A numerical assessment of the load bearing capacity of externally pressurized moderately thick tubes

The collapse behavior of cylindrical shells pressurized from outside is examined. Attention is focused on tubes of moderate thickness, as required by very deep water pipelines or some innovative nuclear power plant proposals. Their collapse is expected to be dominated by yielding but, because of the decreasing nature of the post-collapse evolution, interaction with instability is likely to be significant enough to demand consideration. At present, no quantitative assessment of such effect is available, because little study has been devoted to tubes in this thickness range.Plasticity–instability interaction is activated by imperfections and to assess their influence on a systematic numerical study is undertaken. Computations produce a meaningful measure of the collapse pressure and it is proposed that the allowable pressure be determined on its basis, by introducing a suitable safety factor. This is chosen so that results reproduce those provided by presently accepted procedures in the well explored and reliable range of medium-thin tubes. When the same factor is applied to thicker tubes, the resulting allowable pressure is significantly higher than the values suggested by codes, which apparently react to the present lack of knowledge by assuming an extremely conservative attitude.     

Mutations in the nonstructural 5A region of hepatitis C virus and response of chronic hepatitis C to interferon alfa

BACKGROUND & AIMS: Mutations in hepatitis C virus (HCV) nonstructural protein 5A (NS5A) may correlate with response to interferon in Japanese patients with chronic hepatitis C. The aim of this study was to examine whether these findings could be expanded to European patients infected with genotypes associated to low (1b) or high (3a) response rates. METHODS: Pretreatment serum samples of 66 patients with chronic HCV infection, 48 infected with genotype 1b and 18 with 3a, were analyzed. RESULTS: Among patients infected with genotype 3a, 1 of 7 long-term responders and none of 11 nonresponders showed NS5A amino acid mutations. Among patients infected with genotype 1b, all 7 long-term responders, but also 27 of 41 nonresponders, showed NS5A mutations. There was no correlation between number of mutations and response to therapy. In 10 patients, sequences obtained before and after treatment were compared and failed to show any change. Serum HCV RNA levels did not differ between patients with and without mutations in NS5A sequence. CONCLUSIONS: No significant correlation was found in patients infected with genotypes 1b or 3a between NS5A sequence and response to interferon alfa. NS5A mutations do not correlate with viral load. Changes in this region were not found during interferon alfa treatment.     

Advances in the Management of Central Nervous System Metastases from Breast Cancer

Central nervous system (CNS) metastases are common in breast cancer (BC) patients and are particularly relevant as new treatments for BC are prolonging survival. Here, we review advances in the treatment of CNS metastases from BC, including radiotherapy, systemic therapies, and the evolving role of immunotherapy. The use of radiotherapy and chemotherapy is the cornerstone of treatment for CNS metastases. However, new targeted therapies have recently been developed, including anti-HER2 agents and antibody–drug conjugates that have presented promising results for the treatment of these patients.     

Selective Laser Post-Treatment on Titanium Cold Spray Coatings

The aim of the present work is to investigate the feasibility and effects of a selective postdeposition laser treatment on titanium coatings. Commercially pure titanium grade 2 powders were deposited by means of a cold spray process on aluminum alloy AA2024-T3 sheets. The surface treatment of the coating was realized using a 220 W diode laser. The influence of heat input and dimensional features of coating layer and substrate was assessed by an experimental campaign conducted following a design of experiments approach. Optical and scanning electron microscopy analysis of the microstructure of the deposited and treated material as well as microhardness measurements showed the formation of a compact layer of titanium oxide on the coating surface and the preservation of the temper state of the aluminum substrate.     

Past Editors and Editorial Collaborators 1976

D-optimal fractions of three-level factorial designs for p factors are constructed for factorial effects models (2 ≤ p ≤ 4) and quadratic response surface models (2 ≤ p ≤ 5). These designs are generated using an exchange algorithm for maximizing |X′X| and an algorithm which produces D-optimal balanced array designs. The design properties for the DETMAX designs and the balanced array designs are tabulated. An example is given to illustrate the use of such designs.     

Statistical Programs for High Speed Computers

Response surface methodology, an experimental strategy initially developed and described by Box and Wilson, has been employed with considerable success in a wide variety of situations, especially in the fields of chemistry and chemical engineering. It is the purpose of this paper to review the literature of response surface methodology, emphasizing especially the practical applications of the method. A comprehensive bibliography is included.     

Copper(I) Iodide as Hole‐Conductor in Planar Perovskite Solar Cells: Probing the Origin of J–V Hysteresis

Organic–inorganic lead halide perovskite solar cells are promising alternatives to silicon‐based cells due to their low material costs and high photovoltaic performance. In this work, thin continuous perovskite films are combined with copper(I) iodide (CuI) as inorganic hole‐conducting material to form a planar device architecture. A maximum conversion efficiency of 7.5% with an average efficiency of 5.8 ± 0.8% is achieved which, to our knowledge, is the highest reported efficiency for CuI‐based devices with a planar structure. In contrast to related planar 2,2′,7,7′‐tetrakis‐(N,N ‐di‐4‐methoxyphenylamino)‐9,9′‐spirobifluorene (spiro‐OMeTAD)‐based devices, the CuI‐based devices do not show a pronounced hysteresis when tested by scanning the potential in a forward and backward direction. The strong quenching of photoluminescence (PL) signal and comparatively fast decay of open‐circuit voltage demonstrates a more rapid removal of positive charge carriers from the perovskite layer when in contact with CuI compared to spiro‐OMeTAD. A slow response on a timescale of 10–100 s is observed for the spiro‐OMeTAD‐based devices. In comparison, the CuI‐based device displays a significantly faster response as determined through electrochemical impedance spectroscopy (EIS) and open‐circuit voltage decays (OCVDs). The characteristically slow kinetics measured through EIS and OCVD are linked directly to the current–voltage hysteresis.     

Local measurements in the flow of a steam injector and visualisation

A steam injector is a thermocompression device where the steam drags directly a subcooled liquid and delivers a liquid with an outlet pressure higher than both upstream fluid pressures. The functioning principle of injectors involves sophisticated thermohydraulic processes whose present knowledge is essentially empirical. This work presents an experimental approach of steam injector in order to finely understand and quantify the physical laws driving the flow in the mixing chamber. Local measurements (2D) are carried out on a special device with a rectangular section, where the flow was visualised. These measurements are the void fraction, the static pressure and the static temperature. They permit the calculation of all the variables and a well understanding of the physical phenomena involved in the flow. Especially, we show, in some well-defined zones, the existence of important non-equilibrium kinetic, thermal and thermodynamic phenomena.     

Three-dimensional printed yttria-stabilized zirconia self-supported electrolytes for solid oxide fuel cell applications

Additive manufacturing represents a revolution due to its unique capabilities for freeform fabrication of near net shapes with strong reduction of waste material and capital cost. These unfair advantages are especially relevant for expensive and energy-demanding manufacturing processes of advanced ceramics such as Yttria-stabilized Zirconia, the state-of-the-art electrolyte in Solid Oxide Fuel Cell applications. In this study, self-supported electrolytes of yttria-stabilized zirconia have been printed by using a stereolithography three-dimensional printer. Printed electrolytes and complete cells fabricated with cathode and anode layers of lanthanum strontium manganite- and nickel oxide-yttria-stabilized zirconia composites, respectively, were electrochemical characterized showing full functionality. In addition, more complex configurations of the electrolyte have been printed yielding an increase of the performance entirely based on geometrical aspects. Complementary, a numerical model has been developed and validated as predictive tool for designing more advanced configurations that will enable highly performing and fully customized devices in the next future.     

Aloe vera gel influence on the micellization behavior of copolymer Pluronic F127: A potential photosensitizer carrier for topical application

This work describes the influence of aloe vera gel on Pluronic F127 triblock copolymer (F127) micellization behavior. Aloe vera gel was obtained from aloe vera mucilage found in leaf pulp. F127 (20% w/w) gel and the aloe vera/F127 blend gel were obtained by using the cold method. Fourier transform infrared spectroscopy and X‐ray diffraction analyses of lyophilized samples did not show any important copolymer interaction between aloe vera gel and F127. However, in aqueous medium, the dynamic light scattering data showed that there was an important reduction in micelle size with increasing temperature of the aloe vera/F127 blend hydrogel. The differential scanning calorimetry results indicate that the aloe vera/F127 blend has a higher micellization temperature, affected by the lower dehydrating effect of the poly(propylene oxide) blocks during the micelle formation in comparison to F127 gel. The texture analyses (hardness and adhesiveness) showed that the addition of aloe vera gel did not change the Pluronic F127 gel texture properties. The photosensitizer zinc phthalocyanine (ZnPC) was incorporated into the aloe vera/F127 blend, and the results suggest that this formulation is suitable as a ZnPC delivery system for photodynamic therapy. © 2018 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2018 , 135, 46191.