In situ characterization of porous VPO catalysts with fibrous structure: Identifying the redox behavior and the stability of active sites

Two VPO materials with fibrillar morphology have been prepared by the aid of electrospinning technique. One is a VPO carbon-supported material (VCF200) with fibrous morphology and very high surface area that is stable under oxidizing conditions up to 350C. The other material is a bulk mixed VPO oxide (VPO500) with fibrous structure obtained after optimizing the calcination of the carbon support in VCF200. Despite it is a bulk oxide material, this material exhibits a high surface area (> 60 m2/g). The redox behavior of both samples was monitored by in situ Raman spectroscopy under oxidation/reduction cycles. For the dehydrated supported sample (VCF200), the pyrophosphate phase (VO)2P2O7 (Raman ~930 cm-1) is detected, which has been described as the active phase (see Figure (a) below). This phase is quite stable since it does not disappear upon subsequent oxidation/reduction cycles. Under reduction conditions at 125C, in consecutive cycles, additional Raman bands appear at ~1090 cm-1 that are characteristic of the αII-VOPO4 phase. On the other hand, the bulk phases show a reversible behavior under redox cycles (Figure (b)). Under reducing conditions, a Raman band appears at ~980 cm-1 (β-VPO phase), whereas under oxidation conditions some segregation to VOx oxides occurs. Nevertheless, this segregation is reversible and the β-VPO phase forms again under reducing conditions. Thus, these results demonstrate that the active VPO phases of these fibrous catalysts are quite stable, and that their structure is reversible under several redox cycles, which make them suitable as oxidation catalysts.

A Livestock-Associated, Multidrug-Resistant, Methicillin-Resistant Staphylococcus aureus Clonal Complex 97 Lineage Spreading in Dairy Cattle and Pigs in Italy

Pandemic methicillin-resistant Staphylococcus aureus (MRSA) clonal complex 97 (CC97) lineages originated from livestock-to-human host jumps. In recent years, CC97 has become one of the major MRSA lineages detected in Italian farmed animals. The aim of this study was to characterize and analyze differences in MRSA and methicillin-susceptible S. aureus (MSSA) mainly of swine and bovine origins. Forty-seven CC97 isolates, 35 MRSA isolates, and 6 MSSA isolates from different Italian pig and cattle holdings; 5 pig MRSA isolates from Germany; and 1 human MSSA isolate from Spain were characterized by macrorestriction pulsed-field gel electrophoresis (PFGE) analysis, multilocus sequence typing (MLST), spa typing, staphylococcal cassette chromosome mec (SCCmec) typing, and antimicrobial resistance pattern analysis. Virulence and resistance genes were investigated by PCR and microarray analysis. Most of the isolates were of SCCmec type V (SCCmec V), except for two German MRSA isolates (SCCmec III). Five main clusters were identified by PFGE, with the German isolates (clusters I and II) showing 60.5% similarity with the Italian isolates, most of which (68.1%) grouped into cluster V. All CC97 isolates were Panton-Valentine leukocidin (PVL) negative, and a few (n = 7) tested positive for sak or scn. All MRSA isolates were multidrug resistant (MDR), and the main features were erm(B)- or erm(C)-mediated (n = 18) macrolide-lincosamide-streptogramin B resistance, vga(A)-mediated (n = 37) pleuromutilin resistance, fluoroquinolone resistance (n = 33), tet(K) in 32/37 tet(M)-positive isolates, and blaZ in almost all MRSA isolates. Few host-associated differences were detected among CC97 MRSA isolates: their extensive MDR nature in both pigs and dairy cattle may be a consequence of a spillback from pigs of a MRSA lineage that originated in cattle as MSSA and needs further investigation. Measures should be implemented at the farm level to prevent spillover to humans in intensive farming areas.

Risk factors associated with negative in-vivo diagnostic results in bovine tuberculosis-infected cattle in Spain

BACKGROUND Despite great effort and investment incurred over decades to control bovine tuberculosis (bTB), it is still one of the most important zoonotic diseases in many areas of the world. Test-and-slaughter strategies, the basis of most bTB eradication programs carried out worldwide, have demonstrated its usefulness in the control of the disease. However, in certain countries, eradication has not been achieved due in part to limitations of currently available diagnostic tests. In this study, results of in-vivo and post-mortem diagnostic tests performed on 3,614 animals from 152 bTB-infected cattle herds (beef, dairy, and bullfighting) detected in 2007-2010 in the region of Castilla y León, Spain, were analyzed to identify factors associated with positive bacteriological results in cattle that were non-reactors to the single intradermal tuberculin test, to the interferon-gamma (IFN-γ) assay, or to both tests applied in parallel (Test negative/Culture + animals, T-/C+). The association of individual factors (age, productive type, and number of herd-tests performed since the disclosure of the outbreak) with the bacteriology outcome (positive/negative) was analyzed using a mixed multivariate logistic regression model. RESULTS The proportion of non-reactors with a positive post-mortem result ranged from 24.3% in the case of the SIT test to 12.9% (IFN-γ with 0.05 threshold) and 11.9% (95% CI 9.9-11.4%) using both tests in parallel. Older (>4.5 years) and bullfighting cattle were associated with increased odds of confirmed bTB infection by bacteriology, whereas dairy cattle showed a significantly lower risk. Ancillary use of IFN-γ assay reduced the proportion of T-/C + animals in high risk groups. CONCLUSIONS These results demonstrate the likelihood of positive bacteriological results in non-reactor cattle is influenced by individual epidemiological factors of tested animals. Increased surveillance on non-reactors with an increased probability of being false negative could be helpful to avoid bTB persistence, particularly in chronically infected herds. These findings may aid in the development of effective strategies for eradication of bTB in Spain.

Sticking non-stick: surface and structure control of diamond-like carbon in plasma enhanced chemical vapour deposition

This short review article explores the practical use of diamond-like carbon (DLC) produced by plasma enhanced chemical vapour deposition (PECVD). Using as an example issues relating to the DLC coating of a hand-held surgical device, we draw on previous works using atomic force microscopy, X-ray photoelectron spectroscopy, Raman spectroscopy, scanning electron microscopy, tensiometry and electron paramagnetic resonance. Utilising data from these techniques, we examine the surface structure, substrate-film interface and thin film microstructure, such as sp2/sp3 ratio (graphitic/diamond-like bonding ratio) and sp2 clustering. We explore the variations in parameters describing these characteristics, and relate these to the final device properties such as friction, wear resistance, and diffusion barrier integrity. The material and device characteristics are linked to the initial plasma and substrate conditions.

Caracterização material e microbiológica de espécimes fotográficos

Neste trabalho foram estudadas quatro espécies fotográficas, dois ambrótipos do séc. XIX e dois negativos de gelatina do séc. XX. Estas espécies são suscetiveis a degradações, físicas, químicas e microbiológicas. Técnicas de análise não destrutivas como, a fotografia, a microscopia ótica, a microscopia eletrónica de varrimento e espetroscopia de raios-X por dispersão em energias, a micro-espetroscopia de infravermelho em modo de reflexão total atenuada, a micro-espetroscopia de Raman e a micro-difração de raios-X foram utilizadas na caracterização material. A colonização microbiológica das amostras foi estudada através do isolamento e caracterização dos microrganismos contaminantes. Foram ainda realizados estudos de determinação de atividade celulolítica para os isolados fúngicos provenientes dos ambrótipos bem como ensaios de simulação, nos quais se utilizaram estes isolados para induzir contaminação em ambrótipos contemporâneos e assim avaliar o seu potencial biodeteriogénico. Foi ainda avaliado o potencial biodeteriogénico de isolados bacterianos em negativos de gelatina contemporâneos; Abstract: Material and microbiological characterization of photographic specimens This work presents a scientific study of four photographic specimens, two ambrotypes and two gelatin-silver negative plates from 19th and 20th century, respectively. These specimens are susceptible to physical, chemical and microbiological degradations. A non-destructive approach was used based on techniques such as technical photography, optical microscopy, scanning electron microscopy, infrared micro-spectroscopy, micro-Raman spectroscopy and X-rays micro-diffraction. Microbiological colonization of the samples was studied by isolation and characterization of the contaminating microorganisms. Studies to evaluate cellulolytic activity of fungal isolates from the ambrotypes were carried out and also simulation assays in which were used these isolated to induce contamination in contemporary ambrotypes were done to evaluate their biodeteriogenic potential. It was also studied the biodeteriogenic potential of the bacterial isolates from gelatin-silver negative plates which were subsequently inoculated in contemporary gelatin-silver negatives.

Coupling instrumentation and methodology in the search for traces of life on the early Earth and Mars

Evaluating the nature of the earliest, often controversial, traces of life in the geological record (dating to the Palaeoarchaean, up to ~3.5 billion years before the present) is of fundamental relevance for placing constraints on the potential that life emerged on Mars at approximately the same time (the Noachian period). In their earliest histories, the two planets shared many palaeoenvironmental similarities, before the surface of Mars rapidly became inhospitable to life as we know it. Multi-scalar, multi-modal analyses of fossiliferous rocks from the Barberton greenstone belt of South Africa and the East Pilbara terrane of Western Australia are a window onto primitive prokaryotic ecoystems. Complementary petrographic, morphological, (bio)geochemical and nanostructural analyses of chert horizons and the carbonaceous material within using a wide range of techniques – including optical microscopy, SEM-EDS, Raman spectroscopy, PIXE, µCT, laser ablation ICP-MS, high-resolution TEM-based analytical techniques and secondary ion mass spectrometry – can characterise, at scales from macroscopic to nanoscopic, the fossilised biomes of the earliest Earth. These approaches enable the definition of the palaeoenvironments, and potentially metabolic networks, preserved in ancient rocks. Modifying these protocols is necessary for Martian exploration using rovers, since the range and power of space instrumentation is significantly reduced relative to terrestrial laboratories. Understanding the crucial observations possible using highly complementary rover-based payloads is therefore critical in scientific protocols aiming to detect traces of life on Mars.

A multi-methodological approach for the study of polymorphism in organic pigments and pharmaceuticals

The study of polymorphism has an important role in several fields of materials science, because structural differences lead to different physico-chemical properties of the system. This PhD work was dedicated to the investigation of polymorphism in Indigo, Thioindigo and Quinacridone, as case studies among the organic pigments employed as semiconductors, and in Paracetamol, Phenytoin and Nabumetone, chosen among some commonly used API. The aim of the research was to improve the understanding on the structures of bulk crystals and thin films, adopting Raman spectroscopy as the method of choice, while resorting to other experimental techniques to complement the gathered information. Different crystalline polymorphs, in fact, may be conveniently distinguished by their Raman spectra in the region of the lattice phonons (10-150 cm-1), the frequencies of which, probing the inter-molecular interactions, are very sensitive to even slight modifications in the molecular packing. In particular, we have used Confocal Raman Microscopy, which is a powerful, yet simple, technique for the investigation of crystal polymorphism in organic and inorganic materials, being capable of monitoring physical modifications, chemical transformations and phase inhomogeneities in crystal domains at the micrometre scale. In this way, we have investigated bulk crystals and thin film samples obtained with a variety of crystal growth and deposition techniques. Pure polymorphs and samples with phase mixing were found and fully characterized. Raman spectroscopy was complemented mainly by XRD measurements for bulk crystals and by AFM, GIXD and TEM for thin films. Structures and phonons of the investigated polymorphs were computed by DFT methods, and the comparison between theoretical and experimental results was used to assess the relative stability of the polymorphs and to assist the spectroscopic investigation. The Raman measurements were thus found to be able to clarify ambiguities in the phase assignments which otherwise the other methods were unable to solve.

Sewage sludge as organic fertilizer in agriculture. A study of physico-chemical properties, agronomic efficiency and environmental safety, with a specific focus on tannery sludge

In recent decades, the use of organic fertilizers has gained increasing interest mainly for two reasons: their ability to improve soil fertility and the need to find a sustainable alternative to mineral and synthetic fertilizers. In this context, sewage sludge is a useful organic matrix that can be successfully used in agriculture, due to its chemical composition rich in organic matter, nitrogen, phosphorus and other micronutrients necessary for plant growth. This work investigated three indispensable aspects (i.e., physico-chemical properties, agronomic efficiency and environmental safety) of sewage sludge application as organic fertilizer, emphasizing the role of tannery sludge. In a comparison study with municipal sewage sludge, results showed that the targeted analyses applied (total carbon and nitrogen content, isotope ratio of carbon and nitrogen, infrared spectroscopy and thermal analysis) were able to discriminate tannery sludge from municipal ones, highlighting differences in composition due to the origin of the wastewater and the treatment processes used in the plants. Regarding agronomic efficiency, N bioavailability was tested in a selection of organic fertilizers, including tannery sludge and tannery sludge-based fertilizers. Specifically, the hot-water extractable N has proven to be a good chemical indicator, providing a rapid and reliable indication of N bioavailability in soil. Finally, the behavior of oxybenzone (an emerging organic contaminant detected in sewage sludge) in soils with different physico-chemical properties was studied. Through adsorption and desorption experiments, it was found that the mobility of oxybenzone is reduced in soils rich in organic matter. Furthermore, through spectroscopic methods (e.g., infrared spectroscopy and surface-enhanced Raman spectroscopy) the mechanisms of oxybenzone-humic acids interaction were studied, finding that H-bonds and π-π stacking were predominantly present.

Role of Shiga toxins in the pathogenesis of hemolytic uremic syndrome

During the pathogenesis of hemolytic uremic syndrome (HUS), a severe sequela of Shiga toxin (Stx)-producing Escherichia coli (STEC) gastrointestinal infections, before the toxin acts on the target endothelial cells of the kidney and brain, several Stx forms are transported in the bloodstream: free Stx; Stx bound to circulating cells through Gb3Cer and TLR4 receptors; and Stx associated to blood cell-derived microvesicles. The latter form is mainly responsible for the development of life-threatening HUS in 15% of STEC-infected patients. Stx consist of five B subunits non-covalently bound to a single A subunit (uncleaved Stx) which can be cleaved in two fragments (A1 and A2) held by a disulfide bond (cleaved Stx). After reduction, the enzymatically active A1 fragment responsible for toxicity is released. Cleaved and uncleaved Stx are biologically active but functionally different, thus their presence in patients’ blood could affect the onset of HUS. Currently, there are no effective therapies for the treatment of STEC-infected patients and the gold standard strategies available for the diagnosis are very expensive and time-consuming. In this thesis, by exploiting the resolving power of SERS technology (Amplified Raman Spectroscopy on Surfaces), a plasmonic biosensor was developed as effective diagnostic tool for early detection of Stx in patients’ sera. An acellular protein synthesis system for detecting cleaved Stx2a in human serum based on its greater translation inhibition after treatment with reducing agents was developed and used to identify cleaved Stx in STEC-infected patients’ sera. Pathogenic microvesicles from Stx2a-challenged blood from healthy donors were isolated and characterized. The antibiotic NAB815, acting as inhibitor of toxin binding to TLR4 expressed by circulating cells, was found to be effective in impairing the formation of blood cell-derived microvesicles containing Stx2a, also having a protective effect in cellular models. This approach could be proposed as an innovative treatment for HUS prevention.

Effect of Potato virus X on total phenol and alkaloid contents in Datura stramonium leaves

The present paper reports results of the effect of Potato virus X (PVX) on the contents of total phenols and alkaloids in leaves of Datura stramonium. A significant decrease in the contents of phenols and alkaloids was observed in leaves inoculated with PVX (X-I). However, there was an increase in the percentage of phenols in leaves rubbed with phosphate buffer (C1-I) and in leaves from the nodes immediately above, possibly induced by mechanical injury. Gas chromatography/mass spectroscopy revealed amounts of scopolamine in samples submitted to all treatments, except X-I, in which the amount of this alkaloid was low. High amounts of an unidentified compound (molecular ion m/z 302 and a prominent peak at m/z 129) were noted in extracts from leaves X-I, C1-I and leaves from the nodes immediately above the leaves inoculated with PVX. It is suggested that the synthesis and accumulation of the unidentified compound is a result of stress from mechanical injury and virus inoculation.

Conducting polymer- hydrogel blends for electrochemically controlled drug release devices

Blends formed by electrochemical polymerization of polypyrrole (PPy) into polyacrylamide (PAAm) hydrogels were used as devices for controlled drug release. The influence of several parameters in the synthesis, such as type of hydrogel matrix and polymerization conditions was studied by using a fractional factorial design. The final goal was to obtain an adequate device for use in controlled release tests, based on electrochemical potential control. For controlled release tests, Safranin was used as model drug and release curves (amount of drug vs. time) have shown that these blends are promising materials for this use. The optimized blends obtained were characterized by cyclic voltammetry and Raman spectroscopy.

Análise colorimétrica e espectroscópica do muco de caracóis terrestres Achatina sp alimentados com ração diferenciada

Foram estudados os efeitos da adição de plantas medicinais de princípios cicatrizantes (Centelha asiática, Papaína e Confrei) na ração controle de caracóis terrestres, para se avaliar a interferência destas plantas na composição do muco glicoprotéico. Foram utilizados 80 caracóis terrestres Achatina sp, baseados em um peso homogêneo (49 e 40 g e idade média de 10 e 19 meses para Achatina fulica e Achatina monochromatica, respectivamente). Os animais foram distribuídos aleatoriamente em oito grupos experimentais: controle Achatina fulica (FC) e Achatina monochromatica (MC), centelha asiática Achatina fulica (FCe) e Achatina monochromatica (MCe), papaína Achatina fulica (FPa) e Achatina monochromatica (MPa) e confrei Achatina fulica (FCo) e Achatina monochromatica (MCo). Água e ração foram fornecidos ad libitum. Ao final de 150 dias de tratamento, os animais foram submetidos à técnica de extração do muco glicoprotéico, por meio do estímulo manual da glândula podal, responsável pela secreção deste muco. Esta metodologia considerou o bem-estar dos animais, uma vez que os mesmos não foram sacrificados e retornaram ao seu sistema de criação. Os mucos foram analisados por meio de testes colorimétricos e espectroscópicos, que constataram alterações semelhantes, porém apresentaram variação significativa em sua composição glicoprotéica.

Sequential analysis of global gene expression profiles in immature and in vitro matured bovine oocytes: potential molecular markers of oocyte maturation

Background: Without intensive selection, the majority of bovine oocytes submitted to in vitro embryo production (IVP) fail to develop to the blastocyst stage. This is attributed partly to their maturation status and competences. Using the Affymetrix GeneChip Bovine Genome Array, global mRNA expression analysis of immature (GV) and in vitro matured (IVM) bovine oocytes was carried out to characterize the transcriptome of bovine oocytes and then use a variety of approaches to determine whether the observed transcriptional changes during IVM was real or an artifact of the techniques used during analysis. Results: 8489 transcripts were detected across the two oocyte groups, of which similar to 25.0% (2117 transcripts) were differentially expressed (p < 0.001); corresponding to 589 over-expressed and 1528 under-expressed transcripts in the IVM oocytes compared to their immature counterparts. Over expression of transcripts by IVM oocytes is particularly interesting, therefore, a variety of approaches were employed to determine whether the observed transcriptional changes during IVM were real or an artifact of the techniques used during analysis, including the analysis of transcript abundance in oocytes in vitro matured in the presence of a-amanitin. Subsets of the differentially expressed genes were also validated by quantitative real-time PCR (qPCR) and the gene expression data was classified according to gene ontology and pathway enrichment. Numerous cell cycle linked (CDC2, CDK5, CDK8, HSPA2, MAPK14, TXNL4B), molecular transport (STX5, STX17, SEC22A, SEC22B), and differentiation (NACA) related genes were found to be among the several over-expressed transcripts in GV oocytes compared to the matured counterparts, while ANXA1, PLAU, STC1and LUM were among the over-expressed genes after oocyte maturation. Conclusion: Using sequential experiments, we have shown and confirmed transcriptional changes during oocyte maturation. This dataset provides a unique reference resource for studies concerned with the molecular mechanisms controlling oocyte meiotic maturation in cattle, addresses the existing conflicting issue of transcription during meiotic maturation and contributes to the global goal of improving assisted reproductive technology.

Imprinted gene expression in in vivo- and in vitro-produced bovine embryos and chorio-allantoic membranes

Cloning by nuclear transfer is often associated with poor results due to abnormal nuclear reprogramming of somatic donor cells and altered gene expression patterns. We investigated the expression patterns of imprinted genes IGF2 and IGF2R in 33- to 36-day bovine embryos and chorio-allantoic membranes derived from in vivo- and in vitro-produced embryos by somatic cell nuclear transfer (SCNT), parthenogenetic activation, and in vitro fertilization (IVF). There was a lower IGF2 expression rate in the SCNT (0.19) and parthenogenetic (0.02) groups when compared to in vivo and IVF embryos (2.01; P < 0.05). In the chorio-allantoic membranes, IGF2 showed a baseline expression pattern (P < 0.05) in parthenotes (0.001) when compared to in vivo, IVF (3.13), and SCNT (0.98) groups. IGF2R was less expressed (P < 0.05) in SCNT chorio-allantoic membranes (0.25) when compared to the in vivo group. The low expression of IGF2 in parthenogenetic embryos and chorio-allantoic membranes confirms its imprinted status in cattle. Alterations in the relative frequency of IGF2 and IGF2R transcripts were observed in SCNT-derived bovine embryos and chorioallantoic membranes, respectively, supporting the hypothesis that abnormalities in the expression of imprinted genes are causes of the low efficiency of SCNT procedures in this species.

Structural and optical analysis of GaAsP/GaP core-shell nanowires

The structural and optical properties of GaAsP/GaP core-shell nanowires grown by gas source molecular beam epitaxy were investigated by transmission electron microscopy, Raman spectroscopy, photoluminescence (PL), and magneto-PL. The effects of surface depletion and compositional variations in the ternary alloy manifested as a redshift in GaAsP PL upon surface passivation, and a decrease in redshift in PL in the presence of a magnetic field due to spatial confinement of carriers.