Recent advances in modeling of interfaces and mechanical behavior of multilayer metallic/ceramic composites

Since the introduction of the term “nanolaminate” in the mid-1990s, considerable research activities on metallic/ceramic nanolaminates (MCN) have been conducted. Incorporating ceramics with high hardness and high melting point together with high ductile metals can improve their thermomechanical behavior in corrosive environments. A great number of researchers have reported that MCNs exhibit outstanding thermomechanical properties compared with the constituent layers and bulk material, which is attributed to the atomic structure and high density of the interfaces. This article provides a review of recent advances in modeling of the mechanical behavior of MCN composites, with focus on Nb/NbC and Ti/TiN multilayer composites. The main strengthening mechanisms of MCNs, based on the layer thickness, the interface structure, and the interaction of threading dislocations with the interface as well as dislocations nucleation from the interface, are reviewed, and recently, obtained results from molecular dynamics simulations, along with these findings, are presented. Moreover, MD-based flow surfaces for use in large-scale continuum models are reviewed in connection with results from MD of MCNs under various mechanical loading conditions, including uniaxial and biaxial loadings.     

Indicators of coastal groundwater quality changes induced by seawater infiltration

The diminishing public water supply in Greater Beirut induced by various factors since the 1960's reaching its climax during the civil war (1975–1992), led to the drilling of a multitude of private wells in the Cenomanian coastal aquifer. The increasingly high extraction of the groundwater led to progressive changes in the quality of the ground‐water due to seawater infiltration. This problem stimulated some studies directed at detecting and assessing the status and magnitude of the seawater infiltration, but most of them failed to apply any reliable diagnostic indicators designed to detect and to trace any changes in the quality of the groundwater. In contrast, the present study demonstrates the application of certain diagnostic indicators (DI) devised specifically for the detection, progress and trends of seawater infiltration into an aquifer.     

Effect of phthalic anhydride‐based hyperbranched polyesteramide on cement characteristics

Hyperbranched polyesteramides (HB₁ and HB₂) were prepared by the bulk reaction between phthalic anhydride (PhAn) with either diisopropanolamine (DiPA) or diethanolamine (DEA), respectively. The hyperbranched polyesteramides were characterized by IR, GPC, ¹H‐NMR, and thermal analysis (TGA and DSC). The effects of solutions of 1, 3, and 5 wt % HB₁ and HB₂ on the properties of Ordinary Portland Cement (OPC) and Portland Limestone Cement (PLC) were studied. Measurements of water of consistency, setting times, bulk density, apparent porosity, and compressive strength for the cement pastes were performed. Some selected cement pastes were characterized by IR and SEM photos. The results showed that HB₁ and HB₂ slightly increased the compressive strength, the combined water and density while decreased the apparent porosity. IR of the formed phases showed increase in the intensities of the spectra for the cement pastes mixed with HB₁ and HB₂ when compared with those of the blank cement pastes. SEM images showed that the incorporation of HB₁ and HB₂ affected only shape or morphology and crystallinity of the formed hydrates. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2011     

Reverse osmosis technology for water treatment: State of the art review

This paper presents a review of recent advances in reverse osmosis technology as related to the major issues of concern in this rapidly growing desalination method. These issues include membrane fouling studies and control techniques, membrane characterization methods as well as applications to different water types and constituents present in the feed water. A summary of the major advances in RO performance and mechanism modeling is also presented and available transport models are introduced. Moreover, the two important issues of RO brine discharge and energy costs and recovery methods are discussed. Finally, future research trends and needs relevant to RO are highlighted.     

Impact of pH on the adsorption and desorption kinetics of 2-nitrophenol on activated carbons

The adsorption and desorption kinetics of 2-nitrophenol (2NP) from aqueous solutions using F-400 and WV-B granular activated carbons (GAC) have been studied at pHs 1, 4.6 and 13, using batch tests. Adsorption and desorption kinetics of 2NP on to both carbons were adequately described by the homogeneous solid surface diffusion model (HSSD). The adsorption and desorption kinetics can be predicted at different pHs by using adsorption kinetics parameters of the pH 4.6 and the isotherm parameters for the corresponding pH. Thus, the differences in the rates of adsorption are primarily attributable to the differences in the equilibrium loadings at the various pHs.     

Annealing effects on defect levels of CdTe:Cl materials and the uniformity of the electrical properties

CdTe crystals grown by the traveling heater method (THM) often show a pronounced nonuniformity along the ingots due to the thermal irregularities, the Te-excess growth conditions resulting from the retrograde slope of the solidus line of the phase diagram, and from the introduced impurities. In addition, structural defects can be present that influence the electrical and optical properties. The aim of this work is to study the annealing effects of Cl-doped CdTe on the uniformity of the material, the defects, the resistivity, the /spl mu//spl tau/ product, and on the detection properties. Samples have been annealed under various pressures (vacuum, argon, CdCl/sub 2/) and include different temperature stages between 250/spl deg/C and 850/spl deg/C. An increase of the resistivity was observed after a thermal treatment of these samples under argon pressure. In this case, the highest resistivity was obtained by annealing samples at 460/spl deg/C. The presence of CdCl/sub 2/ during the annealing leads to a better uniformity of the materials. The defects present in the materials have been investigated by photo-induced transient current spectroscopy (PICTS), thermo-electric emission spectroscopy (TEES), and thermally stimulated current (TSC) methods, which allow the calculation of their activation energy, their cross section, and their concentration.     

Unknown primary tumors metastatic to liver

PURPOSE: The objectives of this study were to identify prognostic factors for unknown primary tumor (UPT) patients with hepatic metastases, determine the common primary tumors identified, assess the yield of specific diagnostic studies, and evaluate the impact of therapy on survival. PATIENTS AND METHODS: The 1,522 patients analyzed were referred from January 1, 1987 through June 30, 1995. Clinical data from these patients were entered into a computerized database for storage, retrieval, and analysis. Survival was measured from the time of diagnosis; survival distribution was estimated by the product limit method. Multivariate survival analyses were performed by proportional hazards regression. RESULTS: Five hundred UPT patients had liver metastases. Primary tumors, usually lung, colorectal, or pancreatic neoplasms, were identified in 135 patients (27%). The remaining 365 unknown primary carcinoma (UPC) patients with liver involvement had a higher death rate than those without liver involvement (hazards ratio, 1.63; P < .0001). Neuroendocrine carcinoma patients had a lower death rate than patients without this histology (hazards ratio, 0.29; (P < .0001). Two hundred sixteen of 365 patients with UPC and liver metastases received chemotherapy. Chemotherapy-treated patients had a lower death rate than those who were not treated with chemotherapy (hazards ratio, 0.52; P < .0001). The effect of chemotherapy was most pronounced in patients with adenocarcinoma. CONCLUSION: Hepatic metastases in UPC patients portend a generally poor prognosis. However, subsets of patients with more favorable outcomes can be identified by available clinical and pathologic data. Chemotherapy may be beneficial for the large subset of UPC patients with adenocarcinoma that involves the liver.