Is the largest aqueous gold cluster a superatom complex? Electronic structure & optical response of the structurally determined Au146(pMBA)57

The new water-soluble gold cluster Au146(pMBA)57, the structure of which has been recently determined at sub-atomic resolution by Vergara et al. [1], is the largest aqueous gold cluster ever structurally determined and likewise the smallest cluster with a stacking fault. The core presents a twinned truncated octahedron, while additional peripheral gold atoms follow a C2 rotational symmetry. According to the usual counting rules of the superatom complex (SAC) model, the compound attains a number of 92 SAC electrons if the overall net charge is 3- (three additional electrons). As this is the number of electrons required for a major shell closing, the question arises if Au146(pMBA)57 should be regarded as a superatom complex. Starting from the experimental coordinates we have analyzed the structure using density-functional theory. The optimized (relaxed) structure retains all the connectivity of the experimental coordinates, while removing much of its irregularities in interatomic distances, thereby enhancing the C2-symmetry feature. Analyzing the angular-momentum projected states, we show that, despite a small gap, the electronic structure does not exhibit SAC model character. In addition, optical absorption spectra are found to be relatively smooth compared to the example of the Au144(SR)60 cluster. The Au146(SR)57 cluster does not derive its stability from SAC character; it cannot be considered a superatom complex

Isolation and Identification of an Antimutagenic Phthalate Derivative Compound from Octopus (Paraoctopus limaculatus)

Purpose: To isolate and evaluate the antimutagenic properties of compounds previously identified in octopus (Paraoctopus limaculatus).Methods: Octopus fractions, previously obtained by a sequential thin layer chromatography (TLC) procedure, were subjected to further fractionation by TLC and their anti-mutagenic activity monitored using Salmonella tester strains TA98 and TA100 with metabolic activation (S9) in Ames test. The isolated fractions were subjected to structural studies by Fourier transformed infrared spectroscopy (FTIR), nuclear magnetic resonance (1H and 13C NMR), and gas chromatography-mass spectrometry.Results: Five new fractions were obtained from a previously isolated and reported anti-mutagenic octopus fraction. Fractions RB21321b2 and RB21321b3 inhibited > 80 % of the mutagenicity induced by 500 ng AFB1 on both tester strains and were selected for chemical/structural characterization. Data from IR and 1H and 13C NMR suggested the presence of phthalate type of compounds. GC-MS analysis revealed 278 m/z for both fractions which is consistent with a butyl isobutyl phthalate structure.Conclusion: Based on the findings, the compound responsible for the high anti-mutagenic activity of the isolated fraction from octopus is 1-butyl-2-isobutyl-phthalate.Keywords: Octopus, Anti-Mutagenic, Paraoctopus limaculatus, 1-Butyl-2-isobutyl-phthalat

An efficient triose phosphate synthesis and distribution in wheat provides tolerance to higher field temperature

High temperatures in the field hinder bread wheat high yield production, mainly because of the adverse effects of heat over photosynthesis. The Yaqui Valley, the main wheat producer region in Mexico, is a zone prone to have temperatures over 30 °C. The aim of this work was to test the flag leaf photosynthetic performance in ten bread wheat genotypes grown under high temperatures in the field. The study took place during two seasons (2019-2020 and 2020-2021). In each season, control seeds were sown in December, while heat-stressed were sown in late January to subject wheat to heat stress (HS) during the grain filling stage. HS reduced Grain yield from 20 to 58 % in the first season. HS did not reduce chlorophyll content and light-dependent reactions were unaffected in any of the tested genotypes. Rubisco, chloroplast fructose 1,6-biphosphatase (FBPase), and sucrose phosphate synthase (SPS) activities were measured spectrophotometrically. Rubisco activity did not decrease under HS in any of the genotypes. FBPase activity was reduced by HS indicating that triose phosphate flux to starch synthesis was reduced, while SPS was not affected, and thus, sucrose synthesis was maintained. HS reduced aerial biomass in the ten chosen genotypes. Genotypes SOKWB.1, SOKWB.3, and BORLAUG100 maintained their yield under HS, pointing to a potential success in their introduction in this region for breeding heat-tolerant bread wheat

The Meteorite Fall in Carancas, Lake Titicaca Region, Southern Peru: First Results

The meteorite fall that occurred on September 15, 2007, in the Carancas community is a rare case where it is possible to study both impact phenomenology and meteorite characteristics, including accurate time framework

Etiological identification of viral agents in acute encephalitis in Guadalajara, México, 2011-2015

Introduction: Viral encephalitis is a well-known inflammatory process associated with neurological dysfunction that might derive into severe brain damage or a fatal outcome. In México there is no epidemiological data that describes the prevalence of viral agents responsible for acute encephalitis. Objective: To identify the main viral agents by real time PCR involved in acute encephalitis in Mexico. Materials and methods: We obtained cerebral spinal fluid (CSF) samples from all patients with suspected viral encephalitis admitted to the emergency service of the Hospital Civil de Guadalajara “Fray Antonio Alcalde”. To identify pathogens, we performed nucleic acid extraction using real-time PCR and RT-PCR. Results: Sixty-six patients were diagnosed with acute encephalitis from 2011 to 2014. A definitive viral etiological diagnosis was established in 16 patients (24%); the main causative agents were enteroviruses in 50% of the 16 positive samples, followed by herpes simplex virus (37%) and cytomegaloviruses (12.5%). Patients with encephalitis were predominantly male (63.3%) and a seasonal predominance was observed during autumn (37.5%). The main clinical characteristics in the acute encephalitis phase were fever (48.45) and cephalea (36.3), followed by seizures, disorientation, and muscular weakness (30.3%). Kerning sign was present in two cases (3%) and other two cases presented Brudzinski’s sign (3%). Conclusions: CSF PCR is a suitable diagnostic technique for the identification of viral encephalitis caused by viral infections that allows an appropriate antiviral therapeutic treatment

Hidden components in aqueous "Gold-144' fractionated by PAGE: high resolution orbitrap ESI-MS identifies the Gold-102 and higher all-aromatic Au-pMBA cluster compounds

Accepted author manuscriptExperimental and theoretical evidence reveals the resilience and stability of the larger aqueous gold clusters protected with p-mercaptobenzoic acid ligands (pMBA) of composition Aun(pMBA)p or (n, p). The Au144(pMBA)60, (144, 60), or gold-144 aqueous gold cluster is considered special because of its high symmetry, abundance, and icosahedral structure as well as its many potential uses in material and biological sciences. Yet, to this date, direct confirmation of its precise composition and total structure remains elusive. Results presented here from characterization via high-resolution electrospray ionization mass spectrometry on an Orbitrap instrument confirm Au102(pMBA)44 at isotopic resolution. Further, what usually appears as a single band for (144, 60) in electrophoresis (PAGE) is shown to also contain the (130, 50), recently determined to have a truncated-decahedral structure, and a (137, 56) component in addition to the dominant (144, 60) compound of chiral-icosahedral structure. This finding is significant in that it reveals the existence of structures never before observed in all-aromatic water-soluble species while pointing out the path toward elucidation of the thermodynamic control of protected gold nanocrystal formation.Ye

Analytical Modeling for the Bending Resonant Frequency of Multilayered Microresonators with Variable Cross-Section

Multilayered microresonators commonly use sensitive coating or piezoelectric layers for detection of mass and gas. Most of these microresonators have a variable cross-section that complicates the prediction of their fundamental resonant frequency (generally of the bending mode) through conventional analytical models. In this paper, we present an analytical model to estimate the first resonant frequency and deflection curve of single-clamped multilayered microresonators with variable cross-section. The analytical model is obtained using the Rayleigh and Macaulay methods, as well as the Euler-Bernoulli beam theory. Our model is applied to two multilayered microresonators with piezoelectric excitation reported in the literature. Both microresonators are composed by layers of seven different materials. The results of our analytical model agree very well with those obtained from finite element models (FEMs) and experimental data. Our analytical model can be used to determine the suitable dimensions of the microresonator’s layers in order to obtain a microresonator that operates at a resonant frequency necessary for a particular application

Handmade fish meal as a partial replacement of soybean meal in diets for feedlot lambs: Effects on growth performance, dietary energy and meat quality

With the aim to evaluate a handmade fishmeal (HFM) as a partial replacement of soybean meal (SBM) in finishing diets, 36 intact male Dorper × Pelibuey lambs (41.43±7.38 kg of initial weight) were used in a completely randomized block design to test the following treatments: 1) Cracked corn-based diet containing 12% SBM, 2) inclusion of 3.5% of HFM partially replacing SBM, and 3) inclusion of 7% of HFM partially replacing SBM. Urea and limestone were utilized to balance diets in CP and calcium content. The feeding trial lasted 30 days. Replacement of SBM with HFM did not modify the effects on average daily gain (ADG) and dry matter intake (DMI), but there were numerical differences in ADG; HFM inclusion linearly improved gain-to-feed ratio; dietary net energy (NE) and observed-to-expected diet NE. Hot carcass weight and dressing percentage were not affected by HFM. Except a linear increase on C22:6, the effect of SBM replacement on fatty acid profile in meat was not significant. The meat pH registered at 24 h post-mortem linearly increased with HFM inclusion, but meat colour and sensorial values were unaffected. It was concluded that inclusion of up to 7% of HFM in diet as partial replacement of soybean meal did not negatively affect DMI and ADG, but can increase feed efficiency and dietary energy utilization. The effects of HFM on carcass and meat quality were inappreciable. Due to variations in handmade processing, it is important to verify its chemical composition before HFM can be incorporated into diets