斜发沸石的水热合成和离子交换性能及其在CH_4/N_2分离中的应用

以氢氧化铝为铝源,硅溶胶为硅源,通过水热法合成斜发沸石,采用XRD、TEM、BET、FT-IR、TG、^(29)Si NMR等手段考察了OH^-/Si的摩尔比、晶化时间和晶化温度等合成参数对其结构和CH_4/N_2分离性能的影响。基于晶化动力学曲线,由阿伦尼乌斯方程导出诱导期和生长阶段的表观活化能值,分别为91.5和7.2 kJ/mol。通过水溶液离子交换工艺分别获得Ca型或K型斜发沸石,并初步探讨了离子交换前后斜发沸石对CH_4/N_2的分离性能。结果表明,斜发沸石对CH_4/N_2的平衡选择性依赖于交换阳离子电荷类型,数量及其在骨架中的分布,其中K型斜发沸石分离效果较好,有望用于煤层气回收。

Factors influencing hybrid maize farmers' risk attitudes and their perceptions in Punjab Province,Pakistan

Hybrid maize farmers have to face diverse kinds of climate, biological, price and financial risks. Farmers＇ risk perceptions and risk attitudes are essential elements influencing farm operations and management decisions. However, this important issue has been overlooked in the contemporary studies and therefore there is a dearth of literature on this important issue. The present research is therefore, an attempt to fill this gap. This study aims to quantify hybrid maize farmers＇ perceptions of disastrous risks, their attitudes towards risk and to explore the impacts of various farm and farm household factors on farmers＇ risk attitudes and risk perceptions. The present study is conducted in four hybrid maize growing districts of Punjab Province, Pakistan, using cross-sectional data of 400 hybrid maize farmers. Risk matrix and equally likely certainty equivalent （ELCE） method are used to rank farmers＇ perceptions of four catastrophic risk sources including climate, biological, price and financial risks and to investigate farmers＇ risk aversion attitudes, respectively. Furthermore, probit regression is used to analyze the determinants affecting farmers＇ risk attitudes and risk perceptions. The results of the study showed that majority of farmers are risk averse in nature and perceive price, biological and climate to be potential sources of risks to their farm enterprise. In addition, analysis divulges that distance from farm to main market, off-farm income, location dummies for Sahiwal and Okara, age, maize farming experience, access to extension agent, significantly （either negatively or positively） influence farmers＇ risk attitudes and risk perceptions. The study delivers valuable insights for farmers, agricultural insurance sector, extension services researchers and agricultural policy makers about the local understanding of risks to hybrid maize crop in developing countries, like Pakistan, and have implications for research on farmers＇ adaptation to exposed risks.

Maize production under risk:The simultaneous adoption of off-farm income diversification and agricultural credit to manage risk

Farmers in Pakistan continue to produce maize under various types of risks and adopt several strategies to manage those risks. This study is the first attempt to investigate the factors affecting the concurrent adoption of off-farm income diversification and agricultural credit which the farmers use to manage the risk to maize production. We apply bivariate and multinomial probit approaches to the primary data collected from four districts of Punjab Province in Pakistan. The results show that strong correlations exist between the off-farm diversification and agricultural credit which indicates that the use of one risk management strategy leads to another. The findings demonstrate that education, livestock number, maize farming experience, perceptions of biological risks and risk-averse nature of the growers significantly encourage the adoption of diversification as a risk management tool while farm size inversely affects the adoption of diversification. Similarly, in the adoption equation of credit, maize farming experience, farm size, perceptions of price and biological risks and risk attitude of farmers significantly enhance the chances of adopting agricultural credit to manage farm risks. These findings are important for the relevant stakeholders who seek to offer carefully designed risk minimizing options to the maize farmers.

Evaluations of physico-chemical properties of TiO_(2)/clinoptilolite synthesized via three methods on photocatalytic degradation of crystal violet

Different preparation routes for TiO_(2)-supported natural and synthetic clinoptilolite(TiO_(2)/CP)composites were thoroughly investigated on the basis of sol-gel,hydrothermal,and in-situ hydrothermal methods.The micro-structural features and physicochemical properties of resultant TiO_(2)/CPs were characterized via X-ray diffraction patterns,scanning(transmission)electron microscope images,Fourier transform infrared spectra,inductively coupled plasma-optical emission spectrometry methods,BET-isotherms,UV-visible spectra,and surface charge potential distributions.The results showed that in-situ hydrothermal method led to well dispersions of loaded-TiO_(2) particles on the surface of leaf-like CP,while obviously aggregated TiO_(2) on a relatively distorted structure of CP was obtained using sol-gel and hydrothermal methods.Their adsorptive and photocatalytic efficiencies for removal of crystal violet(CV)dye in aqueous solution were also explored under UV-irradiations.The results demonstrated that TiO_(2)/CPs synthesized via sol-gel and in-situ hydrothermal methods presented the excellent performances with 98% removal efficiencies as compare to the bare commercial TiO_(2) which achieved 53%removal of CV dye.While,the in-situ hydrothermally synthesized TiO_(2)/CPs were the best due to their moderate energy cost,highest adsorption capacities and removal efficiencies.Particularly,the synthetic CPs as supports exhibited synergetic photocatalytic activities for the degradation of CV dye,which is attributed to their high surface areas,better adsorption capability,and fine dispersion of TiO_(2) particles.Adsorption and degradation kinetics of CV dye were found to follow the pseudo-second and pseudo-first order models,respectively.

Comparative Study on Quantitative and Qualitative Characters of Different Oat (<i>Avena sativa</i>L.) Genotypes under Agro-Climatic Conditions of Sargodha, Pakistan

An experiment was conducted to compare the forage yield and qualify of oat (Avena sativa L.) genotypes (F-413, SGD-46, F-408, F-301, SGD-2011, SGD-3, SGD-37, SGD-40, SGD-5 and S-2000) at Fodder Research Institute, Sargodha, Pakistan during the year 2011 to 2012. Experiment was laid out in randomized complete block design (RCBD) having three replications and a net plot of size 1.6 × 5 m. The varieties were differed significantly (P ≤ 0.05) in yield, growth and quality parameters. The variety SGD-40 produced significantly higher green forage yield (80.00 t·ha-1) and dry matter yield (10.95 t·ha-1) than other varieties due to taller plants (145.73 cm), more number of tillers (7.78 m-2) and leaf area per plant (95.08 cm2). It also had the highest crude protein percentage (13.84%). Correlation analysis of quantitative and qualitative characters indicated the strongly positive association of green forage yield with dry matter, crude protein and ash content. While green forage yield was negatively correlated with the number of tillers per plant, keeping in view both forage yield and crude protein contents the genotype SGD-40 grown under the condition of Sargodha (Pakistan).

Schools' Flood Emergency Preparedness in Khyber Pakhtunkhwa Province, Pakistan

Pakistan is highly exposed to climate-induced disasters, especially floods. Flooding history shows that educational establishments have been disproportionately hard-hit by flooding events. In Pakistan, school safety and preparedness is still a choice, rather than a mandatory requirement for all schools. But schools in Pakistan do have a responsibility to keep safe the students in their care,especially during and after the catastrophic events. This implies the need to maintain the environment in and around school property, so as to minimize the impacts of floods and to have the mechanisms in place to maximize a school's resilience. This study examined the emergency preparedness activities of 20 schools in four districts of Khyber Pakhtunkhwa Province that had recently been severely affected by floods. Through face to face interviews and a structured questionnaire(n = 100) we collected data on the four pillars of emergency preparedness:emergency planning, preparation measures, safe school facilities, and hazard education and training. The study revealed that the majority of the sample schools hadexperienced more than one natural hazard-induced disaster,predominantly flooding, yet despite this had not undertaken adequate emergency preparedness activities. There are particular gaps with regard to plans for students with disabilities, the continuity of school operations after a disaster,the presence of maps to identify evacuation routes, the availability of emergency equipment and resources, disaster preparedness guidelines, and psychological first aid and crisis counseling. The strengths, weaknesses, opportunities,and threats analysis that our researchers carried out indicates that, although schools in the survey have taken many steps towards flood preparedness, many weaknesses still exist and there remain significant opportunities to strengthen the preparedness level of many schools. The goal of this study is to inform policy decisions that improve school safety in Pakistan and to suggest the priority areas for future school disaster preparedness and management efforts.