2-(Phenyl­carbonothio­ylsulfan­yl)acetic acid

The title compound, C9H8O2S2, can be used as a chain transfer agent and may be used to control the behavior of polymerization reactions. O—H⋯O hydrogen bonds of moderate character link the mol­ecules into dimers. In the crystal, the dimers are linked into sheets by C—H⋯O inter­actions, forming R 4 2(12) and R 2 2(8) edge-fused rings running parallel to [101]. There are no inter­molecular inter­actions involving the S atoms

In vitro and in vivo comparison of the anti-staphylococcal efficacy of generic products and the innovator of oxacillin

<p>Abstract</p> <p>Background</p> <p>Oxacillin continues to be an important agent in the treatment of staphylococcal infections; many generic products are available and the only requirement for their approval is demonstration of pharmaceutical equivalence. We tested the assumption that pharmaceutical equivalence predicts therapeutic equivalence by comparing 11 generics with the innovator product in terms of concentration of the active pharmaceutical ingredient (API), minimal inhibitory (MIC) and bactericidal concentrations (MBC), and antibacterial efficacy in the neutropenic mouse thigh infection model.</p> <p>Methods</p> <p>The API in each product was measured by a validated microbiological assay and compared by slope (potency) and intercept (concentration) analysis of linear regressions. MIC and MBC were determined by broth microdilution according to Clinical and Laboratory Standard Institute (CLSI) guidelines. For in vivo efficacy, neutropenic ICR mice were inoculated with a clinical strain of <it>Staphylococcus aureus</it>. The animals had 4.14 ± 0.18 log₁₀CFU/thigh when treatment started. Groups of 10 mice per product received a total dose ranging from 2.93 to 750 mg/kg per day administered q1h. Sigmoidal dose-response curves were generated by nonlinear regression fitted to Hill equation to compute maximum effect (E_max), slope (N), and the effective dose reaching 50% of the E_max(ED₅₀). Based on these results, bacteriostatic dose (BD) and dose needed to kill the first log of bacteria (1LKD) were also determined.</p> <p>Results</p> <p>4 generic products failed pharmaceutical equivalence due to significant differences in potency; however, all products were undistinguishable from the innovator in terms of MIC and MBC. Independently of their status with respect to pharmaceutical equivalence or in vitro activity, all generics failed therapeutic equivalence in vivo, displaying significantly lower E_maxand requiring greater BD and 1LKD, or fitting to a non-sigmoidal model.</p> <p>Conclusions</p> <p>Pharmaceutical or in vitro equivalence did not entail therapeutic equivalence for oxacillin generic products, indicating that criteria for approval deserve review to include evaluation of in vivo efficacy.</p

Material assimilation in a shallow diapiric forceful intrusion: evidence from microstructures and csd analysis in a porphyritic intrusive body, “la línea” tunnel, central cordillera, colombia

The contact between the unit Porphyry Andesite and the Cajamarca Group is observed in the "Túnel de la Linea" section. The integration of petrographic, geochemical and textural (crystal size distribution, CSD) analysis allows description of physical and chemical processes that took place in the contact zone in order to propose a model for the intrusion. Material assimilation produced quartz enrichment towards pluton's boundaries associated to a simple process of melt injection. The difference between host rock and hot melt rheologies causedshear stress that produced crystal breaking, folding and foliation rotation

A comparison of robust Kalman filtering methods for artifact correction in heart rate variability analysis

La variabilidad de la frecuencia cardiaca (HRV) ha recibido una atención considerable por mucho años, ya que esta proporciona un valor cuantitativo para examinar el ritmo sinusal modulado para el sistema nervioso autónomo (SNA). El SNA juega un papel importante en campos clínicos y fisiológicos. El análisis de la HRV se puede realizar calculando varias medidas tanto en el domino del tiempo como en la frecuencia. Sin embargo, el cálculo de estas medidas se puede ver afectado por la presencia de artefactos o latidos ectópicos en registros de electrocardiogramas (ECG). Esto es particularmente cierto para registros ECG desde un monitor Holter. El objetivo de este trabajo fue estudiar el rendimiento de varios filtros de Kalman robustos para la corrección de artefactos. Para nuestros experimentos, se usaron dos bases de datos reales: el primer conjunto de datos incluye 10 series de tiempo de intervalos RR a partir de un generador de series de tiempo de intervalos RR realista. La segunda base de datos contiene 10 conjuntos de series de intervalos RR de cinco pacientes sanos y cinco pacientes que sufren una insuficiencia cardiaca congestiva. Se calculó la desviación estándar de los intervalos RR a partir de las señales filtradas. Los resultados se compararon con un reconocido software de procesamiento, mostrando comportamientos y valores similares. Adicionalmente, los métodos propuestos ofrecen resultados satisfactorios en comparación con el filtro de Kalman estándar.Heart rate variability (HRV) has received considerable attention for many years, since it provides a quantitative marker for examining the sinus rhythm modulated by the autonomic nervous system (ANS). The ANS plays an important role in clinical and physiological fields. HRV analysis can be performed by computing several time and frequency domain measurements. However, the computation of such measurements can be affected by the presence of artifacts or ectopic beats in the electrocardiogram (ECG) recording. This is particularly true for ECG recordings from Holter monitors. The aim of this work was to study the performance of several robust Kalman filters for artifact correction in Inter-beat (RR) interval time series. For our experiments, two data sets were used: the first data set included 10 RR interval time series from a realistic RR interval time series generator. The second database contains 10 sets of RR interval series from five healthy patients and five patients suffering from congestive heart failure. The standard deviation of the RR interval was computed over the filtered signals. Results were compared with a state of the art processing software, showing similar values and behavior. In addition, the proposed methods offer satisfactory results in contrast to standard Kalman filtering

MAGMATIC PROCESSES IN THE NEVADO DEL RUIZ VOLCANO: AQUANTITATIVE TEXTURAL ANALYSIS

A partir del análisis petrográfico detallado de flujos de lava del Volcán Nevado del Ruiz (VNR), incluyendo la determinación de la asociación mineral estable y microestructuras, análisis geoquímicos y análisis texturales cuantitativos de distribución de tamaños de cristales (CSD) de plagioclasas, se restringen las interpretaciones de los procesos magmáticos que han ocurrido en este volcán durante los últimos 1,8 Ma. El VNR es uno de los estratovolcanes activos más septentrionales de la Cordillera Central Colombiana, muestra un comportamiento típico de un volcán de zona de subducción con afinidad calco-alcalina, su comportamiento durante el Pleistoceno estuvo dominado por un período eruptivo de tipo efusivo con productos volcánicos de composición monótona, principalmente andesíticos a dacíticos. En este trabajo se analizaron lavas andesíticas y dacíticas con dos piroxenos ± oxihornblenda ± biotita,con microestructuras porfiriticas y glomeroporfiríticas. Las plagioclasas muestran microestructuras de sobrecrecimiento, reabsorción y zonación oscilatoria. Se observan dos poblaciones de cristales de plagioclasa:una con microestructuras en tamiz en su núcleo y otra compuesta por cristales limpios. Las curvas de CSD enplagioclasas muestran patrones de distribución curvilíneos y cóncavos, similares en todas las unidades, con excepción de las lavas de domos que exhiben un patrón lineal. Los piroxenos desarrollan texturas poiquilíticas y de reabsorción y los anfíboles muestran bordes de reacción. Estas características permiten inferir cambios abruptos en la composición del fundido durante el proceso de cristalización, probablemente relacionados conprocesos de mezcla de magmas. Palabras Clave: CSD, Cordillera Central Colombiana, Petrografía, Volcán Nevado del Ruiz. &nbsp; &nbsp;A detailed petrographic analysis of lava flows of the Nevado del Ruiz Volcano (VNR), including determination of mineral assemblages and microstructures, geochemical analysis and a crystal size distribution (CSD) quantitative textural analysis in plagioclases, helps to constrain interpretations of magmatic processes occurringin this volcano during the last 1,8 Ma. The VNR is one of the northern most active strato volcanoes in the Colombian Central Cordillera and displays a typical behavior of a subduction zone volcano with calc-alkaline affinity. This volcano had an eruptive period dominated by effusive behavior during the Pleistocene and itsproducts show a monotonous bulk composition, mainly andesitic to dacitic. Samples analyzed in this work are two-pyroxene andesites ± oxyhornblende ± biotite, with porphyritic and glomeroporphyritic microstructures. Plagioclase displays overgrow and resorption microstructures and crystaloscillatory zoning patterns. There are two plagioclase populations: one with crystals showing finely sievedinteriors and clean rims, the other is a population of clean plagioclase crystals lacking any sieved microstructures.The CSD curves show patterns of curvilinear and concave distributions, similar for all samples, with theexception of the lava domes, that show a linear pattern. Pyroxene has poikilitic and resorption microstructures(coarse cellular microstructures) and amphibole shows reaction rims. These characteristics allow to infer abruptchanges in melt composition during the crystallization process probably related with magma mixing processes. Keywords: Crystal Size Distribution, Colombian Central Cordillera, Nevado del Ruiz Volcano, Igneous Petrolog

Archean continental crust formed by magma hybridization and voluminous partial melting

Archean (4.0–2.5 Ga) tonalite–trondhjemite–granodiorite (TTG) terranes represent fragments of Earth’s first continents that formed via high-grade metamorphism and partial melting of hydrated basaltic crust. While a range of geodynamic regimes can explain the production of TTG magmas, the processes by which they separated from their source and acquired distinctive geochemical signatures remain uncertain. This limits our understanding of how the continental crust internally differentiates, which in turn controls its potential for long-term stabilization as cratonic nuclei. Here, we show via petrological modeling that hydrous Archean mafic crust metamorphosed in a non-plate tectonic regime produces individual pulses of magma with major-, minor-, and trace-element signatures resembling—but not always matching—natural Archean TTGs. Critically, magma hybridization due to co-mingling and accumulation of multiple melt fractions during ascent through the overlying crust eliminates geochemical discrepancies identified when assuming that TTGs formed via crystallization of discrete melt pulses. We posit that much Archean continental crust is made of hybrid magmas that represent up to ~ 40 vol% of partial melts produced along thermal gradients of 50–100 °C/kbar, characteristic of overthickened mafic Archean crust at the head of a mantle plume, crustal overturns, or lithospheric peels

MACUIRA GNEISS: TECTONIC EVOLUTION OF THE PALEOZOIC METAMORPHIC ROCKS, ALTA GUAJIRA – COLOMBIA

El Neis de Macuira es una unidad metamórfica Paleozoica que aflora en las serranías de Simarua, Jarara y Macuira, Alta Guajira. Se trata de un conjunto litológico que sufrió metamorfismo bajo condiciones de P-T en la facies anfibolita y consta de neises anfibólicos y cuarzo-feldespáticos, anfibolitas, esquistos, pegmatitas, rocas calco-silicáticas y mármoles, con evidencias de migmatización en neises y anfibolitas. En la unidad se observan cinco foliaciones (S1-5) y tres eventos de plegamiento (F1-3) interpretados como producto de dos eventos metamórficos desarrollados en un gradiente metamórfico barroviano progresivo con relaciones P-T intermedias, y relacionados con tectónica de colisión continental. La unidad es importante en el entendimiento de la evolución tectónica de la Alta Guajira y el Caribe debido a que registra diferentes fases deformativas pre-, sin- y post-migmatíticas que podrían relacionarse con diferentes episodios tectónicos: el primero relacionado con la colisión de Laurasia y Gondwana (Orogenia Alleghaniana - Paleozoico Tardío) y el segundo relacionado con la evolución de la Placa Caribe (Orogenia Andina - Meso a Cenozoico). Palabras clave: Migmatitas, Deformación, Orogenia Alleghaniana, Alta Guajira, ColombiaThe Macuira Gneiss is a Paleozoic metamorphic unit that outcrops in the Simarua, Jarara and Macuira ranges, Alta Guajira. It is composed by a lithologies metamorphosed under amphibolite facies P-T conditions and consist of amphibolitic and quartz feldspathic gneisses, amphibolites, schists, pegmatites, calc-silicated rocks and marbles, with migmatization evidences in gneisses and amphibolites. Five foliations (S1-5) and three folding events (F1-3) were identified and interpreted as product of two metamorphic events, developed in a progressive barrovian metamorphic gradient of intermediate pressure with intermediate P-T ratio, interpreted as product of continental collision tectonics. This unit is important in understanding of the tectonic evolution of the Alta Guajira and Caribbean because it records different deformational phases pre-, syn- and post-migmatitic, that could be related with different tectonic episodes: the first associated with the collision between Laurasia and Gondwana (Alleghanian Orogeny - Late Paleozoic), and the second related with the Caribbean Plate evolution (Andean Orogeny - Meso-Cenozoic). Keywords: Migmatites, Deformation, Alleghanian orogeny, Alta Guajira, Colombia. &nbsp

MACUIRA GNEISS: TECTONIC EVOLUTION OF THE PALEOZOIC METAMORPHIC ROCKS, ALTA GUAJIRA – COLOMBIA

El Neis de Macuira es una unidad metamórfica Paleozoica que aflora en las serranías de Simarua, Jarara y Macuira, Alta Guajira. Se trata de un conjunto litológico que sufrió metamorfismo bajo condiciones de P-T en la facies anfibolita y consta de neises anfibólicos y cuarzo-feldespáticos, anfibolitas, esquistos, pegmatitas, rocas calco-silicáticas y mármoles, con evidencias de migmatización en neises y anfibolitas. En la unidad se observan cinco foliaciones (S1-5) y tres eventos de plegamiento (F1-3) interpretados como producto de dos eventos metamórficos desarrollados en un gradiente metamórfico barroviano progresivo con relaciones P-T intermedias, y relacionados con tectónica de colisión continental. La unidad es importante en el entendimiento de la evolución tectónica de la Alta Guajira y el Caribe debido a que registra diferentes fases deformativas pre-, sin- y post-migmatíticas que podrían relacionarse con diferentes episodios tectónicos: el primero relacionado con la colisión de Laurasia y Gondwana (Orogenia Alleghaniana - Paleozoico Tardío) y el segundo relacionado con la evolución de la Placa Caribe (Orogenia Andina - Meso a Cenozoico). Palabras clave: Migmatitas, Deformación, Orogenia Alleghaniana, Alta Guajira, ColombiaThe Macuira Gneiss is a Paleozoic metamorphic unit that outcrops in the Simarua, Jarara and Macuira ranges, Alta Guajira. It is composed by a lithologies metamorphosed under amphibolite facies P-T conditions and consist of amphibolitic and quartz feldspathic gneisses, amphibolites, schists, pegmatites, calc-silicated rocks and marbles, with migmatization evidences in gneisses and amphibolites. Five foliations (S1-5) and three folding events (F1-3) were identified and interpreted as product of two metamorphic events, developed in a progressive barrovian metamorphic gradient of intermediate pressure with intermediate P-T ratio, interpreted as product of continental collision tectonics. This unit is important in understanding of the tectonic evolution of the Alta Guajira and Caribbean because it records different deformational phases pre-, syn- and post-migmatitic, that could be related with different tectonic episodes: the first associated with the collision between Laurasia and Gondwana (Alleghanian Orogeny - Late Paleozoic), and the second related with the Caribbean Plate evolution (Andean Orogeny - Meso-Cenozoic). Keywords: Migmatites, Deformation, Alleghanian orogeny, Alta Guajira, Colombia. &nbsp

Influence of the diatomite specie on the peak and residual shear strength of the fine-grained soil

Diatomite is a powdering mineral mainly composed of diatom microfossils present in marine and lacustrine soils, which influences their physical and mechanical properties. Although many articles have been found in the literature concerning the influence of diatomite in the overall behavior of natural soils, few research efforts have been carried out to evaluate the influence of the diatom microfossil species on their shear resistance. Therefore, in this research, the influence of the diatomite species and the content in the peak and the residual shear strength of diatomite-fine grained soil mixtures was analyzed using the annular shear strength test. Scanning electron microscopy (SEM) and Atterberg limits were also carried out as additional tests to explain the interlocking effect between the microfossils and the soil. Overall, both diatomite species increased both peak and residual shear strength of the soil similar to dense sands. Nevertheless, the Mexican species reveal higher friction angle values compared with Colombian species