bluuebunny/crossref_metadata_2025 huggingface dataset:
Stress in hospice at home nurses:a qualitative study
Authors: Tunnah Karen , Johnstone Ros , Jones Angela
Published: March 2012

This baseline study aims to explore Hospice at Home nurse's experiences and well-being while caring for palliative and dying patients. The study will utilise a qualitative method to collect data with the purpose of understanding the Hospice at Home nurse's experience of work and the stressors encountered. The nurses will be interviewed using semistructured interviews, and the data will be analysed and categorised into themes using a grounded theory methodology. The participants will be a purposive sample of trained Hospice at Home nurses who spend the majority of the day providing direct hands on care to patients and their families in the community. Studies suggest that factors to promote resilience and well-being, in hospice nurses can be developed through staff training packages to help prevent burnout. The literature evaluates studies of hospice nurses and stress levels when working in a hospice but very few studies focus on community hospice nurses who are often working alone without the support of a collegiate team in close proximity. This study aims to provide valuable additional data to this little-researched area. The study will report early in 2012 and will inform Hospice At Home nursing teams as to whether coping strategy training would be beneficial for the well-being of the staff, which in turn could result in preventing absence due to sickness, promote staff retention and contribute towards team building.
What shapes and influences preferred place of care at end of life?
Authors: Naismith Jane , Dunn Virginia , Pegrum Helen
Published: March 2012

Research shows that over half the population would like to die at home, however only 20% achieve this.(1) This affects the quality of end of life care and bereavement outcomes. Numerous studies have examined place of death and its' predictors, however there is little published information about the factors that shape and influence the decisions patients make about their preferred place of care (PPC) at the end of life, or about which factors that influence and change these decisions over time.

Aims

To identify the factors, from the individual's perspective, that influence and change preferences for PPC.

Design/results

A descriptive explorative qualitative longitudinal study was undertaken with ethical approval. Four participants were recruited; all were female, aged 55–81 years. All participants had chosen a PPC, however they all wanted to remain at home for as long as possible. Only one achieved their PPC. Factors that influenced choice of PPC were

Becoming ill and realising that they were dying.

A desire to remain autonomous and to retain a sense of dignity and control.

Previous experiences of a location.

Care at home being intrusive.

Not wanting to burden family with care.

The need NOT to compromise close relationships.

Discussion

Participants found discussion of PPC difficult made and assumptions for their carers. They had had little or no information about choice of PPC and none had recorded it in writing. There is a complex interplay of emotional and practical factors that influence PPC. Clear decisions about PPC were not made until dying was imminent. PPC should be viewed as a dynamic decision requiring regular reassessment. This research also demonstrated the difficulty of recruiting participants due to it being considered over burdensome by both patients and healthcare professionals, who adopted a gate-keeping role.
Using consensus methodology to identify events that could trigger holistic assessment in severe COPD
Authors: Cawley Declan , Oliver David , Billings Jenny , Kendall Marilyn , Pinnock Hilary
Published: March 2012

Background

Current policy demands that ‘quality’ end of life care should be universally available irrespective of illness but evidence on how this should be done in non-malignant disease lacking. The ‘lack of biographical disruption’ and uncertainty of the COPD disease trajectory makes this difficult within a service model predicated on identifying ‘transitions’ to palliative care. Therefore the authors require an approach that will capture the ‘needs’ of individuals with severe COPD and their carers, irrespective of which professional arena they come into contact with.

Aims

To identify ‘events’ within the life-long disease trajectory of COPD, that can trigger an assessment of the holistic (supportive and palliative care) needs of patients with severe disease and their carers.

Method

1. Secondary analysis of transcripts from the ‘Breath of Fresh Air’ study (Pinnocket al.,BMJ2011; 342: d142) to identify candidate ‘events’ for consideration as triggers. 2. Consensus meeting of health and social care professionals to characterise a ‘trigger’ and prioritise candidate ‘events’ using a nominal group technique.

Results

Eight candidate ‘events’ were identified: requesting a ‘Blue badge`, home adaptations, hospital admissions, increasing burden of disease, housebound, failure to attend an appointment, shifting priorities of care, increasing carer burden. The consensus meeting affirmed that a successful ‘trigger’ should be visible to patient/carer/health or social care professional, meaningful to all stakeholders involved, actionable (i.e amenable to an intervention). The candidate ‘events’ that reached consensus (>75% agreement) were requesting home adaptations, hospital admissions and being housebound.

Conclusion

The multi-disciplinary group agreed the key characteristics required for an effective ‘triggers’, and prioritised three candidate events. These need to be explored with COPD patients and their carers, to understand their acceptability, attributability, reliability, feasibility and relevance of triggers in delivering quality care for people with severe COPD and carers.
What is the impact of training nurses in resuscitation decisions in advanced illness?
Authors: Faull Christina
Published: March 2012

Background

The East Midlands DNA-CPR form may be completed by a ‘suitably experienced nurse’. The BMA and RCN statement (2007) indicated that nurses may make such decisions, but ambiguity about training and governance remains. Senior community nurses, with previous advanced communication skills training, attended training using the e-ELCA Discussing ‘do not attempt CPR’ decisions. Subsequently nurses could take on the role of signing DNA-CPR forms if agreed by their employer.

Aims

To evaluate the impact of the training on practice and confidence. Methods: A questionnaire was sent 4 months after training and analysed descriptively.

Results

13 of 36 questionnaires were returned. Those with patients on the LCP now completed the DNA-CPR form unless there were difficult dynamics. All completed it for any patient requesting DNA-CPR and 77% completed it with some patients for whom there was no chance of success from CPR. Where such patients or relatives were not in agreement the nurse sought involvement of a doctor. All nurses felt more confident to discuss the topic of CPR and much more confident in discussing a DNA-CPR decision for a dying patient (‘informing’ not ‘asking’), and in dealing with the reactions. Only one nurse reported more difficulties, arising with GPs who were less confident. None of the nurses had had their signature queried by a colleague or relative and many GPs were appreciative of this role. Only two nurses wanted formal assessment of their competence. Some considered assessment to add value if it enhanced the confidence of others in them. 55% wanted on-going CPD, considering this more likely than assessment to quality assure their practice.

Conclusions

The training increased confidence and has changed patient care. Senior nurses appear to assess the risk of their decision making role well and act appropriately. The role appears to have been well accepted.
Exploring issues for doctors surrounding the withdrawal of NIV at the request of patients with MND
Authors: Rowe-Haynes Cassy , Faull Christina , Oliver David
Published: March 2012

Background

NICE guidance recommends that non-invasive ventilation (NIV) should be considered for patients with motor neuron disease (MND). The guidelines acknowledge further research is needed on NIV withdrawal. There is little evidence focusing on the issues doctors face when withdrawing NIV in this group.

Aims

To identify issues and challenges doctors have encountered when withdrawing NIV in MND patients.

Methods

An electronic questionnaire was sent to 1000 members of the Association of Palliative Medicine. Participants rated how practically, emotionally and ethically challenging they found the process of NIV withdrawal. They were invited to expand on issues using free text.

Results

134 responded – 95% were doctors working in various settings, 62% were consultants. 60% had been directly involved in withdrawal of NIV in MND patients. Only 5% used a protocol or guideline. Most found the process of NIV withdrawal practically, emotionally and ethically challenging. The percentage scoring 5 or more on a likert scale (10 =very challenging) were 70% for practically challenging, 75% for emotionally challenging and 60% for ethically challenging. 12% found NIV very emotionally challenging scoring 10 on the scale. Thematic analysis of the free text revealed some common difficulties. Lack of guidance on practical aspects of withdrawal, poor advance care planning and the need to support all involved to prevent conflict were recurrent themes. Statements relating to the emotional burden were diverse but suggest a significant personal impact is felt by many palliative care doctors.

Conclusions

The withdrawal of NIV in patients with MND appears to pose multiple challenges to palliative care doctors involved. Development of guidelines and a clear ethical statement of conduct may help with some of the practical and ethical challenges. Emotional issues appear more complex. Further research into the challenges faced by all professionals in the withdrawal of NIV is necessary.
Adverse reactions to metal debris: histopathological features of periprosthetic soft tissue reactions seen in association with failed metal on metal hip arthroplasties
Authors: Natu Sonali , Sidaginamale Raghavendra Prasad , Gandhi Jamshid , Langton David J , Nargol Antoni V F
Published: March 2012

Aim

To describe the histopathology of localised adverse reactions to metal debris (ARMD) seen in association with failed metal on metal (MoM) hip arthroplasties. The nature of aseptic lymphocytic vasculitis associated lesion (ALVAL) is investigated.

Methods

Periprosthetic soft tissues biopsied at time of revision from failed MoM hip arthroplasties from January 2007 to March 2011 were analysed. The inflammatory cell response was categorised into perivascular lymphocytic cuffing (ALVAL), lymphoid aggregate formation with or without germinal centres, metallosis characterised by sheets of macrophages with intracytoplasmic metallic debris and well-defined granulomas.

Results

123 patient samples were analysed, 36 males (29.2%) and 87 females (70.8%). Three cases showing complete tissue necrosis were excluded. Patients were reviewed between 3.27 to 69.6 months postarthroplasty, with an average of 30.92 months. 103 cases (85.8%) showed ALVAL, 18 cases also showed well-defined granulomas. Of the 103 cases with ALVAL, 60 cases also showed a diffuse chronic lymphocytic synovitis, and 40 cases showed lymphoid aggregates with germinal centres. 17 cases (14.2%) showed pure metallosis. Small vessels showing ALVAL expressed peripheral node addressin.

Conclusions

ARMD is a spectrum of changes comprising of pure metallosis, ALVAL and granulomatous inflammation. ALVAL, a distinctive inflammatory response seen in ARMD, is a precursor of lymphoid neogenesis. Lymphoid neogenesis documented in a variety of chronic inflammatory conditions most probably contributes to tissue necrosis and prosthetic failure seen in MoM hip arthroplasties. The role of vascular changes in contributing to necrosis is unclear at this stage.
Prognostic significance of FOXP1 as an oncogene in hepatocellular carcinoma
Authors: Zhang Yixin , Zhang Suqin , Wang Xudong , Liu Jibin , Yang Liping , He Song , Chen Li , Huang Jianfei
Published: March 2012

Background

Forkhead Box P1 (FOXP1) has been described as both a tumour suppressor candidate and a potential oncogene. The aim of this study is to identify new prognostic biomarkers and therapeutic target structures for the diagnosis and treatment of hepatocellular carcinoma (HCC).

Methods

The expression of FOXP1 mRNA in HCC was characterised using real-time PCR and 20 pairs of fresh frozen HCC tissues and corresponding non-cancerous tissues. FOXP1 protein expression in HCC was confirmed using immunohistochemistry on a tissue microarray chip. Finally, FOXP1 expression was correlated with conventional clinicopathological features of HCC and patient outcome.

Results

The expression of FOXP1 mRNA and protein in HCC cells was much higher than in normal hepatic cells (Z=2.315, p=0.021 and χ2=28.071, 95% CI 0.233 to 0.480, p<0.001, individually). The comparison of clinicopathological characteristics and immunohistochemistry by χ2test analysis showed that the high expression of FOXP1 in HCC was related to large tumour diameter (χ2=6.210, p=0.013), high serum α-fetoprotein levels (χ2=6.920, p=0.031) and later stage grouping with tumour node metastasis classification (χ2=6.714, p=0.035). Kaplan–Meier survival and Cox regression analysis showed that high FOXP1 expression (HR=2.182, 95% CI 1.146 to 4.154, p=0.018) and regional lymph node metastasis (HR=2.326, 95% CI 1.037 to 5.217, p=0.041) were independent prognosis factors.

Conclusions

From this investigation the authors elucidated for the first time that the correlation of high FOXP1 expression correlates with an aggressive malignant phenotype and may constitute a novel prognostic factor for HCC. These results also support a role for FOXP1 as an oncogene in HCC.
Contemporaneous eruption of Nb-enriched basalts – K-adakites – Na-adakites from the 2.7 Ga Penakacherla terrane: implications for subduction zone processes and crustal growth in the eastern Dharwar craton, India
Authors: Kerrich Robert , Manikyamba Chakravadhanula
Published: March 2012

An association of Nb-enriched basalts (NEB), high-MgO andesites (HMA), and flows with adakitic characteristics are interlayered with tholeiitic pillow basalts in the 2.7 Ga Penakacherla greenstone belt of eastern Dharwar craton. Two populations of basalt are present, a high-Mg# Ni (0.65–0.56, 106–52 ppm) and low-Mg# Ni (0.45–0.34, 32–13 ppm) counterpart; Nb spans 6.3–18 ppm relative to “normal” arc tholeiitic basalts, where Nb ∼3 ppm, and hence qualify as NEB. Basalts plot on the low-Ce/Yb trend of intraoceanic arcs, and have fractionated heavy rare-earth elements (HREE) indicative of melting with residual garnet at >90 km. Ratios of Nb/Ta (7.6 ± 0.7), Zr/Hf (44 ± 0.8), and Zr/Sm (27 ± 2.4) are systematically low, high, and similar to respective primitive mantle ratios of 17, 36, and 25, consistent with a mid-ocean ridge basalt-like mantle source in the sub-arc mantle wedge. Intermediate compositions are divided into high-K but low-Na (K2O 1.8–5.3; Na2O 0.5–2.1 wt.%) and low-K but high-Na (K2O 0.10–1.5; Na2O 4.1–5.6 wt.%) populations defining distinct magma series; accordingly, these are termed K-adakitic and Na-adakitic rocks, respectively. The Na-type has SiO2 ≥56 wt.%, MgO <3 wt.%, Mg# ∼0.5, Na2O ≥3.5 wt.%, K2O ≤3 wt.%, Yb ≤1.9 ppm, Cr ≥30 ppm, with slightly lower limits of Al2O3 ≥15 wt.% and La/Yb 7.5–8.2 versus ≥20, thus conforming to most criteria for Na-adakites. NEB are interpreted as melts of mantle wedge hybridized by adakitic melts having residual garnet; and Na-adakites are slab melts of low-Mg basalt in the garnet–amphibolite facies. K-adakitic flows are melts of mafic lower crust, or melts of lower crust delaminated into mantle wedge asthenosphere.
ANALYSIS OF CRITICAL MASS IN THRESHOLD MODEL OF DIFFUSION
Authors: KIM JEEHONG , HUR WONCHANG , KANG SUK-HO
Published: March 2012

Why does diffusion sometimes show cascade phenomena but at other times is impeded? In addressing this question, we considered a threshold model of diffusion, focusing on the formation of a critical mass, which enables diffusion to be self-sustaining. Performing an agent-based simulation, we found that the diffusion model produces only two outcomes: Almost perfect adoption or relatively few adoptions. In order to explain the difference, we considered the various properties of network structures and found that the manner in which thresholds are arrayed over a network is the most critical factor determining the size of a cascade. On the basis of the results, we derived a threshold arrangement method effective for generation of a critical mass and calculated the size required for perfect adoption.
STUDY OF NÉEL TEMPERATURE AND MULTIPLE PHASE COEXISTENCE IN Bi0.5Ca0.5-xBaxMnO3 (x = 0–0.10)
Authors: LI RENWEN , PI LI , TONG WEI , ZHANG LEI , LING LANGSHENG , ZHANG YUHENG
Published: March 2012

Structural and magnetic properties of Bi0.5 Ca0.5-xBaxMnO3 (x = 0, 0.03, 0.05, 0.07 and 0.10) samples with charge ordering (CO) state and C-type antiferromagnetic (AFM) magnetic structure have been studied systematically. With increasing Ba-doping level, both CO and AFM are weakened. From the micro-magnetic analysis, we clarify the ambiguity about the Néel temperature TN in bismuth-based perovskite manganites. We find that the paramagnetic (PM)-CO/AFM transition temperature TCO at high temperature is the onset temperature of the PM–AFM transition, while customarily so-called TN at low temperature indicates the finish of the PM–AFM transition. Both the macro- and micro-magnetic data show that, in all the samples, only AFM state coexists with PM matrix below CO transition and above TN, while AFM state coexists with ferromagnetic (FM) state and PM state at lower temperature below TN.
HOW FAR DO WE GET USING MACHINE LEARNING BLACK-BOXES?
Authors: ROCHA ANDERSON , PAPA JOÃO PAULO , MEIRA LUIS A. A.
Published: March 2012

With several good research groups actively working in machine learning (ML) approaches, we have now the concept of self-containing machine learning solutions that oftentimes work out-of-the-box leading to the concept of ML black-boxes. Although it is important to have such black-boxes helping researchers to deal with several problems nowadays, it comes with an inherent problem increasingly more evident: we have observed that researchers and students are progressively relying on ML black-boxes and, usually, achieving results without knowing the machinery of the classifiers. In this regard, this paper discusses the use of machine learning black-boxes and poses the question of how far we can get using these out-of-the-box solutions instead of going deeper into the machinery of the classifiers. The paper focuses on three aspects of classifiers: (1) the way they compare examples in the feature space; (2) the impact of using features with variable dimensionality; and (3) the impact of using binary classifiers to solve a multi-class problem. We show how knowledge about the classifier's machinery can improve the results way beyond out-of-the-box machine learning solutions.
FRACTIONAL ORDER SPECTRA AND THEIR APPLICATION IN THE THEORY OF VISCOELASTICITY
Authors: HU KAI-XIN , ZHU KE-QIN
Published: March 2012

Some experiments show fractional models can represent the mechanical properties of some materials appropriately, but the way to determine the parameters of the fractional models need further discussion. In this paper, fractional order spectra are presented for complex viscoelastic materials, which mechanical analogy are made by fractional elements connected in series or parallel. Fractional order spectra link the material's constitutive relation and the fractional derivatives closely and reflect the characteristic of networks of mechanical analogy. They provide an effective method to determine the parameters of some fractional models. The experimental method to measure fractional order spectra of complex viscoelastic materials is shown.
ON THE OPTIMAL POLYNOMIAL APPROXIMATION OF STOCHASTIC PDES BY GALERKIN AND COLLOCATION METHODS
Authors: BECK JOAKIM , TEMPONE RAUL , NOBILE FABIO , TAMELLINI LORENZO
Published: March 2012

In this work we focus on the numerical approximation of the solution u of a linear elliptic PDE with stochastic coefficients. The problem is rewritten as a parametric PDE and the functional dependence of the solution on the parameters is approximated by multivariate polynomials. We first consider the stochastic Galerkin method, and rely on sharp estimates for the decay of the Fourier coefficients of the spectral expansion of u on an orthogonal polynomial basis to build a sequence of polynomial subspaces that features better convergence properties, in terms of error versus number of degrees of freedom, than standard choices such as Total Degree or Tensor Product subspaces.

We consider then the Stochastic Collocation method, and use the previous estimates to introduce a new class of Sparse Grids, based on the idea of selecting a priori the most profitable hierarchical surpluses, that, again, features better convergence properties compared to standard Smolyak or tensor product grids. Numerical results show the effectiveness of the newly introduced polynomial spaces and sparse grids.
ON THE DOI MODEL FOR THE SUSPENSIONS OF ROD-LIKE MOLECULES IN COMPRESSIBLE FLUIDS
Authors: BAE HANTAEK , TRIVISA KONSTANTINA
Published: March 2012

Polymeric fluids arise in many practical applications in biotechnology, medicine, chemistry, industrial processes, and atmospheric sciences. In this paper, the Doi model for the suspensions of rod-like molecules in a compressible fluid is investigated. The model under consideration describes the interaction between the orientation of rod-like polymer molecules on the microscopic scale and the macroscopic properties of the fluid in which these molecules are contained. Prescribing arbitrarily the initial density of the fluid, the initial velocity, and the initial orientation distribution in suitable spaces, we establish the global-in-time existence of a weak solution to our model defined on a bounded domain in the three-dimensional space. The proof relies on the construction of an approximate sequence of solutions by introducing appropriate regularization and the establishment of compactness.
EVOLUTIONARY GAME THEORETICAL MODEL OF THE EVOLUTION OF THE CONCEPT OF HUE, A HUE STRUCTURE, AND COLOR CATEGORIZATION IN NOVICE AND STABLE LEARNERS
Authors: STEINGRIMSSON RAGNAR
Published: March 2012

Evolutionary game theory is used to form a finite partition of a continuous hue circle in which perceptually similar hues are each represented by an icon chip and the circle by a finite but game dynamically determined number of icon chips. On the basis of such icon chip structures, a color categorization for both an individual learner and a population of learners is then evolved. These results remove limitations of some particular previous color categorization simulation work which assumed a fixed number of color stimuli and a maximal number of predefined color categories. These simulations are extended to demonstrate that learners need neither to share the same icon chip structures, nor do these structures have to be fully developed for a population of learners to produce a stable color categorization system. Additionally, when a naïve learner is introduced into a population with a stable color categorization, the game dynamics result in the learner's adopting the existing categorization. All results are shown to hold while the underlying icon chip structures evolve continuously in response to novel stimuli. The usefulness of the approach as well as some of the potential implications of the results for human learning of color categories are discussed.
MICROSTRUCTURAL AND MECHANICAL CHARACTERIZATION OF CONSOLIDATED NANO- AND MICRON- SIZE Cu POWDERS
Authors: SALEH A. , HESHMATI-MANESH S. , ATAIE A. , SHEIBANI S.
Published: March 2012

In this paper, nano-crystalline Cu powder with a mean crystallite size of 45 nm and commercial micron-size Cu powder were either hot pressed or cold pressed and sintered conventionally to fabricate bulk samples. Hardness, density, crystallite size and microstructure of the samples after consolidation were examined. The results show that the hardness of the hot pressed nano-crystalline Cu is in the range of 0.75-1.2 GPa which is higher than that of commercial Cu . The density of the bulk nano-crystalline sample showed that the rising sintering temperature increases the density up to 97% of the theoretical value. The mean crystallite size of the hot pressed sample was 64 nm, which still was in the nano scale. The scanning electron microscopy (SEM) images revealed that the hot pressed samples contain less porosities compared to the conventionally consolidated samples.
EFFECT OF LASER WAVELENGTH AND ABLATION TIME ON PULSED LASER ABLATION SYNTHESIS OF AL NANOPARTICLES IN ETHANOL
Authors: BALADI A. , MAMOORY R. SARRAF
Published: March 2012

Aluminum nanoparticles were synthesized by pulsed laser ablation of Al targets in ethanol for 5-15 minutes using the 1064 and 533 nm wavelengths of a Nd:YAG laser with energies of 280-320 mJ per pulse. It has been found that higher wavelength leads to significantly higher ablation efficiency, and finer spherical nanoparticles are also synthesized. Besides, it was obvious that higher ablation time resulted in higher ablated mass, while lower ablation rate was observed. Finer nanoparticles, moreover, are synthesized in higher ablation times.
OPTICAL PROPERTIES OF SYNTHESIZED NANOPARTICLES ZnS USING METHACRYLIC ACID AS THE CAPPING AGENT
Authors: Nazerdeylami Somayeh , Saievar_Iranizad Esmaiel , Molaei Mehdi
Published: March 2012

Optical analysis (UV-vis spectroscopy) of solution of ZnS nanoparticles prepared at room temperature by a chemical capping method using methacrylic acid ( MAA ) capping agent at concentration of 0.05, 0.2, 0.5 and 1.17 molar is investigated. The spectroscopy results indicate increasing of band gap of ZnS through increasing concentration of the methacrylic acid as capping agent in the solution. According to the relation of Effective Mass Approximation, it is concluded that the size of nanoparticles decreased with the increasing concentration of the capping agent in the tested solutions. The size of the particles is found to be in 1.77-2.05 nm range.
CONTROL OF PARTICLE SIZE AND MORPHOLOGY OF COBALT-FERRITE NANOPARTICLES BY SALT-MATRIX DURING ANNEALING
Authors: AZIZI A. , SADRNEZHAAD S.K. , MOSTAFAVI M.
Published: March 2012

Salt-matrix annealing of mechanically alloyed Co -ferrite nanopowder was used to modify its particle size and morphology. Efficiency improvement due to suppression of sintering and growth resulted in reduction of average particle size from ~100nm for salt-less to ~40nm for salt-full annealing procedure. Nanosized single-phase cobalt-ferrite particles were observed after 2h annealing at 750°C in the samples milled for 20 hours both with and without NaCl . NaCl:CoFe 2 O 4 ratio of 10:1 resulted in cabbage-like clusters containing particles smaller than ~50 nm.
INFLUENCE OF B4C TO TTIP MOLAR RATIO ON SYNTHESIS OF NANO TITANIUM DIBORIDE POWDERS VIA SOL-GEL METHOD
Authors: SINAEI POUR FARD HAMED , BAHARVANDI HAMIDREZA , ABDIZADEH HOSSEIN
Published: March 2012

Titanium diboride ( TiB 2) has attracted great interests for its excellent mechanical properties, chemical resistance and good thermal and electrical conductivities. So it is widely applied as cutting tool composites, wear resistant parts, metal melting crucibles and electrode materials. This paper presents synthesis of nano titanium diboride powders via sol-gel method using a mixture of TTIP and B 4 C as precursors. In the hydrolysis step, B 4 C to TTIP molar ratio varied from 1.3 to 2.5. Solution samples stirred well and after aging and drying process, they were heat treated in an argon atmosphere. X-ray diffraction (XRD) patterns and Scanning electron microscopy (SEM) analysis showed that the percentage of synthesized TiB 2 increased gradually as the molar ratio of B 4 C to TTIP reached to 2.3, afterward increasing the B 4 C to TTIP molar ratio caused decreasing of titanium diboride percentage.
THE EFFECT OF OPERATING CONDITIONS ON THE SPARK GENERATED AU-PD NANOPARTICLES
Authors: Tabrizi N. S. , Schmidt-Ott A.
Published: March 2012

Spark discharge is a technique for producing nanoparticles from conductive materials. We had previously used this method to produce Au - Pd bimetallic nanoparticles with a mean diameter of around 6 nm. In this study we changed the operating parameters (e.g. spark energy and frequency, carrier gas type and flow rate) and analyzed the generated particles for their structures and compositions. X ray diffraction (XRD) patterns showed evidence of the formation of alloy phase in all the samples. Compositional analysis by Inductively Coupled Plasma (ICP) revealed that the average mixing ratio was influenced by the polarity, the spark frequency and the gap distance between anode and cathode.
THE PROPERTIES OF BULK ULTRAFINE-GRAINED METALS PROCESSED THROUGH THE APPLICATION OF SEVERE PLASTIC DEFORMATION
Authors: LANGDON TERENCE G.
Published: March 2012

Processing through the application of severe plastic deformation (SPD) provides a very attractive tool for the production of bulk ultrafine-grained materials. These materials typically have grain sizes in the submicrometer or nanometer ranges and they exhibit high strength at ambient temperature and, if the ultrafine grains are reasonably stable at elevated temperatures, they have a potential for use in superplastic forming operations. Several procedures are now available for applying SPD to metal samples but the most promising are Equal-Channel Angular Pressing (ECAP) and High-Pressure Torsion (HPT). This paper examines the basic principles of ECAP and HPT and describes some of the properties that may be achieved using these processing techniques.
FABRICATION OF NANOSTRUCTURED TUBE BY A NOVEL SPD PROCESS: ACCUMULATIVE SPIN-BONDING (ASB)
Authors: MOHEBBI M. S. , AKBARZADEH A.
Published: March 2012

A novel SPD process for manufacturing high strength tubes and cylinders titled as accumulative spin-bonding (ASB) is proposed. This process is applied to a commercially pure aluminum up to four cycles and its effects on the microstructure and mechanical properties are examined by optical microscopy, TEM, microhardness and tension tests. The results show that ultra-fine grains are developed during the process leading to a nanostructure with average grain size in order of 150 nm. Mechanical properties indicate that while the hardness of outer layers is more than inner ones, the hardness and its homogeneity is increased by increasing the ASB cycles. As a result of grain refinement and the scheme of hardness development, the yield and tensile strength of material are increased significantly up to the values of 194 and 235 MPa, respectively.
COMPARISON OF FRACTURE BEHAVIOR OF SHARP WITH BLUNT CRACK TIP IN NANOCRYSTALLINE MATERIALS BY MOLECULAR DYNAMICS SIMULATION
Authors: KATEB MOVAFFAQ , DEHGHANI KAMRAN
Published: March 2012

Molecular Dynamics (MD) simulation was used to figure out the fracture behaviors of nanocrystalline materials (NCM). The simulation was based on more than 13 thousand atoms considered for two systems with sharp and blunt crack tip in NCM. Their atomic level resolution provides novel insights into the fracture behavior of NCM. The results show semi brittle manner for both sharp and blunt tips. Dislocation nucleation and pile up at grain boundary (GB), lead to forming voids at GB. Merging mechanism of voids ahead of crack tip causes crack growth.
FABRICATION AND CHARACTERIZATION OF NANOSTRUCTURED CU-15WT.% MO COMPOUND BY MECHANICAL ALLOYING
Authors: Sabooni Soheil , Mousavi Tayebeh , Karimzadeh Fathallah
Published: March 2012

In the present study nanostructured Cu ( Mo ) compound with 15 weight percent Mo was produced by mechanical alloying using a planetary ball mill. The milling operation was carried out in hardened chromium steel vial and balls under argon atmosphere with a constant ball to powder ratio of 10:1. The structural evolution and characterization of powder particles after different milling times were studied by X-Ray Diffraction, SEM observation and Microhardness measurements. The results showed the displacement of broadened Cu peaks to lower angles, because of dissolving Mo in Cu . The final product was a nanocomposite contains nanocrystalline Cu ( Mo ) supersaturated solid solution matrix and dispersion of nanometric Mo reinforcements. The microhardness of formed nanocomposite increased to 350HV because of grain refinement, formation of solid solution and dispersion hardening.
The investigation of the microstructure and mechanical properties of ordered alominide-iron (boron) nanostructures produced by mechanical alloying and sintering
Authors: Izadi S. , Akbari Gh. , Janghorban K. , Ghaffari M.
Published: March 2012

In this study, mechanical alloying (MA) of Fe -50 Al , Fe -49.5 Al -1 B , and Fe -47.5 Al -5 B (at.%) alloy powders and mechanical properties of sintered products of the as-milled powders were investigated. X-ray diffraction (XRD) results showed the addition of B caused more crystallite refinement compared to the B -free powders. To consider the sintering and ordering behaviors of the parts produced from cold compaction of the powders milled for 80 h, sintering was conducted at various temperatures. It was found that the sintering temperature has no meaningful effect on the long-range order parameter. The transformation of the disordered solid solution developed by MA to ordered Fe - Al - ( B ) intermetallics was a consequence of sintering. Also, the nano-scale structure of the samples was retained even after sintering. The microhardness of pore-free zones of the nanostructured specimens decreased by increasing the sintering temperature. Moreover, the sintering temperature has no effect on the compressive yield stress. However, the fracture strain increased by increasing the sintering temperature. The samples containing 1 at.% B showed more strain to fracture compared with the B -free and 5 at.% B samples.
EVALUATION OF HYDROXYAPATITE-FORSTERITE-BIOACTIVE GLASS COMPOSITE NANOPOWDER PREPARED VIA SOL-GEL METHOD
Authors: MAZROOEI SEBDANI MARYAM , FATHI MOHAMMADHOSSEIN
Published: March 2012

In spite of attractive bioactivity of bioactive ceramics i.e. hydroxyapatite and bioactive glasses, their poor mechanical properties have restricted their clinical applications. To overcome these limitations, an alternative approach suggested is preparation a composite including these bioactive ceramics with others. It is expected that a ceramic reinforcement with reduced grain size below 100 nm promotes theirs. The aim of this work was fabrication and characterization of hydroxyapatite-forsterite-bioglass composite nanopowder. Novel hydroxyapatite-forsterite-bioglass composite nanopowder was synthesized by incorporation of the forsterite and bioactive glass in hydroxyapatite matrix via a sol-gel process. X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM) and fourier transform infrared (FTIR) spectroscopy techniques were utilized in order to evaluate the phase composition, agglomerates size distribution, morphology and particle size and functional groups of synthesized. The effects of sintering temperature and time were also investigated. Results showed that the appropriate temperature for calcination was 600°C and the particle size of composite nanopowder was about 60-70nm. The decomposition of hydroxyapatite was increased with the increase of the sintering temperature and sintering time. Obtained results indicate that prepared composite nanopowder could be a good candidate for medical applications.
ELECTROSPINNING OF CONTINUOUS CARBON NAONOFIBER-FILLED COMPOSITE FIBERS
Authors: Aboutalebi Seyed Hamed , Gholamvand Zahra , Keyanpour-Rad Mansoor
Published: March 2012

In order to translate the superior properties of carbon nanofibers (CNFs) to macro-scale structures, an electrospinning route capable of placing CNFs into a continuous nano-scale composite fibril is introduced. In this work, composite fibers were produced by electrospinning solution of polyacrylonitrile ( PAN ) with carbon nanofibers dispersed in dimethylformamide ( DMF ), which is an effective solvent for carbon nanofibers. Atomic force microscopy (AFM) and scanning electron microscopy (SEM) demonstrated rough and globular surfaces on the CNF containing fibers. Raman spectra confirmed the presence of CNFs in the polymer fibers prepared employing the electrospinning method. Raman observation served as the direct evidence of successful filling of PAN fibers with CNFs and complemented the results obtained by SEM and AFM studies.
EFFECT OF REINFORCEMENT CONTENT AND CONSOLIDATION PROCEDURES ON PROPERTIES OF ALUMINUM–BORON CARBIDE NANO-COMPOSITES
Authors: KHAKBIZ MEHRDAD , HADIAN ALI MOHAMAD , AKHLAGHI FARSHAD
Published: March 2012

Gas atomized Al (6061) powder particles were used to synthesize nano-structured Al based composite powders reinforced with 2 and 5wt.% of nano and micro sized boron carbide particles by mechanical alloying. These composite powders as well as the un-reinforced Al powders were compacted by cold uniaxial pressing. In order to investigate the effect of consolidation procedures on the properties of the resultant Al - B 4 C composites, a number of the samples were subjected to sintering at 620 °C for 2h while the others were hot extruded at 520 °C with the extrusion ratio of 8:1. The effect of percentage and size of B 4 C on the density, hardness and mechanical properties (such as yield strength, compression strength) of the composites were evaluated and compared with those of the un-reinforced alloy. The fractured surfaces of the samples were studied by scanning electron microscopy (SEM). The results of the present study revealed a higher hardness for the extruded samples as compared with their sintered counterparts attributable to their increased density and decreased matrix grain size. It was also shown that addition of 2 and 5wt.% of B 4 C nano-particles increased yield strength of the extruded samples by 3 and 4 times respectively as compared with the un-reinforced aluminum.
DENSIFICATION AND MECHANICAL PROPERTIES OF TiB2-SiC NANOCOMPOSITE WITH SILICON CARBAID AS A SINTERING AID
Authors: Alavi Seyed Hashem , Baharvandi Hamid Reza , Abdizadeh Hossein
Published: March 2012

In this study, titanium diboride ( TiB 2) with silicon carbaid ( SiC ) nano particles as a sintering aid was isostatic-pressed, then sintered at a temperature of 1800°C. The amount of SiC had a significant influence on the sinterability and mechanical properties of TiB 2. When a small amount (10 wt%) of SiC was added, SiC reacted with titania ( TiO2 ) that was present on the surface of TiB 2 powder to form titanium carbaid ( TiC ) and amorphous silica ( SiO 2). Elimination of TiO 2 suppressed the grain growth effectively, which led to an improvement in the densification of TiB 2. Vickers hardness was enhanced remarkably through these improvements in the sinterability and microstructure. On the other hand, when a large amount (≥10 wt%) of SiC was added, the density and hardness were not improved much, presumably because of the extensive formation of SiC phase at the grain boundaries.
Effects of MgO Nano Particles on Microstructural and Mechanical Properties of Aluminum Matrix Composite prepared via Powder Metallurgy Route
Authors: Baghchesara Mohammad Amin , Abdizadeh Hossein , Baharvandi Hamid Reza
Published: March 2012

The objective of the present investigation was to evaluate the microstructural and mechanical properties of Al /nano MgO composite prepared via powder metallurgy method. Pure atomized aluminum powder with an average particle size of 1μm and MgO particulate with an average particle size between 60 to 80 nm were used. Composites containing 1.5, 2.5 and 5 percent of volume fraction of MgO were prepared by powder metallurgy method. The specimens were pressed by Cold Isostatic Press machine (CIP), subsequently were sintered at 575, 600 and 625°C. After sintering and preparing the samples, mechanical properties were measured. The results of microstructure, compression and hardness tests indicated that addition of MgO particulates to aluminum matrix composites improves the mechanical properties.
ANALYSIS OF MECHANICAL PROPERTIES AND MICROSTRUCTURE OF NANO-STRUCTURED NI-CO/SIC COMPOSITE PREPARED BY ELECTRODEPOSITION
Authors: LARI BAGHAL S.M. , HEYDARZADEH SOHI M. , AMADEH A.
Published: March 2012

Ni - Co / SiC nano-composites were prepared by electrodeposition in modified watts bath. The average size of SiC particles was 50 nm. In this study the effect of nano-particle incorporation, Co 2+ and saccharin concentration in electroplating bath on morphology and mechanical properties of Ni - Co / SiC nano-composites were investigated. The electrodeposits were characterized by X-ray diffraction (XRD), scanning electron microscope (SEM), Vickers micro-hardness and tensile tests. The results indicate that an increase in Co 2+ and saccharin concentration in electrolyte lead to a decrease in size of SiC agglomerates and grain size refining of matrix and improvement in mechanical properties. The hardness, tensile and yield strengths of the nano-composite material with nano-structure matrixes were higher than those for microcrystalline ones.
THE EFFECT OF HIGH ENERGY MILLING ON THE SR-HEXAFERRITE NANOCRYSTALLINE POWDER SYNTHESIZED BY A SOL-GEL AUTOCOMBUSTION METHOD
Authors: SADEGHI-NIARAKI S. , SEYYED EBRAHIM S. A. , RAYGAN SH.
Published: March 2012

In this research SrFe 12 O 19 nanocrystalline synthesized by sol-gel auto-combustion method and subsequent annealing at 1000°C for 1h subjected to mechanochemical treatment in a high-energy ball mill and then re-annealing. A planetary ball mill (Fritsch Pulveristte 6) was used to mill the strontium hexaferrite powder at 300 rpm in air for 10, 20 and 40 hours. The process was studied by X-ray diffraction technique and scanning electron microscopy. The X-ray study showed that SrFe 12 O 19 phase was decomposed by milling. Strontium hexaferrite and α- Fe 2 O 3 were obtained with 10 hours milling. There were α- Fe 2 O 3 and strontium hexaferrite in XRD patterns of 20 hours milled sample. With increasing of the milling time to 40 hours, strontium hexaferrite was decomposed completely. The annealing of the 20 and 40 h milled powders at 900°C for 1h led to the formation of single phase strontium hexaferrite with smaller crystallite size compare to that of the hexaferrite powder before milling and subsequent annealing.
Determination of Anisotropic Diamagnetic Susceptibility Using X-ray Diffraction
Authors: Kimura Tsunehisa , Song Guangjie , Matsumoto Kenji , Fujita Keiji , Kimura Fumiko
Published: March 2012

We present a facile method for determining the anisotropic diamagnetic susceptibility of biaxial crystals by performing X-ray diffraction measurements. The proposed method is based on the fact that the amplitude of fluctuations in a crystallographic axis under a magnetic field depends on the direction of the field with respect to the susceptibility axes. By calculating the magnetic energies of a crystal under static and rotating magnetic fields, we determined the relationship of the half-width of the diffraction spots corresponding to the (h
k
l) planes with the anisotropic magnetic susceptibilities χ1-χ2 and χ2-χ3 for the static field and χ1-χ2 and χ1-χ3 for the rotating field, where χ1 > χ2 > χ3. We have shown that the absolute values of the anisotropic diamagnetic susceptibilities can be determined if the size of the microcrystals is known, whereas only the ratio (χ2-χ3)/(χ1-χ2) or (χ1-χ3)/(χ1-χ2) can be determined if the microcrystal size is unknown.
Effects of Ba Deficiency on Ion Ordering, Grain Growth, and Microwave Dielectric Properties of Ba1-xZn1/3Nb2/3O3Ceramics
Authors: Wang Jun , Lu Wenzhong , Lei Wen
Published: March 2012

Ba1-xZn1/3Nb2/3O3(0≤x≤0.02) ceramics were prepared by the solid-state reaction. The effects of Ba deficiency on the long-range order (LRO) of B-site ions, grain growth, and microwave dielectric properties of Ba1-xZn1/3Nb2/3O3ceramics were investigated. Results show that Ba deficiency can effectively improve the sinterability of the ceramics and reduce the densification temperature by about 100 °C. The X-ray diffraction (XRD) and Raman spectra reveal that Ba-deficient samples exhibit a higher degree of LRO, and that the samples withx= 0.01 exhibit the highest degree of LRO. Furthermore, the degree of LRO increases with the decrease in sintering temperature in the range of 1400–1550 °C. Good microwave dielectric properties of εr= 39.8,Q×f= 66532 GHz, and τf= +23.9 ppm/°C are obtained for the Ba-deficient samples withx= 0.01 when sintered at 1450 °C for 4 h. After a second sintering process at 1400 °C/10 h during cooling, theQ×fvalues of Ba1-xZn1/3Nb2/3O3ceramics are improved. An optimizedQ×fvalue of 72650 GHz is obtained for the Ba0.99Zn1/3Nb2/3O3(x= 0.01) ceramics after two-step sintering.
Implementation of Universal Broadband Visible Antireflection Coating for Various Glass Substrates Using Ion-Assisted Deposition
Authors: Liou Yeuh-Yeong , Kuo Li-Hsiang , Yan Jhong-Yong , Jaing Cheng-Chung
Published: March 2012

A normal-incidence universal broadband visible antireflection (AR) coating design, suited for commonly used glass substrates with refractive indices ranging from 1.472 to 1.750, was simulated using a spiral search approach, and then seven different substrates were coated simultaneously in one single deposition run to reduce their visible spectral reflectances by ion-assisted deposition. It was shown that the universal visible AR coating design of various substrates with refractive indices of 1.472, 1.517, 1.552, 1.619, 1.672, 1.718, and 1.750, obtained using the spiral search algorithm of a 2-material 10-layer system, was simplified to an 8-layer design, and the total average visible reflectance of practical AR-coated substrates was reduced from 5.55% for uncoated substrates to below 0.340%; the universal visible AR performance was found suitable. Moreover, this normal-incidence universal broadband visible AR coating also revealed an acceptable wide-angle visible antireflective effect for an incident angle range of 0–30°.
Intelligent Ultraviolet Sensor Composed of GaN-Based Photodiode and N-Channel Metal Oxide Semiconductor Si-Charge Transfer Type Signal Processor
Authors: Lee ChangYong , Matsuno Fumiya , Hashimoto Yoshinori , Okada Hiroshi , Sawada Kazuaki , Wakahara Akihiro
Published: March 2012

Au/n-GaN Schottky barrier diode combined with Si-charge transfer type signal processor was investigated to realize intelligent UV sensors with low noise and high sensitivity. A 10-nm-thick Au was used for the semitransparent Schottky contact. The dark current–voltage characteristic of the Schottky barrier diode exhibited the ideal factor of 1.28 and barrier height of 1.1 eV. The sensitivity of 26.3 mA/W was obtained at a wavelength of 296 nm for 12 µW/mm2 UV irradiation power. Furthermore, the Au/n-GaN Schottky barrier diode was connected with the Si-charge transfer type signal processor to examine the effectiveness of the combined device for a UV detector. The processor was driven by a programmable function generator. Using the open-circuit voltage V
oc as the input signal, 350 mV output was achieved in a single integration cycle. The signal from the Schottky barrier diode was successfully amplified by accumulation operation of the Si-charge transfer type signal processor.