bluuebunny/crossref_metadata_2025_split huggingface dataset:
Influence of Coupling Agent on the Morphology of Multifunctional, Degradable Shape-Memory Polymers
Authors: Fang Liang , Yan Wan , Nöchel Ulrich , Zierke Michael , Behl Marc , Kratz Karl , Lendlein Andreas 
Published: December 2013

ABSTRACTMultifunctional polymer-based biomaterials, which combine degradability and shapememory capability, are promising candidate materials for biomedical implants. An example is a degradable multiblock copolymer (PDC), composed of poly(p-dioxanone) (PPDO) as hard and poly(ε-caprolactone) (PCL) as switching segments. PDC exhibits a unique linear mass loss during hydrolytic degradation, which can be tailored by the PPDO to PCL weight ratio, as well as an excellent thermally induced dual-shape effect. PDC can be synthesized by co-condensation of two oligomeric macrodiols (PCL-diol and PPDO-diol) using aliphatic diisocyanates as coupling agent. Here, we investigated whether different morphologies could be obtained for PDCs synthesized from identical oligomeric macrodiols (PCL-diol with Mn = 2000 g·mol-1 and PPDO-diol with Mn = 5300-5500 g·mol-1) with 2, 2(4), 4-trimethyl-hexamethylene diisocyanate (TMDI) and 1, 6-hexamethylene diisocyanate (HDI), respectively. More specifically, atomic force microscopy (AFM) was utilized for an investigation of the surface morphologies in solution casted PDC thin films in the temperature range from 20 °C to 60 °C. The results obtained in differential scanning calorimetry (DSC) and AFM demonstrated that different morphologies were obtained when TMDI (PDC-TMDI) or HDI (PDC-HDI) were used as linker. PCL related crystals in PDC-HDI were more heterogeneous and less ordered than those in PDCTMDI, while HDI resulted in a larger degree of crystallinity than TMDI. This research provides some new suggestions for choosing a suitable coupling agent to tailor the required morphologies and properties of SMPs with crystallizable switching segments.
The influence of the co-monomer ratio of poly[acrylonitrile-co-(N-vinylpyrrolidone)]s on primary human monocyte-derived dendritic cells
Authors: Roch Toralf , Behl Marc , Zierke Michael , Pierce Benjamin F. , Kratz Karl , Weigel Thomas , Ma Nan , Lendlein Andreas 
Published: December 2013

ABSTRACTA major goal in the field of regenerative medicine is to improve our understanding of how biomaterial properties affect cells of the immune system. Systematic variation of defined chemical properties could help to understand which factors determine and modulate cellular responses. A series of copolymers poly[acrylonitrile-co-(N-vinylpyrrolidone)]s (P(AN-co-NVP)) served as model system, in which increasing hydrophilicity was adjusted by increasing the content related to the NVP based repeating units (nNVP) (0, 4.6, 11.8, 22.3, and 29.4 mol%). The influence of increasing nNVPcontents on cellular response of human primary monocyte derived dendritic cells (DC), which play a key role in the initiation of immune responses, was investigated. It was shown using the LAL-Test as well as a macrophage-based assay, that the materials were free of endotoxins and other microbial contaminations, which could otherwise bias the readout of the DC experiments. The increasing nNVPcontent led to a slightly increased cell death of DC, whereas the activation status of DC was not systematically altered by the different P(AN-co-NVP)s as demonstrated by the expression of co-stimulatory molecule and cytokine secretion. Similarly, under inflammatory conditions mimicked by the addition of lipopolysaccharides (LPS), neither the expression of co-stimulatory molecules nor the release of cytokines was influenced by the different copolymers. Conclusively, our data showed that this class of copolymers does not substantially influence the viability and the activation status of DC.
Hysteresis modeling of porous SMA for drug delivery system designed and fabricated by the laser-assisted sintering
Authors: Shishkovsky Igor V. 
Published: December 2013

ABSTRACTIn this report we develop a complete mathematical model for a porous scaffold from nitinol (NiTi – intermetallic phase) with a shape memory effect (SME), fabricated layerwise via the selective laser sintering (SLS) process. The operation of the SME bio-fluidic MEMS involves such physical process as a heat transfer, a phase transformation with a temperature hysteresis, stress-strain and electrical resistance variations accompanied the phase transformation. The simulations were conducted for the electro- and a thermo- mechanical hysteresis phenomenon, during the SME in the porous nitinol structures of the cylinder shape, which allow to formulate a recommendations for SLS. Previously done the temperature evolution of electrical resistivity was compared with our present calculations as a function of the laser-processing parameters for three dimensional nitinol samples. This model can be used for an estimation of a drug delivery system route during a porous phase volume changing.
Influence of diisocyanate reactivity and water solubility on the formation and the mechanical properties of gelatin-based networks in water
Authors: Gebauer Tim , Neffe Axel T. , Lendlein Andreas 
Published: December 2013

ABSTRACTGelatin can be covalently crosslinked in aqueous solution by application of diisocyanates like L-lysine diisocyanate ethyl ester in order to form hydrogels. Reaction of isocyanate groups with water is however a limiting factor in hydrogel network formation and can strongly influence the outcome of the crosslinking process. Here, diisocyanates with different water solubility and reactivity were applied for the formation of gelatin-based hydrogel networks and the mechanical properties of the hydrogels were investigated to gain a better understanding of starting material/ hydrogel property relations. L-Lysin diisocyanate ethyl ester (LDI), 2,4-toluene diisocyanate (TDI), 1,4-butane diisocyanate (BDI), and isophorone diisocyanate (IPDI) were selected, having different solubility in water ranging from 10-4 to 10-2 mol·L-1. BDI and LDI were estimated to have average reactive isocyanates groups, whereas TDI is highly reactive and IPDI has low reactivity. Formed hydrogels showed different morphologies and were partially very inhomogeneous. Gelation time (1 to 50 minutes), water uptake (300 to 900 wt.-%), and mechanical properties determined by tensile tests (E-moduli 35 to 370 kPa) and rheology (Shear moduli 4.5 to 19.5 kPa) showed that high water solubility as well as high reactivity leads to the formation of poorly crosslinked or inhomogeneous materials. Nevertheless, diisocyanates with lower solubility in water and low reactivity are able to form stable, homogeneous hydrogel networks with gelatin in water.
Generation and Surface Functionalization of Electro Photographic Toner Particles for Biomaterial Applications
Authors: Speyerer Christian , Borchers Kirsten , Storsberg Joachim , Tovar Günter E. M. , Hirth Thomas , Weber Achim 
Published: December 2013

ABSTRACTIn this paper, we provide the investigation about the controlled surface functionalization of acrylic toner particles for electro photography (“laser printing”) with sodium hydroxide and the subsequent carbodiimide-mediated coupling of numerous functional amines onto the generated carboxylic group. Various chemically valuable functionalities, comprising of thiol, alkyne and azide, were bound onto the particles’ surface and allow for further versatile modifications via huisgen cycloaddition as well as thiol-ene reaction. The functionalization of the acrylic toner surface with alkyne, azide and carboxylic groups increased the cell viability up to 178 % ± 22 % and might offer an interesting path for new applications using common laser printing techniques.
QUATERNARY AMMONIUM ANTIMICROBIAL POLYMERS
Authors: Domb Abraham J. , Beyth Nurit , Farah Shady 
Published: December 2013

ABSTRACTPolymers possessing antimicrobial activity have been used for self sterilization surfaces as well as agents for treating contaminated water. Cationic polymers based on quaternary ammonium or guanidine groups have shown high inherent antimicrobial activity where the activity is related to the disruption of the microorganism cell wall. A range of antimicrobial nanoparticles possessing active quaternary ammonium groups with one of the alkyl is a an octyl chain have been synthesized. These nanoparticles were incorporated in dental restoration compositions to form self sterile composites. Quaternary ammonium polyethyleneimine nanoparticles with N-octyl dimethyl residues, demonstrated high antibacterial effect.
Aging Studies of Pu-238 and -239 Containing Calcium Phosphate Ceramic Waste-forms
Authors: Fong Shirley K. , Metcalfe Brian L. , Scheele Randall D. , Strachan Denis M. 
Published: December 2013

ABSTRACTA calcium phosphate ceramic waste-form has been developed at AWE for the immobilisation of chloride containing wastes arising from the pyrochemical reprocessing of plutonium. In order to determine the long term durability of the waste-form, aging trials have been carried out at PNNL. Ceramics were prepared using Pu-239 and -238, these were characterised by PXRD at regular intervals and Single Pass Flow Through (SPFT) tests after approximately 5 yrs.While XRD indicated some loss of crystallinity in the Pu-238 samples after exposure to 2.8 x 1018 α decays, SPFT tests indicated that accelerated aging had not had a detrimental effect on the durability of Pu-238 samples compared to Pu-239 waste-forms.
Fabrication and Characterization of CoFe2O4-Polymer Nanocomposite Thin-Films
Authors: Liu Xiaohua , Liu Shuangyi , O’Brien Stephen 
Published: December 2013

ABSTRACTMagnetic cobalt ferrite nanoparticles provide a pathway towards nanocomposites, due to the ability to fabricate particle-matrix thin films in the submicron range. In this work flexible particulate 0-3 type thin-films, composed of magnetic CoFe2O4 particles (8-18 nm) and ferroelectric poly(vinylidene fluoride-co-hexafluoropropene) (P(VDF-HFP)) polymer, have been fabricated via multiple spin-coating. The thickness of the thin-films was controlled in the range of 500 nm to 1.2 μm, with magnetic particles dispersively embedded in the polymer matrix. Structural information was analyzed by TEM, XRD, HRTEM and SEM. The dielectric and magnetic properties of the cobalt ferrite/copolymer thin films are systematically investigated. The nanocomposite thin films exhibit composition-dependent effective permittivity and loss tangent, as well as temperature and composition-dependent specific saturation magnetization (Ms). The coercivity (Hc) was not affected by the composite’s composition. These films have great potential in smart magnetic devices and biomagnetic applications.
Room Temperature Current Suppression on Magnetic Tunnel Junction Based Molecular Spintronics Devices
Authors: Tyagi Pawan 
Published: December 2013

ABSTRACTMolecular conduction channels between two ferromagnetic electrodes can produce strong exchange coupling and dramatic effect on the spin transport, thus enabling the realization of novel logic and memory devices. To realize such device, we produced Multilayer Edge Molecular Spintronics Devices (MEMSDs) by bridging the organometallic molecular clusters (OMCs) across a ∼2 nm thick insulator of a magnetic tunnel junction (MTJ), along its exposed side edges. These MEMSDs exhibited unprecedented increase in exchange coupling between ferromagnetic films and dramatic changes in the spin transport. This paper focuses on the dramatic current suppression phenomenon exhibited by MEMSDs at room temperature. In the event of current suppression, the effective MEMESDs’ current reduced by as much as six orders in magnitude as compared to the leakage current level of a MTJ test bed. Current suppression phenomenon was found to be associated with the equally dramatic changes in the MTJ test beds due to OMCs. Role of OMC in changing MTJ test bed properties was determined by the three different types of magnetic characterizations: SQUID Magnetometer, Ferromagnetic Resonance, and Magnetic Force Microscopy. Observation of current suppression by independent research groups and supporting studies on similar systems will be crucially important to unequivocally establish the utility of MEMSD approach.
Chaotic behaviour of the map x ↦ ω(x, f)
Authors: D’Aniello Emma , Steele Timothy 
Published: December 2013

Abstract
Let K(2ℕ) be the class of compact subsets of the Cantor space 2ℕ, furnished with the Hausdorff metric. Let f ∈ C(2ℕ). We study the map ω
f: 2ℕ → K(2ℕ) defined as ω
f (x) = ω(x, f), the ω-limit set of x under f. Unlike the case of n-dimensional manifolds, n ≥ 1, we show that ω
f is continuous for the generic self-map f of the Cantor space, even though the set of functions for which ω
f is everywhere discontinuous on a subsystem is dense in C(2ℕ). The relationships between the continuity of ω
f and some forms of chaos are investigated.
Weighted inequalities for some integral operators with rough kernels
Authors: Riveros María , Urciuolo Marta 
Published: December 2013

Abstract
In this paper we study integral operators with kernels $$K(x,y) = k_1 (x - A_1 y) \cdots k_m \left( {x - A_m y} \right),$$
$$k_i \left( x \right) = {{\Omega _i \left( x \right)} \mathord{\left/
{\vphantom {{\Omega _i \left( x \right)} {\left| x \right|}}} \right.
\kern-\nulldelimiterspace} {\left| x \right|}}^{{n \mathord{\left/
{\vphantom {n {q_i }}} \right.
\kern-\nulldelimiterspace} {q_i }}}$$ where Ωi: ℝn → ℝ are homogeneous functions of degree zero, satisfying a size and a Dini condition, A
i are certain invertible matrices, and n/q
1 +…+n/q
m = n−α, 0 ≤ α < n. We obtain the appropriate weighted L
p-L
q estimate, the weighted BMO and weak type estimates for certain weights in A(p, q). We also give a Coifman type estimate for these operators.
Superdeformed structures and low Ω parity doublet in Ne-S nuclei near neutron drip-line
Authors: Singh Shailesh , Praharaj Choudhury , Patra Suresh 
Published: December 2013

AbstractThe structures of Ne, Na, Mg, Al, Si, P and S nuclei near the neutron drip-line region are investigated in the frame-work of relativistic mean field theory and non-relativistic Skyrme Hartree-Fock formalism. The recently discovered nuclei 40Mg and 42Al, which are beyond the drip-line predicted by various mass formulae are located within these models. We find many largely deformed neutron-rich nuclei, whose structures are analyzed. From the structure anatomy, we find that at large deformation low orbits of opposite parities (e.g. $$\frac{1} {2}^ +$$ and $$\frac{1} {2}^ -$$) occur close to each other in energy.
Adult intestinal intussusception — A report of 2 cases and literature review
Authors: Habib Khalid , Jacob George 
Published: December 2013

Abstract
Every five years or so a case of adult small bowel intussusception secondary to pathologies such as inflammatory fibroid polyp (IFP) appears in English literature. Likewise rare cases of adult colonic intussusception due to a tumour have been reported including, more recently, their successful management by laparoscopic approach. We describe two such cases, one each of small bowel and large bowel intussusception, due to IFP and caecal tumour respectively and discuss their management. We also suggest role of combined laparoscopy/endoscopy in selected cases of colonic resections.
A rare cause of respiratory insufficiency: case presentation
Authors: Diaconu Camelia , Paraschiv Bianca , Lungu Răzvan , Bartoş Daniela 
Published: December 2013

Abstract
We report the case of a 73 year old woman who presented for progressive dyspnea. Her medical history included thyroidectomy 15 years ago, myocardial infarction, recurrent paroxysmal atrial fibrillation and femoral fracture two weeks previously, conservatively treated. Physical examination revealed absent breath sounds in the left hemithorax, up to the apex, and crackles in the right hemithorax. The acid-base balance showed acute hypoxemic respiratory failure. The chest X-Ray revealed left diaphragmatic paralysis. Thoracic CT-scan was performed, which excluded the pulmonary embolism and revealed left diaphragmatic relaxation, ascension of the splenic angle of the colon, stomach and spleen up to the projection of left lung hilum, and right postero-basal alveolar condensation process. Diaphragm dysfunction can be caused by various disorders, including phrenic paralysis. This pathology should be considered in the differential diagnosis of acute respiratory failure.
Body fat, lean mass and bone density of the spine and forearm in women
Authors: Boyanov Mihail 
Published: December 2013

Abstract
The aim of this study was to determine the relative contributions of fat mass and lean mass to the variability of bone mineral density (BMD) of the lumbar spine and proximal 1/3 forearm in Bulgarian women. 180 women aged 21 through 76 years participated (mean age 50.8 ± 9.7 years). 130 of them were postmenopausal. Lumbar spine and forearm BMD were measured by dual-energy X-ray absorptiometry, followed by a whole-body scan for body composition examination (Hologic QDR 4500 A device, software version 1.26). The strongest linear correlation was found with body weight (r2=0.231, p<0.001). Using this model, 18.1 % of the variability of lumbar spine BMD was attributable to fat mass and 16.0 % to lean mass. The relative influence of fat mass on L1-L4 BMD was greater than that of lean mass (standardized regression coefficient 0.291 versus 0.199). There were weak correlations of body weight, fat and lean mass with the forearm BMD. Lean mass correlated slightly better (r=0.187, p=0.050) to forearm BMD than fat mass (r=0.162, p=0.055). In conclusion, the differentiation between fat and lean mass does not strengthen the BMD correlations beyond that with total body weight.
Enzymatic synthesis of a chiral chalcogran intermediate
Authors: Mastihuba Vladimír , Čepec Pavel , Vlčková Silvia , Farkašová Erika , Mastihubová Mária , Bobal Pavel 
Published: December 2013

AbstractTwo lipases, Novozyme 435 (lipase B from Candida Antarctica) and Lipozyme TL IM (Thermomyces lanuginosus) were used successfully for the kinetic resolution of racemic 1-(2-furyl)-3-pentanol, the key intermediate in synthesis of the bark beetle pheromone, chalcogran. The desired S-(+)-enantiomer was prepared in enantiomeric excesses higher than 98 % and with yields of 26.3 % and 32.5 %, respectively. Methyl tert-butyl ether and vinyl acetate were found to be the best reaction media and the acetyl donor to achieve fast and effective resolution.
Patagonicola: a new genus of xeromelissine bee from Argentina (Hymenoptera: Apoidea: Colletidae)
Authors: Packer Laurence 
Published: December 2013

AbstractPatagonicolaPackernew genusis described for two species of xeromelissine bee (Hymenoptera: Colletidae) from Patagonian Argentina. One species,P. graveliPackernew speciesis described; the second species,P. aenigma(Packer)new combination, originally placed inChilicolaSpinola, 1851 subgenusChilioediscelisToro and Moldenke, 1979, is designated as the type species. The new genus is superficially most similar toXenochilicolaToro and Moldenke, 1979 but possesses none of the derived characteristics that were originally used to define that genus. Results of a phylogenetic analysis, based upon 114 morphological characters, are presented and suggest that the new genus is the sister clade to (GeodiscelisMichener and Rozen, 1999 +XeromelissaCockerell, 1926). An illustrated key is provided for the genera of Xeromelissinae and for the two species ofPatagonicola.
Circumferential Reconstruction of Severe Acetabular Labral Damage Using Hamstring Allograft: Surgical Technique and Case Series
Authors: Rocha Pedro Costa , Klingenstein Gregory , Ganz Reinhold , Kelly Bryan T. , Leunig Michael 
Published: December 2013

Introduction With excessive acetabular coverage, such as coxa profunda or protrusio, contact between the femoral neck and acetabular rim cause direct damage to the labrochondral junction, and indirect edge loading from a levering effect which may result in hip arthrosis. Arthrosis may be delayed or avoided by addressing the overcoverage and restoring mechanical function of the labrum. We describe four cases of adjunctive complete acetabular labral replacement for circumferential, irreparable labral injury using fresh frozen semitendinous allografts through surgical hip dislocation. Materials and Methods Over a two-year period four patients (age range: 20 to 47 years) underwent surgical hip dislocation to address femoroacetabular impingement with rim trimming, femoral osteochondroplasty, and labral reconstruction. Pre- and postoperative patient reported outcomes were assessed by Oxford Hip Score (OHS), Hip Outcome Score (HOS), and Global Treatment Outcome (GTO) score. Disease progression was graded using AP pelvic radiographs and arthroMR. Results The average LCE correction was 18° (range 7-25°), achieving an average LCE of 33° (range 32-35) postoperatively. Using protected weight bearing all trochanteric osteotomies healed within six weeks after surgery. OA did not progress in any hips. Mean OHS and HOS scores improved 6.3 and 19.8 at one-year follow up. All four patients reported good results according to the GTO. There were two adverse events that resolved and did not affect outcome. Summary and Conclusions Despite complex deformities and preexisting cartilage and labrum wear in this young cohort, three of four patients reported significant functional improvement after treatment of this rare condition. Preliminary experience with circumferential labral reconstruction using hamstring allografts is promising, although long-term data needs to be established.
Predictors of Blood Loss and Haematocrit after Periacetabular Osteotomy
Authors: Lee Cara Beth , Kalish Leslie A. , Millis Michael B. , Kim Young-Jo 
Published: December 2013

Background Acetabular dysplasia is a common cause of hip pain that can lead to osteoarthritis. Periacetabular osteotomy (PAO) is an effective procedure to treat symptomatic dysplasia in properly selected patients. Purpose This study aims to determine patient or perioperative variables that are predictive of blood loss (EBL) and postoperative haematocrit (HCT) with PAO. Patients and Methods Between March 2009 and October 2011, 169 PAOs in 141 patients were performed. Associations with EBL (log-transformed) and lowest postoperative haematocrit (post-HCT, <26 vs. ≥26) were assessed by regression analysis, adjusting for surgeon and for within-patient correlations. Results Geometric mean EBL was 925 mL (range 200–3900mL; 95% CI: 851.3, 1005.1). There was 11.1% greater blood loss per hour of surgery (p = 0.02). Pre-Operative HCT averaged (±SD) 36.1 (±3.3). In 119 cases (71%), the post-HCT was <26. Lower pre-operative HCT correlated with post-HCT <26 (p<0.001); the median ratio of the lowest postoperative HCT to the pre-operative HCT was 0.687 (5th, 95th percentiles: 0.538, 0.781). Age, body mass index (BMI), arthrotomy, and anaesthesia-type showed no association with EBL or post-HCT. Conclusions Longer duration of surgery correlated with increased blood loss during PAO. Current guidelines recommend considering transfusion at haemoglobin ≤8 g/dL for postoperative patients. The median nadir post-HCT was 31% lower than the pre-operative value, a ratio that may help determine the need for pre-operative blood donation. This information facilitates future investigation of blood management with PAO.