193 research outputs found
Inflamação uterina da vaca pós-parto. Do dizer ao fazer...
Reproductive efficiency is one of the most important factors determining the genetic progress and productivity of cattle herds. To maintain acceptable reproductive efficiency, it is necessary for cows to have a calving interval of less than 400 days; a calving-conception interval of less than 110 days and less than 3 services per conception. Reproductive efficiency largely depends on the health and fertility of the herd. Postpartum uterine inflammation (metritis/endometritis/pyometra) is one of the main causes of poor reproductive performance in dairy and dual purpose herds. This condition results in low pregnancy rates, high number of services per conception, long postpartum intervals, high culling rates, and substantial economic losses (Gilbert et al., 2016). There is a great discrepancy in the criteria for diagnosis and treatment of puerperal metritis in dairy farms. In the case of endometritis, the situation is even more critical, because diagnosis is not routinely carried out at the field level, which limits the timely establishment of treatments and preventive management measures.La eficiencia reproductiva es uno de los factores más importantes que determinan el progreso genético y la productividad de los rebaños vacunos. Para mantener una eficiencia reproductiva aceptable, es necesario que las vacas tengan un intervalo entre partos de menos de 400 dÃas; un intervalo parto-concepción menor de 110 dÃas y menos de 3 servicios por concepción. La eficiencia reproductiva depende en gran medida de la salud y fertilidad del rebaño. La inflamación uterina postparto (metritis/endometritis/piometra) es una de las principales causas del bajo rendimiento reproductivo en rebaños lecheros y doble propósito. Esta condición resulta en bajas tasas de preñez, alto número de servicios por concepción, intervalos postparto prolongados, altas tasas de descarte y pérdidas económicas sustanciales (Gilbert et al., 2016). Existe una gran discrepancia en los criterios de diagnóstico y tratamiento de la metritis puerperal en fincas lecheras. En el caso de la endometritis, la situación es aún más crÃtica, porque comúnmente el diagnóstico no se lleva a cabo de manera rutinaria a nivel de campo, lo cual limita la instauración oportuna de los tratamientos y las medidas de manejo preventivo.A eficiência reprodutiva é um dos fatores mais importantes que determinam o progresso genético e a produtividade dos rebanhos bovinos. Para manter uma eficiência reprodutiva aceitável, é necessário que as vacas tenham um intervalo entre partos inferior a 400 dias; um intervalo parto-concepção inferior a 110 dias e inferior a 3 serviços por concepção. A eficiência reprodutiva depende em grande parte da saúde e fertilidade do rebanho. A inflamação uterina pós-parto (metrite/endometrite/piometra) é uma das principais causas do baixo desempenho reprodutivo em rebanhos leiteiros e de dupla finalidade. Essa condição resulta em baixas taxas de gravidez, alto número de serviços por concepção, longos intervalos pós-parto, altas taxas de descarte e perdas econômicas substanciais (Gilbert et al., 2016). Existe uma grande discrepância nos critérios para diagnóstico e tratamento da metrite puerperal em fazendas leiteiras. No caso da endometrite, a situação é ainda mais crÃtica, pois o diagnóstico não é realizado rotineiramente em campo, o que limita o estabelecimento oportuno de tratamentos e medidas preventivas de manejo
Inverted vs Standard PTB7:PC70BM Organic Photovoltaic Devices. The benefit of highly selective and extracting contacts in device performance
In this work we compare the photovoltaic performance of different cell designs, standard
and inverted, for one of the most promising systems to achieve power conversion efficiencies
over 10% in polymer:fullerene single cells, namely PTB7:PC70BM. Impedance spectroscopy,
charge extraction and transient photovoltage are used in order to assign the electrical
losses initially observed in the current density–voltage curve and understand the main limitation
of every design. While inverted devices show competitive performance in terms of
charge generation, transport of carriers and also for charge collection at electrodes, standard
devices present additional resistive losses that are assigned to charge transfer issues
at the active layer/anode interface. This additional resistance increase the overall series
resistance of devices, lowers the fill factor and it is the ultimate responsible for the
observed reduced device performance of standard cells in comparison to inverted ones.
In this way, devices over 7.2% are reported with ZnO and MoO3 as interlayer electrodes that
act as improved highly selective and extracting contacts in comparison to standard PEDOT:PSS
and Ca/Ag. Contacts are thus electrically optimized. Additional improvement of
device performance must consider enhancement of intrinsic recombination properties of
the blend. Lower molecular weights and/or any residual catalyst impurities with respect
to other batches are the only limitation to reach record efficiencies as those shown in
recent works
Efectos de la suplementación parenteral de cobre, zinc, selenio y manganeso sobre el desempeño reproductivo de las vacas Holstein
The objective of this investigation was to study the supplementation of injectable trace minerals (ITM), based on Cu, Zn, Mn, and Se on reproductive performance of dairy cows from Torreon, Mexico, a geographical region characterized by a semi-desertic climate. The study consisted of 2 field trials. Trial 1 compared the application of 2 doses of ITM during the dry period (at dry-off and at prepartum) (n= 75) with a control group (n=79). Trial 2 compared the application of 1 dose of ITM at 35 d postpartum (n=258) with a control group (n=258). In both trials, conception rate at first service (CRFS) and daysto conception were evaluated. In Trial 1, CRFS was not different between groups, but calving to conception interval tended to be shorter in 10 days in the treated than the control group (P=0.14). In trial 2, CRFS was not different between groups either, but time to pregnancy was significantly 14 days earlier than the control group (P ≤ 0.05). It is concluded that although CRFS was similar between groups, the application of an ITM reduced the time to pregnancy in treated than the control groups, which have a great impact on herd’s fertility and profit.El objetivo de esta investigación fue estudiar la suplementación de oligoelementos inyectables (ITM), con base en Cu, Zn, Mn y Se sobre el desempeño reproductivo de vacas lecheras de Torreón, México, una región geográfica caracterizada por un clima semidesértico. El estudio consistió en 2 ensayos de campo. El ensayo 1 comparó la aplicación de 2 dosis de ITM durante el perÃodo seco (al secarse y antes del parto) (n = 75) con un grupo de control (n = 79). El ensayo 2 comparó la aplicación de 1 dosis de ITM a los 35 dÃas después del parto (n = 258) con un grupo de control (n = 258). En ambos ensayos, se evaluaron la tasa de concepción en el primer servicio (CRFS) y los dÃas hasta la concepción. En el Ensayo 1, el CRFS no fue diferente entre los grupos, pero el intervalo entre el parto y la concepción tendió a ser más corto en 10 dÃas en el grupo tratado que en el grupo de control (P = 0,14). En el ensayo 2, la CRFS tampoco fue diferente entre los grupos, pero el tiempo a la preñez fue significativamente 14 dÃas antes que en el grupo control (P ≤ 0,05). Se concluye que aunque la CRFS fue similar entre los grupos, la aplicación de un ITM redujo el tiempo a la gestación en los grupos tratados que en los de control, lo que tiene un gran impacto en la fertilidad y las ganancias del hato.en la fertilidad y las ganancias del hato
Charge carrier transport and contact selectivity limit the operation of PTB7-based organic solar cells of varying active layer thickness
In this work we study the different electrical loss pathways occurring during the operation of bulk heterojunction solar cells by using a variety of electrical and optical characterization techniques beyond the current density–voltage curve (J–V): Impedance Spectroscopy (IS), Charge Extraction (CE) and Transient Photovoltage (TPV). Two sets of devices are analyzed: the first is based on the donor polymer P3HT, known to provide efficient cells using thick active layers (i.e. 270 nm), and the recently developed PTB7 which offers maximum efficiencies for devices with thinner layers (i.e. 100 nm). Devices fabricated with P3HT:PC60BM are not limited by transport of carriers and large active layer thickness may be used. Importantly, increasing the active layer thickness does not modify the contact selectivity. This is supported by analysis of the diode curve measured in the dark (similar leakage currents) and by capacitance–voltage measurements (similar fullerene content covering the cathode). Under these conditions the current density curve under illumination is mainly defined by the recombination processes taking place in the bulk of the active layer. In contrast, transport of carriers and contact selectivity are both limiting factors for the PTB7:PC60BM system. In this case, best efficiencies are obtained with a low active layer thickness and a high fullerene ratio. Reduced active layer thickness minimizes undesired electrical resistances related to carrier transport through the bulk of the active layer. High fullerene content enhances the amount of fullerene molecules at the cathode leading to decreased leakage currents. Then, the overall device efficiency will be a combination of the recombination kinetics in the bulk of the active layer, undesired resistance to transport of carriers and leakage current present due to low selectivity of the contact. The use of additives has also been explored which enhances charge generation and extraction. Overall, this work provides a comprehensive guide on how to interpret results obtained from some of the most widely used optoelectronic techniques employed to analyse operating devices
Co, Zn and Ag-MOFs evaluation as biocidal materials towards photosynthetic organisms
In the present study, the biocidal activity of three different metal organic frameworks (MOFs) based on Co (Co-SIM1), Zn (Zn-SIM1) and Ag (Ag-TAZ) has been evaluated towards one green alga and two cyanobacteria. These organisms are present in fresh- and seawater and take part in the early stages of the biofouling process. The biocidal activity of these materials was evaluated by measuring chlorophyll a concentration and by inhibition zone testing. After 24Â h of exposure the three different MOFs caused >Â 50% of chlorophyll a concentration inhibition towards both cyanobacteria, however, although the green alga presented a great sensitivity for Ag-TAZ (reaching 90% of chlorophyll a concentration inhibition), it was much more resistant to the rest of MOFs. Bioavailability of these metals was studied using ICP-MS, the chemical speciation program Visual MINTEQ, and a heavy metal bioreporter bioanalytical tool. We have elucidated that the biocidal activity presented by these MOFs was due to the dissolved metals released from them and more exactly, it depended on the bioavailability presented by these metal ions, which was closely related with the free ion concentration. This article highlights the potential use of different MOFs as biocidal material towards photosynthetic organisms and reveals important differences in the sensitivity between these organisms that should be taken into account in order to increase the biocidal spectrum of these materialsThis research was supported by the Spanish Ministry of Economy, CTM2013-45775-C2-1-R and CTM2013-45775-C2-2-
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