Pawpaw seed as fertility control agent on male Nile tilapia

To find out if pawpaw (Carica papaya) seeds can induce sterility in male Nile tilapia (Oreochromis niloticus) and to determine if sterility so induced is reversible or otherwise, mature male tilapia of mean weight 40 g were treated for 30 days with a low dose (4.9 g/kg/day) and a high dose (9.8 g/kg/day) of ground pawpaw seeds incorporated into their feed. Fish of similar sizes in the control experiment were fed with feed that did not contain pawpaw seed. The pawpaw seeds induced permanent sterility in the fish that received the high dose, while sterility in the low dose treatment was reversible. Fish in the control experiment spawned two weeks into the experiment and again in the fifth week. Fish in the low dose treatment spawned three weeks after the treatment had been discontinued. Histological sections of the testes showed that pawpaw seeds produced swollen nuclei in the low dose treatment and disintegrated cells in the high dose treatment. The study showed that pawpaw seeds, which are easy to obtain, can be incorporated into fish feeds and used by farmers to control prolific breeding of Nile tilapia.

Feedforward Control of Shape Memory Alloy Actuators Using Fuzzy-Based Inverse Preisach Model

This brief investigates a possible application of the inverse Preisach model in combination with the feedforward and feedback control strategies to control shape memory alloy actuators. In the feedforward control design, a fuzzy-based inverse Preisach model is used to compensate for the hysteresis nonlinearity effect. An extrema input history and a fuzzy inference is utilized to replace the inverse classical Preisach model. This work allows for a reduction in the number of experimental parameters and computation time for the inversion of the classical Preisach model. A proportional-integral-derivative (PID) controller is used as a feedback controller to regulate the error between the desired output and the system output. To demonstrate the effectiveness of the proposed controller, real-time control experiment results are presented.

Modelling and Control of Shape Memory Alloy Actuators by using Preisach Model, Genetic Algorithm and Fuzzy Logic

Shapememoryalloy (SMA) actuators, which have the ability to return to a predetermined shape when heated, have many potential applications in aeronautics, surgical tools, robotics and so on. Nonlinearity hysteresis effects existing in SMA actuators present a problem in the motion control of these smart actuators. This paper investigates the control problem of SMA actuators in both simulation and experiment. In the simulation, the numerical Preisachmodel with geometrical interpretation is used for hysteresis modeling of SMA actuators. This model is then incorporated in a closed loop PID control strategy. The optimal values of PID parameters are determined by using geneticalgorithm to minimize the mean squared error between desired output displacement and simulated output. However, the control performance is not good compared with the simulation results when these parameters are applied to the real SMA control since the system is disturbed by unknown factors and changes in the surrounding environment of the system. A further automated readjustment of the PID parameters using fuzzylogic is proposed for compensating the limitation. To demonstrate the effectiveness of the proposed controller, real time control experiment results are presented.

Variations of the Atlantic meridional overturning circulation in control and transient simulations of the last millennium

The variability of the Atlantic meridional overturing circulation (AMOC) strength is investigated in control experiments and in transient simulations of up to the last millennium using the low-resolution Community Climate System Model version 3. In the transient simulations the AMOC exhibits enhanced low-frequency variability that is mainly caused by infrequent transitions between two semi-stable circulation states which amount to a 10 percent change of the maximum overturning. One transition is also found in a control experiment, but the time-varying external forcing significantly increases the probability of the occurrence of such events though not having a direct, linear impact on the AMOC. The transition from a high to a low AMOC state starts with a reduction of the convection in the Labrador and Irminger Seas and goes along with a changed barotropic circulation of both gyres in the North Atlantic and a gradual strengthening of the convection in the Greenland-Iceland-Norwegian (GIN) Seas. In contrast, the transition from a weak to a strong overturning is induced by decreased mixing in the GIN Seas. As a consequence of the transition, regional sea surface temperature (SST) anomalies are found in the midlatitude North Atlantic and in the convection regions with an amplitude of up to 3 K. The atmospheric response to the SST forcing associated with the transition indicates a significant impact on the Scandinavian surface air temperature (SAT) in the order of 1 K. Thus, the changes of the ocean circulation make a major contribution to the Scandinavian SAT variability in the last millennium.

Seawater carbonate chemistry and net dissolution rate for experiment of Shiraho reef

Acidification of the oceans by increasing anthropogenic CO2 emissions will cause a decrease in biogenic calcification and an increase in carbonate dissolution. Previous studies have suggested that carbonate dissolution will occur in polar regions and in the deep sea where saturation state with respect to carbonate minerals (Omega) will be <1 by 2100. Recent reports demonstrate nocturnal carbonate dissolution of reefs, despite a Omega a (aragonite saturation state) value of >1. This is probably related to the dissolution of reef carbonate (Mg-calcite), which is more soluble than aragonite. However, the threshold of Omega for the dissolution of natural sediments has not been clearly determined. We designed an experimental dissolution system with conditions mimicking those of a natural coral reef, and measured the dissolution rates of aragonite in corals, and of Mg-calcite excreted by other marine organisms, under conditions of Omega a > 1, with controlled seawater pCO2. The experimental data show that dissolution of bulk carbonate sediments sampled from a coral reef occurs at Omega a values of 3.7 to 3.8. Mg-calcite derived from foraminifera and coralline algae dissolves at Omega a values between 3.0 and 3.2, and coralline aragonite starts to dissolve when Omega a = 1.0. We show that nocturnal carbonate dissolution of coral reefs occurs mainly by the dissolution of foraminiferans and coralline algae in reef sediments.

In-vehicle avatars to elicit social response and change driving behaviour

Social and psychological theories have provided a plethora of evidence showing that the physical difficulty to express appropriate social interactions between drivers expresses itself in aggression, selfish driving and anti-social behaviour. Therefore there is a need to improve interactions between drivers and allow clearer collective decision making between them. Personal characteristics and the driving situations play strong roles in driver’s aggression. Our approach is centered around the driving situation as opposed to focusing on personality characteristics. It examines aggression and manipulates contextual variables such as driver’s eye contact exchanges. This paper presents a new unobtrusive in-vehicle system that aims at communicating drivers’ intentions, elicit social responses and increasing mutual awareness. It uses eye gaze as a social cue to affect collective decision making with the view to contribute to safe driving. The authors used a driving simulator to design a case control experiment in which eye gaze movements are conveyed with an avatar. Participants were asked to drive through different types of intersections. An avatar representing the head of the other driver was displayed and driver behaviour was analysed. Significant eye gaze pattern difference where observed when an avatar was displayed. Drivers cautiously refer to the avatar when information is required on the intention of others (e.g. when they do not have the right of way). The majority of participants reported the perception of “being looked at”. The number of glances and time spent gazing at the avatar did not indicate an unsafe distraction by standards of in-vehicle device ergonomic design. Avatars were visually consulted primarily in less demanding driving situations, which underlines their non-distractive nature.

Electrophile-Induced C-C Bond Activation of Vinylcyclopropanes for the Synthesis of Z-Alkylidenetetrahydrofurans

We present a detailed study on the behavior of vinylcyclopropanes as masked donor acceptor system toward the stereoselective synthesis of Z-alkylidenetetrahydrofurans. Results of bromenium catalyzed indirect activation of C-C bond of vinylcyclopropanes and concomitant cyclization to alkylidenetetrahydrofuran and other heterocycles have been discussed. The stereoselective formation of the Z-isomer is strongly controlled by the extent of destabilization of one of the gauche conformers of the vinylcyclopropane. The ring-opening/cyclization step was found to be stereospecific as in the case of DA cyclopropanes. The activation of the C-C bond leads to a tight-carbocation intermediate, which is evident from the complete retention of the stereochemistry. The retention of configuration has been established by a necessary control experiment that rules out the possibility of a double inversion pathway. The present results serve as direct stereochemical evidence in support of a tight ion-pair intermediate versus the controversial S(N)2 pathway. A 2D potential energy scan has been carried out at B3LYP/6-31G(d) level theory to obtain the relative energies of the conformers. The Z-selectivity observed has been explained on the basis of the relative population of the conformers and modeling the intermediate and transition state involved in the reaction at M06-2x/6-31+G(d) level. Energy profile for the cyclization step was modeled considering various possible pathways through which cyclization can happen. The methodology has been successfully demonstrated on vinylcyclobutanes as well.

High Loading of Pd Nanoparticles by Interior Functionalization of MOFs for Heterogeneous Catalysis

In this report, the issue related to nanoparticle (NP) agglomeration upon increasing their loading amount into metal-organic frameworks (MOFs) has been addressed by functionalization of MOFs with alkyne groups. The alkynophilicity of the Pd2+ (or other noble metals) ions has been utilized successfully for significant loading of Pd NPs into alkyne functionalized MOFs. It has been shown here that the size and loading amount of Pd NPs are highly dependent on the surface area and pore width of the MOFs. The loading amount of Pd NPs was increased monotonically without altering their size distribution on a particular MOF. Importantly, the distinct role of alkyne groups for Pe(2+) stabilization has also been demonstrated by performing a control experiment considering a MOF without an alkyne moiety. The preparation of NPs involved two distinct steps viz. adsorption of metal ions inside MOFs and reduction of metal ions. Both of these steps were monitored by microscopic techniques. This report also demonstrates the applicability of Pd@MOF NPs as extremely efficient heterogeneous catalysts for Heck-coupling and hydrogenation reactions of aryl bromides or iodides and alkenes, respectively.

Induced diploid meiogynogenesis in the African clariid catfish Heterobranchus longifilis (Valenciennes, 1840) (Pisces: Clariidae)

Diploid meiotic gynogenesis was induced in African catfish, Heterobranchus longifilis by injection of 0.5ml/kg ovaprim on the breeders, followed by application of UV light irradiation on the spermatozoa and temperature shocking of activated eggs. Diploidy was restored by shocking haploid activated eggs at 5 degree C for 40 minutes. The normal control spermatozoa did not receive any UV irradiation nor temperature shock, while the haploid control spermatozoa were irradiated, but did not receive cold shock. The percentage hatchability in the treated group was 25%, while in the control it was 53%. Less than 15 fingerlings had morphological aberrations. After two weeks of indoor rearing, the survival percentage of the treated group was 45% in the control experiment. Cytogenetic analysis of chromosomes revealed 25 chromosomes in the haploid embryo and 50 chromosomes each in diploid gynogenesis and normal diploid control

Studies of the effects from extracts from two local plants (Tephrosia vogelii and Parkia clappertoniana) on Clarias gariepinus (Tengels)

Studies were carried out using 96hr static toxicity bioassay to determine the effect of lethal concentrations of extracts from two local plants Tephrosia vogelii and Parkia clappertoniana which are known fish poison, on a species of mud fish. Clarias gariepinus Phytochemical analysis of the plant extracts was done and the extract from T. vogelii was found to contain alkaloids, tannins and flavonoids, while the extract from P. clappertoniana was formed to contain alkaloids tannins and saponins. Experimental fish were exposed to test water separately polluted by varying concentrations of extraction of both plant species ranging from 0.50mgl super(-1), 1.50mgl super(-1), 2.50mgl super(-1), 3.0mgl super(-1), 5.00mgl super(-1), 10.00mgl super(-1) in the case of T. vogelii and 5.00mgl super(-1), 7.50mgl super(-1), 10.00mgl super(-1), 15.00mgl super(-1), 20.00mgl super(-1) and 30.00mgl super(-1) in the case of P. clappertaniana. Behavioural hispathological and heamatological examinations were made. Both plant extracts were found to have lethal effects at the higher concentrations, affecting the gills and the central nervous system as well as having a depressive effect on the total count and increasing platelet and white blood cell count. Symptoms of toxicosis observed include, initial inactivation agitated swimming, tumbling movement air gulping, increased opercular beat and period of quiescence/knockdown before death. Marked differences were also observed in the hematological and histopathological analysis of poisoned fish. Lower concentrations of the extracts had sub lethal effects on the fish, which manifested as zigzag movement air gulping increased opercular movement etc. None of these effects were observed in the control experiment

Effect of crude oil and some petroleum products on Clarias Gariepinus fingerlings (Catfish: Claridae)

Ninety (90) hatchery bred fingerlings of Clarias gariepinus (mean weight: 0.96 ± 0.1g) were randomly placed in 15 plastic baths (25 litres each) at the Research laboratory and were exposed to different concentrations of oil products to determine their effects on the fish, to facilitate inferential deductions that will enhance effective aquatic environmental management. Three (3) replicate basins of 5 experimental treatments (crude oil, petrol oil, kerosene oil, engine oil and control) were used at a concentration of 1.25ml. L-1. The control experiment was devoid of oil treatment. Six (6) fingerlings were placed in each replicate basin, flooded with 20 litres of clean tap water and fed with nutrafin cichilid food, 2 times daily at 3% body weight. The results showed that the feeding behaviour and swimming performances of fish were reduced after 24 hours of the addition of the various oil pollutants. Mortality of fingerlings in the oiled basins increased as the hours of exposure increased (i.e. 24, 48, 72 and 96 hours). Recovery was not immediate in the treated basin while surviving fingerlings in the control basins grew up to post-fingerlings after 90 days (3 months). There were significant differences (P<0.01 and P<0.05) in the effect of crude oil and the petroleum products on the mortality rate of C. gariepinus when exposed to oil pollutants at 1.25ml. L-1 concentration

电子束蒸发镀膜速率控制

介绍了电子束蒸发镀膜速率控制的基本原理和方法,选取实际生产中大量使用且蒸发特性较难控制的SiO_2和HfO_2,对两者的电子束蒸发速率控制分别进行了实验研究。采用比例积分微分(PID)闭环反馈控制,通过Ziegler-Nichols工程经验公式进行原始参量整定,并在实验的基础上对控制器的原始参量进行调整以及对积分作用和微分作用进行分区处理,速率控制的实验结果表明,采用该参量整定方法并结合工艺流程的改进,能获得良好的速率控制。针对速率控制中存在的难点问题进行了分析,并提出改进措施:将速率控制和电子枪扫描控制相结合能进一步改善速率控制。

Interações do cobre iônico com microalgas verdes

No presente trabalho foram utilizados micro-organismos fotoautotróficos para a bioacumulação de cobre em regime de batelada. Para tal, utilizou-se micro-organismos dos gêneros Ankistrodesmus, Golenkinia, Monoraphidium e Scenedesmus, em função da sua disponibilidade, facilidade de cultivo e diferenças morfológicas. Ensaios preliminares foram realizados utilizando diferentes concentrações de biossorvente, com o intuito de verificar a influência deste fator na eficiência do processo de captação. Os testes realizados em batelada incluíram também o estudo cinético e do equilíbrio, nos quais foi possível verificar que para todos os gêneros testados, o processo de captação do metal em soluções diluídas atingiu o equilíbrio quase instantaneamente. Em soluções de Cu2+ mais concentradas, observou-se diferenças entre os gêneros estudados, no tempo necessário para estabelecimento do equilíbrio. Além disso, observou-se uma alta eficiência no processo de captação de íons Cu2+ em solução por parte dos micro-organismos, com elevada captação de metal por grama de biomassa. As diferenças morfológicas entre os gêneros pareceram não influenciar significativamente a cinética e o equilíbrio do processo. Os ensaios em batelada foram realizados também empregando-se células de Golenkinia imobilizadas em alginato de cálcio, além de testes com o próprio alginato isento de micro-organismos como experimento-controle afim de verificar a influencia da imobilização nos parâmetros cinéticos e na capacidade de captação. A partir dos resultados obtidos nos ensaios em batelada com todos os biossorventes, testou-se em cada caso a aplicação de modelos cinéticos (pseudo 1 e 2 ordem) e modelos de equilíbrio (isoterma de Langmuir e Freundlich). Verificou-se que para o 4 gêneros que empregando-se células livres o modelo cujo os resultados se adequaram melhor foi o de Langmuir, enquanto que para células imobilizadas ambos modelos se mostraram adequados

资源异质性环境中植物克隆生长的描述与模拟

植物克隆生长型主要由遗传结构决定，不同的克隆植物具有不同的克隆生长型，同时植物的克隆生长型又依具体生境和个体发育阶段不同而变化。Harper认为植物构件的结构由分枝角度、节间长度和芽的成活率决定。大量的研究表明克隆植物生长型主要由3个形态参数决定：节间长度、分枝角度和分枝强度。 植物的生境条件无论在时间还是空间上都是异质性的，即使在很小的尺度上这种异质性也是存在的。在这种具有异质性的生境条件下几乎所有植物都有表型可塑性。植物的表型可塑性是指植物在不同的环境因子条件下，在形态、生物量、生理等方面产生的一系列不同。表现型可塑性是植物种群克服环境异质性的重要途径，也是克隆植物实现觅养行为的途径。克隆植物的觅养行为是通过根茎或匍匐茎的长度和分枝强度的变化以及生物量的分配来实现其迁移和对生境的选择，从而将分株安置在各种微环境中。 克隆植物构型的可塑性可使它在土壤水分斑块性分布的环境中通过克隆生长，调整对不同斑块的土壤水分获取对策。在一田间实验中，匍匐茎草本蛇莓（Duchesnea indica Focke）经历了不同土壤水分水平（土壤最大含水量的40%、60%、80%、100%等）处理，以研究土壤水分对蛇莓克隆构型的影响。结果表明：间隔子长度、分株密度、分枝角度和分枝强度呈二次曲线变化，土壤含水为最大含水量的80%为最适生境。 克隆植物构型的可塑性可使它在养分斑块性分布的环境中通过克隆生长调整相应于对不同斑块的养分获取对策。在一田间实验中，蛇莓经历了不同土壤养分水平（高、中、低和对照）处理，以研究土壤养分对蛇莓克隆构型的影响。结果表明：随着土壤养分水平的增加，间隔子的长度、分枝角度均逐渐降低，分枝强度和分株密度增加。 克隆植物构型的可塑性可使它在不同光强的环境中通过克隆生长，调整其对不同光强的资源获取对策。在控制性光资源异质性生境（模拟浓密林荫、稀疏林荫、农田间套作、裸地等）下，研究和模拟了光资源的时空异质性和蛇莓的克隆可塑性变化。结果表明：随着光照强度的增加，间隔子长度的长度逐渐降低，分枝角度、分株强度呈二次曲线变化。 克隆植物构型的可塑性可使它在不同海拔的环境中通过克隆生长，调整其对不同海拔的资源获取对策。在一海拔高度实验中，匍匐茎草本蛇莓经历了不同海拔(400 m、800 m、1200 m和1600 m)处理，以研究不同海拔对蛇莓克隆构型的影响。结果表明：随着海拔的增加，间隔子长度、分株密度、分枝角度和分枝强度呈二次曲线变化。 从克隆植物生长环境（小气候）定量分析了克隆植物生长必需资源如水分、养分、光强、海拔等的变化特性。具体描述和分析了异质环境尺度的大小和等级数。在前人研究成果的基础上，验证了克隆植物生长必需资源分布异质性的数学模型并建立相应的运算模块。在不同水分、养分、光强和海拔等异质性生境中，蛇莓克隆构型相关特征的可塑性变化可用动态Logistic模型进行模拟和预测，拟合效果较好。结合植物对环境异质性的利用对策，对所揭示的蛇莓克隆构型可塑性进行了讨论。 用分形技术描述了蛇莓在资源斑块性分布的生境中，通过克隆生长调整相应于对不同斑块的资源获取对策。植物克隆构型的形态特征在一定尺度范围内具有自相似特征。蛇莓克隆构型的分形维数直接反映了在异质性生境中蛇莓克隆生长的差异。蛇莓克隆生长越发达分形维数越高。相对小的分形维数，反映出蛇莓克隆生长相对较弱。基于计算机图像技术和分形理论，建立了植物克隆生长分形度量的计算机模型，实现了对植物克隆生长过程的计算机模拟。模拟的蛇莓克隆生长形态与实际生长不仅具有相近的分形维数，而且形态也非常相似。利用克隆生长模型的预测能力克服实验生态学难以逾越的某些研究盲点，其研究成果将对克隆植物利用资源异质性的生态对策研究具有重要的指导意义。

大蹼铃蟾抗菌肽- 2 与IFN2α22b 和TNF2α对膀胱癌细胞株抑制活性的实验研究

目的:比较大蹼铃蟾抗菌肽- 2 (Maximin 2) 与肿瘤坏死因子2α(TNF2α) 、干扰素2α22b ( IFN2α22b) 对不同膀胱癌细胞株的抑制杀伤作用。方法:采用细胞培养及MTT 比色法,检测Maximin 2 、TNF2α及 IFN2α22b 对3 个不同膀胱癌细胞株的抑制作用及作用特点,计算量效回归曲线及50 %抑制率。结果: Maximin 2 对不同的膀胱癌细胞株在100μgPmL 左右(48 h) 即达到50 %抑制率浓度( IC50) ,并呈剂量相 关性,与TNF2α、IFN2α22b 抑制作用的表现形式不同。Maximin 2 抑制率最高表现在第48 h ,以后逐渐减 弱, TNF2α、IFN2α22b 则在前24 h 作用较弱,以后逐渐增强。结论:Maximin 2 对不同的膀胱癌细胞株均 有较强的抑制作用,同TNF2α、IFN2α22b 比较其作用机制有所不同,Maximin 2 对膀胱癌细胞株的杀伤作 用可能主要是通过对肿瘤细胞的直接抑制,并且相对容易失活。