bluuebunny/crossref_metadata_2025_split huggingface dataset:
Synthesis and Functionality of Cyclophosphazene-Based Polymers
Authors: Inoue Kenzo , Itaya Tomoyuki 
Published: October 2002

Abstract
Linear poly(organophosphazene)s have been widely investigated, mainly to correlate the structure of inorganic –P=N– backbone bearing organic groups with their properties and functionalites. Our interests have been directed to relatively new types of polymers containing a cyclophosphazene unit in the side chains, main chains, or as central core and end groups. The phosphazene groups in these polymers can serve as modification sites of polymers, leading to new functionalized materials. The six or more reactive sites of cyclophosphazenes are suitable for the preparation of star-shaped polymers or hyperbranched polymers including dendrimers. Recent works related with polymeric self-assembly showed that some organocyclophosphazenes are useful motifs for the construction of supramolecules, reflecting the structural features of the cyclotri(phosphazene)s. In this review, we describe the synthesis and functionalities of polymers containing cyclotri(phosphazene)s.
Catalytic Asymmetric Aldol Reaction of Trimethoxysilyl Enol Ethers Using 2,2′-Bis(di-p-tolylphosphino)-1,1′-binaphthyl·AgF Complex
Authors: Yanagisawa Akira , Nakatsuka Yoshinari , Asakawa Kenichi , Wadamoto Manabu , Kageyama Hiromi , Yamamoto Hisashi 
Published: October 2002

Abstract
Catalytic asymmetric Mukaiyama-type aldol reaction using trimethoxysilyl enol ethers was achieved using 2,2′-bis(di-p-tolylphosphino)-1,1′-binaphthyl (p-Tol-BINAP)·AgF complex as a catalyst. The chiral silver(I) catalyst was easily generated by mixing p-Tol-BINAP and silver(I) fluoride in MeOH at room temperature. High syn- and enantioselectivities were obtained from both the E- and Z-silyl enol ethers. Use of a 1 : 1 mixture of MeOH and acetone as a solvent in the reaction of cyclohexanone-derived trimethoxysilyl enol ethers resulted in higher enantioselectivity.
A Divergent Synthesis of Essentially Enantiopure syn- and anti-Propionate Aldol Adducts Based on the Chiral 1,3,2-Oxazaborolidin-5-one-Promoted Asymmetric Aldol Reaction Followed by Diastereoselective Radical Reduction
Authors: Kiyooka Syun-ichi , Shahid Kazi Abuds 
Published: October 2002

Abstract
Essentially, enantiopure syn- and anti-propionate aldol adducts were divergently synthesized using a novel strategy which utilizes both the highly enantioselective 1,3,2-oxazaborolidin-5-one-promoted aldol reaction with a ketene silyl acetal derived from ethyl 2-bromo propionate and a highly diastereoselective radical debromination reaction. These procedures provide yields that increase to a level available for practical synthesis.
High-Temperature Electrochemical Heat Pump Using a Water Gas Shift Reaction. Electrochemical Reduction of CO2 to CO
Authors: Ishihara Akimitsu , Fujimori Tomotaka , Motohira Naobumi , Ota Ken-ichiro , Kamiya Nobuyuki 
Published: October 2002

Abstract
The electrochemical reduction of CO2 to CO, which is considered to be the key reaction in a new electrochemical heat pump using the water gas shift reaction, was theoretically and experimentally investigated. Thermochemical predictions show that CO2 can be reduced to CO below −0.8 V at 973 K. It was found that the overpotential of the electrochemical reduction of CO2 to CO on a gold electrode was about 0.3 V at 0.01 mA cm−2. Below −1.4 V, in the range where carbon deposition took place, CO could be produced by a chemical reaction between CO2 and carbon. X-ray diffraction showed that the deposited carbon was not amorphous, but graphitized carbon.
The economic value of ensemble forecasts as a tool for risk assessment: From days to decades
Authors: Palmer T. N. 
Published: October 2002

AbstractDespite the revolutionary development of numerical weather and climate prediction (NWCP) in the second half of the last century, quantitative interaction between model developers and forecast customers has been rather limited. This is apparent in the diverse ways in which weather forecasts are assessed by these two groups: root‐mean‐square error of 500 hPa height on the one hand; pounds, euros or dollars saved on the other.These differences of approach are changing with the development of ensemble forecasting. Ensemble forecasts provide a qualitative tool for the assessment of weather and climate risk for a range of user applications, and on a range of time‐scales, from days to decades. Examples of the commercial application of ensemble forecasting, from electricity generation, ship routeing, pollution modelling, weather‐risk finance, disease prediction and crop yield modelling, are shown from all these time‐scales.A generic user decision model is described that allows one to assess the potential economic value of numerical weather and climate forecasts for a range of customers. Using this, it is possible to relate analytically, potential economic value to conventional meteorological skill scores. A generalized meteorological measure of forecast skill is proposed which takes the distribution of customers into account. It is suggested that when customers' exposure to weather or climate risk can be quantified, such more generalized measures of skill should be used in assessing the performance of an operational NWCP system. Copyright © 2002 Royal Meteorological Society.
The influence of aerosol concentrations on the glaciation and precipitation of a cumulus cloud
Authors: Phillips Vaughan T. J. , Choularton Thomas W. , Blyth Alan M. , Latham John 
Published: October 2002

AbstractThe response of the glaciation and precipitation of a multi‐thermal cumulus cloud to changes in the aerosol concentration has been assessed in a series of sensitivity tests with the UMIST Explicit Microphysics Model (EMM). A simulation of this cloud from the Met Office cloud‐resolving model (CRM) has been utilized in these tests. This cumulus cloud was observed by aircraft during the initial stage of its growth over New Mexico on 10 August 1987. The growth of the simulated cloud is divided into two parts: a shallow phase followed by a deep phase. Maximum values of the cloud depth in these two phases were 5 and 9 km, respectively.In the EMM simulations including only the shallow phase, the precipitation efficiency was found to decrease substantially with increasing atmospheric concentrations of cloud condensation nuclei (CCN). Also, the graupel mixing ratio and total ice concentration were found to decrease as normalized CCN concentrations were increased above typical continental values. These changes are explicable in terms of: (1) the Hallett–Mossop (H–M) process at −3 to −8°C and the freezing of supercooled raindrops in collisions with ice splinters dominating the glaciation; and (2) the warm‐rain process being more significant for the overall precipitation production than the ice process in these particular simulations. The almost complete suppression of precipitation by extreme CCN concentrations corresponding to a forest‐fire plume in the EMM simulation is consistent with the analysis by Rosenfeld of satellite images of Indonesian cumuli engulfed by smoke from biomass burning.A clear tendency for ice crystals to be smaller and more numerous in the anvil was found with increasing CCN concentrations beyond typical continental values in long‐term simulations that included the deep phase. The sensitivity of the precipitation rate to the normalized CCN concentration was found to be relatively low in these deep cases. Copyright © 2002 Royal Meteorological Society.
The relation of moist symmetric instability and upper‐level potential‐vorticity anomalies to the observed evolution of cloud heads
Authors: Dixon R. S. , Browning K. A. , Shutts G. J. 
Published: October 2002

AbstractThe cloud‐head phenomenon has been known for some time as a precursor of rapid cyclogenesis. Based upon satellite imagery, two stages of cloud‐head development are identified in this study that can be related to early and late stages of the associated cyclone. Weakly convex cloud heads emerge from the baroclinic zone at an early stage in cyclogenesis and strongly convex cloud heads develop in association with the rapid deepening of the cyclone. Trajectories are used to highlight the role of an upper‐level potential‐vorticity (PV) anomaly in the growth of the strongly convex cloud head and the main flow associated with the growth of the strongly convex cloud head is viewed using isentropic analysis. The possible role of moist symmetric instability in the development of both weakly and strongly convex cloud heads is discussed and a new diagnostic for measuring the vertically integrated extent of realizable symmetric (VRS) instability, based on the moist geostrophic PV, is introduced. © Royal Meteorological Society, 2002. G. J. Shutt's contribution is Crown copyright.
Upstream influence of numerically simulated squall‐line storms
Authors: Fovell Robert G. 
Published: October 2002

AbstractThe squall line's impact on its upstream environment is examined using traditional cloud and simplified (parametrized moisture) models. The study was motivated by the need to explain significant differences between the two dynamical frameworks. In both, the first environmental response to the convection consists of a rapidly propagating gravity wave characterized by deep tropospheric subsidence. This gravity wave accelerates the low‐level storm inflow in its wake, with the largest effect seen near the surface.In the more sophisticated model, however, this wave is eventually followed by a shorter vertical wavelength feature, one possessing lower‐tropospheric ascent. This second gravity wave, absent from the simplified model runs, substantially alters the upstream environment yet again. The gentle low‐level uplift establishes the ‘cool/moist tongue’ of air that has been found to stretch well ahead of the storm in simulations. Between the second wave and the main storm updraught, the accelerated inflow is shifted from the ground to the middle troposphere where it helps to push dry air into the convecting region.This subsequent environmental adjustment responds to the establishment of a small yet persistent area of weak cooling during the early mature phase. Located in the middle troposphere at the upstream edge of the main cloud mass, this cooling is the combined effect of cloud‐water evaporation and the ascent of subsaturated air. Though the cooling that excites it is of relatively small magnitude (<2 K), this wave's effect is dramatic and significant. A crude fix to the moisture parametrization served to establish a qualitatively similar tongue‐like feature in the simplified model simulations, bringing the results from the two dynamical frameworks more into line. Copyright © 2002 Royal Meteorological Society.
Policy Watch: U.S. Disability Policy in a Changing Environment
Authors: Burkhauser Richard V , Daly Mary C 
Published: October 2002

In this paper we provide a context for evaluating the goals and effectiveness of current disability policy. We review the Social Security Disability Insurance and Supplemental Security Income programs and examine trends in disability benefit receipt and employment among working-age people with disabilities. We discuss the difficulties in crafting efficient and equitable programs for this difficult to target, heterogeneous population. We conclude that changes in policy rather than in underlying health are most likely behind the increases in disability benefit receipt and the declines in employment of working-age people with disabilities over the 1990s business cycle. This feature contains short articles on topics that are currently on the agendas of policymakers, thus illustrating the role of economic analysis in illuminating current debates. Suggestions for future columns and comments on past ones should be sent to C. Eugene Steuerle, c/o Journal of Economic Perspectives, The Urban Institute, 2100 M Street NW, Washington, D.C. 20037.
Are There Commercial Deposits of Methane Hydrates in Ocean Sediments?
Authors: Hovland Martin 
Published: October 2002

Naturally occurring gas hydrates forming in the ocean floor sediments have, ever since the 1970s, been heralded as the next century's viable energy source. Is this really so? What has the Ocean Drilling Program (ODP) found out about the nature of the Bottom Simulating Reflector (BSR) as an indicator of large volumes of gas hydrates and free natural gas? The findings so far from ODP's legs 146 and 164 have been rather discouraging with respect to the in situ amounts of both gas hydrates and free gas. In the sediments drilled on Leg 146, on the Cascadia accretionary wedge off Oregon, USA, the average amount of gas hydrates above a prominent BSR was estimated at 1 – 2 percent by sediment volume. The free gas amount below the BSR was 3–4 percent by sediment volume. On Leg 164 in the Western Atlantic Ocean (Blake Plateau) some higher amounts, averaging up to 4 – 6 percent and 5 – 7 percent by volume of sediment, respectively, were found. However, on the Hydrate Ridge, off Oregon (Cascadia, just south of Leg 146), there has recently been discovered apparently large amounts of sediment-mixed gas hydrates, which may be exploitable. Although the general percentages found so far are much too low for commercial extraction (even a high-grade copper-ore on land must average more than 6 percent by volume), there may exist some high-grade regions worth exploring. But, the question remains: Where shall we seek the high-grade gas hydrate deposits in ocean sediments? Besides the obvious deep-water high porosity conventional type of reservoirs, and judging from recent findings in the Gulf of Mexico and the Caspian Sea, perhaps the most promising locations are those where mud volcanoes occur on the ocean floor.
Study of the Adsorption Mechanism and the Structure of Adsorbed Layers of Polyelectrolytes at the Metal Oxide/Solution Interface
Authors: Chibowski S. , Wiśniewska M. 
Published: October 2002

The influence of the molecular weight of polyacrylic acid (PAA) and polyacrylamide (PAM) as well as of inorganic contaminants on the ZrO2 surface on the adsorption and electrokinetic properties of the metal oxide/polyelectrolyte solution interface were studied for ZrO2 and Fe2O3 solid particles. The calculated concentrations of the various surface groups on ZrO2 and Fe2O3 enabled an investigation of the possible mechanism for the bonding of the studied polyelectrolytes with the surfaces of both oxides. PAA and PAM macromolecules bond with the solid surface mainly via the –OH groups of the oxides, which may interact with the carboxy groups of polyelectrolytes through hydrogen bridging. A comparison of the change in values of the diffuse layer charge with the surface charge enabled the principal factors responsible for the changes in the zeta potential of the oxides, e.g. pH, polymer molecular weight and concentration of the polymer solutions, to be evaluated. From such zeta potential values, it was possible to determine the free energies of adsorption of PAA and PAM on the surfaces of both oxides. The thicknesses of adsorbed polymer layers on Fe2O3 and ZrO2 were calculated on the basis of measurements of their suspension viscosities in the absence and presence of adsorbed polymer. It was shown that the thickness of the adsorption layer increased with increasing polymer molecular weight, pH and concentration of the polymer solution. Because the experimental determination of the number and the length of trains, loops and tails in such polyelectrolytes was not possible, the participation of such segments of polymer structure at the interface was computed using the Scheutjens–Fleer model of polymer adsorption. The polymer adsorption expressed as the number of equivalent monolayers was calculated and compared with the experimental data.
Modified Silica for the Extraction of Cadmium(II), Copper (II) and Zinc(II) Ions from Their Aqueous Solutions
Authors: Khalil L.B. , Attia Amina A. , El-Nabarawy Th. 
Published: October 2002

Increasing concentrations of heavy metal ions in aquatic systems have led to a search for very efficient matrices for their removal. Zirconium(IV) phosphate has been used for many years as a cation-exchanger and dispersion of this phosphate on a high surface area silica might be expected to improve the extraction properties of the material. Modified silica matrices (SiZrP) were prepared by refluxing high surface area silica with zirconium tetrachloride dissolved in ethanol, followed by stirring the dried product in an appropriate volume of 0.1 M H3PO4. The dried SiZrP samples thus obtained were used to extract Cd2+, Cu2+ and Zn2+ ions from their aqueous solutions under varying conditions. The most efficient SiZrP sample was obtained when ZrCl4 was allowed to react with the silica in a 1:1 ratio. High extraction of all the ions studied at an initial concentration of 150 ppm was achieved over the pH range 3.5–6.0, with the order of metal ion extraction being Cd2+ > Cu2+ > Zn2+.
Active Structural and Acoustic Control of Structure-Borne Road Noise in a Passenger Car
Authors: Sas Paul , Dehandschutter Wouter 
Published: October 2002

Within the Brite-Euram Project “Anrava” several active control systems have been evaluated in order to reduce the road noise generated inside the cabin of a mid size station wagon during driving condition on different road surfaces. Different control strategies (feedforward with local and global control, pure feedback) and different approaches (active structural acoustic control and active noise control) have been tested on the car in laboratory conditions and the control performances have been evaluated. The final control strategies that have been selected based on the results of this study, are based on an adaptive feedforward control algorithm: six accelerameters provide the reference signals and 4 microphones placed inside the cabin give the error feedbacks. Two control configurations, each using a different kind of control source, have been retained : a structural acoustic control system which works with 6 inertial shakers positioned at the main vibration transmission paths of the car suspension, an anti-noise system with 4 loudspeakers inside the cabin. The paper describes the approaches utilised to design the different control systems and presents the results obtained during laboratory and road tests, comparing them with the performances predicted by numerical simulations.
Estimation of Reverberation Time in Rectangular Rooms with Non-Uniformly Distributed Absorption Using a Modified Fitzroy Equation
Authors: Neubauer Reinhard O. 
Published: October 2002

One of the major objectives of architectural acoustics is to predict the reverberation time in a room. At this time there are several calculation methods to compute the reverberation time, but still Sabine's and Eyring's classical equations are used. In many practical cases the assumption of diffuse sound field conditions for applying Sabine's theory are not in agreement with the existing sound absorption distribution. Therefore, Sabine's formula, as well as other classical reverberation equations like Eyring's or Millington-Sette's, cannot be applied accurately. In 1959 Fitzroy published a paper devoted to the problem of a more accurate calculation of the reverberation time with non-uniformly distributed absorption. In real rooms Fitzroy's equation may therefore become a useful design tool for estimating reverberation time, however, only if it is modified. A modification of Fitzroy's equation is discussed in this paper and some practical examples are presented which compare predicted and measured values of reverberation time in real rooms. A suggested modification of Fitzroy's equation is presented. Differences between results derived from Fitzroy's, Sabine's, Eyring's and the modified Fitzroy equation as well as results obtained using a room acoustic computer simulation program are compared. Additionally, results are presented and compared using the calculation method of Annex D of prEN 12354-6.
Optimum Design of Reinforced Concrete Beams Using Polynomial Optimization Technique
Authors: Dole Rashmi , Ronghe G. N. , Gupta L. M. 
Published: October 2002

Structural optimization seeks the selection of design variables to achieve within the limit (constraints) placed on the structural behaviour, geometry or other factors; its goal of optimality defined by the objective function for specified loading conditions. The three basic features design variables, objective function and constraints contrive to form the design problem. There are several mathematical techniques to solve such problems. The polynomial optimization technique is a recently evolved procedure which is concerned with finding the minimum of a polynomial objective function subjected to constraints. A structural design problem has been formulated in this manner which enables minimum cost design to be derived rapidly and simply. A paper deals with the application of Polynomial optimization technique to R.C.C. beam-member design problem. In the present study this technique is used to determine the minimum cost of reinforced concrete members by considering several design variables such as breadth, depth, area of reinforcing steel etc. Since it is difficult for the designer in the office to become familiar with the mathematical computation required, further attempt is made to represent the resulting optimum design expressions in the form of “Nomograms” which will facilitate the work in the design office.
Plasma chitotriosidase activity in patients with β‐thalassemia
Authors: Altarescu G. , Rudensky B. , Abrahamov A. , Goldfarb A. , Rund D. , Zimran A. , Elstein D. 
Published: October 2002

AbstractVariable increases in chitotriosidase levels have been reported in Italian patients with β‐thalassemia major and intermedia. We measured plasma chitotriosidase levels in Israeli patients with β‐thalassemia to ascertain its use as a universal marker of disease and/or response to therapy. Chitotriosidase levels in 39 adults (16–53 years; 30 with β‐thalassemia major, 9 with intermedia), and in 14 children (0.7–15 years; 12 with β‐thalassemia major, 2 with intermedia) were compared with other measures of disease, such as ferritin, hemoglobin, liver function tests, and genotype. Plasma chitotriosidase levels were normal (0.37 ± 0.04 mU/mL) in all children. Twelve adults (31%) had elevated levels (>1.33 mU/mL): 11 patients (37%) with thalassemia major and 1 patient (11%) with thalassemia intermedia. A significant correlation was only found between plasma chitotriosidase levels and ferritin levels, and with mean number of transfusions per year. The patient with the highest chitotriosidase (1,440 nmol/mL/hr) had the highest ferritin (5,175 μg/L), required the most transfusions per year (40), and had abnormal liver tests. Normal chitotriosidase levels in the pediatric cohort and increased levels in only some adults may reflect status of iron overload in macrophages; thus there may be a role for monitoring chitotriosidase in patients with β‐thalassemia. Our results confirm results of the Italian cohort; however, in the latter, a more universal correlation was noted and chitotriosidase levels were much higher. Am. J. Hematol. 71:7–10, 2002. © 2002 Wiley‐Liss, Inc.