bluuebunny/crossref_metadata_2025 huggingface dataset:
Financing Infrastructure Projects through Public–Private Partnerships in India
Authors: Ramakrishnan T. S.
Published: January 2015

India has been suffering from a huge deficit in infrastructure facilities. The Indian government perceives the public–private partnership (PPP) model as the preferred mode to bridge this deficit and has initiated several measures in that regard. This paper discusses the basic aspects of PPP and how it works in India. Financing for infrastructure is one of the major issues. This paper explains various issues such as over-dependence on commercial banks for debts; inadequate financing from infrastructure finance companies; issues in external commercial borrowing; nonavailability of mezzanine financing; partial availability of insurance, pension, and provident funds; and nonfinancing issues that are plaguing infrastructure finance in India. The recent improvements such as infrastructure debt bonds, relaxed norms for external commercial borrowing, and reasonable exit options are also examined. The paper suggests various financial reforms that are needed for PPP financing in India such as tapping into savings, allowing foreign direct investment, increasing the cap on viability gap funding, allowing balloon payments, giving impetus for corporation bonds, and building infrastructure corpus.
U.S. Toll Roads since 1950
Authors: Davis Ronald W.
Published: January 2015

Recently there has been a trend among toll road agencies to index their tolls to inflation, giving rise to the question of how past tolls compared with inflation. To answer that question, a database including all toll roads in the United States since 1950 was developed. The database was used to analyze historical national average per mile toll rates for passenger cars and commercial vehicles and to compare these rates with rates of inflation. Historical toll road operation trends, including the annual number of agencies and centerline mileage since 1950, were also analyzed and discussed in the context of changing federal highway policies over time. To consider inflation from the perspective of drivers and toll agencies, the U.S. Bureau of Labor Statistics’ national-level all urban consumers consumer price index (CPI) and FHWA construction price indexes were used for comparison. It was found that considering typical published electronic or cash toll rates, the national average annual toll increase since 1960 was 3.2% for passenger cars and 3.6% for commercial vehicles. That result compares with an average annual national CPI increase of 4.0% and construction price increase of 3.8% in this period. While current national average toll rates remain significantly lower than the inflation rate, the gap has narrowed in recent years, especially considering commercial vehicle tolls and the drop in construction prices following the recent recession.
Robust Tolling Schemes for High-Occupancy Toll Facilities under Variable Demand
Authors: Gardner Lauren M. , Boyles Stephen D. , Bar-Gera Hillel , Tang Kelly
Published: January 2015

High-occupancy toll (HOT) lanes have become an increasingly prevalent form of congestion management pricing in the United States in the past few decades. The success of a HOT facility depends on the pricing scheme, which determines the utilization of the HOT lane, and the corresponding congestion relief on the parallel general purpose lanes. An additional complexity in determining HOT rates arises from the inevitable variability in travel demand inherent to transport networks. A successful tolling scheme must therefore be robust to changes in travel demand. Various tolling schemes for HOT facilities are examined in efforts to identify robust pricing policies. The expected performance and the corresponding variability of the facility are evaluated under each pricing scheme for different demand profiles. The focus is on noncorrelated demand uncertainties (i.e., number of arrivals during given time interval is independent of number of arrivals in preceding and following time intervals), which are modeled by considering the number of arrivals in each minute as an independent random variable with known distribution and time-of-day dependent mean. The performance model for a given demand realization is deterministic. Results show that a fixed toll can achieve about two-thirds of the benefit of an ideal HOT system. The performance of a prescheduled toll system is between the fixed toll and the ideal system: closer to the ideal when the coefficient of variation is below 40% and closer to the fixed toll otherwise. The performance of a relatively simple real-time system, with density-based linear adjustment to the prescheduled toll, is practically equivalent to that of the ideal system.
Economic Evaluation of Trends in Travel Time Reliability in Road Transport
Authors: Van Der Loop Han , Perdok Jan , Willigers Jasper
Published: January 2015

This study aimed to demonstrate that travel time reliability and road network robustness from the user's perspective could be measured with the use of detailed traffic data and according to a definition proposed by international experts. These measurements can be used to describe and explain the trend of travel time reliability and to describe the trend of extreme travel time delays (or nonrecurrent congestion). In the Netherlands, the trend of travel time unreliability increased until 2008 but was followed by a decline in subsequent years until 2011. Socio-economic factors, such as population growth and employment, appeared to be the underlying factors for the increase in travel time unreliability. Serving as a counterbalance were various transport policy measures, such as the addition of lanes, traffic management, and speed limitation and control, which were implemented primarily during the years 2009 to 2012. Finally, the study demonstrated how the volume of travel time reliability could be used as a component for the cost–benefit analyses of adding infrastructure and for calculating the social costs of travel time unreliability for users of the main trunk road network.
Analysis of Alternative to Kentucky Weight–Distance Tax
Authors: Martin Andrew , Bell Mark , Walton Jennifer
Published: January 2015

This study reviewed the existing literature on vehicle mileage taxes, details weight–distance tax repeal and replacement in other states, and provided a policy alternative to Kentucky's weight–distance tax. The authors developed a consolidation plan in which the International Registration Plan and intrastate license plate fees were increased by 129% and the weight–distance tax was eliminated. Revenue projections for the weight–distance tax and registration fees (for the current policy and its alternative) were compared to assess the impact on the state's road fund. In addition, the tax and fee liabilities for individual motor carriers were assessed to see whether the proposed changes would help or hurt firms of various sizes and operational tendencies. Interstate carriers that logged a high percentage of total miles on Kentucky roads or logged a low number of overall miles per vehicle would generally have seen an increased financial obligation to the state. Interstate carriers that logged a low percentage of total miles on Kentucky road or a high number of overall miles per vehicle would generally have seen a diminished financial obligation to the state. The vast majority of all intrastate carriers would have an increased financial obligation to the state under the proposed policy alternative. The study concluded with a discussion of the advantages and disadvantages of weight–distance tax elimination and replacement with a fee-based revenue structure.
Performance Predictions of Rutting for the National Center for Asphalt Technology Test Track
Authors: Lacroix Andrew , Kim Y. Richard
Published: January 2015

Performance-related specifications base pay rates on tests that measure and predict the performance of the mixture. This study evaluated several methods for predicting the rutting resistance of asphalt mixtures. The mixtures and field performance data came from the National Center for Asphalt Technology test track. The pavement sections evaluated were part of an experiment that focused on warm-mix asphalt, high-content reclaimed asphalt pavement (50%), and a combination of the two. One method involved using the dynamic moduli of the mixtures in confined and unconfined conditions. The ranking of the mixtures predicted from both conditions was good compared with the observed ranking from the track but was more reasonable with the confined data. These predictions were compared with common current tests such as the asphalt pavement analyzer and the Hamburg wheel tracker tests. From the ranking of rut depths, these tests did not appear able to distinguish subtler changes to material properties needed for a performance-related specification. Another method employed a viscoplastic shift model implemented within the layered viscoelastic continuum damage program to predict the rut depth. The predicted rut depths were biased 2.5 mm higher than those measured in the field when all three layers (175 mm) of asphalt were used to predict the rut depth, but the ranking matched the field quite well. The results from the top two layers (100 mm) of asphalt were less biased but were more variable than the three-layer results. The results suggest that all pavement layers should be evaluated for predicting rut depths, not just the top two layers.
Subgrade and Foundation Dynamic Performance Evaluation by Means of Lightweight Deflectometer Tests
Authors: Marradi Alessandro , Pinori Umberto , Betti Giacomo
Published: January 2015

Evaluation of the in situ bearing capacity of subgrade and foundation layers is carried out by means of enhanced dynamic testing devices such as the lightweight deflectometer (LWD). These devices offer many practical advantages over traditional plate load tests and allow simulation of real conditions of loads induced by heavy vehicle traffic. Devices provided with a load cell and a geophone can acquire load–deflection time histories, sampling data every 0.25 ms, with a high level of accuracy. LWD data are used mainly to calculate the surface modulus of the tested materials with the Boussinesq equation; procedures specifically developed for estimating the material compaction level achieved on-site are coming into use. This paper focuses on the use of the LWD for investigating the performance of subgrade and foundation layer materials for stiffness (bearing capacity) and compaction achieved. Great effort has been devoted to improving deflectometric tests, correlating energy loss (energy spent to deflect the tested surface, determined as the area enclosed by the load–deflection graph) to the performance of tested materials, especially for compaction level achieved on site. The influence of load frequency is evaluated and described. The results, obtained at two trial fields, confirm the reliability of the LWD in roadwork quality control and for a staged design approach to earthworks.
Influence of Aggregate Base Layer Variability on Pavement Performance
Authors: Titi Hani H. , Faheem Ahmed , Tabatabai Habib , Tutumluer Erol
Published: January 2015

The objective of this research was to investigate the variability of base layer construction in hot-mix asphalt (HMA) pavements and to assess the impact of base layer variability or nonuniformity on pavement performance. Subjective acceptance criteria of base layer construction may lead to variable pavement performance and may result in early pavement distresses and failure. Eleven existing HMA pavement projects with aggregate base course layers constructed in the past few years were selected for falling weight deflectometer (FWD) testing and visual distress surveys. In six of these projects, issues with aggregate base performance (stability and uniformity) had been observed and reported during paving of the HMA surface layer. Later, these pavements exhibited various levels of early distresses, including cracking (longitudinal, transverse, and alligator), aggregate base failure, and pavement surface roughness or irregularities (for ride quality). The remaining five HMA pavement projects, for which no issues related to aggregate base layer behavior were reported during construction, performed well after construction. A test section of approximately 1 mi on each project was subjected to FWD testing. The existing HMA pavements that showed early distresses exhibited high levels of spatial variability and nonuniformity in aggregate base course layers, as demonstrated by FWD testing and backcalculated base layer modulus values and distributions. The existing HMA pavements that performed well exhibited low levels of spatial variability and good uniformity in aggregate base course layers, as shown by the FWD test results and the backcalculated base layer modulus values and distributions.
Backcalculation of Asphalt Concrete Modulus Master Curve from Field-Measured Falling Weight Deflectometer Data
Authors: Zaabar Imen , Chatti Karim , Lee Hyung Suk , Lajnef Nizar
Published: January 2015

A new backcalculation program, DYNABACK-VE, was used to backcalculate pavement layer properties with field data. DYNABACK-VE used a time domain viscoelastic dynamic solution (ViscoWave-II) as a forward routine and a genetic algorithm for backcalculation analysis. The genetic algorithm search method was selected because it had a high potential for converging efficiently to a global solution. The forward solution used continuous integral transforms (Laplace and Hankel) that were more appropriate for transient, nonperiodic signals in the time domain. The algorithm was implemented in C++ and coded for parallel processing with multithreading for achieving better computational efficiency. Field falling weight deflectometer load and defection sensor time histories from three sites (Waverly Road near Lansing, Michigan, and two long-term pavement performance sections) were used for validation. The backcalculated asphalt concrete modulus master curves were compared with those obtained from laboratory testing. Very good agreement was obtained. The new algorithm was capable of backcalculating reliably the master curve of the asphalt concrete layer (four sigmoidal coefficients and two time-temperature shift factors), the elastic moduli for the unbound base or subbase and subgrade materials, and the modulus of stiff layer and the depth to stiff layer, if present. The advantage of the new solution is that it can analyze the response of pavement systems in the time domain and can therefore accommodate time-dependent layer properties and incorporate wave propagation. Also, because the backcalculation is performed in the time domain, the algorithm is not sensitive to truncation in the deflection time histories. This is a significant improvement to the state of the art, since truncation of deflection time histories has prevented frequency domain backcalculation solutions from being successful when measured field data are used.
Study of Cornering Maneuvers of a Pneumatic Tire on Asphalt Pavement Surfaces Using the Finite Element Method
Authors: Anupam K. , Srirangam S. K. , Scarpas A. , Kasbergen C. , Kane M.
Published: January 2015

Field experience shows that most road accidents that occur during turning maneuvers are caused by the loss of vehicle control. The loss of vehicle control is often related to a lack of sufficient friction between the tire and the pavement surface. In experiments and analytical studies, the overall antiskidding performance of a pneumatic tire has been observed to be affected by operating conditions, road texture, and surrounding temperatures. Interactions of these parameters create a complex relationship between their combined effect and the tire's ability to combat skidding. One way to analyze the cornering maneuvers of a vehicle is by means of a validated finite element tool that can carry both the tire and the pavement properties. Few computational studies have been conducted to study the cornering performance of a rolling pneumatic tire, and none of these studies included the role of pavement surface morphologies in their analysis. In this study, a thermomechanical framework was used to analyze the influence of temperature on cornering friction. The cornering friction coefficient was found to decrease with an increase in the loads and the speeds. The cornering friction coefficient was found to increase with an increase in inflation pressure, sideslip angle, and pavement surface texture depth. The proposed study contributes to an understanding of the cornering performance of passenger car tires.
Network Flow Solution Method for Optimal Evacuation Traffic Routing and Signal Control with Nonuniform Threat
Authors: Nassir Neema , Hickman Mark , Zheng Hong , Chiu Yi-Chang
Published: January 2015

An efficient two-stage network flow approach is proposed for the determination of optimal scenarios for integrated traffic routing and signal timing in the evacuation of real-sized urban networks with several threat zones, where the threat levels may be nonuniform across zones. The objective is to minimize total exposure to the threat (severity multiplied by duration) for all evacuees during the evacuation. In the problem formulation, traffic flow dynamics are based on the well-known point queue model in a time-expanded network representation. The proposed solution approach is adapted from a general relaxation-based decomposition method in a network flow formulation. The decomposition method is developed on the basis of insights into the optimal flow of traffic at intersections in the solution of the evacuation routing problem. As for efficiency, the computation time associated with the decomposition method for solving the integrated optimal routing and signal control problem is equivalent to the time required for solving the same optimal routing problem (without optimizing the intersection control plan) because the computation time required for determining the optimal signal control is negligible. The proposed solution method proves to be optimal. The method is implemented and applied to a real-sized evacuation scenario in the transportation network of Tucson, Arizona. The method is stress-tested with some inflated demand scenarios, and computation aspects are reported.
Accessibility of Low-Income Populations to Safe Zones during Localized Evacuations
Authors: Serulle Nayel Urena , Cirillo Cinzia
Published: January 2015

Access to transportation is of utmost importance for an evacuation, especially to the disadvantaged population. This study presents a simple yet revealing and practical tool for measuring the level of accessibility to so-called safe zones. Usually accessibility is reported on the basis of time, cost, or distance and does not account for the many other variables that influence travel behavior. This research bypassed those limitations by using results from the Maryland Statewide Transportation Model to take advantage of the log-sum measure. Flood and storm surge estimates, shelter and hospital locations, demographics, and other data were collected from official sources. Two locations in the Metropolitan Washington Council of Governments region were analyzed: the city of Frederick, Maryland, and the Anacostia neighborhood of Washington, D.C. Results suggest a positive correlation between income and accessibility. However, the results also reveal that factors such as location and vehicle ownership could greatly affect accessibility.
Modeling and Assessment of Crossing Elimination for No-Notice Evacuations
Authors: Jahangiri Arash , Murray-Tuite Pamela , Machiani Sahar Ghanipoor , Park Byungkyu (Brian) , Wolshon Brian
Published: January 2015

Crossing elimination is a relatively recent strategy that emergency managers and departments of transportation may consider during no-notice evacuations. In this strategy, certain intersection movements that may be permissible under normal operating conditions are prohibited so that arterial traffic flow will increase. A few previous studies examined this strategy with contraflow operations. However, the benefits of crossing elimination alone remain unclear. An assessment of the effects of intersection crossing elimination during evacuations helps fill this knowledge gap. A simulation–optimization model was developed to determine the near-optimal configuration of intersection movements from a set of pre-specified possible configurations for intersections in a given area. At the optimization level, the total travel time of evacuees was minimized, and at the lower level, all traffic was assigned to the network with DYNUST traffic assignment simulation software. A simulated annealing heuristic was used to solve the optimization problem. The entire method was applied to a real network to assess the impact of crossing elimination. Three scenarios were developed with combinations of evacuee destination and departure time distributions. Results for these scenarios indicated that total evacuee travel time was improved by about 3% to 5% (9,700 to 11,200 h for about 300,000 evacuees). The availability of through movements and the elimination of merging points were the two factors influencing the selection of modified configurations for intersection movement.
Use of Mobile Lidar Data to Assess Hurricane Damage and Visualize Community Vulnerability
Authors: Gong Jie , Maher Ali
Published: January 2015

Hurricane Sandy, the worst storm of its type to hit U.S. New York City and the state of New Jersey in generations, caused devastating damage to the region's infrastructure, properties, and businesses. Various technologies for the acquisition of geospatial information have been used since the landing of Hurricane Sandy to support critical decision making related to search and rescue, damage assessment, environmental risk analysis, debris removal, and rebuilding processes. The challenge is to match the best sensing method with the desired postdisaster applications. A large-scale application of mobile terrestrial laser scanning technology to posthurricane situations is described for the support of disaster recovery operations in the United States. Several innovative data analysis approaches for supporting damage assessment and flood resilience analysis are presented. Opportunities for and challenges presented by the use of mobile terrestrial laser scanning to support postdisaster recovery operations are discussed to highlight future research directions.
Kinetics of Diffusion-Controlled Adsorption of Adenine and Adenosine in a Carboxymethyl Diaminoethane Pvc-Mediated Column System
Authors: Ayar Ahmet
Published: January 2015

The adsorption kinetics of adenine and adenosine on a ligand-exchange matrix, carboxymethyl diaminoethane poly(vinyl chloride) in cobalt form (cobalt-CMEDA-PVC), have been studied in a fixed-bed column system. The initial ligand concentrations ranged between 1.25×10−5 and 2.0×10−4 mol L−1. The kinetic studies were carried out spectrophotometrically, in order to determine the ratecontrolling step of the adsorption. The kinetic data of the single-component systems were acquired from the breakthrough curves of the ligands on the basis of the equivalent points method. In this study, the homogeneous diffusion model was adapted to a fixed-bed column system to describe the differentiation in the ligand concentration of the effluent, beginning from breakthrough point as a function of time. The results obtained for the adsorption kinetics indicated that the diffusion step plays a significant role in the adsorption kinetics of the ligands, due to the fact that the adsorption performance was strongly affected by the initial concentration of ligands.
A Computational Study of the Mechanism and Kinetics for Gas-Phase Decomposition and Reactivity of the C4F9OCH2O Radical between 200 and 400 K
Authors: Reisi-Vanani Adel , Hoseinpour Sajedin
Published: January 2015

The decomposition processes and reactivity of C4F90CH2O• radical formed from C4F90CH3 (HFE-7100) have been studied by density function theory computational methods. All calculations were performed at B3LYP and mPW1PW91 levels of theory with the 6-311G(d,p) basis set. The calculated barrier heights were further improved by QCISD(T)/6-31G(d)//MP2/6-31G(d) methodology to obtain better rate constants. Five possible pathways were investigated: reaction with O2, reaction with OH radical, C-O bond dissociation, release of H radical and finally rearrangement of the radical and then C-O bond cleavage with energy barriers of 6.35 (6.09) [12.12], 12.85 (16.87) [7.51], 17.05 (21.77) [28.34], 20.3 (20.75) [18.13], 32.60 (31.50) [32.63] and 16.07 (18.73) [20.04] kcal mol−1, respectively (the values in the parentheses for mPW1PW91 and in the brackets for the QCISD(T) method). Rate constants were calculated by utilising canonical transition state theory in the temperature range of 200–400 K and 1 atm pressure, and Arrhenius diagrams were plotted. The results showed that H elimination and H abstraction pathways are dominant for degradation of C4F90CH2O• radical in the atmosphere. A smooth transition from the reactants to products on the corresponding potential energy surface was confirmed by intrinsic reaction coordinate calculations.
Mechanistic Investigation of the Electro-Oxidation of Catechols in the Presence of N-Methylbenzylamine at Room Temperature: Synthesis of New Quinone Derivatives
Authors: Asghari Alireza , Ameri Mohsen , Baraee Behzad , Rajabi Maryam , Bakherad Mohammad , Amoozadeh Ali
Published: January 2015

Electro-oxidation of catechol derivatives has been studied in the presence of N-methylbenzylamine as nucleophile in phosphate buffer (c=0.15 M, pH=7)/ethanol solution using cyclic voltammetry and controlled-potential coulometry (CPC). Voltammetric data indicate that a 1,4-Michael addition of N-methylbenzylamine from its NH group to the electrochemically derived o-quinone via an ECE mechanism has occurred. Moreover, the progress of coulometry confirmed our electrochemical mechanism. The electrochemical synthesis of quinone derivatives has been successfully accomplished using CPC in a two-compartment cell and the products were characterised by FTIR and NMR spectroscopy and elemental analysis.
Mechanistic and Electrochemical Investigation of Catechol Oxidation in the Presence of Thioacetamide: Application for Voltammetric Determination of Thioacetamide in Aqueous Media
Authors: Asghari Alireza , Ghaderi Omid , Rajabi Maryam , Ameri Mohsen , Amoozadeh Ali
Published: January 2015

Electrochemical oxidation of catechol has been studied in the presence of thioacetamide (TAM) in a phosphate buffer solution (0.2 mol L−1, pH=6.0) at the surface of glassy carbon electrode by means of cyclic voltammetry. After the cyclic voltammetric investigation of the reaction mechanism of TAM with catechol, TAM has been determinated by means of the differential pulse voltammetry technique. The results showed that the cathodic peak current of catechol reduced in the presence of various concentrations of TAM and that catechol can participate in a 1,4-Michael addition reaction with TAM under an EC mechanism. The decreasing of the cathodic current of catechol showed a linear relationship with the TAM concentration that can be used for the determination of TAM with a detection limit less than 3 μmol L−1.
Thermal Decomposition and Kinetic Studies of Solid Riboflavin using Model-Free Methods
Authors: Ahmad Naushad , Alam Manawwer , Al-Otaibi Meshary Ayad N.
Published: January 2015

The thermal stability and decomposition kinetics of riboflavin were investigated by nonisothermal thermogravimetric analysis (TGA) experiments in an inert atmosphere. For kinetic analysis, riboflavin was heated from room temperature to 800 °C with five different heating rates (5,10,15,20 and 30°C min−1). From the thermal decomposition process, it was found that there are two main stages of pyrolysis. In the DTG thermograms, the temperature peaks at maximum weight loss rate changed with varying heating rate. The kinetic parameters of decomposition including apparent activation energy ( Ea) and ln A (pre-exponential factor) under an inert atmosphere have been evaluated from the model-free isoconversion methods of Kissinger–Akahira–Sunose (KAS), Flynn–Wall–Ozawa (FWO) and Friedman over the whole temperature domain. It was found that values of Ea and ln A decrease with increasing conversion (α). The reaction order does not have a significant influence on the process because of the high value of the pre-exponential factor. The apparent activation energy distributions with conversion calculated by these methods ranged between 15.18 and 236.55 kJ mol−1, and varied over a broad range in a complex manner depending on the heating rate.
Kinetics of the Entire Methanol to Olefins Process over Sapo-34 Catalyst
Authors: Sun Shiyuan , Li Jianwei
Published: January 2015

The kinetics of the entire process of the SAPO-34 catalyst for the transformation of methanol into olefins in the 400–450 °C range has been established by using the experimental data obtained in an isothermal fixed bed reactor. The model considers the activity change of SAPO-34 zeolite with time on stream. The activity of the catalyst consists of two parts: the stabilisation activity (while methanol is fully transformed) and the deactivation activity (while methanol is not all transformed). According to the activity of the catalyst, this study measured the evolution of each olefin with time on stream respectively.
Effect of the Gas-Phase Reaction on Hydrogen Micro-Combustion in a Pt/Γ-Al2O3 Catalytic Plane Channel with Detailed Chemical Kinetic Mechanisms
Authors: Chen Junjie , Yan Longfei , Song Wenya
Published: January 2015

Hetero-/homogeneous micro-combustion of fuel-lean hydrogen–air mixtures in the plane channel containing a Pt/γ-Al2O3 catalyst washcoat was investigated numerically with detailed chemical kinetic mechanisms. The main theme of the paper is assessing the relative significance of the H2 gas-phase reaction as compared with catalytic reaction at different plane channel heights H, inlet mass fluxes J, and equivalence ratios ϕ in plane micro-channels. The numerical model of microcombustion was employed, which included detailed gas-phase and surface catalytic reaction mechanisms, heat transfer mechanisms, and diffusion of multicomponent species. In order to sustain micro-combustion of fuel-lean hydrogen–air mixtures over Pt/γ-Al2O3 in the range of operating conditions, the solid wall temperature of the micro-combustors was maintained at 1400 K. In plane micro-channels, as the channel dimension is decreased, the micro-combustion characteristics of hydrogen–air mixtures are significantly impacted due to radical and effective heat losses to the walls. However, the catalytic walls contribute to sustain the H2 gas-phase reaction in the micro-channels by decreasing heat losses to the walls due to the exothermic surface catalytic reaction, which also restrains the H2 gas-phase reaction by extracting radicals owing to typically high absorption rates of the above-mentioned species at the walls. Therefore, the detailed radical chain reaction mechanisms can be significantly changed by the presence of surface catalytic reaction (wall reaction), and the radical accumulation in the gas-phase can be restrained. In the present work, the effects of the above-mentioned three key parameters on the interaction between the surface catalytic and gas-phase reactions are discussed. For fuel-lean hydrogen–air mixtures, in each case, the limiting values of the plane channel height, inlet mass flux, and equivalence ratio beyond which the gas-phase reaction become negligible as compared with the surface catalytic reaction are explored. The computational results indicate that variation of the hydrogen–air inlet mass flux at constant inlet equivalence ratio and plane channel height alters the balance between the diffusive and convective mass fluxes. Finally, the equivalence ratio of the hydrogen–air mixtures significantly effects the contribution of the H2 gas-phase reactions to the entire H2 conversion.
Investigation of Solvent Effects on the Reaction of 1-Fluoro-2,4-Dinitrobenzene with Aniline in Molecular-Molecular and Ionic Liquid–Molecular Solvent Mixtures
Authors: Harifi-Mood Ali Reza , Faramarzi Farnaz , Mehrabi Yousef
Published: January 2015

The solvent effects on the reaction of 1-fluoro-2,4-dinitrobenzene with aniline was studied in various compositions of molecular-molecular solvent mixtures and molecular solvent-2-hydroxyethylammonium formate mixtures as media containing an ionic liquid. A mounting trend with the mole fraction of water in aqueous solution of alcohols up to a maximum at a mole fraction of 0.9 with respect to water was found, but a mild decrease with the mole fraction of ethyl acetate in methanol–ethyl acetate mixtures. A similar increasing trend was observed with increasing methanol, ethanol, 2-propanol and dimethylsulfoxide content in the mixtures containing the ionic liquid. Solvent effect investigations based on linear free energy relationship confirm that polarity has a major effect in molecular-molecular solvent mixtures, whereas polarity and hydrogen–bond acceptor ability were the dominant factors on reaction rate in molecular-ionic solvent mixtures. A nonlinear free energy relationship based on the preferential solvation hypothesis showed differences between the microsphere solvation of the solute and the bulk composition of the solvents. In these mixtures, the intermediate of the reaction was preferentially solvated by the ionic liquid.
Reviewers in this Issue Vol.4(3)
Authors: Editor The
Published: January 2015

DOI: http://dx.doi.org/10.3329/jemc.v4i3.21684 J Enam Med Col 2014; 4(3): 195
Provenancing Flower Bulbs by Analytical Fingerprinting: Convallaria Majalis
Authors: Van Ruth Saskia , De Visser Ries
Published: January 2015

The origin of agricultural products is gaining in appreciation while often hard to determine for various reasons. Geographical origin may be resolved using a combination of chemical and physical analytical technologies. In the present case of Lily of the Valley (Convallaria majalis) rhizomes, we investigated an exploratory set of material from The Netherlands, three other European (EU) countries and China. We show that the geographical origin is correlated to patterns of stable isotope ratios (isotope fingerprints) and volatile organic carbon (VOC) compounds (chemical fingerprints). These fingerprints allowed clear distinction using exploratory and supervised statistics. Isotope ratio mass spectrometry of 12C/13C, 14N/15N and 16O/18O isotopes separated materials from Europe and China successfully. The VOC patterns measured by Proton Transfer Reaction Mass Spectrometry (PTR-MS) allowed distinction of three groups: material from The Netherlands, the other EU countries and China. This knowledge is expected to help developing a systematic and efficient analytical tool for authenticating the origin of flower bulbs.
Immunreconstitution and Infectious Complications After Rituximab Treatment in Children and Adolescents: What Do We Know and What Can We Learn from Adults?
Authors: Worch Jennifer , Makarova Olga , Burkhardt Birgit
Published: January 2015

Rituximab, an anti CD20 monoclonal antibody, is widely used in the treatment of B-cell malignancies in adults and increasingly in pediatric patients. By depleting B-cells, rituximab interferes with humoral immunity. This review provides a comprehensive overview of immune reconstitution and infectious complications after rituximab treatment in children and adolescents. Immune reconstitution starts usually after six months with recovery to normal between nine to twelve months. Extended rituximab treatment results in a prolonged recovery of B-cells without an increase of clinically relevant infections. The kinetic of B-cell recovery is influenced by the concomitant chemotherapy and the underlying disease. Intensive B-NHL treatment such as high-dose chemotherapy followed by rituximab bears a risk for prolonged hypogammaglobulinemia. Overall transient alteration of immune reconstitution and infections after rituximab treatment are acceptable for children and adolescent without significant differences compared to adults. However, age related disparities in the kinetic of immune reconstitution and the definitive role of rituximab in the treatment for children and adolescents with B-cell malignancies need to be evaluated in prospective controlled clinical trials.
A New Telegrapher’s-Poisson System in Semiconductor Theory: A Singular Perturbation Approach
Authors: Rossani Alberto
Published: January 2015

In the theory of energy and momentum relaxation in semiconductor devices, the introduction of two temperatures and two mean velocities for electron and phonons is required. A new model, based on an asymptotic procedure for solving the kinetic equations of electrons and phonons is proposed, which naturally gives the displaced Maxwellian at the leading order. After that, balance equations for the electron number, energy densities and momentum densities are constructed, which constitute now a system of five equations for the chemical potential of electrons, the temperatures and the drift velocities. Moreover, Poisson’s equation is coupled, in order to calculate the self-consistent electric field. In Bloch’s approximation, we derive a telegrapher’s-Poisson system for the electron number density and the electric potential, which could allow simple semiconductor calculations, but still including wave propagation effects.
Finding Starting-Values for the Estimation of Vector STAR Models
Authors: Schleer Frauke
Published: January 2015

This paper focuses on finding starting-values for the estimation of Vector STAR models. Based on a Monte Carlo study, different procedures are evaluated. Their performance is assessed with respect to model fit and computational effort. I employ (i) grid search algorithms and (ii) heuristic optimization procedures, namely differential evolution, threshold accepting, and simulated annealing. In the equation-by-equation starting-value search approach the procedures achieve equally good results. Unless the errors are cross-correlated, equation-by-equation search followed by a derivative-based algorithm can handle such an optimization problem sufficiently well. This result holds also for higher-dimensional Vector STAR models with a slight edge for heuristic methods. For more complex Vector STAR models which require a multivariate search approach, simulated annealing and differential evolution outperform threshold accepting and the grid search.
Roll and Bank Estimation Using GPS/INS and Suspension Deflections
Authors: Brown Lowell , Bevly David
Published: January 2015

This article presents a method that provides an estimate of road bank by decoupling the vehicle roll due to the dynamics and the roll due to the road bank. Suspension deflection measurements were used to provide a measurement of the relative roll between the vehicle body frame and the axle frame or between the sprung mass and the unsprung mass, respectively. A deflection scaling parameter was found via suspension geometry and dynamic analysis. The relative roll measurement was then incorporated into two different kinematic navigation models based on extended Kalman filter (EKF) architectures. Each algorithm was tested and then verified on the Prowler ATV experimental platform at the National Center for Asphalt Technology (NCAT). Experimental data showed that both the cascaded and coupled approach performed well in providing estimates of the current vehicle roll and instantaneous road bank.
FT-IR Examination of the Development of Secondary Cell Wall in Cotton Fibers
Authors: Cintrón Michael , Hinchliffe Doug
Published: January 2015

The secondary cell wall development of cotton fibers harvested at 18, 20, 24, 28, 32, 36 and 40 days after flowering was examined using attenuated total reflection Fourier transform-infrared (ATR FT-IR) spectroscopy. Spectra of deuterated cotton fibers did not demonstrate significant changes in their O–H stretching band shapes or positions during development. Only a progressive increase in O–H band intensity was observed. Results indicate that the highly crystalline cellulose component produced during secondary cell wall formation maintains the hydrogen bonding network observed for the primary cell wall. Other general changes were observed for the regular ATR spectra. A progressive intensity increase for bands assigned to cellulose Iβ was observed during fiber development, including a marked intensity increase for vibrations at 1002 and 985 cm−1. In contrast, C–O vibrational bands from dominant conformations observed at 1104, 1052, 1028 cm−1 undergo a modest intensity increase during secondary cell wall development.
Correction: Wai, M.G.C., et al. A Review of Pinealectomy-Induced Melatonin-Deficient Animal Models for the Study of Etiopathogenesis of Adolescent Idiopathic Scoliosis. Int. J. Mol. Sci. 2014, 15, 16484–16499
Authors: Man Gene , Wang William , Yim Annie , Wong Jack , Ng Tzi , Lam Tsz , Lee Simon , Ng Bobby , Wang Chi , Qiu Yong , Cheng Jack
Published: January 2015

The authors wish to make the following corrections to this paper [1]: The first name and surname of the authors were reversed. It should be corrected in the following format (with the surname in bold text):[...]
Pacemaker Activity of the Human Sinoatrial Node: An Update on the Effects of Mutations in HCN4 on the Hyperpolarization-Activated Current
Authors: Verkerk Arie , Wilders Ronald
Published: January 2015

Since 2003, several loss-of-function mutations in the HCN4 gene, which encodes the HCN4 protein, have been associated with sinus node dysfunction. In human sinoatrial node (SAN), HCN4 is the most abundant of the four isoforms of the HCN family. Tetramers of HCN subunits constitute the ion channels that conduct the hyperpolarization-activated “funny” current (If), which plays an important modulating role in SAN pacemaker activity. Voltage-clamp experiments on HCN4 channels expressed in COS-7, CHO and HEK-293 cells, as well as in Xenopus oocytes have revealed changes in the expression and kinetics of mutant channels, but the extent to which especially the kinetic changes would affect If flowing during a human SAN action potential often remains unresolved. In our contribution to the Topical Collection on Human Single Nucleotide Polymorphisms and Disease Diagnostics, we provide an updated review of the mutation-induced changes in the expression and kinetics of HCN4 channels and provide an overview of their effects on If during the time course of a human SAN action potential, as assessed in simulated action potential clamp experiments. Future research may solve apparent inconsistencies between data from clinical studies and data from in vitro and in silico experiments.
Tapping Stem Cells to Target AMD: Challenges and Prospects
Authors: Brandl Caroline , Grassmann Felix , Riolfi Julia , Weber Bernhard
Published: January 2015

Human pluripotent stem cells (hPSCs) are increasingly gaining attention in biomedicine as valuable resources to establish patient-derived cell culture models of the cell type known to express the primary pathology. The idea of “a patient in a dish” aims at basic, but also clinical, applications with the promise to mimic individual genetic and metabolic complexities barely reflected in current invertebrate or vertebrate animal model systems. This may particularly be true for the inherited and complex diseases of the retina, as this tissue has anatomical and physiological aspects unique to the human eye. For example, the complex age-related macular degeneration (AMD), the leading cause of blindness in Western societies, can be attributed to a large number of genetic and individual factors with so far unclear modes of mutual interaction. Here, we review the current status and future prospects of utilizing hPSCs, specifically induced pluripotent stem cells (iPSCs), in basic and clinical AMD research, but also in assessing potential treatment options. We provide an outline of concepts for disease modelling and summarize ongoing and projected clinical trials for stem cell-based therapy in late-stage AMD.
Deformation Analysis of a Pneumatically-Activated Polydimethylsiloxane (PDMS) Membrane and Potential Micro-Pump Applications
Authors: Chiou Chi-Han , Yeh Tai-Yen , Lin Jr-Lung
Published: January 2015

This study presents a double-side diaphragm peristaltic pump for efficient medium transport without the unwanted backflow and the lagging effect of a diaphragm. A theoretical model was derived to predict the important parameter of the micropump, i.e., the motion of the valves at large deformations, for a variety of air pressures. Accordingly, we proposed an easy and robust design to fabricate a Polydimethylsiloxane (PDMS)-based micropump. The theoretical model agrees with a numerical model and experimental data for the deformations of the PDMS membrane. Furthermore, variations of the generated flow rate, including pneumatic frequencies, actuated air pressures, and operation modes were evaluated experimentally for the proposed micropumps. In future, the theoretical equation could provide the optimal parameters for the scientists working on the fabrication of the diaphragm peristaltic pump for applications of cell-culture.
Characterisation of Mediterranean Grape Pomace Seed and Skin Extracts: Polyphenolic Content and Antioxidant Activity
Authors: Ky Isabelle , Teissedre Pierre-Louis
Published: January 2015

Grape pomace seeds and skins from different Mediterranean varieties (Grenache [GRE], Syrah [SYR], Carignan [CAR], Mourvèdre [MOU] and Alicante [ALI]) were extracted using water and water/ethanol 70% in order to develop edible extracts (an aqueous extract [EAQ] and a 70% hydro-alcoholic extract [EA70]) for potential use in nutraceutical or cosmetic formulations. In this study, global content (total polyphenols, total anthocyanins and total tannins), flavan-3-ols and anthocyanins were assessed using HPLC-UV-Fluo-MSn. In addition, extract potential was evaluated by four different assays: Oxygen Radical Absorbance Capacity (ORAC), Ferric Reducing Antioxidant Potential assay (FRAP), Trolox equivalent antioxidant capacity (TEAC) or ABTS assay and 2,2-diphenyl-1-picrylhydrazyl (DPPH) radical scavenging assay. As expected, seed pomace extracts contained higher amounts of polyphenols then skin pomace extracts. Indeed, seeds from Syrah contained a particularly important amount of total polyphenols and tannins in both type of extract (up to 215.84 ± 1.47 mg of gallic acid equivalent [GAE]/g dry weight (DW) and 455.42 ± 1.84 mg/g DW, respectively). These extracts also expressed the highest antioxidant potential with every test. For skins, the maximum total phenolic was found in Alicante EAQ (196.71 ± 0.37 mg GAE/g DW) and in Syrah EA70 (224.92 ± 0.18 mg GAE/g DW). Results obtained in this article constitute a useful tool for the pre-selection of grape pomace seed and skin extracts for nutraceutical purposes.
A Facile Ionic Liquid Promoted Synthesis, Cholinesterase Inhibitory Activity and Molecular Modeling Study of Novel Highly Functionalized Spiropyrrolidines
Authors: Almansour Abdulrahman , Kumar Raju , Arumugam Natarajan , Basiri Alireza , Kia Yalda , Ali Mohamed , Farooq Mehvish , Murugaiyah Vikneswaran
Published: January 2015

A series of novel dimethoxyindanone embedded spiropyrrolidines were synthesized in ionic liquid, [bmim]Br and were evaluated for their inhibitory activities towards cholinesterases. Among the spiropyrrolidines, compound 4f exhibited the most potent activity with an IC50 value of 1.57 µM against acethylcholinesterase (AChE). Molecular docking simulation for the most active compound was employed with the aim of disclosing its binding mechanism to the active site of AChE receptor.