Preliminary study of flow regimes and stream water residence times in multi-scale forested watersheds of central Cambodia

To elucidate the water cycle in lowland forests of the Mekong River basin, our research group established four experimental watersheds in the Stung Chinit River basin in Kampong Thom Province, Cambodia. The drainage areas of these experimental watersheds ranged from small (4 km²) to mesoscale (3,659 km²). Here, we present the first preliminary results of our rainfall-discharge observations and analyses of temporal variations of stable isotope ratios in rainfall, stream water, and groundwater. This paper focuses on the following three main topics: annual rainfall, discharge, and water balance; stormflow generation and dominant flow pathways; and flow regimes and stream water residence times. All stream water residence times (τ = 1.7–7.5 months) for the four experimental watersheds were shorter than the residence time of the groundwater (τ = 9.4 months) through the soil and regolith layers, implying that the stream waters consisted of not only the groundwater-flow component, but also younger-aged flow components such as saturation-excess overland flow. The smallest (4 km²; O Toek Loork) watershed had longer residence time (τ = 7.5 months) than the three larger watersheds (126–3,659 km²; τ = 1.7–3.9 months). This may suggest differing contributions of the groundwater and younger-aged flow components in the stream water in each watershed. Our approach of multi-scale watershed observation might better contribute to the needs of physically based models and aid in predictions for ungauged basins.     

Chipping performance of three processing potato cultivars during long-term storage at two temperature regimes

Three potato cultivars (Russet Burbank, Norchip, and Gemchip) grown with nitrogen applied at three rates were stored at two temperature regimes (Treatment 1: 13 months at 10 CTreatment 2: 1 month at 10 C; followed by a 1 C decrease per week until tubers were 4 C; followed by 6 months at 4 C; followed by a 1 C increase per week until tubers were 10 C; followed by 3 months at 10 C). Tuber chemical components and potato chip appearance were measured at harvest and after 3, 6, 9, 11, 12, and 13 months; these measurements were performed within 24 hours of the time potatoes were removed from storage. Sugar responses (tuber glucose, fructose, sucrose) and potato chip appearance were affected by cultivar over time in both years and storage temperatures. Russet Burbank tubers displayed a significantly higher glucose forming potential and produced darker appearing chips, regardless of storage temperature or time in storage, compared to Norchip and Gemchip. Potatoes receiving a cold-storage treatment contained less sugar and produced lighter appearing chips after 12 months storage compared to tubers stored at a constant 10 C for 12 months. The linear association between tuber chemical components and potato chip appearance varied with storage temperature.     

适合马铃薯晚疫病菌生长的培养基改良试验

由致病疫霉Phytophthora infestans引起的晚疫病是全球第一大作物病害,对马铃薯生产危害非常严重。在对该病菌的研究中确定适宜的培养基是比较关键的一环。本文采用完全随机设计,将晚疫病菌接种到黑麦与胡萝卜不同混合比例的5种培养基上,通过隔日调查的方法,比较其菌落生长直径的大小和产孢量的多少,以此作为衡量5种培养基培养效果的指标。研究结果表明:黑麦与胡萝卜的比例为1:1时,晚疫病菌的菌落生长速度最快,产孢量最多,培养效果最好。因此,可以利用这种培养基来培养马铃薯晚疫病菌,这对开展晚疫病菌的进一步研究具有一定的实际意义。     

Modification of natural bamboo fibers for textile applications

Natural bamboo fibers have excellent properties suggesting that there is a good potential for them to be used in textiles; however, they have not received the attention that they deserve owing to their coarse and stiff quality. Therefore, a chemical method for extraction and modification of natural bamboo fibers for textile end uses were developed and optimized in this paper. The quality of natural bamboo fibers were characterized by their chemical composition, linear density, and tenacity. Experimental results show that the modified bamboo fibers are finer, with significant lower content of noncellulosic substances. The processing parameters are optimized as: 20 g/l NaOH, 3 g/l Na₅P₃O₁₀, 5 g/l Na₂SO₃, 3 g/l penetrating agent, with a fiber to liquid ratio of 1:10, at 100 °C for 2 h, and the bamboo fiber thus produced has cellulose amount of 73.25 %, fineness of 3.26 tex, average length of 44.5 mm, breaking elongation of 2.8 % and tenacity of 2.41 cN/dtex. The result of this study may offer a possibility of developing natural bamboo fibers into practical applications in textiles.     

New One-Pot Methodologies for the Modification or Synthesis of Alkaloid Scaffolds

There are several avenues by which promising bioactive natural products can be produced in sufficient quantities to enable lead optimization and medicinal chemistry studies. The total synthesis of natural products is an important, but sometimes difficult, approach and requires the development of innovative synthetic methodologies to simplify the synthesis of complex molecules. Various classes of natural product alkaloids are both common and widely distributed in plants, bacteria, fungi, insects and marine organisms. This mini-review will discuss the scope, mechanistic insights and enantioselectivity aspects of selected examples of recently developed one-pot methods that have been published in 2009 for the synthesis of substituted piperidines, quinolizidines, pyrrolidines, hexahydropyrrolizines, octahydroindolizines and γ-lactams. In addition, progress on the synthesis of β-carboline (manzamine) alkaloids will also be discussed.     

龙须草叶面积测定方法的初步研究

对人工栽培的不同生长时间龙须草的叶面积测定方法进行了研究.利用LI-3000叶面积仪和生产上常用的长宽法进行比较分析,求得用长宽法测量龙须草叶面积的矫正系数K=0.67,经过相关分析,认为所得K值是值得推荐的.     

A method for the rapid estimation of glycoalkaloids in potato tubers

A rapid method for estimating glycoalkaloid levels in potato tubers has been developed. It is basically a screening technique whereby large numbers of samples can be assigned to categories of alkaloid level such as very low, low, medium and high. The elapsed time is typically four hours and the per sample time 12 to 15 minutes when large numbers are run. Weighed tuber samples are cut up and blended with a volume (ml) of extracting solution equal to the weight of the sample in g. After blending for four minutes, a portion of the extract is poured on to a fluted filter. An aliquot of the filtrate is treated with an antimony trichloride reagent and the color is read at 550 nm after 15 min.     

Optimization of a profile extrusion die for flow balance

One of the problems encountered in the extrusion of plastic profiles is unbalanced flow at the die exit. It causes deformation of the extrudates at ambient and precludes the material transition through remaining stages of production process (calibration, cooling sections etc). In this paper, geometric parameters of a profile extrusion die are optimized using several objective function definitions by Simulated Annealing-Kriging Meta-Algorithm. Objective functions are defined based on the uniformity of velocity distribution at the die exit. For this, Computational Fluid Dynamics (CFD) simulations are performed for N=70 die geometries. Appropriate geometric parameters (t and L) of the die are variables for the optimization problem.     

Clinitest: A simple technique for estimation of reducing sugar content of potatoes

The Clinitest method, originally devised to test urine of diabetic patients, proved to be effective for estimating reducing sugar content of tuber juice. Data obtained by the Clinitest method correlated well with data obtained from the same tubers by the analytical dinitrophenol method and by chip color numbers as determined by Agtron ranges. Simplicity in operation, low cost, and quick results are the main attributes of this method that is potentially useful to the potato industry.     

Modification of polyethylene-polypropylene fibers by emulsion and solvent radiation grafting systems for boron removal

Preparation of boron-selective adsorbent was carried out by radiation induced grafting of glycidyl methacrylate (GMA) onto polyethylene-coated polypropylene (PE-PP) nonwoven fabric in emulsion or solvent medium followed by immobilization of N-methyl-D-glucamine (NMDG). Adsorbent precursors with 180 % degree of grafting (DG) were obtained by applying reaction parameters comprising 20 kGy dose, 5 % monomer concentration and 1 h reaction time in emulsion compared to 30 kGy, 10 % and 3 h in solvent medium. A glucamine density of 2.2 mmol/g could be imparted to the obtained adsorbents. The emulsion-mediated grafting was found more efficient and economical for preparation of boron chelating adsorbents.     

Modification of serological techniques and their evaluation for detection of potato viruses in seed certification related activities

Development of alternative serological techniques to ELISA for detection of potato viruses offers advantages for monitoring virus incidence and for seed potato certification systems. Several trials showed that multiplex tissue print immunoassay (TPIA) and dot blot immunoassay (DBIA) might represent fast, practical, and sensitive alternatives for the detection of: Potato leaf roll virus (PLRV), Potato virus S (PVS), Potato virus X (PVX) and Potato virus Y (PVY), from green and/or tuber tissues. In TPIA, the specific precipitation patterns in infected tissues of leaf petioles or stem cross sections, observed with each virus, allowed identification of the specific virus or mixed infections in a single multiplex assay. For detection of PVY in green tissues, DBIA was shown to be over 50 times more sensitive than ELISA. TPIA and ELISA from the tuber stem end or from eyes might be used for rapid detection of PVY and PVS in seed potato tubers without prior germination. PVS was evenly distributed in potato tuber tissue, while PVY was localized in the vascular tissue beneath the epidermis, with irregular distribution along the periphery of the potato tuber. For laboratories in developing countries lacking time and facilities for tests based on tuber germination, monitoring for PVS and PVY using TPIA in tuber tissue may be a suitable alternative to ELISA.     

Studies on the estimation of sampling error for leatherjackets (Tipula spp.) in grassland

Leatherjacket populations were sampled from 20 sites in Northern Ireland by collecting 10 cm diameter soil cores and wet sieving. The sample variances were linearly related to the sample means. Up to a mean of 1.14 leatherjackets per core, populations could be described by the Poisson distribution. Negative binomial distributions could also be fitted to data where the sample variance was greater than the sample mean. A strong curvilinear relationship was found between the sample mean and the proportion of cores containing leatherjackets. The raw data were used to generate a series of equations which in turn gave rise to a function linking frequency, sample mean and sample size.
The implications of these results are discussed in relation to population estimation and advice to farmers.     

A critical review of remote sensing and other methods for non-destructive estimation of standing crop biomass

Several different techniques for the non-destructive estimation of pasture or range biomass are critically reviewed and compared to remote sensing methods. Similarities and differences between the visual estimation procedure, β-attentuation, capacitance meters, weighted disc, and spectral methods are discussed in terms of accuracy, time, ease of operation, operational constraints and calibration procedures. No one technique has been shown to be superior across the board to the other techniques reviewed for ground-based biomass estimation. A discussion of the strengths and weaknesses of each non-destructive method allows for the selection of the technique most suited to a particular application.     

Development of mathematical models and estimation for the mechanical properties of organic fiber reinforced polyester composites

Organic fiber from animal waste was used for the development of environmentally friendly animal fiber based polyester composites using cow hair. The cow hair fibers were cut into 10 mm lengths to produce the needed short fiber for random dispersion in the matrix. Before use, some of the fibers were treated with sodium hydroxide for fiber surface modification while some were left as untreated. Composites were developed using predetermined proportions of the fibers in an open mould production process. Samples were formed into tensile and flexural shape in their respective moulds and were stripped off the moulds after curing while further curing was ensured for 27 days before testing. Tensile and flexural properties of the cow hair fiber reinforced polyester composites were evaluated from which it was discovered that the untreated fiber reinforced composites possess better enhancement of mechanical properties compared to the treated fiber reinforced composites and the unreinforced polyester material. Mathematical models for the tensile and flexural properties were developed using statistical packages and estimation using developed software. The developed models revealed high degree of correlation between the experimental values and the predicted values. This denotes that the models can be used to predict the mechanical properties of cow hair reinforced polyester composites for various reinforcement contents.     

Estimates of sample size for detection and estimation of incidence and severity of corky ringspot of potato

A computer program was developed to simulate the random collection of tuber samples from potato fields with corky ringspot (CRS). Tubers were harvested from 16 plots in the 1993–94 and 1994–95 seasons, and the incidence and severity of CRS symptoms were assessed. Inputs for the program were number of healthy and CRS-affected tubers and severity tuber symptoms from each plot. The output was the mean and the standard error of the mean of disease incidence and severity for 12 different sample sizes. Accuracy and precision for each sample size were estimated to determine sample size. The sample size of 20 tubers was required to detect the presence of CRS in research plots. The binomial distribution was used. With sample sizes greater than 20, the increase in accuracy and precision leveled off regardless of disease incidence and severity values; therefore sample sizes greater than 20 may be unwarranted for evaluation of chemical control tests.     

The mode of operation of a regulating reservoir for effective use of river flow

In the absence of a reservoir on the downstream side, a river flow that increases temporarily by rainfall cannot be stored and discharged apart from requirements in a command area. This unused water (excess water) occurs to some extent even in a drought year and making effective use of this supply is considered as one of the countermeasures for water shortage. Setting up a regulating reservoir on the upstream side of head works is regarded as one of the methods for making effective use of excess water. The inflow to the river and water delivery loss occurred from rainfall are stored in the regulating reservoir and supplied to the command area on the downstream side as agricultural water. An operational method for the regulating reservoir to effectively utilize the excess water was examined for a canal system by simulation. In an investigated area, there was excess water even in drought years, and making use of it through the regulating reservoir whose capacity is smaller compared to that of a dam can become one of the countermeasures for the drought period. The simulation in this study could estimate quantitatively the effect of the regulating reservoir to make the excess water effective.     

Proposal of new return flow analysis by replacement-in-order method for paddy irrigation water

Return flow and repeated use of irrigation water for paddies is the most important issue in the Asian monsoon region, because sometimes this water is applied in greater quantity than that of evapotranspiration plus percolation. A new return flow analysis, the “replacement-in-order method”, which introduces a unique numbering system for very complicated irrigation and drainage networks, is proposed for the main canal with the dual purposes of irrigation and drainage. The method is applied to the Shichika irrigation district in the ordinal (season) irrigation period, resulting in a return flow ratio of 45 % for the entire area. Of this amount, 25 % is available for irrigation again. The remaining 20 % is unavailable, because the return flow discharged directly into a canal lacking a diversion weir in the drainage system, or into the Japan Sea. The return flow ratio is very different at the main canal location, from no return flow to 88 %. With the aid of the above method, theoretical analysis of return flow for paddy irrigation water can be done. This includes the deterministic return flow ratio inside and outside the irrigation area, plus precise information of return flow ratios at various main canal locations and routes of irrigation and drainage water.     

Modification and Characterization of Nano-TiO<Subscript>2</Subscript> for Efficient Fixation on Cotton Fibers

In this paper, a silane coupling agent, 3-aminopropyltriethoxysilane, was reacted with nano-TiO₂ to introduce amino group onto it which was then reacted with trichlorotriazine to obtain a dichlorotriazine functionalized nano-TiO₂ for the firm fixation of it on cotton fibers. The reaction process was monitored by the titration of primary and secondary amino groups, and the reaction conditions were optimized with orthogonal method accordingly. The dichlorotriazine functionalized nano-TiO₂ was reacted with cotton fabric by the nucleophile substitution reaction to afford nano-TiO₂ functionalized cotton fabric, the structure and surface morphology of the nano-TiO₂ finished cotton fibers were studied by FT-TR and SEM. In addition, the fixation duration of the nano-TiO₂ modified cotton was studied according to AATCC test method 61–2010. The results show that the washing fastness of the nano-TiO₂ is excellent.     

A quick method of obtaining samples for the estimation of carbon dioxide,oxygen and volatiles in the potato tuber

A 5 min evacuation technique utilizing the purging effect of steam, and the vacuum produced by its condensation, was used to collect and compare O₂, CO₂, ethanol and ethylene from potato tubers surface treated with substances inhibiting normal respiratory exchange.