bluuebunny/crossref_metadata_2025 huggingface dataset:
The association between sleep‐disordered breathing and enuresis in children
Authors: Jeyakumar Anita , Rahman Syed I. , Armbrecht Eric S. , Mitchell Ron
Published: April 2012

Objectives/Hypothesis:

To evaluate the prevalence of nocturnal enuresis in children diagnosed with sleep disordered breathing (SDB) and the effect of adenotonsillectomy (T&A) on nocturnal enuresis.

Study Design:

Systematic review of the literature.

Methods:

Systematic review of the literature was performed using PubMed and Ovid. A systematic analysis of the literature was performed from 1980 to 2010 to identify children who had SDB and enuresis. A subset of children with enuresis who underwent T&A for SDB were also studied.

Results:

A total of 14 studies were reviewed. A total of 3,550 children had SDB, of which one‐third (n = 1,113) had a diagnosis of enuresis. Age range was 18 months to 19 years.

Seven studies (n =1,360) had data on patients who underwent T&A for SDB with follow‐up data on enuresis. The mean sample size was 194, with a median follow‐up of 6 months and age range of 2 to 18 years. Preoperative prevalence of enuresis was 31% (426/1,360). A total of 587 children were followed after T&A. The postoperative prevalence of enuresis was 16% (95/587; P < .0002, two‐tailed). Most studies did not make a distinction between primary and secondary enuresis. The age range of the subjects (18 months to 19 years) likely included some patients with developmentally acceptable enuresis.

Conclusions:

SDB in children is associated with nocturnal enuresis. T&A is associated with a significant improvement in enuresis in children with SDB. There is a need for randomized controlled trials to look at the role of T&A in children with SDB and enuresis. Laryngoscope, 2012
Epidemiological aspects of recurrent respiratory papillomatosis: A population‐based study
Authors: Omland Turid , Akre Harriet , Vårdal Mari , Brøndbo Kjell
Published: April 2012

Objectives/Hypothesis:

The incidence of genital infections, cervical cancer, and oropharyngeal cancer induced by human papillomaviruses (HPV) is increasing in Western countries. Primarily, this study was conducted to estimate the incidence rate of recurrent respiratory papillomatosis (RRP) in juveniles and adults in two Norwegian subpopulations for each year between 1987 and 2009. The secondary objective of the study was to investigate whether there are trends in the incidence rates of RRP in the study period similar to what we have seen for HPV‐related cancer.

Study Design:

Population‐based study.

Methods:

Two Norwegian subpopulations with 2.6 million and 1.1 million inhabitants were investigated for the juvenile and adult forms of RRP, respectively, between the years of 1987 and 2009. Patients treated for RRP were identified in all ear/nose/throat departments located in the two areas.

Results:

The overall incidence rates of RRP in juveniles and adults were 0.17 (95% confidence interval [CI], 0.10–0.25) and 0.54 (95% CI, 0.44–0.65) per 100,000, respectively. We found a preponderance of males in both groups (P = .000 for adults and P = .038 for children). There was no significant change in the yearly incidence rate during the study period, for either adults or children, even when stratifying for gender in each group. The median age at onset was 4 years for children and 34 years for adults, with no significant difference between genders, nor significant changes during the study years.

Conclusions:

This study does not support our hypothesis of an increasing incidence of RRP, for either children or adults. The estimated incidence rates in the Norwegian subpopulations are consistent with former population‐based studies. Male preponderance in children was an unexpected finding. Further studies are warranted. Laryngoscope, 2012
Head and neck cancer in transplant recipients
Authors: Deeb Robert , Sharma Saurabh , Mahan Meredith , al‐Khudari Samer , Hall Francis , Yoshida Atsushi , Schweitzer Vanessa
Published: April 2012

Objectives/Hypothesis:

The development of malignancy in organ transplant patients is a well‐known complication of long‐term immunosuppressive therapy. We sought to characterize our institution's 20‐year experience with head and neck cancer after solid organ transplantation.

Study Design:

Retrospective review.

Methods:

Patients who underwent a solid organ transplant with subsequent development of a head and neck malignancy, including cutaneous and noncutaneous (upper aerodigestive tract and salivary gland) cancers, from January 1990 through December 2011 were identified. Patients were stratified according to cancer type, location, stage, and survival and compared to a nontransplant cohort in our institution's tumor registry.

Results:

Of 95 patients identified, 17 had noncutaneous and 78 had cutaneous head and neck malignancies post‐transplant. Among the noncutaneous group, no statistically significant differences occurred in age, gender, stage, or 5‐year survival status when compared to the nontransplant tumor registry cohort. However, significantly fewer transplant patients were alive at 1 year. Among the cutaneous group, >50% had multiple malignancies. The total incidence of head and neck cancer following organ transplantation was 2.6%.

Conclusions:

Although the development of head and neck cancer is a rare side effect of immunosuppression, it still warrants attention. These patients have been found to be less likely to survive >1 year when compared to their nontransplant counterparts. Patients who develop head and neck malignancies following organ transplantation require aggressive screening, treatment, and follow‐up, as this diagnosis may portend a poor prognosis.
Temporal integration of auditory and vestibular stimuli
Authors: Chang Nai‐Yuan N. , Uchanski Rosalie M. , Hullar Timothy E.
Published: April 2012

Objectives/Hypothesis:

Integration of balance‐related cues from the vestibular and other sensory systems requires that they be perceived simultaneously despite arriving asynchronously at the central nervous system. Failure to perform temporal integration of multiple sensory signals represents a novel mechanism to explain symptoms in patients with imbalance. This study tested the ability of normal observers to compensate for sensory asynchronies between vestibular and auditory inputs.

Study Design:

Double‐blinded experimental design.

Methods:

We performed whole‐body rotations about the earth‐vertical axis following a raised‐cosine trajectory at 0.5 and 1.0 Hz to several peak velocities up to a maximum of 180°/s in five normal subjects. Headphones were used to present a diotic auditory stimulus at various times relative to the onset of the rotation. Subjects were required to indicate which cue occurred first.

Results:

The vestibular stimulus needed to be presented 61 milliseconds (at a stimulus frequency of 0.5 Hz) and 19 milliseconds (at 1.0 Hz) before the auditory stimulus. Stimuli presented within a window of 300 milliseconds (at 0.5 Hz) to 200 milliseconds (at 1.0 Hz) were judged to be simultaneous.

Conclusions:

The central nervous system must accommodate for delays in perception of vestibular and other sensory cues. Inaccurate temporal integration of these inputs represents a novel explanation for symptoms of imbalance.
Synthesis and characterisation of antioxidant‐modified esters of dipentaerythritol as lubricating base oil
Authors: Zhang Letao , Cai Guoxing , Wang Yonglei , Eli Wumanjiang
Published: April 2012

In this paper, five antioxidant‐modified esters were synthesised through two steps of simple esterification. Antioxidant‐modified multi‐hydroxyl compound was synthesised at the first step, and antioxidant‐modified esters were synthesised at the second step. This kind of esters is useful in many fields, such as lubricating oil and cutting compound, because of two important functions (antioxidant and lubricant) in the same compound. The active antioxidant group attached to these esters was 3‐(3,5‐di‐tert‐butyl‐4‐hydroxy‐phenyl)‐propionic acid. The esters were characterised with Fourier transform infrared spectroscopy (FTIR) and thermogravimetric (TG) analysis. The analytical results of FTIR demonstrates the changes of alcoholic hydroxyl and carboxyl and suggests that this synthesis was feasible. The TG analysis and rotating pressure vessel method show that this kind of esters has excellent oxidative stability. The physical properties of lubricating base oil, such as viscosity, viscosity index, pour point and flash point, suggested that this kind of esters can be used as lubricating base oil. Copyright © 2012 John Wiley & Sons, Ltd.
The effect of permeability distribution on the numerical analysis of aerostatic ceramic porous bearings
Authors: Nicoletti Rodrigo , de Moraes Purquerio Benedito , de Castro Silveira Zilda
Published: April 2012

This work presents a numerical study on the effect of permeability on the static characteristics of aerostatic ceramic porous bearings. This study is important in bearing design because of the inherent permeability variation of the porous ceramic samples induced by manufacturing and sintering processes. The mathematical modelling of these bearings is based on the modified Reynolds equation, which depends on the pressure‐flow assumption (Darcy or Forchheimer) and on the static and dynamic permeability coefficients of the porous matrix. In this work, the modified Reynolds equation is numerically solved considering the variations of permeability values, whose distribution was obtained from experimental tests of the ceramic samples. Monte Carlo method is used to introduce variability in the solutions. One focuses on the effects of such variation on the results of predicted bearing loading capacity. Results show that optimum regions of the bearing load capacity do not vary significantly due to static and dynamic permeability variations. Copyright © 2012 John Wiley & Sons, Ltd.
Impact of the donor body mass index on the survival of pediatric liver transplant recipients and Post-transplant obesity
Authors: Perito Emily Rothbaum , Rhee Sue , Glidden Dave , Paul Roberts John , Rosenthal Philip
Published: April 2012

In adult liver transplant recipients, the donor body mass index (dBMI) is associated with posttransplant obesity but not with graft or patient survival. Because of the obesity epidemic in the United States and the already limited supply of liver donors, clarifying whether the dBMI affects pediatric outcomes is important. United Network for Organ Sharing data for pediatric liver transplants in the United States (1990-2010) were evaluated. Data on transplants performed between 2004 and 2010 (n = 3788) were used for survival analyses with Kaplan-Meier and Cox proportional hazards models and for posttransplant obesity analyses with generalized estimating equations. For children receiving adult donor livers, a dBMI of 25 to <35 kg/m2 was not associated with graft or patient survival in univariate or multivariate analyses. A dBMI ≥ 35 kg/m2 increased the risk of graft loss [hazard ratio (HR) = 2.54, 95% confidence interval (CI) = 1.29-5.01, P = 0.007] and death (HR = 3.56, 95% CI = 1.64-7.72, P = 0.001). For pediatric donors, the dBMI was not associated with graft loss or mortality in a univariate or multivariate analysis. An overweight or obese donor was not a risk factor for posttransplant obesity. Overweight and obesity are common among liver transplant donors. This analysis suggests that for adult donors, a body mass index (BMI) of 25 to <35 kg/m2 should not by itself be a contraindication to liver donation. Severe obesity (BMI ≥ 35 kg/m2) in adult donors increased the risk of graft loss and mortality, even after adjustments for recipient, donor, and transplant risk factors. Posttransplant obesity was not associated with the dBMI in this analysis. Further research is needed to clarify the impact of donor obesity on pediatric liver transplant recipients. Liver Transpl, 2012. © 2012 AASLD.
Long-term outcomes of stereotactic body radiation therapy in the treatment of hepatocellular cancer as a bridge to transplantation
Authors: O'Connor John K. , Trotter James , Davis Gary L. , Dempster Jane , Klintmalm Goran B. , Goldstein Robert M.
Published: April 2012

Hepatocellular carcinoma (HCC) is potentially curable with hepatic resection or transplantation. Few patients are eligible for resection, and many face a long wait for donor organ availability for liver transplantation. Here we report the safety and efficacy of stereotactic body radiation therapy (SBRT), the explant pathology findings and survival of patients treated with SBRT as a bridge to transplantation for HCC. From April 2005 to August 2010, 10 patients with 11 HCCs were treated with SBRT as a bridge to transplantation. All patients were evaluated by a liver transplant surgeon before radiosurgery. SBRT was delivered with the CyberKnife robotic radiosurgery system. After SBRT, all patients underwent orthotopic liver transplantation. The tumor response was determined by explant pathology. The median follow-up was 62 months from the time of SBRT. The mean time on the liver transplant wait list was 163 days. The median tumor size was 3.4 cm (range = 2.5-5.5 cm). The median SBRT dose was 51 Gy (range = 33-54 Gy) in 3 fractions. The median time from SBRT to liver transplantation was 113 days (range = 8-794 days). At 5 years, the overall survival rate and the disease-free survival rate were both 100%. Overall, 4 of the 10 patients (40%) experienced acute toxicity. Most toxicities were grade 1, and they included nausea, fatigue, and abdominal discomfort. One patient had grade 2 nausea/vomiting. Explant pathology revealed no viable tumor in 3 of the 11 tumors for a complete response rate of 27%. The remaining 8 tumors decreased or remained stable in size. In conclusion, with a median follow-up over 5 years, we have found that SBRT as a bridge to liver transplantation for HCC is feasible and well tolerated. SBRT for HCC may enable patients to remain on the list for frequently curative transplantation during the wait for organ availability. Liver Transpl, 2012. © 2012 AASLD.
Recipient survival and graft survival are not diminished by simultaneous liver-kidney transplantation: An analysis of the united network for organ sharing database
Authors: Martin Eric F. , Huang Jonathan , Xiang Qun , Klein John P. , Bajaj Jasmohan , Saeian Kia
Published: April 2012

Recipients of solitary liver and kidney transplants are living longer, and this increases their risk of long-term complications such as recurrent hepatitis C virus (HCV) and drug-induced nephrotoxicity. These complications may require retransplantation. Since the adoption of the Model for End-Stage Liver Disease, the number of simultaneous liver-kidney transplantation (SLK) procedures has increased. However, there are no standardized criteria for organ allocation to SLK candidates. The aims of this study were to retrospectively compare recipient and graft survival with liver transplantation alone (LTA), SLK, kidney after liver transplantation (KALT), and liver after kidney transplantation (LAKT) and to identify independent risk factors affecting recipient and graft survival. The United Network for Organ Sharing/Organ Procurement and Transplantation Network database (1988-2007) was queried for adult LTA (66,026), SLK (2327), KALT (1738), and LAKT procedures (242). After adjustments for potential confounding demographic and clinical variables, there was no difference in recipient mortality rates with LTA and SLK (P = 0.02). However, there was a 15% decreased risk of graft loss with SLK versus LTA (hazard ratio = 0.85, P < 0.001). The recipient and graft survival rates with SLK were higher than the rates with both KALT (P <0.001 and P <0.001) and LAKT (P = 0.003 and P < 0.001). The following were all identified as independent negative predictors of recipient mortality and graft loss: recipient age ≥ 65 years, male sex, black race, HCV/diabetes mellitus status, donor age ≥ 60 years, serum creatinine level ≥2.0 mg/dL, cold ischemia time > 12 hours, and warm ischemia time > 60 minutes. Although the recent increase in the number of SLK procedures performed each year has effectively decreased the number of potential donor kidneys available to patients with end-stage renal disease (ESRD) awaiting kidney transplantation, SLK in patients with end-stage liver disease and ESRD is justified because of the lower risk of graft loss with SLK versus LTA as well as the superior recipient and graft survival with SLK versus serial liver-kidney transplantation. Liver Transpl, 2012. © 2012 AASLD.
Donor information for living donor liver transplantation: Where can comprehensive information be found?
Authors: Melloul Emmanuel , Raptis Dimitri Aristotle , Oberkofler Christian Eugen , Dutkowski Philipp , Lesurtel Mickael , Clavien Pierre-Alain
Published: April 2012

Recently published data show that a large number of candidates for living donor liver transplantation (LDLT) actively look for additional information on the Internet because today it represents the main source of information for many of them. However, little is known about the quality of the information on LDLT available on the Internet. Our aim was, therefore, to comprehensively evaluate the online information available for LDLT candidates with the expanded Ensuring Quality Information for Patients (EQIP) tool (0-36 items). One hundred Web sites on LDLT were initially found with the Google, Bing, and Yahoo search engines, and we identified 32 Web sites that provided specific information for such candidates in English. Only 9 Web sites addressed >20 items and the scores tended to be higher for educational (P = 0.13) and scientific sites (P = 0.07) compared to hospital sites. The median number of items from the EQIP tool was only 16 (interquartile range = 13-20), and quantitative postoperative morbidity and mortality risk estimates were available on only 19% and 44% of the Web sites, respectively, despite the idea of major complications being mentioned on most Web sites. This analysis demonstrated several significant shortcomings in the quality of the information provided to potential donors for LDLT according to the EQIP instrument. We conclude that there is an urgent need to produce a Web site compliant with international standards for the quality of donor information. Liver Transpl, 2012. © 2012 AASLD.
Improvement in the bonding strength of laminated composites by using air‐textured core‐and‐effect glass yarns
Authors: Mahmood Ali Hasan , Gong Rong Hugh , Porat Isaac
Published: April 2012

Delamination is the most common failure mode in laminated composites due to the reduced strength in the through‐the‐thickness direction. Air‐jet texturing was used to produce bulk and loops in the yarn, which provides more surface contact between the fibers and the resin. The development of core‐and‐effect textured glass yarns and the effect of texturing parameters were presented in the previous article. This article describes the effect of texturing on the mechanical properties including tensile properties, flexure properties, interlaminar shear strength (ILSS) and fracture toughness (Mode I) of glass laminated composites. The composites of plain and twill weave fabrics were developed from both the textured and nontextured yarns. It was observed that the tensile properties decreased and the flexure properties remained unchanged after texturing. However, significant improvement was observed in ILSS and the Mode I fracture toughness of the composites after texturing. The bulkier, loopy structure of the textured yarn provided more surface contact between the fiber and the resin and significantly improved the bonding strength. POLYM. COMPOS., 2012. © 2012 Society of Plastics Engineers
Conductive, mechanical, and chemical resistance properties of polyurushiol/multiwalled carbon nanotube composite coatings
Authors: Bai Weibin , Zhuo Dongxian , Xiao Xueqing , Xie Junna , Lin Jinhuo
Published: April 2012

The polyurushiol (PUS)/multiwalled carbon nanotube (MWCNT) composite coatings were prepared by in situ composite method. The fracture morphology of the composite films showed that MWCNTs had been well dispersed in PUS matrix, which significantly decreased the electrical resistivity and the gloss of the composite films. The nonconducting/conducting state transition took place at approximately 3.0 wt% of MWCNTs with the volume electrical resistivity of 104 Ω cm. The results of the mechanical tests revealed that the impact of strength and the storage modulus of the coatings increased with the addition of MWCNTs. Furthermore, the PUS/MWCNTs composite films had good chemical resistance. POLYM. COMPOS., 2012. © 2012 Society of Plastics Engineers
Effect of nanoclay particles on mold‐filling performance in composites made via resin infusion process
Authors: Karimzadeh M. , Sabet A.R. , Beheshty M.H.
Published: April 2012

This study investigates the effect of 3 and 5 wt% nanoclay (Cloisite 30B) addition on mold filling time and performance of continuous glass filament mat reinforced unsaturated polyester (UP) resin composites made by vacuum infusion process. X‐ray diffraction and transmission electron microscopy analysis as well as viscosity change in liquid state resin confirmed intercalation and exfoliation of the nanoclay in the resin system. The result shows mold filling time increase of 3 and 2.4 times for the samples containing 3 and 5 wt% nanoclay, respectively, compared with nanoclay‐free sample. This increase in mold filling time is directly attributed to the increase in resin viscosity. Filtration of nanoclay particles were observed in the resin flow direction. Result showed 8 and 14% filtration of nanoclay in flow direction for the samples with 3 and 5 wt% nanoclay content, respectively. Nanoclay containing specimens prepared from near resin entry port area showed relatively higher flexural and tensile modulus and as well as strength compared to specimens prepared from area close to vacuum port area. The result showed best performance for 3 wt% nanoclay containing specimen. However, impact strength decreased about 6.1 and 10.8% for 3 and 5% nanoclay, respectively. POLYM. COMPOS., 2012. © 2012 Society of Plastics Engineers
Experimental investigation on reprocessing of extruded wood flour/HDPE composites
Authors: Shahi Peyman , Behravesh Amir Hossein , Daryabari Seyyed Yaser , Lotfi Maziar
Published: April 2012

This article presents an experimental study on the change in the properties of wood–plastic composites (WPCs) when reprocessed. The degree of properties degradation upon reprocessing, for recycling purpose, can be considered as a key factor to choose an alternative against discarding into the environment. A material which retains its properties when recycled, or at least exhibits insignificant reduction in its properties, is favorable in environmental point of view. To investigate the reprocessing effect on the WPC properties, in this study, cylindrical profiles of WPC, with 60 wt% of wood content, were produced using a twin screw extruder, at first stage (virgin WPC). These profiles were then chopped into granules and used in the reproduction of the same shaped product (recycled WPC). For the measurement of mechanical properties, tensile and three‐point bending tests were conducted. Differential scanning calorimetry (DSC) test was performed to compare thermal behavior of the neat HDPE, virgin and recycled composites. Scanning electron microscopy (SEM) images were also produced to observe the adhesion quality of the components and changes in wood particles size. Physical properties such as density and water uptake were also measured. A reduction in strength was observed upon recycling which was accompanied with the decrease in density, while an increase in the flexural modulus was noticed. The results also indicate that the recycled samples exhibit a higher water uptake. Analysis of thermal behavior showed a slight increase in the melting temperature of the reprocessed composite and decrease in the degree of crystallinity especially at the first stage of the HDPE process. POLYM. COMPOS., 2012. © 2012 Society of Plastics Engineers
Isolation and characterization of betel nut leaf fiber: Its potential application in making composites
Authors: Arifuzzaman Khan G.M. , Shahrear Palash S.R. , Shamsul Alam M. , Chakraborty A.K. , Gafur M.A. , Terano M.
Published: April 2012

Betel nut leaf fiber (BNLF) is a new finding as cellulosic filler for polymer composites. Its main constituents are 75% α‐cellulose, 12% hemicelluloses, 10% lignin, and 3% others matter, viscosity average molecular weight 132,000 and degree of crystallinity 70%. In the present work, BNLF reinforced polypropylene (PP) composites were prepared using heat press molding method. 5–20 wt% short length fiber is taken for getting benefits of easy manufacturing and the fiber was chemically treated with NaOH, dicumyl peroxide (DCP), and maleic anhydride‐modified PP (MAPP) to promote the interfacial bond with PP. The extent of modification of fiber was assessed on the basis of morphology, bulk density, moisture absorption, thermal, and mechanical properties of untreated fiber, treated fiber, and their reinforcing PP composites. The tensile and flexural strength of composites increase with the increase of fiber loading up to 10 and 20 wt%, respectively. It was also observed that Young's modulus and flexural modulus increase with fiber loading. The thermal degradation behavior of resulting composites was investigated. Among the various treated fibers, MAPP‐treated fiber composite showed best interfacial interactions as well as mechanical and thermal properties. POLYM. COMPOS., 2012. © 2012 Society of Plastics Engineers
Novel trifluoromethylated epoxy based thermosets: synthesis and characterization
Authors: Penoff Marcela E , Montemartini Pablo E , Oyanguren Patricia A
Published: April 2012

Two series of trifluoromethylated crosslinked epoxy‐based polymers with different molecular architectures and fluorine contents (from 1 to 5 wt%) have been investigated. The epoxy monomer was a diglycidyl ether of bisphenol A, and the curing agents were 3‐(trifluoromethyl)aniline and 4,4′‐methylenebis(3‐chloro‐2,6‐diethylaniline). The structural parameters of networks such as gelation and vitrification and the properties of the resulting fluorinated materials were investigated and compared. Final materials showed high transparency with an ultraviolet‐visible absorption cut‐off between 350 and 380 nm, low moisture (0.60 wt%) and a decrease in dielectric constant from 6.3 to 5.2 with increasing fluorine content. Copyright © 2012 Society of Chemical Industry
Synthesis and conformation effects of poly(phenylacetylene)s having chiral and racemic polylactide pendants
Authors: Zhang Chunhong , Wang Hailun , Su Guangdong , Li Ruiqi , Shen Xiande , Zhang Shuang , Geng Qianqian , Liu Fangbin , Otsuka Issei , Satoh Toshifumi , Kakuchi Toyoji
Published: April 2012

Chiral and racemic macromonomers with a polymerizable phenylacetylenyl end group (PA‐PLLA and PA‐PDLLA) were successfully synthesized through living ring‐opening polymerization of chiral and racemic monomers (L‐lactide and DL‐lactide), respectively. Then the homopolymerization of PA‐PLLA and PA‐PDLLA was successfully carried out to give poly(PA‐PLLA) and poly(PA‐PDLLA), respectively. Chiroptical properties, hydrodynamic radii and micromorphologies of poly(PA‐PLLA) and poly(PA‐PDLLA) were analyzed via circular dichroism, dynamic light scattering and atomic force microscopy (AFM), and the conformation of the polymers is discussed. The results indicate that poly(PA‐PLLA) induced Cotton effects with different intensities in various solvents, and its hydrodynamic radii and dispersity were also different in various solvents, while poly(PA‐PDLLA) induced no Cotton effects and its hydrodynamic radii and dispersity were approximately the same in various solvents. Furthermore, a helical conformation of poly(PA‐PLLA) and the random main chains of poly(PA‐PDLLA) were observed by AFM. Therefore, it is concluded that poly(PA‐PLLA) possesses a dynamic one‐handed helical conformation in various solvents due to chiral poly(L‐lactide) pendants, while poly(PA‐PDLLA) possesses racemic main chains because of the racemic poly(DL‐lactide) pendants. Copyright © 2012 Society of Chemical Industry
Estimation of Agglomeration Degree and Nanoparticles Shape of Zirconia Nanopowders
Authors: Danilenko Igor , Konstantinova Tetyana , Pilipenko Nikolay , Volkova Galina , Glasunova Valentina
Published: April 2012

The influence of different surfactants (Trilon B, Polyammoniumacrylate and Neonol) and mineralizers (HCl, KOH, CH3COOH, etc.) on agglomeration degree of zirconia nanopowders obtained by precipitation technique was investigated. By adding of surfactants and mineralizers the different phase composition, particle size and agglomeration degree of zirconia nanopowders were obtained. The comparison between experimental specific surface area (SSA) value and calculated surface area for nonagglomerated spherical particle model show that experimental value of SSA bigger than calculated value. We proposed that low calcining temperatures (less than 700 °C) lead to formation the zirconia particles with cylindrical form. When taking into account the contact area between the particles in this model, we recalculate the surface area of powders and get better fit to experimental value.
Characterization of Different Shaped Nanocrystallites using X‐ray Diffraction Line Profiles
Authors: Li Zongquan
Published: April 2012

Quantitative information on the X‐ray diffraction line profiles for different shaped nanocrystallites, using nanocrystalline Cu as an example, are obtained by using the Debye scattering equation, which is useful for characterizing nanocrystallite. The apparent lattice parameter obtained from line positions by using the Bragg's law has a larger deviation from the actual value when the crystallite sizes are smaller than about 10nm. When the crystallites are larger than about 6nm, the full width at half maximum (FWHM) ratios of FWHMhkl to FWHM002 are nearly constants which can be used to identify the shape of the crystallites. The Scherrer constant depends not only on the shape of the crystallite but also on the Miller index of the line, the values of the Scherrer constant for different shaped nanocrystallites are given in the present paper.
Characterization of Powders using Micro Computed Tomography
Authors: Redenbach Claudia , Ohser‐Wiedemann Renate , Löffler Ralf , Bernthaler Timo , Nagel Alwin
Published: April 2012

Micro computed tomography (μCT) is proposed as a tool for the characterization of powders. Using this technique three dimensional images carrying the whole spatial information on a particular powder can be obtained. After an image analytic separation of the single particles, distributions of geometric characteristics describing size, shape, and spatial arrangement of the particles can be estimated. The method is applied to four samples of powders with different particle structure. The results are compared with particle size characteristics measured by laser diffraction, sieve analysis, and the analysis of microscopic 2D images.
Analysis of Confidence Lower Limits of Reliability and Hazard Rate for Electronic Stability Control Systems
Authors: Niu Shiwen , Zhan Wei
Published: April 2012

This article describes an evaluation method for reliability and hazard rate of lifetime distribution confidence lower limits for electronic stability control (ESC) system using test data from multistage and subsystems. This method provides estimation that can potentially and significantly reduce the amount of testing, without sacrificing the one‐sided confidence level of reliability. This also allows quicker design verification and validation for ESC systems. The method is derived under the assumption that the reliability parameter is a random variable with a given distribution function, and the product's reliability increases monotonously during the development process. This new method is applied to the analysis of reliability of an ESC system. Copyright © 2012 John Wiley & Sons, Ltd.
Understanding the inactivation process of organophosphorus herbicides: A DFT study of glyphosate metallic complexes with Zn2+, Ca2+, Mg2+, Cu2+, Co3+, Fe3+, Cr3+, and Al3+
Authors: Caetano Melissa S. , Ramalho Teodorico C. , Botrel Douglas F. , da Cunha Elaine F. F. , de Mello Walclee Carvalho
Published: April 2012

Glyphosate is the active component of one of the top‐selling herbicides, which is also a potent EPSP synthase inhibitor. The herbicide is absorbed by living tissue and translocated via the phloem, to plant roots and rhizomes. When applied directly into the soil it has low activity, due to the high adsorption by soil constituents. Understanding the specific interactions between metals in the soil and glyphosate is the main step in understanding the low activity of the herbicide when applied directly into the ground and not pulverized. We can observe there is a stability order for both tetrahedral and octahedral complexes between glyphosate and metals: Zn>Cu>Co>Fe>Cr>Al>Ca>Mg. © 2012 Wiley Periodicals, Inc.
Theoretical study of free and encapsulated carboxylic acid and amide dimers
Authors: Tzeli Demeter , Petsalakis Ioannis D. , Theodorakopoulos Giannoula , Ajami Dariush , Rebek Julius
Published: April 2012

The homodimers and heterodimers of four carboxylic acids RCOOH and four amides RCONH2, where R = H, methyl, phenyl, p‐ethylphenylene have been calculated via DFT(M06‐2X), MP2, and CCSD(T) methods in conjunction with the 6‐31G(d,p), 6‐311+G(d,p), aug‐cc‐pVTZ, and aug‐cc‐pVQZ basis sets to find out how the substituent R influences their dimerization energy (ΔE) and their hydrogen bond length. The calculated ΔE values range from 14 to 17 kcal/mol for the different dimers in the gas phase, with the ordering carboxylic homodimers ≥ amide‐carboxylic dimers > amide homodimers. The M06‐2X/6‐311+G(d,p) geometries and ΔE values are in very good agreement with the corresponding MP2/aug‐cc‐pVQZ and CCSD(T)/aug‐cc‐pVTZ values. Coencapsulation of the dimers was studied to examine its effect on the calculated bond lengths and strength of the hydrogen bonds at the M06‐2X/6‐31G(d,p) level of theory. The experimental and calculated % distributions of the encapsulated dimers, taking into account statistical factors are in good agreement. © 2012 Wiley Periodicals, Inc.
Why sp2‐like nanosilicons should not form: Insight from quantum chemistry
Authors: Sheka E. F.
Published: April 2012

The odd‐electron molecular theory, which takes into account the electron correlation, has been applied for a comparative consideration of sp2 nanocarbons and their siliceous analogues. Four characteristic quantities that involve the energy misalignment, the number of effectively unpaired electrons, the squared spin value, and CC and SiSi chemical bond lengths have been suggested to classify the extent of the odd electron correlation in both families. Providing a considerable enlargement of the internuclear distances, the electron correlation in siliceous species is extremely strong thus resulting in complete radicalization of the species and proving the impossibility of their existence at ambient conditions in contrast to carboneous ones that are not so strong correlated. © 2012 Wiley Periodicals, Inc.
One‐electron pseudopotential study of the alkali hydride cation NaH+: Structure, spectroscopy, transition dipole moments, and radiative lifetimes
Authors: Berriche H.
Published: April 2012

The structure and spectroscopic properties of the ground and the lowest excited electronic states of the alkali hydride cation NaH+ have been investigated using an ab initio approach. In this approach, a nonempirical pseudopotential for the Na+ core has been used and a core–core and a core‐valence correlation corrections have been added. The adiabatic potential energy curves and the molecular spectroscopic constants for numerous electronic states of 2Σ+, 2Π, and 2Δ symmetries, dissociating up to Na (4d) + H+ and Na+ + H (3d), have been calculated. As no experimental data are available, we discuss our results by comparing with the available theoretical calculations. A satisfying agreement has been found for the ground state with previous works. However, a clear disagreement between this study and the model potential work of Magnier (Magnier, J. Phys. Chem. A 2005, 109, 5411) has been observed for several excited states. Numerous avoided crossings between electronic states of 2Σ+ and 2Π symmetries have been found and analysed. They are related to the interaction between the potential energy curves and to the charge transfer process between the two ionic systems Na+H and NaH+. Furthermore, we provide an extensive set of data concerning the transition dipole moments from X2Σ+ and the 22Σ+ states to higher excited states of 2Σ+ and 2Π symmetries. Finally, the adiabatic potential energy curves of the ground (X2Σ+) and the first (22Σ+) excited states and the transition dipole moments between these states are used to evaluate the radiative lifetimes for the vibrational levels of the 22∑+ state for the first time. In addition to the bound–bound contribution, the bound‐free term has been evaluated and added to the total radiative lifetime. © 2012 Wiley Periodicals, Inc.
A theoretical study on the hydrogen transport mechanism in SrTiO3 perovskite. II. Scandium doping at titanium site
Authors: Onishi Taku , Helgaker Trygve
Published: April 2012

Hybrid Kohn–Sham calculations are performed to clarify the proton‐conduction mechanism in Sc‐doped SrTiO3 perovskite, from the viewpoint of energetics and bonding. The calculated potential energy curves are discussed and a molecular‐orbital analysis performed. Much hydrogen can exist around doped scandium, where it is energetically stabilized. However, scandium‐doping has no energetic advantage in the activation energy for proton‐conduction. © 2012 Wiley Periodicals, Inc.
Study of the mass spectrometric behaviors of anthocyanins in negative ionization mode and its applications for characterization of anthocyanins and non‐anthocyanin polyphenols
Authors: Sun Jianghao , Lin Long‐ze , Chen Pei
Published: April 2012

RATIONALE

Traditionally, anthocyanin analysis in mass spectrometry is carried out in the positive ionization mode only. A study of the mass spectrometric behaviors of anthocyanins in the negative ionization mode revealed interesting characteristics that was not previously reported. It can be used to differentiate anthocyanins from other non‐anthocyanin polyphenols.

METHODS

An ultra‐high‐performance liquid chromatography with high‐resolution mass spectrometry (U‐HPLC/HRMS) method was developed. The method used multiple‐stage mass fragmentation in both the negative and positive ion modes. The whole cycle time of the new method is 1.8 s for two full scans and six data‐dependent scans.

RESULTS

The new strategy found, in the negative ionization mode, a series of characteristic ions, e.g. [M–2H]–, [M–2H + H2O]– , formic acid adducts, and doubly charged ions were observed for the MS analysis of anthocyanins. The characteristic ions can be used for identification and differentiation of anthocyanins and non‐anthocyanin phenolic compounds. Comprehensive studies were performed on the differentiation of anthocyanins and non‐anthocyanin polyphenols in blueberry (Vaccinium cyanococcus), Hongcaitai (Brassica compestris L. var. purpurea Bailey), and red radish (Raphanus sativus var. longipinnatus 'Shinrimei').

CONCLUSIONS

The data generated from a single LC run enables rapid and reliable differentiation and identification of anthocyanins and non‐anthocyanins in botanicals and foods. Published 2012. This article is a US Government work and is in the public domain in the USA.
Proactive recovery approach for intrusion tolerance with dynamic configuration of physical and virtual replicas
Authors: Zhao Feng , Li Min , Qiang Weizhong , Jin Hai , Zou Deqing , Zhang Qin
Published: April 2012

Proactive recovery mechanism has been widely used in building intrusion‐tolerant systems that are able to tolerate an arbitrary number of faults. However, previous proactive recovery methods seldom consider the dynamic in attacking power that may cause the increase in fault rate, resulting unguaranteed service availability. This paper describes an approach for tolerating intrusions, or more precisely, damages to replicated data, through dynamic configuration of physical and virtual replicas, which follows a general approach called proactive recovery, and proposes to dynamically adjust recovery frequency to handle potentially changing fault rate. This dynamic proactive recovery method takes the dynamic changes of attaching power into consideration to avoid/minimize the effect of intrusions. Our method is especially effective and useful in intrusion tolerance with physical replicas: it dynamically provides virtual replicas during rejuvenation phase. Copyright © 2012 John Wiley & Sons, Ltd.
Network specific vulnerability based alert reduction approach
Authors: Njogu Humphrey Waita , Jiawei Luo , Kiere Jane Nduta
Published: April 2012

Traditional intrusion detection systems are known for triggering large volumes of alerts. An average commercial intrusion detection system reports thousands of alerts on daily basis. A large proportion of these alerts are false alerts. In the field of alert management, alert verification is cited as critical component in determining the success of intrusions. It helps to eliminate any alert that does not have a corresponding vulnerability in a network, hence improving the effectiveness of alert management approaches. Alert verification alone cannot guarantee alerts of high quality because the validated alerts may contain massive number of redundant alerts. The analysts who review alerts are likely to take longer time to understand the complete security incident because it would involve evaluating each single redundant alert. Consequently, the analysts would not only encounter difficulties when taking the correct decision but would also take longer time to respond against the intrusions. Therefore, the unnecessary alerts diminish the value and urgency of the relevant alerts.

This paper seeks to address the aforementioned issue to strengthen the vulnerability‐based alert management approaches. Our approach verifies alerts prior to merging them. Central to this approach is the use of two components: verifier and alert merger. The verifier component improves the quality of alerts by validating them with enhanced vulnerability assessment data. The alert merger component reduces huge number of redundant alerts. Experiments conducted in our test bed have demonstrated the success of our approach in reducing most of the unnecessary alerts for a range of attacks with high accuracy yet closely maintaining the detection rate. Copyright © 2012 John Wiley & Sons, Ltd.
STaR: design and quantitative measurement of source‐location privacy for wireless sensor networks
Authors: Lightfoot Leron , Li Yun , Ren Jian
Published: April 2012

Wireless sensor networks (WSNs) can provide the world with a technology for real‐time event monitoring. One of the primary concerns that hinder the successful deployment of WSNs is source‐location privacy (SLP). The privacy of the source location is vital and highly jeopardized by the usage of wireless communications. Although message content privacy can be ensured through message encryption, it is much more difficult to adequately address the SLP. For WSNs, SLP service is further complex by the fact that sensors consist of low‐cost and energy‐efficient radio devices. Therefore, using computationally intensive cryptographic algorithms (such as public‐key cryptosystems) and large‐scale broadcasting‐based protocols are not suitable for WSNs. In this paper, we analyze the quantitatively measure source‐location information leakage in routing‐based SLP protection schemes for WSNs. Through this model, we identify vulnerabilities of some well‐known SLP protection schemes. We also propose a routing technique, called the Sink Toroidal Region (STaR), to provide adequate SLP with low energy consumption. With this routing technique, the source node randomly selects an intermediate node within a designed STaR area located around the sink node. Furthermore, this routing protocol ensures that the intermediate node is neither too close, nor too far from the sink node in relations to the entire network. While ensuring SLP, our simulation results show that the proposed scheme is very efficient and can be used for practical applications. Copyright © 2012 John Wiley & Sons, Ltd.
Anonymous communication in overlay networks
Authors: Ren Jian , Li Yun , Jiang Tingting , Li Tongtong
Published: April 2012

Communication anonymity is becoming an increasingly important, or even indispensable, security requirement for many applications. The existing research in anonymous communications can largely be divided into two categories: mix‐based systems and secure multiparty computation‐based systems, originating from mixnet and DC‐net, respectively. However, they either cannot provide provable anonymity or suffer from transmission collision problem. In this paper, we first propose a novel unconditionally secure source anonymous message authentication code that can be applied to any messages without relying on any trusted third parties. While ensuring message sender anonymity, secure source anonymous message authentication code can also provide message content authenticity. We then propose a novel communication protocol that can hide the senders and the recipients from each other and thus can be used for secure file sharing. The security analysis demonstrates that the proposed protocol is secure against various attacks. Our analysis also shows that it is efficient and practical. Copyright © 2012 John Wiley & Sons, Ltd.
Microfluidic Encapsulation of Cells in Polymer Microgels
Authors: Velasco Diego , Tumarkin Ethan , Kumacheva Eugenia
Published: April 2012

In this Concept article, recent advances in microfluidic platforms for the generation of cell‐laden hydrogel particles (microgels) are reported. Advances in the continuous microfluidic encapsulation of cells in droplets and microgels are critically reviewed, and currently used methods for the encapsulation of cells in polymer microgels are discussed. An outlook on current applications and future directions in this field of research are also presented. This article will be of interest to chemists, materials scientists, cell biologists, bioengineers, and pharmacologists.
Developmental pathways linking externalizing symptoms, internalizing symptoms, and academic competence to adolescent substance use
Authors: Englund Michelle M. , Siebenbruner Jessica
Published: April 2012

This study extends previous research investigating the developmental pathways predicting adolescent alcohol and marijuana use by examining the cascading effects of externalizing and internalizing symptoms and academic competence in the prediction of use and level of use of these substances in adolescence. Participants (N = 191) were drawn from a longitudinal study of first‐born children of low‐income mothers. Using data from ages 7, 9, 12, and 16 years, a series of nested two‐part (semi‐continuous) path models from a developmental cascade modeling framework were compared. Controlling for gender, SES, mother’s age at child’s birth, and minority status, we found (a) within‐domain rank‐order stability across time, (b) significant cross‐domain effects over time, (c) higher externalizing symptoms significantly predicted use of alcohol and marijuana as well as higher levels of use in adolescence, and (d) higher levels of academic competence significantly added to the prediction of use of alcohol.