bluuebunny/crossref_metadata_2025_split huggingface dataset:
System Identification for Experimental Study for Polymerization Catalyst Reaction in Fluidized Bed
Authors: Ibrehem Ahmmed S. 
Published: October 2012

In this work, system identification method is used to capture the reactor characteristics of production rate of polyethylene (PE) based on published experimental data. The identification method is used to measure the percentage effect on the production rate of PE by measuring the effect of input factors of temperature of reaction, hydrogen concentration, and [Al]/[Ti] molar catalyst ratio. Temperature of reaction has big effects equal 52.4 % on the output of the system and 47.6 % on interaction of the system's parameters compare to other two factors. Also, hydrogen concentration has big effect equal 45.66 % on the output of the system and 14.7 % on interaction of the system's parameters. [Al]/[Ti] molar catalyst ratio has big effect on interaction of the system equal 28.6 and 1.94 % on the output of the system but less than the reaction temperature and hydrogen concentration. All these results depend on experiment results and these results are very important in industrial plants. © 2011 by Authors, Published by BCREC Group. This is an open access article under the CC BY-SA License (https://creativecommons.org/licenses/by-sa/4.0)
The Role of Sulfur in Solution‐Processed Cu2ZnSn(S,Se)4 and its Effect on Defect Properties
Authors: Duan Hsin‐Sheng , Yang Wenbing , Bob Brion , Hsu Chia‐Jung , Lei Bao , Yang Yang 
Published: October 2012

AbstractUnderstanding the electrically active defects in kesterite Cu2ZnSn(S,Se)4(CZTSSe) is critical for the continued development of solar cells based on this material, but challenging due to the complex nature of this polycrystalline multinary material. A comparative study of CZTSSe alloys with three different bandgaps, made by introducing different fractions of sulfur during the annealing process, is presented. Using admittance spectroscopy, drive level capacitance profiling, and capacitance‐voltage profiling, the dominant defect energy level present in the low sulfur content device is determined to be 0.134 eV above the valence band maximum, with a bulk defect density of 8 × 1014 cm−3, while the high sulfur content device shows a deeper defect energy level of 0.183 eV and a higher bulk defect density, 8.2 × 1015 cm−3. These findings are consistent with the current density–voltage characteristics of the resulting solar cells and their external quantum efficiency. It suggests that as the sulfur content increases, the bandgap of the absorber is enlarged, leading to an increasing open‐circuit voltage (Voc), that is accompanied by stronger recombination due to the higher defect density of the sulfur‐rich absorber. This is reflected in large Voc deficit and poor carrier collection of the high sulfur content device.
Interaction of Ferromagnetic Shape Memory Alloys and RGD Peptides for Mechanical Coupling to Cells: from Ab Initio Calculations to Cell Studies
Authors: Zink Mareike , Szillat Florian , Allenstein Uta , Mayr Stefan G. 
Published: October 2012

AbstractDue to their magneto‐mechanical coupling and biocompatibility, Fe‐Pd based ferromagnetic shape memory alloys are a highly promising materials class for application as contact‐less magneto‐mechanical transducers in biomedical environments. For use in cell and tissue actuators or strain sensors, sufficient adhesion to mediate strains clearly constitutes a prerequisite. As the RGD sequence is the most important binding motif for mammalian cells, which they express to facilitate adhesion, the potential of RGD coatings to achieve this goal is explored. Employing large‐scale density functional theory calculations the physics of bonding between RGD and Fe‐Pd surfaces, which is characterized by coordinate bonds of O and N atoms to Fe, accompanied by electrostatic contributions, is clarified. Theoretical predictions on adhesion, that are confirmed experimentally, suggest RGD as suitable strain mediator to Fe‐Pd surfaces. On the cell side, favorable adhesion properties of RGD‐coated Fe‐Pd are manifested in cell morphology and spreading behavior. Demonstrating that the adhesion forces between RGD and Fe‐Pd exceed those exerted by cells to the RGD coating, as well as traction forces acting onto integrin bonds, the findings pave the way for novel type of applications as cell and tissue actuator or sensor within the areas of tissue engineering and regenerative medicine.
Nanoparticle Stacks with Graded Refractive Indices Enhance the Omnidirectional Light Harvesting of Solar Cells and the Light Extraction of Light‐Emitting Diodes
Authors: Fang Cheng‐Yi , Liu Yu‐Lun , Lee Yang‐Chun , Chen Hsuen‐Li , Wan De‐Hui , Yu Chen‐Chieh 
Published: October 2012

AbstractIn this study, nanoparticles (NPs) of various types and sizes are arranged to enhance both the omnidirectional light harvesting of solar cells and the light extraction of light emitting diodes (LEDs). A graded‐refractive‐index NP stack can minimize reflectance, not only over a broad range of wavelengths but also at different incident angles; the photocurrent of silicon‐based solar cells an also be significantly improved omnidirectionally. In addition, the optical gradient of an NP stack can also enhance the light‐extraction efficiency of LEDs, due to both the graded refractive index and the moderate surface roughness. Large particles having sizes on the same order of the wavelength of the incident light roughen the LED surfaces further and extract light from beyond the critical angle, as supported by three‐dimensional finite‐difference time‐domain simulations. Using this approach, the photoluminescence intensity can be increased by up to sevenfold. The developed technique: arranging sequences of different NPs in graded‐refractive‐index stacks, and considering their ability to scatter light due to their sizes and optical constants, may also significantly improve the performance of various optoelectronic devices.
Fibroblast growth factor receptor 1 (FGFR1) variants and craniofacial variation in Amerindians and related populations
Authors: Gómez‐Valdés Jorge A. , Hünemeier Tábita , Contini Verônica , Acuña‐Alonzo Victor , Macin Gastón , Ballesteros‐Romero Mónica , Corral Pau , Ruiz‐Linares Andres , Sánchez‐Mejorada Gabriela , Canizales‐Quinteros Samuel , Martínez‐Abadías Neus , Salzano Francisco M. , González‐José Rolando , Bortolini Maria cátira 
Published: October 2012

AbstractObjectives:The polymorphic site rs4647905 of the FGFR1 gene was previously associated with a decrease in cephalic index (CI). Here, we evaluate the relationships between genotypes and cephalometric measurements and indices in one Mexican Native and two mestizo Mexican populations using two haplotype‐tag SNPs (rs4647905 and rs3213849) that represent >85% of the FGFR1 variability, plus three other SNPs (rs2293971, rs2304000, and rs930828) situated nearby. In addition, we genotyped five South American natives, two European, one African, and one Siberian populations to evaluate their intra and intercontinental population diversity.Methods:The five SNPs were tested and the craniofacial measurements and indices were collected using standardized procedures. Principal Component Analysis was used to verify individual/population comparisons. Associations were performed through the generalized linear model (GLM), coefficient of determination R2 and linear regression tests.Results:We found a tendency for a decrease in CI in individuals homozygous for allele rs4647905C, regardless of the population to which they belong, though the effect is more pronounced in mestizo. When the GLM analyses were performed using the absolute/linear cephalometric measurements, a statistically significant association was found between four SNPs and head length in the mestizo population.Conclusions:FGFR1 polymorphisms, especially rs4647905, can have an important role in the normal human skull variation, primarily due to their influence in head length, which would affect other cephalometric absolute/linear measures as well as indices like CI as a result of the pervasive nature of the morphological integration that characterizes the human skull. Am. J. Hum. Biol. 2013. © 2012 Wiley Periodicals, Inc.
SERS Detection of Small Inorganic Molecules and Ions
Authors: Alvarez‐Puebla Ramón A. , Liz‐Marzán Luis M. 
Published: October 2012

AbstractSurface‐enhanced Raman scattering (SERS) is one of the most straightforward applications of the so‐called nanoplasmonics. This powerful molecular spectroscopy technique is based on the enhancement of the inelastic scattering from molecules located near nanostructured metallic surfaces when these are illuminated and surface plasmons are excited. The analytical applications of SERS are hindered when the Raman cross‐section of the analyte is too low, which is often the case in inorganic molecular species. This problem is even more serious when atomic species are to be identified, since these cannot display a vibrational signal. Herein we discuss the recent advancements toward the SERS detection of small inorganic compounds, including both molecular and atomic species.
Antifouling microfiltration membranes prepared from poly(vinylidene fluoride)‐graft‐Poly(N‐ vinyl pyrrolidone) powders synthesized via pre‐irradiation induced graft polymerization
Authors: Chen Lifang , Hou Zhengchi , Lu Xiaofeng , Chen Peng , Liu Zhongying , Shen Liguo , Bian Xiaokai , Qin Qiang 
Published: October 2012

AbstractPoly(vinylidene fluoride) (PVDF) powders were grafted with N‐vinyl pyrrolidone using the pre‐irradiation induced graft polymerization technique. The effects of reaction time, absorbed dose, and monomer concentration on the degree of grafting were investigated, and the grafted PVDF powders were characterized by Fourier transform infrared spectroscopy, thermogravimetric analysis, and differential scanning calorimetry. The grafted PVDF powders were also cast into microfiltration (MF) membranes via the phase‐inversion method. The contact angle and water uptake were measured. The membrane morphology was studied by scanning electron microscopy, and the water filtration properties of the membranes were tested. The antifouling properties were determined through measurements of the recovery percentage of pure water flux after the MF membranes were fouled with bovine serum albumin solution. The results confirmed that the existence of poly(N‐vinyl pyrrolidone) (PVP) graft chains improved the hydrophilicity and antifouling properties of the MF membranes cast from PVDF‐g‐PVP powders. © 2012 Wiley Periodicals, Inc. J. Appl. Polym. Sci., 2013
13C‐NMR, 13C‐13C gCOSY, and ESI‐MS characterization of ether‐bridged condensation products in N,N′‐dimethylurea‐formaldehyde systems
Authors: Kibrik Éléonore J. , Steinhof Oliver , Scherr Günter , Thiel Werner R. , Hasse Hans 
Published: October 2012

AbstractThe reaction of urea with formaldehyde is the basis for the production of urea‐formaldehyde (UF) resins which are widely applied in the wood industry. The presence of ether‐bridged condensation products in the UF resin reaction system is an open question in the literature. It is addressed in the present work. The N,N′‐dimethylurea‐formaldehyde model system was studied since it is chemically similar to the UF resin reaction system but allows for a simple elucidation of all reaction products. It was analyzed by 13C‐NMR spectroscopy and ESI‐MS. In corresponding NMR and MS spectra, peaks due to methoxymethylenebis(dimethyl)urea and its hemiformal were observed. 13C‐13C gCOSY analysis was conducted using labeled 13C‐formaldehyde. The correlation spectra showed evidence for an ether‐bridged compound and mass spectra exhibited peaks agreeing with labeled methoxymethylenebis(dimethyl)urea and its hemiformal. Methoxymethylenebis(dimethyl)urea was characterized in N,N′‐dimethylurea‐formaldehyde systems in acidic and slightly basic media. As urea is very similar to N,N′‐dimethylurea, the results of this work strengthen the assumption that ether‐bridged condensation products are likely to form in UF resins. © 2012 Wiley Periodicals, Inc. J. Appl. Polym. Sci., 2013
Proximal Femoral Musculoskeletal Morphology of Chimpanzees and its Evolutionary Significance: A Critique of Morimoto et al. (2011)
Authors: Suwa Gen , Lovejoy C. Owen , Asfaw Berhane , White Tim 
Published: October 2012

AbstractBased on the analysis of computed tomography (CT) scan imagery, Morimoto et al. (Anatomical Record 2011; 294:1433–1445) concluded that the proximal femoral shaft attachment of the chimpanzee gluteus maximus (GM) lies in a position similar to that of modern humans (medial to a longitudinal bony structure that runs superoinferiorly along the lateral proximal shaft), contradicting the previous reports of similarity with the other extant apes. Based on a broader comparative osteological perspective and examination of some of the same CT imageries, we here demonstrate that: 1) although the chimpanzee insertion of the GM appears to lie more posteromedially than it does in gorillas and orangutans, the validity of the extent of this reassessment remains in doubt, pending crossvalidation of CT analyses by parallel dissections of the imaged specimens, and 2) the chimpanzee and human conditions are, nevertheless, distinct. We agree with Morimoto et al. (Anatomical Record 2011; 294:1433–1445) that these observations support the interpretation that superficially similar osteological topographies of the proximal femur were acquired independently by chimpanzees and gorillas, but we disagree about the significance of their suggested human–chimpanzee similarities. Although Morimoto et al. (Anatomical Record 2011; 294:1433–1445) considered these to be shared‐derived features of the chimpanzee–human clade, we instead argue that the shared absence of strong anterolateral displacement of the GM attachment among chimpanzees, basal hominids (such as Orrorin and Ardipithecus), and humans likely reflects the primitive condition characteristic of a wide range of Miocene apes. Anat Rec, 2012. © 2012 Wiley Periodicals, Inc.
Ammonia plasma treatment of polystyrene surfaces enhances proliferation of primary human mesenchymal stem cells and human endothelial cells
Authors: Kleinhans Claudia , Barz Jakob , Wurster Simone , Willig Marleen , Oehr Christian , Müller Michael , Walles Heike , Hirth Thomas , Kluger Petra J. 
Published: October 2012

AbstractThe control of surface properties is a substantial step in the development and improvement of biomaterials for clinical applications as well as for their use in tissue engineering. Interaction of the substrate surface with the biochemical or biological environment is crucial for the outcome of the applied biomaterial and therefore should meet specific requirements regarding the chemical composition, wettability, elasticity, and charge. In this study, we examined the effect of chemical groups introduced by low pressure plasma treatments of polystyrene surfaces on the cell behavior of primary human mesenchymal stem cells (hMSCs) and dermal microvascular endothelial cells (hDMECs). X‐ray photoelectron spectroscopy analysis and contact angle measurements were employed to evaluate ammonia‐, carbon dioxide‐, and acrylic acid‐plasma modifications to substrate surfaces. HMSCs and hDMECs were analyzed simultaneously to identify the most suitable surface functionalization for each cell type. Significantly higher cell proliferation was detected on ammonia plasma‐treated surfaces. Cell‐material interaction could be shown on all created interfaces as well as the expression of typical cell markers. Hence, the applied plasma treatment presents a suitable tool to improve culture condition on polystyrene for two important cell types (hMSCs and hDMECs) in the field of tissue engineering.
Gold nanograin microelectrodes for neuroelectronic interfaces
Authors: Kim Raeyoung , Hong Nari , Nam Yoonkey 
Published: October 2012

AbstractNeuroelectronic interfaces are imperative in investigating neural tissues as electrical signals are the main information carriers in the nervous system and metal microelectrodes have been widely used for recording and stimulation of nerve cells. For high performance microelectrodes, low tissue‐electrode interfacial impedance and high charge injection limits are essential and nanoscale surface engineering has been utilized to meet the requirements for microelectrodes. We report a single‐cell sized microelectrode, which has unique gold nanograin structures, using a simple electrochemical deposition method. The fabricated microelectrode had a sunflower shape with 1–5 (m of micropetals along the circumference of the microelectrode and 500 nm nanograins at the center. The nanograin electrodes had 69‐fold decrease of impedance and 10‐fold increase in electrical stimulation capability compared to unmodified flat gold microelectrodes. The recording and stimulation performance of nanograin electrodes was tested using dissociated rat hippocampal neuronal cultures. Noise levels were extremely low (2.89 μVrms) resulting in high signal‐to‐noise ratio for low‐amplitude action potentials (18.6–315 μV). Small biphasic current pulses (20–60 μA) could evoke action potentials from neurons nearby electrodes. This new nanostructured neural electrode may be applicable for the development of cell‐based biosensors or clinical neural prosthetic devices.
The effect of ultrasonication on the immunomodulatory activity of low‐quality ginseng
Authors: Seo Yong Chang , Song Chi Ho , Lim Hye Won , Lee Hyeon Yong 
Published: October 2012

AbstractThis study investigated the effects of ultrasonication extraction (UE) on the immunomodulatory activity of low‐quality ginseng. The results indicate that the optimal conditions for extracting low‐quality ginseng are ultrasonication at 60 kHz and 85°C for 60 min. The extraction yield from the UE was 20% higher than that of the water extraction (WE) at 100°C. The low quality ginseng obtained from the UE exhibited relatively low cytotoxicity toward normal human cells, with an observed toxicity of 15–18% at a concentration of 1.0 mg/mL. The ginseng product obtained following UE induced human B and T cells growth and resulted in concentrations of up to 9.33 × 104 cells/mL and 15.33 × 104 cells/mL, respectively. The ginseng extract also increased the secretion of interleukin‐6 and tumor necrosis factor‐α from these cells by up to 35%, and natural killer/ cell growth was also improved by up to 30%. The UE effectively released 2‐ to 3‐fold higher levels of ginsenosides than the WE. Specifically, the obtained levels of Rb1, Re, and Rg1, which are likely immunomodulatory factors, were approximately three times higher after ultrasonication than after WE. These results were further supported by the finding that UE product‐treated macrophages produced higher levels of nitric oxide (21 μM) than macrophages treated with the WE product or with standard ginsenosides. These results demonstrate that this optimized ultrasonication process effectively destroyed the more rigid cell walls of low‐quality ginseng and released high levels of ginsenosides. This work is the first to correlate extraction parameters with both extraction yields and biological activity. The use of low‐quality ginseng can thus be expanded by utilizing a low‐temperature ultrasonic extraction process. © 2012 American Institute of Chemical Engineers Biotechnol. Prog., 2013
Shrimp (Litopenaeus vannamei) trypsinogen production in Pichia pastoris bioreactor cultures
Authors: Viader‐Salvadó José M. , Fuentes‐Garibay José A. , Castillo‐Galván Mauricio , Iracheta‐Cárdenas María M. , Galán‐Wong Luis J. , Guerrero‐Olazarán Martha 
Published: October 2012

AbstractRecently, we engineered a Pichia pastoris Mut+ strain to produce and secrete recombinant Litopenaeus vannamei trypsinogen. Despite the observed toxicity of the recombinant shrimp trypsinogen to the P. pastoris cell host, when high density cell cultures in shake flasks with alanine in the induction medium were used recombinant shrimp trypsinogen could be produced. To further improve the product yield, in this work, we evaluated L. vannamei trypsinogen production in P. pastoris using a bioreactor and two recombinant P. pastoris strains with different methanol utilization (Mut) phenotypes. The effect of pH and temperature during the induction step on the trypsinogen production was also evaluated. The results indicate that temperature, pH, and Mut phenotypes influence the production of the recombinant protein, with almost no observed effect on cell growth. All cultures with the Mut+ strain had significant operational difficulties, such as in lowering the induction temperature, maintaining dissolved oxygen (DO) above 20%, and maintaining the methanol concentration at a constant value, and showed a decrease in metabolic activity due to trypsinogen toxicity to the cell host. In the culture with the Muts strain, however, the temperature, methanol concentration, and DO could be more easily controlled, the temperature could be easily decreased, and the trypsinogen caused the lowest toxicity to the host cells. After 96 h of Muts strain induction (pH 6 and 25°C), about 250 mg/L recombinant trypsinogen was detected in the culture medium. © 2012 American Institute of Chemical Engineers Biotechnol. Prog., 2013
Phosphatidylcholine enrichment with medium chain fatty acids by immobilized phospholipase A1‐catalyzed acidolysis
Authors: Ochoa Angélica A. , Hernández‐Becerra Josafat A. , Cavazos‐Garduño Adriana , García Hugo S. , Vernon‐Carter Eduardo J. 
Published: October 2012

AbstractPhospholipids are a biologically and industrially important class of compounds whose physical properties can be improved for diverse applications by substitution of medium‐chain fatty acids for their native fatty acid chains. In this study, phosphatidylcholine (PC) was enriched with medium‐chain fatty acids (MCFAs) by acidolysis with phospholipase A1 (PLA1) immobilized on Duolite A568. Response surface methodology was employed to evaluate the effects of the molar ratio of substrates (PC to free MCFAs), enzyme loading, and reaction temperature on the incorporation of free MCFAs into PC and on PC recovery. Enzyme loading and molar ratio of substrates contributed positively, but temperature negatively, to the incorporation of free MCFAs into PC. Increases in enzyme loading and the molar ratio of PC to free MCFAs led to increased incorporation of the latter into the former, but increased temperature had the opposite effect. By contrast, an increase in enzyme loading led to decreased PC recovery. Increased temperature had also a negative effect on PC recovery. Optimal conditions for maximum incorporation and PC recovery were molar ratio of PC to free MCFAs of 1:16, enzyme loading of 16%, and 50°C. Under these conditions, the incorporation of free MCFAs was 41% and the PC recovery was 53%. © 2012 American Institute of Chemical Engineers Biotechnol. Prog., 2013