Effect of particle size distribution and dynamics on the performance of two-dimensional packing

AbstractExtensive computer simulation is used to revisit and to generalize two classical problems: (i) the random car-parking dynamics of A. Rényi and (ii) the irreversible random sequential adsorption (RSA) of parallel squares of same size on a planar substrate of area L2. In this paper, differently from the classical RSA, the squares obey the size distribution n(a)=n(1)a−τ, where a=1,2,3,… is the area of the squares. Using this scaling distribution and three classes of packing dynamics we study the final packing fraction of particles, ⊖(τ,L), and in particular its thermodynamic limit L→∞. We show that the efficiency to attain a high/low packing density of particles on the substrate is strongly dependent on the value of the exponent τ and on the characteristics of the dynamics

The relationship between fatty acids and fish: lesser-known aspects and the need for increasingly efficient analytical techniques

When we associate the word fatty acids with fish, most people identify fish as sources of fatty acids from the omega families. This relationship is always present in the valuation of nutritional quality of fish. However, fatty acids have many other crucial functions in fish. The oldest studies related to fatty acids focused essentially on their role as sources metabolic energy in the form of ATP through β-oxidation. Many studies referred the fatty acid role for migrations, energy production during growth and egg formation, among others. Soon fatty acids quickly began to be studied from the point of view of source of essential nutrients for several physiological processes and integral components of biological membranes. The high content of highly polyunsaturated fatty acids found in fish is related to the fact that they are poikilothermic. In the presence of various temperature scenarios, fish can effectively exploit a wide chemical diversity of membrane fatty acid profiles, to defend their physical properties, such as fluidity. In the last decades, fatty acids have been used as either biomarkers because they are limited to certain taxa and they can be transferred conservatively from primary producers to higher trophic level or stock identifiers because the fatty acid composition of phospholipids in some body tissues have a stable genetics basis. In the last decades multiple techniques have been used for fatty acid analysis. As a rule, before the instrumental analysis, the sample requires 2 previous steps. These comprise extraction of lipids from the matrix and derivatization. The combination of these two stages generates multiple methodologies that are not always standardized. Soon, the analysis of fatty acids tends to reduce and standardize these previous analyses while the instrumental analysis should solve problems related to similar mass spectra of the isomers and coelution between fatty acidsFundação para a Ciência e Tecnologia (FCT) for a PhD scholarship UI/BD/153381/2022.This work was funding by National Funds through FCT - Foundation for Science and Technology under the Project PTDC/BIA-BMA/030517/2017 and the Portuguese Science Foundation through the strategy plan for MED (Mediterranean Institute for Agriculture, Environment and Development), via project UIDB/05183/2020, for MARE (Marine and Environmental Sciences Centre), via project UIDB/04292/2020, UID/50006/2020, and under the project LA/P/0069/2020 granted to the Associate Laboratory ARNET; and for LAQV-REQUIMTE, via project UIDB/50006/2020 and UIDP/50006/202

Microlenses array made with AZ4562 photoresist for stereoscopic acquisition

In this paper is presented a fabrication process for obtaining refractive microlenses arrays with high reproducibility and low cost. This process was specifically optimized for the AZ4562 photoresist. Functional prototypes of microlenses arrays with dimensions in the range of 30 m, 4.9 mm and 5 m for width, length and thickness, respectively, were fabricated and tested. The pre-thermal reflow spacing between adjacent isosceles trapezoids is 1.35-5.43 m, from bottom to top, respectively. This separation allows the photoresist to reflow and join the adjacent microlens creating a consistent and homogeneous array.This work and Rui Pedro Rocha are fully supported by the Portuguese Foundation for Science and Technology under the project FCT/PTDC/EEA-ELC/109936/2009 and the financial grant SFRH/BD/33733/2009, respectively. The authors would also like to acknowledge Dr.-Ing Christian Koch from MicroChemicals GmbH for the technical support

Hysteresis in the Mott Transition between Plasma and Insulating Gas

We show that hysteresis can occur in the transition between a neutral plasma and the insulating gas consisting of neutral pairs bound by Coulomb attraction. Since the transition depends sensitively on the screening length in the plasma, regions of bistability occur in density--temperature phase space. We present numerical results which indicate where these regions occur for systems such as spin-polarized hydrogen, positronium gas, and excitons in a semiconductor.Comment: 9 pages (Latex/RevTex), 6 postscript figures which are in compressed and uuencoded file, prepared using the utility "uufiles" and separately submitted. They should be automatically included with the text when it is downloaded. Figures also available in hard copy from the authors ([email protected]; [email protected]); paper submitted to Phys. Rev.

Genetic characterization of Guinea-Bissau using a 12 X-chromosomal STR system: inferences from a multiethnic population

A male West African sample from Guinea-Bissau (West-African coast) was genetically analyzed using 12 X chromosomal short tandem repeats that are grouped into four haplotype groups. Linkage disequilibrium was tested (p ≤ 0.0008) and association was detected for the majority of markers in three out of the four studied haplotype clusters. The sample of 332 unrelated individuals analyzed in this study belonged to several recognized ethnic groups (n = 18) which were used to evaluate the genetic variation of Guinea-Bissau’s population. Pairwise genetic distances (FST) did not reveal significant differences among the majority of groups. An additional 110 samples from other countries also belonging to West Africa were as well compared with the sample of Guinea-Bissau. No significant differences were found between these two groups of West African individuals, supporting the genetic homogeneity of this region on the X chromosome level. The generation of over 100 DNA West African sequences provided new insights into the repeat sequence structure of some of the present X-STRs. Parameters for forensic evaluation were also calculated for each X-STR, supporting the potential application of these markers in typical kinship scenarios. Also, the high power of discrimination values for samples of female and male origin observed in this study, confirms the usefulness of the present X-STRs in identification analysis.info:eu-repo/semantics/publishedVersio

In vitro evaluation of five antimicrobial peptides against the plant pathogen Erwinia amylovora

Fire blight is a major pome fruit trees disease that is caused by the quarantine phytopathogenic Erwinia amylovora, leading to major losses, namely, in pear and apple productions. Nevertheless, no effective sustainable control treatments and measures have yet been disclosed. In that regard, antimicrobial peptides (AMPs) have been proposed as an alternative biomolecule against pathogens but some of those AMPs have yet to be tested against E. amylovora. In this study, the potential of five AMPs (RW-BP100, CA-M, 3.1, D4E1, and Dhvar-5) together with BP100, were assessed to control E. amylovora. Antibiograms, minimal inhibitory, and bactericidal concentrations (minimal inhibitory concentration (MIC) and minimal bactericidal concentration (MBC), growth and IC50 were determined and membrane permeabilization capacity was evaluated by flow cytometry analysis and colony-forming units (CFUs) plate counting. For the tested AMPs, the higher inhibitory and bactericidal capacity was observed for RW-BP100 and CA-M (5 and 5–8 M, respectively for both MIC and MBC), whilst for IC50 RW-BP100 presented higher efficiency (2.8 to 3.5 M). Growth curves for the first concentrations bellow MIC showed that these AMPs delayed E. amylovora growth. Flow cytometry disclosed faster membrane permeabilization for CA-M. These results highlight the potential of RW-BP100 and CA-M AMPs as sustainable control measures against E. amylovora.info:eu-repo/semantics/publishedVersio

The DNA damage response is developmentally regulated in the African trypanosome

Genomes are affected by a wide range of damage, which has resulted in the evolution of a number of widely conserved DNA repair pathways. Most of these repair reactions have been described in the African trypanosome Trypanosoma brucei, which is a genetically tractable eukaryotic microbe and important human and animal parasite, but little work has considered how the DNA damage response operates throughout the T. brucei life cycle. Using quantitative PCR we have assessed damage induction and repair in both the nuclear and mitochondrial genomes of the parasite. We show differing kinetics of repair for three forms of DNA damage, and dramatic differences in repair between replicative life cycle forms found in the testse fly midgut and the mammal. We find that mammal-infective T. brucei cells repair oxidative and crosslink-induced DNA damage more efficiently than tsetse-infective cells and, moreover, very distinct patterns of induction and repair of DNA alkylating damage in the two life cycle forms. We also reveal robust repair of DNA lesions in the highly unusual T. brucei mitochondrial genome (the kinetoplast). By examining mutants we show that nuclear alkylation damage is repaired by the concerted action of two repair pathways, and that Rad51 acts in kinetoplast repair. Finally, we correlate repair with cell cycle arrest and cell growth, revealing that induced DNA damage has strikingly differing effects on the two life cycle stages, with distinct timing of alkylation-induced cell cycle arrest and higher levels of damage induced death in mammal-infective cells. Our data reveal that T. brucei regulates the DNA damage response during its life cycle, a capacity that may be shared by many microbial pathogens that exist in variant environments during growth and transmission

Effects of soil management practices and irrigation on plant water relations and productivity of chestnut stands under Mediterranean conditions

The effects of different soil management practices and irrigation on plant water relations, physiological response and productivity of chestnut stands in Northeastern Portugal were assessed during four growing seasons (2003 to 2006). Treatments were: conventional soil tillage up to 15–20 cm depth with a tine cultivator thrice a year (CT); no tillage with spontaneous herbaceous vegetation (NV); no tillage with rainfed seeded pasture (NP); and no tillage with irrigated seeded pasture (NIP). Results suggest that soil water availability was the most critical parameter for chestnut productivity over the study period. In all treatments, high predawn leaf water potentials (-0.40 to -0.55 MPa) were observed during the dry seasons of 2003, 2004 and 2006, showing no critical conditions for plant productivity, which is ascribed to water availability in deep soil layers. In contrast, in 2005, an extremely dry year, water potentials decreased and varied from -1.46 to - 1.72 MPa in late summer, showing unfavourable conditions for nut production. Maintenance of spontaneous herbaceous vegetation without irrigation enhanced productivity of chestnut stands as compared with the conventional tillage system and the no tillage system with seeded pasture. Productivity in the soil watering system (NIP treatment) was not significantly different from that observed in the NV treatment. Therefore, studies on the irrigation strategy should be developed, in order to increase its efficiency especially in stands with young tree

Urinary levels of monohydroxyl PAH metabolites in portuguese firefighters: background levels and impact of tobacco smoke

Firefighting occupational exposure is classified as possible carcinogen to humans by the International Agency for Research on Cancer and the US National Institute for Occupational Safety and Health [1,2]. Tobacco smoke is a very important factor in the assessment of occupational exposure of workers, since the prolonged exposure to tobacco smoke is by itself the major cause of lung cancer [3]. The consumption of tobacco is responsible for the exposure to many smoke components including more than sixty known carcinogens, including some polycyclic aromatic hydrocarbons (PAHs) [4]. PAHs are ubiquitous compounds formed during pyrolysis or incomplete combustion of organic matter, being well-known for their toxic, mutagenic, and carcinogenic properties to humans [5,6]. So far, the impact of tobacco smoke on firefighters’ total exposure to PAHs is very limited.info:eu-repo/semantics/publishedVersio

Characterization of the soil of peach orchards in the region of Beira Interior

A cultura do pessegueiro na região da Beira Interior representa 23% da área total de pessegueiro de Portugal continental e 16% da área de culturas permanentes da região. Para a caracterização do potencial edáfico onde se desenvolve a cultura, foi efectuado um trabalho de sistematização dos dados referentes às análises de terra, através das Organizações de Agricultores reconhecidas para a prática da Protecção Integrada e Produção Integrada de Prunóideas (AAPIM, APPIZÊZERE e Cooperativa dos Fruticultores da Cova da Beira). O total das 117 análises disponíveis diz respeito ao conjunto de agricultores que exploram uma área de pessegueiros de 463 ha, o que corresponde a um terço da área total ocupada pela cultura na região (1500 ha). O conjunto dos dados analisados permitiu concluir que os solos são maioritariamente ácidos, apresentando textura grosseira, baixo teor de matéria orgânica e elevados teores de fósforo e potássio assimiláveis na camada superficial.info:eu-repo/semantics/publishedVersio