Numerical Modelling of Caseless Ammunition with Coreless Bullet in Internal Ballistics

In the search of a new weapon for combat in short range, it is proposed the use of a new experimentally designed 7.62 mm calibre ammunition with a lighter weight (caseless-coreless). This can be used in carbine assault rifles with short barrel or pistols. In this work, the compressible gases flowing through the gun barrel caused by the proposed ammunition were experimentally and numerically analysed. The Large Eddy Simulation was used for the numerical simulation, considering a compressible and turbulent flow, with the chemical species transport model and a complete conversion of the propellant reaction. Variations in pressure and temperature were compared with the results obtained from a conventional 7.62 mm full metal jacket (FMJ) ammunition. Results of ballistic experimental tests and numerical simulations were similar than those of the 9 mm x 19 mm FMJ ammunitions, showing feasibility for the development of new weapons intended for operations of short range shots.Defence Science Journal, Vol. 65, No. 3, May 2015, pp.203-207, DOI: http://dx.doi.org/10.14429/dsj.65.851

Numerical and Experimental Analysis of Sound Suppressor for a 5.56 mm Calibre

A sound suppressor is an internal or external device coupled to the barrel of a firearm. Its development has been historically related to the negative effects produced by the noise. This article presents the numerical and experimental analysis of a sound suppressor for a 5.56 mm caliber rifle. It was designed, manufactured, and tested inside a shooting tunnel for 911 m/s and 344 m/s velocities. Three geometric configurations with curved deflectors, conical deflectors, and finally with a reactive spiral capable of dissipating the acoustic wave were compared considering reactive and dissipative systems. The attenuation of the sound inside the silencer depends directly on the reduction of the projectile wave velocity and the deflagration of the gases at the instant of firing. Then the MIL-STD-1474E standard was used to carry out the experiments. The results in the computational numerical simulation show an average value of 143 dB for the considered three models, the Sound Pressure Level in the reactive core model decreased by 25% with respect to other proposals, which have an average value of 141 dB. These results can be useful to improve in the design of sound suppressors based on the needs of the users and under the specific characteristics of each weapon ballistic.&nbsp

Producción de <i>Trichoderma viride</i> en diferentes sustratos agrícolas

Uno de los sustratos mayormente utilizados para reproducir a Trichoderma spp., es el grano entero de arroz, el cual tiene un costo relativamente alto en la producción de biofungicidas. Con el propósito de encontrar un sustrato económico y de fácil adquisición en la región de Tetela de Ocampo Puebla-México, en el cual la cepa nativa pueda presentar un buen desarrollo y una alta producción de esporas viables, se estableció esta investigación, que tuvo como objetivo evaluar 3 sustratos agrícolas en la reproducción y viabilidad de esporas de Thrichoderma viride. Se evaluaron granos de maíz quebrado, trigo y arroz, donde se utilizó un diseño completamente al azar con cinco repeticiones por tratamiento. El sustrato a base de maíz quebrado fue donde se obtuvo la mayor concentración de esporas la cepa THCA2 con 117.5 PEx104/ml y mostro un 99 % de viabilidad.One of the substrates mainly used to reproduce a Trichoderma spp., Whole grain is rice, which has a relatively high cost in the production of biofungicides. In order to find an affordable and readily available substrate in the region of Tetela de Ocampo Mexico Puebla, in which the native strain could present a good development and high production of viable spores, this research was established, which had the objective to evaluate three agricultural substrates in reproduction and spore viability Thrichoderma viride. Grains of cracked corn, wheat and rice, which used a completely randomized design with five replicates per treatment were evaluated. The substrate based on cracked corn was where the greatest concentration of spores HT-CA2 strain with 117.5 PEx104 / ml was obtained and showed 99% viability.Eje A1 Sistemas de producción de base agroecológica (Trabajos científicos)Facultad de Ciencias Agrarias y Forestale

Producción de <i>Trichoderma viride</i> en diferentes sustratos agrícolas

Uno de los sustratos mayormente utilizados para reproducir a Trichoderma spp., es el grano entero de arroz, el cual tiene un costo relativamente alto en la producción de biofungicidas. Con el propósito de encontrar un sustrato económico y de fácil adquisición en la región de Tetela de Ocampo Puebla-México, en el cual la cepa nativa pueda presentar un buen desarrollo y una alta producción de esporas viables, se estableció esta investigación, que tuvo como objetivo evaluar 3 sustratos agrícolas en la reproducción y viabilidad de esporas de Thrichoderma viride. Se evaluaron granos de maíz quebrado, trigo y arroz, donde se utilizó un diseño completamente al azar con cinco repeticiones por tratamiento. El sustrato a base de maíz quebrado fue donde se obtuvo la mayor concentración de esporas la cepa THCA2 con 117.5 PEx104/ml y mostro un 99 % de viabilidad.One of the substrates mainly used to reproduce a Trichoderma spp., Whole grain is rice, which has a relatively high cost in the production of biofungicides. In order to find an affordable and readily available substrate in the region of Tetela de Ocampo Mexico Puebla, in which the native strain could present a good development and high production of viable spores, this research was established, which had the objective to evaluate three agricultural substrates in reproduction and spore viability Thrichoderma viride. Grains of cracked corn, wheat and rice, which used a completely randomized design with five replicates per treatment were evaluated. The substrate based on cracked corn was where the greatest concentration of spores HT-CA2 strain with 117.5 PEx104 / ml was obtained and showed 99% viability.Eje A1 Sistemas de producción de base agroecológica (Trabajos científicos)Facultad de Ciencias Agrarias y Forestale

Mezquite y agave: Potenciales sustratos en la industria biotecnológica de México.

El mezquite y el agave son especies vegetales ampliamente distribuidas en México los cuales han sido empleados por diversos pueblos de nuestro país y poseen el potencial para ser utilizadas en diferentes aspectos biotecnológicos. La importancia de estas especies vegetales recae en su rol ecológico, tradicional y económico. Asimismo, en la investigación enfocada en la producción de nuevos alimentos, el aislamiento de compuestos con acción farmacológica, la síntesis de nuevos materiales (biopolímeros) y la producción de biocombustibles. Dada la relevancia de estas plantas en México, la presente revisión se basa en presentar un acervo de las características, propiedades y empleos, así como el prometedor uso en biotecnología que presentan estas especies vegetales

Nitrogen-carbon graphite-like semiconductor synthesized from uric acid

A new carbon-nitrogen organic semiconductor has been synthesized by pyrolysis of uric acid. This layered carbon-nitrogen material contains imidazole-, pyridine (naphthyridine)- and graphitic-like nitrogen, as evinced by infrared and X-ray photoelectron spectroscopies. Quantum chemistry calculations support that it would consist of a 2D polymeric material held together by hydrogen bonds. Layers are stacked with an interplanar distance between 3.30 and 3.36 Å, as in graphite and coke. Terahertz spectroscopy shows a behavior similar to that of amorphous carbons, such as coke, with non-interacting layers. This material features substantial differences from polymeric carbon nitride, with some characteristics closer to those of nitrogen-doped graphene, in spite of its higher nitrogen content. The direct optical band gap, dependent on the polycondensation temperature, ranges from 2.10 to 2.32 eV. Although in general the degree of crystallinity is low, in the material synthesized at 600 °C some spots with a certain degree of crystallinity can be found

Constraining the pˉ/p\bar{p}/p Ratio in TeV Cosmic Rays with Observations of the Moon Shadow by HAWC

An indirect measurement of the antiproton flux in cosmic rays is possible as the particles undergo deflection by the geomagnetic field. This effect can be measured by studying the deficit in the flux, or shadow, created by the Moon as it absorbs cosmic rays that are headed towards the Earth. The shadow is displaced from the actual position of the Moon due to geomagnetic deflection, which is a function of the energy and charge of the cosmic rays. The displacement provides a natural tool for momentum/charge discrimination that can be used to study the composition of cosmic rays. Using 33 months of data comprising more than 80 billion cosmic rays measured by the High Altitude Water Cherenkov (HAWC) observatory, we have analyzed the Moon shadow to search for TeV antiprotons in cosmic rays. We present our first upper limits on the $\bar{p}/p$ fraction, which in the absence of any direct measurements, provide the tightest available constraints of $\sim1\%$ on the antiproton fraction for energies between 1 and 10 TeV.Comment: 10 pages, 5 figures. Accepted by Physical Review

All-particle cosmic ray energy spectrum measured by the HAWC experiment from 10 to 500 TeV

We report on the measurement of the all-particle cosmic ray energy spectrum with the High Altitude Water Cherenkov (HAWC) Observatory in the energy range 10 to 500 TeV. HAWC is a ground based air-shower array deployed on the slopes of Volcan Sierra Negra in the state of Puebla, Mexico, and is sensitive to gamma rays and cosmic rays at TeV energies. The data used in this work were taken from 234 days between June 2016 to February 2017. The primary cosmic-ray energy is determined with a maximum likelihood approach using the particle density as a function of distance to the shower core. Introducing quality cuts to isolate events with shower cores landing on the array, the reconstructed energy distribution is unfolded iteratively. The measured all-particle spectrum is consistent with a broken power law with an index of $-2.49\pm0.01$ prior to a break at $(45.7\pm0.1$) TeV, followed by an index of $-2.71\pm0.01$. The spectrum also respresents a single measurement that spans the energy range between direct detection and ground based experiments. As a verification of the detector response, the energy scale and angular resolution are validated by observation of the cosmic ray Moon shadow's dependence on energy.Comment: 16 pages, 11 figures, 4 tables, submission to Physical Review

Extended gamma-ray sources around pulsars constrain the origin of the positron flux at Earth

The unexpectedly high flux of cosmic ray positrons detected at Earth may originate from nearby astrophysical sources, dark matter, or unknown processes of cosmic-ray secondary production. We report the detection, using the HighAltitude Water Cherenkov Observatory (HAWC), of extended tera-electron volt gamma-ray emission coincident with the locations of two nearby middle-aged pulsars (Geminga and PSR B0656+14). The HAWC observations demonstrate that these pulsars are indeed local sources of accelerated leptons, but the measured tera-electron volt emission profile constrains the diffusion of particles away from these sources to be much slower than previously assumed. We demonstrate that the leptons emitted by these objects are therefore unlikely to be the origin of the excess positrons, which may have a more exotic origin.Comment: 16 pages (including supplementary material), 5 figure

Insulin resistance and its association with the components of the metabolic syndrome among obese children and adolescents

<p>Abstract</p> <p>Background</p> <p>Insulin resistance is the primary metabolic disorder associated with obesity; yet little is known about its role as a determinant of the metabolic syndrome in obese children. The aim of this study is to assess the association between the degree of insulin resistance and the different components of the metabolic syndrome among obese children and adolescents.</p> <p>Methods</p> <p>An analytical, cross-sectional and population-based study was performed in forty-four public primary schools in Campeche City, Mexico. A total of 466 obese children and adolescents between 11-13 years of age were recruited. Fasting glucose and insulin concentrations, high density lipoprotein cholesterol, triglycerides, waist circumference, systolic and diastolic blood pressures were measured; insulin resistance and metabolic syndrome were also evaluated.</p> <p>Results</p> <p>Out of the total population studied, 69% presented low values of high density lipoprotein cholesterol, 49% suffered from abdominal obesity, 29% had hypertriglyceridemia, 8% presented high systolic and 13% high diastolic blood pressure, 4% showed impaired fasting glucose, 51% presented insulin resistance and 20% metabolic syndrome. In spite of being obese, 13% of the investigated population did not present any metabolic disorder. For each one of the components of the metabolic syndrome, when insulin resistance increased so did odds ratios as cardiometabolic risk factors.</p> <p>Conclusions</p> <p>Regardless of age and gender an increased degree of insulin resistance is associated with a higher prevalence of disorders in each of the components of the metabolic syndrome and with a heightened risk of suffering metabolic syndrome among obese children and adolescents.</p