bluuebunny/crossref_metadata_2025_split huggingface dataset:
Stranski–Krastanow growth of stacked GaN quantum dots with intense photoluminescence
Authors: Hoshino K. , Kako S. , Arakawa Y. 
Published: November 2003

AbstractMultiple‐layer stacked GaN quantum dots (QDs) with intense photoluminescence (PL) have been grown by the Stranski–Krastanow growth mode in metalorganic chemical vapor deposition. Scanning transmission electron microscopy (STEM) analysis shows that the vertical aligned QDs are formed, which results from a strain field induced by buried islands. We have also investigated PL spectra at room temperature. The PL intensity increases with increasing number of the stacked layer. This indicates that the carriers can be injected into each layer of GaN quantum dots. (© 2003 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Recombination dynamics in low‐dimensional nitride semiconductors
Authors: Kawakami Y. , Kaneta A. , Omae K. , Shikanai A. , Okamoto K. , Marutsuki G. , Narukawa Y. , Mukai T. , Fujita Sg. 
Published: November 2003

AbstractOptical properties induced by two major effects, potential fluctuation and piezoelectric fields, have been assessed to interpret the emission mechanism in low‐dimensional nitride semiconductors because the former leads to the exciton/carrier localization, and the latter to the quantum confined Stark effect (QCSE). Degenerated white‐light pump‐and‐probe spectroscopy has been employed to assess which factor plays an important role in the series of InxGa1−xN multiple quantum well (MQW) structures whose well widths are 3 nm, 5 nm and 10 nm. Moreover, photoluminescence (PL) mapping with scanning near‐field optical microscopy (SNOM) has revealed the dense distribution of island‐like structures, the size of which ranges from 20 nm to 70 nm in a 3 nm‐thick InxGa1−xN single quantum well (SQW) structure emitting at blue spectral region. (© 2003 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Photoluminescence and optical absorption edge for MOVPE‐grown InN
Authors: Sugita K. , Takatsuka H. , Hashimoto A. , Yamamoto A. 
Published: November 2003

AbstractThis paper reports the photoluminescence (PL) spectra and the optical absorption edge at room temperature for MOVPE grown InN films as a function of growth temperature and background carrier concentration. A strong PL band with a peak energy in the range 0.7–0.9 eV is observed at room temperature. A sample grown at around 600 °C shows the highest PL intensity and the lowest peak energy. With decreasing the growth temperature from 600 °C, the PL intensity is markedly decreased and the peak energy is shifted toward the higher energy side. The absorption edge shows a similar change with the PL peak energy when the growth temperature is decreased. The difference between absorption edge and the PL peak energy is 50–100 meVand it increases with increasing the carrier concentration. The changes in PL peak energy and absorption edge with carrier concentration are not so steep compared to the absorption edge change predicted by Davydov et al. This may be explained by the increase in electron effective mass with increasing the carrier concentration reported by Wu et al. [Phys. Rev. B 66, 201403 (2002)]. (© 2003 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Improvement of luminescence capability of Tb3+‐related emission by AlxGa1−xN
Authors: Nakanishi Y. , Wakahara A. , Okada H. , Yoshida A. , Ohshima T. , Itoh H. 
Published: November 2003

AbstractThermal quenching of the trivalent Tb (Tb3+)‐related luminescence in AlxGa1−xN (x: 0.00–0.15) is investigated. Tb ions are introduced into AlxGa1−xN epitaxial layers, which are grown by organometallic vapor phase epitaxy, by implantation at 200 keV. For all samples, strong and sharp emission peaks attributed to the 4f‐4f transition of Tb3+ are observed around 490–600 nm. The thermal quenching of the luminescence intensity and the decay time related to Tb3+ transitions strongly depend on the Al contents, and the luminescence is suppressed by introducing Al into GaN. For AlxGa1−xN with x > 0.10, the Tb3+‐related green photoluminescence can be observed at room temperature. (© 2003 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Microstructure and electronic properties of InGaN alloys
Authors: Ponce F. A. , Srinivasan S. , Bell A. , Geng L. , Liu R. , Stevens M. , Cai J. , Omiya H. , Marui H. , Tanaka S. 
Published: November 2003

AbstractThe InxGa1−xN system has electronic band gaps extending from under 1eV to 3.4 eV, and as such they are used as the active layer in commercially available visible‐light emitting devices. There are many interesting features that make these nitride semiconductor alloys especially useful for efficient light emitters. It has been conjectured that the combination of piezoelectric fields and local composition inhomogeneities may be responsible for the observed high emission efficiencies, in spite of their characteristic high dislocation densities. But it is very difficult to grow InxGa1−xN layers with high indium composition. This paper presents an overview of the properties of InxGa1−xN epilayers based on a systematic study of thick layers and of quantum well structures. We find that the microstructure of thick films varies significantly with indium composition. For x < 0.08, the composition is uniform and unperturbed by dislocations. For 0.10 < x < 0.20, secondary phases nucleate at threading dislocations. For x > 0.20, spontaneous phase separation occurs resulting in a polycrystalline, inhomogeneous layer. A correlation between optical properties and microstructure is presented. It is observed that the misfit strain is affected by threading dislocations. Mechanisms of misfit strain relaxation are presented for InxGa1−xN layers grown on standard GaN on sapphire and on epitaxial‐lateral‐overgrowth GaN layers. In addition, we have studied the properties of quantum well structures using several novel techniques. The electrostatic fields across the wells have been profiled using electron holography in the TEM. The effect of well thickness on the strength of the fields is reported. The effects of localization by compositional fluctuations and of internal field screening have been studied using time‐resolved cathodoluminescence spectroscopy. In spite of significant progress that has been made in the last ten years, much work remains ahead in order to master the science and technology of these alloys. (© 2003 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Field‐compensated quaternary InAlGaN/GaN quantum wells
Authors: Kalaïtzakis F. , Androulidaki M. , Pelekanos N. T. , Dimakis E. , Bellet‐Amalric E. , Jalabert D. , Cengher D. , Tsagaraki K. , Aperathitis E. , Konstantinidis G. , Georgakilas A. 
Published: November 2003

AbstractWe demonstrate that it is possible to reduce significantly the internal polarisation fields in InAlGaN/GaN quantum wells (QWs), provided that the composition of the quaternary layer is appropriate. We have experimentally estimated an internal field of 2.65 mV/Å in In0.085Al0.285Ga0.63N/GaN QWs, which is a factor of four smaller than in “equivalent” GaN/Al0.15Ga0.85N QWs. Preliminary optical pumping experiments on laser structures using as active medium In0.085Al0.285Ga0.63N/GaN QWs have shown lower threshold than GaN/AlGaN laser structures at room temperature. (© 2003 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Nitrides as spintronic materials
Authors: Dietl Tomasz 
Published: November 2003

AbstractThe Guest Editors of the Proceedings of the 5th International Conference on Nitride Semiconductors (ICNS‐5), Hiroshi Amano and Takashi Udagawa, have nominated the invited presentation by Tomasz Dietl [1] as Editor's Choice of the present issue of physica status solidi (b). This paper is a progress report on spintronics‐related issues in Mn‐based III‐nitrides as potential diluted magnetic semiconductors.The cover picture shows the computed values of the Curie temperature for various p‐type III–V compounds containing 5% of Mn in the S = 5/2 high spin state and 3.5 × 1020 holes per cm3, predicting that TC should exceed room temperature in the Mn‐based nitrides.Thomas Dietl is head of the Low‐Temperature Physics Group and professor at the Institute of Physics of the Polish Academy of Sciences. He is one of the most experienced researchers in the area of ferromagnetic semiconductors, spin‐related phenomena and other current topics of semiconductor physics with many publications and invited talks at conferences and seminars world‐wide.The full Proceedings of the 5th International Conference on Nitride Semiconductors (ICNS‐5) are published in physica status solidi (c) – conferences and critical reviews, Vol. 0, No. 7 (November 2003) (ISBN 3‐527‐40489‐9). Conference papers can also be found in phys. stat. sol. (a) 200, No. 1 (2003).
Experimental Studies on the Carboxymethylation of Arrowroot Starch in Isopropanol‐Water Media
Authors: Kooijman Laura M. , Ganzeveld Klaassien J. , Manurung Robbert M. , Heeres Hero J. 
Published: November 2003

AbstractThe reaction between granular arrowroot starch and sodium monochloroacetate (SMCA) in isopropanol‐water mixtures has been studied in a systematic way using experimental design strategies. The effect of six factors, i.e. the theoretical degree of substitution (DSt), reaction time, weight fraction of water in the mixture, NaOH/SMCA ratio, temperature and weight fraction of starch on three responses, i.e. the degree of substitution (DS), the conversion of SMCA and the selectivity of SMCA towards carboxymethyl starch, has been determined in a systematic manner. Granular carboxymethyl arrowroot starch with a maximum DS of 1.4 could be prepared in a singlestep procedure. The results are compared with data obtained for potato starch. Similar trends for all responses were observed, suggesting close similarities between the chemical composition and the topochemistry of granular arrowroot‐ and potato‐starch.
The spatial restrictions of 5′HoxC genes expression are maintained in adult newt spinal cord
Authors: Nicolas S. , Papillon D. , Perez Y. , Caubit X. , Le Parco Y. 
Published: November 2003

Abstract Urodele amphibians are the only adult vertebrates possessing the capacity to regenerate their limbs and tail after amputation. Epimorphic regeneration is characterized by the accumulation of undifferentiated and dividing mesenchymal cells originating from the tissues of the stump, which form a blastema. It has been proposed that the ability to regenerate precisely the amputated structures depends on a ‘positional memory’ of the cells at the level of amputation plane and that a continuum of positional value would be present in adult urodeles along the appendages able to regenerate. Hox genes are good candidates for playing a role in providing the capacity for regeneration and for carrying positional information. Here, we report the cloning of four AbdB‐like genes (Hoxa9, Hoxc10, Hoxc12 and Hoxc13) in the newt Pleurodeles waltl (Pw). To analyse their expression pattern along the antero‐posterior (AP) axis of adult urodele central nervous system (CNS), we used the reverse transcription‐polymerase chain reaction (RT‐PCR) and showed that the 5’HoxC genes expression pattern conforms to the usual spatial colinearity rule. In addition, the expression level in tail regenerates of PwHoxc13, PwHoxc12, and PwHoxc10 was respectively 20, 7 and 2 fold higher than in adult tail. These last results suggest that 5′HoxC genes could specify positional memory in adult spinal cord (SC) and could be involved in axial patterning of the tail during regeneration.
Hydrogen peroxide‐induced apoptosis in pc12 cells and the protective effect of puerarin
Authors: Jiang B. , Liu J. H. , Bao Y. M. , An L. J. 
Published: November 2003

AbstractIn this study, the effect of puerarin on hydrogen peroxide‐induced apoptosis in PC12 cells was studied. Exposure of cells to 0.5 mM H2O2may cause significant viability loss and apoptotic rate increase. When c‐Myc, Bcl‐2 and Bax expression and caspase‐3 activity were measured, using Ac‐DEVD‐AMC as a substrate, the changes in these apoptosis regulatory and effector proteins suggested that the elevation of c‐Myc, decrease in Bcl‐2: Bax protein ratio, and caspase‐3 activation all play a key role in apoptosis. When cells were treated with puerarin prior to 0.5 mM H2O2treatment, a reduction in viability loss and apoptotic rate was seen. In addition, c‐Myc expression decreased and Bcl‐2: Bax ratio increased. Puerarin also reduced the H2O2‐induced elevation of caspase‐3 activation. These results suggest that puerarin can protect neurons against oxidative stress. It can block apoptosis in its early stages via the regulation of anti‐ and pro‐apoptotic proteins, as well as by the attenuation of caspase‐3 activation in H2O2‐induced PC12 cells.
Distigmine bromide induced acute psychotic disorder in a patient with multiple sclerosis
Authors: Himmerich Hubertus , Szegedi Armin , Klawe Christoph , Anghelescu Ion , Müller Matthias J. 
Published: November 2003

AbstractA female patient with multiple sclerosis (MS) suffered from an acute psychotic disorder after taking distigmine bromide for detrusor dysfunction. She showed a dramatic relief of her symptoms after the medication, distigmine bromide, was stopped. Distigmine is not supposed to penetrate the blood-brain barrier (BBB). However, in MS patients a leakage of the BBB could be hypothesized.
Number of dementia sufferers in Europe between the years 2000 and 2050
Authors: Wancata Johannes , Musalek M. , Alexandrowicz R. , Krautgartner M. 
Published: November 2003

AbstractSeveral authors have pointed out that in the next few decades dementia will affect a considerably increasing number of the elderly. To our knowledge there exist no calculations of the number of demented persons for the whole European region. We made calculations on the number of dementia cases for the period 2000–2050 based on the population projections of the United Nations. For this purpose, we used the results of several meta-analyses of epidemiological studies. The number of prevalent dementia cases in the year 2000 was 7.1 million. Within the next 50 years, this number will rise to about 16.2 million dementia sufferers. The number of new dementia cases per year will increase from about 1.9 million in the year 2000 to about 4.1 million in the year 2050. Contrarily, the working-age population will considerably decrease during the next 50 years. In the year 2000, 7.1 million dementia cases faced 493 million persons in working-age. This equals a ratio of 69.4 persons in working-age per one demented person. Until the year 2050, this ratio will decrease to only 21.1. Thus, the financial and emotional burden placed by dementia on the working-age population will markedly rise.
Determinants of burden in caregivers of patients with exacerbating schizophrenia
Authors: Lauber Christoph , Eichenberger Adrian , Luginbühl Peter , Keller Christian , Rössler Wulf 
Published: November 2003

AbstractPurposeRestriction in involuntary hospital admission and reduced lengths of inpatient stay increase burden on relatives of individuals with schizophrenia. This study aims at assessing the relationship between caregiver burden and behavioural disturbances of the affected, e.g. threats, nuisances, but also substance use and aggression. Two weeks before the last hospitalisation of the affected are considered as being the most burdensome period for relatives.Subjects and methodsSixty-four relatives of schizophrenic patients were assessed by the semi-structured “Interview for Measuring the Burden on the Family”. Subscales and total scales of burden were calculated. Predictors were identified by regression analyses.ResultsThe most important predictor of burden is burden in the relationship between caregiver and the affected representing the changes in the relationship occurring in acute illness. Threats, nuisances, time spent with the affected, and burden due to restricted social life and leisure activities were additional predictors, but not aggression or substance abuse. Eighty-five percent of the cases could be assigned correctly.Discussion and conclusionsTo better encounter burden, relatives should learn to cope with disturbing behaviour of and altered relationship to the affected, but also with their own needs. Finally, relatives must be included in the decision whether or not an affected person should be hospitalised.
Involuntary medication in psychiatric inpatient treatment
Authors: Kaltiala-Heino R. , Välimäki M. , Korkeila J. , Tuohimäki C. , Lehtinen V. 
Published: November 2003

AbstractThe aim of this study was to examine involuntary medication in psychiatric inpatient treatment. A retrospective chart review of 1543 consecutive admissions of working aged civil patients from well-defined catchment areas to three psychiatric centres were evaluated regarding events of involuntary medication. 8.2% of the admissions included involuntary medication episode(s). Involuntary medication was associated with a diagnosis of schizophrenia, involuntary legal status and having previously been committed. One of the studied centres used less involuntary medication than the other two, even if patients with schizophrenia were over-represented in that centre. Although involuntary medication mainly takes places in the treatment of patients who are conceptualised most ill and perhaps resist treatment most, treatment culture obviously also plays a role. In future, it is important to study the aspects of treatment culture to fully understand the use of involuntary medication in psychiatry.
Growth‐related changes in cell body size and succinate dehydrogenase activity of spinal motoneurons innervating the rat soleus muscle
Authors: Ishihara Akihiko , Kawano Fuminori , Ishioka Noriaki , Oishi Hirotaka , Higashibata Akira , Shimazu Toru , Ohira Yoshinobu 
Published: November 2003

AbstractCell body sizes and oxidative enzyme (succinate dehydrogenase) activities of spinal motoneurons innervating the soleus muscle were determined in rats ranging in postnatal age from 3 to 13 weeks. The soleus motoneurons were labeled by a retrograde neuronal tracer, nuclear yellow. The mean cell body sizes of motoneurons increased from 3 to 7 weeks of age, while the mean succinate dehydrogenase activities of motoneurons decreased from 3 to 7 weeks of age. There were no changes in mean cell body size or mean succinate dehydrogenase activity of motoneurons from 7 to 13 weeks of age. An inverse relationship between cell body size and succinate dehydrogenase activity of motoneurons was observed, irrespective of age. These results indicate that motoneurons innervating the rat soleus muscle show the adult pattern of cell body size and succinate dehydrogenase activity at an earlier stage of postnatal growth, 7 weeks of age.
FasL‐induced downregulation of CD28 expression on jurkat cells in vitro is associated with activation of caspases
Authors: Ma Shibin , Ochi Hirotomo , Cui Lianxian , He Wei 
Published: November 2003

AbstractLigation of CD28, which is present on the majority of CD4+T cells, promotes proliferation and immune responses. However, expression of CD28 declines with aging, and apoptosis may contribute to this decline. We have investigated the molecular mechanism underlying the decrease in CD28 expression in Jurkat T cells cultured with FasL. FasL blocks expression of CD28 at the transcriptional level. This correlates with activation of caspase cascades: active caspase‐3 can be detected and inhibitors of caspase‐3 and caspase‐8 increase CD28 promoter activity and CD28 expression. These findings are consistent with the hypothesis that apoptosis plays a key role in the age‐related decline of CD28 expression and hence in immunosenescence.
Stunning and myocardial contractile autoregulation studied on the isolated isovolumic blood‐perfused dog heart
Authors: Tucci P. J. F. , Sant'Ana O. , Nogueira R. J. , Murad N. , Lopes A. C. , Sañudo A. , Peres C. A. 
Published: November 2003

AbstractAim:  To study, for the first time, the effects of stunning on homeometric and heterometric autoregulation.Methods and results:  Ischaemia (15 min)/reperfusion (30 min) was induced in the isovolumic blood‐perfused dog heart preparation. Heart rate elevations (n = 9) from 60 to 200 beats min−1, in steps of 20 beats min−1, promoted the same inotropic stimulation in control (C) and stunning (S), indicating that ischaemia/reperfusion does not affect the changes in calcium kinetics elicited by the Bowditch effect. Sudden ventricular dilation (VD) (n = 10) evoked an instantaneous increase in developed pressure (Δ1DP) followed by a continuous slow performance increase (Δ2DP) in C and S. Δ1DP (C: 35 ± 2.2 mmHg; S: 27 ± 2.1 mmHg; P = 0.002) and Δ2DP (C: 20 ± 1.6 mmHg; S: 14 ± 1.3 mmHg; P = 0.002) decreased proportionally, while Δ2/Δ1DP (C: 0.57 ± 0.13; S: 0.58 ± 0.14) and slow response time course (T/2) were unchanged (C: 55 ± 6.6 s; S: 57 ± 7.7 s) after ischaemia/reperfusion. The reduction of Δ1DP can be understood as a decline of the myofilaments calcium responsiveness, the main pathophysiological effect of stunning. The reason for the weakening of Δ2DP, due to intracellular calcium gain, was not determined but it was supposed that its complete manifestation could be restricted by cyclic adenosine monophosphate (cAMP) myocardial content reduction. As reported by others, Δ2DP depends on myocardial cAMP, and it has been shown that myocardial cAMP is decreased after ischaemia/reperfusion.Conclusions:  Contractile depression due to stunning has no effect on the inotropic stimulation generated by the Bowditch phenomenon. Immediate and time‐dependent enhancements of contraction evoked by sudden VD are proportionally reduced and the slow response time course is unaffected in the stunned myocardium.
Visualization of nitric oxide production and intracellular calcium in juxtamedullary afferent arteriolar endothelial cells
Authors: Pittner J. , Liu R. , Brown R. , Wolgast M. , Persson A. E. G. 
Published: November 2003

AbstractAim:  Nitric oxide (NO) is an important signal transmitter with multiple haemodynamic functions in the kidney. Study of these is complicated by the difficulty in measuring NO directly or visualizing its production. Recently the synthesis of a group of new NO‐sensitive fluorescent dyes, diaminofluoresceins (DAF), suitable for imaging applications has been reported. We attempted to use one DAF (DAF‐2 DA) to investigate the relationship between endothelial calcium, NO production and afferent arteriolar reactivity.Methods:  We used the isolated, perfused juxtamedullary nephron preparation (JMN) and loaded the afferent arteriolar endothelium with Fura‐2 AM and DAF‐2 DA (4,5‐diaminofluorescein‐2‐diacetyl). After in vitro calibration of the imaging system, we measured Fura‐2 and DAF‐2 fluorescence in single endothelial cells of afferent arterioles (AA) perfused at a pressure of 100 mmHg.Results:  Carboxy‐2‐phenyl‐4,4,5,5‐tetramethyl‐imidazoline‐1‐oxyl‐3‐oxide (carboxy‐PTIO) (10−3 m), a specific NO scavenger, decreased DAF‐2 fluorescence in the endothelium by 16.1% and the mid‐afferent arteriolar diameter by 10.2%, and increased endothelial calcium by 17.8%. Nω‐nitro‐l‐arginine methyl ester (l‐NAME) (10−4 m) decreased fluorescence intensity of DAF‐2 by 18.6%, increased cellular calcium level by 19.7% and constricted the vessels by 11.6%. Addition of carbachol (10−4 m) increased average DAF‐2 fluorescence by 22.8% and endothelial calcium concentration by 28.9%, whereas the arteriolar diameter remained essentially unchanged. Carbachol failed to increase DAF‐2 fluorescence when administered after l‐NAME pre‐treatment.Conclusion:  We conclude that endothelial NO homeostasis is an important determinant of AA reactivity and suggest that DAF are suitable for real‐time imaging of afferent arteriolar NO production in the isolated, perfused JMN and may be used in combination with calcium‐sensitive fluorophores. We have found that NO reduction by carboxy‐PTIO or l‐NAME increases endothelial calcium, suggesting involvement of calcium signalling in an autocrine NO production feedback in the endothelium. This method should help to further clarify the role of endothelial NO in renal haemodynamics.