Electrochemical biofilm control: a review

One of the methods of controlling biofilms that has widely been discussed in the literature is to apply a potential or electrical current to a metal surface on which the biofilm is growing. Although electrochemical biofilm control has been studied for decades, the literature is often conflicting, as is detailed in this review. The goals of this review are: (1) to present the current status of knowledge regarding electrochemical biofilm control; (2) to establish a basis for a fundamental definition of electrochemical biofilm control and requirements for studying it; (3) to discuss current proposed mechanisms; and (4) to introduce future directions in the field. It is expected that the review will provide researchers with guidelines on comparing datasets across the literature and generating comparable datasets. The authors believe that, with the correct design, electrochemical biofilm control has great potential for industrial use.     

Robust pole placement control of a fermentor

This paper deals with robust pole placement control of a continuous flow alcoholic fermention process. The strain used for experiments is Saccharomyces cerevisae UG5. The fermentor is subject to changs in pH, temperature, mixing, etc. The regularized pole placement adaptive control algorithm is used for regulation and tracking purposes. The substrate concentration and the dilution rate have been respectively selected as controlled and control variables. The eliminant matrix associated to the pole placement problem is non-singular if the identified input-output model has common poles and zeros. Two solutions have been adopted to deal with this ill-conditioning problem. The first solution consists of monitoring the determinant of the eliminant matrix and the second consists of adding a correction term to the highest degree coefficient of either the numerator or denominator of the process transfer function. A robust recursive identification scheme is used for parameters estimation. The fermentor was interfaced with PC computer using a multitasking operating system. Experiments carried out with the fermentor, illustrate the use of the regularized pole placement adaptive control algorithm.     

蔬菜粉虱的系统调查与监测技术

由于烟粉虱Bemisia tabaci、温室白粉虱Trialeurodes vaporariorum等粉虱害虫在我国猖獗为害,我国已从种群动态监测到害虫综合治理开展了一系列研究。为了有一套统一、规范的标准,我们制定了保护地蔬菜与露地蔬菜生产上粉虱害虫的系统调查与监测技术规程,包括调查与监测的目的、样本大棚或田块的选择,粉虱各虫态发生数量的调查、监测与统计方法等,并根据保护地蔬菜与露地蔬菜的生长特点,提出了相应的粉虱害虫预测预报、防治阈值、防治对策及防控时间等技术措施。     

Managing mosquitoes and ticks in a rapidly changing world – Facts and trends

Vector-borne diseases transmitted by mosquitoes and ticks are on the rise. The effective and sustainable control of these arthropod vectors is a puzzling challenge for public health worldwide. In the present review, I attempted to provide a concise and updated overview of the current mosquito and tick research scenario. The wide array of control tools recently developed has been considered, with special reference to those approved by the World Health Organization Vector Control Advisory Group (WHO VCAG), as well as novel ones with an extremely promising potential to be exploited in vector control programs. Concerning mosquitoes, a major focus has been given on genetically modified vectors, eave tubes, attractive toxic sugar baits (ATSB) and biocontrol agents. Regarding ticks, the recent development of highly effective repellents and acaricides (including nanoformulated ones) as well as behavior-based control tools, has been highlighted. In the second part of the review, key research questions about biology and control of mosquitoes and ticks have been critically formulated. A timely research agenda outlining hot issues to be addressed in mosquito and tick research is provided. Overall, it is expected that the present review will contribute to boost research and applications on successful mosquito and tick control strategies, along with an improved knowledge of their biology and ecology.     

Computer control of pH and DO in a laboratory fermenter using a neural network technique

In this contribution, the advantages of the artificial neural network approach to the identification and control of a laboratory-scale biochemical reactor are demonstrated. It is very important to be able to maintain the levels of two process variables, pH and dissolved oxygen (DO) concentration, over the course of fermentation in biosystems control. A PC-supported, fully automated, multi-task control system has been designed and built by the authors. Forward and inverse neural process models are used to identify and control both the pH and the DO concentration in a fermenter containing a Saccharomyces cerevisiae based-culture. The models are trained off-line, using a modified back-propagation algorithm based on conjugate gradients. The inverse neural controller is augmented by a new adaptive term that results in a system with robust performance. Experimental results have confirmed that the regulatory and tracking performances of the control system proposed are good.     

Continuous three-dimensional control of a virtual helicopter using a motor imagery based brain-computer interface

Brain-computer interfaces (BCIs) allow a user to interact with a computer system using thought. However, only recently have devices capable of providing sophisticated multi-dimensional control been achieved non-invasively. A major goal for non-invasive BCI systems has been to provide continuous, intuitive, and accurate control, while retaining a high level of user autonomy. By employing electroencephalography (EEG) to record and decode sensorimotor rhythms (SMRs) induced from motor imaginations, a consistent, user-specific control signal may be characterized. Utilizing a novel method of interactive and continuous control, we trained three normal subjects to modulate their SMRs to achieve three-dimensional movement of a virtual helicopter that is fast, accurate, and continuous. In this system, the virtual helicopter's forward-backward translation and elevation controls were actuated through the modulation of sensorimotor rhythms that were converted to forces applied to the virtual helicopter at every simulation time step, and the helicopter's angle of left or right rotation was linearly mapped, with higher resolution, from sensorimotor rhythms associated with other motor imaginations. These different resolutions of control allow for interplay between general intent actuation and fine control as is seen in the gross and fine movements of the arm and hand. Subjects controlled the helicopter with the goal of flying through rings (targets) randomly positioned and oriented in a three-dimensional space. The subjects flew through rings continuously, acquiring as many as 11 consecutive rings within a five-minute period. In total, the study group successfully acquired over 85% of presented targets. These results affirm the effective, three-dimensional control of our motor imagery based BCI system, and suggest its potential applications in biological navigation, neuroprosthetics, and other applications.     

Remote consequences of a chronic radiation for the population of Hypochoeris maculata L growing on the territory of East-Ural radioactive trace

The caryological study has been carried out on Hypochoeris maculata L. plants growing on the East-Urals radioactive trace. Two Hypochoeris maculata L. populations have been observed. The experimental population grows in contaminated area. 90Sr contamination density is 55 MBq/m2, 137Cs contamination density is 2.5 M Bq/m2. The control population grows in radionuclide-free area. Both in the experimental and in the control populations the plants have been detected bearing extra B-chromosomes in their karyotype. But their frequency was higher in the experimental population than in the control one. In the experimental population the plants with main A-chromosome set karyotype changes have been met in 9 families out of 30 families observed. In the control population one such family has been detected out of 27 families observed. Two plants with karyotype changes in both chromosome sets have been detected in one family of the experimental population, which indicates a possibility of sibling species appearance in the experimental population.     

Bacillus thuringiensis: a biotechnology model

This paper is on the different biotechnological approaches that have been used to improve Bacillus thuringiensis (Bt) for the control of agricultural insect pests and have contributed to the successful use of this biological control agent; it describes how a better knowledge of the high diversity of Bt strains and toxins genes together with the development of efficient host-vector systems has made it possible to overcome a number of the problems associated with Bt based insect control measures. First we present an overview of the biology of Bt and of the mode of action of its insecticidal toxins. We then describe some of the progress that has been made in furthering our knowledge of the genetics of Bt and of its insecticidal toxin genes and in the understanding of their regulation. The paper then deals with the use of recombinant DNA technology to develop new Bt strains for more effective pest control or to introduce the genes encoding partial-endotoxins directly into plants to produce insect-resistant trangenic plants. Several examples describing how biotechnology has been used to increase the production of insecticidal proteins in Bt or their persistence in the field by protecting them against UV degradation are presented and discussed. Finally, based on our knowledge of the mechanism of transposition of the Bt transposon Tn4430, we describe the construction of a new generation of recombinant strains of Bt, from which antibiotic resistance genes and other non-Bt DNA sequences were selectively eliminated, using a new generation of site-specific recombination vectors. In the future, continuing improvement of first generation products and research into new sources of resistance is essential to ensure the long-term control of insect pests. Chimeric toxins could also be produced so as to increase toxin activity or direct resistance towards a particular type of insect. The search for new insecticidal toxins, in Bt or other microorganisms, may also provide new weapons for the fight against insect damage.     

Sliding controller design for a nonlinear fermentation system

The design of a sliding controller for a continuous fermentation process is presented. The results obtained by simulation have proved the control scheme to be very robust. Regulation of substrate concentration at its optimal value has been achieved even though process parameters change their nominal values. Chattering effects are decreased by introducing a minor modification of the control variable around the sliding surface.     

Closed-loop interactions between a shoal of zebrafish and a group of robotic fish in a circular corridor

Collective behavior based on self-organization has been observed in populations of animals from insects to vertebrates. These findings have motivated engineers to investigate approaches to control autonomous multi-robot systems able to reproduce collective animal behaviors, and even to collectively interact with groups of animals. In this article, we show collective decision making by a group of autonomous robots and a group of zebrafish, leading to a shared decision about swimming direction. The robots can also modulate the collective decision-making process in biased and non-biased experimental setups. These results demonstrate the possibility of creating mixed societies of vertebrates and robots in order to study or control animal behavior.     

FRETting for a more detailed interactome

Several methods have been described recently that permit researchers to exert post-translational control over gene products. An intein-based method shows it is a strong contender in the field by demonstrating control of protein activity in a whole animal.     

Disturbance-accommodating control approach applied for the control of a continuous stirred tank reactor

This paper describes an experimental study of linear adaptive control to achieve the monitoring of a continuous stirred tank reactor. The practical control objective was the regulation of the substrate concentration at a pre-specified value in the process effluent despite local changes and/or culture physiology variations. The substrate concentration and the dilution rate have been selected as the controlled and the control variable respectively. The results obtained confirm that this approach offers the possibility to combine simplicity and effectiveness in bioprocess control.     

Management of sugarcane borer populations in Louisiana,a decade of change

The sugarcane borerDiatrea saccharalis (F.) is the most serious and destructive insect attacking sugarcane in Louisiana. Losses in sugar yields ascribed to damage by this pest were estimated to have averaged 13% anally from 1937 to 1957. Biological and cultural control measures have been of little benefit against economically damaging infestations ofD. saccharalis and insecticides have historically assumed a major role in control programs. The maximum number of insecticide applications recommended to growers for full-season control ofD. saccharalis on sugarcane has been reduced from 12 to 3 within the past decade. Management practices most responsible for reductions in applications are: 1) discontinuance of insecticidal control of the first generation, 2) improvement of field survey methods for detecting potentially damaging infestations, 3) utilization of an economic injury threshold to ascertain need for insecticide treatment, 4) replacement of ryania and cryolite in control programs with synthetic organic insecticides that provide more effective and longer periods of control, and and 5) more emphasis on host plant resistance to reduce insecticide use.     

Speed adaptation in a powered transtibial prosthesis controlled with a neuromuscular model

Control schemes for powered ankle-foot prostheses would benefit greatly from a means to make them inherently adaptive to different walking speeds. Towards this goal, one may attempt to emulate the intact human ankle, as it is capable of seamless adaptation. Human locomotion is governed by the interplay among legged dynamics, morphology and neural control including spinal reflexes. It has been suggested that reflexes contribute to the changes in ankle joint dynamics that correspond to walking at different speeds. Here, we use a data-driven muscle-tendon model that produces estimates of the activation, force, length and velocity of the major muscles spanning the ankle to derive local feedback loops that may be critical in the control of those muscles during walking. This purely reflexive approach ignores sources of non-reflexive neural drive and does not necessarily reflect the biological control scheme, yet can still closely reproduce the muscle dynamics estimated from biological data. The resulting neuromuscular model was applied to control a powered ankle-foot prosthesis and tested by an amputee walking at three speeds. The controller produced speed-adaptive behaviour; net ankle work increased with walking speed, highlighting the benefits of applying neuromuscular principles in the control of adaptive prosthetic limbs.     

T-DNA as a gene tag

The characteristics of Agrobacterium-mediated plant transformation are such that the T-DNA can be used as an insertional mutagen and, by extension, a gene tag. An increasing number of mutants have been obtained as a result of T-DNA insertion and the versatility of this experimental system can be exploited further to tag sequences of DNA which control gene expression. While the isolation of specific mutations by T-DNA tagging in the past has been fortuitous, T-DNA-based vectors have the potential to generate transgenic plants with specific, selectable mutations.     

Data acquisition and control of a continuous fermentation unit

Summary Data acquisition and computer control ofZymomonas mobilis fermentation for ethanol production has been studied. An HP 200 series microcomputer system was used in conjunction with an HP 3497A data acquisition unit. On-line ethanol, glucose and cell mass were measured for use as possible control variables. Dilution rate was used as the manipulative variable. A versatile, user-friendly data acquisition program was written to gather, control and analyze data from the continuous fermentation. The program allows user-given control and calibration algorithms so that sophisticated control policies, e.g., self-tuning regulator (STR) and instrumentation, can be implemented with relative ease.     

Process analytical technology implementation for protein refolding: GCSF as a case study

Process analytical technology is gaining interest in the biopharmaceutical industry as a means to enable consistency in processing and thereby in product quality via process control. Protein refolding is known to be significantly impacted by critical process parameters and feed material attributes including composition and pH of the solubilisation and refolding buffers. Hence, to achieve robust process control and product quality, these attributes and parameters need to be monitored. This paper presents an approach towards statistical process control and monitoring of protein refolding, from buffer preparation to refold quenching, during manufacturing of therapeutic proteins from Escherichia coli based systems. The proposed approach utilises measurements of online redox potential, temperature, and pH for development of a statistical model. The model has then been integrated with LabView to permit real-time monitoring of the refolding process. The proposed system has been demonstrated to successfully identify process deviations and thereby enable process control for manufacturing product of consistent quality.     

Eradication of Taenia solium cysticercosis: a role for vaccination of pigs.

Neurocysticercosis due to Taenia solium is an important cause of human morbidity and mortality, particularly in Latin America and parts of Africa and Asia. The disease has been recognised as potentially eradicable. Emphasis has been placed on control of the parasite through mass chemotherapy of human populations to remove tapeworm carriers. This strategy does not control the source of tapeworm infections, cysticercosis in pigs, and parasite transmission may continue due to incomplete chemotherapy coverage of human tapeworm carriers or because of immigration of tapeworm carriers into control areas. Exceptionally effective, practical vaccines have been developed against cysticercosis in sheep and cattle and a recent trial has proved recombinant antigens to be effective against Taenia solium cysticercosis in pigs. A new strategy for eradication of Taenia solium is proposed, based principally on a combined approach of chemotherapy of human tapeworm carriers and vaccination of all pigs at risk of infection.     

重大外来入侵害虫——美国白蛾生物防治技术研究

美国白蛾Hyphantria cunea(Drury)是重大外来入侵害虫,对我国林业和园林绿化造成重大危害,尤其是近年来美国白蛾传入北京,严重威胁着我国“绿色奥运”的顺利举办和首都园林绿化及生态环境安全。根据美国白蛾多发生在居民区、乡镇和城市的特点,作者开展对环境安全的生物防治技术研究。汲取前苏联等国家从美国白蛾的原产地引进天敌进行生物防治没有成功的经验和教训,立足调查和寻找我国本土天敌。经过21年的努力,发现和筛选出白蛾周氏啮小蜂Chouioia cunea Yang(新属新种)这种寄生美国白蛾的特优天敌;研究这种小蜂的行为学、生态学、生物学、解剖学及人工大量繁殖、放蜂防治技术;筛选出人工大量繁殖小蜂的替代寄主,解决小蜂的大量繁殖的瓶颈问题;通过放蜂防治试验,取得良好的防治效果。同时,筛选出防治美国白蛾的高毒力HcNPV病毒毒株,研制出美国白蛾人工饲料,利用人工饲料大量饲养美国白蛾幼虫,然后接种扩增病毒,成功解决HcNPV病毒大量扩增生产和常年生产的技术难题,做到病毒的规模化生产和常年生产,保证大面积生产防治的需要和病毒质量。研究出利用天敌昆虫和病原微生物综合应用的防治模式:在美国白蛾幼虫期喷洒HcNPV病毒,蛹期释放白蛾周氏啮小蜂,达到既控制当代美国白蛾的危害,又有效抑制其下代的种群数量,取得长期的持续控制美国白蛾的防治效果。上海市、大连市、烟台市和青岛市利用该项技术已经完全控制美国白蛾,特别是上海市利用本项生物防治技术防治后,已经连续6年没有再发现美国白蛾。由于该项生物防治技术利用的是自然界原有的控制害虫的生态因子,因而对环境安全,做到既消灭害虫,又保证生态环境和人畜的安全,也保护生物多样性。该项研究成果也为北京采用“绿色”防治技术有效控制美国白蛾提供重要的科技支撑和技术保障。