bluuebunny/crossref_metadata_2025 huggingface dataset:
Upregulation of Matrix Metalloproteinase 1 and Disruption of Mitochondrial Network in Skin Fibroblasts of Patients with MERRF Syndrome
Authors: MA YI‐SHING , CHEN YIN‐CHIU , LU CHING‐YOU , LIU CHUN‐YI , WEI YAU‐HUEI
Published: June 2005

Abstract: By using cDNA microarray and RT‐PCR techniques, we investigated the genome‐wide alteration of gene expression in skin fibroblasts from patients with myoclonic epilepsy and ragged‐red fibers (MERRF) syndrome. By screening for the genes with altered levels of expression, we first discovered that matrix metalloproteinase 1 (MMP1) was highly induced in the primary culture of skin fibroblasts of a female patient in a four‐generation family with MERRF syndrome. This phenomenon was confirmed in skin fibroblasts from three other MERRF patients harboring about 85% of mtDNA with A8344G mutation. A further study revealed that the expression of MMP1 could be further induced by treatment of the skin fibroblasts with 200 μM hydrogen peroxide (H2O2) and inhibited by 1 mM N‐acetylcysteine. Moreover, the intracellular level of H2O2 in skin fibroblasts of the female MERRF patient was higher than those of the asymptomatic family members and age‐matched healthy controls. These findings imply that the increase in the expression of MMP1 may represent one of the responses to the increased oxidative stress in the skin fibroblasts of MERRF patients. We suggest that in affected tissues the oxidative stress‐elicited overexpression of MMP1, and probably other matrix metalloproteinases involved in cytoskeleton remodeling, may play an important role in the pathogenesis and progression of mitochondrial encephalomyopathies such as MERRF syndrome.
Induction of Thioredoxin and Mitochondrial Survival Proteins Mediates Preconditioning‐Induced Cardioprotection and Neuroprotection
Authors: CHIUEH CHUANG C. , ANDOH TSUGUNOBU , CHOCK P BOON
Published: June 2005

Abstract: Delayed cardio‐ and neuroprotection are observed following a preconditioning procedure evoked by a brief and nontoxic oxidative stress due to deprivation of oxygen, glucose, serum, trophic factors, and/or antioxidative enzymes. Preconditioning protection can be observed in vivo and is under clinical trials for preservation of cell viability following organ transplants of liver. Previous studies indicated that ischemic preconditioning increases the expression of heat‐shock proteins (HSPs) and nitric oxide synthase (NOS). Our pilot studies indicate that the treatment of neuronal NOS inhibitor (7‐nitroindazole) and 6Br‐cGMP blocks and mimics, respectively, preconditioning protection in human neuroblastoma SH‐SY5Y cells. This minireview focuses on nitric oxide‐mediated cellular adaptation and the related cGMP/PKG signaling pathway in a compensatory mechanism underlying preconditioning‐induced hormesis. Both preconditioning and 6Br‐cGMP increase the induction of human thioredoxin (Trx) mRNA and protein for cytoprotection, which is largely prevented by transfection of cells with Trx antisense but not sense oligonucleotides. Cytosolic Trx1 and mitochondrial Trx2 suppress free radical formation, lipid peroxidation, oxidative stress, and mitochondria‐dependent apoptosis; knock out/down of either Trx1 or Trx2 is detrimental to cell survival. Other recent findings indicate that a transgenic increase of Trx in mice increases tolerance against oxidative nigral injury caused by 1‐methyl‐4‐phenyl‐1,2,3,6‐tetrahydropyridine (MPTP). Trx1 can be translocated into nucleus and phosphoactivated CREB for a delayed induction of mitochondrial anti‐apoptotic Bcl‐2 and antioxidative MnSOD that is known to increase vitality and survival of cells in the brain and the heart. In conclusion, preconditioning adaptation or a brief oxidative stress induces a delayed nitric oxide‐mediated compensatory mechanism for cell survival and vitality in the central nervous system and the cardiovascular system. Preconditioning‐induced adaptive tolerance may be signaling through a cGMP‐dependent induction of cytosolic redox protein Trx1 and subsequently mitochondrial proteins such as Bcl‐2, MnSOD, and perhaps Trx2 or HSP70.
Angiotensin II Stimulates Hypoxia‐Inducible Factor 1α Accumulation in Glomerular Mesangial Cells
Authors: CHEN TSO‐HSIAO , WANG JIN‐FONG , CHAN PAUL , LEE HORNG‐MO
Published: June 2005

Abstract: Hypoxia increases hypoxia‐inducible factor 1α (HIF‐1α) protein levels by inhibiting ubiquitination and degradation of HIF‐1α, which regulates the transcription of many genes. Recent studies have revealed that many ligands can stimulate HIF‐1α accumulation under nonhypoxic conditions. In this study, we show that angiotensin II (Ang II) increased HIF‐1α protein levels in a time‐ and dose‐dependent manner under normoxic conditions. Treatment of mesangial cells with Ang II (100 nM) increased production of reactive oxygen species (ROS). Ang II (100 nM) increased the phosphorylation of PDK‐1 and Akt/PKB in glomerular mesangial cells. Ang II‐stimulated HIF‐1α accumulation was blocked by the phosphatidylinositol 3‐kinase (PI‐3K) inhibitors, Ly 294001, and wortmannin, suggesting that PI‐3K was involved. Because increased ROS generation by Ang II may activate the PI‐3K‐PKB/Akt signaling pathway, these results suggest that Ang II may stimulate a ROS‐dependent activation of the PI‐3K‐PKB/Akt pathway, which leads to HIF‐1α accumulation.
Simple Cystatin C–Based Prediction Equations for Glomerular Filtration Rate Compared with the Modification of Diet in Renal Disease Prediction Equation for Adults and the Schwartz and the Counahan–Barratt Prediction Equations for Children
Authors: Grubb Anders , Nyman Ulf , Björk Jonas , Lindström Veronica , Rippe Bengt , Sterner Gunnar , Christensson Anders
Published: June 2005

Background: Serum creatinine is the most commonly used marker for estimation of glomerular filtration rate (GFR). To compensate for its drawbacks as a GFR marker, several prediction equations including several parameters are being used, with the Modification of Diet in Renal Disease (MDRD), Schwartz, and Counahan–Barratt equations being the ones most widely accepted for estimation of relative GFR in mL · min−1 · (1.73 m2)−1. The present study analyzes whether these GFR prediction equations for adults and children might be replaced by simple prediction equations based on plasma concentrations of cystatin C.

Methods: Data from 536 patients (0.3–93 years), consecutively referred for determination of GFR by an invasive gold standard procedure, were used for the analysis. Calculations of bias (median percentage of error), correlation (adjusted R2), and percentage of estimates within 30% and 50% of measured GFR were used in the comparisons.

Results: A cystatin C–based prediction equation using only concentration in mg/L and a prepubertal factor: GFR [mL · min−1 · (1.73 m2)−1] = 84.69 × cystatin C (mg/L)−1.680 × 1.384 (if a child <14 years) assessed GFR equally well or better than the simplified MDRD, the Schwartz, and the Counahan–Barratt prediction equations for the adult (≥18 years) and juvenile groups of the investigated cohort. Age did not influence the cystatin C–based prediction equation for adults, whereas gender did, but with a factor close to unity (0.948 for females).

Conclusion: A GFR prediction equation based solely on cystatin C (in mg/L) and a prepubertal factor might replace the simplified MDRD prediction equation for adults and the Schwartz and Counahan–Barratt prediction equations for children.
Eleven rules for a more successful clinical psychology
Authors: Hayes Steven C.
Published: June 2005

The recommendations put forth in the target article, “Twenty‐First Century Graduate Education in Clinical Psychology: A Four Level Matrix Model” (C.R. Snyder & T.R. Elliott, this issue), should be regarded in the context of the large need to develop a more progressive and effective discipline. No amount of “brute force” education and empiricism is certain to solve the problems of the scope of our field identified by the authors. Eleven rules are offered and defended that may lead to a more practically and empirically successful field. © 2005 Wiley Periodicals, Inc. J Clin Psychol.
An attachment theory perspective on the proposed matrix model
Authors: Shorey Hal S.
Published: June 2005

The matrix model (C.R. Snyder & T.R. Elliott, this issue) advocates an increased grounding of clinical psychology graduate students in theory. The matrix model is theory‐based in the ways that it advances this goal. Accordingly, evaluating the matrix model from an extant theoretical perspective should shed light on its applicability and utility as an educational framework. The present attachment theory perspective on the matrix model demonstrates that it meets its stated goals in that it possesses adequate (a) breadth in incorporating theory from across subdisciplines in psychology, and (b) depth in how it facilitates conceptualizing clients and research participants at the intrapersonal, interpersonal, and societal levels. The benefits for incorporating the matrix model in clinical psychology graduate programs are discussed. © 2005 Wiley Periodicals, Inc. J Clin Psychol.
A team effort: Reply to Snyder and Elliott
Authors: Hendrick Susan S.
Published: June 2005

This response to C.R. Snyder and T.R. Elliott's innovative proposals for training (this issue) highlights areas of agreement with the authors as well as encourages greater attention to several issues. These include counseling psychology and its historical emphasis on wellness, mentoring training for current faculty as well as graduate students, and appreciation for the diverse areas within psychology as well as within the broader social sciences (e.g., social work, marriage and family therapy) as contributors to such training. © 2005 Wiley Periodicals, Inc. J Clin Psychol.
Following the money: Economic inhibitors of change affecting graduate education in clinical psychology
Authors: Koocher Gerald P.
Published: June 2005

C.R. Snyder and T.R. Elliott (this issue) offer a thoughtful and elaborate model for future training in graduate clinical psychology, couched in visionary optimism. However, they interpret history and present trends in a manner that seems to ignore the realistic demands of economic forces. They propose thoughtful, constructive, pro‐social directions, but seem at least partially oblivious to underlying economic forces destined to impede meaningful implementation of their model. © 2005 Wiley Periodicals, Inc. J Clin Psychol.
Re‐envisioning the training and practice of clinical psychologists: Preserving science and research orientations in the face of change
Authors: Cook Joan M. , Coyne James C.
Published: June 2005

We argue for preservation of an expectation of psychologists that approach human problems from an evidence‐based perspective. Acquisition of the requisite knowledge, skills, and practical experience require access to resources outside of graduate psychology programs. Whether adhering to a scientist–practitioner or practitioner–scholar model, psychologists must be “scientifically literate.” Deficiencies are noted in the training of scientist–practitioner psychologists for the conduct of clinical trials and the dissemination and sustained implementation of evidence‐based interventions. © 2005 Wiley Periodicals, Inc. J Clin Psychol.
Progesterone primes zona pellucida‐induced activation of phospholipase A2 during acrosomal exocytosis in guinea pig spermatozoa
Authors: Shi Qi‐xian , Chen W.Y. , Yuan Y.Y. , Mao L.Z. , Yu S.Q. , Chen A.J. , Ni Y. , Roldan E.R.S.
Published: June 2005

We investigated, using guinea‐pig spermatozoa as a model, whether phospholipase A2 (PLA2) is involved in progesterone or zona pellucida (ZP)‐stimulated acrosomal exocytosis, if progesterone enhances ZP‐induced activation of PLA2, and mechanisms underlying PLA2 regulation. Spermatozoa were capacitated and labeled in low Ca2+ medium with [14C]choline chloride or [14C]arachidonic acid, washed, and then exposed to millimolar Ca2+ and progesterone and/or ZP. Each agonist stimulated decrease of phosphatidylcholine (PC) and release of arachidonic acid and lysoPC, indicative of PLA2 activation. Aristolochic acid (a PLA2 inhibitor) abrogated lipid changes and exocytosis, indicating that these lipid changes are essential for exocytosis. Exposure of spermatozoa to submaximal concentrations of both progesterone and ZP resulted in a synergistic increase of arachidonic acid and lysoPC releases, and exocytosis, suggesting that, under natural conditions, both agonists interact to bring about acrosomal exocytosis. Progesterone‐induced PLA2 activation appears to be mediated by a GABAA‐like receptor, because bicuculline (a GABAA receptor antagonist) blocked arachidonic acid release and exocytosis. In agreement with this, GABA mimicked progesterone actions. ZP‐induced activation of PLA2 seemed to be transduced via Gi proteins because pertussis toxin blocked arachidonic acid release and acrosomal exocytosis. PLA2 may be regulated by PKC because progesterone‐ or ZP‐induced release of arachidonic acid was blocked by the PKC inhibitors staurosporine or chelerythrine chloride. PLA2 could also be regulated by the cAMP‐PKA pathway; inclusion of the PKA inhibitor 14–22 amide or H‐89 led to a reduction in arachidonic acid release or exocytosis after progesterone or ZP. Taken together, these results suggest that PLA2 plays an essential role in progesterone or ZP‐stimulated exocytosis with progesterone priming ZP action. © 2005 Wiley‐Liss, Inc.
CXCL12 (SDF‐1) and CXCL13 (BCA‐1) chemokines significantly induce proliferation and collagen type I expression in osteoblasts from osteoarthritis patients
Authors: Lisignoli Gina , Toneguzzi Stefania , Piacentini Anna , Cristino Sandra , Grassi Francesco , Cavallo Carola , Facchini Andrea
Published: June 2005

To evaluate the role of CXC chemokines CXCL8 (IL8), CXCL10 (IP‐10), CXCL12 (SDF‐1), and CXCL13 (BCA‐1) in bone remodeling, we analyzed their effects on osteoblasts (OBs) obtained from subchondral trabecular bone tissue of osteoarthritis (OA) and post‐traumatic (PT) patients. The expression of CXC receptors/ligands (CXCR1/CXCL8, CXCR2/CXCL8, CXCR3/CXCL10, CXCR4/CXCL12, and CXCR5/CXCL13) was analyzed in cultured OBs by flow cytometry and immunocytochemistry. Functional assays on CXC chemokine‐treated‐OBs in the presence or absence of their specific inhibitors were performed to analyze cellular proliferation and the enzymatic response to chemokine activation. The expression of chemokine ligands/receptors was also confirmed in bone tissue samples by immunohistochemical analysis. Collagen type I and alkaline phosphatase mRNA expression were analyzed on CXCL12‐ and CXCL13‐treated OBs by real‐time PCR. OBs from both OA and PT patients expressed high levels of CXCR3 and CXCR5 and lower amounts of CXCR1 and CXCR4. CXCL12 and CXCL13, only in OBs from OA patients, induced a significant proliferation that was also confirmed by specific blocking experiments. Moreover, OBs from OA patients released a higher amount of CXCL13 than those of PT patients while no differences were found for CXCL12. In the remodeling area of bone tissue samples, immunohistochemical analysis confirmed that OBs expressed CXCL12/CXCR4 and CXCL13/CXCR5 both in OA and PT samples. CXCL12 and CXCL13 upregulated collagen type I mRNA expression in OBs from OA patients. These data suggest that CXCL12 and CXCL13 may directly modulate cellular proliferation and collagen type I in OA patients, so contributing to the remodeling process that occurs in the evolution of this disease. © 2005 Wiley‐Liss, Inc.
Crossing numbers of Sierpiński‐like graphs
Authors: Klavžar Sandi , Mohar Bojan
Published: June 2005

Crossing numbers of Sierpiński graphs S(n,k) and their regularizations S+(n,k) and S++(n,k) are studied. Drawings of these graphs are presented and proved to be optimal for S+(n,k) and S++(n,k) for every n ≥ 1 and k ≥ 1. The crossing numbers of these graphs are expressed in terms of the crossing number of Kk+1. These are the first nontrivial families of graphs of “fractal” type whose crossing number is known. © 2005 Wiley Periodicals, Inc. J Graph Theory
Synthesis of polyetherols with purine ring. Kinetics and mechanisms of reactions, part 1: Reaction of hydroxymethyl derivatives of uric acid with oxiranes
Authors: Cisek‐Cicirko Irmina , Lubczak Jacek
Published: June 2005

The kinetics and mechanisms of the initial steps of formation of polyetherols from hydroxymethyl derivatives of uric acid and oxiranes were studied. It has been found that initial steps of the reaction of polyetherol formation occur without a catalyst. The NH groups, which are formed upon release of formaldehyde from N‐ and O‐hydroxymethyl derivatives of uric acid, take part in the reaction. © 2005 Wiley Periodicals, Inc. Int J Chem Kinet 37: 464–471, 2005
Twitch airway pressure elicited by magnetic phrenic nerve stimulation in anesthetized healthy children
Authors: Rafferty Gerrard F. , Mustfa Naveed , Man William D. , Sylvester Karl , Fisher Antony , Plaza Miguel , Davenport Mark , Blaney Sean , Moxham John , Greenough Anne
Published: June 2005

Children with diaphragm dysfunction may be unable to maintain adequate ventilation. Accurate diagnosis is important, but can only be achieved using an appropriate test and reference range. The aim of this study, therefore, was to measure diaphragm contractility and examine the influence of age and maturation, using magnetic phrenic nerve stimulation in healthy children. Anterolateral magnetic stimulation (MS) of the phrenic nerves was performed using a 43‐mm figure‐eight coil in 23 children (14 male; mean age, 7.8 years; range, 1.8–15.7) anesthetized for minor surgery with sevoflurane gas. The airway was maintained with a cuffed laryngeal mask airway (LMA) which was briefly occluded during MS. Diaphragm contractility was assessed by measuring the airway pressure (TwPaw) elicited by MS. TwPaw responses were obtained in all subjects, with mean (SD) TwPaw 18.2 (6.8) cm H2O bilateral, 7.3 (3.2) cm H2O left unilateral, and 8.6 (3.1) cm H2O right unilateral. Subgroup analysis was performed in 17 of the children who were prepubertal. Their mean (SD) TwPaw was 17.3 (6.8) cm H2O bilateral, 7.1 (3.7) cm H2O left unilateral, and 8.3 (3.3) right unilateral. The mean (SD) intrapatient coefficients of variation for bilateral and left and right unilateral TwPaw were 8.4% (5.2), 6.7% (3.5), and 11.7% (10.3), respectively. Bilateral and left and right unilateral TwPaw were significantly related to age (P < 0.05). In healthy prepubertal children, diaphragm contractility is primarily influenced by age. Pediatr Pulmonol. 2005; 40:141–147. © 2005 Wiley‐Liss, Inc.
Benzidine photodegradation: a mass spectrometry and UV spectroscopy combined study
Authors: Madeira Paulo , Nunes M. R. , Borges C. , Costa F. M. A. , Florêncio M. H.
Published: June 2005

The benzidine photodegradation process was studied using UV/Vis spectroscopy and electrospray ionization mass spectrometry (ESI‐MS) combined with collision‐induced dissociation (CID) and tandem mass spectrometry (MS/MS). Mass spectrometry was used to characterize benzidine and to identify and characterize possible degradation products and intermediates. The MS data showed that benzidine is quite persistent in aqueous medium. Moreover, the MS analysis enabled us to propose the following three degradation products/intermediates: 4′‐nitro‐4‐biphenylamine, tetrahydroxybiphenyl and 4,4′‐dinitrobiphenyl. For the benzidine molecular ion and protonated molecule and for the protonated molecules of the degradation products/intermediates detected, fragmentation patterns are proposed based on CID and MS/MS data. For the photodegradation process different catalysts were used, namely the commercial TiO2 Degussa P25, and the laboratory‐prepared ZnO, TiO2 anatase and a titanium‐zinc oxide with a perovskite type structure. Comparison of the different catalysts showed that degradation was favoured with the commercial TiO2. Nevertheless, the other catalysts appear to be promising and economic alternatives for potential future remediation studies. Copyright © 2005 John Wiley & Sons, Ltd.
Touch Sensibility in the Hand
Authors: DELLON A LEE
Published: June 2005

Touch sensibility must be evaluated in most of our patients, and must be re-evaluated in many of them following surgery. Touch sensibility must be tested in our disability evaluations and in order to prognosticate regarding hand function. Touch sensibility evaluation can provide a non-invasive guide to acute compartmental syndrome management. Touch sensibility must be re-educated following nerve repair.
Meshed Adhesive Tape for the Treatment of Crushed Fingers in Children
Authors: DUTHIE G. , ADAMS J.
Published: June 2005

Over 300 children a year are treated at the Royal Aberdeen Children’s Hospital for crushed finger tips. We estimate that 5.8% of children, under 13 years of age, suffer this injury, mainly in domestic (72.5%) or car doors (12%). The treatment of partial avulsions of pulp with nail dislocation is described.
Neonatal Upper Limb Ischaemia. The Case for Conservative Management.
Authors: RAYNER C. R. , LLOYD D. J. , WARD K.
Published: June 2005

General supportive measures, the ability to avoid infection, the natural tendency to improvement and the feasability of major reconstructive procedures later suggest that neonatal limb ischaemia should be managed conservatively at first, despite an alarming appearance. The number of infants at risk, especially due to prematurity and effective resuscitation, is theoretically increasing.
“Rugby Finger”—Avulsion of Profundus of Ring Finger
Authors: LUNN P. G. , LAMB D. W.
Published: June 2005

The results of tendon grafting following avulsion of the profundus tendon to the ring finger (“Rugby finger”) are described. Function in the hand was improved in all cases and this is a method of treatment which should be considered by the surgeon experienced in tendon grafting in those patients who are young and well motivated.

The exact reason for the common involvement of the ring finger is not clear but the unique lumbrical origin from that profundus may be an important factor tethering the tendon in the palm, and this is suggested as the possible cause of this injury.
Ulnar Tunnel Syndrome
Authors: GRUNDBERG ARNIS B.
Published: June 2005

Ulnar tunnel syndrome or compression of the ulnar nerve at the wrist is of two distinct types. In the first type compression is at the level of the pisiform with involvement of both sensory and motor fibres. In the second type compression is distal to the pisiform with involvement of the motor fibres only.
Ultrastructure of Solitary Enchondromas
Authors: ZIMNY MARILYN L. , REDLER I.
Published: June 2005

Solitary enchondromas obtained from the small bones of the hand were studied with transmission electron microscopy.

Three cell types were seen as follows: (1) young looking, active cells with extensive dilated rough endoplasmic reticulum and well defined Golgi and mitochondria; (2) older looking, degenerating cells with dilated rough endoplasmic reticulum, well defined Golgi, glycogen masses, vacuoles containing tropocollagen, lipid and myelin figures; and (3) dying cells showing loss of cell membrane and lysosomal-like bodies.

A young chondroblastic cell may try to mature, become a normal chondrocyte that produces normal matrix but it does not succeed and dies.

Enchondromal cells are not capable of forming tropocollagen or synthesizing proteoglycans for the matrix.
An Open Twin Incision Technique of Carpal Tunnel Decompression with Reduced Incidence of Scar Tenderness
Authors: BIYANI A. , DOWNES E. M.
Published: June 2005

We retrospectively compared a single curved incision for carpal tunnel decompression (group A, 29 wrists in 26 patients) with a twin incision technique (group B, 34 wrists in 30 patients), leaving an intact bridge of skin at the base of the palm. Patients in group B reported statistically significant subjective improvement in the early post-operative period, with fewer residual symptoms and earlier recovery of function compared to patients in group A. After a mean post-operative period of 23 months, 5/29 wrists were symptomatic in group A compared to 1/34 wrists in group B at 13 months, but this was not statistically significant.

The twin incision technique is easy to perform and allows rapid post-operative recovery. The incidence of scar tenderness is reduced as palmar cutaneous branches of the median nerve are avoided. Because the distal portion of the transverse carpal ligament is divided under direct vision, this technique is not associated with any significant neurovascular complications.
THE FREQUENCY AND EFFECTING FACTORS OF CONSANGUINEOUS MARRIAGE IN A GROUP OF SOLDIERS IN ANKARA
Authors: KIR TAYFUN , GÜLEÇ MAHIR , BAKIR BILAL , HOŞGÖNÜL ESAT , TÜMERDEM NAZMI
Published: June 2005

This cross-sectional study was carried out to investigate the frequency of consanguineous marriage in a group of army conscripts in Ankara and the factors affecting this. Of 4153 soldiers, 387 were married. The rate of marriage between first cousins was found to be 19·1%, and the overall rate of consanguineous marriage was 24·1%. Consanguineous marriage was found to be significantly prevalent among soldiers who were born in and still living in the Eastern region; among those who lived in villages; among those whose parents as well as themselves had low educational levels; and among those whose marriages were arranged by their families. Neither the payment of bride-price nor the presence of consanguinity between parents was a significant factor for consanguineous marriage. In addition, the age of the soldier and the age at marriage were significantly lower among soldiers married to first cousins than among soldiers whose marriages were not consanguineous.
Undoing static correlation: Long-range charge transfer in time-dependent density-functional theory
Authors: Maitra Neepa T.
Published: June 2005

Long-range charge-transfer excited states are notoriously badly underestimated in time-dependent density-functional theory (TDDFT). We discuss how exact TDDFT captures charge transfer between open-shell species: in particular, the role of the step in the ground-state potential, and the severe frequency dependence of the exchange-correlation kernel. An expression for the latter is derived, that becomes exact in the limit that the charge-transfer excitations are well separated from other excitations. The exchange-correlation kernel has the task of undoing the static correlation in the ground state introduced by the step, in order to accurately recover the physical charge-transfer states.
Validation of intermolecular transfer integral and bandwidth calculations for organic molecular materials
Authors: Huang Jingsong , Kertesz Miklos
Published: June 2005

We present an interpretation of the intermolecular transfer integral that is independent from the origin of the energy scale allowing convergence studies of this important parameter of organic molecular materials. We present extensive numerical studies by using an ethylene π dimer to investigate the dependence of transfer integrals on the level of theory and intermolecular packing. Transfer integrals obtained from semiempirical calculations differ substantially from one another and from ab initio results. The ab initio results are consistent across all the levels used including Hartree–Fock, outer valence Green’s function, and various forms of density functional theory (DFT). Validation of transfer integrals and bandwidths is performed by comparing the calculated values with the experimental values of tetrathiafulvalene-tetracyanoquinodimethane (TTF-TCNQ), bis[1,2,5]thiadiazolo-p-quinobis(1,3-dithiole), (BTQBT) K-TCNQ, and hexagonal graphite. DFT in one of its presently popular forms, such as Perdew–Wang functionals (PW91), in combination with sufficient basis sets provides reliable transfer integrals, and therefore can serve as a basis for energy band calculations for soft organic materials with van der Waals gaps.
Direct measurement of relative and collective diffusion in a dilute binary colloidal suspension
Authors: Knowles Michelle K. , Honerkamp-Smith Aurelia R. , Marcus Andrew H.
Published: June 2005

Experimental characterization of the dynamics of multicomponent fluids is a problem of general importance to the field of complex fluids. We demonstrate a new experimental approach, termed two-color Fourier imaging correlation spectroscopy, which allows direct measurement of the partial dynamic structure factors, S11(k,τ), S22(k,τ), and S12(k,τ), where 1, 2 label the component species of a binary colloidal suspension. Linear combinations of the partial dynamic structure factors yield the characteristic time-correlation functions of the binary fluid. These are the correlation functions of concentration fluctuations SCC(k,τ), number density fluctuations SNN(k,τ), and cross-correlations between number density and concentration fluctuations SNC(k,τ). Test measurements are performed on a dilute symmetric mixture of fluorescently labeled 0.5 and 1.0μm polystyrene spheres. From these data, we determine generalized collective and relative diffusion coefficients, and compare them to the predictions for an ideal mixture of noninteracting particles.
Interaction of formic acid with solid water
Authors: Bahr S. , Borodin A. , Höfft O. , Kempter V. , Allouche A.
Published: June 2005

The interaction of formic acid (HCOOH) with solid water, deposited on tungsten at 80K, was investigated. We have prepared and annealed formic acid (FA)/water interfaces (FA layers on thin films of solid water and H2O adlayers on thin FA films). Metastable impact electron spectroscopy and ultraviolet photoemission spectroscopy (He I and II) were utilized to study the electron emission from the 10a′ to 6a′ molecular orbitals (MOs) of FA, and the 1b1, 3a1, and 1b2 MOs of H2O. These spectra were compared with results of density-functional theory calculations on FA-H2O complexes reported in Ref. 14 [A. Allouche, J. Chem. Phys. 122, 234703(2005), (preceding paper)]. Temperature programmed desorption was applied for information on the desorption kinetics. Initially, FA is adsorbed on top of the water film. The FA spectra are distorted with respect to those from FA monomers; it is concluded that a strong interaction exists between the adsorbates. Even though partial solvation of FA species takes place during annealing, FA remains in the top layer up to the desorption of the water film. When H2O molecules are offered to FA films at 80K, no water network is formed during the initial stage of water exposure; H2O molecules interact individually via H bonds with the formic acid network. Experiment and theory agree that no water-induced deprotonation of the formic acid molecules takes place.
Adhesion of polymer coatings studied by laser-induced delamination
Authors: Fedorov A. , De Hosson J. Th. M.
Published: June 2005

This paper concentrates on the laser-induced delamination technique, aimed at measuring the practical work of adhesion of thin polymer coatings on metal substrates. In this technique an infrared laser-pulsed beam is used to create an initial blister. Upon increasing the pulse intensity, the size of the blister grows, resulting in partial delamination of the film. In this work the blister profiles and the blister pressure were obtained from independent measurements. Alongside experiments, a simple model is developed to provide the equations necessary for calculating the blister strain energy, height, and the gas pressure inside the blister. The model is essentially based on an elastic behavior of the polymer film. The blister height and the blister pressure predicted by the model were confronted with the experimental observations and a fair agreement was found. The adhesion properties of the polyethylene terephthalate films on a steel substrate were characterized in terms of the maximum stress required for delamination and the practical work of adhesion. The relation between the two are discussed. Because the blister formation and subsequent delamination take place on a time scale of microseconds, it is argued that the viscous properties of the film do not manifest on this time scale and the contribution of plastic deformation of the film is rather small.
Measurement of ion motion in a shear Alfvén wave
Authors: Palmer Nathan , Gekelman Walter , Vincena Stephen
Published: June 2005

In this study, the technique of laser-induced fluorescence (LIF) has been used to meausure Ti and the E×B0 and polarization drifts of shear Alfvén waves in the Large Plasma Device at UCLA [W. Gekelman, H. Pfister, Z. Lucky, J. Bamber, D. Leneman, and J. Maggs, Rev. Sci. Instrum. 62, 2875 (1991)]. The waves were launched by an antenna located at the end of the device and were observed to propagate along the axis of a 9 m long, 40 cm diameter cylindrical argon plasma in the kinetic regime [βe≈9.5(me∕mi)], with fwave∕fci≈0.8. Care was taken to record the measurements from various diagnostics at the same spatial positions on four cross-sectional planes along the length of the plasma. Two-dimensional LIF measurements of the ion drifts perpendicular to B0 were undertaken. Ion drifts were observed to be as large as 14% of the ion thermal speed. The ion polarization and E×B0 drifts were distinguished by their phase relation to Bwave. The measured drifts are compared to kinetic theory. E⊥ (the transverse component of Ewave) was computed from the drift velocities, and E‖ was estimated from E⊥.
Density-functional molecular-dynamics study of the redox reactions of two anionic, aqueous transition-metal complexes
Authors: Tateyama Yoshitaka , Blumberger Jochen , Sprik Michiel , Tavernelli Ivano
Published: June 2005

The thermochemistry of the RuO42−+MnO4−→RuO4−+MnO42− redox reaction in aqueous solution is studied by separate density-functional-based ab initio molecular-dynamics simulations of the component half reactions RuO42−→RuO4−+e− and MnO42−→MnO4−+e−. We compare the results of a recently developed grand-canonical method for the computation of oxidation free energies to the predictions by the energy-gap relations of the Marcus theory that can be assumed to apply to these reactions. The calculated redox potentials are in good agreement. The subtraction of the half-reaction free energies gives an estimate of the free energy of the full reaction. The result obtained from the grand-canonical method is −0.4eV, while the application of the Marcus theory gives −0.3eV. These should be compared to the experimental value of 0.0eV. Size effects, in response to increasing the number of water molecules in the periodic model system from 30 to 48, are found to be small (≈0.1eV). The link to the Marcus theory also has enabled us to compute reorganization free energies for oxidation. For both the MnO42− and RuO42− redox reactions we find the same reorganization free energy of 0.8eV (1.0eV in the larger system). The results for the free energies and further analysis of solvation and electronic structure confirm that these two tetrahedral oxoanions show very similar behavior in solution in spite of the central transition-metal atoms occupying a different row and column in the periodic table.
Writing of nonlinear optical Sm2(MoO4)3 crystal lines at the surface of glass by samarium atom heat processing
Authors: Abe M. , Benino Y. , Fujiwara T. , Komatsu T. , Sato R.
Published: June 2005

Some glasses such as 21.25Sm2O3.63.75MoO3.15B2O3 (mol %) giving the formation of nonlinear optical Sm2(MoO4)3 crystals through conventional crystallization in an electric furnace and through continuous-wave Nd: yttrium aluminum garnet (YAG) laser (wavelength: 1064nm) irradiation (samarium atom heat processing) have been developed. It is proposed from x-ray diffraction analyses, micro-Raman-scattering spectra, and second-harmonic generation measurements that the crystal structure of Sm2(MoO4)3 formed by the crystallization is the β′-phase structure with an orthorhombic (noncentrosymmetric) symmetry. The lines consisting of nonlinear optical β′-Sm2(MoO4)3 crystals are written at the surface of glasses by YAG laser irradiation (laser power: P=0.4W, laser scanning speed: S=1–10μm∕s), and, in particular, homogeneous crystal lines are formed at the laser scanning speed of 1μm∕s. Refractive index changes (not crystallization) are also induced by YAG laser irradiation of P=0.4W and a high laser scanning speed of S=25μm∕s. The crystallization mechanism in the laser-irradiated region has been proposed. The present study demonstrates that the samarium atom heat processing is a technique for the writing of rare earth containing optical nonlinear/ferroelectric crystal lines in glass.
Density-functional theory band gap of wurtzite InN
Authors: Bagayoko D. , Franklin Lashounda
Published: June 2005

We report the calculated band gap of wurtzite indium nitride. Our ab initio computations employed a local-density approximation (LDA) potential and the linear combination of Gaussian orbital formalism. The implementation of the ab initio Bagayoko, Zhao, and Williams method [Phys. Rev. B 60, 1563 (1999)] led to a LDA band gap of 0.88eV, in excellent agreement with recent experiments. We also present calculated density of states (DOS) and the electron effective mass at the bottom of the conduction band. Our DOS curves indicate that an experiment could find values of the band gap up to 2eV, depending on the sensitivity of the apparatus, the interpretation of resulting data, and associated uncertainties.
Vlasov–Maxwell equilibrium solutions for Harris sheet magnetic field with Kappa velocity distribution
Authors: Fu W.-Z. , Hau L.-N.
Published: June 2005

An exact solution of the steady-state, one-dimensional Vlasov–Maxwell equations for a plasma current sheet with oppositely directed magnetic field was found by Harris in 1962. The so-called Harris magnetic field model assumes Maxwellian velocity distributions for oppositely drifting ions and electrons and has been widely used for plasma stability studies. This paper extends Harris solutions by using more general κ distribution functions that incorporate Maxwellian distribution in the limit of κ→∞. A new functional form for the plasma pressure as a function of the magnetic vector potential p(A) is found and the magnetic field is a modified tanhz function. In the extended solutions the effective temperature is no longer spatially uniform like in the Harris model and the thickness of the current layer decreases with decreasing κ.
Breakdown of ultrathin native oxide films at contact interfaces of electromechanically stressed silicon microdevices
Authors: Kogut L. , Komvopoulos K.
Published: June 2005

Breakdown of oxide films at contact interfaces can result in significant current fluctuations with severe consequences on the long-term performance of electromechanical microdevices. Contrary to metal-oxide-semiconductor technology, the physical phenomena leading to breakdown of ultrathin native oxide films at silicon contact interfaces due to electromechanical stresses remain elusive. The objective of this study was to bridge this gap by performing experiments with special silicon microdevices subjected to different electrical actuation voltages and dwell contact times. Abrupt excursions in the current flow across the contact interface indicated the occurrence of breakdown events in the electromechanically stressed oxide films at the contact interface. The post-breakdown current–voltage response remained non-Ohmic, which is characteristic of the conduction paths produced during the breakdown events. The relatively long duration (a few seconds) of the electrical transient response is not indicative of contact bouncing, which is on the order of a few microseconds. The abrupt changes in the current density across the contact interface are associated with the formation of defects in the silicon oxide film.
Study of relaxation kinetics in argon afterglow by the breakdown time delay measurements
Authors: Marković V. Lj. , Gocić S. R. , Stamenković S. N. , Petrović Z. Lj.
Published: June 2005

In this paper the afterglow kinetics in argon is studied by the breakdown time delay measurements as a function of relaxation time t¯d(τ) (“memory curve”). Measurements were carried out at the pressure of 1.33mbar in a gas tube with gold-plated copper cathode and approximate and exact numerical models are developed to follow metastable and charged particle decay. It was found that the early afterglow kinetics is governed by the charged particle decay up to hundreds of milliseconds, extending from ambipolar to the free diffusion limit. Quenching processes reduce the effective lifetime of metastable states several orders of magnitude below that relevant for the time scale of the observations if realistic abundances and processes are included in the model. Nitrogen atoms originating from impurities and recombining on the cathode surface can determine the breakdown time delay down to that defined by the level of cosmic rays and natural radioactivity.
Microwave modulation of electron heating and Shubnikov–de Haas oscillation in two-dimensional electron systems
Authors: Lei X. L. , Liu S. Y.
Published: June 2005

Recently discovered modulations of Shubnikov–de Haas oscillations in microwave-irradiated two-dimensional electron systems are shown to arise from electron heating induced by the radiation. The electron temperature, obtained by balancing the energy absorption from the microwave field and the energy dissipation to the lattice through realistic electron-phonon couplings, exhibits resonance. The modulation of the Shubnikov–de Haas oscillation and the suppression of magnetoresistance are demonstrated together with microwave-induced resistance oscillation, in agreement with experimental findings.
Unintentionally doped n-type Al0.67Ga0.33N epilayers
Authors: Nakarmi M. L. , Nepal N. , Lin J. Y. , Jiang H. X.
Published: June 2005

Unintentionally doped Al0.67Ga0.33N epilayers were grown on AlN∕sapphire templates by metalorganic chemical vapor deposition. Optimized undoped Al0.67Ga0.33N epilayers exhibited an n-type conductivity as confirmed by Hall-effect measurement with a room-temperature resistivity of about 85Ωcm. Variable temperature Hall-effect measurement revealed the existence of a shallow donor level with activation energy of about 90meV. The photoluminescence (PL) spectra exhibited an emission peak at 4.13eV (4.06eV) related to an impurity transition at 10K (300K). Temperature dependent PL measurement also confirmed the existence of a shallow donor with comparable activation energy as that obtained by Hall-effect measurement. Isolated oxygen impurities are believed to be a strong candidate of the donor that remains as a shallow state in AlxGa1−xN up to x∼0.7. Compensating defects and the nature of the O donor in Al0.67Ga0.33N epilayers are also discussed.
Plasmon effects on infrared spectra of GaN nanocolumns
Authors: Iwanaga Takeshi , Suzuki Toshihiko , Yagi Shigeru , Motooka Teruaki
Published: June 2005

Infrared (IR) transmission spectra of GaN nanocolumns were analyzed. In addition to the bulk GaN optical phonon signal, a broad absorption peak was observed from undoped and Mg-doped nanocolumns. The central position and width of the broad peak changed with the growth condition and Mg concentration. Based on the Lorentz–Drude model composed of phonon and plasmon modes associated with depolarization fields in GaN nanocolumns, IR transmission spectra were fitted by adjusting the free-electron concentration and scattering rate. Dependence of these values on the column size and impurity concentration is discussed.
Improved Method for the Growth of Yttrium-Iron and Yttrium-Gallium Garnets
Authors: Nielsen J. W.
Published: June 2005

Large single crystals of yttrium and rare earth iron garnets, and yttrium and rare earth gallium garnets,have been grown from molten solutions of lead oxide and lead fluoride. The crystals are grown by slowly cooling melts from about 1260°C to near 950°C. Sample compositions are: for YIG, 8 mole % Y2O3, 22 mole% Fe2O3, 30 mole % PbO and 40 mole % PbF2; for YGaG, 5.8 mole % Y2O3, 14 mole % Ga2O3, 39.4 mole% PbO and 40.8 mole % PbF2.

This method provides crystals both large in size and of superior quality. Best results are obtained when the containing crucible is hotter near its top than at its base since nucleation is thereby reduced.
New Material for Permanent Magnets on a Base of Mn and Al
Authors: Koch A. J. J. , Hokkeling P. , v. d. Steeg M. G. , de Vos K. J.
Published: June 2005

During an investigation of the Mn-Al system from 40–100% Mn, a new metastable phase was found,which has a tetragonal structure with lattice constants a = 2.77 A and c = 3.57 A and lattice positions 000 and 121212 with a preference of the Mn atoms for one of these positions. This τ phase, which has the approximate composition Mn1.11 Al0.89, can only be obtained by special heat treatment. It possesses remarkable magnetic properites. From the approach to saturation an anisotropy constant of about 107 ergs/cm3 can be calculated, while the extrapolated value σ∞ amounts to 96 erg/oe g; the latter corresponds to a 4πIs of 6200 G.

Particles obtained by grinding the bulk material possess an HCI value of up to 6000 oe. No fixed correlation exists between particle size and the value of HCI; the latter is strongly dependent on the method of pulverization, and the authors are inclined to think that HCI is largely determined by the extent of deformation.

The increase of HCI caused by grinding is accompanied by a decrease of the magnetic moment. This decrease can be partially reversed by aging. The observed decrease in the magnetic moment on pulverizing agrees with the value calculated from X-ray and neutron diffraction data. The current fine-particle theory is unable to give an adequate explanation of the HCI.

An anisotropic permanent magnet was obtained by swaging cast bars, with the following properties in the preferred direction: Br = 4280 G, HCI = 4600 oe, HCB = 2750 oe, BHmax = 3.5×106 G oe.
Survey of Ferromagnetic Resonance in Small Ferrimagnetic Ellipsoids
Authors: Morgenthaler Frederic R.
Published: June 2005

This paper discusses the response of the magnetization in a small ferrimagnetic ellipsoid, magnetized in an arbitrary direction and excited by spatially uniform microwave magnetic fields, when a typical spin wave is present. The generalized Kittel frequency is given, and possible frequency generation processes appropriate to the ellipsoidal geometry are treated. If the ellipsoid is magnetized at an angle to a principal axis,time-varying components of demagnetizing field at the fundamental frequency occur in the longitudinal direction, as well as transverse components varying at this frequency. Previous analyses have not included such a possibility and certain interesting solutions have, therefore, been missed. In particular, it is found that subharmonics as well as harmonics may be created when the driving field exceeds a certain threshold power. The particular case of the half-frequency resonance is considered and the conditions for the minimum threshold are given. The generalized Suhl spin-wave spectrum is found, together with the coupling relations between the uniform precession and the spin wave. The Suhl first and second order instability thresholds, for the general ellipsoid, are formulated, and a zero order coupling is established for certain transient states of the magnetization. In addition, direct parametric coupling between a longitudinal pumping field and both the uniform precession and the spin waves is discussed.
Internal Friction Anomalies in Ferromagnets and Antiferromagnets near the Curie Point
Authors: Belov K. P. , Katayev G. I. , Levitin R. Z.
Published: June 2005

Measurements of the temperature dependence of internal friction in a number of ferromagnets and antiferromagnets were carried out. In ferromagnetic alloys (Invars) and antiferromagnets (MnO etc.), which have a large spontaneous deformation of the crystalline lattice near the Curie point, sharp peaks of the internal friction were found. The thermodynamical theory of second order phase transitions is used to interpret this phenomenon.