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Abstract: The kinetics of sulfur vulcanization of rubber presents two specific aspects: The main crosslinking reaction is preceded by an induction period during which the crosslink density increases very slowly (these two steps are generally described separately by existing kinetic models); and can be followed by reversion due to the thermal degradation of unstable polysulfide crosslinks formed during vulcanization. This phenomenon, which results in lower final mechanical properties for high curing temperatures, is studied here by combining classical isothermal kinetic experiments with high temperature post-cure experiments on rubber samples previously vulcanized at low temperature where reversion is negligible. The isoconversional analysis of experimental data is shown to allow the development of an efficient kinetic parameter estimation technique for an existing semi-mechanistic kinetic model describing reversion, and leads to the development of a new continuous kinetic model allowing the simulation of the whole kinetic process including the induction, main vulcanization and reversion steps. [Copyright &y& Elsevier]

Abstract: Isoconversionnal kinetic analysis was applied for the first time to the isothermal cure reaction of an elastomer compound. The apparent activation energy obtained was almost constant, regardless of the degree of cure. Such a result justifies the use of simple phenomenological kinetic models with a unique activation energy, and allows development of a knowledge based approach to kinetic parameters estimation, applied to two models frequently used for the modelling of elastomer cure reactions: the Isayev and Kamal & Sourour models. Simplified Kamal & Sourour models with a reduced number of kinetic parameters were obtained. Simulations with such models give a better description of experimental data than the Isayev model, especially taking into account the simulation of the rate of reaction. [Copyright &y& Elsevier]

Deep eutectic solvents (DES) based on choline chloride and hydrogen bond donors are shown to be efficient functional additives for thermoplastic starch, able to act as efficient plasticizers, water uptake inhibitors, and as compatibilizers in the case of blends with a hydrophobic phase. One of the DES tested also prevents the recrystallization of starch. Although such properties can also be obtained with an imidazolium chloride ionic liquid, DES present the advantage of being environmentally friendly and potentially cheaper. Their wide potential in terms of formulation, by adjusting the nature and content of the hydrogen bond donor, opens new perspectives for the development of efficient starch based biodegradable plastics and composites. [ABSTRACT FROM AUTHOR]

Abstract: Poly(hydroxy-alcanoates) bioplastics have an unusually small temperature processing window due to their thermal instability, which affects both molecular weight distribution and rheological behavior. The use of a rheometrical device mounted on an injection molding machine has been shown to allow the study of dynamic viscosity variations for very short residence times in the melt (down to a few tens of seconds). Moreover, dynamic viscosity can be obtained over a wide range of shear rates (up to 50000 s−1) with both Bagley and Rabinowitsch corrections. The rheological data obtained for a poly(3-hydroxybutyrate-co-3-hydroxyvalerate), PHBV copolymer shows that the reduction in viscosity associated with degradation is very fast and is detectable even at temperatures close to the melting point. Size Exclusion Chromatography analysis of selected samples shows that, except for residence times below 15s, molecular mass distribution is substantially affected, shifting toward lower masses, and with an increase in oligomer compound content. These oligomers may act as plasticizers of the bioplastic. The results also suggest that important thermomechanical degradation takes place during the plasticization/feeding step of injection molding. [Copyright &y& Elsevier]

Health research programs targeting the population of Gabon and Equatorial Africa at the International Center for Medical Research in Franceville (CIRMF), Gabon, have evolved during the years since its inception in 1979 in accordance with emerging diseases. Since the reemergence of Ebola virus in Central Africa, the CIRMF "Emerging Viral Disease Unit" developed diagnostic tools and epidemiologic strategies and transfers of such technology to support the response of the National Public Health System and the World Health Organization to epidemics of Ebola virus disease. The Unit carries out a unique investigation program on the natural history of the filoviruses, emergence of epidemics, and Ebola virus pathogenesis. In addition, academic training is provided at all levels to regional and international students covering emerging conditions (host factors, molecular biology, genetics) that favor the spread of viral diseases. [ABSTRACT FROM AUTHOR]

Ebolavirus and Marburgvirus, two filoviruses belonging to the Filoviridae family, are among the most virulent pathogens for humans and non-human primates, causing outbreaks of fulminant hemorrhagic fever (HF) in Central African countries with case fatality rates of up to 90%. Fruit bats are the likely reservoir, and human infection occurs through contact with bats or infected large-animal carcasses or by person-to-person contact (through body fluids, medical care, and burial practices). Schematically, clinical manifestations occur in three successive phases and include general, gastrointestinal, and mucocutaneous disorders. Death usually results from hemorrhagic complications. Cutaneous manifestations rarely make a major contribution to disease severity but can assist with the diagnosis. Rash, the main cutaneous disorder, is nonspecific and cannot guide the differential diagnosis. Immunohistochemical examination of skin biopsy or necropsy specimens can confirm the diagnosis. [ABSTRACT FROM AUTHOR]

Abstract: An ionic liquid (1-butyl-3-methyl imidazolium chloride [BMIM]Cl) was used as a plasticizer in starch, zein and their blends; and compared to glycerol, a classical plasticizer of starch. Thermoplastic plasticized biopolymer materials were obtained by melt processing using a twin screw microcompounder. Such a device allows simulating a twin screw extrusion process on small batches of a few grams, and to evaluate the necessary specific mechanical energy input for native starch destructurization; and the final apparent melt viscosity. Both were shown to be significantly reduced for starch in presence of [BMIM]Cl (compared to glycerol), while zein processing behavior was less sensitive to the plasticizer used. This induces significant starch/zein viscosity ratio differences, which affect melt mixing of the starch zein blends. In starch rich blends, this results in smaller zein aggregates in the case of [BMIM]Cl. The characterization of the materials indicates that, compared to glycerol, the use of [BMIM]Cl leads to less hygroscopicity, a more efficient plasticization of both starch and zein phases and a compatibilization of starch/zein blends. [Copyright &y& Elsevier]

Abstract: A styrene–butadiene copolymer is filled with mixtures of pyrogenic silica combined with a silane coupling agent and fibers of organophilic sepiolite. The mechanical properties of the composites reveal that a mixture of double fillers impart to the elastomeric matrix a higher degree of reinforcement than that which would result from a simple addition of the two types of fillers. The swelling ratio of the composite containing the two types of fillers was found to highly decrease with regard to the pure polymer reflecting strong interactions with the matrix. The changes in the state of dispersion by adding the second filler were evaluated by transmission electron microscopy. [Copyright &y& Elsevier]

Since 2004, several million indigenous cases of Chikungunya virus disease occurred in Africa, the Indian Ocean, India, Asia and, recently, Europe. The virus, usually transmitted by Aedes aegypti mosquitoes, has now repeatedly been associated with a new vector, Ae. Albopictus. Analysis of full-length viral sequences reveals three independent events of virus exposure to Ae. Albopictus, each followed by the acquisition of a single adaptive mutation providing selective advantage for transmission by this mosquito. This disconcerting and current unique example of "evolutionary convergence" occurring in nature illustrates rapid pathogen adaptation to ecological perturbation, driven directly as a consequence of human activities. [ABSTRACT FROM AUTHOR]

Background. Patients who have refused to provide blood samples has meant that there have been significant delays in confirming outbreaks of Ebola virus hemorrhagic fever (EVHF). During the 2 EVHF outbreaks in the Republic of Congo in 2003, we assessed the use of oral fluid specimens versus serum samples for laboratory confirmation of cases of EVHF. Methods. Serum and oral fluid specimens were obtained from 24 patients with suspected Ebola and 10 healthy control subjects. Specimens were analyzed for immunoglobulin G antibodies by enzyme-linked immunosorbent assay (ELISA) and for Ebola virus by antigen detection ELISA and reverse-transcriptase polymerase chain reaction (RT-PCR). Oral fluid specimens were collected with a commercially available collection device. Results. We failed to detect antibodies against Ebola in the oral fluid specimens obtained from patients whose serum samples were seropositive. All patients with positive serum RT-PCR results also had positive results for their oral fluid specimens. Conclusions. This study demonstrates the usefulness of oral fluid samples for the investigation of Ebola outbreaks, but further development in antibodies and antigen detection in oral fluid specimens is needed before these samples are used for filovirus surveillance activities in Africa. [ABSTRACT FROM AUTHOR]

Abstract: The evolution of the coefficient of thermal expansion (CTE) of a thermosetting polymer during cure reaction is an important parameter for industrial applications such as composite processing since it influences the development of internal stresses in the material. The CTE being almost impossible to measure on a reacting thermoset, we propose to use an indirect method based on the modelling of ionic conductivity by a modified WLF equation, allowing to calculate the evolution of CTE from dielectric spectroscopy measurements. This method is applied to a dicyanate ester thermosetting polymer, leading to encouraging results both qualitatively and quantitatively. [Copyright &y& Elsevier]

Several human and animal Ebola outbreaks have occurred over the past 4 years in Gabon and the Republic of Congo. The human outbreaks consisted of multiple simultaneous epidemics caused by different viral strains, and each epidemic resulted from the handling of a distinct gorilla, chimpanzee, or duiker carcass. These animal populations declined markedly during human Ebola outbreaks, apparently as a result of Ebola infection. Recovered carcasses were infected by a variety of Ebola strains, suggesting that Ebola outbreaks in great apes result from multiple virus introductions from the natural host. Surveillance of animal mortality may help to predict and prevent human Ebola outbreaks. [ABSTRACT FROM AUTHOR]

In a previous paper, the kinetic behavior of a cyanate ester trimerization was studied. In this paper, the thermophysical properties (heat capacity, thermal conductivity) are measured and modeled (as a function of temperature and conversion) for the neat resin and for a glass fibers composite. These models (thermophysical and kinetics) are used to simulate the thermal transfers in an instrumented heated mold. The calculated local temperatures and surface heat fluxes appear to be in very good agreement with measurements, for both the neat resin and the composite. [Copyright &y& Elsevier]

The human and simian strains of Loa loa microfilariae are morphologically identical even though their periodicities vary. When using primate models (Mandrillus sphinx) of human loaisis for vaccination trials, the absence of any ongoing simian L, loa infection must be demonstrated. Nested primers derived from a human strain of L. loa (targeted on the repeat 3 region of the gene encoding the 15 kDa polyprotein; 15r3) amplified at 366 bp sequence from simian L. loa genomic DNA and blood lysates from mandrills infected with simian L. loa. This nested-PCR assay has been tested on 12 amicrofilaremic (AMF) mandrills (without filarial microfilariae) and was positive in four mandrills. The nested-PCR product derived from simian L. loa genomic DNA and from three of four AMF mandrills has been sequenced. No difference was observed between the four sequences, which, in addition, were 99. 18% identical to the 15r3 of human L. loa. Therefore, the 15r3 sequence is conserved within human and simian L. loa. These results suggest that the four PCR-positive mandrills without circulating microfilariae had occult simian L. loa infections. The study demonstrates the ability of a nested-PCR assay to identify animals naturally infected with simian L. loa. [ABSTRACT FROM AUTHOR]

Ebola virus is very pathogenic in humans. It induces an acute hemorrhagic fever that leads to death in about 70% of patients. We compared the immune responses of patients who died from Ebola virus disease with those who survived during two large outbreaks in 1996 in Gabon. In survivors, early and increasing levels of IgG, directed mainly against the nucleoprotein and the 40-kDa viral protein, were followed by clearance of circulating viral antigen and activation of cytotoxic T cells, which was indicated by the upregulation of FasL, perforin, CD28 and gamma interferon mRNA in peripheral blood mononuclear cells. In contrast, fatal infection was characterized by impaired humoral responses, with absent specific IgG and barely detectable IgM. Early activation of T cells, indicated by mRNA patterns in peripheral blood mononuclear cells and considerable release of gamma interferon in plasma, was followed in the days preceding death by the disappearance of T cell-related mRNA (including CD3 and CD8). DNA fragmentation in blood leukocytes and release of 41/7 nuclear matrix protein in plasma indicated that massive intravascular apoptosis proceeded relentlessly during the last 5 days of life. Thus, events very early in Ebola virus infection determine the control of viral replication and recovery or catastrophic illness and death. [ABSTRACT FROM AUTHOR]

Reports on the Ebola hemorrhagic fever outbreaks in Gabon during 1994-1995. Diagnosis of yellow fever among patients prior to the discovery of the presence of Ebola virus; Other epidemics that occurred in the northeastern part of the country.

Studies the structure determination of C-terminal complementary peptide bound to a mutant phosphoglycerate kinase (PGK) and conformational changes in the peptide induced by formation of peptide-protein complex by transferred nuclear Overhauser effect spectroscopy (NOE). Presence of alpha-helix fold in 405-409 region; Discussion on the role of alpha-helix from C-terminal peptide in recovery of catalytic activity in mutant PGK.

An outbreak of febrile illness occurred in Gabon in 2007, with 20,000 suspected cases. Chikungunya or dengue-2 virus infections were identified in 321 patients; 8 patients had documented co-infections. Aedes albopictus was identified as the principal vector for the transmission of both viruses. [ABSTRACT FROM AUTHOR]

Hepatitis B virus (HBV) infection leads to around 800,000 deaths yearly and is considered to be a major public health problem worldwide. However, HBV origins remain poorly understood. Here, we looked for bat HBV (BtHBV) in different bat species in Gabon to investigate the role of these animals as carriers of ancestral hepadnaviruses because these viruses are much more diverse in bats than in other host species. DNA was extracted from 859 bat livers belonging to 11 species collected in caves and villages in the southeast of Gabon and analyzed using PCRs targeting the surface gene. Positive samples were sequenced using the Sanger method. BtHBV DNA was detected in 64 (7.4%) individuals belonging to eight species mainly collected in caves. Thirty-six (36) sequences among the 37 obtained after sequencing were phylogenetically close to the RBHBV strain recently isolated in Gabonese bats, while the remaining sequence was close to a rodent HBV strain isolated in America. The generalized linear mixed model showed that the variable species best explained the occurrence of BtHBV infection in bats. The discovery of a BtHBV strain homologous to a rodent strain in bats raises the possibility that these animals may be carriers of ancestral hepadnaviruses. [ABSTRACT FROM AUTHOR]

Rift Valley fever (RVF) is a mosquito-borne viral zoonosis caused by the Rift Valley fever virus (RVFV) that can infect domestic and wild animals. Although the RVFV transmission cycle has been well documented across Africa in savanna ecosystems, little is known about its transmission in tropical rainforest settings, particularly in Central Africa. We therefore conducted a survey in northeastern Gabon to assess RVFV circulation among wild and domestic animals. Among 163 wildlife samples tested using RVFV-specific RT-qPCR, four ruminants belonging to subfamily Cephalophinae were detected positive. The phylogenetic analysis revealed that the four RVFV sequences clustered together with a virus isolated in Namibia within the well-structured Egyptian clade. A cross-sectional survey conducted on sheep, goats and dogs living in villages within the same area determined the IgG RVFV-specific antibody prevalence using cELISA. Out of the 306 small ruminants tested (214 goats, 92 sheep), an overall antibody prevalence of 15.4% (95% CI [11.5–19.9]) was observed with a higher rate in goats than in sheep (20.1% versus 3.3%). RVFV-specific antibodies were detected in a single dog out of the 26 tested. Neither age, sex of domestic animals nor season was found to be significant risk factors of RVFV occurrence. Our findings highlight sylvatic circulation of RVFV for the first time in Gabon. These results stress the need to develop adequate surveillance plan measures to better control the public health threat of RVFV. Author summary: Rift Valley fever (RVF) is a mosquito-borne viral zoonosis caused by the Rift Valley fever virus (RVFV) that can affect wild and domestic animals. Although the RVFV transmission cycle has been well documented across Africa in savanna ecosystems, little is known about its transmission in tropical rainforests, especially in Central Africa. We thus conducted a survey in northeastern Gabon to assess RVFV circulation among wild and domestic animals. In this study, we demonstrated for the first time in Gabon the presence of the RVFV in two wildlife species (Peter's duiker Cephalophus callipygus and the blue duiker Philantomba monticola). In addition, we detected RVFV-specific antibodies in small domestic ruminants (sheep and goats) at an overall antibody prevalence of 15.4%, with a much higher seroprevalence rate in goats than sheep (20.1% versus 3.3%). Furthermore, RVFV-specific antibodies were also observed in a single (hunting) dog out of the 26 tested. These results stress the need to develop adequate surveillance plan measures to better control the public health threat of RVFV. [ABSTRACT FROM AUTHOR]

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/δZFC value. 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. Plain Language Summary: 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. Key Points: 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 [ABSTRACT FROM AUTHOR]

An association between malaria and risk for death among patients with Ebola virus disease has suggested within-host interactions between Plasmodium falciparum parasites and Ebola virus. To determine whether such an interaction might also influence the probability of acquiring either infection, we used a large snapshot surveillance study from rural Gabon to test if past exposure to Ebola virus is associated with current infection with Plasmodium spp. during nonepidemic conditions. We found a strong positive association, on population and individual levels, between seropositivity for antibodies against Ebola virus and the presence of Plasmodium parasites in the blood. According to a multiple regression model accounting for other key variables, antibodies against Ebola virus emerged as the strongest individual-level risk factor for acquiring malaria. Our results suggest that within-host interactions between malaria parasites and Ebola virus may underlie epidemiologic associations. [ABSTRACT FROM AUTHOR]

Although Zika virus (ZIKV) circulates in sub-Saharan Africa, no case of ZIKV-associated microcephaly has thus far been reported. Here, we report evidence of a possible association between a 2007 outbreak of febrile illness and an increase in microcephaly and possibly ZIKV infection in Gabon. [ABSTRACT FROM AUTHOR]

The first recorded human outbreak of Ebola virus was in 1976, but the wild reservoir of this virus is still unknown. Here we test for Ebola in more than a thousand small vertebrates that were collected during Ebola outbreaks in humans and great apes between 2001 and 2003 in Gabon and the Republic of the Congo. We find evidence of asymptomatic infection by Ebola virus in three species of fruit bat, indicating that these animals may be acting as a reservoir for this deadly virus. [ABSTRACT FROM AUTHOR]

This article discusses the detection of natural non-polio enteroviruses (EVs) in captive mandrills and chimpanzees housed in a primate center in Franceville, Gabon. The study found that EVs were present in both species, with mandrills carrying EVs of the species EV-J and chimpanzees carrying EVs of the species EV-A90. The detection of EVs in mandrills did not pose a threat to the species, as healthy captive and wild individuals also harbored these EVs. However, the detection of EV-A90 in chimpanzees highlighted the potential risk of zoonotic transmission from humans. The study emphasizes the importance of monitoring and studying EVs in order to protect primate health and prevent the introduction of human pathogens into the wild. [Extracted from the article]

Simple Summary: Enteric viruses cause gastroenteritis in humans and animals, but have also been associated with several extraintestinal diseases. These viruses affect a wide range of vertebrate species, including birds and mammals. Frequent and close contact between humans and animals can potentially lead to the emergence of zoonoses. Approximately 60% of zoonotic diseases in humans are spillovers from wildlife. Preventing future outbreaks of emerging zoonotic diseases calls for better description of the viruses that circulate in domestic animals, because they are located at the human/wildlife interface. We therefore screened for the presence of astroviruses, enteroviruses, and caliciviruses—three of the main viral families causing enteric diseases both in humans and animals—in goats, sheep and dogs living in villages in northeastern Gabon. We identified the presence of astroviruses in goats, a calicivirus in a dog, and enteroviruses in all three species. All detected viruses were animal-related, but not those from wildlife. However, we showed that some human-pathogenic enteroviruses infect goats and dogs. Therefore, further studies are required to better understand the role of domestic animals as amplifiers of reverse zoonotic viruses. Astroviruses (AstVs), enteroviruses (EVs), and caliciviruses (CaVs) infect several vertebrate taxa. Transmitted through the fecal–oral route, these enteric viruses are highly resistant and can survive in the environment, thereby increasing their zoonotic potential. Here, we screened for AstVs, EVs, and CaVs to investigate the role of domestic animals in the emergence of zoonoses, because they are situated at the human/wildlife interface, particularly in rural forested areas in Central Africa. Rectal swabs were obtained from 123 goats, 41 sheep, and 76 dogs in 10 villages located in northeastern Gabon. Extracted RNA reverse-transcribed into cDNA was used to detect AstVs, EVs, and CaVs by amplification of the RNA-dependent RNA polymerase (RdRp), or capsid protein (VP1) gene using PCR. A total of 23 samples tested positive, including 17 goats for AstVs, 2 goats, 2 sheep, 1 dog for EVs, and 1 dog for CaVs. Phylogenetic analyses revealed that AstV RdRp sequences clustered with sheep-, goat-, or bovine-related AstVs. In addition, one goat and two sheep VP1 sequences clustered with caprine/ovine-related Evs within the Enterovirus G species, and the CaV was a canine vesivirus. However, human-pathogenic Evs, EV-B80 and EV-C99, were detected in goats and dogs, raising questions on the maintenance of viruses able to infect humans. [ABSTRACT FROM AUTHOR]

Transgenically-produced amylose-only (AO) starch was used to manufacture bioplastic prototypes. Extruded starch samples were tested for crystal residues, elasticity, glass transition temperature, mechanical properties, molecular mass and microstructure. The AO starch granule crystallinity was both of the B- and Vh-type, while the isogenic control starch was mainly A-type. The first of three endothermic transitions was attributed to gelatinization at about 60 °C. The second and third peaks were identified as melting of the starch and amylose-lipid complexes, respectively. After extrusion, the AO samples displayed Vh- and B-type crystalline structures, the B-type polymorph being the dominant one. The AO prototypes demonstrated a 6-fold higher mechanical stress at break and 2.5-fold higher strain at break compared to control starch. Dynamic mechanical analysis showed a significant increase in the storage modulus (E′) for AO samples compared to the control. The data support the use of pure starch-based bioplastics devoid of non-polysaccharide fillers. [ABSTRACT FROM AUTHOR]

A new process, PMOFSA, is described here, that opens the way for the one-pot straightforward and versatile manufacture of polymer-MOF nanoparticles in water. It can be expected that this study will not only expand the scope of in situ preparation of polymer-MOF nano-objects but also inspire researchers in the field to prepare a new generation of polymer-MOF hybrid materials. [ABSTRACT FROM AUTHOR]

Following the emergence of SARS-CoV-2, cases of pets infected with variants circulating among humans were reported. In order to evaluate the occurrence of SARS-CoV-2 circulation among pets in the Republic of the Congo, we conducted a ten-month study of dogs and cats living in COVID-19-positive households in Brazzaville and neighboring localities. Real-time PCR and the Luminex platform were used to detect SARS-CoV-2 RNA and antibodies to SARS-CoV-2 RBD and S proteins, respectively. Our results show for the first time the simultaneous circulation of several variants of SARS-CoV-2, including viruses from clades 20A and 20H and a putative recombinant variant between viruses from clades 20B and 20H. We found a high seroprevalence of 38.6%, with 14% of tested pets positive for SARS-CoV-2 RNA. Thirty-four percent of infected pets developed mild clinical signs, including respiratory and digestive signs, and shed the virus for about one day to two weeks. These results highlight the potential risk of SARS-CoV-2 interspecies transmission and the benefits of a "One Health" approach that includes SARS-CoV-2 diagnosis and surveillance of viral diversity in pets. This approach aims to prevent transmission to surrounding wildlife as well as spillback to humans. [ABSTRACT FROM AUTHOR]

Background: Cervical cancer is the third most common cancer among women worldwide, but particularly affects women living in sub-Saharan Africa. Screening and vaccination programs are two prevention approaches that can reduce cervical cancer incidence. However, effective vaccination campaigns require better knowledge of the prevalence of the main human papillomavirus (HPV) genotypes reported in high-grade neoplastic lesions and invasive carcinomas in women. Methods: All samples collected in this study were processed using standard histopathological methods with haematoxylin and eosin staining of the sections. Areas with abnormal cells were then identified. The HPV genotype was determined on the DNA extracted from the same sections using nested PCR followed by amplicon sequencing and real-time PCR specific to five different HPV genotypes (16, 18, 33, 45 and 58). Results: A total of 132 Gabonese patients with high-grade neoplastic lesions were included in this study; 81% were squamous cell carcinomas (SCC). At least one HPV was detected in 92.4% patients; HPV16 (75.4%) was the most frequent genotype, followed by HPV18, 58, 45, 33 and 35. Moreover, histological analysis showed that SCC samples had 50% and 58.2% stage III and IV tumor cells, respectively, according to the FIGO classification. Finally, 36.9% of these stage III and IV patients were less than 50 years old. Conclusions: Our results confirm the high prevalence of HPV16 and 18 genotypes among high-grade lesions in Gabonese women. This study confirms the need for a national strategy for early screening of precancerous lesions associated with a broad national vaccination program among non-sexually active women to significantly reduce the long-term cancer burden. [ABSTRACT FROM AUTHOR]

Magnetotactic bacteria (MTB) biomineralize intracellular magnetic nanocrystals and swim along geomagnetic field lines. While few axenic MTB cultures exist, living cells can be separated magnetically from natural environments for analysis. The bacterial universal 27F/1492R primer pair has been used widely to amplify nearly full‐length 16S rRNA genes and to provide phylogenetic portraits of MTB communities. However, incomplete coverage and amplification biases inevitably prevent detection of some phylogenetically specific or non‐abundant MTB. Here, we propose a new formulation of the upstream 390F primer that we combined with the downstream 1492R primer to specifically amplify 1100‐bp 16S rRNA gene sequences of sulfate‐reducing MTB in freshwater sediments from Lake Weiyanghu, Xi'an, northwestern China. With correlative fluorescence in situ hybridization and scanning/transmission electron microscopy, three novel MTB strains (WYHR‐2, WYHR‐3 and WYHR‐4) from the Desulfobacterota phylum were identified phylogenetically and structurally at the single‐cell level. Strain WYHR‐2 produces bullet‐shaped magnetosome magnetite, while the other two strains produce both cubic/prismatic greigite and bullet‐shaped magnetite. Our results expand knowledge of bacterial diversity and magnetosome biomineralization of sulfate‐reducing MTB. We also propose a general strategy for identifying and characterizing uncultured MTB from natural environments. [ABSTRACT FROM AUTHOR]

Liquid Silicone Rubber (LSR) belongs to the category of High Temperature Vulcanization rubbers (HTVs). Due to its implementation facility, its mechanical and thermal properties and its convenience for the medical and food industries, LSR is used in a wide range of applications. In order to examine LSR kinetic performances, thermal and rheometric experimental investigations are conducted to characterize the material and discuss the kinetic model describing crosslinking behavior. The Gel Point is investigated at different temperatures to improve our understanding of the different crosslinking steps and determine which characterization method (thermal or rheological) best represents the reaction. The results show that the LSR network undergoes specific development during crosslinking. Gel point occurs before the mechanical reaction starts. Gelation behavior resembles that of a thermosetting material despite the elastomer properties confirmed by the thermal study. Finally, the thermal method seems more reliable to describe the crosslinking kinetics of LSR. [ABSTRACT FROM AUTHOR]

Caliciviruses (Caliciviridae) and astroviruses (Astroviridae) are among the leading cause of non-bacterial foodborne disease and gastroenteritis in human. These non-enveloped RNA viruses infect a wide range of vertebrate species including rodents. Rodents are among the most important hosts of infectious diseases globally and are responsible for over 80 zoonotic pathogens that affect humans. Therefore, screening pathogens in rodents will be is necessary to prevent cross-species transmission to prevent zoonotic outbreaks. In the present study, we screened caliciviruses and astroviruses in order to describe their diversity and whether they harbor strains that can infect humans. RNA was then extracted from intestine samples of 245 rodents and retrotranscribed in cDNA to screen caliciviruses and astroviruses by PCRs. All the samples tested negative for caliciviruses and while astroviruses were detected in 18 (7.3%) samples of Rattus rattus species. Phylogenetic analyses based on the RdRp gene showed that all the sequences belonged to Mamastrovirus genus in which they were genetically related to R. rattus related AstVs previously detected in Gabon or in Rattus spp. AstV from Kenya and Asia. These findings suggested that transportation such as land and railway, as well national and international trade, are likely to facilitate spread of AstVs by the dissemination of rodents. • All Rodent were tested negative for caliciviruses. • Rattus rattus is the only species infected by astroviruses. • No rodents were infected with human astroviruses. • Transportation such as land and railway, as well national and international trade, are likely to facilitate spread of enteric viruses by the dissemination of rodents. [ABSTRACT FROM AUTHOR]

A nucleation method to form diamond on chemically pretreated silicon (111) surfaces is reported. The nucleation consisted of binding covalently 2,2-divinyladamantane molecules on the silicon substrate. Subsequently, low pressure diamond growth was performed via microwave plasma chemical vapor deposition in a tubular deposition system. The resulting diamond layers presented a good crystallinity and the Raman spectra showed a very sharp peak at 1331 cm[sup -1]. © 1998 American Institute of Physics. [ABSTRACT FROM AUTHOR]

Four indigenous cyanobacteria isolates identified as QUCCCM 34: Chroococcidiopsis sp., QUCCCM 54: Pleurocapsa sp., QUCCCM 77: Euhalothece sp., and QUCCCM 129: Cyanobacterium sp. were investigated during this study. Temperatures and salinities observed in outdoor were reproduced indoor, using small-scale photobioreactors, and culture conditions were optimized for maximum biomass and phycobiliprotein productions. The strains showed their halo and thermotolerance capacity. The highest biomass productivity was 125 ± 1.1 mg x L−1 d−1 for Pleurocapsa sp.at 30 °C–40 ppt. The major phycobiliproteins were phycocyanin, and the content was strain and age dependent. Pleurocapsa sp., Euhalothece sp., and Cyanobacterium sp reached their highest phycocyanin content (up to 160 ± 2.6 mg PC g x -1) after 4, 8, and 10 days, respectively, while it was only up to 100 ± 3.5 mg PC g x -1 for Chroococcidiopsis sp. at day 4, 40 °C–60 ppt. Increasing temperature and salinity stimulated the phycocyanin synthesis in Chroococcidiopsis sp, Pleurocapsa sp. and Euhalothece sp., whereas only salinity increment enhanced the pigments production(both phycoerythrin and phycocyanin) for Cyanobacterium sp. Finally, all the pigment extracts exhibited an antioxidant and radical scavenging activity which were maximal for the extracts from Pleurocapsa sp., with ≈ 60 mM Trolox equivalent g x −1 and 50%, respectively. [Display omitted] • Novel cyanobacteria isolates were studied for their thermotolerant and halotolerant ability. • Temperature and salinity affected the growth kinetics with highest biomass productivity of 125 ± 1.1 mg x L−1 d−1 for Pleurocapsa sp. • The major phycobiliproteins were Phycocyanin (up to 16 %.), and the content was strain and age dependent. • Pigment extracts exhibited remarkable antioxidant ability higher than those reported for Spirulina sp. [ABSTRACT FROM AUTHOR]

The formation of gas hydrates is a major issue during the operation of oil and gas pipelines, because gas hydrates cause plugging, thereby disrupting the normal oil and gas flows. A solution is to inject gas hydrate inhibitors such as ionic liquids. Contrary to classical inhibitors, ionic liquids act both as thermodynamic inhibitors and hydrate inhibitors, and as anti-agglomerates. Imidazolium-based ionic liquids have been found efficient for the inhibition of CO2 and CH4 hydrates. For CO2 gas hydrates, N-ethyl-N-methylmorpholinium bromide showed an average depression temperature of 1.72 K at 10 wt% concentration. The induction time of 1-ethyl-3-methyl imidazolium bromide is 36.3 h for CO2 hydrates at 1 wt% concentration. For CH4 hydrates, 1-ethyl-3-methyl-imidazolium chloride showed average depression temperature of 4.80 K at 40 wt%. For mixed gas hydrates of CO2 and CH4, only quaternary ammonium salts have been studied. Tetramethyl ammonium hydroxide shifted the hydrate liquid vapour equilibrium to 1.56 K at 10 wt%, while tetrabutylammonium hydroxide showed an induction time of 0.74 h at 1 wt% concentration. [ABSTRACT FROM AUTHOR]

Highlights: [•] Laboratory experiments were performed on a glass simulating archeological artifacts. [•] Experimental conditions reproduced in situ anoxic and clay-type environment. [•] The effects of siderite and metal iron on glass leaching were investigated. [•] Siderite led to a moderate and transient effect limited by silica sorption. [•] With metal iron, glass corrosion is durably sustained by the precipitation of Fe-silicates. [ABSTRACT FROM AUTHOR]

The incorporation of plasmonic nanoconstructs in biodegradable polymeric nanoparticles (NPs), together with therapeutic drugs in a controlled procedure is of interest for different applications in Nanomedicine. Advanced hybrid nanomaterials can be engineered by combining the in situ formation of plasmonic palladium nanosheets (NSs) and the proper ionic nature of the encapsulated drug. This study presents a new procedure to synthesize hybrid nanostructures by a Pickering double emulsion. Anisotropic palladium (Pd) NSs with unique near‐infrared (NIR)‐optical properties can be assembled within a poly lactic‐co‐glycolic acid matrix of < 200 nm NPs, when Pd precursors are in situ reduced via a gas‐phase procedure. The hybrid nanomaterials respond to external NIR light stimulus. The unprecedented precision to assemble, in a single stage, plasmonic nanoconstructs having a total loading selectivity, when encapsulated in combination with hydrophobic drugs, offers new opportunities in the new class of theragnostics, in particular when triggered drug delivery and photothermal therapies are required. [ABSTRACT FROM AUTHOR]

A method for image analysis was implemented to determine the edge pixels of two biopolymer-based thermoplastic filaments during their hot melt isothermal sintering at 120 °C. Successive inverted ellipses are adjusted to the contour of the sintered filaments and lead to the identification of the parameters of the corresponding lemniscates of Booth. The different steps of the morphological image analysis are detailed, from 8-bit coded acquired images (1 frame/s), to the final fitting of the optimized mathematical functions describing the evolution of the filaments envelope. The complete sequence is composed of an initial pure viscous sintering step during the first minute, followed by viscoelastic swelling combined with melt spreading for a longer time, and then the stabilization of the sintered filaments shape for over 2 min at high temperatures. Using a master curve obtained from Hopper's abacus, the characteristic viscous sintering time is assessed at tvs = 78 s, confirming the one previously found based on the measurement of the bonding neck length alone. Then, the full description of the evolution of the thermoplastic filaments envelope is assessable by image analysis during sintering trials as a result of its digital modeling as successive lemniscates of Booth, reflecting geometry changes in the molten state. [ABSTRACT FROM AUTHOR]

Abstract: The present work focuses on the fire retarding behaviour of (ethylene–vinyl acetate (EVA) copolymer/magnesium hydroxide (MH)/talc) composites. Talc particles of different lamellarity and specific surface area have been tested, leading to the conclusion that for highly lamellar talc particles, the fire retarding behaviour becomes similar to that of (EVA/MH/organomodified montmorillonite (oMMT)) composites, with a significant intumescence. This intumescence, which occurs during the pre-ignition period in cone calorimeter tests, seems to be related to three phenomena caused by the presence of the lamellar particles (oMMT or talc): heterogeneous bubble nucleation, increased viscosity and charring promotion. [Copyright &y& Elsevier]

Although there are several reports in the literature of SARS‐CoV‐2 infection in cats, few SARS‐CoV‐2 sequences from infected cats have been published. In this study, SARS‐CoV‐2 infection was evaluated in two cats by clinical observation, molecular biology (qPCR and NGS), and serology (microsphere immunoassay and seroneutralization). Following the observation of symptomatic SARS‐CoV‐2 infection in two cats, infection status was confirmed by RT‐qPCR and, in one cat, serological analysis for antibodies against N‐protein and S‐protein, as well as neutralizing antibodies. Comparative analysis of five SARS‐CoV‐2 sequence fragments obtained from one of the cats showed that this infection was not with one of the three recently emerged variants of SARS‐CoV‐2. This study provides additional information on the clinical, molecular, and serological aspects of SARS‐CoV‐2 infection in cats. This study provides additional information on the clinical, molecular, and serological aspects of SARS‐CoV‐2 infection in cats. [ABSTRACT FROM AUTHOR]

The catalytic subunit of glutamylcysteine ligase (GCLC) primarily regulates de novo synthesis of glutathione (GSH) in mammalian cells and is central to the antioxidant capacity of the cell. However, GCLC expression in pancreatic islets has not been previously examined. We designed experiments to ascertain whether GCLC is normally expressed in islets and whether it is up-regulated by interleukin-lβ (IL-1β). GCLC expression levels were intermediate compared with other met- abolic tissues (kidney, liver, muscle, fat, and lung). IL-1β up-regulated GCLC expression (10 ng/ml IL-1β, 3.76 ± 0.86; 100 ng/ml IL-lβ, 4.22 ± 0.68-fold control) via the p38 form of mitogen-activated protein kinase and NFκB and also increased reactive oxygen species levels (10 ng/ml IL-1β, 5.41 ± 1.8-fold control). This was accompanied by an increase in intraislet GSH/GSSG ratio (control, 7.1 ± 0.1; 10 ng/ml IL-1β, 8.0 ± 0.5; 100 ng/ml IL-1β, 8.2 ± 0.5- fold control; p < 0.05). To determine whether overex- pression of GCLC increases the antioxidant capacity of the islet and prevents the adverse effects of IL-1β on glucose-induced insulin secretion, islets were infected with an adenovirus encoding GCLC. IL-1β significantly decreased glucose-stimulated insulin secretion (control, 123.8 ± 17.7; IL-1β, 40.2 ± 3.9 microunits/ml insulin/islet). GCLC overexpression increased intraislet GSH levels and partially prevented the decrease in glucose-stimulated insulin secretion caused by IL-1β. These data provide the first report of GCLC expression in the islet and demonstrate that adenoviral overexpression of GCLC increases intracellular GSH levels and protects the beta cell from the adverse effects of IL-1β. [ABSTRACT FROM AUTHOR]

D-Glyceraldehyde (D-GLYC) is usually considered to be a stimulator of insulin secretion but theoretically can also form reactive oxygen species (ROS), which can inhibit beta cell function. We examined the time- and concentration-dependent effects of D-GLYC on insulin secretion, insulin content, and formation of ROS. We observed that a 2-h exposure to 0.05–2 mM D-GLYC potentiated glucose-stimulated insulin secretion (GSIS) in isolated Wistar rat islets but that higher concentrations inhibited GSIS. A 24-h exposure to 2 mM D-GLYC inhibited GSIS, decreased insulin content, and increased intracellular peroxide levels (2.14 ± 0.31-fold increase, n = 4, p < 0.05). N-Acetylcysteine (10 ms) prevented the increase in intracellular peroxides and the adverse effects of D-GLYC on GSIS. In the presence of 11.1 but not 3.0 mM glucose, koningic acid (10 μM), a specific glyceraldehyde-3-phosphate dehydrogenase inhibitor, increased intracellular peroxide levels (1.88 ± 0.30-fold increase, n = 9, p < 0.01) and inhibited GSIS (control GSIS = p < 0.001; koningic acid GSIS, not significant). To determine whether oxidative phosphorylation was the source of ROS formation, we cultured rat islets with mitochondrial inhibitors. Neither rotenone or myxothiazol prevented D-GLYC-induced increases in islet ROS. Adenoviral overexpression of manganese superoxide dismutase also failed to prevent the effect of D-GLYC to increase ROS levels. These observations indicate that exposure to excess D-GLYC increases reactive oxygen species in the islet via non-mitochondrial pathways and suggest the hypothesis that the oxidative stress associated with elevated D-GLYC levels could be a mechanism for glucose toxicity in beta cells exposed chronically to high glucose concentrations. [ABSTRACT FROM AUTHOR]