624 research outputs found
Flocculation on a chip: a novel screening approach to determine floc growth rates and select flocculating agents
Flocculation is a key purification step in cell-based processes for the food and pharmaceutical industry
where the removal of cells and cellular debris is aided by adding flocculating agents. However, finding the
best suited flocculating agent and optimal conditions to achieve rapid and effective flocculation is a nontrivial
task. In conventional analytical systems, turbulent mixing creates a dynamic equilibrium between floc
growth and breakage, constraining the determination of floc formation rates. Furthermore, these systems
typically rely on end-point measurements only. We have successfully developed for the first time a microfluidic
system for the study of flocculation under well controlled conditions. In our microfluidic device
(ÎŒFLOC), floc sizes and growth rates were monitored in real time using high-speed imaging and computational
image analysis. The on-line and in situ detection allowed quantification of floc sizes and their growth
kinetics. This eliminated the issues of sample handling, sample dispersion, and end-point measurements.
We demonstrated the power of this approach by quantifying the growth rates of floc formation under forty
different growth conditions by varying industrially relevant flocculating agents (pDADMAC, PEI, PEG), their
concentration and dosage. Growth rates between 12.2 ÎŒm sâ1 for a strongly cationic flocculant (pDADMAC)
and 0.6 ÎŒm sâ1 for a non-ionic flocculant (PEG) were observed, demonstrating the potential to rank flocculating
conditions in a quantitative way. We have therefore created a screening tool to efficiently compare
flocculating agents and rapidly find the best flocculating condition, which will significantly accelerate early
bioprocess development
Productive restructuring and the reallocation of work and employment: a survey of the ânewâ forms of social inequality
O propĂłsito do presente artigo consiste
em questionar a inevitabilidade dos processos de
segmentação e precarização das relaçÔes de trabalho
e emprego, responsåveis pela inscrição de
ânovasâ formas de desigualdade social que alicerçam
o actual modelo de desenvolvimento das economias
e sociedades. Visa-se criticar os limites da
lĂłgica econĂŽmica e financeira, de contornos globais,
que configuram um ânovo espĂrito do capitalismoâ,
ou seja, uma espécie de divinização da
ordem natural das coisas. ImpÔe-se fazer, por isso,
um pĂ©riplo analĂtico pelas transformaçÔes em curso
no mercado de trabalho, acompanhado pela vigilĂąncia
epistemolĂłgica que permita enquadrar e
relativizar as (di)visÔes neoliberais e teses tecnodeterministas
dominantes. A perspectivação de cenårios
sobre o futuro do trabalho encerrarĂĄ este
périplo, permitindo-nos alertar para os condicionalismos
histĂłrico-temporais, para a urgĂȘncia de
se desocultar o que de ideolĂłgico e polĂtico existe
nas actuais lógicas de racionalização e para os
processos de ressimbolização do trabalho e emprego
enquanto âexperiĂȘncia social centralâ na
contemporaneidade.The scope of this paper is to question
the inevitability of the processes of segmentation
and increased precariousness of the relations
of labor and employment, which are responsible
for the introduction of ânewâ forms of
social inequality that underpin the current model
of development of economies and societies. It
seeks to criticize the limits of global financial and
economic logic, which constitute a ânew spirit of
capitalism,â namely a kind of reverence for the
natural order of things. It is therefore necessary
to conduct an analytical survey of the ongoing
changes in the labor market, accompanied by epistemological
vigilance which makes it possible to
see neoliberal (di)visions and dominant technodeterministic
theses in context. The enunciation
of scenarios on the future of work will conclude
this survey and will make it possible to draw attention
to both the historical and temporal constraints
and to the urgent need to unveil what is
ideological and political in the prevailing logic of
rationalization and processes to reinstate work
and employment as a âcentral social experienceâ
in contemporary times
Phenotypic and genotypic monitoring of Schistosoma mansoni in Tanzanian schoolchildren five years into a preventative chemotherapy national control programme
We conducted combined in vitro PZQ efficacy testing with population genetic analyses of S. mansoni collected from children from two schools in 2010, five years after the introduction of a National Control Programme. Children at one school had received four annual PZQ treatments and the other school had received two mass treatments in total. We compared genetic differentiation, indices of genetic diversity, and estimated adult worm burden from parasites collected in 2010 with samples collected in 2005 (before the control programme began) and in 2006 (six months after the first PZQ treatment). Using 2010 larval samples, we also compared the genetic similarity of those with high and low in vitro sensitivity to PZQ
Modelling and analysis of time dependent processes in a chemically reactive mixture
In this paper, we study the propagation of sound waves and the dynamics of local wave disturbances
induced by spontaneous internal fluctuations in a reactive mixture. We consider a non-diffusive, non-heat
conducting and non-viscous mixture described by an Eulerian set of evolution equations. The model is derived from the kinetic theory in a hydrodynamic regime of a fast chemical reaction. The reactive source terms are explicitly computed from the kinetic theory and are built in themodel in a proper way. For both time-dependent problems, we first derive the appropriate dispersion relation, which retains the main effects of the chemical process, and then investigate the influence of the chemical reaction on the properties of interest in the problems studied here. We complete our study by developing a rather detailed analysis using the HydrogenâChlorine system as reference. Several numerical computations are included illustrating the behavior of the phase velocity and attenuation coefficient in a low-frequency regime and describing the spectrum of the eigenmodes in the small wavenumber limit.The paper is partially supported by the Research Centre of Mathematics of the University of Minho, with the Portuguese Funds from the Foundation for Science and Technology (FCT) through the Project UID/MAT/00013/2013. We wish to thank the anonymous Referees for their valuable comments and suggestions that helped us to improve the paper.info:eu-repo/semantics/publishedVersio
Environmental variables, habitat discontinuity and life history shaping the genetic structure of Pomatoschistus marmoratus
Coastal lagoons are semi-isolated ecosystems
exposed to wide fluctuations of environmental conditions
and showing habitat fragmentation. These features may
play an important role in separating species into different
populations, even at small spatial scales. In this study, we
evaluate the concordance between mitochondrial (previous
published data) and nuclear data analyzing the genetic
variability of Pomatoschistus marmoratus in five localities,
inside and outside the Mar Menor coastal lagoon (SE
Spain) using eight microsatellites. High genetic diversity
and similar levels of allele richness were observed across
all loci and localities, although significant genic and
genotypic differentiation was found between populations
inside and outside the lagoon. In contrast to the FST values
obtained from previous mitochondrial DNA analyses
(control region), the microsatellite data exhibited significant
differentiation among samples inside the Mar Menor
and between lagoonal and marine samples. This pattern
was corroborated using Cavalli-Sforza genetic distances.
The habitat fragmentation inside the coastal lagoon and
among lagoon and marine localities could be acting as a
barrier to gene flow and contributing to the observed
genetic structure. Our results from generalized additive
models point a significant link between extreme lagoonal
environmental conditions (mainly maximum salinity) and
P. marmoratus genetic composition. Thereby, these environmental
features could be also acting on genetic structure
of coastal lagoon populations of P. marmoratus favoring
their genetic divergence. The mating strategy of P. marmoratus
could be also influencing our results obtained from
mitochondrial and nuclear DNA. Therefore, a special
consideration must be done in the selection of the DNA
markers depending on the reproductive strategy of the
species
Genome of the Avirulent Human-Infective TrypanosomeâTrypanosoma rangeli
Background: Trypanosoma rangeli is a hemoflagellate protozoan parasite infecting humans and other wild and domestic mammals across Central and South America. It does not cause human disease, but it can be mistaken for the etiologic agent of Chagas disease, Trypanosoma cruzi. We have sequenced the T. rangeli genome to provide new tools for elucidating the distinct and intriguing biology of this species and the key pathways related to interaction with its arthropod and mammalian hosts. Methodology/Principal Findings: The T. rangeli haploid genome is ,24 Mb in length, and is the smallest and least repetitive trypanosomatid genome sequenced thus far. This parasite genome has shorter subtelomeric sequences compared to those of T. cruzi and T. brucei; displays intraspecific karyotype variability and lacks minichromosomes. Of the predicted 7,613 protein coding sequences, functional annotations could be determined for 2,415, while 5,043 are hypothetical proteins, some with evidence of protein expression. 7,101 genes (93%) are shared with other trypanosomatids that infect humans. An ortholog of the dcl2 gene involved in the T. brucei RNAi pathway was found in T. rangeli, but the RNAi machinery is non-functional since the other genes in this pathway are pseudogenized. T. rangeli is highly susceptible to oxidative stress, a phenotype that may be explained by a smaller number of anti-oxidant defense enzymes and heatshock proteins. Conclusions/Significance: Phylogenetic comparison of nuclear and mitochondrial genes indicates that T. rangeli and T. cruzi are equidistant from T. brucei. In addition to revealing new aspects of trypanosome co-evolution within the vertebrate and invertebrate hosts, comparative genomic analysis with pathogenic trypanosomatids provides valuable new information that can be further explored with the aim of developing better diagnostic tools and/or therapeutic targets
DNA Encoding an HIV-1 Gag/Human Lysosome-Associated Membrane Protein-1 Chimera Elicits a Broad Cellular and Humoral Immune Response in Rhesus Macaques
Previous studies of HIV-1 p55Gag immunization of mice have demonstrated the usefulness of targeting antigens to the cellular compartment containing the major histocompatibility complex type II (MHC II) complex molecules by use of a DNA antigen formulation encoding Gag as a chimera with the mouse lysosome-associated membrane protein (mLAMP/gag). In the present study, we have analyzed the magnitude and breadth of Gag-specific T-lymphocyte and antibody responses elicited in Rhesus macaques after immunization with DNA encoding a human LAMP/gag (hLAMP/gag) chimera. ELISPOT analyses indicated that the average Gag-specific IFN-Îł response elicited by the hLAMP/gag chimera was detectable after only two or three naked DNA immunizations in all five immunized macaques and reached an average of 1000 spot-forming cells (SFC)/10(6) PBMCs. High IFN-Îł ELISPOT responses were detected in CD8(+)-depleted cells, indicating that CD4(+) T-cells play a major role in these responses. The T-cell responses of four of the macaques were also tested by use of ELISPOT to 12 overlapping 15-amino acids (aa) peptide pools containing ten peptides each, encompassing the complete Gag protein sequence. The two Mamu 08 immunized macaques responded to eight and twelve of the pools, the Mamu B01 to six, and the other macaque to five pools indicating that the hLAMP/gag DNA antigen formulation elicits a broad T-cell response against Gag. Additionally, there was a strong HIV-1-specific IgG response. The IgG antibody titers increased after each DNA injection, indicating a strong amnestic B-cell response, and were highly elevated in all the macaques after three immunizations. Moreover, the serum of each macaque recognized 13 of the 49 peptides of a 20-aa peptide library covering the complete Gag amino acid sequence. In addition, HIV-1-specific IgA antibodies were present in the plasma and external secretions, including nasal washes. These data support the findings of increased immunogenicity of genetic vaccines encoded as LAMP chimeras, including the response to DNA vaccines by non-human primates
- âŠ