Distribution by Scientific Domains

Kinds of Diamond

  • boron-doped diamond
  • cvd diamond
  • nanocrystalline diamond
  • polycrystalline diamond

  • Terms modified by Diamond

  • diamond anvil cell
  • diamond bar
  • diamond electrode
  • diamond film
  • diamond net
  • diamond nucleation
  • diamond sector
  • diamond single crystal
  • diamond structure
  • diamond substrate
  • diamond surface
  • diamond syndrome

  • Selected Abstracts

    DIAMOND gets its boss

    DOI: 10.1107/S0909049501015680
    First page of article [source]

    XAFS,XI and new sources in Europe , SLS, SOLEIL and DIAMOND

    S. Samar Hasnain
    First page of article [source]

    Worldwide childhood type 1 diabetes incidence , what can we learn from epidemiology?

    G Soltesz
    Abstract:, Type 1 diabetes is the most common form of diabetes in most part of the world, although reliable data are still unavailable in several countries. Wide variations exist between the incidence rates of different populations, incidence is lowest in China and Venezuela (0.1 per 100 000 per year) and highest in Finland and Sardinia (37 per 100 000 per year). In most populations girls and boys are equally affected. In general, the incidence increases with age, the incidence peak is at puberty. After the pubertal years, the incidence rate significantly drops in young women, but remains relatively high in young adult males up to the age 29,35 years. Prospective national and large international registries (DIAMOND and EURODIAB) demonstrated an increasing trend in incidence in most regions of the world over the last few decades and increases seem to be the highest in the youngest age group. Analytical epidemiological studies have identified environmental risk factors operating early in life which might have contributed to the increasing trend in incidence. These include enteroviral infections in pregnant women, older maternal age (39,42 years), preeclampsia, cesarean section delivery, increased birthweight, early introduction of cow's milk proteins and an increased rate of postnatal growth (weight and height). Optimal vitamin D supplementation during early life has been shown to be protective. Some of these environmental risk factors such as viruses may initiate autoimmunity toward the beta cell, other exposures may put on overload on the already affected beta cell and thus accelerate the disease process. [source]


    Article first published online: 20 JUL 2010
    No abstract is available for this article. [source]


    ARCHAEOMETRY, Issue 1 2005
    P. J. LU
    The majority of prehistoric lithic artefacts were fashioned from rocks and minerals no harder than quartz, and there is no prehistoric evidence for the working of harder materials, such as corundum and diamond. The earliest physical evidence for the use of corundum (ruby, sapphire) is thought to be the abrasive grit recovered from Bronze Age Minoan quartz beads (c. 1700,1500 bc), while diamond is thought to have been used no earlier than 500 bc, in India. Here we show that corundum was worked c. 4000,3500 bc during the Neolithic period in China, in the form of polished axes from the Liangzhu and Sanxingcun cultures. We also present physical evidence that later Liangzhu axes (c. 2500 bc), made from the same previously undescribed rock whose most abundant component is corundum, were polished to a mirror-like finish with a diamond abrasive. Our findings, which are the first to support the use of corundum and diamond in a prehistoric context, may also help to explain the trademark feature of the Neolithic in China, vast quantities of finely polished nephrite jade artefacts. [source]

    DIAMONDS: Zimbabwe Gem Sale

    Article first published online: 30 SEP 2010
    No abstract is available for this article. [source]

    DIAMONDS: "Blood Diamond" Smuggling

    Article first published online: 18 DEC 200
    No abstract is available for this article. [source]

    DIAMONDS: De Beers Raises Production

    Article first published online: 27 AUG 200
    No abstract is available for this article. [source]

    Seasonal variation of diagnosis of Type 1 diabetes mellitus in children worldwide

    DIABETIC MEDICINE, Issue 7 2009
    E. V. Moltchanova
    Abstract Aims, To determine if there is a worldwide seasonal pattern in the clinical onset of Type 1 diabetes. Methods, Analysis of the seasonality in diagnosis of Type 1 diabetes was based on the incidence data in 0- to 14-year-old children collected by the World Health Organization Diabetes Mondiale (WHO DiaMond) Project over the period 1990,1999. One hundred and five centres from 53 countries worldwide provided enough data for the seasonality analysis. The incidence seasonality patterns were also determined for age- and sex-specific groups. Results, Forty-two out of 105 centres exhibited significant seasonality in the incidence of Type 1 diabetes (P < 0.05). The existence of significant seasonal patterns correlated with higher level of incidence and of the average yearly counts. The correlation disappeared after adjustment for latitude. Twenty-eight of those centres had peaks in October to January and 33 had troughs in June to August. Two out of the four centres with significant seasonality in the southern hemisphere demonstrated a different pattern with a peak in July to September and a trough in January to March. Conclusions, The seasonality of the incidence of Type 1 diabetes mellitus in children under 15 years of age is a real phenomenon, as was reported previously and as is now demonstrated by this large standardized study. The seasonality pattern appears to be dependent on the geographical position, at least as far as the northern/southern hemisphere dichotomy is concerned. However, more data are needed on the populations living below the 30th parallel north in order to complete the picture. [source]

    Writing as Inquiry: Storying the Teaching Self in Writing Workshops

    CURRICULUM INQUIRY, Issue 4 2002
    Freema Elbaz, Luwisch
    Recent research demonstrates that the process of telling and writing personal stories is a powerful means of fostering teachers' professional growth (Connelly & Clandinin, 1995; Conle, 1996; Diamond, 1994; Heikkinen, 1998; Kelchtermans, 1993). This article aims to further understanding of writing in the development of teachers' narratives of practice, and to critically examine the potential of the writing workshop as a space where diverse voices can find expression. I take up a narrative perspective, seeing the practice of teaching as constructed when teachers tell and live out particular stories. I examine the autobiographic writing of teachers who participated in a graduate course on autobiography and professional development, drawing on phenomenological (Van Manen, 1990) and narrative methods (Mishler, 1986) and attending to issues of voice (Raymond, Butt, & Townsend, 1992, Brown & Gilligan, 1992) and "restorying" (Clandinin & Connelly, 1996, 1998). The main questions addressed are how do teachers narratively construct their own development and how does the university context, usually construed as a locus of knowledge transmission, function as a framework for the processes of storytelling, reflection, and restorying of experience and for the elaboration by teachers of an internally persuasive discourse (Bakhtin, 1981)? The article describes the experience of the course and the various uses to which participants put autobiographic writing; the range of voices used in the writing is indicated. Three "moments" in the writing process are discussed: describing, storying, and questioning, moments that, taken together, are seen to make up the restorying process. The conclusions point to limitations and possibilities of writing in the academic setting, in particular the place of theory in helping to draw out teachers' voices. [source]

    Inhibitory functioning across ADHD subtypes: Recent findings, clinical implications, and future directions

    Zachary W. Adams
    Abstract Although growing consensus supports the role of deficient behavioral inhibition as a central feature of the combined subtype of ADHD (ADHD/C; Barkley 1997 Psychol Bull 121:65,94; Nigg 2001 Psychol Bull 127:571,598), little research has focused on how this finding generalizes to the primarily inattentive subtype (ADHD/I). This question holds particular relevance in light of recent work suggesting that ADHD/I might be better characterized as a disorder separate from ADHD/C (Diamond 2005 Dev Psychopathol 17:807,825; Milich et al. 2001 Clin Psychol Sci Pract 8:463,488). This article describes major findings in the area of inhibitory performance in ADHD and highlights recent research suggesting important areas of divergence between the subtypes. In particular, preliminary findings point to potential differences between the subtypes with respect to how children process important contextual information from the environment, such as preparatory cues that precede responses and rewarding or punishing feedback following behavior. These suggestive findings are discussed in the context of treatment implications, which could involve differential intervention approaches for each subtype targeted to the specific deficit profiles that characterize each group of children. Future research avenues aimed toward building a sound theoretical model of ADHD/I and a better understanding of its relation to ADHD/C are also presented. Specifically, investigators are encouraged to continue studying the complex interplay between inhibitory and attentional processes, as this area seems particularly promising in its ability to improve our understanding of the potentially distinct pathologies underlying the ADHD subtypes. © 2008 Wiley-Liss, Inc. Dev Disabil Res Rev 2008;14:268,275. [source]

    Interbank Lending, Liquidity and Banking Crises

    ECONOMIC NOTES, Issue 3 2002
    Paola Brighi
    In this paper, we show that abandoning the Diamond and Dybvig hypothesis of a unique bank representing the entire banking system gives rise to the possibility of endogenizing the interbank exchanges. In a system characterized by uncertainty regarding the moment of withdrawal of deposits, access to interbank liquidity decreases the bank risk of failure and bank runs. The possibility, moreover, to invest excess liquidity in the interbank market at a positive interest rate increases expected bank profits. (J.E.L.: E52, G21). [source]

    The Influence of Doping Levels and Surface Termination on the Electrochemistry of Polycrystalline Diamond

    ELECTROANALYSIS, Issue 6 2004
    Abstract The influence of surface chemistry and boron doping density on the redox chemistry of Fe(CN) at CVD polycrystalline diamond electrodes is considered. It is demonstrated that for this couple both the doping density and the surface chemistry are important in determining the rate of charge transfer at the electrode/electrolyte interface. For hydrogen terminated CVD diamond metallic electrochemical behavior is always observed, even at boron doping densities as low as 7×1018,cm,3. In contrast, the electrochemical behavior of oxygen terminated CVD diamond varies with doping density, a metallic response being observed at high doping density and semiconductor behavior at low doping density. It is shown that the results attained may be explained by a surface state mediated charge transfer mechanism, thus demonstrating the importance of controlling surface chemistry in electroanalytical applications of diamond. [source]

    Electroanalysis at Diamond-Like and Doped-Diamond Electrodes

    ELECTROANALYSIS, Issue 17 2003
    Abstract Diamond as a high performance material occupies a special place due to its in many ways extreme properties, e.g., hardness, chemical inertness, thermal conductivity, optical properties, and electric characteristics. Work mainly over the last decade has shown that diamond also occupies a special place as an electrode material with interesting applications in electroanalysis. When made sufficiently electrically conducting for example by boron-doping, ,thin film' and ,free,standing' diamond electrodes exhibit remarkable chemical resistance to etching, a wide potential window, low background current responses, mechanical stability towards ultrasound induced interfacial cavitation, a low ,stickiness' in adsorption processes, and a high degree of ,tunability' of the surface properties. This review summarizes some of the recent work aimed at applying conductive (boron-doped) diamond electrodes to improve procedures in electroanalysis. [source]

    Biotic ligand model of the acute toxicity of metals.


    Abstract The biotic ligand model (BLM) of acute metal toxicity to aquatic organisms is based on the idea that mortality occurs when the metal,biotic ligand complex reaches a critical concentration. For fish, the biotic ligand is either known or suspected to be the sodium or calcium channel proteins in the gill surface that regulate the ionic composition of the blood. For other organisms, it is hypothesized that a biotic ligand exists and that mortality can be modeled in a similar way. The biotic ligand interacts with the metal cations in solution. The amount of metal that binds is determined by a competition for metal ions between the biotic ligand and the other aqueous ligands, particularly dissolved organic matter (DOM), and the competition for the biotic ligand between the toxic metal ion and the other metal cations in solution, for example, calcium. The model is a generalization of the free ion activity model that relates toxicity to the concentration of the divalent metal cation. The difference is the presence of competitive binding at the biotic ligand, which models the protective effects of other metal cations, and the direct influence of pH. The model is implemented using the Windermere humic aqueous model (WHAM) model of metal,DOM complexation. It is applied to copper and silver using gill complexation constants reported by R. Playle and coworkers. Initial application is made to the fathead minnow data set reported by R. Erickson and a water effects ratio data set by J. Diamond. The use of the BLM for determining total maximum daily loadings (TMDLs) and for regional risk assessments is discussed within a probabilistic framework. At first glance, it appears that a large amount of data are required for a successful application. However, the use of lognormal probability distributions reduces the required data to a manageable amount. [source]

    Effect of Microstructure on Residual Stresses in Sintered Diamond,Metal Composites,

    U. Selvadurai-Laßl
    As residual stresses can reduce the lifetime of diamond-cobalt composite cutting tools, the composite stress state needs to be understood very well. Thus, the effect of microstructure on the residual stresses was investigated here. Stress measurements were carried out in the cobalt matrix by X-ray diffraction (XRD) and Synchrotron-XRD (SXRD). In addition to global stress measurements, investigations of stresses in small cobalt areas near the diamonds were performed by high brilliant synchrotron radiation using different apertures. [source]

    The Role of Binder Content on Microstructure and Properties of a Cu-base Active Brazing Filler Metal for Diamond and cBN

    R. Elsener
    Melting experiments of Cu-Sn-Ti-Zr filler metal powder containing cellulose nitrate and graphite, respectively, resulted in the formation of nanosized TiC particles in both Cu-rich phase and CuSn3Ti5 intermetallic regions of the alloy (see figure). The variation of the binder type and content allows to tailor the properties of the filler metals in terms of erosion resistance, decisive for a new generation of superabrasive tools. [source]

    Supported Lipid Bilayer on Nanocrystalline Diamond: Dual Optical and Field-Effect Sensor for Membrane Disruption

    Priscilla Kailian Ang
    Abstract It is demonstrated that a good biomimetic model lipid membrane with dynamic fluidity can be established on optically transparent nanocrystalline diamond (OTND) with surface roughness below 10,nm. Maigainin II, an antimicrobial peptide, is chosen to investigate the permeation of artificial bacterial membranes constructed on OTND. Due to the unique combination of optical transparency and highly sensitive surface conducting channel, intrinsic OTND affords the possibility of dual-mode sensing based on optical and field effect properties. This opens up new possibilities for making integrated biomolecule,semiconductor microdevices, or sensors where the binding of biomolecules can be tracked using confocal microscopy whilst the associated changes in charge density during membrane perforation can be tracked using the space charge effect in the semiconductor. Such a synergistic approach may provide a powerful methodology for the screening of specific bactericidal activity on biomimetic membrane systems. [source]

    The Marriage of Marx and Darwin?

    HISTORY AND THEORY, Issue 1 2002
    Doyne Dawson
    Recent attempts to develop scientific research strategies for cultural evolution have mostly drawn upon evolutionary biology, but within anthropology there is also an influential tradition of non-biological evolutionary thought whose basic principle is adaptation to the environment. This article is mainly concerned with the "cultural materialist" school of Marvin Harris, but also treats the recent attempt of Jared Diamond to create a more radical model of evolutionary ecology. I argue that the ecological tradition does not represent a real alternative to neo-Darwinism and is in fact a pseudo-Darwinist theory. I also suggest that the bias in favor of materialistic explanation in cultural evolution may not be justified. [source]


    Diamond and Dybvig provide a model of intermediation in which deposit insurance can avoid socially undesirable bank runs. We extend the Diamond,Dybvig model to evaluate the costs and benefits of deposit insurance in the presence of moral hazard by banks and monitoring by depositors. We find that complete deposit insurance alone will not support the first-best outcome: depositors will not have adequate incentives for monitoring and banks will invest in excessively risky projects. However, an additional capital requirement for banks can restore the first-best allocation. [source]

    Characteristics of skin aging in Korean men and women

    J. H. Chung
    Introduction Korea is located between Japan and Mainland China. The people of these three countries have similar appearances and it is difficult to differentiate between them. Although the population of Asia is more than half of the total population of the Earth, the inherent characteristics of Asian skin have not been well investigated. Commercial markets for cosmetics and drugs for photoaged skin are rapidly expanding in many Asian countries. Therefore, many investigators in the field of dermatology and cosmetology have become interested in brown Asian skin. Clinical characteristics of skin aging and photoaging in Asians Skin aging can be divided into two basic processes: intrinsic aging and photoaging [1]. Intrinsic aging is characterized by smooth, dry, pale, and finely wrinkled skin, whereas photoaging, which indicates premature skin aging in chronically photodamaged skin, is characterized by severe wrinkling and irregular pigmentation. The pattern of wrinkling in Asians seems to differ from that in Caucasians. Asians have coarser, thicker and deep wrinkles, particularly in the forehead, perioral and Crow's foot areas. In contrast, Caucasians usually have relatively fine cheek and Crow's foot wrinkles. The reasons for these differences are not known and need further investigation. There are racial, ethnic and genetic differences, and differences of skin structure and function, between the brown skin of Asians and the white skin of Caucasians. As Asian skin is more pigmented, acute and chronic cutaneous responses to UV irradiation differ from those in white skin. Many people believe, based on clinical impressions, that the main process of photoaging in Asians involves pigmentary changes, rather than wrinkling. However, no study has been performed to confirm this belief. Risk factors for skin wrinkles and their relative risks in Korean skin [2] Various factors such as age, sun-exposure, and smoking are known to be important risk factors for wrinkles. However, the relative risks of each factor on wrinkles in the brown skin of Asians have not been investigated, and they could differ from those in Caucasians. An evaluation system for skin wrinkling is necessary for Asian skin [3]. Thus, we developed an eight-point photographic scale for assessing wrinkles in both Korean genders [2]. This scale can probably be applied to the populations of other Asian countries, at least to the Japanese and Chinese. The pattern of wrinkles in both genders appears to be similar. Age Age is an important risk factor for wrinkling in Asians, as in Caucasians. Korean subjects in their 60s showed a 12-fold increased risk of wrinkling, while subjects in their 70s have a 56-fold increased risk compared with young age group. UV light It is well known that the UV component in sunlight can cause and accelerate photoaging. The pigmented skin of Asian may better protect skin from acute and chronic UV damage. However, we found a strong association between sun-exposure and the development of wrinkling in Koreans. It was found that sun exposure of more than 5 h per day was associated with a 4.8-fold increased risk in wrinkling versus less than 2 h of sun-exposure in Koreans. Estrogen deficiency Korean females have more wrinkles than men, after controlling for age, sun exposure, and smoking, it was found that they have a 3.6-fold increased risk of developing wrinkles than their male counterparts [2]. It has also been reported, that the relative risk for wrinkling in women is higher than in men as for in white Caucasians [4]. The reason why women show more wrinkles remains to be determined. It is possible that a reduction in skin collagen because of estrogen deficiency in postmenopausal woman may aggravate wrinkling severity. Korean women with more than 10 years since menopause showed a 3.9-fold higher risk of wrinkling than the women 5 years of beyond menopause [5]. We demonstrated that women with a history of HRT have a significantly lower risk, more specifically, one fifth of the risk of facial wrinkling relative to those who had no history of HRT. Interestingly, we found that wrinkle severity significantly increased with an increasing number of full term pregnancies. The relative risk for severe wrinkling is increased by approximately 1.8-fold per full term pregnancy. Smoking It is known that smoking causes skin wrinkling in Caucasians, and that it plays no role in Blacks [6, 7]. Koreans with have a smoking history of more than 30 pack years showed a more than 2.8-fold increased risk of wrinkles [2]. The relative risks of wrinkles associated with a 30,50 pack-years history of smoking were 2.8- and 5.5-fold, respectively. Dyspigmentation in Asian skin To follow pigmentary changes, six photographic standards for both genders were developed for Korean skin, to produce a 6-point scale [2, 8]. Hyperpigmented spots, mostly lentigines, were prominent among women, while seborrheic keratosis tended to be more prominent in men. Seborrheic keratosis in Korean men Seborrheic keratoses (SKs) are benign cutaneous tumors. They have diverse clinical and histopathological appearances and are very common in the elderly (over 50 years old). The etiology of SKs is not well understood, although patients with a great number of lesionsshow a familial trait with an autosomal dominant pattern, and human papilloma virus has been suggested as possible cause because of verrucous appearance of the lesions. Exposure to sunlight has been suggested to be a risk factor for SKs. However, there is still some debate in terms of the role of sunlight. Recently, we have investigated the clinical characteristics of SKs and relationship between SKs and sunlight exposure in Korean males [9]. The prevalence of SKs in Koreans increases with age; it rose from 78.9% at 40 years, to 93.9% at 50 years and 98.7% in those over 60 years. Exposed areas, i.e. the face, neck and dorsum of the hands, demonstrate a significant increase in the prevalence of SKs by decade, whereas partly exposed areas, although SKs tended to increase in prevalence with age, this trend was not significant. When the estimated body surface area (BSA) is taken into account, the number of SKs on both the face and dorsum of the hands (0.51 ± 0.08 per 1% BSA) was over-represented compared with the trunk. SKs were also concentrated on the neck (0.38 ± 0.07 per 1% BSA) and in the V-area (0.47 ± 0.09 per 1% BSA). Outer forearms also showed 3-fold more SKs per unit area than neighboring arms and inner forearms, which are classified as partly exposed area (0.09 ± 0.02, 0.03 ± 0.01, respectively). The total area covered by SKs on exposed area also became significantly larger with aging than on intermittently exposed areas. These results indicate that exposure to sunlight might be related to SK growth. Our results indicated that excessive sun exposure is an independent risk factor of SKs. After controlling for age, smoking, and skin type, subjects with a sun exposure history of more than 6 hours per day showed a 2.28-fold increased risk of having severe SKs (n , 6) compared with those exposed for less that 3 h per day. These findings indicated that sun-exposure may play an important role in SK development. In summary, SKs are very common in Korean males and represent one of the major pigmentary problems. SKs concentrate on exposed skin, especially on the face and dorsum of the hands. Both age and lifetime cumulative sunlight exposure are important contributing factors and may work in a synergistic manner. Conclusion Many people tend to believe that wrinkles are not a prominent feature of Asian photoaged skin, and that dyspigmentation is a major manifestation in Asian skin. Contrary to this impression, wrinkling is also a major problem in the photoaged skin of Asians, and Korean people showing severe pigmentary changes usually tend to have severe wrinkles. In conclusion, the wrinkling patterns and pigmentary changes of photoaged skin in East Asians differ from those of Caucasians, and the relative risks of aggravating factors may be different from those of Caucasian skin. References 1.,Gilchrest, B.A. Skin aging and photoaging: an overview. J. Am. Acad. Dermatol. 21, 610,613 (1989). 2.,Chung, J.H. et al. Cutaneous photodamage in Koreans: influence of sex, sun exposure, smoking, and skin color. Arch. Dermatol. 137, 1043,1051 (2001). 3.,Griffiths, C.E. et al. A photonumeric scale for the assessment of cutaneous photodamage. Arch. Dermatol. 128, 347,351 (1992). 4.,Ernster, V.L. et al. Facial wrinkling in men and women, by smoking status. Am. J. Public Health. 85, 78,82 (1995). 5.,Youn, C.S. et al. Effect of pregnancy and menopause on facial wrinkling in women. Acta Derm. Venereol. 83, 419,424 (2003). 6.,Kadunce, D.P. et al. Cigarette smoking: risk factor for premature facial wrinkling. Ann. Intern. Med. 114, 840,844 (1991). 7.,Allen, H.B., Johnson, B.L. and Diamond, S.M. Smoker's wrinkles? JAMA. 225, 1067,1069 (1973). 8.,Chung, J.H. Photoaging in Asians. Photodermatol. Photoimmunol. Photomed. 19, 109,121 (2003). 9.,Kwon, O.S. et al. Seborrheic keratosis in the Korean males: causative role of sunlight. Photodermatol. Photoimmunol. Photomed. 19, 73,80 (2003). [source]

    Cover Picture: Synthesis of a Self-Assembled Hybrid of Ultrananocrystalline Diamond and Carbon Nanotubes (Adv. Mater.

    ADVANCED MATERIALS, Issue 12 2005
    Abstract The cover shows self-assembled hybrids of ultrananocrystalline diamond (UNCD) and carbon nanotubes (CNTs). These hybrids were successfully prepared by their simultaneous growth within an argon-rich Ar/CH4 plasma, in work reported on p.,1496 by Carlisle and co-workers. Various methods demonstrated the coexistence of UNCD and CNTs, and the capability of controlling the relative fraction and configuration of UNCD and CNTs in the hybrid material. This new synthesis pathway enables the development of new nanocarbons with unique mechanical, tribological, and electrochemical properties. [source]

    The construct validity of the client questionnaire of the Wisconsin Quality of Life Index , a cross-validation study

    Jean Caron
    Abstract The Wisconsin Quality of Life Index (W-QLI, Becker, Diamond and Sainfort, 1993) consists of eight scales: satisfaction with life domains, occupational activities, symptoms, physical health, social relations/support, finances, psychological wellbeing, and activities of daily living. The W-QLI has been modified to fit the characteristics of the Canadian population, the universal Canadian health system, and community and social services in Canada and the modified form was named CaW-QLI (Diaz, Mercier, Hachey, Caron, and Boyer, 1999). This study will verify the empirical basis of these theoretical dimensions by applying a cross-validation procedure on two samples, most of whose subjects have a serious mental illness. Confirmatory factor analyses and exploratory factor analyses using the principal component extraction technique with varimax rotation were applied. With the exception of the occupational activities domain, the remaining scales were correctly identified by the factor analyses on each sample. The occupational activities scale should be developed by additional items for representing this scale, which is too brief, and two other items should be revised in order to improve the quality of the instrument. Copyright © 2003 Whurr Publishers Ltd. [source]

    DIAMONDS: "Blood Diamond" Smuggling

    Article first published online: 18 DEC 200
    No abstract is available for this article. [source]

    Effects of Tooth Preparation Burs and Luting Cement Types on the Marginal Fit of Extracoronal Restorations

    Mohamed F. Ayad BDS
    Abstract Purpose: Although surface roughness of axial walls could contribute to precision of a cast restoration, it is unclear how the roughness of tooth preparation affects marginal fit of the restoration in clinical practice. The purpose of this study was to describe the morphologic features of dentin surfaces prepared by common rotary instruments of similar shapes and to determine their effects on the marginal fit for complete cast crowns. Materials and Methods: Ninety crowns were cast for standardized complete crown tooth preparations. Diamond, tungsten carbide finishing, and crosscut carbide burs of similar shape were used (N = 30). The crowns in each group were subdivided into three groups (n = 10) for use with different luting cements: zinc phosphate cement (Fleck's), glass ionomer cement (Ketac-Cem), and adhesive resin cement (Panavia 21). Marginal fit was measured with a light microscope in a plane parallel to the tooth surface before and after cementation between four pairs of index indentations placed at equal distances around the circumference of each specimen. Difference among groups was tested for statistical significance with analysis of variance (ANOVA) followed by Ryan-Einot-Gabriel-Welsch Multiple Range Test (,= 0.05). Results: Analysis of measurements disclosed a statistically significant difference for burs used to finish tooth preparations (p < 0.001); however, luting cement measurements were not significantly different (p= 0.152). Also, the interaction effect was not significantly different (p= 0.685). For zinc phosphate cement, the highest marginal discrepancy value (100 ± 106 ,m) was for tooth preparations refined with carbide burs, and the lowest discrepancy value (36 ± 30 ,m) was for tooth preparations refined with finishing burs. For glass ionomer cement, the highest marginal discrepancy value (61 ± 47 ,m) was for tooth preparations refined with carbide burs, and the lowest discrepancy value (33 ± 40 ,m) was for tooth preparations refined with finishing burs. For adhesive resin cement, the highest marginal discrepancy value (88 ± 81 ,m) was for tooth preparations refined with carbide burs, and the lowest discrepancy value (19 ± 17 ,m) was for tooth preparations refined with finishing burs. Conclusions: Marginal fit of complete cast crowns is influenced by tooth preparation surface characteristics, regardless of the type of luting agent used for cementation. Tooth preparations refined with finishing burs may favor the placement of restorations with the smallest marginal discrepancies, regardless of the type of cement used. [source]

    Tooth Preparation: A Study on the Effect of Different Variables and a Comparison Between Conventional and Channeled Diamond Burs

    Daniel F. Galindo DDS
    Purpose: The purpose of this study was to evaluate the different variables involved in tooth cutting to characterize intrapulpal temperature generation, cutting efficiency, and bur durability when using conventional and channeled diamond burs. Materials and Methods: Forty premolars and 60 molars were selected for the study. Four diamond burs were paired according to grit size: 125- ,m grit: Brasseler Coarse (Control 1) and TDA System (Test 1) burs; and 180- ,m grit: Brasseler CRF (Control 2) and NTI Turbo Diamond (Test 2) burs. Each bur was used twice when cutting the premolar teeth, whereas it was used for 60 cuts when cutting the molar teeth. The data were analyzed to compare the correlation of bur design, grit and wear, amount of pressure, advancement rate, revolutions per minute, cutting time and rate, and proximity to the pulp chamber with intrapulpal temperature generation, cutting efficiency, and bur longevity. The mean values of test and control burs in each group were compared using an ANOVA (p < 0.05 for significant differences) for temperature generation and an ANOVA and the Tukey multiple range test (p, 0.05) for cutting efficiency and bur longevity. Results: No significant difference was found in intrapulpal temperature generation while cutting premolar and molar teeth with conventional and channeled diamond burs. In both groups, the mean temperature recorded during and after the cutting procedure was lower than the baseline temperature. For premolar teeth, no significant difference was established for control and test burs for the load required to cut into the tooth and the cutting rate. However, both test burs showed significantly fewer revolutions per minute when compared to their control counterparts. For the molar teeth, the Brasseler CRF bur required a significantly lower cutting load when compared to the NTI bur, whereas no difference was noted between the other pair of burs. The cutting rate was significantly higher for both control burs, whereas revolutions per minute (rpm) were greater for control coarser burs only. Overall, channeled burs showed a significantly lower cutting efficiency when compared to conventionally designed burs. Conclusion: Within the limitations of this study, channeled burs showed no significant advantage over conventional diamond burs when evaluating temperature generation and bur durability. Moreover, the cutting efficiency of conventional burs was greater than that of channeled burs. [source]

    Diamond as pressure sensor in high-pressure Raman spectroscopy using sapphire and other gem anvil cells

    Valentín García Baonza
    Abstract We propose a new Raman pressure scale based on the shift with pressure of the fundamental Raman band of micrometer-sized diamonds. First, we confirmed that the pressure slope of the triply degenerate diamond phonon behaves in a similar fashion to that of the bulk. Our measurements were calibrated Raman against the Sm:YAG fluorescence pressure scale up to 5 GPa using a gasketed sapphire anvil cell. The most relevant features regarding the design of the anvil cell are briefly outlined. Measurements were performed under hydrostatic conditions using 4 : 1 methanol,ethanol as pressure-transmitting medium. The calibration pressures according to the relationship p(GPa) = 0.356[,(cm,1) , 1332.3] are considered to be accurate within about 0.1 GPa. The convenience of using micrometer-sized diamonds as pressure sensors in Raman studies using gem anvil devices is demonstrated with several examples. Copyright © 2003 John Wiley & Sons, Ltd. [source]

    Characterization of germanium linear kinoform lenses at Diamond Light Source

    L. Alianelli
    The unprecedented brilliance achieved by third-generation synchrotron sources and the availability of improved optics have opened up new opportunities for the study of materials at the micrometre and nanometre scale. Focusing the synchrotron radiation to smaller and smaller beams is having a huge impact on a wide research area at synchrotrons. The key to the exploitation of the improved sources is the development of novel optics that deliver narrow beams without loss of brilliance and coherence. Several types of synchrotron focusing optics are successfully fabricated using advanced miniaturization techniques. Kinoform refractive lenses are being developed for hard X-ray beamlines, and the first test results at Diamond are discussed in this paper. [source]

    Use of confocal and multiphoton microscopy for the evaluation of micro-optical components and emitters

    J.M. Girkin
    Abstract We report on the application of confocal and multiphoton microscopic techniques for the evaluation of the latest generation of micro optical components. The optical emitting characteristics of arrays of matrix addressable GaN micrometer-sized light emitting diodes (micro-LEDs) have been measured using a commercial confocal microscope utilising the LEDs' own emission along with reflection confocal microscopy to determine the surface structure. Multiphoton induced luminescence from the 10,20-micron diameter emitters has also been used to examine the structure of the device and we compare this with electrically induced emission. In related work, the optical properties of micro lens arrays (10,100-micron diameter) fabricated in SiC, Sapphire, and Diamond have been determined using transmission confocal microscopy. Such optical microscopy techniques offer a simple, non-destructive method to determine the structure and performance of such novel devices. Microsc. Res. Tech. 64:293,296, 2004. © 2004 Wiley-Liss, Inc. [source]

    Central venous catheter thrombosis as a cause of SVC obstruction and cardiac tamponade in a patient with Diamond,Blackfan anemia and iron overload

    PEDIATRIC BLOOD & CANCER, Issue 1 2006
    Mark L. Norris MD
    Abstract Cardiac tamponade is an infrequent but potentially lethal complication related to use of central venous catheters (CVC). We present the case of a 16-year-old female with Diamond,Blackfan anemia (DBA) who developed pericardial tamponade secondary to superior venous caval obstruction caused by CVC thrombosis. The patient presented 3 months after line placement with vomiting, abdominal pain, and cardiomegaly on chest X-ray (CXR). Her condition quickly decompensated with cardiac arrest and subsequent death despite immediate pericardiocentesis. As a result of this case, our center has developed a protocol for the management of CVC problems as a means of facilitating rapid recognition of central line clots. © 2005 Wiley-Liss, Inc. [source]