bluuebunny/crossref_metadata_2025 huggingface dataset:
Le désarroi du thérapeute systémicien face à la diversité des représentations de la famille et le chevauchement des modèles familiaux chez le(s) consultant(s)
Authors: Bargach Amina , Mrini Salima , Gharbi Leïla
Published: April 2011

Dans cette mouvance sociétale telle qu’elle a été exprimée par les organisateurs, notre idée en tant que praticiennes marocaines, est de transmettre et de partager notre expérience clinique avec d’autres praticiens. Notre but serait de converger vers des modèles de conceptualisation et d’intervention systémique qui d’un côté garde la cohérence et la rigueur de nos outils et de l’autre nous permette de chercher notre propre évolution. De notre point de vue, cette mouvance est beaucoup plus frappante que l’idée qu’on a ailleurs du Maroc comme pays arabo-musulman. Alors qu’il y a différents modèles de famille (berbère, juive, chrétienne et musulmane), et que la réalité dans laquelle nous sommes impliquées est plus complexe, nous sommes confrontées à des changements brusques auxquels nous n’avons pas pu avoir le temps de nous adapter. Les diversités des représentations de la famille chez l’individu peuvent nous surprendre et nous dérouter, ce qui nous ramène à revoir nos propres représentations en tant que professionnelles pour répondre à la demande des personnes et des familles qui s’adressent à nous, tout en essayant d’introduire des changements dans le contexte. Quelques exemples significatifs de thérapies familiales dans ce bouleversement vont être présentés dans cet article pour illustrer nos préoccupations en tant que thérapeutes de familles au Maroc dans le contexte actuel.
Security of Bolted Joints during Explosive Loading
Authors: Horsfall Ian , Hansen Bjarne , Carr Debra
Published: April 2011

Bolted joints are used extensively in military vehicles allowing for the rapid repair of modular systems. However, concerns have been raised regarding the security of such joints during an explosion when severe shear loadings are likely. This paper examines the response of bolted joints to explosive, quasi-static and dynamic loading regimes. The energy required to fracture, energy absorbed during fracture, and metallographic features produced during loading are presented. No evidence of brittle failure was observed, irrespective of loading rate. The use of countersunk holes increased the energy absorbed during dynamic fracture.
Lightweight Hybrid Electrical Vehicle Structural Topology Optimisation Investigation Focusing on Crashworthiness
Authors: Christensen Jesper , Bastien Christophe , Blundell Mike , Gittens Andrew , Tomlin Oliver
Published: April 2011

As focus on the world climate rises, so does the demand for ever more environmentally friendly technologies. The response from the automotive industry includes vehicles whose primary propulsion systems are not based upon fossil fuels. On this basis a Low Carbon Vehicle Technology Project, partly funded by the European Regional Development Fund, is currently under way; part of this project involves designing a lightweight Body In White (BIW). This has been specifically tailored to suit the drive train and general packaging requirements associated with a Hybrid Electric Vehicle (HEV). The future opportunities for new lightweight vehicle architecture have been investigated using a technique entitled topology optimisation, which extracts the idealised load paths for a given loading. The topology optimisation includes equivalent NCAP dynamic impact loading conditions, as well as torsional rigidity performance. Initially a total of 7 loading scenarios are applied on a structure comprising of various battery and range extender layouts. Two different optimisation modelling techniques have been undertaken comparing conventional boundary conditions against inertia relief, as well as studying the sensitivity of the BIW topology against the influence of load case direction and battery box stiffness. Optimal locations for the two components having the highest mass, i.e. a single battery pack and a combined range extender and fuel tank have been studied focusing upon the effects of the location of their Centre of Mass. It has been assumed that advances in battery technology will reduce the external dimensions of the battery package, thereby enabling an increased number of possible locations within the BIW.
Fine-tuning Nonlinear Finite Element Analysis Methodology for Aircraft Seat Certification using Component Level Testing and Validation
Authors: Bhonge Prasannakumar S. , Lankarani Hamid M.
Published: April 2011

Finite element analysis (FEA) has become a part of new development in automotive as well as in aircraft seating industries. The goal of the FEA in product development is not only to design but to substantiate the certification tests or possibly replace the certification tests. The case of a certification by substantiation tests increases the necessity of validation of the Finite Element (FE) model. In the aircraft industry, the seating Advisory Circular (AC) 20-146 specifies a methodology for the dynamic seat, Certification By Analysis, for use in the Parts 23, 25, 27 and 29 airplanes and rotorcraft. In FE modeling of typically nonlinear environments such as the aircraft dynamic seat simulations, input parameters such as material model, element type, time step scale factor, element length, material model etc. play a vital role in the accuracy of the results. Selecting appropriate material models and other parameters leads to improved accuracy in the FE model and hence to validation with the experimental test results. The purpose of this study is to fine-tune non-linear FEA methodology for aircraft seat certification using component level testing and validation. For this purpose, the effects of input parameters such as the material model, element length, and time step scale factor are evaluated using component test-FE simulation on static tension test on aluminum, high speed load-deflection test on seat cushion and belt pull test. Verification of FE input parameters is determined in each case. Appropriate input variables are selected and provided to an aircraft seat FEA case study and validated against sled test results to demonstrate the validity of the finite element models.
Application of Shell Elements to Create Advanced Finite Element Model for Offset Deformable Barrier
Authors: Asadi Mehrdad , Walker Brian
Published: April 2011

Crash test barriers have been used to assess crashworthiness characteristics of passenger vehicles. Different barriers are employed to examine specific aspects of car structures within certain impact conditions. This paper demonstrates a methodology to create finite element model for Offset Deformable Barrier (ODB) that is used in frontal crash tests. The model is generated using shell elements in LS-DYNA to configure aluminium honeycomb sections. A generic Y cross-section is initially devolved and validated by component test results predict crush behaviour of honeycomb blocks and establish material data before they are used in ODB model. A series of full-scale physical tests has been designed and performed to verify the accuracy of the new FE model for ODB. The model is subjected to four tests with individual boundary conditions and impact speeds while numerical and visual data from CAE are correlated against experiments. The results from FE analysis offer precise correlations with test data and the model has been able to capture detailed deformation patterns for each test setup.
Evaluation of a Tailored Approach for Tobacco Dependence Treatment for American Indians
Authors: D'Silva Joanne , Schillo Barbara A. , Sandman Nathan R. , Leonard Theresa L. , Boyle Raymond G.
Published: April 2011

Purpose.

Evaluate a tailored approach for tobacco dependence treatment for American Indians.

Design.

A single-group design evaluation of a culturally specific curriculum for tobacco dependence treatment was implemented. Baseline assessment, program utilization, and 90-day follow-up interview data were analyzed.

Setting.

Fond du Lac Reservation in rural Minnesota and Mashkiki Waakaaigan Pharmacy in Minneapolis, Minnesota.

Subjects.

American Indian adults (N = 317).

Intervention.

Four 1-hour individual or group sessions of behavioral counseling paired with pharmacotherapy.

Measures.

Demographic variables, program satisfaction, and tobacco use behaviors.

Analysis.

Descriptive statistics; for abstinence, a smoking = missing analysis was used, assuming all nonrespondents were still smoking.

Results.

Sixty-three percent of participants completed the program. The 90-day follow-up response rate was 47%. Of those who completed, 47% reported abstinence at the 90-day follow-up. Missing = smoking analysis yielded a 21.8% quit rate. Continuing smokers cut their daily smoking by half from 17 to eight cigarettes, 88% reported an increase in self-efficacy for their next quit, and 44% planned to quit within 30 days.

Conclusion.

Evidence-based tobacco dependence treatment programs tailored to be culturally specific have the potential to significantly affect the burden of tobacco-related disparities among American Indians. (Am J Health Promot 2011;25[5 Supplement]:S66-S69.)
Quitline Utilization Rates of African-American and White Smokers: The California Experience
Authors: Zhu Shu-Hong , Gardiner Phillip , Cummins Sharon , Anderson Christopher , Wong Shiushing , Cowling David , Gamst Anthony
Published: April 2011

Purpose.

To compare the utilization rate of a statewide tobacco quitline by African-American smokers to that of white smokers.

Design, Setting, and Subjects.

Observational study of 18 years of state quitline operation in California. Subjects were 61,096 African-American and 279,042 white smokers who called the quitline from August 1992 to December 2009. Data from six California Tobacco Surveys, 1993, 1996, 1999, 2002, 2005, and 2008 were also used.

Measure.

Callers' answers to the question how they heard about the quitline were grouped into four categories: media, health care providers, friends/family, and others.

Analysis.

The averaged annual quitline call volume for each ethnic group was divided by the total number of smokers in that group, based on California Tobacco Surveys, to produce the annual quitline utilization rate.

Results.

In five out of six periods of comparison, African-American smokers had a higher annual utilization rate than white smokers. The odds ratios [ORs] ranged from 1.44 to 2.40 (all p < .05). In the 1996 comparison, the OR was .90 (p < .05). The difference in utilization rates that is attributed to media, accounts for most of the difference in total utilization rates between the two ethnic groups.

Conclusions.

Within the context of California's comprehensive tobacco control program, which includes a strong media campaign, African-American smokers were significantly more likely to call the state quitline than white smokers were. Promoting the quitline as part of antismoking media campaigns can help reduce disparity in cessation service utilization. (Am J Health Promot 2011;25[5 Supplement]:S51–S58.)
Provider Smoking Cessation Advice among California Asian-American Smokers
Authors: Tong Elisa K. , Tang Hao , Chen Moon S. , McPhee Stephen J.
Published: April 2011

Purpose.

To determine proportions of provider advice to quit smoking for Asian-American smokers and to describe factors that may affect the provision of such advice.

Design.

Secondary data analysis of population-based survey.

Setting.

California.

Subjects.

Current smokers from the California Tobacco Use Surveys for Chinese-Americans (n = 2117, participation rate = 52%), Korean-Americans (n = 2545, participation rate = 48%), and Vietnamese-Americans (n = 2179, participation rate = 63.5%).

Measures.

Sociodemographics including insurance status, smoking frequency, provider visit in past year, and provider advice to quit.

Analysis.

Multivariate logistic regression models examined dependent outcomes of (1) provider visit in past year and (2) provider advice to quit.

Results.

Less than a third (30.5%) of smokers in our study reported both seeing a provider (50.8%) and then receiving advice to quit (60.1%). Factors associated with provider visits included being female, being 45 years or older, having health insurance, and being Vietnamese. Among smokers who saw a provider, factors associated with provider advice to quit included having health insurance and being a daily smoker.

Conclusions.

Asian-American smokers reported low proportions of provider advice to quit in the past year, largely because only half of smokers saw a provider. Providers who see such smokers may need greater awareness that several effective cessation treatments do not require health insurance, and that intermittent smokers need advice to quit. (Am J Health Promot 2011;25[5 Supplement]:S70-S74.)
Differences in Smoking Behavior and Attitudes among Puerto Rican, Dominican, and Non-Latino White Caregivers of Children with Asthma
Authors: Borrelli Belinda , Hayes Rashelle B. , Gregor Kristin , Lee Christina S. , McQuaid Elizabeth L.
Published: April 2011

Purpose.

No studies have examined the differences in smoking attitudes and behavior between Dominicans (DRs) and Puerto Ricans (PRs). Identification of pretreatment differences is important for cultural adaptation of evidenced-based smoking cessation treatments.

Design.

Secondary analysis.

Setting/Intervention.

Three home visits for asthma education and smoking cessation.

Subjects.

Caregivers who smoke and have a child with asthma: DRs (n = 30), PRs (n = 67), and non-Latino whites (n = 128; NLWs).

Measures.

Baseline assessment of psychosocial variables.

Analyses.

Controlled for age, education, and acculturation.

Results.

Compared with DRs, PRs were more acculturated, more nicotine dependent, less motivated and confident to quit, and identified more pros of smoking (all p < .05). Compared with NLWs, PRs were less likely to be employed, smoked fewer cigarettes per day, and had lower education, greater depressed mood, greater pros and cons of smoking, less social support, and higher child asthma morbidity (all p < .05). Compared with NLWs, DRs were less nicotine dependent, more confident to quit, and less likely to live with a smoker; reported greater cons of smoking and greater stress; and were more likely to have a household smoking ban (DRs 60% vs. NLWs 33.6%). Only 3.3% of DRs were precontemplators vs. 16.4% (PRs) and 10.9% (NLWs).

Conclusions.

PRs appear to have more factors associated with risk of smoking treatment failure; DRs appear to have more protective factors. Examination of the role of these smoking attitudes as potential moderators and mediators of smoking behavior are needed to guide the cultural adaptation of evidenced-based treatments. (Am J Health Promot 2011;25[5 Supplement]:S91—S95.)
The annual cycle in lower stratospheric temperatures revisited
Authors: Fueglistaler S. , Haynes P. H. , Forster P. M.
Published: April 2011

Abstract. Observed lower stratospheric temperatures show a prominent annual cycle. The cycles in the tropics and Northern Hemisphere are in phase and the cycle in the Southern Hemisphere has the opposite phase. In an elegant and influential paper, Yulaeva, Holton and Wallace (1994) explained the observed pattern as a direct consequence of hemispheric asymmetries in the dynamical forcing of the stratospheric circulation. They showed that in Microwave Sounding Unit channel 4 (weighting centered in the lower stratosphere) data the combined extratropical and the tropical temperature cycle nearly compensate and interpreted the out-of-phase temperature variations between tropics and extratropics as the temperature response to an annual cycle in the wave driven residual circulation. We show that the near-compensation of temperature variations observed by Yulaeva et al. (1994) is artefact of the weighting function of the MSU-4 channel and does not hold on individual pressure levels. We discuss in detail the conditions required that temperature variations compensate, and what insights can be obtained from analysis of tropical, extratropical and global mean temperature variations. Dynamically induced seasonal variations of lower stratospheric ozone lead to an amplification of the seasonal temperature cycle particularly in the tropics. The latitudinal structure of static stability also induces a significant deviation from compensation of tropical and combined extratropical temperature variations. In line with Yulaeva et al. (1994) we affirm that the see-saw pattern in the annual cycles of tropical and combined extratropical temperatures provides an important pointer to mechanistic models for interannual variability and trends, but additionally conclude that the feedback of dynamically induced ozone variations on temperatures and the latitudinal structure of static stability should be included as leading order processes in such models.
Measurements of cloud condensation nuclei activity and droplet activation kinetics of wet processed regional dust samples and minerals
Authors: Kumar P. , Sokolik I. N. , Nenes A.
Published: April 2011

Abstract. This study reports laboratory measurements of particle size distributions, cloud condensation nuclei (CCN) activity, and droplet activation kinetics of wet generated aerosols from clays, calcite, quartz, and desert soil samples from Northern Africa, East Asia/China, and Northern America. The dependence of critical supersaturation, sc, on particle dry diameter, Ddry, is used to characterize particle-water interactions and assess the ability of Frenkel-Halsey-Hill adsorption activation theory (FHH-AT) and Köhler theory (KT) to describe the CCN activity of the considered samples. Regional dust samples produce unimodal size distributions with particle sizes as small as 40 nm, CCN activation consistent with KT, and exhibit hygroscopicity similar to inorganic salts. Clays and minerals produce a bimodal size distribution; the CCN activity of the smaller mode is consistent with KT, while the larger mode is less hydrophilic, follows activation by FHH-AT, and displays almost identical CCN activity to dry generated dust. Ion Chromatography (IC) analysis performed on regional dust samples indicates a soluble fraction that cannot explain the CCN activity of dry or wet generated dust. A mass balance and hygroscopicity closure suggests that the small amount of ions (of low solubility compounds like calcite) present in the dry dust dissolve in the aqueous suspension during the wet generation process and give rise to the observed small hygroscopic mode. Overall these results identify an artifact that may question the atmospheric relevance of dust CCN activity studies using the wet generation method. Based on a threshold droplet growth analysis, wet generated mineral aerosols display similar activation kinetics compared to ammonium sulfate calibration aerosol. Finally, a unified CCN activity framework that accounts for concurrent effects of solute and adsorption is developed to describe the CCN activity of aged or hygroscopic dusts.
Size-resolved CCN distributions and activation kinetics of aged continental and marine aerosol
Authors: Bougiatioti A. , Nenes A. , Fountoukis C. , Kalivitis N. , Pandis S. N. , Mihalopoulos N.
Published: April 2011

Abstract. We present size-segregated measurements of cloud condensation nucleus (CCN) activity of aged aerosol sampled at Finokalia, Crete, during the Finokalia Aerosol Measurement Experiment of summer 2007 (FAME07). From analysis of the data, hygroscopicity and activation kinetics distributions are derived. The CCN are found to be highly hygroscopic, (expressed by a size- and time-averaged hygroscopicity parameter κ ~ 0.22), with the majority of particles activating at ~0.5–0.6% supersaturation. Air masses originating from Central-Eastern Europe tend to be associated with higher CCN concentrations and slightly lower hygroscopicity (κ ~ 0.18) than for other airmass types. The particles were always well mixed, as reflected by the high activation ratios and narrow hygroscopicity distribution widths. Smaller particles (~30 nm) were found to be more hygroscopic (~0.1 κ units higher) than the larger ones (~100 nm). The particles with diameters less than 80 nm exhibited a diurnal hygroscopicity cycle (with κ peaking at ~14:00 h local time), consistent with photochemical aging and volatilization of less hygroscopic material from the aerosol. Use of bulk chemical composition and the aerosol number distribution results in excellent CCN closure when applying Köhler theory in its simplest form. Using asymptotic and threshold droplet growth analysis, the "aged" organics present in the aerosol were found not to suppress or delay the water uptake kinetics of particles in this environment.
Identification of a general light use efficiency model for gross primary production
Authors: Horn J. E. , Schulz K.
Published: April 2011

Abstract. Non-stationary and non-linear dynamic time series analysis tools are applied to multi-annual eddy covariance and micrometeorological data from 44 FLUXNET sites to derive a light use efficiency model for gross primary production on a daily basis. The extracted typical behaviour of the canopies in response to meteorological forcing leads to a model formulation allowing for a variable influence of the environmental drivers temperature and moisture availability modulating the light use efficiency. Thereby, the model is applicable to a broad range of vegetation types and climatic conditions. The proposed model explains large proportions of the variation of the gross carbon uptake at the study sites while the optimized set of six parameters is well defined. With the parameters showing explainable and meaningful relations to site-specific environmental conditions, the model has the potential to serve as basis for general regionalization strategies for large scale carbon flux predictions.
Interglacial and glacial variability from the last 800 ka in marine, ice and terrestrial archives
Authors: Lang N. , Wolff E. W.
Published: April 2011

Abstract. We have compiled 37 ice, marine and terrestrial palaeoclimate records covering the last 800 000 years in order to assess the pattern of glacial and interglacial strength, and termination amplitude. Records were selected based on their length, completeness and resolution, and their age models were updated, where required, by alignment to the LR04 benthic δ18O stack. The resulting compilation allows comparison of individual glacial to interglacial transitions with confidence, but the level of synchronisation is inadequate for discussion of temporal phasing. The comparison of interglacials and glacials concentrates on the peaks immediately before and after terminations; particularly strong and weak glacials and interglacials have been identified. This confirms that strong interglacials are confined to the last 450 ka, and that this is a globally robust pattern; however weak interglacials (i.e. marine isotope stage 7) can still occur in this later period. Strong glacial periods are also concentrated in the recent half of the records, although marine isotope stage 16 is strong in many δ18O records. Strong interglacials, particularly in the marine isotopic records, tend to follow strong glacials, suggesting that we should not expect interglacial strength to be strongly influenced by the instantaneous astronomical forcing. Many interglacials have a complex structure, with multiple peaks and troughs whose origin needs to be understood. However this compilation emphasises the under-representation of terrestrial environments and highlights the need for long palaeoclimate records from these areas. The main result of this work is the compiled datasets and maps of interglacial strength which provide a target for modelling studies and for conceptual understanding.
Exploration of land-use scenarios for flood hazard modeling – the case of Santiago de Chile
Authors: Müller A. , Reinstorf F.
Published: April 2011

Abstract. Urban expansion leads to modifications in land use and land cover and to the loss of vegetated areas. These developments are in some regions of the world accelerated by a changing regional climate. As a consequence, major changes in the amount of green spaces can be observed in many urban regions. Amongst other dependences the amount of green spaces determines the availability of retention areas in a watershed. The goal of this research is to develop possible land-use and land-cover scenarios for a watershed and to explore the influence of land-use and land-cover changes on its runoff behavior using the distributed hydrological model HEC-HMS. The study area for this research is a small peri-urban watershed in the eastern area of Santiago de Chile. Three spatially explicit exploratory land-use/land-cover scenario alternatives were developed based on the analysis of previous land-use developments using high resolution satellite data, on the analysis of urban planning laws, on the analysis of climate change predictions, and on expert interviews. Modeling the resulting changes in runoff allows making predictions about the changes in flood hazard which the adjacent urban areas are facing after heavy winter precipitation events. The paper shows how HEC-HMS was used applying a distributed event modeling approach. The derived runoff values are combined with existing flood hazard maps and can be regarded as important source of information for the adaptation to changing conditions in the study area. The most significant finding is that the land-use changes that have to be expected after long drought periods pose the highest risk with respect to floods.
Predicting the Specific Surface Area and Pressure Drop of Reticulated Ceramic Foams Used as Catalyst Support
Authors: Inayat Amer , Freund Hannsjörg , Schwab Andreas , Zeiser Thomas , Schwieger Wilhelm
Published: April 2011

Open‐cell ceramic foams are attractive candidates as catalyst support owing to their remarkable heat and mass transfer characteristics. The accurate knowledge of the specific surface area and the pressure drop is a prerequisite for the reliable design of reactors with solid foam structures as internals. In this contribution, we propose a new correlation for the prediction of the pressure drop in reticulated ceramic foams using their predicted specific surface area. The correlation is based on an ideal tetrakaidecahedron geometry, which is the preferred representative geometry for reticulated foams. The validity of the correlation is demonstrated by experimental data of reticulated ceramic foams of different pores per inch (PPI), porosity, and material from the present study as well as from the open literature.
The Potential of Molecular Self‐Assembled Monolayers in Organic Electronic Devices
Authors: Halik Marcus , Hirsch Andreas
Published: April 2011

Functionalized molecules that organize to self‐assembled monolayers (SAMs) are gaining importance in organic electronic devices. They are fully compatible with flexible substrates, are amenable to low‐cost processing, and show reliable film‐forming behavior. Highly integrated devices, such as sensor arrays or memories, have also been demonstrated. Starting from auxiliary layers, which improve and modify surfaces and interfaces in traditional thin‐film devices, the applications of SAMs develop towards molecular scale electronics, including active molecular device layers and multifunctional SAMs, which fulfill several layer functions of a device within one monolayer. Mixed SAMs make new and tunable device features possible, by stoichiometric control of the composition of different SAM‐forming molecules.
Rare‐Earth Ion Doped Up‐Conversion Materials for Photovoltaic Applications
Authors: Wang Hai‐Qiao , Batentschuk Miroslaw , Osvet Andres , Pinna Luigi , Brabec Christoph J.
Published: April 2011

With the aim of utilizing the infrared region of solar radiation to improve solar cell performance, significant progress, including theoretical analysis and experimental achievement, has been made in the field of up‐conversion for photovoltaic applications. This Research News article reviews recent progress in the development of rear‐earth (RE) ion doped up‐conversion materials for solar cell applications. In addition, new trends for RE‐ion‐doped phosphors are briefly discussed, among them trivalent RE‐ion‐doped up‐conversion materials for organic solar cell applications.
Direkte katalytische asymmetrische Reaktionen unter Protonentransferkatalyse
Authors: Kumagai Naoya , Shibasaki Masakatsu
Published: April 2011

Die kooperative Katalyse hat sich als eine leistungsfähige Strategie für stereoselektive Umwandlungen unter milden Bedingungen bewährt. Hierbei sind die spezifischen Wechselwirkungen zwischen den Katalysatorkomponenten und den Substraten so aufeinander abgestimmt, dass hohe Katalyseeffizienzen und eine ausgezeichnete Kontrolle des stereochemischen Verlaufs resultieren. Durch Ausnutzen des Kooperativitätsprinzips lassen sich zahllose stereoselektive Reaktionen unter milden Protonentransferbedingungen mit perfekter Atomökonomie verwirklichen. Dieser Kurzaufsatz fasst unsere jüngsten Beiträge auf dem Gebiet der C‐N‐ und C‐C‐Bindungsbildungen mittels kooperativer Katalyse zusammen.
Recent Advances in Direct Catalytic Asymmetric Transformations under Proton‐Transfer Conditions
Authors: Kumagai Naoya , Shibasaki Masakatsu
Published: April 2011

Cooperative catalysis has proven to be a particularly powerful strategy for promoting stereoselective organic transformations under mild reaction conditions. The specific interactions between the catalyst components and substrates are precisely orchestrated to elicit high catalytic efficiency and excellent control of the stereochemical course. By harnessing the power of cooperativity, various sets of stereoselective reactions proceed under mild proton‐transfer conditions with perfect atom economy. This Minireview summarizes our recent contributions to several CN and CC bond‐forming reactions in this field and related transformations.
Morphological and structural development of recycled crosslinked polyethylene during solid‐state mechanochemical milling
Authors: Wu Hejun , Liang Mei , Lu Canhui
Published: April 2011

Waste crosslinked polyethylene (XLPE) was partially decrosslinked to obtain a thermoplastic recycled material through solid‐state mechanochemical milling with pan‐mill equipment at ambient temperature. The gel fraction and size exclusion chromatography measurements showed that the gel content of XLPE decreased remarkably with increasing cycles of mechanochemical milling, whereas the molecular weight of the sol fraction was not significantly reduced; this indicated the realization of partial decrosslinking during mechanochemical milling. Differential scanning calorimetry and X‐ray diffraction analysis showed that the melting temperature of decrosslinked polyethylene increased by 3.5°C because the bigger crystallites size resulting from the higher mobility of the chain segment. The improved thermoplastic characteristic of XLPE after mechanochemical milling were confirmed by scanning electron microscopy and rheological measurement. The mechanical properties of recycled XLPE also achieved significant improvement after mechanochemical milling. Solid‐state mechanochemical milling is a cost‐effective, reliable, and environmentally friendly method for recycling XLPE at ambient temperature without any additional materials or chemicals. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2011
Negative dielectric constant and electrical conductivity of Au/n‐Si (111) Schottky barrier diodes with PVA/Ni,Zn interfacial layer
Authors: Tunç T. , Dökme İ. , Altındal Ş. , Uslu İ.
Published: April 2011

In this study, the dielectric properties and alternating‐current (ac) conductivity of Au/(PVA/Ni,Zn acetates)/n‐Si Schottky diodes (SDs) were determined by the measurement impedance technique. Dielectric properties and electrical conductivity of Au/(PVA/Ni,Zn acetates)/n‐Si SDs in the frequency range of 0.5 kHz to 10 MHz and voltage range of −2 to 5 V were investigated in detail using experimental C–V and G–V measurements. Experimental results show that the values of the dielectric constant (ε′), dielectric loss (ε″), and tan δ obtained from the measured capacitance and conductance have been a strong function of frequency and applied voltage, and the values of ε′ have been unexpectedly found to be negative, especially at high voltages. Other parameters of Au/(PVA/Ni,Zn acetates)/n‐Si SDs, such as ac electrical conductivity (σac), the real part of electric modulus (M′), and the imaginary part of electric modulus (M″) varied with changing frequency for various voltages. The main propose of this study is to discuss the polymeric interfacial layer at metal and semiconductor affect and probe the dielectric properties of Au/(PVA/Ni,Zn acetates)/n‐Si SDs regarding the negative capacitance as a function of frequency and voltage. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2011
Noncoplanar rigid‐rod aromatic polyhydrazides containing Tröger's base
Authors: Abdolmaleki Amir , Heshmat‐Azad Sanaz , Kheradmand‐fard Mansoreh
Published: April 2011

A new Tröger's base‐containing aromatic dihydrazide, 2,8‐bis(carboxylic)‐6H, 12H‐5,11‐methanodibenzo‐[b,f] [1,5]‐diazocine dihydrazide, was prepared by the condensation of ethyl p‐aminobenzoate with hexamethylenetetramine in the presence of trifluoroacetic acid, followed by converting to the dihydrazide with a high yield and high purity. A series of novel aromatic polyhydrazides were prepared from the Tröger's unit containing dihydrazide and various aromatic diacyl chlorides via low‐temperature solution polycondensation in quantitative yields. All the polyhydrazides were amorphous and readily soluble at room temperature in polar organic solvents such as N,N‐dimethylacetamide and N‐methyl‐2‐pyrrolidone. These polymers could be solution cast into transparent, tough, and flexible films with good mechanical properties. They had useful levels of thermal stability associated with good glass transition temperatures (163–172°C), 10% weight‐loss temperatures in excess of 460°C, and char yields at 800°C in nitrogen higher than 39%. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2011
Thermal, crystalline, and mechanical properties of octa(3‐chloropropylsilsesquioxane)/ poly(L‐lactic acid) hybrid films
Authors: Zhang Xiaojing , Sun Jiashu , Fang Shaoming , Han Xiniu , Li Yadong , Zhang Chenggui
Published: April 2011

A series of organic‐inorganic hybrid films were prepared based on octa(3‐chloropropylsilsesquioxane) (OCPS) and poly(L‐lactic acid) (PLLA) via simply solution blending method. The thermal, crystalline and mechanical properties of OCPS/PLLA hybrid films were characterized by Fourier transform infrared, scanning electron microscopy, energy dispersive spectrometer, differential scanning calorimetry (DSC), X‐ray diffraction, polarized optical microscopy, thermogravimetric analysis (TGA), and tensile tests. The results showed that OCPS could be dispersed well at molecular level when its content was less than 3 wt % and began to crystallize in PLLA matrix when the content increased to 5 wt %. DSC study revealed that OCPS acted as a plasticizer to decrease both Tg and Tm of the PLLA matrix at various heating rates. The addition of OCPS did not change the crystal form of PLLA, while had an great influence on the cold crystallization and melting behaviors of PLLA in the second heating cycles. Moreover, the initial crystallinity of OCPS/PLLA was higher than that of pure PLLA. The results suggested that OCPS could be an effective heterogeneous nucleating reagent to promote the crystallization of PLLA. TGA showed that the PLLA thermal degradation mechanism remained unchanged, whereas the weight loss temperatures and residual weights were improved. Tensile tests indicated that the incorporation of OCPS into PLLA matrix changed the tensile behavior of the hybrid films from brittle to ductile, and the strain at break was improved remarkably as a result of the plasticizer effect of OCPS. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2011
Durable flame retardant finishing of PET/cotton blends using a Novel PVA‐based phosphorus‐nitrogen polymer
Authors: Li Qiang‐Lin , Wang Xiu‐Li , Wang De‐Yi , Wang Yu‐Zhong , Feng Xi‐Ning , Zheng Guang‐Hong
Published: April 2011

A novel polymeric flame retardant (FR) with phosphorous‐nitrogen pendent groups (PVP‐P‐DCA) was synthesized by polyvinyl alcohol (PVA), phosphoric acid, and dicyandiamide (DCA). Its structure was characterized by FTIR, 1H, 13C, 31P NMR, elemental analysis and TG. Poly(ethylene terephthalate) (PET)/cotton blends (T/C) was treated via pad‐dry‐cure process with PVP‐P‐DCA. The surface of FR‐T/C was characterized by FTIR and SEM. The fabric performance was examined by whiteness and tensile property. The fire behavior was performed by limited oxygen index (LOI), vertical burning test, cone calorimetry test. The durability effect, thermal stability, and flame retardancy mechanism of the treated T/C were investigated by TGA, FTIR, and SEM. The results show that PVP‐P‐DCA is not only an effective FR but also a good char‐forming agent for the T/C. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2011.
In situ compatibilization of PEN/LCP blends by ultrasonic extrusion
Authors: Gunes Kaan , Isayev Avraam I.
Published: April 2011

In situ compatibilization of immiscible blends of PEN and thermotropic LCP was achieved by the ultrasonically‐aided extrusion process. Ultrasonically‐treated PEN underwent degradation, leading to a decrease of its viscosity. Viscosity of LCP was unaffected by ultrasonic treatment. Because of reduced viscosity ratio of PEN to LCP at high amplitude of ultrasonic treatment, larger LCP domains were observed in molding of the blends. LCP acted as a nucleating agent, promoting higher crystallinity in PEN/LCP blends. Ultrasonically‐induced copolymer formation was detected by MALDI‐TOF mass spectrometry in the blends. Ultrasonic treatment of 90/10 PEN/LCP blends improved interfacial adhesion in fibers spun at intermediate draw down ratios (DDR), improving their ductility. The lack of improvement in the mechanical properties of fibers spun at high DDR after ultrasonic treatment was attributed to the disturbance of interfacial copolymer by high elongation stresses. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2011.
Bipolar Heteroleptic Green Iridium Dendrimers Containing Oligocarbazole and Oxadiazole Dendrons for Bright and Efficient Nondoped Electrophosphorescent Devices
Authors: Chen Lingcheng , Ding Junqiao , Cheng Yanxiang , Xie Zhiyuan , Wang Lixiang , Jing Xiabin , Wang Fosong
Published: April 2011

Bipolar heteroleptic green light‐emitting iridium (Ir) dendrimers G(OXD) and G(DOXD) have been designed and synthesized under mild conditions in high yields, in which the first C^N and second O^O ligands are functionalized with oligocarbazole‐ and oxadiazole‐based dendrons, respectively. To avoid affecting the optical properties of the emissive iridium core, all the functional moieties are attached to the ligands through a flexible spacer. Compared with the unipolar dendrimer G(acac), dendrimers G(OXD) and G(DOXD) exhibit the close emission maxima of 511–512 nm and photoluminescence quantum yield of 0.39–0.40 in a solution of toluene. Moreover, on going from G(acac) to G(OXD) and G(DOXD), we have found that the introduction of oxadiazole fragments decreases the lowest unoccupied molecular orbital (LUMO) energy levels to facilitate the electron injection and electron transporting, while their highest occupied molecular orbital (HOMO) energy levels remain unchanged. This means that, we can individually tune the HOMO and LUMO energy levels based on the heteroleptic structure to ensure the relative independence between the hole and electron in the emitting layer (EML), which is a favorable feature for bipolar optoelectronic materials. As a result, a bilayer nondoped electrophosphorescent device with G(DOXD) as the EML gives a maximum luminous efficiency of 25.5 cd A−1 (ηext: 7.4 %) and a brightness of 33 880 cd m−2. In comparison to G(acac) (17.2 cd A−1, 17 680 cd m−2), both the efficiency and brightness are improved by about 1.5 and 2 times, respectively. These state‐of‐the‐art performances indicate the potential of these bipolar heteroleptic iridium dendrimers as solution‐processible emitting materials for nondoped device applications.
Bioenergy feedstock‐specific enrichment of microbial populations during high‐solids thermophilic deconstruction
Authors: Reddy Amitha P. , Allgaier Martin , Singer Steven W. , Hazen Terry C. , Simmons Blake A. , Hugenholtz Philip , VanderGheynst Jean S.
Published: April 2011

Thermophilic microbial communities that are active in a high‐solids environment offer great potential for the discovery of industrially relevant enzymes that efficiently deconstruct bioenergy feedstocks. In this study, finished green waste compost was used as an inoculum source to enrich microbial communities and associated enzymes that hydrolyze cellulose and hemicellulose during thermophilic high‐solids fermentation of the bioenergy feedstocks switchgrass and corn stover. Methods involving the disruption of enzyme and plant cell wall polysaccharide interactions were developed to recover xylanase and endoglucanase activity from deconstructed solids. Xylanase and endoglucanase activity increased by more than a factor of 5, upon four successive enrichments on switchgrass. Overall, the changes for switchgrass were more pronounced than for corn stover; solids reduction between the first and second enrichments increased by a factor of four for switchgrass while solids reduction remained relatively constant for corn stover. Amplicon pyrosequencing analysis of small‐subunit ribosomal RNA genes recovered from enriched samples indicated rapid changes in the microbial communities between the first and second enrichment with the simplified communities achieved by the third enrichment. The results demonstrate a successful approach for enrichment of unique microbial communities and enzymes active in a thermophilic high‐solids environment. Biotechnol. Bioeng. 2011;108:2088–2098. © 2011 Wiley Periodicals, Inc.
Oxygen supply controls the onset of pristinamycins production by Streptomyces pristinaespiralis in shaking flasks
Authors: Mehmood N. , Olmos E. , Goergen J‐L. , Blanchard F. , Ullisch D. , Klöckner W. , Büchs J. , Delaunay S.
Published: April 2011

Antibiotics are secondary metabolites, generally produced during stationary phase of growth under different nutritional and hydrodynamic stresses. However, the exact mechanisms of the induction of antibiotics production are still not clearly established. In a previous study, the induction of pristinamycins production by Streptomyces pristinaespiralis as well as product concentrations were correlated with power dissipation per unit of volume (P/V) in shaking flasks. In this study, detailed kinetics of growth, substrate consumption, oxygen transfer rate and pristinamycins production under varying P/V conditions have been obtained and analyzed. Our results showed that higher P/V resulted in a higher concentration of biomass and promoted an earlier nutrient limitation and ultimately an earlier induction of pristinamycins production. The maximal specific growth rate, specific oxygen consumption rate and specific consumption rate of glutamate increased with P/V while influence was less marked with specific consumption rate of glucose, arginine, ammonium ions and phosphate. When oxygen uptake rate (OUR) was limited by free‐surface oxygen transfer, pristinamycins production was not detected despite the occurrence of nitrogen and/or phosphate sources limitation. The threshold value for OUR observed was around 25 mmol L−1 h−1. This suggested that a limitation in nitrogen and/or phosphate alone was not sufficient to induce pristinamycins production by S. pristinaespiralis pr11. To induce this production, the oxygen transfer had to be non‐limiting. Biotechnol. Bioeng. 2011;108:2151–2161. © 2011 Wiley Periodicals, Inc.
Saturation of transgene protein synthesis from mRNA in cells producing a large number of transgene mRNA
Authors: Takahashi Yuki , Nishikawa Makiya , Takiguchi Naomi , Suehara Tetsuya , Takakura Yoshinobu
Published: April 2011

Experimental results have suggested that transgene expression can be saturated when large amounts of plasmid vectors are delivered into cells. To investigate this saturation kinetic behavior, cells were transfected with monitoring and competing plasmids using cationic liposomes. Even although an identical amount of a monitoring plasmid expressing firefly luciferase (FL) was used for transfection, transgene expression from the plasmid was greatly affected by the level of transgene expression from competing plasmids expressing renilla luciferase (RL). Similar results were obtained by exchanging the monitoring and competing plasmids. The competing plasmid‐dependent reduction in transgene expression from the monitoring plasmid was also observed in mouse liver after hydrodynamic injection of plasmids. On the other hand, the mRNA and protein expression level of glyceraldehyde‐3‐phosphate dehydrogenase (GAPDH), an endogenous gene, in the liver hardly changed even when transgene expression process is saturated. The expression of FL from a monitoring plasmid was significantly restored by siRNA‐mediated degradation of RL mRNA that was expressed from a competing plasmid. These results suggest that the efficiency of protein synthesis from plasmid vectors is reduced when a large amount of mRNA is transcribed with no significant changes in endogenous gene expression. Biotechnol. Bioeng. 2011;108: 2380–2389. © 2011 Wiley Periodicals, Inc.
Kinetic modeling of light limitation and sulfur deprivation effects in the induction of hydrogen production with Chlamydomonas reinhardtii. Part II: Definition of model‐based protocols and experimental validation
Authors: Degrenne B. , Pruvost J. , Titica M. , Takache H. , Legrand J.
Published: April 2011

Photosynthetic hydrogen production under light by the green microalga Chlamydomonas reinhardtii was investigated in a torus‐shaped PBR in sulfur‐deprived conditions. Culture conditions, represented by the dry biomass concentration of the inoculum, sulfate concentration, and incident photon flux density (PFD), were optimized based on a previously published model (Fouchard et al., 2009. Biotechnol Bioeng 102:232–245). This allowed a strictly autotrophic production, whereas the sulfur‐deprived protocol is usually applied in photoheterotrophic conditions. Experimental results combined with additional information from kinetic simulations emphasize effects of sulfur deprivation and light attenuation in the PBR in inducing anoxia and hydrogen production. A broad range of PFD was tested (up to 500 µmol photons m−2 s−1). Maximum hydrogen productivities were 1.0 ± 0.2 mL H2/h/L (or 25 ± 5 mL H2/m2 h) and 3.1 mL ± 0.4 H2/h L (or 77.5 ± 10 mL H2/m2 h), at 110 and 500 µmol photons m−2 s−1, respectively. These values approached a maximum specific productivity of approximately 1.9 mL ± 0.4 H2/h/g of biomass dry weight, clearly indicative of a limitation in cell capacity to produce hydrogen. The efficiency of the process and further optimizations are discussed. Biotechnol. Bioeng. 2011;108: 2288–2299. © 2011 Wiley Periodicals, Inc.