bluuebunny/crossref_metadata_2025 huggingface dataset:
Raman analysis of synthetic eritadenine
Authors: Enman Josefine , Ramser Kerstin , Rova Ulrika , Berglund Kris Arvid
Published: June 2008

Eritadenine, 2(R),3(R)‐dihydroxy‐4‐(9‐adenyl)‐butyric acid, is a cholesterol‐reducing compound naturally occurring in the shitake mushroom (Lentinus edodes). To identify the unknown Raman spectrum of this compound, pure synthetic eritadenine was examined and the vibrational modes were assigned by following the synthesis pathway. This was accomplished by comparing the known spectra of the starting compounds adenine and D‐ribose with the spectra of a synthesis intermediate, methyl 5‐(6‐Aminopurin‐9H‐9‐yl)‐2,3‐O‐isopropylidene‐5‐deoxy‐β‐D‐ribofuranoside (MAIR) and eritadenine. In the Raman spectrum of eritadenine, a distinctive vibrational mode at 773 cm−1 was detected and ascribed to vibrations in the carbon chain, ν(CC). A Raman line that arose at 1212 cm−1, both in the Raman spectrum of MAIR and eritadenine, was also assigned to ν(CC). Additional Raman lines detected at 1526 and at 1583 cm−1 in the Raman spectrum of MAIR and eritadenine were assigned to ν(NC) and a deformation of the purine ring structure. In these cases the vibrational modes are due to the linkage between adenine and the ribofuranoside moiety for MAIR, and between adenine and the carbon chain for eritadenine. This link is also the cause for the disappearance of adenine specific Raman lines in the spectrum of both MAIR and eritadenine. Several vibrations observed in the spectrum of D‐ribose were not observed in the Raman spectrum of eritadenine due to the absence of the ribose ring structure. In the Raman spectrum of MAIR some of the D‐ribose specific Raman lines disappeared due to the introduction of methyl and isopropylidene moieties to the ribose unit. With the approach presented in this study the so far unknown Raman spectrum of eritadenine could be successfully identified and is presented here for the first time. Copyright © 2008 John Wiley & Sons, Ltd.
Sensory properties of soy yoghurts prepared from yellow and black soymilk using Streptococcus infantarius 12 and Weisellia sp. 4
Authors: Chun Jiyeon , Kwon Dae‐Young , Kim Jong Sang , Kim Jeong‐Hwan
Published: June 2008

BACKGROUND: Soy yoghurts containing enhanced bioactive isoflavone aglycones were prepared from combinations of yellow (YS) and black soymilk (BS) (YS:BS = 100:0, 70:30, 50:50 and 0:100, v/v) by fermentation with Streptococcus infantarius 12 and Weisellia sp. 4 at 37 °C for 10 h. Sensory properties of the bioactive soy yoghurts were investigated. Furthermore, other characteristics including the contents of isoflavones, viable cell numbers, pH, colour and DPPH radical scavenging activity were investigated.

RESULTS: One hundred percent YS yoghurt showed the highest scores of all sensory attributes while 100% BS yoghurt was the lowest for colour and smoothness. The overall acceptability scores were 5.9 and 5.2 for 100% YS and 100% BS yoghurts, respectively (9‐point scale). The L‐values of soy yoghurts decreased as the percentage BS increased, indicating darkening of soy yoghurts. The contents of bioactive isoflavone aglycones (daidzein and genistein) in soy yoghurts remarkably increased (>1300 mg kg−1) by fermentation. Viable cell numbers and pH of soy yoghurts ranged from 8.4 × 108 to 9.6 × 108 CFU g−1 and 4.43 to 4.54, respectively. DPPH radical scavenging activity significantly increased as the percentage BS increased (P < 0.05).

CONCLUSION: One hundred percent YS yoghurt was better for overall sensory properties while 100% BS yogurt was more bioactive in terms of the isoflavone aglycone contents and DPPH radical scavenging activity compared to other yoghurts. Copyright © 2008 Society of Chemical Industry
Effect of Pichia membranaefaciens combined with salicylic acid on controlling brown rot in peach fruit and the mechanisms involved
Authors: Xu Xiangbin , Chan Zhulong , Xu Yong , Tian Shiping
Published: June 2008

BACKGROUND: Fruits are usually stored at low temperature to slow physiological metabolism, maintain quality and extend storage life. However, brown rot caused by Monilinia fructicola often occurs in peach fruit at low temperature, resulting in serious losses. As a promising alternative to the use of synthetic fungicides, the antagonistic yeast Pichia membranaefaciens showed a potential effect on controlling post‐harvest brown rot. To improve biocontrol efficacy of the yeast against fungal pathogen, the biocontrol efficacy of P. membranaefaciens combined with salicylic acid (SA) in inhibiting brown rot in peach fruit caused by M. fructicola was investigated.

RESULTS: As compared to P. membranaefaciens used alone, the yeast combined with SA significantly reduced lesion diameter caused by M. fructicola, and increased the activities of chitinase, β‐1,3‐glucanase and peroxidase (POD), as well as enhanced the expressions of chitinase and β‐1,3‐glucanase genes in peach fruit. Moreover, SA at 2 mmol concentration did not affect yeast growth, but inhibited pathogen growth.

CONCLUSION: The mechanism by which SA enhances the biocontrol efficacy of the antagonistic yeast against brown rot may be related to inducing biochemical defence responses in peach fruit, and a moderate inhibitory effect of SA on growth of M. fructicola. Copyright © 2008 Society of Chemical Industry
Left hemihepatectomy and caudate lobectomy and complete extrahepatic bile duct resection using transduodenal approach for hilar cholangiocarcinoma arsing from Biliary Papillomatosis
Authors: Kim Jae Keun , Hwang Ho Kyoung , Park Joon Seong , Cho Sin Il , Yoon Dong Sup , Chi Hoon Sang
Published: June 2008

Background

Biliary papillomatosis (BP) is a rare disease characterized by multiple papillary lesions of variable distribution and extent in the intra and extrahepatic bile duct. Hepatopancreatoduodenectomy (HPD) can be indicated for the resection of diffuse intra and extrahepatic BP that extended to the distal bile duct and ampullary region. The mortality rate for HPD has recently decreased but HPD still has a high morbidity rate. In this study, we present a safe procedure for concomitant intrahepatic and extrahepatic BP.

Patients and Methods

Preoperative studies showed showed multiple, variable‐sized, and nodular papillary masses with mucin in the left intrahepatic ducts, confluence of the right and left hepatic ducts, common hepatic duct, and whole CBD, but peripheral to the right intrahepatic bile ducts were grossly well preserved. We underwent Lt. hepatectomy and the common bile duct and ampulla of Vater were completely resected with transduodenal approach and the pancreatic duct was repositioned to the duodenal mucosa.

Conclusions

Major hepatic resection and transduodenal approach for complete bile duct resection and pancreatic duct repositioning could be an acceptable therapeutic option for concomitant intrahepatic and extrahepatic biliary papillomatosis without the evidence of pancreatic duct involvement in the patients with severe comorbidity. J. Surg. Oncol. 2008;98:139–142. © 2008 Wiley‐Liss, Inc.
Clinicopathological and prognostic significance of mucin phenotype in gastric cancer
Authors: Wakatsuki Kohei , Yamada Yukishige , Narikiyo Michihiro , Ueno Masato , Takayama Tomoyoshi , Tamaki Hidetoshi , Miki Katsuhiko , Matsumoto Sohei , Enomoto Koji , Yokotani Tomoyo , Nakajima Yoshiyuki
Published: June 2008

Background and Objectives

Gastric and intestinal mucin phenotype cell markers are widely expressed in gastric carcinoma cells, irrespective of their tumor histological type. In the present study, we tried to reveal the clinicopathological significance of mucin phenotype in human gastric carcinomas. Moreover, we investigated the clinical significance of RUNX3 in association with mucin phenotype.

Methods

The mucin expression of MUC5AC, MUC6, MUC2, and CD10 was evaluated in 97 gastric carcinomas by immunohistochemistry. Tumors were classified into gastric (G), gastric and intestinal mixed (GI), intestinal (I), and null (N) phenotype according to combination of mucin expression.

Results

The rate of G, GI, I, and N phenotype was 40.0%, 38.1%, 10.3%, and 19.6%, respectively. Mucin phenotype was also significantly correlated with several clinicopathological findings. Patients with I phenotype had a significantly poorer prognosis than those with any other phenotypes. They also had a higher rate of postoperative liver metastasis. Multivariate analysis revealed that mucin phenotype was a significant independent prognostic factor. We suggested that Loss of RUNX3 expression might correlate with intestinal phenotype and postoperative outcome.

Conclusions

Mucin phenotype has a significant prognostic value and may be a useful marker for the treatment of human gastric carcinoma. J. Surg. Oncol. 2008;98:124–129. © 2008 Wiley‐Liss, Inc.
Schwingfestigkeit von Kehlnähten mit und ohne Fugenöffnung
Authors: Özden H.
Published: June 2008

Auf die Frage; hat das Dickblechschweißen mit und ohne Fugenvorbereitung einen dominierenden Einfluss auf die Schwingfestigkeit? In der Literatur gibt es über den Einfluss der Nahtformen auf die Betriebsfestigkeit nicht genügende Arbeiten zu finden, deren Angaben aber in manchen Fällen einander widersprechen. Die Minimierung des Nahtquerschnittes sowie der Verzicht der Nahtvorbereitung und der Nahtnachbearbeitung wirken entscheidend auf die Fertigungskosten der Schweißverbindung. Zugleich kann enorme Zeit, Material und Energie eingespart werden.

In dieser Arbeit wird das Schwingfestigkeitsverhalten von Kehlnahtverbindungen mit und ohne Fugenvorbereitung unter Biege‐ und Torsionsbeanspruchungen untersucht. Die Untersuchungsergebnisse werden dargestellt und kommentiert. Als das wichtigste Untersuchungsergebnis ist festzustellen, dass die Nahtform beim HV‐ und HY‐ Kehlnähten unter Biege‐ und Torsionsbeanspruchungen keinen dominierenden Einfluss auf die Schwingfestigkeit hat. Die Wöhlerlinien verlaufen für beide Nahtformen fast identisch.
Investigation of wear resistance and microstructure of a newly developed chromium and vanadium containing iron‐based hardfacing alloy
Authors: Reisgen U. , Dilthey U. , Balashov B. , Kondapalli S. , Geffers C.
Published: June 2008

Plasma transferred arc (PTA) welded Ni and Co‐based alloys have gained high acceptance in many industrial applications for the wear protection of components. Recently, the cost of nickel and cobalt is rising drastically. This paper presents the development of a cost‐effective high chromium and vanadium containing iron‐based hardfacing alloy with high hardness and wear resistance. The welding processing of the alloy is carried out by PTA welding of atomized powders. Investigations on powder production as well as on weldability are presented. The coatings are metallographically studied by optical microscopy, SEM, EDX and micro‐hardness measurements. The wear resistance properties of the coatings are examined using pin on disk, dry sand rubber wheel and Miller testing, the corrosion properties are determined by immersion corrosion tests. The newly developed iron‐based alloy has nearly the same wear resistance as Ni‐based alloys with fused tungsten carbides at a higher level of corrosion resistance and much lower cost.
The effect of weld parameters on friction stir welding of brass plates
Authors: Çam G. , Serindağ H. T. , Çakan A. , Mistikoglu S. , Yavuz H.
Published: June 2008

More successful results have been obtained in butt‐ and overlap‐joining of Al‐alloy plates by a recently developed solid state joining technique, namely friction stir welding (FSW), than in more conventional fusion welding processes. In this joining technique, no fusion takes place in the joint area of the plates welded. This novel joining method also offers the potential to weld some other materials rather than Al‐alloys, such as Mg‐alloys, brasses and low strength steels.

In this study, the applicability of friction stir welding to brasses, namely 90 %Cu‐10 %Zn and 70 %Cu‐30 %Zn alloys, has been investigated. The joint performance was determined by conducting optical microscopy, microhardness mesurements and mechanical testing (e.g. tensile and bend tests). The effect of welding speed on the joint quality at a given rotational speed of the stirring pin (i.e. 1600 rpm) was also determined for both alloys. The highest joint performances were obtained at a welding speed of 210 mm/min for both alloys.
A comparison of cardiac 31P MRS at 1.5 and 3 T
Authors: Tyler Damian J. , Hudsmith Lucy E. , Clarke Kieran , Neubauer Stefan , Robson Matthew D.
Published: June 2008

31P MRS was evaluated on normal volunteers at 1.5 and 3 T, and the signal‐to‐noise ratio (SNR) of the two field strengths was calculated. The in vivo spin‐lattice, T1, relaxation times for PCr and γ‐ATP, which are essential for correcting for the effects of radiofrequency saturation on the PCr/ATP ratio, were determined at 3 T. The T1 values for six volunteers were 3.8 ± 0.7 s for PCr (mean ± SD) and 2.4 ± 1.1 s for γ‐ATP, which are similar to reported values at 1.5 T, allowing us to use protocols developed at 1.5 T at the new clinical field strength of 3 T. Direct comparison between 1.5 T and 3 T in the same 10 subjects, using coils of identical geometry and identical pulse sequences gave a mean SNR for PCr at 3 T which was 206 ± 94% of that at 1.5 T. The linewidth for PCr increased from 13 ± 6 Hz at 1.5 T to 22 ± 12 Hz at 3 T. The coefficient of variation in the measurement of PCr/ATP, based on the Cramer–Rao lower bounds, was reduced from 32 ± 25% at 1.5 T to 18 ± 13% at 3 T. Thus, 31P MRS at 3 T is greatly improved by the increase in SNR compared with acquisitions at 1.5 T because of the higher field strength. Copyright © 2008 John Wiley & Sons, Ltd.
A nonprofit manager's guide to online volunteering
Authors: Dhebar Beatrice Bezmalinovic , Stokes Benjamin
Published: June 2008

As access to the Internet expands, volunteer managers have the option of using this new technology to manage pools of volunteers online. Online volunteering can appear deceptively simple: post an opening, select a volunteer, and then manage them by e‐mail. However, our evaluation of an active online volunteering service used by more than three hundred organizations and ten thousand potential volunteers indicates that additional planning and management are frequently needed. Through an analysis of two years of quantitative data and interviews with more than forty volunteers and managers, we have extracted suggested practices and programmatic implications for managers in the areas of program design, volunteer selection, training, ongoing operations, and evaluation.
Clear‐cell adenofibroma can be a clonal precursor for clear‐cell adenocarcinoma of the ovary: a possible alternative ovarian clear‐cell carcinogenic pathway
Authors: Yamamoto S , Tsuda H , Takano M , Hase K , Tamai S , Matsubara O
Published: June 2008

Several studies have reported that ovarian clear‐cell adenocarcinoma can be derived from endometriosis. Although the clear‐cell adenofibroma (CCAF), a major form of benign and borderline ovarian clear‐cell tumour, has been suggested as another precursor for clear‐cell adenocarcinoma (CCA), there is no supportive genetic evidence for this presumption. To examine the genetic linkage between CCAF and CCA of the ovary, we conducted allelotype analysis for both CCAF and adjacent CCA components in 14 cases of CCA associated with benign CCAF and/or borderline CCAF. DNA isolated from laser‐microdissected tissue was subjected to polymerase chain reaction and analysis for loss of heterozygosity (LOH), using 17 polymorphic markers located on 11 chromosomal arms: 1p, 5q, 8p, 9p, 9q, 10q, 11q, 13q, 18q, 19p and 22q. For all informative loci, the frequency of LOH in adenocarcinoma was 49% (54/110 loci), and was significantly higher than those in the components of benign CCAF (22%, 20/92 loci) and borderline CCAF (30%, 25/83 loci) (χ2 test; p < 0.05, respectively). The concordance rate in allelic patterns at all informative loci was 74% between benign CCAF and adenocarcinoma components, 81% between borderline CCAF and adenocarcinoma components, and 95% between benign CCAF and borderline CCAF components. Furthermore, between CCAF and adenocarcinoma components, an identical LOH pattern, involving the same alleles, was found in 13 (93%) of 14 cases at one or more chromosomal loci, and estimation of probability indicated that these events were very unlikely to have occurred by chance. Among the markers examined, LOHs on 5q, 10q and 22q were frequent in both CCAF and adenocarcinoma components, whereas LOHs on 1p and 13q were rare in CCAF components but frequent in adenocarcinoma components. These findings suggest that CCAF can be a clonal precursor for ovarian clear‐cell adenocarcinoma. Copyright © 2008 Pathological Society of Great Britain and Ireland. Published by John Wiley & Sons, Ltd.
Ionic liquids as an efficient bulk membrane for the selective transport of organic compounds
Authors: Branco Luís C. , Crespo João G. , Afonso Carlos A. M.
Published: June 2008

The possibility of using ionic liquids (ILs) in bulk (non‐supported) liquid membranes for the selective transport of organic molecules has been demonstrated. Recent publications have shown the potential usefulness of ILs in selective transport application and separation processes. In this work, a systematic selective transport study was performed using 1,4‐dioxane, 1‐propanol, 1‐butanol, cyclohexanol, cyclohexanone, morpholine and methylmorpholine as a 7‐component mixture of representative organic compounds, and 10 different ILs based on five cation structures such as 1‐n‐alkyl‐3‐methylimidazolium cation (n‐butyl and n‐octyl), 1‐n‐butyl‐2,3‐dimethylimidazolium cation, 1‐(2‐hydroxyethyl)‐3‐methylimidazolium ([C2OHmim]+), 1‐[2‐(2‐methoxy‐ethoxy)‐ethyl]‐3‐methylimidazolium ([C5O2mim]+) and tetra‐alkyl‐dimethylguanidinium cation (alkyl = ethylbutyl and hexyl), combined with PF and Tf2N− anions. These studies allowed us to understand the effect of cation–anion IL structures as novel liquid membranes, and also to conclude that IL polarity seems to be crucial in order to achieve high affinities and selectivities for a specific organic substrate. In general, the use of ILs based on more polar cations containing ether or hydroxyl functional groups increases their affinity for all organic compounds but also reduces the selective transport observed, especially for secondary and tertiary amines. Copyright © 2008 John Wiley & Sons, Ltd.
Special Materials in Pyrotechnics: V. Military Applications of Phosphorus and its Compounds
Authors: Koch Ernst‐Christian
Published: June 2008

This paper reviews the military applications of phosphorus in obscurants, incendiaries, float and smoke signals, friction igniters and decoys. Whereas white phosphorus (WP) is still in use as both incendiary and obscurant ammunition it has been mainly replaced today by red phosphorus (RP). For part VI see Ref. [1].
Computed Thermodynamic and Explosive Properties of 1‐Azido‐2‐nitro‐2‐azapropane (ANAP)
Authors: Klapötke Thomas M. , Steemann F. Xaver , Sućeska Muhamed
Published: June 2008

Some thermodynamic and explosive properties of the recently reported 1‐azido‐2‐nitro‐2‐azapropane (ANAP) have been determined in a combined computational ab initio (MP2/aug‐cc‐pVDZ) and EXPLO5 (Becker–Kistiakowsky–Wilson's equation of state, BKW EOS) study. The enthalpy of formation of ANAP in the liquid phase was calculated to be ΔfH°, ANAP(l)=+297.1 kJ mol−1. The heat of detonation (Qv), the detonation pressure (P), and the detonation velocity of ANAP were calculated to be Qv=−6088 kJ kg−1, P=23.8 GPa, D=8033 m s−1. A mixture of ANAP and tetranitromethane (TNM) was investigated in an attempt to tailor the impact sensitivity of ANAP, but results obtained indicate that the mixture is almost as sensitive as pure ANAP. On the other hand, ANAP and TNM were found to be chemically compatible (1H, 13C, 14N NMR; DSC) and a 1 : 1 mixture (by weight) of both components was calculated to have superior explosive properties than either of the individual components: Qv=−6848 kJ kg−1, P=27.0 GPa, D=8284 m s−1.
Study of the Effect of Additive Particle Size on Non‐ideal Explosive Performance
Authors: Trzciński Waldemar A. , Cudziło Stanisław , Paszula Józef , Callaway James
Published: June 2008

Detonation performance of non‐ideal RDX‐based compositions was studied. Charges of phlegmatised RDX containing 30% of two types of aluminium powders, coarse aluminium oxide or fine lithium fluoride particles were tested. The research concerning influence of inert and reactive additives on the detonation velocity and quasi‐static pressure was carried out. To estimate the degree of afterburning of the detonation products and reactive particles, closed explosions were performed in a chamber filled with different atmospheres. Explosion residues were also analysed. Gasdynamical and thermochemical calculations were also performed for the tested explosive compositions.
Stabilizer Degradation in Propellants: Identification of Two Isomeric Forms of 2‐Nitro‐N‐nitroso‐N‐ethylaniline
Authors: Ritter Helmut , Braun Silke , Kaiser Manfred , Becher Christopher
Published: June 2008

During the degradation of the propellant stabilizer Centralite I the 2‐nitro‐N‐nitroso‐N‐ethylaniline 2N‐NO‐EA is formed showing two signals in the chromatographic analysis (HPLC) with a 2 : 1 ratio, while the 4‐nitro isomer presents only one signal. This completely unexpected behaviour which interferes with the qualitative and quantitative determination was supposed to be due to the presence of two isomeric forms; however, the existence of two rotameric forms cannot be excluded. A detailed parameter study of the analytical conditions showed that at temperatures of 5 °C the isolation of the two forms should be possible. Preparative chromatography on a RP‐18 column at 5 °C indeed gave fractions with differing percentages of both forms; at room temperature a re‐equilibration to the starting ratio of 2 : 1 was observed.
Investigation of the Burning Properties of Slow‐Propagation Tungsten Type Delay Compositions
Authors: Lu Kai‐Tai , Yang Ching‐Chyuan , Ko Yang‐Hsiung
Published: June 2008

Twenty‐eight delay compositions with a variation of the W content of ±20% wt, on the basis of the primitive formula, W/BaCrO4/KClO4/SiO2/Viton=27 : 54 : 11 : 6 : 2, were designed for delay ignition in self‐destruction application of fuse. They were processed finally to be cylindrical pellets and were then characterized by measuring their burning properties including igniting ability, burning rate, and output flame temperature. In the experiments, the cylindrical pellets were packed into a heat‐resisting quartz tube and were ignited by an electrical‐heating wire. A high‐speed video camera and a digital‐image processing device were used for simultaneously recording the combustion phenomena such as ignition and flame propagation. In addition, the output flame temperature was detected by placing a thermocouple at the end of the quartz tube. The delay compositions were also loaded in a cylindrical aluminum tube to measure burning properties as compared to naked cylindrical pellets. According to these experimental results, this work discussed the effect of composition on burning properties. The consequences of these analyses will be very important and useful for defining criteria in formulating the tungsten type slow‐propagation delay compositions, as well as for improving self‐destruction designs of fuse.
Porous silicon antireflection layer for solar cells using metal‐assisted chemical etching
Authors: Chaoui Rachid , Mahmoudi Bedra , Si Ahmed Yasmina
Published: June 2008

Porous silicon antireflection coatings were generated on fully processed screen‐printed monocrystalline silicon solar cells using metal‐assisted chemical etching in HF:H2O2:ethanol. In this method, interaction of the HF acid with the cell front grid contact results in the dissolution of silver nanoparticles which provide the catalytic sites required to initiate porous silicon formation. Control of the etching time and HF concentration was found critical to attain good antireflection proper‐ ties while avoiding front contact degradation. The optimised porous silicon layer reduced the solar cell effective reflectance from 44% to 12% in the spectral range 400–1100 nm and increased the short‐circuit current density by 46%. The solar cell efficiency was raised by 3% absolute. The simplicity of the method makes it promising for cost‐effective reduction of reflection losses in silicon solar cells. (© 2008 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Reconstruction of the thermally quenched glow‐curve of Al2O3:C
Authors: Dallas G. I. , Afouxenidis D. , Stefanaki E. C. , Tsagas N. F. , Polymeris G. S. , Tsirliganis N. C. , Kitis G.
Published: June 2008

The experimental glow‐curve of Al2O3:C is highly disturbed due to the strong thermal quenching effect present in this material. Therefore, the real glow‐curve shape of this material is unknown. The present work describes an attempt to reconstruct the glow‐curve shape of Al2O3:C samples with different TL peak structures. The reconstruction procedure is performed in two steps. In the first step, the very narrow glow‐curves are fitted with the product of known kinetic equations and the expression giving the thermal quenching efficiency. From this procedure the quenching parameters are estimated. Next, the experimental glow curves are reconstructed (corrected for thermal quenching) dividing them by the quenching efficiency using the evaluated parameters from the first step. This step was applied to all types of glow curve structures. It was found that the quenching parameters estimated from the above procedure for Al2O3:C are in very good agreement with those reported in the literature. The results indicate that the method can be used as an alternative method for the evaluation of the quenching parameters and the reconstruction of the real (without quenching) glow‐curves of various materials. (© 2008 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Orbital angular momentum, its torque and magnetic moment calculated for the electrons circulating on the Landau levels of a crystalline solid
Authors: Olszewski S. , Rolin’︁ski T.
Published: June 2008

The angular momentum of electrons circulating in a constant magnetic field has been examined for the case of free electrons and those bound in a crystal lattice. The case of the crystal electrons provides us with a change of the angular momentum in the course of the process of the electron circulation. This temporal dependence can then be associated with the relaxation time of the circulation varying along the electron position on the orbit. The quantum expressions for the angular momentum and the magnetic moment, similar to those calculated for the energies of the Landau levels, have been derived and compared, first, with the experimental data for semiconductors, next with those obtained by Askenazy. For semiconductors the average observed data differ from those calculated from the theory by a factor equal to about two. (© 2008 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Cation ordering in NiFe2–xCrx O4‐spinels studied by Mössbauer spectroscopy in external fields
Authors: Winell S. , Amcoff Ö. , Ericsson T.
Published: June 2008

NiFe2–x Crx O4, 0 ≤ x ≤ 1.8, produced from appropriate oxides, has been studied using Mössbauer spectroscopy (MS) at low and ambient temperatures and in external fields up to 7 Tesla. X‐ray diffraction (XRD) shows all samples to be single phase cubic spinels, where a0 changes with change in x, as a concave curve, with a minimum at around x = 1. Analyses, based on Mössbauer spectra, show NiFe2–x Crx O4 to be a nearly perfect inverted spinel for x ≤ 0.6. However, for higher x ‐values the ordering is more complicated. It is shown that iron also populates the octahedral positions for x ≥ 0.8. (© 2008 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Bulk growth of SiC – review on advances of SiC vapor growth for improved doping and systematic study on dislocation evolution
Authors: Sakwe Sakwe Aloysius , Stockmeier Mathias , Hens Philip , Müller Ralf , Queren Desirée , Kunecke Ulrike , Konias Katja , Hock Rainer , Magerl Andreas , Pons Michel , Winnacker Albrecht , Wellmann Peter
Published: June 2008

This paper reviews research on advanced bulk crystal growth of SiC. A brief review highlights the benefits of the so called Modified Physical Vapor Transport Technique which uses an additional gas pipe for fine tuning of the growth cell of a conventional Physical Vapor Transport setup with additional gases. Main emphasis, however, will be laid on a systematic dislocation evolution study for various growth parameter sets. Besides doping, growth temperature was considered. Two main results were found: (i) In p‐type SiC, irrespective of the incorporation of aluminum or boron acceptors, basal plane dislocations that are harmful for bipolar power devices appear less pronounced or are even absent compared to n‐type SiC. (ii) Growth at elevated seed temperature (i.e. 2300 °C and higher) is beneficial for low dislocation densities. (© 2008 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Fabrication of high performance 3C‐SiC vertical MOSFETs by reducing planar defects
Authors: Nagasawa Hiroyuki , Abe Masayuki , Yagi Kuniaki , Kawahara Takamitsu , Hatta Naoki
Published: June 2008

The planar defect density of 3C‐SiC can be reduced by growing it on undulant‐Si substrates. However, specific stacking faults (SFs) remain, that expose the Si‐face on the (001) surface. These residual SFs increase the leakage current in devices made with 3C‐SiC. They can be eliminated using an advanced SF‐reduction method called switch‐back epitaxy (SBE) that combines polarity conversion with homoepitaxial growth. Vertical metal–oxide–semiconductor field‐effect‐transistors (MOSFETs) are fabricated on 3C‐SiC with SBE, varying in size from a single cell with an area of (30 × 30) μm2to 12,000 hexagonal cells on a (3 × 3) mm2chip. The MOSFET characteristics suggest that currents greater than 100 A are realistic for blocking voltages of 600–1,200 V by increasing the number of cells with reduced cell‐pitch. The combination of blocking voltage capability with a demonstrable high current capacity shows that 3C‐SiC is well‐suited for use in vertical MOSFETs for high‐ and medium‐power electronic applications. (© 2008 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Slow waves in magnetic metamaterials: history, fundamentals and applications
Authors: Shamonina E.
Published: June 2008

Magnetic metamaterials consist of small metallic resonators of the split ring type. Microscopic properties of these structures are governed by near field coupling between individual elements. This strongly anisotropic coupling leads to propagation of slow magnetoinductive waves with the wavelength much shorter than that of the electromagnetic radiation. This opens up novel possibilities of designing miniaturised subwavelength waveguide components and near‐field lenses in a wide range of frequencies, from radio frequencies, with a potential for medical applications in MRI, to the IR and visible range, aiming at fast signal processing. This paper provides an overview of contributions that led to the birth of the subject of magnetic metamaterials. The properties of slow waves on magnetic metamaterials including their dispersion characteristics, excitation and applications are discussed. The emphasis is laid on phenomena such as backward and forward slow waves, polaritonic hybridization of the interaction of a metamaterial with an incident electromagnetic wave yielding negative values of magnetic permeability, the possibility of positive and negative refraction of slow waves as well as mechanisms for near field subwavelength imaging. (© 2008 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Spectroscopy and imaging of GaAs/InGaAs/GaAs nanowires grown by selective‐area metalorganic vapor phase epitaxy
Authors: Fukui M. , Kobayashi Y. , Motohisa J. , Fukui T.
Published: June 2008

We have performed micro‐photoluminescence (μ‐PL) spectroscopy and imaging of single GaAs/InGaAs/GaAs nanowires (NWs) grown by selective‐area metalorganic vapor phase epitaxy (SA‐MOVPE) on masked GaAs (111)B substrates. Strong emission was observed from both end of the NW dispersed on a Si substrate. Measurements of excitation power dependence and two types of spatially‐ and spectrally‐resolved image revealed that those emissions, located around 1.40 and 1.44 eV, were from InGaAs quantum well embedded in the GaAs NW, and were suggested to be from different region. (© 2008 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Electrical study of InAs/GaAs quantum dots with two different environments
Authors: Kaniewska M. , Engström O. , Kaczmarczyk M. , Surma B. , Jung W. , Zaremba G.
Published: June 2008

Unusually complex spectra have been obtained for InAs/GaAs quantum dot (QD) structures when studied as a function of applied bias by deep level transient spectroscopy (DLTS). In spite of their complexity, basic processes for electron escape from the QDs have been recognized. We show that due to the variety of transitions involving direct tunneling and more complex thermal transitions, due to QD size fluctuations, and environmental dependent QD carrier population, measurement conditions have to be carefully suited for characterizing transport properties of the QDs. Additionally, on the basis of results of a comparative study under chosen measurement conditions, we conclude that the states of the InAs QDs shift towards the middle of the energy gap if the QDs are capped with a Ga‐rich InGaAs insertion. It explains a red‐shift of the emission wavelength that was found by photoluminescence measurements (PL). (© 2008 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Telecom single‐photon source with horn structure
Authors: Takemoto K. , Hirose S. , Takatsu M. , Yokoyama N. , Sakuma Y. , Usuki T. , Miyazawa T. , Arakawa Y.
Published: June 2008

Nearly background free 1.5‐μm single‐photon source has been demonstrated using quasiresonant pulsed excitation. We performed a micro‐photoluminescence excitation together with photon‐correlation experiments, and then we compared photon statistics in nonresonant and quasiresonant excitation case. When we tuned the pump laser to the quasiresonant state which is 18.6 meV higher than the ground state excitonic transmission, almost background‐free luminescence was found at 1524.3 nm. The second‐order correlation function at time delay of zero, g(2)(0), was reduced to 0.017 when we carefully estimated noise contributions of after‐pulses and dark counts in InGaAs APD detectors. This result opens up the possibility of promoting high quality single‐photon source at telecommunication wavelength. (© 2008 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Incorporation of N in high N‐content GaAsN films investigated by Raman scattering
Authors: Sanorpim S. , Panpech P. , Vijarnwannaluk S. , Nakajima F. , Kuboya S. , Katayama R. , Onabe K.
Published: June 2008

High N‐content GaAs1–x Nx films (0 ≤ x ≤ 0.055) grown GaAs (001) substrates by MOVPE were investigated using micro‐Raman spectroscopy. The nitrogen local vibration mode (N‐LVM) which was clearly observed at around 468 ‐ 475 cm‐1 is used as a tool to examine the N incorporation. No change in the local environment of N is observed for the high N‐containing films with N contents up to x = 0.055. The use of 514.5 nm‐line Ar+ laser as the light source gives a linear dependence of the N contents determined by Raman spectroscopy (xRaman) on the N contents determined by the high resolution X‐ray diffraction (xXRD) for xXRD ≤ 0.055, providing a realizable calibration method to determine N content in the high N‐content GaAs1‐x Nx films. On the other hand, the use of longer wavelength (632.8 nm‐line He‐Ne laser) gives a best coincidence for only the lower N contents (x < 0.02). Since, the use of longer wavelength requires the thicker film owing to a thicker optical penetration depth. Thus, in our case, a deviation from the linear behavior for higher N contents, xXRD ≥ 0.02, is not due to the N‐related reasons, but this is the results of the additional Raman scattering intensity of GaAs‐LO from the substrate. (© 2008 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Size control of nanoscaled MnAs dots fabricated on sulfur‐passivated GaAs (001)
Authors: Okabayashi J. , Ueno Y. , Yoshino J.
Published: June 2008

We have investigated the growth conditions of nanoscaled MnAs dots fabricated on sulfur‐terminated GaAs (001) surfaces with regard to the surface coverage and substrate temperature (Ts) during the growth. Scanning tunneling microscopy (STM) images reveal that the size of nanoscaled MnAs dots is controllable with respect to the values of Ts in the range of 200–300 °C. For high Ts values, the sizes of the dots become large and are limited to a diameter and height of 15 and 8 nm, respectively. Further, STM observations indicate the formation of two types of MnAs dots when more than three monolayers are grown. (© 2008 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Micro‐twin induced structural misalignment in InSb quantum wells
Authors: Mishima T. D. , Edirisooriya M. , Santos M. B.
Published: June 2008

Structural misalignments in InSb quantum wells (QWs) caused by a micro‐twin (MT) defect have been investigated by transmission electron microscopy (TEM). Dark field (DF) TEM images with the 002 reflection of the parent region show the misalignment clearly, in spite of their low image intensity. Equations that relate the width of a MT and some dimensions regarding the misalignment are derived. These equations make it possible to deduce the dimensions by [$ \bar 1 $10]‐directional 220 DF‐TEM images which have a higher image intensity than 002 DF‐TEM images. (© 2008 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Theoretical investigations on anisotropic optical properties in semipolar and nonpolar InGaN quantum wells
Authors: Kojima Kazunobu , Kamon Hiroaki , Funato Mitsuru , Kawakami Yoichi
Published: June 2008

The anisotropic band structures and spontaneous emission of the non c plane InGaN/GaN quantum wells (QWs) were computed based on the k·p perturbation theory. Spontaneous emission due to the A valence band is strongly polarized perpendicular to the c axis, while that from the B band has 90º‐rotated polarization, for the crystal angle θ larger than 50°. However, it was found that excited carriers can distribute into both the A and B bands, so that the effective polarization Peff defined by the integrated luminescence intensity is much reduced even for nonpolar InGaN/GaN QWs. Thus, Peff was systematically studied for arbitrary planes. We found that the energy separation between the A and B bands becomes significant and carrier population of the B valence band is suppressed as the In content increases, when Peff approaches unity. (© 2008 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
GaAs emission from GaInP/Er,O‐Co doped GaAs/GaInP laser diodes grown by organometallic vapor phase epitaxy
Authors: Fujii Kei , Hidaka Keiji , Yamamoto Dai , Terai Yoshikazu , Fujiwara Yasufumi
Published: June 2008

We have fabricated GaInP/Er,O‐codoped GaAs (GaAs:Er,O)/GaInP double heterostructure (DH) laser diodes (LDs) by organometallic vapor phase epitaxy (OMVPE) and investigated their lasing characteristics at GaAs band‐edge. Laser emission at the GaAs band‐edge was observed from the DH LDs at room temperature. The threshold current density (Jth) increased by doping of Er. The slope of the Jth against the reciprocal cavity length (1/L) also increased by the Er doping, indicating reduced relaxation time of injected carriers in GaAs:Er,O. (© 2008 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Band warping effect appeared in commensurability oscillations in antidot lattices of a two‐dimensional hole gas
Authors: Kang Ning , Suzuki Kazuya , Abe Eisuke , Hashimoto Yoshiaki , Iye Yasuhiro , Katsumoto Shingo
Published: June 2008

We have confirmed band warping effect of twodimensional holes confined at GaAs/AlGaAs singleheterojunction through classical commensurability resistance oscillations in anti‐dot lattices (ADLs). The oscillations in the triangular ADLs are decomposed into three peaks, two of which are assigned to localized orbits of holes with a lighter effective math (l‐hole), and the other is assigned to that of holes with heavier average effective math (h‐hole). The latter assignment is possible only when the h‐hole band is heavily warped, thus evidencing the warping. (© 2008 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Influence of the local absorber layer thickness on the performance of ZnO nanorod solar cells
Authors: Belaidi Abdelhak , Dittrich Thomas , Kieven David , Tornow Julian , Schwarzburg Klaus , Lux‐Steiner Martha
Published: June 2008

The local absorber layer thickness (dlocal) of solar cells with extremely thin absorber was changed between 10 nm and 70 nm. As a model system, ZnO nanorod arrays (electron conductor) with fixed internal surface area coated with In2S3 (absorber) and impregnated with CuSCN (transparent hole conductor) were applied. The performance of the small area solar cells depended critically on dlocal. The highest short circuit current density was reached for the lowest dlocal. In contrast, the highest open circuit voltage was obtained for the highest dlocal. A maximum energy conversion efficiency of 3.4% at AM1.5 was achieved. Limiting factors are discussed.(© 2008 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
A new warranty strategy: Combining a renewing free‐replacement warranty with a rebate policy
Authors: Chien Yu‐Hung
Published: June 2008

In this paper, a new warranty policy is proposed and analyzed for repairable products. This policy combines a renewing free‐replacement warranty with a rebate policy. Under this combined policy, the warranty period is partitioned into two intervals. If a product fails during the first interval, the seller replaces the product with a new or repaired product, and the warranty begins anew for the replacement. If a product fails in the second interval, the seller refunds a pre‐specified proportion of the sales price. We derive conditions under which the combined policy is cost‐effective from the perspective of the seller. A numerical example is presented and a sensitivity analysis is performed. Our results imply that reduced demand due to higher prices can be offset with a longer warranty period. Finally, the future extension as well as the practical application of this warranty policy is discussed through an informal survey. Copyright © 2008 John Wiley & Sons, Ltd.
Simultaneous determination of water‐soluble vitamins in selected food matrices by liquid chromatography/electrospray ionization tandem mass spectrometry
Authors: Gentili Alessandra , Caretti Fulvia , D'Ascenzo Giuseppe , Marchese Stefano , Perret Daniela , Di Corcia Daniele , Rocca Lucia Mainero
Published: June 2008

A rapid, simple and sensitive method based on liquid chromatography/tandem mass spectrometry (LC/MS/MS) with an electrospray ionization (ESI) source for the simultaneous analysis of fourteen water‐soluble vitamins (B1, B2, two B3 vitamers, B5, five B6 vitamers, B8, B9, B12 and C) in various food matrices, i.e. maize flour, green and golden kiwi and tomato pulp, is presented here. Analytes were separated by ion‐suppression reversed‐phase liquid chromatography in less than 10 min and detected in positive ion mode. Sensitivity and specificity of this method allowed two important results to be achieved: (i) limits of detection of the analytes at ng g−1 levels (except for vitamin C); (ii) development of a rapid sample treatment that minimizes analyte exposition to light, air and heat, eliminating any step of extract concentration. Analyte recovery depended on the type of matrix. In particular, recovery of the analytes in maize flour was ≥70%, with the exception of vitamin C, pyridoxal‐5′‐phosphate and vitamin B9 (ca 40%); with tomato pulp, recovery was ≥64%, except for vitamin C (41%); with kiwi, recovery was ≥73%, except for nicotinamide (ca. 30%). Copyright © 2008 John Wiley & Sons, Ltd.
Mass defect profiles of biological matrices and the general applicability of mass defect filtering for metabolite detection
Authors: Zhang Haiying , Zhu Mingshe , Ray Kenneth L. , Ma Li , Zhang Donglu
Published: June 2008

Recent examples have demonstrated that the high‐resolution liquid chromatography/mass spectrometry (LC/MS)‐based mass defect filtering (MDF) technique was effective in selectively detecting drug metabolites regardless of their molecular weights or fragmentation patterns. The main objective of the current study was to evaluate the general applicability of MDF for drug metabolite detection in typical biological matrices. Mass defect profiles of commonly used biological matrices including plasma, urine, bile, and feces were obtained using an LTQ FT mass spectrometer and were compared with those of 115 commonly prescribed drugs. The mass defect profiles were presented as two‐dimensional Y‐X plots with the determined mass defects of components on the y‐axis versus the corresponding m/z values on the x‐axis. The mass defect profiles of the matrices appeared to be similar for each type of matrix across species, yet marked differences were apparent between matrices of a given species. The mass defect profiles of components in plasma, bile, and feces showed significant separation from most of the 115 drugs. The mass defect profiles of urine did not show such clean separation from that of the 115 drugs. The results suggest that MDF has a broad applicability for selective detection of drug metabolites in plasma, bile and feces although the selectivity for detecting urinary drug metabolites is not as good as in the other matrices. In addition, the mass defect profiles of the biological matrices allow for prediction of the effectiveness of MDF for certain applications, and for designing specific MDF windows for selective detection of drug metabolites. Copyright © 2008 John Wiley & Sons, Ltd.
Generation and collision‐induced dissociation of ammonium tetrafluoroborate cluster ions
Authors: Dain Ryan P. , Van Stipdonk Michael J.
Published: June 2008

Singly and doubly charged cluster ions of ammonium tetrafluoroborate (NH4BF4) with general formula [(NH4BF4)nNH4]+ and [(NH4BF4)m(NH4)2]2+, respectively, were generated by electrospray ionization (ESI) and their fragmentation examined using collision‐induced dissociation (CID) and ion‐trap tandem mass spectrometry. CID of [(NH4BF4)nNH4]+ caused the loss of one or more neutral NH4BF4 units. The n = 2 cluster, [(NH4BF4)2NH4]+, was unique in that it also exhibited a dissociation pathway in which HBF4 was eliminated to create [(NH4BF4)(NH3)NH4]+. Dissociation of [(NH4BF4)m(NH4)2]2+ occurred through two general pathways: (a) ‘fission’ to produce singly charged cluster ions and (b) elimination of one or more neutral NH4BF4 units to leave doubly charged product ions. CID profiles, and measurements of changing precursor and product ion signal intensity as a function of applied collision voltage, were collected for [(NH4BF4)nNH4]+ and compared with those for analogous [(NaBF4)nNa]+ and [(KBF4)nK]+ ions to determine the influence of the cation on the relative stability of cluster ions. In general, the [(NH4BF4)nNH4]+ clusters were found to be easier to dissociate than both the sodium and potassium clusters of comparable size, with [(KBF4)nK]+ ions the most difficult to dissociate. Copyright © 2008 John Wiley & Sons, Ltd.
An improved method for de novo sequencing of arginine‐containing, Nα‐tris(2,4,6‐trimethoxyphenyl)phosphonium‐acetylated peptides
Authors: Kuyama Hiroki , Sonomura Kazuhiro , Shima Keisuke , Nishimura Osamu , Tsunasawa Susumu
Published: June 2008

An improved method for de novo sequencing of arginine‐containing peptides modified with succinimidyloxycarbonylmethyl tris(2,4,6‐trimethoxyphenyl)phosphonium bromide (TMPP‐Ac‐OSu) is reported. A tagging reagent, TMPP‐Ac‐OSu, was introduced to improve the sequence analysis of peptides owing to the simplified fragmentation pattern. However, peptides containing arginine residues did not fragment efficiently even after TMPP‐Ac modification at their N‐termini. This report describes how fragmentation efficiency of TMPP‐Ac‐modified arginine‐containing peptides was significantly improved by modifying the guanidino group on the side chain of arginine with acetylacetone. Copyright © 2008 John Wiley & Sons, Ltd.