Author: JUAN CARLOS VAZQUEZ CHAGOYAN
The impact of parametric variations on digital circuit performance is increasing in nanometer Integrated Circuits (IC), namely of Process, power supply Voltage and Temperature (PVT) variations. Moreover, circuit aging also impacts circuit performance, especially due to Negative Bias Temperature Instability (NBTI) effect. A growing number of physical defects manifest themselves as delay faults (at production, or during product lifetime). On-chip, on-line delay monitoring, as a circuit failure prediction technique, can be an attractive solution to guarantee correct operation in safety–critical applications. Safe operation can be monitored, by predictive delay fault detection. A delay monitoring methodology and a novel delay sensor (to be selectively inserted in key locations in the design and to be activated according to user’s requirements) is proposed, and a 65 nm design is presented. The proposed sensor is programmable, allowing delay monitoring for a wide range of delay values, and has been optimized to exhibit low sensitivity to PVT and aging-induced variations. Two MOSFET models—BPTM and ST—have been used. As abnormal delays can be monitored, regardless of their origin, both parametric variations and physical defects impact on circuit performance can be identified. Simulation results show that the sensor is effective in identifying such abnormal delays, due to NBTI-induced aging and to resistive open defects.
Delay sensors Reliability in nanometer technologies Failure prediction Process variations Predictive delay fault detection CIENCIAS FÍSICO MATEMÁTICAS Y CIENCIAS DE LA TIERRA FÍSICA ELECTRÓNICA ELECTRÓNICA
Anaerobic digestion (AD) is a biological process which produces biomethane as energy source, using waste as substrate. Cometabolism is a novel way to enhance liquid AD, via augmenting the biodiversity of inoculums, especially in the hitherto little-studied 96-h initiation period critical to AD startup. Dog, horse and sheep feces were used as sources of inoculum and mixed with fruit and vegetable waste (FVW) and water. Thermophilic (55 C), mesophilic (39 ) and psychrophilic (25 C) AD conditions were tested. As inoculum and water quantities alter the abundance and diversity of the anaerobic communities, 1:1 and 1:4 ratios of FVW feedstock to inoculum solutions were compared. Live Saccharomyces cerevisiae was supplemented as probiotic in the anaerobic reactors. Biogas, CO2 and CH4 were measured as well as digestion of FVW. Results showed consistently more CH4 production under cometabolism, higher inoculum density and thermophilic conditions; higher CH4, pH and digestion simultaneously occurred in the mixed-inoculum reactors. A strong relationship between biogas and its CO2 and CH4 main components was found. Horse inoculum in the mixed reactors enhanced CH4 production; sheep inoculums improved digestibility; and the dog inoculum seemed to neutralize pH. S. cerevisiae may have improved cellulolytic activity in FVW digestion at 25 and 39 C, and provided an energy and nutrient source at 55 C.
El río Lerma está poblado por diversas bacterias que se han vuelto resistentes a los contaminantes presentes. Algunas de estas bacterias son capaces de transformar algunos contaminantes a sustancias menos tóxicas. Tres cepas aisladas de sedimentos del Río Lerma resistieron concentraciones superiores a 207 mg L-1 de Cr(VI) y lo transformaron. La capacidad de transformación del Cr(VI) en orden descendente fue: Pseudomonas entomophila L48 > Pseudomonas cedrina CFML 96- 198 > Pseudomonas graminis DSM 11363. Por otro lado, ocho cepas con diferentes porcentajes de transformación de metil paratión (PM) fueron aisladas. Las cepas resistieron concentraciones superiores a 1,052 mg L-1. La capacidad de trasformación del PM en orden descendente fue: Comamonas testosteroni KS 0043 > Achromobacter denitrifi cans DSM 30026> Rhodococcus qingshengii djl-6 >Achromobacter spanius LMG 5911 > Pseudomonas meridiana CMS 38 > Pseudomonas veronii CIP 104663 > Pseudomonas nitroreducens IAM 1439 > Microbacterium esteraromaticum DSM 8609. Estas bacterias presentan un potencial biotecnológico en la remediación de cuerpos de agua o en tratamientos de agua para uso industrial.
Las células madre o progenitoras se han clasifi cado según su lecho natural de derivación, su aptitud y su función diferencial, en tres tipos: totipotenciales, pluripotenciales y multipotenciales; las primeras, llamadas células madre embrionarias, derivadas del cigoto en estadio de mórula; las segundas, provenientes de la masa celular interna (MCI) del blastocisto; las terceras, denominadas células madre somáticas, se encuentran en algunos tejidos adultos. La diferencia biológica radica en su capacidad para producir diversos linajes celulares; las totipotentes están biológicamente aptas para dar origen a un organismo completo; las pluripotentes pueden generar todos los tipos celulares, incluida la línea germinal; y las multipotentes pueden derivar en linajes específi cos. Las células troncales tienen la capacidad de autorrenovación y de originar células hijas comprometidas con determinadas rutas del desarrollo; se caracterizan porque se dividen indefi nidamente y además se diferencian de manera morfológica y funcional. Cuando las células troncoembrionarias y algunos tipos de células progenitoras se extraen de su entorno natural y se cultivan in vitro, en medios adecuados, pueden ser transfectadas y se mantienen indiferenciadas, sin perder su potencial; así, al reintroducirse a blastocistos receptores continúan su desarrollo. El estudio y la compilación de información acerca de estas cualidades biológicas de función diferencial, así como su utilidad para aprovechar la recombinación homóloga y para producir modelos animales que generen proteínas recombinantes, aplicables en medicina preventiva-regenerativa y tratamiento de enfermedades, constituyen el objetivo de este trabajo.
El síndrome reproductivo y respiratorio del cerdo (PRRS), es una enfermedad de origen viral que ocasiona fallas reproductivas severas en cerdas gestantes, con menos grado en la calidad del semen en verracos y problemas respiratorios en cerdos de todas las edades pero principalmente en lechones; también se asocia o incrementa la manifestación de otras enfermedades respiratorias. Es una de las enfermedades de mayor importancia económica mundial, en la mayoría de los países de producción de porcinos, donde en gran parte de ellos permanece endémico. El virus de PRRS (PRRSV) presenta un alto grado de mutabilidad, por lo que hay una gran diversidad genética de cepas del linaje norteamericano (PRRSV NA) y entre el PRRSV NA y el linaje europeo (PRRSV EU), lo que afecta la homogeneidad y poca o nula antigenicidad cruzada para vacunas; el virus vacunal modificado, único comercialmente accesible para generar algún grado confiable de inmunidad, ha mostrado la capacidad de revertirse a patógeno, con replicabilidad y recombinación con virus de campo; las vacunas sólo se utilizan para disminuir el grado de afección de la enfermedad; el virus muestra una capacidad de inmunosupresión e inmunoregulación que le permite, prolongar el tiempo de viremia en los animales enfermos, quienes eliminan el virus por saliva, secreciones tras placentarias, mamarias y muy posiblemente excremento, siendo la transmisión principal por contacto directo o por objetos contaminados; además presenta una posterior selectividad a pocos tejidos linfoides, que le permite permanecer inadvertido hasta que, en condiciones favorables, vuelve a manifestarse la enfermedad, ya sea como pequeños brotes, o como pandemia.
Due to probable toxicity problems to the host animals, these feed additives are not routinely used (Salem et al. 2014a, b). Recently, a great awareness from public health aspects such as residues of these chemicals in milk and meat, and bacterial resistance to antibiotics as a result of increased use in the food chains prohibits their use as feed additives (Barton 2000). These supplements have been criticized by the consumers’ organizations on the ground of product safety and quality. The consumers’ demands have stimulated to search for natural alternatives to chemical feed additives. Supplementation with probiotics that can survive in the rumen has become a suitable alternative (Fon and Nsahlai 2013).
For many years, ruminant nutritionists and microbiologists have been interested in manipulating the microbial ecosystem of the rumen to improve production efficiency of different ruminant species. Removal and restriction of antibiotics subtherapeutic uses from ruminant diets has amplified interest in improving nutrient utilization and animal performance and search for more safe alternatives. Some bacterial and fungal microorganisms as a direct-fed microbial (DFM) can be the most suitable solutions. Microorganisms that are commonly used in DFM for ruminants may be classified mainly as lactic acid producing bacteria (LAB), lactic acid utilizing bacteria (LUB), or other microorganism’s species like Lactobacillus, Bifidobacterium, Enterococcus, Streptococcus, Bacillus, Propionibacterium, Megasphaera elsdenii and Prevotellabryantii, in addition to some fungal species of yeast such as Saccharomyces and Aspergillus. A definitive mode of action for bacterial or fungal DFM has not been established; although a variety of mechanisms have been suggested. Bacterial DFM potentially moderate rumen conditions, and improve weight gain and feed efficiency. Fungal DFM may reduce harmful oxygen from the rumen, prevent excess lactate production, increase feed digestibility, and alter rumen fermentation patterns. DFM may also compete with and inhibit the growth of pathogens, immune system modulation, and modulate microbial balance in the gastrointestinal tract. Improved dry matter intake, milk yield, fat corrected milk yield and milk fat content were obtained with DFM administration. However, the response to DFM is not constant; depending on dosages, feeding times and frequencies, and strains of DFM. Nonetheless, recent studies have supported the positive effects of DFM on ruminant performance.
The aim of this study was to determine the seroprevalence and presence of Chlamydia abortus in Saanen breed female goats from commercial dairy goat farms under intensive production in the municipality of Guanajuato, Mexico. Sera were collected to determine the prevalence of anti-C. abortus IgG antibodies using recombinant enzymelinked immunosorbent assay (rELISA) and cell culture. Polymerase chain reaction (PCR) was used to prove the presence of the pathogen in swab samples collected from the vagina and rectum of selected animals. Additionally, foetal tissue samples from a sudden abortion were collected. C. abortus prevalence in female goats of commercial milking farms sampled in Guanajuato, Mexico, was 4.87 % (n=246). Seropositive animals were found in six out of nine (66.6 %) dairy goat farms sampled, and prevalence among animals in individual farms ranged between 3.44 and 13.51 %. C. abortus was detected using PCR in spleen tissue from the aborted foetus. PCR-based detection, as well as isolation from vaginal and rectal swabs, was not possible in the present study. Isolation through cell culture was also unsuccessful from aborted foetal tissue samples. In conclusion, the results from rELISA and PCR show that C. abortus is present in dairy goat farms in the state of Guanajuato, Mexico.
MONA MOHAMED MOHAMED YASSEEN ELGHANDOUR JUAN CARLOS VAZQUEZ CHAGOYAN Abdelfattah Zeidan Mohamed Salem Ahmed E. Kholif JOSE SIMON MARTINEZ CASTAÑEDA LUIS MIGUEL CAMACHO DIAZ GERMAN BUENDIA RODRIGUEZ (2013)
There is increasing interest in feeding fiber-based feeds as an alternative to high-starch cereal grains to horses as a means of meeting the energy demands and reduce various pathologies, such as gastric ulceration, hind-gut acidosis, laminitis, and colic [2,3], associated with feeding high levels of cereal grains. Depending on the forage type and time of harvest, forages of moderate to high nutritive value may meet the energy and crude protein (CP) requirements of horses . Horses naturally use forage as a primary component of their diet, and forage is a basic necessity for normal function of the equine digestive system. High forage rations are desirable because they contain low levels of starch and sugar. Feeding a minimum 1% of body weight as fiber is very important to minimize the incidence of hindgut acidosis , colic , gastric ulcers , and stereotypical behaviors . In tropical areas such as Mexico, forages used as feeds are generally low in digestibility and low in true protein . Therefore, there is a need to develop feeding strategies which meet the requirements of performance horses while maintaining gut health and integrity.
This experimentwas conducted to evaluate in vitro effects of equine fecal inocula fermentative capacity on 9 fibrous forages in the presence of Saccharomyces cerevisiae. The fibrous feeds were corn stover (Zeamays), oat straw(Avena sativa), sugarcane bagasseandleaves (Saccharum officinarum), llanero grass leaves (Andropogon gayanus), Taiwan grass leaves (Pennisetum purpureum), sorghum straw (Sorghum vulgare), and steria grass leaves (Cynodon plectostachyus). Fibrous feed samples were incubated with several doses of S. cerevisiae; 0 (control), 1.25 (low), 2.5 (medium) and 5 (high) mg/g dry matter (DM) of a commercial yeast product containing 1 1010/g. Fecal inoculumwas collected from4 adult horseswere fed onanamount of commercial concentrate and oat hay ad libitum. Gas production (GP)was recorded at 2, 4, 6, 8, 10, 12, 24, and 48 hours post inoculation. An interaction occurred between feeds and yeast dose for fecalpH(P<.01), asymptoticGP (b, ml/gDM); rate ofGP (c, /hr); initial delay beforeGP began (L, hours),GPat 4 hours and48 hours (P<.01), andGPat 8 hours (P<.01) andat 24 hours (P<.01). Differences in fecal fermentation capacity between the tropical and template grass (P < .05) occurred for fecal pH, c, and GP during first 12 hours, whereas differences occurred (P< .05) between the agriculture byproducts and the grasses for fecal pH, b, and GP from 8 to 48 hours. Fermentation capacity between straws versus not straws (P <.05) differed for fecal pH, b, and GP after 12 hours between straws versus not straws. Addition of S. cerevisiae to Z. mays stover reduced (P <.01) fecal pH and the c fraction with a higher (P <.01) b fraction versus the other feeds. From4 to 24 hours, S. officinarumbagasse improvedGP tothe highest values versus S. officinarum leaves. After 24 hours, Z. mays stover had the highest GP, whereas C. plectostachyus leaves had the lowest. There were no differences among the yeast doses for all measured parameters with the exception of L values (linear effect; P <.01). The Z. mays stover hadthe highestnutritive comparedtothe otherfibrous feeds.However, additionof S. cerevisiae at 2.5 to 5.0 g/kg DM improved fecal fermentation capacity of low-quality forages
SANDRA MARICRUZ LOPEZ HEYDECK Marcos Cajero Juárez ROGELIO ALEJANDRO ALONSO MORALES JOSE SIMON MARTINEZ CASTAÑEDA Jose Francisco Robles González ALBERTO BARBABOSA PLIEGO JUAN CARLOS VAZQUEZ CHAGOYAN (2009)
Electroporation has been the method of election for transfection of murine embryonic stem cells for over 15 years; however, it is a time consuming protocol because it requires large amounts of DNA and cells, as well as expensive and delicate equipment. Lipofection is a transfection method that requires lower amounts of cells and DNA than electroporation, and has proven to be effi cient in a large number of cell lines. It has been shown that after lipofection, mouse embryonic stem cells remain pluripotent, capable of forming germ line chimeras and can be transfected with greater effi ciency than with electroporation; however, gene targeting of mouse embryonic stem cells by lipofection has not been reported. The objective of this work was to fi nd out if lipofection can be used as effi ciently as electroporation for regular gene targeting protocols. This context compares gene targeting effi ciency between these techniques in mouse embryonic stem cells E14TG2a, using a gene replacement type vector. No differences were found in gene targeting effi ciency between groups; however, lipofection was three times more effi cient than electroporation in transfection effi ciency, which makes lipofection a less expensive alternative method to produce gene targeting in mouse embryonic stem cells.
The mode of action of bacterial silage feed additives was
proposed by McDonald (1981) who concluded that silages
are characterized by having low pH values, usually between
3.7 and 4.2, and containing high concentration of lactic acid.
Noton (1982) confirmed that anaerobic bacteria fermentation
converts sugary compounds in the material into lactic acid
inhibiting normal aerobic bacterial action. If air is kept out
of the silage, it is preserved efficiently and stably.
As a result of agriculture practices, million tons of agriculture are produced as a secondary or by-products; however, with low
nutritive values. Many methods are applied to improve the nutritive value and increase its utilization in ruminant’s nutrition.
The biological treatments are the most common with more safe-treated products. In most cases, the biological treatments
are paralleled with decreased crude fiber and fiber fractions content with increased crude protein content. Direct-fed microbial
and exogenous enzymes to animal are other ways of biological methods for improving nutritive value of feeds. Here
in this review, we will try to cover the biological treatments of by-products from different sides view with different types of
animals and different animal end-products.