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Carbapenems are a class of beta-lactam antibiotics with broad spectrum of activity. They are often considered as a last resort in treatment of infections caused by multidrug resistant organisms. Carbapenemase-producing Enterobacteriaceae (CPE) have been reported worldwide. Class D OXA-48 carbapenemases is rapidly disseminating in Enterobacteriaceae leading to high mortality from resistant and invasive CPE infections. In the present study, we attempted to isolate OXA-48 carbapenemase-producing Enterobacteriaceae from different clinical specimens obtained from hospitalized patients at different ICU of kasr Kasr Al-Ainy hospital, Cairo University. Initial screening for carbapenemase-producing Enterobacteriaceae was done using ertapenem disc diffusion method and direct inoculation of the specimens into ChromID OXA-48. The phenotypic Modified Hodge Test (MHT) was used for confirmation of carbapenemse production among screened carbapenem resistant isolates.Out of 112 collected samples, 94 Enterobacteriaceae were isolated. Fifty five isolates (58.5%) were ertapenem disc resistant and 50 isolates (53%) showed positive growth on ChromID OXA-48. Fifty two (94.5%) out of 55 suspected carbapenemase-producing isolates by disc diffusion method and the 50 isolates (100%) grown on ChromID OXA-48 were MHT positive. Our study underlines the need to detect OXA-48 CPE as early as possible to minimize its spread in ICU and apply appropriate infection control measures.

Carbapenems are a class of beta-lactam antibiotics with broad spectrum of activity. They are often considered as a last resort in treatment of infections caused by multidrug resistant organisms. Carbapenemase-producing Enterobacteriaceae (CPE) have been reported worldwide. Resistance to carbapenems in Enterobacteriaceae is caused mainly by carbapenemase production or by porin loss combined with the expression of b-lactamases like extended-spectrum beta-lactamases (ESBL) or AmpC b-lactamase. Class D OXA-48 carbapenemases is one of the most prevalent carbapenemases in Enterobacteriaceae. In the present study, we attempted to isolate carbapenemase-producing Enterobacteriaceae from different clinical specimens obtained from hospitalized patients at different ICU of kasr Al-Ainy hospital. Initial screening for carbapenemase-producing Enterobacteriaceae was done using ertapenem disc diffusion method and direct inoculation of the specimens into ChromID OXA-48. The phenotypic Modified Hodge Test (MHT) was used for confirmation of carbapenemse production among screened carbapenem resistant isolates.Out of 112 collected samples, 94 Enterobacteriaceae were isolated. Fifty five isolates (58.5%) were ertapenem disc resistant and 50 isolates (53%) showed positive growth on ChromID OXA-48. Fifty two (94.5%) out of 55 suspected carbapenemase-producing isolates by disc diffusion method and the 50 isolates (100%) grown on ChromID OXA-48 were MHT positive. [ABSTRACT FROM AUTHOR]

En las explotaciones de Litio es de suma relevancia modelar la temperatura ambiental denominada también temperatura cinética (Chuvieco, 2010) (Jensen, 1996), debido a que esta permite establecer un plan de manejo para la explotación de los salares. El presente estudio se realizo en el Salar de Susques, Provincia de Jujuy, República de Argentina, el sector se contaba con estaciones de la red meteorológica de la República de Argentina y empresas mineras existentes en el área en estudio. En los estudios de modelación de temperatura cinética se menciona la fuerte relación entre los procesos térmicos reales e ideales con respecto a presión y volumen (Bristow, K.L. y Campbell, G.S., 1984)( Ravelo, A. y R. Zanve"or, 1992) (Richardson, C.W., 1981), en la atmosfera esto se traducen en interrelaciones entre la humedad relativa, rapidez del viento, presión y radiación solar entre otros. Debido a lo anterior se procedió a aplicar un procedimiento de análisis de datos que consta de cuatro etapas, en la primera etapa se modela teóricamente la variable en estudio, en una segunda etapa se estudia gráficamente las relaciones entre las formas armónicas genéricas de los datos teóricos y reales, en la tercera etapa se ajusta los datos a través de técnicas auto regresión entre variables generadas por modelación de datos (ARIMA-Modelo Auto Regresivo Inte grado de Media Móvil) y en tiempos variables de pronostico futuro (ARMA-Modelo Auto Regresivo de Media Móvil) , en su cuarta etapa se ejecuta un análisis grafico de dispersión, contraste de series y comentario se sensibilidad (Step simplificado), obteniendo finalmente una ecuación de modelación del tipo: ... La cual es particular al mes en estudio y es perfectible en su entrada de datos. [ABSTRACT FROM AUTHOR]

SiCN polymer-derived ceramics (PDCs) with different carboncontents have been synthesized by pyrolysis of poly(phenylvinylsilylcarbodiimide)and of poly(phenylsilsesquicarbodiimide), and their structure andenergetics have been studied using 29Si, 13C, 15N, and 1H solid state nuclear magnetic resonance(NMR) spectroscopy and oxide melt solution calorimetry. The structureof these PDCs at lower carbon content (35–40 wt %) and pyrolysistemperatures (800 °C) consists primarily of amorphous nanodomainsof sp2carbon and silicon nitride with an interfacial regioncharacterized by mixed bonding between N, C, and Si atoms that islikely stabilized by the presence of hydrogen. The average size ofthe carbon domains increases with increasing carbon content, and acontinuously connected amorphous carbon matrix is formed in PDCs with55–60 wt % C. The interfacial silicon–carbon and nitrogen–carbonbonds are destroyed with concomitant hydrogen loss upon increasingthe pyrolysis temperature to 1100 °C. Calorimetry results demonstratethat the mixed bonding between C, N, and Si atoms in the interfacialregions play a key role in the thermodynamic stabilization of thesePDC. They become energetically less stable with increasing annealingtemperature and concomitant decrease of mixed bonds and hydrogen loss. [ABSTRACT FROM AUTHOR]

A novel oxidation resistant SiC/B4 C/C nanocomposite was prepared by the pyrolysis of carborane-containing poly(silyleneethynylenephenyleneethynylene) ( CB- PSEPE) at 1450°C in argon. The phase composition and microstructure of the carbon-rich ceramic were investigated by X-ray diffraction, Raman spectroscopy and transmission electron microscopy. The β- SiC (~12 nm) and B4 C (~20 nm) nanocrystalline phases were formed during the pyrolysis process of CB- PSEPE. The presence of boron in CB- PSEPE promotes the growth of β- SiC nanocrystals. The ceramic shows excellent thermooxidative stability based on thermogravimetric analysis in air. A borosilicate layer was formed on the surface of the ceramic after oxidation. This carborane-containing conjugated polycarbosilane could be a potential precursor for oxidation resistant carbon-based materials. [ABSTRACT FROM AUTHOR]

Silicon oxycarbides synthesized through a conventional polymeric route show characteristic nanodomains that consist of sp 2 hybridized carbon, tetrahedrally coordinated SiO 4, and tetrahedrally coordinated silicon with carbon substitution for oxygen, called "mixed bonds." Here we synthesize two preceramic polymers possessing both phenyl substituents as unique organic groups. In one precursor, the phenyl group is directly bonded to silicon, resulting in a SiOC polymer-derived ceramic (PDC) with mixed bonding. In the other precursor, the phenyl group is bonded to the silicon through Si-O-C bridges, which results in a SiOC PDC without mixed bonding. Radial breathing-like mode bands in the Raman spectra reveal that SiOC PDCs contain carbon nanoscrolls with spiral-like rolled-up geometry and open edges at the ends of their structure. Calorimetric measurements of the heat of dissolution in a molten salt solvent show that the SiOC PDCs with mixed bonding have negative enthalpies of formation with respect to crystalline components (silicon carbide, cristobalite, and graphite) and are more thermodynamically stable than those without. The heats of formation from crystalline SiO 2 , SiC, and C of SiOC PDCs without mixed bonding are close to zero and depend on the pyrolysis temperature. Solid state MAS NMR confirms the presence or absence of mixed bonding and further shows that, without mixed bonding, terminal hydroxyls are bound to some of the Si-O tetrahedra. This study indicates that mixed bonding, along with additional factors, such as the presence of terminal hydroxyl groups, contributes to the thermodynamic stability of SiOC PDCs.

The bulk chlorine decay rate in drinking water supply systems depend on many factors, including temperature. In this document, the method to determine the order of reaction of chlorine with water is reported, as well as the method to estimate Kb (Bulk reaction rate constant). Experiments were carried out to determine the bulk chlorine decay, for which a set of water samples to determine the free residual chlorine every hour were analyzed. Chlorine concentrations were graphed against time and adjusted appropriately to the developed model. The experimental results showed that the average value of the mass decomposition rate was 0.15 h -1 . It was shown that temperature affects the variation of the reaction rate of chlorine with water, Kb increases as temperature increases. In this manuscript it is reported:•The method that allows determining the reaction kinetic order of chlorine with drinking water.•The method that can help residual chlorine modelers in the correct definition of the bulk reaction rate constant.•The effectiveness of the method for evaluating the decomposition of residual chlorine in drinking water distribution networks as a function of temperature., Competing Interests: The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (© 2020 The Author(s). Published by Elsevier B.V.)

Herein we report the synthesis of novel 0D-nanocarbon-based silicon-containing ceramic composites by a facile salt-free synthesis method followed by polymer-to-ceramic transformation. 0D-nanocarbon-silica composites were synthesized via a one-pot sol-gel process using tetramethyl orthosilicate (TMOS) and functionalized nanodiamonds and converted subsequently via pyrolysis under an argon atmosphere into nanodiamond/silica nanocomposites. The thermal conversion of the nanodiamond phase to a multilayer fullerene phase was carefully investigated by integral and local characterization methods such as vibrational spectroscopy, X-ray diffraction, BET, SEM and HRTEM. The incorporation of nanodiamonds in a silica matrix enhances the crystallization temperature of the silica phase, as α-cristobalite, to 1500 °C, while their full graphitization is shifted to T > 1700 °C under an argon atmosphere. The thermal decomposition of the nanodiamond/silica composites leads to the formation of materials with a high specific surface area (up to 562 m 2 g -1 ) and a mesoporous structure. No carbothermal reaction of composing phases was identified. The results obtained in the present study allow for designing advanced and highly-defined mesoporous 0D-nanocarbon-containing composites with tailored structural features and multifunctional property profiles.

The present study introduces a facile single-source precursor preparative access to bamboo-like multiwalled carbon nanotubes (MWCNTs) highly dispersed within a mesoporous silica-rich matrix. The metal-free single-source precursor was synthesized via a one-pot sol-gel process using tetramethyl orthosilicate (TMOS) and 4,4'-dihydroxybiphenyl (DHBP) and converted subsequently via pyrolysis under an argon atmosphere into MWCNT/silica nanocomposites. The in situ segregation of the highly defective bamboo-like MWCNTs was carefully investigated and has been shown to occur within the mesopores of the silica-rich matrix at relatively low temperatures and without the use of a metal catalyst. The experimental results have been supported by extensive computational simulations, which correlate the molecular architecture of the single-source precursor with the structural features of the carbon phase segregating from the silica matrix. Furthermore, the role of hydrogen in the stability of the prepared nanocomposites as well as in the high-temperature evolution and morphology of the segregated MWCNTs has been discussed based on vibrational spectroscopy, calorimetric studies and empirical potential calculations. The results obtained within the present study may allow for designing highly-defined nanocarbon-containing composites with tailored structural features and property profiles.

The present Review addresses current developments related to polymer-derived ceramic nanocomposites (PDC-NCs). Different classes of preceramic polymers are briefly introduced and their conversion into ceramic materials with adjustable phase compositions and microstructures is presented. Emphasis is set on discussing the intimate relationship between the chemistry and structural architecture of the precursor and the structural features and properties of the resulting ceramic nanocomposites. Various structural and functional properties of silicon-containing ceramic nanocomposites as well as different preparative strategies to achieve nano-scaled PDC-NC-based ordered structures are highlighted, based on selected ceramic nanocomposite systems. Furthermore, prospective applications of the PDC-NCs such as high-temperature stable materials for thermal protection systems, membranes for hot gas separation purposes, materials for heterogeneous catalysis, nano-confinement materials for hydrogen storage applications as well as anode materials for secondary ion batteries are introduced and discussed in detail.

Burnout is scientifically a work related syndrome which consists of three dimensions: emotional exhaustion, depersonalization and reduced professional efficacy. Different instruments for the diagnosis of burnout exist, accompanied by many associated problems, however. This paper describes a proposal aiming at supporting the diagnosis of burnout using measures complementary to the Maslach Burnout Inventory (MBI). It specifically focuses on emotions detection to provide useful information that contributes to the decision making process about the syndrome.

Amorphous silicon oxycarbide polymer-derived ceramics (PDCs), synthesized from organometallic precursors, contain carbon- and silica-rich nanodomains, the latter with extensive substitution of carbon for oxygen, linking Si-centered SiO(x)C(4-x) tetrahedra. Calorimetric studies demonstrated these PDCs to be thermodynamically more stable than a mixture of SiO2, C, and silicon carbide. Here, we show by multinuclear NMR spectroscopy that substitution of C for O is also attained in PDCs with depolymerized silica-rich domains containing lithium, associated with SiO(x)C(4-x) tetrahedra with nonbridging oxygen. We suggest that significant (several percent) substitution of C for O could occur in more complex geological silicate melts/glasses in contact with graphite at moderate pressure and high temperature and may be thermodynamically far more accessible than C for Si substitution. Carbon incorporation will change the local structure and may affect physical properties, such as viscosity. Analogous carbon substitution at grain boundaries, at defect sites, or as equilibrium states in nominally acarbonaceous crystalline silicates, even if present at levels at 10-100 ppm, might form an extensive and hitherto hidden reservoir of carbon in the lower crust and mantle.

Bulk B-C-N materials were synthesized under static high thermobaric conditions (20 GPa and 2,000 °C) in a multianvil apparatus from a polymer derived t-BC 1.97 N ceramic. The bulk samples were characterised using X-ray synchrotron radiation and analytical transmission electron microscopy in combination with electron energy loss spectroscopy. Polycrystalline B-C-N materials with a cubic type structure were formed under the applied reaction conditions, but the formation of a ternary cubic diamond-like c-BC₂N compound, could not be unambiguously confirmed.

The preparation of a series of 3-hydrazinocycloalkyl[1,2-c]pyridazines 7 and some derivatives as hydrazones 8, 9, triazoles 10 and pyrroles 11 are described together with their hypotensive activity in normotensive rats.

A series of 5-(4-substituted piperazin-1-yl)-2-nitroanilines (4) and 5-(4-substituted piperazin-1-yl)benzimidazole-2-carbamates (6) has been synthesized starting from 5-chloro-2-nitroaniline (3) and N-monosubstituted piperazines. Catalytic reduction of 4 with Pd/C followed by treatment with 1,3-dicarbomethoxy-S-methylisothiourea yielded the corresponding methyl-5-(4-substituted piperazin-1-yl)benzimidazole-2-carbamates (6) which were for anthelmintic activity against experimental infections of Trichinella spiralis.