bluuebunny/crossref_metadata_2025_split huggingface dataset:
Kinetics and Equilibrium Swelling Properties of Hydrophilic Polymethacrylate Networks
Authors: Elouali Fatima Zohra , Maschke Ulrich 
Published: June 2011

AbstractSummary: Hydrogels were synthesized by polymerization of 2‐Hydroxy ethylmethacrylate (HEMA) in the presence of ethyleneglycoldimethacrylate (EGDMA) as a crosslinking agent. Structural information and thermophysical properties of the hydrogels were analyzed using Fourier‐Transform Infrared spectroscopy, thermogravimetrical analysis, and differential scanning calorimetry. The swelling behaviour of the obtained chemically crosslinked P(HEMA‐EGDMA) networks in aqueous solution was investigated as a function of the pH value and concentration of crosslinking agent. Plateau values were found at equilibrium swelling for a low pH value after one day swelling, whereas increasing water uptake was obtained for pH = 6.32 even at swelling times of more than five days. For short swelling times, a linear relationship between swelling ratio and time was found. Experimental data were rationalized using Fick's second law of diffusion. For early and moderate times of diffusion, threshold values were found in all cases considered here, indicating a Fickian behaviour below and a non‐Fickian diffusion mechanism above the threshold.
Use of Biopolymers for the Removal of Metal Ion Contaminants from Water
Authors: Bondarev A. , Mihai S. , Pântea O. , Neagoe S. 
Published: June 2011

AbstractSummary: Naturally abundant biosorbants such as chitin and chitosan are recognized as excellent metal ligands, forming stable complexes with many metal ions, and serving as effective protein coagulating agents. Chitosan is a heteropolymer made of D‐glucosamine and a small fraction of N‐acetyl‐D‐glucosamine residues. Therefore, the adsorption ability of chitosan is found to be much higher than that of chitin, which has relatively fewer amino groups. Zeolites are crystalline microporous aluminosilicates with ion exchange properties suitable for a wide range of applications in catalysis and separation of liquid and gaseous mixtures. Incorporation in chitosan membranes is an effective method to control the diffusion outside the zeolite crystals and appropriately designed composite systems can find numerous opportunities for applications in wastewater treatment. In this paper we present the synthesis of zeolite‐chitosan and zeolite‐ethyl cellulose composites by encapsulation of clinoptilolite using a gelling solution of chitosan or an ethyl cellulose solution in ethyl acetate. The adsorption process of Cu2+ and Cd2+ on some adsorbents was investigated: clinoptillolite tuff (0.05 mm), chitosan flakes, ethyl cellulose, zeolite‐chitosan and zeolite‐ ethyl cellulose composites. Zeolite‐chitosan composites have been prepared by encapsulation of zeolites by a gelling solution of chitosan. Micrometric crystals of clinoptillolite were dispersed in a 3% chitosan solution in 1% aqueous acetic acid. The chitosan gel was formed and the zeolite crystals were encapsulated during the gelling process. The same procedure was used to obtain zeolite – ethyl cellulose composites. Study of the metal ion retention properties of different adsorbent materials was carried out using a steady state regime. The concentration of heavy metal ions in supernatant was determined by the atomic absorption spectrophotometric method. Adsorption isotherms of metal ions on adsorbents were determined and correlated with common isotherm equations such as Langmuir and Freundlich models.
Effect of Curing Process on the Dynamic Response of Polymer Dispersed Liquid Crystal Films
Authors: Abdoune Fatima Zohra , Benkhaled Leila , Méchernène Lahcène , Maschke Ulrich 
Published: June 2011

AbstractSummary: The time relaxation of the optical transmission of polymer‐dispersed liquid crystal films was investigated after application of an electric rectangular pulse. These films, consisting of liquid crystalline microdomains dispersed in a polymer matrix, were obtained by polymerization induced phase separation using ultraviolet and electron beam curing techniques. The effects of the curing procedure and film thickness on the transmission properties were investigated. The electro‐optical response was expressed via a hierarchy of order parameters. A good agreement between the experimental data and calculated transmission values was found.
Fast radiofrequency flip angle calibration by Bloch–Siegert shift
Authors: Sacolick Laura I. , Sun Ling , Vogel Mika W. , Dixon W. Thomas , Hancu Ileana 
Published: June 2011

AbstractIn a recent work, we presented a novel method for B field mapping based on the Bloch–Siegert shift. Here, we apply this method to automated fast radiofrequency transmit gain calibration. Two off‐resonance radiofrequency pulses were added to a slice‐selective spin echo sequence. The off‐resonance pulses induce a Bloch–Siegert phase shift in the acquired signal that is proportional to the square of the radiofrequency field magnitude B12. The signal is further spatially localized by a readout gradient, and the signal‐weighted average B1 field is calculated. This calibration from starting system transmit gain to average flip angle is used to calculate the transmit gain setting needed to produce a desired imaging sequence flip angle. A robust implementation is demonstrated with a scan time of 3 s. The Bloch–Siegert‐based calibration was used to predict the transmit gain for a 90° radiofrequency pulse and gave a flip angle of 88.6 ± 3.42° when tested in vivo in 32 volunteers. Magn Reson Med, 2011. © 2011 Wiley Periodicals, Inc.
A quantitative comparison of the influence of individual versus population‐derived vascular input functions on dynamic contrast enhanced‐MRI in small animals
Authors: Loveless Mary E. , Halliday Jane , Liess Carsten , Xu Lei , Dortch Richard D. , Whisenant Jennifer , Waterton John C. , Gore John C. , Yankeelov Thomas E. 
Published: June 2011

AbstractFor quantitative analysis of dynamic contrast enhanced magnetic resonance imaging data, the time course of the concentration of the contrast agent in the blood plasma, or vascular input function (VIF), is required. We compared pharmacokinetic parameters derived using individual and population‐based VIFs in mice for two different contrast agents, gadopentetate dimeglumine and P846. Eleven mice with subcutaneous 4T1 breast cancer xenografts were imaged at 7 T. A precontrast T1 map was acquired along with dynamic T1‐weighted gradient echo images before, during, and after a bolus injection of contrast agent delivered via a syringe pump. Each animal's individual VIF and derived population‐averaged VIF were used to extract parameters from the signal‐time curves of tumor tissue at both the region of interest and voxel level. The results indicate that for both contrast agents, Ktrans values estimated using population‐averaged VIF have a high correlation (concordance correlation coefficient > 0.85) with Ktrans values estimated using individual VIF on both a region of interest and voxel level. This work supports the validity of using of a population‐based VIF with a stringent injection protocol in preclinical dynamic contrast enhanced magnetic resonance imaging studies. Magn Reson Med, 2011. © 2011 Wiley‐Liss, Inc.
Volume measurement of bone erosions in magnetic resonance images of patients with rheumatoid arthritis
Authors: Emond P. D. , Inglis D. , Choi A. , Tricta J. , Adachi J. D. , Gordon C. L. 
Published: June 2011

AbstractThe volume of bone erosions in the metacarpophalangeal joints is a radiological feature that can be used to track the progression of rheumatoid arthritis. We introduce a hybrid segmentation algorithm that combines region growing and level‐set segmentation algorithms to semiautomatically measure the volume of bone erosions in magnetic resonance images. A total of 40 rheumatoid arthritis patients were included in the study. The scans of eight patients were used for training, whereas the remaining 32 scans were used to determine the accuracy, precision, and speed of the technique. The reproducibility of the semiautomated technique and that of manual segmentation was defined in terms of intraclass correlation coefficients. Both techniques were equally precise with intraclass correlation coefficient values greater than 0.9. The hybrid algorithm was highly accurate: the least squares fit between the semiautomated segmentations to those manually traced by a musculoskeletal radiologist resulted in a slope of 1.030 with an x‐intercept of 1.385 mm3 and an R2 value of 0.923. The semiautomated technique was significantly faster than manual segmentation, which took two to four times longer to complete. Our hybrid algorithm shows promise in the quantitative assessment of radiological features of rheumatoid arthritis in a clinical setting. Magn Reson Med, 2012. © 2011 Wiley Periodicals, Inc.
Hospitalization and surgical rates in patients with Crohn's disease treated with infliximab: a matched analysis
Authors: Leombruno John Paul , Nguyen Geoffrey C. , Grootendorst Paul , Juurlink David , Einarson Tom 
Published: June 2011

ABSTRACTPurposeThe majority of subjects with Crohn's Disease (CD) will be hospitalized and will receive surgery for their disease. These interventions account for most of the direct costs of the disease. We sought to explore the association between infliximab use and CD‐related surgery and hospitalizations.MethodsWe obtained patient‐level health claims between 1996 and 2007 from the Régie de l'Assurance Maladie du Québec (RAMQ), a Canadian provincial health care insurer. Subjects who were i) enrolled in the RAMQ for at least 2 years, ii) received prescription drug benefits for each year of enrolment and iii) were identified as having CD using a validated algorithm were eligible for the study. For each subject treated with infliximab, up to two closely matched comparison subjects were selected using propensity score methods. We compared time to first CD‐related intra‐abdominal surgery or hospitalization in infliximab users and non‐users.ResultsWe matched 338 infliximab users (mean age 34, 45% male) to at least one comparison subject using propensity score matching. Subjects who received infliximab had a significantly lower risk of experiencing a CD‐related intra‐abdominal surgery (hazard ratio [HR] = 0.64; 95% confidence interval [CI] 0.51–0.81) or hospitalization (HR = 0.73; 95% CI 0.63–0.85). Infliximab users also experienced lower rates of hospitalized days (Rate Ratio = 0.69; 95% CI 0.49–0.97).ConclusionsOur results support the real world effectiveness of infliximab therapy in reducing CD‐related surgeries and hospitalizations. Copyright © 2011 John Wiley & Sons, Ltd.
Association between non‐steroidal anti‐inflammatory drugs and keratinocyte carcinomas of the skin among participants in the Veterans Affairs Topical Tretinoin Chemoprevention Trial
Authors: Nunes Anthony P. , Lapane Kate L. , Weinstock Martin A. ,   VATTC Trial Group
Published: June 2011

ABSTRACTPurposeObservational studies have reported significant negative associations between sporadic non‐steroidal anti‐inflammatory drug (NSAID) use and keratinocyte carcinoma (KC) while reporting null results for regular use. This pattern may be partially explained by the operational expression of NSAID exposure and analytic model assumptions. Our goals were to quantify the association between NSAIDs and KC and to explore the impact of exposure metrics and modeling assumptions on observed associations.MethodsWe conducted a prospective cohort study by linking data from the Veterans Affairs Topical Tretinoin Chemoprevention Trial and the VA Pharmacy Benefits Management database. NSAID use was categorized according to cyclooxygenase selectivity, timing of initiation, and frequency of use. Data were analyzed using time‐varying and time‐fixed multivariable‐adjusted Cox proportional hazard models [Correction made here after initial online publication]. Simulated null data were generated and analyzed to explore potential biases introduced by the models and the exposure metrics.ResultsDuring a median follow‐up time of 2 years for basal cell carcinoma and 2.5 years for squamous cell carcinoma, 472 occurrences of BCC and 309 occurrences of SCC were observed. Time‐fixed analyses of NSAID exposure metrics produced significant negative associations, whereas time‐varying analyses produced null results. Analysis of simulated null data revealed the potential for strong bias in the time‐fixed analyses.ConclusionsThis study did not identify a negative association between NSAIDs and KC. The disparity between the time‐fixed and the time‐varying analyses highlights the extent to which operational definitions of drug exposures and reliance on time‐fixed methods may introduce bias. Published 2011. This article is a US Government work and is in the public domain in the USA.
Psychometric development and reliability analysis of a patient satisfaction with interpersonal relationship with navigator measure: a multi‐site patient navigation research program study
Authors: Jean‐Pierre Pascal , Fiscella Kevin , Winters Paul C. , Post Douglas , Wells Kristen J. , McKoy June M. , Battaglia Tracy , Simon Melissa A. , Kilbourn Kristin ,   The Patient Navigation Research Program Group
Published: June 2011

AbstractBackgroundPatient navigation (PN) is a method for addressing racial–ethnic and socioeconomically based disparities in cancer‐related care. Patient navigators provide logistic and emotional support to underserved patients to facilitate successful completion of diagnostic and treatment care. Yet, little is known about patient satisfaction with the relationship with a navigator due to a dearth of instruments measuring satisfaction.ObjectiveThe objective of this study was to validate the Patient Satisfaction with Interpersonal Relationship with Navigator (PSN‐I) measure for patients undergoing diagnostic and/or therapeutic cancer care.MethodsWe administered the PSN‐I to 783 participants from the nine different sites of the National Cancer Institute sponsored Patient Navigation Research Program. We evaluated the latent structure and internal consistency of the PSN‐I using principal components analysis (PCA) and Cronbach coefficient alpha (α), respectively. We used correlation analyses to examine divergence and convergence of the PSN‐I with the Patient Satisfaction with Cancer‐related Care (PSCC), the Rapid Estimate of Adult Literacy in Medicine (REALM) Long Form, and patients' demographics.ResultsThe PCA revealed a coherent set of items that explicates 76.6% of the variance in PSN‐I. Reliability assessment revealed high internal consistency (α ranging from 0.95 to 0.96). The PSN‐I had good face validity as well as convergent and divergent validities as indicated by moderate correlations with score on the PSCC (all ps < 0.0001) and non‐significant correlations with primary language, marital status, and scores on the REALM Long Form (all ps > 0.05).ConclusionThe PSN‐I is a valid and suitable measure of satisfaction with a patient navigator for the present sample. Copyright © 2011 John Wiley & Sons, Ltd.
High‐Performance Plasma‐Polymerized Alkaline Anion‐Exchange Membranes for Potential Application in Direct Alcohol Fuel Cells
Authors: Zhang Chengxu , Hu Jue , Nagatsu Masaaki , Meng Yuedong , Shen Wei , Toyoda Hirotaka , Shu Xingsheng 
Published: June 2011

AbstractAlkaline anion‐exchange membranes (AAEMs) are becoming significant materials for application in fuel cells. Considering the mobility of hydroxide ions is inherently slower than that of proton in dilute solution, AAEMs with high ion conductivity and several microns thickness are promising. In this study, ultra‐thin AAEMs are successfully synthesized by plasma polymerization. The attenuated total reflection Fourier transform infrared spectroscopy, X‐ray photoelectron spectroscopy, and thermo gravimetric analysis demonstrate that the benzyltrimethylammonium cationic groups are successfully introduced into the polymer matrix via plasma polymerization, quaternization, and alkalization. The physicochemical and electrochemical characteristics, including ionic exchange capacity, water uptake, thermal stability, chemical stability, and ionic conductivity, are measured. The plasma‐polymerized AAEMs exhibit a satisfactory thermal stability, chemical stability, ionic exchange capacity (1.29 mmol · g−1), ionic conductivity (0.0331 S · cm−1), and activation energy (7.632 kJ · mol−1), suggesting a great potential for application in direct alcohol fuel cells. magnified image
Testosterone and prolactin increase carboxypeptidase‐D and nitric oxide levels to promote survival of prostate cancer cells
Authors: Thomas Lynn N. , Morehouse Timothy J. , Too Catherine K.L. 
Published: June 2011

AbstractBACKGROUNDPlasma‐membrane carboxypeptidase‐D (CPD) releases arginine from extracellular substrates. Arginine is converted intracellularly to nitric oxide (NO). This study determined the effects of testosterone (T) and prolactin (PRL) on CPD expression, and the role(s) of CPD in NO production and survival of prostate cancer (PCa) cells.METHODSLNCaP cells were treated with T and/or PRL. CPD expression was measured. Regulation by T (low doses) was determined using transfected cells overexpressing 5α‐reductase type‐1 (5αR1), which converts T to the more potent dihydrotestosterone. The effects of siRNAs targeting CPD (siCPDs) on NO production, cell viability, and apoptosis were determined using DAF2‐DA, MTS, and Annexin‐V assays. The effects of PRL/T on CPD/NO levels in PC‐3, MDA‐PCa‐2b, and 22Rv1 cells were also evaluated.RESULTSIn LNCaP cells, 10 nM T and 10 ng/ml PRL‐upregulated CPD mRNA/protein levels. In pTRE‐transfectants, 1 nM T‐upregulated CPD mRNA levels by ∼2‐fold over controls, whereas 0.1 nM T caused similar upregulation in pTRE‐5αR1‐transfectants. In LNCaP cells cultured in arginine‐free medium, addition of furylacryloyl‐Ala‐Arg (FAR; CPD substrate) increased NO levels. NO production, with FAR, was enhanced by PRL and/or T. siCPDs decreased NO production and cell viability, but increased apoptosis. QPCR analysis showed T/PRL‐upregulation of CPD in 22Rv1, MDA‐PCa‐2b, and PC‐3 cells. NO production was doubled by T/PRL in 22Rv1 cells, tripled by T in MDA‐PCa‐2b cells, and marginally increased by PRL in MDA‐PCa‐2b and PC‐3 cells.CONCLUSIONST and PRL upregulate CPD and NO levels in PCa cells. CPD increases NO production to promote PCa cell survival. Prostate 72:450–460, 2012. © 2011 Wiley Periodicals, Inc.
The impact of deep convection on the West African summer monsoon climate: a regional climate model sensitivity study
Authors: Sylla M. B. , Giorgi F. , Ruti P. M. , Calmanti S. , Dell'Aquila A. 
Published: June 2011

AbstractThe role of the representation of deep convection on key elements of the West African summer monsoon climate is addressed using the Regional Climate Model RegCM3. Two simulations in which a scheme of deep convection is activated and then turned off are performed and intercompared. Results show that the presence of deep convective heating along the intertropical convergence zone sustains increased lower‐level baroclinicity favoring intensification of the jet core and leading to a more realistic African easterly jet. In addition, although the isentropic potential vorticity (IPV) is lower when the convection scheme is switched off, African easterly waves (AEWs) are still generated and propagate westwards but they dissipate around the west coast. Substantial differences between the two simulations occur mainly at the 6‐ to 9‐day time‐scale over land, when much weaker activity is simulated in the absence of convection. This indicates that orographic friction and low‐level large‐scale moisture convergence, generating high values of latent heat and IPV, may play the dominant role in the genesis and growth of AEWs and that deep convection acts to strengthen the overall wave activity and to favor their west coast development. Copyright © 2011 Royal Meteorological Society
A pre‐operative approach of range of motion simulation and verification for femoroacetabular impingement
Authors: Chang Ta‐Cheng , Kang Hyosig , Arata Louis , Zhao Weizhao 
Published: June 2011

AbstractBackgroundFemoroacetabular impingement (FAI) is increasingly recognized as a potential cause of hip osteoarthritis. A system capable of pre‐operatively simulating hip range of motion (ROM) by given surface models from either healthy or FAI diseased bone is desirable.MethodsAn impingement detection system using bounding sphere hierarchies was first developed. Both precision and accuracy of the impingement detection system were verified by a custom‐designed phantom to imitate ball‐and‐socket hip movement. The impingement detection system was then implemented into the hip ROM simulation system to simulate the ROM of (1) healthy pelvis and femur, and (2) healthy pelvis and pathologic femur. The ROM simulation system was also verified by manipulating sawbones under the navigation of an optical tracking system.ResultsThe impingement detection system achieved a distance error of 0.53 ± 0.06 mm and an angular error of 0.28 ± 0.03°. The impingement detection accuracies were 100%, 100%, and 96% in three different phantom orientations, respectively. The mean errors between simulated and verified ROM were 0.10 ± 1.39° for the ‘healthy pelvis and femur’ group, and − 2.38 ± 3.49° for the ‘healthy pelvis and pathologic femur’ group.ConclusionThe present study demonstrates a pre‐operative approach to virtually simulate and predict the functional hip ROM based on the given bone models. The impingement detection and ROM simulation systems developed may also be used for other orthopedic applications. Copyright © 2011 John Wiley & Sons, Ltd.
Training program for fundamental surgical skill in robotic laparoscopic surgery
Authors: Suh Irene , Mukherjee Mukul , Oleynikov Dmitry , Siu Ka‐Chun 
Published: June 2011

AbstractBackgroundAlthough the use of robotic laparoscopic surgery has increased in popularity, training protocols for gaining proficiency in robotic surgical skills are not well established. The purpose of this study was to examine a fundamental training program that provides an effective approach to evaluate and improve robotic surgical skills performance using the da Vinci™ Surgical System.MethodsFifteen medical students without any robotic surgical experience were recruited. Participants went through a 4‐day training program for developing fundamental robotic surgical skills and received a retention test 1 day after the completion of training. Data analysis included time to task completion, average speed, total distance traveled and movement curvature of the instrument tips, and muscle activities of the participants' forearms. Surgical performance was graded by the modified Objective Structured Assessment of Technical Skills for robotic laparoscopic surgery. Finally, participants evaluated their own performance after each session through questionnaires.ResultsSignificant training effects were shown for the time to task completion (p < 0.001), average speed (p < 0.01), and movement curvature (p < 0.05) for the test conditions. Significant learning effects were also found for EMG activation (p < 0.05). Participants reported more mastery, familiarity, and self‐confidence and less difficulty in performing fundamental tasks with the surgical robot in both post‐testing and retention sessions.ConclusionsOur 4‐day training program comprising of a series of training tasks from fundamental to surgical skill levels was effective in improving surgical skills. Further studies are required to verify these findings with a longer period of retention. Copyright © 2011 John Wiley & Sons, Ltd.