bluuebunny/crossref_metadata_2025 huggingface dataset:
Assessment of Models to Measure Pedestrian Activity at Signalized Intersections
Authors: Pulugurtha Srinivas S. , Repaka Sudha R.
Published: December 2008

The allocation of resources to build facilities amicable to pedestrians is governed by pedestrian activity at the location of interest. Collecting real-world data such as pedestrian counts at each point of interest is an expensive and time-consuming process. However, unlike trip generation models to estimate vehicle trips, the literature documents limited research to model and measure activity pertaining to pedestrian counts. The development and an assessment of models to measure pedestrian activity at signalized intersections are presented. Data collected at 176 signalized intersections in the city of Charlotte, North Carolina, are used to develop models to measure pedestrian activity by the time of day at signalized intersections. Pedestrian counts collected at the 176 intersections are used as a dependent variable. Factors such as demographic characteristics (population, household units), socioeconomic characteristics (income level, employment), land use characteristics (residential, commercial, industrial, etc.), network characteristics (number of approaches, number of lanes, speed limits, traffic volume, presence of medians), and the number of transit stops are extracted and estimated by using features available in a commercial geographic information system software program. These factors are used as independent variables. Multiple regression analysis through backward elimination of independent variables is used to develop the models. The developed models could be used by practitioners to measure pedestrian activity at a location if data are available. The measured pedestrian activity could be used in transportation planning, safety, and operational analyses.
Pedestrian Level-of-Service Model for Arterials
Authors: Petritsch Theodore A. , Landis Bruce W. , Huang Herman F. , Dowling Richard
Published: December 2008

NCHRP Project 3-70, Multimodal Level of Service Analysis for Urban Streets, is developing and testing a framework and enhanced methods for determining levels of service for the automobile, transit, bicycle, and pedestrian modes on urban streets. The proposed pedestrian level-of-service (LOS) model for arterials developed as part of NCHRP Project 3-70 is presented. This effort represents a progressive shift in evaluating the quality of service from a provider-based measure (how many vehicles or pedestrians can be moved and how fast) to a user-based measure (how well do drivers and pedestrians believe the facility meets their needs). To obtain feedback from potential pedestrian facility users, data for the model were obtained from participants in video simulation laboratories. The proposed model consists of a pedestrian density LOS and a pedestrian nondensity LOS. The density LOS is computed according to the methods provided in the Highway Capacity Manual. The nondensity LOS is a function of the pedestrian LOS of roadway segments, the pedestrian LOS of intersections, and the roadway crossing difficulty factor.
Stutter-Flash Light-Emitting-Diode Beacons to Increase Yielding to Pedestrians at Crosswalks
Authors: Van Houten Ron , Ellis Ralph , Marmolejo Erick
Published: December 2008

Motorists often fail to yield to pedestrians in marked multilane crosswalks at uncontrolled locations. Several studies have demonstrated that the use of advance yield markings along with a “Yield Here to Pedestrians” sign can reduce the incidence of multiple-threat crashes but have only a small effect on overall driver yielding behavior. A low-cost alternative to increase driver yielding is the use of amber light-emitting-diode (LED) flashers with an irregular flash pattern. As part of an FHWA cooperative agreement to evaluate intelligent transportation system treatments, amber LED flashers with an irregular flash pattern were installed at two multilane crosswalks in Miami–Dade County, Florida, in an experiment to increase yielding behavior. A reversal design was employed in this experiment to demonstrate experimental control at each site. This design involves alternating sessions with and without the devices activated. The results showed that the LED flashers installed on the pedestrian sign produced a marked increase in yielding behavior at both crosswalks and that similar data were collected from staged pedestrians and local residents using these crosswalks. Data also indicated that the use of the device produced a reduction in evasive conflicts between drivers and pedestrians at both sites and a reduction in the percentage of pedestrians trapped in the crosswalk at the center of a road without a median island. A second experiment evaluated the effects of illuminating the departure area with LED lighting when the system was activated at night. This treatment did not produce a further increase in yielding. The LED stutter-flash beacons likely overshadowed the effect of the pad lighting.
Influence of Pedestrian Traffic on Capacity of Right-Turning Movements at Signalized Intersections
Authors: Chen Xiao-ming , Shao Chun-fu , Hao Yue
Published: December 2008

Pedestrians have a significant influence on vehicle capacities of turning movements at signalized intersections. The increasing emphasis on pedestrian traffic has highlighted deficiencies in the relevant research in China. It is imperative to quantify accurately the effect of pedestrians on vehicle capacity to provide a basis for traffic operations and facility designs in mixed traffic conditions. This study proposes an analytical model for the capacity of right-turning movements influenced by pedestrians at signalized intersections. The model takes into account pedestrian behavior, pedestrian–vehicle conflict mechanisms, and pedestrian arrivals in platoons. The conflict-zone capacity is modeled on the basis of the conflict mechanism. The model was calibrated and used as the basis to calculate right-turn vehicle capacities. The capacities yielded by the proposed model depend strongly on the average conflict times. The results show that pedestrians have a strong impact on the right-turn capacities at low pedestrian volumes and that the effects of additional pedestrians decrease as the pedestrian volumes increase. VISSIM was employed to simulate the interactions between right turns and pedestrians to validate the model. A numerical example is presented to compare the proposed model with the simulations and several existing analytical models. At low pedestrian volumes, the predictions of the other methods are approximately equal; at high pedestrian volumes, the models assuming pedestrian priority yield lower capacities than those assuming no priority.
Segway Rider Behavior
Authors: Miller Sheryl , Molino John A. , Kennedy Jason F. , Emo Amanda K. , Do Ann
Published: December 2008

The Segway Human Transporter is becoming more prevalent on urban sidewalks. This experiment investigated the approach speed and passing clearance that Segway devices exhibit on encountering a variety of obstacles on the sidewalk. The experiment was conducted with a sample of 20 Segway operators: 10 experienced operators and 10 novices. For the given experimental course and procedures, the results of the study revealed that ( a) Segway riders approach obstacles at a mean speed of about 4.5 mph (7.2 km/h) with a range from 2.7 mph (4.3 km/h) to 6.8 mph (10.9 km/h); ( b) Segway riders pass obstacles with a mean clearance of about 14.5 in. (36.7 cm) with a range from 3.3 in. (8.4 cm) to 43.2 in. (110 cm); ( c) Segway riders pass moving pedestrians at an average speed of about 5 mph (8.1 km/h) and with an average clearance of 35.9 in. (91.2 cm); ( d) Segway riders pass obstacles more slowly by about 0.5 mph (0.8 km/h) on average and closer by about 17.6 in. (44.7 cm) on average on a narrow as opposed to a wide sidewalk; and ( e) experienced Segway riders pass faster by about 1.9 mph (3.1 km/h) on average than do novice riders. In the current experiment, the average passing event involving a Segway rider and a pedestrian required a minimum total distance of approximately 7.0 ft (2.1 m). These data should assist engineers in calculating the impact of various mixes of Segway traffic on sidewalks.
Understanding and Mapping Institutional Impediments to Walking and Bicycling to School
Authors: Steiner Ruth L. , Bejleri Ilir , Wheelock Jennifer L. , Boles Gene , Cahill Maria , Perez Benito O.
Published: December 2008

The Safe, Accountable, Flexible, Efficient Transportation Equity Act: A Legacy for Users (SAFETEA-LU) legislation calls for the establishment of a Safe Routes to School program in each state that is funded for the five fiscal years from 2005 through 2009. States are required to spend between 70% and 90% for infrastructure and between 10% and 30% on noninfrastructure programs. For each of these components of the program to be successful, the built environment of the community surrounding the school needs to support all modes of travel. Much of the emphasis in Safe Routes to School programs has focused on increasing walking in neighborhoods with the characteristics that support walking, such as high-density residential areas close to schools and connected grid and pedestrian amenities. Using Hillsborough County, Florida, as a case study, this paper focuses on barriers to walking and bicycling to school by examining how decisions about school siting, school attendance boundaries, street network characteristics, and other factors controlled by local governments and school boards affect the potential for children to walk to school.
Evaluation of Effectiveness of School Zone Flashers in North Carolina
Authors: Simpson Carrie L.
Published: December 2008

The North Carolina Department of Transportation has been placing flashing beacons on school zone signs where warranted in an attempt to provide more awareness of the school zone speed limit and at the request of schools. The purpose of this project was to evaluate the effectiveness of placing flashing beacons on school zone speed limit signs and to determine if speed compliance was improved in school zones. A sample set of 15 treatment school zones with flashers and 15 comparison school zones without flashers was selected for analysis throughout North Carolina. Sites were selected to include a mix of geometric features and geographic elements. Flashers had been installed at each of the sites for at least 3 years. The school-time speed limits at all sites ranged between 25 and 45 mph. Speed data were collected at all sites during the reduced-speed school zone hours of operation (school time) and outside the reduced-speed school zone hours of operation (nonschool time). Several different measures of effectiveness were calculated to compare the characteristics of the speed distributions, including the percentage of vehicles exceeding the speed limit, average speed, 85th percentile speed, and pace speed. Results showed no practical difference in vehicle speeds between the flasher and nonflasher locations during school-time hours. Although vehicle speeds did decrease from nonschool-time hours to school-time hours at both flasher and nonflasher sites, the speed reductions were not enough to bring drivers into compliance with the school-time speed limit. Both locations with and without flashers had an extremely low compliance rate with the school-time speed limit.
Urban Bicyclists
Authors: Delmelle Elizabeth Cahill , Thill Jean-Claude
Published: December 2008

As issues related to oil dependency, rising gas prices, and global warming come to the forefront of topics of concern for Americans, the need for alternative modes of transportation has become critical. Urban settings are seemingly ideal for bicycling to become a significant mode, given the greater compactness of destinations. However, in the United States, bicycling is both scarcely used and very dangerous, as bicyclists are 12 times more likely to be killed than automobile drivers. The purpose of this research is to gain greater insights into the geographic dimensions of traffic crash intensity that bicyclists may experience in American cities. Bicycle crashes are studied in Buffalo, New York, for the years 2003 and 2004. The geographic distribution of crashes is determined and compared for both youth and adult bicyclists and factors of crash hazard intensity are statistically identified. Density of development and physical road characteristics such as roadway and intersection functional class are examined, as well as socioeconomic and demographic variables and potential trip attractors. Given the spatial nature of these variables, a spatially weighted regression model is incorporated to account for spatial dependencies of the dependent variables and of their model residuals. The results of the analysis indicate clear distinctions between youth and adult bicycle crashes, both in terms of the neighborhoods where victims reside and in terms of the neighborhoods where these two demographic groups are found to be more frequently involved in a crash with a motorized vehicle.
The Applicability of Space Syntax to Bicycle Facility Planning
Authors: McCahill Chris , Garrick Norman W.
Published: December 2008

With the emergence of bicycles as an increasingly viable form of urban transportation comes the need for improved design and planning tools. Existing methods for evaluating bicycle facilities and for prioritizing their construction and maintenance are reviewed. Two components are necessary for such an analysis: one for assessing the quality of the segments that make up the network, and one for assessing the overall network itself. Space syntax analysis is evaluated as a tool for network assessment on the basis of its potential to predict patterns of travel over different network configurations. The theory behind space syntax is evaluated and then tested by using data from the city of Cambridge, Massachusetts. A good model for predicting bicycle volumes within a network can be constructed by using only census data and the space syntax measure “choice.” Unlike existing bicycle suitability measures, space syntax describes the importance of segments to the connectivity or completeness of the network.
Fifty Years of Bicycle Policy in Davis, California
Authors: Buehler Ted , Handy Susan
Published: December 2008

Davis, California, has long been known as the bicycle capital of the United States. In the 1960s, citizens lobbied for bike lanes to make bike travel safer. After 2 years of lobbying and 1 year of engineering, Davis created the first bike lanes in postwar America. After 1967, transportation in Davis was oriented toward the bicycle. The city's Public Works Department staff developed many innovative designs and programs that were fine-tuned in Davis and then exported elsewhere. The university and city worked together on engineering, education, enforcement, and encouragement efforts. In the 1980s, greenways were added to the system. Davis now has 50 mi of bike lanes and 50 mi of off-street paths in a 10-square-mi city, making a highly functional bicycle transportation system. However, bicycling levels have decreased since 1990, falling from 28% of work trips in 1980 to 14% in 2000. City and University of California, Davis, staff attribute this to changing demographics, intercity commuting, and increased transit. In addition, during this time, bicycle programs have contracted and infrastructure expansion has slowed. Application of theories of public policy change suggest that the advocacy efforts in the 1960s led to a policy shift emphasizing bicycling that continued through the mid-1990s, when most programs had dwindled or disappeared. In the future, a resurgence in advocacy might reverse the deterioration of bicycle programs and result in increased bicycle use by Davis residents.
Cycling for Everyone
Authors: Pucher John , Buehler Ralph
Published: December 2008

This paper investigates how bicycling can be promoted as a safe and feasible means of transport for everyone and for all trip purposes. The policies and programs needed to encourage a broad spectrum of social groups to cycle are the same policies and programs that encourage high overall levels of cycling: extensive systems of separate cycling facilities, intersection modifications and priority bicycle traffic signals, traffic calming of neighborhoods, safe and convenient bike parking, coordination and integration of cycling with public transport, traffic education and training for both cyclists and motorists, and traffic laws that favor cyclists and pedestrians. To show how this multifaceted, coordinated approach actually works, the paper focuses on cycling trends and policies in the Netherlands, Denmark, and Germany. The national-level comparative analysis is supplemented with case studies of large and small cities in each country.
Motor Scooters and Mopeds
Authors: Haworth Narelle , Nielson Angela
Published: December 2008

Little is known about the crash involvement of scooters and mopeds and whether they are safer than other motorcycles. Difficulties in defining motor scooters and mopeds and identifying them in crash and other databases have hindered research. This paper reviews recent research and analyzes the nature and extent of moped and motorcycle crashes in the State of Queensland, Australia. Analyses of merged crash and registration data found that the number of moped crashes increased from 25 in 2001 to 97 in 2005. Most crashes resulted in hospitalization (43%) or medical treatment (38%) and occurred between 6 a.m. and 6 p.m. on weekdays in low-speed areas. Overall, 50.8% of crashes occurred at intersections and 32.3% were single-vehicle crashes. The most common crash types were collisions between vehicles traveling in the same direction (24.8%), loss of control on a straight road (23.1%), and collisions between the moped and another vehicle on an adjacent approach to an intersection (18.2%). The ratio of motorcycle to moped crashes was about 19:1, but moped crashes increased at a greater rate during 2001–2005 (260% versus 71%). The distributions of crash severity were similar. Moped crashes more often involved loss of control on a straight road (23.1% versus 12.7%), while motorcycle crashes more often involved loss of control on a curve (13.6% versus 5.0%). Moped riders in crashes were much more likely than motorcycle riders to be female (37.9% versus 7.2%) and younger and hold an interstate (10.8% versus 1.3%) or overseas (7.8% versus 0.7%) license. The interpretation of these data and their implications for licensing and other countermeasures are discussed.
Comparison between Powered Two-Wheeler and Passenger Car Free-Flow Speeds in Urban Areas
Authors: Perco Paolo
Published: December 2008

Accident data indicate that motorcyclists are a particularly vulnerable group of road users because they run a higher risk of being injured or killed in an accident than passenger car drivers. One of the countermeasures that can improve traffic safety for motorcyclists is an increase in awareness and knowledge about powered two-wheelers (PTWs) in the planning, construction, operation, and maintenance of new and existing roads. Road design standards and policies that regulate design process and safety evaluations are usually based on passenger car characteristics only. In particular, the passenger car operating speed is used as the critical input for design choices of geometric elements connected with traffic safety and as a performance measure to evaluate road design and consistency. Because the passenger car operating speed might not be representative of the PTW operating speed, this study compared the PTW and passenger car speed distributions in urban areas to establish definitively whether they are similar. The results showed that PTW speeds are always considerably higher than passenger car speeds and that the corresponding operating speeds are correlated. Therefore, a prediction equation to estimate the PTW operating speed starting from passenger car operating speed was developed for urban streets. This equation can help highway engineers to estimate expected PTW speeds that can be effectively used in the safety evaluations of new and existing roads where the significant presence of PTWs in the traffic flow suggests that this vehicle type should be considered.
Radiation- and Photo-induced Activation of 5-Fluorouracil Prodrugs as a Strategy for the Selective Treatment of Solid Tumors
Authors: Ito Takeo , Tanabe Kazuhito , Yamada Hisatsugu , Hatta Hiroshi , Nishimoto Sei-ichi
Published: December 2008

5-Fluorouracil (5-FU) is used widely as an anticancer drug to treat solid cancers, such as colon, breast, rectal, and pancreatic cancers, although its clinical application is limited because 5-FU has gastrointestinal and hematological toxicity. Many groups are searching for prodrugs with functions that are tumor selective in their delivery and can be activated to improve the clinical utility of 5-FU as an important cancer chemotherapeutic agent. UV and ionizing radiation can cause chemical reactions in a localized area of the body, and these have been applied in the development of site-specific drug activation and sensitization. In this review, we describe recent progress in the development of novel 5-FU prodrugs that are activated site specifically by UV light and ionizing radiation in the tumor microenvironment. We also discuss the chemical mechanisms underlying this activation.
Discovery of a Novel CCR5 Antagonist Lead Compound Through Fragment Assembly
Authors: Liu Yanqing , Zhou Enkun , Yu Kunqian , Zhu Jin , Zhang Yu , Xie Xin , Li Jian , Jiang Hualiang
Published: December 2008

CCR5, as the major co-receptor for HIV-1 entry, is an attractive novel target for the pharmaceutical industry in the HIV-1 therapeutic area. In this study, based on the structures of maraviroc and 1,4-bis(4-(7-chloroquinolin-4-yl)piperazin-1-yl)butane-1,4-dione (1), which was identified using structure-based virtual screening in conjunction with a calcium mobilization assay, a series of novel small molecule CCR5 antagonists have been designed and synthesized through fragment assembly. Preliminary SARs were obtained, which are in good agreement with the molecular binding model and should prove helpful for future antagonist design. The novel scaffold presented here might also be useful in the development of maraviroc-derived second generation CCR5 antagonists.
Organocatalytic Oxidative Dehydrogenation of Dihydroarenes by Dioxygen Using 2,3-Dichloro-5,6-dicyano-benzoquinone (DDQ) and NaNO2
Authors: Zhang Wei , Ma Hong , Zhou Lipeng , Sun Zhiqiang , Du Zhongtian , Miao Hong , Xu Jie
Published: December 2008

The oxidative dehydrogenation of dihydroarenes catalyzed by 2,3-dichloro-5,6-dicyano-benzoquinone(DDQ) and NaNO2 with dioxygen is reported. The combination of DDQ and NaNO2 showed high efficiency and high selectivity, compared with other benzoquinones and anthraquinones, e.g., >99% conversion of 9,10-dihydroanthracene with 99% selectivity for anthracene can be obtained at 120 °C under 1.3 MPa O2 for 8 h. Excellent results were achieved in the oxidative dehydrogenation of variety of dihydroarenes.
The Metabolism of Anammox
Authors: Kartal Boran , Keltjens Jan T , Jetten Mike SM
Published: December 2008

Anaerobic ammonium‐oxidizing (anammox) bacteria derive their energy for growth from the conversion of ammonium and nitrite into dinitrogen gas. The bacteria are the latest addition to the biogeochemical nitrogen cycle. The slowly growing micro‐organisms that belong to the Planctomycetes are characterized by a compartmentalized cell architecture featuring a central cell organelle, the ‘anammoxosome’. Membrane systems surrounding the different cellular compartments are composed of unique ‘ladderane’ lipid molecules. Although the metabolism has not been completely resolved, nitrogen formation seems to involve the intermediary formation of hydrazine, a most reactive and toxic compound. Anammox bacteria have been detected in many oxygen‐limited freshwater and marine ecosystems investigated. In the marine environment, over 50% of the nitrogen gas released is made by anammox bacteria. Application of the anammox process offers an attractive alternative to current wastewater treatment systems for the removal of fixed nitrogen.

Key concepts

Ammonium is converted under anaerobic conditions into dinitrogen gas by a newly discovered and specialized group of micro‐organisms, the anammox bacteria.

Anammox bacteria are chemolithoautotrophic organisms that gain their energy for growth from the conversion of the inorganic substrates ammonium and nitrite. Cell carbon is derived from carbon dioxide.

Anammox bacteria are characterised by a unique cell plan featuring a central cell organelle, the anammoxosome.

The lipids from anammox bacteria are composed of highly unusual ‘ladderane’ molecules.

The conversion of ammonium and nitrite into dinitrogen gas proceeds through the intermediary formation of the toxic and highly reactive hydrazine.

Anammox bacteria synthesize adenosine triphosphate (ATP) by an electrochemical proton gradient most likely established across the anammoxosome membrane.

In nature approximately 50% of the dinitrogen gas released into the atmosphere is made by anammox bacteria.

Anammox bacteria offer an economically attractive and environmentally friendly alternative to current wastewater treatment processes for the removal of fixed nitrogen.
Single Molecule Detection, Analysis, and Manipulation
Authors: Walter Nils G.
Published: December 2008

Single molecule detection represents the ultimate goal in analytical chemistry. Both confocal and wide‐field microscopes are now widely used to detect, analyze, and manipulate single molecules in samples ranging in complexity from controlled in vitro conditions to the inside of living cells. Conformational rearrangements and chemical reactions of single molecules can be monitored in real time to detect rare and/or short‐lived intermediates and molecular heterogeneity. The molecular motion of single molecules or particles can be followed at high temporal and spatial resolution. Individual molecules can be repeatedly manipulated and their mechanical properties measured using calibrated forces. The current status of the analytical chemistry of single molecules is surveyed here, including fluorescence microscopy, optical tweezers, and atomic force microscopy (AFM).
Design and Fabrication of Magnetically Functionalized Core/Shell Microspheres for Smart Drug Delivery
Authors: Gong Xiuqing , Peng Suili , Wen Weijia , Sheng Ping , Li Weihua
Published: December 2008

The fabrication of magnetically functionalized core/shell microspheres by using the microfluidic flow‐focusing (MFF) approach is reported. The shell of each microsphere is embedded with magnetic nanoparticles, thereby enabling the microspheres to deform under an applied magnetic field. By encapsulating a drug, for example, aspirin, inside the microspheres, the drug release of the microspheres is enhanced under the compression–extension oscillations that are induced by an AC magnetic field. This active pumping mode of drug release can be controlled by varying the frequency and magnitude of the applied magnetic field as well as the time profile of the magnetic field. UV absorption measurements of cumulative aspirin release are carried out to determine the influence of these factors. The drug release behavior is found to be significantly different depending on whether the applied field varies sinusoidally or in a step‐function manner with time.
Von Economo Neurons in the Elephant Brain
Authors: Hakeem Atiya Y. , Sherwood Chet C. , Bonar Christopher J. , Butti Camilla , Hof Patrick R. , Allman John M.
Published: December 2008

Von Economo neurons (VENs), previously found in humans, all of the great ape species, and four cetacean species, are also present in African and Indian elephants. The VENs in the elephant are primarily found in similar locations to those in the other species. They are most abundant in the frontoinsular cortex (area FI) and are also present at lower density in the anterior cingulate cortex. Additionally, they are found in a dorsolateral prefrontal area and less abundantly in the region of the frontal pole. The VEN morphology appears to have arisen independently in hominids, cetaceans, and elephants, and may reflect a specialization for the rapid transmission of crucial social information in very large brains. Anat Rec 2009. © 2008 Wiley‐Liss, Inc.
Ultrastructural Morphology and Morphometry of Phrenic Nerve in Rats
Authors: Fazan Valéria Paula Sassoli , Rodrigues Filho Omar Andrade , Jordão Caroline Echavarria Rodrigues , Moore Kenneth Charles
Published: December 2008

Despite numerous literature reports on the morphometry of the myelinated fibers of phrenic nerves in rats, a systematic study of the longitudinal and lateral symmetry of the unmyelinated fibers morphometry is not available. In this study, we have undertaken ultrastructural and morphometric studies of the phrenic nerve in adult rats, assessing two different levels (proximal and distal) from both right and left sides. Phrenic nerves of adult male Wistar rats were prepared for epoxy resin embedding and transmission electron microscopy. Morphometric analysis was performed with the aid of computer software, which took into consideration the unmyelinated fiber number, density, area, and diameter, as well as ratio between myelinated and unmyelinated fibers, and the percentage of the fascicular area occupied by the myelinated and unmyelinated fibers. Comparison of data from proximal and distal segments on the same side and from the same levels between sides was performed. Differences were considered significant when P < 0.05. The most important finding is that morphometric parameters of the phrenic nerve unmyelinated fibers in adult rats are both longitudinally and laterally symmetric. This study adds important morphometric information about the unmyelinated fibers of the phrenic nerves in adult rats for proximal and distal levels on both sides of the animal. Anat Rec 2009. © 2008 Wiley‐Liss, Inc.
Aero‐hygrothermisches Verhalten von Umfassungskonstruktionen mit Hohlräumen
Authors: Gnoth Steffen , Hansel Frank , Häupl Peter , Fechner Heiko
Published: December 2008

Die vorliegende Arbeit leistet einen Beitrag zur gekoppelten aero‐hygrothermischen Bauteilsimulation für Strukturen mit Hohlräumen. Den Schwerpunkt bildet dabei die Entwicklung eines CaFD‐Modells (Cavity Fluid Dynamics) und Computercodes, welche auf der Lösung der Navier‐Stokes‐Gleichungen für laminare Strömungen inkompressibler reibungsbehafteter Fluide basieren. Mit der Definition einer Softwareschnittstelle gelingt es, den zunächst eigenständig ausführbaren Strömungslöser CaFD‐Tool in Form einer dynamischen Bibliothek in den Quellcode der am Institut für Bauklimatik der Technischen Universität Dresden entwickelten Software DELPHIN 4 einzubinden. Mit der Formulierung eines vereinfachten Mehr‐Zonen‐Modells ist es möglich, die bei einem durchströmten Hohlraum oder Spalt auftretende Überlagerung von natürlicher und erzwungener Konvektion zu simulieren. Außerdem können die Feuchtefelder, verursacht durch Kondensationserscheinungen der eindringenden feucht‐warmen Raumluft im Hohlraum und im angrenzenden Baustoff quantifiziert werden. Neben der exakten energetischen Beurteilung der Bauteile lassen sich Möglichkeiten zur Vermeidung von Feuchteschäden aufzeigen.
Host and Non‐Host Plant Response to Bacterial Wilt in Potato: Role of the Lipopolysaccharide Isolated from Ralstonia solanacearum and Molecular Analysis of Plant–Pathogen Interaction
Authors: Esposito Nunzio , Ovchinnikova Olga G. , Barone Amalia , Zoina Astolfo , Holst Otto , Evidente Antonio
Published: December 2008

Ralstonia solanacearum is one of the most devastating phytopathogenic bacteria, in particular its race 3. This microorganism is the causal agent of destructive diseases of different crops including tomato and potato. An important aspect of the interaction between this pathogen, and the host and non‐host plants was its biochemical and molecular basis. Thus, the lipopolysaccharides (LPS) were extracted from the R. solanacearum cell wall, purified, and the O‐specific polysaccharide (OPS) was isolated and chemically characterized by compositional analyses and NMR spectroscopy. The OPS was constituted of two linear polymers of an approximate ratio of 3 : 1, both of which were built up from three rhamnose and one N‐acetylglucosamine residues and differed only in the substitution of one rhamnose residue. The LPS inhibited the hypersensitivity reaction (HR) in non‐host tobacco plants and induced localized resistance in host potato plants, both of which were pre‐treated with the LPS before being inoculated with the pathogen. A cDNA‐AFLP approach was used to study transcriptome variation during the resistant and susceptible interactions. This revealed the presence of metabolites specifically expressed in the S. commersonii‐resistant genotypes, which could be involved in the plant–pathogen incompatible reaction. Furthermore, a specific EST collection of the Ralstonia–potato interaction has been built up.
Antimycobacterial Butanolides from the Root of Lindera akoensis
Authors: Chang Su‐Yen , Cheng Ming‐Jen , Peng Chien‐Fang , Chang Hsun‐Shuo , Chen Ih‐Sheng
Published: December 2008

Three racemic butanolides, majorenolide (1), majorynolide (2), and majoranolide (3), with 18 known compounds, including ten butanolides, i.e., litsenolide A2 (4), litsenolide B2 (5), litsenolide C1 (6), litsenolide C2 (7), hamabiwalactone A (8), hamabiwalactone B (9), litseakolide A (10), litseakolide B (11), isoobtusilactone (12), and obtusilactone (13); one lignan, i.e., (±)‐syringaresinol (14), two flavans, i.e., (+)‐catechin (15), and (−)‐epicatechin (16), one coumarin, i.e., scopoletin (17), and four steroids, i.e., a mixture of β‐sitosterol (18) and stigmasterol (19), and a mixture of β‐sitosteryl‐3‐O‐β‐D‐glucoside (20) and stigmasteryl‐3‐O‐β‐D‐glucoside (21) were isolated from the root of Lindera akoensis. The structures of the isolates were elucidated by in‐depth spectroscopic analysis. Compounds 1–3 were previously assigned a δ‐lactone structure, which was then revised to a γ‐lactone structure, based on 1D‐NMR data. The cigar‐HMBC technique was used to confirm the accuracy of the γ‐lactone structure, and the zero [α]$\rm{ _{\rm{D}}^{20} }$ value of compounds 1–3 suggested that they were considerably racemized. Nine butanolides 1–3, 4–8, and 10 showed antimycobacterial activities against M. tuberculosis H37Rv, with MIC values of 15–50 μg/ml.
Effects of Compounds Isolated from the Fruits of Rumex japonicus on the Protein Glycation
Authors: Jang Dae Sik , Kim Jong Min , Kim Junghyun , Yoo Jeong Lim , Kim Young Sook , Kim Jin Sook
Published: December 2008

An anthraquinone, emodin (1), and five flavonoids, kaempferol‐3‐O‐β‐D‐glucoside (2), quercetin (3), quercitrin (4), isoquercitrin (5), and (+)‐catechin (6), were isolated from an AcOEt‐soluble extract of the fruits of Rumex japonicus. Their structures were determined by spectroscopic data interpretation. All the isolates were evaluated for their potential to inhibit AGEs (advanced glycation end products) formation and AGEs cross‐linking, and to break already formed AGEs cross‐links.
trans–cis Photoisomerization of Azobenzene‐Conjugated Dithiolato‐Bipyridine Platinum(II) Complexes: Extension of Photoresponse to Longer Wavelengths and Photocontrollable Tristability
Authors: Sakamoto Ryota , Kume Shoko , Sugimoto Manabu , Nishihara Hiroshi
Published: December 2008

Azobenzene derivatives modified with dithiolato‐bipyridine platinum(II) complexes were synthesized, revealing their highly extended photoresponses to the long wavelength region as well as unique photocontrollable tristability. The absorptions of trans‐1 and trans‐2 with one azobenzene group on the dithiolene and bipyridine ligands, respectively, cover the range from 300 to 700 nm. These absorptions are ascribed, by means of time‐dependent (TD)DFT calculations, to transitions from dithiolene(π) to bipyridine(π*), namely, interligand charge transfer (CT), π–π*, and n–π* transitions of the azobenzene unit, and π–π* transitions of the bipyridine ligand. In addition, only trans‐1 shows distinctive electronic bands, assignable to transitions from the dithiolene(π) to azobenzene(π*), defined as intraligand CT. Complex 1 shows photoisomerization behavior opposite to that of azobenzene: trans‐to‐cis and cis‐to‐trans conversions proceed with 405 and 312 nm irradiation, which correspond to excitation with the intraligand CT, and π–π* bands of the azobenzene and bipyridine units, respectively. In contrast, complex 2 shows photoisomerization similar to that of azobenzene: trans‐to‐cis and cis‐to‐trans transformations occur with 365 and 405 nm irradiation, respectively. Irradiation at 578 nm, corresponding to excitation of the interligand CT transitions, results in cis‐to‐trans conversion of both 1 and 2, which is the longest wavelength ever reported to effect the photoisomerization of the azobenzene group. The absorption and photochromism of 4, which has azobenzene groups on both the dithiolato and bipyridine ligands, have characteristics quite similar to those of 1 and 2, which furnishes 4 with photocontrollable tristability in a single molecule using light at 365, 405, and 578 nm. We also clarified that 1 and 2 have high photoisomerization efficiencies, and good thermal stability of the cis forms. Complexes 3 and 5 have almost the identical photoresponse to those of their positional isomers, complexes 2 and 4.
Spin Crossover in a Family of Iron(II) Complexes with Hexadentate ligands: Ligand Strain as a Factor Determining the Transition Temperature
Authors: Matouzenko Galina S. , Borshch Serguei A. , Jeanneau Erwann , Bushuev Mark B.
Published: December 2008

This paper reports the synthesis of a family of mononuclear complexes [Fe(L)]X2 (X=BF4, PF6, ClO4) with hexadentate ligands L=Hpy‐DAPP ({bis[N‐(2‐pyridylmethyl)‐3‐aminopropyl](2‐pyridylmethyl)amine}), Hpy‐EPPA ({[N‐(2‐pyridylmethyl)‐3‐aminopropyl][N‐(2‐pyridylmethyl)‐2‐aminoethyl](2‐pyridylmethyl)amine}) and Hpy‐DEPA ({bis[N‐(2‐pyridylmethyl)‐2‐aminoethyl](2‐pyridylmethyl)amine}). The systematic change of the length of amino‐aliphatic chains in these ligands results in chelate rings of different size: two six‐membered rings for Hpy‐DAPP, one five‐ and one six‐membered rings for Hpy‐EPPA, and two five‐membered rings for Hpy‐DEPA. The X‐ray analysis of three low‐spin complexes [Fe(L)](BF4)2 revealed similarities in their molecular and crystal structures. The magnetic measurements have shown that all synthesized complexes display spin‐crossover behavior. The spin‐transition temperature increases upon the change from six‐membered to five‐membered chelate rings, clearly demonstrating the role of the ligand strain. This effect does not depend on the nature of the counter ion. We discuss the structural features accountable for the strain effect on the spin‐transition temperature.
Formation of Tantalum Carbide and Nitride Phases in Atomic Layer Deposition Using Hydrogen Plasma and tert‐Butylimido‐tris(diethylamido)‐tantalum (TBTDET), and its Effect on Material Properties
Authors: Song Moon‐Kyun , Rhee Shi‐Woo
Published: December 2008

TaCN films are deposited with plasma‐enhanced atomic layer deposition (PEALD) using tert‐butylimido‐tris(diethylamido)‐tantalum and hydrogen. It is confirmed that the film is a homogeneous mixture of TaC, TaN, Ta3N5, and Ta2O5 with the oxide phase formed from the post‐deposition uptake of oxygen from the air. It is shown that the electrical properties of TaCN film are affected by the phase composition in the film. The effects of process parameters, such as deposition temperature, plasma power, and cycle time, on the film composition and electronic properties are evaluated. With the increase of the TaC and TaN phases over the Ta3N5 phase, the resistivity of the film is decreased. As the deposition temperature, plasma power, and plasma cycle time are increased, the carbide and TaN phases in the film are increased and the film resistivity is decreased. The uptake of oxygen after deposition is up to 10 at.‐%, and the resistivity of TaCN film deposited using PEALD is as low as 350 µΩ · cm.
Study of Atmospheric MOCVD of TiO2 Thin Films by Means of Computational Fluid Dynamics Simulations
Authors: Baguer Neyda , Neyts Erik , Van Gils Sake , Bogaerts Annemie
Published: December 2008

This paper presents the computational study of the metal‐organic (MO) CVD of titanium dioxide (TiO2) films grown using titanium tetraisopropoxide (TTIP) as a precursor and nitrogen as a carrier gas. The TiO2 films are deposited under atmospheric pressure. The effects of the precursor concentration, the substrate temperature, and the hydrolysis reaction on the deposition process are investigated. It is found that hydrolysis of the TTIP decreases the onset temperature of the gas‐phase thermal decomposition, and that the deposition rate increases with the precursor concentration and with the decrease of substrate temperature. Concerning the mechanism responsible for the film growth, the model shows that at the lowest precursor concentration, the direct adsorption of the precursor is dominant, while at higher precursor concentrations, the monomer deposition becomes more important.
Controlling the Size and Density of Silicon Nanostructures by Incorporation of Nitrogen
Authors: Kiebach Ragnar , Yu Zhenrui , Aceves‐Mijares Mariano , Du Jinhui , Bian Dongcai , López‐Estopier Rosa , Carrillo‐Lopez Jesús , Juárez‐Diaz Gabriel , Juarez Javier Martinez
Published: December 2008

Si nanostructures are prepared by thermal annealing of silicon rich oxide (SRO) which is deposited using low pressure (LP) CVD. X‐ray diffraction (XRD), Raman spectroscopy, infrared (IR) spectroscopy, and transmission electron microscopy (TEM) are used to characterize the structure of the Si nanocrystals and nanoislands. The density, crystallinity, and size of the Si nanoislands and Si nanocrystals can be controlled by the amount of nitrogen hosted in the SRO. The Si and SiO2 phase separation of the SRO during the annealing process is hindered by the incorporation of nitrogen.
Magnetic Field Effects on the Formation and Properties of Nickel Nanostructures
Authors: Sun Lixia , Chen Qianwang
Published: December 2008

A facile solvothermal hydrazine reduction route was designed for the synthesis of shape‐controlled one‐dimensional (1D) nickel wires in the presence of magnetic fields. The reaction conditions involved were studied systematically to select the optimal reaction parameters to reveal the effects of weak magnetic fields on the formation and properties of nickel nanostructures. The magnetic‐field‐dependent formation of 1D nickel wires indicated that the reduction of nickel ions with concentration less than 0.21 M preferentially occurs along the magnetic line of force, leading to the formation of uniform 1D wires, whereas higher concentrations could lead to quick reaction in the whole system and formation of isolated particles coexisting with wires composed of microspheres formed along the magnetic line of force. The improved magnetic properties of the sample formed in a magnetic field relative to those of samples formed without an applied field may be due to variation of the magnetic domain structure in the 1D nickel wires. Moreover, it was found that microwave absorption of a 1D nickel wire/poly(methyl methacrylate) (PMMA) composite at 8.5–12.5 GHz was evidently enhanced relative to that of a nickel microsphere/PMMA composite, which indicates that the anisotropic wires are not simply an assembly of particles, but that the magnetic domain structures in wires has been changed by the applied field.(© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2009)
New Terpenoid Constituents of the Southwestern Caribbean Sea Whip Pseudopterogorgia elisabethae (Bayer), Including a Unique Pentanorditerpene
Authors: Shi Yan‐Ping , Wei Xiaomei , Rodríguez Ileana I. , Rodríguez Abimael D. , Mayer Alejandro M. S.
Published: December 2008

Seven structurally diverse terpenoids, including four diterpenes, a norditerpene, a bisnorditerpene, and a biogenetically related pentanorditerpene, have been isolated from the hexane extract of the Caribbean gorgonian octocoral Pseudopterogorgia elisabethae, collected near the island of San Andrés, Colombia. The structures of all the new compounds were determined by detailed spectroscopic analysis and chemical derivatization. Many of the purified isolates were evaluated in vitro as potential agents to treat neuroinflammation and also as growth inhibitors against the pathogenic microbe Mycobacterium tuberculosis H37Rv.(© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2009)
Photocyclodimerization of 5‐Methyl‐2H‐pyran‐3(6H)‐one
Authors: Groesch Ljubov , Kopf Jürgen , Margaretha Paul
Published: December 2008

The structures of the main products resulting from photocyclodimerization of the title compound 2 and of other 3‐methyl‐substituted ‘oxacyclohex‐2‐en‐1‐ones’ (=dihydropyranones) were determined by X‐ray crystallography. In connection, the 13C‐NMR chemical shifts of the cyclobutane C‐atoms of these dimers allow a clear differentiation between head‐to‐head and head‐to‐tail regioisomers, all structurally related to those of isophorone (1).
Iridoids from the Bark of Alstonia scholaris
Authors: Feng Tao , Cai Xiang‐Hai , Du Zhi‐Zhi , Luo Xiao‐Dong
Published: December 2008

Four new 11‐noriridoids named scholareins A–D (1–4), along with three known derivatives, isoboonein (5), alyxialactone (6), and loganin (7), were isolated from EtOH extracts of the bark of Alstonia scholaris by chromatographic methods. Their structures were identified by extensive mass‐spectrometric and spectroscopic (especially 2D‐NMR) experiments.
One‐Pot Diastereoselective Synthesis of Densely Functionalized 2H‐Indeno[2,1‐b]furans. Single‐Crystal X‐Ray Structure of Dimethyl 8,8a‐Dihydro‐8‐oxo‐8a‐(2,2,2‐trichloroethoxy)‐2H‐indeno[2,1‐b]furan‐2,3‐di­carboxylate
Authors: Ramazani Ali , Noshiranzadeh Nader , Ghamkhari Alieh , Ślepokura Katarzyna , Lis Tadeusz
Published: December 2008

Highly reactive 1 : 1 intermediates were produced in the reaction of Ph3P and dialkyl acetylenedicarboxylates (=dialkyl but‐2‐ynedioates). Protonation of these intermediates by alcohols (2,2,2‐trichloroethanol, propargyl alcohol (=prop‐2‐yn‐1‐ol), MeOH, benzyl alcohol, and allyl alcohol (=prop‐2‐en‐1‐ol) led to vinyltriphenylphosphonium salts 4, which underwent a Michael addition reaction with the conjugate base to produce the corresponding stabilized phosphonium ylides 5 (Scheme). Wittig reaction of the stabilized phosphonium ylides with ninhydrin (6) led to the corresponding densely functionalized 2H‐indeno[2,1‐b]furans 10 in fairly good yields (Table 1). The structures of the final products were confirmed by IR, 1H‐ and 13C‐NMR spectroscopy, and mass spectrometry. The configuration of dimethyl 8,8a‐dihydro‐8‐oxo‐8a‐(2,2,2‐trichloroethoxy)‐2H‐indeno[2,1‐b]furan‐2,3‐dicarboxylate (10a) was established by a single‐crystal X‐ray structure determination, establishing that the one‐pot multicomponent condensation reaction was completely diastereoselective.
Withanolides from Physalis alkekengi var. francheti
Authors: Li Yi‐Zheng , Pan Ying‐Ming , Huang Xiao‐Yan , Wang Heng‐Shan
Published: December 2008

Two new withanolides, namely (20S,22R)‐15α‐acetoxy‐5α‐chloro‐6β,14β‐dihydroxy‐1‐oxowitha‐2,24‐dienolide (1) and (22R)‐5β,6β : 14α,17 : 14β,26‐triepoxy‐2α‐ethoxy‐13,20,22‐trihydroxy‐1,15‐dioxo‐16α,24‐cyclo‐13,14‐secoergosta‐18,27‐dioic acid 18→20,27→22‐dilactone (2), along with six known compounds, physagulin B (3), withangulatin A (4), physalin I (5), withaminimin (6), physagulin J (7), and ergosta‐5,25‐diene‐3β,24ξ‐diol (8), were isolated from the whole plant of Physalis alkekengi var. francheti. Their structures were elucidated on the basis of spectroscopic analyses.
Reductions of Benzene Derivatives Whose Benzylic Positions Bear Oxygen Atoms under Mild Conditions
Authors: Menzek Abdullah , Karakaya Melek Gökmen , Kaya Afşin Ahmet
Published: December 2008

Reductions of compounds whose benzylic positions bear O‐atoms, such as benzyl alcohol, dibenzyl ether, styrene oxide, benzaldehyde, acetophenone, and benzophenone, to the corresponding non‐conjugated dienes were performed by using t‐BuOH, Li, and gaseous NH3 in THF at room temperature. In these reductions, it was observed that the functional groups at benzylic positions were reduced first.