bluuebunny/crossref_metadata_2025 huggingface dataset:
Nano-Bioceramic Production via Mechano-Chemical Conversion (Ultrasonication)
Authors: Oktar Faik Nüzhet , Agathopoulos Simeon , Ozyegin Lutfiye Sevgi , Turner I.G. , Gunduz O. , Demirkol N. , Brück S. , Ben-Nissan Besim , Samur R. , Kayali E.S. , Aktas Cenk
Published: November 2012

The production of nano-calcium phosphate powders, such as HA (hydroxyapatite), from synthetic chemicals can be expensive and time consuming. The skeleton or shells of sea creatures (e.g. sea urchins, shells, corals) could be an alternative source of materials to produce very fine and even nano-structured calcium phosphate biomaterial powders. Ηydrothermal conversion under very high pressures or methods such as hot-plating (chemical) or ultrasonication (mechano-chemical), have been proposed to transform naturally derived CaCO3, e.g. aragonite, into apatite based materials. The aim of the present work was to prepare inexpensive nano-sized HA and TCP bioceramics powders from a local sea snail shells as a possible raw material for HA/TCP bioceramics. Empty shells of a local sea snail (Nassarius hinia reticulatus) from Marmara Sea, Turkey were collected from a beach near Istanbul. The collected shells were ground to a particle size <75µm. Thermal analyses (DTA/TGA) were performed to determine the exact CaCO3 content and thermal behavior. The raw powder was suspended in an aqueous media which was placed in an ultrasonic bath. The temperature was set at 80°C for 15min. Then, an equivalent (to CaO content) amount of H3PO4 was added drop by drop very gently into the solution. The reaction continued for 8h, following which the liquid component was evaporated off in an incubator at 100°C for 24h. The dried sediment was collected and heat treated at two different temperatures, 400 and 800°C. The morphology of the powders produced was examined using SEM. The crystalline phases were indentified using X-ray analysis. X-ray diffractograms indicated the presence of two calcium phosphate phases, namely HA and whitlockite. SEM observations showed that the powder produced comprised nano-sized particles. FTIR results also indicated the presence of HA and whitlockite structures. The experimental results suggest that Nassariushinia reticulatus shells could be an alternative source for the production of various mono or biphasic calcium phosphates. In this study, local sea snail shells were successfully converted to HA and whitlockite with a simple mechano-chemical (ultrasonic) conversion method without the use of complex hydrothermal methods.
Morphological Control of Hydroxyapatite Particles by Homogeneous Precipitation Method in the Co-Presence of Various Carboxylic Acids
Authors: Shimizu Hideki , Zhuang Zhi , Aizawa Mamoru
Published: November 2012

We focused on the investigation of the influence of carboxylic acid additives on the morphology of hydroxyapatite (Ca10(PO4)6(OH)2, HAp) particles synthesized by a homogeneous precipitation method. Three types of carboxylic acids with different number of carboxyl groups, that is, acetic acid, succinic acid and citric acid, were used as additives to control the nucleation, growth and alignment of HAp crystals. The powder properties of resulting particles were examined by powder X-ray diffractometry, fourier-transform infrared spectroscopy, and scanning electron microscopy. All resulting particles were identified to be single-phase carbonate-containing calcium-deficient HAp. The resulting particles synthesized by using acetic acid as an additive were strip-like morphology. In the case of succinic acid addition, the resulting particles exhibited irregular plate-like or spherical morphology. Wheileas, in the case of citric acid addition, the obtained particles became regular spherical shape. These results indicate the numbers of carboxyl groups of carboxylic acid give an influence of the morphology of the HAp particles.
A New Role for Marine Skeletal Proteins in Regenerative Orthopaedics
Authors: Green David W. , Padula Matthew , Santos Jerran , Chou Joshua , Milthorpe Bruce , Ben-Nissan Besim
Published: November 2012

Use of ready-made marine skeletons is one of the simplest possible remedies to major problems hindering the future development of regenerative orthopaedics- such as, providing a richness of framework designs and now a potentially rich, accessible source of osteopromotive analogues and biomineralisation proteins. It has already been shown that coral and marine sponge skeletons can support self-sustaining musculoskeletal tissues and that extracts of spongin collagen and nacre seashell organic matrices promote bone mineralisation. This should not be surprising given that the pivotal biomineralisation proteins, which orchestrate bone morphogenesis are also found in the earliest calcifying marine organisms. This is because they are representatives of the first molecular components established for calcification, morphogenesis and wound healing. In support of this notion, it has emerged that BMP molecules- the main cluster of bone growth factors for human bone morphogenesis- are secreted by endodermal cells into the developing skeleton. In addition, the regenerative signalling proteins, TGF-b and Wnt-prime targets in bone therapeutics- are also present in early marine sponge development and instrumental to stem cell activation in Cnidarians. Based on this match between vertebrate and invertebrate main developmental proteins, we review the nature and extent of this evolutionary relatedness and use it to support the development of a new strategy, which is to mine selected marine origin organic matrices for novel metabolic, signalling and structural proteins/peptides and protein analogues to apply in regenerative orthopaedics, particularly when using adult stem cells. To support such a proposal we show early stage evidence-gathered in our own laboratory- of the presence of fibrinogen fragments and early osteopromotive effects of a coral organic matrix extract on stem cells. In practice the discovery of new osteopromotive and osteo-accelerant protein analogues will require use of traditional chromatography techniques, osteoactivity assays to hone in on potential proteins of significance and advanced proteomic tools to provide accurate sequencing, determine the mechanisms and molecular pathways involved in osteoactivation and determine the efficiency and effectiveness of marine skeleton-derived protein modulation of the stem cell (MSC) proteome. As more analogues are discovered using proteomic tools, skeletal organic matrices may have ever increasing utility for regenerative orthopaedics.
Simplification of the Synthesis Method for Silicon-Substituted Hydroxyapatite: A Raman Spectroscopy Study
Authors: Harden F.J. , Gibson Iain R. , Skakle J.M.S.
Published: November 2012

The addition of silicon ions to hydroxyapatite (HA) provides a more inorganic bone-like chemical composition compared to stoichiometric HA. It is known to aid the bioactivity of the material and to improve the rates of osseointegration, osteoconduction and bone mineralisation. The literature, however, lacks detailed information regarding each step of the aqueous precipitation procedure to produce silicon-substituted HA (Si-HA). The current work utilised Raman spectroscopy at each stage of the aqueous precipitation method to determine how the silicate is incorporated into the HA structure when producing Si-HA. Raman spectra indicated that at the initial stages of the reaction the disilicate ion (Si2O76-) formed with the orthosilicate (SiO44-) ion becoming more dominant after sintering. The results demonstrated that the form of silicate in the Si-HA aqueous precipitation method can be tracked using Raman spectroscopy.
Positron Annihilation Parameters in Connection to Surface Phenomenon of Liquids
Authors: Ganguly Bichitra Nandi
Published: November 2012

Surface tension is an important property of liquid, the bulk surface tension concept changes considerably when minute volume of a given liquid (drop let radius<10nm) is considered. Although an extensive thermodynamical treatment and theoretical basis have been considered in the past on the curvature dependence of surface tension, yet its experimental evaluation is deemed necessary and it has been shown hither to that positronium annihilation parameters serve faithfully to this purpose. However, the drastic lowering of surface tension with the dispersion of surfactant in the liquid phase display a different phenomenon altogether and has been dealt separately by positron annihilation results.
Location of Phase Boundaries of Lyotropic Liquid Crystal Employing Positron Lifetime Spectroscopy and Electrical Conductivity Measurement
Authors: Yadav Ramesh , Singh K. Chandramani , Choudhary S.R. , Jain P.C.
Published: November 2012

Different compositions of surfactant systems give rise to a rich variety of structures of aggregates. At higher concentrations of surfactant in water, the surfactant molecules aggregate to form lyotropic liquid crystals [1]. In the present work we have prepared two surfactant systems consisting of (i) 20% of cetyl-trimethyl-ammonium-bromide (CTAB) in water, and (ii) 30% of tetra-decyl-trimethyl-ammonium-bromide (TTAB) in water. Both the systems exhibit various lyotropic liquid crystal structures when an increasing amount of co-surfactant is added as third component [2, 3]. These liquid crystalline structures are very sensitive to the solution conditions such as co-surfactant concentration, temperature, ionic strength, counter ion polarizability etc. In this study, positron life time spectroscopy and conductivity measurement have been employed to locate various phases exhibited by the lyotropic liquid crystals. In addition to delineating various phase boundaries of the systems, positron annihilation technique has also yielded new findings.
Positron and Charged Ion Diffusion and the Effective Interactions in the Liquid Phase
Authors: Yamada Kouhei , Saito Makoto , Suzuki H. , Kanazawa Ikuzo
Published: November 2012

We have discussed the origin of the attractive interactions between like charged ions in the liquid phase, by using the theoretical formula, which explains an anomalous diffusion mechanism of positrons in the liquid phase. It is suggested strongly that the attractive interactions are attributed to exchange interactions of the massive gauge fields between like charged ions.
Effect of Hydrophilicity of the Sidechains on the Amorphous Structure of Polypropylene Derivatives Studied by Positronium Lifetime Measurements
Authors: Ito Kenji , Hagihara Hideaki , Kobayashi Yoshinori
Published: November 2012

Polypropylene (PP) derivatives, prepared with different α-olefin comonomers of hexane and hexenol, were investigated using the positron annihilation lifetime technique. The free-volume hole sizes for the present polymers were quantified from the long-lived ortho-positronium (o-Ps) lifetimes. In contrast to the case of nonpolar, introduction of the polar hexenol into PP reduced the o-Ps lifetimes and the hole sizes derived from them. This indicates that the interchain interaction due to the hydrogen bonds in the amorphous region is much stronger than the enhancement of the segmental motion due to the butyl long branch. A comparison of the o-Ps lifetimes with the corresponding tensile strength suggested significant contribution of the subnanostructure in the amorphous region to the mechanical property.
Positronium Lifetime Study on Subnanoscopic Structure of Polyrotaxane
Authors: Ito Kenji , Zhao Chang Ming , Ito Kohzo , Kobayashi Yoshinori
Published: November 2012

The subnanoscopic structures of polyrotaxanes, prepared from α-cyclodextrins, poly(ethylene glycol), and bulky adamantane end groups, were examined by means of the positron annihilation lifetime technique, in consideration of the free-volume hole, quantified from the long-lived ortho-positronium (o-Ps) lifetimes. The influence of the chemical structure on the temperature dependence of the o-Ps lifetimes are discussed.
Towards the Positronium and Radiolytic Hydrogen Formation Mechanisms in Liquid Hydrocarbons
Authors: Byakov Vsevolod , Stepanov Sergey V.
Published: November 2012

Ps and radiolytic hydrogen yields anticorrelate in saturated hydrocarbons when molecular structure changes from a normal to a cyclic form. This fact is explained by much higher mobility of primary radical-cations in cyclic hydrocarbons than in normal ones.
Positron Lifetime at Deep Donors of Radiation Origin in Proton - Irradiated FZ-Silicon Single Crystals
Authors: Arutyunov Nikolai Yu. , Elsayed Mohamed , Krause-Rehberg Reinhard , Emtsev Valentin V. , Oganesyan Gagik A. , Kozlovski Vitalii V.
Published: November 2012

The recovery of shallow donor states of the atoms of phosphorus in n-FZ-Si:P material irradiated at the room temperature with 15 MeV protons was studied in the course of isochronal annealing. This process was investigated by the positron annihilation lifetime (PAL) spectroscopy and by low-temperature electrical measurements. The positron traps of a vacancy type manifesting themselves as deep donors have been revealed. These defects begin to anneal at ~ 593 K– 613 K; roughly estimated activation energy of the process is Ea ≈ 0.59 eV under the first order of reaction. The results suggest the involvement, at least, of one vacancy and the impurity atom of phosphorus in the microstructure of the deep donor.
Evidence of the Participation of Electronic Excited States in the Mechanism of Positronium Formation in Substitutional Tb1-xEux(dpm)3 Solid Solutions Studied by Optical and Positron Annihilation Spectroscopies
Authors: Magalhães Welington F. , Fulgêncio Fernando , de Oliveira Fernando C. , Windmöller Dario , Machado José C. , Brito Hermi F. , Malta Oscar L. , de Sá Gilberto F.
Published: November 2012

Positron annihilation lifetime (PALS) and photoluminescence spectroscopies measurements were performed in Tb(III) and Eu(III) dipivaloylmethanates, Tb(dpm)3 and Eu(dpm)3, and also on their binary solid solutions of general formula Tb1-xEux(dpm)3. A correlation between the 5D4 Tb(III) energy level lifetime and the positronium formation probability was observed, indicating that the ligand-to-metal charge transfer LMCT states act in both luminescence quenching and positronium formation inhibition. From these results, a new model is proposed, showing that excited electronic states have a relevant role in the positronium formation mechanism.
Positronium Formation and Decay in Organic Scintillators for Neutrino Detection
Authors: Consolati Giovanni , Franco D. , Trezzi D.
Published: November 2012

The detection of electron anti-neutrinos is generally carried out by searching for the coincidence of the reaction products, neutron and positron, in liquid scintillators. However, in these last a positron may form positronium (Ps) with an electron of the medium; efficiency of the process may be high. Furthermore, the triplet ground state sublevel (o-Ps) has lifetimes of a few ns. These features introduce distortions in the time distribution of the emitted photons, which is essential for position reconstruction and pulse shape discrimination algorithms in anti-neutrino experiments. This drawback can be favorably exploited by using o-Ps as a probe to detect anti-neutrinos in the scintillator. We report results of positron annihilation lifetime measurements in some organic liquid scintillators used for neutrino experiments. The o-Ps induced distortion of the scintillation photon emission time distribution may enhance the anti-neutrino detection.
Sealed 22Na Sources for Positron Annihilation Lifetime Spectroscopy
Authors: Yamawaki Masato , Kobayashi Yoshinori , Ito Kenji , Matsumoto Mikio , Ishizu Hidetake , Umino Akiyo , Hattori Kanehisa , Watanabe Yoshihiro
Published: November 2012

Sealed radioactive sources of 22Na for positron annihilation lifetime spectroscopy (PALS), free from the legal regulations, are commercially available from an American company. However, thick foils are used to seal 22Na in these sources and large fractions of the positrons annihilate in the sealing materials. Further, it is pointed out that a long lifetime component over 1 ns appears in the positron lifetime spectrum acquired with the Kapton sealed source (POSK-22, IPL Inc.). In this research, attempts were made to develop high quality sealed positron sources, potentially free from regulations, for ubiquitous application of PALS. The sources prepared in the present work are of high quality and applicable to our new PALS, which does not require sample cutting and is potentially applicable to truly nondestructive, onsite inspection of various materials
Layer Structures of Composite Membranes for Water Filtration Elucidated by Variable-Energy Positron Annihilation
Authors: Chen Zhe , Ito Kenji , Yanagishita Hiroshi , Oshima Nagayasu , Suzuki Ryoichi , Kobayashi Yoshinori
Published: November 2012

Commercial composite membranes for water purification were studied by means of the variable-energy positron annihilation γ-ray technique. The positron incident energy E dependence of R parameter (3γ/2γ ratio) analyzed from positron annihilation γ-ray spectra revealed the layer structure consisting of a dense top layer and a porous substrate for the membranes. Thickness of the dense layer for each membrane was evaluated from the R(E) based on a positron implantation stopping profile.
“In Situ” Observation of Crystallization in Propylene Carbonate, Salol and M-Toluidine
Authors: Majerník Viktor , Krištiak Jozef , Šauša Ondrej , Iskrová-Miklošovičová Martina
Published: November 2012

Positron annihilation lifetime measurements have been performed on three molecular systems: propylene carbonate, salol and m-toluidine at the temperature range from 20 K up to 300 K. The time dependences of the orthopositronium lifetime and intensity have been observed at the temperature range between a solid state and the liquid state. These changes can be explained as transitions from the amorphous phase to one or two crystalline phases. The crystallization process from cooled liquid was observed in all three cases at different temperatures on the time scale up to 60 hours.
Crystal Structure and Twinning of Rb3Mo14O22
Authors: Hainz Markus , Boller Herbert
Published: November 2012

Rb3Mo14O22 has been prepared and its crystal structure determined: S.G.: P21/c (No.14), a = 10.462(7), b = 9.414(2), c = 9.956(5) Ǻ, β = 103.73(2)°, Z = 2, R = 0.046. It is isotypic to K3Mo14O22. The crystal structure can be described as a substitutional derivative of a ccp close packing of oxygen and rubidium atoms with interspersed Mo14O34 units having a core of three trans-edge condensed molybdenum octahedra. The observed multiple twinning is explained by this structural model. A bond valence analysis is presented.
Electrical and Magnetic Properties of CuEu2W2O10 and Cu3Eu2W4O18
Authors: Urbanowicz Piotr , Tomaszewicz Elzbieta , Groń Tadeusz , Duda Henryk , Mazur Slawomir , Kukuła Zenon , Pawlus Sebastian , Mydlarz Tadeusz , Krok Kowalski Józef
Published: November 2012

Magnetic susceptibility measurements showed both a weak response to magnetic field and a lack of the Curie-Weiss region for CuEu2W2O10 and Cu3Eu2W4O18 tungstates characteristic for the multiplet widths comparable to thermal energy. Magnetization measurements displayed the linear temperature dependence with the lower magnetic moment for Cu3Eu2W4O18 in comparison with CuEu2W2O10, indicating that the effect of the electric charges associated with the surrounding ligands can change the multiplet width of individual states. It is affecting the electrical properties of examined tungstates which reveal the insulating state and low relative permittivity εr ~ 29 in case of CuEu2W2O10 and the thermally activated p-type electrical conduction for Cu3Eu2W4O18 with the activation energy of 1.11 eV and the large value of εr ~ 217 above the room temperature.
Influence of Ti Substitution on the Critical Properties of CuxCryTizSe4 (z = 0.24 and 0.35)
Authors: Krok-Kowalski Józef , Władarz Grzegorz , Rduch Paweł , Malicka Ewa , Groń Tadeusz , Guzik Adam
Published: November 2012

Magnetization, M, and susceptibility, , measurements of CuxCryTizSe4 (z = 0.24 and 0.35) showed both strong lowering of magnetic moment in comparison with CuCr2Se4 matrix and zero-field-cooling (ZFC) – field-cooling (FC) susceptibility splitting characteristic for the spin-glass (SG) behaviour. Isothermal magnetization curves, M(H), easy saturate and large both the Curie (TC ~ 250 K) and Curie-Weiss (θCW ~ 280 K) temperatures indicate the ferromagnetic order which coexists with the SG state. The critical behaviour of polycrystalline CuxCryTizSe4 spinels investigated around the paramagnetic–ferromagnetic (PM-FM) phase transition revealed that the values of critical exponents are close to those predicted by the mean field model for long-range interactions only for Cu1.02Cr1.77Ti0.24Se4. It means that the larger spin frustration the more difficulty is it to describe the critical properties with the aid of the theoretical models.
Band Structure Calculations for (Ni1-XCux)2MnGa Heusler Alloys
Authors: Goraus Jerzy , Kolano-Burian Aleksandra , Hawełek Łukasz
Published: November 2012

Ni2MnGa alloy exhibits significant magnetocaloric effect due to structural and magnetic transition, which take place at similar temperature range. In this report we present band structure calculations for Ni2MnGa doped with Cu performed within KKR-CPA scheme. We also calculated the estimated temperature of the magnetic transition as a function of dopant concentration within Mean-Field-Approach (MFA). Our calculations show that the Curie temperature increases with Cu doping in agreement with recent experimental data.
Structural and Electronic Properties of ScC and NbC: A First Principles Study
Authors: Abdel Rahim Gladys Patricia , Rodríguez Jairo Arbey
Published: November 2012

We study the structural and electronic properties of scandium carbide ScC and niobium carbide NbC in both the sodium chloride rock salt (NaCl) and wurtzite structures by means of accurate first principles total energy calculations. The calculations were performed employing the full-potential linearized plane wave method (FP-LAPW). We used the generalized gradient approximation (GGA) of Perdew Burke and Ernzerhof for the exchange and correlation potential. Volume optimization and density of states including spin (DOS) of the systems are presented.
A Density Functional Theory Study of the Fe(001)/Fe3O4(001) Interface
Authors: Shikhman Irina A. , Shelyapina Marina G. , Kupriyanova Galina S.
Published: November 2012

Magnetite is a very promising candidate for hard electrode in magnetic tunnel junction devices due to its electronic and magnetic properties. Addition of a buffer iron layer improves required properties. Here we report on the results of our DFT study of the impact of the additional Fe buffer layer on the electronic and magnetic properties of magnetite.
The Influence of Ce on the Electrical Resistivity and Electronic Structure in the Gd1-xCexIn3 Compounds
Authors: Bajorek Anna , Chełkowska Grażyna , Chrobak Artur , Kwiecień Grudziecka Marzena
Published: November 2012

All studied Gd1-xCexIn3 compounds crystallize in the cubic AuCu3 - type of crystal structure. The influence of Gd/Ce substitution is reflected in the linear increase of the unit cell parameter. The temperature dependence of the electrical resistivity ρ(T) strongly depends on the Ce content. For compounds with x≤0.2 a typical metallic behavior has been observed. In contrary, for Ce-rich compounds (x≥0.5) a characteristic Kondo-type behaviour has been noticed. The analysis of cerium XPS core level lines reveals the occurrence of possible Ce intermediate valence.
RNi9In2 (R= Pr, Nd, Eu) Compounds and their Hydrides
Authors: Bigun Inna , Dzevenko Mariya , Havela Ladislav , Kalychak Yaroslav
Published: November 2012

RNi9In2 and their hydrides crystallize in the YNi9In2 structure type. Low pressure hydrogenation leads to absorption of 1.5-3.4 H/f.u. RNi9In2 (R= Pr, Nd, Eu) as well as PrNi9In2H1.7 and NdNi9In2H1.5 exhibit Curie-Weiss behaviour in the 2-300 K temperature range. EuNi9In2 reveals ferromagnetism below approximately 40 K, which may be due to a secondary phase. Its hydride is Pauli paramagnet, indicating Eu3+ state. RNi9In2 (R= Pr, Nd) as well as PrNi9In2H1.7 and NdNi9In2H1.5 exhibit Curie-Weiss behaviour and lack of magnetic ordering down to T = 2 K.
Thermodynamic Properties of RZnSn2 (R = Y, Er, Lu) Compounds with HfCuSi2 Structure Type
Authors: Łątka Kazimierz , Przewoźnik Janusz , Verbovytskyy Yury , Gonçalves Antonio Pereira
Published: November 2012

The results of magnetic and specific heat studies are reviewed and discussed for the series of RZnSn2 (R = Y, Er and Lu) compounds crystallizing in the same tetragonal HfCuSi2 - type of structure. A sharp peak in the specific heat of ErZnSn2 compound is indicative for magnetic ordering of Er moments at 5.0 K, being in agreement with its established antiferromagnetic nature. The estimated magnetic entropy Smagn contribution is less than that expected for the ground state J = 15/2 multiplet of Er3+.
An 166Er-Mossbauer Investigation of ErNiAl4
Authors: Ryan Dominic H. , Lee Hone Nicholas , Stewart Glen A.
Published: November 2012

A low temperature 166Er-Mössbauer spectroscopy investigation of ErNiAl4 reveals that the Er3+ ion’s ground state Kramers doublet has ¦Jz¦ just 8% less than the fully-stretched value of J = 15/2. The persistence of a magnetically-split spectrum to well above TN = 5.8 K is consistent with Orbach type paramagnetic relaxation that proceeds via the third excited crystal field level.
Allogeneic Stem Cell Transplantation in Acute Myeloid Leukemia
Authors: Ali Natasha , Adil Salman Naseem , Shaikh Mohammad Usman , Masood Nehal
Published: November 2012

We report a case series of 12 patients with acute myeloid leukemia who underwent allogeneic stem cell transplant with a matched related donor. Male to female ratio was 1:1. The main complication post-transplant was graft-versus-host disease (n = 7 patients). Transplant-related mortality involved one patient; cause of death was multi-organ failure. After a median follow up of 36.0 ± 11.3 months, overall survival was 16%.
Erratum to the Paper “A Lower Bound for the Length of Closed Geodesics on a Finsler Manifold”
Authors: Zhao Wei
Published: November 2012

We correct two clerical errors made in the paper ”A Lower Bound for the Length of Closed Geodesics on a Finsler Manifold”.
Effects of Toothbrushing with Fluoride Abrasive and Whitening Dentifrices on Both Unbleached and Bleached Human Enamel Surface in Terms of Roughness and Hardness: An in vitro Study
Authors: Bolay Sukran , Cakir Filiz Yalcin , Gurgan Sevil
Published: November 2012

Aim

The aim of this in vitro study was to evaluate the surface roughness and hardness of both unbleached and bleached (opalescence; 10% carbamide peroxide) human enamel brushed with water (without dentifrice), fluoride abrasive dentifrice (Colgate Total) and whitening dentifrice (Natural White).

Materials and methods

Human enamel samples were obtained from third molars and randomly divided into five groups (n = 8): G1—Control (brushed with water without dentifrice), G2—Colgate Total (fluoride abrasive dentifrice), G3—Natural White (whitening dentifrice), G4—Opalescence (10% carbamide peroxide) and then brushed with Colgate Total, G5— Opalescence (10% carbamide peroxide) and then brushed with Natural White. Bleaching regimen was applied according to manufacturers’ instructions. The brushing process was performed with a modified Nyffenegger's brushing machine. Surface roughness was analyzed with a profilometer. Microhardness testing was performed with a Brinell hardness tester.

Results

Results were statistically analyzed by Kruskal-Wallis, one-way ANOVA analysis and Mann-Whitney U, Wilcoxon matched-pairs signed-ranks tests. There were significant differences in surface roughness values for all groups, which showed an increase in roughness (p < 0.05). When the bleaching treatment combined with brushing with whitening dentifrice was performed (G5), there was a significant decrease in hardness values (p < 0.05). The other groups (G1, G2, G3, G4) showed no significant hardness differences (p > 0.05).

Conclusion

It was concluded that toothbrushing procedures increased the enamel surface roughness, and that bleaching regimen performed with cleaning treatment, through brushing with whitening dentifrice decreased hardness values.

Clinical significance

When applied together, bleaching and cleaning treatments may alter the enamel surface roughness and hardness values.

How to cite this article

Bolay S, Cakir FY, Gurgan S. Effects of Toothbrushing with Fluoride Abrasive and Whitening Dentifrices on Both Unbleached and Bleached Human Enamel Surface in Terms of Roughness and Hardness: An in vitro Study. J Contemp Dent Pract 2012;13(5):584-589.
Evaluation of Elongated Styloid Process on Digital Panoramic Radiographs
Authors: Roopashri G , Vaishali MR , David Maria Priscilla , Baig Muqeet , Shankar Uma
Published: November 2012

Background and objective

The elongated styloid process may produce characteristic head and neck pain syndromes, commonly known as Eagle's syndrome. An awareness of this syndrome is important to all health practitioners involved in the diagnosis and treatment of neck and head pain. It has been estimated that 2 to 28% of the general adult population has radiographic appearance of elongated styloid process.

The objective of the study was to assess the elongation of styloid process on digital panoramic radiographs and to evaluate the prevalence of elongation according to age, sex and types.

Results

Elongated styloid process was seen in 107 subjects out of 300 patients who were aged between 10 and 70 years old. Our study revealed that as age increased elongation of styloid process increased with female predominance. Type 1 elongation was most common than the other types of elongation. We also found that left styloids were elongated than the right with bilateral elongation.

Conclusion

Panoramic radiographs can show a correct picture of elongated styloid process which can confirm the diagnosis and can thus help avoid misinterpretation of the symptoms as tonsillar pain or pain of dental, pharyngeal or muscular origin and hence panoramic radiography is economical and the best imaging modality to view the elongation of styloid process.

How to cite this article

Roopashri G, Vaishali MR, David MP, Baig M, Shankar U. Evaluation of Elongated Styloid Process on Digital Panoramic Radiographs. J Contemp Dent Pract 2012;13(5):618-622.
Comparison of Microleakage of Composite Restorations using Fifth and Sixth Generation Dentin Bonding Agent: An in vivo Study
Authors: Samimi Pooran , Barekatain Mehrdad , Alaei Samaneh
Published: November 2012

Introduction

The success of bonded restorations depends on effective bonding between restorative materials and tooth structure, and it prevents microleakage. New dentin bonding systems have been introduced which promotes this concept. The aim of this study was to compare the amount of microleakage between ‘single bond’ vs ‘Prompt L-Pop’ during different time periods.

Materials and methods

In this clinical trial study, 60 nonretentive class five cavities were prepared on buccal surfaces of human premolars which were scheduled to be removed for orthodontic purposes. The cavities were restored using two different bonding agents; fifth generation (Single Bond) and sixth generation (Prompt L-Pop) and then filled with resin composite (Filtek Z-250). The samples in both groups were extracted after placing the restoration in three periods of time: Immediately, 1 week and 6 months postplacement. Specimens were sealed with two layers of nail varnish except for 1 mm around restoration and immersed in a silver nitrate solution for 24 hours. The teeth were then sectioned longitudinally and the degree of microleakage was determined by stereomicroscope based on standard usual criteria.

Results

Single bond showed more leakage at dentin margin than enamel margin in all three extraction periods and differences were significant among three groups (p < 0.05). In samples which were restored with Prompt L-Pop only in groups of 6 months there were significant differences between enamel and dentin margins. At enamel margin there were no significant differences between microleakage of groups according to the passage of time (p > 0.05).

Conclusion

The results of this study using two different bonding systems, indicate that adhesion to enamel was more valuable than dentin and perhaps systems that include self-etching primers are less sensitive to remaining moisture on dentin and they are less affected during different time periods.

How to cite this article

Samimi P, Barekatain M, Alaei S. Comparison of Microleakage of Composite Restorations using Fifth and Sixth Generation Dentin Bonding Agent: An in vivo Study. J Contemp Dent Pract 2012;13(5):632-636.
Anterior Restorations in Bleached Teeth: Difficulty Establishing the Color after Bleaching
Authors: Santezi Carolina , Tonetto Mateus Rodrigues , Presoto Cristina Dupim , Jassé Fernanda Ferreira , de Oliveira Júnior Osmir Batista , de Andrade Marcelo Ferrarezi , de Toledo Leonardo Renato
Published: November 2012

It is becoming more common for patients to look for cosmetic procedures in dental offices. The search for lost or desired esthetics by patients is increasingly frequent and the professional must be able to meet this demand. To do this, dentists not only need to return the tooth back to its normal functioning state but also promote esthetic excellence. In this context, the association of cosmetic procedures, such as teeth whitening and restorative procedures, such as direct adhesive restorations is very common. The composite resins employed nowadays allow the reproduction of various optical properties of natural teeth. With these composite resins, it is possible to reproduce features such as translucency, opacity and specific features of the dental element, to bring back the esthetic harmony of the smile. This article reports a clinical case demonstrating the placement, in a stratified manner, of composite resins in bleached teeth, as well as the reproduction of optical and natural aspects of the teeth. In order to achieve esthetic and functional success of the restored procedure, it is important to be familiar with the new techniques and new materials in the market and above all, we must know when and where to use them.

How to cite this article

Santezi C, Tonetto MR, Presoto CD, Jassé FF, de Oliveira OB Junior, de Andrade MF, de Toledo Leonardo R. Anterior Restorations in Bleached Teeth: Difficulty Establishing the Color after Bleaching. J Contemp Dent Pract 2012;13(5):735-739.
Stratospheric ozone interannual variability (1995–2011) as observed by Lidar and Satellite at Mauna Loa Observatory, HI and Table Mountain Facility, CA
Authors: Kirgis G. , Leblanc T. , McDermid I. S. , Walsh T. D.
Published: November 2012

Abstract. The Jet Propulsion Laboratory (JPL) lidars, at the Mauna Loa Observatory, Hawaii (MLO, 19.5° N, 155.6° W) and the JPL Table Mountain Facility (TMF, California, 34.5° N, 117.7° W), have been measuring vertical profiles of stratospheric ozone routinely since the early 1990's and late-1980s respectively. Interannual variability of ozone above these two sites was investigated using a multi-linear regression analysis on the deseasonalized monthly mean lidar and satellite time-series at 1 km intervals between 20 and 45 km from January 1995 to April 2011, a period of low volcanic aerosol loading. Explanatory variables representing the 11-yr solar cycle, the El Niño Southern Oscillation, the Quasi-Biennial Oscillation, the Eliassen–Palm flux, and horizontal and vertical transport were used. A new proxy, the mid-latitude ozone depleting gas index, which shows a decrease with time as an outcome of the Montreal Protocol, was introduced and compared to the more commonly used linear trend method. The analysis also compares the lidar time-series and a merged time-series obtained from the space-borne stratospheric aerosol and gas experiment II, halogen occultation experiment, and Aura-microwave limb sounder instruments. The results from both lidar and satellite measurements are consistent with recent model simulations which propose changes in tropical upwelling. Additionally, at TMF the ozone depleting gas index explains as much variance as the Quasi-Biennial Oscillation in the upper stratosphere. Over the past 17 yr a diminishing downward trend in ozone was observed before 2000 and a net increase, and sign of ozone recovery, is observed after 2005. Our results which include dynamical proxies suggest possible coupling between horizontal transport and the 11-yr solar cycle response, although a dataset spanning a period longer than one solar cycle is needed to confirm this result.
Ground-based integrated path coherent differential absorption lidar measurement of CO2: hard target return
Authors: Ishii S. , Koyama M. , Baron P. , Iwai H. , Mizutani K. , Itabe T. , Sato A. , Asai K.
Published: November 2012

Abstract. The National Institute of Information and Communications Technology (NICT) have made a great deal of effort to develop a coherent 2-μm differential absorption and wind lidar (Co2DiaWiL) for measuring CO2 and wind speed. First, coherent Integrated Path Differential Absorption (IPDA) lidar experiments were conducted using the Co2DiaWiL and a hard target (surface return) located about 7.12 km south of NICT on 11, 27, and 28 December 2010. The detection sensitivity of a 2-μm IPDA lidar was examined in detail using the CO2 concentration measured by the hard target. The precisions of CO2 measurement for the hard target and 900, 4500 and 27 000 shot pairs were 6.5, 2.8, and 1.2%, respectively. The results indicated that a coherent IPDA lidar with a laser operating at a high pulse repetition frequency of a few tens of KHz is necessary for measuring the CO2 concentration of the hard target with a precision of 1–2 ppm. Statistical comparisons indicated that, although a small amount of in situ data and the fact that they were not co-located with the hard target made comparison difficult, the CO2 volume mixing ratio measured with the Co2DiaWiL was about 5 ppm lower than that measured with the in situ sensor. The statistical results indicated that there were no differences between the hard target and atmospheric return measurements. A precision of 1.5% was achieved from the atmospheric return, which is lower than that obtained from the hard-target returns. Although long-range DIfferential Absorption Lidar (DIAL) CO2 measurement with the atmospheric return can result in highly precise measurement, the precision of the atmospheric return measurement was widely distributed comparing to that of the hard target return. Our results indicated that it is important to use a Q-switched laser to measure the range-gated differential absorption optical depth with the atmospheric return and that it is better to simultaneously conduct both hard target and atmospheric return measurements to enable highly accurate CO2 measurement.
FMCW sparse array imaging and restoration for microwave gauging
Authors: Kolb S. , Stolle R.
Published: November 2012

Abstract. The application of imaging radar to microwave level gauging represents a prospect of increasing the reliability of target detection. The aperture size of the used sensor determines the underlying azimuthal resolution. In consequence, when FMCW-based multistatic radar (FMCW: frequency modulated continuous wave) is used, the number of antennas dictates this essential property of an imaging system. The application of a sparse array leads to an improvement of the azimuthal resolution by keeping the number of array elements constant with the cost of increased side lobe level. Therefore, ambiguities occur within the imaging process. This problem can be modelled by a point spread function (PSF) which is common in image processing. Hence, an inverse system to the imaging system is needed to restore unique information of existing targets within the observed radar scenario. In general, the process of imaging is of ill-conditioned nature and therefore appropriate algorithms have to be applied. The present paper first develops the degradation model, namely PSF, of an imaging system based on a uniform linear array in time domain. As a result, range and azimuth dimensions are interdependent and the process of imaging has to be reformulated in one dimension. Matrix-based approaches can be adopted in this way. The second part applies two computational methods to the given inverse problem, namely quadratic and non-quadratic regularization. Notably, the second one exhibits an ability to suppress ambiguities. This can be demonstrated with the results of both, simulations and measurements, and enables sparse array imaging to localize point targets more unambiguously.
Late Neolithic Mondsee Culture in Austria: living on lakes and living with flood risk?
Authors: Swierczynski T. , Lauterbach S. , Dulski P. , Brauer A.
Published: November 2012

Abstract. Neolithic and Bronze Age lake-dwellings in the European Alps became recently protected under the UNESCO World Heritage. However, only little is known about the cultural history of the related pre-historic communities, their adaptation strategies to environmental changes and particularly about the almost synchronous decline of many of these settlements around the transition from the Late Neolithic to the Early Bronze Age. For example, there is an ongoing debate whether the abandonment of Late Neolithic lake-dwellings at Lake Mondsee (Upper Austria) was caused by unfavourable climate conditions or a single catastrophic event. Within the varved sediments of Lake Mondsee we investigated the occurrence of intercalated detrital layers from major floods and debris flows to unravel extreme surface runoff recurrence during the Neolithic settlement phase. A combination of detailed sediment microfacies analysis and μXRF element scanning allows distinguishing debris flow and flood deposits. A total of 60 flood and 12 debris flow event layers was detected between 4000 and 7000 varve yr BP. Compared to the centennial- to millennial-scale average, a period of increased runoff event frequency can be identified between 4450 and 5900 varve yr BP. Enhanced flood frequency is accompanied by predominantly siliciclastic sediment supply between 5000 and 5500 varve yr BP and enhanced dolomitic sediment supply between 4500 and 5000 varve yr BP, revealing a change from regional floods to more local runoff events. Interestingly, during the interval of highest flood frequency a change in the location and the construction technique of the Neolithic lake-dwellings at Lake Mondsee can be observed. While lake-dwellings of the first settlement phase (ca. 5750–5200 cal. yr BP) were constructed on wetlands, later constructions (ca. 5400–4650 cal. yr BP) were built on piles upon the water, possibly indicating an adaptation to either increased flood risk or a general increase of the lake-level. However, also other than climatic factors (e.g. socio-economic changes) must have influenced the decline of the Mondsee Culture because flood activity generally decreased since 4450 varve yr BP, but no new lake-dwellings have been established thereafter.
A numerical study of the Southern Ocean including a thermodynamic active ice shelf – Part 1: Weddell Sea
Authors: Meccia V. , Wainer I. , Tonelli M. , Curchitser E.
Published: November 2012

Abstract. There is a great amount of uncertainty regarding the understanding of the atmosphere-ocean-cryosphere interactions in the Southern Ocean despite the role that the region plays in our changing climate. With the aim of studying the relative importance of sea-ice and ice shelf processes in the Southern Ocean, a coupled ocean circulation sea-ice/ice shelf cavity model based on the Regional Ocean Model System (ROMS) is used in a periodic circumpolar domain with enhanced resolution in the Weddell Sea. A hierarchy of numerical experiments is performed where first a sea-ice model is used and then an ice shelf thermodynamic parameterization is included in order to evaluate the improvements resulting from each component. Results show that it is necessary to consider the formation and melting of sea-ice in order to adequately reproduce the observed hydrography and circulation. Inclusion of ice shelves cavities in the model only improves results if the ice shelf-ocean thermodynamic fluxes are active. Ice shelves and ocean interactions are an important process to be considered in order to obtain realistic hydrographic values under the ice shelf. The model framework presented in this work is a promising tool for analyzing the Southern Ocean response to future climate change scenarios.
Groundwater-surface water interactions, vegetation dependencies and implications for water resources management in the semi-arid Hailiutu River catchment, China – A synthesis
Authors: Zhou Y. , Wenninger J. , Yang Z. , Yin L. , Huang J. , Hou L. , Wang X. , Zhang D. , Uhlenbrook S.
Published: November 2012

Abstract. During the last decades, large scale land use changes took place in the Hailiutu River catchment, a semi-arid area in northwest China. These changes had significant impacts on the water resources in the area. Insights into groundwater and surface water interactions and vegetation-water dependencies help to understand these impacts and formulate sustainable water resources management policies. In this study, groundwater and surface water interactions were identified using the baseflow index at the catchment scale, and hydraulic and temperature methods as well as event hydrograph separation techniques at the sub-catchment scale. The results show that almost 88% of the river discharge consists of groundwater. Vegetation dependencies on groundwater were analyzed from the relationship between the Normalized Difference Vegetation Index (NDVI) and groundwater depth at the catchment scale and along an ecohydrogeological cross-section, and by measuring the sap flow of different plants, soil water contents and groundwater levels at different research sites. The results show that all vegetation types, i.e. trees (willow (Salix matsudana) and poplar (Populus simonii)), bushes (salix (Salix psammophila)) and agricultural crops (maize (Zea mays)), depend on groundwater as the dominant water source for transpiration. The comparative analysis indicates that maize crops use the largest amount of water, followed by poplar trees, salix bushes, and willow trees. For sustainable water use with the objective of satisfying water demand for socio-economical development and to prevent desertification, more water use efficient crops such as sorghum, barley and millet should be promoted to reduce the consumptive water use for irrigation. Willow trees should be used as wind-breaks in croplands and along roads, and dry resistant and less water use intensive plants (for instance native bushes) should be used to vegetate sand dunes.