Thermal,swelling and stability kinetics of chitosan based semi-interpenetrating network hydrogels

The present study is focused on studying the swelling kinetics, thermal and aqueous stabilities, and determination of various forms of water in the chitosan (CS) and polyacrylonitrile (PAN) blend and semi-interpenetrating polymer network (sIPN). CS/PAN blend hydrogel films were prepared by solution casting technique. The blend film with optimum swelling properties was selected for the synthesis of sIPN. CS in the blend was crosslinked with the vapors of Glutaraldehyde (GTA) to prepare sIPN. The fabricated CS/PAN blend and sIPN hydrogels films were characterized with Fourier transform infrared (FTIR), thermal gravimetric analysis (TGA) and field emission scanning electron microscope (FESEM). The kinetics of swelling, bound and unbound waters and aqueous stability were determined experimentally. FESEM showed good miscibility between CS and PAN, FTIR showed no chemical interaction between CS and PAN; however, it did show a doublet for the sIPN, TGA showed improved thermal stability and swelling kinetic followed second order kinetics. The degree of swelling of the sIPN hydrogels samples at room temperature varied from ~2200 % (with a fair degree of stability (~30 %)) to ~1000 % (with high degree of aqueous stability (43 %)) with increase in the crosslinking time. The calculated unbound water (W_UB) max., for the blend was 52.3 % whereas for the bound (W_B) the max., was 41.9 %. However, for sIPN hydrogel films, the W_UB water decreased (max. 21.0 %) where as the W_B increased (max. 52.0 %). The decrease in W_UB and increase in the W_B is attributed to the formation of a compact structure and increase in the contact area between the water and polymers in sIPN hydrogels due to the induction of new water contacting point in these hydrogel films, respectively.     

Association between insecticide use and greenhouse whitefly (Trialeurodes vaporariorum westwood) resistance to insecticides in hawaii

Susceptibility to acephate, methomyl, and permethrin was determined with laboratory bioassays for adults of greenhouse whitefly, Trialeurodes vaporariorum Westwood, from 12 to 14 sites in Hawaii. Comparisons at LC₅₀ showed up to 42-fold resistance to acephate, 36-fold resistance to methomyl, and 8-fold resistance to permethrin. Higher levels of resistance to acephate and methomyl than to permethrin are consistent with greater use of organophosphates and carbamates than pyrethroids by growers. Insecticide use varied from 1 to 98 insecticide sprays per site per season. Significant positive associations between LC₅₀ for each insecticide and frequency of application of the same insecticide were found across sites. This finding suggests that local variation in insecticide use was an important cause of variation in susceptibility.     

Electrical stimulation of lumbar spinal nerve roots in dogs

The aim of this study was to test the applicability of electrical stimulation of lumbar spinal nerve roots and obtain normative electrical root stimulation (ERS) data for L7 nerve root and sciatic nerve in dogs. For that purpose ERS and sciatic nerve stimulations were performed consecutively, in totally 40 healthy dogs. ERS was applied in the L7/S1 intervertebral space via monopolar needle electrodes. Muscle responses were recorded from the gastrocnemius muscles on the left and right hind limbs. Sciatic nerve stimulation was performed at the greater trochanter level on the left hind limb, with records obtained from the left gastrocnemius muscle. Mean root latencies of the left and right side were 5.22?±?0.49 ms and 5.29?±?0.53 ms, respectively. There was no significant difference in root latency between the right and left sides. The mean terminal latency was 3.82?±?0.46 ms. The proximal motor nerve conduction velocity of the sciatic nerve was 63.15?±?3.43 m/s. The results of this study show that ERS provides objective data about the integrity of lumbar spinal nerve roots by evaluating the entire population of motor fibres and total length of the motor axon in dogs. ERS can be considered a useful diagnostic method for confirmation of diagnoses of lumbosacral diseases.     

氮钾肥、密度对稻纹枯病进展影响的定量效应

采用回归通用旋转设计方法试验,组建了以水稻纹枯病进展速率(R)为目标函数的数学模型:结果表明:对纹枯病进展速率的影响是氮量>密度>钾肥,其中以施氮量为关键因素;对病害进展速率影响的交互因素是氮量和钾肥。经模型的模拟优化和仿真,在试验幅度内,每亩施纯氮量最高,钾肥用量最小,密度最大的情况下,病害进展速率最大;在施氮量最小、钾肥量偏低、密度最小的情况下,病害进展速率最小(最优)。     

The efficacy of ivermectin and levamisole against natural Nematodirus spathiger infection in the Arabian sand gazelle (Gazella subgutturosa marica) and the Arabian mountain gazelle (Gazella gazella) in Saudi Arabia

The efficacy of two broad spectrum anthelmintics (Ivermectin and Levamisole) against the nematode Nematodirus spathiger in the reem (Arabian sand gazelle) and idmi (Arabian mountain gazelle) at King Khalid Wildlife Research Centre (KKWRC) was determined. Gazelles of both species naturally infected with N. spathiger were each divided into 3 groups. One group was treated with Ivermectin, the other group with Levamisole and the last group was left as untreated control. Faecal egg counts were employed to determine the efficacy of the two drugs against N. spathiger infection in both gazelle species. Reduction in arithmetic mean faecal egg counts achieved by Ivermectin and Levamisole in the reem gazelles was 94% and 89.3%, respectively. The reduction in the idmi gazelles was 97.2% and 96.4%, respectively. Hence, both anthelmintics appeared to be more effective in the idmi gazelles than in the reem gazelles, however, there was no significant difference in the faecal egg reduction tests in both animal species.     

品种和氮肥对早稻纹枯病影响的定量研究

分别研究了品种、施氮量及其互作对早稻纹枯病的影响。结果表明:纹枯病的发展随施氮量的增加而加重,施氮量(N)与病害发展速率比值(RR)关系模型是:RR=1.07899/[1+1.21482EXP(-0.22775*N)]。纹枯病对氮量的灵敏点在每亩施纯氮7.5—12.5公斤内;品种间抗感差异明显,其感病程度可分为三类,各类品种系数可互换;品种与施氮量互作对病情发展影响显著,施氮量对品种抗感性有一定影响,组建了各类品种系数与施氮量关系的数学模型。     

The haematological and biochemical effects of the gastrointestinal nematodes prevalent in camels (Camelus dromedarius) in central Saudi Arabia

Coprological examinations on 1200 Najdi camels (Camelus dromedarius) in the Gassim region of central Saudi Arabia between October 1992 and September 1993 revealed the presence of strongyletype, Nematodirus and Strongyloides eggs. In addition, examination of the gastrointestinal tracts of 240 camels slaughtered in different abattoirs in the Gassim region from March to August 1994 revealed 11 species of helminths. Infection with gastrointestinal trichostronglyes resulted in normocytic, normochromic anaemia. Adult infected camels showed leukocytosis, a decrease in total serum protein concentration and increases in blood urea concentration and in serum creatine phosphokinase activity.Abbreviations ALP alkaline phosphatase - AST aspartate aminotransferase - CPK creatine phosphokinase; epg, eggs per gram - GGT gamma-glutamyl transferase - Hb haemoglobin - MCV mean corpuscular volume - MCHC mean corpuscular haemoglobin concentration - PCV packed cell volume - RBC red blood cell