Crecimiento, rendimiento y calidad de semillas de tres cv de Cenchrus ciliaris bajo condiciones de salinidad

La salinidad es uno de los mayores factores limitantes para la expansión de la frontera agrícola, afecta a más de 30 millones de hectáreas principalmente en las regiones áridas y semiáridas, donde es una de las principales limitaciones edáficas para la producción de plantas forrajeras. Cenchrus ciliaris (Poaceae), es una especie perenne, nativa de África y de la mitad este de Asia de conocida tolerancia a condiciones de sequía y elevadas temperaturas. Sin embargo la información sobre la tolerancia a condiciones de salinidad es escasa por lo que el objetivo general de este trabajo fue aportar conocimientos sobre los efectos de la salinidad en el rendimiento de forraje y semilla de Cenchrus ciliaris y algunos de los mecanismos fisiológicos subyacentes. Para esto se utilizaron tres cv Americana, Biloela y Texas, que se cultivaron en containers de 1000 litros sobre arena lavada durante dos temporadas. Este sistema de cultivo permitió controlar los niveles de salinidad en el sustrato, similar a una hidroponía, pero mantener a las plantas en condiciones de campo en cuanto a temperatura, radiación, humedad, vientos etc. Haciendo así que los resultados sean mucho más próximos y extrapolables a una condición real de cultivo. Los tratamientos consistieron en riegos con soluciones de NaCl de 8, 13 y 18 dS/m, sobre una base de solución nutritiva. El control consistió solamente en la mencionada solución nutritiva (3 dS/m). Para evitar la acumulación de sales en el perfil se diseñó un sistema de drenaje que permitió monitorear diariamente el lixiviado de riego y mantener el sistema estable. Los efectos de los tratamientos se evaluaron sobre variables de crecimiento y de rendimiento reproductivo. También se realizaron mediciones de potencial hídrico, osmótico, contenido relativo de agua (RWC) y acumulación de iones en lámina foliar. Para determinar si la semillas obtenidas de plantas estresadas toleran mejor condiciones de estrés durante la germinación, estas se incubaron en soluciones de NaCl de -0.5, -1, -1.5, -2, -2.5 y -3 MPa. Los resultados mostraron que los tres cv responden de manera similar frente al estrés, disminuyendo el crecimiento vegetativo y el rendimiento conforme aumenta la salinidad. Como respuesta general a los tratamientos salinos el crecimiento disminuyó al igual que lo observado para condiciones de estrés hídrico. De todas las etapas del ciclo ontogénico estudiadas la más susceptible fue la inicial que comprendió plantas que estaban iniciando la etapa reproductiva, siendo el cv Biloela el más susceptible. Luego hacia el final de la temporada de crecimiento las diferencias entre el control y el tratamiento menos salino (8 dS/m) desaparecieron. Esto indica que el cultivo es más sensible a la salinidad en la etapa vegetativa y el inicio de la etapa reproductiva. De las componentes del rendimiento reproductivo sólo el número de espigas por planta y el peso de 100 cariopses se vieron afectados. Con respecto a las variables hídricas los tres cv modificaron tanto el potencial hídrico como el osmótico y mantuvieron su RWC constante. Los iones adicionados con los tratamientos Na+ y Cl- se acumularon en hoja conforme aumentó la conductividad de las soluciones de riego. El análisis de K+ para cada cv mostró que en todos los casos los niveles de este ion fueron significativamente mayores en el control que en los tratamientos. En los tres cv estudiados se observó que semillas provenientes de plantas que crecieron en condiciones de salinidad germinaron en mayor cantidad y más rápido que las provenientes del control. En el cv Texas estas diferencias son especialmente marcadas, así semillas provenientes del tratamiento con mayor nivel de salinidad (18 S/m) germinaron casi un 50 por ciento más que las provenientes del control. El efecto de la salinidad durante el desarrollo de las semillas incrementó los niveles de germinación en los controles (0 Mpa) y en condiciones moderadas de salinidad (-0,5 a -1,5 MPa)

Crecimiento, rendimiento y calidad de semillas de tres cv de Cenchrus ciliaris bajo condiciones de salinidad

La salinidad es uno de los mayores factores limitantes para la expansión de la frontera agrícola, afecta a más de 30 millones de hectáreas principalmente en las regiones áridas y semiáridas, donde es una de las principales limitaciones edáficas para la producción de plantas forrajeras. Cenchrus ciliaris (Poaceae), es una especie perenne, nativa de África y de la mitad este de Asia de conocida tolerancia a condiciones de sequía y elevadas temperaturas. Sin embargo la información sobre la tolerancia a condiciones de salinidad es escasa por lo que el objetivo general de este trabajo fue aportar conocimientos sobre los efectos de la salinidad en el rendimiento de forraje y semilla de Cenchrus ciliaris y algunos de los mecanismos fisiológicos subyacentes. Para esto se utilizaron tres cv Americana, Biloela y Texas, que se cultivaron en containers de 1000 litros sobre arena lavada durante dos temporadas. Este sistema de cultivo permitió controlar los niveles de salinidad en el sustrato, similar a una hidroponía, pero mantener a las plantas en condiciones de campo en cuanto a temperatura, radiación, humedad, vientos etc. Haciendo así que los resultados sean mucho más próximos y extrapolables a una condición real de cultivo. Los tratamientos consistieron en riegos con soluciones de NaCl de 8, 13 y 18 dS/m, sobre una base de solución nutritiva. El control consistió solamente en la mencionada solución nutritiva (3 dS/m). Para evitar la acumulación de sales en el perfil se diseñó un sistema de drenaje que permitió monitorear diariamente el lixiviado de riego y mantener el sistema estable. Los efectos de los tratamientos se evaluaron sobre variables de crecimiento y de rendimiento reproductivo. También se realizaron mediciones de potencial hídrico, osmótico, contenido relativo de agua (RWC)y acumulación de iones en lámina foliar. Para determinar si la semillas obtenidas de plantas estresadas toleran mejor condiciones de estrés durante la germinación, estas se incubaron en soluciones de NaCl de -0.5, -1, -1.5, -2, -2.5 y -3 MPa. Los resultados mostraron que los tres cv responden de manera similar frente al estrés, disminuyendo el crecimiento vegetativo y el rendimiento conforme aumenta la salinidad. Como respuesta general a los tratamientos salinos el crecimiento disminuyó al igual que lo observado para condiciones de estrés hídrico. De todas las etapas del ciclo ontogénico estudiadas la más susceptible fue la inicial que comprendió plantas que estaban iniciando la etapa reproductiva, siendo el cv Biloela el más susceptible. Luego hacia el final de la temporada de crecimiento las diferencias entre el control y el tratamiento menos salino (8 dS/m)desaparecieron. Esto indica que el cultivo es más sensible a la salinidad en la etapa vegetativa y el inicio de la etapa reproductiva. De las componentes del rendimiento reproductivo sólo el número de espigas por planta y el peso de 100 cariopses se vieron afectados. Con respecto a las variables hídricas los tres cv modificaron tanto el potencial hídrico como el osmótico y mantuvieron su RWC constante. Los iones adicionados con los tratamientos Na+ y Cl- se acumularon en hoja conforme aumentó la conductividad de las soluciones de riego. El análisis de K+ para cada cv mostró que en todos los casos los niveles de este ion fueron significativamente mayores en el control que en los tratamientos. En los tres cv estudiados se observó que semillas provenientes de plantas que crecieron en condiciones de salinidad germinaron en mayor cantidad y más rápido que las provenientes del control. En el cv Texas estas diferencias son especialmente marcadas, así semillas provenientes del tratamiento con mayor nivel de salinidad (18 S/m)germinaron casi un 50 por ciento más que las provenientes del control. El efecto de la salinidad durante el desarrollo de las semillas incrementó los niveles de germinación en los controles (0 Mpa)y en condiciones moderadas de salinidad (-0,5 a -1,5 MPa)

ATR-FTIR spectroscopy and spectroscopic imaging of solvent and permeant diffusion across model membranes

The uptake and diffusion of solvents across polymer membranes is important in controlled drug delivery, effects on drug uptake into, for example, infusion bags and containers, as well as transport across protective clothing. Attenuated Total Reflectance Fourier Transform Infrared (ATR-FTIR) spectroscopy has been used to monitor the effects of different solvents on the diffusion of a model compound, 4-cyanophenol (CNP) across silicone membrane and on the equilibrium concentration of CNP obtained in the membrane following diffusion. ATR-FTIR spectroscopic imaging of membrane diffusion was used to gain an understanding of when the boundary conditions applied to Fick's second law, used to model the diffusion of permeants across the silicone membrane do not hold. The imaging experiments indicated that when the solvent was not taken up appreciably into the membrane, the presence of discrete solvent pools between the ATR crystal and the silicone membrane can affect the diffusion profile of the permeant. This effect is more significant if the permeant has a high solubility in the solvent. In contrast, solvents that are taken up into the membrane to a greater extent, or those where the solubility of the permeant in the vehicle is relatively low, were found to show a good fit to the diffusion model. As such these systems allow the ATR-FTIR spectroscopic approach to give mechanistic insight into how the particular solvents enhance permeation. The solubility of CNP in the solvent and the uptake of the solvent into the membrane were found to be important influences on the equilibrium concentration of the permeant obtained in the membrane following diffusion. In general, solvents which were taken up to a significant extent into the membrane and which caused the membrane to swell increased the diffusion coefficient of the permeant in the membrane though other factors such as solvent viscosity may also be important.

Caking strength of granulated clay under frozen conditions

Transport of particulate clay occurs during some extremely cold weather conditions typically in the winter in the far North area. During the transport and temporary storage time, the clay may cake inside a rail or road wagon or in a silo, and consequently be difficult to be discharged from the containers. This paper studied caking strength of a granulated clay powder with a certain water moisture content of 18% for influences of temperature, packing stress and freezing time. The temperature tested was -5 oC, -10 oC and -20 oC. Because the clay powder may be packed at different bed depth, the study was undertaken across the packing stress range at 8.3 kPa (1 m bed depth), 25.0 kPa (3 m) and 75.0 kPa (9 m). Freezing time varied between 4 hours (transport) and 18 hours (overnight). During the tests, failure of caked materials was measured using a QTS texture analyzer and the caking strength of frozen samples was calculated. Influences on freeze caking of granular clay in storage or transport are discussed briefly. Some conclusions are made at the end of the paper,including recommendations for practical methods for mitigating these problems.

Repositioning documents in social research

In matters of social research sociologists and other social scientists have tended to view documents primarily as sources of evidence and as receptacles of inert content.The key strategies for data exploration have consequently been associated with various styles of content or thematic analysis. Even when discourse analysis has been recommended, there has been a marked tendency to deal with records, files, and the like, primarily as containers - things to be read, understood, and categorized. In this article, however, the author seeks to demonstrate that by focussing on the functioning of documents instead of content, sociology can embrace a much wider range of approaches to both data collection and analysis. Indeed, the adoption of such a programme encourages researchers to see documents as active agents in the world, and to view documentation as a key component of dynamic networks rather than as a set of static and immutable 'things'.

Validating Injection Stretch-Blow Molding Simulation Through Free Blow Trials

A 2D isothermal finite element simulation of the injection stretch-blow molding (ISBM) process for polyethylene terephthalate (PET) containers has been developed through the commercial finite element package ABAQUS/standard. In this work, the blowing air to inflate the PET preform was modeled through two different approaches: a direct pressure input (as measured in the blowing machine) and a constant mass flow rate input (based on a pressure-volume-time relationship). The results from these two approaches were validated against free blow and free stretch-blow experiments, which were instrumented and monitored through high-speed video. Results show that simulation using a constant mass flow rate approach gave a better prediction of volume vs. time curve and preform shape evolution when compared with the direct pressure approach and hence is more appropriate in modeling the preblowing stage in the injection stretch-blow molding process

Modelling and Instrumentation of Stretch Blow Moulding

The injection stretch blow moulding process is used to manufacture PET containers used in the soft drinks and carbonated soft drinks industry. The process consists of a test tube like specimen known as a preform which is heated, stretch and blown into a mould to form the container. This research is focused on developing a validated simulation of the process thus enabling manufacturers to design their products in a virtual environment without the need to waste time, material and energy. The simulation has been developed using the commercial FEA package Abaqus and has been validated using state of the art data acquisition system consisting of measurements for preform temperature (inner and outer wall) using a device known as THERMOscan (Figure 1), stretch rod force and velocity, internal pressure and air temperature inside the preform using an instrumented stretch rod and the?exact?timing of when the preform touches the mould wall using contact sensors.? In addition, validation studies have also been performed by blowing a perform without a mould and using high sped imaging technology in cooperation with an advanced digital image correlation system (VIC 3D) to provided new quantitative information on the behaviour of PET during blowing.? The approach has resulted in a realistic simulation in terms of accurate input parameters, preform shape evolution and prediction of final properties.

Potential hazard to human health from exposure to fragments of lead bullets and shot in the tissues of game animals

Lead is highly toxic to animals. Humans eating game killed using lead ammunition generally avoid swallowing shot or bullets and dietary lead exposure from this source has been considered low. Recent evidence illustrates that lead bullets fragment on impact, leaving small lead particles widely distributed in game tissues. Our paper asks whether lead gunshot pellets also fragment upon impact, and whether lead derived from spent gunshot and bullets in the tissues of game animals could pose a threat to human health.

Lead contamination and associated disease in captive and reintroduced red kites Milvus milvus in England

Since 1989, a red kite Milvus milvus reintroduction programme has been underway in the United Kingdom, with 4-6 week old nestlings brought into captivity and held for 6-8 weeks before reintroduction. As scavengers, red kites may consume unretrieved game, and ingest shot or lead (Pb) fragments in their prey's flesh. We evaluated exposure to Pb in captive and wild red kites by taking blood samples from 125 captive young red kites prior to release, through analysing 264 pellets (regurgitated by wild birds) collected from under a roost site, and analysing Pb concentrations in livers and/or bones of 87 red kites found dead between 1995 and 2003. Lead isotope analyses of livers were also conducted in an effort to identify Pb exposure routes. Forty-six (36.8%) kites sampled prior to release had elevated blood Pb concentrations (201-3340 microg l(-1)). The source of this Pb was probably small fragments of lead ammunition in the carcasses of birds or mammals either fed to the nestlings by their parents or, more likely, subsequently whilst in captivity. Once released, kites were also exposed to lead shot in their food, and a minimum of 1.5-2.3% of regurgitated pellets contained Pb gunshot. Seven of 44 red kites found dead or that were captured sick and died within a few days had elevated (>6 mg kg(-1) dry weight [d.w.]) liver Pb concentrations, and six of these (14%) had concentrations of >15 mg kg(-1) d.w., compatible with fatal Pb poisoning. Post-mortem analyses indicated that two of these birds had died of other causes (poisoning by rodenticide and a banned agricultural pesticide); the remaining four (9%) probably died of Pb poisoning. Bone samples from 86 red kites showed a skewed distribution of Pb concentration, and 18 samples (21%) had Pb concentrations >20 mg kg(-1) d.w., indicating elevated exposure to Pb at some stage in the birds' life. Lead isotopic signatures (Pb (208/206); Pb (206/207)) in liver samples of the majority of kites were compatible with those found in lead shot extracted from regurgitated pellets. Lead isotope ratios found in the livers of kites with very low Pb concentrations were distinct from UK petrol Pb isotopic signatures, indicating that birds were exposed to little residual petrol Pb. We conclude that the primary source of Pb to which red kites are exposed is lead ammunition (shotgun pellets or rifle bullets), or fragments thereof, in their food sources; in some cases exposure appears sufficient to be fatal. We make recommendations to reduce Pb poisoning in both captive and wild red kites and other scavenging species.

Multibody modelling of gabion beams for impact applications

Gabions are stone-filled wire containers which are frequently used as retaining walls. However, due to their high mass, relatively low cost and visual appeal, a row of single gabion blocks, joined at the ends, has the potential to be used as a roadside impact absorption device where traditional steel or concrete devices may not be suitable. To evaluate such application, the shear and bending deformation of gabions under vehicle impact need to be investigated. In this paper, the shear response of a single gabion block is analytically modelled and a gabion beam multibody model is developed using a discretisation method to capture the deformability of the gabion structure. The material properties of the gabion beam are adopted from experimental values available in the literature and the modelling is statically validated over a three-point bending test and a distributed loading test. The results show that the discretised multibody modelling can be effectively used to describe the static deformation behaviour of gabion blocks.

Milling plant and soil material in plastic tubes over-estimates carbon and under-estimates nitrogen concentrations

Milling of plant and soil material in plastic tubes, such as microcentrifuge tubes, over-estimates carbon (C) and under-estimates nitrogen (N) concentrations due to the introduction of polypropylene into milled samples, as identified using Fourier-transform infra-red spectroscopy.

This study compares C and N concentrations of roots and soil milled in microcentrifuge tubes versus stainless steel containers, demonstrating that a longer milling time, greater milling intensity, smaller sample size and inclusion of abrasive sample material all increase polypropylene contamination from plastic tubes leading to overestimation of C concentrations by up to 8 % (0.08 g g(-1)).

Erroneous estimations of C and N, and other analytes, must be assumed after milling in plastic tubes and milling methods should be adapted to minimise such error.

Measuring and modelling air mass flow rate in the injection stretch blow moulding process

The injection stretch blow moulding process involves the inflation and stretching of a hot preform into a mould to form bottles. A critical process variable and an essential input for process simulations is the rate of pressure increase within the preform during forming, which is regulated by an air flow restrictor valve. The paper describes a set of experiments for measuring the air flow rate within an industrial ISBM machine and the subsequent modelling of it with the FEA package ABAQUS. Two rigid containers were inserted into a Sidel SBO1 blow moulding machine and subjected to different supply pressures and air flow restrictor settings. The pressure and air temperature were recorded for each experiment enabling the mass flow rate of air to be determined along with an important machine characteristic known as the ‘dead volume’. The experimental setup was simulated within the commercial FEA package ABAQUS/Explicit using a combination of structural, fluid and fluid link elements that idealize the air flowing through an orifice behaving as an ideal gas under isothermal conditions. Results between experiment and simulation are compared and show a good correlation.

UV dosimetry for solar water disinfection (SODIS) carried out in different plastic bottles and bags

Solar water disinfection (SODIS) is a well-established inexpensive means of water disinfection in developing countries, but lacks an indicator to illustrate its end-point. A study of the solar UV dosage required for SODIS, in order to achieve a bacteria concentration below the detection limit for: Escherichia coli, Enterococcus spp. and Clostridium perfringens, in water in PET bottles, PE and PE/EVA bags showed disinfection to be most efficient in PE bags, with a solar UV (290–385 nm) dose of 389 kJ m−2 required. In parallel to the disinfection experiments, a range of polyoxometalate, semiconductor photocatalysis and photodegradable dye-based solar UV dosimeter indicators were tested under the same solar UV irradiation conditions. All three types of dosimeter produced indicators that largely and significantly change colour upon exposure to 389 kJ m−2 solar UV; further indicators are reported which change colour at higher doses and hence would be suitable for the less efficient SODIS containers tested. All indicators tested were robust, easy to use and inexpensive so as not to add significantly to the attractive low cost of SODIS. Furthermore, whilst semiconductor photocatalyst and photodegradable dye based indicators are disposable, one-use systems, the polyoxometalate based indicators recover colour in the dark overnight, allowing them to be reused, and hence further decreasing the cost of using indicators during the implementation of the SODIS method.

Effect of high temperature, biaxial stretching on the thermal and mechanical properties of HDPE/MWCNT sheet

High density polyethylene (HDPE)/multi-walled carbon nanotube (MWCNT) composites containing 4 wt% MWCNTs were prepared by melt mixing followed by compression moulding into sheet. Compression moulded sheets were heated to just below the melting temperature and biaxially stretched at ratios (SRs) of 2, 2.5 and 3.0. The effect of stretching on the thermal and mechanical properties of the sheet was studied by differential scanning calorimetry (DSC) and tensile testing. DSC results show that the crystallinity of all the stretched samples increases by approximately 13% due to strain induced crystallization. The melting temperature of the biaxially stretched samples increases only slightly while crystallization temperature is not affected. Tensile test results indicate that at a SR of 2.5 the elastic modulus of the stretched composites increases by 17.6% relative to the virgin HDPE, but the breaking strength decreases by 33%. While the elastic modulus and breaking strength of the HDPE/MWCNT samples continue to increase as SR increases they drop off after a SR of 2.5 for the virgin HDPE. This is probably due to the constraining influence of the nanotubes preventing the relaxation of polymer chains caused by adiabatic heating at high SRs. The addition of MWCNTs results in significant strain hardening during deformation. While this will lead to increased energy requirement in forming it will also result in a more stable process and the ability to produce deep draw containers with more uniform wall thickness

COP and clathrin-coated vesicle budding:different pathways, common approaches

Vesicle and tubule transport containers move proteins and lipids from one membrane system to another. Newly forming transport containers frequently have electron-dense coats. Coats coordinate the accumulation of cargo and sculpt the membrane. Recent advances have shown that components of both COP1 and clathrin-adaptor coats share the same structure and the same motif-based cargo recognition and accessory factor recruitment mechanisms, which leads to insights on conserved aspects of coat recruitment, polymerisation and membrane deformation. These themes point to the way in which evolutionarily conserved features underpin these diverse pathways.