RF-PACVD of water repellent and protective HMDSO coatings on bell metal surfaces: Correlation between discharge parameters and film properties

Hexamethyldisiloxane (HMDSO) films have been deposited on bell metal using radiofrequency plasma assisted chemical vapor deposition (RF-PACVD) technique. The protective performances of the HMDSO films and their water repellency have been investigated as a function of DC self-bias voltage on the substrates during deposition. Plasma potential measurements during film deposition process are carried out by self-compensated emissive probe. Optical emission spectroscopy (OES) analyses of the plasma during deposition reveal no significant change in the plasma composition within the DC self-bias voltage range of −40 V to −160 V that is used. Raman and X-ray photoelectron spectroscopy (XPS) studies are carried out for film chemistry analysis and indicate that the impinging ion energy on the substrates influences the physio-chemical properties of the HMDSO films. At critical ion energy of 113 qV (corresponding to DC self-bias voltage of −100 V), the deposited HMDSO film exhibits least defective Si-O-Si chemical structure and highest inorganic character and this contributes to its best corrosion resistance behavior. The hardness and elastic modulus of the films are found to be bias dependent and are 1.27 GPa and 5.36 GPa for films deposited at −100 V. The critical load for delamination is also bias dependent and is 11 mN for this film. The water repellency of the HMDSO films is observed to be dependent on the variation in surface roughness. The results of the investigations suggest that HMDSO films deposited by RF-PACVD can be used as protective coatings on bell metal surfaces.     

Local constancy of dimensions of Hecke eigenspaces of automorphic forms

We use a method of Buzzard to study p-adic families of Hilbert modular forms and modular forms over imaginary quadratic fields. In the case of Hilbert modular forms, we get local constancy of dimensions of spaces of fixed slope and varying weight. For imaginary quadratic fields we obtain bounds independent of the weight on the dimensions of such spaces.     

Phase Transfer Catalyzed Peroxidation of Car Boxylic Acids with Potassium Persulfate

Aqueous solution of potassium persulfate converts water-insoluble carboxylic acids in ether (or dichloromethane), to peracids in a yield of 80–90% under the catalytic influence of benzyltriethylammonium chloride (BTEAC) or polyethyleneglycol (PEG-400). The reaction is further catalyzed kinetically in presence of a sulfonated polymer.     

Accelerating molecular dynamic simulation on graphics processing units

We describe a complete implementation of all‐atom protein molecular dynamics running entirely on a graphics processing unit (GPU), including all standard force field terms, integration, constraints, and implicit solvent. We discuss the design of our algorithms and important optimizations needed to fully take advantage of a GPU. We evaluate its performance, and show that it can be more than 700 times faster than a conventional implementation running on a single CPU core. © 2009 Wiley Periodicals, Inc. J Comput Chem, 2009     

On the solutions of the Wick-Cutkosky model in the instantaneous approximation

By reexamining the analysis of Basu and Biswas, based on the stereographic projection method of Fock and Levy, it is shown that the general solution of the Wick-Cutkosky model in the instantaneous approximation, hitherto unreported, involves only one quantum number; this is contrasted with the well-known solution which involves two quantum numbers, but for which the spectrum is degenerate with respect to one of them. The latter situation is shown to hold under a rather special circumstance.     

A study of iso- and alio-valent cation doped Ag2SO4 solid electrolyte

2 SO₄. The solid solubility limits up to x≤3 mole% for monovalent, x≤5.27 mole% for divalent and x≤3.63 mole% for trivalent cation doped Ag₂SO₄ are set with XRD, SEM, IR and DSC techniques. A predominant dependence of conductivity on the ionic size of iso- and alio-valent cations is observed. In particular, the conductivity enhances in both α and β phases, despite having a lower ionic-size dopant cation (relative to that of Ag⁺) in the transition element cation doped Ag₂SO₄. Ca²⁺, Ba²⁺, Y³⁺ and Dy³⁺ doped samples show depature from the regular behaviour in the β-phase. The conductivity behaviour is discussed considering ionic size, valence and electronic structure of the guest cations. Received: 3 February 1997/Accepted: 27 May 1997     

Preliminary design studies of a 100 MeV H−/H+ LINAC as injector for SNS synchrotron/ADS LINAC

It is proposed to construct a spallation neutron source (SNS) at Centre for Advanced Technology (CAT) based on a 1 GeV proton synchrotron with 100 MeV H⁻ LINAC as injector. Additionally, the LINAC can form the first 100 MeV part of a 1 GeV proton LINAC to be built in future for accelerator driven system (ADS) applications. We are exploring a configuration of the 100 MeV LINAC which will consist of an H⁻ ion source, a 4–6 MeV RFQ followed either by a 20 MeV drift tube LINAC (DTL) and 100 MeV separated function drift tube LINAC (SDTL) or a coupled cavity drift tube LINAC (CCDTL) structure. In this paper, we present the results of our preliminary physics design studies of the RFQ-SDTL, RFQ-CCDTL and RFQ-DTL-SDTL configurations. The design of the 4.5 MeV RFQ is discussed along with the matching sections between the RFQ-SDTL/DTL and RFQ-CCDTL. The choice of the accelerator configuration and that of various parameters of the individual accelerator structures under consideration are discussed. The design objectives are to arrive at a configuration which eases heat removal for CW operation and which is less prone to halo formation in order to reduce the beam loss at higher energies.     

Influence of protonation on physico-chemical properties of metal extractants

Summary The protonation constants of several metal extractants, especially hydroxamic acids have been determined by a solvent extraction method. The influence of the acidity on the solubility and the distribution ratio has been studied. A plot correlates the protonation behaviour of these metal extractants with the Hammett Acidity Function, H_o. The protonation constant is useful to explain the acid catalysed hydrolysis rate of these metal extractants and to determine the extraction coefficients of their metal chelates.     

Effects of saturation on optical bistability with coupled surface plasmons

We present exact numerical results for a symmetric layered medium (prism/Ag film/nonlinear dielectric/Ag film/prism) where the middle dielectric slab is assumed to have a saturation-type nonlinearity. We show bistable behaviour in the power dependence of the reflectivity ofp-polarized light under the condition when coupled surface modes are excited in the structure. Moreover, we study the effect of saturation on the bistable behaviour to show that multivalued character is inhibited by saturation effects. The field distributions corresponding to the minimum reflectivity states of the nonlinear structure are also presented.