the habitual pitch with a borderline increase in maximum phonation time. Discussion of the after-mentioned results is presented.     

Hit-optimization using target-directed dynamic combinatorial chemistry: development of inhibitors of the anti-infective target 1-deoxy-d-xylulose-5-phosphate synthase

Target-directed dynamic combinatorial chemistry (tdDCC) enables identification, as well as optimization of ligands for un(der)explored targets such as the anti-infective target 1-deoxy-d-xylulose-5-phosphate synthase (DXPS). We report the use of tdDCC to first identify and subsequently optimize binders/inhibitors of the anti-infective target DXPS. The initial hits were also optimized for their antibacterial activity against E. coli and M. tuberculosis during subsequent tdDCC runs. Using tdDCC, we were able to generate acylhydrazone-based inhibitors of DXPS. The tailored tdDCC runs also provided insights into the structure–activity relationship of this novel class of DXPS inhibitors. The competition tdDCC runs provided important information about the mode of inhibition of acylhydrazone-based inhibitors. This approach holds the potential to expedite the drug-discovery process and should be applicable to a range of biological targets.

Target-directed dynamic combinatorial chemistry was used for hit-identification and subsequent hit-optimization for the anti-infective target 1-deoxy-d-xylulose-5-phosphate synthase resulting in novel inhibitors with low micromolar affinities.     

Concise synthesis of 2-amino-4(3H)-quinazolinones from simple (Hetero)aromatic amines

A novel and simple method of preparation of 2-alkylaminoquinazolin-4-ones with fused heteroaromatic rings from easily accessible (hetero)aromatic amines is described. The method is very efficient, and the 2-alkylaminoquinazolinone derivatives are obtained in three steps without chromatographic purification. The key step is the ring closure of the N-protected guanidine intermediates by intramolecular Friedel-Craft's type substitution.     

Experimental and density functional theory insights into the effect of withdrawing ligands on the fluorescence yield of Ru(II)‐based complexes

The quality of emission spectra of metal complexes gives good insights into their performance in many optoelectronic applications. Herein, the effect of the number and position of various ligand structures on the emission spectra of Ru bipyridine complexes was studied. Specifically, the use of a different number of withdrawing groups (COOH) was investigated in detail. The complexes were first investigated using density functional theory (DFT) and time‐dependent DFT calculations and then confirmed experimentally. The bandgap energy, reactivity, emission spectra and Stokes shift were found to depend on the number and position of the withdrawing groups attached to the Ru(bpy)₂²⁺ complexes. Upon increasing the number of withdrawing groups, the electrons were found to be withdrawn from the carbon orbitals and resonated to reach the metal, and accumulated around it, thus enhancing the metal‐to‐ligand charge transfer mechanism instead of the ligand‐to‐ligand charge transfer mechanism. The complexes with more withdrawing groups showed spectra with more intense emission peaks with shorter lifetime, indicating the enhancement in the photoactivity of the complexes. Ligands with ring nitrogens with two COOH groups showed the greatest effect on the enhancement of the emission spectra with a lifetime of 0.5359 ns. The resulting collective emission spectra covered a wide wavelength range, making the investigated complexes a good choice for many optoelectronic applications.