Ab initio Molecular Dynamical Investigation of the Finite Temperature Behavior of the Tetrahedral Au19_{19} and Au20_{20} Clusters

Density functional molecular dynamics simulations have been carried out to understand the finite temperature behavior of Au$_{19}$ and Au$_{20}$ clusters. Au$_{20}$ has been reported to be a unique molecule having tetrahedral geometry, a large HOMO-LUMO energy gap and an atomic packing similar to that of the bulk gold (J. Li et al., Science, {\bf 299} 864, 2003). Our results show that the geometry of Au$_{19}$ is exactly identical to that of Au$_{20}$ with one missing corner atom (called as vacancy). Surprisingly, our calculated heat capacities for this nearly identical pair of gold cluster exhibit dramatic differences. Au$_{20}$ undergoes a clear and distinct solid like to liquid like transition with a sharp peak in the heat capacity curve around 770 K. On the other hand, Au$_{19}$ has a broad and flat heat capacity curve with continuous melting transition. This continuous melting transition turns out to be a consequence of a process involving series of atomic rearrangements along the surface to fill in the missing corner atom. This results in a restricted diffusive motion of atoms along the surface of Au$_{19}$ between 650 K to 900 K during which the shape of the ground state geometry is retained. In contrast, the tetrahedral structure of Au$_{20}$ is destroyed around 800 K, and the cluster is clearly in a liquid like state above 1000 K. Thus, this work clearly demonstrates that (i) the gold clusters exhibit size sensitive variations in the heat capacity curves and (ii) the broad and continuous melting transition in a cluster, a feature which has so far been attributed to the disorder or absence of symmetry in the system, can also be a consequence of a defect (absence of a cap atom) in the structure.Comment: 7 figure

Density functional investigation of the interaction of acetone with small gold clusters

The structural evolution of Aun (n = 2, 3, 5, 7, 9, and 13) clusters and the adsorption of organic molecules such as acetone, acetaldehyde, and diethyl ketone on these clusters are studied using a density functional method. The detailed study of the adsorption of acetone on the Aun clusters reveals two main points. (1) The acetone molecule interacts with one gold atom of the gold clusters via the carbonyl oxygen. (2) This interaction is mediated through back donation mainly from the spd-hybridized orbitals of the interacting gold atom to the oxygen atom of the acetone molecule. In addition, a hydrogen bond is observed between a hydrogen atom of the methyl group and another gold atom (not involved in the bonding with carbonyl oxygen). Interestingly, the authors notice that the geometries of Au9 and Au13 undergo a significant flattening due to the adsorption of an acetone molecule. They have also investigated the role of the alkyl chain attached to the carbonyl group in the adsorption process by analyzing the interaction of Au13 with acetaldehyde and diethyl ketone

Physicochemical Properties of Moringa oleifera Seeds and Their Edible Oil Cultivated at Different Regions in Egypt

Abstract Moringa oleifera is a plant that successfully grows recently in Egypt and has rich of nutrients seeds with valuable content of edible oil. The present study aimed at determining the physicochemical properties of moringa seeds and their extracted oil of which cultivated at different regions in Egypt. Obtained results revealed that protein, lipid, ash, fiber and total carbohydrate contents were in range of 34.51% -36.5%, 28.62% -30.06%, 4.22% -5.06%, 10.92% -12.16% and 19.00% -20.29%, respectively. Consequently, caloric value was around 450.36 -451.32 kcal 100 g −1 for dried moringa seeds. As confirmed, dried moringa seeds are considered as a rich source of dietary minerals. TPCs content of M. oleifera seed were ranged from 16.9 -18.5 mg GAE g −1 dw. The antioxidants activity was in a range of 0.17 -0.28 μmol TE g −1 dw (DPPH scavenging activity) and was in a range of 4.19 -6.29 μmol TE g −1 dw (DPPH scavenging activity). The chlorophyll a, chlorophyll b, carotenoids, flavonoids and flavonols contents were ranged from 0.93 to 1.78, 4.89 to 8.41, 13.53 to 19.56 mg g −1 dw, 3.30 to 5.40 and 2.30 to 4.10 mg QE g −1 dw, respectively. Obviously, the individual essential amino acids (EAAs) and nonessential amino acids (NEAAs) recorded higher contents when compared to referenced protein. Total AA showed in triple amount in moringa protein when compared FAO standard. The acid value, iodine value, unsaponificable matter, peroxide value, refractive index, saponification value of cold pressed moringa seeds oil found to be 0.29 -0.37 mg·g −1 , 65.7 -67.5, 0.60 to 0.74 g 100 g −1 , 1.67 -2.47 mEq/Kg, 1.4607 -1.4613, 171.7 to 178.3 mg KOH g −1 , respectively. Clearly, the unsaturated fatty acids (USFA) contents of M. oleifera edible oils were 77.14% -84.98%, especially oleic (73.30% -79.58%). On contrary, the saturated fatty acids (SFA) recorded 15.00% -22.83% where palmitic and stearic acids were the predominant SFA. The results of oil physicochemical parameters were compared with those of commercial oils. It could be illustrated that moringa seeds and its oil considered as a good source for dietar

Draft Genome Sequence of Photorhabdus luminescens Strain BA1, an Entomopathogenic Bacterium Isolated from Nematodes Found in Egypt

Photorhabdus luminescens strain BA1 is an entomopathogenic bacterium that forms a symbiotic association with Heterorhabditis nematodes. We report here a 5.0-Mbp draft genome sequence for P. luminscens strain BA1, with a G+C content of 42.46% and 4,250 candidate protein-coding genes

Chemoenzymatic Hydrogen Production from Methanol through the Interplay of Metal Complexes and Biocatalysts

Microbial methylotrophic organisms can serve as great inspiration in the development of biomimetic strategies for the dehydrogenative conversion of C1 molecules under ambient conditions. In this Concept article, a concise personal perspective on the recent advancements in the field of biomimetic catalytic models for methanol and formaldehyde conversion, in the presence and absence of enzymes and co-factors, towards the formation of hydrogen under ambient conditions is given. In particular, formaldehyde dehydrogenase mimics have been introduced in stand-alone C1-interconversion networks. Recently, coupled systems with alcohol oxidase and dehydrogenase enzymes have been also developed for in situ formation and decomposition of formaldehyde and/or reduced/oxidized nicotinamide adenine dinucleotide (NADH/ NAD+). Although C1 molecules are already used in many industries for hydrogen production, these conceptual bioinspired low-temperature energy conversion processes may lead one day to more efficient energy storage systems enabling renewable and sustainable hydrogen generation for hydrogen fuel cells under ambient conditions using C1 molecules as fuels for mobile and miniaturized energy storage solutions in which harsh conditions like those in industrial plants are not applicable.Peer reviewe

Investigation of the bioequivalence of montelukast chewable tablets after a single oral administration using a validated LC-MS/MS method

Background: Montelukast (MT) is a leukotriene D4 antagonist. It is an effective and safe medicine for the prophylaxis and treatment of chronic asthma. It is also used to prevent acute exercise-induced bronchoconstriction and as a symptomatic relief of seasonal allergic rhinitis and perennial allergic rhinitis. Objective: The aim of this study was to evaluate the bioequivalence (BE) of two drug products: generic MT 5 mg chewable tablets versus the branded drug Singulair® pediatric 5 mg chewable tablets among Mediterranean volunteers. Methods: An open-label, randomized two-period crossover BE design was conducted in 32 healthy male volunteers with a 9-day washout period between doses and under fasting conditions. The drug concentrations in plasma were quantified by using a newly developed and fully validated liquid chromatography tandem mass spectrometry method, and the pharmacokinetic parameters were calculated using a non-compartmental model. The ratio for generic/branded tablets using geometric least squares means was calculated for both the MT products. Results: The relationship between concentration and peak area ratio was found to be linear within the range 6.098–365.855 ng/mL. The correlation coefficient (R2) was always greater than 0.99 during the course of the validation. Statistical comparison of the main pharmacokinetic parameters showed no significant difference between the generic and branded products. The point estimates (ratios of geometric means) were 101.2%, 101.6%, and 98.11% for area under the curve (AUC)0→last, AUC0→inf, and Cmax, respectively. The 90% confidence intervals were within the predefined limits of 80.00%–125.00% as specified by the US Food and Drug Administration and European Medicines Agency for BE studies. Conclusion: Broncast® pediatric chewable tablets (5 mg/tablet) are bioequivalent to Singulair® pediatric chewable tablets (5 mg/tablet), with a similar safety profile. This suggests that these two formulations can be considered interchangeable in clinical practice

Preclinical Analysis of JAA-F11, a Specific Anti-Thomsen-Friedenreich Antibody via Immunohistochemistry and In Vivo Imaging.

The tumor specificity of JAA-F11, a novel monoclonal antibody specific for the Thomsen-Friedenreich cancer antigen (TF-Ag-alpha linked), has been comprehensively studied by in vitro immunohistochemical (IHC) staining of human tumor and normal tissue microarrays and in vivo biodistribution and imaging by micro-positron emission tomography imaging in breast and lung tumor models in mice. The IHC analysis detailed herein is the comprehensive biological analysis of the tumor specificity of JAA-F11 antibody performed as JAA-F11 is progressing towards preclinical safety testing and clinical trials. Wide tumor reactivity of JAA-F11, relative to the matched mouse IgG3 (control), was observed in 85% of 1269 cases of breast, lung, prostate, colon, bladder, and ovarian cancer. Staining on tissues from breast cancer cases was similar regardless of hormonal or Her2 status, and this is particularly important in finding a target on the currently untargetable triple-negative breast cancer subtype. Humanization of JAA-F11 was recently carried out as explained in a companion paper "Humanization of JAA-F11, a Highly Specific Anti-Thomsen-Friedenreich Pancarcinoma Antibody and In Vitro Efficacy Analysis" (Neoplasia 19: 716-733, 2017), and it was confirmed that humanization did not affect chemical specificity. IHC studies with humanized JAA-F11 showed similar binding to human breast tumor tissues. In vivo imaging and biodistribution studies in a mouse syngeneic breast cancer model and in a mouse-human xenograft lung cancer model with humanized 124I- JAA-F11 construct confirmed in vitro tumor reactivity and specificity. In conclusion, the tumor reactivity of JAA-F11 supports the continued development of JAA-F11 as a targeted cancer therapeutic for multiple cancers, including those with unmet need

Draft Genome Sequence of Photorhabdus temperata Strain Meg1, an Entomopathogenic Bacterium Isolated from Heterorhabditis megidis Nematodes

Photorhabdus temperata strain Meg1 is an entomopathogenic bacterium that forms a symbiotic association with Heterorhabditis nematodes. We report here a 4.9-Mbp draft genome sequence for P. temperata strain Meg1, with a G+C content of 43.18% and containing 4,340 candidate protein-coding genes

The effect of extra dimensions on gravity wave bursts from cosmic string cusps

We explore the kinematical effect of having extra dimensions on the gravity wave emission from cosmic strings. Additional dimensions both round off cusps, and reduce the probability of their formation. We recompute the gravity wave burst, taking into account these two factors, and find a potentially significant damping on the gravity waves of the strings.Comment: 33 pages, 8 figures, published versio

Horizon-preserving dualities and perturbations in non-canonical scalar field cosmologies

We generalize the cosmological duality between inflation and cyclic contraction under the interchange $a \leftrightarrow H$ to the case of non-canonical scalar field theories with varying speed of sound. The single duality in the canonical case generalizes to a family of three dualities constructed to leave the cosmological acoustic horizon invariant. We find three classes of models: (I) DBI inflation, (II) the non-canonical generalization of cyclic contraction, and (III) a new cosmological solution with rapidly decreasing speed of sound and relatively slowly growing scale factor, which we dub {\it stalled} cosmology. We construct dual analogs to the inflationary slow roll approximation, and solve for the curvature perturbation in all three cases. Both cyclic contraction and stalled cosmology predict a strongly blue spectrum for the curvature perturbations inconsistent with observations.Comment: 36 pages, LaTeX (v2: references added, version submitted to JCAP