Amino­guanidinium hydrogen fumarate

The title compound, CH7N4 +·C4H3O4 −, is a molecular salt in which the amino­guanidinium cations and fumarate monoanions are close to planar, with maximum deviations of 0.011 (1) and 0.177 (1) Å, respectively. The crystal packing is stabilized by inter­molecular N—H⋯O and O—H⋯O hydrogen bonds

Cross Type Neutralizing Antibodies Detected in a Unique HIV-2 Infected Individual From India

Background: Infection with HIV-2, a retrovirus that is closely related to HIV-1, is characterized by slower disease progression and transmission, longer latency period and low or undetectable viremia. Host immunity, including production of potent neutralizing antibodies, may be one of the possible contributors to the distinction between the two infections. In an attempt to understand whether HIV-2 infection results in production of neutralizing antibodies and to characterize the nature of the neutralization response we screened plasma of 37 HIV-2 infected individuals for the presence of broadly neutralizing antibodies.Materials and Methods: Thirty seven asymptomatic, ART-naïve, HIV-2 infected individuals were recruited for the study. Plasma obtained from these individuals were screened for the presence of broadly cross reactive neutralizing antibodies (BCNabs) using the standard neutralization screening protocol with a panel of HIV-1 and HIV-2 pseudoviruses. Plasma exhibiting broad neutralization activity were assessed for their potency employing a titration assay. Further, an attempt was made to characterize the neutralization specificity of the plasma exhibiting broad and potent neutralization activity.Result: While majority of the samples tested were capable of neutralizing HIV-2 pseudoviruses with high to moderate potency, one unique sample demonstrated broad cross clade and cross type neutralization with ability to strongly neutralize the vast majority of both HIV-1 and HIV-2 viruses tested (19/20). Preliminary analyses indicate the possible presence of antibodies with multiple glycan epitope binding specificities.Conclusion: The study identified a unique HIV-2 sample with exceptional ability to neutralize HIV-2 viruses and cross-neutralize HIV-1 viruses with great breadth and potency. This sample holds promise for isolation of novel monoclonal antibodies that may exploited as potential therapeutic tools for HIV infection

Structural diversity in organotin compounds derived from bulky monoaryl phosphates: dimeric, tetrameric, and polymeric tin phosphate complexes

Monoaryl phosphates with a bulky aryl substituent have been used to synthesize new organotin clusters and polymers. The equimolar reaction between 2,6-diisopropylphenylphosphate (dipp-H2) and Me2SnCl2 in ethanol at 25 °C leads to the formation of [Me2Sn(μ3-dipp)]n (1), while the reaction of 2,6-dimethylphenylphosphate (dmpp-H2) with Me2SnCl2 in either a 1:1 or 2:1 molar ratio proceeds to produce exclusively [Me2Sn(μ-dmpp-H)2]n.nH2O (2). Compounds 1 and 2 are 1D polymers with different architectures. In compound 1, the tin atom is five-coordinate (trigonal bipyramidal). Each dipp ligand bridges three different tin atoms to form an infinite ladder-chain structure. In 2, each six-coordinate (octahedral) tin atom is surrounded by four phosphate oxygen atoms originating from four different bridging dmpp-H ligands, thus forming a spirocyclic coordination polymeric chain. The use of nBu2SnO as the diorganotin source in its reaction with dipp-H2 leads to the isolation of dimeric [nBu2Sn(μ-dipp-H)(dipp-H)]2 (4), which contains a central Sn2O4P2 unit. There are two chemically different half molecules of 4 in the asymmetric part of the unit cell and hence it actually exists as a 1:1 mixture of [nBu2Sn(μ-dipp-H)(dipp-H)]2 and [nBu2Sn(μ-dipp)(dipp-H2)]2 in the solid state. The reaction of the monoorgano tin precursor nBuSn(O)(OH)·xH2O with dipp-H2 takes place in acetone at room temperature to yield the tetrameric cluster 5, which has different structures in the solution and in the solid state. 31P NMR spectroscopy clearly suggests that 5 has the formula [nBu4Sn4(μ-O)2((μ-dipp-H)8] in solution. The single-crystal X-ray diffraction studies in the solid state, however, reveal that compound 5 exists as [nBu4Sn4(μ-OH)2(μ-dipp-H)6(μ-dipp)2]. The use of compounds 1-4 as possible precursors for the preparation of ceramic tin phosphate materials has been investigated. The thermolysis of 1 at 500 °C leads to the formation of quantitative amounts of Sn2P2O7, while the thermolysis of 2, 3, and 4 under similar conditions results in the formation of SnP2O7

The effect of methane addition on reacting hydrogen jets in crossflow

The combustion characteristics in a jet in crossflow configuration are numerically investigated using Large Eddy Simulation (LES) with subgrid scale modelling for partially premixed combustion. The time-averaged statistics are compared with the experimental measurements. Both the temperature and velocity comparisons show good agreements with measurements. The distribution of reaction regions of nitrogen-diluted hydrogen fuel jet is then examined in both physical and mixture fraction space. The results demonstrate that the fuel consumption in potential core, near-field and far-field regions occurs at various mixture fraction ranges. In the potential core region, reactions predominantly occur between the lean and stoichiometric mixture fraction range. This range broadens to include fuel-rich conditions in the near-field region and narrows again to fuel-lean combustion in the far-field region. With these changes in the mixture fraction range, the fractional contribution from different combustion modes also changes. A closer study of these changes reveals that the fractional contribution from the non-premixed mode is highest at the end of the potential core region. The dependency of these combustion modes on the fuel composition is studied by increasing the volume fraction of methane in the jet. This resulted in altered chemical kinetics and thereby increased the fractional contribution of the non-premixed mode, particularly in the potential core region.1. Mitsubishi Heavy Industries, Ltd., Takasago, Japan. 2. ARCHER2 UK National Supercomputing Service - Pioneer Project (e808). 3. EPSRC Tier2 National HPC service, CSD3

First organotin complex of a phosphonic diamide RP(O)(NHR)<SUB>2</SUB>

Diorganotin dichloride-phosphonic diamide complex, [Ph<SUB>2</SUB>SnCl<SUB>2</SUB>(tBuP(O)(NH<SUP>i</SUP>Pr)<SUB>2</SUB>)<SUB>2</SUB>] (1), is prepared by the addition of two equivalents of<SUP> t</SUP>BuP(O)(NH<SUP>i</SUP>Pr)<SUB>2</SUB> to one equivalents of Ph<SUB>2</SUB>SnCl<SUB>2</SUB> either in the presence or absence of triethylamine. Compound 1 is a rare example of an all-trans SnA<SUB>2</SUB>B<SUB>2</SUB>C<SUB>2</SUB> complex that contains H-bonded six-membered rings which are made up of six different main group elements

Favipiravir: insight into the crystal structure, Hirshfeld surface analysis and computational study

In this work we report structural and computational studies of favipiravir, which is now used as a drug for COVID-19 treatment. The molecule is completely flat and stabilized by an intramolecular O–H···O hydrogen bond, yielding a six-membered pseudo-aromatic ring. The aromaticity index of this pseudo-aromatic ring was found to be 0.748, while the same indix for the pyrazine ring in favipiravir was found to be 0.954. The crystal packing of favipiravir is mainly constructed through intermolecular N–H···O, N–H···N and C–H···O hydrogen bonds, yielding a 3D supramolecular framework with a zst topology defined by the point symbol of (65·8). The crystal structure of favipiravir is further stabilized by weak C–F···F–C intermolecular type II dihalogen interactions, yielding a 1D supramolecular polymeric chain. More than 80% of the total Hirshfeld surface area for favipiravir is occupied by H···H/C/N/O/F and C···N/O contacts. Energy frameworks have been calculated to additionally analyze the overall crystal packing. It was established that the structure of favipiravir is mainly characterized by the dispersion energy framework followed by the less significant electrostatic energy framework contribution. Finally, by using density functional theory (DFT) calculations and the quantum theory of atoms in molecules, we have assigned the interaction energy of each hydrogen bond, which can be helpful to develop scoring functions to be used in force fields/docking calculations

Structural Diversity in Zinc Phosphates and Phosphinates: Observation of a Lattice Water Dimer Sandwiched Between Phosphoryl Oxygen Atoms

Reactions of zinc acetate dihydrate with organic phosphates $[(RO)_2P(O)(OH)]$ (R = tBu, Ph) and phosphinic acids [PhR'P(O)(OH)] (R' = Ph, H) have been investigated in the presence of 1,10-phenanthroline (phen). While the use of ditert-butyl phosphate (dtbp-H) results in the formation of $[Zn(phen)_2(dtbp)(OH_2)][dtbp](MeOH)(MeCOOH)(H_2O)_3$ (1), the change of phosphorus source to diphenylphosphate (dpp-H) yields an interesting phosphate-bridged dinuclear complex $[{Zn(phen)(dpp)}_2{\mu_2-dpp}_2]$ (2). Mononuclear complexes $[Zn(phen)_2(dppi)_2](H_2O)_2$ (3) and $[Zn(phen)_2(ppi)_2]-(H_2O)$ (4) have been obtained from similar reactions by the use of diphenylphosphinic acid (dppi-H) and phenylphosphinic acid (ppi-H), respectively. The high steric bulk of the dtbp ligand results in the formation of the cationic complex 1, where only one of the dtbp ligands is directly coordinated to the metal atom, leaving the second dtbp molecule as the counter anion. The inorganic core of dinuclear zinc phosphate 2 resembles the single four-ring (S4R) secondary building unit of framework zinc phosphates. Compounds 3 and 4 are neutral monomeric hexacoordinate complexes with two chelating 1,10-phen ligands and two monodentate phosphinate ligands. The two lattice water molecules in 3 form an interesting water dimer $(H_2O)_2$. These water dimers link the mononuclear zinc complexes in the lattice to form an Hbonded one-dimensional polymer. Similarly, the lattice water present in 4 serves to link the zinc phenylphosphinate molecules through hydrogen bonding in the form of a 1-D polymer. The reaction of the precursor complex $[Zn(bpy)_2(OAc)]-(ClO_4).H_2O$ with dpp-H, dppi-H, and ppi-H in methanol leads to the formation of zinc phosphate $[Zn(bpy)_2(dpp)]_2-(ClO_4)_2.H_2O$ (5) and phosphinates $[Zn(bpy)_2(dppi)]_2(ClO_4)_2$ (6) and $[Zn(bpy)_2(ppi)]_2(ClO_4)_2$ (7), respectively. The molecular structures of 1–5 and 7 have been determined by singlecrystal X-ray diffraction studies

Elevated Numbers of HIV-Specific Poly-Functional CD8+ T Cells With Stem Cell-Like and Follicular Homing Phenotypes in HIV-Exposed Seronegative Individuals.

HIV-specific CD8+ T cells are known to play a key role in viral control during acute and chronic HIV infection. Although many studies have demonstrated the importance of HIV-specific CD8+ T cells in viral control, its correlation with protection against HIV infection remains incompletely understood. To better understand the nature of the immune response that contributes to the early control of HIV infection, we analyzed the phenotype, distribution and function of anti-viral CD8+ T cells in a cohort of HIV-exposed seronegative (HESN) women, and compared them with healthy controls and HIV-infected individuals. Further, we evaluated the in vitro viral inhibition activity of CD8+ T cells against diverse HIV-1 strains. We found that the HESN group had significantly higher levels of CD8+ T cells that express T-stem cell-like (TSCM) and follicular homing (CXCR5+) phenotype with more effector like characteristics as compared to healthy controls. Further, we observed that the HESN population had a higher frequency of HIV-specific poly-functional CD8+ T cells with robust in vitro virus inhibiting capacity against different clades of HIV. Overall, our results demonstrate that the HESN population has elevated levels of HIV-specific poly-functional CD8+ T cells with robust virus inhibiting ability and express elevated levels of markers pertaining to TSCM and follicular homing phenotype. These results demonstrate that future vaccine and therapeutic strategies should focus on eliciting these critical CD8+ T cell subsets