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PubMed1989

Fibronectin on excimer laser and diamond knife incisions.

The experiment was designed to illustrate the difference between the diamond knife and the excimer laser (ArF 193 nm) on keratotomy incisions. The histopathologic effect of fibronectin applied to these wounds was observed. Fibronectin demonstrated a chemotactic effect on fibroblasts and increased the amount of newly synthesized collagen deposited at the incision sites. The excimer laser incisions treated with fibronectin had 43% more fibroblasts per 2,500 microns 2 than the excimer laser incisions not treated with fibronectin. The adjustable diamond knife incisions treated with fibronectin had 42% more fibroblasts than the adjustable diamond knife incisions not treated with fibronectin. The excimer laser ArF 193 nm incisions had 18% more fibroblasts in the incision area than the adjustable diamond knife incisions independent of fibronectin usage. This indicates that the excimer laser incisions and the diamond knife incisions may have different healing mechanisms--perhaps because of the distinctive modes of action of these instruments.

Animals↗

PubMed2006

Examination of the spatially heterogeneous electroactivity of boron-doped diamond microarray electrodes.

Spatial variations in the electrical and electrochemical activity of microarray electrodes, fabricated entirely from diamond, have been investigated. The arrays contain approximately 50-mum-diameter boron-doped diamond (BDD) disks spaced 250 mum apart (center to center) in insulating intrinsic diamond supports, such that the BDD regions are coplanar with the intrinsic diamond. Atomic force microscopy (AFM) imaging of the surface reveals a roughness of no more than +/-10 nm over the array. Each BDD microdisk within the array contains polycrystalline BDD with a variety of different grains exposed. Using conducting-AFM, the conductivity of the different grains was found to vary within a BDD microdisk. Electrochemical imaging of the electroactivity of the microdisk electrodes using scanning electrochemical microscopy operating in substrate generation-tip collection mode revealed that, under apparently diffusion-limited steady-state conditions, there was a small variation in the response between electrodes. However, the majority of electrodes in the array appeared to show predominantly metallic behavior. For the electrodes that showed a lower activity, all grains within the microdisk supported electron transfer, albeit at different rates, as evidenced by studies on the electrodeposition of metallic silver, at potentials far negative of the flat band potential of oxygen-terminated polycrystalline diamond. The possibility of using these array electrodes for steady-state diffusion-limited measurements in electroanalytical applications is far-reaching. However, caution should be exercised in the kinetic analysis of voltammetric measurements, since wide variations in the electroactivity of individual grains are apparent when the potential is below the diffusion-limited value.

Journal Article↗

PubMed2003

Covalent adlayer growth on a diamond thin film surface.

The surface of boron-doped diamond thin films can be modified by exposure to a strong oxidizing agent, resulting in the formation of -OH and =O terminated diamond. The -OH groups are reacted with an acid chloride to produce a covalently bound, modified diamond thin film surface. The demonstration of these reactions allows for the facile modification of diamond surfaces using techniques well established for oxide surfaces. Characterization of the covalently bound species shows submonolayer coverage, and time-resolved fluorescence measurements are reflective of the highly featured nature of the diamond film.

Journal Article↗

PubMed2004

Photochemical modification of diamond films: introduction of perfluorooctyl functional groups on their surface.

Photolysis of perfluoroazooctane with diamond films led the chemical modification of the surface to introduce perfluorooctyl functional groups, confirmed by means of Fourier transform infrared spectroscopy, X-ray photoelectron spectroscopy (XPS), Raman spectroscopy, and time-of-flight secondary ion mass spectrometry measurements. Diamond films modified with fluorine moieties showed improved frictional property and reduction of surface energy, as evaluated by contact angle to water, compared with a pristine diamond film. The contact angle and friction coefficient of chemically modified diamond film are 118 degrees and 0.1, respectively. The results of the value of the contact angle depending on irradiation times are consistent with those of the F/C ratio of fluorinated diamond films by monitoring with XPS.

Journal Article↗

PubMed2002

The electrochemical oxidation of homocysteine at boron-doped diamond electrodes with application to HPLC amperometric detection.

The electrochemical oxidation of homocysteine was studied at as-deposited and anodized (oxidized) boron-doped diamond (BDD) thin film electrodes with cyclic voltammetry, flow injection analysis and high-pressure liquid chromatography with amperometric detection. At anodized boron-doped diamond electrodes, highly reproducible, well-defined cyclic voltammograms for homocysteine oxidation were obtained in acidic media, while as-deposited diamond did not provide a detectable signal. In alkaline media, however, the oxidation response was obtained both at as-deposited and anodized diamond electrodes. The potential sweep rate dependence of homocysteine oxidation (peak currents for 1 mM homocysteine linearly proportional to v(1/2), within the range of 0.01 to 0.3 V s(-1)) indicates that the oxidation involves a diffusing species, with negligible adsorption on the BDD surface at this concentration. In the flow system, BDD exhibited a highly reproducible amperometric response, with a peak variation less than 2%. An extremely low detection limit (1 nM) was obtained at 1.6 V vs. Ag/AgCl. In addition, the determination of homocysteine in a standard mixture with aminothiols and disulfide compounds by means of isocratic reverse-phase HPLC with amperometric detection at diamond electrodes has been investigated. The results showed excellent separation, with a detection limit of 1 pmol and a linear range of three orders of magnitude.

Boron↗

PubMed1990

Ambiguous fluidity and rigidity and diamonds that ooze!

If white hemicircles rotate over the edges of a black diamond, there occurs an ambiguity of rigidity and motion. As the hemicircles obscure the vertices of the diamond, the figure transforms from a diamond to a rotating, nonrigid cross made of a tar-like fluid. When the corners reappear, the stimulus again becomes a rigid, solid diamond. Visibility of the vertices implies rigidity. If white squares are rotated, fluidity is not perceived. If the diamond has sawtooth edges and the hemicircles are rotated, no fluidity is perceived. Similarly, if illusory contours suggest the amodal completion of the vertices, rigidity is maintained.

Adult↗

PubMed1999

Diamond-shaped optical fiber delivery system.

OBJECTIVE: Physicians who use laser systems are looking for new fiberoptic delivery systems with better performance. We searched for a delivery system with high power and with a tip of high durability that may be reused many times. SUMMARY BACKGROUND DATA: The delivery systems currently found on the market can burn and break easily. The surgeon may either finish the surgery with a damaged delivery system, or have to switch to a new one during surgery, thus increasing the inconvenience and cost of the surgery. METHODS: Distal tips of fibers used with Nd:YAG and diode lasers have been shaped and polished according to their specific function, including excision, vaporization, and coagulation of tissue. RESULTS: We have developed several prototypes of optical fiber delivery systems, and in particular, we have developed a prototype of a delivery system, called the Diamond-Shaped Optical Fiber Delivery System, or Diamond. By making the tip of an optical fiber diamond shaped, we are able to obtain greater mechanical resistance than that of other delivery systems that were tested in our laboratory. In the Colorectal Unit, we applied it in surgical procedures such as perianal fistulectomy, hemorrhoidectomy, and excision of condilomata acuminata and pilonidal cyst and sinuses. During cutting and coagulating, the system performed well with no technical problems. CONCLUSIONS: A new delivery system (Diamond) gave satisfactory performance during surgical operations. Its main component, the diamond-shaped distal end, provided high durability and was reused many times, thus improving the quality of operations and reducing expenses greatly.

Biophysical Phenomena↗

PubMed2004

Effect of diamond nucleation process on propagation losses of AlN/diamond SAW filter.

In this work, the effect of a diamond nucleation process on freestanding aluminium nitride (AlN)/diamond surface acoustic wave (SAW) device performances was studied. Before diamond deposition, silicon (Si) substrates have been mechanically nucleated, using an ultrasonic vibration table with submicron diamond slurry, and bias-enhanced nucleated (BEN). Freestanding diamond layers obtained on mechanically scratched Si substrates exhibit a surface roughness of R(MS) = 13 nm, whereas very low surface roughness (as low as R(MS) < or = 1 nm) can be achieved on a freestanding BEN diamond layer. Propagation losses have been measured as a function of the operating frequency for the two nucleation techniques. Dispersion curves of phase velocities and electromechanical coupling coefficient (K2) were determined experimentally and by calculation as a function of normalized thickness AlN film (kh(AlN) = 2pi h(AlN)/lambda). Experimental results show that the propagation losses strongly depend on the nucleation technique, and that these losses are weakly increased with frequency when the BEN technique is used.

Journal Article↗

PubMed1990

'Diamond-shaped' crypts and mucosal elastin: helpful diagnostic features in biopsies of rectal prolapse.

The biopsy diagnosis of prolapsing rectal mucosa syndrome can be difficult. We present two newly described features--'diamond-shaped' crypts and mucosal elastin--which appear to be helpful in histological diagnosis. Of 32 biopsies of prolapsing rectal mucosa syndrome, all showed diamond-shaped crypts or mucosal elastin, and 28 contained both. Control biopsies comprised cases of normal or irritable bowel syndrome (46), irradiation colitis and ischaemic colitis (16), inflammatory bowel disease (26), and adenomas (30). Mucosal elastin and 'diamond-shaped' crypts with distinctive scalloped edges, which were never seen in prolapse, were observed in half the cases of irradiation and ischaemic colitis. Diamond-shaped crypts were seen in one case of inflammatory bowel disease. Diamond-shaped crypts and elastin were seen in the base of adenomas large enough to cause localized prolapse, and in four biopsies from patients with irritable bowel syndrome, all of whom had given a history of straining at stool.

Adenoma↗

PubMed1995

DIAMOND: a computerized system for the management and evaluation of district-wide diabetes care.

A computerized diabetic clinic management system, DIAMOND, has been developed with the collaboration of local general practitioners (GPs) to assist communication about diabetic patients across the district. DIAMOND is written in a Windows format using Microsoft Access and its dataset is in line with BDA and Diabcare recommendations. DIAMOND is user-friendly and includes displays and help messages throughout and does not require advanced computer knowledge. The main index contains two primary tables: a patient registration table with demographic data and an episode table with clinically important physical and biochemical measures. All entered data are coded to facilitate audit and an audit function, which automatically presents data, either numerically or graphically, is included in the report facility. DIAMOND also incorporates a system for patient education and training (PEATS) which may be operated by a health professional or the patient. Over 4500 patients in Newham are presently registered on DIAMOND with in excess of 15,000 episodes. Evaluation of this information is providing important clinical information both within individual GP practices and district-wide to assist future plans for health care provision.

Diabetes Mellitus↗

PubMed2000

A comparison of Ultraflex Diamond stents and Wallstents for palliation of distal malignant biliary strictures.

OBJECTIVE: The objective of this study was to compare the effectiveness of the Ultraflex Diamond stent and the Wallstent for the drainage of distal malignant biliary strictures. METHODS: The results obtained in 23 consecutive patients in whom the insertion of a Ultraflex Diamond stent had been attempted were compared with those obtained in 23 patients matched for age, gender, serum bilirubin, and diagnosis who had been treated with Wallstents. RESULTS: Biliary drainage was obtained in 100% of cases. More than one stent was required in 4% and 12% of patients treated with Ultraflex Diamond stents and Wallstents, respectively (p > 0.05). The first stent inserted did not provide adequate biliary drainage in four patients, because of the impaction of the proximal end of Wallstents into the bile duct wall (n = 2) and obstruction of the stent lumen by tumor tissue (one in each group). Procedure-related morbidity and mortality were 4%. Patients were followed-up for a mean of 228 days (range, 1 to 1262 days). During follow-up, bile duct obstruction relapsed in 5/22 and 6/21 patients treated with Ultraflex Diamond stents and Wallstents, respectively. Life table analysis of bile duct patency was similar with both stent models. CONCLUSIONS: Ultraflex Diamond stents are easy to insert and provide a high success rate of biliary drainage with minimal complication. Although long-term patency rates obtained with this stent were similar to those observed with Wallstents, no firm conclusion can be drawn in this regard due to the relatively small number of patients studied.

Adult↗

PubMed1998

Eclogitic diamond formation at jwaneng: No room for a recycled component

Eclogitic diamonds have a large range of delta13C values, whereas peridotitic diamonds do not. Paired delta15N-delta13C-N variations in 40 eclogitic diamonds from the Jwaneng kimberlite in Botswana show that neither the influence of recycled biogenic carbon nor the global and primordial heterogeneity of mantle carbon are likely for the origin of the large delta13C range; the data instead support a fractionation process. It is proposed that carbonatitic mantle melts from which diamonds crystallize undergo different evolutions before diamond precipitation, when percolating through either a peridotite or an eclogite. These different evolutions, reflecting the presence or absence of olivine, can account for their respective delta13C distributions.

Journal Article↗

PubMedDate not supplied

Flow in sequential vein grafts with diamond anastomoses.

Flow in single grafts was compared to flow in sequential grafts with diamond anastomoses to the branches of the right and circumflex coronary arteries. The mean flow was 36 ml/min for single grafts, 51 ml/min for sequential grafts with one diamond anastomosis, and 69 ml/min for sequential grafts with two diamond anastomoses. The flow in two single grafts, 72 ml/min, was significantly more than the flow in sequential grafts with one diamond anastomosis and equalled the flow in sequential grafts with three distal anastomoses. Constructing diamond anastomoses with interrupted sutures did not significantly enhance flows in sequential grafts.

Blood Flow Velocity↗

PubMed1978

[Studies on the cutting ability of dental diamond points--the trial manufacture of the cutting test apparatus (author's transl)].

Diamond points and tungstencarbite burs are used as the dental cutting tools for many appliance accordingly with the many purpose of used positions. Notwithstanding that the dental cutting tools have been usually applied for many purpose of dental treatment, the paper on these studies have scarcely been reported. In this studies the test of dental cutting tools curried out using the diamond points and examined these characteristics. As the problems on the cutting tests are the push load of cutting tools and the cutting quantities. This studies tried to make the test apparatus for the cutting test of dental diamond points considering to dental treatments. The glass plates used for photograph are used for cutting materials supposing to the enamel properties of teeth and the cutting tests put into practice for the types of diamond points with different diameter. The cutting characteristics of the diamond points are examined with the using of the test results and are appreciated with the considering to the test apparatus.

Dental High-Speed Equipment↗

PubMedDate not supplied

13C spin-lattice relaxation in natural diamond: Zeeman relaxation at 4.7 T and 300 K due to fixed paramagnetic nitrogen defects.

13C spin-lattice relaxation times in the laboratory frame, ranging from 1.4 to 36 h, have been measured on a suite of five natural type Ia and Ib diamonds at 4.7 T and 300 K. Each of the diamonds contains two types of fixed paramagnetic centers with overlapping inhomogeneous electron paramagnetic resonance (EPR) lines. EPR techniques have been employed to identify these defects and to determine their concentrations and relaxation times at X-band. Spin-lattice relaxation behavior of 13C in diamonds containing paramagnetic P1, P2, N2. and N3 centers are discussed. Depending on the paramagnetic impurity types and concentrations present in each diamond, three different nuclear spin-lattice relaxation (SLR) paths exist, namely that due to electron SLR mechanisms and two types of three-spin processes (TSPs). The one three-spin process (TSP1) involves a simultaneous transition of two electron spins belonging to the same hyperfine EPR line and a flip of a 13C spin, while the other process (TSP2) involves two electron spins belonging to different hyperfine EPR lines and a 13C spin. It is shown that the thermal contact between the 13C nuclear Zeeman and electron dipole-dipole interaction reservoirs is field dependent, thus forming a bottleneck in the 13C relaxation path due to TSP1 at high magnetic fields.

Carbon Isotopes↗

PubMed1991

Implanted 3He, 4He, and Xe in further studies of diamonds from Western Australia.

In measurements of the noble gases in additional samples of diamonds from the Argyle and Ellendale lamproites in Western Australia we have failed to encounter any neon-rich stones such as showed solar-like isotopic compositions in earlier work. No neon was detected above the relatively high blank levels in our glass apparatus. White and brown diamonds showed no differences in noble gas content, nor did samples segregated by the color of long-wave UF fluorescence. The rare gas patterns in the 1.2 Ga Argyle pipe are largely consistent with implanted 3He, 4He, and fissiogenic Xe from U/Th in the matrix rock in which the diamonds have been stored for so long. These implanted species are absent in diamonds from the much younger (approximately 20 Ma) Ellendale pipe. We give implantation formulae for several models of inhomogeneously distributed U/Th. Differences in 3He content between pipe and alluvial Argyle samples are consistent with expected cosmogenic production in the latter. An expanded data base for helium and carbon isotopic data on the same samples supports a negative [4He]-delta 13C correlation seen earlier in work from our group, but if the Argyle samples, which contain light carbon, are corrected for implanted 4He, the correlation is considerably weakened. We no longer see an earlier 3He/4He-delta 13C correlation.

Carbon Isotopes↗

PubMed1994

Study of natural diamonds by dynamic nuclear polarization-enhanced 13C nuclear magnetic resonance spectroscopy.

The results of a study of two types of natural-diamond crystals by dynamic nuclear polarization (DNP)-enhanced high-resolution solid-state 13C nuclear magnetic resonance (NMR) are reported. The home-built DNP magic-angle spinning (MAS) 13C NMR spectrometer operates at 54 GHz for electrons and 20.2 MHz for carbons. The power of the microwave source was about 30 W and the highest DNP enhancement factor came near to 10(3). It was shown that in the MAS spectra the 13C NMR linewidths of the Ib-type diamond were broader than those of IaB3-type diamond. From the hyperfine structure of the DNP enhancement as a function of frequency, four kinds of nitrogen-centred and one kind of carbon-centred free radicals could be identified in the Ib-type diamond. The hyperfine structures of the DNP enhancement curve that originated from the anisotropic hyperfine interaction between electron and nuclei could be partially averaged out by MAS. The 13C polarization time of DNP was rather long, i.e. 1500 s, and the spin-lattice relaxation time (without microwave irradiation) was about 300 s, which was somewhat shorter than anticipated. Discussions on these experimental results have been made in this report.

Diamond↗

PubMed2005

Discrimination of metamorphic diamond populations by Raman spectroscopy (Kokchetav, Kazakhstan).

Metamorphic diamond is a powerful but frequently debated indicator for ultrahigh-pressure metamorphic (UHPM) conditions. Because of their small size, their optical identification needs confirmation. Characteristics of chemically extracted microdiamonds from Kokchetav, identified by different analytical methods, are used here for unambiguous in situ identification by Raman microspectroscopy. Differences appear in the diamond spectra and the Raman analytical method is explored as a helpful tool in the discrimination between diamond populations from four different UHPM lithologies of Kokchetav. Not considering the graphite-coated diamond, out of the reach of the laser wavelength used here, the comparison of these Kokchetav Raman spectra may provide additional information in other UHPM studies.

Diamond↗