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The viscous sintering kinetics of thermoplastic polymers is generally studied by monitoring the evolution of the bonding neck between two particles (spherical, or cylindrical) and using a refined Frenkel-Eshelby’s model. Recently, we showed that the entire contour of sintering filaments could be modelled by lemniscates as figure-eight shape curves to assess bonding abilities of a 3D-printable plasticized biopolymer. Using COMSOL Multiphysics® software, we set up a 2D finite element model of thermoplastic filaments’ viscous sintering with flow front tracking by the level set method. This leads to contrasted images of the two phases, i.e. air and polymer, allowing the prediction of the shape of the interface corresponding to the filaments’ contour. An image analysis procedure is applied to the simulated sequences and the ones acquired during sintering trials of extruded filaments based on zein, a corn protein plasticized by 20w% glycerol. This method is based on the assessment of the coordinates of sintered filaments’ edge pixels and their fitting by lemniscates of Booth. We show that the 2D FEM approach combined with level set method allows simulating the hot melt viscous sintering of a 3D-printable thermoplastic biopolymer as a two-phase flow. Furthermore, the image analysis is successfully applied to simulated and experimental sequences, thanks to the monitoring of the filaments’ contour, to assess their bonding kinetics and check its modelling.

The 'switch-off' hypothesis to explain β-cell regulation of α-cell function during hypoglycemia has not been assessed previously in isolated islets, largely because they characteristically do not respond to glucose deprivation by secreting glucagon. We examined this hypothesis using normal human and Wistar rat islets, as well as islets from streptozotocin (STZ)-administered β-cell-deficient Wistar rats. As expected, islets perifused with glucose and 3-isobutryl-1-methylxanthine did not respond to glucose deprivation by increasing glucagon secretion. However, if normal rat islets were first perifused with 16.7 mmol/l glucose to increase endogenous insulin secretion, followed by discontinuation of the glucose perifusate, a glucagon response to glucose deprivation was observed (peak change within 10 rain after switch off = 61 ± 15 pg/ml [mean ± SE], n = 6, P < 0.01). A glucagon response from normal human islets using the same experimental design was also observed. A glucagon response (peak change within 7 min after switch off = 31 ± 1 pg/ml, n = 3, P < 0.01) was observed from β-cell-depleted, STZ-induced diabetic rats whose islets still secreted small amounts of insulin. However, when these islets were first perifused with both exogenous insulin and 16.7 mmol/l glucose, followed by switching off both the insulin and glucose perifusate, a significantly larger (P < 0.05) glucagon response was observed (peak change within 7 min after switch off = 71 ± 11 pg/ml, n = 4, P < 0.01). This response was not observed if the insulin perifusion was not switched off when the islets were deprived of glucose or when insulin was switched off without glucose deprivation. These data uniquely demonstrate that both normal, isolated islets and islets from STZ-administered rats can respond to glucose deprivation by releasing glucagon if they are first provided with increased endogenous or exogenous insulin. These results fully support the β-cell switch-off hypothesis as a key mechanism for the s-cell response to hypoglycemia. Diabetes 53:1488-1495, 2004, Glucagon during hypoglycemia secretion stimulates glycogenolysis, thereby restoring normoglycemia. Loss of the glucagon response to hypoglycemia is an important problem for patients with type 1 diabetes and for patients with [...]

The glucagon response is the first line of defense against hypoglycemia and is lost in insulin-dependent diabetes. The β-cell 'switch-off' hypothesis proposes that a sudden cessation of insulin secretion from β-cells into the portal circulation of the islet during hypoglycemia is a necessary signal for the glucagon response from downstream α-cells. Although indirect evidence exists to support this hypothesis, it has not been directly tested in vivo by provision and then discontinuation of regional reinsulinization of α-cells at the time of a hypoglycemic challenge. We studied streptozotocin (STZ)-induced diabetic Wistar rats that had no glucagon response to a hypoglycemic challenge. We reestablished insulin regulation of the α-cell by regionally infusing insulin (0.025 µU/min) directly into the superior pancreaticoduodenal artery (SPDa) of STZ-administered rats at an infusion rate that did not alter systemic venous glucose levels. SPDa insulin infusion was switched off simultaneously when blood glucose fell to, Glucagon is the key hormone released in response to hypoglycemia (1-4). It counterregulates the fall in blood glucose through stimulation of hepatic glycogenolysis (5,6). People with type 1 diabetes lose [...]

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The article discusses the impact of the Covid-19 pandemic on the color cosmetics industry, and the launch of vegan products for diverse people. Topics include the rise in sales of eye beauty and care products such as mascara, eyeliners and color palettes; and the creation of sustainable cosmetics to influence target groups.

Dissimilatory iron-reducing bacteria (DIRB) oxidize organic matter or hydrogen and reduce ferric iron to form Fe(II)-bearing minerals, such as magnetite and siderite. However, compared with magnetite, which was extensively studied, the mineralization process and mechanisms of siderite remain unclear. Here, with the combination of advanced electron microscopy and synchrotron-based scanning transmission X-ray microscopy (STXM) approaches, we studied in detail the morphological, structural, and chemical features of biogenic siderite via a growth experiment with Shewanella oneidensisMR-4. Results showed that along with the growth of cells, Fe(II) ions were increasingly released into solution and reacted with CO32–to form micrometer-sized siderite minerals with spindle, rod, peanut, dumbbell, and sphere shapes. They are composed of many single-crystal siderite plates that are fanned out from the center of the particles. Additionally, STXM revealed Fh and organic molecules inside siderite. This suggests that the siderite crystals might assemble around a Fh-organic molecule core and then continue to grow radially. This study illustrates the biomineralization and assembly of siderite by a successive multistep growth process induced by DIRB, also provides evidences that the distinctive shapes and the presence of organic molecules inside might be morphological and chemical features for biogenic siderite.

Zein, a biopolymer from corn, was plasticized by glycerol and an Active Pharmaceutical Ingredient-Ionic Liquid (API-IL) for its melt processing at 130 °C. In order to enhance the rheological properties of the formulation for 3D printing, the ratio of glycerol to API-IL was adjusted while maintaining a consistent addition of 20% plasticizer. A 50/50 ratio allowed obtaining an initial melt viscosity suitable for extrusion-based processes, at approximately 1 kPa.s at a shear rate of 10 s−1, with a shear thinning behavior. This viscosity remained stable during a processing window of about 6 min, before zein proteins start to aggregate, leading to an apparent gelation phenomenon for long residence times. The processability of this formulation containing API-IL for the printing of tablets for potential therapeutic applications was confirmed by tests on a 3D printer. Nonetheless, in comparison to a reference formulation containing only glycerol, the printing accuracy experienced a decrease. This was ascribed to slower viscous sintering kinetics in presence of API-IL, evidenced by monitoring fusion-bonding during dynamic X-ray tomography trials carried out at Synchrotron SOLEIL.

•Plant-based melt-processable biopolymers are considered for AM.•Material extrusion (ME) processing window raises complex but addressable challenges.•Thermophysical specifications are detailed to assess plant biopolymers printability.•Specific functionalities of ME printed parts can be targeted by reverse engineering.

ABSTRACTThe majority of patients with acute febrile jaundice (>95%) identified through a yellow fever surveillance program in the Democratic Republic of Congo (DRC) test negative for antibodies against yellow fever virus. However, no etiological investigation has ever been carried out on these patients. Here, we tested for hepatitis A (HAV), hepatitis B (HBV), hepatitis C (HCV), hepatitis D (HDV), and hepatitis E (HEV) viruses, all of which can cause acute febrile jaundice, in patients included in the yellow fever surveillance program in the DRC. On a total of 498 serum samples collected from suspected cases of yellow fever from January 2003 to January 2012, enzyme-linked immunosorbent assay (ELISA) techniques were used to screen for antibodies against HAV (IgM) and HEV (IgM) and for antigens and antibodies against HBV (HBsAg and anti-hepatitis B core protein [HBc] IgM, respectively), HCV, and HDV. Viral loads and genotypes were determined for HBV and HVD. Viral hepatitis serological markers were diagnosed in 218 (43.7%) patients. The seroprevalences were 16.7% for HAV, 24.6% for HBV, 2.3% for HCV, and 10.4% for HEV, and 26.1% of HBV-positive patients were also infected with HDV. Median viral loads were 4.19 × 105IU/ml for HBV (range, 769 to 9.82 × 109IU/ml) and 1.4 × 106IU/ml for HDV (range, 3.1 × 102to 2.9 × 108IU/ml). Genotypes A, E, and D of HBV and genotype 1 of HDV were detected. These high hepatitis prevalence rates highlight the necessity to include screening for hepatitis viruses in the yellow fever surveillance program in the DRC.

The formation of ultra-small Mg-based particles nanoconfined into the mesopores of a carbon template was studied by in situsynchrotron diffraction. Either Mg2Ni or Mg2NiH4nanoparticles can be directly formed starting from separate Ni and MgH2nano-species by tuning the H2pressure and temperature. Both ultra-small Mg2Ni and Mg2NiH4nanoparticles (∼4nm) are extremely stable against coalescence during hydrogen sorption cycling and prolonged exposure to high temperature as compared to Mg and MgH2nanoparticles that show severe coalescence under same experimental conditions. The structural transition reported in bulk Mg2NiH4from high temperature cubic to low temperature monoclinic structure is no longer observed for the nanoconfined particles. Hydrogen absorption/desorption in nanosized Mg2Ni is reversible and sorption kinetics proceed very quickly (∼5min) even at 483K. On the contrary, the thermodynamics properties are not altered by nanoconfinement. This study opens new routes for successful nanoconfinement of stoichiometric hydrides into the pores of carbon hosts along with a better understanding of the underlying nanochemistry.

ABSTRACTThe prevalence of hepatitis B virus (HBV) surface antigen was significantly higher in urban (12.9%) than in rural (7.6%) populations (P= 0.003), but no difference was found in the prevalence of hepatitis delta virus (HDV), which was high in both populations. Phylogenetic analysis showed the circulation of HBV-A3 and -E genotypes and the presence of HDV-1, HDV-7, and HDV-8 clades.

Domestic pets can contract severe acute respiratory syndrome coronavirus 2 (SARS‐CoV‐2) infection; however, it is unknown whether the UK B.1.1.7 variant can more easily infect certain animal species or increase the possibility of human‐to‐animal transmission. This is a descriptive case series reporting SARS‐CoV‐2 B.1.1.7 variant infections in a group of dogs and cats with suspected myocarditis. The study describes the infection of domestic cats and dogs by the B.1.1.7 variant. Two cats and one dog were positive to SARS‐CoV‐2 PCR on rectal swab, and two cats and one dog were found to have SARS‐CoV‐2 antibodies 2–6 weeks after they developed signs of cardiac disease. Many owners of these pets had developed respiratory symptoms 3–6 weeks before their pets became ill and had also tested positive for COVID‐19. Interestingly, all these pets were referred for acute onset of cardiac disease, including severe myocardial disorders of suspected inflammatory origin but without primary respiratory signs. These findings demonstrate, for the first time, the ability for pets to be infected by the B.1.1.7 variant and question its possible pathogenicity in these animals.

Polyquaternium-74 is a synthetic high performance conditioning polymer whose flocculation and deposition characteristics enable it to match or outperform traditional conditioning polymers in detangling, overall hair conditioning, shine enhancement and buildup reduction when combined, as shown here, with a submicron dimethicone emulsion. Benefits are noted for 2-in-1 shampoo formulations. [ABSTRACT FROM AUTHOR]

Needs for recycling thermoset composite materials are considerably increasing. Unfortunately, such materials are particularly difficult to recycle due to their crosslinked nature. In this paper, we focus on the case of Sheet Moulding Compounds (SMC), which consist of an unsaturated polyester filled with glass fibres and calcium carbonate. We consider the possibilities of mechanical treatments allowing to obtain ground fractions that could be used as fillers for the reinforcement of thermoplastics. Two processes are described and compared with an existing industrial one. Finally, optimised fractions of SMC waste are introduced into polypropylene, leading to promising results in term of mechanical properties.

Two different metallo-supramolecular amphiphilic block copolymers have been synthesized, using a hydrophilic poly(ethylene oxide) block connected through a bis-(2,2′:6′2″-terpyridine-ruthenium) complex either to a hydrophobic polystyrene or to a poly(ethylene-co-butylene) block. These copolymers were used to prepare aqueous micelles. The morphological characterization of the metallo-supramolecular micelles was performed by dynamic light scattering and transmission electron microscopy. Besides individual micelles, larger structures were also observed by these two independent techniques. The larger structures were the result of aggregation of individual micelles. In addition, the influence of the ionic strength of the medium was investigated. Although the metallo-supramolecular copolymers do not contain charged blocks, the corresponding micelles behaved as polyelectrolyte-like micelles. This behaviour was attributed to the presence of NaCl ions, strongly associated to the poly(ethylene oxide) blocks. This was evidenced by transmission electron microscopy, that revealed the presence of the salt in the metallo-supramolecular micelles. Copyright © 2003 Society of Chemical Industry

The complex thermorheological behaviour observed in miscible polymer blends is modelled by combining two existing theoretical approaches: The Thermal Concentration Fluctuation model (A. Zetsche, E.W. Fischer, Acta Polymer.1994, 45, 168) and the Effective Concentration model (T.P. Lodge, T.C.B. McLeish, Macromolecules2000, 33, 5278), giving rise to a simple model with only one adjustable parameter. This model is then tested in the case of two model blends allowing to show its abilities and limitations to describe how the respective segmental dynamics of lowest or highest Tgcomponent are affected by blending.

The overall size and composition of the pool of naive and memory T cells are tightly regulated by homeostatic mechanisms. Recent work has shown that homeostasis of naive T cells is controlled by two factors, self-major histocompatibility complex (MHC)/peptide ligands and a cytokine, interleukin (IL)-7. In particular, contact with these two factors is required for naive CD4+ and CD8+ cells to undergo “homeostatic” proliferation, i.e., proliferation induced as a consequence of severe T cell depletion. In contrast to naive T cells, the factors that drive memory T cells to undergo homeostatic proliferation are poorly understood. To address this issue, purified memory phenotype CD4+ and CD8+ cells from normal mice were adoptively transferred into various gene-knockout mice rendered T cell–deficient by sublethal irradiation. Three findings are reported. First, unlike naive T cells, homeostatic proliferation of memory T cells is largely MHC independent. Second, memory CD8+ cells can utilize either IL-7 or IL-15 to undergo homeostatic proliferation; however, in the absence of both IL-7 and IL-15, homeostatic proliferation fails to occur. Third, unlike memory CD8+ cells, homeostatic proliferation of memory CD4+ cells is independent of IL-7 and IL-15 (also IL-4). Thus, the homeostatic proliferation mechanisms that control memory CD8+ cells and memory CD4+ cells are quite distinct.

Examining the rate of in vivo T cell turnover (proliferation) in aged mice revealed a marked reduction in turnover at the level of memory-phenotype CD44hi CD8+ cells relative to young mice. Based on adoptive transfer experiments, the reduced turnover of aged CD44hi CD8+ cells reflected an inhibitory influence of the aged host environment. Aged CD44hi CD8+ cells also showed poor in vivo responses to IL-15 and IL-15–inducing agents, but responded well to IL-15 in vitro. Two mechanisms could account for the reduced turnover of aged CD44hi CD8+ cells in vivo. First, aging was associated with a prominent and selective increase in Bcl-2 expression in CD44hi CD8+ cells. Hence, the reduced turnover of aged CD44hi CD8+ cells may in part reflect the antiproliferative effect of enhanced Bcl-2 expression. Second, the impaired in vivo response of aged CD44hi CD8+ cells to IL-15 correlated with increased serum levels of type I interferons (IFN-I) and was largely reversed by injection of anti–IFN-I antibody. Hence the selective reduction in the turnover of aged CD44hi CD8+ cells in vivo may reflect the combined inhibitory effects of enhanced Bcl-2 expression and high IFN-I levels.

We developed a simple, rapid, inexpensive, and highly sensitive and specific strategy for the detection and lineage differentiation of primate lentiviruses (PIV-ELISA). It is based on the use of two indirect ELISA methods using synthetic peptides mapping the gp41/36 region (detection component) and the V3 region (differentiation component) of four lentivirus lineages, namely SIVcpz/HIV-1 (groups M, O, N, and SIVcpz-gab), SIVmnd, SIVagm, and SIVsm/SIVmac/HIV-2. This strategy was evaluated with panels of sera originating from both humans and nonhuman primates. The human reference panel consisted of 144 HIV Western blot (WB)-positive sera in which the corresponding virus had been genotyped (HIV-1: 72 group M, 28 group O, and 6 group N; HIV-2: 21 subtype A and 10 subtype B; and 7 HIV-1+2) and 105 HIV WB-negative samples. The nonhuman primate reference panel consisted of 24 sera from monkeys infected by viruses belonging to the four lineages included in the PIV-ELISA strategy (5 chimpanzees, 5 macaques, 8 mandrills, and 6 vervets) and 42 samples from seronegative animals. Additional field evaluation panels consisted of 815 human sera from Gabon, Cameroon, and France and 537 samples from 25 nonhuman primate species. All the samples from the two reference panels were correctly detected and discriminated by PIV-ELISA. In the human field evaluation panel, the gp41/36 component correctly identified all the test samples, with 98% specificity. The V3 component discriminated 206 HIV-1 group M, 98 group O, 12 group M+O, and 128 HIV-2 sera. In the primate field evaluation panel, both gp41/36 and V3 detected and discriminated all the WB-positive samples originating from monkeys infected with SIVcpz, SIVagm-ver, SIVmnd-1, SIVmnd-2, SIVdrl, or SIVsun. These results were confirmed by genotyping in every case. Four SIV-infected red-capped mangabeys (confirmed by PCR) were correctly identified by gp41/36, but only two reacted with the V3 peptides in the absence of a specific SIVrcm V3 peptide. Addition of a V3 SIVrcm peptide discriminated all the SIVrcm-positive samples. Fourteen Papio papio samples were positive for SIVsm gp 36 and by WB, but negative by PCR, whereas three Papio cynocephalus samples were positive by gp41/36 but indeterminate by WB and negative by PCR. This combined ELISA system is thus highly sensitive and specific for antibodies directed against HIV and SIV. In addition, the V3-based serotyping results always agreed with genotyping results. This method should prove useful for studies of lentivirus prevalence and diversity in human and nonhuman primates, and may also have the potential to detect previously undescribed SIVs.

In this work, temperature modulated DSC is used to measure the heat flow evolved during the cure reaction of a dicyanate ester resin. This technique enables the heat capacity contribution to be separated from the heat source term (from the kinetic behavior) in nonisothermal conditions. At any given moment, therefore, the true reaction rate can be calculated without any assumptions about the shape of the baseline of the thermogram. Resulting accurate data are used for the characterization of cure kinetics. The isoconversional analysis shows that the apparent activation energy varies with conversion degree, so that a Kamal & Sourour kinetic model is proposed. Its kinetic parameters are obtained by an inverse method, and such a model is successfully used to simulate nonisothermal, isothermal and multistep cure experiments.

Differential scanning calorimetry (DSC) is one of the most used methods for kinetic studies of thermoset cure reactions. The basic assumption made in this technique is the proportionality between the heat generation rate and cure reaction rate. To have access to the heat generation rate that provides information about reaction kinetics, one must know the baseline under the measured curve. Various methods of baseline construction are described and recommended, but most thermoset cure kinetic studies only use a straight line between the exothermal peak start and the end. The influence of changes in the sample's heat capacity is rarely taken into consideration. The use of data obtained with this type of baseline to determine kinetic parameters can lead to significant errors. DSC thermograms in the scanning mode are simulated for two epoxy-amine type systems of known cure kinetic and thermophysical characteristics. Simulated thermograms are analyzed using a straight baseline, and different parameter estimation techniques are applied to the resulting data to characterize the cure reaction. The results are compared with real values. © 2000 John Wiley & Sons, Inc. J Appl Polym Sci 78: 2262–2271, 2000

AbstractThe 3D solution structure of α-cobratoxin, a neurotoxin purified from the Naja naja siamensissnake venom, has been determined by Nuclear Magnetic Resonance spectroscopy, in conjunction with distance geometry and restrained molecular dynamics, at pH 7.5. A total of 490 distance restraints were obtained from NOE intensities and 25 φ dihedral angle restraints deduced from J- coupling data. The generated structures are well defined with root mean square deviations from a geometrical mean structure of 0.107 ± 0.036 nm for the backbone atoms and 0.128 ±0.073 nm for the side-chain atoms (considering residues 1 to 66 minus 26 to 35). A comparison between the generated structures at pH 7.5 and the mean NMR solution structure at pH 3.2 revealed that the 3D structure of α-cobratoxin is more compact at neutral pH. This major difference is mainly due to the pH-dependant conformational variations of three residues His18, Thr44and Thr59.

The increased research on bat coronaviruses after severe acute respiratory syndrome coronavirus (SARS-CoV) and Middle East respiratory syndrome coronavirus (MERS-CoV) allowed the very rapid identification of SARS-CoV-2. This is an excellent example of the importance of knowing viruses harbored by wildlife in general, and bats in particular, for global preparedness against emerging viral pathogens.

Magnetotactic bacteria (MTB) have long fascinated geologists and biologists because they biomineralize intracellular single domain (SD) magnetite crystals within magnetosomes that are generally organized into single or multiple chains. MTB remains in the geological record (magnetofossils) are ideal magnetic carriers and are used to reconstruct paleomagnetic and paleoenvironmental information. Here we studied the biomineralization and magnetic properties of magnetosomal magnetite produced by uncultured magnetotactic coccus strain THC‐1, isolated from the Tanghe River, China, by combining transmission electron microscope (TEM) and rock magnetic approaches. Our results reveal that THC‐1 produces hexagonal prismatic magnetite single crystals that are elongated along the [111] crystallographic direction. Most of the magnetite crystals within THC‐1 are dispersed without obvious chain assembly. A whole‐cell THC‐1 sample yields a normal SD hysteresis loop and a Verwey transition temperature of ~112 K. In contrast to MTB cells with magnetosome chain(s), THC‐1 cells have a teardrop first‐order reversal curve distribution that is indicative of moderate interparticle interactions. Due to the absence of a magnetosome chain, THC‐1 has relatively high values of the difference between the saturation isothermal remanent magnetization (SIRM) below and above the Verwey transition temperature for field‐cooled and zero field‐cooled SIRM curves (δFC, δZFC) and a low δFC/δZFCvalue. Together with previous studies, our results demonstrate that some MTB species/strains can form magnetosomal magnetite without linear chain configurations. Magnetite produced by MTB has diverse magnetic properties, which are distinctive but not necessarily unique compared to other magnetite types. Therefore, combining bulk magnetic measurements and TEM observations remains necessary for identifying magnetofossils in the geological record. Magnetotactic bacteria (MTB) are intriguing because they produce magnetic nanocrystals of magnetite (Fe3O4) or greigite (Fe3S4) within intracellular organelles (magnetosomes) that can leave tiny magnetic fossils (magnetofossils) in the geological record. Magnetofossil identification for paleoenvironmental and paleomagnetic purposes is based heavily on knowledge of modern MTB that often organize magnetic particles into chain(s). We studied here the crystallographic and magnetic properties of uncultured magnetotactic coccus strain THC‐1 in which magnetosomal magnetite particles are dispersed without obvious chain assembly. In contrast to whole‐cell MTB samples with magnetosome chain(s), THC‐1 has distinctive magnetic properties. Together with previous studies, our results demonstrate that MTB magnetite has diverse magnetic properties that are distinctive but not necessarily unique compared to other magnetite types. This indicates that combining magnetic measurements and transmission electron microscope observations remains necessary for identifying magnetofossils. Magnetotactic coccus THC‐1 forms prismatic magnetosomal magnetite that is dispersed within the cellTHC‐1 has distinctive magnetic properties compared to magnetotactic bacteria (MTB) with magnetosome chainsMTB magnetite is magnetically distinctive but not unique compared to other magnetite types

Magnetite produced by magnetotactic bacteria (MTB) provides stable paleomagnetic signals because it occurs as natural single‐domain magnetic nanocrystals. MTB can also provide useful paleoenvironmental information because their crystal morphologies are associated with particular bacterial groups and the environments in which they live. However, identification of the fossil remains of MTB (i.e., magnetofossils) from ancient sediments or rocks is challenging because of their generally small sizes and because the growth, morphology, and chain assembly of magnetite within MTB are not well understood. Nanoscale characterization is, therefore, needed to understand magnetite biomineralization and to develop magnetofossils as biogeochemical proxies for paleoenvironmental reconstructions. Using advanced transmission electron microscopy, we investigated magnetite growth and chain arrangements within magnetotactic Deltaproteobacteria strain WYHR‐1, which reveals how the magnetite grows to form elongated, bullet‐shaped nanocrystals. Three crystal growth stages are recognized: (i) initial isotropic growth to produce nearly round ~20 nm particles, (ii) subsequent anisotropic growth along the [001] crystallographic direction to ~75 nm lengths and ~30–40 nm widths, and (iii) unidirectional growth along the [001] direction to ~180 nm lengths, with some growing to ~280 nm. Crystal growth and habit differ from that of magnetite produced by other known MTB strains, which indicates species‐specific biomineralization. These findings suggest that magnetite biomineralization might be much more diverse among MTB than previously thought. When characterized adequately at species level, magnetofossil crystallography, and apomorphic features are, therefore, likely to become useful proxies for ancient MTB taxonomic groups or species and for interpreting the environments in which they lived. Biomineralization is a widespread process that provides living organisms with mineralized skeletons and organelles. Biominerals are mainly responsible for Earth's fossil record. As a striking example of microbial biomineralization, magnetotactic bacteria form intracellular chains of magnetic nanocrystals that they use to sense Earth's magnetic field. Their fossilized remains (magnetofossils) are being used increasingly to reconstruct paleomagnetic and paleoenvironmental information. However, magnetofossil identification remains challenging because magnetite particle growth and chain assembly processes are poorly understood. We report a species‐specific crystal growth and chain arrangement process in a novel magnetotactic strain WYHR‐1. Our findings suggest that magnetofossil crystallography could become a proxy for ancient bacterial taxonomic groups or species and for interpreting the environments in which they lived. Magnetite produced by MTB carries stable paleomagnetic signals, but paleoenvironmental interpretation of biogenic magnetite is less obviousWe find that magnetite crystals grow by a multistep process in a novel MTB to form highly elongated, bullet‐shaped magnetiteSpecies‐specific magnetite biomineralization indicates that magnetite morphology is a proxy for ancient MTB taxonomic groups or species

The article discusses the report of virologist Eric Leroy of the International Centre for Medical Research of Franceville, the World Health Organization (WHO) collaborating center in Gabon that is qualifying the Ebola virus in the Democratic Republic of the Congo (DRC), revealing its non-relation to the 6-month-old epidemic in West Africa. Topics cited include the urgent calls for immediate action to contain the outbreak, the Ebola statistics according to WHO, and the outbreak zone in the DRC.

The aim of this study was to provide information on trypanosome species infecting trypanotolerant cattle from southern Gabon. The study was conducted on 224 trypanotolerant cattle from three regions located in southern Gabon, using ITS1primer-based PCR. Seventy-two (32%) N’dama cattle were found polymerase chain reaction (PCR) positive with trypanosomes. The overall prevalence of trypanosomosis was 57% (63/110), 4% (4/100), and 36% (5/14) in the Gala section of the Nyanga ranch, the Miyama ranch, and Ossiele, respectively. Trypanosoma congolenseand Trypanosoma vivaxwere identified. In Gala section and Ossiele, T. congolenseand T. vivaxwere found. In the Miyama ranch, only T. vivaxwas identified. Mixed infections were also found. The forest(9%) and savannah(63%) subgroups of T. congolensewere identified. The presence of the two subgroups was detected in 16 out of 56 cattle (29%). T. congolenseand T. vivaxwould appear to be the main agents responsible for bovine trypanosomosis in southern Gabon. Although trypanotolerant, N’dama cattle may serve as a reservoir, and this should be further studied. On the other hand, these trypanotolerant cattle can be reared in such tsetse infested areas, which gives them an advantage compared to other trypanosensitive breeds, and this shows that they represent a key factor in biodiversity which has to be promoted.

Magnetotactic bacteria (MTB) are known to produce single-domain magnetite or greigite crystals within intracellular membrane organelles and to navigate along the Earth's magnetic field lines. MTB have been suggested as being one of the most ancient biomineralizing metabolisms on the Earth and they represent a fundamental model of intracellular biomineralization. Moreover, the determination of their specific crystallographic signature (e.g. structure and morphology) is essential for palaeoenvironmental and ancient-life studies. Yet, the mechanisms of MTB biomineralization remain poorly understood, although this process has been extensively studied in several cultured MTB strains in the Proteobacteriaphylum. Here, we show a comprehensive transmission electron microscopy (TEM) study of magnetic and structural properties down to atomic scales on bullet-shaped magnetites produced by the uncultured strain MYR-1 belonging to the Nitrospiraephylum, a deeply branching phylogenetic MTB group. We observed a multiple-step crystal growth of MYR-1 magnetite: initial isotropic growth forming cubo-octahedral particles (less than approx. 40 nm), subsequent anisotropic growth and a systematic final elongation along [001] direction. During the crystal growth, one major {111} face is well developed and preserved at the larger basal end of the crystal. The basal {111} face appears to be terminated by a tetrahedral–octahedral-mixed iron surface, suggesting dimensional advantages for binding protein(s), which may template the crystallization of magnetite. This study offers new insights for understanding magnetite biomineralization within the Nitrospiraephylum.

The article focuses on a study related to the Ebola virus. It causes sporadic, lethal outbreaks in people and apes in Africa. Researcher Eric Leroy and his colleagues of Gabon based-International Centre for Medical Research in Franceville Basin, think they have tracked it down to three species of fruit bat. Previous campaigns to test animals, including bats, in outbreak zones have failed to find the virus. This time the effort succeeded, says Leroy, because the team sampled bats near where carcasses of apes killed by Ebola were found, within days of the apes' deaths. The study was published in the journal "New Scientist."

Reports on the use of dogs in monitoring the spread of Ebola virus in the African country of Gabon. Role of epidemiologist Eric Leroy in a study on Ebola antibodies in dogs; Significance of the study in gathering information in regions where tracing the disease is difficult; Attitude of villagers in the area towards the collection of blood samples.

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Eric Kraft. Crown, $20 (192p) ISBN 0517-59614-8 Peter Leroy, hotel owner in the town of Babbington, Long Island ('dam capital of America'), offers further marvelously appealing recollections of his boyhood [...]