bluuebunny/crossref_metadata_2025 huggingface dataset:
Effect of Channeling Agents on the Release Profile of Theophylline from METHOCEL K4M Based Matrix tablets
Authors: Razzak Md Shaikhul Millat Ibn , Khan Ferdous , Khan Md Ziaur Rahman , Fatema Kanij , Islam Muhammed Shahidul , Reza Md Selim
Published: October 2008

The present study was undertaken to investigate the effect of channeling agents on the release profile of Theophylline from METHOCEL K4M based matrix systems. Matrix tablets of Theophylline using METHOCEL K4M were prepared by direct compression process. METHOCEL K4M polymer is hydrophilic in nature. NaCl and PEG 1500 were used as channeling agents. Drug release study was evaluated for eight hours using USP 22 paddletype dissolution apparatus using distilled water as the dissolution medium. The release mechanisms were explored and explained with zero order, Higuchi and Korsmeyer equations. The release rate, extent and mechanisms were found to be governed by channeling agent type and content. Higher channeling agent content (42.49%) in the matrix increased the rate and extent of the drug release because of increased porosity in the tablet matrices, at lower channeling agent (19.76%) level, the rate and extent of drug release was decreased and in absence of channeling agents these were least. NaCl ensures maximum release of drug from low viscosity grade METHOCEL K4M than PEG 1500 when other parameters were kept constant. It was found that type and amount of channeling agent significantly affect the time required for 50% of drug release (T50%), percentage drug release at 8 hours, release rate constant (K) and diffusion exponent (n). Kinetic modeling of dissolution profiles revealed drug release mechanism ranges from diffusion controlled or Fickian transport to anomalous type or non-Fickian transport, which was mainly dependent on the presence of type and amount of channeling agent. These studies indicate that the proper balance between a matrix forming agent and a channeling agent can produce a drug dissolution profile similar to a theoretical dissolution profile.Key words: Channeling agent, Theophylline, Release Profile, Methocel K4MDOI = 10.3329/dujps.v7i1.1214Dhaka Univ. J. Pharm. Sci. 7(1): 27-32, 2008 (June)
Study of Moisture Absorption by Ranitidine Hydrochloride: Effect of % RH, Excipients, Dosage Forms and Packing Materials
Authors: Islam SM Ashraful , Hossain Md Amir , Kabir ANM Hamidul , Kabir Shaila , Hossain Md Khalid
Published: October 2008

Moisture absorption by ranitidine at three different level of relative humidity (RH) has been studied. Percentage of moisture absorption at 22%, 57% and 75% RH was 0.6%, 3.1%, and 4.9% respectively. Ranitidine blended with various excipients (maize starch, lactose, avicel PH-101, mannitol, povidone K-30, magnesium stearate and purified talc) were also exposed to 75% relative humidity (% RH) to observe their effects on moisture absorption. Moisture absorption by ranitidine was either increased or decreased when ranitidine was mixed with various diluents, binders and lubricants. Ranitidine mixed with lactose, aerosil-200 and avicel PH-101 absorbed minimum amount of moisture while ranitidine mixed with maize starch absorbed maximum. On the other hand, ranitidine mixed with mannitol was found to absorb intermediate amount of moisture. Ranitidine mixed with povidone K-30 absorbed almost double moisture than pure ranitidine. Ranitidine mixed with purified talc and magnesium stearate absorbed almost same amount of moisture. The type of dosage form and type of packing materials also influenced moisture absorption. Uncoated tablets absorbed maximum amount of moisture (4.5%) while coated tablets absorbed minimum (2%). On the other hand, capsule was found to absorb intermediate amount of moisture (3.4%). PVC-Alu foil packed uncoated ranitidine tablet absorbed more moisture (3.3%) than that of Alu-Alu packed uncoated ranitidine tablet (0.16%). Key words: % RH, ranitidine hydrochloride, moisture, absorption Â DOI = 10.3329/dujps.v7i1.1219 Dhaka Univ. J. Pharm. Sci. 7(1): 59-64, 2008 (June)
Antimicrobial and Cytotoxic Activities of Dillenia pentagyna
Authors: Haque Md Enamul , Islam Md Nahidul , Hossain Mahbub , Mohamad Akim Uddin , Karim Md Fazlul , Rahman Md Atiar
Published: October 2008

DOI = 10.3329/dujps.v7i1.1228Dhaka Univ. J. Pharm. Sci. 7(1): 103-105, 2008 (June)
From Text to Dance: Andrée Howard's The Sailor's Return
Authors: JONES SUSAN
Published: October 2008

This essay explores the source material for Andrée Howard's 1947 narrative work for Ballet Rambert, The Sailor's Return. Howard based her libretto for the ballet on David Garnett's 1925 novel of the same name, closely following his story of a West African princess who marries an English sailor and encounters racial prejudice in England. I examine the textual and choreographic contexts for the ballet, relating its visual rhetoric and movement vocabularies to a variety of sources from nineteenth- and twentieth-century literature and dance. In investigating the novel, we find that Garnett drew on Richard Burton's 1864 anthropological account of Dahomey (now Benin) in West Africa, especially his striking descriptions of Amazonian dance. I locate these transmissions between text and dance in the context of modernist discussions of primitivism, showing that while aspects of Howard's ballet conform to enduring primitivist traditions, its focus on the female protagonist's individuality and ethnic origins reflects the anthropological thrust of the textual sources and offers a striking critique of racism in a realist mode. Howard's choreographic style can also be located in the context of contemporary experiments in black performance dance. Her sensitive handling of sources shows her important contribution to narrative ballet and the distinctiveness of her presentation of female experience in the period.
Anticancer Alkaloid Lamellarins Inhibit Protein Kinases
Authors: Baunbæk Dianne , Trinkler Nolwenn , Ferandin Yoan , Lozach Olivier , Ploypradith Poonsakdi , Rucirawat Somsak , Ishibashi Fumito , Iwao Masatomo , Meijer Laurent
Published: October 2008

Lamellarins, a family of hexacyclic pyrrole alkaloids originally isolated from marine invertebrates, display promising anti-tumor activity. They induce apoptotic cell death through multi-target mechanisms, including inhibition of topoisomerase I, interaction with DNA and direct effects on mitochondria. We here report that lamellarins inhibit several protein kinases relevant to cancer such as cyclin-dependent kinases, dualspecificity tyrosine phosphorylation activated kinase 1A, casein kinase 1, glycogen synthase kinase-3 and PIM-1. A good correlation is observed between the effects of lamellarins on protein kinases and their action on cell death, suggesting that inhibition of specific kinases may contribute to the cytotoxicity of lamellarins. Structure/activity relationship suggests several paths for the optimization of lamellarins as kinase inhibitors.
MULTI‐OBJECTIVE DECISION‐MAKING FOR ROAD DESIGN
Authors: Brauers Willem Karel M. , Zavadskas Edmundas Kazimieras , Peldschus Friedel , Turskis Zenonas
Published: October 2008

Multi‐objective analysis is a popular tool to solve many economic, managerial and construction problems. The objective of this research is to develop and implement a methodology for multi‐objective optimization of multi‐alternative decisions in road construction. After a rough overview of the articles dealing with the multi‐objective decision and assessment of road design alternatives described by discrete values, Multi‐Objective Optimization on the basis of the Ratio Analysis (MOORA) method was selected. This method focuses on a matrix of alternative responses on the objectives. A case study demonstrates the concept of multi‐objective optimization of road design alternatives and the best road design alternative is determined.
SEA MOTORWAYS AS A PART OF THE LOGISTICS CHAIN
Authors: Paulauskas Vytautas , Bentzen Kent
Published: October 2008

This paper presents the main tools of Sea Motorways as an important part of the logistics chain and can be used presented methodically as a framework for designing logistics or supply chains along with sea motorways. Various factors influencing the choice of logistics chains with sea motorway part are described. The methodology of evaluating sea motorways and the logistics chain is furnished. The paper concludes by identifying the best logistics chains including sea motorways.
STAKEHOLDER APPROACH IN THE MANAGEMENT OF PUBLIC TRANSPORT COMPANIES
Authors: Susnienė Dalia , Jurkauskas Algirdas
Published: October 2008

The sustainable development of urban mobility cannot be envisaged without a transport system which could be able to meet the needs of citizens and businesses, make a positive impact on the environment and be socially fair and economically efficient. An efficient transport system increases safety, improves network efficiency and stimulates intermodality which reduces transport impact on environment and makes cities more attractive. In order to survive and successfully operate in the market, it is necessary for public transport companies to look for and implement new management models in their system. Every organization is surrounded by the environment and it is very important to examine external factors if an organization wants to gain a strong position in the market which is also important for public transport companies. The involvement of stakeholders in the supply of public transport services i.e. what level of relationships are needed between a transportation company and its various stakeholders is necessary in order to meet the main stakeholder ‐ passenger needs. Consequently, as to supply the passenger with the best service, relationships between different stakeholders (municipality, public transport company, state road maintenance service etc.) are of vital importance. It is essential to emphasise that state institutions and municipalities play a crucial role in managing public transport companies. State institutions influence them through legal instruments and regulations and municipalities, as the main shareholders, through the impact on management board and through subsidizing the company from municipality budget. Therefore, it is very important to have in mind this particularity in managing public transport companies and in the relationships with their stakeholders.
DECISION SUPPORT SYSTEM FOR SOLVING THE STREET ROUTING PROBLEM
Authors: Matis Peter
Published: October 2008

Servicing a large number of customers in a city zone is often a considerable part of many logistics chains. The capacity of one delivery vehicle is limited, but, at the same time, it usually serves plenty of customers. This problem is often called a Street Routing Problem (SRP). Key differences between Vehicle Routing Problem (VRP) and SRP are presented here. The main problem of SRP is that when the number of customers is huge, the number of delivery path combinations becomes enormous. As the experimental results show in the case of SRP the error on the length of delivery routes based on an expert's judgment when compared to the optimal solution is in the range of 10–25%. As presented in the paper, only using decision support systems such as Geographical Information Systems (GIS) makes possible to effectively manage SRP. Besides classical measurements used in VRP, such as total length of routes or time required for delivery in each route, other measurements, mostly qualitative ones, are presented. All of these are named as visual attractiveness. This paper discusses possible relationships between quantitative and qualitative measurements that give a promise for finding better solutions of SRP. Several new types of heuristics for solving SRP are evaluated and afterward compared using the real data. One of the key properties of GIS to use routing software is its flexible interactive and user‐friendly environment. Routing software can find a good solution and explore the possibilities while an expert later can change the calculated routes to explore other possibilities based on the expert's judgment. This paper presents a practical use of new heuristics with the ArcView and solution of address mail for several cities in Slovakia served by Slovak Post ltd. Other Decision Support Systems that solve SRP are presented as TRANSCAD developed by Caliper Corporation or GeoRoute promoted by Canadian Post and GIRO.
THE IMPACT OF THE INTERNAL WELDING DEFECTS ON THE JOINT STRENGTH
Authors: Didžiokas Rimantas , Janutėnienė Jolanta , Jonaitytė Jurgita
Published: October 2008

The paper looks at the impact of the internal welding defects on the strength of joints. The tension tests provided the values of the welded joint strength limits depending on the area of sporadic voids, slag intrusions and the field of discontinuities. Considering the results of the conducted experiments, the mathematical relationships between the strength of the welded joint and defected area were concluded. In presence of all three defects, the distance of the defects from the weld surface was measured. It is deduced that the defects nearer to the surface reduce the strength of the welded joint more than those noticed in deeper layers.
HYDRODYNAMIC COEFFICIENTS AND FORCES ON MULTIHULLS IN SHALLOW WATER WITH CONSTANT OR VARIABLE DEPTH
Authors: Dabssi Noureddine , Chagdali Mohamed , Hémon Alain
Published: October 2008

Numerical and hydro dynamical procedures are developed to compute bidimensional hydrodynamic coefficients and forces on multihulls associated with harmonic oscillations in shallow water with constant or variable depth. The forces are composed of two parts and include the sum of incident and diffracted forces and hydrodynamic reaction. The latter one is used to determinate the hydrodynamic coefficients (added mass and damping). The numerical method used is the Boundary Element Method. We can compute flow around multihulls sections. An application to cylindrical, right triangular and rectangular hull forms is presented.
ASSESSMENT OF EMPLOYEE'S KNOWLEDGE POTENTIAL IN TRANSPORT SECTOR
Authors: Morkvėnas Renatas , Bivainis Juozas , Jaržemskis Andrius
Published: October 2008

Although plenty of scientists have researched the theoretical and practical problems of assessing knowledge potential for a few decades, the unified and single methodology of assessment has not been accepted. Discussions on the factors having the strongest impact on the knowledge potential of employees have been processed. The method stated in this article is adopted to transport sector. An evaluation of specifications for the factors making a real impact helped with building a model including such factors as educational level, occupational experience, occupation level, dutifulness, decision making and responsibility level, self‐support at work, work culture, difficulty level at work, motivation, employee's influence on achieving organization's aim and the level of using technology at work. The specifications of the above introduced factors have been prepared. Practical acceptance of the model has been researched by an experiment conducted in a transport company.
THE INTEGRATED EVALUATION OF THE MACRO ENVIRONMENT OF COMPANIES PROVIDING TRANSPORT SERVICES
Authors: Žvirblis Algis , Zinkevičiūtė Virgilija
Published: October 2008

The article presents the main principles of the integrated evaluation of macro environment components and factors influencing the performance of transport companies as well as providing the validated quantitative evaluation models and results obtained in evaluating the macro environment of Lithuanian companies providing transport services. Since quantitative evaluation is growing in importance, the process of developing the principles and methods of business macro environment quantitative evaluation is becoming relevant from both theoretical and practical perspectives. The created methodology is based on the concept of macro environment as an integrated whole of components, formalization and the principle of three‐stage quantitative evaluation. The methodology suggested involves the quantitative evaluation of primary factors and macro environment components as an integral dimension (expressed in points). On the basis of this principle, an integrated macro environment evaluation parameter is established as its level index. The methodology integrates the identification of significant factors, building scenarios, a primary analysis of factors, expert evaluation, the quantitative evaluation of macro environment components and their whole. The application of the multi‐criteria Simple Additive Weighting (SAW) method is validated. The integrated evaluation of the macro environment of Lithuanian freight transportation companies was conducted. As a result, the level indices of all components as well as the level index of macro environment considered as a whole of components were identified. The latter reflects the extent of deviation from an average level of a favourable macro environment. This is important for developing strategic marketing decisions and expanding a strategic area.
GOVERNANCE AND INSTITUTIONS OF TRANSPORTATION INVESTMENTS IN U.S. MEGA‐REGIONS
Authors: Vega Henry L. , Penne Leo
Published: October 2008

From a planning perspective, a mega‐region can be defined as an extended network of metropolitan centers and their surrounding areas, crossing county and state lines, linked by integrated labor markets, land use systems and transportation and communication infrastructure. From a governance perspective, delimiting the jurisdictional borders of a mega‐region is rather challenging due to the overlap of hierarchy of governance systems. It has been suggested that the effective management of existing transportation infrastructure and the planning and financing of new investments in these areas will need to operate under a regional framework of governance. What such regional framework might look like is still subject to debate. Despite years in the planning, currently no mega‐regional transportation initiative has been implemented in the U.S. This article uses descriptive and interpretative analysis to further the debate in two areas. It first reviews definitional issues in the existing literature as they apply to mega‐regions and transportation. Second, it undertakes a comprehensive survey of regional initiatives, such as the Corridors of the Future Program, to highlight the complexity of multi‐state transportation projects. Lessons from this survey can be useful when developing future transport policy, as policymakers increase their efforts to adopt regional governance initiatives to finance transportation investments worldwide.
Surface‐Dominated Transport Properties of Silicon Nanowires
Authors: Jie Jiansheng , Zhang Wenjun , Peng Kuiqing , Yuan Guodong , Lee Chun Sing , Lee Shuit‐Tong
Published: October 2008

Surface effects are widely recognized to significantly influence the properties of nanostructures, although the detailed mechanisms are rarely studied and unclear. Herein we report for the first time a quantitative evaluation of the surface‐related contributions to transport properties in nanostructures by using Si nanowires (NWs) as a paradigm. Critical to this study is the capability of synthesizing SiNWs with predetermined conduction type and carrier concentration from Si wafer of known properties using the recently developed metal‐catalyzed chemical etching method. Strikingly, the conductance of p‐type SiNWs is substantively larger in air than that of the original wafer, is sensitive to humidity and volatile gases, and thinner wires show higher conductivity. Further, SiNW‐based field‐effect transistors (FETs) show NWs to have a hole concentration two orders of magnitude higher than the original wafer. In vacuum, the conductivity of SiNWs dramatically decreases, whereas hole mobility increases. The device performances are further improved by embedding SiNW FETs in 250 nm SiO2, which insulates the devices from atmosphere and passivates the surface defects of NWs. Owing to the strong surface effects, n‐type SiNWs even change to exhibit p‐type characteristics. The totality of the results provides definitive confirmation that the electrical characteristics of SiNWs are dominated by surface states. A model based on surface band bending and carrier scattering caused by surface states is proposed to interpret experimental results. The phenomenon of surface‐dependent transport properties should be generic to all nanoscale structures, and is significant for nanodevice design for sensor and electronic applications.
Cold Consolidation of Metal–Ceramic Nanocomposite Powders with Large Ceramic Fractions
Authors: Menéndez Enric , Salazar‐Alvarez German , Zhilyaev Alexander P. , Suriñach Santiago , Baró Maria Dolors , Nogués Josep , Sort Jordi
Published: October 2008

Co/α‐Al2O3 powder mixtures (5, 10, 20, 30, 40, and 50 mass % of α‐Al2O3) have been ball‐milled and, subsequently, consolidated at room temperature by means of a high pressure torsion procedure in order to produce bulk nanostructured composites. For mixtures up to 20% of α‐Al2O3, the cold‐compaction results in roughly fully dense disks with relatively high microhardness values. However, the compaction for 30, 40, and 50% of α‐Al2O3 is less effective, resulting in a reduction of the microhardness although a structure in the nanoscale range is still preserved. A detailed structural investigation has been also performed.
Synthesis of Polymerizable Superoxide Dismutase Mimetics to Reduce Reactive Oxygen Species Damage in Transplanted Biomedical Devices
Authors: Cheung Charles Y. , McCartney Suzanne J. , Anseth Kristi S.
Published: October 2008

A new polymerizable superoxide dismutase (SOD) mimetic metalloporphyrin macromer was synthesized to minimize inflammatory damage associated with tissue transplantation and biomaterial implantation, such as the use of encapsulated pancreatic islets for the treatment of type I diabetes mellitus (TIDM). This functional SOD mimetic, Mn(III) Tetrakis[1‐(3‐acryloxy‐propyl)‐4‐pyridyl] porphyrin (MnTPPyP‐Acryl), was copolymerized and crosslinked with poly(ethylene glycol) diacrylate (PEGDA) to form hydrogel networks that may actively reduce reactive oxygen species (ROS) damage associated with biomaterial implantation. Solution phase activity assays with MnTPPyP‐Acryl macromers showed comparable SOD activity to MnTMPyP, a non‐polymerizable commercially available SOD mimetic. This work also describes the development of a new, simple, and inexpensive solid phase assay system that was developed to assess the activity of MnTPPyP‐Acryl macromers polymerized within PEGDA hydrogels, which has the potential to fulfill an existing void with the biochemical tools available for testing other immobilized ROS antagonists. With this new assay system, hydrogels containing up to 0.25 mol% MnTPPyP‐Acryl showed significantly higher levels of SOD activity, whereas control hydrogels polymerized with inactive TPPyP‐Acryl macromers showed only background levels of activity. The potential for repeated use of such hydrogel devices to consistently reduce superoxide anion concentrations was demonstrated upon retention of ∼100% SOD activity for at least 72 h post‐polymerization. These results demonstrate the potential that polymerizable SOD mimetics may have for integration into medical devices for the minimization of inflammatory damage upon transplantation, such as during the delivery of encapsulated pancreatic islets.
Sol‐Gel/Polyelectrolyte Active Corrosion Protection System
Authors: Lamaka Svetlana V. , Shchukin Dmitry G. , Andreeva Daria V. , Zheludkevich Mikhail L. , Möhwald Helmuth , Ferreira Mario G. S.
Published: October 2008

This work presents a new type of feed‐back active coating with inhibitor‐containing reservoirs for corrosion protection of metallic substrates. The reservoirs are composed of stratified layers of oppositely charged polyelectrolytes deposited on AA2024 aluminum alloy coated with hybrid sol‐gel film. The layer‐by‐layer assembled polyelectrolyte film with the entrapped corrosion inhibitor is constructed by sequential spray‐coating deposition of water solutions of poly(ethyleneimine), poly(sodium styrenesulfonate) and 8‐hydroxyquiniline on the top of the sol‐gel coating. The active corrosion protection of AA2024 alloy coated with SiO2/ZrO2 sol‐gel film and modified by polyelectrolytes is demonstrated by electrochemical impedance spectroscopy and scanning vibrating electrode technique. The results obtained here show that polyelectrolyte films deposited atop of the hybrid sol‐gel coating on AA2024 alloy remarkably improve the long‐term protection performance providing additional “intelligent” anticorrosion effect that results from delivery of inhibiting species “on demand”. This becomes possible since the configuration of the polyelectrolyte molecules depends on the presence of H+ ions making the polyelectrolyte film sensitive to the pH of the surrounding solution. The source of local pH changes is the corrosion process starting in the micro‐ and nano‐defects leading to increased permeability of the polyelectrolyte reservoir and, consequently, to controllable release of entrapped inhibitor.
Optimal tuning of thermodynamic‐based decentralized PI control loops: Application to the Tennessee Eastman Process
Authors: Antelo Luis T. , Exler Oliver , Banga Julio R. , Alonso Antonio A.
Published: October 2008

The need of designing decentralized control loops emerges to ensure the global stability of a given process plant. To that purpose, it has been proposed in recent works a systematic approach to derive robust decentralized controllers, which is based on the link between thermodynamics and passivity theory, as well as on the fundamentals of process networks. This thermodynamic‐based control (TBC) methodology has several steps: (1) Decomposition of the considered process system into abstract mass and energy inventory networks; (2) design of conceptual mass and energy inventory control loops to guarantee the convergence of the states of the plant to a compact convex region defined by constant inventories, where input‐output stability follows; (3) definition of intensive variable control loops (if needed) to achieve global stability, and (4) realization of the conceptual inventory and intensive variable control loops over the available degrees of freedom in the system by using, for instance, PI controllers. A tool to tune these PI control loops is developed, based on the solution of a nonlinear programming optimization problem (NLP), in order to complete the proposed hierarchical and systematic TBC design. The aim is to minimize a given cost function, subject to both the system dynamics, as well as the linear and nonlinear constraints (no disturbances affecting the system are considered), where the vector of decision variables will be formed by the parameters of the PI controllers used in the defined decentralized control loops. We will test this tuning procedure in several control designs developed for the challenging benchmark of the Tennessee Eastman Process (TEP) by Ricker and Larsson et al., as well as in two TBC candidates, concluding that the best candidate among the proposed ones (in terms of final cost function) will be one of these TBC designs. For solving the NLP problem, two local (FMINCON and NOMADm) solvers, and a new global (MITS) one are used, comparing their performances. Finally, the dynamic analysis of the optimal tuned closed loop systems is carried out, finding that the presented TBC control candidates will be stable, while the other control structures considered exhibit complex dynamic behaviors or even instability when disturbances affecting the process are considered. © 2008 American Institute of Chemical Engineers AIChE J, 2008
Two fluid model using kinetic theory for modeling of one‐step hydrogen production gasifier
Authors: Yu Liang , Lu Jing , Zhang Xiangping , Zhang Suojiang , Wang Xiaoling
Published: October 2008

A Two Fluid Model (TFM) using kinetic theory of granular flow has been developed to describe an innovative process of hydrogen production in a single step. An extended Multi‐species of Solid Phase (MSP) method is proposed to simulate the gas‐solid heterogeneous reactions in an entrained flow gasifier, as opposed to Single‐species of Solid Phase (SSP) in previous studies. The intrinsic equations of methane steam reforming and water‐gas shift reactions are used for a good understanding of the reaction mechanism for high concentration of hydrogen production under higher pressure. On the basis of the results of computing, the main feature of core‐annular reaction zone is predicted in the fully developed flow region. And the similar flame‐like structure for velocity and temperature is observed to emerge from the feed injection zone at the bottom of gasifier. The model well illustrates the effects of CaO on enhancing the concentration of hydrogen and sequestering CO2 in the process of coal gasification. The advantages of pressure gasification are also shown that coal conversion increases with increasing pressure while H2S concentration and tar content decreases. Moreover, there is a steep increase in H2S and tar species initiated from the entrance of gasifier and then a decrease at the next section. The model shows good agreement with the measurements of flow field and gas products concentration in laboratory‐scale plants. © 2008 American Institute of Chemical Engineers AIChE J, 2008
Design and optimization of a hybrid distillation/melt crystallization process
Authors: Franke Meik Bernhard , Nowotny Norman , Ndocko Eugene Ndocko , Górak Andrzej , Strube Jochen
Published: October 2008

Hybrid distillation/melt crystallization processes are widely used for the separation of isomer mixtures. The design of a hybrid separation processes is not a trivial task because of several structural and operational degrees of freedom. In this article, a new three‐step design approach is proposed to address the above mentioned challenges. In the first step, process alternatives are generated by heuristic rules. In the second step, the generated process alternatives are optimized with respect to their energy consumption by using shortcut methods. In the third step, the most promising alternatives are rigorously optimized with respect to their total annualized costs, whereas the resulting mixed‐integer nonlinear programming (MINLP) problem is solved using a modified generalized benders decomposition (GBD) algorithm to take the nonconvexities into account. The feasibility of this design approach is demonstrated by design of a hybrid distillation/melt crystallization process for separation of a ternary isomer mixture. © 2008 American Institute of Chemical Engineers AIChE J, 2008
A two‐level distillation design method
Authors: Amale Amit , Lucia Angelo
Published: October 2008

Recently, Lucia et al. have used a distillation line method to develop the concept of shortest stripping line distance approach to minimum energy designs of distillation columns and multiunit processes. It is well known that distillation line methods can be very sensitive to specified product compositions. A two‐level distillation design procedure is proposed for finding portfolios of minimum energy designs when specifications are given in terms of key component recoveries. Thus, product compositions are not specified but calculated. It is shown that the proposed two‐level design procedure is flexible and can find minimum energy designs for both zeotropic and azeotropic distillations. It is also shown that the two‐level design method encompasses Underwood's solution but can find minimum energy designs when Underwood's method fails. Numerical results for several distillation examples involving ternary and quaternary mixtures are presented to support these claims, and geometric illustrations are used to elucidate key points. © 2008 American Institute of Chemical Engineers AIChE J, 2008
Cloning and characterization of the secreted hemocytic prophenoloxidases of Heliothis virescens
Authors: Shelby Kent S. , Popham Holly J. R.
Published: October 2008

The plasma enzyme phenoloxidase plays an important role in host resistance against viral, bacterial, fungal, filarial, and parasitoid challenge. Two Heliothis virescens prophenoloxidase transcripts, HvPPO‐1 and HvPPO‐2, were assembled from ESTs derived from a hemocyte cDNA library. The 2,363‐bp HvPPO‐1 contig encoded a 696–amino acid protein. The 3,255‐bp HvPPO‐2 contig encoded a 684–amino acid protein. Hemocyte and fat body transcript levels of HvPPO‐1 were slightly elevated by bacterial infection in 5th instar larvae; however, HvPPO‐2 expression was not significantly elevated above controls by bacterial infection. Per os infection of 4th instar larvae with the baculovirus Helicoverpa zea SNPV (HzSNPV) had a mild but significant suppressive effect upon fat body and hemocytic HvPPO‐1 expression when compared to expression in same‐aged controls. HvPPO‐2 expression levels in fat bodies and hemocytes from 4th instar larvae was not significantly altered by HzSNPV infection. HzSNPV infection of 5th instar larvae caused no significant alteration of HvPPO‐1 or of HvPPO‐2 expression in either fat bodies or hemocytes. Thus, even though prophenoloxidase subunits are constitutively expressed at high levels in larval H. virescens hemocytes and fat bodies, the subunit HvPPO‐1 is differentially regulated by bacterial and baculoviral infection. Arch. Insect Biochem. Physiol. 69:127‐142, 2008. © 2008 Wiley‐Liss, Inc.
Microwaves from UMTS/GSM mobile phones induce long‐lasting inhibition of 53BP1/γ‐H2AX DNA repair foci in human lymphocytes
Authors: Belyaev Igor Y. , Markovà Eva , Hillert Lena , Malmgren Lars O.G. , Persson Bertil R.R.
Published: October 2008

We have recently described frequency‐dependent effects of mobile phone microwaves (MWs) of global system for mobile communication (GSM) on human lymphocytes from persons reporting hypersensitivity to electromagnetic fields and healthy persons. Contrary to GSM, universal global telecommunications system (UMTS) mobile phones emit wide‐band MW signals. Hypothetically, UMTS MWs may result in higher biological effects compared to GSM signal because of eventual “effective” frequencies within the wideband. Here, we report for the first time that UMTS MWs affect chromatin and inhibit formation of DNA double‐strand breaks co‐localizing 53BP1/γ‐H2AX DNA repair foci in human lymphocytes from hypersensitive and healthy persons and confirm that effects of GSM MWs depend on carrier frequency. Remarkably, the effects of MWs on 53BP1/γ‐H2AX foci persisted up to 72 h following exposure of cells, even longer than the stress response following heat shock. The data are in line with the hypothesis that the type of signal, UMTS MWs, may have higher biological efficiency and possibly larger health risk effects compared to GSM radiation emissions. No significant differences in effects between groups of healthy and hypersensitive subjects were observed, except for the effects of UMTS MWs and GSM‐915 MHz MWs on the formation of the DNA repair foci, which were different for hypersensitive (P < 0.02[53BP1]//0.01[γ‐H2AX]) but not for control subjects (P > 0.05). The non‐parametric statistics used here did not indicate specificity of the differences revealed between the effects of GSM and UMTS MWs on cells from hypersensitive subjects and more data are needed to study the nature of these differences. Bioelectromagnetics 30:129–141, 2009. © 2008 Wiley‐Liss, Inc.
Effects of 60 Hz 14 µT magnetic field on the apoptosis of testicular germ cell in mice
Authors: Kim Yoon‐Won , Kim Hee‐Sung , Lee Jin‐Sang , Kim Young‐Jin , Lee Sang‐Kon , Seo Jae‐Nam , Jung Kyeong‐Cheon , Kim Nam , Gimm Youn‐Myoung
Published: October 2008

We recently reported that continuous exposure, for 8 weeks, of extremely low frequency (ELF) magnetic field (MF) of 0.1 or 0.5 mT might induce testicular germ cell apoptosis in BALB/c mice. In that report, the ELF MF exposure did not significantly affect the body weight or testicular weight, but significantly increased the incidence of testicular germ cell death. In the present study, we aimed to further characterize the effect of a 16‐week continuous exposure to ELF MF of 14 or 200 µT on testicular germ cell apoptosis in mice. There were no significant effects of MF on body weight and testosterone levels in mice. In TUNEL staining (In situ terminal deoxynucleotidyl transferase‐mediated deoxy‐UTP nick end labeling), germ cells showed a significantly higher apoptotic rate in exposed mice than in sham controls (P < 0.001). TUNEL‐positive cells were mainly spermatogonia. In an electron microscopic study, degenerating spermatogonia showed condensation of nuclear chromatin similar to apoptosis. These results indicate that apoptosis may be induced in spermatogenic cells in mice by continuous exposure to 60 Hz MF of 14 µT. Bioelectromagnetics 30:66–72, 2009. © 2008 Wiley‐Liss, Inc.
Effect of long term exposure to 0.5 T static magnetic fields on growth and size of GH3 cells
Authors: Rosen Arthur D. , Chastney Erin E.
Published: October 2008

Brief exposure to moderate intensity static magnetic fields has been shown to produce a transient alteration in physiological function in a variety of biological systems, primarily those related to changes in intracellular Ca2+. In the present study GH3 cells were cultured during continuous exposure to a 0.5 T field, for periods of up to 5 weeks. Following a 1‐week exposure, cell growth declined by 22% and returned to control levels in 1 week. This was not statistically significant but, with a 4‐week exposure, a statistically significant decline in growth of 51% was observed and return to control levels did not occur for 4 weeks. Cell diameter, on the other hand, significantly increased following 3 weeks of exposure and did not return to control levels for 3 weeks after termination of exposure. Ca2+‐dependent changes in the dynamic reorganization of the actin cytoskeleton are suggested as the probable explanation for these observations. Bioelectromagnetics 30:114–119, 2009. © 2008 Wiley‐Liss, Inc.
Die Unterinntaltrasse in der Bauausführung
Authors: Herdina Johann
Published: October 2008

Der 2,3 Mrd. Euro teure Abschnitt der zweigleisigen Zulaufstrecke zum Brennerbasistunnel im Unterinntal wird fast zur Gänze unterirdisch errichtet. Die seichte Lage der Tunnel in einem inneralpinen Tal führt dazu, dass bei der Bauausführung fast alle im Spezialtiefbau bekannten Verfahren zur Anwendung kommen. Diese werden sogar in Kombinationen verwendet, die weltweit noch nie zusammen eingesetzt wurden. Der Bericht gibt einen Einblick in die einzelnen Baulose dieses schwierigen 41 km langen Abschnitts der europäischen TEN Achse Nr.1 zwischen Berlin und Palermo.
Hinweise zum neuen DIN‐Fachbericht 102 – Betonbrücken, Ausgabe 2008 Teil 2
Authors: Haveresch Karlheinz , Maurer Reinhard
Published: October 2008

In Heft 8 von Beton‐ und Stahlbetonbau wurden wichtige neue Regelungen der bevorstehenden Neuausgabe von DIN‐Fachbericht 102 vorgestellt und erläutert. Dort wurden die Themenschwerpunkte:

– Schnittstelle Bauwerk und Baugrund

– Einwirkungen während der Bauzeit

– Schnittgrößen aus Zwang im Grenzzustand der Tragfähigkeit

– Besonderheiten von Brücken mit Kastenquerschnitten

– Bestimmung der Spaltzugbewehrung an Spanngliedverankerungen

– Behandlung von Spannverfahren

– Robustheitsbewehrung und

– Querkraftbemessung

behandelt.

Im vorliegenden Beitrag wird die Erläuterung des neuen DIN‐Fachberichts 102 zu weiteren Themenschwerpunkten fortgesetzt.
Language learning with interactive virtual agent scenarios and speech recognition: Lessons learned
Authors: Anderson James N. , Davidson Nancie , Morton Hazel , Jack Mervyn A.
Published: October 2008

The SPELL (Spoken Electronic Language Learning) system is a self‐access computer‐assisted language learning (CALL) package that integrates speaker‐independent continuous speech recognition technology with virtual worlds and embodied virtual agents to create an environment in which learners can converse in the target language within meaningful contextualized scenarios. In this paper we provide an overview of the functionality, architecture, and implementation of the SPELL system. We also describe four phases of usability evaluation conducted with the system and summarize the main results of these user assessments. Finally, we discuss the most significant lessons learned in the development and evaluation of the system. The paper focuses on the technological aspects of the system and its evaluation for usability and robustness, rather than its pedagogical methodology. Copyright © 2008 John Wiley & Sons, Ltd.
A Mitochondriotropic Derivative of Quercetin: A Strategy to Increase the Effectiveness of Polyphenols
Authors: Mattarei Andrea , Biasutto Lucia , Marotta Ester , De Marchi Umberto , Sassi Nicola , Garbisa Spiridione , Zoratti Mario , Paradisi Cristina
Published: October 2008

Mitochondria‐targeted compounds are needed to act on a variety of processes that take place in these subcellular organelles and that have great pathophysiological relevance. In particular, redox‐active molecules that are capable of homing in on mitochondria provide a tool to intervene on a major cellular source of reactive oxygen species and on the processes they induce, notably the mitochondrial permeability transition and cell death. We have linked the 3‐OH of quercetin (3,3′,4′,5,7‐pentahydroxy flavone), a model polyphenol, and the triphenylphosphonium moiety, a membrane‐permeant cationic group, to produce proof‐of‐principle mitochondriotropic quercetin derivatives. The remaining hydroxyls were sometimes acetylated to hinder metabolism and improve solubility. The new compounds accumulate in mitochondria in a transmembrane potential‐driven process and are only slowly metabolised by cultured human colon cells. They inhibit mitochondrial ATPase activity much as quercetin does, and are toxic for fast‐growing cells.
Direct Epoxidation in Candida antarctica Lipase B Studied by Experiment and Theory
Authors: Svedendahl Maria , Carlqvist Peter , Branneby Cecilia , Allnér Olof , Frise Anton , Hult Karl , Berglund Per , Brinck Tore
Published: October 2008

Candida antarctica lipase B (CALB) is a promiscuous serine hydrolase that, besides its native function, catalyzes different side reactions, such as direct epoxidation. A single‐point mutant of CALB demonstrated a direct epoxidation reaction mechanism for the epoxidation of α,β‐unsaturated aldehydes by hydrogen peroxide in aqueous and organic solution. Mutation of the catalytically active Ser105 to alanine made the previously assumed indirect epoxidation reaction mechanism impossible. Gibbs free energies, activation parameters, and substrate selectivities were determined both computationally and experimentally. The energetics and mechanism for the direct epoxidation in CALB Ser105Ala were investigated by density functional theory calculations, and it was demonstrated that the reaction proceeds through a two step‐mechanism with formation of an oxyanionic intermediate. The active‐site residue His224 functions as a general acid‐base catalyst with support from Asp187. Oxyanion stabilization is facilitated by two hydrogen bonds from Thr40.
Statistical methods for evaluating the linearity in assay validation
Authors: Hsieh Eric , Hsiao Chin‐fu , Liu Jen‐pei
Published: October 2008

One of the most important characteristics for evaluation of the accuracy in assay validation is the linearity. Kroll, et al. 1 proposed a method based on the average deviation from linearity (ADL) to evaluate the linearity. Hsieh and Liu 2 suggested that hypothesis for proving the linearity be formulated as the alternative hypothesis and proposed the corrected Kroll's method. However, the issue concerning the variability in estimation of the non‐centrality parameter is still unresolved. Consequently, the type I error rates may still be inflated for the corrected Kroll's method. To overcome this issue, we propose the sum of squares of deviations from linearity (SSDL) as an alternative metric for evaluation of linearity. Based on SSDL, we applied the method of generalized pivotal quantities (GPQ) for the inference of evaluation of linearity. The simulation studies were conducted to empirically investigate the size and power between current and proposed methods. The simulation results show that the proposed GPQ method not only adequately control size but also provide sufficient power than other methods. A numeric example illustrates the proposed methods. Copyright © 2008 John Wiley & Sons, Ltd.
Influence of benzylamine on the resolution of ibuprofen with (+)‐(R)‐phenylethylamine via supercritical fluid extraction
Authors: Molnár Péter , Bombicz Petra , Varga Csaba , Bereczki Laura , Székely Edit , Pokol György , Fogassy Elemér , Simándi Béla
Published: October 2008

The resolution of racemic ibuprofen was studied by partial diastereomer salt formation. The resolution was performed via two methods: resolution with (+)‐(R)‐phenylethylamine as chiral agent and resolution with a mixture of (+)‐(R)‐phenylethylamine and benzylamine. The diastereomers and unreacted enantiomers were separated by supercritical fluid extraction with carbon dioxide at 15 MPa and 33°C. The influence of the achiral benzylamine on the resolution efficiency was studied by varying the concentrations of the structurally related amines in their mixtures, keeping the sum molar ratio of the amines to racemic ibuprofen constant at 0.55 ± 0.02. The presence of benzylamine positively influenced the resolution efficiency at certain concentrations. The crystal structure of the salts of (+)‐(R)‐phenylethylamine with (−)‐(R)‐ibuprofen and (+)‐(S)‐ibuprofen, respectively, as well as the cocrystal of the benzylamine—ibuprofen salt with neutral ibuprofen molecules are presented. These structures were determined by single crystal X‐ray diffraction, proving the significantly different stoichiometry of the related amines with the chiral acid, in accordance with mass balance calculations. Chirality, 2008. © 2009 Wiley‐Liss, Inc.
African American and poor patients have a dramatically worse prognosis for head and neck cancer
Authors: Molina Manuel A. , Cheung Michael C. , Perez Eduardo A. , Byrne Margaret M. , Franceschi Dido , Moffat Frederick L. , Livingstone Alan S. , Goodwin W. Jarrard , Gutierrez Juan C. , Koniaris Leonidas G.
Published: October 2008

BACKGROUND.

Differences in cancer survival based on race, ethnicity, and socioeconomic status (SES) are a major issue. To identify points of intervention and improve survival, the authors sought to determine the impact of race, ethnicity, and socioeconomic status for patients with cancers of the head and neck (HN).

METHODS.

HN cancer patients diagnosed between 1998 and 2002 were examined using a linked Florida Cancer Data System and Florida Agency for Health Care Administration data set.

RESULTS.

A total of 20,915 patients with HN cancers were identified, predominantly in the oral cavity and larynx. Overall, 72% of patients were male, 89.7% were white, 8.4% were African American (AA), and 10.6% were Hispanic. The median survival time (MST) was 37 months. MST varied significantly by race (white, 40 months vs AA, 21 months; P < .001), sex (men, 36 months vs women, 41 months; P = .001), and area poverty level (lowest, 27 months vs highest, 34 months; P < .0001). Only 32% of AA patients underwent surgery in comparison with 45% of white patients (P < .001). On multivariate analysis, independent predictors of poorer outcomes were race, poverty, age, sex, tumor site, stage, grade, treatment modality, and a history of smoking and alcohol consumption.

CONCLUSIONS.

Carcinomas of the HN have an overall high mortality with a disproportionate impact on AA patients and the poor. Dramatic disparities by race and SES are not explained completely by demographics, comorbid conditions, or undertreatment. Earlier diagnosis and greater access to surgery and adjuvant therapies in these patients would likely yield significant improvement in outcomes. Cancer 2008. © 2008 American Cancer Society.