bluuebunny/crossref_metadata_2025 huggingface dataset:
Three‐dimensional self‐assembling peptide matrix enhances the formation of embryoid bodies and their neuronal differentiation
Authors: Li Qianqian , Chow King L. , Chau Ying
Published: July 2013

We have tailored the properties of a self‐assembling peptide (SAP) matrix to direct embryonic stem cells towards neuronal differentiation by adopting a three‐dimensional (3D) culture, matching mechanical strength with that of neural tissue, and incorporating fixed laminin‐derived pentapeptide signals (IKVAV). We report here that such a matrix alone can induce mouse embryonic stem (ES) cells to first develop into embryoid body (EB) and increase their propensity for subsequent neuronal differentiation. Embryoid bodies were observed by day 5 of culture in SAP matrix. βIII‐tubulin as an early neuronal commitment marker was more prominently detected in cells cultured in the matrix containing IKVAV signals. Interestingly, ES‐derived cells did not display distinct neuron morphology within the 3D culture; however, 55 ± 10% of those cells within IKVAV conjugated matrix and 38 ± 6% of those within base matrix displayed higher potential towards neuronal differentiation after 7 days. When retrieved and recultured on a tissue culture plate, they exhibited extended neurite outgrowths and networks in the absence of any additional neuronal differentiation growth factor. The up‐regulated expression of neuronal development markers (MAP2 and MeCP2) and the down‐regulation of glial marker (GFAP) support that further neuronal differentiation takes place upon reculture. The results showed that an artificial matrix composed of designer SAPs could prompt the formation of EB and provides the cues favoring neuronal differentiation of ES cells. © 2013 Wiley Periodicals, Inc. J Biomed Mater Res Part A: 102A: 1991–2000, 2014.
Tissue response to composite hydrogels for vertical bone augmentation in the rat
Authors: Kinard Lucas A. , Dahlin Rebecca L. , Henslee Allan M. , Spicer Patrick P. , Chu Chia‐Ye , Tabata Yasuhiko , van den Beucken Jeroen J.J.P. , Jansen John A. , Young Simon , Wong Mark E. , Kasper F. Kurtis , Mikos Antonios G.
Published: July 2013

The objective of the present study was to develop a preclinical animal model for evaluating bone augmentation and to examine the level of bone augmentation induced by hydrogel composites. Design criteria outlined for the development of the animal model included rigid immobilization of bilateral implants apposed to the parietal bone of the rat, while avoiding the calvarial sutures. The animal model was evaluated through the implantation of hydrogel composites of oligo(poly(ethylene glycol) fumarate) (OPF) and gelatin microparticles releasing bone morphogenetic protein‐2 (BMP‐2). The BMP‐2 release profile was varied and compared to the implantation of a material control without BMP‐2. Each hydrogel composite was implanted within a polypropylene cassette, which was immobilized to the calvarial bone using screws, and empty cassettes were implanted as a control. The design criteria for the animal model were realized; however, the level of bone augmentation did not vary between any of the groups after 4 weeks. Osteoclastic bone resorption occurred to a higher extent in groups releasing BMP‐2, but the cause could not be elucidated. In conclusion, a promising bone augmentation model was established in the rat; however, refinement of the hydrogel composites was suggested to optimize the constructs for bone augmentation applications. © 2013 Wiley Periodicals, Inc. J Biomed Mater Res Part A: 102A: 2079–2088, 2014.
Uniaxial cyclic strain stimulates cell proliferation and secretion of interleukin‐6 and vascular endothelial growth factor of human dermal fibroblasts seeded on chitosan scaffolds
Authors: Park Ki‐Sook , Lee Eun‐Gyu , Son Youngsook
Published: July 2013

Human dermal fibroblasts were inoculated into chitosan sponge scaffolds coated with type I collagen and it might be developed as a dermal substitute and/or dressing material. The application of 14% uniaxial cyclic strain to the cellular scaffolds affected the characteristics of the seeded human dermal fibroblasts. Cyclic strain enhanced cellular proliferation, the activity of metalloproteinase‐2, and the expression of extracellular matrix proteins such as fibronectin. Moreover, cyclic strain increased the expression of vascular endothelial growth factor (VEGF) and interleukin (IL)−6, which are critical to wound healing. Even under static culture (strain, 0%) following 14% cyclic strain, the expression of VEGF and IL‐6, which had increased under 14% strain, was amplified or maintained for at least 3 days. Uniaxial cyclic strain may enhance the wound‐healing potential of human dermal fibroblasts seeded on chitosan scaffolds through the changes in the cellular characteristics of the fibroblasts when the cellular scaffold is transplanted into skin wounds, especially chronic wounds such as diabetic wounds. © 2013 Wiley Periodicals, Inc. J Biomed Mater Res Part A: 102A: 2268–2276, 2014.
Improved brain delivery of vincristine using dextran sulfate complex solid lipid nanoparticles: Optimization and in vivo evaluation
Authors: Aboutaleb Ehsan , Atyabi Fatemeh , Khoshayand Mohammad Reza , Vatanara Ali Reza , Ostad Seyed Nasser , Kobarfard Farzad , Dinarvand Rassoul
Published: July 2013

Vincristine (VC) sulfate, a freely water‐soluble cytotoxic agent was incorporated into cetyl palmitate solid lipid nanoparticles (SLNs) with the aid of dextran sodium sulfate (DS), a poly anion, using a microemulsion method. The manufacturing process was optimized using response surface methodology (Box–Behnken design). SLNs were characterized for size, zeta potential, morphology, crystallinity, and release behavior. The drug encapsulation efficiency reached up to 93% and release study revealed sustained drug release. SLN formulation showed comparable cytotoxic effect in comparison to VC sulfate solution against the MDA‐MB‐231 cells. The in vivo studies following injection to rat revealed higher plasma and tissue concentrations and longer drug mean residence times compared to VC solution. Using cumarin‐6 as a model drug, it was shown that drug delivery to the brain was enhanced close to five times using SLNs prepared in this study compared to free cumarin‐6. It can be concluded that complexes of cetyl palmitate SLNs with DS could produce high VC‐loaded SLNs suitable for delivery of anticancer drugs to brain tumors. © 2013 Wiley Periodicals, Inc. J Biomed Mater Res Part A: 102A: 2125–2136, 2014.
Effect of doping in carbon nanotubes on the viability of biomimetic chitosan‐carbon nanotubes‐hydroxyapatite scaffolds
Authors: Fonseca‐García Abril , Mota‐Morales Josué D. , Quintero‐Ortega Iraís A. , García‐Carvajal Zaira Y. , Martínez‐López V. , Ruvalcaba Erika , Landa‐Solís Carlos , Solis Lilia , Ibarra Clemente , Gutiérrez María C. , Terrones Mauricio , Sanchez Isaac C. , del Monte Francisco , Velasquillo María C. , Luna‐Bárcenas G.
Published: July 2013

This work describes the preparation and characterization of biomimetic chitosan/multiwall carbon nanotubes/nano‐hydroxyapatite (CTS/MWCNT/nHAp) scaffolds and their viability for bone tissue engineering applications. The cryogenic process ice segregation‐induced self‐assembly (ISISA) was used to fabricate 3D biomimetic CTS scaffolds. Proper combination of cryogenics, freeze‐drying, nature and molecular ratio of solutes give rise to 3D porous interconnected scaffolds with clusters of nHAp distributed along the scaffold surface. The effect of doping in CNT (e.g. with oxygen and nitrogen atoms) on cell viability was tested. Under the same processing conditions, pore size was in the range of 20–150 μm and irrespective on the type of CNT. Studies on cell viability with scaffolds were carried out using human cells from periosteum biopsy. Prior to cell seeding, the immunophenotype of mesenchymal periosteum or periosteum‐derived stem cells (MSCs‐PCs) was characterized by flow cytometric analysis using fluorescence‐activated and characteristic cell surface markers for MSCs‐PCs. The characterized MSCs‐PCs maintained their periosteal potential in cell cultures until the 2nd passage from primary cell culture. Thus, the biomimetic CTS/MWCNT/nHAp scaffolds demonstrated good biocompatibility and cell viability in all cases such that it can be considered as promising biomaterials for bone tissue engineering. © 2013 Wiley Periodicals, Inc. J Biomed Mater Res Part A: 102A: 3341–3351, 2014.
Formation of thermo‐sensitive polyelectrolyte complex micelles from two biocompatible graft copolymers for drug delivery
Authors: Li Guiying , Meng Yanfeng , Guo Lei , Zhang Ting , Liu Junshen
Published: July 2013

Thermo‐sensitive polyelectrolyte complex (PEC) micelles assembled from two biocompatible graft copolymers chitosan‐g‐poly(N‐isopropylacrylamide) (CS‐g‐PNIPAM) and carboxymethyl cellulose‐g‐poly(N‐isopropylacrylamide) (CMC‐g‐PNIPAM) were prepared for delivery of 5‐fluorouracil (5‐FU). The PEC micelles showed a narrow size distribution with core‐shell structure, in which the core formed from positively charged CS and negatively charged CMC by electrostatic interactions and the shell formed from thermo‐sensitive PNIPAM. The synthesized PEC micelles have lower critical solution temperatures (LCST) in the region of 37°C, which is favorable for smart drug delivery applications. The hydrogen bondings between PEC micelles and 5‐FU increased the drug loading. Changing temperature, pH or ionic strength, a sustained and controlled release was observed due to the deformation of PEC micelles. Adding glutaraldehyde, a chemical crosslinking reagent, was an efficient way to reinforce the micelles structure and decrease the initial burst release. Cytotoxicity assays showed that drug‐loaded PEC micelles retained higher cell inhibition efficiency in HeLa cells. © 2013 Wiley Periodicals, Inc. J Biomed Mater Res Part A: 102A: 2163–2172, 2014.
Biosynthetic hydrogels—Studies on chemical and physical characteristics on long‐term cellular response for tissue engineering
Authors: Thankam Finosh Gnanaprakasam , Muthu Jayabalan
Published: July 2013

Biosynthetic hydrogels can meet the drawbacks caused by natural and synthetic ones for biomedical applications. In the current article we present a novel biosynthetic alginate ‐ poly(propylene fumarate) copolymer based chemically crosslinked hydrogel scaffolds for cardiac tissue engineering applications. Partially crosslinked PA hydrogel and fully cross linked PA‐A hydrogel scaffolds were prepared. The influence of chemical and physical (morphology and architecture of hydrogel) characteristics on the long term cellular response was studied. Both these hydrogels were cytocompatible and showed no genotoxicity upon contact with fibroblast cells. Both PA and PA‐A were able to resist deleterious effects of reactive oxygen species and sustain the viability of L929 cells. The hydrogel incubated oxidative stress induced cells were capable of maintaining the intra cellular reduced glutathione (GSH) expression to the normal level confirmed their protective effect. Relatively the PA hydrogel was found to be unstable in the cell culture medium. The PA‐A hydrogel was able to withstand appreciable cyclic stretching. The cyclic stretching introduced complex macro and microarchitectural features with interconnected pores and more structured bound water which would provide long‐term viability of around 250% after the 24th day of culture. All these qualities make PA‐A hydrogel form a potent candidate for cardiac tissue engineering. © 2013 Wiley Periodicals, Inc. J Biomed Mater Res Part A: 102A: 2238–2247, 2014.
Polyethyleneimine Solubilized Luminescent Au(I)‐Thiolate Complexes for Highly Sensitive and Selective Cyanide Anion Sensing
Authors: Du Yi , Yuan Zhiqin , Xu Dong , Cai Na , He Yan , Yeung Edward S.
Published: July 2013

Cyanide (CN−) is a highly toxic anion to human beings, exploring efficient probes for sensitive and selective detection of it is very important. In this study, we explore a simple one‐pot reaction to synthesize polyethyleneimine (PEI) solubilized Au(I)‐MUA (11‐mercaptoundecanoic acid) complexes under mild condition. The as prepared Au(I)‐MUA complexes exhibit strong red photoluminescence (PL) and can act as sensitive and selective CN− optical sensor in aqueous media based on the chemical reaction between CN− and gold atom that quench the fluorescence, and the limit of detection is 10 nM, which is ∼270 times lower than the maximum contamination level (2.7 μM) in drinking water permitted by WHO. Additionally, real water sample from a local lake is tested with these optical sensors, and the PL variation caused by 0.1 μ CN− can be observed.
Exergy as a tool for measuring process intensification in chemical engineering
Authors: Luis Patricia
Published: July 2013

Exergy is defined as the maximum shaft work that can be done in a process to bring the system into equilibrium with the environment. Thus, exergy analyses are the first step to understand where the weak points of processes are. It considers intrinsically the quality of energy: when energy loses its quality, exergy is destroyed. In addition, optimization of processes aiming at the minimization of exergy destruction can be done as a function of the topology and physical characteristics of the system, such as finite dimensions, shapes, materials, finite speeds, and finite‐time intervals of operation, establishing a direct relationship between exergy and process intensification. However, the emphasis on exergy in chemical engineering is still very poor compared with other fields, in spite of being one of the areas in which more exergy is destroyed due to reaction and separation.

This paper gives an overview of the current application of exergy analyses in chemical engineering, showing the main fields in which exergy studies are performed and focusing the attention on two critical points of action: separation technologies (distillation and membrane technology) and CO2 capture. New research trends in chemical engineering using exergy as a tool for process intensification are highlighted. © 2013 Society of Chemical Industry
Theoretical tools for studies of low‐frequency thermospheric variability
Authors: Picone J. M. , Meier R. R. , Emmert J. T.
Published: July 2013

This paper supports studies of low‐frequency variability (LFV) within the thermosphere by deriving approximate integral and closed‐form solutions of a nontrivial model of thermospheric temperature, density, and composition depending on altitude and time. We also provide a paradigm for applying dimensional analysis in such studies. The domain is the region between the mesopause and the exobase. The solutions emphasize the connectedness of the thermosphere, i.e., nonlocal influences of LFV in key physical parameters and phenomena. The present focus is seasonal variability, within which the origin of a sizable semiannual variation in the thermosphere remains under active investigation. Following from the thermodynamic differential equation for temperature is a filtered, integral solution consistent with the Π theorem of dimensional analysis. A key result is the explicit demonstration that lower thermospheric boundary conditions affect low‐frequency variability throughout the thermosphere, making accurate boundary conditions essential to modeling LFV. In addition, LFV of the temperature varies inversely with variability of the net heating profile and has directly and inversely proportional contributions from variations in the thermal conductivity profile, which can include an “eddy diffusivity” component. Given a temperature profile, diffusive equilibrium defines model composition. For rapid calculations and transparency, we develop an approximate, closed‐form solution for temperature, density, and composition depending only on a minimal set of observable parameters, and from that, we demonstrate the essential role of the phase and amplitude profile of the temperature LFV in determining the corresponding profile of variability in composition and density.
Upper mantle compositional variations and discontinuity topography imaged beneath Australia from Bayesian inversion of surface‐wave phase velocities and thermochemical modeling
Authors: Khan A. , Zunino A. , Deschamps F.
Published: July 2013

Here we discuss the nature of velocity heterogeneities seen in seismic tomography images of Earth's mantle whose origins and relation to thermochemical variations are yet to be understood. We illustrate this by inverting fundamental‐mode and higher‐order surface‐wave phase velocities for radial models of the thermochemical and anisotropic structure of the mantle to 450 km depth. Dispersion data are linked to thermochemical parameters through a thermodynamic formalism for computing mantle mineral phase equilibria and physical properties. The inverse problem is solved using a probabilistic inference approach whereby robust uncertainty estimates are obtained. We find that both compositional and thermal anomalies are required if observations are to be satisfied. Mantle thermochemical variations extend to 250 km depth beneath western and central Australia and are characterized by increased Mg/Fe and Mg/Si values relative to surrounding mantle. Correlated herewith are thermal variations that closely follow surface tectonics. We also observe a strong contribution to lateral variations in structure and topography across the “410 km” seismic discontinuity from thermochemically induced phase transformations that appear much stronger than lateral variations immediately above and below. Inside the transition zone, a general decoupling of structure relative to that of the upper mantle occurs driven by a reversal in Mg/Si, while thermal anomalies are smoothed out. Comparison of presently derived shear‐wave tomography models with other regional models is encouraging. Radial anisotropy is strongest at 150/200 km depth beneath oceanic/continental areas, respectively, and appears weak and homogeneous below. Finally, geoid anomalies are computed for a subset of sampled model and compared to observations.
Evaluation of single field‐of‐view cloud top height retrievals from hyperspectral infrared sounder radiances with CloudSat and CALIPSO measurements
Authors: Yao Zhigang , Li Jun , Weisz Elisabeth , Heidinger Andrew , Liu Chian‐Yi
Published: July 2013

Accurate cloud top height retrievals from hyperspectral infrared (IR) sounder radiances are needed for weather and climate prediction. To account for the nonlinearity of the cloud parameters with respect to the IR radiances, a one‐dimensional variational retrieval algorithm is used to derive the cloud top heights (CTHs) from the Atmospheric Infrared Sounder (AIRS) radiances on a single field‐of‐view basis. The CTHs are evaluated by comparison with the measurements from radar and lidar instruments onboard the Earth Observing System (EOS) CloudSat and Cloud‐Aerosol Lidar and Infrared Pathfinder Satellite Observation (CALIPSO) satellites. Using the retrievals from a global 3 day dataset, it is found that the variational algorithm compared with the regression algorithm could reduce the variability of the difference between the AIRS and active measurements by 1 km. And the biases of AIRS CTHs range from +1.5 to −1.4 km and from +1.6 to −3.8 km, depending on the Cloud Profiling Radar (CPR) and CALIPSO CTHs between 3 and 18 km, respectively. Globally, the AIRS CTH is overestimated (underestimated) when the CTH from active measurements is below (above) 5 km. The bias decreases from −1.9 to −0.8 km, and the variability decreases from 2.8 to about 1.6 km with the increase of the CALIPSO cloud optical thickness from 0.1 to 2.5. It also reveals that the AIRS CTHs agree better with the CPR than the CALIPSO.
On Maximum Edge Cuts of Connected Digraphs
Authors: Chen Guantao , Gu Manzhan , Li Nana
Published: July 2013

A set F of edges in a digraph D is called a directed cut if there exists a nontrivial partition of such that F consists of all directed edges from X to Y. Let denote the maximum size of a directed cut of D, and let be the set of all digraphs D such that or for any vertex v in D. We show that for any connected digraph , which provides a positive answer to a problem of Lehel, Maffray, and Preissmann. Additionally, we consider triangle‐free digraphs in and answer another question of theirs.
How transformational leadership influences follower helping behavior: The role of trust and prosocial motivation
Authors: Zhu Yue , Akhtar Syed
Published: July 2013

We proposed and tested a moderated mediation model that jointly examines affect‐based and cognition‐based trust as the mediators and prosocial motivation as the moderator in relationships between transformational leadership and followers’ helping behavior towards coworkers. Data were collected from 348 sales and servicing employees and their supervisors in four private retail companies and five private manufacturing companies located in Southeast China. The results showed that both affect‐based trust and cognition‐based trust mediated the relationship between transformational leadership and followers’ helping behavior towards coworkers. Furthermore, moderated mediation analyses showed that affect‐based trust mediated the relationship between transformational leadership and followers’ helping behavior towards coworkers only among employees with high prosocial motivation, whereas cognition‐based trust mediated this relationship among only those with low prosocial motivation. Implications for the theory and practice of leadership are then discussed. Copyright © 2013 John Wiley & Sons, Ltd.
Interpolation of temperature in a mountainous region using nonlinear profiles and non‐Euclidean distances
Authors: Frei Christoph
Published: July 2013

In mountain regions, the distribution of surface air temperature happens to show marked horizontal gradients and nonlinear variations with topographic height. These pose a major challenge for the construction of area‐wide temperature datasets on a regular grid. This study introduces a new deterministic method's for the spatial interpolation of daily temperature from station measurements. Building on a scale‐separation concept, the methods main features are (1) a nonlinear parametric function to model nonlinearities in the vertical thermal profile at the scale of major basins, and (2) a distance weighting scheme with a non‐Euclidean metric that accounts for terrain effects on the spatial representativity of measurements. The method is configured for the territory of Switzerland (European Alps) and is applied for the construction of a km‐scale grid dataset from 70‐100 stations over all days from 1961 to 2010. Several illustrative cases attest the method's potential, also under challenging conditions. Temperature patterns from basin‐scale inversions and surface heated/cooled boundary layers are realistically reproduced. In situations with valley‐scale cold‐air pools and foehn, the method is less prone to artificial upslope/downslope extrapolation often observed with other techniques. With a network of 100 stations in Switzerland, typical interpolation errors (mean absolute error MAE, cross‐validation) range from 0.5 °C over flat and hilly terrain in summer to 1.5 °C in the Alps in winter. Larger and partly systematic errors (MAE ≥ 3 °C) must be expected in un‐sampled valleys in winter due to the missing out of local‐scale cold pools. Interpolation accuracy was found to vary with the change in station density over time, demonstrating improvements in the overall representativity of the measurement network. But this also compromises the long‐term homogeneity of the grid dataset, despite it being based on homogeneous records. The presented method may be applicable in other mountain regions after some configuration.
Long‐term analysis of heat waves in Ukraine
Authors: Shevchenko Olga , Lee Hyunjung , Snizhko Sergiy , Mayer Helmut
Published: July 2013

In the past few decades, severe heat waves were representative of the weather conditions in various parts of the world. They had distinctly negative impacts on humans, plants, animals and different economic sectors. Particularly in cities, where most humans are living, their well‐being, efficiency and health were affected, which even caused a relatively high mortality rate. This is why a large interest still exists to analyse heat waves in the past by use of statistical methods.

As an investigation on heat waves is not available for the territory of Ukraine up to now, a retrospective analysis was conducted. Its main aims were (1) to determine the frequency of heat wave episodes for this country and (2) to analyse their spatiotemporal distribution, duration and intensity. On the basis of 13 selected stations of the meteorological network of the Ukrainian Hydrometeorological Centre, daily values of maximum air temperature (Ta,max) in the summer months June to August were used to determine heat wave episodes according to the definition recommended by the IPCC. For all stations, complete and reliable Ta,max time series were available for the period 1951–2011. With respect to some stations, the Ta,max time series already started some years earlier, e.g. in 1936 for five stations and even in 1911 for four stations. However, the Ta,max time series of almost all stations had gaps in the summer months before 1951, particularly in the 1940s of the 20th century. As they could not be filled in a satisfying way, this limitation was considered in the data analysis.

The results indicate that most of the heat wave episodes occurred at stations located in Eastern Ukraine. In contrast to other decades, the number of heat wave episodes was highest for almost all stations in the decade 2001–2010. The fewest heat wave episodes were determined for the two decades 1961 to 1980. The longest heat wave duration varied between 7 d in Henichesk (southern seashore) and 24 d in Lugansk (Eastern Ukraine). For many stations, the longest heat wave duration occurred in the first two decades of August 2010, i.e. in the period of the extremely severe heat wave in Western Russia.

The intensity of heat waves was analysed by use of the cumulative Ta,max excess. The results show that heat waves of the longest duration mostly represented the strongest heat waves. The 24‐d heat wave 2010 in Lugansk was the strongest in the investigation period quantified by a cumulative Ta,max excess of 128 °C.
Enzyme Modification of Grain By‐products and Their Biocomposites: Characterization, Mechanical and Thermal Properties
Authors: Mamun Abdullah Al , Bledzki Andrzej Korneliusz
Published: July 2013

Rice husk‐ and wheat husk (W)‐reinforced polylactide composites are fabricated using a high‐speed mixer followed by an injection molding process with a fiber load of 40 wt%. Prior to composite production, the husks are modified using a mixture of enzymes. The enzyme modification processing parameters, such as the temperature, duration, and enzyme concentration are optimised. The modified husks are characterised using FT‐IR spectroscopy and scanning electron microscopy in order to observe the changes in the fiber surfaces and particle sizes. The moisture absorption properties of modified and unmodified husks are also observed. The following properties of the resulting composites are characterized: tensile, flexural, impact strength, energy absorption, dynamic‐mechanical and odor emission properties. The properties of husk‐reinforced polylactide composites are compared with those of soft‐wood fiber composites.
Projections and Policies for Volunteer Programs: The Implications of the Serve America Act for Volunteer Diversity and Management
Authors: Nesbit Rebecca , Brudney Jeffrey L.
Published: July 2013

This article explores the limits of public policy as it affects volunteerism in the United States. Our analysis focuses on the potential of the Edward M. Kennedy Serve America Act (2009), the most sweeping volunteer legislation in U.S. history, to raise the level of volunteering and national service in the United States, particularly among young people, older people, and minorities—the primary target populations of the act. The Serve America Act aims to increase service‐learning opportunities and national service placements substantially. However, the long‐term impact of these changes on the rate of volunteering and the composition and character of the volunteering population remains unclear. Using data from the Current Population Survey's annual Supplement on Volunteering, we examine a variety of reasonable policy scenarios to see how the Serve America Act might affect future volunteering through the year 2050. The findings suggest that even if the Serve America Act is fully funded and implemented, it is unlikely to have a long‐term impact on the overall volunteering rate and, consequently, that altering the national volunteering rate might be an unrealistic public policy goal. Nevertheless, the analysis shows that because of naturally occurring changes in the population, the composition of the volunteer pool is likely to change as we move toward 2050—a demographic shift that will present increased challenges for volunteer managers. We discuss these challenges and how managers might deal with them effectively.
Agency Problems between Managers and Employees in Nonprofit Organizations: A Discrete Choice Experiment
Authors: Van Puyvelde Stijn , Caers Ralf , Du Bois Cind , Jegers Marc
Published: July 2013

Most principal–agent literature of nonprofit organizations has focused on the relationship between board members and managers. However, in addition to the role as an agent of the board, the manager also performs a role as principal with respect to the nonprofit employees. By using a discrete choice experiment, we identify the objectives of managers and employees in nonprofit organizations and assess the presence of agency problems in this relationship. Our sample consists of 76 headmasters, 161 teachers, and 39 administrative employees in 74 secondary nonprofit schools in Belgium. We find that the six objectives set out in the experiment play an important role for both headmasters and subordinate staff. However, the results also indicate that some of these objectives are significantly more important for the headmasters. In sum, our results suggest that agency theory and stewardship theory are not necessarily in conflict with each other but can be combined into a more general governance framework for nonprofit organizations. Consequently, we argue that incentive structures that incorporate different types of objectives can facilitate the recruitment and retention of employees in nonprofit organizations.
Bioarchaeological Analysis of a Royal Burial from the Oldest Maya Tomb in Palenque, Mexico
Authors: Couoh L. R.
Published: July 2013

In 1957, a new discovery inside Temple XVIII‐A was made in Palenque, the Mayan archaeological site in Chiapas Mexico, a royal tomb of an original design which proved to be the oldest at the site. Two skeletons were found, the principal (PAL‐44) was at the centre showing red pigmentation on the surface of some bones, personal adornments and offerings, which indicate that he was an early ruler of Palenque. The second (PAL‐45), deposited at the entrance, not in a special mortuary position, without offerings, suggests it was of a lower social status. This research presents a new bioarchaeological analysis with the following results: (i) The result of a direct radiocarbon dating of PAL‐44 by accelerator mass spectrometry is 250–420 cal AD (LTL12759A:1696 ± 30 BP). This means that the personage was buried long before the first designated ruler of Palenque, who, according to the epigraphic record was enthroned in ad 431. (ii) With X‐Ray Fluorescence, the red pigment was identified as cinnabar (HgS). (iii) PAL‐44 is a young adult male with a severe idiopathic scoliosis with a double curvature that affected the ribcage and lower limbs. Such a three‐dimensional deformity resulted in changes to his body mechanics and induced motion asymmetry. Consequently, his health and mobility must have been significantly affected by such a severe condition. (iv) PAL‐45 is an adult female with signs of nutritional problems in childhood and entheseal changes probably related to her activity. Three ante‐mortem traumas are registered: rib fracture, frontal depressed circular fracture and a nasal septal deviation. This traumatic event took place two weeks, approximately, prior to PAL‐45's death. Copyright © 2013 John Wiley & Sons, Ltd.
Stage‐specific insecticidal characteristics of a nucleopolyhedrovirus isolate from Chrysodeixis chalcites enhanced by optical brighteners
Authors: Bernal Alexandra , Simón Oihane , Williams Trevor , Caballero Primitivo
Published: July 2013

Background

Chrysodeixis chalcites is a major noctuid pest of banana crops in the Canary Islands. The stage‐specific susceptibility of this pest to C. chalcites single nucleopolyhedrovirus (ChchSNPV‐TF1) was determined, as well as the effect of selected optical brighteners as enhancers of primary infection.

Results

Susceptibility to ChchSNPV‐TF1 occlusion bodies (OBs) decreased as larval stage increased; second instars (L2) were 10 000‐fold more susceptible than sixth instars (L6). Virus speed of kill was 42 h faster in L2 than in L6. OB production increased in late instars; L6 larvae produced 23‐fold more OBs than L4. Addition of 10 mg mL−1 Tinopal enhanced OB pathogenicity by 4.43‐ to 397‐fold depending on instar, whereas 10 µL mL−1 Leucophor resulted in potentiation of OB pathogenicity from 1.46‐ to 143‐fold. Mean time to death decreased by 14 to 26 h when larvae consumed OBs in mixtures with 10 mg mL−1 Tinopal, or 10 µL mL−1 Leucophor, although in these treatments OB yields were reduced by up to 8.5‐fold (Tinopal) or up to 3.8‐fold (Leucophor).

Conclusion

These results have clear applications for the use of ChchSNPV‐TF1 as a biological insecticide in control programs against C. chalcites in the Canary Islands. © 2013 Society of Chemical Industry
A Rhodiola Rosea Root Extract Protects Skeletal Muscle Cells Against Chemically Induced Oxidative Stress by Modulating Heat Shock Protein 70 (HSP70) Expression
Authors: Hernández‐Santana Aaron , Pérez‐López Verónica , Zubeldia Jose María , Jiménez‐del‐Rio Miguel
Published: July 2013

Rhodiola rosea is a perennial plant in the Crassulaceae family, recently postulated to exert its adaptogenic functions partially by modulating the expression of molecular factors such as heat shock proteins (HSP). The aim of this study was to analyze the efficacy of a Rhodiola rosea extract (Rhodiolife) in protecting murine skeletal muscle cells (C2C12 myotubes) from chemically induced oxidative stress and to establish whether modulation of HSP70 expression is observed. C2C12 cells treated with Rhodiolife did not experience any loss of viability (p > 0.05) at concentrations of 1–100 µg/mL for up to 24 h. In control cultures, viability decreased 25% following exposure to 2 mM H2O2 (1 h). However, no significant decrease in viability in cells pre‐treated with extract at concentrations as low as 1 µg/mL was observed. HSP70 mRNA levels were up‐regulated two‐fold in cell cultures treated with Rhodiolife (10 µg/mL), and expression was further enhanced by exposure to H2O2 (six‐fold, p < 0.05). HSP70 protein levels were maintained in pre‐treated cell cultures compared to controls but was significantly lower (−50%) in cells lacking treatment exposed to H2O2. The present results indicate that Rhodiolife protects C2C12 myotubes against peroxide‐induced oxidative stress through the modulation of the molecular chaperone HSP70. Copyright © 2013 John Wiley & Sons, Ltd.
Performance analysis of experimental‐scale scramjet engine driven DCW‐MHD generator
Authors: Takahashi Toru , Fujino Takayasu , Ishikawa Motoo
Published: July 2013

Numerical analyses of the experimental‐scale scramjet engine driven magnetohydrodynamics generator implemented in the Hypersonic Vehicle Electric Power System project have been carried out to clarify plasma behaviors and power generation characteristics. Three‐dimensional numerical analyses have been performed under the two inlet conditions: one is the uniform inlet temperature condition, and the other is the nonuniform inlet temperature condition. Under the nonuniform inlet temperature condition, the generator performance approximately agrees with the experimental result. The tendency of the voltage loss is also reconstructed near the power takeoff electrodes though the voltage loss is smaller than that observed in the experimental result. The electric power output under the nonuniform inlet temperature condition is 40% smaller than that under the uniform inlet temperature condition. This is because the ratio of the Joule dissipation to the work by the Lorentz force increases owing to the decrease of active generator region as the current concentrates in the high‐temperature region when the inlet temperature nonuniformity is considered. © 2013 Institute of Electrical Engineers of Japan. Published by John Wiley & Sons, Inc.
Fabricated Micro‐Nano Devices for In vivo and In vitro Biomedical Applications
Authors: Barkam Swetha , Saraf Shashank , Seal Sudipta
Published: July 2013

In recent years, the innovative use of microelectromechanical systems (MEMSs) and nanoelectromechanical systems (NEMSs) in biomedical applications has opened wide opportunities for precise and accurate human diagnostics and therapeutics. The introduction of nanotechnology in biomedical applications has facilitated the exact control and regulation of biological environments. This ability is derived from the small size of the devices and their multifunctional capabilities to operate at specific sites for selected durations of time. Researchers have developed wide varieties of unique and multifunctional MEMS/NEMS devices with micro and nano features for biomedical applications (BioMEMS/NEMS) using the state of the art microfabrication techniques and biocompatible materials. However, the integration of devices with the biological milieu is still a fundamental issue to be addressed. Devices often fail to operate due to loss of functionality, or generate adverse toxic effects inside the body. The in vitro and in vivo performance of implantable BioMEMS such as biosensors, smart stents, drug delivery systems, and actuation systems are researched extensively to understand the interaction of the BioMEMS devices with physiological environments. BioMEMS developed for drug delivery applications include microneedles, microreservoirs, and micropumps to achieve targeted drug delivery. The biocompatibility of BioMEMS is further enhanced through the application of tissue and smart surface engineering. This involves the application of nanotechnology, which includes the modification of surfaces with polymers or the self‐assembly of monolayers of molecules. Thereby, the adverse effects of biofouling can be reduced and the performance of devices can be improved in in vivo and in vitro conditions. WIREs Nanomed Nanobiotechnol 2013, 5:544–568. doi: 10.1002/wnan.1227

This article is categorized under:

Diagnostic Tools > Biosensing

Diagnostic Tools > Diagnostic Nanodevices

Nanotechnology Approaches to Biology > Nanoscale Systems in Biology
Selective enrichment and production of highly urease active bacteria by non-sterile (open) chemostat culture
Authors: Cheng Liang , Cord-Ruwisch Ralf
Published: July 2013

In general, bioprocesses can be subdivided into naturally occurring processes, not requiring sterility (e.g., beer brewing, wine making, lactic acid fermentation, or biogas digestion) and other processes (e.g., the production of enzymes and antibiotics) that typically require a high level of sterility to avoid contaminant microbes overgrowing the production strain. The current paper describes the sustainable, non-sterile production of an industrial enzyme using activated sludge as inoculum. By using selective conditions (high pH, high ammonia concentration, and presence of urea) for the target bacterium, highly active ureolytic bacteria, physiologically resembling Sporosarcina pasteurii were reproducibly enriched and then continuously produced via chemostat operation of the bioreactor. When using a pH of 10 and about 0.2 M urea in a yeast extract-based medium, ureolytic bacteria developed under aerobic chemostat operation at hydraulic retention times of about 10 h with urease levels of about 60 μmol min−1 ml−1 culture. For cost minimization at an industrial scale the costly protein-rich yeast extract medium could be replaced by commercial milk powder or by lysed activated sludge. Glutamate, molasses, or glucose-based media did not result in the enrichment of ureolytic bacteria by the chemostat. The concentration of intracellular urease was sufficiently high such that the produced raw effluent from the reactor could be used directly for biocementation in the field.
Local responses to macro development policies and their effects on rural system in China’s mountainous regions: the case of Shuanghe Village in Sichuan Province
Authors: Li Yu-rui , Liu Yan-sui , Long Hua-lou , Wang Jie-yong
Published: July 2013

China has promulgated a series of policies including the Western Development Program, the Grain for Green Project, agricultural support policies and building a new countryside strategy to eliminate east-west differences and urban-rural disparities since the late 1990s. This paper gives a holistic examination on local responses to the four typical macro socio-economic development policies and their effects on rural system based on a case study of a mountainous village in southern Sichuan Province. The results showed that the policies have not moved the case study village from its historically marginal status. To some extent, its socio-economic situation might have been worsened by accelerated out-migration of the youth, loss of agricultural land due to afforestation and industrial plants, increased fire hazard due to afforestation and reforestation, increased environmental pollution due to industrial enterprises attracted to the village and a steep decline in agricultural production due to loss of and inefficient use of cultivated land. Factors causing local villages’ dilemmas include the nonuniformity of actors’ objectives, finiteness of villagers’ abilities, and the imperfect incentive and restraint mechanism for local government’s activities under existing policy framework composed of uncoordinated one-size-fits-all policies. We suggest that China’s rural policy in the new period should gradually shift from a sectoral to a place-based one, from top-down incentives to the development of bottom-up projects, and fully recognize the diversity of rural space, so as to lift local capacities and make good use of the knowledge shared by different actors. Moreover, it is also necessary to integrate the various sectoral policies, and improve the interministerial and interdepartmental coordination of rural policies at regional and local levels.
Degradation of wetlands on the Qinghai-Tibet Plateau: A comparison of the effectiveness of three indicators
Authors: Gao Jay , Li Xi-lai , Cheung Alan , Yang Yuan-wu
Published: July 2013

The Qinghai-Tibet Plateau encompasses a large quantity of wetlands, some of which have been degraded to varying severity levels. In the literature, a number of degradation indicators have been proposed to evaluate ecological health of wetlands, but their effectiveness in the plateau environment remains unknown. In this study, we assessed the effectiveness of three degradation indicators, soil moisture content at 10 cm deep, vegetative cover, and density of pika burrows. The degradation severity of wetlands in Maduo County on the Qinghai-Tibet Plateau is enumerated at four levels, intact, slight, moderate and severe. Analysis of 106 samples collected in the field demonstrates that the density of pika burrows is the least reliable indicator. By comparison, vegetative cover and underlying soil moisture content are more reliable, even though neither is a perfect indicator as the difference among adjacent levels of severity as revealed by t-test is not always statistically significant. The imperfection of vegetative cover as an indicator is due to its variation among different types of wetlands. The limitation of moisture content is attributed to its non-linear relationship with wetland degradation. Above the threshold of about 50% in moisture content wetlands are unlikely to be degraded. It is recommended that moisture be measured at the point near the surface and vegetative cover be further differentiated by species in order to improve their effectiveness.
The Removal of Thermally Aged Films of Triacylglycerides by Surfactant Solutions
Authors: Dunstan Timothy S. , Fletcher Paul D. I.
Published: July 2013

Thermal ageing of triacylglycerides (TAG) at high temperatures produces films which resist removal using aqueous surfactant solutions. We used a mass loss method to investigate the removal of thermally aged TAG films from hard surfaces using aqueous solutions of surfactants of different charge types. It was found that cationic surfactants are most effective at high pH, whereas anionics are most effective at low pH and a non‐ionic surfactant is most effective at intermediate pH. We showed that the TAG film removal process occurs in several stages. In the first “lag phase” no TAG removal occurs; the surfactant first partitions into the thermally aged film. In the second stage, the TAG film containing surfactant was removed by solubilisation into micelles in the aqueous solution. The effects of pH and surfactant charge on the TAG removal process correlate with the effects of these variables on the extent of surfactant partitioning to the TAG film and on the maximum extent of TAG solubilisation within the micelles. Additionally, we showed how the TAG removal is enhanced by the addition of amphiphilic additives such as alcohols which act as co‐surfactants. The study demonstrates that aqueous surfactant solutions provide a viable and more benign alternative to current methods for the removal of thermally aged TAG films.
Theoretical and Experimental Studies for Corrosion Inhibition Performance of Q235 Steel by Imidazoline Inhibitors against CO2 Corrosion
Authors: Zhang Jing , Niu Longwei , Zhu Fengmin , Li Chengjie , Du Min
Published: July 2013

The inhibition performance of two imidazoline inhibitors, 1‐(2‐thioureaethyl)‐2‐alkyl‐imidazoline (TAI) and chloride‐1‐(2,3‐dihydroxylpropyl)‐1‐(2‐thioureaethyl)‐2‐alkyl‐imidazoline sodium phosphate (TAIP), for Q235 steel in saltwater saturated with CO2 was studied by using molecular dynamics simulations and quantum chemistry calculations. The conclusions were experimentally verified by weight loss, polarization curves, electrochemical impedance spectroscopy (EIS) and surface analysis techniques. The theoretical results suggest that imidazoline ring and heteroatoms are the active site and the adsorption stability weakens gradually in the order of TAIP, TAI. Experimental results show that the two inhibitors act as mixed type inhibitors and can inhibit the corrosion of Q235 in CO2 saturated saltwater solution.
A Trichome‐Specific Linoleate Lipoxygenase Expressed During Pyrethrin Biosynthesis in Pyrethrum
Authors: Ramirez Aldana M. , Yang Ting , Bouwmeester Harro J. , Jongsma Maarten A.
Published: July 2013

The lipid precursor alcohols of pyrethrins—jasmolone, pyrethrolone and cinerolone—have been proposed as sharing parts of the oxylipin pathway with jasmonic acid. This implies that one of the first committed steps of pyrethrin biosynthesis is catalyzed by a lipoxygenase, catalyzing the hydroperoxidation of linolenic acid at position 13. Previously, we showed that the expression and activity of chrysanthemyl diphosphate synthase (TcCDS), the enzyme catalyzing the first committed step in the biosynthesis of the acid moiety of pyrethrins, is trichome‐specific and developmentally regulated in flowers. In the present study we characterized the expression pattern of 25 lipoxygenase EST contigs, and subsequently carried out the molecular cloning of two pyrethrum lipoxygenases, TcLOX1 and TcLOX2, that have a similar pattern to TcCDS. Only recombinant TcLOX1 catalyzed the peroxidation of the linolenic acid substrate. Just as TcCDS, TcLOX1, are exclusively expressed in trichomes. Phylogenetic analysis showed that the enzyme shared the highest homology with chloroplast‐localized 13‐type‐lipoxygenases that are involved in maintaining basal levels of jasmonate.