Microstructure and crystallographic properties of Cu77Zn21 alloy under the effect of heat treatment

The influence of heat treatment process on microstructure and physiochemical properties of Cu₇₇Zn₂₁ alloy was studied. Samples were heated from 300 to 700°C for 15 minutes and gradually cooled to room temperature. Samples were characterized using mechanical testing and surface analysis techniques. It was observed that the grain size increases with the increasing temperature. The decrease in hardness is due to composition change of the Cu-Zn alloy attributed to zinc diffusion.XRD shows the presence of only α brass with a preferential orientation along the (111) plane. The analyses show that temperature affects the crystalline parameters. The rms microstrain was reduced mainly by thermal activation. The heat treatment promotes atomic diffusion and leads to a better crystallinity of the particles. The results of Raman investigations confirmed the changes in the Cu-Zn alloy surface composition with a clear enrichment in CuO. This behavior correlates with the results obtained by mechanical testing.     

A 1-V RF-CMOS LNA design utilizing the technique of capacitive feedback matching network

In this paper, a CMOS low-noise amplifier (LNA) with a new input matching topology has been proposed, analyzed and measured. The input matching network is designed through the technique of capacitive feedback matching network. The proposed LNA which is implemented in a technology is operated at the frequency of 12.8 GHz. It has a gain S21 of 13.2 dB, a noise figure (NF) of 4.57 dB and an NF_min of 4.46 dB. The reverse isolation S12 of the LNA can achieve and the input and output return losses are better than . The input 1-dB compression point is and IIP3 is . This LNA drains 10 mA from the supply voltage of 1 V.     

Condition assessment of concrete in hydraulic structures by surface wave non-destructive testing

Maintenance and rehabilitation of concrete structures affected by alkali-aggregate reaction (AAR) require conducting detailed assessment of the concrete conditions, mainly close to the surface where the damage is more severe. This paper presents in situ investigations by surface wave testing of near-surface AAR damage in two hydraulic structures. The survey was carried out using a non-intrusive multi-sensor method that involves frequency–wavenumber analysis of surface waves. The method allows solving Rayleigh surface wave propagation modes required for the determination of the shear wave velocity in terms of depth. The variation of Young’s modulus with concrete depth can be estimated from the obtained shear wave velocity profile. Two different cases of surface wave propagation, typical of concrete structures, are discussed in this paper. The tests were conducted from the concrete surface only and the subsurface quality was mapped up to a depth of 1.50 m. The applications show that the proposed surface wave method is a potential non-destructive evaluation method that can be used to detect and locate near surface damage in concrete structures.

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Fine and Ultrafine Particle Characterization and Modeling in High-Speed Milling of 6061-T6 Aluminum Alloy

In this study, an experimental investigation was carried out on fine and ultrafine metallic dust emission during high-speed milling of 6061-T6 aluminum alloy in wet and dry conditions. Measurements of dust emission were conducted using a scanning mobility particle sizer spectrometer and an aerodynamic particle sizer spectrometer. These instruments were used to characterize particles in the micrometer and the nanometer size ranges. It was confirmed that the machining process produces nanoparticles as small as 10 nm and that the characteristics of the generated nanoparticles are not significantly influenced by the cutting conditions. The cutting forces and chip compression ratio were measured to validate the proposed dust generation model based on an energy approach. Good agreement was observed between the model and the experimental measurements for the investigated conditions. It was demonstrated that the majority of generated dust is caused by deformations in the primary shear zone. In addition, the percentage of generated dust is significantly influenced by deformation conditions in the chip formation zone. It was found that high cutting speeds could reduce the percentage of the generated particles during the milling process.     

Development of a total quality scoring system based on consumer preference weightings and sensory profiles: application to fruit dates (Tamr)

A scoring system for evaluating the total quality of a food product (Tamr) based on consumer preferences was developed and tested for validity. The development process started with a survey among adult date consumers in the United Arab Emirates to identify their perception of characterizing total quality of date fruit among specified attributes. The consumer subjective ranking of eleven specified attributes was used to derive a quantitative weighted factor for each attribute. Based on the weighted factor a quantitative scoring guide was developed. A panel evaluation of five date varieties (Khlas, Barhee, Boumaan, Fard and Ruzeiz) was conducted as an application of the developed scoring system. Panel evaluation results and consumer ranking and preference data of the same varieties compared well. In both panel evaluation and consumer ranking, Khlas variety was perceived to have the best quality by far among the tested varieties. Barhee and Boumaan varieties showed no significant variation between them in both panel evaluation and consumer ranking, and both were in the second order of preference. Variety Ruzeiz was in the lowest order of preference in both panel evaluation and consumer ranking. Testing of the method indicated its appropriateness in predicting total quality of a food product as would be perceived by consumers.     

Cavitation corrosion of nodular cast iron (NCI) in seawater: Microstructural effects

An investigation was carried out to determine the effect of the microstructure of nodular cast iron (NCI) on its cavitation corrosion behavior in natural seawater. The cavitation tests were conducted using a cavitation-induced facility at a frequency of 20 kHz on detached specimens. Morphological examinations on cavitated specimens indicated that the surface of NCI became very rough with large size cavity pits. Examination by optical microscopy of cross-sectioned specimens revealed the presence of microcracks in the bottom of cavity pits. Localized material removal on the NCI surface was due to ductile tearing and brittle modes of failure.     

The TRPC1 Channel Forms a PI3K/CaM Complex and Regulates Pancreatic Ductal Adenocarcinoma Cell Proliferation in a Ca2+-Independent Manner

Dysregulation of the transient receptor canonical ion channel (TRPC1) has been found in several cancer types, yet the underlying molecular mechanisms through which TRPC1 impacts pancreatic ductal adenocarcinoma (PDAC) cell proliferation are incompletely understood. Here, we found that TRPC1 is upregulated in human PDAC tissue compared to adjacent pancreatic tissue and this higher expression correlates with low overall survival. TRPC1 is, as well, upregulated in the aggressive PDAC cell line PANC-1, compared to a duct-like cell line, and its knockdown (KD) reduced cell proliferation along with PANC-1 3D spheroid growth by arresting cells in the G1/S phase whilst decreasing cyclin A, CDK2, CDK6, and increasing p21^CIP1 expression. In addition, the KD of TRPC1 neither affected Ca²⁺ influx nor store-operated Ca²⁺ entry (SOCE) and reduced cell proliferation independently of extracellular calcium. Interestingly, TRPC1 interacted with the PI3K-p85α subunit and calmodulin (CaM); both the CaM protein level and AKT phosphorylation were reduced upon TRPC1 KD. In conclusion, our results show that TRPC1 regulates PDAC cell proliferation and cell cycle progression by interacting with PI3K-p85α and CaM through a Ca²⁺-independent pathway.     

Monitoring surface water content using visible and short-wave infrared SPOT-5 data of wheat plots in irrigated semi-arid regions

Irrigated agriculture is an important strategic sector in arid and semi-arid regions. Given the large spatial coverage of irrigated areas, operational tools based on satellite remote sensing can contribute to their optimal management. The aim of this study was to evaluate the potential of two spectral indices, calculated from SPOT-5 high-resolution visible (HRV) data, to retrieve the surface water content values (from bare soil to completely covered soil) over wheat fields and detect irrigation supplies in an irrigated area. These indices are the normalized difference water index (NDWI) and the moisture stress index (MSI), covering the main growth stages of wheat. These indices were compared to corresponding in situ measurements of soil moisture and vegetation water content in 30 wheat fields in an irrigated area of Morocco, during the 2012–2013 and 2013–2014 cropping seasons. NDWI and MSI were highly correlated with in situ measurements at both the beginning of the growing season (sowing) and at full vegetation cover (grain filling). From sowing to grain filling, the best correlation (R² = 0.86; p < 0.01) was found for the relationship between NDWI values and observed soil moisture values. These results were validated using a k-fold cross-validation methodology; they indicated that NDWI can be used to estimate and map surface water content changes at the main crop growth stages (from sowing to grain filling). NDWI is an operative index for monitoring irrigation, such as detecting irrigation supplies and mitigating wheat water stress at field and regional levels in semi-arid areas.     

SOOT FORMATION IN GAS TURBINE COMBUSTORS

ABSTRACT

Soot formation in the gas turbine combustors has serious effects on liner durability, carbon deposition and smoke emission.

In this work an analytical study is made to derive quantitative relationships for calculating temperature, unburned hydrocarbon and oxygen concentration from previous detailed experimental data. The quantities of the derived parameters are used in a soot formation model to predict soot concentration along the primary zone.

The soot concentration predicted compares favourably with experiment especially at full load conditions. This supports the capability of the model with the derived quantitative relationships in predicting soot concentration for different gas turbine combustors.