We report, for the first time, quadrupole mass spectrometry of neutral and positive ionic hydrocarbon species measured at the rf biased substrate electrode of an inductively coupled plasma for ...acetylene rich C2H2:Ar mixtures under various bias, frequency and pressure conditions. It has been observed that, irrespective of initial gas mixture, the resultant plasma is dominated by argon neutrals and ions. This is attributed to highly efficient conversion of acetylene to C2H due to the enhanced electron density compared to a standard capacitive plasma where the acetylene (neutral and ion) species remain dominant. This conversion may be crucial to film formation via inert rather than hydrocarbon ion bombardment. In addition, the transient formation of CH4 from acetylene has been discovered using IR absorption spectroscopy with time constants similar to observed pressure variations. Rate coefficients and rates for many of the reaction mechanisms, calculated using measured EEDFs and species densities, are given. These results have important application in plasma models and growth studies for hydrogenated amorphous or diamond-like carbon film deposition. Film growth under similar plasma conditions is reported in an associated paper along with ion energy distributions for important growth species.
Ion energy distributions have been determined at the rf-bias electrode in an inductively-coupled acetylene-argon plasma for various substrate bias voltages and frequencies under conditions suitable ...for film deposition. These are compared with those obtained at the grounded wall of a capacitively coupled plasma. In the former, for pressures up to 25 mTorr, the IEDs exhibit bimodal structures with peak separation values that follow the expected dependence on voltage and frequency. At higher pressures, 120 mTorr, the bimodal structure is replaced by a single peak. For all conditions, the dominant ion is Ar+ or ArH+ despite a set C2H2:Ar flow ratio of 2:1, and this can be attributed to the high electron dissociation of the parent molecule. Diamond-like carbon films indicate a peak hardness at an ion energy of around 90 eV and a very sharp fall in hardness is noted beyond this value. This is similar to the observed bombardment energy relationship for sp3 bond formation in hydrogen-free tetragonal amorphous carbon or bias-sputtered films. However, due to the lack of carbon-based ions, an alternative film growth mechanism must be considered, possibly based on argon knock-on implantation of surface adsorbed carbon species. The results have shown that the use of high frequency bias or bias harmonics may lead to much narrower ion energy distributions.
Titanium as a micromechanical material O'Mahony, C; Hill, M; Hughes, P J ...
Journal of micromechanics and microengineering,
07/2002, Letnik:
12, Številka:
4
Journal Article, Conference Proceeding
Recenzirano
The suitability of titanium for use in microelectromechanical applications is investigated. A range of titanium microdevices, including free-standing fixed-fixed beams and cantilevers, has been ...successfully fabricated using a fully CMOS compatible, dry-release surface micromachining process. Finite-element simulations have been used to extract a semi-analytical model which describes the pull-in behaviour of fixed-fixed beams, while taking into account the effects of the non-ideal beam anchors. This method has been used to obtain an estimate of the Young's modulus and residual stress in the metal. Capacitance monitoring has shown that the beams remain flat after sacrificial layer release, and interferometry imaging has been used to investigate the stability of beam anchors during device actuation. Furthermore, titanium beams have remained stable under repeated actuation in initial cycle testing and may be suitable for use as a major component of microswitches. One such possible design is outlined.
The 5α‐reduced metabolites of testosterone, including dihydrotestosterone, are considered the primary regulators of epididymal function. Two genes encode two 5α‐reductase isozymes. We examined ...5α‐reductase type 1 and type 2 mRNA tissue distribution and relative abundance in cynomolgus monkey (Macaca fascicularis) testicular and epididymal tissues using semiquantitative reverse transcriptase‐polymerase chain reaction (RT‐PCR). mRNA extracted from monkey tissues including the testis (T) and the proximal caput (PCp), the caput (Cp), the midcorpus (Co), and the distal cauda (Cd) epididymis was reverse transcribed to produce cDNAs. 5α‐reductase type 1 and 2 cDNAs were subsequently coamplified with the housekeeping gene, cyclophilin, in a PCR spiked with MP‐dCTP. Relative abundance was reported as the cpm ratios of type 1 or type 2/cyclophilin mRNA. Semiquantitative RT‐PCR results indicated that type 1 mRNA was most abundant in the testis (0.48 ± 0.06) and significantly decreased distally along the monkey epididymis (PCp: 0.29 ± 0.04; Cp: 0.29 ± 0.04; Co: 0.21 ± 0.03; Cd: 0.07 ± 0.01) (P < 0.001). Type 2 mRNA was undetectable in the testis but was present throughout the epididymis at uniform levels (PCp: 1.6 ± 0.2; Cp: 1.4 ± 0.3; Co: 1.6 ± 0.2; Cd: 1.5 ± 0.2). These data demonstrate that 5α‐reductase type 1 mRNA is differentially expressed but of low abundance along the nonhuman primate epididymis, whereas 5α‐reductase type 2 gene expression is uniform.
We present a joint cosmic shear analysis of the Dark Energy Survey (DES Y3) and the Kilo-Degree Survey (KiDS-1000) in a collaborative effort between the two survey teams. We find consistent ...cosmological parameter constraints between DES Y3 and KiDS-1000 which, when combined in a joint-survey analysis, constrain the parameter \(S_8 = \sigma_8 \sqrt{\Omega_{\rm m}/0.3}\) with a mean value of \(0.790^{+0.018}_{-0.014}\). The mean marginal is lower than the maximum a posteriori estimate, \(S_8=0.801\), owing to skewness in the marginal distribution and projection effects in the multi-dimensional parameter space. Our results are consistent with \(S_8\) constraints from observations of the cosmic microwave background by Planck, with agreement at the \(1.7\sigma\) level. We use a Hybrid analysis pipeline, defined from a mock survey study quantifying the impact of the different analysis choices originally adopted by each survey team. We review intrinsic alignment models, baryon feedback mitigation strategies, priors, samplers and models of the non-linear matter power spectrum.
The 5alpha-reduced metabolites of testosterone, including dihydrotestosterone, are considered the primary regulators of epididymal function. Two genes encode two 5alpha-reductase isozymes. We ...examined 5alpha-reductase type 1 and type 2 mRNA tissue distribution and relative abundance in cynomolgus monkey (Macaca fascicularis) testicular and epididymal tissues using semiquantitative reverse transcriptase-polymerase chain reaction (RT-PCR). mRNA extracted from monkey tissues including the testis (T) and the proximal caput (PCp), the caput (Cp), the midcorpus (Co), and the distal cauda (Cd) epididymis was reverse transcribed to produce cDNAs. 5alpha-reductase type 1 and 2 cDNAs were subsequently coamplified with the housekeeping gene, cyclophilin, in a PCR spiked with 33P-dCTP. Relative abundance was reported as the cpm ratios of type 1 or type 2/cyclophilin mRNA. Semiquantitative RT-PCR results indicated that type 1 mRNA was most abundant in the testis (0.48 +/- 0.06) and significantly decreased distally along the monkey epididymis (PCp: 0.29 +/- 0.04; Cp: 0.29 +/- 0.04; Co: 0.21 +/- 0.03; Cd: 0.07 +/- 0.01) (P < 0.001). Type 2 mRNA was undetectable in the testis but was present throughout the epididymis at uniform levels (PCp: 1.6 +/- 0.2; Cp: 1.4 +/- 0.3; Co: 1.6 +/- 0.2; Cd: 1.5 +/- 0.2). These data demonstrate that 5alpha-reductase type 1 mRNA is differentially expressed but of low abundance along the nonhuman primate epididymis, whereas 5alpha-reductase type 2 gene expression is uniform.
