Highly efficient cis-1,4 polymerisation of isoprene using simple homoleptic amido rare earth-based catalysts

Polymerisation of isoprene was performed by means of ternary catalytic systems made of Ln[N(SiMe₃)₂]₃ (Ln = Nd (1), Y (2))/borate/Al(ⁱBu)₃ combinations (borate = [HNMe₂Ph][B(C₆F₅)₄] (HNB), [CPh₃][B(C₆F₅)₄] (TB) or B(C₆F₅)₃ (Barf)). With borate activator B(C₆F₅)₃, highly active (up to 4700 kg mol⁻¹h⁻¹) and selective catalysts are obtained with both neodymium and yttrium metals, leading up to 96% cis-1,4-polyisoprene.     

Optical,FTIR and DC Conductivity of Soda Lime Silicate Glass Containing Cement Dust and Transition Metal Ions

Four soda lime silicate glass samples of composition (70 % SiO₂+ 20 % Na₂O+ 10 % CaO mol %) were prepared after adding 5 wt% cement dust to each sample mixture besides 0.1 wt% of one transition metal (TM) oxide of Fe, Co or Cu. The four samples were melted by a conventional melt-annealing technique at 1400 ^°C for 2.5 h. Density, UV/VIS, FTIR and DC conductivity measurements were performed for each glass. Experimental results indicate that there are only slight differences in the density values. The optical spectra reveal that the TM free sample and the sample containing iron ions have the same spectral features while the samples containing copper or cobalt exhibit distinct characteristic absorption bands due to each TM ion. FTIR spectra reveal characteristic vibrational bands due to stretching and bending modes of the silicate network. DC conductivity data show variations in the values of the studied samples according to the type of TM ions added. All the experimental results were correlated with each other in accordance with the current views on the constitution of the studied glasses.     

New biobased carboxylic acid hardeners for epoxy resins

Soybean oil was modified into a novel biobased polyacid hardener by thiol‐ene coupling with thioglycolic acid. The structure of the initial soybean oil and polyacid triglyceride was carefully analyzed using ¹H NMR and titration. The thermal crosslinking reaction between acid hardener and epoxidized resin was studied by differential scanning calorimetry (DSC) and rheology. Then, the synthesized biobased acid hardener was employed as a novel curing agent for bisphenol A diglycidyl ether to elaborate new partially biobased materials. These materials, formulated in stoichiometry ratio, were characterized by DSC, thermogravimetry analyses, dynamic mechanical analyses and exhibit interesting properties for coatings. Practical applications: The products of the chemistry described in this contribution, i.e., polyacid from soybean oil and thioglycolic acid, provide biobased building blocks for further epoxy resin syntheses by reaction with epoxy groups. The obtained epoxy resins are partially biobased and may be applied as binders and coatings.     

Integrated synthetic, pharmacological, and computational investigation of cis-2-(3,5-dichlorophenylcarbamoyl)cyclohexanecarboxylic acid enantiomers as positive allosteric modulators of metabotropic glutamate receptor subtype 4

2‐(3,5‐Dichlorophenylcarbamoyl)cyclohexanecarboxylic acid ( 1 ) is a potent and selective positive allosteric modulator of metabotropic glutamate receptor subtype 4 (mGluR4). The activity of 1 was reported to reside in the cis diastereomer with equal potency between its enantiomeric forms (Niswender et al., Mol. Pharmacol. 2008 , 74, 1345–1358). In the present study, the asymmetric synthesis of each of the cis enantiomers was performed, and their activities were compared with that of the racemic trans. In our assays, the cis enantiomers differ in potency, with one of them (1R,2S) higher and the other (1S,2R) lower than the racemic trans. High‐level quantum chemical calculations were carried out to characterize the structures of minimum energy in all‐isomer conformational space as well as particular intermediates between conformational transitions. Computational analysis identified structural features of 1 that can play a role in mGluR4 functionality and establish the basis for subsequent work, in which molecular chirality constructed on conformations derived from those found for the active (1R,2S) enantiomer can provide new ideas for drug discovery. Comparison between experimental and theoretical circular dichroism spectra confirmed both the absolute configuration of the (1R,2S) compound and its calculated most stable conformation, thereby supporting experimental and theoretical work.     

Argon Attenuates Multiorgan Failure in Relation with HMGB1 Inhibition

Argon inhalation attenuates multiorgan failure (MOF) after experimental ischemic injury. We hypothesized that this protection could involve decreased High Mobility Group Box 1 (HMGB1) systemic release. We investigated this issue in an animal model of MOF induced by aortic cross-clamping. Anesthetized rabbits were submitted to supra-coeliac aortic cross-clamping for 30 min, followed by 300 min of reperfusion. They were randomly divided into three groups (n = 7/group). The Control group inhaled nitrogen (70%) and oxygen (30%). The Argon group was exposed to a mixture of argon (70%) and oxygen (30%). The last group inhaled nitrogen/oxygen (70/30%) with an administration of the HMGB1 inhibitor glycyrrhizin (4 mg/kg i.v.) 5 min before aortic unclamping. At the end of follow-up, cardiac output was significantly higher in Argon and Glycyrrhizin vs. Control (60 ± 4 and 49 ± 4 vs. 33 ± 8 mL/kg/min, respectively). Metabolic acidosis was attenuated in Argon and Glycyrrhizin vs. Control, along with reduced amount of norepinephrine to reverse arterial hypotension. This was associated with reduced interleukin-6 and HMGB1 plasma concentration in Argon and Glycyrrhizin vs. Control. End-organ damages were also attenuated in the liver and kidney in Argon and Glycyrrhizin vs. Control, respectively. Argon inhalation reduced HMGB1 blood level after experimental aortic cross-clamping and provided similar benefits to direct HMGB1 inhibition.     

Phosphorylation of Native Porcine Olfactory Binding Proteins

The identification of various isoforms of olfactory binding proteins is of major importance to elucidate their involvement in detection of pheromones and other odors. Here, we report the characterization of the phosphorylation of OBP (odorant binding protein) and Von Ebner’s gland protein (VEG) from the pig, Sus scrofa. After labeling with specific antibodies raised against the three types of phosphorylation (Ser, Thr, Tyr), the phosphate-modified residues were mapped by using the beta-elimination followed by Michael addition of dithiothreitol (BEMAD) method. Eleven phosphorylation sites were localized in the pOBP sequence and nine sites in the VEG sequence. OBPs are secreted by Bowman’s gland cells in the extracellular mucus lining the nasal cavity. After tracking the secretion pathway in the rough endoplasmic reticulum of these cells, we hypothesize that these proteins may be phosphorylated by ectokinases that remain to be characterized. The existence of such a regulatory mechanism theoretically increases the number of OBP variants, and it suggests a more specific role for OBPs in odorant coding than the one of odorant solubilizer and transporter. Electronic supplementary material  The online version of this article (doi:) contains supplementary material, which is available to authorized users. Chrystelle Le Danvic and Fanny Brimau contributed equally to the work.     

Distribution of KIR Genes and Their HLA Ligands in Different Viral Infectious Diseases: Frequency Study in Sicilian Population

Natural killer (NK) cells play a role in defence against viral infections by killing infected cells or by producing cytokines and interacting with adaptive immune cells. Killer immunoglobulin-like receptors (KIRs) regulate the activation of NK cells through their interaction with human leucocyte antigens (HLA). Ninety-six Sicilian patients positive to Human Immunodeficiency Virus-1 (HIV) and ninety-two Sicilian patients positive to SARS-CoV-2 were genotyped for KIRs and their HLA ligands. We also included fifty-six Sicilian patients with chronic hepatitis B (CHB) already recruited in our previous study. The aim of this study was to compare the distribution of KIR–HLA genes/groups of these three different infected populations with healthy Sicilian donors from the literature. We showed that the inhibitory KIR3DL1 gene and the KIR3DL1/HLA-B Bw4 pairing were more prevalent in individual CHB. At the same time, the frequency of HLA-C2 was increased in CHB compared to other groups. In contrast, the HLA-C1 ligand seems to have no contribution to CHB progression whereas it was significantly higher in COVID-19 and HIV-positive than healthy controls. These results suggest that specific KIR–HLA combinations can predict the outcome/susceptibility of these viral infections and allows to plan successful customized therapeutic strategies.     

A meta-analytical structural equations analysis of a model of employee turnover.

Combined meta-analysis with structural equations modeling (SEM) to validate the W. H. Mobley et al (1978) turnover theory as well as alternative structural networks proposed by A. Dalessio et al (1986), P. W. Hom et al (1984), and B. D. Bannister and R. W. Griffeth (1986). The authors aggregated correlations from 17 studies (N?=?5,013 employees), correcting for unreliability and sampling error. Then they used SEM to assess the models, comparing their relative fits to data. SEM analyses corroborated the Mobley et al model better than did past research, but these analyses also showed that the Dalessio et al and the Hom et al theories explained sample data more plausibly. Additional SEM tests found that turnover base rates, time lags between turnover and model assessments, unemployment rates, and occupational differences moderated the models' pathways. The present findings suggest various implications for these theories and for turnover research. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

High-Temperature Creep Degradation of the AM1/NiAlPt/EBPVD YSZ System

The failure mechanisms of a NiAlPt/electron beam physical vapor deposition yttria-stabilized-zirconia thermal barrier coating system deposited on the AM1 single crystalline substrate have been investigated under pure creep conditions in the temperature range from 1273 K to 1373 K (1000 °C to 1100 °C) and for durations up to 1000 hours. Doubly tapered specimens were used allowing for the analysis of different stress states and different accumulated viscoplastic strains for a given creep condition. Under such experiments, two kinds of damage mechanisms were observed. Under low applied stress conditions (i.e., long creep tests), microcracking is localized in the vicinity of the thermally grown oxide (TGO). Under high applied stress conditions, an unconventional failure mechanism at the substrate/bond coat interface is observed because of large creep strains and fast creep deformation, hence leading to a limited TGO growth. This unconventional failure mechanism is observed although the interfacial bond coat/top coat TGO thickening is accelerated by the mechanical applied stress beyond a given stress threshold.