bluuebunny/crossref_metadata_2025 huggingface dataset:
Determination of the Spectral Properties and Harmonic Levels for Driving an Induction Motor by an Inverter Driver under the Different Load Conditions
Authors: Taskin S. , Gokozan H.
Published: December 2011

This paper analyses the electrical power quality for the induction motor of 75 kWusing the spectral analysis methods. Measurements are carried out by collecting the current and voltage variations in a ceramic factory. Spectral analyzing techniques are applied to the collected data to get the spectral properties. Hence, induction motor operation regions are categorized under three zones. These are no-load condition; transient case from no-load to load and full-load, respectively. Consequently, the variations of the harmonics are compared with each other under these different operation conditions and then the most important characteristics of the harmonics are determined. In this manner, dominant harmonics are obtained as 5th, 7th, 11th, 13th and 17th harmonics as well as fundamental frequency at 50 Hz. Ill. 9, bibl. 18, tabl. 1 (in English; abstracts in English and Lithuanian).http://dx.doi.org/10.5755/j01.eee.108.2.149
Simulation using Interruptions
Authors: Bartkevicius S. , Sarkauskas K. , Vilkauskas A.
Published: December 2011

Simulation of control systems with large amount of interacting objects requires a powerful computer, because traditionally systems with polling are used. The number of conditions to check on each step of simulations becomes so large, that models become unfunction-al. The new simulation technique, using program interruptions, which are organized by the model itself is proposed. Replace of polling by interruptions lets radically increase the speed of simulation and simplify the model structure. Ill. 6, bibl. 7 (in English; abstracts in English and Lithuanian).http://dx.doi.org/10.5755/j01.eee.108.2.150
Computer-aided Analysis of Thermal Convection near Electric Devices
Authors: Czapp S. , Czapp M.
Published: December 2011

Current-carrying capacity of electric devices strictly depends on the heat transfer between electric devices and surroundings. For example, in order to increase the current-carrying capacity of devices, a forced circulation of air is applied. Comprehensive observation and analysis of natural thermal convection indicates that the process intensity depends on positioning of the electric devices and addi-tional elements as screens or canals close to the device. In the paper analysis of thermal convection with the use of Ansys/Flotran code is presented. The results of the analysis of thermal convection with the use of additional screen close to the electric device are pre-sented. Optimum distance between the electric device and the screen is evaluated. Ill. 8, bibl. 8 (in English; abstracts in English and Lithuanian).http://dx.doi.org/10.5755/j01.eee.109.3.163
Experimental Study of Moment Method for Undergraduates in Electromagnetic
Authors: O. Serteller N. F. , Ak A. G. , Kocyigit G. , Akinci T. C.
Published: December 2011

The experimental study and Moment Method with is programmed in Mathematica are presented here to facilitate introductory instruction on numerical methods for undergraduate electrical education students. The Method of Moments (MOM) is introduced at the beginning level to prepare students for subsequent advanced topics in complex matrix method and linear vector space theory. The study is carried out with parallel plate capacitor. The different capacitor (dielectric) materials are tried and coincidental program of MOM are studied. Ill. 4, bibl. 9, tabl. 1 (in English; abstracts in English and Lithuanian).http://dx.doi.org/10.5755/j01.eee.109.3.184
Integration of Biosensors and Associated Electronics on Lab-on-Chip Devices
Authors: Giannitsis A. T. , Parve T. , Min M.
Published: December 2011

Lab-on-chip devices comprise a class of bioelectronic miniaturized devices that incorporate microfluidic and biosensing apparatuses on a single chip. They are dedicated for analyzing and processing biochemical liquid samples, which may consist of enzymes, proteins, nucleotides, or even cells and viruses. Furthermore, lab-on-chips may enhance synthesis of biochemical products. The importance of lab-on-chip devices lies on their potentiality of advancing the development of environmental monitoring sensors and also point-of-care analyzers in medicine. This article presents the usual microfabrication methods for manufacturing lab-on-chip devices, with emphasis on the integration of the biosensor, the biocompatibility of the sensing element of the biosensor, and the essential electronics. Three major types of biosensors are analyzed: optical, impedimetric and electrochemical ones. Ill. 7, bibl. 28 (in English; abstracts in English and Lithuanian).http://dx.doi.org/10.5755/j01.eee.110.4.288
Ant System Initial Parameters Distribution
Authors: Laptik R.
Published: December 2011

The paper presents some preliminary results on distributing initial parameter values among ants in Ant System. Two cases are studied, one with uniform distribution of heuristic information sensitivity values among ants and other with Gaussian distribution. Experimental analysis is performed by comparing behavior of Ant System with possible parameter values from the range to distributed parameter values solving Traveling Salesman Problem. Minimum mean error found, number of optimal solutions found and convergence speed are used as main indicators of Ant System performance evaluation. Uniform distribution proved to have minimum mean error difference from optimal value not more than 2 % with similar convergence speed. Number of optimal solutions found is from 2 to 5 times worse than in case of optimal parameter value due to small number of ants with parameter set close to optimal. Distribution of initial parameter values proved to be competitive when system complexity increase is not possible and initial values are not known. Bibl. 12, tabl. 2 (in English; abstracts in English and Lithuanian).http://dx.doi.org/10.5755/j01.eee.110.4.294
Efficiency Increase at Low Temperatures through Heat Accumulation Tube Sections in Synthetic Material Damp-Proof Luminaires with T5 Fluorescent Lamps
Authors: Pracht F.
Published: December 2011

The new energy-saving fluorescent lamp generation T5/16 mm exhibits an extremely high operational efficiency at room tempera-ture. However, low ambient temperatures cause a significantly reduced luminous flux and thus a low operational efficiency. It is there-fore for economic reasons not practical to deploy this new generation of lamps at low temperatures. In the present paper and engineering solution is discussed which is capable of improving the luminous flux in consideration of the special conditions in higher protection class luminaries. Ill. 2, bibl. 8 (in English; abstracts in English and Lithuanian).http://dx.doi.org/10.5755/j01.eee.110.4.307
Model for Wireless Base Station Goodput Evaluation in Vehicular Communication Systems
Authors: Ipatovs A. , Petersons E. , Jansons J.
Published: December 2011

In this paper we present the model of wireless base station goodput evaluation. There was used access point model as queuing system with different kind of requests and cycling auto traffic model. Wireless mobile networks have different parameters, such as client stations distance to access point, number of clients in wireless network range, vehicle speed and traffic type. These parameters were analyzed and presented in this paper. Ill. 5, bibl. 17 (in English; abstracts in English and Lithuanian).http://dx.doi.org/10.5755/j01.eee.111.5.348
Dynamic Data Processing with Kaiman Filter
Authors: Kluga A. , Kluga J.
Published: December 2011

In this work research results of dynamic data processing with adaptive Kalman filter are presented. In filtering process parameters of filter are change on results of difference between measuring and expected coordinate. Modeling results of adaptive Kalman filtering are comparing with classic Kalman filter. Modeling results using adaptive Kalman filtering for coordinate estimation shows that estimation error decrease in points when parameters of movement change very rapidly. Results of adaptive Kalman filter modeling and filter use for GPS receiver information processing are described. Ill. 11, bibl. 4 (in English; abstracts in English and Lithuanian).http://dx.doi.org/10.5755/j01.eee.111.5.351
The Selection of Thermistors for the Temperature Measurement Gear
Authors: Leskauskaite J. , Dumcius A.
Published: December 2011

The parameters represented on manufacturer datasheet are usually insufficient for the optimum selection of thermistors. Some manufacturers give generalized numerical data of R(T) dependences. Using this data it is possible to select successfully the most suitable thermistor and equation for describing of T(R) dependence. It is shown that by selecting four points in the generalized characteristic it is possible to calculate the coefficients of the approximation equation. By the application of these coefficients in the calculations the temperature measurement errors can be decreased by an order. The results of calculations and experiment are given. Ill. 4, bibl. 8, tabl. 5 (in English; abstracts in English and Lithuanian).http://dx.doi.org/10.5755/j01.eee.111.5.357
Diffusion Welded Contacts and Related Art Applied to Semiconductor Materials
Authors: Korolkov O. , Sleptsuk N. , Toompuu J. , Rang T.
Published: December 2011

Today the majority of the contacts for semiconductor devices are prepared by use of standard technologies, when the semiconductor wafer is subordinated to multiple deposition processes and thermal treatments. In this paper we present the basic physical principals and practical realization of diffusion welding technology for fabrication of high quality contacts to semiconductor materials. The paper gives brief details of our previous experience of diffusion welding in semiconductor manufacturing. Here are described the technology and equipment used in the production of power semiconductor devices based on silicon. In parallels to diffusion welded contacts to silicon rectifying elements the same method was successfully developed in application to GaAs structures and SiC large area Schottky diodes. Ill. 8, bibl. 8 (in English; abstracts in English and Lithuanian).http://dx.doi.org/10.5755/j01.eee.111.5.359
Non-Destructive Evaluation of Green Ceramic Body Density by Ultrasonic Technique
Authors: Kulokas M. , Kazys R. , Mazeika L.
Published: December 2011

Laboratory measurements of spatial density distribution in green ceramic tiles were implemented using ultrasonic contact coupling measurement method. The main objective of these measurements is to measure spatial density distribution in pressed green ceramic tiles. Measurements of longitudinal ultrasonic wave propagation velocity were carried out using pulse and correlation methods and the tile density values were calculated. Evaluation of the measurement method, estimation of uncertainty of measurements and analysis of further improvements purposed to adapt it for on-line measurements in a production process were carried out. Ill. 7, bibl. 16, tabl. 1 (in English; abstracts in English and Lithuanian).http://dx.doi.org/10.5755/j01.eee.111.5.360
Multimodal Wheelchair Control for the Paralyzed People
Authors: Maskeliunas R. , Simutis R.
Published: December 2011

Most serious accidents and injuries often end with various motoric disabilities usually resulting in a limited control of the muscles of various body parts and in some worst case scenario even the whole body. The associated governmental support programs of today are targeted at providing the technological means enabling the handicapped persons to have as independent life as possible. In the presented research authors concentrate on the development of a mobility device for the paralyzed people, trying to develop an effective multimodal HCI algorithm by combining the traditional input with speech and video recognition technologies into one associative "package". Paper reviews some of the associated research on the topic, a proposed algorithm for the multimodal wheelchair control and a scheme of implementation. Ill. 2, bibl. 17 (in English; abstracts in English and Lithuanian).http://dx.doi.org/10.5755/j01.eee.111.5.362
Markovian Model of the Voltage Gating of Connexin-based Gap Junction Channels
Authors: Sakalauskaite A. , Pranevicius H. , Pranevicius M. , Bukauskas F.
Published: December 2011

Gap junction (GJ) channels, which are formed of a connexin (Cx) protein provide pathways through which ions and small molecules are exchanged between adjacent cells. GJs co-ordinate the cellular activity in tissues by synchronizing their electrical activity and allowing a direct cell-to-cell chemical signaling. Electrically gap junctions present nonlinear conductance that depends on transjunctional voltage and can be modulated by chemical reagents and ions, such as pH, Ca2+, etc. Here, we describe the model of the voltage gating of gap junctions using Markovian formalism. The results obtained using a stationary Markov model are well comparable with those obtained using a stochastic/imitational model of voltage gating. Ill. 5, bibl. 5, tabl. 3 (in English; abstracts in English and Lithuanian).http://dx.doi.org/10.5755/j01.eee.111.5.367
A Case Study on Agile Estimating and Planning using Scrum
Authors: Mahnic V.
Published: December 2011

We describe a case study that was conducted at the University of Ljubljana with the aim of studying the behavior of development teams using Scrum for the first time, i.e., a situation typical for software companies trying to introduce Scrum into their development process. 13 student teams were required to develop an almost real project strictly using Scrum. The data on project management activities were collected in order to measure the amount of work completed, compliance with the release and iteration plans, and ability of effort estimation, thus contributing to evidence-based assessment of the typical Scrum processes. It was found that the initial plans and effort estimates were over-optimistic, but the abilities of estimating and planning improved from Sprint to Sprint. Most teams were able to define almost accurate Sprint plans after three Sprints. In the third Sprint the velocity stabilized and the actual achievement almost completely matched the plan. Bibl. 25, tabl. 4 (in English; abstracts in English and Lithuanian).http://dx.doi.org/10.5755/j01.eee.111.5.372
An 800 kb deletion at 17q23.2 including the MED13 (THRAP1) gene, revealed by aCGH in a patient with a SMC 17p
Authors: Boutry‐Kryza Nadia , Labalme Audrey , Till Marianne , Schluth‐Bolard Caroline , Langue Jacques , Turleau Catherine , Edery Patrick , Sanlaville Damien
Published: December 2011

We report on clinical and cytogenetic studies in a 7‐year‐old child with moderate intellectual disability, short stature, mild dysmorphism, and hearing loss. R‐chromosome banding showed a de novo autosomal marker originating from the 17p chromosome segment in all cells analyzed. Array comparative genome hybridization (aCGH) was used to determine the gene content and proximal and distal breakpoints of the small supernumerary marker chromosome (SMC). These breakpoints mapped to the centromere of chromosome 17 and the 17p11.2 region, respectively. Unexpectedly, aCGH analysis also revealed a de novo deletion of 800 kb encompassing six genes in the 17q23.2 region, including MED13 (also known as THRAP1). We compared our patient with other reported cases of SMC(17), to determine the respective contributions of the duplication and the deletion to the phenotype. We cannot entirely exclude a minor role for the SMC(17), but we suggest that MED13 haploinsufficiency was responsible for the phenotype of the patient particularly the cataract, hearing loss and semicircular canal dysplasia. Moreover, this report highlights the usefulness of aCGH for the specification of gene content in cases of abnormality, facilitating the establishment of accurate phenotype–genotype correlations and the detection of other, complex rearrangements. © 2011 Wiley Periodicals, Inc.
Evaluation of conserved and ultra‐conserved non‐genic sequences in chromosome 15q15‐linked periodic catatonia
Authors: Schanze Denny , Ekici Arif B. , Pfuhlmann Bruno , Reis André , Stöber Gerald
Published: December 2011

Conserved and ultra‐conserved non‐genic sequence elements (CNGs, UCEs) between human and other mammalian genomes seem to constitute a heterogeneous group of functional sequences which likely have important biological function. To determine whether variation in CNGs and UCEs contributes to risk for the schizophrenic subphenotype of periodic catatonia (according to K. Leonhard; OMIM 605419), we evaluated non‐coding elements at a critical 7.35 Mb interval on chromosome 15q15 in 8 unrelated cases with periodic catatonia (derived from pedigrees compatible with linkage to chromosome 15q15) and 8 controls, followed by association studies in a cohort of 510 cases and controls. Among 65 CNGs (≥100 bp, 100% identity; human‐mouse comparison), 7 CNGs matched criteria for UCE (≥200 bp, 100% identity). A hot spot of 62/65 CNGs (95%) appeared at the MEIS2 locus, which implicates functional importance of associated (ultra‐)conserved elements to this early developmental gene, which is present in the human fetal neocortex and associated with metabolic side effects to antipsychotic drugs. Further CNGs were identified at the PLCB2 and DLL4 locus or located intergenic between TYRO3 and MAPKBP1. Automated sequencing revealed genetic variation in 12.3% of CNGs, but frequencies were low (MAF: 0.06–0.4) in cases. Three variants located inside CNGs/UCEs were found in cases only. In a case–control association study we could not confirm a significant association of these three CNG‐variants with periodic catatonia. Our results suggest genetic variation in (ultra‐)conserved non‐genic sequence elements which might alter functional properties. The identified variants are genetically not associated with the phenotype of periodic catatonia. © 2011 Wiley Periodicals, Inc.
SNP variants within the vanilloidTRPV1andTRPV3receptor genes are associated with migraine in the Spanish population
Authors: Carreño Oriel , Corominas Roser , Fernández‐Morales Jessica , Camiña Montserrat , Sobrido María‐Jesús , Fernández‐Fernández José Manuel , Pozo‐Rosich Patricia , Cormand Bru , Macaya Alfons
Published: December 2011

The transient receptor potential (TRP) superfamily of non‐selective cationic channels are involved in several processes plausibly relevant to migraine pathophysiology, including multimodal sensory and pain perception, central and peripheral sensitization, and regulation of calcium homeostasis. With the aim of identifying single nucleotide polymorphisms (SNPs) in TRP genes that may confer increased genetic susceptibility to migraine, we carried out a case–control genetic association study with replication, including a total of 1,040 cases and 1,037 controls. We genotyped 149 SNPs covering 14 TRP genes with known brain expression. The two‐stage study comprised samples of 555 and 485 Spanish, Caucasian patients, selected according to the ICHD‐II criteria for the diagnosis of migraine without aura (MO) or migraine with aura (MA). In the discovery sample, 19 SNPs in ten TRP genes showed nominal association (P < 0.05) with MO, MA, or overall migraine. In the replication sample, nominal association was confirmed for TRPV3 rs7217270 in MA and TRPV1 rs222741 in the overall migraine group. Risk haplotypes were identified for seven of the genes showing nominal association in the discovery set, but none of them was replicated. The present findings suggest that members of the vanilloid TRPV subfamily of receptors contribute to the genetic susceptibility to migraine in the Spanish population. © 2011 Wiley Periodicals, Inc.
Study of a possible role of the monoamine oxidase A (MAOA) gene in paranoid schizophrenia among a Chinese population
Authors: Sun Yuhui , Zhang Jiexu , Yuan Yanbo , Yu Xin , Shen Yan , Xu Qi
Published: December 2011

Monoamine oxidase A (MAOA) is the enzyme responsible for degradation of several monoamines, such as dopamine and serotonin that are considered as being two of the most important neurotransmitters involved in the pathophysiology of schizophrenia. To study a possible role of the MAOA gene in conferring susceptibility to schizophrenia, the present study genotyped the variable number of tandem repeat (VNTR) polymorphism and 41 SNPs across this gene among 555 unrelated patients with paranoid schizophrenia and 567 unrelated healthy controls. Quantitative real‐time PCR analysis was employed to quantify expression of MAOA mRNA in 73 drug‐free patients. While none of these genotyped DNA markers showed allelic association with paranoid schizophrenia, haplotypic association was found for the VNTR‐rs6323, VNTR‐rs1137070, and VNTR‐rs6323‐rs1137070 haplotypes in female subjects. Nevertheless, no significant change of the expression of MAOA mRNA was detected in either female or male patients with paranoid schizophrenia. Our study suggests that the interaction between genetic variants within the MAOA gene may contribute to an increased risk of paranoid schizophrenia, but the precise mechanism needs further investigation. © 2011 Wiley Periodicals, Inc.
Antibacterial properties of additives used in injection immunotherapy
Authors: Gilbert Kevin C. , Sundareshan Vidya , Bass Richard M. , Lin Sandra Y.
Published: December 2011

Background:

Previous studies have reviewed the safety of preparing and administering allergy injection immunotherapy in a physician's office, and showed no evidence of infectious complications. The current study examines the antimicrobial properties of the common additives used in preparation of multidose immunotherapy vials.

Methods:

Vials were prepared with varying concentrations of glycerin (0‐25%), phenol (0‐0.4%) and combinations of glycerin with phenol. A standard inoculum of Staphylococcus aureus was introduced in each vial and incubated. Optical densities were measured and colony counts were performed at 24 and 48 hours. Follow‐up broth microdilution assays were performed using varying inocula of bacteria and the highest concentrations of additives to determine the number of bacteria for which these solutions were bacteriostatic and/or bactericidal. Optical densities were measured and colony counts were performed as in the vial assays.

Results:

All vials with varying dilutions of glycerin, phenol, and their combination showed bacterial growth with the standard inoculum of Staphylococcus aureus. Visible turbidity and optical density were inversely related to additive concentration. Follow‐up microdilution assays with differing concentrations of bacteria demonstrated bactericidal activity with inocula of 1×103 colony forming units (CFU) of Staphylococcus aureus at clinically used concentrations of glycerin and phenol.

Conclusion:

Higher concentrations of additives show better inhibition of bacterial growth. Solutions containing glycerin showed superior bactericidal activity than those containing only phenol. At concentrations of additives used in preparing allergy immunotherapy vials, antibacterial effects were observed with inoculation of 1×103 CFU or less of Staphylococcus aureus. © 2011 ARS‐AAOA, LLC.
DNA‐Origami: die Kunst, DNA zu falten
Authors: Saccà Barbara , Niemeyer Christof M.
Published: December 2011

Die Einführung der DNA‐Origami‐Technik hat den Entwurf und die Herstellung von nanoskaligen DNA‐Objekten stark vereinfacht. Die Selbstorganisation eines DNA‐Origamis ist ein Prozess, durch den ein langes, zirkuläres DNA‐Einzelstrangmolekül (häufig aus dem Phagen M13mp18) unter Verwendung einer Vielzahl von kurzen Helfersträngen in praktisch jede gewünschte Form gefaltet werden kann. Dieser Ansatz ermöglicht die problemlose Herstellung von Objekten mit einer adressierbaren Oberfläche von der Größe einiger tausend Quadratnanometer. Dies entspricht einer “Pixel”‐Auflösung von etwa 6 nm. Gleichzeitig ist der Herstellungsprozess schnell, stellt keine hohen Anforderungen an die experimentellen Bedingungen und führt zu einer hohen Ausbeute der gewünschten Struktur. Diese Eigenschaften machen die DNA‐Origami‐Technik in der strukturellen DNA‐Nanotechnologie zur Methode der Wahl, wenn zwei‐ und dreidimensionale DNA‐Objekte hergestellt werden sollen. In diesem Kurzaufsatz werden die jüngsten Fortschritte bei der Entwicklung von DNA‐Origami‐Strukturen zusammengefasst, die zahlreiche interessante Anwendungsmöglichkeiten eröffnen.
Properties of phenol‐formaldehyde resins prepared from phenol‐liquefied lignin
Authors: Lee Wen‐Jau , Chang Kuo‐Chun , Tseng I‐Min
Published: December 2011

In this study, alkaline lignin (AL), dealkaline lignin (DAL), and lignin sulfonate (SL) were liquefied in phenol with sulfuric acid (H2SO4) or hydrochloric acid (HCl) as the catalyst. The phenol‐liquefied lignins were used as raw materials to prepare resol‐type phenol‐formaldehyde resins (PF) by reacting with formalin under alkaline conditions. The results show that phenol‐liquefied lignin‐based PF resins had shorter gel time at 135°C and had lower exothermic peak temperature during DSC heat‐scanning than that of normal PF resin. The thermo‐degradation of cured phenol‐liquefied lignin‐based PF resins was divided into four temperature regions, similar to the normal PF resin. When phenol‐liquefied lignin‐based PF resins were used for manufacturing plywood, most of them had the dry, warm water soaked, and repetitive boiling water soaked bonding strength fitting in the request of CNS 1349 standard for Type 1 plywood. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2011
The effect of maleic anhydride grafting efficiency on the flexural properties of polyethylene composites
Authors: Gunning M. A. , Istrate O. M. , Geever L. M. , Lyons J. G. , Blackie P. , Chen B. , Higginbotham C. L.
Published: December 2011

Many authors have reported on the property enhancements possible by compounding high density polyethylene (HDPE) with fillers to produce composites. It is accepted that polyethylene combined with materials such as nanoclay or wood flour will not yield favorable properties unless a compatibilizing material is used to form a link. In this work, compatibilized HDPE was produced by grafting maleic anhydride (MA) to its backbone in a twin screw extruder using a peroxide initiated reactive process. Fourier transform infrared spectroscopy (FTIR) was used to examine the effects of varying peroxide and MA levels on the grafting percentage and it was found that a high percentage could be achieved. The gel content of each HDPE‐g‐MA batch was determined and twin bore rheometry analysis was carried out to examine the effects of crosslinking and MA grafting on the melt viscosity. These HDPE‐g‐MA compatibilizers were subsequently compounded with nanoclay and wood flour to produce composites. The composite materials were tested using a three point bending apparatus to determine the flexural modulus and strength and were shown to have favorable mechanical properties when compared with composites containing no compatibilizer. X‐ray diffraction (XRD) was used to examine the effects of grafted MA content on the intercalation and exfoliation levels of nanoclay composites. The results from XRD scans showed that increased intercalation in polymer nanoclay composites was achieved by increasing the grafted MA content. This was confirmed using a scanning electron microscope, where images produced showed increased levels of dispersion and reductions in nanoclay agglomerates. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2011
Development of fibrillar morphology in immiscible PP/PS blends under shear flow
Authors: Mei Yuan , Huang Yajiang , He Yusong , Yang Qi
Published: December 2011

The formation dynamics of fibrillar morphology in dilute immiscible polypropylene (PP)/polystyrene blends under simple shear flow is investigated using optical‐shear technique. Two strategies in generating fibrillar droplets under shear flow, namely temperature quench and shear jump, are studied. It is found that the shear‐induced deformation of PP droplets is closely related to the total shear strain and changes of rheological properties of components during the temperature quench or shear‐jump process. The shape evolution of fibrillar droplets under shear flow displays large deviation to the prediction of affine deformation theory based on Newtonian fluids and that of three deformation models, which consider the viscoelastic properties of components. The possible effect of droplet coalescence, breakup, and interfacial slip on the deviation between the experimental data and the prediction values for droplet deformation are discussed. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2011
Dielectric properties and structures of melt‐compounded poly(ethylene oxide)–montmorillonite nanocomposites
Authors: Choudhary Shobhna , Sengwa R. J.
Published: December 2011

The dielectric dispersion and relaxation process in melt‐compounded hot‐pressed poly(ethylene oxide) (PEO)–montmorillonite (MMT) clay nanocomposite films of 0–20 wt % MMT concentration were investigated over the frequency range 20 Hz to 1 MHz at ambient temperature. X‐ray diffraction study of the nanocomposites evidences that the PEO has been intercalated into the MMT interlayer galleries with a helical‐type multilayer structures, which results the formation of unique parallel plane PEO–MMT layered structures. The relaxation times corresponding to PEO chain segmental motion were determined from the loss peak frequencies of different dielectric formalisms and the same is used to explore the interactions compatibility between PEO molecules and the MMT nano platelets. It is revealed that the loading of only 1 wt % MMT in PEO matrix significantly increases the PEO chain segmental motion due to intercalation, which further varies anomalously with increase of MMT concentration. The real part of dielectric function at 1 MHz, relaxation time, and dc conductivity of these melt‐compounded nanocomposites were compared with the aqueous solution‐cast PEO–MMT films. Considering the comparative changes in the values of various dielectric parameters, the effect of synthesization route on the intercalated/exfoliated‐MMT structures and the PEO chain dynamics were discussed. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2011
Preparation of epoxy functionalized PP with unique structure and its post‐ring open reaction
Authors: Wang Shuangshuang , Shao Lu , Song Zhiqiang , Zhao Jiruo , Feng Ying
Published: December 2011

This article discusses a convenient chemical approach named in situ chlorination graft copolymerization (ISCGC) to prepare epoxy functionalized isotactic polypropylene (iPP) with a unique structure. This method was carried out in the gas‐solid state, and chlorine was used as radical initiator as well as terminate agent. The effect of influence factors on the structure of the functionalized PP was investigated, and it was determined by levels of grafted GMA moieties. The results showed that PP modified with GMA could obtain higher grafting level. Crystallinity and mechanical properties of the functionalized PP were also investigated. For the purpose of researching the reactivity of epoxy groups located at the grafted side chains, trichloroacetic acid and hydroxyl‐terminated butadiene–acrylonitrile rubber (HTBN) were used as models to explore the ring open reaction of the epoxy groups of the functionalized PP. The structure and property of the modified PP that has undergone post‐ring open reaction was characterized by FTIR, dynamic property analysis. The results indicated that epoxy groups of the graft side chains have successfully undergone ring open reaction in the presence of carbonyl and hydroxyl groups. Additionally, the compatibilization of PP with HTBN is enhanced after PP was modified by GMA. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2011
Laminar Expression of Ephrin‐A2 in Primary Somatosensory Cortex of Postnatal Rats
Authors: Kenmuir Cynthia L. , Chiaia Nicolas L. , Lane Richard D. , Mooney Richard D.
Published: December 2011

Several Eph receptors, prominently EphA4 and EphA7, and their corresponding ligands are known to influence neocortical development, including topographic sorting of thalamocortical axons within primary somatosensory cortex (SI). This study investigated postnatal expression of a ligand that can bind to these receptors, ephrin‐A2. Quantitative methods revealed that expression of ephrin‐A2 mRNA in SI reached maximum levels on postnatal day (P) 4 and dropped thereafter to background by P18. Ephrin‐A2 mRNA expression assessed by in situ hybridization qualitatively revealed a similar time course and localized the expression pattern primarily in two broad laminae in SI, comprising the supragranular and infragranular layers, and with additional expression in the subplate. This expression pattern was investigated in greater detail using immunohistochemistry for ephrin‐A2 protein. Immunoreactivity generally showed the same laminar distribution as seen with in situ hybridization, except that it persisted longer, lasting to approximately P14. Expression in the cortical plate was low or absent within presumptive layer IV, and it remained so as cortical lamination progressed. Double‐labeling immunohistochemistry with confocal microscopy revealed that cortical neurons were the principal elements expressing ephrin‐A2 protein. These findings are consistent with possible involvement of ephrin‐A2, in concert with one or more Eph receptors, in influencing arbor development of thalamocortical axons at cortical layer IV boundaries. Anat Rec, 2012. © 2011 Wiley Periodicals, Inc.
Isolation and purification of recombinant proteins, antibodies and plasmid DNA with hydroxyapatite chromatography
Authors: Hilbrig Frank , Freitag Ruth
Published: December 2011

Hydroxyapatite and related stationary phases increasingly play a role in the downstream processing of high‐value biological materials, such as recombinant proteins, therapeutic antibodies and pharmaceutical‐grade plasmid DNA. Chromatographic hydroxyapatite is an inorganic, ceramic material identical in composition, if not in structure, to calcium phosphate found in human bones and teeth. The interaction of hydroxyapatite with biomacromolecules is complex and highly dynamic, which can make predicting performance difficult, but also allows the design of very selective isolation processes. This review discusses the currently commercially available chromatographic materials, different retention mechanisms supported by these materials and differential exploitation for the design of highly specific isolation procedures. The state of the art of antibody purification by hydroxy‐ and fluoroapatite is reviewed together with tested routines for method development and implementation. Finally, the isolation of plasmid DNA is discussed, since the purification of DNA therapeutics at a sufficiently large scale is an emerging need in bioprocess development and perhaps the area in bioseparation where apatite chromatography can make its most important contribution to date.
Identification of a 21 amino acid peptide conferring 3‐hydroxypropionic acid stress‐tolerance to Escherichia coli
Authors: Warnecke T.E. , Lynch M.D. , Lipscomb M.L. , Gill R.T.
Published: December 2011

We report the identification of a novel small open reading frame in Escherichia coli. The sORF (called iroK) encodes a 21 amino cid peptide, which when translated confers a 133% (ca. 20 g/L) increase in resistance to 3‐hydroxypropionic acid. We show that iroK conferred tolerance is additive to previously identified tolerance mechanisms involving relief of inhibited metabolism, yet does not involve altered 3‐HP transport. This result demonstrates the continued surprises that microbial genomes hold and emphasize the importance of comprehensive discovery methods in future strain and metabolic engineering efforts. Biotechnol. Bioeng. 2012; 109:1347–1352. © 2011 Wiley Periodicals, Inc.
384 hanging drop arrays give excellent Z‐factors and allow versatile formation of co‐culture spheroids
Authors: Hsiao Amy Y. , Tung Yi‐Chung , Qu Xianggui , Patel Lalit R. , Pienta Kenneth J. , Takayama Shuichi
Published: December 2011

We previously reported the development of a simple, user‐friendly, and versatile 384 hanging drop array plate for 3D spheroid culture and the importance of utilizing 3D cellular models in anti‐cancer drug sensitivity testing. The 384 hanging drop array plate allows for high‐throughput capabilities and offers significant improvements over existing 3D spheroid culture methods. To allow for practical 3D cell‐based high‐throughput screening and enable broader use of the plate, we characterize the robustness of the 384 hanging drop array plate in terms of assay performance and demonstrate the versatility of the plate. We find that the 384 hanging drop array plate performance is robust in fluorescence‐ and colorimetric‐based assays through Z‐factor calculations. Finally, we demonstrate different plate capabilities and applications, including: spheroid transfer and retrieval for Janus spheroid formation, sequential addition of cells for concentric layer patterning of different cell types, and culture of a wide variety of cell types. Biotechnol. Bioeng. 2012; 109:1293–1304. © 2011 Wiley Periodicals, Inc.
PCR Analysis of expR Gene Regulating Biosynthesis of Exopolysaccharides in Sinorhizobium meliloti
Authors: Sorroche Fernando G. , Giordano Walter
Published: December 2011

Exopolysaccharide (EPS) production by the rhizobacterium Sinorhizobium meliloti is essential for root nodule formation on its legume host (alfalfa), and for establishment of a nitrogen‐fixing symbiosis between the two partners. Production of EPS II (galactoglucan) by certain S. meliloti strains results in a mucoid colony phenotype. Other strains that are unable to produce EPS II display a dry phenotype, due to the presence of an insertion element in the gene expR, a key regulator involved in many important cellular processes, including production of low‐molecular‐weight EPS II. We describe a series of three programmed undergraduate biochemistry laboratory classes teaching PCR and electrophoresis procedures to detect non‐functional expR loci in S. meliloti.
Bacterial cellulose modified using recombinant proteins to improve neuronal and mesenchymal cell adhesion
Authors: Pértile Renata , Moreira Susana , Andrade Fábia , Domingues Lucília , Gama Miguel
Published: December 2011

A wide variety of biomaterials and bioactive molecules have been applied as scaffolds in neuronal tissue engineering. However, creating devices that enhance the regeneration of nervous system injuries is still a challenge, due the difficulty in providing an appropriate environment for cell growth and differentiation and active stimulation of nerve regeneration. In recent years, bacterial cellulose (BC) has emerged as a promising biomaterial for biomedical applications because of its properties such as high crystallinity, an ultrafine fiber network, high tensile strength, and biocompatibility. The small signaling peptides found in the proteins of extracellular matrix are described in the literature as promoters of adhesion and proliferation for several cell lineages on different surfaces. In this work, the peptide IKVAV was fused to a carbohydrate‐binding module (CBM3) and used to modify BC surfaces, with the goal of promoting neuronal and mesenchymal stem cell (MSC) adhesion. The recombinant proteins IKVAV‐CBM3 and (19)IKVAV‐CBM3 were successfully expressed in E. coli, purified through affinity chromatography, and stably adsorbed to the BC membranes. The effect of these recombinant proteins, as well as RGD‐CBM3, on cell adhesion was evaluated by MTS colorimetric assay. The results showed that the (19)IKVAV‐CBM3 was able to significantly improve the adhesion of both neuronal and mesenchymal cells and had no effect on the other cell lineages tested. The MSC neurotrophin expression in cells grown on BC membranes modified with the recombinant proteins was also analyzed. © 2012 American Institute of Chemical Engineers Biotechnol. Prog., 2012
The role of inducible nitric oxide synthase and haem oxygenase 1 in growth and development of dental tissue'
Authors: Speranza Lorenza , Pesce Mirko , Franceschelli Sara , Mastrangelo Filiberto , Patruno Antonia , De Lutiis Maria Anna , Tetè Stefano , Felaco Mario , Grilli Alfredo
Published: December 2011

In this study, the activity of the antioxidant enzyme network was assessed spectrophotometrically in samples of dental pulp and dental papilla taken from third‐molar gem extracts. The production of nitric oxide by the conversion of l‐(2,3,4,5)‐[3H] arginine to l‐(3H) citrulline, the activity of haem oxygenase 1 (HO‐1) through bilirubin synthesis and the expression of inducible nitric oxide synthase (iNOS), HO‐1 proteins and messenger RNA by Western blot and reverse‐transcribed polymerase chain reaction were also tested. The objective of this study was to evaluate the role of two proteins, iNOS and HO‐1, which are upregulated by a condition of oxidative stress present during dental tissue differentiation and development. This is fundamental for guaranteeing proper homeostasis favouring a physiological tissue growth. The results revealed an over‐expression of iNOS and HO‐1 in the papilla, compared with that in the pulp, mediated by the nuclear factor kappa B transcription factor activated by the reactive oxygen species that acts as scavengers for the superoxide radicals. HO‐1, a metabolically active enzyme in the papilla, but not in the pulp, seems to inhibit the iNOS enzyme by a crosstalk between the two proteins. We suggest that the probable mechanism through which this happens is the interaction of HO‐1 with haem, a cofactor dimer indispensible for iNOS, and the subsequent suppression of its metabolic activity. Copyright © 2011 John Wiley & Sons, Ltd.
Effect of bivalirudin compared with unfractionated heparin plus abciximab on infarct size and myocardial recovery after primary percutaneous coronary intervention: The horizons‐AMI CMRI substudy
Authors: Wöhrle Jochen , Merkle Nico , Kunze Markus , Cristea Ecaterina , Mehran Roxana , Rottbauer Wolfgang , Stone Gregg W.
Published: December 2011

Background: Myocardial infarct size is a strong independent predictor of mortality in patients with ST‐elevation myocardial infarction (STEMI). In the Harmonizing Outcomes with RevasculariZatiON and Stents in Acute Myocardial Infarction (HORIZONS‐AMI) trial, bivalirudin compared with unfractionated heparin plus a glycoprotein IIb/IIIa inhibitor reduced cardiac mortality in STEMI patients, which was attributed to reduced major bleeding. Whether a possible reduction in infarct size with bivalirudin may have contributed to the enhanced survival with this agent is unknown. Methods: Cardiac magnetic resonance imaging was performed within 7 days and after 6 months in 51 randomized patients from a single center in HORIZONS‐AMI trial (N = 28 bivalirudin, N = 23 heparin plus abciximab). Infarct size, microvascular obstruction (MVO), left ventricular ejection fraction (LVEF), and LV end‐diastolic and end‐systolic volume indices were evaluated. Results: Infarct size was not significantly different after treatment with bivalirudin compared with heparin plus abciximab either within 7 days (median 9.3% [interquartile range 4.9%, 26.6%] vs. 20.0% [5.9%, 28.2%], P = 0.28) or at 6 months 6.7% [3.8%, 20.0%] vs. 8.2% [1.8%, 16.5%], P = 0.73). MVO was present in 28.6% versus 34.8% of patients respectively (P = 0.63). LVEF and LV volume indices also did not significantly differ between the two groups at either time period, nor were differences in myocardial recovery evident. Conclusions: In conclusion, in the HORIZONS‐AMI Cardiac magnetic resonance imaging (CMRI) substudy, cardiac magnetic resonance imaging within 7 days and at 6 months after primary percutaneous coronary intervention (PCI) did not demonstrate significant differences in infarct size, MVO, LVEF, or LV volume indices in patients treated with bivalirudin compared with unfractionated heparin plus abciximab. © 2011 Wiley Periodicals, Inc.
Helical Content of a β3‐Octapeptide in Methanol: Molecular Dynamics Simulations Explain a Seeming Discrepancy between Conclusions Derived from CD and NMR Data
Authors: Niggli Damaris A. , Ebert Marc‐Olivier , Lin Zhixiong , Seebach Dieter , van Gunsteren Wilfred F.
Published: December 2011

Connecting experimental observables with the underlying conformational ensemble is a long‐standing problem in the structure determination of biomolecules. The simulations described in this article attempt to resolve a seeming discrepancy between the conformational features derived from measured NOE intensities, 3J‐coupling constants, and circular dichroism (CD) spectra for two β‐peptides differing in a linker between two side‐chains. Although both peptides are very similar in terms of the r−6 averaged distances between atom pairs involved in the observed NOEs, the molecular dynamics trajectories suggest why the CD spectra show a greater 314‐helical propensity for the linked, cyclic peptide than for the linear one, whereas slightly more NMR NOE peaks are observed and assigned for the latter. The nine 100 ns unrestrained simulations show better agreement with the observed experimental data than the single conformations derived from the published NMR structures by additional energy minimization with the GROMOS force field. They show why the seemingly contradictory quantities obtained by NMR and CD spectroscopy can arise from a single conformational ensemble.
Comparative study of eight cubic equations of state for predicting thermodynamic properties of alkanes
Authors: Faradonbeh Moosa Rabiei , Abedi Jalal , Harding Thomas G.
Published: December 2011

Precise descriptions of the thermodynamic properties of pure fluids require accurate definition of vapour–pressure and phase volumes as well as residual volumes, enthalpies and entropies. While carefully fitted multi‐parameter equations of state (EOS), such as Benedict–Webb–Rubin–Starling fulfil these requirements, cubic EOSs usually do not. On the other hand, cubic EOSs are widely used in the oil industry, due to their simplicity and reliability in most vapour–liquid equilibrium calculations. For thermal oil recovery processes and the natural gas industry, the choice of EOS becomes important for predicting thermodynamic properties, such as isobaric and isochoric heat capacities, sound velocity and the Joule–Thomson coefficient. In this study, eight cubic EOSs which most of them are used in commercial reservoir simulators are selected for evaluation of their capability in the prediction of second‐order derivative thermodynamic properties at different temperatures and pressures, using pure components frequently found in petroleum and natural gas mixtures. It is shown that none of the cubic EOSs could accurately predict all of the stated parameters, especially below the critical point. All EOSs failed to show the extrema in the derivative properties. However, among these equations the Yu–Lu and Schmidt–Wenzel EOSs were found to have more reliable predictions in most of the cases. © 2011 Canadian Society for Chemical Engineering