Cyanogenic,carotenoids and protein composition in leaves and roots across seven diverse population found in the world cassava germplasm collection at CIAT,Colombia

The objective of this study was to characterise the nutritional potential of leaves and identify a diversity centre with low cyanide and high nutrient content among 178 Latin American cassava genotypes. This field-based collection represents the seven diversity centres, held at The International Center for Tropical Agriculture (CIAT Palmira, Colombia) by the Cassava Program. The cyanide, all-trans-β-carotene and lutein concentrations in cassava leaves ranged from 346 to 7484 ppm dry basis (db), from 174–547 μg g⁻¹ db and 15–181 μg g⁻¹ db, respectively. Cassava leaves also showed significant levels of essential amino acids leucine, lysine, phenylalanine, valine and threonine, and average total protein content of 26.24 g 100 g⁻¹ db. Among seven diversity centres, South American rainforest group showed low cyanide and high carotene content in leaves. In addition, VEN77 and PAN51 genotypes stood out for having low cyanide in leaves and roots and high carotene in leaves. This genetic diversity can be used to select high potential progenitors for breeding purposes.     

Fatigue in bamboo

This paper describes the results of an experimental programme to determine the fatigue behaviour of bamboo. Bamboo is subjected to cyclic loading, both in the plant itself and subsequently when the material is used in load-bearing applications in the construction industry. However, there is currently no data in the literature describing fatigue in this material. We found that sections of bamboo culm loaded parallel to the culm axis did not undergo fatigue failure: samples either failed on the first loading cycle, or not at all. By contrast, fatigue was readily apparent in samples loaded in compression across the diameter of the culm. The number of cycles to failure increased as the cyclic load range decreased in a manner similar to that found in many engineering materials: fatigue occurred at applied loads as small as 40% of the ultimate strength. Two different species of bamboo were tested and found to have different ultimate strengths but similar high-cycle fatigue strengths. Finite element analysis was used to help understand the progression of fatigue damage and the effect of stress concentration features. Some tentative design rules are proposed to define stress levels for the safe use of bamboo, taking fatigue into account.     

Bamboo biochar-catalytic degradation of lignin under microwave heating

Abstract

Lignin biochar-catalytic depolymerization using biochar Fe-600, Fe-800, Ni-600, Ni-800 catalysts under microwave-heating (180?°C for 30?min) was explored in an ethanol/formic acid (1:1) media. Non-catalyst depolymerization was also studied and compared with the biochar-catalysts results. Characteristics of the bio-char catalysts were analyze by BET, XRD, and FT-IR. GPC, FT-IR, and MALDI-TOF MS spectrometry were also used to characterize the depolymerization products. The experimental results showed that the S_BET, V_t, and V_mec and average pore diameter of the biochars are considerably dependent on the preparation temperature and type of cation (Ni²⁺ or Fe³⁺). The maximum yield of bio-oil product was obtained as 85?wt% with the addition of biochar Ni-600 and the total amount of oligomers or monomers with a molecular weight of 164 to 446 reaches 80.4%.     

Potential of in-field and low temperature drying for reducing chlorophyll contents in canola (Brassica napus L)

The presence of green seeds in canola arises primarily from the common practice of swathing the crop prematurely in order to hasten the harvesting process and reduce the shattering losses. The purpose of this study was to determine the effects of plant maturity, swathing and duration of swathing on moisture and chlorophyll contents of canola seeds (Brassica napus L cv Westar), and to determine the effect of canola conditioning with air at 25·C and 90% RH on chlorophyll content. A standing crop of canola with 50% to 10% (w/w) seed moisture content was sampled at regular intervals in two consecutive harvest years (1989 and 1990). Canola was also swathed at three different stages of maturity, and seeds were checked for chlorophyll at 2-3 day intervals and compared with chlorophyll contents of seed from standing crop. Samples were conditioned in a thin layer with air at 25·C and 90% RH for 24 h, and chlorophyll was determined before and after conditioning. The chlorophyll of seeds decreased exponentially with a decrease in moisture content. Conditioning canola seeds decreased chlorophyll content by an average of 16% (SD = ± 12%).     

Dynamics of photosynthetic pigments in an Andean lake in Colombia

Guatavita Lake is a small, sheltered tropical high mountain lake located in the Colombian Andes, with a closed watershed and a maximum depth of 25 m. It is the freshwater source for human consumption in nearby small towns, as well as being a site of cultural value for the country, as it was a sacred place to indigenous peoples until about five centuries ago. As the structure and function of this aquatic ecosystem is poorly understood, this study provides initial knowledge on its phytoplankton biomass dynamics, which should be useful in designing efficient management plans with environmental baseline information for similar lakes elsewhere. Physical and chemical data, and photosynthetic pigment concentrations, were measured for the period November 1999–November 2000 at the central vertical axis of Guatavita Lake. The vertical profile of the chlorophyll‐a concentration was closely related to the dissolved inorganic nitrogen concentrations and the thermal stratification characteristics. The maximum chlorophyll‐a concentration in the metalimnion was recorded for the thermal stratification period (November 1999–June 2000). Deepening of the maximum chlorophyll‐a concentration began in February, continuing to June, when it reached its lowest value at the 15 m depth. The phytoplankton biomass values showed an increment within the entire water column at the beginning of the mixing period (July). The relation between the metalimnetic peak of chlorophyll‐a and the dissolved inorganic nitrogen concentration suggests the growth of the phytoplankton community is limited mainly by the availability of nitrogen.     

湖泊藻类叶绿素-α和悬浮物浓度的高光谱定量遥感模型研究

本文利用地物光谱仪对太湖水体进行了光谱测量和同步采样分析，对获得的数据尝试用光谱分离法进行分析，从中分离出蓝藻和悬浮物的特征波峰，建立波峰高度与同步水质采样得到的叶绿素-α浓度和悬浮物浓度的对应关系，得出其遥感定量反演算法，并实际应用在OMIS成像光谱仪图像上．     

气相色谱法测定新鲜茶叶中有机氯农药残留量

对新鲜茶树叶中六六六和滴滴涕共八种异构体的残留量进行测定,与同地点成品茶叶农药残留量相比较基本无差异。本法检测限为>1.8ng/g,回收率为78.2％-99.0％,相对标准偏差<10.0％。     

Rapid determination of chlorophylls in vegetable oils by laser-based fluorometry

The presence of chlorophylls in vegetable oils is considered undesirable due to their adverse effects on oxidative deterioration, bleachability and hydrogenation. The usual methods for determination of chlorophylls in vegetable oils are absorption spectrophotometry, fluorometry and liquid chromatography using fluorescence detectors. This paper outlines a fluorometric method using a laser as the excitation source. The chlorophylls in crude palm oil, rapeseed oil, soya bean oil and olive oil were determined directly by laser-based fluorometry using (a) a helium-neon laser (632-8 nm, 5 mW) as the excitation source and an optical-multichannel analyser (OMA) with an intensified diode array as the detector, and (b) a helium-neon laser and a photomultiplier tube as the detector. The method is especially suitable for the detection of chlorophylls in crude palm oil since no pre-extraction step is required. The levels of chlorophylls measured in vegetable oils using the laser technique was also compared against values obtained by conventional spectrophotometric methods. The simplicity and rapid quantification of laser based fluorometry suggest that this technique can be readily applied to the detection or a wide variety of fluorescing species in vegetable oils.     

Modified Atmosphere Packaging Affects Ascorbic Acid, Enzyme Activity and Market Quality of Broccoli

Reduced ascorbic acid (RAA) content, total chlorophyll and green color retention, enzyme activities and texture changes were followed in broccoli spears packaged in polymeric film and nonpackaged during 96 hr storage (10°C). Concentrations within packages monitored by gas chromatography were (CO₂,) 8% and (0²) 10%. RAA retention, moisture content, total chlorophyll and color retention were greater in packaged broccoli. No differences were found between packaged and nonpackaged broccoli for ascorbate oxidase and peroxidase activities, or texture.     

制丝线FT651型叶片垂直分片机控制系统的改进方案

针对叶片垂直分片机使用过程中出现的劈坏烟箱、纵向移动刀架失控和系统无报警功能等问题,分析故障产生的原因,并对其控制系统进行改进。