In this work, we studied the thermal decomposition of a widely employed silicone elastomer, polydimethylsiloxane, in an inert atmosphere. This silicone elastomer has several applications due to its ...high thermal stability such as MEMS (microelectromechanical systems) precursors, microfluidic components, adhesives, lubricants, and precursors for non-porous ceramics. Therefore, a reliable description of the thermal decomposition kinetics is important to prevent or control the decomposition in such applications. While the decomposition has been amply reported as a complex process, most kinetic studies published on this system use simplified methods that avoid the fact that the entire process cannot be described by a single kinetic triplet. Here, we have studied the decomposition process by first separating the overall reaction into its three constituent steps which were subsequently analysed independently. The deconvolution was carried out using Fraser-Suzuki function that is capable of fitting an asymmetric peak fitting function. The resulting kinetic parameters proved to be able to reconstruct the original experimental curves but are also capable of producing accurate predictions of curves recorded at heating schedules different from those employed to record the experimental data used in the kinetic analysis. Finally, it was found that the rate limiting step of all stages is the diffusion of the gases released during the polymer decomposition through the transforming polymeric matrix.
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•The thermal decomposition of polydimethylsiloxane has been studied by thermogravimetric analysis.•This complex process is composed by three overlapping stages.•These stages have been separated by deconvolution procedure using Fraser-Suzuki functions.•Every stage has been studied by combined kinetic analysis. All stages obey diffusion mechanisms.•The calculated triplets kinetic were validated by reconstructions and predictions.
Starch is an essential biopolymer for creating viscous food systems in the food industry. Viscosity behavior is unclear in the literature and varies with the thermal process and moisture content ...used. This study analyzed how ohmic heating affects the pasting properties of corn starch in response to changes in moisture and temperature. Corn starch is mixed with water at varying ratios (1:1, 1:3, and 1:5). The mixture is heated at 5 °C min−1 using an ohmic heating cooker to 80, 100, and 120 °C. Moisture affects pasting and starch properties. Peak viscosity varies with moisture content, decreasing from 5904 cP (native) to 3204–4510 cP at a 1:1 ratio. At a moisture ratio of 1:3, peak viscosity matched the native sample. Higher peak viscosity (6539 to 8772 cP) occurred at high moisture levels (1:3). Thermal properties confirmed different gelatinization degrees, which is evidenced by a shift in the x‐ray diffraction pattern from A‐type (native starch) to V‐type crystalline. The viscosity and physicochemical properties of corn starch depend on temperature and moisture levels. Moisture has a more significant impact on these properties than temperature. Therefore, varying the moisture content it can improve corn starch properties precisely, making it useful for the food industry.
The moisture content (100, 300, and 500%) more than temperature (80, 100, and 120 °C) defined the physicochemical properties of gelatinized corn starch viscosity, thermic, and structural.
Using the Two Micron All Sky Survey Photometric Redshift catalogue we perform a number of statistical tests aimed at detecting possible departures from statistical homogeneity and isotropy in the ...large-scale structure of the Universe. Making use of the angular homogeneity index, an observable proposed in a previous publication, as well as studying the scaling of the angular clustering and number counts with magnitude limit, we place constraints on the fractal nature of the galaxy distribution. We find that the statistical properties of our sample are in excellent agreement with the standard cosmological model, and that it reaches the homogeneous regime significantly faster than a class of fractal models with dimensions D < 2.75. As part of our search for systematic effects, we also study the presence of hemispherical asymmetries in our data, finding no significant deviation beyond those allowed by the concordance model.
Aims
The antimicrobial activity of Acacia farnesiana against Vibrio cholerae has been demonstrated; however, no information regarding its active compound or its mechanism of action has been ...documented.
Methods and Results
The active compound was isolated from A. farnesiana by bioassay‐guided fractionation and identified as methyl gallate by nuclear magnetic resonance (NMR) techniques (1H NMR and 13C NMR). The minimum bactericidal concentration (MBC) of methyl gallate and its effect on membrane integrity, cytoplasmic pH, membrane potential, ATP synthesis and gene expression of cholera toxin (ctx) from V. cholerae were determined. The MBC of methyl gallate ranged from 30 ± 1 to 50 ± 1 μg ml−1. Methyl gallate affected cell membrane integrity, causing a decrease in cytoplasmic pH (pHin, from 7·3 to <3·0), and membrane hyperpolarization, and ATP was no longer produced by the treated cells. However, methyl gallate did not affect ctx gene expression.
Conclusions
Methyl gallate is a major antimicrobial compound from A. farnesiana that disturbs the membrane activity of V. cholerae.
Significance and Impact of the Study
The effects of methyl gallate validate several traditional antimicrobial uses of A. farnesiana, and it is an attractive alternative to control V. cholerae.
Persistent high risk HPV infection can lead to cervical cancer, the second most common malignant tumor in women worldwide. NK cells play a crucial role against tumors and virus-infected cells through ...a fine balance between activating and inhibitory receptors. Expression of triggering receptors NKp30, NKp44, NKp46 and NKG2D on NK cells correlates with cytolytic activity against tumor cells, but these receptors have not been studied in cervical cancer and precursor lesions. The aim of the present work was to study NKp30, NKp46, NKG2D, NKp80 and 2B4 expression in NK cells from patients with cervical cancer and precursor lesions, in the context of HPV infection.
NKp30, NKp46, NKG2D, NKp80 and 2B4 expression was analyzed by flow cytometry on NK cells from 59 patients with cervical cancer and squamous intraepithelial lesions. NK cell cytotoxicity was evaluated in a 4 hour CFSE/7-AAD flow cytometry assay. HPV types were identified by PCR assays.
We report here for the first time that NK cell-activating receptors NKp30 and NKp46 are significantly down-regulated in cervical cancer and high grade squamous intraepithelial lesion (HGSIL) patients. NCRs down-regulation correlated with low cytolytic activity, HPV-16 infection and clinical stage. NKG2D was also down-regulated in cervical cancer patients.
Our results suggest that NKp30, NKp46 and NKG2D down-regulation represent an evasion mechanism associated to low NK cell activity, HPV-16 infection and cervical cancer progression.
Celotno besedilo
Dostopno za:
DOBA, IZUM, KILJ, NUK, PILJ, PNG, SAZU, SIK, UILJ, UKNU, UL, UM, UPUK
The Spanish Familial Pancreatic Cancer Registry (PANGENFAM) was established in 2009 and aims to characterize the genotype and phenotype of familial pancreatic cancer (FPC). Furthermore, an early ...detection screening program for pancreatic ductal adenocarcinoma (PDAC) is provided to healthy high-risk individuals from FPC and hereditary pancreatic cancer families (first-degree relatives). This article describes our experience over the last 10 years in high-risk screening. Hereditary and familial pancreatic cancer families were identified through the oncology and gastroenterology units. High-risk individuals underwent annual screening with endoscopic ultrasound (EUS) and magnetic resonance (MRI) from age 40 or 10 years younger than the youngest affected family member. Results: PANGENFAM has enrolled 290 individuals from 143 families, including 52 PDAC cases and 238 high-risk individuals. All high-risk individuals eligible for screening were offered to enter the surveillance program, with 143 currently participating. Pancreatic abnormalities were detected in 94 individuals (median age 53 years (29–83), with common findings including cystic lesions and inhomogeneous parenchyma. Imaging test concordance was 66%. Surgical intervention was performed in 4 high-risk individuals following highly suspicious lesions detected by imaging. PANGENFAM is a valuable resource for science innovation, such as biobanking, with clinical and imaging data available for analysis. For high-risk families, it may offer a potential for early diagnosis. Collaboration with other national and international registries is needed to increase our understanding of the disease biology and to standardize criteria for inclusion and follow-up, optimizing cost-effectiveness and efficacy.
This work proposed a controlled method to modify the physicochemical properties of corn starch through heating and cooling extrusion (HCE) cycles. It was used native corn starch adjusted to 60% ...moisture. It was then subjected to 5 HCE cycles at 100 and 125 °C, at 10 rpm. Water absorption index (WAI), water solubility index (WSI), resistant starch (RS), thermal properties, viscosity, FTIR, and X-ray were evaluated. For WAI and WSI, a gradual increase was observed on each HCE cycle. Thermal properties shown that enthalpy decrease with each HCE cycles due to more gelatinization. Viscosity properties shown a thermally stable starch conditions being directly proportional to HCE cycles. The RS increased for each 5 HCE. XRD revealed that HCE cycle changed the starch structure from an orthorhombic structure to V-type crystalline structure. Finally, it was concluded that HCE cycles is a method to produce corn starch with controlled physicochemical properties.
•Extrusion heating-cooling cycles (EHCC) change and sharpen the crystalline structure of corn starch.•HCE cycle modifies the resistant starch (RS) percentage.•HCE cycle increases the starch's water absorption and solubility indexes.•HCE cycles decreased the gelatinization enthalpy.•HCE cycles produced a retrograded thermally stable starch.
Seismic vulnerability and loss analyses of buildings are usually estimated under the fixed-based condition, omitting the soil-structure interaction (SSI) effects. However, according to the literature ...and the seismic damage due to past events, mid-to high-rise buildings located on soft soils can present a worse seismic performance. This manuscript aims to investigate whether the SSI effects affect the seismic performance and the losses of reinforced concrete (RC) buildings. To do so, a real 5-storey RC building has been selected as the case study. It was built prior to restrictive Spanish seismic codes. The building was constructed over soft alluvial strata and it has a shallow foundation. The area is characterised by a moderate seismic hazard. Nonlinear static analysis (NLSA) and incremental dynamic analysis (IDA) have been performed to assess the seismic behaviour and the losses expected of the case study building. The calculations have been done in the OpenSees finite-element framework. The direct method has been used to model the SSI. The results have been obtained for the fixed-base and for the SSI models. The numerical outcomes have shown the remarkable effect of the SSI on the fragility and on the performance of these structures. It has been observed that the severe damage expected can be worsened by up to 38% if SSI is taken into account. Additionally, the soft-storey mechanism at the ground floor concentrates all the damage expected, showing that this is the most seismic vulnerable part of the building (owing to higher interstorey-drift ratios and peak floor acceleration values). The losses expected derived for structural and non-structural components have been 140% higher if the SSI is considered.
•NLSA and IDA to assess the seismic performance, fragility curves and losses of RC buildings.•Direct method and distributed plasticity approach to model the SSI and RC nonlinearity.•The severe damage expected can be worsened by up to 38%.•Expected losses can be increased up to 140% if the SSI is considered.•Higher expected losses for non-structural components with regards to the structural ones.
We report an extensive experimental study of a dual-wavelength (1530 and 1560 nm) passively mode-locked fiber laser in a ring configuration with strict control of the polarization state. Different ...types of laser operation are identified, which are classified into ten mode locking regimes (solitons-noise-like pulsing, solitons-solitons, solitons-CW, bound solitons-CW, solitons (1530 nm), CW-solitons, CW-bound solitons, Q-switched-like noise-like pulsing, steady noise-like pulsing at 1530 nm and intermittent mode locking), which are mapped in terms of the polarization settings (ellipticity and azimuth). The resulting map establishes, in a clear and repeatable way, the relation existing between each mode locking regime and the polarization adjustment, which allows controlling at the same time intracavity losses, the gain profile, the cavity spectral transfer function, as well as the nonlinear switching characteristic.
The present paper makes a comparative analysis of the outdoor culture of
H. pluvialis in a tubular photobioreactor and a bubble column. Both reactors had the same volume and were operated in the same ...way, thus allowing the influence of the reactor design to be analyzed. Due to the large changes in cell morphology and biochemical composition of
H. pluvialis during outdoor culture, a new, faster methodology has been developed for their evaluation. Characterisation of the cultures is carried out on a macroscopic scale using a colorimetric method that allows the simultaneous determination of biomass concentration, and the chlorophyll, carotenoid and astaxanthin content of the biomass. On the microscopic scale, a method was developed based on the computer analysis of digital microscopic images. This method allows the quantification of cell population, average cell size and population homogeneity. The accuracy of the methods was verified during the operation of outdoor photobioreactors on a pilot plant scale. Data from the reactors showed tubular reactors to be more suitable for the production of
H. pluvialis biomass and/or astaxanthin, due to their higher light availability. In the tubular photobioreactor biomass concentrations of 7.0
g/L (d.wt.) were reached after 16 days, with an overall biomass productivity of 0.41
g/L
day. In the bubble column photobioreactor, on the other hand, the maximum biomass concentration reached was 1.4
g/L, with an overall biomass productivity of 0.06
g/L
day. The maximum daily biomass productivity, 0.55
g/L
day, was reached in the tubular photobioreactor for an average irradiance inside the culture of 130
μE/m
2s. In addition, the carotenoid content of biomass from tubular photobioreactor increased up to 2.0%
d.wt., whereas that of the biomass from the bubble column remained roughly constant at values of 0.5%
d.wt. It should be noted that in the tubular photobioreactor under conditions of nitrate saturation, there was an accumulation of carotenoids due to the high irradiance in this reactor, their content in the biomass increasing from 0.5 to 1.0%
d.wt. However, carotenoid accumulation mainly took place when nitrate concentration in the medium was below 5.0
mM, conditions which were only observed in the tubular photobioreactor. A similar behaviour was observed for astaxanthin, with maximum values of 1.1 and 0.2%
d.wt. measured in the tubular and bubble column photobioreactors, respectively. From these data astaxanthin productivities of 4.4 and 0.12
mg/L
day were calculated for the tubular and the bubble column photobioreactors. Accumulation of carotenoids was also accompanied by an increase in cell size from 20 to 35
μm, which was only observed in the tubular photobioreactors. Thus it may be concluded that the methodology developed in the present study allows the monitoring of
H. pluvialis cultures characterized by fast variations of cell morphology and biochemical composition, especially in outdoor conditions, and that tubular photobioreactors are preferable to bubble columns for the production of biomass and/or astaxanthin.
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