Micromachined Electric Field Mill Employing a Vertical Moving Shutter

AbstractThis paper presents a new type of micromachined electric field mill (MEFM) for measuring dc electric fields. This MEFM employs thermal actuators for vertical movement of an electrically grounded shutter, to mill the amplitude of a dc electric field incident on underlying sense electrodes. It addresses the main drawbacks of existing MEFMs, which are shutter displacement in large electric field, and drive signal interference from the shutter actuator. Simulation results show that for a 1kV/m dc field the output of the sensor is about 1pA

Alternating current conduction properties of thermally evaporated alpha-nickel phthalocyanine thin films: Effects of oxygen doping and thermal annealing

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Thermodynamic properties of Pt nanoparticles: Size, shape, support, and adsorbate effects

This study presents a systematic investigation of the thermodynamic properties of free and γ-Al2O3-supported size-controlled Pt nanoparticles (NPs) and their evolution with decreasing NP size. A combination of in situ extended x-ray absorption fine-structure spectroscopy (EXAFS), ex situ transmission electron microscopy (TEM) measurements, and NP shape modeling revealed (i) a cross over from positive to negative thermal expansion with decreasing particle size, (ii) size- and shape-dependent changes in the mean square bond-projected bond-length fluctuations, and (iii) enhanced Debye temperatures (ΘD, relative to bulk Pt) with a bimodal size-dependence for NPs in the size range of ∼0.8–5.4 nm. For large NP sizes (diameter d >1.5 nm) ΘD was found to decrease toward ΘD of bulk Pt with increasing NP size. For NPs ≤ 1 nm, a monotonic decrease of ΘD was observed with decreasing NP size and increasing number of low-coordinated surface atoms. Our density functional theory calculations confirm the size- and shape-dependence of the vibrational properties of our smallest NPs and show how their behavior may be tuned by H desorption from the NPs. The experimental results can be partly attributed to thermally induced changes in the coverage of the adsorbate (H2) used during the EXAFS measurements, bearing in mind that the interaction of the Pt NPs with the stiff, high-melting temperature γ-Al2O3 support may also play a role. The calculations also provide good qualitative agreement with the trends in the mean square bond-projected bond-length fluctuations measured via EXAFS. Furthermore, they revealed that part of the ΘD enhancement observed experimentally for the smallest NPs (d ≤ 1 nm) might be assigned to the specific sensitivity of EXAFS, which is intrinsically limited to bond-projected bond-length fluctuations

Thermodynamic properties of Pt nanoparticles: Size, shape, support, and adsorbate effects

This study presents a systematic investigation of the thermodynamic properties of free and gamma-Al2O3-supported size-controlled Pt nanoparticles (NPs) and their evolution with decreasing NP size. A combination of in situ extended x-ray absorption fine-structure spectroscopy (EXAFS), ex situ transmission electron microscopy (TEM) measurements, and NP shape modeling revealed (i) a cross over from positive to negative thermal expansion with decreasing particle size, (ii) size- and shape-dependent changes in the mean square bond-projected bond-length fluctuations, and (iii) enhanced Debye temperatures (D-circle minus, relative to bulk Pt) with a bimodal size- dependence for NPs in the size range of similar to 0.8-5.4 nm. For large NP sizes (diameter d \u3e 1.5 nm) D-circle minus was found to decrease toward D-circle minus of bulk Pt with increasing NP size. For NPs \u3c = 1 nm, a monotonic decrease of D-circle minus was observed with decreasing NP size and increasing number of low-coordinated surface atoms. Our density functional theory calculations confirm the size- and shape-dependence of the vibrational properties of our smallest NPs and show how their behavior may be tuned by H desorption from the NPs. The experimental results can be partly attributed to thermally induced changes in the coverage of the adsorbate (H-2) used during the EXAFS measurements, bearing in mind that the interaction of the Pt NPs with the stiff, high-melting temperature gamma-Al2O3 support may also play a role. The calculations also provide good qualitative agreement with the trends in the mean square bond-projected bond-length fluctuations measured via EXAFS. Furthermore, they revealed that part of the D-circle minus enhancement observed experimentally for the smallest NPs (d \u3c = 1 nm) might be assigned to the specific sensitivity of EXAFS, which is intrinsically limited to bond-projected bond-length fluctuations

Epigenetic associations of type 2 diabetes and BMI in an Arab population

Background The prevalence of type 2 diabetes (T2D) and obesity has dramatically increased within a few generations, reaching epidemic levels. In addition to genetic risk factors, epigenetic mechanisms triggered by changing environment are investigated for their role in the pathogenesis of these complex diseases. Epigenome-wide association studies (EWASs) have revealed significant associations of T2D, obesity, and BMI with DNA methylation. However, populations from the Middle East, where T2D and obesity rates are highest worldwide, have not been investigated so far. Methods We performed the first EWAS in an Arab population with T2D and BMI and attempted to replicate 47 EWAS associations previously reported in Caucasians. We used the Illumina Infinium HumanMethylation450 BeadChip to quantify DNA methylation in whole blood DNA from 123 subjects of 15 multigenerational families from Qatar. To investigate the effect of differing genetic background and environment on the epigenetic associations, we further assessed the effect of replicated loci in 810 twins from UK. Results Our EWAS suggested a novel association between T2D and cg06721411 (DQX1; p value = 1.18 × 10−9). We replicated in the Qatari population seven CpG associations with BMI (SOCS3, p value = 3.99 × 10−6; SREBF1, p value = 4.33 × 10−5; SBNO2, p value = 5.87 × 10−5; CPT1A, p value = 7.99 × 10−5; PRR5L, p value = 1.85 × 10−4; cg03078551, intergenic region on chromosome 17; p value = 1.00 × 10−3; LY6G6E, p value = 1.10 × 10−3) and one with T2D (TXNIP, p value = 2.46 × 10−5). All the associations were further confirmed in the UK cohort for both BMI and T2D. Meta-analysis increased the significance of the observed associations and revealed strong heterogeneity of the effect sizes (apart from CPT1A), although associations at these loci showed concordant direction in the two populations. Conclusions Our study replicated eight known CpG associations with T2D or BMI in an Arab population. Heterogeneity of the effects at all loci except CPT1A between the Qatari and UK studies suggests that the underlying mechanisms might depend on genetic background and environmental pressure. Our EWAS results provide a basis for comparison with other ethnicities

Safety climate factors in construction – a literature review

It is an established fact that a mature safety climate and a rich safety culture contribute to achieving a safe workplace. This paper aims to explore and to make explicit the existing safety climate assessment tools and dimensions and suggests the leading factors that can be used for safety climate assessment in construction. The construction industry and the status of occupational safety and health are firstly discussed in a global context. The concept of safety climate is then discussed with a review of different safety climate factors from the published literature. A qualitative research method was employed to explore the existing safety climate factors. A total of 19 safety climate assessment tools with 103 safety climate factors spanning over a period of 39 years (1980–2019) are discussed. The most prevailing safety climate factors including management commitment, training, employees’ involvement, behaviour, communication, accountability and justice, and leadership are discussed in the paper. It is recommended that the factors discussed in this paper may need to be validated first before they are incorporated in the assessment of the safety climate of a specific construction project and organisation in a country or region

Investigations of the electronic conduction mechanisms in evaporated thin films of lead phthalocyanine

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