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

The knowledge of master dyers revealed by HPLC-DAD and UHPLC-HRMS/MS

UIDB/00749/2020 UIDP/00749/2020This work provides new knowledge on natural yellows used in Iran. Seven biological sources were selected based on interviews with dye masters in Isfahan workshops (Iran). Delphinium semibarbatum, Eremostachys laevigata, Prangos ferulacea, Morus alba, Pistacia vera, Punica granatum, and Vitis vinifera are currently used in these workshops. Aiming to study the dye composition of wool samples dyed with the extracts of the selected biological sources and the changes induced by the dyeing procedures in the original chemical composition of the plant extract, raw materials and dyed wool (by us and in the workshops) were analyzed by HPLC–DAD and UHPLC–HRMS/MS. The main yellows for E. laevigata are luteolin-O-glycosides. In the other plant sources, the main chromophores are based on 3-O-glycosides of kaempferol, quercetin, and isorhamnetin. In pistachio hulls, myricitin derivatives were detected and we propose their use as markers. Generally, the solutions extracted from the wool displayed a higher amount of more polar compounds, but also a higher amount of aglycones. Importantly, the chromatographic profiles of the samples we prepared compared well with 17th c. yellows in Persian carpets, and therefore can be considered highly characterized references for the study of Persian yellowThis work provides new knowledge on natural yellows used in Iran. Seven biological sources were selected based on interviews with dye masters in Isfahan workshops (Iran). Delphinium semibarbatum, Eremostachys laevigata, Prangos ferulacea, Morus alba, Pistacia vera, Punica granatum, and Vitis vinifera are currently used in these workshops. Aiming to study the dye composition of wool samples dyed with the extracts of the selected biological sources and the changes induced by the dyeing procedures in the original chemical composition of the plant extract, raw materials and dyed wool (by us and in the workshops) were analyzed by HPLC–DAD and UHPLC–HRMS/MS. The main yellows for E. laevigata are luteolin-O-glycosides. In the other plant sources, the main chromophores are based on 3-O-glycosides of kaempferol, quercetin, and isorhamnetin. In pistachio hulls, myricitin derivatives were detected and we propose their use as markers. Generally, the solutions extracted from the wool displayed a higher amount of more polar compounds, but also a higher amount of aglycones. Importantly, the chromatographic profiles of the samples we prepared compared well with 17th c. yellows in Persian carpets, and therefore can be considered highly characterized references for the study of Persian yellows.publishersversionpublishe

Biofouling in tubes: some trends and perspectives

A significant increase in the literature concerning the formation of biological deposits in tubes has been noticed in the last few years. Yet, the scope of the majority of the reports is limited to the study of a single operating parameter. Besides, the operating conditions differ significantly from case to case, renderino difficult the absortion of the available information. In this work, a survey of the most recent publications on the subject of tube biofouling is undertaken, as a means of clarifying further research proprams. Emphasis is placed on the systems used, experimental equipments adopted and, essentially on the parameters studied. Of these, specially attention is qiven to the influence of tube material and roughness, foulant type and concentration, fluid velocity and temperature field

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

Space, City and Post colonialism in the Poetic Discourse of the “Independent Writers of Pernambuco”

In Altas literaturas (High Literatures), Leyla Perrone Moisés reminds us that in the scope of Catholicism the canon acquired the meaning of a "list of saints recognized by the papal authority" which "by extension came to mean the set of literary authors recognized as masters of tradition" (1988, p. 61) .That, undoubtedly, guided the literary studies in Brazil until very recently. These studies ignored non-canonical literary works. In other words, the canonical thinking was oblivious to a rich literary production which was not in accordance with a colonialist view of the academic studies developed in our universities. In this work, we intend to study the literary production of some poets in Recife (Brazil), in the 1980s in relation to the established canon. We focus on the Movement, known as “Independent Writers of Pernambuco” aiming to bring to light a literary movement forgotten by Brazilian academic community.. Our study has a postcolonial perspectives we explore the need to pay attention to literary production by writers who do not always belong to “traditional canon” (Said, 2004). The poetical works of the movement we study may play a vital role in the context of Brazil and Pernambuco. By considering the emerging social responsibilities of writers and intellectuals in an ever more interdependent world, we suggest that studying the movement and its authors who are not much explored by Brazilian scholars we may be decolonizing the knowledge on literature in Brazil. Wetake into account the movement´s relations with Brazilian Northeastern culture and its program of action, dating from 1981, the beginning of the so-called "Lost Decade." The movement had an important voice against the most conservative and traditionalist criticism at that time. We believe that by studying the movement we are offering the opportunity to rethink our Brazilian and Pernambucan literary canon

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