An Intact Kidney Slice Model to Investigate Vasa Recta Properties and Function in situ

Background: Medullary blood flow is via vasa recta capillaries, which possess contractile pericytes. In vitro studies using isolated descending vasa recta show that pericytes can constrict/dilate descending vasa recta when vasoactive substances are present. We describe a live kidney slice model in which pericyte-mediated vasa recta constriction/dilation can be visualized in situ. Methods: Confocal microscopy was used to image calcein, propidium iodide and Hoechst labelling in ‘live’ kidney slices, to determine tubular and vascular cell viability and morphology. DIC video-imaging of live kidney slices was employed to investigate pericyte-mediated real-time changes in vasa recta diameter. Results: Pericytes were identified on vasa recta and their morphology and density were characterized in the medulla. Pericyte-mediated changes in vasa recta diameter (10–30%) were evoked in response to bath application of vasoactive agents (norepinephrine, endothelin-1, angiotensin-II and prostaglandin E2) or by manipulating endogenous vasoactive signalling pathways (using tyramine, L-NAME, a cyclo-oxygenase (COX-1) inhibitor indomethacin, and ATP release). Conclusions: The live kidney slice model is a valid complementary technique for investigating vasa recta function in situ and the role of pericytes as regulators of vasa recta diameter. This technique may also be useful in exploring the role of tubulovascular crosstalk in regulation of medullary blood flow

Microstructural evolution of 3YSZ flash sintered with current ramp control

Ceramics sintered by Flash Sintering (FS), sometimes have heterogeneity in their microstructure. Among the possible causes of this problem, the formation of hotspots is probably the principal issue observed in flash sintering. The hotspots are formed due to the heterogeneity of the resistance of current passing in the green sample. In this way, in the flash phenomenon, the current finds preferential paths, carrying on non-uniform thermal runaway. In this work, we observed that one way of reversing this problem was gradually increasing the electric current density at FS. For this, 3YSZ was shaped in cylindrical form (5 mm height and 6 mm diameter) and flash sintered, at a tubular setup proposed before1, under the application of an AC electric field of 120 V/cm (RMS basis) applied from the beginning of the furnace heating. Three different electric current density ramps were studied: 0.012, 0.024 and 0.048 A.s-1, named as Z1, Z2 and Z3 respectively, until they reached the maximum value of 100 mA.mm-2 (the moment the power supply was turned off). For comparison purposes, conventional FS (Z0) was performed using the same electrical parameters. The electric source, in this case, remained on after reaching 100 mA.mm-2 for 142 s (time calculated to reach the same total energy supplied by the electrical source of samples Z1). After sintering, the apparent densities of the samples were measured according to the Archimedes principle. For analysis of the microstructure, the samples were cut radially and three regions of each sample were observed in SEM: center, right and left surfaces. The grain size distribution was made for each region using ImageJ software. The apparent density of samples sintered by FS was 94 % (Z0) and samples with electrical current ramp were 93 %, 92 % and 87 % for Z1, Z2 and Z3, respectively. The apparent density is proportional to the total energy supplied to the sample (energy provided by the power supply and thermal energy provided by the furnace). Thus, the density of Z0 was expected to be close to the density of Z1. As samples Z2 and Z3 had more abrupt ramps, the energy supplied was lower, which resulted in lower apparent density. The grain size distribution indicates that the mean grain size between the three different regions did not present statistically significant differences (ANOVA test) for the same sample. Please click Additional Files below to see the full abstract

Authentication and discrimination of new Brazilian Canephora coffees with geographical indication using a miniaturized near-infrared spectrometer.

New Brazilian Canephora coffees (Conilon and Robusta) of high added value from specific origins have been protected by geographical indication to guarantee their origin and quality. Recently, benchtop near-infrared (NIR) spectroscopy combined with chemometrics has demonstrated its usefulness to discriminate them. It was the first study, however, and therefore the possibility exists to develop a new portable NIR method for this purpose. This work assessed a miniaturized NIR as a cheaper spectrometer to discriminate and authenticate new Brazilian Canephora coffees with certified geographical origins and to differentiate them from specialty Arabica. Discriminant chemometric and class modeling techniques have been applied and have obtained good predictive ability on external test sets. In addition, models with similar classification purpose were compared with those obtained in previous research carried out with benchtop NIR for the same samples, obtaining comparable results. In this context, the portable method was used as a laboratory technique and has the advantage of being cheaper than benchtop NIR spectrometer. Furthermore, it brings a high possibility to be implemented in small coffee cooperatives, industries or control agencies in the future that do not have high economic resources

Time-domain nuclear magnetic resonance (TD-NMR) and chemometrics for determination of fat content in commercial products of milk powder.

Made available in DSpace on 2017-11-09T23:16:05Z (GMT). No. of bitstreams: 1 PROCITimedomainnuclear....pdf: 1135929 bytes, checksum: 473b2dd2b69ad9452455ae6850aa087f (MD5) Previous issue date: 2017-11-09bitstream/item/166525/1/PROCI-Time-domain-nuclear....pd

Phase evolution during Conventional and Flash Sintering of hydroxyapatite-zirconia composite using in-situ synchrotron x-ray diffraction

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Brazilian Canephora coffee evaluation using NIR spectroscopy and discriminant chemometric techniques.

High-quality Brazilian Canephora coffees are rising to the level of specialty coffees in the face of a new industry perception. In this framework, spectra from 527 coffees were analyzed in the near-infrared (NIR) region. Prin- cipal component analysis distinguished Brazilian Canephora producing states, botanical varieties, low and high- quality Canephora, Canephora and Arabica, and Canephora with geographical indication (GI) from those without GI. Also, Canephora coffee cultivars from Western Brazilian Amazon were distinguished. Three multi-class PLS- DA (traditional, hard, and soft versions) were compared to discriminate 5 classes: Robusta Amaz?onico from traditional (1) and indigenous (2) producers of Rond?onia, Conilon from Espírito Santo (3), Conilon from Bahia (4), and specialty Arabica (5). Binary PLS-DA discriminated GI Canephora and non-GI Canephora with 100% sensitivity and specificity. Carbohydrates, chlorogenic acids, lipids, caffeine, and proteins were dominant ab- sorption bands in coffee classifications. The proposed method is objective, simple, fast, and could be used in the routine analysis of coffee to verify claims of identity, variety, and origin

H NMR, FAAS, portable NIR, benchtop NIR, and ATR-FTIR-MIR spectroscopies for characterizing and discriminating new Brazilian Canephora coffees in a multi-block analysis perspective.

Different analytical techniques, mixing single and multi-block chemometric analyses in supervised and unsu- pervised approaches, and the selection of variables in the coffee discrimination domain have been reported. Molecular and atomic spectroscopic techniques (1H NMR, portable NIR, benchtop NIR, ATR-FTIR-MIR, and FAAS) were used to characterize and discriminate Brazilian Canephora coffees of specific producers, including two with geographical indication, and also to differentiate them from the Arabica. The sample set comprised 100 Canephora samples of different geographical origins in Brazil (Conilon from Espírito Santo, Amazonian Robusta from indigenous and non-indigenous producers of Rondonia, and Conilon from Bahia) and Arabica coffee (25 samples). ComDim exploratory multi-block analysis was first used to evaluate the contributions of all the different data blocks that characterized the samples and determine the calibration and validation sets. Multi- block discrimination by the SO-PLS-LDA was then used to validate the feasibility of discrimination, and to identify the relevant analytical techniques. The discrimination based on all the blocks presented 100% correct discrimination on training, cross-validation, and test sets, and suggested that only a single block (benchtop NIR) is needed to achieve a perfect discrimination. PLS-DA was then applied to the data from portable NIR to evaluate whether comparable performances could be achieved; all test samples were correctly discriminated with the exception of two Robusta Amazonico from non-indigenous producers and two Conilon from Espírito Santo, indicating that very accurate results can be obtained also using a portable instrument. Finally, the use of CovSel- DA allowed the discrimination to be optimized on the most cost-effective analytical technique (portable NIR). CovSel-LDA models selected the best variables for benchtop and portable NIR, impacting positively portable NIR performance and suggesting that portable NIR could bring comparable or at least only slightly worse perfor- mance than benchtop NIR for discrimination

Monitoramento de estiagem durante o verão de regiões tropicais utilizando imagens AVHRR/NOAA-14.

No presente trabalho, objetivou-se estudar a influência da precipitação na evolução dos índices de vegetação Ratio e NDVI, visando determinar o parâmetro mais adequado para ser utilizado no monitoramento de estiagem

Impact of ZrO2 Content on the Formation of Sr-Enriched Phosphates in Al2O3/ZrO2 Nanocomposites for Bone Tissue Engineering.

Abstract: This study investigates the profound impact of the ZrO2 inclusion volume on the characteristics of Al2O3/ZrO2 nanocomposites, particularly influencing the formation of calcium phosphates on the surface. This research, aimed at advancing tissue engineering, prepared nanocomposites with 5, 10, and 15 vol% ZrO2 , subjecting them to chemical surface treatment for enhanced calcium phosphate deposition sites. Biomimetic coating with Sr-enriched simulated body fluid (SBF) further enhanced the bioactivity of nanocomposites. While the ZrO2 concentration heightened the oxygen availability on nanocomposite surfaces, the quantity of Sr-containing phosphate was comparatively less influenced than the formation of calcium phosphate phases. Notably, the coated nanocomposites exhibited a high cell viability and no toxicity, signifying their potential in bone tissue engineering. Overall, these findings contribute to the development of regenerative biomaterials, holding promise for enhancing bone regeneration therapies