PD-1 is an immunoinhibitory receptor expressed by activated T cells, B cells, and myeloid cells. Mice deficient in PD-1 exhibit a breakdown of peripheral tolerance and demonstrate multiple autoimmune ...features. We report here that the ligand of PD-1 (PD-L1) is a member of the B7 gene family. Engagement of PD-1 by PD-L1 leads to the inhibition of T cell receptor-mediated lymphocyte proliferation and cytokine secretion. In addition, PD-1 signaling can inhibit at least suboptimal levels of CD28-mediated costimulation. PD-L1 is expressed by antigen-presenting cells, including human peripheral blood monocytes stimulated with interferon gamma, and activated human and murine dendritic cells. In addition, PD-L1 is expressed in nonlymphoid tissues such as heart and lung. The relative levels of inhibitory PD-L1 and costimulatory B7-1/B7-2 signals on antigen-presenting cells may determine the extent of T cell activation and consequently the threshold between tolerance and autoimmunity. PD-L1 expression on nonlymphoid tissues and its potential interaction with PD-1 may subsequently determine the extent of immune responses at sites of inflammation.
► The hot deformation behaviour of the Al 2024 alloy was analyzed by torsion testing, constitutive equations and processing maps. ► EBSD was employed to characterize the microstructure and its ...correlation with processing maps. ► A forming temperature range of 360–410°C and strain rates of 2.1–4.5s−1 is recommended. ► Extended dynamic recovery (DRV) under the most favourable conditions leads to uniform and fine grain size. ► The behaviour of precipitates at processing temperature determines the mechanical properties.
The forming behaviour of an Al–Cu–Mg alloy (Al 2024-T351) has been studied by processing maps and microstructural characterization. Torsion tests were conducted in the range 278–467°C, between 2.1 and 25.6s−1. Stress–strain curves obtained from the experiment data were fitted using the Garofalo equation to obtain the constitutive parameters, obtaining a stress exponent of 6.1 and an activation energy of 180kJ/mol. Electron backscatter diffraction (EBSD) was employed to characterize the microtexture and microstructure, before and after torsion testing, to evaluate the microstructural changes and instability phenomena. A peak ductility of the Al 2024 alloy was found at about 400°C at all strain rates considered. According to the processing maps and microstructure observation, the optimum hot deformation condition for the Al 2024 alloy is in the range 360–410°C and 2.1–4.5s−1. Under these favourable conditions a uniform and fine grain size is obtained by extended dynamic recovery (DRV), which leads to the formation of subgrain boundaries that progressively transform at large strains into new high angle grain boundaries.
• The microstructure and the yield stress obtained after ECAP processing is determined mainly by the processing severity. • The processing severity has been estimated by the maximum load recorded ...during the ECAP processing. • Increase from 3 to 8 ECAP passes at 130
°C produces a marked improvement in yield stress without significant loss of elongation. • Processing at low temperature limits dislocation recovery during processing, decreasing the elongation at fracture.
Tensile tests were conducted to evaluate the influence of equal-channel angular pressing (ECAP) on the mechanical properties at room temperature of overaged Al 7075-O alloy. ECAP processing was performed using route B
C at different temperatures and number of passes, i.e. different processing severity conditions. The maximum load (
F
max) recorded during the last pass of each ECAP path considered in this study is a very good estimation of the processing severity. The mechanical properties were studied in terms of the balance between tensile strength and ductility. In the processed Al 7075-O alloy, the grain size was reduced down to ∼150
nm. Consequently, tensile testing at room temperature revealed a significant increase in the maximum tensile strength after ECAP with respect to the as start material. In the present study, as the processing severity increases with the number of ECAP passes or with the decrease in processing temperature, there is a consistent trend of increment in ultimate tensile strength with minor decrease in uniform plastic elongation respect to the first ECAP pass at room temperature. This is in contrast to the behaviour after more severe plastic deformation conditions, where an increase in strength together with a strong decrease in elongation would be expected.
•A novel multi-sensor infrared non-dispersive was developed.•The new multi-sensor NDIR was probed to measure carbon dioxide (CO2) and methane (CH4) from river sediments in situ.•A gas extraction ...chamber was designed and built based on the biogas yield under the extraction by ultrasound.•The specific methanogenic activity was measured to evaluate the biogas yield.
A novel multi-sensor infrared non-dispersive was developed and used to measure carbon dioxide (CO2) and methane (CH4) from river sediments. The infrared filters were developed considering the bandwidth (BW) and central wavelength (CWL) of the infrared spectra of gases. Experiments were performed using sediments from the Lerma River taken during the rainy and dry seasons in order to determine the dimensions of sensor and the gas concentration detection limits (SPAN). The sensor and the extraction chamber dimensions were determined based on the biogas yield under the extraction by ultrasound and specific methanogenic activity (SMA), while SPAN values were established from the results of gas concentration measured by gas chromatography. The volume of sensor was 2.23 mL and selected SPAN values were fixed to 20% for CH4 and CO2 from the calibration and the gas obtained from sediments.
In this work, a comparative study evaluating the influence of different functionalization of carbon nanotubes on the properties of nanocomposites with polymeric matrix was performed. A 50/50 wt% ...polycarbonate (PC)/poly(acrylonitrile‐butadiene‐styrene) (ABS) blend was used as polymeric matrix of the nanocomposites. The comparison was made between nanocomposites reinforced with covalently functionalized multiwall carbon nanotubes (MWCNTf) and MWCNTf/nanoclay hybrid functionalization. The effect on the mechanical and morphological properties of the nanocomposites was evaluated through tensile and Izod impact tests and scanning electron microscopy and transmission electron microscopy (TEM) analyses. The thermal characterization of PC/ABS blends and nanocomposites was performed by differential scanning calorimetry (DSC). Results showed that both methods of functionalization of MWCNTs increased the stiffness and impact resistance of the nanocomposites. TEM micrographs indicated the preferred location of the reinforcements in the SAN phase of ABS. Results from DSC indicated an increase in the thermal resistance of the nanocomposites.
The purpose of this work was to develop nanocomposites materials consisting of PC/ABS matrix using functionalized multi‐walled carbon nanotubes (MWCNTf) as filler. The carbon nanotubes were modified by covalent and non‐covalent functionalization and then incorporated into the matrix. Results showed that both methods of functionalization of MWCNTs significantly improved the stiffness and impact resistance of the nanocomposites.
In this research, the kinetics and thermodynamics of corncob hydrolysis in dilute phosphoric acid, obtained at different acid concentrations, temperatures, and reaction times are reported for the ...first time. The sugars were obtained mainly from hemicellulose and cellulose degradation: trehalose, arabinose, glucose, and fructose were produced under minimal hydrolysis conditions and xylose under the most severe hydrolysis conditions. The highest sugar yield was 54 g of sugar per 100 g of corncob under most severe conditions with a degradation factor of only 0.03 to furfurals. The hydrolysates can be used without any treatment for biogas production by dark fermentation. Kinetic constants calculated from the Saeman and first-order models allowed us to determine the thermodynamic parameters and understand the energetic changes during hydrolysis. The activation energy for sugar production was 52 kJ mol−1, and the activation energies were 78 kJ mol−1 and 115 kJ mol−1 for sugar decomposition into furfural and 5-HMF, respectively.
•Hydrolysis of corncob with H3PO4 achieved a high sugar yield.•From aldehyde concentration, hydrolysates can be employed for biofuel production.•Rates and thermodynamic parameters depend on acid concentration and temperature.•Thermodynamic parameters for phosphoric acid hydrolysis of corncob are reported.•Sugars were stable products and their production was the most favourable reaction.
▶ The objective of this work was to characterize the microstructural refinement and strengthening of an Al–7
wt% Si processed by HPT, considering the influence of the initial Si concentration in ...supersaturated solid solution. ▶ Severe deformation produced precipitation of fine particles of silicon, which were very useful in retaining fine microstructures (∼200 nm in grain size) during HPT processing. ▶ The refining and strengthening of the Al matrix depend on the available supersaturated solid solution during the HPT processing.
A hypoeutectic Al–7
wt% Si alloy was subjected to high-pressure torsion (HPT) at room temperature using an imposed pressure of 6
GPa and torsional straining through five revolutions. Different thermal treatments, prior to the HPT processing, resulted in reducing supersaturated Si concentration in comparison to the as-cast material. Microstructural parameters and microhardness were evaluated in the present work. Processing by HPT produced significant grain refinement with grain sizes of about 200–400
nm. Furthermore, fine deformation-induced Si precipitates from the supersaturated solid solution were observed, which are very useful in retaining the fine microstructure during HPT processing. The microhardness increase was outstanding, with values for processed samples twice higher (84
HV) than that for the as-cast Al–7
wt% Si alloy (44
HV). The results demonstrate that the refining and strengthening of the Al matrix by HPT processing depend on the available supersaturated solid solution during the processing.
The inactivation kinetics of Lactobacillus plantarum in a mandarin juice treated by thermal treatment (45-90 °C), high-pressure homogenisation (HPH) (30-120 MPa at 15 and 30 °C) and high-pressure ...processing (HPP) (150-450 MPa at 15, 30 and 45 °C) were fitted to different Weibullian equations. A synergic effect between pressure and temperature was observed in HPH and HPP treatments achieving 2.38 log cycles after 120 MPa at 30 °C for 10 s (final T of 45 °C) and 6.12 log cycles after 400 MPa at 45 °C for 1 min (final T of 60 °C), respectively. A combined treatment of 100 MPa at 15 °C for 10 s and 300 MPa at 15-30 °C for 1 min in HPH and HPP, respectively, was needed to the first logarithm microbial population decline. Weibull model accurately predicted microorganism inactivation kinetics after HPH and HPP processing when displaying single shoulder or tail in the survivor curves, whereas when a more complex trend was observed after thermal treatment, the double-Weibull equation was found more appropriate to explain such behaviour. Equivalent treatments that achieved the same degree of microbial inactivation (77 °C-10 s in thermal processing, 120 MPa-10 s at 30 °C in HPH processing and 375 MPa-1 min at 30 °C in HPP) were selected to study the effects on quality parameters. The application of dynamic pressure led to a decrease in sedimentable pulp, transmittance and juice redness, thus stabilising the opaqueness and cloudiness of mandarin juice. Pectin methyl esterase (PME) was found to be highly baroresistant to static and dynamic pressure. Carotenoid content remained unaffected by any treatment. This study shows the potential of high-pressure homogenisation as an alternative for fruit-juice pasteurisation.
Examples where the enantiomerically pure sulfinyl group has been used successfully to control the sterochemistry of the product in the key step of the total synthesis of biologically active compounds ...are presented.
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