Mathematical modeling of an aqueous film coating process in a Bohle Lab-Coater, Part 1: Development of the model

The purpose of this study was to develop a model to predict (1) air and product temperatures, (2) product moisture, and (3) air humidity during an aqueous coating process using a Bohle Lab-Coater. Because of the geometrical properties and the airflow, the drum of the Bohle Lab-Coater can in principle be divided into 2 zones of equal size—the drying and the spraying zones. For each zone, 4 balance equations could be set up describing the change of the air humidity, the product moisture, the enthalpy of the air, and the enthalpy of the product in each zone. For this purpose, knowledge regarding heat and mass transfer and also the motion of the tablets in drums was used. Based on the considerations of the heat and mass transfer, a set of first-order coupled ordinary differential equations (ODEs) was developed. This set of ODEs can be solved numerically. In this part, the development of the model is described in detail, whereas the application of the model can be found in part 2.     

Preparation of surfactant-free nanoparticles of methacrylic acid copolymers used for film coating

The aim of the present study was to prepare surfactant-free pseudolatexes of various methacrylic acid copolymers. These aqueous colloidal dispersions of polymeric materials for oral administration are intended for film coating of solid dosage forms or for direct manufacturing of manoparticles. Nanoparticulate dispersions were produced by an emulsification-diffusion method involving the use of partially water-miscible solvents and the mutual saturation of the aqueous and organic phases prior to the emulsification in order to reduce the initial thermodynamic instability of the emulsion. Because of the self-emulsifying properties of the methacrylic acid copolymers, it was possible to prepare aqueous dispersions of colloidal size containing up to 30% wt/vol of Eudragit RL, RS, and E using 2-butanone or methyl acetate as partially water-miscible solvents, but without any surfactant. However, in the case of the cationic Eudragit E, protonation of the tertiary amine groups by acidification of the aqueous phase was necessary to improve the emulsion stability in the absence of surfactant and subsequently to prevent droplet coalescence during evaporation. In addition, a pseudolatex of Eudragit E was used to validate the coating properties of the formulation for solid dosage forms. Film-coated tablets of quinidine sulfate showed a transparent glossy continuous film that was firmly attached to the tablet. The dissolution profile of quinidine sulfate from the tablets coated with the Eudragit E pseudolatex was comparable to that of tablets coated with an acetonic solution of Eudragit E. Furthermore, both types of coating ensured similar taste masking. The emulsification-evaporation method used was shown to be appropriate for the preparation of surfactant-free colloidal dispersions of the 3 types of preformed methacrylic acid copolymers; the dispersions can subsequently be used for film coating of solid dosage forms. Published: July 28, 2006     

Effect of polymer differences on fungal penetration of hydrogel lenses

Summary Two chemically distinct types of hydrogel lenses, vifilcon A and bufilcon A, each with a water content of 55%, were challenged in a balanced salts solution withAspergillus fumigatus, Cladosporium cladosporioides, Curvularia lunata andFusarium solani. The lenses were cleaned, disinfected and stained after varying periods of incubation and examined with light microscopy and scanning electron microscopy. For three of the four fungi, the bufilcon A lens was more susceptible to fungal attack than the vifilcon A lens.Curv. lunata produced the greatest number of penetration pegs within 72 h for both lens types. Etching of lens surfaces was observed withC. cladosporioides. In general, the susceptibility of a hydrogel lens to penetration with a fungus appeared to vary with the species of fungus and the chemical composition of the lens.     

The combined effects of plasma and hydrogel coating on adhesion of Staphylococcus epidermidis and Staphylococcus aureus to polyurethane catheters

Abstract The adhesion of three Staphylococcus epidermidis and three S. aureus clinical isolates, to uncoated and hydrogel-coated polyurethane catheters was tested, following pretreatment of catheters with human plasma. Plasma significantly decreased the adhesion of S. epidermidis strains to uncoated polyurethane catheters, but had no significant effect on the adhesion to hydrogel-coated catheters. The influence of plasma on adhesion of S. aureus strains to catheters was strain dependent. Plasma significantly increased the adhesion of one strain (SA6) to uncoated catheters. For two other strains (SA3 and SA14) plasma produced no clear effect on their adhesion to uncoated catheters; adhesion values for each strain showed either a small but significant increase or a replicate-dependent increase or decrease. However, plasma significantly increased the adhesion of all S. aureus strains to hydrogel-coated polyurethane catheters. Overall, with the exception of one batch culture of S. epidermidis strain SE3 tested, attachment to plasma-treated hydrogel-coated catheters was statistically significantly lower, by up to 85%, than attachment to plasma-treated uncoated catheters for both S. epidermidis and S. aureus .     

A novel approach in the assessment of polymeric film formation and film adhesion on different pharmaceutical solid substrates

The purpose of this study was to evaluate the nature of film formation on tablets with different compositions, using confocal laser scanning microscopy (CLSM), and to measure film adhesion via the application of a novel “magnet probe test”. Three excipients, microcrystalline cellulose (MCC), spray-dried lactose monohydrate, and dibasic calcium phosphate dihydrate, were individually blended with 0.5% magnesium stearate, as a lubricant, and 2.5% tetracycline HCl, as a fluorescent marker, and were compressed using a Carver press. Tablets were coated with a solution consisting of 7% hydroxypropyl methylcellulose (HPMC) phthalate (HP-55), and 0.5% cetyl alcohl in acetone and isopropanol (11:9). The nature of polymer interaction with the tablets and coating was evaluated using CLSM and a designed magnet probe test. CLSM images clearly showed coating efficiency, thickness, and uniformity of film formation, and the extent of drug migration into the film at the coating interfaces of tablets. Among the excipients, MCC demonstrated the best interface for both film formation and uniformity in thickness relative to lactose monohydrate and dibasic calcium phosphate dihydrate. The detachment force of the coating layers from the tablet surfaces, as measured with the developed magnet probe test, was in the order of MCC>lactose monohydrate>dibasic calcium phosphate dihydrate. It was also shown that the designed magnet probe test provides reliable and reproducible results when used for measurement of film adhesion and bonding strength.     

Effect of hyperthermia on blood constituents in the domestic rabbit (Lepus cuniculus)

1. 1. Effects of exposing rabbits to temperatures 37–50°C on body-core temperature and some blood constituents were investigated.

2. 2. Heat stroke death occurred at or above a critical core-temperature of 43.0°C.

3. 3. Plasma osmolality and levels of glucose, urea and lactate were significantly elevated in hyperthermia.

4. 4. Widespread tissue damage was indicated by increases in plasma activities of glutamate oxaloacetate transaminase (GOT), glutamate pyruvate transaminase (GPT) and creatinine phosphokinase (CPK).

5. 5. The most sensitive indicators of impending heat stroke in heat stressed rabbits were plasma levels or urea, lactate and CPK.

根表铁锰氧化物胶膜对不同品种水稻吸镉的影响

采用土培方法,研究了不同品种水稻吸镉的差异及其与根表铁锰氧化物胶膜的关系,结果表明：不同品种水稻其根膜,根部及地上部含镉量均存在显著性差异,且镉在不同水稻植株体内运输转移能力不同,不同水稻其根表淀积的铁锰氧化物数量也存在显著性差异,根膜及地上部的含镉量与极膜的含铁量均未达到显著性相关,但与根膜的含锰量相关性显著。     

Effect of diets on growth,digestibility, carcass and meat quality characteristics of four rabbit breeds

The current study was conducted to evaluate three diets using four rabbit breeds. A total of 320 male weaned rabbits representing four breeds named V-line, Saudi-1, Saudi-2 and Saudi-3 were randomly distributed into three comparable dietary treatments. Three levels of indigenous feedstuffs (IFS) of 42.5%, 65% or 87.5% (alfalfa hay, barley and wheat bran) were substituted for the same levels of non-indigenous feedstuffs in the diet (corn grain, soybean, molasses, and limestone) to form three diets named D1, D2 and D3, respectively. These dietary treatments were used to evaluate post-weaning growth performance, feed intake, feed conversion, carcass and lean composition, and nutrients digestibility in four rabbit breeds.Partial replacement of IFS with non-indigenous feedstuffs attained significant increase in growth performance. The diet containing 87.5% IFS led to significant increase in daily weight gains by 8.4, 4.0, 8.1, 6.2 and 6.7 g at age intervals of 5–6, 7–8, 9–10, 10–11 and 11–12 weeks compared to the control diet, respectively. The diet containing 87.5% IFS showed a significant reduction in feed conversion ratio compared to control diet during the experimental periods. The diet containing 65% IFS showed significant increases in pre-slaughter weight (112 g) and hot carcass weight (89 g), while dressing percent, offal weight and percent, and non-carcass weights and percentages (head, fur, legs + tail, viscera) were not significantly different. The diet containing 87.5% IFS gave an increase of 1.1%, 6.4%, 8.8%, 17.9%, 7.4%, and 19.6% in digestibility coefficients of organic matter (OM), crude protein (CP), neutral detergent fibre (NFD), acid detergent fiber (ADF), hemi-cellulose (HC) and cellulose (C) compared to control diet, respectively.Feed intakes were moderate and ranged from 69 to 124 g for V-line, 77 to 128 g for Saudi-1, 79 to 130 g for Saudi-2, and 76 to 119 g for Saudi-3 along with moderate ratios of feed conversion ranging from 2.65 to 3.80, 2.45 to 3.90, 2.46 to 3.79 and 2.63 to 3.65, respectively. Pre-slaughter weight, hot carcass weight, and offal weight were in favour of Saudi-2 rabbits compared to the other groups. Both Saudi-1 and Saudi-2 rabbits were slightly higher than Saudi-3 in weights and percentages of head, fur, viscera and legs + tail. Lean and bone weights and percentages and meat to bone ratio in Saudi-2 carcasses were slightly higher than those recorded in the other groups, while moisture, DM, CP, EE and ash contents in the lean have shown little differences between groups. Rabbits of Saudi-1 were ranked the first in digestibility coefficients of OM, CP, NDF, ADF, HC, C and cell count compared to other groups.Rabbits of Saudi-2 fed diet containing 87.5% IFS recorded the heaviest body weights and gains since this class showed considerable deviations in body weights of 345, 341, 269, 307, 321, 345 and 347 g at 6, 7, 8, 9, 10, 11 and 12 weeks of age, respectively, in comparison with the lightest class. Both Saudi-2 and Saudi-3 rabbits fed the diet containing 87.5% IFS had favourable estimates of feed conversions ranging from 2.1 to 3.4, while rabbits of Saudi-1 fed the diet containing 87.5% IFS recorded the best digestibility coefficients.     

Effect of partial outlet obstruction on nitrotyrosine content and distribution within the rabbit bladder

Purpose: Evidence indicates that free radicals are etiological factors in obstructive bladder disease. However, it is not clear which species of reactive oxygen or nitrogen species mediate the damage. The current studies were designed to determine if partial outlet obstruction in rabbits results in the generation of nitrotyrosine (NT). Materials and methods: Sixteen rabbits were separated into four groups of four. The rabbits in groups 1 and 2 underwent sham operation while rabbits in groups 3 and 4 underwent partial outlet obstruction. The rabbits in groups 1 and 3 were evaluated after 1 week of obstruction and the rabbits in groups 2 and 4 were evaluated after 2 weeks of obstruction. A separate group of four controls were evaluated simultaneously with the sham and obstructed rabbits. Four rabbits from each group were evaluated after 1 and 2 weeks of obstruction. Four control rabbits were also evaluated. Isolated strips were evaluated for contractile responses and NT content of the mucosa and muscle were quantitated by Western blot analysis. Results: (1) The mucosa contains both 42 and 62 kD proteins exhibiting a strong nitrotyrosine signal; the muscle presents a signal only at 62 kD. (2) The sham operations had no effect on nitrotyrosine distribution or content. (3) The nitrotyrosine of both mucosal proteins and the muscle protein are increased in the 1 week obstructed bladder; whereas, only the 62 kD signal is increased in the two week obstructed bladder mucosa. (4) The contractile response to FS are reduced to a significantly greater degree than the responses to carbachol, KCl, or ATP. Conclusions: These studies clearly demonstrated that partial outlet obstruction in rabbits results in significant increases in nitrotyrosine within the bladder and may contribute to the contractile dysfunctions mediated by partial outlet obstruction. (Mol Cell Biochem 276: 143–148, 2005)     

Effect of partial ischemia on phospholipids and postischemic lipid peroxidation in rabbit spinal cord

Rabbit spinal cord, subjected to severe partial ischemia induced by abdominal aorta ligation tightly below the renal arteries, was analyzed for phospholipid composition and levels of lipid peroxidation products after 10, 20, and 40 min of the insult. Under conditions when spinal cord blood flow was decreased below 5% of control, concentrations of inositol and ethanolamine phospholipids were decreased by 30% and 10%, respectively. Phosphatidic acid concentration was also altered during ischemia. No accumulation of thiobarbituric acid reactive substances (TBA-RS), conjugated dienes and fluorescent lipid soluble material was found throughout the ischemic period. Pattern of TBA-RS, conjugated diene, and fluorophore formation during postischemic in vitro incubation without and with a peroxidation couple (Fe²⁺, ascorbic acid) showed increased susceptibility to postischemic lipid peroxidation in tissues after 20 and 40 min of ischemia.     

地膜覆盖栽培对土壤微生物种群和生物活性的影响

研究了覆膜栽培条件下土壤微生物种群和生物活性．棕壤长期覆膜种植玉米,土壤表层微生物数量增多,细菌、放线菌和真菌分别增加２２．６％、２９．３％和１９．７％．苗期细菌增加最多,达２１４％,拔节期和成熟期放线菌增加最多,为２２４％和２４４％,生育期真菌增加幅度１２２～１４６％．细菌中兼厌气性种群优势有所增强,真菌优势种群无变化．肥力水平不同地块覆膜均加强土壤呼吸作用,高肥地块土壤脲酶活性升高,低肥地块无变化．     

半干旱地区地膜覆盖对作物产量和氮效率的影响

在年降水量415mm的半干旱地区黄绵土上,以春小麦为供试作物进行大田试验,研究地膜覆盖进程(包括不覆膜、播种后覆膜30d、覆膜60d和全程覆膜)、底墒和施N对作物产量和N效率的影响．结果表明,增加底墒、地膜覆盖和施N均会显著增加作物产量和吸N量(α＜0.01),其影响顺序为N肥＞底墒＞覆膜．覆膜对产量的效应因底、施N和覆膜进程而异．从平均看,在低底墒时,各种覆膜处理产量虽有增加,但与不覆膜处理间的差异并不显著,而在高底墒时,以覆膜60d的产量最高,以不覆膜最低．由于覆膜和底墒影响作物产量和吸N量,因而也影响N效率．在低底墒时,以不覆膜和覆膜30d时N效率最高,而在高低墒时,30d、60d和全程覆膜处理间差异不显著．综合作物产量和N效率,全生育期覆膜并没有多少实际意义．     

Effect of surface roughness on squeeze film poroelastic bearings with special reference to synovial joints

A simplified mathematical model has been developed for understanding the combined effects of surface roughness and couple stresses on lubrication aspects of synovial joints. The modified Reynolds equation which incorporates the elastic as well as randomized surface roughness structure of cartilage with couple-stress fluid as lubricant is derived. The mean pressure, load carrying capacity and time of approach as functions of film thickness during normal articulation of joints are obtained by using Christensen stochastic theory with the assumption that the roughness asperity heights are to be small compared to the film thickness. The effects of surface roughness and elasticity are considerably pronounced for the poroelastic bearings with couple-stress fluid as lubricant compared with classical case.     

薄膜包装对于柿果冷藏生理及品质变化的影响

冷藏条件下采用有孔的聚乙烯薄膜为包装材料贮藏‘尖柿’,研究了聚乙烯薄膜的保湿作用对果实质地、生理生化,以及失重、失鲜等变化进程的影响。结果表明：薄膜包装能有效地防止蒸腾失水、显著抑制失重率增加,减缓硬度下降,推迟呼吸、乙烯峰到来的时间,并降低峰值,抑制细胞膜透性的增大,使果实保持光洁、饱满的外观形态,县有良好的商品性。     

Effect of repetitive ischemic preconditioning on spinal cord ischemia in a rabbit model

A completely randomized controlled study based on a rabbit model was designed to study the effect of repetitive ischemic preconditioning (IPC) on a spinal cord ischemic reperfusion injury. Twenty four white adult Japanese rabbits were randomly assigned to one of the 3 groups (n = 8 per group): Group I: sham-operation group, Group II: ischemic reperfusion group, and, Group III: IPC group. Spinal cord ischemia was induced by infra-renal aortic cross-clamp for 45 min in Group II. Before 45 min ischemia, the rabbits in Group III underwent four cycles of IPC (5 min of ischemia followed by 5 min of reperfusion). Post-operative neurological function, electromyography (EMG) of rear limbs, and spinal cord histopathological changes were measured. The concentrations of calcium, magnesium, copper, and zinc in spinal cord were measured in the 7th day. The neurological function and histopathological changes in Group II were significantly different from those in Group I or Group III (P < 0.05 or 0.01). There was a more significant change of EMG in Group II than that in Group III (P < 0.05). The concentrations of calcium and copper in Group II were significantly higher (P < 0.05 or 0.01), but magnesium and zinc were significantly lower (P < 0.05) than those in Group I. Calcium and copper in Group II were significantly higher (P < 0.05), but zinc was significantly lower (P < 0.01) than those in Group III. In conclusion, repetitive IPC can protect rabbit spinal cord from ischemic reperfusion injury in a timely manner, which is associated with corrections of imbalance of calcium, magnesium, copper, and zinc in the ischemic region.     

高岭土颗粒涂布对中国梨喀木虱寄主选择、产卵的影响及应用效果

为探索可替代化学药剂防治中国梨喀木虱的措施,开展了高岭土颗粒涂布对其寄主选择、产卵影响及应用效果的研究。分别采用3.5%高岭土水溶液、清水对梨休眠枝和当年生枝叶进行喷雾涂布处理,于24、48、72、96 h监测选择条件下成虫分布情况,于96 h记录选择和非选择条件下各枝条上的卵量。采用高岭土水溶液对梨苗均匀喷雾涂布,通过被害叶率、单叶若虫量、虫龄指数、为害指数对应用效果进行评价。研究结果显示,在选择条件下,经高岭土涂布的枝条上成虫数量明显少于对照,高岭土涂布的枝条上冬型成虫数量在96 h时最低(0.5头/枝),96 h时着卵量(1.83头/枝)显著低于对照(30.83头/枝);高岭土涂布的枝叶上夏型成虫在72 h时最低(1.17头/枝),96 h时着卵量(12.33头/枝)显著低于对照(242.5头/枝);在非选择条件下,冬型和夏型成虫在高岭土涂布的枝条上着卵量(2.83和15.17头/枝)分别显著低于对照(25.17和170.42头/枝);供试植株在接虫45 d后为害最严重,高岭土涂布的植株被害叶率(54.17%)、单叶若虫量(2.29头/叶)、虫龄指数(3.79)、为害指数(0.41)分别显著低于为对照植株(98.61%、11.72头/叶、4.13、0.95)。上述结果表明,高岭土涂布对中国梨喀木虱成虫的寄主选择具有驱避效果,对雌成虫的产卵具有抑制作用;高岭土涂布可限制中国梨喀木虱种群增长,降低危害水平。研究结果为中国梨喀木虱的综合治理提供了现实依据。     

Effect of aging on the response of biochemical markers in the rabbit subjected to short-term partial bladder obstruction

Purpose Partial bladder outlet obstruction (PBOO) results in marked biochemical alterations in the bladder. In this study, we focused on comparison of thapsigargin sensitive sarco/endoplasmic reticulum Ca²⁺ ATPase activity (SERCA) and Citrate Synthase after short term PBOO in young versus old rabbits. Materials and methods A total of 20 young and 20 mature male rabbits were divided into 4 sub-groups of 5 rabbits each (4 obstructed and 1 sham-control rabbit). The rabbits in the groups were evaluated after 1, 3, 7, and 14 days of obstruction, respectively. The activities of SERCA and citrate synthase were examined as markers for sarcoplasmic reticular calcium storage and release and mitochondrial function, respectively. Results The SERCA activity of bladder body smooth muscle in the young animals increased at 7 and 14 days. For the old rabbits, the SERCA activity decreased significantly by 1 day and remained this level throughout the course of obstruction, and was significantly lower than young at all time periods. The citrate synthase activity in the young animals decreased over the 1–7 days, and then returned toward control level by 14 days following obstruction. In the old animals, citrate synthase activity of bladder body smooth muscle progressively decreased over the course of the study, and was significantly lower in the old than the young animals after 14 days obstructed. Conclusion The urinary bladders of the young rabbits have a considerable greater ability to adapt to PBOO than do those of the old rabbits. The deterioration of mitochondrial and SR function may be important mechanisms underlying geriatric voiding dysfunction.     

黄土区地膜覆盖对麦田土壤微生物体碳的影响

研究了1999年(丰水年)和2000年(干旱年)旱地条件下不同时间覆膜(不覆膜、覆膜30d、覆膜60d和全程覆膜)对春小麦(Triticum aestivum)农田土壤微生物体碳的影响．结果表明,1999年土壤微生物体碳平均为335．3mg·kg^-1干土,2000年平均为259．3mg·kg^-1干土,前者高出后者29．37％．2年中最高微生物体碳均出现在全程覆膜处理．1999年。土壤微生物体碳在覆膜60d时即接近最高值。该处理籽粒产量也最高．2000年。由于春小麦生育后期降水丰富。在整个生育期中,微生物体碳增长表现为“增长-平稳甚至出现下降-再增长”的梯形方式,到生育后期,各处理之间才出现显著差异。全程覆膜处理的微生物体碳后期大幅度增加。与1999年接近．2年中各处理的C／N处于7．732～9．042之间。远低于11．3的临界值,C／P处于300．8～719．6之间,均高于300的临界值,不利于土壤微生物体碳的增加．微生物和作物对土壤有效态氮和磷的吸收处于竞争状态,表明该农田生态系统有机质严重不足。已经构成了限制作物生产力发挥的雷耍因素．长期地膜覆蔫和大量伸用化肥将加剧这一问题的严重性。     

控释肥料对覆膜栽培稻田N2O排放的影响

采用静态箱-气相色谱法,研究了控释肥料对四川丘陵地区覆膜节水高产栽培稻田N₂O排放的影响.结果表明: 稻田施用尿素及控释肥料后水稻生长期N₂O排放总量分别为(38.2±4.4)和(21.5±5.2) mg N·m^-2;施用尿素处理N₂O排放系数为0.25%,施用控释肥料处理N₂O排放系数为0.14%,减少了43.6%(P<0.05),其中烤田前减少了49.6%(P<0.05);控释肥料可抑制施肥引起的N₂O排放峰值,降幅达52.6%;控释肥料对水稻不同生长季节土壤微生物生物量氮、NH₄⁺-N含量和水稻产量均无显著影响;N₂O排放与5 cm土壤温度、土壤Eh值无显著相关性.