The incremental change of the SP wave vector and the

The incremental change of the SP wave vector and the selleck products DOS are also observed with increasing dielectric constant of the material on top metal layer. Previous experimental results on interactions between semiconductor excitons and nanostructured

Ag/Au SPs are considered and explained using such SP DOS.”
“Background: Acute otitis media (AOM) is the most common childhood diagnosis, leading to prescription of all antibiotic in the United States. Although antibiotics are used in children with AOM, in part, to Shorten the duration of symptoms, no instruments have been developed to track early changes in Symptoms from the parent’s point The goal of the present study was to develop and evaluate a parent-reported symptom scale for children with AOM (AOM-SOS) for use as an outcome measure in AOM treatment trials.

Methods: From a pool of 28 potential symptoms, we selected 7 on the basis of parent questionnaire, expert interviews, and review of the literature (or inclusion in the AOM-SOS. We administered the AOM-SOS to a primary-care sample of children aged 6-25 months enrolled in a study of nasopharyngeal bacterial colonization. Children were seen for well visits, illness visits, and AOM follow-up visits. At each visit, parents completed the AOM-SOS

and their children were examined by trained otoseopists, As part of the evaluation of the AOM-SOS, we examined the association between each item on the questionnaire and the clinical diagnosis of AOM while adjusting for the presence of upper respiratory tract infection. To assess responsiveness, we examined the change in AOM-SOS S63845 manufacturer scores in patients with AOM who were seen for follow-up within 3 weeks of diagnosis.

Results: We evaluated 264 children (mean age, 12.5 months at entry) p38 MAP Kinase pathway at a total of 642 visits. We diagnosed AOM at 24% of the visits. Each item on the questionnaire was significantly associated with the clinical diagnosis of AOM (P < 0.001 for each), before and after adjusting for the presence or absence of upper respiratory infection. The mean AOM-SOS score at visits when AOM was diagnosed was 3.71, compared with 0.96 at visits

when AOM was not diagnosed (P < 0.001). Internal reliability of the scale its measured by Cronbach’s alpha was 0.84. AOM-SOS scores in children with AOM who were otoscopically improved decreased by all average of 2.81 points (standardized response mean = 0.73).

Conclusions: We have developed a short symptom scale for children with AOM. This study provides preliminary data on the performance of the AOM-SOS in a primary care sample of children.”
“The effects of addition of two chemical blowing agents in cellular rubber blend of natural rubber (NR) and styrene-butadiene rubber (SBR) at a fixed blend ratio of 1 : 1 on cure characteristics, and mechanical and morphological properties were invesigated. The chemical blowing agents used in this work were Oxybis (benzene sulfonyl) hydrazide (OBSH) and Azo dicarbonamide (ADC).

Animals in group 2 were given ginger (50 mg/kg/day) in drinking w

Animals in group 2 were given ginger (50 mg/kg/day) in drinking water for 8 weeks. Rats in group 3 (DEN group) were injected with a single dose of DEN (200 mg/kg, i.p.), 2 weeks later received a single dose of CCl4 (2 mL/kg i.g) by gavage as 1:1 dilution in corn oil. Animals in group 4 (DEN-ginger group) received the

same carcinogenesis induction protocol as in group 3 plus ginger (50 mg/kg/day) in drinking click here water for 2 weeks before induction of hepatocarcinogenesis and continued throughout the experimental period. DEN-initiated and CCl4-promoted hepatocarcinogenesis in male Wistar rats was manifested biochemically by elevation of serum hepatic tumor markers tested; alpha-fetoprotein and carcinoembryonic antigen. In addition, hepatocarcinogenesis was further confirmed by a significant increase in hepatic tissue growth factors; vascular endothelial growth factor, basic fibroblast growth factor, and hydroxyproline content. A marked decrease in endostatin and metallothonein were also observed. Long-term ginger extract administration 2 weeks before induction of hepatocarcinogenesis and throughout the experimental period prevented the decrease of the hepatic content Dinaciclib Cell Cycle inhibitor of metallothionein and endostatin and the increase in the growth factors induced by the carcinogen. Moreover, ginger extract normalize serum hepatic tumor markers. Histopathological

examination of liver tissue also correlated with the biochemical observations. These findings suggest a protective effect of ginger extract against premalignant stages MK-4827 inhibitor of liver cancer in the DEN-initiated and CCl4-promoted hepatocarcinogenesis model in rats. (C) 2010 International Union of Biochemistry and Molecular Biology, Inc. Volume 36, Number 6, November/December

2010, Pages 483-490. E-mail: [email protected]
“Plantar warts are a common reason for dermatological consultations and their treatment can occasionally be a challenge. Plantar warts are benign lesions produced by the human papillomavirus (HPV) that often fail to respond to habitual treatment. Cidofovir is a potent antiviral drug that acts competitively, inhibiting viral DNA polymerase. Our aim was to assess the efficacy and safety of cidofovir cream for the treatment of viral plantar warts. We undertook a retrospective observational study of patients with plantar warts who received treatment with topical cidofovir between July 2008 and July 2011 at the Dermatology Service of the Hospital Costa del Sol, Marbella, Spain. Data about the rate of treatment response, the adverse effects, and recurrences, as well as the characteristics of the patient cohort, were recorded. We identified 35 patients who had received some previous treatment. The usual concentration was 3% (in 33 of 35 cases), applied twice a day (in 31 of 35 cases). A greater or lesser response was noted in 28 cases. There were two recurrences.

In the stress-free control condition, the adolescent group showed

In the stress-free control condition, the adolescent group showed higher fear-potentiated startle responses, larger dendritic arborization, more proximal dendritic spine distribution and lower levels of truncated TrkB than the adult rats. Social instability stress exerted opposite effects on fear-potentiated

startle responses selleckchem in these two groups, i.e., the stress period appeared to hamper the performance in adolescents but improved it in adult rats. Furthermore, whilst the chronic social stress applied to adolescent rats reduced their dendritic field and spine density in basal and lateral amygdala neurons, the opposite stress effects on neuron morphology were observed in the adult rats. Moreover, stress LDN-193189 in vivo in adolescence suppressed the amygdala expression of synaptic proteins, i.e., full-length TrkB and SNAP-25, whereas, in the adult rats, chronic stress enhanced full-length and truncated TrkB expressions in the amygdala. In summary, chronic social instability stress hinders amygdala neuron development in the adolescent brain, while mature neurons in the amygdala are capable of adapting to the stress. The stress induced age-dependent effects on the fear-potentiated memory may occur by altering the brain-derived neurotrophic factor (BDNF)-TrkB signaling and neuroplasticity in the amygdala.”
“Hyperthermia can be used as an adjunctive method of chemotherapy,

radiotherapy, and gene therapy to improve cancer treatment. In this study, we investigate the hyperthermic cell death of cervix cancer CaSki cells in a microchannel integrated with a directional heating scheme. Heat was applied from the inner end to the outer end of the channel and a temperature distribution

from 60 degrees C to 30 degrees C was established. A three dimensional (3D) numerical model was conducted for the heat check details transfer simulation, based on which a simple fitting method was proposed to easily estimate the temperature distribution along the channel. Cell death along the channel was mapped 22 h after the heating treatment by dual fluorescent labeling and phase-contrast microscopy imaging. Upstream, where the temperature is higher than 42 degrees C, we observe necrotic death, late-stage and early stage apoptotic death in sequence along the channel. Downstream and in the middle of the channel, where the temperature is lower than 42 degrees C, significant cell detachment was noted. Vigorous detachment was observed even in the non-hyperthermic zone (temperature lower than 37 degrees C), which we believe is due to the direct effect of the hyperthermic zones (higher than 37 degrees C). The present work not only gives a vivid map of cell responses under a temperature gradient, but also reveals the potential interactions of the heated tumor cells and non-heated tumor cells, which are seldom investigated in conventional petri-dish experiments. (C) 2012 American Institute of Physics. [

However, our results did not show any impairment of learning of e

However, our results did not show any impairment of learning of extinction after the administration of alcohol. Behavioural as well as attentional responses indicated extinction of conditioned responses for both experimental groups.

Conclusions: These findings suggest that alcohol at GSI-IX datasheet a dose that impairs performance in a task of inhibitory control does not impair learning of extinction. (C) 2009 Elsevier Ireland Ltd. All rights reserved.”
“Five mutant forms of glucoamylase (GA) from the filamentous fungus Aspergillus awamori with artificial disulfide bonds (4D-G137A\A14C,

6D-A14C\Y419C\G137A, 10D-V13C\G396C, 11D-V13C\G396C\A14C\Y419C\G137A, and 20D-G137A\A246C\A14C) were constructed using molecular modeling simulations and experimentally tested for thermostability. The introduction of two additional disulfide bonds between its first and thirteenth alpha-helices and that of the loop located close to a catalytic residue-E400-made

it possible to assess the effects ON-01910 cell line of disulfide bridges on protein thermostability. The mutant proteins with combined amino acid substitutions G137A\A14C, V13C\G396C\A14C\Y419C\G137A, and G137A\A246C\A14C showed higher thermal stability as compared to the wild-type protein. At the same time, new disulfide bridges in the mutant A14C\Y419C\G137A and V13C\G396C proteins led to the destabilization of their structure and the loss of thermal stability.”
“A series of organic-inorganic hybrid thermosensitive,gels with three different structures were prepared from N-isopropylacrylamide

see more (NIPAAm), and N, N’-methylenebisacrylamide (NMBA) and tetraethoxysilane (TEOS) [N-IPN]; NIPAAm 3-(trimethoxysilyl) propyl methacrylate (TMSPMA) as coupling agent and TEOS [NT-IPN]; and NIPAAm, TMSPMA, and TEOS [NT-semi-IPN] by emulsion polymerization and sol-gel reaction in this study,. The effect of different gel structures and coupling agent oil the swelling behavior, mechanical properties, and morphologies of the present gels was investigated. Results showed that the properties of the gels would be affected by the gel networks such is IPN or semi-IPN and with or without existence of TMSPMA as the bridge chain between networks. The NT-semi-IPN gel had higher swelling ratio and faster diffusion rate because poly(NIPAAm) moiety in the semi-IPN gels was not restricted by NMBA network. However, the IPN gels such as N-IPN and NT-IPN had good mechanical properties and lower swelling ratio, but had a poor thermosensitivity due to the addition of coupling agent, TMSPMA, into the gel system that resulted in denser link between organic and inorganic components. The morphology showed that IPN gels had partial aggregation (siloxane domain) and showed some denser phases. (c) 2008 Wiley Periodicals, Inc.

9%NaCl, injected intraperitoneally at a dosage of 200mg/Kg of bo

9%NaCl, injected intraperitoneally at a dosage. of 200mg/Kg of body weight, twice a week for 12 weeks. The rats were decapitated and blood sample was collected at the end of experimental period and used for liver functions, enzyme activity,

antioxidant enzymes and lipid peroxidation estimations. Genomic DNA was isolated from excised tissue determine the ACE genotypes using specific primers. The ACE gene expression in liver tissue was assessed using the quantitative RTPCR method. The activity of ALT, total and direct bilirubin, SOD and CAT levels were significantly high (p<0.05) and level of MDA was significantly low (p<0.05) in TAA treated rats as compared to control rats. The ACE gene expression after 12 weeks TAA treatment in

learn more cirrhotic rats was significantly increased (p<0.05) in comparison to controls. This study describes the importance find more of RAS in the development of hepatic fibrosis and the benefits of modulation of this system ACE gene expression. The finding of major up-regulation of ACE in the experimental rat liver provides further insight into the complexities of the RAS and its regulation in liver injury. The development of specific modulators of ACE activity and function, in future, will help determine the role of ACE and its genetic variants in the pathophysiology of liver disease.”
“Objective: National arthroplasty registers are often cited as examples of a non-randomized design that have made an essential contribution to advances

in assessing arthroplasty procedures. We aimed to compare national registers to randomized controlled trials (RCTs) and meta-analyses in the field of arthroplasty in terms of scientific production and impact.

Method: We systematically searched Medline via PubMed and the registers’ websites to select all articles from national registers, RCTs and meta-analyses assessing hip and knee arthroplasty. The scientific production and impact were evaluated by number of publications, number of citations (total and the 3-year citation counts), and information click here on the 2008 journal impact factor (IF), for each design and identified articles. We also contacted representatives of all the selected registers to determine the availability of the data for external research projects.

Results: We retrieved information on 13 active national hip or knee arthroplasty registers; for 9, data were available for research projects under specific conditions. Overall, 190 publications in peer-reviewed journals resulted from national arthroplasty registers, 476 from RCTs, and 40 from meta-analyses. We found 4,112 citations for national register reports, 7,328 for RCT reports and 552 for meta-analysis reports. The median [interquartile [IQR] range] number of citations for register, RCT and meta-analysis reports in the 3-year period after publication was 3.5 [1.0-6.0], 2.0 [1.0-6.0], and 2.5 [0.5-7.5], respectively.

The baseline ophthalmological examinations and visual field analy

The baseline ophthalmological examinations and visual field analysis (on automated Humphrey visual field (HVF) 10-2 perimetry, Humphrey

HFA II-i 750 i, Carl Zeiss Meditec AG, Jena, Germany) were completely normal. The sdOCT was performed Belnacasan order with the Optovue technology according to the manufacturer’s guidelines using EMM5, retinal nerve fiber layer (RNFL) and ganglion cell complex (GCC) scans. The retinal thickness values in central foveal, inferior and superior hemispheres, temporal, superior, nasal and inferior para-and perifoveal areas and the RNFL thickness of eyes were compared before and 6 months after starting treatment by the paired t test.

Results: The retinal thickness values in central parafoveal (p = 0.02), and superior hemisphere (p = 0.01) in parafoveal area, parafoveal superior (p = 0.02), temporal (p = 0.03) and nasal (p = 0.04) quadrants were significantly thicker after 6 months of treatment. The thickness of the perifoveal area and the average RNFL thickness was not significantly different in any of the quadrants before and after starting HCQ treatment. The GCC thickness also did not change significantly different in superior and inferior hemisphere after starting treatment.

Discussion and conclusion: We observe increased

retinal thickness in parafoveal areas in patients on HCQ therapy at GSK690693 manufacturer short term. Its clinical significance may be apparent in longer follow up studies.”
“Examination with CT and image registration Etomoxir Metabolism inhibitor is a new technique that we have previously used to assess 3D segmental motions in the lumbar spine in a phantom. Current multi-slice computed tomography (CT) offers highly accurate spatial volume resolution without significant distortion and modern CT scanners makes it possible to reduce the radiation dose to the patients. Our aim was to assess segmental movement in the lumbar spine with the aforementioned method in healthy subjects and also to determine rotation accuracy on phantom vertebrae.

The subjects were

examined in flexion-extension using low dose CT. Eleven healthy, asymptomatic subjects participated in the current study. The subjects were placed on a custom made jig which could provoke the lumbar spine into flexion or extension. CT examination in flexion and extension was performed. The image analysis was performed using a 3D volume fusion tool, registering one of the vertebrae, and then measuring Euler angles and distances in the registered volumes.

The mean 3D facet joint translation at L4-L5 was in the right facet joint 6.1 mm (3.1-8.3), left facet joint 6.9 mm (4.9-9.9), at L5-S1: right facet joint 4.5 mm (1.4-6.9), and for the left facet joint 4.8 mm (2.0-7.7). In subjects the mean angles at the L4-L5 level were: in the sagittal plane 14.3A degrees, coronal plane 0.9A degrees (-0.6 to 2.8), and in the transverse plane 0.6A degrees (-0.4 to 1.5), in the L5-S1 level the rotation was in sagittal plane 10.2A degrees (2.4-16.1), coronal plane 0A degrees (-1.2 to 1.2), and in the transverse plane 0.

We present here the development of mathematical, time-delay model

We present here the development of mathematical, time-delay models for protein translation, based on PDE models, which in turn are derived through systematic approximations of first-principles mechanistic models. Theoretical analysis buy 5-Fluoracil suggests that the key features that determine the time-delays and the agreement between the time-delay and the mechanistic models are ribosome density and distribution, i.e., the number of ribosomes on the mRNA chain relative to their maximum and their distribution along the mRNA chain. Based on

analytical considerations and on computational studies, we show that the steady-state and dynamic responses of the time-delay models are in excellent agreement with the detailed mechanistic models, under physiological conditions that correspond to uniform ribosome distribution and for ribosome density up to 70%. The methodology presented here can be used for the development of reduced time-delay models of mRNA synthesis and large genetic

networks. The good agreement between the time-delay and the mechanistic models will allow us to use the reduced model and advanced computational methods from nonlinear dynamics in order to perform studies that are not practical using the large-scale mechanistic models.”
“Implementation of the linear electro-optic (EO) effect in thin film waveguides is expected to allow drastic reductions in the drive voltage, power, and dimensions of devices devoted to light modulation. It should also enable the realization of electrically tunable photonic crystal devices. In this paper we introduce a method phosphatase inhibitor which eliminates systematically the sources of the unreliability which strongly affects thin film EO characterization.

Based on a Fabry-Perot reflective configuration, the method enables characterizing simultaneously the EO, converse-piezoelectric, and electroabsorptive effects in a film. It provides the magnitude and sign of each of the involved coefficients, and allows accounting for the whole of experimental data versus angle of incidence for both transverse-electric and transverse-magnetic polarizations. At lambda=633 nm and room temperature, the results obtained with an epitaxial strontium barium niobate (SrxBa1-xNb2O6, x=0.60) ferroelectric thin film, are: r(13)=+ 8.5 +/- 1.3 pm/V, r(33)=+38.9 +/- 0.5 pm/V, d(33) =Delta e/Delta V=+21 +/- 4 pm/V, and Delta k(o)/Delta V=(+9.8 +/- 0.6) x 10(-6), where r(13) and r(33) are two linear EO coefficients, d(33) is a converse-piezoelectric coefficient, and e, k(o), V represent, respectively, the film thickness, film ordinary extinction coefficient, and applied voltage. Converse-piezoelectric and electroabsorptive effects are found significant in the film response at a frequency below piezoelectric resonance. Diagonal and effective EO coefficients of the (Sr, Ba)Nb2O6 (SBN) film explored in the present work are larger than those of a crystal of lithium niobate (LN) at the same wavelength lambda=633 nm.

SAS and SUDAAN were used for the statistical analysis

SAS and SUDAAN were used for the statistical analysis.

Results: When utilising the AHA/NHLBI criteria, adults acquiring between 736 and 1,360 MET-minutes per week (MET.min.wk(-1)) of LTPA were found to be 35% (OR 0.65; MLN4924 95% CI 0.48, 0.88) less likely to meet the metabolic syndrome diagnosis criteria compared with those reporting no LTPA. However, protection (OR 0.70; 95% CI 0.51, 0.96) started earlier when utilising the WHO criteria (393-737 MET.min.wk(-1)). Significant inverse associations (OR 034; 95% CI 0.44, 0.66) and (OR 0.61; 95% CI 0.48, 0.77) for WHO and AHA/NHLBI criteria respectively, were also found for the

metabolic syndrome when examining Buparlisib mw LTPA by the current public heath PA recommendation. In addition, the overall age-adjusted prevalence of the metabolic syndrome among U.S. adults was estimated to be 21.9% and 36.3% for the WHO and AHA/NLHBI definitions respectively.

Conclusion: Our findings estimate that

adults engaging in a level of LTPA similar to the current public health recommendation may have a decreased risk of developing the metabolic syndrome. Also, depending on the definition used, between one in three and one in five U.S. adults are estimated to have the metabolic syndrome.”
“SETTING: Gaborone, Botswana.OBJECTIVE: To determine if starting anti-tuberculosis treatment at clinics in Gaborone without co-located human immunodeficiency virus (HIV) clinics would delay time to highly active antiretroviral this website therapy (HAART) initiation and be associated with lower survival compared to

starting anti-tuberculosis treatment at clinics with on-site HIV clinics.DESIGN: Retrospective cohort study. Subjects were HAART-naive, aged 21 years with pulmonary tuberculosis (TB), HIV and CD4 counts 250 cells/mm(3) initiating anti-tuberculosis treatment between 2005 and 2010. Survival at completion of anti-tuberculosis treatment or at 6 months post-treatment initiation and time to HAART after anti-tuberculosis treatment initiation were compared by clinic type.Results: Respectively 259 and 80 patients from clinics without and with on-site HIV facilities qualified for the study. Age, sex, CD4, baseline sputum smears and loss to follow-up rate were similar by clinic type. Mortality did not differ between clinics without or with on-site HIV clinics (20/250, 8.0% vs. 8/79, 10.1%, relative risk 0.79, 95%CI 0.36-1.72), nor did median time to HAART initiation (respectively 63 and 66 days, P = 0.53).conclusion: In urban areas where TB and HIV programs are separate, geographic co-location alone without further integration may not reduce mortality or time to HAART initiation among co-infected patients.”
“Myopericarditis can be caused by a wide range of infectious agents.

(C) 2011 American Institute of Physics [doi:10 1063/1 3660745]“<

(C) 2011 American Institute of Physics. [doi:10.1063/1.3660745]“
“Exposure to an elevated CO2 concentration ([CO2]) generally decreases leaf N CP-456773 cost content per unit area (N-area) and stomatal density, and increases

leaf thickness. Mature leaves can ‘sense’ elevated [CO2] and this regulates stomatal development of expanding leaves (systemic regulation). It is unclear if systemic regulation is involved in determination of leaf thickness and N-area-traits that are significantly correlated with photosynthetic capacity. A cuvette system was used whereby [CO2] around mature leaves was controlled separately from that around expanding leaves. Expanding leaves of poplar (Populus trichocarpaxP. deltoides) seedlings were exposed to elevated [CO2] (720 mu mol mol(-1)) while the remaining mature leaves inside the cuvette were under ambient [CO2] of 360 mu mol mol(-1). Reverse treatments were performed. Exposure of newly developing leaves to elevated [CO2] increased their thickness, but when mature leaves were exposed to elevated [CO2] the increase in thickness of new leaves was less pronounced. The largest response to [CO2] was reflected in the palisade tissue thickness (as opposed to the spongy tissue) of new leaves. The N-area of new leaves was unaffected by the local [CO2] where the new leaves developed, but decreased following the exposure

of mature leaves PRIMA-1MET manufacturer to elevated [CO2]. Selleck Trichostatin A The volume fraction of mesophyll cells compared with total leaf and the mesophyll cell density changed in a manner similar to the response of N-area. These results suggest that N-area is controlled independently of the leaf thickness, and suggest that N-area is under systemic regulation by [CO2] signals from mature leaves that control mesophyll cell division.”
“Takayasu’s arteritis (TA), also known as the “”pulseless disease,”" is a chronic vasculitis of the aorta and aortic branches. TA with Crohn’s disease is rare and has not been documented in China before. In this paper we report on a case of Takayasu’s arteritis associated with concurrent

Crohn’s disease. A 17-year-old Chinese male developed upper limb sourness and a sensation of fatigue, and his upper limb pulses were absent. He was diagnosed with TA and underwent an axillary artery bypass with autologous great saphenous vein on the left subclavian artery. After the surgery, he regained the normal blood pressure. This patient also had years of diarrhea and developed an anal canal ulcer, and was diagnosed with inflammatory bowel disease and ulcerative colitis before. Five months after the TA surgery, he was hospitalized for severe stomachache and diarrhea and was finally diagnosed with Crohn’s disease. The possible pathophysiological mechanisms responsible for concurrent existence of TA and Crohn’s disease may be associated with immune disorders, especially autoimmunity.

The maximum values of I-131/Cs-134 activity ratio corresponding t

The maximum values of I-131/Cs-134 activity ratio corresponding to thyroid uptake factors of 0.3, 0.1 and 0.03 were evaluated to be 0.9, 2.6 and 8.7, respectively. The maximum value of the I-131/Cs-134 activity ratio was used to obtain the

most conservative thyroid equivalent dose estimation. The maximum internal exposure of the thyroid to (131I) on the basis of Cs-134 accumulated in the body measured by the whole body counter was estimated to be 18 mSv. This value was much smaller than 50 mSv that selleck screening library the International Atomic Energy Agency recommends as the dose at which exposed persons should take stable iodine tablets. (C) 2013 Elsevier Ltd. All rights reserved.”
“Historically, surgical competence has been evaluated subjectively. Fundamental changes in surgical technology and training have focused attention on the use of objective measurement of performance to improve patient safety Nepicastat supplier and reduce errors. Surgical performance can be measured using a variety of tools, both in the clinical and simulated environments. Objective assessments can play a role in training by improving the evaluation and feedback. At the end of training or when a new skill is acquired, objective assessments may be used to ensure that a proficiency level has been reached and potentially as a condition for independent practice. When assessments are used for

high-stakes evaluations like certification, they must be demonstrably reliable and valid. The definition of HDAC inhibitor assessment, and the necessary components of a valid instrument, will be summarized. An overview of practical applications of objective assessment as it applies to training, selection,

and certification of surgeons will be presented. (C) 2010 Published by Elsevier Ltd.”
“We experimentally investigate the isothermal amorphous-to-fcc polycrystalline phase transition process in amorphous Ge2Sb2Te5 thin films prepared by sputtering. The amorphous layers were either as deposited or formed by Ar+ ion implantation after crystallization at 300 degrees C. The kinetics of the amorphous-to-polycrystal transition are analyzed through electrical measurements, in which the Johnson-Mehl-Avrami-Kolmogorov theory is employed. The procedure to extract the kinetics of the phase transition from conductivity versus time data is carefully discussed and compared to data of cross-sectional transmission electron microscopy images versus anneal time. By following this proposed procedure, the nucleation and growth parameters, and the activation energies have been determined. Results indicate that the process of isothermal crystallization in Ge2Sb2Te5 takes place in two stages, in which the Avrami exponent changes in the range from 3 to 1. These results are understood in terms of modifications in the kinetics of the phase transition.