Biofilm formation by Pseudomonas fluorescens

The formation of biofilms on heat exchange surfaces was studied using water contaminated with Pseudomonas fluorescens. The rate of deposition and the maximum amount of deposit decrease as the fluid velocity increases. The processes occurring at the interface and in the biofilm appear to govern the build-up of the deposit. together with the removal (shear stress) mechanism. Values of the attachment and biological growth rates were calculated from the changes observed in the biofilm thermal resistances after suppressing the addition of nutrients to the flowing water. In both cases there is a decrease for higher velocities.JNICT. Portugal. through Project no. 8750

Avaliação da condição física

A avaliação da condição física (CF) possui caráter complexo e subjetivo, não obstante os propósitos de motivação dos jovens para a atividade física e aptidão física. A CF no PNEF possui um programa comum para cada ciclo de escolaridade, tendo como finalidade a elevação das capacidades condicionais e coordenativas, privilegiando a zona de aptidão “saudável” para os jovens. Embora a avaliação da CF seja associada à promoção da saúde e atividade física, os autores alertam para a fraca fiabilidade dos resultados e os constrangimentos nos alunos. Dados recolhidos de docentes de 6 escolas, de 2º e 3º ciclos e Ensino Secundário do Funchal, permitiram aferir que, para a maioria, a carga letiva de Educação Física não é suficiente para um trabalho harmonioso da CF, devendo esta ser avaliada como matéria de ensino. A avaliação da aptidão física continuará a constituir um veículo promotor da atividade física, saúde e bem-estar. Urge questionar o modelo de avaliação isolado da CF, porém é necessário encontrar modelos operacionalizáveis, no sentido de atuar de forma mais eficaz na promoção da aptidão e atividade física dos jovens, sendo a Educação Física um meio privilegiado para o efeito.info:eu-repo/semantics/publishedVersio

The effect of clay particles on the efficacy of a biocide

The effect of kaolin particles on the bacterial activity as well as on the efficacy of a biocide was investigated. The results show that the presence of the clay particles enhance the Pseudomonas fluorescens activity for all buffered pH values tested, this increase being more relevant for the more adverse pH for this bacteria growth. The results also demonstrated that kaolin reduces the ability of desinfection of a carbamatebased biocide against P. fluorescens suspensions.União Europeia - Training and Mobility of Researchers, project BIOTOBIO. PRAXIS XXI BD/3242/94. Instituto de Biotecnologia e Química Fina (IBQF). Fundação Luso-Americana para o Desenvolvimento (FLAD)

A simple flow cell for monitoring biofilm formation in laboratory and industrial conditions

This work proposes and discusses a simple flow cell reactor that provides a means to monitoring biofilm growth by periodical removing biofilm-attached slides for off-line, nondestructive and destructive biofilm analysis without the stoppage of the flow. With this flow cell, biofilm growth and respiratory activity can be easily followed, either in well defined laboratory conditions or in an industrial environment. The reproducible and typical biofilm development curves obtained validated this flow cell and confirmed its potential for different biofilm-related studies, which can include biocidal treatment

Diagnosis of Human Leptospirosis in a Clinical Setting: Real-Time PCR High Resolution Melting Analysis for Detection of Leptospira at the Onset of Disease:

Currently, direct detection of Leptospira can be done in clinical laboratories by conventional and by real-time PCR (qRT-PCR). We tested a biobank of paired samples of serum and urine from the same patient (202 patients) presenting at the hospital in an area endemic for leptospirosis using qRT-PCR followed by high resolution melting (HRM) analysis. The results were compared with those obtained by conventional nested PCR and with the serologic gold standard microscopic agglutination test (MAT). Differences were resolved by sequencing. qRT-PCR-HRM was positive for 46 of the 202 patients (22.7%, accuracy 100%) which is consistent with known prevalence of leptospirosis in the Azores. MAT results were positive for 3 of the 46 patients (6.5%). Analysis of paired samples allowed us to identify the illness point at which patients presented at the hospital: onset, dissemination or excretion. The melting curve analysis of Leptospira species revealed that 60.9% (28/46) of patients were infected with L. interrogans and 39.1% (18/46) were infected with L. borgpetersenii, both endemic to the Azores. We validated the use of qRT-PCR-HRM for diagnosis of leptospirosis and for identification of the Leptospira species at the earliest onset of infection in a clinical setting, in less than 2 hours.publishersversionpublishe

Surface interactions and deposit growth in fouling of heat exchangers

Fouling of heat exchangers is a costly problem in industJ)'. There is a need for a better understanding of the phenomena involved in the build up of deposits on surfaces. The paper reviews the basic mechanisms of fouling, emphasizing their rdle in determining the overall fouling rate. Mass transfer, adhesion, chemical or biological reactions can be the rate limiting processes depending on the design and operating conditions of the heat exchanger. Reference is made to the most common types of fouling, particularly in water systems, and to their interaction with corrosion of metallic surfaces. Special attention is devoted to adhesion, since the formation of fouling layers is primarily a surface process. The main forces of adhesion and the methods fa predicting adhesion tendencies are reviewed. The paper presents and discusses data obtained in laboratory studies on fouling caused by inorganic particles, by microorganisms, and also by both of these types of foulants acting simultaneously. Synergistic phenomena (positive and negative) seem to occur when two oc more types of foulants are present in the fluid, but the final result is still unpredictable. Data on the effects of fluid velocity, temperature and surface material are also presented and discussed.(undefined

Interaction between different fouling agents in water systems

Publicado em "Heat transfer 1990 : proceedings of the Ninth International Heat Transfer Conference", Jerusalem, Israel, Vol. 5 (1990)Most of the fouling studies have been up to now focused on the build up of deposits caused by only one foulant. Although this type of research allows a more clear identification of the mechanisms involved in the formation of deposits, the study of more realistic situations is now needed. The paper reports the results of fouling tests where different fouling agents were present in water: kaolin plus magnetite particles, and bacteria (Pseudomonas jl.uorescens) plus kaolin particles. Deposit formation was monitored through heat transfer measurements. The tests were performed with water flowing at several velocities and the data were compared with previous results obtained using a single foulant. in an attempt to determine possible changes in the processes controlling the fouling rate. Increased fouling resistances and rates were observed when kaolin particles were suspended in the bacteria - - water system. The kaolin - magnetite interaction seems to decrease the final amount of deposit and, at the same time, to increase its mechanical strength. Modifications in the metabolic processes or in the adhesion forces may account for the observed changes