Correlation between acidic properties of nickel sulfate supported on TiO2-ZrO2 and catalytic activity for ethylene dimerization

A series of catalysts, NiSO₄/TiO₂-ZrO₂, for ethylene dimerization was prepared by the impregnation method using an aqueous solution of nickel sulfate. For NiSO₄/TiO₂ -ZrO₂ sample, no diffraction line of nickel sulfate was observed up to 30 wt%, indicating good dispersion of nickel sulfate on the surface of TiO₂-ZrO₂. The addition of nickel sulfate to TiO₂-ZrO₂ shifted the phase transition of TiZrO₄ from amorphous to orthorhombic to a higher temperature because of the interaction between nickel sulfate and TiO₂-ZrO₂. The number of acid sites of NiSO₄/TiO₂-ZrO₂ increased in proportion to the nickel sulfate content up to 20 wt% of NiSO₄. Nickel sulfate supported on TiO₂-ZrO₂ was found to be very active even at room temperature, giving a maximum in both activity and acidity when the catalyst containing 20% NiSO₄ was calcined and evacuated at 500°C The asymmetric stretching frequency of the S=O bonds for NiSO₄/TiO₂-ZrO₂ samples was related to the acidic properties and catalytic activity. That is, the higher the frequency, the higher both the number of acid sites and the catalytic activity for ethylene dimerization.     

Advanced photospacers with elastic recovery

A new series of photospacers has been prepared with different types of crosslinkers to improve elastic recovery. Afunctional crosslinker with six reactive groups demonstrates the best elastic recovery. As the quantity of crosslinker is increased, the elastic recovery also increases, probably due to an increase in the crosslinking density. The use of ADMS EPS® results in high resolution, good uniformity, and high production yield in the liquid‐crystal‐display (LCD) process. Especially, EPS® improves and solves problems such as viewing angle, crosstalk, and dark spots.     

Enhancing adhesion by ion beam-induced atomic mixing at the interface between copper film and polyimide substrate

Ion beam mixing was used to improve the adhesion between deposited Cu film (400 Å) and polyimide (PI) substrate. Ar⁺ ion with the energy levels between 180 and 200 keV, and the dose between 10¹⁴ to 4 × 10¹⁶ ions/cm² were used. The surface analyses were carried out by Rutherford Backscattering Spectroscopy (SEM). RBS analysis, using 2 MeV He⁺ ions, showed mixing of Cu and FI and the mixing depended on the Ar⁺ energy and dose. The X-ray study showed a very broad halo for deposited Cu film but the (111) peak appeared after the Ar⁺ implantation and the peak increased with Ar⁺ ion dose. Optical micrographs showed that Cu film formed circular bubbles after many thermal cycles when adhesion was poor and fracture cracks when adhesion was good.     

Data quality review program: the Society of Thoracic Surgeons Adult Cardiac National Database

In summary, the National Database Committee's Audit and Validation Subcommittee is working to maximize the data completeness and quality of the STS National Database. Toward this end, we welcome your suggestions for improvement.     

Obstacle Avoidance Path Planning based on Output Constrained Model Predictive Control

International Journal of Control, Automation and Systems - Image processing and control technologies have been widely studied and autonomous vehicles have become an active research area. For...     

Novel synthesis of carboxy-functional soybean acrylic-alkyd resins for water-reducible coatings

A new process was developed for synthesis of alkyd resins in which a conventional monoglyceride is reacted with a carboxy-functional acrylic copolymer. The novel products are called acrylicalkyd resins. The carboxy-functional acrylic copolymers were synthesized by solution-free radical polymerization. Gelation during alkyd resin synthesis was avoided by: (1) limiting the molecular weight of the acrylic copolymers to M_n 3500–5000 and (2) limiting the number average functionality about 6.5–10 carboxyl groups per molecule. Further, the carboxyl groups were derived from a mixture of acrylic and methacrylic acids (1/1.2 mol ratio) in the expectation that this would help control the process. Three series of acrylic copolymers were prepared from various combinations of acrylic monomers and reacted with a monoglyceride prepared from soybean oil and trimethylol propane. The composition of the acrylic resin was adjusted to minimize phase separation [observed visually and by scanning probe microscopy (SPM)] within cast films. The most satisfactory results were obtained with copolymers of 62–71 wt% of methyl methacrylate, 5–21 wt% of lauryl methacrylate, 7.2 wt% of acrylic acid, and 10.3 wt% of methacrylic acid. In preliminary tests, waterborne coatings made from acrylic-alkyd resins based on these acrylics had excellent stability, with acid numbers changing less than 10% after nine months of storage. Coatings Research Institute Ypsilanti MI 48197 Department of Physics, Ypsilanti, MI 48197.     

In vivo accuracy of two radiographic systems in the detection of Bj?rk-Shiley convexo-concave heart valve outlet strut single leg separations

OBJECTIVE: Modified cineradiographic systems have been used clinically to detect partially broken outlet struts in normally functioning Bj?rk-Shiley convexo-concave heart valves. Almost all such valves were explanted, presuming that full failure would likely follow. Inasmuch as the clinical setting only rarely permits examination of normally rated valves, the accuracy of radiographic detection cannot be clinically defined. This study uses the clinical radiographic technique in sheep implanted with known-status convexo-concave valves, comparing its accuracy and that of a newly developed, geometric image magnification radiography system. METHODS: Twenty-one sheep with mitral convexo-concave valves were studied on both systems. Five were used for extensive training. When operators were expert with both systems, images of four intact valves and 12 valves with outlet strut single leg separations, along with a seventeenth single leg separation valve used for calibration, were integrated into 112 image sets organized into a balanced incomplete block design for evaluation by eight trained, blinded reviewers. RESULTS: Cineradiography sensitivity was 24% versus 31% for direct image magnification. The odds ratio for detection of single leg separation by direct image magnification versus cineradiography was 2.0 (95% confidence interval, 0.76 to 5.9; p = 0.13). Cineradiography specificity was 93% versus 90% for direct image magnification. Sensitivity and specificity varied markedly by reviewer, with sensitivity ranging from 8% to 55% and specificity from 51% to 100% for the combined technologies. CONCLUSIONS: The data support the need for more intensive training for convexo-concave valve imaging and further investigation of unconventional radiographic technologies. Clinical cineradiography of convexo-concave valves may detect as little as 25% of valves having a single leg separation, underestimating the prevalence of single leg separations and thereby implying more rapid progression to full fracture than is actually the case.     

Effect of simple stress on the glass transition of polymers at high pressures

Experimental studies, which have been carried out in this laboratory, showed the yield strength in tension, compression, and shear in the rubbery and the glassy states increased with increasing hydrostatic pressure. Moreover, the Young's modulus also increased with pressure and the amount of the increase across the glass transition temperature (T _g) at a given pressure can be as large as three orders of magnitude in the case of elastomers. An extension of the Gibbs-Dimarzio theory is proposed to account for the effect of applied stress on the glass transition temeprature of glass-forming polymers. When a simple stress, such as tensile, compressive or shear stress, is applied to a polymer, the T _g will decrease, compared to a polymer without applied stress. A glass-forming polymer in the vicinity of the transition would behave differently from that predicted by rubber elasticity. The partition function taking into account the effect of stress is suggested to be $$\Gamma = \Sigma W(f, n_0 ){\text{ }}\exp {\text{ }}[ - \beta (PV + U - \sigma V\varepsilon )]$$ where the strain ?=σ (f ? f ₀) in which f and f ₀ are the fraction of flexed bonds with and without stress, respectively. Furthermore, by this model, the Young's modulus across the transition, E _L and E _G, can be evaluated. The Young's modulus increases with increasing pressure at lower and moderate pressure range but the increase is rather small at very high pressure range.     

Fracture response of polyimide and polysulfone under hydrostatic pressure

Fracture response of polyimide and polysulfone in tension under superimposed hydrostatic pressures up to 100,000 psi is presented. The influence of hydrostatic pressure and the pressure medium on the specific surface energy γ is determined by utilizing the Griffith theory of brittle fracture. For polyimide as well as for polysulfone, γ is found to increase with increasing pressure. Furthermore, for polysulfone at any given pressure level, the value of γ is found to be lower in heptane medium than in kerosene. Heptane is known to be a stress-cracking agent for polysulfone. Fracture surface of the tested tensile specimens is examined by using a scanning electron microscope. The observed fracture features are correlated with the macroscopic deformation behavior and also with the effects of the pressure medium used. In polyimide, the region of crack initiation narrows down from a very broad region at atmospheric pressure to almost a point source along the outer periphery of the specimen at 100,000 psi. In addition, polyimide undergoes a transition in the nature of fracture response between 80,000 to 100,000 psi, and this is clearly indicated in the scanning electron micrographs. In polysulfone, the crack propagation appears to be faster when heptane is used as the pressure medium than when kerosene is used. The penetration of the medium into the specimens can be observed on the micrographs. Several scanning electron micrographs of the fracture surface suggest the possibility of a significant temperature rise in the specimen during fracture. This increase in the specimen temperature is roughly estimated from the stored elastic energy released upon fracture.