In vitro investigation of friction at the interface between bone and a surgical instrument.

PubMed

Parekh, Jugal; Shepherd, Duncan E T; Hukins, David W L; Hingley, Carl; Maffulli, Nicola

2013-06-01

This study investigated the friction between surgical instruments and bone to aid improvements to instrument design. The bases of orthopaedic surgical instruments are usually made of metal, especially stainless steel. Silicone elastomer was chosen as an alternate biocompatible material, which would be compliant on the bone surface when used as the base of an instrument. The coefficient of static friction was calculated at the bone/material interface in the presence of a synthetic solution that had a comparable viscosity to that of blood, to assess the friction provided by each base material. Three types of silicone elastomers with different hardnesses (Shore A hardness 23, 50 and 77) and three distinct stainless steel surfaces (obtained by spark erosion, sand blasting and surface grinding) were used to assess the friction provided by the materials on slippery bone. The bone specimens were taken from the flattest region of the femoral shaft of a bovine femur; the outer surfaces of the specimens were kept intact. In general, the stainless steel surfaces exhibited higher values of coefficient of static friction, compared to the silicone elastomer samples. The stainless steel surface finished by spark erosion (surface roughness Ra  = 8.9 ± 1.6 µm) had the highest coefficient value of 0.74 ± 0.04. The coefficient values for the silicone elastomer sample with the highest hardness (Dow Corning Silastic Q7-4780, Shore A hardness 77) was not significantly different to values provided by the stainless steel surface finished by sand blasting (surface roughness Ra  = 2.2 ± 0.1 µm) or surface grinding (surface roughness Ra  = 0.1 ± 0.0 µm). Based on the results of this study, it is concluded that silicone could be a potentially useful material for the design of bases of orthopaedic instruments that interface with bone.

The effect of thermocycling on the fracture toughness and hardness of core buildup materials.

PubMed

Medina Tirado, J I; Nagy, W W; Dhuru, V B; Ziebert, A J

2001-11-01

Thermocycling has been shown to cause surface degradation of many dental materials, but its effect on the fracture toughness and hardness of direct core buildup materials is unknown. This study was designed to determine the effect of thermocycling on the fracture toughness and hardness of 5 core buildup materials. Fifteen specimens were prepared from each of the following materials: Fluorocore, VariGlass VLC, Valiant PhD, Vitremer, and Chelon-Silver. American Standard for Testing Materials guidelines for single-edge notch, bar-shaped specimens were used. Ten specimens of each material were thermocycled for 2000 cycles; the other 5 specimens were not thermocycled. All specimens were subjected to 3-point bending in a universal testing machine. The load at fracture was recorded, and the fracture toughness (K(IC)) was calculated. Barcol hardness values were also determined. Data were analyzed with 1-way analysis of variance and compared with the Tukey multiple range test (P<.05). Pearson's correlation coefficient was also calculated to measure the association between fracture toughness and hardness. Fluorocore had the highest thermocycled mean K(IC) and Valiant PhD the highest non-thermocycled K(IC). Chelon-Silver demonstrated the lowest mean K(IC) both before and after thermocycling. One-way analysis of variance demonstrated significant differences between conditions, and the Tukey test showed significant differences (P<.05) between materials for both conditions. Most specimens also showed significant hardness differences between conditions. Pearson's correlation coefficient indicated only a mild-to-moderate correlation between hardness and fracture toughness. Within the limitations of this study, the thermocycling process negatively affected the fracture toughness and hardness of the core buildup materials tested.

Effect of Gradual Heating and Fat/Oil Type on Fat Stability, Texture, Color, and Microstructure of Meat Batters.

PubMed

Barbut, S; Youssef, M K

2016-09-01

The effects of endpoint cooking temperature (40, 50, 60, 70, 80, and 90 °C) on emulsion stability, texture, color, and microstructure of meat batters prepared with different fats/oils were studied. Canola oil treatments showed the highest cooking loss whereas hydrogenated palm oil provided the most stable meat batters. Rendered beef fat was less stable than regular beef fat. Increasing endpoint cooking temperatures resulted in a progressive reduction of water holding capacity in all treatments. As temperature was raised, meat batters showed higher hardness and cohesiveness values, but no appreciable changes in cohesiveness above 60 °C. Canola and hydrogenated palm oil treatments showed the highest hardness and chewiness values. Lightness (L(*) ) values of all meat batters increased significantly with increasing temperature from 40 to 60 or 70 °C; no major changes observed above 70 °C. Light microscopy revealed no substantial changes in the microstructure of all the stable meat batters cooked to between 50 and 70 °C. Heating to 90 °C changed the microstructure in all meat batters except the hydrogenated palm oil treatments, which still showed nonround fat particles and a less aggregated protein matrix. © 2016 Institute of Food Technologists®

SA45. Amotivation in Schizophrenia, Bipolar Disorder, and Major Depressive Disorder: A Preliminary Comparison Study

PubMed Central

Zou, Ying-min; Ni, Ke; Wang, Yang-yu; Yu, En-qing; Lui, Simon S. Y.; Cheung, Eric F. C.; Chan, Raymond C. K.

2017-01-01

Abstract Background: Deficits in reward processing, such as approaching motivation, reward learning and effort-based decision-making, have been observed in patients with schizophrenia (SCZ), bipolar disorder (BD), and major depressive disorder (MDD). However, little is known about the nature of reward-processing deficits in these 3 diagnostic groups. The present study aimed to compare and contrast amotivation in these 3 diagnostic groups using an effort-based decision-making task. Methods: Sixty patients (19 SCZ patients, 18 BD patients and 23 MDD patients) and 27 healthy controls (HC) were recruited for the present study. The Effort Expenditure for Reward Task (EEfRT) was administered to evaluate their effort allocation pattern. This task required participants to choose easy or hard tasks in response to different levels of reward magnitude and reward probability. Results: Results showed that SCZ, BD, and MDD patients chose fewer hard tasks compared to HC. As reward magnitude increased, MDD patients made the least effort to gain reward compared to the other groups. When reward probability was intermediate, MDD patients chose fewer hard tasks than SCZ patients, whereas BD patients and HC chose more hard tasks than MDD and SCZ patients. When the reward probability was high, all 3 groups of patients tried fewer hard tasks than HC. Moreover, SCZ and MDD patients were less likely to choose hard tasks than BD patients and HC in the intermediate estimated value conditions. However, in the highest estimated value condition, there was no group difference in hard task choices between these 3 clinical groups, and they were all less motivated than HC. Conclusion: SCZ, BD, and MDD patients shared common deficits in gaining reward if the reward probability and estimated value were high. SCZ and MDD patients showed less motivation than BD patients in gaining reward when the reward probability and estimated value was intermediate.

Structure-mechanics property relationship of waste derived biochars.

PubMed

Das, Oisik; Sarmah, Ajit K; Bhattacharyya, Debes

2015-12-15

The widespread applications of biochar in agriculture and environmental remediation made the scientific community ignore its mechanical properties. Hence, to examine the scope of biochar's structural applications, its mechanical properties have been investigated in this paper through nanoindentation technique. Seven waste derived biochars, made under different pyrolysis conditions and from diverse feedstocks, were studied via nanoindentation, infrared spectroscopy, X-ray crystallography, thermogravimetry, and electron microscopy. Following this, an attempt was made to correlate the biochars' hardness/modulus with reaction conditions and their chemical properties. The pine wood biochar made at 900°C and 60min residence time was found to have the highest hardness and elastic modulus of 4.29 and 25.01GPa, respectively. It was shown that a combination of higher heat treatment (≥500°C) temperature and longer residence time (~60min) increases the values of hardness and modulus. It was further realized that pyrolysis temperature was a more dominant factor than residence time in determining the final mechanical properties of biochar particles. The degree of aromaticity and crystallinity of the biochar were also correlated with higher values of hardness and modulus. Copyright © 2015 Elsevier B.V. All rights reserved.

Tribological Testing, Analysis and Characterization of D.C. Magnetron Sputtered Ti-Nb-N Thin Film Coatings on Stainless Steel

NASA Astrophysics Data System (ADS)

Joshi, Prathmesh

To enhance the surface properties of stainless steel, the substrate was coated with a 1μm thick coating of Ti-Nb-N by reactive DC magnetron sputtering at different N2 flow rates, substrate biasing and Nb-Ti ratio. The characterization of the coated samples was performed by the following techniques: hardness by Knoop micro-hardness tester, phase analysis by X-ray Diffraction (XRD), compositional analysis by Energy Dispersive X-ray Spectroscopy (EDS) and adhesion by scratch test. The tribology testing was performed on linearly reciprocating ball-on-plate wear testing machine and wear depth and wear volume were evaluated by white light interferometer. The micro-hardness test yielded appreciable enhancement in the surface hardness with the highest value being 1450 HK. Presence of three prominent phases namely NbN, Nb2N3 and TiN resulted from the XRD analysis. EDS analysis revealed the presence of Ti, Nb and Nitrogen. Adhesion was evaluated on the basis of critical loads for cohesive (Lc1) and adhesive (Lc2) failures with values varying between 7-12 N and 16-25 N respectively, during scratch test for coatings on SS substrates.

Microstructures and mechanical properties of duplex low carbon steel

NASA Astrophysics Data System (ADS)

Alfirano; Eben, U. S.; Hidayat, M.

2018-04-01

The microstructures behavior of duplex cold-rolled low carbon steel for automotive applications has been investigated. Intercritical annealing treatment is commonly used to develop a duplex low carbon steel containing ferrite and martensite. To get a duplex phase ferrite and martensite, the specimens were heated at inter-critical annealing temperature of 775°C - 825°C, for heating time up to 20 minutes, followed by water-quenched. The hardness of specimens was studied. The optical microscopy was used to analyze the microstructures. The optimal annealing conditions (martensite volume fraction approaching 20%) at 775°C with a heating time of 10 minutes was achieved. The highest hardness value was obtained in cold-rolled specimens of 41% in size reduction for intercritical annealing temperature of 825°C. In this condition, the hardness value was 373 HVN. The correlation between intercritical annealing temperature and time can be expressed in the transformation kinetics as fγ/fe = 1-exp(-Ktn) wherein K and n are grain growth rate constant and Avrami’s exponent, respectively. From experiment, the value of K = 0.15 and n = 0.461. Using the relationship between temperatures and heating time, activation energy (Q) can be calculated that is 267 kJ/mol.

Evaluation of optical changes of three types of lenses: hard PMMA, hydrogel, and heparin surface modified hard lenses effected by silicone oil, used clinically as a substitute of the vitreous body.

PubMed

Prokopowicz, Magdalena; Czarnobaj, Katarzyna; Raczyńska, Krystyna; Łukasiak, Jerzy; Przyjazny, Andrzej

2002-01-01

The objective of these investigations was an in vitro evaluation whether silicone oil OXANE of viscosity 5700 cSt clinically used in eye surgery as a substitute of the vitreous body, being in contact with an artificial polymer lens used as an implant of human lens, causes the changes in its optical properties. The paper presents the results of spectral analysis of transmission of visible (VIS) radiation of three types of artificial lenses: hard PMMA, hydrogel, heparin surface modified (HSM) hard PMMA, and the same lenses damaged by YAG laser radiation with an energy increasing from 1.7 mJ to 3.7 mJ, exposed to clinically applied silicone oil. The studies were carried out, in two-week intervals, over a period of 20 weeks. Hard PMMA and HSM lenses were found not to have changed their optical properties after 20 weeks of exposure to silicone oil. The measured transmittance values were within the range of instrumental error (+/- 1%). Optical properties of hydrogel lenses exposed to silicone oils deteriorated with exposure and after 20-week exposure to silicone oil the average transmittance value decreased by about 18%, reaching its final value of 67.08 +/- 2.37% (RSD = 5.56%). A minimal decrease of the initial transmittance values was observed only for the lenses exposed to laser radiation of highest energy (3.7 mJ). After completed exposure to silicone oil, two kinds of lenses were found to have a slightly improved transmittance: hard PMMA lenses by about 4% and HSM lenses by about 2%. On the other hand, in case of hydrogel lenses the deterioration of optical properties to the extent comparable to that of hydrogel lenses not damaged by laser radiation was observed.

Soft- to network hard-material for constructing both ion- and electron-conductive hierarchical porous structure to significantly boost energy density of a supercapacitor.

PubMed

Yang, Pingping; Xie, Jiale; Guo, Chunxian; Li, Chang Ming

2017-01-01

Soft-material PEDOT is used to network hard Co 3 O 4 nanowires for constructing both ion- and electron-conductive hierarchical porous structure Co 3 O 4 /PEDOT to greatly boost the capacitor energy density than sum of that of plain Co 3 O 4 nanowires and PEDOT film. Specifically, the networked hierarchical porous structure of Co 3 O 4 /PEDOT is synthesized and tailored through hydrothermal method and post-electrochemical polymerization method for the PEDOT coating onto Co 3 O 4 nanowires. Typically, Co 3 O 4 /PEDOT supercapacitor gets a highest areal capacitance of 160mFcm -2 at a current density of 0.2mAcm -2 , which is about 2.2 times larger than the sum of that of plain Co 3 O 4 NWs (0.92mFcm -2 ) and PEDOT film (69.88mFcm -2 ). Besides, if only PEDOT as active mass is counted, Co 3 O 4 /PEDOT cell can achieve a highest capacitance of 567.21Fg -1 , this is the highest capacitance value obtained by PEDOT-based supercapacitors. Furthermore, this soft-hard network porous structure also achieves a high cycling stability of 93% capacitance retention after the 20,000th cycle. This work demonstrates a new approach to constructing both ion and electron conductive hierarchical porous structure to significantly boost energy density of a supercapacitor. Copyright © 2016 Elsevier Inc. All rights reserved.

Effect of five commercial mouth rinses on the microhardness of a nanofilled resin composite restorative material: An in vitro study

PubMed Central

Jyothi, KN; Crasta, Shanol; Venugopal, P

2012-01-01

Aim and Objectives: This in vitro study was designed to comparatively evaluate the effect of five commercial mouth rinses on the micro hardness of a nanofilled resin based restorative material. Materials and Methods: Fifty specimens of resin composite material (Filtek Z350XT, 3M ESPE, St.Paul, MN USA) were prepared and immersed in artificial saliva for 24 h. The base line micro hardness of specimens was recorded using Vicker's micro hardness tester (MMT – X7 Matsuzawa, Japan). The specimens were randomly distributed into five groups, each containing 10 specimens (n=10) as follows – Group I Listerine (alcohol based), Group II Periogard (alcohol based), Group III Colgate plax (alcohol based), Group IV C- prev (alcohol free), Group V Hiora(alcohol free). The specimens were immersed in 20 ml of mouth rinses and incubated for 24 h at 37°C. The post immersion micro hardness values of the specimens were recorded and the data was tabulated for statistical analysis. Kruskal–Wallis test was used for inter group comparison followed by pair wise comparison of groups using Mann–Whitney U test. The level of significance was set at P=0.05. Results: Significant reduction in the mean VHN (Vicker's micro hardness number) was observed in all the groups after exposure to the tested mouth rinses (P<0.01) and the reduction in mean VHN values were as follows: Group I 12.09, Group II 3.42, Group II 1.51, Group IV 1.03, Group V 0.57. Inter group comparison showed statistically significant reduction in micro hardness in Groups I and II compared to all other groups with P<0.001. There was no significant difference between Groups III, IV and V. Conclusion: All the mouth rinses showed a reduction in the microhardness of nanofilled resin composite material with listerine (Group I) containing maximum amount of alcohol, showing highest reduction in micro hardness value. PMID:22876004

Predicting obstructive coronary artery disease using carotid ultrasound parameters: a nomogram from a large real-world clinical data.

PubMed

Wu, Na; Chen, Xinghua; Li, Mingyang; Qu, Xiaolong; Li, Yueli; Xie, Weijia; Wu, Long; Xiang, Ying; Li, Yafei; Zhong, Li

2018-05-21

Carotid ultrasound is a non-invasive tool for risk assessment of coronary artery disease (CAD). There is no consensus on which carotid ultrasound parameter constitutes the best measurement of atherosclerosis. We investigated which model of carotid ultrasound parameters and clinical risk factors (CRF) have the highest predictive value for CAD. We enrolled 2431 consecutive patients who have suspected CAD and underwent coronary angiography and carotid ultrasound with measurements of carotid intima-media thickness (CIMT), total number of plaques and areas of different types of plaques classified by echogenicity. Total number of plaques demonstrated the highest incremental prediction ability to predict CAD over CRF (area under the curve [AUC] 0.752 vs 0.701, net reclassification index [NRI] = 0.514, P < 0.001), followed by area of maximum mixed and soft plaques. CIMT had no significant incremental value over CRF (AUC 0.704 vs 0.701, P = 0.241; NRI = 0.062, P = 0.168). The model comprising total number of plaques, areas of maximum soft, hard and mixed plaques plus CRF had the highest discriminatory (AUC = 0.757) and reclassification value (NRI = 0.567) for CAD. A nomogram based on this model was developed to predict CAD. For subjects at low and intermediate risk, the model comprising total number of plaques plus CRF was the best. Total number of plaques, area of maximum soft, hard and mixed plaques showed significantly incremental prediction ability over CRF. A nomogram based on these factors provided an intuitive and practical method in detecting CAD. This article is protected by copyright. All rights reserved. This article is protected by copyright. All rights reserved.

Structural analysis of bioceramic materials for denture application

NASA Astrophysics Data System (ADS)

Rauf, Nurlaela; Tahir, Dahlang; Arbiansyah, Muhammad

2016-03-01

Structural analysis has been performed on bioceramic materials for denture application by using X-ray diffraction (XRD), X-ray fluorescence (XRF), and Scanning Electron Microscopy (SEM). XRF is using for analysis chemical composition of raw materials. XRF shows the ratio 1 : 1 : 1 : 1 between feldspar, quartz, kaolin and eggshell, respectively, resulting composition CaO content of 56.78 %, which is similar with natural tooth. Sample preparation was carried out on temperature of 800 °C, 900 °C and 1000 °C. X-ray diffraction result showed that the structure is crystalline with trigonal crystal system for SiO2 (a=b=4.9134 Å and c=5.4051 Å) and CaH2O2 (a=b=3.5925 Å and c=4.9082 Å). Based on the Scherrer's equation showed the crystallite size of the highest peak (SiO2) increase with increasing the temperature preparation. The highest hardness value (87 kg/mm2) and match with the standards of dentin hardness. The surface structure was observed by using SEM also discussed.

Ti-Si-C thin films produced by magnetron sputtering: correlation between physical properties, mechanical properties and tribological behavior.

PubMed

Cunha, L; Vaz, F; Moura, C; Munteanu, D; Ionescu, C; Rivière, J P; Le Bourhis, E

2010-04-01

Ti-Si-C thin films were deposited onto silicon, stainless steel and high-speed steel substrates by magnetron sputtering, using different chamber configurations. The composition of the produced films was obtained by Electron Probe Micro-Analysis (EPMA) and the structure by X-ray diffraction (XRD). The hardness and residual stresses were obtained by depth-sensing indentation and substrate deflection measurements (using Stoney's equation), respectively. The tribological behavior of the produced films was studied by pin-on-disc. The increase of the concentration of non-metallic elements (carbon and silicon) caused significant changes in their properties. Structural analysis revealed the possibility of the coexistence of different phases in the prepared films, namely Ti metallic phase (alpha-Ti or beta-Ti) in the films with higher Ti content. The coatings with highest carbon contents, exhibited mainly a sub-stoichiometric fcc NaCI TiC-type structure. These structural changes were also confirmed by resistivity measurements, whose values ranged from 10(3) omega/sq for low non-metal concentration, up to 10(6) omega/sq for the highest metalloid concentration. A strong increase of hardness and residual stresses was observed with the increase of the non-metal concentration in the films. The hardness (H) values ranged between 11 and 27 GPa, with a clear dependence on both crystalline structure and composition features. Following the mechanical behavior, the tribological results showed similar trends, with both friction coefficients and wear revealing also a straight correlation with the composition and crystalline structure of the coatings.

Early hardness of self-adhesive resin cements cured under indirect resin composite restorations.

PubMed

Giráldez, Isabel; Ceballos, Laura; Garrido, Miguel A; Rodríguez, Jesús

2011-04-01

To determine the influence of curing mode on the surface hardness of seven resin cements used to lute indirect composite restorations. Seven commercial dual-curing resin cements were tested: two were total-etch (RelyX ARC [3M ESPE, St. Paul, MN, USA] and Variolink II [Ivoclar Vivadent, Schaan, Liechtenstein]); one was self-etch (Multilink Automix [Ivoclar Vivadent]), and four were self-adhesive (RelyX Unicem [3M ESPE], Maxcem Elite [Kerr Corp., Orange, CA, USA], SmartCem2 [Dentsply, Detrey, GmbH, Konstanz, Germany], and G-Cem [GC CORPORATION, Itabashi-Ku, Tokyo, Japan]). Three specimens (0.5 × 6.5mm) of each material were prepared for each of three experimental groups: Group 1 (cements allowed to self cure); Group 2 (cements light-cured for 40 seconds); and Group 3 (cements light-cured for 80 seconds). All specimens were cured through a 4-mm-thick composite cylinder (Filtek Z250-A3). Surface microhardness numbers were determined at 20 min after preparation. Results were analyzed by two-way analysis of variance and Student-Newman-Keuls tests (p<0.05). Superficial hardness was significantly influenced by the resin cement tested (p<0.0001), the curing mode (p<0.0001), and their interaction (p<0.0001). RelyX ARC exhibited the highest mean microhardness values regardless of the curing mode. Light-curing significantly increased the microhardness of all resin cements studied, and these values increased even further with a doubling of irradiation time. Self-adhesive cements exhibited different behavior according to the curing mode. RelyX Unicem was highly sensitive to light irradiation, showing the lowest mean values in the self-curing mode. After light irradiation for 40 or 80 seconds, Maxcem Elite exhibited the lowest mean hardness values of all the resin cements tested. The microhardness of resin cements is highly dependent on the brand. Dual-curing resin cements should always be light irradiated for longer periods than that recommended by manufacturers. Dual-curing resin cements should always be light-cured for longer irradiation times, as light irradiation for 80 seconds yields the highest microhardness values in comparison with self-curing or light irradiation for 40 seconds. However, some self-adhesive resin cements exhibit low microhardness values when used to cement 4-mm-thick indirect composite restorations regardless of the curing mode applied. © 2011, COPYRIGHT THE AUTHORS. JOURNAL COMPILATION © 2011, WILEY PERIODICALS, INC.

The Effects of Potato Puree and Bread Crumbs on Some Quality Characteristics of Low Fat Meatballs

PubMed Central

Ergezer, Haluk; Akcan, Tolga; Serdaroğlu, Meltem

2014-01-01

The purpose of this study was to determine the effects of using different amounts of potato puree (PP) (10 or 20%) and 10% bread crumbs (BC) as an extender and also control samples (C) with no added extender on chemical composition, energy values, cooking analyses, colour measurements, water holding capacity (WHC), penetration values, thiobarbituric acid value (TBA) and sensory analyses of meatballs. Meatball samples were cooked in a pre-heated 180℃ electric oven. Uncooked meatballs formulated with 20% PP had the highest moisture content. No significant differences were recorded for protein contents of uncooked samples. The highest cooking yield was found in samples extended with 10% BC. Increasing PP from 10% to 20% increased cooking yield of meatballs. 20% PP increased moisture and fat retention values and water holding capacity of meatballs. Meatballs with 10% BC had the lowest (the hardness in the texture) and meatballs with the 20% PP had the highest (the softness in the texture) penetration values. Formulating meatballs at a level of 20% resulted lower L* values. TBA values of control samples were higher than in PP added samples at the end of the storage period. Flavour scores for meatballs formulated with PP were higher than control and meatballs formulated with BC. Meatballs formulated with 10% PP had similar overall acceptability with meatballs added with 10% BC. PMID:26761488

The Effects of Potato Puree and Bread Crumbs on Some Quality Characteristics of Low Fat Meatballs.

PubMed

Ergezer, Haluk; Akcan, Tolga; Serdaroğlu, Meltem

2014-01-01

The purpose of this study was to determine the effects of using different amounts of potato puree (PP) (10 or 20%) and 10% bread crumbs (BC) as an extender and also control samples (C) with no added extender on chemical composition, energy values, cooking analyses, colour measurements, water holding capacity (WHC), penetration values, thiobarbituric acid value (TBA) and sensory analyses of meatballs. Meatball samples were cooked in a pre-heated 180℃ electric oven. Uncooked meatballs formulated with 20% PP had the highest moisture content. No significant differences were recorded for protein contents of uncooked samples. The highest cooking yield was found in samples extended with 10% BC. Increasing PP from 10% to 20% increased cooking yield of meatballs. 20% PP increased moisture and fat retention values and water holding capacity of meatballs. Meatballs with 10% BC had the lowest (the hardness in the texture) and meatballs with the 20% PP had the highest (the softness in the texture) penetration values. Formulating meatballs at a level of 20% resulted lower L* values. TBA values of control samples were higher than in PP added samples at the end of the storage period. Flavour scores for meatballs formulated with PP were higher than control and meatballs formulated with BC. Meatballs formulated with 10% PP had similar overall acceptability with meatballs added with 10% BC.

Effect of different types of disinfection solution and aging on the hardness and colour stability of maxillofacial silicone elastomers.

PubMed

Cevik, Pinar; Yildirim-Bicer, Arzu Z

2017-11-09

Understanding the effect of aging and different disinfecting agents on the physical properties of pigmented maxillofacial silicones may help eliminate the current uncertainty as to the best follow-up suggestions for the patients treated with silicone prostheses. One hundred fifty specimens (14 × 2 mm) were evaluated for colour and 75 specimens (30 × 10 mm) for hardness (total, 225 specimens). Five specimens were used for hardness testing in each disinfecting solution while 10 silicone specimens were used for colour evaluation. The samples were separated into 5 groups and the initial hardness and colour evaluations were performed and placed in disinfectant solution (neutral soap, effervescent tablet, 0.2% chlorhexidine, 4% chlorhexidine, sodium hypochlorite). A second set of colour and hardness measurements was taken after 48 hours of disinfection and 1,008 hours of artificial aging in a QUV-accelerated weathering tester. Two-way and 1-way analysis of variance with Tukey tests and paired t-test were used for statistical analysis (α = 0.05). Before artificial aging, the hardness value of the red pigment group was found to be significantly lower than that of the brown pigment group. After aging, the lowest Shore A value was seen in the neutral soap group, while the highest was seen in the effervescent tablet. Based on the results of this study, chlorohexidine 0.2% was found to be most suitable agent for disinfection of the prostheses. Washing with neutral soap caused loss of pigment from the surface of the silicones. Sodium hypochlorite was found to have a colour-fading effect on silicone specimens.

Effect of the Duck Skin on Quality Characteristics of Duck Hams

PubMed Central

Kim, Dong-Hyun; Kim, Tae-Kyung; Kim, Young-Boong; Sung, Jung-Min; Jang, YoungJin; Shim, Jae-Yun; Han, Sung-Gu; Choi, Yun-Sang

2017-01-01

This study was conducted to investigate the effect of duck skin on cooking loss, emulsion stability, pH, color, protein solubility, texture profile analysis (TPA), apparent viscosity, and sensory characteristics of press type duck ham with different ratio of duck breast meat and duck skin. Five duck ham formulations were produced with the following compositions: T1 (duck breast 70% + duck skin 30%), T2 (duck breast 60% + duck skin 40%), T3 (duck breast 50% + duck skin 50%), T4 (duck breast 40% + duck skin 60%), and T5 (duck breast 30% + duck skin 70%). The cooking loss and fat separation were lower in T1, and the total expressible fluid separations were lower in T1 and T2 than others. The pH ranged from 6.48 to 6.59, with the highest values in T4 and T5. T5 had the highest CIE L*-value, and T1 and T2 had the highest CIE a*-values; however, CIE b*-values did not differ significantly between the duck ham samples. The protein solubility and TPA (hardness, springiness, cohesiveness, gumminess, and chewiness) were the highest in T1. T1 and T2 had higher scores for color, tenderness, and overall acceptability. T1, T2, and T3 showed significantly higher values, but there were no significant differences for flavor and juiciness. Regarding apparent viscosity properties, T1 and T2 had higher viscosity values than the other formulations. In conclusion, the T1 (duck breast 70% + duck skin 30%) and T2 (duck breast 60% + duck skin 40%) duck hams show the highest quality characteristics. PMID:28747821

Position Estimation Using Image Derivative

NASA Technical Reports Server (NTRS)

Mortari, Daniele; deDilectis, Francesco; Zanetti, Renato

2015-01-01

This paper describes an image processing algorithm to process Moon and/or Earth images. The theory presented is based on the fact that Moon hard edge points are characterized by the highest values of the image derivative. Outliers are eliminated by two sequential filters. Moon center and radius are then estimated by nonlinear least-squares using circular sigmoid functions. The proposed image processing has been applied and validated using real and synthetic Moon images.

The effect of different rutile electrodes on mechanical properties of underwater wet welded AH-36 steel plates

NASA Astrophysics Data System (ADS)

Winarto, Winarto; Purnama, Dewin; Churniawan, Iwan

2018-04-01

Underwater welding is an important role in the rescue of ships and underwater structures, in case of emergency. In this study, the marine steel plates used are AH-36 steel as parent material. This type of steel is included in the High Strength Low Alloy (HSLA). Electrodes used for welding AH-36 steel plates are commonly the E6013 and E 7024 which are the type of based rutile electrodes. Those electrodes are widely available on the market and they would be compared with the original electrode for underwater which is the type of E7014 with the trade name of Broco UW-CS-1. Welding method used is Shielding Metal Arc Welding (SMAW) with the variation of 5 m and 10 m underwater depth and also varied with the electric current of 120A, 140A and 250A. It was found that hardness value of increased in the area of weld metal and HAZ. HAZ also tends to have the highest hardness compared to both of weld metal and base metal. Non destructive test by radiographed test (RT) on welds showed that there are found welding defects in the form of incomplete penetration on all variations of welding parameters, but there is no porosity defect detected. The results of the hardness tests of underwater wet welded steel plates show that the hardness value of both rutile electrodes (E6013 and E 7024) is apparently similar hardness value compared with the existing commercial electrode (E7014 of Broco UW-CS- 1). The tensile test results of underwater wet welded steel plates show that the use of rutile electrode of E6013 gives a better tensile properties than other rutile electrodes.

Effectiveness of plant-derived proanthocyanidins on demineralization on enamel and dentin under artificial cariogenic challenge

PubMed Central

da SILVA, Ana Paula Pereira; GONÇALVES, Rafael Simões; BORGES, Ana Flávia Sanches; BEDRAN-RUSSO, Ana Karina; SHINOHARA, Mirela Sanae

2015-01-01

Dental caries is considered a disease of high prevalence and a constant problem in public health. Proanthocyanidins (PAs) are substances that have been the target of recent studies aiming to control or treat caries. Objective The aim of this in vitro study was to evaluate the efficacy of a treatment with grape seed extract, under cariogenic challenge, to minimize or even prevent the onset of caries in the enamel and dentin. Material and Methods Blocks of enamel and dentin (6.0x6.0 mm) were obtained from bovine central incisors, polished, and selected by analysis of surface microhardness (SH). The blocks were randomly divided into 3 groups (n=15), according to the following treatments: GC (control), GSE (grape seed extract), GF (fluoride – 1,000 ppm). The blocks were subjected to 6 daily pH cycles for 8 days. Within the daily cycling, the specimens were stored in buffered solution. The blocks were then analyzed for perpendicular and surface hardness and polarized light microscopy. Results The means were subjected to statistical analysis using the ANOVA and Fisher’s PLSD tests (p<0.05). For enamel SH, GF showed the highest hardness values. In the dentin, GF was also the one that showed higher hardness values, followed by GSE. Regarding the cross-sectional hardness values, all groups behaved similarly in both the enamel and dentin. The samples that were treated with GSE and fluoride (GF) showed statistically higher values than the control. Conclusion Based on the data obtained in this in vitro study, it is suggested that grape seed extract inhibits demineralization of artificial carious lesions in both the enamel and dentin, but in a different scale in each structure and in a smaller scale when compared to fluoride. PMID:26221925

The effect of aqueous media on the mechanical properties of fluorapatite-mullite glass-ceramics.

PubMed

Mollazadeh, S; Ajalli, Siamak; Kashi, Tahereh S Jafarzadeh; Yekta, Bijan Eftekhai; Javadpour, Jafar; Jafari, S; Youssefi, Abbas; Fazel, Akbar

2015-11-01

To verify the effects of alternating thermal changes in aqueous media and chemical composition on mechanical properties of apatite-mullite glass-ceramics and to investigate concentration of ions eluted from glass-ceramics in aqueous media. The glass compositions were from SiO2Al2O3P2O5CaOTiO2BaOZrO2CaF2 system. Glass-ceramics were prepared by heat-treating at 1100°C for 3h samples alternately immersed in water at 5 and 60°C. The 3-point bending strength (n=10) were determined using 3×4×25mm/bar and a universal testing machine, at a cross-head speed of 0.1mm/min. Vickers micro hardness were evaluated by applying a total of 15-20 indentations under a 100g load for 30s. Concentrations of ions eluted from glass-ceramics immersed in 60±5°C double distilled water were determined by ion chromatography. The toxicity of glass-ceramics was assessed by seeding the osteosarcoma cells (MG63) on powder for different days and their cell proliferation assessment was investigated by MTT assay. The data were analyzed using one way analysis of variance and the means were compared by Tukey's test (5% significance level). The highest flexural strength and hardness values after thermal changes belonged to TiO2 and ZrO2 containing glass-ceramics which contained lower amount of released ions. BaO containing glass-ceramic and sample with extra amount of silica showed the highest amount of reduction in their mechanical strength values. These additives enhanced the concentration of eluted ions in aqueous media. MTT results showed that glass-ceramics were almost equivalent concerning their in-vitro biological behavior. Thermal changes and chemical compositions had significant effects on flexural strength and Vickers micro-hardness values. Copyright © 2015 Academy of Dental Materials. Published by Elsevier Ltd. All rights reserved.

Mechanical properties and three-body wear of dental restoratives and their comparative flowable materials.

PubMed

Schultz, Sabine; Rosentritt, Martin; Behr, Michael; Handel, Gerhard

2010-01-01

To compare wear performance and resistance to crack propagation (K1C) of commercial restorative materials and their flowable variations. A potential correlation between three-body wear and fracture toughness, modulus of elasticity, fracture work, Vickers hardness, and filler content was investigated. Seven restoratives (five composites, one ormocer, and one compomer) and their corresponding flowable materials were used to determine and compare the three-body wear with a bolus of millet-seed shells and rice food (Willytec). The wear characteristics were measured by profilometry after 50,000, 100,000, 150,000, and 200,000 loading cycles. The fracture toughness value, K1C (MPam1/2), for each single-edged notched specimen was measured in a three-point bending test (universal testing machine 1446, Zwick). Fracture work and modulus of elasticity were calculated from the load curves. Vickers hardness was measured (HV hardness tester, Zwick) according to DIN 50133. The veneering composite Sinfony (3M ESPE) was used as a reference material. Heavily filled composites experienced less wear than their flowable variations. The nanofiller composites revealed better wear results than hybrid composites, compomers, and ormocers. After 200,000 load cycles, the lowest wear rates were detected for Grandio (14 microm; Voco), and the highest mean values were found for Dyract AP (104 microm; Dentsply DeTrey). The values for fracture toughness (K1C) ranged from 0.82 to 3.64 MPam1/2. Highest K1C data was exhibited by the nanocomposite Nanopaq (Schutz Dental). All tested restorative materials exhibited higher fracture toughness than their low-viscosity variations. The wear resistance of the newer generation composites with incorporated nanofiller or microfiller particles increased to a high extent. Flowables show less resistance against wear and crack propagation because of their lower filler content. The reduced mechanical properties limit their use as a restorative to small noncontact, low-stress clinical situations.

New nanostructured ceramics from baddeleyite with improved mechanical properties for biomedical applications

NASA Astrophysics Data System (ADS)

Tyurin, Alexander I.; Zhigachev, Andrey O.; Umrikhin, Alexey V.; Rodaev, Vyacheslav V.; Korenkov, Viktor V.; Pirozhkova, Tatyana S.

2017-12-01

A method for the preparation of novel nanostructured zirconia ceramics from natural zirconia mineral—baddeleyite—using CaO as the stabilizer is described in the present work. Optimal synthesis conditions, including calcia content, planetary mill treatment regime, sintering time and temperature, corresponding to the highest values of hardness H, Young modulus E, and fracture toughness KC are found. The values of the mechanical properties H = 10.8 GPa, E = 200 GPa, and KC = 13.3 MPa m1/2 are comparable with or exceed the corresponding properties of commercial yttria-stabilized ceramics prepared from chemically precipitated zirconia.

Modeling of the effect of freezer conditions on the hardness of ice cream using response surface methodology.

PubMed

Inoue, K; Ochi, H; Habara, K; Taketsuka, M; Saito, H; Ichihashi, N; Iwatsuki, K

2009-12-01

The effect of conventional continuous freezer parameters [mix flow (L/h), overrun (%), drawing temperature ( degrees C), cylinder pressure (kPa), and dasher speed (rpm)] on the hardness of ice cream under varying measured temperatures (-5, -10, and -15 degrees C) was investigated systematically using response surface methodology (central composite face-centered design), and the relationships were expressed as statistical models. The range (maximum and minimum values) of each freezer parameter was set according to the actual capability of the conventional freezer and applicability to the manufacturing process. Hardness was measured using a penetrometer. These models showed that overrun and drawing temperature had significant effects on hardness. The models can be used to optimize freezer conditions to make ice cream of the least possible hardness under the highest overrun (120%) and a drawing temperature of approximately -5.5 degrees C (slightly warmer than the lowest drawing temperature of -6.5 degrees C) within the range of this study. With reference to the structural elements of the ice cream, we suggest that the volume of overrun and ice crystal content, ice crystal size, and fat globule destabilization affect the hardness of ice cream. In addition, the combination of a simple instrumental parameter and response surface methodology allows us to show the relation between freezer conditions and one of the most important properties-hardness-visually and quantitatively on the practical level.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Rauf, Nurlaela, E-mail: n-rauf@fmipa.unhas.ac.id; Tahir, Dahlang; Arbiansyah, Muhammad

Structural analysis has been performed on bioceramic materials for denture application by using X-ray diffraction (XRD), X-ray fluorescence (XRF), and Scanning Electron Microscopy (SEM). XRF is using for analysis chemical composition of raw materials. XRF shows the ratio 1 : 1 : 1 : 1 between feldspar, quartz, kaolin and eggshell, respectively, resulting composition CaO content of 56.78 %, which is similar with natural tooth. Sample preparation was carried out on temperature of 800 °C, 900 °C and 1000 °C. X-ray diffraction result showed that the structure is crystalline with trigonal crystal system for SiO{sub 2} (a=b=4.9134 Å and c=5.4051more » Å) and CaH{sub 2}O{sub 2} (a=b=3.5925 Å and c=4.9082 Å). Based on the Scherrer’s equation showed the crystallite size of the highest peak (SiO{sub 2}) increase with increasing the temperature preparation. The highest hardness value (87 kg/mm{sup 2}) and match with the standards of dentin hardness. The surface structure was observed by using SEM also discussed.« less

Effect of etch-and-rinse and self-etching adhesive systems on hardness uniformity of resin cements after glass fiber post cementation

PubMed Central

Grande da Cruz, Fernanda Zander; Grande, Christiana Zander; Roderjan, Douglas Augusto; Galvão Arrais, César Augusto; Bührer Samra, Adriana Postiglione; Calixto, Abraham Lincoln

2012-01-01

Objective To evaluate the effects of etch-and-rinse and self-etching adhesive systems on Vickers hardness (VHN) uniformity of dual-cured resin cements after fiber post cementation. Methods: Fifty glass fiber posts were cemented into bovine roots using the following cementing systems: Prime&Bond 2.1 Dual Cure and Enforce with light-activation (PBDC-LCEN); Prime&Bond 2.1 and Enforce with light-activation (PB-CLEN); Prime&Bond 2.1 Dual Cure and Enforce without light exposure (PBDC-SCEN); ED Primer and Panavia 21 (ED-SCPN); and Clearfil SE Bond and Panavia 21 (CF-SCPN). The roots were stored in distilled water for 72 h and transversely sectioned into thirds (coronal, medium, and apical). The VHN values of the resin cement layers were measured close to the post and to the dentin wall on the transversely sectioned flat surfaces. The results were analyzed by three-way repeated measures analysis of variance (ANOVA) and Tukey’s post-hoc test (pre-set alpha of 5%). Results: Most resin cements presented higher VHN values near the post than near the dentin wall. The ED-SCPN group showed the highest VHN values regardless of the root third, while the self-cured group PBDC-SCEN exhibited the lowest values. The resin cements from the light-activated groups PBDC-LCEN and PB-LCEN showed lower VHN values at the apical third than at the coronal third. The VHN values were not influenced by the root third in self-cured groups PBDC-SCEN, ED-SCPN, and ED-SCPN. Conclusion: Depending on the product, bonding agents might promote changes in hardness uniformity of resin cements after post cementation. PMID:22904652

High Elastic Moduli of a 54Al2O3-46Ta2O5 Glass Fabricated via Containerless Processing

PubMed Central

Rosales-Sosa, Gustavo A.; Masuno, Atsunobu; Higo, Yuji; Inoue, Hiroyuki; Yanaba, Yutaka; Mizoguchi, Teruyasu; Umada, Takumi; Okamura, Kohei; Kato, Katsuyoshi; Watanabe, Yasuhiro

2015-01-01

Glasses with high elastic moduli have been in demand for many years because the thickness of such glasses can be reduced while maintaining its strength. Moreover, thinner and lighter glasses are desired for the fabrication of windows in buildings and cars, cover glasses for smart-phones and substrates in Thin-Film Transistor (TFT) displays. In this work, we report a 54Al2O3-46Ta2O5 glass fabricated by aerodynamic levitation which possesses one of the highest elastic moduli and hardness for oxide glasses also displaying excellent optical properties. The glass was colorless and transparent in the visible region, and its refractive index nd was as high as 1.94. The measured Young’s modulus and Vickers hardness were 158.3 GPa and 9.1 GPa, respectively, which are comparable to the previously reported highest values for oxide glasses. Analysis made using 27Al Magic Angle Spinning Nuclear Magnetic Resonance (MAS NMR) spectroscopy revealed the presence of a significantly large fraction of high-coordinated Al in addition to four-coordinated Al in the glass. The high elastic modulus and hardness are attributed to both the large cationic field strength of Ta5+ ions and the large dissociation energies per unit volume of Al2O3 and Ta2O5. PMID:26468639

Effect of polymorphisms at the ghrelin gene locus on carcass, microstructure and physicochemical properties of longissimus lumborum muscle of Polish Landrace pigs.

PubMed

Wojtysiak, Dorota; Kaczor, Urszula

2011-12-01

The influence of RFLP-BsrI polymorphisms at the ghrelin gene locus on carcass, meat quality parameters and muscle fiber characteristics of longissimus lumborum was studied in 168 barrows of the Polish Landrace breed. Analysis revealed a high frequency of the 1 allele (0.60) with the frequencies of the 11, 12 and 22 genotypes being 0.45, 0.30 and 0.25, respectively. The most favorable parameters of meat traits were characteristic of pigs with the 22 genotype, together with a higher carcass and loin weight and lower thermal loss compared to 12 heterozygotes. The highest fat content was found in pigs with the 11 genotype, which had the highest abdominal fat weight and mean backfat thickness. Meanwhile, the 12 heterozygotes were characterized by the largest loin eye areas, highest lightness (L*) and yellowness (b*) values, and lowest redness (a*) values, as well as the greatest hardness and chewiness and largest diameter of type IIB muscle fibers compared to the other genotypes. Copyright © 2011 Elsevier Ltd. All rights reserved.

Determination of sulfuric acid concentration for anti-cavitation characteristics of Al alloy by two step anodizing process to forming nano porous.

PubMed

Lee, Seung-Jun; Kim, Seong-Kweon; Jeong, Jae-Yong; Kim, Seong-Jong

2014-12-01

Al alloy is a highly active metal but forms a protective oxide film having high corrosion resistance in atmosphere environment. However, the oxide film is not suitable for practical use, since the thickness of the film is not uniform and it is severly altered with formation conditions. This study focused on developing an aluminum anodizing layer having hardness, corrosion resistance and abrasion resistance equivalent to a commercial grade protective layer. Aluminum anodizing layer was produced by two-step aluminum anodizing oxide (AAO) process with different sulfuric acid concentrations, and the cavitation characteristics of the anodized coating layer was investigated. In hardness measurement, the anodized coating layer produced with 15 vol.% of sulfuric acid condition had the highest value of hardness but exhibited poor cavitation resistance due to being more brittle than those with other conditions. The 10 vol.% of sulfuric acid condition was thus considered to be the optimum condition as it had the lowest weight loss and damage depth.

The influence of tempering process for DP lateritic steel in hardness and microstructure behavior

NASA Astrophysics Data System (ADS)

Hasbi, Muhammad Yunan; Saefudin, Romijarso, Toni Bambang

2018-05-01

In this study, the influence of tempering temperature on dual phase (DP) steel lateritic has been examined. Lateritic is chosen because of its excellence as austenite stabilizer in the formation of martensite and also increase the weldability due to nickel content. The hardness and microstructure behavior of steels were the main focus of this research. One of the goals was to obtain the combination of high strength and ductile materials for automotive application. The specimens used in this study were low carbon steel made by the hot-rolled process and followed by the initial heating process with various temperature (760 °C, 800 °C, 840 °C) continued with rapid cooling. The specimens also conducted by secondary heating with tempering process at 450 °C in an hour with very slow cooling. The experimental results showed that correlation between temperatures with hardness properties of materials. The hardness of the specimens increases as temperature increases. It was because austenite phase has a sufficient time and temperature to form, therefore the amount of transformed austenite becomes martensite was greater. The highest hardness reached by T = 840 °C was 46.98 HRC, it was about 153% from as cast (18.54 HRC). Decreasing in hardness value when the specimen was tempering at 450 °C indicated that martensite phase has been transformed into tempered martensite.

Quality assessment of pharmaceutical tablet samples using Fourier transform near infrared spectroscopy and multivariate analysis

NASA Astrophysics Data System (ADS)

Kandpal, Lalit Mohan; Tewari, Jagdish; Gopinathan, Nishanth; Stolee, Jessica; Strong, Rick; Boulas, Pierre; Cho, Byoung-Kwan

2017-09-01

Determination of the content uniformity, assessed by the amount of an active pharmaceutical ingredient (API), and hardness of pharmaceutical materials is important for achieving a high-quality formulation and to ensure the intended therapeutic effects of the end-product. In this work, Fourier transform near infrared (FT-NIR) spectroscopy was used to determine the content uniformity and hardness of a pharmaceutical mini-tablet and standard tablet samples. Tablet samples were scanned using an FT-NIR instrument and tablet spectra were collected at wavelengths of 1000-2500 nm. Furthermore, multivariate analysis was applied to extract the relationship between the FT-NIR spectra and the measured parameters. The results of FT-NIR spectroscopy for API and hardness prediction were as precise as the reference high-performance liquid chromatography and mechanical hardness tests. For the prediction of mini-tablet API content, the highest coefficient of determination for the prediction (R2p) was found to be 0.99 with a standard error of prediction (SEP) of 0.72 mg. Moreover, the standard tablet hardness measurement had a R2p value of 0.91 with an SEP of 0.25 kg. These results suggest that FT-NIR spectroscopy is an alternative and accurate nondestructive measurement tool for the detection of the chemical and physical properties of pharmaceutical samples.

Wear and microhardness of different resin composite materials.

PubMed

Say, Esra Can; Civelek, Arzu; Nobecourt, Alain; Ersoy, Mustafa; Guleryuz, Canan

2003-01-01

This study determined the three-body abrasive wear resistance of two packable composites (P-60; Solitaire 2), an ion-releasing composite (Ariston AT), a hybrid composite (Tetric Ceram) and an ormocer (Admira). The study also looked at the correlation between wear resistance and hardness of the composites. Three-body wear testing was performed using an ACTA wear machine with 15 N contact force using millet seed as the third body. Wear depth (microm) was measured by profilometry after 200,000 cycles. The hardness test was performed using a digital microhardness tester (load: 500 g; dwell time: 15 seconds). The data were analyzed by using Kruskal Wallis (p < 0.05). There were statistically significant differences among the three body abrasive wear of the composites. The ranking from least to most were as follows: Filtek P-60 < Solitaire 2 < Ariston AT < Tetric Ceram < Admira. Filtek P-60 showed the highest microhardness value. No other significant differences in hardness were observed among the different resin composites (P-60 > AristonAT = Tetric Ceram = Solitaire 2 = Admira). The results of this study indicate that there are significant differences in the wear resistance of the resin composites. The correlation between hardness and wear was significant with a correlation coefficient of r:-0.91. A significant negative correlation exists between hardness and three-body wear of resin composites.

The effect of long-term disinfection procedures on hardness property of resin denture teeth.

PubMed

Campanha, Nara Hellen; Pavarina, Ana Cláudia; Jorge, Janaina Habib; Vergani, Carlos Eduardo; Machado, Ana Lucia; Giampaolo, Eunice Teresinha

2012-06-01

The aim of the study was to evaluate the effect of long-term disinfection procedures on the Vickers hardness (VHN) of acrylic resin denture teeth. Five acrylic resin denture teeth (Vipi Dent Plus-V, Trilux-T, Biolux-B, Postaris-P and Artiplus-A) and one composite resin denture teeth (SR-Orthosit-O) were embedded in heat-polymerised acrylic resin within polyvinylchloride tubes. Specimens were stored in distilled water at 37°C for 48 h. Measurements of hardness were taken after the following disinfection procedures: immersion for 7 days in 4% chlorhexidine gluconate or in 1% sodium hypochlorite (CIm and HIm group, respectively) and seven daily cycles of microwave sterilisation at 650 W for 6 min (MwS group). In the WIm group, specimens were maintained in water during the time used to perform the disinfection procedures (7 days). Data were analysed with anova followed by the Bonferroni procedure (α = 0.01). Microwave disinfection decreased the hardness of all acrylic resin denture teeth (p < 0.001). Immersion for 7 days in 4% chlorhexidine gluconate or distilled water had significant effect on the hardness of the acrylic resin denture teeth A (p < 0.01), and 1% sodium hypochlorite on teeth T (p < 0.01). All disinfection procedures decrease the hardness of the composite resin denture teeth (p < 0.01). Teeth O exhibited the highest and teeth V the lowest hardness values in the control group (p < 0.01). Disinfection procedures changed the hardness of resin denture teeth. © 2011 The Gerodontology Society and John Wiley & Sons A/S.

Viscoelastic properties of tablets from Osborne fractions, pentosans, flour and bread evaluated by creep tests

NASA Astrophysics Data System (ADS)

Escalante-Aburto, Anayansi; de Dios Figueroa-Cárdenas, Juan; Véles-Medina, José Juan; Ponce-García, Néstor; Hernández-Estrada, Zorba Josué; Rayas-Duarte, Patricia; Simsek, Senay

2017-07-01

Little attention has been given to the influence of non-gluten components on the viscoelastic properties of wheat flour dough, bread making process and their products. The aim of this study was to evaluate by creep tests the viscoelastic properties of tablets manufactured from Osborne solubility fractions (globulins, gliadins, glutenins, albumins and residue), pentosans, flour and bread. Hard and soft wheat cultivars were used to prepare the reconstituted tablets. Sintered tablets (except flour and bread) showed similar values to those obtained from the sum of the regression coefficients of the fractions. Gliadins and albumins accounted for about 54% of the total elasticity. Gliadins contributed with almost half of the total viscosity (45.7%), and showed the highest value for the viscosity coefficient of the viscous element. When the effect of dilution was evaluated, the residue showed the highest instantaneous elastic modulus (788.2 MPa). Retardation times of the first element (λ1 3.5 s) were about 10 times lower than the second element (λ2 39.3 s). The analysis of compliance of data corrected by protein content in flour showed that the residue fraction presented the highest values. An important contribution of non-gluten components (starch, albumins and globulins) on the viscoelastic performance of sintered tablets from Osborne fractions, flour and bread was found.

Melting of SiC powders preplaced duplex stainless steel using TIG welding

NASA Astrophysics Data System (ADS)

Maleque, M. A.; Afiq, M.

2018-01-01

TIG torch welding technique is a conventional melting technique for the cladding of metallic materials. Duplex stainless steels (DSS) show decrease in performance under aggressive environment which may lead to unanticipated failure due to poor surface properties. In this research, surface modification is done by using TIG torch method where silicon carbide (SiC) particles are fused into DSS substrate in order to form a new intermetallic compound at the surface. The effect of particle size, feed rate of SiC preplacement, energy input and shielding gas flow rate on surface topography, microstructure, microstructure and hardness are investigated. Deepest melt pool (1.237 mm) is produced via TIG torch with highest energy input of 1080 J/mm. Observations of surface topography shows rippling marks which confirms that re-solidification process has taken place. Melt microstructure consist of dendritic and globular carbides precipitate as well as partially melted silicon carbides (SiC) particles. Micro hardness recorded at value ranging from 316 HV0.5 to 1277 HV0.5 which shows increment from base hardness of 260 HV0.5kgf. The analyzed result showed that incorporation of silicon carbide particles via TIG Torch method increase the hardness of DSS.

Effects of delayed finishing/polishing on surface roughness, hardness and gloss of tooth-coloured restorative materials.

PubMed

Yazici, A Ruya; Tuncer, Duygu; Antonson, Sibel; Onen, Alev; Kilinc, Evren

2010-01-01

The aim of this study was to investigate the effect of delayed finishing/polishing on the surface roughness, hardness and gloss of tooth-coloured restorative materials. Four different tooth-coloured restoratives: a flowable resin composite- Tetric Flow, a hybrid resin composite- Venus, a nanohybrid resin composite- Grandio, and a polyacid modified resin composite- Dyract Extra were used. 30 specimens were made for each material and randomly assigned into three groups. The first group was finished/polished immediately and the second group was finished/polished after 24 hours. The remaining 10 specimens served as control. The surface roughness of each sample was recorded using a laser profilometer. Gloss measurements were performed using a small-area glossmeter. Vickers microhardness measurements were performed from three locations on each specimen surface under 100g load and 10s dwell time. Data for surface roughness and hardness were analyzed by Kruskal Wallis test and data for gloss were subjected to one-way ANOVA and Tukey test (P <.05). The smoothest surfaces were obtained under Mylar strip for all materials. While there were no significant differences in surface roughness of immediate and delayed finished/polished Dyract Extra samples, immediately finished/polished Venus and Grandio samples showed significantly higher roughness than the delayed polished samples (P <.05). In Tetric Flow samples, immediately finishing/polishing provided smoother surface than delayed finishing/polishing (P <.05). The highest gloss values were recorded under Mylar strip for all materials. While delayed finishing/polishing resulted in a significantly higher gloss compared to immediate finishing/polishing in Venus samples (P <.05), no differences were observed between delayed or immediate finishing/polishing for the other materials (P>.05). The lowest hardness values were found under Mylar strip. Delayed finishing/polishing significantly increased the hardness of all materials. The effect of delayed finishing/polishing on surface roughness, gloss and hardness appears to be material dependent.

Thermomechanical Properties of Sb2O3-TeO2-V2O5 Glassy Systems: Thermal Stability, Glass Forming Tendency and Vickers Hardness

NASA Astrophysics Data System (ADS)

Souri, Dariush; Torkashvand, Ziba

2017-04-01

Three-component 40TeO2-(60- x)V2O5- xSb2O3 glasses with 0 ≤ x ≤ 10 (in mol.%) were obtained by the rapid melt-quenching method. These glasses were studied with respect to some mechanical properties with the goal of obtaining information about their structure. The Vickers hardness test was employed to obtain Vickers micro-hardness ( H V) at two different loads, which was within the range of 13.187-17.557 GPa for a typical 0.1 HV (0.9807 N) load. In addition, theoretical micro-hardness ( H) was investigated and compared with experimental H V, showing the elevating trend with increase of Sb2O3 content, as for H V. Furthermore, differential scanning calorimetry (DSC) was employed within the range of 150-500°C at heating rates of φ = 3 K/min, 6 K/min, 9 K/min, 10 K/min, and 13 K/min. In this work, thermal stability ( T s = T cr - T x) and glass forming tendency ( K gl) were measured and reported for these glasses to determine the relationship between the chemical composition and the thermal stability, in order to interpret the structure of glass. Generally, from the ascertained outputs [analysis of mechanical data, titration study, the values of reduced fraction of vanadium ions ( C V) and oxygen molar volume ( V_{{O}}^{*} )], it was found that the micro-hardness had an increasing trend with increasing the Sb2O3 content. Among the studied glasses, the sample with x = 8 had a higher average micro-hardness value, the highest average thermal stability and glass forming tendency with respect to the other samples, which makes it a useful material (owning very good resistance against thermal attacks) for device manufacturing.

[Influence of long-term water storage on the physical and chemical properties of four different dental cements].

PubMed

Xu, Xiaodong; Meng, Xiangfeng

2014-11-01

To evaluate and compare the physical and chemical properties of four different dental cements under long-term water storage. A glass-ionomer cement (A:Fuji I), a resin reinforced glass-ionomer (B: Fuji Plus), a self-adhesive resin cement (C:G-Cem), and an etch & rinse resin cement (D: Duolink) were taken as samples. According to ISO 4049, water sorption and solubility of four resin cements under different storage times (1 week, 1, 3, 6 and 12 months) were calculated (n = 5), meanwhile their surface Knoop micro hardness values were measured. Surface cracks were detected on sample B and C after 12 months. Sample A was fragmentized after 6 months. Sample B showed significantly lower surface hardness after 12 months than it did after the first 24 hours of water storage (P < 0.05). Sample D showed significantly lower water sorption than other cements did at all exam time point. The highest water sorption values were observed in Sample D after 1 month [(40.8±2.5) µg/mm(3)], in Sample B after 3 months [(551.3±22.5) µg/mm(3)], in Sample C after 12 months [(147.5±8.3) µg/mm(3)]. The highest solubility values were detected in Sample B after 3 months [(105.3±10.5) µg/mm(3)], in Sample C after 12 months [(79.3 ± 6.2) µg/mm(3)], and in Sample D after 12 months [(23.9 ± 6.9) µg/mm(3)]. Among the four types of cements, the etch & rinse resin cement showed the best stability of physical and chemical properties under long-term water storage.

Shore hardness and tensile bond strength of long-term soft denture lining materials.

PubMed

Kim, Bong-Jun; Yang, Hong-So; Chun, Min-Geoung; Park, Yeong-Joon

2014-11-01

Reduced softness and separation from the denture base are the most significant problems of long-term soft lining materials. The purpose of this study was to evaluate the durometer Shore A hardness and tensile bond strength of long-term soft denture lining materials and to investigate the correlation between these 2 properties. A group of 7 soft lining materials, 6 silicone based (Dentusil, GC Reline Soft, GC Reline Ultrasoft, Mucopren Soft, Mucosoft, Sofreliner Tough) and 1 acrylic resin based (Durabase), were evaluated for durometer Shore A hardness and tensile bond strength to heat-polymerized denture base resin (Lucitone 199). A specially designed split mold and loading assembly with a swivel connector were used for the durometer Shore A hardness test and tensile bond strength test to improve accuracy and facilitate measurement. Three specimens of each product were stored in a 37°C water bath, and durometer Shore A hardness tests were carried out after 24 hours and 28 days. A tensile bond strength test was carried out for 10 specimens of each product, which were stored in a 37°C water bath for 24 hours before the test. Repeated-measures ANOVA, the Kruskal-Wallis and Duncan multiple range tests, and the Spearman correlation were used for statistical analyses. The repeated-measures ANOVA found significant durometer Shore A hardness differences for the materials (P<.001) and the interaction effect (aging×materials) (P<.001). GC Reline Ultrasoft showed the lowest mean durometer Shore A hardness (21.30 ±0.29 for 24 hours, 34.73 ±0.47 for 28 days), and GC Reline Soft showed the highest mean durometer Shore A hardness (50.13 ±0.48 for 24 hours, 57.20 ±0.28 for 28 days). The Kruskal-Wallis test found a significant difference in the mean tensile bond strength values (P<.001). GC Reline Ultrasoft (0.82 ±0.32 MPa) and Mucopren Soft (0.96 ±0.46 MPa) had a significantly lower mean tensile bond strength (P<.05). GC Reline Soft had the highest mean tensile bond strength (2.99 ±0.43 MPa) (P<.05), and acrylic resin-based Durabase showed a significantly different tensile bond strength (1.32 ±0.16 MPa), except for Mucopren Soft, among the materials (P<.05). The tensile bond strength and Shore A hardness showed a statistically insignificant moderate positive correlation (r=0.571, P=.180 for Shore A hardness 24 hours versus tensile bond strength; r=0.607, P=.148 for Shore A hardness 28 days versus tensile bond strength). Within the limitations of this study, significant differences were found in durometer Shore A hardness (with aging time) and tensile bond strength among the materials. Adhesive failure was moderately correlated with durometer Shore A hardness, especially after 28 days, but was not significant. Copyright © 2014 Editorial Council for the Journal of Prosthetic Dentistry. Published by Elsevier Inc. All rights reserved.

Effect of the addition of silanated silica on the mechanical properties of microwave heat-cured acrylic resin.

PubMed

da Silva, Lucas H; Feitosa, Sabrina A; Valera, Marcia C; de Araujo, Maria A M; Tango, Rubens N

2012-06-01

The purpose of this study was to evaluate the flexural strength and Vickers hardness of a microwave energy heat-cured acrylic resin by adding different concentrations of silane surface-treated nanoparticle silica. Acrylic resin specimens with dimensions of 65 × 10 × 2.5 mm were formed and divided into five experimental groups (n = 10) according to the silica concentration added to the acrylic resin mass (weight %) prior to polymerisation : G1, without silica; G2, 0.1% silica; G3, 0.5% silica; G4, 1.0% silica; and G5, 5.0% silica. The specimens were submitted to a three-point flexural strength test and to the Vickers hardness test (HVN). The data obtained were statistically analysed by anova and the Tukey test (α = 0.05). Regarding flexural strength, G5 differed from the other experimental groups (G1, G2, G3 and G4) presenting the lowest mean, while G4 presented a significantly higher mean, with the exception of group G3. Regarding Vickers hardness, a decrease in values was observed, in which G1 presented the highest hardness compared with the other experimental groups. Incorporating surface-treated silica resulted in direct benefits in the flexural strength of the acrylic resin activated by microwave energy; however, similar results were not achieved for hardness. © 2012 The Gerodontology Society and John Wiley & Sons A/S.

Effect of G-Coat Plus on the mechanical properties of glass-ionomer cements.

PubMed

Bagheri, R; Taha, N A; Azar, M R; Burrow, M F

2013-12-01

Although various mechanical properties of tooth-coloured materials have been described, little data have been published on the effect of ageing and G-Coat Plus on the hardness and strength of the glass-ionomer cements (GICs). Specimens were prepared from one polyacid-modified resin composite (PAMRC; Freedom, SDI), one resin-modified glass-ionomer cement; (RM-GIC; Fuji II LC, GC), and one conventional glass-ionomer cement; (GIC; Fuji IX, GC). GIC and RM-GIC were tested both with and without applying G-Coat Plus (GC). Specimens were conditioned in 37 °C distilled water for either 24 hours, four and eight weeks. Half the specimens were subjected to a shear punch test using a universal testing machine; the remaining half was subjected to Vickers Hardness test. Data analysis showed that the hardness and shear punch values were material dependent. The hardness and shear punch of the PAMRC was the highest and GIC the lowest. Applying the G-Coat Plus was associated with a significant decrease in the hardness of the materials but increase in the shear punch strength after four and eight weeks. The mechanical properties of the restorative materials were affected by applying G-Coat Plus and distilled water immersion over time. The PAMRC was significantly stronger and harder than the RM-GIC or GIC. © 2013 Australian Dental Association.

Mechanical properties and microstructures of glass-ionomer cements.

PubMed

Xie, D; Brantley, W A; Culbertson, B M; Wang, G

2000-03-01

The objective of this study was to determine the flexural strength (FS), compressive strength (CS), diametral tensile strength (DTS), Knoop hardness (KHN) and wear resistance of ten commercial glass-ionomer cements (GICs). The fracture surfaces of these cements were examined using scanning electron microscopic (SEM) techniques to ascertain relationships between the mechanical properties and microstructures of these cements. Specimens were fabricated according to the instructions from each manufacturer. The FS, CS, DTS, KHN and wear rate were measured after conditioning the specimens for 7 d in distilled water at 37 degrees C. One-way analysis of variance with the post hoc Tukey-Kramer multiple range test was used to determine which specimen groups were significantly different for each test. The fracture surface of one representative specimen of each GIC from the FS tests was examined using a scanning electron microscope. The resin-modified GICs (RM GICs) exhibited much higher FS and DTS, not generally higher CS, often lower Knoop hardness and generally lower wear resistance, compared to the conventional GICs (C GICs). Vitremer (3M) had the highest values of FS and DTS; Fuji II LC (GC International) and Ketac-Molar (ESPE) had the highest CS; Ketac-Fil (ESPE) had the highest KHN. Ketac-Bond (ESPE) had the lowest FS; alpha-Silver (DMG-Hamburg) had the lowest CS. Four GICs (alpha-Fil (DMG-Hamburg), alpha-Silver, Ketac-Bond and Fuji II) had the lowest values of DTS, which were not significantly different from each other; alpha-Silver and Ketac-Silver had the lowest values of KHN. The highest wear resistance was exhibited by alpha-Silver and Ketac-Fil; F2LC had the lowest wear resistance. The C GICs exhibited brittle behavior, whereas the RM GICs underwent substantial plastic deformation in compression. The more integrated the microstructure, the higher were the FS and DTS. Higher CS was correlated with smaller glass particles, and higher KHN was found where there was a combination of smaller glass particles and lower porosity. Larger glass particle sizes and a more integrated microstructure contributed to a higher wear resistance. The mechanical properties of GICs were closely related to their microstructures. Factors such as the integrity of the interface between the glass particles and the polymer matrix, the particle size, and the number and size of voids have important roles in determining the mechanical properties.

Effect of heat input on microstructure, wear and friction behavior of (wt.-%) 50FeCrC-20FeW-30FeB coating on AISI 1020 produced by using PTA welding.

PubMed

Özel, Cihan; Gürgenç, Turan

2018-01-01

In this study, AISI 1020 steel surface was coated in different heat inputs with (wt.-%) 50FeCrC-20FeW-30FeB powder mixture by using plasma transferred arc (PTA) welding method. The microstructure of the coated samples were investigated by using optical microscope (OM), scanning electron microscope (SEM), X-ray diffraction (XRD) and energy dispersive X-ray (EDS). The hardness was measured with micro hardness test device. The dry sliding wear and friction coefficient properties were determined using a block-on-disk type wear test device. Wear tests were performed at 19.62 N, 39.24 N, 58.86 N load and the sliding distance of 900 m. The results were shown that different microstructures formed due to the heat input change. The highest average micro hardness value was measured at 1217 HV on sample coated with low heat input. It was determined that the wear resistance decreased with increasing heat input.

Microstructural evolution with various Ti contents in Fe-based hardfacing alloys using a GTAW technique

NASA Astrophysics Data System (ADS)

Hsieh, Chih-Chun; Liu, Yi-Chia; Wang, Jia-Siang; Wu, Weite

2014-07-01

The aim of this study is to discuss the effect of microstructural development with different Ti contents in Fe-based hardfacing alloys. A series of Fe-Cr-C-Si-Mn-xTi alloy fillers was deposited on SS400 low carbon steel substrate using oscillating gas tungsten arc welding. The microstructure in the Fe-based hardfacing alloy without Ti content addition included: the primary γ, eutectic γ+(Fe,Cr)3C, eutectic γ+(Fe,Cr)2C and martensite. With increasing Ti contents, the microstructures showed the primary TiC carbide, γ phase and eutectic γ+(Fe,Cr,Ti)3C. The amount and size of TiC carbide in the hardfacing layers increased as the Ti content increased. However, the eutectic γ+(Fe,Cr,Ti)3C content decreased as the Ti content increased. According to the results of the hardness test, the lowest hardness value (HRC 54.93) was found with 0% wt% Ti and the highest hardness (HRC 60.29) was observed with 4.87 wt% Ti.

Effect of heat input on microstructure, wear and friction behavior of (wt.-%) 50FeCrC-20FeW-30FeB coating on AISI 1020 produced by using PTA welding

PubMed Central

Gürgenç, Turan

2018-01-01

In this study, AISI 1020 steel surface was coated in different heat inputs with (wt.-%) 50FeCrC-20FeW-30FeB powder mixture by using plasma transferred arc (PTA) welding method. The microstructure of the coated samples were investigated by using optical microscope (OM), scanning electron microscope (SEM), X-ray diffraction (XRD) and energy dispersive X-ray (EDS). The hardness was measured with micro hardness test device. The dry sliding wear and friction coefficient properties were determined using a block-on-disk type wear test device. Wear tests were performed at 19.62 N, 39.24 N, 58.86 N load and the sliding distance of 900 m. The results were shown that different microstructures formed due to the heat input change. The highest average micro hardness value was measured at 1217 HV on sample coated with low heat input. It was determined that the wear resistance decreased with increasing heat input. PMID:29324875

Mechanical properties of titanium-hydroxyapatite (Ti-HA) composite coating on stainless steel prepared by thermal spraying

NASA Astrophysics Data System (ADS)

Rosmamuhamadani, R.; Azhar, N. H.; Talari, M. K.; Yahaya, Sabrina M.; Sulaiman, S.; Ismail, M. I. S.

2017-09-01

Addition of hydroxyapatite (HA) can enhance the bioactivity of the common metallic implant due to its similarity with natural bones and teeth. In this investigation, high velocity oxy-fuel (HVOFT) technique was used to deposit titanium-hydroxyapatite (Ti-HA) composite on stainless steel substrate plate with different percentage of HA for biomedical applications. The aim of this research is to investigate the mechanical properties of Ti-HA coating such as hardness, adhesion strength and wear behaviour. The hardness and strength was determined by using SHIMADZU-microhardness Vickers tester and PosiTest AT portable adhesion tester respectively. The wear test was performed by using pin-on-disk equipment and field emission scanning electron microscope (FESEM) used to determine the extent of surface damage. From the results obtained, mechanical properties such as hardness and adhesion strength of titanium (Ti) coating decreased with the increased of HA contents. Meanwhile, the coefficient of friction of Ti-10% HA coating shows the highest value compare to others as three-body abrasion had occurred during the test.

The Effect of Water Hardness on Mortality of Zebrafish (Danio rerio) During Exposure to Oxytetracycline.

PubMed

Hundt, Matthias; Schreiber, Benjamin; Eckmann, Reiner; Lunestad, Bjørn Tore; Wünneman, Hannah; Schulz, Ralf

2016-02-01

Marking of fish otoliths with oxytetracycline and tetracycline is a widely used method to evaluate the effectiveness of stocking operations. Available protocols for the labeling of fish specify a number of factors influencing mark quality and potential risk for fish during marking. This study investigates the influence of water hardness on mortality of freshwater fish during marking with OTC. In order to pursue this question complexation of OTC with Mg(2+) and Ca(2+) cations was measured spectrophotometrically. Furthermore, zebrafish (Danio rerio) were immersed in OTC solutions (1200 mg/L; 48 h immersion) combined with varying levels of water hardness (5.5, 15.5, 25.5, 32.5°dH). The amount of OTC-Mg-Ca-complexes was positively correlated to water hardness. Moreover, it could be demonstrated that mortality of zebrafish during marking varied as a factor of water hardness. Highest mortalities occurred at the lowest (5.5°dH) and the highest (32.5°dH) tested levels during marking with OTC.

Evaluation of the Various Drying Methods on Surface Hardness of Type IV Dental Stone

PubMed Central

Sudhakar, A; Srivatsa, G; Shetty, Rohit; Rajeswari, C L; Manvi, Supriya

2015-01-01

Background: Studies regarding the effect of various methods to increase the surface hardness of Type IV dental stone are not conclusive. Therefore, this study was carried out to evaluate the effect of air drying, micro oven drying and die hardener on surface hardness of Type IV dental stone. Materials and Methods: A standard metal die was fabricated; polyvinyl siloxane impression material was used to make the molds of metal die. A total of 120 specimens were obtained from two different die stones and were grouped as Group A (kalrock) and Group B (pearl stone), and were subjected to air drying for 24 h, micro oven drying and application of die hardener. These models were then subjected to surface hardness testing using the knoop hardness instrument. The obtained data were subjected to statistical analysis. Results: The hardness of Group A specimens was 64 ± 0.54 Knoop hardness number (KHN) after application of die hardener, 60.47 ± 0.41 KHN after 24 h air drying, 58.2 ± 0.88 after microwave oven drying and 24.6 ± 0.4 after 1 h air drying. The hardness of Group B specimens was 45.59 ± 0.63 KHN after application of die hardener, 40.2 ± 0.63 KHN after 24 h air drying, 38.28 ± 0.55 KHN after microwave oven drying and 19.91 ± 0.64 KHN after 1 h air drying. Conclusion: Group A showed better results than Group B at all times. Application of the die hardener showed highest hardness values followed in the order by 24 h air drying, microwave oven drying and 1 h air drying in both groups. The study showed that air drying the dies for 24 h followed by application of a single layer of the die hardener produced the best surface hardness and is recommended to be followed in practice. PMID:26124610

Hardness of the subchondral bone of the patella in the normal state, in chondromalacia, and in osteoarthrosis.

PubMed

Björkström, S; Goldie, I F

1982-06-01

The hardness of bone is its property of withstanding the impact of a penetrating agent. It has been found that articular degenerative changes in, for example, the tibia (knee) are combined with a decrease in the hardness of the subchondral bone. In this investigation the hardness of subchondral bone in chondromalacia and osteoarthrosis of the patella has been analysed and compared with normal subchondral bone. Using an indentation method originally described by Brinell the hardness of the subchondral bone was evaluated in 7 normal patellae, in 20 with chondromalacia and in 33 with osteoarthrosis. A microscopic and microradiographic study of the subchondral bone was carried out simultaneously. Hardness was lowest in the normal material. The mean hardness value beneath the degenerated cartilage differed only slightly from that of the normal material, but the variation of values was increased. The hardness in bone in the chondromalacia area was lower than the hardness in bone covered by surrounding normal cartilage. The mean hardness value in bone beneath normal parts of cartilage in specimens with chondromalacia was higher than the mean hardness value of the normal material. In the microscopic and microradiographic examination it became evident that there was a relationship between trabecular structure and subchondral bone hardness; high values: coarse and solid structure; low values: slender and less regular structure.

Registration of 'Bolles' hard red spring wheat with high grain protein concentration and superior baking quality

USDA-ARS?s Scientific Manuscript database

The hard red spring wheat market class in the U.S. commands the highest prices on the worldwide wheat markets because of its high protein content, strong gluten, and good baking properties. ‘Bolles’ (PI 678430), a hard red spring wheat cultivar, was released by the University of Minnesota Agricultu...

Wear Enhancement of Wheel-Rail Interaction by Ultrasonic Nanocrystalline Surface Modification Technique.

PubMed

Chang, Seky; Pyun, Young-Sik; Amanov, Auezhan

2017-02-16

In this study, an ultrasonic nanocrystalline surface modification (UNSM) technique was applied to normal and heat-treated rails made of 60 kgK steel to enhance the wear resistance of the wheel-rail interaction. The hardness and compressive residual stress values of the untreated and UNSM-treated rails were measured by the Brinell hardness tester and X-ray diffraction technique, respectively. It was found, according to the measurement results, that the hardness was increased by about 20% and 8%, whereas the compressive residual stress was induced by about 52% and 62% for the UNSM-treated normal and heat-treated rails, respectively. The UNSM-treated normal rail showed a slightly higher hardness than the heat-treated rail. The wear resistance of rails with respect to rotating speed and rolling time was assessed using a rolling contact wear (RCW) tester under dry conditions. The RCW test results revealed that the wear of the UNSM-treated rails was enhanced in comparison with those of the untreated rails. Also, the wear amount of the rails was increased with increasing the rotation speed. The UNSM-treated normal rail exhibited the highest wear resistance with respect to the rotation speed. The wear mechanisms of the rails are also discussed based on microscopic images of the worn out surfaces.

Wear Enhancement of Wheel-Rail Interaction by Ultrasonic Nanocrystalline Surface Modification Technique

PubMed Central

Chang, Seky; Pyun, Young-Sik; Amanov, Auezhan

2017-01-01

In this study, an ultrasonic nanocrystalline surface modification (UNSM) technique was applied to normal and heat-treated rails made of 60 kgK steel to enhance the wear resistance of the wheel-rail interaction. The hardness and compressive residual stress values of the untreated and UNSM-treated rails were measured by the Brinell hardness tester and X-ray diffraction technique, respectively. It was found, according to the measurement results, that the hardness was increased by about 20% and 8%, whereas the compressive residual stress was induced by about 52% and 62% for the UNSM-treated normal and heat-treated rails, respectively. The UNSM-treated normal rail showed a slightly higher hardness than the heat-treated rail. The wear resistance of rails with respect to rotating speed and rolling time was assessed using a rolling contact wear (RCW) tester under dry conditions. The RCW test results revealed that the wear of the UNSM-treated rails was enhanced in comparison with those of the untreated rails. Also, the wear amount of the rails was increased with increasing the rotation speed. The UNSM-treated normal rail exhibited the highest wear resistance with respect to the rotation speed. The wear mechanisms of the rails are also discussed based on microscopic images of the worn out surfaces. PMID:28772549

A novel method to predict the highest hardness of plasma sprayed coating without micro-defects

NASA Astrophysics Data System (ADS)

Zhuo, Yukun; Ye, Fuxing; Wang, Feng

2018-04-01

The plasma sprayed coatings are stacked by splats, which are regarded generally as the elementary units of coating. Many researchers have focused on the morphology and formation mechanism of splat. However, a novel method to predict the highest hardness of plasma sprayed coating without micro-defects is proposed according to the nanohardness of splat in this paper. The effectiveness of this novel method was examined by experiments. Firstly, the microstructure of splats and coating, meanwhile the 3D topography of the splats were observed by SEM (SU1510) and video microscope (VHX-2000). Secondly, the nanohardness of splats was evaluated by nanoindentation (NHT) in order to be compared with microhardness of coating measured by microhardness tester (HV-1000A). The results show that the nanohardness of splats with diameter of 70 μm, 100 μm and 140 μm were in the scope of 11∼12 GPa while the microhardness of coating were in the range of 8∼9 GPa. Because the splats had not micro-defects such as pores and cracks in the nanohardness evaluated nano-zone, the nanohardness of the splats can be utilized to predict the highest hardness of coating without micro-defects. This method indicates the maximum of sprayed coating hardness and will reduce the test number to get high hardness coating for better wear resistance.

Cardiovascular diseases and hard drinking waters: implications from a systematic review with meta-analysis of case-control studies.

PubMed

Gianfredi, Vincenza; Bragazzi, Nicola Luigi; Nucci, Daniele; Villarini, Milena; Moretti, Massimo

2017-02-01

This systematic review with meta-analysis, performed according to the Preferred Reporting Items for Systematic Reviews and Meta-analysis (PRISMA) guidelines, aims at evaluating the potential correlation between magnesium and calcium concentration in drinking waters and the risk of cardiovascular diseases (CVD), which impose a considerable burden in high-income countries. Included studies were of the case-control studies type. From an initial list of 643 potentially eligible articles, seven studies were finally retained in the quantitative analysis. Since each one of them assessed different ion concentrations, subjects exposed to the highest concentration versus those exposed to the lowest concentration were compared. By including an overall figure of 44,000 subjects, the result suggests a protective effect of the ions on CVD prevention, with an effect-size (ES) of 0.82 (95% confidence interval CI = [0.70-0.95], p-value = 0.008) for calcium, and ES = 0.75 (95% CI = [0.66-0.86], p-value = 0.000) for magnesium. Hard water consumption seems to be protective against CVD. However, the high heterogeneity (I 2 = 75.24, p-value = 0.001 for calcium; I 2 = 72.96, p-value = 0.0024 for magnesium) and the existence of publication bias limits the robustness and generalizability of these findings. Further high-quality studies are needed to reproduce and confirm these results.

Structure-property studies of thermoplastic and thermosetting polyurethanes using palm and soya oils-based polyols.

PubMed

Mohammed, Issam Ahmed; Al-Mulla, Emad Abbas Jaffar; Kadar, Nurul Khizien Abdul; Ibrahim, Mazlan

2013-01-01

Palm and soya oils were converted to monoglycerides via transesterification of triglycerides with glycerol by one step process to produce renewable polyols. Thermoplastic polyurethanes (TPPUs) were prepared from the reaction of the monoglycerides which act as polyol with 4,4'-methylenediphenyldiisocyanate (MDI) whereas, thermosetting polyurethanes (TSPUs) were prepared from the reaction of glycerol, MDI and monoglycerides in one pot. Characterization of the polyurethanes was carried out by FT-IR, (1)H NMR, and iodine value and sol-gel fraction. The TSPUs showed good thermal properties compared to TPPUs as well as TSPUs exhibits good properties in pencil hardness and adhesion, however poorer in flexural and impact strength compared to TPPUs. The higher percentage of cross linked fraction, the higher degree of cross linking occurred, which is due to the higher number of double bond presents in the TSPUs. These were reflected in iodine value test as the highest iodine value of the soya-based thermosetting polyurethanes confirmed the highest degree of cross linking. Polyurethanes based on soya oil showed better properties compared to palm oil. This study is a breakthrough development of polyurethane resins using palm and soya oils as one of the raw materials.

The effect of turbidity levels and Moringa oleifera concentration on the effectiveness of coagulation in water treatment.

PubMed

Nkurunziza, T; Nduwayezu, J B; Banadda, E N; Nhapi, I

2009-01-01

Laboratory experiments were carried out to assess the water purification and antimicrobial properties of Moringa oleifera (MO). Hence different concentrations (25 to 300 mg/L) were prepared from a salt (1 M NaCl) extract of MO fine powder and applied to natural surface water whose turbidity levels ranged from 50 to 450 NTU. The parameters determined before and after coagulation were turbidity, pH, colour, hardness, iron, manganese and Escherichia coli. The experiments showed that turbidity removal is influenced by the initial turbidity since the lowest turbidity removal of 83.2% was observed at 50 NTU, whilst the highest of 99.8% was obtained at 450 NTU. Colour removal followed the same trend as the turbidity. The pH exhibited slight variations through the coagulation. The hardness removal was very low (0 to 15%). However, high removals were achieved for iron (90.4% to 100%) and manganese (93.1% to 100%). The highest E. coli removal achieved was 96.0%. Its removal was associated with the turbidity removal. The optimum MO dosages were 150 mg/L (50 NTU and 150 NTU) and 125 mg/L for the rest of the initial turbidity values. Furthermore all the parameters determined satisfied the WHO guidelines for drinking water except for E. coli.

Mechanical Properties of Calcium Fluoride-Based Composite Materials

PubMed Central

Kleczewska, Joanna; Pryliński, Mariusz; Podlewska, Magdalena; Sokołowski, Jerzy; Łapińska, Barbara

2016-01-01

Aim of the study was to evaluate mechanical properties of light-curing composite materials modified with the addition of calcium fluoride. The study used one experimental light-curing composite material (ECM) and one commercially available flowable light-curing composite material (FA) that were modified with 0.5–5.0 wt% anhydrous calcium fluoride. Morphology of the samples and uniformity of CaF2 distribution were analyzed using Scanning Electron Microscopy (SEM) and Energy Dispersive Spectroscopy (EDS). Mechanical properties were tested after 24-hour storage of specimens in dry or wet conditions. Stored dry ECM enriched with 0.5–1.0 wt% CaF2 showed higher tensile strength values, while water storage of all modified ECM specimens decreased their tensile strength. The highest Vickers hardness tested after dry storage was observed for 2.5 wt% CaF2 content in ECM. The addition of 2.0–5.0 wt% CaF2 to FA caused significant decrease in tensile strength after dry storage and overall tensile strength decrease of modified FA specimens after water storage. The content of 2.0 wt% CaF2 in FA resulted in the highest Vickers hardness tested after wet storage. Commercially available composite material (FA), unmodified with fluoride addition, demonstrated overall significantly higher mechanical properties. PMID:28004001

Evaluation of microhardness, surface roughness, and wear behavior of different types of resin composites polymerized with two different light sources.

PubMed

Topcu, Fulya Toksoy; Erdemir, Ugur; Sahinkesen, Gunes; Yildiz, Esra; Uslan, Ibrahim; Acikel, Cengizhan

2010-02-01

The microhardness, surface roughness and wear resistance of different types of resin composites, polymerized by a Quartz Tungsten Halogen (QTH) or Light Emitting Diode (LED) light curing units (LCU) were evaluated in this in vitro study. Cylindrical blocks were prepared from composites (8 mm in diameter, and 2 mm in thickness) and polymerized by a LED or a QTH LCU. Vickers hardness was measured on the top and bottom surfaces of the specimens. Surface roughness was measured with a surface profilometer on the top of the specimens. For the wear test, specimens were tested in a conventional pin-on-disc tribology machine under 15 N loads. The statistical analyses were performed by one-way analysis of variance (ANOVA) and t-tests, including the Bonferroni correction. Nanocomposite material Clearfil Majesty Posterior showed the highest hardness values in all polymerization types at the top and bottom surfaces (p < 0.05). Microhybrid Clearfil APX and hybrid Quixfil composites demonstrated the greatest surface roughness. Wear resistance of Clearfil Majesty Posterior was found to be the highest among the other tested resin composites. The results indicated that Clearfil Majesty Posterior demonstrated higher microhardness, less surface roughness, and higher wear resistance when compared with the other tested materials for both polymerization types.

Environmental change pattern in central Japan as revealed by LANDSAT data

NASA Technical Reports Server (NTRS)

Maruyasu, T. (Principal Investigator); Tsuchiya, K.; Ochiai, H.

1977-01-01

The author has identified the following significant results. A patched cirrus reported by weather stations was hardly recognizable by the eye in LANDSAT MSS data of a three year time lapse. The cloud cover affected radiance values significantly in band 4, while its effect was minimal in bands 6 and 7 (near infrared spectra). The cross correlation coefficient analysis between the two images indicated that the highest value obtained in central Japan was 0.963 for the area where little change occurred in land use over the three period. An analysis of land use in Nagoya showed little change in the metropolitan area while a fairly large change occurred in the northern periphery of the city where large scale housing projects are located.

Effect of Dietary Fiber Enrichment and Different Cooking Methods on Quality of Chicken Nuggets.

PubMed

Pathera, Ashok K; Riar, C S; Yadav, Sanjay; Sharma, D P

2017-01-01

The effect of dietary fiber enrichment (wheat bran) and cooking methods (oven, steam and microwave) on functional and physico-chemical properties of raw nuggets formulation as well as nutritional, color and textural properties of chicken nuggets were analyzed in this study. Among different cooking methods used for nuggets preparation, steam cooked nuggets had significantly ( p <0.05) higher water holding capacity (56.65%), cooking yield (97.16%) and total dietary fiber content (4.32%) in comparison to oven and microwave cooked nuggets. The effect of cooking methods and wheat bran incorporation was also noticed on textural properties of the nuggets. Hardness, firmness and toughness values of oven and steam cooked nuggets were significantly ( p <0.05) higher than microwave cooked nuggets. Among nuggets prepared by different cooking methods, cohesiveness of microwave cooked nuggets was found to be significantly ( p <0.05) highest, whereas, oven cooked nuggets had significantly ( p <0.05) highest gumminess and chewiness values. Steam cooked nuggets were found to be better among all nuggets due to their higher cooking yield and dietary fiber content.

Effect of Dietary Fiber Enrichment and Different Cooking Methods on Quality of Chicken Nuggets

PubMed Central

Yadav, Sanjay; Sharma, D. P.

2017-01-01

The effect of dietary fiber enrichment (wheat bran) and cooking methods (oven, steam and microwave) on functional and physico-chemical properties of raw nuggets formulation as well as nutritional, color and textural properties of chicken nuggets were analyzed in this study. Among different cooking methods used for nuggets preparation, steam cooked nuggets had significantly (p<0.05) higher water holding capacity (56.65%), cooking yield (97.16%) and total dietary fiber content (4.32%) in comparison to oven and microwave cooked nuggets. The effect of cooking methods and wheat bran incorporation was also noticed on textural properties of the nuggets. Hardness, firmness and toughness values of oven and steam cooked nuggets were significantly (p<0.05) higher than microwave cooked nuggets. Among nuggets prepared by different cooking methods, cohesiveness of microwave cooked nuggets was found to be significantly (p<0.05) highest, whereas, oven cooked nuggets had significantly (p<0.05) highest gumminess and chewiness values. Steam cooked nuggets were found to be better among all nuggets due to their higher cooking yield and dietary fiber content. PMID:28747827

The effect of silver (Ag) addition to mechanical and electrical properties of copper alloy (Cu) casting product

NASA Astrophysics Data System (ADS)

Felicia, Dian M.; Rochiem, R.; Laia, Standley M.

2018-04-01

Copper have good mechanical properties and good electrical conductivities. Therefore, copper usually used as electrical components. Silver have better electrical conductivities than copper. Female contact resistor is one of the electrical component used in circuit breaker. This study aims to analyze the effect of silver addition to hardness, strength, and electric conductivity properties of copper alloy. This study uses variation of 0; 0.035; 0.07; 0.1 wt. % Ag (silver) addition to determine the effect on mechanical properties and electrical properties of copper alloy through sand casting process. Modelling of thermal analysis and structural analysis was calculated to find the best design for the sand casting experiments. The result of Cu-Ag alloy as cast will be characterized by OES test, metallography test, Brinell hardness test, tensile test, and LCR meter test. The result of this study showed that the addition of silver increase mechanical properties of Cu-Ag. The maximum hardness value of this alloy is 83.1 HRB which is Cu-0.01 Ag and the lowest is 52.26 HRB which is pure Cu. The maximum strength value is 153.2 MPa which is Cu-0.07 Ag and the lowest is 94.6 MPa which is pure Cu. Silver addition decrease electrical properties of this alloy. The highest electric conductivity is 438.98 S/m which is pure Cu and the lowest is 52.61 S.m which is Cu-0.1 Ag.

Effect of hardness on acute toxicity of metal mixtures using Daphnia magna: prediction of acid mine drainage toxicity.

PubMed

Yim, Jin Hee; Kim, Kyoung W; Kim, Sang D

2006-11-02

In this study, the effect of hardness on the combined outcome of metal mixtures was investigated using Daphnia magna. The toxic unit (TU) was calculated using modified LC(50) values based on the hardness (i.e., LC(50-soft) and LC(50-hard)). From a bioassay test, the degree of sensitivity to hardness on the toxicity changes was in the order: Cd

The characterization of ceramic alumina prepared by using additive glass beads

NASA Astrophysics Data System (ADS)

Suprapedi; Muljadi; Sardjono, Priyo

2018-01-01

The ceramic alumina has been made by using additive glass bead (5 and 10 % wt.). There are two kinds of materials, such as : gamma Alumina and glass bead. Synthesis of alumina was done by ball milling for 24 hours, then the mixed powder was dried in drying oven at 100 °C for 6 hours. Furthermore, the dried powder was mixed by using 2 % of PVA and continued with compacted to form a pellet with pressure of 50 MPA. The next step is sintering process with variation temperature of 1150, 1200, 1250, 1300 and 1400 °C and holding time for 2 hours. The characterization conducted are consist of test density, hardness, shrinkage, and microstructure. The results show that ceramic alumina with addition of 10 % wt. glass bead has the higher value of density, hardness and shrinkage than addition of 5% wt. glass bead. The highest characterization of ceramic alumina with addition 10 % glass bead was achieved at sintering temperature of 1400 °C with density 3.68 g/cm3, hardness vickers 780.40 Hv and shrinkage 15.23 %. The XRD results show that it was founds a corrundum (alpha Alumina) as dominant phase and mullite as minor phase.

The influence of flame hardening process to aluminum 7075 series on the mechanical strength and micro structure

NASA Astrophysics Data System (ADS)

Koin, Sudibtia Titio; Triyono, Teguh; Surojo, Eko

2018-02-01

The 7075 series alloys are heat treatable wrought aluminum alloys based on the Al-Zn-Mg(-Cu) system. They are widely used in high-performance structural aerospace and transportation applications. Apart from compositional, casting and thermo-mechanical processing effects, the balance of properties is also significantly influenced by the way in which the materials are heat-treated. This paper describes the effect of flame hardening process to aluminum 7075 series on the increasing hardness, tensile strength, and evolution of microstructure. A test specimen had made by machining process and flame heating. Temperature of solution heat treatment is varied on 350 °C, 400 °C, 450 °C and 500 °C. After that process a test specimen would be quenched at nitrate-nitrite liquid during 45 minutes and artificial aging at 120°C until two days. The testing specimen consist of hardness and tensile strength according to ASTM. The result showed that specimen had precipitation on microstructure lead to an increase in aluminum properties. On the temperature 450°C solution heat treatment, the aluminum properties reached the highest value, namely, hardness of 129 HVN and tensile strength 570 MPa.

Measurement of the dependence of transverse energy production at large pseudorapidity on the hard-scattering kinematics of proton–proton collisions at √s = 2.76 TeV with ATLAS

DOE Office of Scientific and Technical Information (OSTI.GOV)

Aad, G.

2016-03-02

The relationship between jet production in the central region and the underlying-event activity in a pseudorapidity-separated region is studied in 4.0 pb -1 of √s = 2.76 TeV pp collision data recorded with the ATLAS detector at the LHC. The underlying event is characterised through measurements of the average value of the sum of the transverse energy at large pseudorapidity downstream of one of the protons, which are reported here as a function of hard-scattering kinematic variables. The hard scattering is characterised by the average transverse momentum and pseudorapidity of the two highest transverse momentum jets in the event. Themore » dijet kinematics are used to estimate, on an event-by-event basis, the scaled longitudinal momenta of the hard-scattered partons in the target and projectile beam-protons moving toward and away from the region measuring transverse energy, respectively. Transverse energy production at large pseudorapidity is observed to decrease with a linear dependence on the longitudinal momentum fraction in the target proton and to depend only weakly on that in the projectile proton. Lastly, the results are compared to the predictions of various Monte Carlo event generators, which qualitatively reproduce the trends observed in data but generally underpredict the overall level of transverse energy at forward pseudorapidity.« less

The effect of different composition of ternary mixtures of emulsifying salts on the consistency of processed cheese spreads manufactured from Swiss-type cheese with different degrees of maturity.

PubMed

Salek, R N; Černíková, M; Maděrová, S; Lapčík, L; Buňka, F

2016-05-01

The scope of this work was to investigate the dependence of selected textural (texture profile analysis, TPA) and viscoelastic properties of processed cheese on the composition of ternary mixtures of emulsifying salts [disodium hydrogenphosphate, DSP; tetrasodium diphosphate, TSPP; sodium salt of polyphosphate (with mean length n ≈ 20), P20; and trisodium citrate, TSC] during a 60-d storage period (6±2°C). The processed cheese samples [40% wt/wt dry matter (DM) content, 50% wt/wt fat in DM content] were manufactured using Swiss-type cheese (as the main raw material) with 4 different maturity degrees (4, 8, 12, and 16 wk of ripening). Moreover, the pH of the samples was adjusted (the target values within the range of 5.60-5.80), corresponding to the standard pH values of spreadable processed cheese. With respect to the individual application of emulsifying salts (regardless of the maturity degree of the Swiss-type cheese applied), the samples prepared with P20 were the hardest, followed by those prepared with TSPP, TSC, and DSP. Furthermore, a specific ratio of DSP:TSPP (1:1) led to a significant increase in the hardness of the samples. On the whole, the hardness of all processed cheese samples increased with the prolonging storage period, whereas their hardness significantly dropped with the rising ripening stage of the raw material utilized. In all of the cases, the trends of hardness development remained analogous, and only the absolute values differed significantly. Moreover, the findings of TPA were in accordance with those of the rheological analysis. In particular, the specific ratio of DSP:TSPP (1:1) resulted in the highest gel strength and interaction factor values, followed by P20, TSPP, TSC, and DSP (used individually), reporting the same trend which was demonstrated by TPA. The monitored values of the gel strength and interaction factor decreased with the increasing maturity degree of the Swiss-type cheese used. The intensity of the rigidity of the samples showed an analogous relationship to the intensity of the gel strength; the higher the gel strength of the sample, the more inflexible the product is expected to be. Copyright © 2016 American Dairy Science Association. Published by Elsevier Inc. All rights reserved.

Effect of co-milled wheat, green gram and barley on the rheological and quality characteristics of cookies.

PubMed

Tulse, Siddharth B; V, Reshma; Rajiv, Jyotsna; Sakhare, Suresh D

2015-10-01

Studies were carried out on the co-milling of wheat (W), green gram (GG) and barley (BR) grains using a roller milling system. The co-milled straight run flours obtained by varying proportions of wheat, barley and green gram WGGBR-1 (90:5:5), WGGBR-2 (80:10:10) and WGGBR-3 (70:15:15) were used in the cookie baking experiments. As the amount of GG and BR increased in blend, water absorption increased (56.5-58.4%) and dough stability and extensibility values decreased (104-92 mm). Hardness of cookie doughs and spread ratio (7.70-6.00) of cookies decreased and breaking strength values increased from 2900 to 3700 g in cookies made using co-milled blends WGGBR-1, WGGBR-2 and WGGBR-3. The highest breaking strength value (3700 g), large islands, gummy mouth feel and lowest overall quality score of 51.5 were recorded for cookies made with blend WGGBR-3 indicating that the cookies had unacceptable hard texture. The optimum blend for cookies was WGGBR-2 (80:10:10) and the cookies possessed slightly small islands, crisp, light texture and a pleasant taste. These cookies had 12.30 and 8.00% protein and dietary fibre as against the control cookie values of 8 and 4%, respectively. The in vitro protein digestibility of the control cookies was 61% and it was 51% for cookies made with WGGBR-2 blend. © The Author(s) 2014.

Technological, rheological and sensory characterizations of a yogurt containing an exopolysaccharide extract from Lactobacillus fermentum Lf2, a new food additive.

PubMed

Ale, Elisa C; Perezlindo, Marcos J; Pavón, Yanina; Peralta, Guillermo H; Costa, Silvia; Sabbag, Nora; Bergamini, Carina; Reinheimer, Jorge A; Binetti, Ana G

2016-12-01

Lactobacillus fermentum Lf2, an autochthonous strain isolated as a non starter culture in Cremoso cheese, produces high EPS levels (~1g/L) in optimized conditions (SDM broth, pH6.0, 30°C, 72h). Technological (texture profile and rheological analysis) and sensory properties of non-fat yogurts with 300 and 600mg EPS/L were studied at 3 and 25days after manufacture. Yogurts with different EPS concentrations showed higher hardness values than the control group at both periods of time, being the only significant difference that remained stable during time. The consistency index was also higher for the treated samples at both times evaluated, being significantly different for samples with 300mg/L of EPS extract, while the flow behavior index was lower for EPS-added yogurts. The thixotropic index was lower (P<0.05) for samples with the highest EPS extract concentration at the end of the storage time. Regarding the sensory analysis, those yogurts with 600mg/L of EPS extract presented the highest values of consistency at 3days of storage. No considerable differences for defects (milk powder, acid, bitter and cooked milk flavors) were perceived between treated and control samples at both times evaluated. Syneresis was also studied and samples with 600mg/L of EPS extract presented the lowest syneresis values at 25days of storage, which considerably decreased with the time of storage. In conclusion, the EPS from L. fermentum Lf2, used as an additive, provided yogurt with creamy consistency and increased hardness, without the presence of unwanted defects and improving the water holding capacity of the product. All the analysis done showed the potential of this extract to be used as a technofunctional natural ingredient, and it should be considered its positive impact on health, according to previous studies. Copyright © 2016 Elsevier Ltd. All rights reserved.

The X-ray photoelectron spectroscopy depth profiling and tribological characterization of ion-plated gold on various metals

NASA Technical Reports Server (NTRS)

Miyoshi, K.; Spalvins, T.; Buckley, D. H.

1983-01-01

For the case of ion-plated gold, the graded interface between gold and a nickel substrate and a nickel substrate, such tribological properties as friction and microhardness are examined by means of X-ray photoelectron spectroscopy analysis and depth profiling. Sliding was conducted against SiC pins in both the adhesive process, where friction arises from adhesion between sliding surfaces, and abrasion, in which friction is due to pin indentation and groove-plowing. Both types of friction are influenced by coating depth, but with opposite trends: the graded interface exhibited the highest adhesion, but the lowest abrasion. The coefficient of friction due to abrasion is inversely related to hardness. Graded interface microhardness values are found to be the highest, due to an alloying effect. There is almost no interface gradation between the vapor-deposited gold film and the substrate.

Silicone modified resins for graphite fiber laminates

NASA Technical Reports Server (NTRS)

Frost, L. W.; Bower, G. M.

1979-01-01

The development of silicon modified resins for graphite fiber laminates which will prevent the dispersal of graphite fibers when the composites are burned is discussed. Eighty-five silicone modified resins were synthesized and evaluated including unsaturated polyesters, thermosetting methacrylates, epoxies, polyimides, and phenolics. Neat resins were judged in terms of Si content, homogeneity, hardness, Char formation, and thermal stability. Char formation was estimated by thermogravimetry to 1,000 C in air and in N2. Thermal stability was evaluated by isothermal weight loss measurements for 200 hrs in air at three temperatures. Four silicone modified epoxies were selected for evaluation in unidirectional filament wound graphite laminates. Neat samples of these resins had 1,000 C char residues of 25 to 50%. The highest flexural values measured for the laminates were a strength of 140 kpsi and a modulus of 10 Mpsi. The highest interlaminar shear strength was 5.3 kpsi.

Pancreatic hardness: Correlation of surgeon’s palpation, durometer measurement and preoperative magnetic resonance imaging features

PubMed Central

Hong, Tae Ho; Choi, Joon-Il; Park, Michael Yong; Rha, Sung Eun; Lee, Young Joon; You, Young Kyoung; Choi, Moon Hyung

2017-01-01

AIM To evaluate the correlation between subjective assessments of pancreatic hardness based on the palpation, objective measurements using a durometer, and magnetic resonance imaging (MRI) findings for assessing pancreatic hardness. METHODS Eighty-three patients undergoing pancreatectomies were enrolled. An experienced surgeon subjectively evaluated the pancreatic hardness in the surgical field by palpation. The pancreatic hardness was also objectively evaluated using a durometer. Preoperative MRI findings were evaluated by a radiologist in terms of the apparent diffusion coefficient (ADC) values, the relative signal intensity decrease (RSID) of the pancreatic parenchyma, and the diameter of the pancreatic parenchyma and duct. Durometer measurement results, ADC values, RSID, pancreatic duct and parenchyma diameters, and the ratio of the diameters of the duct and parenchyma were compared between pancreases judged to be soft or hard pancreas on the palpation. A correlation analysis was also performed between the durometer and MRI measurements. RESULTS The palpation assessment classified 44 patients as having a soft pancreas and 39 patients as having a hard pancreas. ADC values were significantly lower in the hard pancreas group. The ductal diameter and duct-to-pancreas ratio were significantly higher in the hard pancreas group. For durometer measurements, a correlation analysis showed a positive correlation with the ductal diameter and the duct-to-pancreas ratio and a negative correlation with ADC values. CONCLUSION Hard pancreases showed lower ADC values, a wider pancreatic duct diameter and a higher duct-to-pancreas ratio than soft pancreases. Additionally, the ADC values, diameter of the pancreatic duct and duct-to-pancreas ratio were closely correlated with the durometer results. PMID:28373771

Pancreatic hardness: Correlation of surgeon's palpation, durometer measurement and preoperative magnetic resonance imaging features.

PubMed

Hong, Tae Ho; Choi, Joon-Il; Park, Michael Yong; Rha, Sung Eun; Lee, Young Joon; You, Young Kyoung; Choi, Moon Hyung

2017-03-21

To evaluate the correlation between subjective assessments of pancreatic hardness based on the palpation, objective measurements using a durometer, and magnetic resonance imaging (MRI) findings for assessing pancreatic hardness. Eighty-three patients undergoing pancreatectomies were enrolled. An experienced surgeon subjectively evaluated the pancreatic hardness in the surgical field by palpation. The pancreatic hardness was also objectively evaluated using a durometer. Preoperative MRI findings were evaluated by a radiologist in terms of the apparent diffusion coefficient (ADC) values, the relative signal intensity decrease (RSID) of the pancreatic parenchyma, and the diameter of the pancreatic parenchyma and duct. Durometer measurement results, ADC values, RSID, pancreatic duct and parenchyma diameters, and the ratio of the diameters of the duct and parenchyma were compared between pancreases judged to be soft or hard pancreas on the palpation. A correlation analysis was also performed between the durometer and MRI measurements. The palpation assessment classified 44 patients as having a soft pancreas and 39 patients as having a hard pancreas. ADC values were significantly lower in the hard pancreas group. The ductal diameter and duct-to-pancreas ratio were significantly higher in the hard pancreas group. For durometer measurements, a correlation analysis showed a positive correlation with the ductal diameter and the duct-to-pancreas ratio and a negative correlation with ADC values. Hard pancreases showed lower ADC values, a wider pancreatic duct diameter and a higher duct-to-pancreas ratio than soft pancreases. Additionally, the ADC values, diameter of the pancreatic duct and duct-to-pancreas ratio were closely correlated with the durometer results.

Friction and hardness of gold films deposited by ion plating and evaporation

NASA Technical Reports Server (NTRS)

Miyoshi, K.; Spalvins, T.; Buckley, D. H.

1983-01-01

Sliding friction experiments were conducted with ion-plated and vapor-deposited gold films on various substrates in contact with a 0.025-mm-radius spherical silicon carbide rider in mineral oil. Hardness measurements were also made to examine the hardness depth profile of the coated gold on the substrate. The results indicate that the hardness is influenced by the depth of the gold coating from the surface. The hardness increases with an increase in the depth. The hardness is also related to the composition gradient in the graded interface between the gold coating and the substrate. The graded interface exhibited the highest hardness resulting from an alloy hardening effect. The coefficient of friction is inversely related to the hardness, namely, the load carrying capacity of the surface. The greater the hardness that the metal surface possesses, the lower is the coefficient of friction. The graded interface exhibited the lowest coefficient of friction.

The XPS depth profiling and tribological characterization of ion-plated gold on various metals

NASA Technical Reports Server (NTRS)

Miyoshi, K.; Spalvins, T.; Buckley, D. H.

1983-01-01

Friction properties were measured with a gold film; the graded interface between gold and nickel substrate; and the nickel substrate. All sliding was conducted against hard silicon carbide pins in two processes. In the adhesive process, friction arises primarily from adhesion between sliding surfaces. In the abrasion process, friction occurs as a result of the hard pin sliding against the film, indenting into it, and plowing a series of grooves. Copper and 440 C stainless steel substrates were also used. Results indicate that the friction related to both adhesion and abrasion is influenced by coating depth. The trends in friction behavior as a function of film depth are, however, just the opposite. The graded interface exhibited the highest adhesion and friction, while the graded interface resulted in the lowest abrasion and friction. The coefficient of friction due to abrasion is inversely related to the hardness. The greater the hardness of the surface, the lower is the abrasion and friction. The microhardness in the graded interface exhibited the highest hardness due to an alloy hardening effect. Almost no graded interface between the vapor-deposited gold film and the substrates was detected.

Properties of bioadhesive ketoprofen liquid suppositories: preparation, determination of gelation temperature, viscosity studies and evaluation of mechanical properties using texture analyzer by 4 × 4 factorial design.

PubMed

Ozgüney, Işık; Kardhiqi, Anita

2014-12-01

Development and evaluation of thermosensitive and bioadhesive liquid suppositories containing ketoprofen (KP). This study was conducted to develope thermosensitive and bioadhesive liquid suppositories containing KP using poloxamer and different bioadhesive polymers and to investigate their gelation temperature, viscosity and mechanical properties. Bioadhesive liquid suppositories were prepared by the cold method using poloxamer 407 (P 407), Poloxamer 188 (P 188) and various amounts of different bioadhesive polymers. Their gelation temperatures, viscosity values and mechanical properties were determined using texture analyzer by 4 × 4 factorial design. It was seen that in presence of KP, gelation temperature of formulation P 407/P 188 (4/20%) significantly decreased from 64 to 37.1 °C. It is to be noted that addition of increasing concentrations of bioadhesive polymers lowered gelation temperature and its decrease was highest with addition of Carbopol 934 P (C). Results of texture profile analysis (TPA) showed that formulations containing C have significantly higher hardness and adhesiveness values than other bioadhesive formulations. According to TPA, gel structure of liquid suppository formulation F5, containing P 407/P 188/KP/C (4/20/2.5/0.8%), exhibited the greatest hardness, compressibilty, adhesiveness and besides greatest viscosity. According to mechanical properties and viscosity values, it was concluded that F5 could be a promising formulation.

A study on friability, hardness and fiber content analysis of fiber enriched milk tablet

NASA Astrophysics Data System (ADS)

Suzihaque, M. U. H.; Irfan, M. H.; Ibrahim, U. K.

2017-06-01

This study was performed to analyze the friability, hardness and fiber content of fiber enriched milk tablet derived from five different local fiber sources such as carrot, spinach, dragon fruit, mango and watermelon. Cow milk was mixed to complement with the tablet as a protein source. The powder were spray dried at 100°C, 120°C and 140°C and freeze dried at -60°C. The mixture of fruits and milk were made into equal ratio with the addition of 15 maltodextrin as a carrier. Tablets formed were used for friability and hardness test while dried powder were used for fiber content analysis. Dragon fruit tablet dried at 140°C have the highest friability with 11. 42 of weight loss. The second highest friability was spinach tablet dried at 100°C and 120°C drying temp erature with 9.30 and 9.28 respectively. The lowest friability was exhibited by carrot, mango and watermelon tablet at 100°C and dragon fruit at 120°C while carrot and spinach at 140°C. In contras t, none of the freeze dried tablets showed any weight loss hence they are not friable. For hardness test, all of the freeze dried showed to have higher tensile strength than spray dried, where carrot showed to be the highest at 2.27 Newton and the lowest were spray dried mango at 0.16 Newton. In fiber content analysis, freeze dried mango have the highest fiber content followed by freeze dried carrot and 140°C s pray dried carrot. It can be concluded that the higher the spray dry temperature, the more friable is the tablet. While, high friability leads to lower hardness of tablets. In terms of fiber content, the higher the spray dry temperature, the lower the fiber content found.

TiCN/TiNbCN multilayer coatings with enhanced mechanical properties

NASA Astrophysics Data System (ADS)

Caicedo, J. C.; Amaya, C.; Yate, L.; Gómez, M. E.; Zambrano, G.; Alvarado-Rivera, J.; Muñoz-Saldaña, J.; Prieto, P.

2010-08-01

Enhancement of mechanical properties by using a TiCN/TiNbCN multilayered system with different bilayer periods ( Λ) and bilayer numbers ( n) via magnetron sputtering technique was studied in this work. The coatings were characterized in terms of structural, chemical, morphological and mechanical properties by X-ray diffraction (XRD), atomic force microscopy (AFM), scanning electron microscopy (SEM), transmission electron microscopy (TEM) and nanoindentation. Results of the X-ray analysis showed reflections associated to FCC (1 1 1) crystal structure for TiCN/TiNbCN films. AFM analysis revealed a reduction of grain size and roughness when the bilayer number is increased and the bilayer period is decreased. Finally, enhancement of mechanical properties was determined via nanoindentation measurements. The best behavior was obtained when the bilayer period ( Λ) was 15 nm ( n = 200), yielding the highest hardness (42 GPa) and elastic modulus (408 GPa). The values for the hardness and elastic modulus are 1.6 and 1.3 times greater than the coating with n = 1, respectively. The enhancement effects in multilayer coatings could be attributed to different mechanisms for layer formation with nanometric thickness due to the Hall-Petch effect; because this effect, originally used to explain the increase in hardness with decreasing grain size in bulk polycrystalline metals, has also been used to explain hardness enhancements in multilayers taking into account the thickness reduction at individual single layers that make the multilayered system. The Hall-Petch model based on dislocation motion within layers and across layer interfaces, has been successfully applied to multilayers to explain this hardness enhancement.

Multiple regression equations modelling of groundwater of Ajmer-Pushkar railway line region, Rajasthan (India).

PubMed

Mathur, Praveen; Sharma, Sarita; Soni, Bhupendra

2010-01-01

In the present work, an attempt is made to formulate multiple regression equations using all possible regressions method for groundwater quality assessment of Ajmer-Pushkar railway line region in pre- and post-monsoon seasons. Correlation studies revealed the existence of linear relationships (r 0.7) for electrical conductivity (EC), total hardness (TH) and total dissolved solids (TDS) with other water quality parameters. The highest correlation was found between EC and TDS (r = 0.973). EC showed highly significant positive correlation with Na, K, Cl, TDS and total solids (TS). TH showed highest correlation with Ca and Mg. TDS showed significant correlation with Na, K, SO4, PO4 and Cl. The study indicated that most of the contamination present was water soluble or ionic in nature. Mg was present as MgCl2; K mainly as KCl and K2SO4, and Na was present as the salts of Cl, SO4 and PO4. On the other hand, F and NO3 showed no significant correlations. The r2 values and F values (at 95% confidence limit, alpha = 0.05) for the modelled equations indicated high degree of linearity among independent and dependent variables. Also the error % between calculated and experimental values was contained within +/- 15% limit.

The effect of nano-SiC on characteristics of ADC12/nano-SiC composite with Sr and TiB addition produced by stir casting process

NASA Astrophysics Data System (ADS)

Anne Zulfia, S.; Salshabia, Nadella; Dhaneswara, Donanta; Utomo, Budi Wahyu

2018-05-01

ADC12 reinforced nano SiC has been successfully produced by stir casting process. Nano SiC was added into ADC12 alloy varied from 0.05 to 0.3 vf-% while Al-5Ti-1B and Sr were kept constant at 0.04 and 0.02 wt-% respectively to all composites. Mg was added 10 wt% to improve reinforce's wettability. The addition of Al-5Ti-1B to the alloy was as grain refiner while Sr was added to modify Mg2Si. All composites were characterized both microstructures analysis and mechanical properties include tensile strength, hardness, wear rate, impact strength, and porosity. The highest properties of composites was obtained at 0.3 vf-% nano SiC addition with UTS of 155.4 MPa, hardness of 46.16 HRB, impact strength of 0.22 J/mm2, and wear rate of 1.71 × 10-5 mm3/m. Tensile strength and hardness increased as grain size and porosities decreased. The highest wear resistance was investigated on the composition with the highest hardness. Impact strength decreased due to increasing volume fraction of nano-SiC. The phases present in microsturucture was dominantly Mg2Si which also affected mechanical properties of these composites.

Heat generation caused by ablation of dental hard tissues with an ultrashort pulse laser (USPL) system.

PubMed

Braun, Andreas; Krillke, Raphael Franz; Frentzen, Matthias; Bourauel, Christoph; Stark, Helmut; Schelle, Florian

2015-02-01

Heat generation during the removal of dental hard tissues may lead to a temperature increase and cause painful sensations or damage dental tissues. The aim of this study was to assess heat generation in dental hard tissues following laser ablation using an ultrashort pulse laser (USPL) system. A total of 85 specimens of dental hard tissues were used, comprising 45 specimens of human dentine evaluating a thickness of 1, 2, and 3 mm (15 samples each) and 40 specimens of human enamel with a thickness of 1 and 2 mm (20 samples each). Ablation was performed with an Nd:YVO4 laser at 1,064 nm, a pulse duration of 9 ps, and a repetition rate of 500 kHz with an average output power of 6 W. Specimens were irradiated for 0.8 s. Employing a scanner system, rectangular cavities of 1-mm edge length were generated. A temperature sensor was placed at the back of the specimens, recording the temperature during the ablation process. All measurements were made employing a heat-conductive paste without any additional cooling or spray. Heat generation during laser ablation depended on the dental hard tissue (enamel or dentine) and the thickness of the respective tissue (p < 0.05). Highest temperature increase could be observed in the 1-mm thickness group for enamel. Evaluating the 1-mm group for dentine, a significantly lower temperature increase could be measured (p < 0.05) with lowest values in the 3-mm group (p < 0.05). A time delay for temperature increase during the ablation process depending on the material thickness was observed for both hard tissues (p < 0.05). Employing the USPL system to remove dental hard tissues, heat generation has to be considered. Especially during laser ablation next to pulpal tissues, painful sensations and potential thermal injury of pulp tissue might occur.

The bioaccumulation of210Po and210Pb in the southern Baltic organisms

NASA Astrophysics Data System (ADS)

Stepnowski, P.; Skwarzec, B.

1999-01-01

The paper presents the results of210Po and210Pb determinations in three species of Baltic invertebrates, crustacean Saduria entomon, molluscs Mya arenaria and Mytilus trossulus Obtained data show significant differences in activity concentrations of both radionuclides in the tissues and organs examined. The highest values for210Po were found in hepatopancreas of Mytlius trossulus. Similar concentration effect is observed in the same organ of Saduria entomon.210Po is not significantly accumulated in haemolymph and gonads of crustacean as well as shell and fat of molluscs. Great disproportion between210Po and210Pb is observed in the hard tissues of Saduria entomon.

Traceability in hardness measurements: from the definition to industry

NASA Astrophysics Data System (ADS)

Germak, Alessandro; Herrmann, Konrad; Low, Samuel

2010-04-01

The measurement of hardness has been and continues to be of significant importance to many of the world's manufacturing industries. Conventional hardness testing is the most commonly used method for acceptance testing and production quality control of metals and metallic products. Instrumented indentation is one of the few techniques available for obtaining various property values for coatings and electronic products in the micrometre and nanometre dimensional scales. For these industries to be successful, it is critical that measurements made by suppliers and customers agree within some practical limits. To help assure this measurement agreement, a traceability chain for hardness measurement traceability from the hardness definition to industry has developed and evolved over the past 100 years, but its development has been complicated. A hardness measurement value not only requires traceability of force, length and time measurements but also requires traceability of the hardness values measured by the hardness machine. These multiple traceability paths are needed because a hardness measurement is affected by other influence parameters that are often difficult to identify, quantify and correct. This paper describes the current situation of hardness measurement traceability that exists for the conventional hardness methods (i.e. Rockwell, Brinell, Vickers and Knoop hardness) and for special-application hardness and indentation methods (i.e. elastomer, dynamic, portables and instrumented indentation).

The effect of immersion time to low carbon steel hardness and microstructure with hot dip galvanizing coating method

NASA Astrophysics Data System (ADS)

Hakim, A. A.; Rajagukguk, T. O.; Sumardi, S.

2018-01-01

Along with developing necessities of metal materials, these rise demands of quality improvements and material protections especially the mechanical properties of the material. This research used hot dip galvanizing coating method. The objectives of this research were to find out Rockwell hardness (HRb), layer thickness, micro structure and observation with Scanning Electron Microscope (SEM) from result of coating by using Hot Dip Galvanizing coating method with immersion time of 3, 6, 9, and 12 minutes at 460°C. The result shows that Highest Rockwell hardness test (HRb) was at 3 minutes immersion time with 76.012 HRb. Highest thickness result was 217.3 μm at 12 minutes immersion. Microstructure test result showed that coating was formed at eta, zeta, delta and gamma phases, while Scanning Electron Microscope (SEM) showed Fe, Zn, Mn, Si and S elements at the specimens after coating.

A Method for Measuring the Hardness of the Surface Layer on Hot Forging Dies Using a Nanoindenter

NASA Astrophysics Data System (ADS)

Mencin, P.; van Tyne, C. J.; Levy, B. S.

2009-11-01

The properties and characteristics of the surface layer of forging dies are critical for understanding and controlling wear. However, the surface layer is very thin, and appropriate property measurements are difficult to obtain. The objective of the present study is to determine if nanoindenter testing provides a reliable method, which could be used to measure the surface hardness in forging die steels. To test the reliability of nanoindenter testing, nanoindenter values for two quenched and tempered steels (FX and H13) are compared to microhardness and macrohardness values. These steels were heat treated for various times to produce specimens with different values of hardness. The heat-treated specimens were tested using three different instruments—a Rockwell hardness tester for macrohardness, a Vickers hardness tester for microhardness, and a nanoindenter tester for fine scale evaluation of hardness. The results of this study indicate that nanoindenter values obtained using a Nanoindenter XP Machine with a Berkovich indenter reliably correlate with Rockwell C macrohardness values, and with Vickers HV microhardness values. Consequently, nanoindenter testing can provide reliable results for analyzing the surface layer of hot forging dies.

Oral health attitudes and behavior of dental students at the University of Zagreb, Croatia.

PubMed

Badovinac, Ana; Božić, Darko; Vučinac, Ivana; Vešligaj, Jasna; Vražić, Domagoj; Plancak, Darije

2013-09-01

The aim of this study was to investigate oral health behavior and attitudes of dental students in years 1 to 6 at the University of Zagreb, Croatia. The Croatian version of the Hiroshima University-Dental Behavioral Inventory (HU-DBI) was administered to predoctoral dental students, and collected data were analyzed. A total of 503 students (22.3 ± 2.6 mean age) completed the questionnaire. The response rate was 85.1 percent, and 72.4 percent of the respondents were female. These dental students' answers to eleven out of twenty HU-DBI items differed significantly by academic year. The mean questionnaire score was 6.62 ± 1.54, and the highest value of the HU-DBI score was in the fourth year (7.24 ± 1.54). First-year students were most likely to have a toothbrush with hard bristles and felt they had not brushed well unless done with hard strokes. Students in the sixth year were least worried about visiting a dentist and most frequently put off going to a dentist until having a toothache, indicating that rise of knowledge contributes to higher self-confidence. The mean HU-DBI score for these students showed average value, pointing out the need for a comprehensive oral hygiene and preventive program from the start of dental school.

Production of crispy bread snacks containing chicken meat and chicken meat powder.

PubMed

Cakmak, Hulya; Altinel, Burak; Kumcuoglu, Seher; Kisla, Duygu; Tavman, Sebnem

2016-01-01

Chicken meat in two different forms (chicken meat and chicken meat powder) were added into white flour and whole wheat blend baguette bread formulations for protein enrichment and finally developing new and healthy snacks. The chicken meat and powder levels were 10% for white flour baguette, and 15% for whole wheat blend. The dried baguette samples were packaged under 100% N2, and physical, chemical, microbiological and sensorial properties were evaluated during 3 months of storage. Protein content of chicken meat powder added samples were found statistically higher than chicken meat added samples. Hardness of the snacks was significantly affected from type of chicken meat, such as values were higher for chicken meat added samples than chicken meat powder added samples. Lipid oxidation of the snacks was determined by TBA analysis, and TBA value for whole wheat mixture snack with 15% of chicken meat was the highest among all during storage. The highest overall acceptance score was obtained from white flour snack with 10% chicken meat. There was no coliform bacteria detected during storage and the results of yeast-mold count and aerobic plate count of snacks remained between the quantitative ranges.

A sol-gel monolithic metal-organic framework with enhanced methane uptake.

PubMed

Tian, Tian; Zeng, Zhixin; Vulpe, Diana; Casco, Mirian E; Divitini, Giorgio; Midgley, Paul A; Silvestre-Albero, Joaquin; Tan, Jin-Chong; Moghadam, Peyman Z; Fairen-Jimenez, David

2018-02-01

A critical bottleneck for the use of natural gas as a transportation fuel has been the development of materials capable of storing it in a sufficiently compact form at ambient temperature. Here we report the synthesis of a porous monolithic metal-organic framework (MOF), which after successful packing and densification reaches 259 cm 3 (STP) cm -3 capacity. This is the highest value reported to date for conformed shape porous solids, and represents a greater than 50% improvement over any previously reported experimental value. Nanoindentation tests on the monolithic MOF showed robust mechanical properties, with hardness at least 130% greater than that previously measured in its conventional MOF counterparts. Our findings represent a substantial step in the application of mechanically robust conformed and densified MOFs for high volumetric energy storage and other industrial applications.

A sol-gel monolithic metal-organic framework with enhanced methane uptake

NASA Astrophysics Data System (ADS)

Tian, Tian; Zeng, Zhixin; Vulpe, Diana; Casco, Mirian E.; Divitini, Giorgio; Midgley, Paul A.; Silvestre-Albero, Joaquin; Tan, Jin-Chong; Moghadam, Peyman Z.; Fairen-Jimenez, David

2018-02-01

A critical bottleneck for the use of natural gas as a transportation fuel has been the development of materials capable of storing it in a sufficiently compact form at ambient temperature. Here we report the synthesis of a porous monolithic metal-organic framework (MOF), which after successful packing and densification reaches 259 cm3 (STP) cm-3 capacity. This is the highest value reported to date for conformed shape porous solids, and represents a greater than 50% improvement over any previously reported experimental value. Nanoindentation tests on the monolithic MOF showed robust mechanical properties, with hardness at least 130% greater than that previously measured in its conventional MOF counterparts. Our findings represent a substantial step in the application of mechanically robust conformed and densified MOFs for high volumetric energy storage and other industrial applications.

Laser cutting of bone tissue under bulk water with a pulsed ps-laser at 532 nm.

PubMed

Tulea, Cristian-Alexander; Caron, Jan; Gehlich, Nils; Lenenbach, Achim; Noll, Reinhard; Loosen, Peter

2015-10-01

Hard-tissue ablation was already investigated for a broad variety of pulsed laser systems, which cover almost the entire range of available wavelengths and pulse parameters. Most effective in hard-tissue ablation are Er:YAG and CO2 lasers, both utilizing the effect of absorption of infrared wavelengths by water and so-called explosive vaporization, when a thin water film or water–air spray is supplied. The typical flow rates and the water layer thicknesses are too low for surgical applications where bleeding occurs and wound flushing is necessary. We studied a 20 W ps-laser with 532 nm wavelength and a pulse energy of 1 mJ to effectively ablate bones that are submerged 14 mm under water. For these laser parameters, the plasma-mediated ablation mechanism is dominant. Simulations based on the blow-off model predict the cut depth and cross-sectional shape of the incision. The model is modified considering the cross section of the Gaussian beam, the incident angle, and reflections. The ablation rate amounts to 0.2  mm3/s, corresponding to an increase by at least 50% of the highest values published so far for ultrashort laser ablation of hard tissue.

Optimizing the Synthesis of Alumina Inserts Using Hot Isostatic Pressing (HIP)

NASA Astrophysics Data System (ADS)

Ariff, T. F.; Azhar, A. Z.; Sariff, M. N.; Rasid, S. N.; Zahari, S. Z.; Bahar, R.; Karim, M.; Nurul Amin, AKM

2018-01-01

Alumina or Aluminium Oxide (Al2O3) is well known for its high strength and hardness. Its low heat retention and low specific heat characteristics make it attractive to be used widely as a cutting tool for grinding, milling and turning processes. Various synthesis methods have been used for the purpose of enhancing the properties of the alumina inserts. However, the optimization process using Hot Isostatic Pressing (HIP) has not been performed. This research aims in finding the optimum parameters in synthesizing the alumina inserts (98Al2O3 1.6ZrO2 0.4MgO, 93Al2O3 6.4ZrO2 0.6MgO and 85Al2O3 14.5ZrO2 0.5MgO) using HIP at different temperatures (1200, 1250 and 1300°C) and sintering time (10, 30 and 60 minutes). Hardness, density, shrinkage and microstructure using SEM were analysed. The optimum sintering condition for the alumina insert was found in 98Al2O3 1.6ZrO2 0.4MgO sintered at 1300°C for 60 minutes for it exhibited the highest values of hardness (1917HV), density (3.95g/cm3), shrinkage (9.6%).

A customer value analysis of Taiwan ice cream market: a means-end chain approach across consumption situations.

PubMed

Chen, Yan-Kwang; Tsai, Pei-Shan; Chiu, Fei-Rung

2015-01-01

In the highly competitive market, it is increasingly hard for ice cream stores to develop creative marketing strategies to retain existing customers and attract new ones. This study applies the means-end chain approach to identify the customer value, consequences, and attributes of ice cream and to suggest useful information for ice cream sellers to develop differential marketing strategies across various consumption situations (i.e. on a date, gathering with friends, craving for ice cream). This study conducted one-on-one in-depth interviews with participants. The interview content was subsequently analyzed and coded to produce an implication matrix and a hierarchical value map, which was further used to determine customers' value perceptions. The results indicate the terminal values of the highest strength comprised economy, pleasure, and efficiency. Pleasure was emphasized among consumers who were on a date or gathering with friends, whereas satisfaction was emphasized among consumers who craved ice cream. Based on the results, the study also provides suggestions to the industry and future researchers.

High-Strength Ultra-Fine-Grained Hypereutectic Al-Si-Fe-X (X = Cr, Mn) Alloys Prepared by Short-Term Mechanical Alloying and Spark Plasma Sintering.

PubMed

Průša, Filip; Bláhová, Markéta; Vojtěch, Dalibor; Kučera, Vojtěch; Bernatiková, Adriana; Kubatík, Tomáš František; Michalcová, Alena

2016-11-30

In this work, Al-20Si-10Fe-6Cr and Al-20Si-10Fe-6Mn (wt %) alloys were prepared by a combination of short-term mechanical alloying and spark plasma sintering. The microstructure was composed of homogeneously dispersed intermetallic particles forming composite-like structures. X-ray diffraction analysis and TEM + EDS analysis determined that the α-Al along with α-Al 15 (Fe,Cr)₃Si₂ or α-Al 15 (Fe,Mn)₃Si₂ phases were present, with dimensions below 130 nm. The highest hardness of 380 ± 7 HV5 was observed for the Al-20Si-10Fe-6Mn alloy, exceeding the hardness of the reference as-cast Al-12Si-1Cu-1 Mg-1Ni alloy (121 ± 2 HV5) by nearly a factor of three. Both of the prepared alloys showed exceptional thermal stability with the hardness remaining almost the same even after 100 h of annealing at 400 °C. Additionally, the compressive strengths of the Al-20Si-10Fe-6Cr and Al-20Si-10Fe-6Mn alloys reached 869 MPa and 887 MPa, respectively, and had virtually the same values of 870 MPa and 865 MPa, respectively, even after 100 h of annealing. More importantly, the alloys showed an increase in ductility at 400 °C, reaching several tens of percent. Thus, both of the investigated alloys showed better mechanical properties, including superior hardness, compressive strength and thermal stability, as compared to the reference Al-10Si-1Cu-1Mg-1Ni alloy, which softened remarkably, reducing its hardness by almost 50% to 63 ± 8 HV5.

High-Strength Ultra-Fine-Grained Hypereutectic Al-Si-Fe-X (X = Cr, Mn) Alloys Prepared by Short-Term Mechanical Alloying and Spark Plasma Sintering

PubMed Central

Průša, Filip; Bláhová, Markéta; Vojtěch, Dalibor; Kučera, Vojtěch; Bernatiková, Adriana; Kubatík, Tomáš František; Michalcová, Alena

2016-01-01

In this work, Al-20Si-10Fe-6Cr and Al-20Si-10Fe-6Mn (wt %) alloys were prepared by a combination of short-term mechanical alloying and spark plasma sintering. The microstructure was composed of homogeneously dispersed intermetallic particles forming composite-like structures. X-ray diffraction analysis and TEM + EDS analysis determined that the α-Al along with α-Al15(Fe,Cr)3Si2 or α-Al15(Fe,Mn)3Si2 phases were present, with dimensions below 130 nm. The highest hardness of 380 ± 7 HV5 was observed for the Al-20Si-10Fe-6Mn alloy, exceeding the hardness of the reference as-cast Al-12Si-1Cu-1 Mg-1Ni alloy (121 ± 2 HV5) by nearly a factor of three. Both of the prepared alloys showed exceptional thermal stability with the hardness remaining almost the same even after 100 h of annealing at 400 °C. Additionally, the compressive strengths of the Al-20Si-10Fe-6Cr and Al-20Si-10Fe-6Mn alloys reached 869 MPa and 887 MPa, respectively, and had virtually the same values of 870 MPa and 865 MPa, respectively, even after 100 h of annealing. More importantly, the alloys showed an increase in ductility at 400 °C, reaching several tens of percent. Thus, both of the investigated alloys showed better mechanical properties, including superior hardness, compressive strength and thermal stability, as compared to the reference Al-10Si-1Cu-1Mg-1Ni alloy, which softened remarkably, reducing its hardness by almost 50% to 63 ± 8 HV5. PMID:28774094

Microstructure, Hardness, and Residual Stress Distributions in T-Joint Weld of HSLA S500MC Steel

NASA Astrophysics Data System (ADS)

Frih, Intissar; Montay, Guillaume; Adragna, Pierre-Antoine

2017-03-01

This paper investigates the characterization of the microstructure, hardness, and residual stress distributions of MIG-welded high-strength low-alloy S500MC steel. The T-joint weld for 10-mm-thick plates was joined using a two passes MIG welding technology. The contour method was performed to measure longitudinal welding residual stress. The obtained results highlighted a good correlation between the metallurgical phase constituents and hardness distribution within the weld zones. In fact, the presence of bainite and smaller ferrite grain size in the weld-fusion zone might be the reason for the highest hardness measured in this region. A similar trend of the residual stress and hardness distributions was also obtained.

Effect of cow and soy milk on enamel hardness of immersed teeth

NASA Astrophysics Data System (ADS)

Widanti, H. A.; Herda, E.; Damiyanti, M.

2017-08-01

Cow milk and soy milk have different mineral contents and this can affect the tooth remineralization process. The aim of this study was to determine the effect of cow and soy milk on immersed teeth after demineralization. Twenty-one specimens, of human maxillary premolars, were measured for enamel hardness before immersion and demineralization in orange juice. The teeth were divided into three groups (n = 7) with each group immersed in either distilled water, cow milk, or soy milk. There was a significant increase in enamel hardness in all groups (p < 0.05). Cow milk provided the highest increase in enamel hardness, of all the three groups, but was not able to restore the initial enamel hardness.

A study on hardness behavior of geopolymer paste in different condition

NASA Astrophysics Data System (ADS)

Zainal, Farah Farhana; Hussin, Kamarudin; Rahmat, Azmi; Abdullah, Mohd Mustafa Al Bakri; Shamsudin, Shaiful Rizam

2016-07-01

This study has been conducted to understand the hardness behavior of geopolymer paste in different conditions; with and without being immersed in water. Geopolymer paste has been used nowadays as an alternative way to reduce global warming pollution by carbon dioxide (CO2) released to the air caused from the production of Ordinary Portland Cement (OPC). Geopolymer has many advantages such as high compressive strength, lower water absorption and lower porosity. Geopolymer paste in this study was made from a mixture of fly ash and alkaline activators. The alkaline activators that have been used were sodium hydroxide (NaOH) solution and sodium silicate (Na2SiO3) solution. Then the mixture was allowed to harden for 24hrs at ambient temperature and then placed in the oven for 24hrs with 60°C for the curing process. The hardness testing was conducted after a few months when the samples already achieved the optimum design. The samples were divided to two conditions; without immersion which was placed at ambient temperature (S1) and immersed in water for one week (S2). The samples then are divided into two at the center and testing was conducted into 4 parts which are part 1, part 2, part 3 and part 4. Various methods of non-destructively testing concrete and mortar have been in use for many years such as Vickers hardness test, Rockwell hardness test, Brinell hardness test and many more. The Rockwell hardness test method as defined in ASTM E-18 is the most commonly used hardness test method which is also used in this study. From the results, S1 has higher hardness value than S2 for all parts with the maximum value of S1 is 118.6 and the minimum value is 71.8. The maximum value of S2 is 114.4 and the minimum value is 0. The central part of the geopolymer paste also showed greater hardness values than the edge area of the samples.

Investigation on the effect of Friction Stir Processing Parameters on Micro-structure and Micro-hardness of Rice Husk Ash reinforced Al6061 Metal Matrix Composites

NASA Astrophysics Data System (ADS)

Fatchurrohman, N.; Farhana, N.; Marini, C. D.

2018-03-01

Friction stir processing (FSP) is an alternative way to produce the surface composites of aluminium alloy in order to modify the microstructure and improve the mechanical properties. In this experiment, Al6061 aluminium alloy has been chosen to be used as the matrix base plate for the FSP. Al606 has potential for the use in advanced application but it has low wear resistance. While, the reinforced used was rice husk ash (RHA) in order to produce surface composites which increased the micro hardness of the plate composites. The Al6061 was stirred individually and with 5 weight % of RHA at three different tool rotational speeds of 800 rpm, 1000 rpm and 1200 rpm. After running the FSP, the result in the distribution of particles and the micro hardness of the specimens were identified. The result showed that Al6061 plate with the existing 5 weight % of RHA reinforced at the highest of tool rotational speeds of 1200rpm has the best distribution of particles and the highest result in average of micro hardness with 80Hv.

Diversity within Italian Cheesemaking Brine-Associated Bacterial Communities Evidenced by Massive Parallel 16S rRNA Gene Tag Sequencing

PubMed Central

Marino, Marilena; Innocente, Nadia; Maifreni, Michela; Mounier, Jérôme; Cobo-Díaz, José F.; Coton, Emmanuel; Carraro, Lisa; Cardazzo, Barbara

2017-01-01

This study explored the bacterial diversity of brines used for cheesemaking in Italy, as well as their physicochemical characteristics. In this context, 19 brines used to salt soft, semi-hard, and hard Italian cheeses were collected in 14 commercial cheese plants and analyzed using a culture-independent amplicon sequencing approach in order to describe their bacterial microbiota. Large NaCl concentration variations were observed among the selected brines, with hard cheese brines exhibiting the highest values. Acidity values showed a great variability too, probably in relation to the brine use prior to sampling. Despite their high salt content, brine microbial loads ranged from 2.11 to 6.51 log CFU/mL for the total mesophilic count. Microbial community profiling assessed by 16S rRNA gene sequencing showed that these ecosystems were dominated by Firmicutes and Proteobacteria, followed by Actinobacteria and Bacteroidetes. Cheese type and brine salinity seem to be the main parameters accountable for brine microbial diversity. On the contrary, brine pH, acidity and protein concentration, correlated to cheese brine age, did not have any selective effect on the microbiota composition. Nine major genera were present in all analyzed brines, indicating that they might compose the core microbiome of cheese brines. Staphylococcus aureus was occasionally detected in brines using selective culture media. Interestingly, bacterial genera associated with a functional and technological use were frequently detected. Indeed Bifidobacteriaceae, which might be valuable probiotic candidates, and specific microbial genera such as Tetragenococcus, Corynebacterium and non-pathogenic Staphylococcus, which can contribute to sensorial properties of ripened cheeses, were widespread within brines. PMID:29163411

Preparation of multi-layer film consisting of hydrogen-free DLC and nitrogen-containing DLC for conductive hard coating

NASA Astrophysics Data System (ADS)

Iijima, Yushi; Harigai, Toru; Isono, Ryo; Degai, Satoshi; Tanimoto, Tsuyoshi; Suda, Yoshiyuki; Takikawa, Hirofumi; Yasui, Haruyuki; Kaneko, Satoru; Kunitsugu, Shinsuke; Kamiya, Masao; Taki, Makoto

2018-01-01

Conductive hard-coating films have potential application as protective films for contact pins used in the electrical inspection process for integrated circuit chips. In this study, multi-layer diamond-like carbon (DLC) films were prepared as conductive hard-coating films. The multi-layer DLC films consisting of DLC and nitrogen-containing DLC (N-DLC) film were prepared using a T-shape filtered arc deposition method. Periodic DLC/N-DLC four-layer and eight-layer films had the same film thickness by changing the thickness of each layer. In the ball-on-disk test, the N-DLC mono-layer film showed the highest wear resistance; however, in the spherical polishing method, the eight-layer film showed the highest polishing resistance. The wear and polishing resistance and the aggressiveness against an opponent material of the multi-layer DLC films improved by reducing the thickness of a layer. In multi-layer films, the soft N-DLC layer between hard DLC layers is believed to function as a cushion. Thus, the tribological properties of the DLC films were improved by a multi-layered structure. The electrical resistivity of multi-layer DLC films was approximately half that of the DLC mono-layer film. Therefore, the periodic DLC/N-DLC eight-layer film is a good conductive hard-coating film.

Thermomagnetic and thermoelectric properties of semiconductors (PbTe, PbSe) at ultrahigh pressures

NASA Astrophysics Data System (ADS)

Ovsyannikov, Sergey V.; Shchennikov, Vladimir V.

2004-02-01

The longitudinal and transverse thermomagnetic Nernst-Ettingshausen (LNE, TNE) effects and the Maggi-Reghi-Leduc (MRL) effect were measured on PbTe and PbSe micro-samples at ultrahigh pressures upto 20 GPa. Values of the mobility of charge carriers as well as the scattering parameter were estimated both for the low- and high-pressure phase of PbTe and PbSe. At about 3 GPa, the maxima of both Nernst-Ettingshausen effects and magnetoresistance (MR) (and hence of the mobility of charge carriers μ), attributed to the gapless state of PbTe and PbSe were established. The TNE effect was found to be the largest among the effects measured, while the MRL was hardly visible even at the highest mobility values of the charge carriers. The possibilities for using thermomagnetic effects in micro-device technologies are discussed.

The relationship between grain hardness, dough mixing parameters and bread-making quality in winter wheat.

PubMed

Salmanowicz, Bolesław P; Adamski, Tadeusz; Surma, Maria; Kaczmarek, Zygmunt; Karolina, Krystkowiak; Kuczyńska, Anetta; Banaszak, Zofia; Lugowska, Bogusława; Majcher, Małgorzata; Obuchowski, Wiktor

2012-01-01

The influence of grain hardness, determined by using molecular markers and physical methods (near-infrared (NIR) technique and particle size index-PSI) on dough characteristics, which in turn were determined with the use of a farinograph and reomixer, as well as bread-making properties were studied. The material covered 24 winter wheat genotypes differing in grain hardness. The field experiment was conducted at standard and increased levels of nitrogen fertilization. Results of molecular analyses were in agreement with those obtained by the use of physical methods for soft-grained lines. Some lines classified as hard (by physical methods) appeared to have the wild-type Pina and Pinb alleles, similar to soft lines. Differences in dough and bread-making properties between lines classified as hard and soft on the basis of molecular data appeared to be of less significance than the differences between lines classified as hard and soft on the basis of physical analyses of grain texture. Values of relative grain hardness at the increased nitrogen fertilization level were significantly higher. At both fertilization levels the NIR parameter determining grain hardness was significantly positively correlated with the wet gluten and sedimentation values, with most of the rheological parameters and bread yield. Values of this parameter correlated with quality characteristics in a higher degree than values of particle size index.

The Relationship Between Grain Hardness, Dough Mixing Parameters and Bread-Making Quality in Winter Wheat

PubMed Central

Salmanowicz, Bolesław P.; Adamski, Tadeusz; Surma, Maria; Kaczmarek, Zygmunt; Karolina, Krystkowiak; Kuczyńska, Anetta; Banaszak, Zofia; Ługowska, Bogusława; Majcher, Małgorzata; Obuchowski, Wiktor

2012-01-01

The influence of grain hardness, determined by using molecular markers and physical methods (near-infrared (NIR) technique and particle size index—PSI) on dough characteristics, which in turn were determined with the use of a farinograph and reomixer, as well as bread-making properties were studied. The material covered 24 winter wheat genotypes differing in grain hardness. The field experiment was conducted at standard and increased levels of nitrogen fertilization. Results of molecular analyses were in agreement with those obtained by the use of physical methods for soft-grained lines. Some lines classified as hard (by physical methods) appeared to have the wild-type Pina and Pinb alleles, similar to soft lines. Differences in dough and bread-making properties between lines classified as hard and soft on the basis of molecular data appeared to be of less significance than the differences between lines classified as hard and soft on the basis of physical analyses of grain texture. Values of relative grain hardness at the increased nitrogen fertilization level were significantly higher. At both fertilization levels the NIR parameter determining grain hardness was significantly positively correlated with the wet gluten and sedimentation values, with most of the rheological parameters and bread yield. Values of this parameter correlated with quality characteristics in a higher degree than values of particle size index. PMID:22605973

Lactose, galactose and glucose determination in naturally "lactose free" hard cheese: HPAEC-PAD method validation.

PubMed

Monti, Lucia; Negri, Stefano; Meucci, Aurora; Stroppa, Angelo; Galli, Andrea; Contarini, Giovanna

2017-04-01

A chromatographic method by HPAEC-PAD was developed and in-house validated for the quantification of low sugar levels in hard cheese, specifically Grana Padano PDO cheese. Particular attention was paid to the extraction procedure, due to residual microbial and enzymatic activities. Specificity in detection and linearity were verified. Recoveries ranged from 93% for lactose to 98% for glucose and galactose. The obtained LOD and LOQ values were, respectively, 0.25 and 0.41mg/100g for lactose, 0.14 and 0.27mg/100g for galactose, and 0.16 and 0.26mg/100g for glucose. The method was applied to 59 samples of Grana Padano PDO cheese: galactose showed the highest concentration and variability among the samples (1.36±0.89), compared to both lactose (0.45±0.12) and glucose (0.46±0.13). Considering the very low levels of sugars detected, authentic PDO Grana Padano could be safely included in the diet of people suffering from lactose intolerance. Copyright © 2016 Elsevier Ltd. All rights reserved.

Lithological and hydrochemical controls on distribution and speciation of uranium in groundwaters of hard-rock granitic aquifers of Madurai District, Tamil Nadu (India).

PubMed

Thivya, C; Chidambaram, S; Keesari, Tirumalesh; Prasanna, M V; Thilagavathi, R; Adithya, V S; Singaraja, C

2016-04-01

Uranium is a radioactive element normally present in hexavalent form as U(VI) in solution and elevated levels in drinking water cause health hazards. Representative groundwater samples were collected from different litho-units in this region and were analyzed for total U and major and minor ions. Results indicate that the highest U concentration (113 µg l(-1)) was found in granitic terrains of this region and about 10 % of the samples exceed the permissible limit for drinking water. Among different species of U in aqueous media, carbonate complexes [UO2(CO3)(2)(2-)] are found to be dominant. Groundwater with higher U has higher pCO2 values, indicating weathering by bicarbonate ions resulting in preferential mobilization of U in groundwater. The major minerals uraninite and coffinite were found to be supersaturated and are likely to control the distribution of U in the study area. Nature of U in groundwater, the effects of lithology on hydrochemistry and factors controlling its distribution in hard rock aquifers of Madurai district are highlighted in this paper.

TiC-Fe-Based Composite Coating Prepared by Self-Propagating High-Temperature Synthesis

NASA Astrophysics Data System (ADS)

He, Shen; Fan, Xi'an; Chang, Qingming; Xiao, Lixiang

2017-06-01

TiC-Fe-based composite coatings were prepared in situ by self-propagating high-temperature synthesis combined with vacuum expendable pattern casting process. The band-like TiC phase embedded in a continuous Fe binder. There were no obvious defects and impurities at the interface between coatings and matrices. Fe presented consecutively in the coating zones and substrate zones without interruption and the microhardness in the cross-sectional area of the coating-matrix reduces continuously from the coating to the matrix area, indicating a good metallurgical bonding between the coatings and matrices. The effect of casting temperature on the microstructure and hardness of TiC-Fe-based composite coating was investigated in detail. The TiC particles formed at low casting temperature were nearly spherical in shape, and the size of TiC particles increased with increasing casting temperature due to more agglomeration. The hardness of the coatings increased first and then decreased with increasing casting temperature, and reached the highest value of 68 HRC when the casting temperature was 1773 K (1500 °C), which was twice more than that of the matrix.

Fat reduction in comminuted meat products-effects of beef fat, regular and pre-emulsified canola oil.

PubMed

Youssef, M K; Barbut, S

2011-04-01

The effects of fat reduction (25.0%, 17.5%, and 10.0%) and substituting beef fat with canola oil or pre-emulsified canola oil (using soy protein isolate, sodium caseinate or whey protein isolate) on cooking loss, texture and color of comminuted meat products were investigated. Reducing fat from 25 to 10% increased cooking loss and decreased hardness. Canola oil or pre-emulsified treatments showed a positive effect on improving yield and restoring textural parameters. Using sodium caseinate to pre-emulsify the oil resulted in the highest hardness value. Cohesiveness was affected by fat type and level. The color of reduced fat meat batters was darker for all, except the beef fat treatments. Using canola oil or pre-emulsified oil resulted in a significant reduction in redness. The results show that pre-emulsification can offset some of the changes in reduced fat meat products when more water is used to substitute for the fat and that pre-emulsification can also help to produce a more stable meat matrix. © 2010 The American Meat Science Association. Published by Elsevier Ltd. All rights reserved.

Effects of process parameters on the properties of barley containing snacks enriched with brewer's spent grain.

PubMed

Kirjoranta, Satu; Tenkanen, Maija; Jouppila, Kirsi

2016-01-01

Brewer's spent grain (BSG), a by-product of malting of barley in the production of malt extract, was used as an ingredient in extruded barley-based snacks in order to improve the nutritional value of the snacks and widen the applications of this by-product in food sector. The effects of the extrusion parameters on the selected properties of the snacks were studied. Snacks with different ingredients including whole grain barley flour, BSG, whey protein isolate (WPI), barley starch and waxy corn starch were produced in 5 separate trials using a co-rotating twin-screw extruder. Extrusion parameters were water content of the mass (17-23 %), screw speed (200-500 rpm) and temperature of the last section and die (110-150 °C). Expansion, hardness and water content of the snacks were determined. Snacks containing barley flour and BSG (10 % of solids) had small expansion and high hardness. Addition of WPI (20 % of solids) increased expansion only slightly. Snacks with high expansion and small hardness were obtained when part of the barley flour was replaced with starch (barley or waxy corn). Yet, the highest expansion and the smallest hardness were achieved when barley flour was used with barley starch and WPI without BSG. Furthermore, expansion increased by increasing screw speed and decreasing water content of the mass in most of the trials. This study showed that BSG is a suitable material for extruded snacks rich in dietary fiber. Physical properties of the snacks could be improved by using barley or waxy corn starch and WPI.

Fabrication of modified GIC: GIC-nanoSiO2-HA-ZrO2 using two different mixing methods

NASA Astrophysics Data System (ADS)

Ghazali, Nor Ainon Maziah; Bakar, Wan Zaripah Wan; Rahman, Ismail Ab; Masudi, Sam'an Malik

2017-12-01

Conventional glass ionomer cement (GIC) is among the mostly used material in dentistry but some modifications were needed due to its deficiencies such as low mechanical strength and opacity. In this study, a new nanocomposite, GIC-nanoSiO2-HA-ZrO2 was fabricated whereby zirconia is added to improve the hardness. The nanocomposite of SiO2-HA-ZrO2 was synthesized using two different mixing methods which are one pot and spatulation methods. One pot method involved the addition of zirconia nanopowder during the one pot synthesis of nanoSiO2-HA and spatulation method involved the addition of zirconia nanopowder by controlled grinding process using mortar and pestle. Different weight percentage from 1-20 % of nanoSiO2-HA-ZrO2 was added to GIC and the hardness was analyzed using Vickers Tester. The one pot method recorded the highest and significant hardness value at 3 % addition which is ˜75.27 HV (± 2.48) compared to spatulation method ˜69.53 HV (± 7.78) at p < 0.05. Scanning Electron Microscope image from one pot method showed less agglomeration of the nanopowder and nanozirconia is uniformly distributed. Within the limitation of this study, one pot method produced better GIC-nanoSiO2-HA-ZrO2 composite.

Combined Effect of Long Processing Time and Na2SiF6 on the Properties of PEO Coatings Formed on AZ91D

NASA Astrophysics Data System (ADS)

Rehman, Zeeshan Ur; Koo, Bon Heun

2016-08-01

In this study, protective ceramic coatings were prepared on AZ91D magnesium alloy by plasma electrolytic oxidation (PEO) to improve the corrosion and mechanical properties of AZ91D magnesium alloy. The process was conducted in silicate-fluoride-based electrolyte solution. It was found that the average micro-hardness of the coating was significantly increased with an increase in the PEO processing time. The highest value of the average micro-hardness ~1271.2 HV was recorded for 60-min processing time. The phase analysis of the coatings indicated that they were mainly composed of Mg2SiO4, MgO, and MgF2 phases. The surface and cross-sectional study demonstrated that porosity was largely reduced with processing time, together with the change in pore geometry from irregular to spherical shape. The results of the polarization test in 3.5 wt.% NaCl solution revealed that aggressive corrosion took place for 5-min sample; however, the corrosion current was noticeably decreased to 0.43 × 10-7 A/cm2 for the 60-min-coated sample. The superior nobility and hardness for long processing time are suggested to be due to the dense and highly thick coating, coupled with the presence of MgF2 phase.

Effects of Ground, Concentrated, and Powdered Beef on the Quality of Noodle Products

PubMed Central

Choi, Jin Young

2014-01-01

The aim of this study was to ascertain the effects of beef on the quality characteristics, such as color, texture profile, water absorption ratio, volume, turbidity, and sensory evaluation, of noodle products. Various types of beef were added to the flour at a mixture ratio of ground beef (BG) 10, 15, 20, 25%; concentrated beef (BC) 9, 11, 13, 15%; and powdered beef (BP) 1, 3, 5, 7%. Each treatment was analyzed and compared with a 100% flour noodle as a control. With increasing BG, BC, and BP ratios, the L and b values for color decreased, while the a value increased, from that in the control. The hardness of the noodles treated with BG increased with increasing mixture ratios, but hardness decreased in the BC and BP treatments with increasing mixture ratios (p<0.05). The noodles with the largest beef composition in the mixtures of each treatment exhibited the highest turbidity scores, which was believed to be because the solid contents would be transferred to the soup during heating. In the sensory evaluation of cooked noodles, the BG 10%, BC 9%, and BP 1% treatments exhibited the best color. In an overall preference test, 20% of BG and 3% of BP could be added to the noodles. The best palatability was exhibited by the BG 10%, BC 13%, and BP 3% treatments. PMID:26761675

Toward improved mechanical, tribological, corrosion and in-vitro bioactivity properties of mixed oxide nanotubes on Ti-6Al-7Nb implant using multi-objective PSO.

PubMed

Rafieerad, A R; Bushroa, A R; Nasiri-Tabrizi, B; Kaboli, S H A; Khanahmadi, S; Amiri, Ahmad; Vadivelu, J; Yusof, F; Basirun, W J; Wasa, K

2017-05-01

Recently, the robust optimization and prediction models have been highly noticed in district of surface engineering and coating techniques to obtain the highest possible output values through least trial and error experiments. Besides, due to necessity of finding the optimum value of dependent variables, the multi-objective metaheuristic models have been proposed to optimize various processes. Herein, oriented mixed oxide nanotubular arrays were grown on Ti-6Al-7Nb (Ti67) implant using physical vapor deposition magnetron sputtering (PVDMS) designed by Taguchi and following electrochemical anodization. The obtained adhesion strength and hardness of Ti67/Nb were modeled by particle swarm optimization (PSO) to predict the outputs performance. According to developed models, multi-objective PSO (MOPSO) run aimed at finding PVDMS inputs to maximize current outputs simultaneously. The provided sputtering parameters were applied as validation experiment and resulted in higher adhesion strength and hardness of interfaced layer with Ti67. The as-deposited Nb layer before and after optimization were anodized in fluoride-base electrolyte for 300min. To crystallize the coatings, the anodically grown mixed oxide TiO 2 -Nb 2 O 5 -Al 2 O 3 nanotubes were annealed at 440°C for 30min. From the FESEM observations, the optimized adhesive Nb interlayer led to further homogeneity of mixed nanotube arrays. As a result of this surface modification, the anodized sample after annealing showed the highest mechanical, tribological, corrosion resistant and in-vitro bioactivity properties, where a thick bone-like apatite layer was formed on the mixed oxide nanotubes surface within 10 days immersion in simulated body fluid (SBF) after applied MOPSO. The novel results of this study can be effective in optimizing a variety of the surface properties of the nanostructured implants. Copyright © 2016 Elsevier Ltd. All rights reserved.

Integral Equation Study of Molecular Fluids and Liquid Crystals in Two Dimensions

NASA Astrophysics Data System (ADS)

Ward, David Atlee

The Ornstein-Zernike (OZ) equation is solved with a Percus-Yevick (PY) closure for the hard ellipse and hard planar dumbell fluids in two dimensions. The correlation functions, including the orientation correlation function, are expanded in a set of orthogonal functions and the coefficients are solved for using an iterative algorithm developed by Lado. The pressure, compressibility, and orientation coefficients are computed for a variety of densities and molecular elongations. The hard planar dumbell fluid shows no orientational ordering. The PY values for the pressure differ from the corresponding Monte Carlo (MC) values by as much as 8% for the cases studied. The hard ellipse fluid exhibits some orientational ordering. Ordering is much more pronounced for ellipses with an axis ratio larger than 2.0. Pressure values computed for the hard ellipse fluid from the PY theory differ from the corresponding MC values by as much as 11% for the cases studied. As the PY solutions do exhibit a nematic character in the hard ellipse fluid, we find it to be a viable reference system for further studies of the nematic liquid crystal phase, though the isotropic-nematic (I-N) phase transition found by Vieillard-Baron was not observed in the PY solutions. The Maier-Saupe theory was reformulated based on the density functional formalism of Sluckin and Shukla. Using PY data of the hard ellipse as input for the direct correlation function in the isotropic phase, the orientational distribution was calculated. The values obtained showed only extremely weak nematic behavior.

Effect of sintering atmosphere on the hardness of ThO2

NASA Astrophysics Data System (ADS)

Baena, Angela; Cardinaels, Thomas; Van Eyken, Jelle; Puzzolante, Jean Louis; Binnemans, Koen; Verwerft, Marc

2016-08-01

The hardness and toughness of ThO2 sintered under reducing and oxidizing conditions has been investigated and, quite unexpectedly, a significant difference in hardness was observed for the entire range of porosities studied. Reducing conditions systematically yielded higher hardness values than oxidizing conditions. Extrapolated to zero porosity, the hardness for ThO2 is H0 = 10.5 ± 0.3 GPa for oxidizing conditions and H0 = 12.4 ± 0.7 GPa for reducing conditions. Toughness values have been derived from Vickers indentations; differences in toughness were insignificant and only a single value is proposed: KIC = 0.97 ± 0.12 MPa √m. The difference in hardness is attributed to the presence of point defects, also acting as color centers and causing grey coloration of ThO2 sintered under reducing conditions. Furthermore, and of interest for nuclear fuel production, is the finding that ThO2 sintered under reducing conditions is significantly easier to grind compared to material sintered under oxidizing conditions.

Assessment of the hardness of different orthodontic wires and brackets produced by metal injection molding and conventional methods

PubMed Central

Alavi, Shiva; Kachuie, Marzie

2017-01-01

Background: This study was conducted to assess the hardness of orthodontic brackets produced by metal injection molding (MIM) and conventional methods and different orthodontic wires (stainless steel, nickel-titanium [Ni-Ti], and beta-titanium alloys) for better clinical results. Materials and Methods: A total of 15 specimens from each brand of orthodontic brackets and wires were examined. The brackets (Elite Opti-Mim which is produced by MIM process and Ultratrimm which is produced by conventional brazing method) and the wires (stainless steel, Ni-Ti, and beta-titanium) were embedded in epoxy resin, followed by grinding, polishing, and coating. Then, X-ray energy dispersive spectroscopy (EDS) microanalysis was applied to assess their elemental composition. The same specimen surfaces were repolished and used for Vickers microhardness assessment. Hardness was statistically analyzed with Kruskal–Wallis test, followed by Mann–Whitney test at the 0.05 level of significance. Results: The X-ray EDS analysis revealed different ferrous or co-based alloys in each bracket. The maximum mean hardness values of the wires were achieved for stainless steel (SS) (529.85 Vickers hardness [VHN]) versus the minimum values for beta-titanium (334.65 VHN). Among the brackets, Elite Opti-Mim exhibited significantly higher VHN values (262.66 VHN) compared to Ultratrimm (206.59 VHN). VHN values of wire alloys were significantly higher than those of the brackets. Conclusion: MIM orthodontic brackets exhibited hardness values much lower than those of SS orthodontic archwires and were more compatible with NiTi and beta-titanium archwires. A wide range of microhardness values has been reported for conventional orthodontic brackets and it should be considered that the manufacturing method might be only one of the factors affecting the mechanical properties of orthodontic brackets including hardness. PMID:28928783

Effect of heat treatment on mechanical properties of age-hardenable gold alloy at intraoral temperature.

PubMed

Watanabe, I; Watanabe, E; Cai, Z; Okabe, T; Atsuta, M

2001-09-01

The aim of this study was to investigate the effect of various heat treatments on the mechanical properties of gold alloys capable of age-hardening at intraoral temperature. Dumbbell-shaped patterns (ISO 6871) were cast with three gold alloys (Sofard; NC Type-IV; Aurum Cast, NihombashiTokuriki Co.). The Sofard alloy is age-hardenable at intraoral temperature. The castings underwent various heat treatments [as-cast (AC); solution treatment (ST); high-temperature aging (HA); intraoral aging (IA)]. After these heat treatments, ultimate tensile strength (UTS), 0.2% offset yield strength (YS), and elongation (EL) were measured at a strain rate of 1.7x10(-4)/s. Fracture surfaces of the specimens after tensile testing were observed using SEM. Vickers hardness was also measured after heat treating. After IA, the hardness values of the Sofard alloy increased and reached values similar to the hardness of the Sofard specimens aged at high temperature (HA). The hardness values of the NC Type-IV and Aurum Cast specimens slightly increased after IA, but did not reach the values of the specimens after HA. All the Sofard, NC Type-IV and Aurum Cast specimens showed significantly (P<0.05) greater hardness values after HA, compared with the values after any other heat treatments (AC, ST and IA). The UTS and YS of the specimens indicated a tendency similar to the results obtained for hardness. The Sofard specimens with ST showed the greatest elongation compared to the corresponding NC Type-IV and Aurum Cast specimens. However, the elongation of the Sofard specimens was abruptly reduced after intraoral aging. Intraoral aging significantly improved the mechanical properties and hardness of the Sofard alloy.

Assessment of the hardness of different orthodontic wires and brackets produced by metal injection molding and conventional methods.

PubMed

Alavi, Shiva; Kachuie, Marzie

2017-01-01

This study was conducted to assess the hardness of orthodontic brackets produced by metal injection molding (MIM) and conventional methods and different orthodontic wires (stainless steel, nickel-titanium [Ni-Ti], and beta-titanium alloys) for better clinical results. A total of 15 specimens from each brand of orthodontic brackets and wires were examined. The brackets (Elite Opti-Mim which is produced by MIM process and Ultratrimm which is produced by conventional brazing method) and the wires (stainless steel, Ni-Ti, and beta-titanium) were embedded in epoxy resin, followed by grinding, polishing, and coating. Then, X-ray energy dispersive spectroscopy (EDS) microanalysis was applied to assess their elemental composition. The same specimen surfaces were repolished and used for Vickers microhardness assessment. Hardness was statistically analyzed with Kruskal-Wallis test, followed by Mann-Whitney test at the 0.05 level of significance. The X-ray EDS analysis revealed different ferrous or co-based alloys in each bracket. The maximum mean hardness values of the wires were achieved for stainless steel (SS) (529.85 Vickers hardness [VHN]) versus the minimum values for beta-titanium (334.65 VHN). Among the brackets, Elite Opti-Mim exhibited significantly higher VHN values (262.66 VHN) compared to Ultratrimm (206.59 VHN). VHN values of wire alloys were significantly higher than those of the brackets. MIM orthodontic brackets exhibited hardness values much lower than those of SS orthodontic archwires and were more compatible with NiTi and beta-titanium archwires. A wide range of microhardness values has been reported for conventional orthodontic brackets and it should be considered that the manufacturing method might be only one of the factors affecting the mechanical properties of orthodontic brackets including hardness.

[An in vitro investigation of wear resistance and hardness of three kinds of new composite resins].

PubMed

Wang, Li-kai; Shi, Lian-shui; Zhu, Hong-shui

2008-02-01

To evaluate wear resistance and hardness of three kinds of new composite resins. Three kinds of new composite resins, Solidex, Spectrum, Filtek Z350, were tested. Enamel as control group. A refited MG-200 wear machine was used in this study. Scanning electron microscope (SEM) was used to observe the friction surface of each tested material. Hardness of each tested material was determined by Vickers indentation technique. The data of wear and hardness were analyzed by Mann-Whitney test and 1-way ANOVA. The relationship between the hardness of the composites and the amount of wear of them was determined by a regression analysis method. Filtek Z350 showed the lowest volumetric wear and highest Vickers hardness in the composites (P < 0.05). No significant differences in wear and hardness were observed between Solidex and Spectrum (P > 0.05). Significant relationships were observed between the hardness of the composites and the amount of wear of them (r = 0.968 6) (P < 0.05). Different wear characters of the friction surface of the tested materials were observed by SEM. Nanofilled composite was superior to the hybrid composite in wear resistance and hardness.

Indications of negative evolution for the sources of the highest energy cosmic rays

DOE Office of Scientific and Technical Information (OSTI.GOV)

Taylor, Andrew M.; Ahlers, Markus; Hooper, Dan

2015-09-14

Using recent measurements of the spectrum and chemical composition of the highest energy cosmic rays, we consider the sources of these particles. We find that these data strongly prefer models in which the sources of the ultra-high-energy cosmic rays inject predominantly intermediate mass nuclei, with comparatively few protons or heavy nuclei, such as iron or silicon. If the number density of sources per comoving volume does not evolve with redshift, the injected spectrum must be very hard (α≃1) in order to fit the spectrum observed from Earth. Such a hard spectral index would be surprising and difficult to accommodate theoretically.more » In contrast, much softer spectral indices, consistent with the predictions of Fermi acceleration (α≃2), are favored in models with negative source evolution. Furthermore with this theoretical bias, these observations thus favor models in which the sources of the highest energy cosmic rays are preferentially located within the low-redshift universe.« less

Predicting the Performance of Chain Saw Machines Based on Shore Scleroscope Hardness

NASA Astrophysics Data System (ADS)

Tumac, Deniz

2014-03-01

Shore hardness has been used to estimate several physical and mechanical properties of rocks over the last few decades. However, the number of researches correlating Shore hardness with rock cutting performance is quite limited. Also, rather limited researches have been carried out on predicting the performance of chain saw machines. This study differs from the previous investigations in the way that Shore hardness values (SH1, SH2, and deformation coefficient) are used to determine the field performance of chain saw machines. The measured Shore hardness values are correlated with the physical and mechanical properties of natural stone samples, cutting parameters (normal force, cutting force, and specific energy) obtained from linear cutting tests in unrelieved cutting mode, and areal net cutting rate of chain saw machines. Two empirical models developed previously are improved for the prediction of the areal net cutting rate of chain saw machines. The first model is based on a revised chain saw penetration index, which uses SH1, machine weight, and useful arm cutting depth as predictors. The second model is based on the power consumed for only cutting the stone, arm thickness, and specific energy as a function of the deformation coefficient. While cutting force has a strong relationship with Shore hardness values, the normal force has a weak or moderate correlation. Uniaxial compressive strength, Cerchar abrasivity index, and density can also be predicted by Shore hardness values.

Influence of the bracket on bonding and physical behavior of orthodontic resin cements.

PubMed

Bolaños-Carmona, Victoria; Zein, Bilal; Menéndez-Núñez, Mario; Sánchez-Sánchez, Purificación; Ceballos-García, Laura; González-López, Santiago

2015-01-01

The aim of the study is to determine the influence of the type of bracket, on bond strength, microhardness and conversion degree (CD) of four resin orthodontic cements. Micro-tensile bond strength (µTBS) test between the bracket base and the cement was carried out on glass-hour-shaped specimens (n=20). Vickers Hardness Number (VHN) and micro-Raman spectra were recorded in situ under the bracket base. Weibull distribution, ANOVA and non-parametric test were applied for data analysis (p<0.05). The highest values of ή as well as the β Weibull parameter were obtained for metallic brackets with Transbond™ plastic brackets with the self-curing cement showing the worst performance. The CD was from 80% to 62.5%.

Effect of feed composition, moisture content and extrusion temperature on extrudate characteristics of yam-corn-rice based snack food.

PubMed

Seth, Dibyakanta; Badwaik, Laxmikant S; Ganapathy, Vijayalakshmi

2015-03-01

Blends of yam, rice and corn flour were processed in a twin-screw extruder. Effects of yam flour (10-40 %), feed moisture content (12-24 %) and extruder barrel temperature (100-140 °C) on the characteristics of the dried extrudates was investigated using a statistical technique response surface methodology (RSM). Radial expansion ratio differed significantly (p ≤ 0.05) with change in all the independent variables. Highest expansion (3.97) was found at lowest moisture content (12 %) and highest barrel temperature (140 °C). Increased yam flour level decreased the expansion ratio significantly. Water absorption index (WAI) increased significantly with increase of all variables. However, water solubility index (WSI) did not change with change in yam flour percent. Hardness of extrudates that varied from 3.86 to 6.94 N was positively correlated with yam flour level and feed moisture content, however it decreased significantly (p ≤ 0.001) with increase of barrel temperature. Yam percent of 15.75 with feed moisture and barrel temperature at 12.00 % and 140 °C respectively gave an optimized product of high desirability (> 0.90) with optimum responses of 3.29 expansion ratio, 5.64 g/g dry solid water absorption index, 30.39 % water solubility index and 3.86 N hardness. The predicted values registered non-significant (p < 0.10) differences from the experimental results. Further study would include the sensory properties enhancement of extruded snacks and little emphasis on the chemistry of interaction between different components.

Physical and chemical quality characteristics and antioxidant properties of strawberry cultivars (Fragaria × ananassa Duch.) in Greece: assessment of their sensory impact.

PubMed

Zeliou, Konstantina; Papasotiropoulos, Vassilis; Manoussopoulos, Yiannis; Lamari, Fotini N

2018-02-01

There are many factors determining the strawberry organoleptic profile and they are difficult to define. In this study, the sensory, physical, and chemical quality characteristics, the antioxidant properties as examined using ferric reducing antioxidant power (FRAP) and 1-diphenyl-2-picrylhydrazyl (DPPH) assays, the lactone concentration, and the FaFAD1 expression of ripe strawberries (cv. Camarosa, Florida Fortuna, and Sabrina) from Greece were evaluated and their interrelationships were investigated. 'Camarosa' had the highest antioxidant capacity and polyphenol content, although significant intra-cultivar variations of sugars, solid soluble content/titratable acidity (SSC/TA), red color intensity, sweetness, and hardness were recorded. In 'Sabrina' there was a constant lactone presence and FaFAD1 expression; it also had the lowest ascorbic acid content, the highest pH, SSC/TA index, firmness, and sweetness. 'Fortuna' showed the lowest sweetness and aroma indices, whereas 'Camarosa' had intermediate ones. Overall, firmness was correlated with hardness, while pH and SSC/TA index correlated with juiciness and sweetness. Both γ-decalactone and γ-dodecalactone concentrations were correlated with FaFAD1 expression and pH, but they did not solely determine the aroma sensory perception. In total, FRAP values were positively correlated with ascorbic acid and polyphenol content, and negatively with pH. Significant inter- and intra-cultivar variation was recorded, revealing the impact of the genotype and underlining the effect of microenvironmental and cultivation conditions on quality and sensory perception. © 2018 Society of Chemical Industry. © 2018 Society of Chemical Industry.

Evaluation of degree of conversion and hardness of dental composites photo-activated with different light guide tips.

PubMed

Galvão, Marília Regalado; Caldas, Sergei Godeiro Fernandes Rabelo; Bagnato, Vanderlei Salvador; de Souza Rastelli, Alessandra Nara; de Andrade, Marcelo Ferrarezi

2013-01-01

The aim of this study was to evaluate the degree of conversion and hardness of different composite resins, photo-activated for 40 s with two different light guide tips, fiber optic and polymer. Five specimens were made for each group evaluated. The percentage of unreacted carbon double bonds (% C═C) was determined from the ratio of absorbance intensities of aliphatic C═C (peak at 1637 cm(-1)) against internal standard before and after curing of the specimen: aromatic C-C (peak at 1610 cm(-1)). The Vickers hardness measurements were performed in a universal testing machine. A 50 gf load was used and the indenter with a dwell time of 30 seconds. The degree of conversion and hardness mean values were analyzed separately by ANOVA and Tukey's test, with a significance level set at 5%. The mean values of degree of conversion for the polymer and fiber optic light guide tip were statistically different (P<.001). The hardness mean values were statistically different among the light guide tips (P<.001), but also there was difference between top and bottom surfaces (P<.001). The results showed that the resins photo-activated with the fiber optic light guide tip promoted higher values for degree of conversion and hardness.

Evaluation of degree of conversion and hardness of dental composites photo-activated with different light guide tips

PubMed Central

Galvão, Marília Regalado; Caldas, Sergei Godeiro Fernandes Rabelo; Bagnato, Vanderlei Salvador; de Souza Rastelli, Alessandra Nara; de Andrade, Marcelo Ferrarezi

2013-01-01

Objective: The aim of this study was to evaluate the degree of conversion and hardness of different composite resins, photo-activated for 40 s with two different light guide tips, fiber optic and polymer. Methods: Five specimens were made for each group evaluated. The percentage of unreacted carbon double bonds (% C═C) was determined from the ratio of absorbance intensities of aliphatic C═C (peak at 1637 cm−1) against internal standard before and after curing of the specimen: aromatic C-C (peak at 1610 cm−1). The Vickers hardness measurements were performed in a universal testing machine. A 50 gf load was used and the indenter with a dwell time of 30 seconds. The degree of conversion and hardness mean values were analyzed separately by ANOVA and Tukey’s test, with a significance level set at 5%. Results: The mean values of degree of conversion for the polymer and fiber optic light guide tip were statistically different (P<.001). The hardness mean values were statistically different among the light guide tips (P<.001), but also there was difference between top and bottom surfaces (P<.001). Conclusions: The results showed that the resins photo-activated with the fiber optic light guide tip promoted higher values for degree of conversion and hardness. PMID:23407620

Enhancement of surface mechanical properties by using TiN[BCN/BN] n/c-BN multilayer system

NASA Astrophysics Data System (ADS)

Moreno, H.; Caicedo, J. C.; Amaya, C.; Muñoz-Saldaña, J.; Yate, L.; Esteve, J.; Prieto, P.

2010-11-01

The aim of this work is to improve the mechanical properties of AISI 4140 steel substrates by using a TiN[BCN/BN] n/c-BN multilayer system as a protective coating. TiN[BCN/BN] n/c-BN multilayered coatings via reactive r.f. magnetron sputtering technique were grown, systematically varying the length period ( Λ) and the number of bilayers ( n) because one bilayer ( n = 1) represents two different layers ( tBCN + tBN), thus the total thickness of the coating and all other growth parameters were maintained constant. The coatings were characterized by Fourier transform infrared spectroscopy showing bands associated with h-BN bonds and c-BN stretching vibrations centered at 1400 cm -1 and 1100 cm -1, respectively. Coating composition and multilayer modulation were studied via secondary ion mass spectroscopy. Atomic force microscopy analysis revealed a reduction in grain size and roughness when the bilayer number ( n) increased and the bilayer period decreased. Finally, enhancement of mechanical properties was determined via nanoindentation measurements. The best behavior was obtained when the bilayer period ( Λ) was 80 nm ( n = 25), yielding the relative highest hardness (˜30 GPa) and elastic modulus (230 GPa). The values for the hardness and elastic modulus are 1.5 and 1.7 times greater than the coating with n = 1, respectively. The enhancement effects in multilayered coatings could be attributed to different mechanisms for layer formation with nanometric thickness due to the Hall-Petch effect; because this effect, originally used to explain increased hardness with decreasing grain size in bulk polycrystalline metals, has also been used to explain hardness enhancements in multilayered coatings taking into account the thickness reduction at individual single layers that make up the multilayered system. The Hall-Petch model based on dislocation motion within layered and across layer interfaces has been successfully applied to multilayered coatings to explain this hardness enhancement.

Effect of exposure intensity and post-cure temperature storage on hardness of contemporary photo-activated composites.

PubMed

Quance, S C; Shortall, A C; Harrington, E; Lumley, P J

2001-11-01

The effect of variation in post-exposure storage temperature (18 vs. 37 degrees C) and light intensity (200 vs. 500mW/cm(2)) on micro-hardness of seven light-activated resin composite materials, cured with a Prismetics Mk II (Dentsply) light activation unit, were studied. Hardness values at the upper and lower surfaces of 2mm thick disc shaped specimens of seven light-cured resin composite materials (Herculite XRV and Prodigy/Kerr, Z100 and Silux Plus/3M, TPH/Dentsply, Pertac-Hybrid/Espe, and Charisma/Kulzer), which had been stored dry, were determined 24h after irradiation with a Prismetics Mk II (Dentsply) light activation unit. Hardness values varied with product, surface, storage temperature, and curing light intensity. In no case did the hardness at the lower surface equal that of the upper surface, and the combination of 500mW/cm(2) intensity and 37 degrees C storage produced the best hardness results at the lower surface. Material composition had a significant influence on surface hardness. Only one of the seven products (TPH) produced a mean hardness values at the lower surface >80% of the maximum mean upper surface hardness obtained for the corresponding product at 500mW/cm(2) intensity/37 degrees C storage temperature when subjected to all four test regimes. Despite optimum post-cure storage conditions, 200mW/cm(2) intensity curing for 40s will not produce acceptable hardness at the lower surface of 2mm increments of the majority of products tested.

Influence of mineral oil and additives on microhardness and surface chemistry of magnesium oxide (001) surface

NASA Technical Reports Server (NTRS)

Miyoshi, K.; Shigaki, H.; Buckley, D. H.

1982-01-01

X-ray photoelectron spectroscopy analyses and hardness experiments were conducted with cleaved magnesium oxide /001/ surfaces. The magnesium oxide bulk crystals were cleaved into specimens along the /001/ surface, and indentations were made on the cleaved surface in laboratory air, in nitrogen gas, or in degassed mineral oil with and without an additive while not exposing specimen surface to any other environment. The various additives examined contained sulfur, phosphorus, chlorine, or oleic acid. The sulfur-containing additive exhibited the highest hardness and smallest dislocation patterns evidencing plastic deformation; the chlorine-containing additive exhibited the lowest hardness and largest dislocation patterns evidencing plastic deformation. Hydrocarbon and chloride (MgCl2) films formed on the magnesium oxide surface. A chloride film was responsible for the lowest measured hardness.

Hydration entropy change from the hard sphere model.

PubMed

Graziano, Giuseppe; Lee, Byungkook

2002-12-10

The gas to liquid transfer entropy change for a pure non-polar liquid can be calculated quite accurately using a hard sphere model that obeys the Carnahan-Starling equation of state. The same procedure fails to produce a reasonable value for hydrogen bonding liquids such as water, methanol and ethanol. However, the size of the molecules increases when the hydrogen bonds are turned off to produce the hard sphere system and the volume packing density rises. We show here that the hard sphere system that has this increased packing density reproduces the experimental transfer entropy values rather well. The gas to water transfer entropy values for small non-polar hydrocarbons is also not reproduced by a hard sphere model, whether one uses the normal (2.8 A diameter) or the increased (3.2 A) size for water. At least part of the reason that the hard sphere model with 2.8 A size water produces too small entropy change is that the size of water is too small for a system without hydrogen bonds. The reason that the 3.2 A model also produces too small entropy values is that this is an overly crowded system and that the free volume introduced in the system by the addition of a solute molecule produces too much of a relief to this crowding. A hard sphere model, in which the free volume increase is limited by requiring that the average surface-to-surface distance between the solute and water molecules is the same as that between the increased-size water molecules, does approximately reproduce the experimental hydration entropy values. Copyright 2002 Elsevier Science B.V.

Evaluation of the flexural strength and microhardness of provisional crown and bridge materials fabricated by different methods

PubMed Central

Digholkar, Shruti; Madhav, V. N. V.; Palaskar, Jayant

2016-01-01

Purpose: The purpose of this study was to evaluate and compare the flexural strength and microhardness of provisional restorative materials fabricated utilizing rapid prototyping (RP), Computer Assisted Designing and Computer Assisted Milling (CAD-CAM) and conventional method. Materials and Methods: Twenty specimens of dimensions 25 mm × 2 mm × 2 mm (ADA-ANSI specification #27) were fabricated each using: (1) Three dimensional (3D) printed light-cured micro-hybrid filled composite by RP resin group, (2) a milled polymethyl methacrylate (CH) using CAD-CAM (CC resin group), and (3) a conventionally fabricated heat activated polymerized CH resin group. Flexural strength and microhardness were measured and values obtained were evaluated. Results: The measured mean flexural strength values (MegaPascals) were 79.54 (RP resin group), 104.20 (CC resin group), and 95.58 (CH resin group). The measured mean microhardness values (Knoop hardness number) were 32.77 (RP resin group), 25.33 (CC resin group), and 27.36 (CH resin group). The analysis of variance (ANOVA) test shows that there is statistically significant difference in the flexural strength values of the three groups (P < 0.05). According to the pairwise comparison of Tukey's honest significant difference (HSD) test, flexural strength values of CC resin group and CH resin group were higher and statistically significant than those of the RP resin group (P < 0.05). However, there was no significant difference between flexural strength values of CC resin and CH resin group (P = 0.64). The difference in microhardness values of the three groups was statistically significant according to ANOVA as well as the intergroup comparison done using the Tukey's HSD (post hoc) test (P < 0.05). Conclusions: CC-based CH had the highest flexural strength whereas RP-based 3D printed and light cured micro-hybrid filled composite had the highest microhardness. PMID:27746595

Assessment of surface hardness of acrylic resins submitted to accelerated artificial aging.

PubMed

Tornavoi, D C; Agnelli, J A M; Lepri, C P; Mazzetto, M O; Botelho, A L; Soares, R G; Dos Reis, A C

2012-06-01

The aim of this study was to assess the influence of accelerated artificial aging (AAA) on the surface hardness of acrylic resins. The following three commercial brands of acrylic resins were tested: Vipi Flash (autopolymerized resin), Vipi Wave (microwave heat-polymerized resin) and Vipi Cril (conventional heat-polymerized resin). To perform the tests, 21 test specimens (65x10x3 mm) were made, 7 for each resin. Three surface hardness readings were performed for each test specimen, before and after AAA, and the means were submitted to the following tests: Kolmogorov-Smirnov (P>0.05), Levene Statistic, Two-way ANOVA, Tukey Post Hoc (P<0.05) with the SPSS Statistical Software 17.0. The analysis of the factors showed significant differences in the hardness values (P<0.05). Before aging, the autopolymerized acrylic resin Vipi Flash showed lower hardness values when compared with the heat-polymerized resin Vipi Cril (P=0.001). After aging, the 3 materials showed similar performance when compared among them. The Vipi Cril was the only one affected by AAA and showed lower hardness values after this procedure (Pp=0.003). It may be concluded that accelerated artificial aging influenced surface hardness of heat-polymerized acrylic resin Vipi Cril.

A Novel Approach to Determine the Prevalence of Type of Soft Palate Using Digital Intraoral Impression.

PubMed

Chaturvedi, Saurabh; Khaled Addas, Mohamed; Al Humaidi, Abdullah Saad Ali; Al Qahtani, Abdulrazaq Mohammed; Al Qahtani, Mubarak Daghash

2017-01-01

To determine the prevalence of type of soft palate in targeted population. Using computer technology in dentistry, intraoral digital scanner, and 3D analysis software tool, study was conducted. 100 patients selected from the outpatient clinics were divided into two groups based on the ages of 20-40 years and 41-60 years with equal ratio of males and females. Each selected patient's maxillary arch was scanned with intraoral scanner; images so obtained were sectioned in anteroposterior cross section and with the 3D analysis software; the angulation between hard and soft palate was determined. The prevalence of type II soft palate (angulation between hard and soft palate is between 10 and 45 degrees) was highest, 60% in group 1 and 44% in group 2. The difference between genders was statistically significant with p value <0.05 in both the groups, although females had higher angulation compared to the males in all classes of both groups. In targeted population of Aseer Province, Saudi Arabia, the prevalence of type II soft palate was more common, with higher soft palate angulation among females. The advanced age had no effect in the type of soft palate in the region.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Esgin, U.; Özyürek, D.; Kaya, H., E-mail: hasan.kaya@kocaeli.edu.tr

In the present study, wear behaviors of Monel 400, Monel 404, Monel R-405 and Monel K-500 alloys produced by Powder Metallurgy (P/M) method were investigated. These compounds prepared from elemental powders were cold-pressed (600 MPa) and then, sintered at 1150°C for 2 hours and cooled down to the room temperature in furnace environment. Monel alloys produced by the P/M method were characterized through scanning electron microscope (SEM+EDS), X-ray diffraction (XRD), hardness and density measurements. In wear tests, standard pin-on-disk type device was used. Specimens produced within four different Monel Alloys were tested under 1ms{sup −1} sliding speed, under three different loadsmore » (20N, 30N and 40N) and five different sliding distances (400-2000 m). The results show that Monel Alloys have γ matrix and that Al{sub 0,9}Ni{sub 4,22} intermetallic phase was formed in the structure. Also, the highest hardness value was measured with the Monel K-500 alloy. In wear tests, the maximum weight loss according to the sliding distance, was observed in Monel 400 and Monel 404 alloys while the minimum weight loss was achieved by the Monel K-500 alloy.« less

Field observations of the electrostatic charges of blowing snow in Hokkaido, Japan

NASA Astrophysics Data System (ADS)

Omiya, S.; Sato, A.

2011-12-01

An electrostatic charge of blowing snow may be a contributing factor in the formation of a snow drift and a snow cornice, and changing of the trajectory of own motion. However, detailed electrification characteristics of blowing snow are not known as there are few reports of charge measurements. We carried out field observations of the electrostatic charges of blowing snow in Tobetsu, Hokkaido, Japan in the mid winter of 2011. An anemovane and a thermohygrometer were used for the meteorological observation. Charge-to-mass ratios of blowing snow were obtained by a Faraday-cage, an electrometer and an electric balance. In this observation period, the air temperature during the blowing snow event was -6.5 to -0.5 degree Celsius. The measured charges in this observation were consistent with the previous studies in sign, which is negative, but they were smaller than the previous one. In most cases, the measured values increased with the temperature decrease, which corresponds with previous studies. However, some results contradicted the tendency, and the maximum value was obtained on the day of the highest air temperature of -0.5 degree Celsius. This discrepancy may be explained from the difference of the snow surface condition on observation day. The day when the maximum value was obtained, the snow surface was covered with old snow, and hard. On the other hand, in many other cases, the snow surface was covered with the fresh snow, and soft. Blowing snow particles on the hard surface can travel longer distance than on the soft one. Therefore, it can be surmised that the hard surface makes the blowing snow particles accumulate a lot of negative charges due to a large number of collisions to the surface. This can be supported by the results of the wind tunnel experiments by Omiya and Sato (2011). By this field observation, it was newly suggested that the electrostatic charge of blowing snow are influenced greatly by the difference of the snow surface condition. REFERENCE: Omiya and Sato,(2010):An electrostatic charge measurement of blowing snow particles focusing on collision frequency to the snow surface. AGU Abstract Database, 2010 Fall Meeting.

Particles and Zinc on the Absorbed Impact Energy of Gravity Cast Aluminum Matrix Composites

NASA Astrophysics Data System (ADS)

Corchado, Marcos; Reyes, Fernando; Suárez, Oscar Marcelo

2014-06-01

The effect of different amounts of boron, in the form of AlB2 particles, as well as zinc concentration in a gravity cast Al-B-Zn composite, was studied and related to the absorbed energy upon fracture during Charpy impact experiments. In addition, the authors correlated the composite Brinell hardness with the quantitative assessment of brittle and ductile fracture areas of the Charpy fractured specimens and found that increasing AlB2 particle concentration resulted in a reduction of absorbed impact energy. Although larger zinc levels produced somewhat similar results, the AlB2 effect was prevalent. The energy absorption upon impact reached a maximum when no particles were present; conversely, the lowest amount of absorbed energy corresponded to a composite with a composition of 15 wt.% Zn and 8% in volume of AlB2, i.e., the highest concentration of AlB2 and zinc studied. Raising the amount of AlB2 as well as zinc, as expected, resulted in higher Brinell hardness. A statistical analysis allowed studying of the particle size distribution, whereas values for crack tip opening displacement were subsequently calculated for the range of particle sizes found and the corresponding AlB2 particle volume percent. Higher porosity values were measured for larger AlB2 volume percent. Finally, analyses of fracture surfaces corroborated that brittle fracture was favored in composites with higher amounts of AlB2 and zinc.

First-Principles Calculations on the Origin of Mechanical Properties and Electronic Structures of 5d Transition Metal Monocarbides MC (M = Hf, Ta, W, Re, Os, Ir, and Pt)

NASA Astrophysics Data System (ADS)

Fukuichi, Masayuki; Momida, Hiroyoshi; Geshi, Masaaki; Michiuchi, Masato; Sogabe, Koichi; Oguchi, Tamio

2018-04-01

Much is not systematically known about the origin of mechanical properties among 5d transition metal carbides including tungsten carbide. In order to understand the microscopic origin of hardness, the mechanical properties and electronic structures of 5d transition metal monocarbides MC (M = Hf, Ta, W, Re, Os, Ir, and Pt) in five different structures (NaCl, WC, ZnS, CsCl, and NiAs type) are analyzed using first-principles calculations based on the density functional theory. Our results would indicate that WC-type WC and NiAs-type ReC have the highest and second highest hardness among all of the MC, respectively, in terms of the Debye temperature. By examining the Debye temperature in the series, it is found that MC in the range of less and more than half filled 5d shells are brittle and ductile, respectively. Our results would indicate that filling in the bonding and anti-bonding states contributes to brittleness and ductility. The Debye temperature could be a key to understanding hardness in terms of bulk and shear moduli. In addition, we evaluate some other structural properties such as equilibrium volume, formation enthalpy, and elastic constant to investigate structural stability. Based on the theoretical findings, the microscopic mechanisms of hardness and brittleness in the transition metal carbides are discussed.

A comparative study of hospital admissions for respiratory diseases during normal and dusty days in Iran.

PubMed

Geravandi, Sahar; Sicard, Pierre; Khaniabadi, Yusef Omidi; De Marco, Alessandra; Ghomeishi, Ali; Goudarzi, Gholamreza; Mahboubi, Mohammad; Yari, Ahmad Reza; Dobaradaran, Sina; Hassani, Ghasem; Mohammadi, Mohammad Javad; Sadeghi, Shahram

2017-08-01

During the last century, most of people around the world moved from communicable to non-communicable diseases, mainly due to air pollution. Air pollutants and dust storm increase risk of morbidity, for cardiovascular and respiratory diseases, and increase the number of deaths. The city of Ahvaz is considered as the focal point of air pollution and dust storm in Iran. The aim of this study was to determine the number of Hospital Admission Respiratory Disease (HARD) including asthma attacks, acute bronchitis and chronic obstructive pulmonary disease attributed to PM 10 by a descriptive study during normal and dust event days in Ahvaz during the time period 2010-2012. The hourly PM 10 data was collected from the Iranian Environmental Protection Agency and Razi hospital. The annual PM 10 mean concentrations reached 282, 288 and 278 μg/m 3 in 2010, 2011 and 2012, respectively. The number of HARD attributed to PM 10 was 1438, 1945 and 1393 people, respectively, and the highest number of daily admissions was attributed to the highest daily PM 10 concentration in Ahvaz. The average number of daily HARD during dusty days was higher than normal days, and a significant positive correlation, between the number of hospital admissions and dusty days, was found. Dust had significant impact on HARD in Ahvaz.

Relationship Between Crystalline Structure and Hardness of Ti-Si-N-O Coatings Fabricated by dc Sputtering

NASA Astrophysics Data System (ADS)

García-González, Leandro; Hernández-Torres, Julián; Mendoza-Barrera, Claudia; Meléndez-Lira, Miguel; García-Ramírez, Pedro J.; Martínez-Castillo, Jaime; Sauceda, Ángel; Herrera-May, Agustin L.; Muñoz Saldaña, Juan; Espinoza-Beltrán, Francisco J.

2008-08-01

Ti-Si-N-O coatings were deposited on AISI D2 tool steel and silicon substrates by dc reactive magnetron co-sputtering using a target of Ti-Si with a constant area ratio of 0.2. The substrate temperature was 400 °C and reactive atmosphere of nitrogen and argon. For all samples, argon flow was maintained constant at 25 sccm, while the flow of the nitrogen was varied to analyze the structural changes related to chemical composition and resistivity. According to results obtained by x-ray diffraction and stoichiometry calculations by x-ray energy dispersive spectroscopy the Ti-Si-N-O coatings contain two solid solutions. The higher crystalline part corresponds to titanium oxynitrure. Hardness tests on the coatings were carried out using the indentation work model and the hardness value was determined. Finally, the values of hardness were corroborated by nanoindentation test, and values of Young’s modulus and elastic recovery were discussed. We concluded that F2TSN sample ( F Ar = 25 sccm, F N = 5 sccm, P = 200 W, and P W = 8.9 × 10-3 mbar) presented the greatest hardness and the lowest resistivity values, due to its preferential crystalline orientation.

Evaluation of polymethyl methacrylate resin mechanical properties with incorporated halloysite nanotubes

PubMed Central

2016-01-01

PURPOSE This study inspects the effect of incorporating halloysite nanotubes (HNTs) into polymethyl methacrylate (PMMA) resin on its flexural strength, hardness, and Young's modulus. MATERIALS AND METHODS Four groups of acrylic resin powder were prepared. One group without HNTs was used as a control group and the other three groups contained 0.3, 0.6 and 0.9 wt% HNTs. For each one, flexural strength, Young's modulus and hardness values were measured. One-way ANOVA and Tukey's test were used for comparison (P<.05). RESULTS At lower concentration (0.3 wt%) of HNT, there was a significant increase of hardness values but no significant increase in both flexural strength and Young's modulus values of PMMA resin. In contrast, at higher concentration (0.6 and 0.9 wt%), there was a significant decrease in hardness values but no significant decrease in flexural strength and Young's modulus values compared to those of the control group. CONCLUSION Addition of lower concentration of halloysite nanotubes to denture base materials could improve some of their mechanical properties. Improving the mechanical properties of acrylic resin base material could increase the patient satisfaction. PMID:27350849

Application of Artificial Neural Network to Predict Colour Change, Shrinkage and Texture of Osmotically Dehydrated Pumpkin

NASA Astrophysics Data System (ADS)

Tang, S. Y.; Lee, J. S.; Loh, S. P.; Tham, H. J.

2017-06-01

The objectives of this study were to use Artificial Neural Network (ANN) to predict colour change, shrinkage and texture of osmotically dehydrated pumpkin slices. The effects of process variables such as concentration of osmotic solution, immersion temperature and immersion time on the above mentioned physical properties were studied. The colour of the samples was measured using a colorimeter and the net colour difference changes, ΔE were determined. The texture was measured in terms of hardness by using a Texture Analyzer. As for the shrinkage, displacement of volume method was applied and percentage of shrinkage was obtained in terms of volume changes. A feed-forward backpropagation network with sigmoidal function was developed and best network configuration was chosen based on the highest correlation coefficients between the experimental values versus predicted values. As a comparison, Response Surface Methodology (RSM) statistical analysis was also employed. The performances of both RSM and ANN modelling were evaluated based on absolute average deviation (AAD), correlation of determination (R2) and root mean square error (RMSE). The results showed that ANN has higher prediction capability as compared to RSM. The relative importance of the variables on the physical properties were also determined by using connection weight approach in ANN. It was found that solution concentration showed the highest influence on all three physical properties.

Utilization of African grains for sourdough bread making.

PubMed

Coda, Rossana; Di Cagno, Raffaella; Rizzello, Carlo G; Nionelli, Luana; Edema, Mojisola O; Gobbetti, Marco

2011-08-01

Acha and Iburu flours were singly subjected to sourdough fermentation with previously selected autochthonous starters. Sourdoughs were used (30%, wt/wt) as aroma carriers and acidifiers during short time fermentation with the addition of baker's yeast. Acha and Iburu sourdough breads were compared to wheat sourdough bread started with the same strains and to breads made with the same formula but using baker's yeast alone. During Acha and Iburu sourdough fermentations, starter lactic acid bacteria reached almost the same cell density found in wheat sourdoughs. Acidification was more intense. Iburu sourdough bread had the highest total titratable acidity, the lowest pH, and contained the highest levels of free amino acids and phytase activity. The values of in vitro protein digestibility did not differ between Acha sourdough and wheat sourdough breads, while Iburu sourdough bread showed a slightly lower value. Acha and Iburu sourdough breads showed lower specific volume and higher density with respect to wheat sourdough breads. Nevertheless, Acha and Iburu sourdough breads were preferred for hardness and resilience. As shown by sensory analysis, Acha and especially Iburu sourdough breads were appreciated for color, acid taste and flavor, and overall acceptability. This study was aimed at evaluating the technological and nutritional properties of the African cereals Acha and Iburu. Sourdough fermentation and the use of selected starters increased the nutritional and sensory qualities and the potential application for bakery industry. © 2011 Institute of Food Technologists®

Tactile sensor is useful for estimating liver hardness and liver fibrosis compared with ultrasonography and computed tomography.

PubMed

Suzuki, Satoshi; Watanabe, Yohei; Yazawa, Takashi; Ishigame, Teruhide; Sassa, Motoki; Monma, Tomoyuki; Takawa, Tadashi; Kumamoto, Kensuke; Nakamura, Izumi; Ohoki, Shinji; Hatakeyama, Yuichi; Sakuma, Hiroshi; Ono, Toshiyuki; Omata, Sadao; Takenoshita, Seiichi

2014-01-01

We examined whether conventional ultrasonography (US) and computed tomography (CT) were useful to evaluate liver hardness and hepatic fibrosis by comparing the results with those obtained by a tactile sensor using rats with liver fibrosis. We used 44 Wistar rats in which liver fibrosis was induced by intraperitoneal administration of thioacetamide. The CT and US values of each liver were measured before laparotomy. After laparotomy, a tactile sensor was used to measure liver hardness. We prepared Azan stained sections of each excised liver specimen and calculated the degree of liver fibrosis (HFI: hepatic fibrosis index) by computed color image analysis. The stiffness values and HFI showed a positive correlation (r=0.690, p<0.001), as did the tactile values and HFI (r=0.709, p<0.001).In addition, the stiffness and tactile values correlated positively with each other (r=0.814, p<0.001). There was no correlation between the CT values and HFI, as well as no correlation between the US values and HFI. We confirmed that it was difficult to evaluate liver hardness and HFI by CT or US examination, and considered that, at present, a tactile sensor is useful method for evaluating HFI.

A comparative evaluation of effect of modern-curing lights and curing modes on conventional and novel-resin monomers

PubMed Central

Roy, Konda Karthik; Kumar, Kanumuru Pavan; John, Gijo; Sooraparaju, Sujatha Gopal; Nujella, Surya Kumari; Sowmya, Kyatham

2018-01-01

Aim: The aim of this study is to compare and to evaluate effect of curing light and curing modes on the nanohybrid composite resins with conventional Bis-GMA and novel tricyclodecane (TCD) monomers. Methodology: Two nanohybrid composites, IPS empress direct and charisma diamond were used in this study. Light-emitting diode (LED)-curing unit and quartz-tungsten-halogen (QTH)-curing unit which were operated into two different modes: continuous and soft start. Based on the composite resin, curing lights, and mode of curing used, the samples were divided into 8 groups. After polymerization, the samples were stored for 48 h in complete darkness at 37°C and 100% humidity. The Vickers hardness (VK) of the surface was determined with Vickers indenter by the application of 200 g for 15 s. Three VK readings were recorded for each sample surface both on top and bottom surfaces. For all the specimens, the three hardness values for each surface were averaged and reported as a single value. The mean VK and hardness ratio were calculated. The depth of cure was assessed based on the hardness ratio. Results: Comparison of mean hardness values and hardness ratios was done using ANOVA with post hoc Tukey's test. Conclusion: Both QTH- and LED-curing units had shown the adequate depth of cure. Soft-start-curing mode in both QTH- and LED-curing lights had effectively increased microhardness than the continuous mode of curing. TCD monomer had shown higher hardness values compared with conventional Bis-GMA-containing resin. PMID:29628651

Structure and Mechanical Properties of Al-Cu-Fe-X Alloys with Excellent Thermal Stability.

PubMed

Školáková, Andrea; Novák, Pavel; Mejzlíková, Lucie; Průša, Filip; Salvetr, Pavel; Vojtěch, Dalibor

2017-11-05

In this work, the structure and mechanical properties of innovative Al-Cu-Fe based alloys were studied. We focused on preparation and characterization of rapidly solidified and hot extruded Al-Cu-Fe, Al-Cu-Fe-Ni and Al-Cu-Fe-Cr alloys. The content of transition metals affects mechanical properties and structure. For this reason, microstructure, phase composition, hardness and thermal stability have been investigated in this study. The results showed exceptional thermal stability of these alloys and very good values of mechanical properties. Alloying by chromium ensured the highest thermal stability, while nickel addition refined the structure of the consolidated alloy. High thermal stability of all tested alloys was described in context with the transformation of the quasicrystalline phases to other types of intermetallics.

Structure and Mechanical Properties of Al-Cu-Fe-X Alloys with Excellent Thermal Stability

PubMed Central

Školáková, Andrea; Novák, Pavel; Mejzlíková, Lucie; Průša, Filip; Salvetr, Pavel; Vojtěch, Dalibor

2017-01-01

In this work, the structure and mechanical properties of innovative Al-Cu-Fe based alloys were studied. We focused on preparation and characterization of rapidly solidified and hot extruded Al-Cu-Fe, Al-Cu-Fe-Ni and Al-Cu-Fe-Cr alloys. The content of transition metals affects mechanical properties and structure. For this reason, microstructure, phase composition, hardness and thermal stability have been investigated in this study. The results showed exceptional thermal stability of these alloys and very good values of mechanical properties. Alloying by chromium ensured the highest thermal stability, while nickel addition refined the structure of the consolidated alloy. High thermal stability of all tested alloys was described in context with the transformation of the quasicrystalline phases to other types of intermetallics. PMID:29113096

The hard X-ray spectrum of NGC 5506 as seen by NuSTAR

DOE Office of Scientific and Technical Information (OSTI.GOV)

Matt, G.; Balokovi , M.; Marinucci, A.

2015-01-14

NuSTAR observed the bright Compton-thin, narrow-line Seyfert 1 galaxy, NGC 5506, for about 56 ks. In agreement with past observations, the spectrum is well fitted by a power law with Γ ~ 1.9, a distant reflection component and narrow ionized iron lines. A relativistically blurred reflection component is not required by the data. When an exponential high-energy cutoff is added to the power law, a value of 720more » $$+130\\atop{-190}$$ keV (90 percent confidence level) is found. Even allowing for systematic uncertainties, we find a 3σ lower limit to the high-energy cutoff of 350 keV, the highest lower limit to the cutoff energy found so far in an AGN by NuSTAR.« less

Hardening characteristics of CO2 laser welds in advanced high strength steel

NASA Astrophysics Data System (ADS)

Han, Tae-Kyo; Park, Bong-Gyu; Kang, Chung-Yun

2012-06-01

When the CO2 laser welder with 6 kW output was used to weld 4 TRIP steels, 2 DP steels and a precipitation-hardened steel, which have the tensile strength in the range of 600-1000 MPa, the effect of welding speed on hardening characteristics was investigated. In the weld of TRIP steels and DP steels, the maximum hardness was shown in the fusion zone and the HAZ near the bond line, and the hardness was decreased from the HAZ to the base metal. Only in the PH600 steel, the maximum hardness was shown in the fusion zone and the hardness was decreased from bond line to the base metal. The maximum hardness value was not changed due to the variation of the welding speed within a given range of the welding speed. When the correlation with maximum hardness value using 6 known carbon equivalents was examined, those of CEL (=C+Si/50+Mn/25+P/2+Cr/25) and PL (=C+Mn/22+14B) were 0.96 and 0.95 respectively, and CEL was better because it could reflect the contribution of Si and Cr added to AHSS. The maximum hardness value could be calculated by the equation "Hmax=701CEL+281". The phase transformation analysis indicated that only martensitic transformation was expected in the given range of the welding conditions. Therefore, the maximum hardness of the weld was the same as that of water cooled steel and not changed with the variation of the welding speed

Heat Transfer and Thermal Stress Analysis of a Mandibular Molar Tooth Restored by Different Indirect Restorations Using a Three-Dimensional Finite Element Method.

PubMed

Çelik Köycü, Berrak; İmirzalıoğlu, Pervin

2017-07-01

Daily consumption of food and drink creates rapid temperature changes in the oral cavity. Heat transfer and thermal stress caused by temperature changes in restored teeth may damage the hard and soft tissue components, resulting in restoration failure. This study evaluates the temperature distribution and related thermal stress on mandibular molar teeth restored via three indirect restorations using three-dimensional (3D) finite element analysis (FEA). A 3D finite element model was constructed of a mandibular first molar and included enamel, dentin, pulp, surrounding bone, and indirect class 2 restorations of type 2 dental gold alloy, ceramic, and composite resin. A transient thermal FEA was performed to investigate the temperature distribution and the resulting thermal stress after simulated temperature changes from 36°C to 4 or 60°C for a 2-second time period. The restoration models had similar temperature distributions at 2 seconds in both the thermal conditions. Compared with 60°C exposure, the 4°C condition resulted in thermal stress values of higher magnitudes. At 4ºC, the highest stress value observed was tensile stress (56 to 57 MPa), whereas at 60°C, the highest stress value observed was compressive stress (42 to 43 MPa). These stresses appeared at the cervical region of the lingual enamel. The thermal stress at the restoration surface and resin cement showed decreasing order of magnitude as follows: composite > gold > ceramic, in both thermal conditions. The properties of the restorative materials do not affect temperature distribution at 2 seconds in restored teeth. The pulpal temperature is below the threshold for vital pulp tissue (42ºC). Temperature changes generate maximum thermal stress at the cervical region of the enamel. With the highest thermal expansion coefficient, composite resin restorations exhibit higher stress patterns than ceramic and gold restorations. © 2015 by the American College of Prosthodontists.

Estimating Janka hardness from specific gravity for tropical and temperate species

Treesearch

Michael C. Wiemann; David W. Green

2007-01-01

Using mean values for basic (green) specific gravity and Janka side hardness for individual species obtained from the world literature, regression equations were developed to predict side hardness from specific gravity. Statistical and graphical methods showed that the hardness–specific gravity relationship is the same for tropical and temperate hardwoods, but that the...

Sub-second variations of high energy ( 300 keV) hard X-ray emission from solar flares

NASA Technical Reports Server (NTRS)

Bai, Taeil

1986-01-01

Subsecond variations of hard X-ray emission from solar flares were first observed with a balloon-borne detector. With the launch of the Solar Maximum Mission (SMM), it is now well known that subsecond variations of hard X-ray emission occur quite frequently. Such rapid variations give constraints on the modeling of electron energization. Such rapid variations reported until now, however, were observed at relatively low energies. Fast mode data obtained by the Hard X-ray Burst Spectrometer (HXRBS) has time resolution of approximately 1 ms but has no energy resolution. Therefore, rapid fluctuations observed in the fast-mode HXRBS data are dominated by the low energy hard X-rays. It is of interest to know whether rapid fluctuations are observed in high-energy X-rays. The highest energy band at which subsecond variations were observed is 223 to 1057 keV. Subsecond variations observed with HXRBS at energies greater than 300 keV are reported, and the implications discussed.

Influence on grip of knife handle surface characteristics and wearing protective gloves.

PubMed

Claudon, Laurent

2006-11-01

Ten subjects were asked to apply maximum torques on knife handles with either their bare hand or their hand wearing a Kevlar fibre protective glove. Four knife handles (2 roughnesses, 2 hardnesses) were tested. Surface electromyograms of 6 upper limb and shoulder muscles were recorded and subject opinions on both knife handle hardness and friction in the hand were also assessed. The results revealed the significant influence of wearing gloves (p<0.0001), knife type (p<0.0005) and handle hardness (p<0.005) on the applied torque. Wearing Kevlar fibre gloves greatly increased the torque independently of the other two parameters. Under the bare hand condition, a 90 degrees ShA slightly rough handle provided the greatest torque. Subject opinion agreed with the observed effects on recorded torque values except for the hardness factor, for which a preference for the 70 degrees ShA value over the 90 degrees ShA value emerged.

Process for casting hard-faced, lightweight camshafts and other cylindrical products

DOEpatents

Hansen, Jeffrey S.; Turner, Paul C.; Argetsinger, Edward R.; Wilson, Rick D.

1996-01-01

A process for casting a hard-faced cylindrical product such as an automobile camshaft includes the steps of: (a) preparing a composition formed from a molten base metal and an additive in particle form and having a hardness value greater than the hardness value of the base metal; (b) introducing the composition into a flask containing a meltable pattern of a cylindrical product such as an automobile camshaft to be manufactured and encased in sand to allow the composition to melt the pattern and assume the shape of the pattern within the sand; and (c) rotating the flask containing the pattern about the longitudinal axes of both the flask and the pattern as the molten base metal containing the additive in particle form is introduced into the flask to cause particles of the additive entrained in the molten base metal to migrate by centrifugal action to the radial extremities of the pattern and thereby provide a cylindrical product having a hardness value greater at it's radial extremities than at its center when the molten base metal solidifies.

An assessment of the water quality of drinking water in rural districts in Zimbabwe. The case of Gokwe South, Nkayi, Lupane, and Mwenezi districts

NASA Astrophysics Data System (ADS)

Hoko, Zvikomborero

Zimbabwe generally receives an average rainfall of 675 mm per annum of which only a maximum of 10% finds its way to rivers as runoff. Gokwe, Nkayi, Lupane and Mwenezi are some of the driest districts in Zimbabwe having mean annual runoffs (MAR) in the range 17-70 mm. River flows especially in Nkayi and Lupane are seasonal and often dry in the period June to November every year. The Kalahari sands predominantly found in such areas as Gokwe, Nkayi, and Lupane promote rapid percolation of rainwater leaving little runoff. The main source of water for domestic purposes in these areas is groundwater with very little reliance on surface water. This study analyzed the water quality of water points in Gokwe South, Nkayi, Lupane, and Mwenezi districts. Parameters analyzed were pH, temperature, dissolved oxygen (DO), turbidity and electrical conductivity (EC). Water quality perceptions from the villagers and the research team were investigated and possible correlations studied. Water quality perceptions included, taste and soap consumption and colour. The uses of the water at domestic level as well as available alternatives to borehole water were investigated. The pH generally ranged from 6.5 to 8.0, which is within the Canadian guidelines. DO was 0.3-5.9 mg/l while turbidity ranged from 0 to 259 NTU with Mwenezi having the highest turbidity value. Conductivity ranged from 70 to 9800 μS/cm with the lowest and highest values recorded in Gokwe and Mwenezi. It was found out that the water quality in terms of taste and odour was 97% satisfactory for Gokwe South, 85% Nkayi, 64% Lupane, and 62% for Mwenezi. High soap consumption which is related to hardness was perceived to be least in Lupane (14%) and highest in Mwenezi with 81%. In general taste complaints also corresponded to high soap consumption but the opposite was not true. It was observed that there was no clear correlation between the quality parameters studied and perceived quality as for example satisfactory taste responses were obtained at EC values higher than the threshold minimum value for objection.

"We Can Get Everything We Want if We Try Hard": Young People, Celebrity, Hard Work

ERIC Educational Resources Information Center

Mendick, Heather; Allen, Kim; Harvey, Laura

2015-01-01

Drawing on 24 group interviews on celebrity with 148 students aged 14-17 across six schools, we show that "hard work" is valued by young people in England. We argue that we should not simply celebrate this investment in hard work. While it opens up successful subjectivities to previously excluded groups, it reproduces neoliberal…

Effects of toothbrush hardness on in vitro wear and roughness of composite resins.

PubMed

Kyoizumi, Hideaki; Yamada, Junji; Suzuki, Toshimitsu; Kanehira, Masafumi; Finger, Werner J; Sasaki, Keiichi

2013-11-01

To investigate and compare the effects of toothbrushes with different hardness on abrasion and surface roughness of composite resins. Toothbrushes (DENT. EX Slimhead II 33, Lion Dental Products Co. Ltd., Tokyo, Japan) marked as soft, medium and hard, were used to brush 10 beam-shaped specimens of each of three composites resins (Venus [VEN], Venus Diamond [VED] and Venus Pearl [VEP]; HeraeusKulzer) with standardized calcium carbonate slurry in a multistation testing machine (2N load, 60 Hz). After each of five cycles with 10k brushing strokes the wear depth and surface roughness of the specimens were determined. After completion of 50k strokes representative samples were inspected by SEM. Data were treated with ANOVA and regression analyses (p < 0.05). Abrasion of the composite resins increased linearly with increasing number of brushing cycles (r² > 0.9). Highest wear was recorded for VEN, lowest for VED. Hard brushes produced significantly higher wear on VEN and VEP, whereas no difference in wear by toothbrush type was detected for VED. Significantly highest surface roughness was found on VED specimens (Ra > 1.5 µm), the lowest one on VEN (Ra < 0.3 µm). VEN specimens showed increased numbers of pinhole defects when brushed with hard toothbrushes, surfaces of VEP were uniformly abraded without level differences between the prepolymerized fillers and the glass filler-loaded matrix, VED showed large glass fillers protruding over the main filler-loaded matrix portion under each condition. Abrasion and surface roughness of composite resins produced by toothbrushing with dentifrice depend mainly on the type of restorative resin. Hardness grades of toothbrushes have minor effects only on abrasion and surface roughness of composite resins. No relationship was found between abrasion and surface roughness. The grade of the toothbrush used has minor effect on wear, texture and roughness of the composite resin.

The epidemiology of bearing surface usage in total hip arthroplasty in the United States.

PubMed

Bozic, Kevin J; Kurtz, Steven; Lau, Edmund; Ong, Kevin; Chiu, Vanessa; Vail, Thomas P; Rubash, Harry E; Berry, Daniel J

2009-07-01

Hard-on-hard bearings offer the potential to improve the survivorship of total hip arthroplasty implants. However, the specific indications for the use of these advanced technologies remain controversial. The purpose of this study was to characterize the epidemiology of bearing surface utilization in total hip arthroplasty in the United States with respect to patient, hospital, geographic, and payer characteristics. The Nationwide Inpatient Sample database was used to analyze bearing type and demographic characteristics associated with 112,095 primary total hip arthroplasties performed in the United States between October 1, 2005, and December 31, 2006. The prevalence of each type of total hip arthroplasty bearing was calculated for population subgroups as a function of age, sex, census region, payer class, and hospital type. The most commonly reported bearing was metal-on-polyethylene (51%) followed by metal-on-metal (35%) and ceramic-on-ceramic (14%). Metal-on-polyethylene bearings were most commonly reported in female Medicare patients who were sixty-five to seventy-four years old, while metal-on-metal and ceramic-on-ceramic bearings were most commonly reported in privately insured male patients who were less than sixty-five years old. Thirty-three percent of patients over sixty-five years old had a hard-on-hard bearing reported. There was substantial regional variation in bearing usage; the highest prevalence of metal-on-polyethylene bearings was reported in the Northeast and at nonteaching hospitals, and the highest prevalence of metal-on-metal bearings was reported in the South and at teaching hospitals. The usage of total hip arthroplasty bearings varies considerably by patient characteristics, hospital type, and geographic location throughout the United States. Despite uncertain advantages in older patients, hard-on-hard bearings are commonly used in patients over the age of sixty-five years. Further study is necessary to define the appropriate indications for these advanced technologies in total hip arthroplasty.

Shear-wave sonoelastography for assessing masseter muscle hardness in comparison with strain sonoelastography: study with phantoms and healthy volunteers

PubMed Central

Nakayama, Miwa; Nishiyama, Wataru; Nozawa, Michihito

2016-01-01

Objectives Shear-wave sonoelastography is expected to facilitate low operator dependency, high reproducibility and quantitative evaluation, whereas there are few reports on available normative values of in vivo tissue in head and neck fields. The purpose of this study was to examine the reliabilities on measuring hardness using shear-wave sonoelastography and to clarify normal values of masseter muscle hardness in healthy volunteers. Methods Phantoms with known hardness ranging from 20 to 140 kPa were scanned with shear-wave sonoelastography, and inter- and intraoperator reliabilities were examined compared with strain sonoelastography. The relationships between the actual and measured hardness were analyzed. The masseter muscle hardness in 30 healthy volunteers was measured using shear-wave sonoelastography. Results: The inter- and intraoperator intraclass correlation coefficients were almost perfect. Strong correlations were seen between the actual and measured hardness. The mean hardness of the masseter muscles in healthy volunteers was 42.82 ± 5.56 kPa at rest and 53.36 ± 8.46 kPa during jaw clenching. Conclusions: The hardness measured with shear-wave sonoelastography showed high-level reliability. Shear-wave sonoelastography may be suitable for evaluation of the masseter muscles. PMID:26624000

Shear-wave sonoelastography for assessing masseter muscle hardness in comparison with strain sonoelastography: study with phantoms and healthy volunteers.

PubMed

Ariji, Yoshiko; Nakayama, Miwa; Nishiyama, Wataru; Nozawa, Michihito; Ariji, Eiichiro

2016-01-01

Objectives Shear-wave sonoelastography is expected to facilitate low operator dependency, high reproducibility and quantitative evaluation, whereas there are few reports on available normative values of in vivo tissue in head and neck fields. The purpose of this study was to examine the reliabilities on measuring hardness using shear-wave sonoelastography and to clarify normal values of masseter muscle hardness in healthy volunteers. Methods Phantoms with known hardness ranging from 20 to 140 kPa were scanned with shear-wave sonoelastography, and inter- and intraoperator reliabilities were examined compared with strain sonoelastography. The relationships between the actual and measured hardness were analyzed. The masseter muscle hardness in 30 healthy volunteers was measured using shear-wave sonoelastography. The inter- and intraoperator intraclass correlation coefficients were almost perfect. Strong correlations were seen between the actual and measured hardness. The mean hardness of the masseter muscles in healthy volunteers was 42.82 ± 5.56 kPa at rest and 53.36 ± 8.46 kPa during jaw clenching. The hardness measured with shear-wave sonoelastography showed high-level reliability. Shear-wave sonoelastography may be suitable for evaluation of the masseter muscles.

NIST/ISAC standardization study: variability in assignment of intensity values to fluorescence standard beads and in cross calibration of standard beads to hard dyed beads.

PubMed

Hoffman, Robert A; Wang, Lili; Bigos, Martin; Nolan, John P

2012-09-01

Results from a standardization study cosponsored by the International Society for Advancement of Cytometry (ISAC) and the US National Institute of Standards and Technology (NIST) are reported. The study evaluated the variability of assigning intensity values to fluorophore standard beads by bead manufacturers and the variability of cross calibrating the standard beads to stained polymer beads (hard-dyed beads) using different flow cytometers. Hard dyed beads are generally not spectrally matched to the fluorophores used to stain cells, and spectral response varies among flow cytometers. Thus if hard dyed beads are used as fluorescence calibrators, one expects calibration for specific fluorophores (e.g., FITC or PE) to vary among different instruments. Using standard beads surface-stained with specific fluorophores (FITC, PE, APC, and Pacific Blue™), the study compared the measured intensity of fluorophore standard beads to that of hard dyed beads through cross calibration on 133 different flow cytometers. Using robust CV as a measure of variability, the variation of cross calibrated values was typically 20% or more for a particular hard dyed bead in a specific detection channel. The variation across different instrument models was often greater than the variation within a particular instrument model. As a separate part of the study, NIST and four bead manufacturers used a NIST supplied protocol and calibrated fluorophore solution standards to assign intensity values to the fluorophore beads. Values assigned to the reference beads by different groups varied by orders of magnitude in most cases, reflecting differences in instrumentation used to perform the calibration. The study concluded that the use of any spectrally unmatched hard dyed bead as a general fluorescence calibrator must be verified and characterized for every particular instrument model. Close interaction between bead manufacturers and NIST is recommended to have reliable and uniformly assigned fluorescence standard beads. Copyright © 2012 International Society for Advancement of Cytometry.

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.

PubMed

Bolay, Sukran; Cakir, Filiz Yalcin; Gurgan, Sevil

2012-09-01

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

Global chemical reactivity parameters for several chiral beta-blockers from the Density Functional Theory viewpoint

PubMed Central

TALMACIU, MONA MARIA; BODOKI, EDE; OPREAN, RADU

2016-01-01

Background and aim Beta-adrenergic antagonists have been established as first line treatment in the medical management of hypertension, acute coronary syndrome and other cardiovascular diseases, as well as for the prevention of initial episodes of gastrointestinal bleeding in patients with cirrhosis and esophageal varices, glaucoma, and have recently become the main form of treatment of infantile hemangiomas. The aim of the present study is to calculate for 14 beta-blockers several quantum chemical descriptors in order to interpret various molecular properties such as electronic structure, conformation, reactivity, in the interest of determining how such descriptors could have an impact on our understanding of the experimental observations and describing various aspects of chemical binding of beta-blockers in terms of these descriptors. Methods The 2D chemical structures of the beta-blockers (14 molecules with one stereogenic center) were cleaned in 3D, their geometry was preoptimized using the software MOPAC2012, by PM6 method, and then further refined using standard settings in MOE; HOMO and LUMO descriptors were calculated using semi-empirical molecular orbital methods AM1, MNDO and PM3, for the lowest energy conformers and the quantum chemical descriptors (HLG, electronegativity, chemical potential, hardness and softness, electrophilicity) were then calculated. Results According to HOMO-LUMO gap and the chemical hardness the most stable compounds are alprenolol, bisoprolol and esmolol. The softness values calculated for the study molecules revolve around 0.100. Propranolol, sotalol and timolol have among the highest electrophilicity index of the studied beta-blocker molecules. Results obtained from calculations showed that acebutolol, atenolol, timolol and sotalol have the highest values for the electronegativity index. Conclusions The future aim is to determine whether it is possible to find a valid correlation between these descriptors and the physicochemical behavior of the molecules from this class. The HLG could be correlated to the experimentally recorded electrochemical properties of the molecules. HOMO could be correlated to the observed oxidation potential, since the required voltage is related to the energy of the HOMO, because only the electron from this orbital is involved in the oxidation process. PMID:27857521

Comparative Mechanical Improvement of Stainless Steel 304 Through Three Methods

NASA Astrophysics Data System (ADS)

Mubarok, N.; Notonegoro, H. A.; Thosin, K. A. Z.

2018-05-01

Stainless Steel 304 (SS304) is one of stainless steel group widely used in industries for various purposes. In this paper, we compared the experimental process to enhance the mechanical properties of the surface SS304 through three different methods, cold rolled, annealed salt baht bronzing (ASB), and annealed salt baht boronizing-quench (ASB-Q). The phase change in SS304 due to the cold rolled process makes this method is to abandon. The increasing of the annealing time in the ASB method has a nonlinear relationship with the increases in hardness value. Comparing to the increases in hardness value of the ASB method, the hardness value of ASB-Q methods is still lower than that method.

The effect of tempering treatment on mechanical properties and microstructure for armored lateritic steel

NASA Astrophysics Data System (ADS)

Herbirowo, Satrio; Adjiantoro, Bintang; Romijarso, Toni Bambang; Pramono, Andika Widya

2018-05-01

High demand of armor material impacts on the use of lateritic steel as alternative armored material, therefore an increase of its mechanical properties is necessary. Quenching and tempering process can be used to increase the mechanical properties of the lateritic steel. The variables that used in this research are variation in media quench (water, oil, and air) and variation in tempering temperatures (0, 100, and 200 °C). The results show that specimen with water quenchant tempered at 100 °C have the highest average on hardness (59.1 HRC) and tensile strength. Specimen with oil quenchant tempered at 100 °C has the highest impact toughness (52 J). Secondary hardening and tempered martensite embrittlement phenomenon is found in some specimens where its hardness increased and its impact toughness decreased after the tempering process. Microstructures which formed in this process are martensite and retained austenite phase with fracture types are brittle.

Modeling of the reburning process using sewage sludge-derived syngas.

PubMed

Werle, Sebastian

2012-04-01

Gasification of sewage sludge can provide clean and effective reburning fuel for combustion applications. The motivation of this work was to define the reburning potential of the sewage sludge gasification gas (syngas). A numerical simulation of the co-combustion process of syngas in a hard coal-fired boiler was done. All calculations were performed using the Chemkin programme and a plug-flow reactor model was used. The calculations were modelled using the GRI-Mech 2.11 mechanism. The highest conversions for nitric oxide (NO) were obtained at temperatures of approximately 1000-1200K. The combustion of hard coal with sewage sludge-derived syngas reduces NO emissions. The highest reduction efficiency (>90%) was achieved when the molar flow ratio of the syngas was 15%. Calculations show that the analysed syngas can provide better results than advanced reburning (connected with ammonia injection), which is more complicated process. Copyright © 2011 Elsevier Ltd. All rights reserved.

Porous Hard Carbon Derived from Walnut Shell as an Anode Material for Sodium-Ion Batteries

NASA Astrophysics Data System (ADS)

Zhang, Sensen; Li, Ying; Li, Min

2018-02-01

Porous hard carbon with large interlayer distance was fabricated from walnut shells through a facile high-temperature pyrolysis process and investigated as an anode material for sodium-ion batteries (SIBs). The results show that the electrochemical performance is mainly dependent on the pyrolysis temperature. The porous hard carbon, which was carbonized at 1300°C, displays the highest reversible capacity of 230 mAh g-1 at 20 mA g-1 and an excellent cycling stability (96% capacity retained over 200 cycles). The promising electrochemical performances are attributed to the porous structure reducing distances for sodium ion diffusion and expanded interlayer spacing, which is beneficial for sodium reversible insertion/extraction. The excellent electrochemical performance as well as the low-cost and environmental friendliness demonstrates that walnut shell-derived porous hard carbon is a promising anode material candidate for SIBs.

Precision of hard structures used to estimate age of mountain Whitefish (Prosopium williamsoni)

USGS Publications Warehouse

Watkins, Carson J.; Ross, Tyler J.; Hardy, Ryan S.; Quist, Michael C.

2015-01-01

The mountain whitefish (Prosopium williamsoni) is a widely distributed salmonid in western North America that has decreased in abundance over portions of its distribution due to anthropogenic disturbances. In this investigation, we examined precision of age estimates derived from scales, pectoral fin rays, and sagittal otoliths from 167 mountain whitefish. Otoliths and pectoral fin rays were mounted in epoxy and cross-sectioned before examination. Scales were pressed onto acetate slides and resulting impressions were examined. Between-reader precision (i.e., between 2 readers), between-reader variability, and reader confidence ratings were compared among hard structures. Coefficient of variation (CV) in age estimates was lowest and percentage of exact agreement (PA-0) was highest for scales (CV = 5.9; PA-0 = 70%) compared to pectoral fin rays (CV =11.0; PA-0 = 58%) and otoliths (CV = 12.3; PA-0 = 55%). Median confidence ratings were significantly different (P ≤ 0.05) among all structures, with scales having the highest median confidence. Reader confidence decreased with fish age for scales and pectoral fin rays, but reader confidence increased with fish age for otoliths. In general, age estimates were more precise and reader confidence was higher for scales compared to pectoral fin rays and otoliths. This research will help fisheries biologists in selecting the most appropriate hard structure to use for future age and growth studies on mountain whitefish. In turn, selection of the most precise hard structure will lead to better estimates of dynamic rate functions.

Experimental Studies on Al (5.7% Zn) Alloy based Hybrid MMC

NASA Astrophysics Data System (ADS)

Shivaprakash, Y. M.; Ramu, H. C.; Chiranjivee; Kumar, Roushan; Kumar, Deepak

2018-02-01

In this investigation, an attempt is made to disperse SiC (20-25 microns) and Gr (15-20 microns) in the aluminium alloy having Zn, Mg and coper as major alloying elements. The composite is further subjected to mechanical testing to determine various properties like hardness, tensile strength and wear resistance. The alloy and composite samples were tested in the un heat treated conditions. All the tests were done at the laboratory conditions as per ASTM standards. The Pin-On-Disc tribometer is used to test the two-body abrasive sliding wear behaviour in dry conditions. The wear pattern is analysed by the optical images of worn surface taken in an inverted metallurgical microscope. The calculated density is found to be reducing as the SiC and Gr quantity is increased in the base alloy. The as cast Al alloy was found to be having highest hardness. The introduction of SiC tend to increase the hardness and UTS, since Gr is also introduced simultaneously which tends to reduce the hardness and UTS of composite. The composite having highest quantity of Gr showed superior wear resistance which is mainly because the Gr particulates provide an inbuilt lubricating properties to composite. The analysis of images of worn surface showed the abrasive and delamination pattern of wear. The composites developed in the present work can be used in the automobile and aerospace parts that are light in weight and require self-lubricating properties to enhance the wear resistance.

Friction behavior of 304 stainless steel of varying hardness lubricated with benzene and some benzyl structures

NASA Technical Reports Server (NTRS)

Buckley, D. H.

1974-01-01

The lubricating properties of some benzyl and benzene structures were determined by using 304 stainless steel surfaces strained to various hardness. Friction coefficients and wear track widths were measured with a Bowden-Leben type friction apparatus by using a pin-on-disk specimen configuration. Results obtained indicate that benzyl monosulfide, dibenzyl disulfide, and benzyl alcohol resulted in the lowest friction coefficients for 304 stainless steel, while benzyl ether provided the least surface protection and gave the highest friction. Strainhardening of the 304 stainless steel prior to sliding resulted in reduced friction in dry sliding. With benzyl monosulfide, dibenzyl disulfide, and benzyl alcohol changes in 304 stainless steel hardness had no effect upon friction behavior.

Development of Finite Element Forulations for High-Fidelity Polycrystals and Damage Avoidance in Friction Stir Welding

DTIC Science & Technology

2010-07-26

evolving Voce hardness at the end of each bending and straightening cycle. The value contoured is the element average Voce hardness calculated by volume...cycle is shown in Figure 18. These results show that the gradient hardness is on the order of 10% of the Voce hardness. Increasing the gradient...the models or to the Voce hardness patterns. There are notable changes between the fully bent and fully straightened deformations that indicate a

Hardness and Microstructure of Binary and Ternary Nitinol Compounds

NASA Technical Reports Server (NTRS)

Stanford, Malcolm K.

2016-01-01

The hardness and microstructure of twenty-six binary and ternary Nitinol (nickel titanium, nickel titanium hafnium, nickel titanium zirconium and nickel titanium tantalum) compounds were studied. A small (50g) ingot of each compound was produced by vacuum arc remelting. Each ingot was homogenized in vacuum for 48 hr followed by furnace cooling. Specimens from the ingots were then heat treated at 800, 900, 1000 or 1100 degree C for 2 hr followed by water quenching. The hardness and microstructure of each specimen was compared to the baseline material (55-Nitinol, 55 at.% nickel - 45 at.% titanium, after heat treatment at 900 degC). The results show that eleven of the studied compounds had higher hardness values than the baseline material. Moreover, twelve of the studied compounds had measured hardness values greater 600HV at heat treatments from 800 to 900 degree C.

Influence of different fillers on the properties of an experimental vinyl polysiloxane.

PubMed

Meincke, Débora Könzgen; Ogliari, Aline de Oliveira; Ogliari, Fabrício Aulo

2016-01-01

The aim of the study was to evaluate the effect of the incorporation of different fillers on an experimental vinyl polysiloxane (VPS) at two different concentrations, 20% and 40%. Different fillers were added to an experimental VPS. The study was developed in two stages: (i) incorporation of fillers in different concentrations: (a) 20 wt% fillers, and (b) 40 wt%. The fillers were added to experimental VPS and mixed with a speed mixer; (ii) characterization of experimental VPS; after the base paste and catalyst paste were mixed, the experimental VPS was used to make specimens specifically for each test, which were stored at 23°C for 24 hours. The tests were designed according to the specific standardization for the analysis of tensile strength, detail reproduction, Shore A hardness, and elastic recovery. For analysis of filler size pattern, scanning electron microscopy at 1500× magnification was used. The aerosil OX-50 40% (AE), and pure aluminum hydroxide 40% (PAH) groups presented the highest tensile strength and Shore A hardness values. However, those were the only groups that did not present continuous detail reproduction of an intersection of 20 μm line. The elastic recovery was not statistically significant. The undesirable characteristics of VPS (lowest Shore A hardness and tensile strength) were observed when it was added to the composition of acrylic polymer (AP) and fiberglass (FG) in both concentrations, 20% and 40%. In groups AE and PAH, agglomerates of nanofillers were shown in SEM micrography, while the other groups presented different shapes and fillers sizes.

A locally adaptive kernel regression method for facies delineation

NASA Astrophysics Data System (ADS)

Fernàndez-Garcia, D.; Barahona-Palomo, M.; Henri, C. V.; Sanchez-Vila, X.

2015-12-01

Facies delineation is defined as the separation of geological units with distinct intrinsic characteristics (grain size, hydraulic conductivity, mineralogical composition). A major challenge in this area stems from the fact that only a few scattered pieces of hydrogeological information are available to delineate geological facies. Several methods to delineate facies are available in the literature, ranging from those based only on existing hard data, to those including secondary data or external knowledge about sedimentological patterns. This paper describes a methodology to use kernel regression methods as an effective tool for facies delineation. The method uses both the spatial and the actual sampled values to produce, for each individual hard data point, a locally adaptive steering kernel function, self-adjusting the principal directions of the local anisotropic kernels to the direction of highest local spatial correlation. The method is shown to outperform the nearest neighbor classification method in a number of synthetic aquifers whenever the available number of hard data is small and randomly distributed in space. In the case of exhaustive sampling, the steering kernel regression method converges to the true solution. Simulations ran in a suite of synthetic examples are used to explore the selection of kernel parameters in typical field settings. It is shown that, in practice, a rule of thumb can be used to obtain suboptimal results. The performance of the method is demonstrated to significantly improve when external information regarding facies proportions is incorporated. Remarkably, the method allows for a reasonable reconstruction of the facies connectivity patterns, shown in terms of breakthrough curves performance.

Formulation development and optimization: Encapsulated system of Atenolol and Glyburide.

PubMed

Maboos, Madiha; Yousuf, Rabia Ismail; Shoaib, Muhammad Harris

2016-03-01

Objective of this study is to develop; tablet-in-a capsule system, to deliver Atenolol 25mg and Glyburide 5mg in the hard gelatin capsule. In order to improve patient compliance and reduce problems associated with complex therapeutic regimen Atenolol (cardio-selective beta-blocker) and Glyburide (anti-diabetic; sulfonylurea) are commonly, prescribed to the diabetic hypertensive patient. Metgod: In present work six different formulations of Atenolol (AF1-AF6) and Glyburide (GF1-GF6) were prepared by direct compression method using Avicel, Lactose DC, Crospovidone and Magnesium Stearate in different proportions and encapsulated in hard gelatin shells. Post compression parameters i.e. weight variation, diameter variation, thickness variation, hardness variation, % friability, disintegration, % drug release were determined at different pH 1.2, 4.5 and 6.8, and subjected to dissolution profile comparison through similarity factor (ƒ2). Stability studies were performed and shelf lives were calculated by R-Gui Stab R console 2.15.2 and determined to be 15 and 27 months for Atenolol and Glyburide respectively. The percentage drug contents of Atenolol and Glyburide were estimated spectrophotometerically at 286 nm and 314.7 nm respectively. Formulations CF1-CF6 (encapsulated) were subjected to weight variation, disintegration and dissolution tests and subjected to model dependant analysis for dissolution studies. The simultaneous quantitation of Atenolol and Glyburide for content assay was done by HPLC method of analysis. formulation CF6 is showing highest coefficient of correlation values for all models applied. So we can conclude that the proposed system can improve patient compliance by increasing the ease of administration of two drugs together.

Calcium ascorbate as a potential partial substitute for NaCl in dry fermented sausages: effect on colour, texture and hygienic quality at different concentrations.

PubMed

Gimeno, O; Astiasarán, I; Bello, J

2001-01-01

A control product (2.6% NaCl) and different treatments with reduced levels of salt (1, 2.3% NaCl; 2, 2.0% NaCl; 3, 1.7% NaCl; 4, 1.4% NaCl) and increased amounts of calcium ascorbate with an equivalent ionic strength to that of the control were assayed. The percentages of reduction of sodium content in relation to the control were 15, 24, 37 and 45% and the supply of calcium was 26, 33, 42 and 50% of the Recommended Dietary Allowance (RDAs established by NRC, US) for treatments 1, 2, 3 and 4, respectively. Partial substitution of NaCl by calcium ascorbate caused higher acidification related with the higher lactic acid bacteria development and probably with the presence of calcium. The instrumental measurement of colour gave rise to some significant differences especially with the highest amount of calcium ascorbate (treatment 4), giving rise to significant higher a* and b* values and lower L* values in relation to the control. Treatments 2, 3 and 4 lead to products with lower hardness and gumminess values than the control. No problems related to the hygienic quality were observed.

Preparation and evaluation of silicon nitride matrices for silicon nitride-SiC fiber composites. M.S. Thesis Final Technical Report

NASA Technical Reports Server (NTRS)

Axelson, Scott R.

1988-01-01

Continuous silicon carbide (SiC) fiber was added to three types of silicon nitride (Si3N4) matrices. Efforts were aimed at producing a dense Si3N4 matrix from reaction-bonded silicon nitride (RBSN) by hot-isostatic-pressing (HIP) and pressureless sintering, and from Si3N4 powder by hot-pressing. The sintering additives utilized were chosen to allow for densification, while not causing severe degradation of the fiber. The ceramic microstructures were evaluated using scanning optical microscopy. Vickers indentation was used to determine the microhardness and fracture toughness values of the matrices. The RBSN matrices in this study did not reach more than 80 percent of theoretical density after sintering at various temperatures, pressures, and additive levels. Hot-pressing Si3N4 powder produced the highest density matrices; hardness and toughness values were within an order of magnitude of the best literature values. The best sintering aid composition chosen included Y2O3, SiO2, and Al2O3 or AlN. Photomicrographs demonstrate a significant reduction of fiber attack by this additive composition.

Co-electrodeposition of hard Ni-W/diamond nanocomposite coatings

PubMed Central

Zhang, Xinyu; Qin, Jiaqian; Das, Malay Kumar; Hao, Ruru; Zhong, Hua; Thueploy, Adisak; Limpanart, Sarintorn; Boonyongmaneerat, Yuttanant; Ma, Mingzhen; Liu, Riping

2016-01-01

Electroplated hard chrome coating is widely used as a wear resistant coating to prolong the life of mechanical components. However, the electroplating process generates hexavalent chromium ion which is known carcinogen. Hence, there is a major effort throughout the electroplating industry to replace hard chrome coating. Composite coating has been identified as suitable materials for replacement of hard chrome coating, while deposition coating prepared using traditional co-deposition techniques have relatively low particles content, but the content of particles incorporated into a coating may fundamentally affect its properties. In the present work, Ni-W/diamond composite coatings were prepared by sediment co-electrodeposition from Ni-W plating bath, containing suspended diamond particles. This study indicates that higher diamond contents could be successfully co-deposited and uniformly distributed in the Ni-W alloy matrix. The maximum hardness of Ni-W/diamond composite coatings is found to be 2249 ± 23 Hv due to the highest diamond content of 64 wt.%. The hardness could be further enhanced up to 2647 ± 25 Hv with heat treatment at 873 K for 1 h in Ar gas, which is comparable to hard chrome coatings. Moreover, the addition of diamond particles could significantly enhance the wear resistance of the coatings. PMID:26924136

Co-electrodeposition of hard Ni-W/diamond nanocomposite coatings.

PubMed

Zhang, Xinyu; Qin, Jiaqian; Das, Malay Kumar; Hao, Ruru; Zhong, Hua; Thueploy, Adisak; Limpanart, Sarintorn; Boonyongmaneerat, Yuttanant; Ma, Mingzhen; Liu, Riping

2016-02-29

Electroplated hard chrome coating is widely used as a wear resistant coating to prolong the life of mechanical components. However, the electroplating process generates hexavalent chromium ion which is known carcinogen. Hence, there is a major effort throughout the electroplating industry to replace hard chrome coating. Composite coating has been identified as suitable materials for replacement of hard chrome coating, while deposition coating prepared using traditional co-deposition techniques have relatively low particles content, but the content of particles incorporated into a coating may fundamentally affect its properties. In the present work, Ni-W/diamond composite coatings were prepared by sediment co-electrodeposition from Ni-W plating bath, containing suspended diamond particles. This study indicates that higher diamond contents could be successfully co-deposited and uniformly distributed in the Ni-W alloy matrix. The maximum hardness of Ni-W/diamond composite coatings is found to be 2249 ± 23 Hv due to the highest diamond content of 64 wt.%. The hardness could be further enhanced up to 2647 ± 25 Hv with heat treatment at 873 K for 1 h in Ar gas, which is comparable to hard chrome coatings. Moreover, the addition of diamond particles could significantly enhance the wear resistance of the coatings.

Co-electrodeposition of hard Ni-W/diamond nanocomposite coatings

NASA Astrophysics Data System (ADS)

Zhang, Xinyu; Qin, Jiaqian; Das, Malay Kumar; Hao, Ruru; Zhong, Hua; Thueploy, Adisak; Limpanart, Sarintorn; Boonyongmaneerat, Yuttanant; Ma, Mingzhen; Liu, Riping

2016-02-01

Electroplated hard chrome coating is widely used as a wear resistant coating to prolong the life of mechanical components. However, the electroplating process generates hexavalent chromium ion which is known carcinogen. Hence, there is a major effort throughout the electroplating industry to replace hard chrome coating. Composite coating has been identified as suitable materials for replacement of hard chrome coating, while deposition coating prepared using traditional co-deposition techniques have relatively low particles content, but the content of particles incorporated into a coating may fundamentally affect its properties. In the present work, Ni-W/diamond composite coatings were prepared by sediment co-electrodeposition from Ni-W plating bath, containing suspended diamond particles. This study indicates that higher diamond contents could be successfully co-deposited and uniformly distributed in the Ni-W alloy matrix. The maximum hardness of Ni-W/diamond composite coatings is found to be 2249 ± 23 Hv due to the highest diamond content of 64 wt.%. The hardness could be further enhanced up to 2647 ± 25 Hv with heat treatment at 873 K for 1 h in Ar gas, which is comparable to hard chrome coatings. Moreover, the addition of diamond particles could significantly enhance the wear resistance of the coatings.

Light energy attenuation through orthodontic ceramic brackets at different irradiation times.

PubMed

Santini, Ario; Tiu, Szu Hui; McGuinness, Niall J P; Aldossary, Mohammed Saeed

2016-09-01

To evaluate the total light energy (TLE) transmission through three types of ceramic brackets with, bracket alone and with the addition of orthodontic adhesive, at different exposure durations, and to compare the microhardness of the cured adhesive. Three different makes of ceramic brackets, Pure Sapphire(M), Clarity™ ADVANCED(P) and Dual Ceramic(P) were used. Eighteen specimens of each make were prepared and allocated to three groups (n = 6). MARC(®)-resin calibrator was used to determine the light curing unit (LCU) tip irradiance (mW/cm(2)) and TLE (J/cm(2)) transmitted through the ceramic brackets, and through ceramic bracket plus Transbond™ XT Light Cure Adhesive, for 5, 10 and 20 s. Vickers-hardness values at the bottom of the cured adhesive were determined. Statistical analysis used one-way analysis of variance (ANOVA); P = 0.05. TLE transmission rose significantly among all samples with increasing exposure durations. TLE reaching the adhesive- enamel interface was less than 10 J/cm(2), and through monocrystalline and polycrystalline ceramic brackets was significantly different (P < 0.05). Pure Sapphire(M) showed the highest amount of TLE transmission and Vickers-hardness values for 5, 10 and 20 s. Following manufacturer's recommendations, insufficient TLE may be delivered to the adhesive: increasing the exposure durations may be required when adhesive is cured through ceramic brackets. Clinicians are advised to measure the tip irradiance of their LCUs and increase curing time beyond 5 s. Orthodontic clinicians should understand the type of light curing device and the orthodontic adhesive used in their practice.

Effects of Various Kinds of Salt on the Quality and Storage Characteristics of Tteokgalbi.

PubMed

Lee, Hyun-Joo; Lee, Jae-Joon

2014-01-01

This study was carried out to evaluate the effects of various kinds of salt on the quality and storage characteristics of tteokgalbi. The tteokgalbi was prepared using four types of salt: 1.5% purified salt (control, C), 1.5% five-year-old solar salt (FS), 1.5% Topan solar salt (TS), and 1.5% French Guérande solar salt (GS). The moisture, crude lipid, crude ash, crude protein and calorie contents, water holding capacity, and cooking loss were not significantly different between control and all other treatments. As for the textural characteristics, the use of GS increased the hardness of the tteokgalbi. According to the sensory evaluation, the use of TS had the best score in springiness. Tteokgalbi made with TS and GS had the two highest scores in flavor and total acceptability. During 15 d of storage, the contents of 2-thiobarbituric acid (TBA) value, volatile basic nitrogen (VBN) and the total microbial counts increased, while the pH decreased. The TBA values of the tteokgalbi containing TS and GS were lower than that of C. Lightness (L) and yellowness (b) values decreased during storage, but redness (a) displayed no significant difference during storage. Overall, the best results, in terms of TBA value and sensory attributes, were obtained for the tteokgalbi containing TS and GS.

The use of sensory perception indicators for improving the characterization and modelling of total petroleum hydrocarbon (TPH) grade in soils.

PubMed

Roxo, Sónia; de Almeida, José António; Matias, Filipa Vieira; Mata-Lima, Herlander; Barbosa, Sofia

2016-03-01

This paper proposes a multistep approach for creating a 3D stochastic model of total petroleum hydrocarbon (TPH) grade in potentially polluted soils of a deactivated oil storage site by using chemical analysis results as primary or hard data and classes of sensory perception variables as secondary or soft data. First, the statistical relationship between the sensory perception variables (e.g. colour, odour and oil-water reaction) and TPH grade is analysed, after which the sensory perception variable exhibiting the highest correlation is selected (oil-water reaction in this case study). The probabilities of cells belonging to classes of oil-water reaction are then estimated for the entire soil volume using indicator kriging. Next, local histograms of TPH grade for each grid cell are computed, combining the probabilities of belonging to a specific sensory perception indicator class and conditional to the simulated values of TPH grade. Finally, simulated images of TPH grade are generated by using the P-field simulation algorithm, utilising the local histograms of TPH grade for each grid cell. The set of simulated TPH values allows several calculations to be performed, such as average values, local uncertainties and the probability of the TPH grade of the soil exceeding a specific threshold value.

Does the casting mode influence microstructure, fracture and properties of different metal ceramic alloys?

PubMed

Bauer, José Roberto de Oliveira; Grande, Rosa Helena Miranda; Rodrigues-Filho, Leonardo Eloy; Pinto, Marcelo Mendes; Loguercio, Alessandro Dourado

2012-01-01

The aim of the present study was to evaluate the tensile strength, elongation, microhardness, microstructure and fracture pattern of various metal ceramic alloys cast under different casting conditions. Two Ni-Cr alloys, Co-Cr and Pd-Ag were used. The casting conditions were as follows: electromagnetic induction under argon atmosphere, vacuum, using blowtorch without atmosphere control. For each condition, 16 specimens, each measuring 25 mm long and 2.5 mm in diameter, were obtained. Ultimate tensile strength (UTS) and elongation (EL) tests were performed using a Kratos machine. Vickers Microhardness (VM), fracture mode and microstructure were analyzed by SEM. UTS, EL and VM data were statistically analyzed using ANOVA. For UTS, alloy composition had a direct influence on casting condition of alloys (Wiron 99 and Remanium CD), with higher values shown when cast with Flame/Air (p < 0.05). The factors 'alloy" and 'casting condition" influenced the EL and VM results, generally presenting opposite results, i.e., alloy with high elongation value had lower hardness (Wiron 99), and casting condition with the lowest EL values had the highest VM values (blowtorch). Both factors had significant influence on the properties evaluated, and prosthetic laboratories should select the appropriate casting method for each alloy composition to obtain the desired property.

Comparative Study on the Effects of Boiling, Steaming, Grilling, Microwaving and Superheated Steaming on Quality Characteristics of Marinated Chicken Steak

PubMed Central

Choi, Yun-Sang; Kim, Young-Boong; Jeon, Ki-Hong; Kim, Eun-Mi; Sung, Jung-Min; Kim, Hyun-Wook

2016-01-01

The effects of five different cooking methods (boiling, steaming, grilling, microwaving, and superheated steaming) on proximate composition, pH, color, cooking loss, textural properties, and sensory characteristics of chicken steak were studied. Moisture content and lightness value (L*-value) were higher in superheated steam cooked chicken steak than that of the other cooking treatments such as boiling, steaming, grilling and microwaving cooking (p<0.05), whereas protein content, redness value (a*-value), hardness, gumminess, and chewiness of superheated steam cooked chicken steak was lower than that in the other cooking treatments (p<0.05). Fat content and ash content, springiness, and cohesiveness were not significantly different among the chicken steak cooked using various methods (p>0.05). Among the sensory characteristics, tenderness score, juiciness score and overall acceptability score were the highest for the superheated steam samples (p<0.05), whereas no difference in flavor scores were observed among the other treatments (p>0.05). These results show that marinated chicken steak treated with superheated steam in a preheated 250℃ oven and 380℃ steam for 5 min until core temperature reached 75℃ improved the quality characteristics and sensory properties the best. Therefore, superheated steam was useful to improve cooked chicken steak. PMID:27499656

Microstructure and Wear Resistance of Composite Coating by Laser Cladding Al/TiN on the Ti-6Al-4V Substrate

NASA Astrophysics Data System (ADS)

Zhang, H. X.; Yu, H. J.; Chen, C. Z.

2015-05-01

The composite coatings were fabricated by laser cladding Al/TiN pre-placed powders on Ti-6Al-4V substrate for enhancing wear resistance and hardness of the substrate. The composite coatings were analyzed by means of X-ray diffraction (XRD), scanning electron microscope (SEM) and energy dispersive spectrometer (EDS). The sliding wear tests were performed by MM200 wear test machine. The hardness of the coatings was tested by HV-1000 hardness tester. After laser cladding, it was found that there was a good metallurgical bond between the coating and the substrate. The composite coatings were mainly composed of the matrix of β-Ti (Al) and the reinforcements of titanium nitride (TiN), Ti3Al, TiAl and Al3Ti. The hardness and wear resistance of the coatings on four samples were greatly improved, among which sample 4 exhibited the highest hardness and best wear resistance. The hardness of the coating on sample 4 was approximately 2.5 times of the Ti-6Al-4V substrate. And the wear resistance of sample 4 was four times of the substrate.

Nanomechanical and nanotribological properties of Nb substituted TiN thin films

NASA Astrophysics Data System (ADS)

Krishna, M. Ghanashyam; Vasu, K.; Padmanabhan, K. A.

2012-06-01

Nanomechanical and nanotribological properties of Ti1-xNbxN (0≤x≤1) thin films were investigated as a function x. The films were deposited onto polycrystalline nuclear grade 316LN stainless steel (SS) substrate by radio frequency magnetron sputtering in 100% N2 plasma. The hardness and Young's modulus increased while the friction coefficient and wear volume decreased with increasing Nb substitution. The highest hardness achieved was 31GPa for x=0.77. At the same Nb concentration, the friction coefficient was 0.15 and the elastic recovery was 60%.

Fabrication of Self-Ordered Alumina Films with Large Interpore Distance by Janus Anodization in Citric Acid

NASA Astrophysics Data System (ADS)

Ma, Yingjun; Wen, Yihao; Li, Juan; Li, Yuxin; Zhang, Zhiying; Feng, Chenchen; Sun, Runguang

2016-12-01

Self-organized porous anodic alumina (PAA) formed by electrochemical anodization have become a fundamental tool to develop various functional nanomaterials. However, it is still a great challenge to break the interpore distance (Dint) limit (500 nm) by using current anodization technologies of mild anodization (MA) and hard anodization (HA). Here, we reported a new anodization mode named “Janus anodization” (JA) to controllably fabricate self-ordered PAA with large Dint at high voltage of 350-400 V. JA naturally occurs as anodizing Al foils in citric acid solution, which possessing both the characteristics of MA and HA. The process can be divided into two stages: I, slow pore nucleation stage similar to MA; II, unequilibrium self-organization process similar to HA. The as-prepared films had the highest modulus (7.0 GPa) and hardness (127.2 GPa) values compared with the alumina obtained by MA and HA. The optical studies showed that the black films have low reflectance (<10 %) in the wavelength range of 250-1500 nm and photoluminescence property. Dint can be tuned between 645-884 nm by controlling citric acid concentration or anodization voltage. JA is a potential technology to efficiently and controllably fabricate microstructured or hybrid micro- and nanostructured materials with novel properties.

Fabrication of Self-Ordered Alumina Films with Large Interpore Distance by Janus Anodization in Citric Acid

PubMed Central

Ma, Yingjun; Wen, Yihao; Li, Juan; Li, Yuxin; Zhang, Zhiying; Feng, Chenchen; Sun, Runguang

2016-01-01

Self-organized porous anodic alumina (PAA) formed by electrochemical anodization have become a fundamental tool to develop various functional nanomaterials. However, it is still a great challenge to break the interpore distance (Dint) limit (500 nm) by using current anodization technologies of mild anodization (MA) and hard anodization (HA). Here, we reported a new anodization mode named “Janus anodization” (JA) to controllably fabricate self-ordered PAA with large Dint at high voltage of 350–400 V. JA naturally occurs as anodizing Al foils in citric acid solution, which possessing both the characteristics of MA and HA. The process can be divided into two stages: I, slow pore nucleation stage similar to MA; II, unequilibrium self-organization process similar to HA. The as-prepared films had the highest modulus (7.0 GPa) and hardness (127.2 GPa) values compared with the alumina obtained by MA and HA. The optical studies showed that the black films have low reflectance (<10 %) in the wavelength range of 250–1500 nm and photoluminescence property. Dint can be tuned between 645–884 nm by controlling citric acid concentration or anodization voltage. JA is a potential technology to efficiently and controllably fabricate microstructured or hybrid micro- and nanostructured materials with novel properties. PMID:27958365

A Novel Approach to Determine the Prevalence of Type of Soft Palate Using Digital Intraoral Impression

PubMed Central

Khaled Addas, Mohamed; Al Humaidi, Abdullah Saad Ali; Al Qahtani, Abdulrazaq Mohammed; Al Qahtani, Mubarak Daghash

2017-01-01

Aim To determine the prevalence of type of soft palate in targeted population. Materials and Methods Using computer technology in dentistry, intraoral digital scanner, and 3D analysis software tool, study was conducted. 100 patients selected from the outpatient clinics were divided into two groups based on the ages of 20–40 years and 41–60 years with equal ratio of males and females. Each selected patient's maxillary arch was scanned with intraoral scanner; images so obtained were sectioned in anteroposterior cross section and with the 3D analysis software; the angulation between hard and soft palate was determined. Results The prevalence of type II soft palate (angulation between hard and soft palate is between 10 and 45 degrees) was highest, 60% in group 1 and 44% in group 2. The difference between genders was statistically significant with p value <0.05 in both the groups, although females had higher angulation compared to the males in all classes of both groups. Conclusions In targeted population of Aseer Province, Saudi Arabia, the prevalence of type II soft palate was more common, with higher soft palate angulation among females. The advanced age had no effect in the type of soft palate in the region. PMID:28951740

Effects of compression force on elasticity index and elasticity ratio in ultrasound elastography

PubMed Central

Sasaki, Y; Sakamoto, J; Kamio, T; Nishikawa, K; Otonari-Yamamoto, M; Wako, M

2014-01-01

Objectives: The purpose of this study was to investigate the relationship between compression force and hardness values in ultrasound elastography. Methods: Ultrasound elastography was performed using an elastography phantom, comprising inclusions with different elasticities and echogenicities. The compression force was set to approximately 100 gw (light force) and approximately 500 gw (heavy force). The elasticity index (EI) of the inclusion was measured. The EI was a relative hardness value of a structure within an elastographic image. Similarly, the EI of the background was measured as a reference. The elasticity ratio (ER) was calculated as the EI of the inclusion divided by the EI of the reference. Results: The hardness of the phantom could be discerned with both the EI and ER, regardless of the compression force. The EI and ER with heavy force tended to be higher than those with light force, but the difference was not significant. A strong correlation was observed between the EI and ER of soft structures, whereas the correlation between the EI and ER of hard structures was weak, and the ER values varied widely. Conclusions: The EI offers potential as a good indicator for assessing the hardness. PMID:24592929

Seismic signals hard clipping overcoming

NASA Astrophysics Data System (ADS)

Olszowa, Paula; Sokolowski, Jakub

2018-01-01

In signal processing the clipping is understand as the phenomenon of limiting the signal beyond certain threshold. It is often related to overloading of a sensor. Two particular types of clipping are being recognized: soft and hard. Beyond the limiting value soft clipping reduces the signal real gain while the hard clipping stiffly sets the signal values at the limit. In both cases certain amount of signal information is lost. Obviously if one possess the model which describes the considered signal and the threshold value (which might be slightly more difficult to obtain in the soft clipping case), the attempt of restoring the signal can be made. Commonly it is assumed that the seismic signals take form of an impulse response of some specific system. This may lead to belief that the sine wave may be the most appropriate to fit in the clipping period. However, this should be tested. In this paper the possibility of overcoming the hard clipping in seismic signals originating from a geoseismic station belonging to an underground mine is considered. A set of raw signals will be hard-clipped manually and then couple different functions will be fitted and compared in terms of least squares. The results will be then analysed.

Influence of charged defects on the interfacial bonding strength of tantalum- and silver-doped nanograined TiO2.

PubMed

Azadmanjiri, Jalal; Wang, James; Berndt, Christopher C; Kapoor, Ajay; Zhu, De Ming; Ang, Andrew S M; Srivastava, Vijay K

2017-05-17

A nano-grained layer including line defects was formed on the surface of a Ti alloy (Ti alloy , Ti-6Al-4V ELI). Then, the micro- and nano-grained Ti alloy with the formation of TiO 2 on its top surface was coated with a bioactive Ta layer with or without incorporating an antibacterial agent of Ag that was manufactured by magnetron sputtering. Subsequently, the influence of the charged defects (the defects that can be electrically charged on the surface) on the interfacial bonding strength and hardness of the surface system was studied via an electronic model. Thereby, material systems of (i) Ta coated micro-grained titanium alloy (Ta/MGTi alloy ), (ii) Ta coated nano-grained titanium alloy (Ta/NGTi alloy ), (iii) TaAg coated micro-grained titanium alloy (TaAg/MGTi alloy ) and (iv) TaAg coated nano-grained titanium alloy (TaAg/NGTi alloy ) were formed. X-ray photoelectron spectroscopy was used to probe the electronic structure of the micro- and nano-grained Ti alloy , and so-formed heterostructures. The thin film/substrate interfaces exhibited different satellite peak intensities. The satellite peak intensity may be related to the interfacial bonding strength and hardness of the surface system. The interfacial layer of TaAg/NGTi alloy exhibited the highest satellite intensity and maximum hardness value. The increased bonding strength and hardness in the TaAg/NGTi alloy arises due to the negative core charge of the dislocations and neighbor space charge accumulation, as well as electron accumulation in the created semiconductor phases of larger band gap at the interfacial layer. These two factors generate interfacial polarization and enhance the satellite intensity. Consequently, the interfacial bonding strength and hardness of the surface system are improved by the formation of mixed covalent-ionic bonding structures around the dislocation core area and the interfacial layer. The bonding strength relationship by in situ XPS on the metal/TiO 2 interfacial layer may be examined with other noble metals and applied in diverse fields.

Evaluation of Vickers hardness and depth of cure of six composite resins photo-activated with different polymerization modes.

PubMed

Poggio, C; Lombardini, M; Gaviati, S; Chiesa, M

2012-07-01

The current in vitro study evaluated Vickers hardness (VK) and depth of cure (hardness ratio) of six resin composites, polymerized with a light-emitting diode (LED) curing unit by different polymerization modes: Standard 20 s, Standard 40 s, Soft-start 40 s. SIX RESIN COMPOSITES WERE SELECTED FOR THE PRESENT STUDY: three microhybrid (Esthet.X HD, Amaris, Filtek Silorane), two nanohybrid (Grandio, Ceram.X mono) and one nanofilled (Filtek Supreme XT). The VK of the surface was determined with a microhardness tester using a Vickers diamond indenter and a 200 g load applied for 15 seconds. The mean VK and hardness ratio of the specimens were calculated using the formula: hardness ratio = VK of bottom surface / VK of top surface. For all the materials tested and with all the polymerization modes, hardness ratio was higher than the minimum value indicated in literature in order to consider the bottom surface as adequately cured (0.80). Curing time did not affect hardness ratio values for Filtek Silorane, Grandio and Filtek Supreme XT. The effectiveness of cure at the top and bottom surface was not affected by Soft-start polymerization mode.

Determination of Spatially Resolved Tablet Density and Hardness Using Near-Infrared Chemical Imaging (NIR-CI).

PubMed

Talwar, Sameer; Roopwani, Rahul; Anderson, Carl A; Buckner, Ira S; Drennen, James K

2017-08-01

Near-infrared chemical imaging (NIR-CI) combines spectroscopy with digital imaging, enabling spatially resolved analysis and characterization of pharmaceutical samples. Hardness and relative density are critical quality attributes (CQA) that affect tablet performance. Intra-sample density or hardness variability can reveal deficiencies in formulation design or the tableting process. This study was designed to develop NIR-CI methods to predict spatially resolved tablet density and hardness. The method was implemented using a two-step procedure. First, NIR-CI was used to develop a relative density/solid fraction (SF) prediction method for pure microcrystalline cellulose (MCC) compacts only. A partial least squares (PLS) model for predicting SF was generated by regressing the spectra of certain representative pixels selected from each image against the compact SF. Pixel selection was accomplished with a threshold based on the Euclidean distance from the median tablet spectrum. Second, micro-indentation was performed on the calibration compacts to obtain hardness values. A univariate model was developed by relating the empirical hardness values to the NIR-CI predicted SF at the micro-indented pixel locations: this model generated spatially resolved hardness predictions for the entire tablet surface.

Quantitative evaluation of reduction of plaque-like hard exudates in diabetic macular edema after intravitreal triamcinolone injection.

PubMed

Cekiç, Osman; Bardak, Yavuz; Tiğ, U Sahin; Yildizoğlu, Uzeyir; Bardak, Handan

2008-04-01

To describe a new method of quantifying the amount of plaque-like hard exudates after intravitreal triamcinolone acetonide injection in diabetic macular edema. This study included 22 eyes of 14 patients (mean age, 63 years) with chronic diabetic macular edema and plaque-like hard exudates. The patients were injected with a single dose of 4 mg intravitreal triamcinolone acetonide. The optic disc size as relative size unit was taken to quantify the hard exudates: Total areas of exudates and the optic nerve head were computed from fundus pictures with a digital analysis program on magnified images. The former was divided by the latter, and the results were expressed as a percentage value. The ratio was used to track improvements in a given eye over 6 months. Average ratio of hard exudates to optic nerve head area reduced to 81% of its initial value at 1 month (P=0.007), to 54% at 3 months (P<0.001) and to 41% at 6 months (P<0.001). The new method allowed detection of a significant reduction of ratio of hard exudates to optic disc area of diabetic plaque-like hard exudates following 4 mg intravitreal triamcinolone.

Effect of pH, Surfactant, and Heat Treatment on Morphology, Structure, and Hardness of Electrodeposited Co-P Coatings

NASA Astrophysics Data System (ADS)

Zeinali-Rad, M.; Allahkaram, S. R.; Mahdavi, S.

2015-09-01

Nano-crystalline and amorphous Co-P coatings were deposited on plain carbon steel substrates by using direct current. Effects of electrolyte pH on morphology, current efficiency, phosphorus content, hardness, and preferred orientation of the nano-crystalline coatings were investigated. Moreover, the effects of heat treatment on microstructure and hardness of the nano-crystalline and the amorphous coatings were studied. The results showed that, phosphorus content and hardness of the nano-crystalline coatings were decreased by increasing of the pH, in spite of a current efficiency enhancement to as much as 98%. Grain size and preferred orientation were also changed from 13 to 31 nm and from mostly [002] to [100] by increasing the pH from 1 to 4, respectively. Smoother coatings and higher current efficiencies were obtained by the addition of 1 g/L sodium dodecyl sulfate (SDS) to the bath. Highest hardness of the nano-crystalline and the amorphous coatings was about 600 and 750 HV, which increased and reached 760 and 1090 HV after heat treatment, respectively.

Biodegradable thermoplastic polyurethanes incorporating polyhedral oligosilsesquioxane.

PubMed

Knight, Pamela T; Lee, Kyung Min; Qin, Haihu; Mather, Patrick T

2008-09-01

A new hybrid thermoplastic polyurethane (TPU) system that incorporates an organic, biodegradable poly(D, L-lactide) soft block with a hard block bearing the inorganic polyhedral oligosilsesquioxane (POSS) moiety is introduced and studied. Changes in the polyol composition made through variation of the hydrophilic initiator molecular weight show direct control of the final transition temperatures. Incorporating POSS into the hard segments allows for excellent elasticity above T(g), as evidenced with dynamic mechanical analysis, not seen in most other biodegradable materials. This elasticity is attributed to physical cross-links formed in the hard block through POSS crystallization, as revealed with wide-angle X-ray diffraction. Increasing the POSS incorporation level in the TPU hard block was observed to increase crystallinity and also the rigidity of the material. The highest incorporation, using a statistical average of three POSS units per hard block, demonstrated one-way shape memory with excellent shape fixing capabilities. In vitro degradation of this sample was also investigated during a two month period. Moderate water uptake and dramatic molecular weight decrease were immediately observed although large mass loss (approximately 20 wt %) was not observed until the two month time point.

Investigation of pouring temperature and holding time for semisolid metal feedstock production

NASA Astrophysics Data System (ADS)

Razak, N. A.; Ahmad, A. H.; Rashidi, M. M.

2017-10-01

Semisolid metal (SSM) processing, as a kind of new technology that exploits forming of alloys between solidus and liquidus temperatures, has attracted great attention from investigators for its thixotropic behaviour as well as having advantages in reducing porosity, macrosegregation, and forming forces during shaping process. Various techniques are employed to produce feedstock with fine globular microstructures, and direct thermal method is one of them. In this paper, the effect from different pouring temperatures and holding times using a direct thermal method on microstructure and hardness of aluminium alloy 6061 is presented. Molten aluminium alloy 6061 was poured into a cylindrical copper mould and cooled down to the semisolid temperature before being quenched in water at room temperature. The effect of different pouring temperatures of 660 °C, 680 °C, 700 °C, and holding time of 20 s, and 60 s on the microstructure of aluminium alloy 6061 were investigated. From the micrographs, it was found that the most globular structures were achieved at processing parameters of 660 °C pouring temperature and 60 s holding time. The highest density and hardness of the samples were found at the same processing parameters. It can be concluded that the most spheroidal microstructure, the highest density, and the hardness were recorded at lower pouring temperature and longer holding time.

Prevalence, intensity and population dynamics of hard ticks (Acari: Ixodidae) on sheep in the humid tropics of Mexico.

PubMed

Coronel-Benedett, Karen C; Ojeda-Robertos, Nadia Florencia; González-Garduño, Roberto; Ibañez, Francisco Martínez; Rodríguez-Vivas, Roger Iván

2018-01-01

Hard ticks are a perennial problem in livestock systems throughout Mexico. No data are currently available on tick prevalence, infestation intensity and population dynamics for sheep in the humid tropics of Mexico. Blackbelly sheep (n = 30) in Tabasco state, Mexico, were examined every 3 weeks for 1 year, and all Ixodidae ticks were counted and removed for analysis. Tick species were identified, infestation prevalence and intensity calculated per animal, and infestation per body zone determined. Overall infestation on the studied animals was 51.9%. Four tick species were identified (Amblyomma mixtum, A. imitator, Rhipicephalus microplus and R. annulatus), the most abundant being A. mixtum (94.9%). Prevalence was highest during the northwinds season (61.9%), followed by the dry (48.5%) and rainy (47.3%) seasons; however, the intensity (2.01-2.07 ticks/sheep) did not differ between seasons. Infestation was most frequent in certain zones including the axilla, crotch, udder, abdomen, thorax and rib area. Sheep in the humid tropics of Tabasco, Mexico, are parasitized by four hard tick species and prevalence is highest in the northwinds season. The present data constitute an important baseline for developing sustainable tick control programs for sheep in the humid tropics of Mexico.

First-principles study on the structure, elastic properties, hardness and electronic structure of TMB4 (TM=Cr, Re, Ru and Os) compounds

NASA Astrophysics Data System (ADS)

Pan, Y.; Zheng, W. T.; Guan, W. M.; Zhang, K. H.; Fan, X. F.

2013-11-01

The structural formation, elastic properties, hardness and electronic structure of TMB4 (TM=Cr, Re, Ru and Os) compounds are investigated using first-principles approach. The value of C22 for these compounds is almost two times bigger than the C11 and C33. The intrinsic hardness, shear modulus and Young's modulus are calculated to be in a sequence of CrB4>ReB4>RuB4>OsB4, and the Poisson's ratio and B/G ratio of TMB4 follow the order of CrB4

Improvement of Quench Factor Analysis in Phase and Hardness Prediction of a Quenched Steel

NASA Astrophysics Data System (ADS)

Kianezhad, M.; Sajjadi, S. A.

2013-05-01

The accurate prediction of alloys' properties introduced by heat treatment has been considered by many researchers. The advantages of such predictions are reduction of test trails and materials' consumption as well as time and energy saving. One of the most important methods to predict hardness in quenched steel parts is Quench Factor Analysis (QFA). Classical QFA is based on the Johnson-Mehl-Avrami-Kolmogorov (JMAK) equation. In this study, a modified form of the QFA based on the work by Rometsch et al. is compared with the classical QFA, and they are applied to prediction of hardness of steels. For this purpose, samples of CK60 steel were utilized as raw material. They were austenitized at 1103 K (830 °C). After quenching in different environments, they were cut and their hardness was determined. In addition, the hardness values of the samples were fitted using the classical and modified equations for the quench factor analysis and the results were compared. Results showed a significant improvement in fitted values of the hardness and proved the higher efficiency of the new method.

Investigation of mechanical properties of modern dental composites after artificial aging for one year.

PubMed

Hahnel, Sebastian; Henrich, Anne; Bürgers, Ralf; Handel, Gerhard; Rosentritt, Martin

2010-01-01

This in vitro study investigated the aging behavior of dental composites with regard to surface roughness (SR), Vickers hardness (VH) and flexural strength (FS), and the study elucidated the impact of artificial aging parameters. One hundred and sixty-five rectangular specimens were prepared from five composites (Filtek Supreme XT, Filtek Silorane, CeramX, Quixfil, experimental ormocer) and subjected to various artificial aging protocols (storage in distilled water/ethanol/artificial saliva for 7, 90 and 365 days; thermal cycling, 2 x 3000 cycles 5/55 degrees C). SR, VH and FS were determined at baseline and after each aging treatment. Means and standard deviations were calculated; statistical analysis was performed using three-way ANOVA and the Tukey-Kramer multiple comparison test (alpha=.05). The results showed a significant influence in the composite and aging duration on mechanical parameters; the aging medium did not have a significant influence on VH and FS, but there was a significant influence on SR. The highest overall VH was found for theexperimental ormocer; Filtek Silorane yielded the lowest values. For FS, the significantly highest values were found for Filtek Silorane, and the lowest values were found for the experimental ormocer. Prolonged aging periods (90 or 365 days) or thermal cycling led to significant decreases in both VH and FS and significant increases in SR. The findings of the current study indicate that composites differ significantly for SR and its mechanical properties with regard to FS and VH, as well as in aging behavior. Generally, artificial aging leads to a significant decrease in mechanical properties, which underlines the relevance of continuous improvement of dental composites.

Evaluation of glass transition temperature and dynamic mechanical properties of autopolymerized hard direct denture reline resins.

PubMed

Takase, Kazuma; Watanabe, Ikuya; Kurogi, Tadafumi; Murata, Hiroshi

2015-01-01

This study assessed methods for evaluation of glass transition temperature (Tg) of autopolymerized hard direct denture reline resins using dynamic mechanical analysis and differential scanning calorimetry in addition to the dynamic mechanical properties. The Tg values of 3 different reline resins were determined using a dynamic viscoelastometer and differential scanning calorimeter, and rheological parameters were also determined. Although all materials exhibited higher storage modulus and loss modulus values, and a lower loss tangent at 37˚C with a higher frequency, the frequency dependence was not large. Tg values obtained by dynamic mechanical analysis were higher than those by differential scanning calorimetry and higher frequency led to higher Tg, while more stable Tg values were also obtained by that method. These results suggest that dynamic mechanical analysis is more advantageous for characterization of autopolymerized hard direct denture reline resins than differential scanning calorimetry.

A multiresolution approach for the convergence acceleration of multivariate curve resolution methods.

PubMed

Sawall, Mathias; Kubis, Christoph; Börner, Armin; Selent, Detlef; Neymeyr, Klaus

2015-09-03

Modern computerized spectroscopic instrumentation can result in high volumes of spectroscopic data. Such accurate measurements rise special computational challenges for multivariate curve resolution techniques since pure component factorizations are often solved via constrained minimization problems. The computational costs for these calculations rapidly grow with an increased time or frequency resolution of the spectral measurements. The key idea of this paper is to define for the given high-dimensional spectroscopic data a sequence of coarsened subproblems with reduced resolutions. The multiresolution algorithm first computes a pure component factorization for the coarsest problem with the lowest resolution. Then the factorization results are used as initial values for the next problem with a higher resolution. Good initial values result in a fast solution on the next refined level. This procedure is repeated and finally a factorization is determined for the highest level of resolution. The described multiresolution approach allows a considerable convergence acceleration. The computational procedure is analyzed and is tested for experimental spectroscopic data from the rhodium-catalyzed hydroformylation together with various soft and hard models. Copyright © 2015 Elsevier B.V. All rights reserved.

Color, sensory and textural attributes of beef frankfurter, beef ham and meat-free sausage containing tomato pomace.

PubMed

Savadkoohi, Sobhan; Hoogenkamp, Henk; Shamsi, Kambiz; Farahnaky, Asgar

2014-08-01

The present investigation focuses on the textural properties, sensory attributes and color changes of beef frankfurter, beef ham and meat-free sausage produced by different levels of bleached tomato pomace. The texture and color profile were performed using an instrumental texture analyzer and colorimeter. The findings indicated that tomato pomace-added sausages had higher water holding capacity (WHC) compared to that of commercial samples. The frankfurters containing 5 and 7% (w/w) tomato pomace had the highest redness (a*), chroma (C*) and color differences (ΔE) values, while the meat-free sausages containing 7% (w/w) tomato pomace had significant (p<0.05) values for lightness (L*) and yellowness (b*). Furthermore, there were no significant (p>0.05) color differences between beef ham samples (with and without tomato pomace). A significant progression in the textural hardness and chewiness of systems containing tomato pomace was observed as well as higher sensory scores by panelists. According to sensorial evaluations, bleached tomato pomace improved the consumer acceptability and preference. Copyright © 2014 Elsevier Ltd. All rights reserved.

Formulation of dark chocolate as a carrier to deliver eicosapentaenoic and docosahexaenoic acids: Effects on product quality.

PubMed

Toker, Omer Said; Konar, Nevzat; Palabiyik, Ibrahim; Rasouli Pirouzian, Haniyeh; Oba, Sirin; Polat, Derya Genc; Poyrazoglu, Ender Sinan; Sagdic, Osman

2018-07-15

In this study, dark chocolate enriched with EPA (eicosapentaenoic acid) and DHA (docosahexaenoic acid) was developed using various forms and origins. Quality characteristics such as physical, thermo-gravimetric, rheological, textural and sensory properties of chocolates were investigated. The highest EPA/DHA stability was determined in samples prepared by free-flowing powder and microencapsulated forms of omega-3 fatty acids (FA). The L ∗ and C ∗ values varied from 32.16-33.37 and 7.45-8.09, respectively for the all samples. Hardness values ranged between 6422 and 8367 N and the use of EPA/DHA in the triglyceride form caused softer chocolate whereas control sample was the hardest sample. Melting and rheological properties were not significantly affected by the studied EPA/DHA sources (P < 0.05). Microencapsulated EPA/DHA added chocolate was the most preferred source whereas sample with algae oil showed the lowest acceptability. According to the results, dark chocolate can be used for delivering omega-3 FA by considering their origin and physical form. Copyright © 2018 Elsevier Ltd. All rights reserved.

A Modified Theoretical Model of Intrinsic Hardness of Crystalline Solids

PubMed Central

Dai, Fu-Zhi; Zhou, Yanchun

2016-01-01

Super-hard materials have been extensively investigated due to their practical importance in numerous industrial applications. To stimulate the design and exploration of new super-hard materials, microscopic models that elucidate the fundamental factors controlling hardness are desirable. The present work modified the theoretical model of intrinsic hardness proposed by Gao. In the modification, we emphasize the critical role of appropriately decomposing a crystal to pseudo-binary crystals, which should be carried out based on the valence electron population of each bond. After modification, the model becomes self-consistent and predicts well the hardness values of many crystals, including crystals composed of complex chemical bonds. The modified model provides fundamental insights into the nature of hardness, which can facilitate the quest for intrinsic super-hard materials. PMID:27604165

Deformation Microstructures Near Vickers Indentations in SNO2/SI Coated Systems

NASA Astrophysics Data System (ADS)

Daria, G.; Evghenii, H.; Olga, S.; Zinaida, D.; Iana, M.; Victor, Z.

The micromechanical properties (hardness and brittleness) of the hard-on-hard SnO2 / Si-coated system (CS) and their modification depending the on load value has been studied. A nonmonotonic changing of microhardness with load growth was detected. The brittle/plastic behavior of the rigid/hard-on-hard SnO2 / Si CS and its response to concentrated load action explains it.A specific evolution of the indentation-deformed zone vs. load value attributed to the change in the internal stress redistribution between film and substrate was detected. It results in a brittleness indentation size effect (BISE) of the SnO2 / Si CS revealed in this experiment.It was shown that the greater portion of internal stresses under indentation is concentrated in the coating layer at small loads. This fact causes a strong elastic-plastic relaxation in the film and its delamination from substrate. The increase of brittle failure in the indentation-deformed zone with a decrease of indentation load was revealed.

Comparison of hardness variation of ion irradiated borosilicate glasses with different projected ranges

NASA Astrophysics Data System (ADS)

Sun, M. L.; Peng, H. B.; Duan, B. H.; Liu, F. F.; Du, X.; Yuan, W.; Zhang, B. T.; Zhang, X. Y.; Wang, T. S.

2018-03-01

Borosilicate glass has potential application for vitrification of high-level radioactive waste, which attracts extensive interest in studying its radiation durability. In this study, sodium borosilicate glass samples were irradiated with 4 MeV Kr17+ ion, 5 MeV Xe26+ ion and 0.3 MeV P+ ion, respectively. The hardness of irradiated borosilicate glass samples was measured with nanoindentation in continuous stiffness mode and quasi continuous stiffness mode, separately. Extrapolation method, mean value method, squared extrapolation method and selected point method are used to obtain hardness of irradiated glass and a comparison among these four methods is conducted. The extrapolation method is suggested to analyze the hardness of ion irradiated glass. With increasing irradiation dose, the values of hardness for samples irradiated with Kr, Xe and P ions dropped and then saturated at 0.02 dpa. Besides, both the maximum variations and decay constants for three kinds of ions with different energies are similar indicates the similarity behind the hardness variation in glasses after irradiation. Furthermore, the hardness variation of low energy P ion irradiated samples whose range is much smaller than those of high energy Kr and Xe ions, has the same trend as that of Kr and Xe ions. It suggested that electronic energy loss did not play a significant role in hardness decrease for irradiation of low energy ions.

Evaluation of human muscle hardness after dynamic exercise with ultrasound real-time tissue elastography: a feasibility study.

PubMed

Yanagisawa, O; Niitsu, M; Kurihara, T; Fukubayashi, T

2011-09-01

To assess the feasibility of ultrasound real-time tissue elastography (RTE) for measuring exercise-induced changes in muscle hardness and to compare the findings of RTE with those of a tissue hardness meter for semi-quantitative assessment of the hardness of exercised muscles. Nine male participants performed an arm-curl exercise. RTE measurements were performed by manually applying repetitive compression with the transducer on the scan position before exercise, immediately after exercise, and at 30 min after exercise; strain ratios between muscle and a reference material (hydrogel) were calculated (muscle strain/material strain). A tissue hardness meter was also used to evaluate muscle hardness. The intraclass correlation coefficients (ICCs) for the three repeated measurements at each measurement time were calculated to evaluate the intra-observer reproducibility of each technique. Immediately after exercise, the strain ratio and the value obtained using the tissue hardness meter significantly decreased (from 1.65 to 1.35) and increased (from 51.8 to 54.3), respectively. Both parameters returned to their pre-exercise value 30 min after exercise. The ICCs of the RTE (and the ICCs of the muscle hardness meter) were 0.971 (0.816) before exercise, 0.939 (0.776) immediately after exercise, and 0.959 (0.882) at 30 min after exercise. Similar to the muscle hardness meter, RTE revealed the exercise-induced changes of muscle hardness semi-quantitatively. The intra-observer reproducibility of RTE was very high at each measurement time. These findings suggest that RTE is a clinically useful technique for assessing hardness of specific exercised muscles. Copyright © 2011 The Royal College of Radiologists. Published by Elsevier Ltd. All rights reserved.

Development of Polyethylene Glycol and Hard Fat-Based Mucoadhesive Tablets Containing Various Types of Polyvinyl Alcohols as Mucoadhesive Polymers for Buccal Application.

PubMed

Ikeuchi-Takahashi, Yuri; Kobayashi, Ayaka; Onishi, Hiraku

2017-06-01

Topical drug application has the advantage of avoiding systemic side effects. We attempted to develop a long-acting matrix-type tablet containing indomethacin (IM) with low physical stimulus and potent mucoadhesive force to treat pain caused by oral aphtha. A mixture of polyethylene glycol (PEG) and hard fat was used as the tablet base. Ethylcellulose was added to the base in an attempt to control drug release. Tablets with PEG as a base were also prepared for comparison. Polyvinyl alcohols (PVAs) with various degrees of saponification were added to increase the mucoadhesive force. From the optical microscopic observations, formulations using PEG and hard fat exhibit PEG/hard fat dispersions caused by the stabilizing effects of PVA. Although the tablets using PEG and hard fat showed sufficient adhesiveness and sustained drug release, those using PEG as the base did not. Drug release was controlled by the amount of hard fat and the saponification degree of PVA. The drug release rate was most increased in a tablet containing PVA with an intermediate degree of saponification, PEG and hard fat. From differential scanning calorimetry and powder X-ray diffraction, IM was considered to exist in the molecular phase. From the results of buccal administration of tablets to rats, highest tissue concentrations were observed in the tablet containing PVA with the intermediate degree of saponification using PEG and hard fat, and the plasma concentrations were sufficiently low in comparison.

Executing application function calls in response to an interrupt

DOEpatents

Almasi, Gheorghe; Archer, Charles J.; Giampapa, Mark E.; Gooding, Thomas M.; Heidelberger, Philip; Parker, Jeffrey J.

2010-05-11

Executing application function calls in response to an interrupt including creating a thread; receiving an interrupt having an interrupt type; determining whether a value of a semaphore represents that interrupts are disabled; if the value of the semaphore represents that interrupts are not disabled: calling, by the thread, one or more preconfigured functions in dependence upon the interrupt type of the interrupt; yielding the thread; and if the value of the semaphore represents that interrupts are disabled: setting the value of the semaphore to represent to a kernel that interrupts are hard-disabled; and hard-disabling interrupts at the kernel.

The influence of topical application of grapeseed extract gel on enamel surface hardness after demineralization

NASA Astrophysics Data System (ADS)

Saragih, D. A.; Herda, E.; Triaminingsih, S.

2017-08-01

The aim of this study was to analyze the influence of topical application of 6.5% and 12.5% grapeseed extract gels for duration of application 16 and 32 minutes on the enamel surface hardness following tooth demineralization by an energy drink. The samples were 21 bovine teeth that underwent demineralization by immersion in the energy drink for 5 minutes in an incubator at 37°C. The demineralized specimens were randomly divided into a control group and 2 treatment groups. The control group was immersed in artificial saliva for 6 hours at 37°C, whereas the treatment groups were treated with topical 6.5% and 12.5% grapeseed extract gels for durations of 16 and 32 minutes and then immersed in artificial saliva for 6 hours at 37°C. The hardness was measured with a Knoop hardness tester. Statistical analysis by repeated ANOVA and one-way ANOVA revealed a significant increase in the enamel hardness value (p<0.05) after the application of the topical grapeseed extract gels at both concentrations. Application of 12.5% topical grapeseed extract gel for 32 minutes resulted in a restored hardness that insignificant diffrence from the initial hardness value obtained before demineralization (p>0.05).

Cadmium risks to freshwater life: derivation and validation of low-effect criteria values using laboratory and field studies

USGS Publications Warehouse

Mebane, Christopher A.

2006-01-01

In 2001, the U.S. Environmental Protection Agency (EPA) released updated aquatic life criteria for cadmium. Since then, additional data on the effects of cadmium to aquatic life have become available from studies supported by the EPA, Idaho Department of Environmental Quality (IDEQ), and the U.S. Geological Survey, among other sources. Updated data on the effects of cadmium to aquatic life were compiled and reviewed and low-effect concentrations were estimated. Low-effect values were calculated using EPA's guidelines for deriving numerical national water-quality criteria for the protection of aquatic organisms and their uses. Data on the short-term (acute) effects of cadmium on North American freshwater species that were suitable for criteria derivation were located for 69 species representing 57 genera and 33 families. For longer-term (chronic) effects of cadmium on North American freshwater species, suitable data were located for 28 species representing 21 genera and 17 families. Both the acute and chronic toxicity of cadmium were dependent on the hardness of the test water. Hardness-toxicity regressions were developed for both acute and chronic datasets so that effects data from different tests could be adjusted to a common water hardness. Hardness-adjusted effects values were pooled to obtain species and genus mean acute and chronic values, which then were ranked by their sensitivity to cadmium. The four most sensitive genera to acute exposures were, in order of increasing cadmium resistance, Oncorhynchus (Pacific trout and salmon), Salvelinus ('char' trout), Salmo (Atlantic trout and salmon), and Cottus (sculpin). The four most sensitive genera to chronic exposures were Hyalella (amphipod), Cottus, Gammarus (amphipod), and Salvelinus. Using the updated datasets, hardness dependent criteria equations were calculated for acute and chronic exposures to cadmium. At a hardness of 50 mg/L as calcium carbonate, the criterion maximum concentration (CMC, or 'acute' criterion) was calculated as 0.75 mug/L cadmium using the hardness-dependent equation CMC = e(0.8403 ? ln(hardness)-3.572) where the 'ln hardness' is the natural logarithm of the water hardness. Likewise, the criterion continuous concentration (CCC, or 'chronic' criterion) was calculated as 0.37 mug/L cadmium using the hardness-dependent equation CCC = (e(0.6247 ? ln(hardness)-3.384)) ? (1.101672 - ((ln hardness) ? 0.041838))). Using data that were independent of those used to derive the criteria, the criteria concentrations were evaluated to estimate whether adverse effects were expected to the biological integrity of natural waters or to selected species listed as threatened or endangered. One species was identified that would not be fully protected by the derived CCC, the amphipod Hyalella azteca. Exposure to CCC conditions likely would lead to population decreases in Hyalella azteca, the food web consequences of which probably would be slight if macroinvertebrate communities were otherwise diverse. Some data also suggested adverse behavioral changes are possible in fish following long-term exposures to low levels of cadmium, particularly in char (genus Salvelinus). Although ambiguous, these data indicate a need to periodically review the literature on behavioral changes in fish following metals exposure as more information becomes available. Most data reviewed indicated that criteria conditions were unlikely to contribute to overt adverse effects to either biological integrity or listed species. If elevated cadmium concentrations that approach the chronic criterion values occur in ambient waters, careful biological monitoring of invertebrate and fish assemblages would be prudent to validate the prediction that the assemblages would not be adversely affected by cadmium at criterion concentrations.

Effect of simulated chairside grinding procedures using commercially available abrasive agents on the surface properties of zirconia.

PubMed

Sandhu, Ramandeep; Kheur, Mohit; Kheur, Supriya

2017-01-01

The aim of the present study was to assess the change in physical properties (surface roughness, surface hardness and phase transformation) after surface grinding of zirconia by using three commercially available abrasives. Thirty sintered zirconia specimens were prepared and divided into three groups namely Group M (grinded using Mani Dia diamond bur standard grit), Group T (grinded using Tri Hawk diamond bur coarse grit) and Group P (grinded using Predator carbide bur). A customised assembly was used to follow a standardised protocol for surface grinding. The surface roughness, surface hardness and phase transformation was recorded before and after the grinding procedure. ANOVA and Bonferroni post hoc test were used to assess the values obtained after the testing the surface roughness and surface hardness. The results of the present study revealed the average values of change in surface roughness as Group M (0.44 μ m) and Group T (1.235 μ m) and Group P (-0.88 μ m). The average values of change in surface hardness were Group T (19.578 HV), Group M (46.722 HV) and Group P (36.429 HV). The change in surface hardness was not statistically significant. There was no phase transformation seen after the grinding procedure. Carbide burs along with copious water irrigation when used to grind zirconia intra-orally produces has a polishing effect, minimal change in hardness & no phase transformation. The present study advocates the use of carbides for chair-side grinding of zirconia.

Theoretical model of hardness anisotropy in brittle materials

NASA Astrophysics Data System (ADS)

Gao, Faming

2012-07-01

Anisotropy is prominent in the hardness test of single crystals. However, the anisotropic nature is not demonstrated quantitatively in previous hardness model. In this work, it is found that the electron transition energy per unit volume in the glide region and the orientation of glide region play critical roles in determining hardness value and hardness anisotropy for a single crystal material. We express the mathematical definition of hardness anisotropy through simple algebraic relations. The calculated Knoop hardnesses of the single crystals are in good agreement with observations. This theory, extended to polycrystalline materials by including hall-petch effect and quantum size effect, predicts that the polycrystalline diamond with low angle grain boundaries can be harder than single-crystal bulk diamond. Combining first-principles technique and the formula of hardness anisotropy the hardness of monoclinic M-carbon, orthorhombic W-carbon, Z-carbon, and T-carbon are predicted.

Impact of the hard-coded parameters on the hydrologic fluxes of the land surface model Noah-MP

NASA Astrophysics Data System (ADS)

Cuntz, Matthias; Mai, Juliane; Samaniego, Luis; Clark, Martyn; Wulfmeyer, Volker; Attinger, Sabine; Thober, Stephan

2016-04-01

Land surface models incorporate a large number of processes, described by physical, chemical and empirical equations. The process descriptions contain a number of parameters that can be soil or plant type dependent and are typically read from tabulated input files. Land surface models may have, however, process descriptions that contain fixed, hard-coded numbers in the computer code, which are not identified as model parameters. Here we searched for hard-coded parameters in the computer code of the land surface model Noah with multiple process options (Noah-MP) to assess the importance of the fixed values on restricting the model's agility during parameter estimation. We found 139 hard-coded values in all Noah-MP process options, which are mostly spatially constant values. This is in addition to the 71 standard parameters of Noah-MP, which mostly get distributed spatially by given vegetation and soil input maps. We performed a Sobol' global sensitivity analysis of Noah-MP to variations of the standard and hard-coded parameters for a specific set of process options. 42 standard parameters and 75 hard-coded parameters were active with the chosen process options. The sensitivities of the hydrologic output fluxes latent heat and total runoff as well as their component fluxes were evaluated. These sensitivities were evaluated at twelve catchments of the Eastern United States with very different hydro-meteorological regimes. Noah-MP's hydrologic output fluxes are sensitive to two thirds of its standard parameters. The most sensitive parameter is, however, a hard-coded value in the formulation of soil surface resistance for evaporation, which proved to be oversensitive in other land surface models as well. Surface runoff is sensitive to almost all hard-coded parameters of the snow processes and the meteorological inputs. These parameter sensitivities diminish in total runoff. Assessing these parameters in model calibration would require detailed snow observations or the calculation of hydrologic signatures of the runoff data. Latent heat and total runoff exhibit very similar sensitivities towards standard and hard-coded parameters in Noah-MP because of their tight coupling via the water balance. It should therefore be comparable to calibrate Noah-MP either against latent heat observations or against river runoff data. Latent heat and total runoff are sensitive to both, plant and soil parameters. Calibrating only a parameter sub-set of only soil parameters, for example, thus limits the ability to derive realistic model parameters. It is thus recommended to include the most sensitive hard-coded model parameters that were exposed in this study when calibrating Noah-MP.

Architectural impact of FDDI network on scheduling hard real-time traffic

NASA Technical Reports Server (NTRS)

Agrawal, Gopal; Chen, Baio; Zhao, Wei; Davari, Sadegh

1991-01-01

The architectural impact on guaranteeing synchronous message deadlines in FDDI (Fiber Distributed Data Interface) token ring networks is examined. The FDDI network does not have facility to support (global) priority arbitration which is a useful facility for scheduling hard real time activities. As a result, it was found that the worst case utilization of synchronous traffic in an FDDI network can be far less than that in a centralized single processor system. Nevertheless, it is proposed and analyzed that a scheduling method can guarantee deadlines of synchronous messages having traffic utilization up to 33 pct., the highest to date.

Usefulness of the left ventricular myocardial contraction fraction in healthy men and women to predict cardiovascular morbidity and mortality.

PubMed

Chuang, Michael L; Gona, Philimon; Salton, Carol J; Yeon, Susan B; Kissinger, Kraig V; Blease, Susan J; Levy, Daniel; O'Donnell, Christopher J; Manning, Warren J

2012-05-15

We sought to determine whether depressed myocardial contraction fraction (MCF; ratio of left ventricular [LV] stroke volume to myocardial volume) predicts cardiovascular disease (CVD) events in initially healthy adults. A subset (n = 318, 60 ± 9 years old, 158 men) of the Framingham Heart Study Offspring cohort free of clinical CVD underwent volumetric cardiovascular magnetic resonance imaging in 1998 through 1999. LV ejection fraction (EF), mass, and MCF were determined. "Hard" CVD events consisted of cardiovascular death, myocardial infarction, stroke, or new heart failure. A Cox proportional hazards model adjusting for Framingham Coronary Risk Score was used to estimate hazard ratios for incident hard CVD events for gender-specific quartiles of MCF, LV mass, and LVEF. The lowest quartile of LV mass and highest quartiles of MCF and EF served as referents. Kaplan-Meier survival plots and log-rank test were used to compare event-free survival. MCF was greater in women (0.58 ± 0.13) than in men (0.52 ± 0.11, p <0.01). Nearly all participants (99%) had EF ≥0.55. During an up to 9-year follow-up (median 5.2), 31 participants (10%) developed an incident hard CVD event. Lowest-quartile MCF was 7 times more likely to develop a hard CVD (hazard ratio 7.11, p = 0.010) compared to the remaining quartiles, and increased hazards persisted even after adjustment for LV mass (hazard ratio 6.09, p = 0.020). The highest-quartile LV mass/height 2.7 had a nearly fivefold risk (hazard ratio 4.68, p = 0.016). Event-free survival was shorter in lowest-quartile MCF (p = 0.0006) but not in lowest-quartile LVEF. In conclusion, in a cohort of adults initially without clinical CVD, lowest-quartile MCF conferred an increased hazard for hard CVD events after adjustment for traditional CVD risk factors and LV mass. Copyright © 2012 Elsevier Inc. All rights reserved.

γ' Precipitation Study of a Co-Ni-Based Alloy

NASA Astrophysics Data System (ADS)

Locq, D.; Martin, M.; Ramusat, C.; Fossard, F.; Perrut, M.

2018-05-01

A Co-Ni-based alloy strengthened by γ'-(L12) precipitates was utilized to investigate the precipitation evolution after various cooling rates and several aging conditions. In this study, the precipitate size and volume fraction have been studied via scanning electron microscopy and transmission electron microscopy. The influence of the precipitation evolution was measured via microhardness tests. The cooling rate study shows a more sluggish γ' precipitation reaction compared to that observed in a Ni-based superalloy. Following a rapid cooling rate, the application of appropriate double aging treatments allows for the increase of the γ' volume fraction as well as the control of the size and distribution of the precipitates. The highest hardness values reach those measured on supersolvus cast and wrought Ni-based superalloys. The observed γ' precipitation behavior should have implications for the production, the heat treatment, the welding, or the additive manufacturing of this new class of high-temperature materials.

Application of dairy proteins as technological and nutritional improvers of calcium-supplemented gluten-free bread.

PubMed

Krupa-Kozak, Urszula; Bączek, Natalia; Rosell, Cristina M

2013-11-14

Effect of dairy proteins on gluten-free dough behavior, and nutritional and technological properties of gluten-free bread was evaluated. Experimental doughs, containing dairy powders, showed low consistency. Obtained gluten-free breads were rich in proteins, and, regarding the energy value delivered by proteins, they could be considered as a source of proteins or high in proteins. Applied dairy proteins affected the technological properties of experimental breads causing a significant (p < 0.05) increase of the specific volume, crust darkening, and crumb lightness, depending on the dairy supplementation level, rather than the protein type. Dairy proteins incorporated at a 12% level, significantly (p < 0.05) decreased the hardness; nevertheless, the highest amount of proteins tested led to the opposite effect. These results indicate that milk proteins tested could be successfully added to gluten-free bread with beneficial effects on technological and nutritional properties.

Application of Dairy Proteins as Technological and Nutritional Improvers of Calcium-Supplemented Gluten-Free Bread

PubMed Central

Krupa-Kozak, Urszula; Bączek, Natalia; Rosell, Cristina M.

2013-01-01

Effect of dairy proteins on gluten-free dough behavior, and nutritional and technological properties of gluten-free bread was evaluated. Experimental doughs, containing dairy powders, showed low consistency. Obtained gluten-free breads were rich in proteins, and, regarding the energy value delivered by proteins, they could be considered as a source of proteins or high in proteins. Applied dairy proteins affected the technological properties of experimental breads causing a significant (p < 0.05) increase of the specific volume, crust darkening, and crumb lightness, depending on the dairy supplementation level, rather than the protein type. Dairy proteins incorporated at a 12% level, significantly (p < 0.05) decreased the hardness; nevertheless, the highest amount of proteins tested led to the opposite effect. These results indicate that milk proteins tested could be successfully added to gluten-free bread with beneficial effects on technological and nutritional properties. PMID:24241213

Physicochemical and organoleptic characteristics of seasoned beef patties with added glutinous rice flour.

PubMed

Yi, Hae Chang; Cho, Hyunnho; Hong, Jae Joon; Ryu, Rae Kyeong; Hwang, Keum Taek; Regenstein, Joe M

2012-12-01

This study was conducted to determine if glutinous rice flour (GRF) could be a functional food additive to potentially replace corn starch (CS), soy protein isolate (SPI) and/or sodium tripolyphosphate (STPP) to improve the physicochemical and organoleptic characteristics of seasoned beef patties. GRF had a lower cook loss among the treatment groups due to an increase in fat and moisture retentions (p<0.05). GRF lowered texture profile values for hardness, gumminess, springiness, and chewiness (p<0.05) of the patties, which are generally beneficial for this product. The beef patties with GRF were juicier and more tender than the control and other treatments (p<0.05). Hedonic scores for juiciness, tenderness and overall acceptability were the highest for the beef patties with 1 and 3% GRFs, suggesting that GRF may be an effective functional ingredient to improve the textural quality of seasoned beef patties. Copyright © 2012 Elsevier Ltd. All rights reserved.

Evaluation of acetylated moth bean starch as a carrier for controlled drug delivery

PubMed Central

Singh, Akhilesh V.; Nath, Lila K.

2012-01-01

The present investigation concerns with the development of controlled release tablets of lamivudine using acetylated moth bean starch. The acetylated starch was synthesized with acetic anhydride in pyridine medium. The acetylated moth bean starch was tested for acute toxicity and drug–excipient compatibility study. The formulations were evaluated for physical characteristics like hardness, friability, % drug content and weight variations. The in vitro release study showed that the optimized formulation exhibited highest correlation (R) value in case of Higuchi kinetic model and the release mechanism study proved that the formulation showed a combination of diffusion and erosion process. There was a significant difference in the pharmacokinetic parameters (Tmax, Cmax, AUC, Vd, T1/2 and MDT) of the optimized formulation as compared to the marketed conventional tablet Lamivir®, which proved controlled release potential of acetylated moth bean starch. PMID:22210486

Tailored Welding Technique for High Strength Al-Cu Alloy for Higher Mechanical Properties

NASA Astrophysics Data System (ADS)

Biradar, N. S.; Raman, R.

AA2014 aluminum alloy, with 4.5% Cu as major alloying element, offers highest strength and hardness values in T6 temper and finds extensive use in aircraft primary structures. However, this alloy is difficult to weld by fusion welding because the dendritic structure formed can affect weld properties seriously. Among the welding processes, AC-TIG technique is largely used for welding. As welded yield strength was in the range of 190-195 MPa, using conventional TIG technique. Welding metallurgy of AA2014 was critically reviewed and factors responsible for lower properties were identified. Square-wave AC TIG with Transverse mechanical arc oscillation (TMAO) was postulated to improve the weld strength. A systematic experimentation using 4 mm thick plates produced YS in the range of 230-240 MPa, has been achieved. Through characterization including optical and SEM/EDX was conducted to validate the metallurgical phenomena attributable to improvement in weld properties.

Mechanical and tribological properties of crystalline aluminum nitride coatings deposited on stainless steel by magnetron sputtering

NASA Astrophysics Data System (ADS)

Choudhary, R. K.; Mishra, S. C.; Mishra, P.; Limaye, P. K.; Singh, K.

2015-11-01

Aluminum nitride (AlN) coating is a potential candidate for addressing the problems of MHD pressure drop, tritium permeation and liquid metal corrosion of the test blanket module of fusion reactor. In this work, AlN coatings were grown on stainless steel by magnetron sputtering. Grazing incidence X-ray diffraction measurement revealed that formation of mixed phase (wurtzite and rock salt) AlN was favored at low discharge power and substrate negative biasing. However, at sufficiently high discharge power and substrate bias, (100) oriented wurtzite AlN was obtained. Secondary ion mass spectroscopy showed presence of oxygen in the coatings. The highest value of hardness and Young's modulus were 14.1 GPa and 215 GPa, respectively. Scratch test showed adhesive failure at a load of about 20 N. Wear test showed improved wear resistance of the coatings obtained at higher substrate bias.

Final report on COOMET Vickers PTB/VNIIFTRI key comparison (COOMET.M.H-K1.b and COOMET.M.H-K1.c)

NASA Astrophysics Data System (ADS)

Aslanyan, E.; Herrmann, K.

2013-01-01

This report describes a COOMET key comparison on Vickers hardness scales of two National Metrology Institutes—PTB and VNIIFTRI. The pilot laboratory was PTB, which was the linking institute with the key comparison reference values of CCM.H-K1. In the key comparison two sets of hardness reference blocks for the Vickers hardness scales HV1 and HV30, each consisting of three hardness reference blocks with the hardness levels 240 HV, 540 HV and 840 HV, are used. The same hardness reference blocks were used previously in the key comparison CCM.H-K1. The measurement results and uncertainty assessments, announced by VNIIFTRI, are in good agreement with the key comparison reference values of CCM.H-K1. Main text. To reach the main text of this paper, click on Final Report. Note that this text is that which appears in Appendix B of the BIPM key comparison database kcdb.bipm.org/. The final report has been peer-reviewed and approved for publication by the CCM, according to the provisions of the CIPM Mutual Recognition Arrangement (CIPM MRA).

Studying hardness, workability and minimum bending radius in selectively laser-sintered Ti–6Al–4V alloy samples

NASA Astrophysics Data System (ADS)

Galkina, N. V.; Nosova, Y. A.; Balyakin, A. V.

2018-03-01

This research is relevant as it tries to improve the mechanical and service performance of the Ti–6Al–4V titanium alloy obtained by selective laser sintering. For that purpose, sintered samples were annealed at 750 and 850°C for an hour. Sintered and annealed samples were tested for hardness, workability and microstructure. It was found that incomplete annealing of selectively laser-sintered Ti–6Al–4V samples results in an insignificant reduction in hardness and ductility. Sintered and incompletely annealed samples had a hardness of 32..33 HRC, which is lower than the value of annealed parts specified in standards. Complete annealing at temperature 850°C reduces the hardness to 25 HRC and ductility by 15...20%. Incomplete annealing lowers the ductility factor from 0.08 to 0.06. Complete annealing lowers that value to 0.025. Complete annealing probably results in the embrittlement of sintered samples, perhaps due to their oxidation and hydrogenation in the air. Optical metallography showed lateral fractures in both sintered and annealed samples, which might be the reason why they had lower hardness and ductility.

Nitrogen soft and hard X-ray emissions using different shapes of anodes in a 4-kJ plasma focus device

DOE Office of Scientific and Technical Information (OSTI.GOV)

Mahtab, M., E-mail: m.mahtab.83@gmail.com; Habibi, M., E-mail: mortezahabibi@aut.ac.ir

2013-12-15

The effect of different anode tip geometries on the intensity of soft and hard X-rays emitted from a 4-kJ plasma focus device is investigated using five different anode tips. The shapes of the uppermost region of these anodes (tips) have been cylindrical-flat, cylindrical-hollow, spherical-convex, cone-flat, and cone-hollow. For time-resolved measurement of the emitted X-rays, several BPX-65 pin diodes covered by different filters and a fast plastic scintillator are used. Experimental results have shown that, the highest intensity of the both soft and hard X-ray is recorded in cone-flat, spherical-convex, and cone-hollow tips, respectively. The use of cone-flat anode tip hasmore » augmented the emitted X-ray three times.« less

Mechanical properties of Mo-Si-B alloys fabricated by using core-shell powder with dispersion of yttria nanoparticles

NASA Astrophysics Data System (ADS)

Byun, Jong Min; Bang, Su-Ryong; Choi, Won June; Kim, Min Sang; Noh, Goo Won; Kim, Young Do

2017-01-01

In recent years, refractory materials with excellent high-temperature properties have been in the spotlight as a next generation's high-temperature materials. Among these, Mo-Si-B alloys composed of two intermetallic compound phases (Mo5SiB2 and Mo3Si) and a ductile α-Mo phase have shown an outstanding thermal properties. However, due to the brittleness of the intermetallic compound phases, Mo-Si-B alloys were restricted to apply for the structural materials. So, to enhance the mechanical properties of Mo-Si-B alloys, many efforts to add rare-earth oxide particles in the Mo-Si-B alloy were performed to induce the improvement of strength and fracture toughness. In this study, to investigate the effect of adding nano-sized Y2O3 particles in Mo-Si-B alloy, a core-shell powder consisting of intermetallic compound phases as the core and nano-sized α-Mo and Y2O3 particles surrounding the core was fabricated. Then pressureless sintering was carried out at 1400 °C for 3 h, and the mechanical properties of sintered bodies with different amounts of Y2O3 particles were evaluated by Vickers hardness and 3-point bending test. Vickers hardness was improved by dispersed Y2O3 particles in the Mo-Si-B alloy. Especially, Mo-3Si-1B-1.5Y2O3 alloy had the highest value, 589 Hv. The fracture toughness was measured using Mo-3Si-1B-1.5Y2O3 alloy and the value indicated as 13.5 MPa·√m.

Stream-Sediment Geochemistry in Mining-Impacted Drainages of the Yankee Fork of the Salmon River, Custer County, Idaho

USGS Publications Warehouse

Frost, Thomas P.; Box, Stephen E.

2009-01-01

This reconnaissance study was undertaken at the request of the USDA Forest Service, Region 4, to assess the geochemistry, in particular the mercury and selenium contents, of mining-impacted sediments in the Yankee Fork of the Salmon River in Custer County Idaho. The Yankee Fork has been the site of hard-rock and placer mining, primarily for gold and silver, starting in the 1880s. Major dredge placer mining from the 1930s to 1950s in the Yankee Fork disturbed about a 10-kilometer reach. Mercury was commonly used in early hard-rock mining and placer operations for amalgamation and recovery of gold. During the late 1970s, feasibility studies were done on cyanide-heap leach recovery of gold from low-grade ores of the Sunbeam and related deposits. In the mid-1990s a major open-pit bulk-vat leach operation was started at the Grouse Creek Mine. This operation shut down when gold values proved to be lower than expected. Mercury in stream sediments in the Yankee Fork ranges from below 0.02 ppm to 7 ppm, with the highest values associated with old mill locations and lode and placer mines. Selenium ranges from below the detection limit for this study of 0.2 ppm to 4 ppm in Yankee Fork sediment samples. The generally elevated selenium content in the sediment samples reflect the generally high selenium contents in the volcanic rocks that underlie the Yankee Fork and the presence of gold and silver selenides in some of the veins that were exploited in the early phases of mining.

Nanoprecipitates and Their Strengthening Behavior in Al-Mg-Si Alloy During the Aging Process

NASA Astrophysics Data System (ADS)

Li, Hui; Liu, Wenqing

2017-04-01

The different nanoprecipitates formed in a 6061 aluminum alloy during aging at 453 K (180 °C), with or without 168 hours of pre-natural aging (NA), and the age-hardening response of the alloy were investigated by atom probe tomography (APT) and hardness testing. A hardness plateau developed between 2 and 8 hours in both the artificial aging (AA) and artificial aging with pre-natural aging (NAAA) samples. The hardness of NAAA samples was lower than that of AA samples when artificially aged for the same time. A 168-hour NA led to the formation of solute atom clusters in the matrix. The NA accelerated the precipitation kinetics of the following AA. The solute atom clusters gave the highest hardness increment per unit volume fraction. The β″ precipitates were dominant in the samples at the hardness plateau. The average normalized Mg:Si ratios of the solute atom clusters and GP zones were near 1. The average Mg:Si ratio of β″ precipitates increased from 1.3 to 1.5 upon aging for 2 hours. The microstructural evolution of samples with or without NA and its influence on the strengthening effects are discussed based on the experimental results.

Synergistic methods for the production of high-strength and low-cost boron carbide

NASA Astrophysics Data System (ADS)

Wiley, Charles Schenck

2011-12-01

Boron carbide (B4C) is a non-oxide ceramic in the same class of nonmetallic hard materials as silicon carbide and diamond. The high hardness, high elastic modulus and low density of B4C make it a nearly ideal material for personnel and vehicular armor. B4C plates formed via hot-pressing are currently issued to U.S. soldiers and have exhibited excellent performance; however, hot-pressed articles contain inherent processing defects and are limited to simple geometries such as low-curvature plates. Recent advances in the pressureless sintering of B4C have produced theoretically-dense and complex-shape articles that also exhibit superior ballistic performance. However, the cost of this material is currently high due to the powder shape, size, and size distribution that are required, which limits the economic feasibility of producing such a product. Additionally, the low fracture toughness of pure boron carbide may have resulted in historically lower transition velocities (the projectile velocity range at which armor begins to fail) than competing silicon carbide ceramics in high-velocity long-rod tungsten penetrator tests. Lower fracture toughness also limits multi-hit protection capability. Consequently, these requirements motivated research into methods for improving the densification and fracture toughness of inexpensive boron carbide composites that could result in the development of a superior armor material that would also be cost-competitive with other high-performance ceramics. The primary objective of this research was to study the effect of titanium and carbon additives on the sintering and mechanical properties of inexpensive B4C powders. The boron carbide powder examined in this study was a sub-micron (0.6 mum median particle size) boron carbide powder produced by H.C. Starck GmbH via a jet milling process. A carbon source in the form of phenolic resin, and titanium additives in the form of 32 nm and 0.9 mum TiO2 powders were selected. Parametric studies of sintering behavior were performed via high-temperature dilatometry in order to measure the in-situ sample contraction and thereby measure the influence of the additives and their amounts on the overall densification rate. Additionally, broad composition and sintering/post-HIPing studies followed by characterization and mechanical testing elucidated the effects of these additives on sample densification, microstructure de- velopment, and mechanical properties such as Vickers hardness and microindentation fracture toughness. Based upon this research, a process has been developed for the sintering of boron carbide that yielded end products with high relative densities (i.e., 100%, or theoretical density), microstructures with a fine (˜2-3 mum) grain size, and high Vickers microindentation hardness values. In addition to possessing these improved physical properties, the costs of producing this material were substantially lower (by a factor of 5 or more) than recently patented work on the pressureless sintering and post-HIPing of phase-pure boron carbide powder. This recently patented work developed out of our laboratory utilized an optimized powder distribution and yielded samples with high relative densities and high hardness values. The current work employed the use of titanium and carbon additives in specific ratios to activate the sintering of boron carbide powder possessing an approximately mono-modal particle size distribution. Upon heating to high temperatures, these additives produced fine-scale TiB2 and graphite inclusions that served to hinder grain growth and substantially improve overall sintered and post-HIPed densities when added in sufficient concentrations. The fine boron carbide grain size manifested as a result of these second phase inclusions caused a substantial increase in hardness; the highest hardness specimen yielded a hardness value (2884.5 kg/mm2) approaching that of phase-pure and theoretically-dense boron carbide (2939 kg/mm2). Additionally, the same high-hardness composition exhibited a noticeably higher fracture toughness (3.04 MPa˙m1/2) compared to phase-pure boron carbide (2.42 MPa˙m1/2), representing a 25.6% improvement. A potential consequence of this study would be the development of a superior armor material that is sufficiently affordable, allowing it to be incorporated into the general soldier's armor chassis.

Effect of inhomogeneity of light from light curing units on the surface hardness of composite resin.

PubMed

Arikawa, Hiroyuki; Kanie, Takahito; Fujii, Koichi; Takahashi, Hideo; Ban, Seiji

2008-01-01

This study investigated the characteristics of output light from different types of light curing units, and their effects on polymerization of light-activated composite resin. Three quartz-tungsten-halogen lamps, one plasma arc lamp, and one LED light curing unit were used. Intensity distribution of light emitted from the light guide tip was measured at 1.0-mm intervals across the guide tip. Distribution of Knoop hardness number on the surface of resin irradiated with the light curing units was also measured. For all units, inhomogeneous distribution of light intensity across the guide tip was observed. Minimum light intensity values were 19-80% of the maximum values. In terms of surface hardness, inhomogeneous distribution was also observed for the materials irradiated with the tested units. Minimum values were 53-92% of the maximum values. Our results indicated that markedly inhomogeneous light emitted from light curing unit could result in inhomogeneous polymerization in some areas of the restoration below the light guide tip.

Effects of Various Kinds of Salt on the Quality and Storage Characteristics of Tteokgalbi

PubMed Central

Lee, Jae-Joon

2014-01-01

This study was carried out to evaluate the effects of various kinds of salt on the quality and storage characteristics of tteokgalbi. The tteokgalbi was prepared using four types of salt: 1.5% purified salt (control, C), 1.5% five-year-old solar salt (FS), 1.5% Topan solar salt (TS), and 1.5% French Guérande solar salt (GS). The moisture, crude lipid, crude ash, crude protein and calorie contents, water holding capacity, and cooking loss were not significantly different between control and all other treatments. As for the textural characteristics, the use of GS increased the hardness of the tteokgalbi. According to the sensory evaluation, the use of TS had the best score in springiness. Tteokgalbi made with TS and GS had the two highest scores in flavor and total acceptability. During 15 d of storage, the contents of 2-thiobarbituric acid (TBA) value, volatile basic nitrogen (VBN) and the total microbial counts increased, while the pH decreased. The TBA values of the tteokgalbi containing TS and GS were lower than that of C. Lightness (L) and yellowness (b) values decreased during storage, but redness (a) displayed no significant difference during storage. Overall, the best results, in terms of TBA value and sensory attributes, were obtained for the tteokgalbi containing TS and GS. PMID:26761494

Comparison between complete denture and implant-retained overdenture: effect of different mucosa thickness and resiliency on stress distribution.

PubMed

Assunção, Wirley Gonçalves; Barão, Valentim Adelino Ricardo; Tabata, Lucas Fernando; de Sousa, Edson Antonio Capello; Gomes, Erica Alves; Delben, Juliana Aparecida

2009-12-01

The effect of different mucosa characteristics on stress distribution of complete dentures and overdentures remains unknown. The aim of this study was to evaluate the effect of different mucosa thickness and resiliency on the stress distribution of complete dentures and implant-retained overdentures using a two-dimensional finite element analysis. Representative models of the edentulous mandible were constructed on AutoCAD software according to the groups' characteristics. In group CD, a model of the edentulous mandible supporting a complete denture was obtained while in group IO, a model of edentulous mandible supporting an overdenture over two unsplinted implants with an o' ring system was constructed. In each group, mucosa assumed three characteristics of thickness (1, 3 and 5 mm) corresponding to the resiliencies hard, resilient and soft respectively. Evaluation was performed on Ansys software with 100N vertical load applied on central incisor teeth. The principal stress was used as analysis criteria. Group IO showed higher stress values than group CD regardless of mucosal thickness and resiliency. Stress decreased at the supporting tissues in both groups as the thickness and resiliency of mucosa increased. In relation to the supporting tissues, cortical bone showed the highest stress values. It was concluded that the use of an attachment system increases stress values and the thickness and resiliency of mucosa influence more on these values.

Effects of Lemon Balm on the Oxidative Stability and the Quality Properties of Hamburger Patties during Refrigerated Storage

PubMed Central

Lee, Hyun-Joo; Choi, Yang-Il

2014-01-01

This study was performed to investigate the effects of lemon balm (Melissa officinalis L.) on various quality and antioxidant activity of hamburger patties. Lemon balm extract (LBE) showed the highest amount of total polyphenol (801.00 mg TAE/g DW) and flavonoids (65.05 mg RA/g DW). The IC50 value of DPPH hydroxyl scavenging of LBE was 132 μg/mL. The hamburger patties were prepared by 0% (N), 0.1% (L1), 0.5% (L2), and 1.0% (L3) of the lemon balm powder. The addition of lemon balm powder increased the chewiness value, but did not affect the hardness, cohesiveness, and springiness values. Lemon balm powder had positive effects on sensory evaluation of patties. The pH of all patties decreased with longer storage period. 2-Thiobarbituric acid value, volatile basic nitrogen content, and the total microbial counts of hamburger patties in the L3 group were lower, compared to those of the normal (N group). In conclusion, the L3 group had significantly delayed lipid peroxidation compared to other treatment groups. However, the addition of lemon balm powder into patties showed no significantly influence on proximate composition, calorie contents, water holding capacity and cooking loss of patties. Therefore, lemon balm might be a useful natural antioxidant additive in meat products. PMID:26761292

Effects of thermal treatment on energy density and hardness of torrefied wood pellets

DOE Office of Scientific and Technical Information (OSTI.GOV)

Peng, Jianghong; Wang, Jingsong; Bi, Xiaotao T.

Here, three types of wood pellets samples, including two types of commercial pellets and one type of lab-made control pellets were torrefied in a fixed bed unit to study the effect of thermal pretreatment on the quality of wood pellets. The quality of wood pellets was mainly characterized by the pellet density, bulk density, higher heating value, Meyer hardness, saturated moisture uptake, volumetric energy density, and energy yield. Results showed that torrefaction significantly decreased the pellet density, hardness, volumetric energy density, and energy yield. The higher heating value increased and the saturated moisture content decreased after torrefaction. In view ofmore » the lower density, lower hardness, lower volumetric energy density, and energy yield of torrefied pellets, it is recommended that biomass should be torrefied and then compressed to make strong pellets of high hydrophobicity and volumetric energy density.« less

Effects of thermal treatment on energy density and hardness of torrefied wood pellets

DOE PAGES

Peng, Jianghong; Wang, Jingsong; Bi, Xiaotao T.; ...

2014-09-27

Here, three types of wood pellets samples, including two types of commercial pellets and one type of lab-made control pellets were torrefied in a fixed bed unit to study the effect of thermal pretreatment on the quality of wood pellets. The quality of wood pellets was mainly characterized by the pellet density, bulk density, higher heating value, Meyer hardness, saturated moisture uptake, volumetric energy density, and energy yield. Results showed that torrefaction significantly decreased the pellet density, hardness, volumetric energy density, and energy yield. The higher heating value increased and the saturated moisture content decreased after torrefaction. In view ofmore » the lower density, lower hardness, lower volumetric energy density, and energy yield of torrefied pellets, it is recommended that biomass should be torrefied and then compressed to make strong pellets of high hydrophobicity and volumetric energy density.« less

A new formulation for orally disintegrating tablets using a suspension spray-coating method.

PubMed

Okuda, Y; Irisawa, Y; Okimoto, K; Osawa, T; Yamashita, S

2009-12-01

The aim of this study was to design a new orally disintegrating tablet (ODT) that has high tablet hardness and a fast oral disintegration rate using a new preparation method. To obtain rapid disintegration granules (RDGs), a saccharide, such as trehalose, mannitol, or lactose, was spray-coated with a suspension of corn starch using a fluidized-bed granulator (suspension method). As an additional disintegrant, crospovidone, light anhydrous silicic acid, or hydroxypropyl starch was also included in the suspension. The RDGs obtained possessed extremely large surface areas, narrow particle size distribution, and numerous micro-pores. When tabletting these RDGs, it was found that the RDGs increased tablet hardness by decreasing plastic deformation and increasing the contact frequency between granules. In all tablets, a linear relationship was observed between tablet hardness and oral disintegration time. From each linear correlation line, a slope (D/H value) and an intercept (D/H(0) value) were calculated. Tablets with small D/H and D/H(0) values could disintegrate immediately in the oral cavity regardless of the tablet hardness and were considered to be appropriate for ODTs. Therefore, these values were used as key parameters to select better ODTs. Of all the RDGs prepared in this study, mannitol spray-coated with a suspension of corn starch and crospovidone (2.5:1 w/w ratio) showed most appropriate properties for ODTs; fast in vivo oral disintegration time, and high tablet hardness. In conclusion, this simple method to prepare superior formulations for new ODTs was established by spray-coating mannitol with a suspension of appropriate disintegrants.

Body temperature rhythm and control of the time of the best physical condition by performing physical labor.

PubMed

Imafuku, Michio

2016-01-01

The initial examination of a male subject's body temperature revealed that it was highest during the evening. Based on this observation, I measured grasping power, calculation speed, performance time on a light sensory task and body temperature, all of which were highest or best during the evening. The time of this subject's best physical condition shifted from the evening to morning hours when the subject executed hard physical labor in the morning, and the shifted phase was maintained after the termination of the labor period.

Influence of design variables on radiation hardness of silicon MINP solar cells

NASA Technical Reports Server (NTRS)

Anderson, W. A.; Solaun, S.; Rao, B. B.; Banerjee, S.

1985-01-01

Metal-insulator-N/P silicon (MINP) solar cells were fabricated using different substrate resistivity values, different N-layer designs, and different I-layer designs. A shallow junction into an 0.3 ohm-cm substrate gave best efficiency whereas a deeper junction into a 1 to 4 ohm-cm substrate gave improved radiation hardness. I-layer design variation did little to influence radiation hardness.

The application of pulse modulated plasma to the plasma enhanced chemical vapor deposition of dielectric materials

NASA Astrophysics Data System (ADS)

Qi, Yu

This dissertation work applied the pulse modulated plasma to the plasma enhanced chemical vapor deposition (PECVD) of two types of dielectric materials: SiO2-like coatings and Teflon-like coatings. SiO2-like coatings were firstly implemented with continuous plasma. It was proven that three different precursors: hexamethyldisiloxane (HMDSO), 1, 3, 5, 7-tetramethylcyclotetrasiloxane (TMCTS) and octamethylcyclotetrasiloxane (OMCTS) can be used to generate hard, clear and high density SiO2 deposition with coupled high growth rate and low processing temperature via PECVD. Under similar conditions, HMDSO has the lowest growth rate, lowest hardness and highest carbon content; TMCTS has the highest growth rate and hardness, and lowest carbon content; and OMCTS has moderate rates of these deposition qualities, but the best corrosion resistance. Substrate bias seems to have no effect on any deposition quality. High chamber pressure can significantly lower the carbon content in the thin films but does not affect any other qualities; the O2/precursor ratio is the most influential factor among all variables considered in this experiment. The deposition hardness and O:Si ratio always increase with this ratio while the carbon content always decreases. However, different precursors require different optimal ratios to achieve the highest growth rate. Pulse modulation was introduced into PECVD of SiO2-like coatings and OMCTS was selected as the precursor. It was demonstrated that pulse frequency, duty ratio and peak power have significant effects on deposition qualities. The proper combination of the pulse parameters and other traditional plasma parameters can significantly lower the processing temperature while retaining or even improving other deposition qualities, such as growth rate, corrosion resistance and elemental composition. Hardness is the only sacrifice of the lower time-average power caused by pulsing. Therefore, pulse modulation can effectively expand the possible range of combinations of desired deposition qualities. Finally, the pulsed plasma was used to implement PECVD of teflon-like coatings. An important discovery in this application is that in addition to pulse period, on-time and on-time peak power, the power level during the off-time is an important factor. The density of CF2 is a function of all these pulse parameters. The best result obtained is up to 67.2% CF2 and a 1.87:1 of F:C ratio when the off-time power level is ˜100--130 W the frequency is several Hz, the on-time peak power is ˜1000 W and the duty ratio is ˜7--10%.

Effects of environment on microhardness of magnesium oxide

NASA Technical Reports Server (NTRS)

Ishigaki, H.; Buckley, D. H.

1982-01-01

Micro-Vickers hardness measurements of magnesium oxide single crystals were conducted in various environments. These environments included air, nitrogen gas, water, mineral oil with or without various additives, and aqueous solutions with various pH values. Indentations were made on the (100) plane with the diagonals of the indentation in the (100) direction. The results indicate that a sulfur containing additve in mineral oil increased hardness, a chlorine containing additive in mineral oil decreased hardness, and aqueous solutions of hydrogen chloride decreased hardness. Other environments were found to have little effect on hardness. Mechanically polished surfaces showed larger indentation creep than did as-cleaved surfaces.

Evaluation of tribological properties of selected engine oils during operation of the friction pairs of steel-on-steel

NASA Astrophysics Data System (ADS)

Barszcz, Marcin; Józwik, Jerzy; Dziedzic, Krzysztof; Stec, Kamil

2017-10-01

The paper includes an assessment of the tribological properties of mineral and synthetic Lotos oil marked SAE 15W/40 and SAE 5W/40 at ambient temperature and 100 °C. The evaluation was based on the analysis of the tribological properties of friction couple consumables. Tribological tests were performed using the Anton Paar THT 1000 high temperature tribotester according to ASTM G133. Tribological properties were investigated using the "ball on disc" method. The change of friction coefficient, friction couple temperature, volume wear of samples and counter-samples and Hertz stresses were evaluated. In addition, hardness tests of the friction couple materials as well as surface roughness before and after friction were performed. On the basis of tribological studies, it was noted that Lotos Synthetic 5W/40 oil has better cooling properties compared. For both oils the coefficient of friction was lower at ambient temperature than at 100 °C. The highest value of volume wear of the sample was noted for the combination lubricated with Mineral Oil 15W/40 at 100 °C (0.0143 mm3) while for counter-sample lubricated with synthetic oil at ambient temperature (0.0039 mm3). The highest sample wear coefficient was recorded for the mineral oil lubricated at temperature of 100 °C (3.585*10-7 mm3/N/m) while for counter-sample lubricated with synthetic oil at ambient temperature (9.8768*10-8 mm3/N/m). The Hertz stress for each test couple had a value of 1.787 GPa.

Identifying factors linked to the occurrence of alien gastropods in isolated woodland water bodies

NASA Astrophysics Data System (ADS)

Spyra, Aneta; Strzelec, Małgorzata

2014-03-01

Biological invasions are a significant component of human-caused global change and is widely regarded as one of the main threats to natural biodiversity. Isolated anthropogenic water bodies created in the areas that are deprived of natural freshwater habitats allow the survival and reproduction of alien species on newly settled sites. They are often small with water level fluctuations causing frequent environmental disturbances. The colonisation success may be the result of the rate of their degradation. The aims of the study were to determine the environmental conditions that affect the existence of alien species of gastropods in this type of aquatic environment and to examine whether the occurrence of non-native species affects the community structure of the native species. This study made it possible to group woodland ponds according to the occurrence of the three invasive species in snail communities and discuss the environmental conditions present in these pond types. Analysis of water properties emphasised the distinctiveness of the selected pond types. In ponds of the Potamopyrgus antipodarum type, we found the highest values of some parameters mainly hardness, conductivity, and content of calcium and chlorides, in contrast with the Physella acuta type, which were characterised by the lowest values except for phosphates and nitrites. In the Ferrissia fragilis type, we found the highest nitrate content. Data on the occurrence of alien species in different water environments play an important role in actions which are taken to prevent new invasions and spread of non-native species as well as to reduce future impacts of invaders.

Identifying factors linked to the occurrence of alien gastropods in isolated woodland water bodies.

PubMed

Spyra, Aneta; Strzelec, Małgorzata

2014-03-01

Biological invasions are a significant component of human-caused global change and is widely regarded as one of the main threats to natural biodiversity. Isolated anthropogenic water bodies created in the areas that are deprived of natural freshwater habitats allow the survival and reproduction of alien species on newly settled sites. They are often small with water level fluctuations causing frequent environmental disturbances. The colonisation success may be the result of the rate of their degradation. The aims of the study were to determine the environmental conditions that affect the existence of alien species of gastropods in this type of aquatic environment and to examine whether the occurrence of non-native species affects the community structure of the native species. This study made it possible to group woodland ponds according to the occurrence of the three invasive species in snail communities and discuss the environmental conditions present in these pond types. Analysis of water properties emphasised the distinctiveness of the selected pond types. In ponds of the Potamopyrgus antipodarum type, we found the highest values of some parameters mainly hardness, conductivity, and content of calcium and chlorides, in contrast with the Physella acuta type, which were characterised by the lowest values except for phosphates and nitrites. In the Ferrissia fragilis type, we found the highest nitrate content. Data on the occurrence of alien species in different water environments play an important role in actions which are taken to prevent new invasions and spread of non-native species as well as to reduce future impacts of invaders.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Nagakubo, A.; Ogi, H., E-mail: ogi@me.es.osaka-u.ac.jp; Hirao, M.

Nano-polycrystalline boron nitride (BN) is expected to replace diamond as a superhard and superstiff material. Although its hardening was reported, its elasticity remains unclear and the as-measured hardness could be significantly different from the true value due to the elastic recovery. In this study, we measured the longitudinal-wave elastic constant of nano-polycrystalline BNs using picosecond ultrasound spectroscopy and confirmed the elastic softening for small-grain BNs. We also measured Vickers and Knoop hardness for the same specimens and clarified the relationship between hardness and stiffness. The Vickers hardness significantly increased as the grain size decreased, while the Knoop hardness remained nearlymore » unchanged. We attribute the apparent increase in Vickers hardness to the elastic recovery and propose a model to support this insight.« less

Manufacture, characterisation and properties of novel fluorcanasite glass-ceramics.

PubMed

Pollington, Sarah; van Noort, Richard

2012-11-01

The aim of this study was to investigate the manufacture and characterisation of different compositions of fluorcanasite glass-ceramics with reduced fluorine content and to assess their mechanical and physical properties. Three compositional variations (S80, S81 and S82) of a fluorcanasite glass were investigated. Differential thermal analysis (DTA) and X-ray diffraction (XRD) identified crystallisation temperatures and phases. X-ray fluorescence (XRF) determined the element composition in the glass-ceramics. Different heat treatments [2 h nucleation and either 2 or 4 h crystallisation] were used for the glasses. Scanning electron microscopy (SEM) examined the microstructure of the cerammed glass. The chemical solubility, biaxial flexural strength, fracture toughness, hardness and brittleness index of S81 and S82 fluorcanasite were investigated with lithium disilicate (e.max CAD, Ivoclar Vivadent) as a commercial comparison. Statistical analysis was performed using one-way ANOVA with Tukey's multiple comparison tests (P<0.05). Weibull analysis was employed to examine the reliability of the strength data. All compositions successfully produced glasses. XRD analysis confirmed fluorcanasite formation with the S81 and S82 compositions, with the S82 (2+2h) showing the most prominent crystal structure. The chemical solubility of the glass-ceramics was significantly different, varying from 2565 ± 507 μg/cm(2) for the S81 (2+2 h) to 722 ± 177 μg/cm(2) for the S82 (2+2 h) to 37.4 ± 25.2 μg/cm(2) for the lithium disilicate. BFS values were highest for the S82 (2+2 h) composition (250 ± 26 MPa) and lithium disilicate (266 ± 37 MPa) glass-ceramics. The fracture toughness was higher for the S82 compositions, with the S82 (2+2h) attaining the highest value of 4.2 ± 0.3 MPa m(1/2)(P=0.01). The S82 (2+2 h) fluorcanasite glass-ceramic had the lowest brittleness index. The S82 (2+2 h) fluorcanasite glass-ceramic has acceptable chemical solubility, high biaxial flexural strength, fracture toughness and hardness. A novel glass-ceramic has been developed with potential as a restorative material. The S82 (2+2 h) has mechanical and physical properties that would allow the glass-ceramic to be used as a machinable core material for veneered resin-bonded ceramic restorations. Copyright © 2012 Elsevier Ltd. All rights reserved.

Oil-structuring characterization of natural waxes in canola oil oleogels: Rheological, thermal, and oxidative properties

USDA-ARS?s Scientific Manuscript database

Natural waxes (candelilla wax, carnauba wax, and beeswax) were utilized as canola oil structurants to produce oleogels and their physicochemical properties were evaluated from rheological, thermal, and oxidative points of view. The oleogels with candelilla wax exhibited the highest hardness, followe...

Effect of simulated chairside grinding procedures using commercially available abrasive agents on the surface properties of zirconia

PubMed Central

Sandhu, Ramandeep; Kheur, Mohit; Kheur, Supriya

2017-01-01

Aim: The aim of the present study was to assess the change in physical properties (surface roughness, surface hardness and phase transformation) after surface grinding of zirconia by using three commercially available abrasives. Materials and Methods: Thirty sintered zirconia specimens were prepared and divided into three groups namely Group M (grinded using Mani Dia diamond bur standard grit), Group T (grinded using Tri Hawk diamond bur coarse grit) and Group P (grinded using Predator carbide bur). A customised assembly was used to follow a standardised protocol for surface grinding. The surface roughness, surface hardness and phase transformation was recorded before and after the grinding procedure. Statistical Analysis Used: ANOVA and Bonferroni post hoc test were used to assess the values obtained after the testing the surface roughness and surface hardness. Results: The results of the present study revealed the average values of change in surface roughness as Group M (0.44 μm) and Group T (1.235 μm) and Group P (-0.88 μm). The average values of change in surface hardness were Group T (19.578 HV), Group M (46.722 HV) and Group P (36.429 HV). The change in surface hardness was not statistically significant. There was no phase transformation seen after the grinding procedure. Clinical Significance: Carbide burs along with copious water irrigation when used to grind zirconia intra-orally produces has a polishing effect, minimal change in hardness & no phase transformation. The present study advocates the use of carbides for chair-side grinding of zirconia. PMID:28216841

Statistical experiments using the multiple regression research for prediction of proper hardness in areas of phosphorus cast-iron brake shoes manufacturing

NASA Astrophysics Data System (ADS)

Kiss, I.; Cioată, V. G.; Ratiu, S. A.; Rackov, M.; Penčić, M.

2018-01-01

Multivariate research is important in areas of cast-iron brake shoes manufacturing, because many variables interact with each other simultaneously. This article focuses on expressing the multiple linear regression model related to the hardness assurance by the chemical composition of the phosphorous cast irons destined to the brake shoes, having in view that the regression coefficients will illustrate the unrelated contributions of each independent variable towards predicting the dependent variable. In order to settle the multiple correlations between the hardness of the cast-iron brake shoes, and their chemical compositions several regression equations has been proposed. Is searched a mathematical solution which can determine the optimum chemical composition for the hardness desirable values. Starting from the above-mentioned affirmations two new statistical experiments are effectuated related to the values of Phosphorus [P], Manganese [Mn] and Silicon [Si]. Therefore, the regression equations, which describe the mathematical dependency between the above-mentioned elements and the hardness, are determined. As result, several correlation charts will be revealed.

Ultrasonic Technique for Predicting Grittiness of Salted Duck Egg

NASA Astrophysics Data System (ADS)

Erawan, S.; Budiastra, I. W.; Subrata, I. D. M.

2018-05-01

Grittiness of egg yolk is a major factor in consumer acceptance of salted duck egg product. Commonly, the grittiness level is determined by the destructive method. Salted egg industries need a grading system that can judge the grittiness accurately and nondestructively. The purpose of this study was to develop a method for determining grittiness of salted duck eggs nondestructively based on ultrasonic method. This study used 100 samples of salted duck eggs with 7,10,14 and 21 days of salting age. Velocity and attenuation were measured by an ultrasonic system at frequency 50 kHz, followed by physicochemical properties measurement (hardness of egg yolks and salt content), and organoleptic test. Ultrasonic wave velocity in salted duck eggs ranged from 620.6 m/s to 1334.6 m/s, while the coefficient of attenuation value ranged from – 0.76 dB/m to -0.51 dB/m. Yolk hardness was 2.68 N at 7 days to 5.54 N at 21 days of salting age. Salt content was 1.81 % at 7 days to 5.71 % at 21 days of salting age. Highest scores of organoleptic tests on salted duck eggs were 4.23 and 4.18 for 10 and 14 days of salting age, respectively. Discriminant function using ultrasonic velocity variables in minor and major diameter could predict grittiness with 95 % accuracy.

The use of Hibiscus esculentus (Okra) gum in sustaining the release of propranolol hydrochloride in a solid oral dosage form.

PubMed

Zaharuddin, Nurul Dhania; Noordin, Mohamed Ibrahim; Kadivar, Ali

2014-01-01

The effectiveness of Okra gum in sustaining the release of propranolol hydrochloride in a tablet was studied. Okra gum was extracted from the pods of Hibiscus esculentus using acetone as a drying agent. Dried Okra gum was made into powder form and its physical and chemical characteristics such as solubility, pH, moisture content, viscosity, morphology study using SEM, infrared study using FTIR, crystallinity study using XRD, and thermal study using DSC and TGA were carried out. The powder was used in the preparation of tablet using granulation and compression methods. Propranolol hydrochloride was used as a model drug and the activity of Okra gum as a binder was compared by preparing tablets using a synthetic and a semisynthetic binder which are hydroxylmethylpropyl cellulose (HPMC) and sodium alginate, respectively. Evaluation of drug release kinetics that was attained from dissolution studies showed that Okra gum retarded the release up to 24 hours and exhibited the longest release as compared to HPMC and sodium alginate. The tensile and crushing strength of tablets was also evaluated by conducting hardness and friability tests. Okra gum was observed to produce tablets with the highest hardness value and lowest friability. Hence, Okra gum was testified as an effective adjuvant to produce favourable sustained release tablets with strong tensile and crushing strength.

Effects of Glasswort (Salicornia herbacea L.) Hydrates on Quality Characteristics of Reduced-salt, Reduced-fat Frankfurters

PubMed Central

Choi, Yun-Sang

2015-01-01

This study evaluated the effects of adding glasswort hydrate containing non-meat ingredient (GM, carboxy methyl cellulose; GC, carrageenan; GI, isolated soy protein; GS, sodium caseinate) on the quality characteristics of reduced-salt, reduced-fat frankfurters. The pH and color evaluation showed significant differences, depending on the type of glasswort hydrate added (p<0.05). In the raw batters and cooked frankfurters, the addition of glasswort hydrate decreased the redness and increased the yellowness in comparison with frankfurters without glasswort hydrate. The reduction in salt and fat content significantly increased cooking loss and decreased hardness, tenderness and juiciness (p<0.05). Glasswort hydrate containing non-meat ingredient improved cooking loss, water holding capacity, emulsion stability, hardness, and viscosity of reduced-salt, reduced-fat frankfurters. The GM treatment had the highest myofibiliar protein solubility among all treatments, which was associated with emulsion stability and viscosity. The GC treatment had higher values for all texture parameters than the control. In the sensory evaluation, the addition of glasswort hydrate with non-meat ingredient improved tenderness and juiciness of reduced-salt, reduced-fat frankfurters. GM, GC, and GI treatments improved not only the physicochemical properties but also the sensory characteristics of reduced-salt, reduced-fat frankfurters. The results indicated that the use of glasswort hydrate containing non-meat ingredient was improved the quality characteristics of reduced-salt, reduced-fat frankfurters. PMID:26877638

Silica removal in industrial effluents with high silica content and low hardness.

PubMed

Latour, Isabel; Miranda, Ruben; Blanco, Angeles

2014-01-01

High silica content of de-inked paper mill effluents is limiting their regeneration and reuse after membrane treatments such as reverse osmosis (RO). Silica removal during softening processes is a common treatment; however, the effluent from the paper mill studied has a low hardness content, which makes the addition of magnesium compounds necessary to increase silica removal. Two soluble magnesium compounds (MgCl₂∙6H₂O and MgSO₄∙7H₂O) were tested at five dosages (250-1,500 mg/L) and different initial pH values. High removal rates (80-90%) were obtained with both products at the highest pH tested (11.5). With these removal efficiencies, it is possible to work at high RO recoveries (75-85%) without silica scaling. Although pH regulation significantly increased the conductivity of the waters (at pH 11.5 from 2.1 to 3.7-4.0 mS/cm), this could be partially solved by using Ca(OH)₂ instead of NaOH as pH regulator (final conductivity around 3.0 mS/cm). Maximum chemical oxygen demand (COD) removal obtained with caustic soda was lower than with lime (15 vs. 30%). Additionally, the combined use of a polyaluminum coagulant during the softening process was studied; the coagulant, however, did not significantly improve silica removal, obtaining a maximum increase of only 10%.

Experimental Investigation on Surface Quality Processed by Self-Excited Oscillation Pulsed Waterjet Peening

PubMed Central

Ding, Xiaolong; Kang, Yong; Li, Deng; Wang, Xiaochuan; Zeng, Dongping

2017-01-01

High-speed waterjet peening technology has attracted a lot of interest and is now being widely studied due to its great ability to strengthen metal surfaces. In order to further improve the mechanical properties of metals, self-excited oscillation pulsed waterjets (SOPWs) were used for surface peening with an experimental investigation focused on the surface topography and properties. By impinging the aluminum alloy (5052) specimens with SOPWs issuing from an organ-pipe oscillation nozzle, the hardness and roughness at various inlet pressures and stand-off distances were measured and analyzed, as well as the residual stress. Under the condition of optimum stand-off distances, the microscopic appearances of peened specimens obtained by SEM were displayed and analyzed. Results show that self-excited oscillation pulsed waterjet peening (SOPWP) is capable of improving the surface quality. More specifically, compared with an untreated surface, the hardness and residual stress of the peened surfaces were increased by 61.69% and 148%, respectively. There exists an optimal stand-off distance and operating pressure for creating the highest surface quality. SOPWP can produce almost the same enhancement effect as shot peening and lead to a lower surface roughness. Although such an approach is empirical and qualitative in nature, this procedure also generated information of value in guiding future theoretical and experimental work on the application of SOPWP in the industry practice. PMID:28841184

The Use of Hibiscus esculentus (Okra) Gum in Sustaining the Release of Propranolol Hydrochloride in a Solid Oral Dosage Form

PubMed Central

Noordin, Mohamed Ibrahim; Kadivar, Ali

2014-01-01

The effectiveness of Okra gum in sustaining the release of propranolol hydrochloride in a tablet was studied. Okra gum was extracted from the pods of Hibiscus esculentus using acetone as a drying agent. Dried Okra gum was made into powder form and its physical and chemical characteristics such as solubility, pH, moisture content, viscosity, morphology study using SEM, infrared study using FTIR, crystallinity study using XRD, and thermal study using DSC and TGA were carried out. The powder was used in the preparation of tablet using granulation and compression methods. Propranolol hydrochloride was used as a model drug and the activity of Okra gum as a binder was compared by preparing tablets using a synthetic and a semisynthetic binder which are hydroxylmethylpropyl cellulose (HPMC) and sodium alginate, respectively. Evaluation of drug release kinetics that was attained from dissolution studies showed that Okra gum retarded the release up to 24 hours and exhibited the longest release as compared to HPMC and sodium alginate. The tensile and crushing strength of tablets was also evaluated by conducting hardness and friability tests. Okra gum was observed to produce tablets with the highest hardness value and lowest friability. Hence, Okra gum was testified as an effective adjuvant to produce favourable sustained release tablets with strong tensile and crushing strength. PMID:24678512

Functional and taxonomic plant diversity for riverbank protection works: bioengineering techniques close to natural banks and beyond hard engineering.

PubMed

Cavaillé, Paul; Ducasse, Léon; Breton, Vincent; Dommanget, Fanny; Tabacchi, Eric; Evette, André

2015-03-15

Erosion control is a major issue in the Prealps region since piedmont is subject to both intense flood hazards and anthropic pressure. Riverbank protections may have major impacts on local ecosystem functioning and ecological corridor continuity. This study aimed to estimate the effects of the types of riverbank protection technique (from pure riprap to pure bioengineering) on the taxonomic and ecological composition of plant communities in comparison with unmanaged riverbanks as the referential system. Thirty-eight embankments were sampled in the foothills of the French and Swiss Alps. Four distinct riverbank techniques were analyzed and natural young willow stands were chosen as the referential system. At each site, vegetation was sampled along three transects from the waterline to the top of the riverbank. Plant communities were characterized using biological group composition (growth forms and life history, life strategies and distribution in space and time) and functional diversity indices (MFAD, FDc and wFDc). We identified 177 distinct plant species on 38 sites. Higher species richness levels were observed on bioengineered banks (from an average of 12 species recorded on ripraps to 27 species recorded on bioengineered banks) strongly dominated by Salicaceae species, especially for fascine and cribwall banks. Functional analyses of plant communities highlighted significant differences among bank types (p-value: 0.001) for all selected biological groups. Competitive - ruderal strategy, rooting shoots, stems or leaves that lie down or break off, and unisexual - dioecious, as well as pioneer plants and low shrubs (<4 m tall) distinguished bioengineered bank types. Functional diversity indices confirmed these differences among bank types (MFAD: p-value: 0.002; FDc: p-value: 0.003; wFDc: p-value: 0.005). Riprap always showed the lowest levels on functional diversity indices, fascine and cribwall banks were at the medium level and finally mixed and natural banks the highest level. These results confirm the low ecological potential of purely hard engineering techniques and highlight the similarity of bioengineered techniques and unmanaged riverbanks. Copyright © 2014 Elsevier Ltd. All rights reserved.

The Effects of Low- and High-Energy Cutoffs on Solar Flare Microwave and Hard X-Ray Spectra

NASA Technical Reports Server (NTRS)

Holman, G. D.; Oegerle, William (Technical Monitor)

2002-01-01

Microwave and hard x-ray spectra provide crucial information about energetic electrons and their environment in solar flares. These spectra are becoming better determined with the Owens Valley Solar Array (OVSA) and the recent launch of the Ramaty High Energy Solar Spectroscopic Imager (RHESSI). The proposed Frequency Agile Solar Radiotelescope (FASR) promises even greater advances in radio observations of solar flares. Both microwave and hard x-ray spectra are sensitive to cutoffs in the electron distribution function. The determination of the high-energy cutoff from these spectra establishes the highest electron energies produced by the acceleration mechanism, while determination of the low-energy cutoff is crucial to establishing the total energy in accelerated electrons. This paper will show computations of the effects of both high- and low-energy cutoffs on microwave and hard x-ray spectra. The optically thick portion of a microwave spectrum is enhanced and smoothed by a low-energy cutoff, while a hard x-ray spectrum is flattened below the cutoff energy. A high-energy cutoff steepens the microwave spectrum and increases the wavelength at which the spectrum peaks, while the hard x-ray spectrum begins to steepen at photon energies roughly an order of magnitude below the electron cutoff energy. This work discusses how flare microwave and hard x-ray spectra can be analyzed together to determine these electron cutoff energies. This work is supported in part by the NASA Sun-Earth Connection Program.

Effects of shoe sole hardness on plantar pressure and comfort in older people with forefoot pain.

PubMed

Lane, Tamara J; Landorf, Karl B; Bonanno, Daniel R; Raspovic, Anita; Menz, Hylton B

2014-01-01

Plantar forefoot pain is common in older people and is related to increased peak pressures under the foot during gait. Variations in the hardness of the shoe sole may therefore influence both the magnitude of loading under the foot and the perceived comfort of the shoe in this population. The aim of this investigation was to determine the effect of varying shoe sole hardness on plantar pressures and comfort in older people with forefoot pain. In-shoe plantar pressures under the forefoot, midfoot and rearfoot were recorded from 35 older people (mean age 73.2, SD 4.5 years) with current or previous forefoot pain using the pedar-X(®) system. Participants walked at their normal comfortable speed along an 8m walkway in shoes with three different levels of sole hardness: soft (Shore A25), medium (Shore A40) and hard (Shore A58). Shoe comfort was measured on a 100mm visual analogue scale. There were statistically significant differences in peak pressure of between 5% and 23% across the forefoot, midfoot and rearfoot (p<0.01). The hard-soled shoe registered the highest peak pressures and the soft-soled shoe the lowest peak pressures. However, no differences in comfort scores across the three shoe conditions were observed. These findings demonstrate that as shoe sole hardness increases, plantar pressure increases, however this does not appear to have a significant effect on shoe comfort. Crown Copyright © 2013. Published by Elsevier B.V. All rights reserved.

Parameterized Complexity of k-Anonymity: Hardness and Tractability

NASA Astrophysics Data System (ADS)

Bonizzoni, Paola; Della Vedova, Gianluca; Dondi, Riccardo; Pirola, Yuri

The problem of publishing personal data without giving up privacy is becoming increasingly important. A precise formalization that has been recently proposed is the k-anonymity, where the rows of a table are partitioned in clusters of size at least k and all rows in a cluster become the same tuple after the suppression of some entries. The natural optimization problem, where the goal is to minimize the number of suppressed entries, is hard even when the stored values are over a binary alphabet or the table consists of a bounded number of columns. In this paper we study how the complexity of the problem is influenced by different parameters. First we show that the problem is W[1]-hard when parameterized by the value of the solution (and k). Then we exhibit a fixed-parameter algorithm when the problem is parameterized by the number of columns and the number of different values in any column.

Enrichment of probiotic ice cream with different dietary fibers: Structural characteristics and culture viability.

PubMed

Akalın, A S; Kesenkas, H; Dinkci, N; Unal, G; Ozer, E; Kınık, O

2018-01-01

This study evaluated the effect of 5 dietary fibers (apple, orange, oat, bamboo, and wheat) on the physicochemical, rheological, and textural characteristics; sensory properties; and culture viability of probiotic ice cream stored at -18°C for 180 d. The presence of orange and apple fibers increased the titratable acidity, decreased the lightness (color) value of the ice creams, and enhanced the red and yellow coloration. Compared with the control sample, the consistency indices and apparent viscosities of the experimental samples increased with the addition of all dietary fibers except oat fiber. The highest viscosity was obtained in the sample fortified with apple fiber, whereas the ice cream containing orange fiber showed the highest hardness after d 60 of storage. The addition of orange and apple fibers significantly increased melting resistance; however, panelists did not generally like these samples in terms of taste-flavor. All ice creams had viable counts of Lactobacillus acidophilus of ≥7 log cfu/g during storage except the samples with orange and bamboo fiber. Bifidobacterium lactis counts were also found to be >6 log cfu/g in those samples until d 150 of storage. Copyright © 2018 American Dairy Science Association. Published by Elsevier Inc. All rights reserved.

Physicochemical and Rheological Properties of a Dairy Dessert, Enriched with Chickpea Flour.

PubMed

Aguilar-Raymundo, Victoria Guadalupe; Vélez-Ruiz, Jorge Fernando

2018-02-18

Dairy desserts are complex mixtures and matrices including main components such as milk, sugar, starch, hydrocolloids, colorants and flavors, with a proteinaceous structure; they are widely consumed and present a semisolid consistency. In this work, the physicochemical and rheological properties of a dairy dessert with the addition of chickpea flour (raw and cooked, at four concentrations) were studied to determine the effect of the flour. The results indicated that luminosity (L*: 62.75-83.29), pH (6.35-7.11) and acidity (1.56-3.56) changed with the type of flour. The flow properties of the custards exhibited a non-Newtonian behavior that was well fitted by three flow models. The studied custard systems were stored for twelve days at 4 °C. The physicochemical and flow properties of the custards changed notably as a function of flour addition and storage time. From all samples, only four were analyzed with oscillatory tests, showing their mechanical spectra with elastic behavior. The dessert texture was also measured, founding that those formulated with Blanco Noroeste chickpea flour exhibited the highest values of hardness (0.356-0.391 Newton (N)) through the twelve days. It can be concluded that those custard systems with the highest content of flour presented a very good response as a potential new dairy product.

The wildlife research & rescue programme for mammals at Hulu Terengganu Hydroelectric Project (HTHEP), Terengganu, Peninsular Malaysia

NASA Astrophysics Data System (ADS)

Nur-Syuhada, N.; Magintan, D.; Siti-Hajar, A. R.; Aisah, M. S.; Shukor, M. N.

2016-11-01

During the inundation of the Hulu Terengganu Hydroelectric Project in October 2014, a wildlife rescue programme was conducted to rescue animals found trapped within the expanding 61.6 km2 reservoir. A total of 244 mammals from 30 species, representing 12 families were rescued by various methods included baited live trapping, catchpoles, hoop nets and by hand. The order Rodentia recorded the highest amount of rescued individuals at 20.9%, followed by Primate (18.9), Dermoptera (11.1), Carnivora (0.8) and Pholidota (0.4). The genus Rattus recorded the highest individuals rescued (51 individuals) probably due to the rapid clear-cut logging of the forest prior to inundation. Notable mammals of high conservational value rescued included Manis javanicus (Pangolin), Presbytis melalophos siamensis (Mitred Leaf Monkey), Trachypithecus obscurus (Dusky Leaf Monkey), Hylobates lar (White Handed Gibbon), Nycticebus coucang (Slow Loris), Galeopterus variegatus (Sunda Colugo), Callosciurus nigrovittatus (Sunda Black-banded Squirrel), Ratufa spp. (Giant Squirrels), and Sundasciurus hippurus (Horse-tailed Squirrel). Various data and biological samples were collected from the mammals rescued prior to their release at the nearest forest reserves. Rescue operation enabled the inventory and comprehensive data collection of various arboreal and rare mammal species that are hard to capture using the traditional survey method.

Protectiveness of water quality criteria for copper in western United States waters relative to predicted olfactory responses in juvenile Pacific salmon.

PubMed

DeForest, David K; Gensemer, Robert W; Van Genderen, Eric J; Gorsuch, Joseph W

2011-07-01

Copper (Cu) can impair olfaction in juvenile Pacific salmon (as well as other fishes), thus potentially inhibiting the ability of juveniles to avoid predators or to find food. Because Cu is commonly elevated in stormwater runoff in urban environments, storm events may result in elevated Cu concentrations in salmon-bearing streams. Accordingly, there is concern that existing Cu criteria, which were not derived using data for olfactory-related endpoints, may not be adequately protective of juvenile salmon. However, a modification of the US Environmental Protection Agency (USEPA) biotic ligand model (BLM) for deriving site-specific Cu criteria was recently proposed, which accounted for the sensitivity of olfactory endpoints. The modification was based on olfactory inhibition in juvenile coho salmon (Oncorhynchus kisutch) exposed to Cu in various combinations of pH, hardness, alkalinity, and dissolved organic carbon (DOC) concentrations. We used that olfactory-based BLM to derive 20% inhibition concentrations (IC20) values for Cu for 133 stream locations in the western United States. The olfactory BLM-based IC20 values were compared to the existing hardness-based Cu criteria and the USEPA's BLM-based Cu criteria for these representative natural waters of the western United States. Of the 133 sampling locations, mean hardness-dependent acute and chronic Cu criteria were below the mean olfactory-based BLM IC20 value in 122 (92%) and 129 (97%) of the waters, respectively (i.e., <20% olfactory impairment would have been predicted at the mean hardness-based Cu criteria concentrations). Waters characterized by a combination of high hardness and very low DOC were most likely to have hardness-based Cu criteria that were higher than the olfactory-based BLM IC20 values, because DOC strongly influences Cu bioavailability in the BLM. In all waters, the USEPA's current BLM-based criteria were below the mean olfactory-based BLM IC20 values, indicating that the USEPA's BLM-based criteria are protective of olfactory impairment in juvenile salmon. Copyright © 2011 SETAC.

Assessment of multi-pulse laser-induced damage threshold of metallic mirrors for Thomson scattering system.

PubMed

Sato, Masaya; Kajita, Shin; Yasuhara, Ryo; Ohno, Noriyasu; Tokitani, Masayuki; Yoshida, Naoaki; Tawara, Yuzuru

2013-04-22

Multi-pulse laser-induced damage threshold (LIDT) was experimentally investigated up to ~10(6) pulses for Cu, Ag mirrors. The surface roughness and the hardness dependence on the LIDT were also examined. The LIDT of OFHC-Cu decreased with the pulse number and was 1.0 J/cm(2) at 1.8 × 10(6) pulses. The expected LIDT of cutting Ag at 10(7) pulses was the highest; Ag mirror would be one of the best choices for ITER Thomson scattering system. For the roughness and hardness, material dependences of LIDT are discussed with experimental results.

Effect of beverages and mouthwashes on the hardness of polymers used in intraoral prostheses.

PubMed

Goiato, Marcelo Coelho; Dos Santos, Daniela Micheline; Andreotti, Agda Marobo; Nobrega, Adhara Smith; Moreno, Amalia; Haddad, Marcela Filié; Pesqueira, Aldiéris Alves

2014-10-01

The mechanical properties of acrylic resins used in intraoral prostheses may be altered by frequent exposure to liquids such as beverages and mouthwashes. This study aimed to evaluate the effect of thermocycling and liquid immersion on the hardness of four brands of acrylic resins commonly used in removable prostheses (Onda Cryl, QC-20, Clássico, Lucitone). For each brand of resin, seven specimens were immersed in each of six solutions (coffee, cola, red wine, Plax-Colgate, Listerine [LI], Oral B), and seven more were placed in artificial saliva (control). The hardness was tested using a microhardness tester before and after 5000 thermocycles and after 1, 3, 24, 48, and 96 hours of immersion. The results were analyzed using three-way repeated-measures ANOVA and Tukey's test (p < 0.05). The hardness of the resins decreased following thermocycling and immersion in the solutions. Specimens immersed in cola and wine exhibited significant decreases in hardness after immersion for 96 hours, although the greatest significant decrease in hardness occurred in specimens immersed in LI. However, according to American Dental Association specification 12, the Knoop hardness of acrylic resins for intraoral prostheses should not be below 15. Thus, the median values of superficial hardness observed in most of the acrylic resins in this study are considered clinically acceptable. The microhardness of polymers used for intraoral prostheses decreases following thermocycling. Among specimens immersed in beverages, those immersed in cola or wine experienced the greatest decrease in microhardness. Immersion of acrylic resins in LI significantly decreased the microhardness in relation to the initial value. Among the resins assessed, QC-20 exhibited the lowest initial hardness. © 2014 by the American College of Prosthodontists.

The effect of case hardening treatment on aluminum 7075 toward its hardness and tensile strength

NASA Astrophysics Data System (ADS)

Darsono, Febri Budi; Triyono, Teguh; Surojo, Eko

2018-02-01

This research was aimed at figuring out the effect of case hardening treatment on aluminum 7075 toward its hardness and tensile strength. Pack carburizing was the method used in this process. It was conducted in 2 hours of holding time in various solution heat treatment (SHT): 350°C, 400°C, 450°C, and 500° C using smoergen oven, which was then followed by quenching. Several tests to see the effect of the treatment were done before and after the treatment, namely: Vickers hardness test using HWMMT-X7, tensile test ASTM B557-84 using SANS UTM, XRD test using Rigaku Benchtop, and SEM-EDS test using JEOL JSM-6510 LA. The result showed that the hardness and tensile of aluminum 7075 before treatment were 59.1 VHN and 235.7 Mpa. After treatment, its hardness values were 94.0, 120.7, 141.3, and 145.9 VHN and the tensile strengths were 321.7, 410.0, 480.0, and 538.3 Mpa. The result showed that SHT temperature rise in pack carburizing process increased the tensile strength, while the increase of the hardness value is due to the formation of Al4C3 phase on the aluminum surface.

Pseudo hard-sphere potential for use in continuous molecular-dynamics simulation of spherical and chain molecules

NASA Astrophysics Data System (ADS)

Jover, J.; Haslam, A. J.; Galindo, A.; Jackson, G.; Müller, E. A.

2012-10-01

We present a continuous pseudo-hard-sphere potential based on a cut-and-shifted Mie (generalized Lennard-Jones) potential with exponents (50, 49). Using this potential one can mimic the volumetric, structural, and dynamic properties of the discontinuous hard-sphere potential over the whole fluid range. The continuous pseudo potential has the advantage that it may be incorporated directly into off-the-shelf molecular-dynamics code, allowing the user to capitalise on existing hardware and software advances. Simulation results for the compressibility factor of the fluid and solid phases of our pseudo hard spheres are presented and compared both to the Carnahan-Starling equation of state of the fluid and published data, the differences being indistinguishable within simulation uncertainty. The specific form of the potential is employed to simulate flexible chains formed from these pseudo hard spheres at contact (pearl-necklace model) for mc = 4, 5, 7, 8, 16, 20, 100, 201, and 500 monomer segments. The compressibility factor of the chains per unit of monomer, mc, approaches a limiting value at reasonably small values, mc < 50, as predicted by Wertheim's first order thermodynamic perturbation theory. Simulation results are also presented for highly asymmetric mixtures of pseudo hard spheres, with diameter ratios of 3:1, 5:1, 20:1 over the whole composition range.

Radiation enhanced modification of HDPE for medical applications.

PubMed

Suwanprateeb, J; Trongtong, P

2003-10-01

Comparison of gamma irradiation induced change in properties in terms of thermal and mechanical properties between two grades of HDPE and UHMWPE was carried out. It was found that the responses to irradiation of two grades of HDPE investigated were close whereas a difference in response was found between HDPE and UHMWPE. The irradiation dose that caused the lowest wear and highest hardness for UHMWPE was 500 kGy. When irradiation dose was above 500 kGy, no significant changes in wear and hardness properties were observed. The irradiation dose for HDPE, both 2208J and 7000F, that caused the wear resistance and hardness comparable to irradiated UHMWPE at 500 kGy was 1000 kGy. In addition, the dose of 750 kGy was needed for HDPE to achieve the similar level of wear resistance as non-irradiated UHMWPE. Copyright 2003 Kluwer Acadamic Publishers

Formulation and evaluation of antihyperglycemic leaf extracts of Zizyphus spina-christi (L.) Willd.

PubMed

Nesseem, D I; Michel, C G; Sleem, A A; El-Alfy, T S

2009-02-01

This study deals with the formulation of antihyperglycemic leaf extracts of Zizyphus spina-christi (L.) Willd. A bioactivity guided fractionation of different leaf extracts [defatted ethanol 70% (a), butanol (b), ethanol 70% (c), ethyl acetate (d) and petroleum ether (e) extracts] revealed that extract (c) possessed the highest antihyperglycemic activity followed by (b) and (a). HPLC was adopted for standardization of the extract (c) based on evaluation of the major saponin christinin-A which was used as marker. The detection limit was 9.45 mg/ml for Christinin-A. Extracts (a), (b) and (c) were separately formulated in soft (S) and hard (H) gelatin capsules. Two different formulations (F1 and F2) were tried using different excipients suitable for oral drug delivery. Formula 1, used for soft gelatin capsules [(F1) Sa, Sb, Sc] Formula 2, used for hard gelatin capsules [(F2) - Ha, Hb, Hc]. The recovery rates of the samples of saponin were in the range 99.43-101.86% at 200, 800 microg/ml and 1200 microg/ml. Saponin release rates from different formulae were carried out using dissolution tester USP XXIV. The highest release was obtained from formulation Sc. The release of the extracts followed diffusion mechanism. The selected formula Sc exhibited highest anti-diabetic activity (P < 0.01) on acute and long-term administration and highest saponin release. This formula (Sc) contained poly-oxyethylene (20) cetyl ether (BC-20TX), PEG 400, PEG 6000, purified water, meglyol 810, ascorbic acid and 200 mg of extract (c).

Strength/Brittleness Classification of Igneous Intact Rocks Based on Basic Physical and Dynamic Properties

NASA Astrophysics Data System (ADS)

Aligholi, Saeed; Lashkaripour, Gholam Reza; Ghafoori, Mohammad

2017-01-01

This paper sheds further light on the fundamental relationships between simple methods, rock strength, and brittleness of igneous rocks. In particular, the relationship between mechanical (point load strength index I s(50) and brittleness value S 20), basic physical (dry density and porosity), and dynamic properties (P-wave velocity and Schmidt rebound values) for a wide range of Iranian igneous rocks is investigated. First, 30 statistical models (including simple and multiple linear regression analyses) were built to identify the relationships between mechanical properties and simple methods. The results imply that rocks with different Schmidt hardness (SH) rebound values have different physicomechanical properties or relations. Second, using these results, it was proved that dry density, P-wave velocity, and SH rebound value provide a fine complement to mechanical properties classification of rock materials. Further, a detailed investigation was conducted on the relationships between mechanical and simple tests, which are established with limited ranges of P-wave velocity and dry density. The results show that strength values decrease with the SH rebound value. In addition, there is a systematic trend between dry density, P-wave velocity, rebound hardness, and brittleness value of the studied rocks, and rocks with medium hardness have a higher brittleness value. Finally, a strength classification chart and a brittleness classification table are presented, providing reliable and low-cost methods for the classification of igneous rocks.

Toward a Revolution in Intelligence Affairs

DTIC Science & Technology

2005-01-01

hard because people overestimate the value of what they have⎯and underestimate the value of what they may gain by giving that up." James Belasco and...Best Truths : Intelligence in the Information Age, New Haven: Yale University Press, 2000, p. 44. 19 collection operations, and analytical methodologies...to CIA DDO James Pavitt, “We have more reporting on the really hard targets than I can remember at any time in my nearly 30 years of agency service.”7

Development of a novel oxirane-acrylate composite restorative resin material

NASA Astrophysics Data System (ADS)

Sripathi Panditaradhyula, Anuhya

The need for resin with a long clinical life can be satiated through the novel formulation of varying concentrations of oxirane and acrylate monomers with an increase in filler loading in the sample, which will allow the creation of a resin that is less susceptible to chemical degradation along with improved mechanical properties. Various concentrations of oxirane and acrylate monomers with a three-component photoinitiation system, which is capable of both free radical (acrylate) and cationic (oxirane) initiation, are used. The resin composites were placed in the Speedmixer for 30 seconds and gravitation convection oven for one minute, repeated 5-7 times. The resin composites were used to create a 9.525 mm diameter * 1.5875 mm thick resin mold. The mold was then photocured for twenty seconds on both sides using VALO blue LED light. The Rockwell hardness and shore D durometer hardness served as relative measures of bonding between the monomers. The ideal formulation of oxirane and acrylate concentrations were used to perform the Instron 3 point bend test, as well as contact angle determination. The goal is to identify a resin with a clinical life twice that of the resins being used in practice. Potential findings include ideal oxirane and acrylate concentrations with the highest shore D durometer hardness, Rockwell hardness, contact angle values, and Instron 3 point bend test values. Ideal color, transparency and properties of the resin are taken into account. Optimization of oxirane and acrylate monomers, impact while using various filler components (salination, number of fillers), filler particle size variations and variations in using different filler concentrations are observed. Results of using micro and nano-sized monomers are also studied. Addition of fluorinated acrylate monomer to the micro and nano composite was the next goal. A comparison of all the above stated compositions to the control group 70/30 BisTEG was done. A study on the degradation behavior of these specimens were done by placing the respective specimens in distilled water, ascorbic acid (pH=1.5) and NaOH (pH=13). These resins were not fully cured with filler apart from filled 25:75 oxirane: acrylate cured best. Replacing 4-(Octyloxy) phenyl] phenyl iodonium SbF6 (OPPI) with 4-Isopropyl-4'- methyldiphenyl iodonium Tetrakis (pentafluorophenyl borate (Borate) initiator enhanced 24hr oxirane cure. Formulations had greater hardness compared with the controls. The increase in hardness was due to Increase in oxirane functionality, Increase in filler loading and use of acrylate-salinated filler. Modulus and ultimate transverse strength are greater than controls, but did not have statistically significance energy to break. Thus, these composites are as tough as controls and less brittle. They have the higher hydrophobicity than BisGMA: TEGDMA controls. Furthermore, other means of increasing hydrophobicity was explored, because higher the hydrophobicity, higher the resistance to hydrolytic degradation. Further research observations, such as dynamic mechanical analysis, should be carried out in order to determine the molecular interactions and usage of multi-walled, white carbon nanotubes as filler material.

Investigation of Specificity of Mechanical Properties of Hard Materials on Nanoscale with Use of SPM- Nanohardness Tester

NASA Astrophysics Data System (ADS)

Lvova, N. A.; Blank, V. D.; Gogolinskiy, K. V.; Kulibaba, V. F.

2007-04-01

Specifisities of deformation on nanoscale of hard brittle materials with the hardness exceeding 10 GP by means of scanning probe microscope - nanohardness tester "NanoScan" are investigated. It is found, that pile-up is forming at scratching of sample surface with use of diamond indenter. Heigh of this pile-up depends on hardness and elastic modulus of the material. Definition of the contact area without taking into account height of pile-up leads to an overestimation of hardness values. At scratching of silicon carbide surface a transition from plastic flow to fracture is found out. The results received allowed to estimate fracture toughness KIC for silicon carbide.

Fesbnd X (X = B, N) binary compounds: First-principles calculations of electronic structures, theoretic hardness and magnetic properties

NASA Astrophysics Data System (ADS)

Hui, Liangliang; Xie, Zhongjing; Li, Chunmei; Chen, Zhi-Qian

2018-04-01

The first-principles calculations are implemented to investigate the electronic structures, theoretic hardness and magnetic properties of iron borides and nitrides with four different crystal systems containing hexagonal (FeB2, ε-Fe3N), tetragonal (Fe2B, α″-Fe16N2), orthorhombic (α-FeB, θ-Fe3B, ζ-Fe2N), and cubic (zb-FeN, rs-FeN, γ‧-Fe4N, γ-Fe23B6) phase. The calculated lattice parameters using RPBE meet well with the experimental results. The cohesive energy and formation enthalpy values indicate the Fesbnd X (X = B, N) binary compounds are thermodynamically stable. Meanwhile, the h-FeB2 is most difficult phase for experimental synthesis among these interstitial compounds. Moreover, magnetic properties are discussed and show that the mean magnetic moments of o-Fe3B and c-Fe23B6 with the values of 2.227 μB and 2.256 μB per iron atom are approaching to that of pure iron (2.32 μB) while the c-Fe4N and t-Fe16N2 with the values of 2.51 and 2.48 μB are beyond that of pure α-Fe. The c-FeN phase shows nonmagnetic in zb-style while rs-type shows antiferromagnetic with a value of 2.52 μB. Furthermore, the average bonding length and Mulliken population combined with electronic structures are also analysed in this paper which provide that strong Fesbnd X and Xsbnd X covalent bonds are responsible for high hardness. Finally, the theoretic hardness of Xsbnd X, Fesbnd X and Fesbnd Fe bonds is predicted by semi empirical hardness theory.

Effects of milk powder and its components on texture, yield, and color of a lean poultry meat model system.

PubMed

Barbut, S

2010-06-01

The effects of whole milk powder, 2 skim milk powders, caseinate, and 2 modified whey proteins (2% protein level in the final product) were evaluated in lean chicken meat batters and compared with controls with and without added lactose. All dairy proteins significantly (P<0.05) reduced cook losses when compared against the controls, with the 2 skim milk powders and modified whey-I showing the best results. Hardness and fracturability were also higher for all test batters compared with controls. Skim milk-II showed the highest fracturability value (21.9 vs. 7.1 N for the control) and was also found to be the most cost-effective ingredient for improving moisture binding and texture; skim milk-I and modified whey-I followed behind. Springiness and fracture distance were higher for all of the dairy proteins, except caseinate, indicating a positive contribution to the lean meat system's elasticity. In terms of color, adding the skim milk powders, modified whey-II, and whole milk powder resulted in lighter cooked meat batters as evidenced by the higher L* values and higher spectra curves.

Evaluating the effect of some mechanical properties for chemically treated various natural fibers reinforced polyester composite

NASA Astrophysics Data System (ADS)

Salih, Wafaa Mahdi; Abdulkader, Niveen Jamal; Salih, Sana Mahdi

2018-05-01

This research were studied the effect of some mechanical properties for composite materials reinforced fiber and prepared from material (polyester with various natural fibers) then studied the effect of chemical treatment on the same fiber immerse in 10% NaOH solution for half an hour and then compared, the results of the same test of composite materials without and with chemical treatment and the results proved that there is a clear effect when treat the fiber compared to non-chemical treatment of the fibers also noted that hemp fibers loaded the stress higher than other fibers for both cases to distinguish them that the hemp fiber has continuous fibers either the other fibers are characterized by the type of cross linking or chopped types in tensile test, and the results of the same test of composite materials without and with chemical treatment and the results proved that the hardness of the fiber composite while the treated fiber composite samples better than the untreated fiber, and from the figures the palm leaf has the highest value than lufa fiber, hemp fiber and the smallest value is in sisal fiber because of the nature of formation fibers materials.

Comprehensive monitoring of drinking well water quality in Seoul metropolitan city, Korea.

PubMed

Kim, Ki-Hyun; Susaya, Janice P; Park, Chan Goo; Uhm, Jung-Hoon; Hur, Jin

2013-08-01

In this research, the quality of drinking well waters from 14 districts around Seoul metropolitan city, Korea was assessed by measuring a number of parameters with established guideline (e.g., arsenic, fluoride, nitrate nitrogen, benzene, 1,2-dichloroethene, dichloromethane, copper, and lead) and without such criteria (e.g., hardness, chloride ion, sulfate ion, ammonia nitrogen, aluminum, iron, manganese, and zinc). Physical parameters such as evaporation residue (or total dissolved solids) and turbidity were also measured. The importance of each parameter in well waters was examined in terms of the magnitude and exceedance frequency of guideline values established by international (and national) health agencies. The results of this study indicate that among the eight parameters with well-established guidelines (e.g., WHO), arsenic and lead (guideline value of 0.01 mg L(-1) for both) recorded the highest exceedance frequency of 18 and 16 well samples ranging in 0.06-136 and 2-9 mg L(-1), respectively. As such, a number of water quality parameters measured from many well waters in this urban area were in critical levels which require immediate attention for treatment and continuous monitoring.

Collection Development: Our World of Work

ERIC Educational Resources Information Center

Easton, Bonnie

2010-01-01

The current recession has hit American workers hard. According to the Bureau of Labor Statistics, ten percent of the U.S. workforce is unemployed (as of November 2009), the highest rate since April 1983. In addition, the labor market is experiencing record rates in the length of time job hunters remain unemployed, while companies receive hundreds…

Eight Ways to Retain Students in a Tough Economy

ERIC Educational Resources Information Center

Cardona, Adolfo Rudy

2009-01-01

Universities are not immune to the effects of the slumping economy, yet many of them are reporting their highest application and enrollment rates ever, as hard times compel people to look for new ways to increase their skills. Students' efforts to improve their job prospects, along with colleges' marketing efforts, have, indeed, translated to…

Characterization of biocomposites of sheep hydroxyapatite (SHA)/shellac/sugar as bone filler material

NASA Astrophysics Data System (ADS)

Triyono, Joko; Rizha, Yushak; Triyono, Teguh

2018-04-01

The use of biomaterials in orthopedics is increasing. This led to the growth of innovations in the field of medicine, one of them is the development of biomaterials. Study of Sheep Hydroxyapatite (SHA)/shellac/sugar biocomposite characterization was to determine the phase of the material, porosity, hardness and compressive strength of them. This research was conducted to develop new types of biomaterials that can be used as bone filler material. The analysis that used in this research was dry methods. The results showed that observation of XRD (X-Ray Diffraction) shows the pattern of diffraction 2θ: 31.6472°, 32.7753°, 32.0723°, The highest hardness of SHA/shellac/sugar ratio was 70:30% (7.38±0.1395 VHN) and the lowest at 50:50% (4.91±0.37 VHN). The highest Diametral Tensile Strength (DTS) test was 70:30% (5.43±1.395 MPa) and the lowest at 50:50% (3.10±0.26 MPa). SEM observations are performed to see the material porosity.

The Experiences of Non-Signing Deaf and Hard-of-Hearing Students and Their Academic and Social Integration into a Primarily Signing Deaf University Environment

ERIC Educational Resources Information Center

Dorminy, Jerri Lyn

2013-01-01

What is the value of a predominantly signing Deaf University such as Gallaudet University for an oral deaf or hard-of-hearing non-signing student who grew up in the mainstreamed or inclusive educational settings? This study sought to explore the experiences of ten non-signing oral deaf and hard-of-hearing university students as they integrated,…

DOE Office of Scientific and Technical Information (OSTI.GOV)

Ice, G.E.; Barbee, T.; Bionta, R.

The increasing availability of synchrotron x-ray sources has stimulated the development of advanced hard x-ray (E{>=}5 keV) microprobes. New x-ray optics have been demonstrated which show promise for achieving intense submicron hard x-ray probes. These probes will be used for extraordinary elemental detection by x-ray fluorescence/absorption and for microdiffraction to identify phase and strain. The inherent elemental and crystallographic sensitivity of an x-ray microprobe and its inherently nondestructive and penetrating nature makes the development of an advanced hard x-ray microprobe an important national goal. In this workshop state-of-the-art hard x-ray microprobe optics were described and future directions were discussed. Genemore » Ice, Oak Ridge National Laboratory (ORNL), presented an overview of the current status of hard x-ray microprobe optics and described the use of crystal spectrometers to improve minimum detectable limits in fluorescent microprobe experiments. Al Thompson, Lawrence Berkeley Laboratory (LBL), described work at the Center for X-ray Optics to develop a hard x-ray microprobe based on Kirkpatrick-Baez (KB) optics. Al Thompson also showed the results of some experimental measurements with their KB optics. Malcolm Howells presented a method for bending elliptical mirrors and Troy Barbee commented on the use of graded d spacings to achieve highest efficiency in KB multilayer microfocusing. Richard Bionta, Lawrence Livermore National Laboratory (LLNL), described the development of the first hard x-ray zone plates and future promise of so called {open_quotes}jelly roll{close_quotes} or sputter slice zone plates. Wenbing Yun, Argonne National Laboratory (ANL), described characterization of jelly roll and lithographically produced zone plates and described the application of zone plates to focus extremely narrow bandwidths by nuclear resonance. This report summarizes the presentations of the workshop subgroup on hard x-ray microprobes.« less

Comparison of the effect of resin infiltrant, fluoride varnish, and nano-hydroxy apatite paste on surface hardness and streptococcus mutans adhesion to artificial enamel lesions.

PubMed

Aziznezhad, Mahdiye; Alaghemand, Homayoon; Shahande, Zahra; Pasdar, Nilgoon; Bijani, Ali; Eslami, Abdolreza; Dastan, Zohre

2017-03-01

Dental caries is a major public health problem, and Streptococcus mutans is considered the main causal agent of dental caries. This study aimed to compare the effect of three re-mineralizing materials: resin infiltrant, fluoride varnish, and nano-hydroxy apatite paste on the surface hardness and adhesion of Streptococcus mutans as noninvasive treatments for initial enamel lesions. This experimental study was conducted from December 2015 through March 2016 in Babol, Iran. Artificial enamel lesions were created on 60 enamel surfaces, which were divided into two groups: Group A and Group B (30 subjects per group). Group A was divided into three subgroups (10 samples in each subgroup), including fluoride varnish group, nano-hydroxy apatite paste group (Nano P paste), and resin infiltrant group (Icon-resin). In Group A, the surface hardness of each sample was measured in three stages: First, on an intact enamel (baseline); second, after creating artificial enamel lesions; third, after application of re-mineralizing materials. In Group B, the samples were divided into five subgroups, including intact enamel, demineralized enamel, demineralized enamel treated with fluoride varnish, Nano P paste, and Icon-resin. In Group B, standard Streptococcus mutans bacteria adhesion (PTCC 1683) was examined and reported in terms of colony forming units (CFU/ml). Then, data were analyzed using ANOVA, Kruskal-Wallis, Mann-Whitney, and post hoc tests. In Group A, after treatment with re-mineralizing materials, the Icon-resin group had the highest surface hardness among the studied groups, then the Nano P paste group and fluoride varnish group, respectively (p = 0.035). In Group B, in terms of bacterial adhesion, fluoride varnish group had zero bacterial adhesion level, and then the Nano P paste group, Icon-resin group, intact enamel group, and the de-mineralized enamel group showed bacterial adhesion increasing in order (p < 0.001). According to the study among the examined materials, the resin infiltrant increased the tooth surface hardness as the intact enamel and fluoride varnish had the highest reduction level for bacterial adhesion. Nano P paste had an effect between the two materials, both in increasing surface hardness and reducing bacterial adhesion.

CORRELATION OF HARD X-RAY AND WHITE LIGHT EMISSION IN SOLAR FLARES

DOE Office of Scientific and Technical Information (OSTI.GOV)

Kuhar, Matej; Krucker, Säm; Battaglia, Marina

A statistical study of the correlation between hard X-ray and white light emission in solar flares is performed in order to search for a link between flare-accelerated electrons and white light formation. We analyze 43 flares spanning GOES classes M and X using observations from the Reuven Ramaty High Energy Solar Spectroscopic Imager and Helioseismic and Magnetic Imager. We calculate X-ray fluxes at 30 keV and white light fluxes at 6173 Å summed over the hard X-ray flare ribbons with an integration time of 45 s around the peak hard-X ray time. We find a good correlation between hard X-raymore » fluxes and excess white light fluxes, with a highest correlation coefficient of 0.68 for photons with energy of 30 keV. Assuming the thick target model, a similar correlation is found between the deposited power by flare-accelerated electrons and the white light fluxes. The correlation coefficient is found to be largest for energy deposition by electrons above ∼50 keV. At higher electron energies the correlation decreases gradually while a rapid decrease is seen if the energy provided by low-energy electrons is added. This suggests that flare-accelerated electrons of energy ∼50 keV are the main source for white light production.« less

Study on mechanical and microstructure behavior of submerged arc welding flux using red mud

NASA Astrophysics Data System (ADS)

Dewangan, Rishi; Pandey, Pankaj K.; Upadhyay, Renu

2018-05-01

This paper emphasis on utilization of Red Mud for preparing submerged arc welding flux and study its mechanical and microstructure behavior. Among the six fluxes prepared in the laboratory, Flux no. 1 (basicity 1.106) found to be best due to its running performance, micro hardness and Brinell hardness. The hardness value (HV) of the fluxes was varying from 165.70 to 217.15 at a load of 1000gm respectively. From the micrograph of welded metal, acicular ferrite found to be optimum which helps in increasing the ductility and hardness of the welded material.

A safety study in vitro for the effects of an in-office bleaching system on the integrity of enamel and dentine.

PubMed

Sulieman, M; Addy, M; Macdonald, E; Rees, J S

2004-09-01

The aim of this study was to investigate safety concerns with bleaching procedures by studying the effects of a high concentration hydrogen peroxide (HP) in-surgery bleaching product on enamel and dentine. Flat enamel and dentine samples embedded in epoxy resin were prepared from human third molar teeth. Erosion of enamel: groups of enamel samples were treated with 35% HP then citric acid (CA) or brushing with toothpaste or CA alone and water alone. Enamel Loss was measured using a profilometer. Abrasion/erosion of dentine: groups of dentine specimens were treated as follows: Group 1--brushed with water for 30 min. Group 2--brushed with 35% HP for 30 min. Group 3--power bleached for 30 min and then Group 4--brushed with toothpaste for 1 minute. Group 5--water soaked for 30 min followed by brushing with toothpaste for 1 min. Group 6--orange juice soaked for 30 min followed by brushing with toothpaste for 1 min. Treatment effects were measured using a profilometer. Hardness tests: enamel and dentine specimens were hardness tested using a Wallace indenter prior to and post bleaching. Scanning Electron Microscopy: enamel and dentine specimens were taped and the exposed tissue treated with 35% HP and then studied under scanning electronmicroscopy (SEM). Enamel erosion: bleaching enamel samples had no measurable effect on enamel. Pre-bleaching had no significant effect on subsequent CA erosion or brushing. Abrasion/erosion of dentine: no significant differences were found between treatments 1-5 with little change from baseline detected. Orange juice (Group 6) produced considerable and significantly more erosion than other treatments. Hardness tests: there were no significant changes in hardness values for enamel and dentine. SEM: there was no evidence of any topographical changes to either enamel or dentine. Using one of the highest concentrations of HP for tooth bleaching procedures and maximum likely peroxide exposure, there was no evidence of deleterious effects on enamel or dentine. It must be assumed that studies which reported adverse effects on enamel and or dentine of bleaches reflect not the bleach itself but the pH of the formulation used.

Influence of polymerization time and depth of cure of resin composites determined by Vickers hardness.

PubMed

Lombardini, Marco; Chiesa, Marco; Scribante, Andrea; Colombo, Marco; Poggio, Claudio

2012-11-01

Adequate polymerization of resin composites could be considered as a crucial factor in obtaining good clinical performance, particularly in stress-bearing areas. An insufficient curing degree affects the resin composite's chemical properties The current in vitro study evaluated the influence of polymerization time and depth of cure of six commercial resin composites by Vickers microhardness (VK). SIX RESIN COMPOSITES WERE SELECTED: Three microhybrid (Esthet.X HD, Amaris, Filtek Silorane), two nanohybrid (Grandio, Ceram.X mono), and one nanofilled (Filtek Supreme XT). The VK of the surface was determined by a microhardness tester using a Vickers diamond indenter and a 200 g load applied for 15 s. The bottom to top mean VK ratio was calculated using the formula: Hardness ratio = VK of bottom surface/VK of top surface. Vickers hardness values of test materials during exposure time of 20 and 40 s and depths of cure of 2 and 3 mm were determined and compared. Data were analyzed using analysis of variance (ANOVA) test. For all the tested materials and with all the exposure time periods, hardness ratio was higher than the minimum value indicated in literature (0.8). Exposure time and depth of cure did not affect hardness ratio values for Filtek Silorane, Grandio, and Filtek Supreme XT. Among the materials tested, the nanofilled and the nanohybrid resin composites were rather insensible to thickness variations. Miicrohybrid composites, instead, had features different from one another.

Studying the properties of a predicted tetragonal silicon by first principles

NASA Astrophysics Data System (ADS)

Xue, Han-Yu; Zhang, Can; Pang, Dong-Dong; Huang, Xue-Qian; Lv, Zhen-Long; Duan, Man-Yi

2018-03-01

Silicon is a very important material in many technological fields. It also has a complicated phase diagram of scientific interest. Here we reported a new allotrope of silicon obtained from crystal structure prediction. We studied its electronic, vibrational, dielectric, elastic and hardness properties by first-principles calculations. The results indicate that it is an indirect narrow-band-gap semiconductor. It is dynamically stable with a doubly degenerate infrared-active mode at its Brillouin zone center. Born effective charges of the constituent element are very small, resulting in a negligible ionic dielectric contribution. Calculated elasticity-related quantities imply that it is mechanically stable but anisotropic. There exist slowly increasing stages in the stress-strain curves of this crystal, which make it difficult to estimate the hardness of the crystal by calculating its ideal strengths. Taking advantage of the hardness model proposed by Šimůnek, we obtained a value of 12.0 GPa as its hardness. This value is lower than that of the cubic diamond-structural Si by about 5.5%.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Pan, Y.; Zheng, W.T., E-mail: WTZheng@jlu.edu.cn; Guan, W.M.

The structural formation, elastic properties, hardness and electronic structure of TMB{sub 4} (TM=Cr, Re, Ru and Os) compounds are investigated using first-principles approach. The value of C{sub 22} for these compounds is almost two times bigger than the C{sub 11} and C{sub 33}. The intrinsic hardness, shear modulus and Young's modulus are calculated to be in a sequence of CrB{sub 4}>ReB{sub 4}>RuB{sub 4}>OsB{sub 4}, and the Poisson's ratio and B/G ratio of TMB{sub 4} follow the order of CrB{sub 4}ReB{sub 4}>RuB{sub 4}>OsB{sub 4}. • The trend of hardness for TMB{sub 4} is consistent with the variation of elastic modulus. •more » The C{sub 22} value of TMB{sub 4} is bigger than that of C{sub 11} and C{sub 33}. • The high hardness of TMB{sub 4} is originated from the B–B bonds cage.« less

How to predict the sugariness and hardness of melons: A near-infrared hyperspectral imaging method.

PubMed

Sun, Meijun; Zhang, Dong; Liu, Li; Wang, Zheng

2017-03-01

Hyperspectral imaging (HSI) in the near-infrared (NIR) region (900-1700nm) was used for non-intrusive quality measurements (of sweetness and texture) in melons. First, HSI data from melon samples were acquired to extract the spectral signatures. The corresponding sample sweetness and hardness values were recorded using traditional intrusive methods. Partial least squares regression (PLSR), principal component analysis (PCA), support vector machine (SVM), and artificial neural network (ANN) models were created to predict melon sweetness and hardness values from the hyperspectral data. Experimental results for the three types of melons show that PLSR produces the most accurate results. To reduce the high dimensionality of the hyperspectral data, the weighted regression coefficients of the resulting PLSR models were used to identify the most important wavelengths. On the basis of these wavelengths, each image pixel was used to visualize the sweetness and hardness in all the portions of each sample. Copyright © 2016 Elsevier Ltd. All rights reserved.

Comparison Between Neck and Shoulder Stiffness Determined by Shear Wave Ultrasound Elastography and a Muscle Hardness Meter.

PubMed

Akagi, Ryota; Kusama, Saki

2015-08-01

The goals of this study were to compare neck and shoulder stiffness values determined by shear wave ultrasound elastography with those obtained with a muscle hardness meter and to verify the correspondence between objective and subjective stiffness in the neck and shoulder. Twenty-four young men and women participated in the study. Their neck and shoulder stiffness was determined at six sites. Before the start of the measurements, patients rated their present subjective symptoms of neck and shoulder stiffness on a 6-point verbal scale. At all measurement sites, the correlation coefficients between the values of muscle hardness indices determined by the muscle hardness meter and shear wave ultrasound elastography were not significant. Furthermore, individuals' subjective neck and shoulder stiffness did not correspond to their objective symptoms. These results suggest that the use of shear wave ultrasound elastography is essential to more precisely assess neck and shoulder stiffness. Copyright © 2015 World Federation for Ultrasound in Medicine & Biology. Published by Elsevier Inc. All rights reserved.

Experiments and modeling to characterize microstructure and hardness in 304L

DOE PAGES

Deibler, Lisa Anne; Brown, Arthur; Puskar, Joseph D.

2017-01-12

Drawn 304L stainless steel tubing was subjected to 42 different annealing heat treatments with the goal of initializing a microstructural model to select a heat treatment to soften the tubing from a hardness of 305 Knoop to 225–275 Knoop. The amount of recrystallization and grain size caused by 18 heat treatments were analyzed via optical microscopy and image analysis, revealing the full range of recrystallization from 0 to 100%. The formation of carbides during the longer duration and higher-temperature heat treatments was monitored via transmission electron microscope evaluation. The experimental results informed a model which includes recovery, recrystallization, and grainmore » growth to predict microstructure and hardness. After initialization of the model, it was able to predict hardness with a R 2 value of 0.95 and recrystallization with an R 2 value of 0.99. As a result, the model was then utilized in the design and testing of a heat treatment to soften the tubing.« less

Microstructural features of friction stir welded dissimilar Aluminium alloys AA2219-AA7475

NASA Astrophysics Data System (ADS)

Zaman Khan, Noor; Ubaid, Mohammed; Siddiquee, Arshad Noor; Khan, Zahid A.; Al-Ahmari, Abdulrahman; Chen, Xizhang; Haider Abidi, Mustufa

2018-05-01

High strength, good corrosion resistance, light weight make aluminium alloys a material of choice in many industrial sectors like aerospace, marine etc. Problems associated with welding of these alloys by fusion welding processes restricted their use in various industries. Friction stir welding (FSW), a clean solid-state joining process, easily overcomes various difficulties encountered during conventional fusion welding processes. In the present work, the effect of rotational speed (710 rpm, 900 rpm and 1120 rpm) on micro-hardness distribution and microstructure of FSWed dissimilar aluminium alloy joints were analyzed. Plates of AA7475-T761 and AA2219-O having thickness of 2.5 mm were welded by fixing AA7475 on retreating side (RS) and AA2219 on advancing side (AS). Welded joints were characterized by Vickers micro-hardness testing, scanning electron microscopy (SEM) and optical microscopy (OM). Results revealed that rotational speed significantly affects the micro-hardness due to increase in grain size, coarsening and dissolution of strengthening precipitates and re-precipitation. Higher micro-hardness values were observed in stir zone due to grain refinement and re-precipitation. Minimum micro-hardness value was observed at the TMAZ/HAZ of advancing side due to thermal softening.

Effect of Ar ion on the surface properties of low density polyethylene

NASA Astrophysics Data System (ADS)

Zaki, M. F.

2016-04-01

In this paper, low-density polyethylene (LDPE) was irradiated by argon ion with different fluences up to 1015ions/cm2. The optical, chemical and hardness properties have been investigated using UV-Vis spectroscopy, Fourier transform infrared spectroscopy (FTIR), scanning electron microscope (SEM) and micro-indentation tester, respectively. The results showed the ion beam bombardment induced decreases in the transmittance of the irradiated polymer samples. This change in transmittance can be attributed to the formation of conjugated bonds i.e. possible formation of defects and/or carbon clusters. The indirect optical band gap decreased from 3.0 eV for the pristine sample to 2.3 eV for that sample irradiated with the highest fluence of the Ar ion beam. Furthermore, the number of carbon atoms and clusters increased with increasing Ar ion fluences. FTIR spectra showed the formation of new bands of the bombarded polymer samples. Furthermore, polar groups were created on the surface of the irradiated samples which refer to the increase of the hydrophilic nature of the surface of the irradiated samples. The Vicker's hardness increased from 4.9 MPa for the pristine sample to 17.9 MPa for those bombarded at the highest fluence. This increase is attributed to the increase in the crosslinking and alterations of the bombarded surface into hydrogenated amorphous carbon, which improves the hardness of the irradiated samples. The bombarded LDPE surfaces may be used in special applications to the field of the micro-electronic devices and shock absorbers.

Microstructural characterization of an SA508–309L/308L–316L domestic dissimilar metal welded safe-end joint

DOE Office of Scientific and Technical Information (OSTI.GOV)

Ming, Hongliang; Zhang, Zhiming; Wang, Jianqiu, E-mail: wangjianqiu@imr.ac.cn

2014-11-15

The microstructure of an SA508–309L/308L–316L domestic dissimilar metal welded safe-end joint was characterized in this work by optical microscopy, scanning electron microscopy (with electron back scattering diffraction) and micro-hardness testing. Epitaxial growth and competitive growth are evident in the 308L–316L fusion boundary regions. A martensite layer, carbon-depleted zones, and type-II and type-I boundaries are found in the SA508–309L fusion boundary regions, while only martensite and austenite mixed zones are observed in the SA508–308L fusion boundary regions. The microstructure near the fusion boundary and the microstructure transition in the SA508 heat affected zone are quite complex. Both for SA508–309L/308L and 308L–316L,more » the highest residual strain is located on the outside of the weldment. The residual strain and the grain boundary character distribution change with increasing distance from the fusion boundary in the heat affected zone of 316L. Micro-hardness measurements also reveal non-uniform mechanical properties across the weldment. - Highlights: • The microstructure of SA508 HAZ, especially near the FB, is very complex. • The outside of the dissimilar metal welded joint has the highest residual. • The micro-hardness distributions along the DMWJ are non-uniform.« less

The effect of filler loading and morphology on the mechanical properties of contemporary composites.

PubMed

Kim, Kyo-Han; Ong, Joo L; Okuno, Osamu

2002-06-01

Little information exists regarding the filler morphology and loading of composites with respect to their effects on selected mechanical properties and fracture toughness. The objectives of this study were to: (1) classify commercial composites according to filler morphology, (2) evaluate the influence of filler morphology on filler loading, and (3) evaluate the effect of filler morphology and loading on the hardness, flexural strength, flexural modulus, and fracture toughness of contemporary composites. Field emission scanning electron microscopy/energy dispersive spectroscopy was used to classify 3 specimens from each of 14 commercial composites into 4 groups according to filler morphology. The specimens (each 5 x 2.5 x 15 mm) were derived from the fractured remnants after the fracture toughness test. Filler weight content was determined by the standard ash method, and the volume content was calculated using the weight percentage and density of the filler and matrix components. Microhardness was measured with a Vickers hardness tester, and flexural strength and modulus were measured with a universal testing machine. A 3-point bending test (ASTM E-399) was used to determine the fracture toughness of each composite. Data were compared with analysis of variance followed by Duncan's multiple range test, both at the P<.05 level of significance. The composites were classified into 4 categories according to filler morphology: prepolymerized, irregular-shaped, both prepolymerized and irregular-shaped, and round particles. Filler loading was influenced by filler morphology. Composites containing prepolymerized filler particles had the lowest filler content (25% to 51% of filler volume), whereas composites containing round particles had the highest filler content (59% to 60% of filler volume). The mechanical properties of the composites were related to their filler content. Composites with the highest filler by volume exhibited the highest flexural strength (120 to 129 MPa), flexural modulus (12 to 15 GPa), and hardness (101 to 117 VHN). Fracture toughness was also affected by filler volume, but maximum toughness was found at a threshold level of approximately 55% filler volume. Within the limitations of this study, the commercial composites tested could be classified by their filler morphology. This property influenced filler loading. Both filler morphology and filler loading influenced flexural strength, flexural modulus, hardness, and fracture toughness.

Value of Progression of Coronary Artery Calcification for Risk Prediction of Coronary and Cardiovascular Events: Result of the HNR Study (Heinz Nixdorf Recall).

PubMed

Lehmann, Nils; Erbel, Raimund; Mahabadi, Amir A; Rauwolf, Michael; Möhlenkamp, Stefan; Moebus, Susanne; Kälsch, Hagen; Budde, Thomas; Schmermund, Axel; Stang, Andreas; Führer-Sakel, Dagmar; Weimar, Christian; Roggenbuck, Ulla; Dragano, Nico; Jöckel, Karl-Heinz

2018-02-13

Computed tomography (CT) allows estimation of coronary artery calcium (CAC) progression. We evaluated several progression algorithms in our unselected, population-based cohort for risk prediction of coronary and cardiovascular events. In 3281 participants (45-74 years of age), free from cardiovascular disease until the second visit, risk factors, and CTs at baseline (b) and after a mean of 5.1 years (5y) were measured. Hard coronary and cardiovascular events, and total cardiovascular events including revascularization, as well, were recorded during a follow-up time of 7.8±2.2 years after the second CT. The added predictive value of 10 CAC progression algorithms on top of risk factors including baseline CAC was evaluated by using survival analysis, C-statistics, net reclassification improvement, and integrated discrimination index. A subgroup analysis of risk in CAC categories was performed. We observed 85 (2.6%) hard coronary, 161 (4.9%) hard cardiovascular, and 241 (7.3%) total cardiovascular events. Absolute CAC progression was higher with versus without subsequent coronary events (median, 115 [Q1-Q3, 23-360] versus 8 [0-83], P <0.0001; similar for hard/total cardiovascular events). Some progression algorithms added to the predictive value of baseline CT and risk assessment in terms of C-statistic or integrated discrimination index, especially for total cardiovascular events. However, CAC progression did not improve models including CAC 5y and 5-year risk factors. An excellent prognosis was found for 921 participants with double-zero CAC b =CAC 5y =0 (10-year coronary and hard/total cardiovascular risk: 1.4%, 2.0%, and 2.8%), which was for participants with incident CAC 1.8%, 3.8%, and 6.6%, respectively. When CAC b progressed from 1 to 399 to CAC 5y ≥400, coronary and total cardiovascular risk were nearly 2-fold in comparison with subjects who remained below CAC 5y =400. Participants with CAC b ≥400 had high rates of hard coronary and hard/total cardiovascular events (10-year risk: 12.0%, 13.5%, and 30.9%, respectively). CAC progression is associated with coronary and cardiovascular event rates, but adds only weakly to risk prediction. What counts is the most recent CAC value and risk factor assessment. Therefore, a repeat scan >5 years after the first scan may be of additional value, except when a double-zero CT scan is present or when the subjects are already at high risk. © 2017 The Authors.

High hardness in the biocompatible intermetallic compound β-Ti3Au

PubMed Central

Svanidze, Eteri; Besara, Tiglet; Ozaydin, M. Fevsi; Tiwary, Chandra Sekhar; Wang, Jiakui K.; Radhakrishnan, Sruthi; Mani, Sendurai; Xin, Yan; Han, Ke; Liang, Hong; Siegrist, Theo; Ajayan, Pulickel M.; Morosan, E.

2016-01-01

The search for new hard materials is often challenging, but strongly motivated by the vast application potential such materials hold. Ti3Au exhibits high hardness values (about four times those of pure Ti and most steel alloys), reduced coefficient of friction and wear rates, and biocompatibility, all of which are optimal traits for orthopedic, dental, and prosthetic applications. In addition, the ability of this compound to adhere to ceramic parts can reduce both the weight and the cost of medical components. The fourfold increase in the hardness of Ti3Au compared to other Ti–Au alloys and compounds can be attributed to the elevated valence electron density, the reduced bond length, and the pseudogap formation. Understanding the origin of hardness in this intermetallic compound provides an avenue toward designing superior biocompatible, hard materials. PMID:27453942

High hardness in the biocompatible intermetallic compound β-Ti3Au.

PubMed

Svanidze, Eteri; Besara, Tiglet; Ozaydin, M Fevsi; Tiwary, Chandra Sekhar; Wang, Jiakui K; Radhakrishnan, Sruthi; Mani, Sendurai; Xin, Yan; Han, Ke; Liang, Hong; Siegrist, Theo; Ajayan, Pulickel M; Morosan, E

2016-07-01

The search for new hard materials is often challenging, but strongly motivated by the vast application potential such materials hold. Ti3Au exhibits high hardness values (about four times those of pure Ti and most steel alloys), reduced coefficient of friction and wear rates, and biocompatibility, all of which are optimal traits for orthopedic, dental, and prosthetic applications. In addition, the ability of this compound to adhere to ceramic parts can reduce both the weight and the cost of medical components. The fourfold increase in the hardness of Ti3Au compared to other Ti-Au alloys and compounds can be attributed to the elevated valence electron density, the reduced bond length, and the pseudogap formation. Understanding the origin of hardness in this intermetallic compound provides an avenue toward designing superior biocompatible, hard materials.

Novel hard compositions and methods of preparation

DOEpatents

Sheinberg, H.

1981-02-03

Novel very hard compositions of matter are prepared by using in all embodiments only a minor amount of a particular carbide (or materials which can form the carbide in situ when subjected to heat and pressure); and no strategic cobalt is needed. Under a particular range of conditions, densified compositions of matter of the invention are prepared having hardnesses on the Rockwell A test substantially equal to the hardness of pure tungsten carbide and to two of the hardest commercial cobalt-bonded tungsten carbides. Alternately, other compositions of the invention which have slightly lower hardnesses than those described above in one embodiment also possess the advantage of requiring no tungsten and in another embodiment possess the advantage of having a good fracture toughness value.

Group electronegativity for prediction of materials hardness.

PubMed

Li, Keyan; Yang, Peng; Niu, Lingxiao; Xue, Dongfeng

2012-06-28

We have developed a method to predict the hardness of materials containing ultrastrong anionic polyhedra, dense atomic clusters, and layers stacked through van der Waals bonds on the basis of group electronegativity. By considering these polyhedra, clusters, and layers as groups that behave as rigid unities like superatoms bonding to other atoms or groups, the hardness values of materials such as oxysalts, T-carbon, and graphite were quantitatively calculated, and the results are consistent with the available experiments. We found that the hardness of materials containing these artificial groups is determined by the bonds between the groups and other atoms or groups, rather than by the weakest bonds. This work sheds light on the nature of materials hardness and the design of novel inorganic crystal materials.

Method of determining elastic and plastic mechanical properties of ceramic materials using spherical indenters

DOEpatents

Adler, Thomas A.

1996-01-01

The invention pertains a method of determining elastic and plastic mechanical properties of ceramics, intermetallics, metals, plastics and other hard, brittle materials which fracture prior to plastically deforming when loads are applied. Elastic and plastic mechanical properties of ceramic materials are determined using spherical indenters. The method is most useful for measuring and calculating the plastic and elastic deformation of hard, brittle materials with low values of elastic modulus to hardness.

Hardness map of human meta tarsals and phalanges of toes.

PubMed

Manarvi, Irfan

2016-08-01

Predicting location of fracture in human bones has been a keen area of research for the past few decades. A variety of tests for hardness, deformation and strain field measurement have been conducted in the past; but considered insufficient due to various limitations. Researchers therefore have proposed further studies due to inaccuracies in measurement methods, testing machines and experimental errors. Advancement and availability of hardware, measuring instrumentation and testing machines can now provide remedies to these limitations. Human foot is a critical part of body exposed to various forces throughout its life. A number of products are developed for using over it for protection and care. Which many times do not provide sufficient protection and may itself become a source of stress due to non-consideration of the delicacy of bones in the feet. A continuous strain or overloading on feet may occur resulting to discomfort and even fracture. Not knowing how the hardness is spread all over the Meta tarsals and phalanges is one of major contributory factor for unsatisfactory design of foot protection products. This paper provides a complete hardness distribution map developed by experimental testing of all the Meta tarsals and Phalanges of toes for a typical human foot. The bones were taken from two left feet of a 40 and 42 year old male cadaver. These were dehydrated prior to measurements of hardness using Leeb hardness testing method. Hardness was measured around the circumference of a bone as well as along its length. Hardness values can be related to tensile strength of the bones to predict possible values of stress that could be borne by these bones. Results may also be used for design and developing various accessories for human feet health care and comfort.

SUPPLEMENTARY COMPARISON: Final report of the bilateral comparison APMP.M.H-S2 of hardness measurement for Rockwell scales A and B between PTB and NIMT

NASA Astrophysics Data System (ADS)

Sanponpute, Tassanai; Meesaplak, Apichaya; Herrmann, Konrad; Menelao, Febo

2009-01-01

The bilateral comparison APMP.M.H-S2 of hardness measurement for Rockwell scales A and B was arranged by the National Institute of Metrology of Thailand, NIMT, as the pilot laboratory, comparing with Physikalisch-Technische Bundesanstalt of Germany, PTB. The objective of this comparison was to confirm the calibration and measurement capabilities of NIMT in hardness measurement. The period of measurement covered March to August 2009. There were two sets of artefacts: scale A artefact set and scale B artefact set. The scale A artefact set consisted of seven hardness blocks: 35 HRA, 40 HRA, 55 HRA, 60 HRA, 70 HRA, 80 HRA, 85 HRA. The artefact set for scale B consisted of nine hardness blocks: 25 HRB, 30 HRB, 40 HRB, 50 HRB, 60 HRB, 70 HRB, 80 HRB, 90 HRB, 100 HRB. Laboratories had to ensure that the primary Rockwell hardness machines passed the verification process according to ISO 6508-3. Then participants measured the hardness value by making ten indentations in a designated area of each artefact block. Hardness measurement results and uncertainty budget were then reported to the pilot laboratory and were used to compute the degrees of equivalence in terms of the Comparison Reference Value (CRV) and En ratio. Main text. To reach the main text of this paper, click on Final Report. Note that this text is that which appears in Appendix B of the BIPM key comparison database kcdb.bipm.org/. The final report has been peer-reviewed and approved for publication by APMP, according to the provisions of the CIPM Mutual Recognition Arrangement (MRA).

Human bone hardness seems to depend on tissue type but not on anatomical site in the long bones of an old subject.

PubMed

Ohman, Caroline; Zwierzak, Iwona; Baleani, Massimiliano; Viceconti, Marco

2013-02-01

It has been hypothesised that among different human subjects, the bone tissue quality varies as a function of the bone segment morphology. The aim of this study was to assess and compare the quality, evaluated in terms of hardness of packages of lamellae, of cortical and trabecular bones, at different anatomical sites within the human skeleton. The contralateral six long bones of an old human subject were indented at different levels along the diaphysis and at both epiphyses of each bone. Hardness value, which is correlated to the degree of mineralisation, of both cortical and trabecular bone tissues was calculated for each indentation location. It was found that the cortical bone tissue was harder (+18%) than the trabecular one. In general, the bone hardness was found to be locally highly heterogeneous. In fact, considering one single slice obtained for a bone segment, the coefficient of variation of the hardness values was up to 12% for cortical bone and up to 17% for trabecular bone. However, the tissue hardness was on average quite homogeneous within and among the long bones of the studied donor, although differences up to 9% among levels and up to 7% among bone segments were found. These findings seem not to support the mentioned hypothesis, at least not for the long bones of an old subject.

Pseudo hard-sphere potential for use in continuous molecular-dynamics simulation of spherical and chain molecules.

PubMed

Jover, J; Haslam, A J; Galindo, A; Jackson, G; Müller, E A

2012-10-14

We present a continuous pseudo-hard-sphere potential based on a cut-and-shifted Mie (generalized Lennard-Jones) potential with exponents (50, 49). Using this potential one can mimic the volumetric, structural, and dynamic properties of the discontinuous hard-sphere potential over the whole fluid range. The continuous pseudo potential has the advantage that it may be incorporated directly into off-the-shelf molecular-dynamics code, allowing the user to capitalise on existing hardware and software advances. Simulation results for the compressibility factor of the fluid and solid phases of our pseudo hard spheres are presented and compared both to the Carnahan-Starling equation of state of the fluid and published data, the differences being indistinguishable within simulation uncertainty. The specific form of the potential is employed to simulate flexible chains formed from these pseudo hard spheres at contact (pearl-necklace model) for m(c) = 4, 5, 7, 8, 16, 20, 100, 201, and 500 monomer segments. The compressibility factor of the chains per unit of monomer, m(c), approaches a limiting value at reasonably small values, m(c) < 50, as predicted by Wertheim's first order thermodynamic perturbation theory. Simulation results are also presented for highly asymmetric mixtures of pseudo hard spheres, with diameter ratios of 3:1, 5:1, 20:1 over the whole composition range.

The fractional urinary fluoride excretion of adults consuming naturally and artificially fluoridated water and the influence of water hardness: a randomized trial.

PubMed

Villa, A; Cabezas, L; Anabalón, M; Rugg-Gunn, A

2009-09-01

To assess whether there was any significant difference in the average fractional urinary fluoride excretion (FUFE) values among adults consuming (NaF) fluoridated Ca-free water (reference water), naturally fluoridated hard water and an artificially (H2SiF6) fluoridated soft water. Sixty adult females (N=20 for each treatment) participated in this randomized, double-blind trial. The experimental design of this study provided an indirect estimation of the fluoride absorption in different types of water through the assessment of the fractional urinary fluoride excretion of volunteers. Average daily FUFE values (daily amount of fluoride excreted in urine/daily total fluoride intake) were not significantly different between the three treatments (Kruskal-Wallis; p = 0.62). The average 24-hour FUFE value (n=60) was 0.69; 95% C.I. 0.65-0.73. The results of this study suggest that the absorption of fluoride is not affected by water hardness.

Attributing a monetary value to patients' time: A contingent valuation approach.

PubMed

van den Berg, Bernard; Gafni, Amiram; Portrait, France

2017-04-01

It is hard to ignore the importance of patient time investment in the production of health since the influential paper by Grossman (1972). Patients' time includes time to admission, travel time, waiting time, and treatment time and can be substantial. Patients' time is, however, often ignored in economic analyses. This may lead to biased results and inappropriate policy recommendations, which may eventually influence patients' health, wellbeing and welfare. How to value patient time is not straightforward. Although there is some emerging literature on the monetary valuation of patient time, an important challenge remains to develop an approach that can be used to monetarily value time of patients not participating in the labour market. We aim to contribute to the health economics literature by describing and empirically illustrating how to monetarily value the time of patients not participating in the labour market comprehensively, using the contingent valuation method. It is worth noting that our method can also be applied to people participating in the labour market. This paper describes the development of the contingent valuation survey. We apply our survey approach to a sample of 238 Dutch patients not participating in the labour market: n = 107 Radiotherapy department (data collected between November 2011 and January 2013); n = 44 Rehabilitation department (March 2012-May 2012); n = 87 Orthopaedics department (January to June 2013). Results show that those patients value waiting time the highest (€30.10 per hour) and value travel and treatment time equally with respectively €13.20 and €13.32 per hour. This paper encourages future empirical research refining and applying the developed survey methodology to create more data on how other subgroups of individuals value their patients' time. Copyright © 2017 Elsevier Ltd. All rights reserved.

Fourier Transform Infrared Spectroscopic Studies Of Wheat In The Mid Infrared

NASA Astrophysics Data System (ADS)

Olinger, Jill M.; Griffiths, Peter R.

1989-12-01

Official grain standards of the United States state that wheat may be divided into seven classes which are: Durum, Red Durum, Hard Red Spring, Hard Red Winter, Soft Red Winter, White, and Mixed.1 Most end uses of wheat involve converting the grain into flour through one of a variety of grinding methods. The quality of wheat-based products is often very dependent upon the type or class of wheat which was used to make the flour. Pasta products, for example, are made almost exclusively from the flour of durum wheats, which are the hardest of the wheats listed above. The highest quality breads are produced using flour from wheats classed as hard, whereas cakes, cookies and pastries are considered best when flour from wheats classed as soft are used. It is obvious then that the capability of determining the class of a particular wheat, especially with respect to hardness, is of economic importance to growers, processors, and merchants of wheat and wheat products. Hardness has been measured in many different ways 2-5 but, as of yet, no one method has become the method of choice. This paper reports on the use of principal components analysis (PCA) of mid infrared diffuse reflectance (DR) spectra of diluted ground wheats to aid in the classification of those wheats with respect to their hardness. The theory and mathematics involved in a principal component analysis have been described elsewhere.9

Monte Carlo study of four dimensional binary hard hypersphere mixtures

NASA Astrophysics Data System (ADS)

Bishop, Marvin; Whitlock, Paula A.

2012-01-01

A multithreaded Monte Carlo code was used to study the properties of binary mixtures of hard hyperspheres in four dimensions. The ratios of the diameters of the hyperspheres examined were 0.4, 0.5, 0.6, and 0.8. Many total densities of the binary mixtures were investigated. The pair correlation functions and the equations of state were determined and compared with other simulation results and theoretical predictions. At lower diameter ratios the pair correlation functions of the mixture agree with the pair correlation function of a one component fluid at an appropriately scaled density. The theoretical results for the equation of state compare well to the Monte Carlo calculations for all but the highest densities studied.

Evaluating the Relationships Between NTNU/SINTEF Drillability Indices with Index Properties and Petrographic Data of Hard Igneous Rocks

NASA Astrophysics Data System (ADS)

Aligholi, Saeed; Lashkaripour, Gholam Reza; Ghafoori, Mohammad; Azali, Sadegh Tarigh

2017-11-01

Thorough and realistic performance predictions are among the main requisites for estimating excavation costs and time of the tunneling projects. Also, NTNU/SINTEF rock drillability indices, including the Drilling Rate Index™ (DRI), Bit Wear Index™ (BWI), and Cutter Life Index™ (CLI), are among the most effective indices for determining rock drillability. In this study, brittleness value (S20), Sievers' J-Value (SJ), abrasion value (AV), and Abrasion Value Cutter Steel (AVS) tests are conducted to determine these indices for a wide range of Iranian hard igneous rocks. In addition, relationships between such drillability parameters with petrographic features and index properties of the tested rocks are investigated. The results from multiple regression analysis revealed that the multiple regression models prepared using petrographic features provide a better estimation of drillability compared to those prepared using index properties. Also, it was found that the semiautomatic petrography and multiple regression analyses provide a suitable complement to determine drillability properties of igneous rocks. Based on the results of this study, AV has higher correlations with studied mineralogical indices than AVS. The results imply that, in general, rock surface hardness of hard igneous rocks is very high, and the acidic igneous rocks have a lower strength and density and higher S20 than those of basic rocks. Moreover, DRI is higher, while BWI is lower in acidic igneous rocks, suggesting that drill and blast tunneling is more convenient in these rocks than basic rocks.

Alternate approach for calculating hardness based on residual indentation depth: Comparison with experiments

NASA Astrophysics Data System (ADS)

Ananthakrishna, G.; K, Srikanth

2018-03-01

It is well known that plastic deformation is a highly nonlinear dissipative irreversible phenomenon of considerable complexity. As a consequence, little progress has been made in modeling some well-known size-dependent properties of plastic deformation, for instance, calculating hardness as a function of indentation depth independently. Here, we devise a method of calculating hardness by calculating the residual indentation depth and then calculate the hardness as the ratio of the load to the residual imprint area. Recognizing the fact that dislocations are the basic defects controlling the plastic component of the indentation depth, we set up a system of coupled nonlinear time evolution equations for the mobile, forest, and geometrically necessary dislocation densities. Within our approach, we consider the geometrically necessary dislocations to be immobile since they contribute to additional hardness. The model includes dislocation multiplication, storage, and recovery mechanisms. The growth of the geometrically necessary dislocation density is controlled by the number of loops that can be activated under the contact area and the mean strain gradient. The equations are then coupled to the load rate equation. Our approach has the ability to adopt experimental parameters such as the indentation rates, the geometrical parameters defining the Berkovich indenter, including the nominal tip radius. The residual indentation depth is obtained by integrating the Orowan expression for the plastic strain rate, which is then used to calculate the hardness. Consistent with the experimental observations, the increasing hardness with decreasing indentation depth in our model arises from limited dislocation sources at small indentation depths and therefore avoids divergence in the limit of small depths reported in the Nix-Gao model. We demonstrate that for a range of parameter values that physically represent different materials, the model predicts the three characteristic features of hardness, namely, increase in the hardness with decreasing indentation depth, and the linear relation between the square of the hardness and the inverse of the indentation depth, for all but 150 nm, deviating for smaller depths. In addition, we also show that it is straightforward to obtain optimized parameter values that give good fit to the hardness data for polycrystalline cold worked copper and single crystals of silver.

Groundwater quality in the Lake Champlain Basin, New York, 2009

USGS Publications Warehouse

Nystrom, Elizabeth A.

2011-01-01

Water was sampled from 20 production and domestic wells from August through November 2009 to characterize groundwater quality in the Lake Champlain Basin in New York. Of the 20 wells sampled, 8 were completed in sand and gravel, and 12 were completed in bedrock. The samples were collected and processed by standard U.S. Geological Survey procedures and were analyzed for 147 physiochemical properties and constituents, including major ions, nutrients, trace elements, pesticides, volatile organic compounds (VOCs), radionuclides, and indicator bacteria. Water quality in the study area is generally good, but concentrations of some constituents equaled or exceeded current or proposed Federal or New York State drinking-water standards; these were color (1 sample), pH (3 samples), sodium (3 samples), total dissolved solids (4 samples), iron (4 samples), manganese (3 samples), gross alpha radioactivity (1 sample), radon-222 (10 samples), and bacteria (5 samples). The pH of all samples was typically neutral or slightly basic (median 7.1); the median water temperature was 9.7°C. The ions with the highest median concentrations were bicarbonate [median 158 milligrams per liter (mg/L)] and calcium (median 45.5 mg/L). Groundwater in the study area is soft to very hard, but more samples were hard or very hard (121 mg/L or more as CaCO3) than were moderately hard or soft (120 mg/L or less as CaCO3); the median hardness was 180 mg/L as CaCO3. The maximum concentration of nitrate plus nitrite was 3.79 mg/L as nitrogen, which did not exceed established drinking-water standards for nitrate plus nitrite (10 mg/L as nitrogen). The trace elements with the highest median concentrations were strontium (median 202 micrograms per liter [μg/L]), and iron (median 55 μg/L in unfiltered water). Six pesticides and pesticide degradates, including atrazine, fipronil, disulfoton, prometon, and two pesticide degradates, CIAT and desulfinylfipronil, were detected among five samples at concentrations of 0.02 μg/L or less; they included herbicides, herbicide degradates, insecticides, and insecticide degradates. Six VOCs were detected among six samples; these included a solvent, the gasoline additive methyl tert-butyl ether (MTBE), and four trihalomethanes. The highest radon-222 activities were in samples from crystalline bedrock wells (maximum 4,100 picocuries per liter [pCi/L]); half of all samples exceeded a proposed U.S. Environmental Protection Agency (USEPA) drinking-water standard of 300 pCi/L. Total coliform bacteria were detected in five samples, fecal coliform bacteria were detected in one sample, and Escherichia coli (E. coli) were not detected in any sample.

Morphometric, densitometric and mechanical properties of mandibular deciduous teeth in 5-month-old Polish Merino sheep

PubMed Central

2014-01-01

Background Caries, enamel hypoplasia, molar incisor hipomineralization, amylogenesis imperfecta, dentine dysplasia, hypophosphatasia and other dental disorders lead to tooth mineralization disturbances and structural abnormalities, decreasing masticatory organ functions. Dental disorders in sheep can lead to premature slaughter before they have attained final stage of their reproductive life and induce economic loss due to high flock replacement costs. Growth rate, health status and meat quality of sheep depends on tooth properties and quality determining in large extent efficiency of the masticatory apparatus and initial food break up. Considering lack of basic anatomical and physiological data on teeth properties in sheep, the aim of the study was to evaluate morphometric, densitometric and mechanical traits of deciduous mandibular incisor, canine and the second premolar obtained at the slaughter age of 5 months of life. Results The obtained results have shown the highest values of weight, total tooth volume, enamel volume and dentine volume in second premolar. Morphometric and mechanical parameters of incisors reached the highest values in first incisor and decreased gradually in second and third incisor, and in canine. Densitometric measurements have not revealed significant differences of the volumetric tooth mineral density in hard dental tissues between the investigated teeth. Conclusions In conclusion, proposed methodological approach is noninvasive since the deciduous teeth undergo physiological replacement with permanent teeth. Deciduous teeth can be easy collected for analyses from large animal population and may reflect mineral status and metabolism resulting from postnatal growth and development of the whole flock. In individual cases, evaluation of properties of deciduous teeth may serve for breeding selection and further reproduction of sheep possessing favorable traits of teeth and better masticatory system functions. PMID:24548814

Magnetic and structural properties of rapidly quenched Nd-Fe-Co-Ge-B alloys

NASA Astrophysics Data System (ADS)

Beitollahi, A.; Gholamipour, R.; Marghusian, V. K.; Andreev, S. V.; Bogatkin, A. N.; Duragin, S. S.; Kozlov, A. N.; Kudrevatykh, N. V.; Bogdanov, S. G.; Pirogov, A. N.

2006-12-01

We have studied the structure and magnetic properties of some rapidly quenched and subsequently annealed alloys prepared by centrifugal method with a composition (in wt %) Nd(29.5), Co(6), B(1.1), Ge (x), Fe(balance) with x=0.0, 0.2, 0.4, 0.6, 0.8, 1.0 (wt %) for Ge. Based on X-ray diffraction (XRD), elastic neutron diffraction, and small-angle neutron scattering (SANS), the formation of partially crystallized main hard magnetic 2:14:1 (Φ) phase in the amorphous matrix was detected for all as-spun samples. The size of the clusters formed for the sample with 1 wt % Ge determined based on SANS profiles was about 10 nm. It was shown that the addition of Ge shifts the maximum crystallization peak of the main 2:14:1 phase to higher temperatures. The variation of the magnitudes of different magnetic parameters such as i H c and M s versus Ge concentration for as-spun samples can be possibly related to the different rate of crystallization of the 2:14:1 phase formed. Further, for the samples doped with 0.8 and 1.0 wt % Ge and annealed at 760°C for 5 min the formation of some extra phases such as Nd5Ge3, NdFe2, NdB4, as well as α-Fe was detected by XRD. The magnetic measurements carried out using a vibrating-sample magnetometer (VSM) for these samples also supported the XRD data obtained. While the highest values of coercivity i H c = 772 kA/m were obtained for the annealed samples without Ge, the highest value of σr = 69 emu/g was also obtained for the samples substituted with 0.8 wt % Ge without an appreciable reduction in i H c.

Evaluating the role of ion composition on the toxicity of copper to Ceriodaphnia dubia in very hard waters.

PubMed

Gensemer, Robert W; Naddy, Rami B; Stubblefield, William A; Hockett, J Russell; Santore, Robert; Paquin, Paul

2002-09-01

The mitigating effect of increasing hardness on metal toxicity is reflected in water quality criteria in the United States over the range of 25-400 mgl(-1) (as CaCO(3)). However, waters in the arid west of the US frequently exceed 400 mgl(-1) hardness, and the applicability of hardness-toxicity relationships in these waters is unknown. Acute toxicity tests with Ceriodaphnia dubia were conducted at hardness levels ranging from approximately 300 to 1,200 mgl(-1) using reconstituted waters that mimic two natural waters with elevated hardness: (1) alkaline desert southwest streams (Las Vegas Wash, NV), and (2) low alkalinity waters from a CaSO(4)-treated mining effluent in Colorado. The moderately-alkaline EPA synthetic hard water was also included for comparison. Copper toxicity did not consistently vary as a function of hardness, but likely as a function of other water quality characteristics (e.g., alkalinity or other correlated factors). The hardness equations used in regulatory criteria, therefore, may not provide an accurate level of protection against copper toxicity in all types of very hard waters. However, the mechanistic Biotic ligand model generally predicted copper toxicity within +/-2X of observed EC(50) values, and thus may be more useful than hardness for modifying water quality criteria.

Antecedents of Adolescent Initiation into Stages of Drug Use: A Developmental Analysis

ERIC Educational Resources Information Center

Kandel, Denise B.; And Others

1978-01-01

Predictors associated with adolescents' initiation into three cumulative stages of drug use--hard liquor, marihuana, and other illicit drugs--were investigated. The strongest predictors were prior involvement in deviant behavior (hard liquor); peer influence, and adolescent beliefs and values (marihuana); and relationship to parents, and…

77 FR 1591 - Energy Conservation Program: Test Procedure for Automatic Commercial Ice Makers

Federal Register 2010, 2011, 2012, 2013, 2014

2012-01-11

.... Establishment of a Metric for Potable Water Used to Produce Ice 6. Standardization of Water Hardness for Measurement of Potable Water Used in Making Ice 7. Testing of Batch Type Ice Makers at the Highest Purge..., AHRI Standard 810 with Addendum 1. This addendum revised the definition of ``potable water use rate...

The Big Rocks: Priority Management for Principals

ERIC Educational Resources Information Center

Marshall, Kim

2008-01-01

How can a dedicated principal work really, really hard but fail to get significant gains in student achievement? The answer is obvious: by spending too much time on the wrong things and not enough on the right things. The principal's number-one priority is zeroing in on the highest-priority activities for bringing all students to high levels of…

Effect of Addition of Natural Antioxidants on the Shelf-Life of “Chorizo”, a Spanish Dry-Cured Sausage

PubMed Central

Pateiro, Mirian; Bermúdez, Roberto; Lorenzo, José Manuel; Franco, Daniel

2015-01-01

The dose effect of the addition of natural antioxidants (tea, chestnut, grape seed and beer extracts) on physicochemical, microbiological changes and on oxidative stability of dry-cured “chorizo”, as well as their effect during the storage under vacuum conditions was evaluated. Color parameters were significantly (p < 0.05) affected by the addition of antioxidants so that samples that contained antioxidants were more effective in maintaining color. The improving effects were dose-dependent with highest values with the dose of 50 mg/kg during ripening and depend on the extract during vacuum packaging. Addition of antioxidants decreased (p < 0.05) the oxidation, showing thiobarbituric acid reactive substances (TBARS) values below 0.4 mg MDA/kg. Natural antioxidants matched or even improved the results obtained for butylated hydroxytoluene (BHT). Regarding texture profile analysis (TPA) analysis, hardness values significantly (p < 0.001) decreased with the addition of antioxidants, obtaining the lower results with the dose of 200 mg/kg both during ripening and vacuum packaging. Antioxidants reduced the counts of total viable counts (TVC), lactic acid bacteria (LAB), mold and yeast. Free fatty acid content during ripening and under vacuum conditions showed a gradual and significant (p < 0.05) release as a result of lipolysis. At the end of ripening, the addition of GRA1000 protected chorizos from oxidative degradation. PMID:26785337

Effect of linseed supplementation and slaughter age on meat quality of grazing cross-bred Galician x Burguete foals.

PubMed

Domínguez, Rubén; Pateiro, Mirian; Crecente, Santiago; Ruiz, Marta; Sarriés, María V; Lorenzo, José M

2018-01-01

The aim of this study was to assess the effect of finishing diet (control concentrate vs. linseed concentrate) and slaughter age (13 vs. 26 months) on meat and nutritional quality of foal meat. For this study, 46 foals from crossing Galicia Mountain x Burguete breeds were used. The obtained results showed that slaughter age had an influence on chemical composition and colour parameters. Foals slaughtered at the age of 13 months had lower content of intramuscular fat and higher cholesterol contents than those slaughtered at 26 months of age. Regarding colour parameters, older foals showed the highest values of redness and lowest myoglobin contents. Finishing diet had a low effect on the majority of parameters evaluated. Foals fed with linseed presented lower shear force values than those fed with control concentrate. Fatty acid and amino acid contents were hardly influenced by finishing diet, whereas slaughter age effect had a high impact on fatty acid profile. Older animals showed lowest SFA values and n-6/n-3 ratio. Older animals presented the best meat quality. Diet had low effect in meat quality and could be related to the short time during finishing diet was administered and the low amount of linseed in the experimental diet. © 2017 Society of Chemical Industry. © 2017 Society of Chemical Industry.

Effect of Pleurotus eryngii Mushroom β-Glucan on Quality Characteristics of Common Wheat Pasta.

PubMed

Kim, SunHee; Lee, Jo-Won; Heo, Yena; Moon, BoKyung

2016-04-01

The objective of this study was to evaluate the effect of β-glucan-rich fractions (BGRFs) from Pleurotus eryngii mushroom powder on the quality, textural properties, and sensory evaluation of common wheat pasta. Pasta was prepared from semolina flour and common wheat flour by replacing common wheat flour at 2%, 4%, and 6% with BGRFs. Semolina flour showed significantly higher viscosities than common wheat flour samples. However, all viscosities, except the breakdown viscosity, were reduced with increasing percentages of BGRFs. Replacement of the common wheat flour with BGRFs resulted in a reddish brown colored pasta with a lower L* value and a higher a* value. The common wheat pastas containing up to 4% BGRFs were not significantly different from semolina pasta with regard to cooking loss. Addition of up to 2% BGRFs had no significant impact on swelling index and water absorption. The addition of BGRFs in common wheat flour had a positive effect on the quality of common wheat pasta and resulted in hardness values similar to those of semolina pasta. In a sensory evaluation, cooked pasta with 2% BGRFs had the highest overall acceptability score. In summary, the results showed that common wheat flour containing 4% BGRFs could be used to produce pasta with an improved quality and texture properties similar to semolina pasta. © 2016 Institute of Food Technologists®

Microstructure and hardness of bovine enamel in roselle extract solution

NASA Astrophysics Data System (ADS)

Dame, M. T.; Noerdin, A.; Indrani, D. J.

2017-08-01

The aim of this study was to analyze the effect of roselle extract solution on the microstructure and hardness of bovine enamel. Ten bovine teeth and a 5% concentration of roselle extract solution were prepared. Immersions of each bovine tooth in roselle extract solution were conducted up to 60 minutes. The bovine enamel surface was characterized in hardness and microscopy. It was apparent that the initial hardness was 328 KHN, and after immersion in 15 and 60 min, the values decrease to 57.4 KHN and 11 KHN, respectively. Scanning electron microscopy (SEM) revealed changes in enamel rods after immersion in the roselle extract solution.

Radial distribution function for hard spheres in fractal dimensions: A heuristic approximation.

PubMed

Santos, Andrés; de Haro, Mariano López

2016-06-01

Analytic approximations for the radial distribution function, the structure factor, and the equation of state of hard-core fluids in fractal dimension d (1≤d≤3) are developed as heuristic interpolations from the knowledge of the exact and Percus-Yevick results for the hard-rod and hard-sphere fluids, respectively. In order to assess their value, such approximate results are compared with those of recent Monte Carlo simulations and numerical solutions of the Percus-Yevick equation for a fractal dimension [M. Heinen et al., Phys. Rev. Lett. 115, 097801 (2015)PRLTAO0031-900710.1103/PhysRevLett.115.097801], a good agreement being observed.

Application of Rapid Visco Analyser (RVA) viscograms and chemometrics for maize hardness characterisation.

PubMed

Guelpa, Anina; Bevilacqua, Marta; Marini, Federico; O'Kennedy, Kim; Geladi, Paul; Manley, Marena

2015-04-15

It has been established in this study that the Rapid Visco Analyser (RVA) can describe maize hardness, irrespective of the RVA profile, when used in association with appropriate multivariate data analysis techniques. Therefore, the RVA can complement or replace current and/or conventional methods as a hardness descriptor. Hardness modelling based on RVA viscograms was carried out using seven conventional hardness methods (hectoliter mass (HLM), hundred kernel mass (HKM), particle size index (PSI), percentage vitreous endosperm (%VE), protein content, percentage chop (%chop) and near infrared (NIR) spectroscopy) as references and three different RVA profiles (hard, soft and standard) as predictors. An approach using locally weighted partial least squares (LW-PLS) was followed to build the regression models. The resulted prediction errors (root mean square error of cross-validation (RMSECV) and root mean square error of prediction (RMSEP)) for the quantification of hardness values were always lower or in the same order of the laboratory error of the reference method. Copyright © 2014 Elsevier Ltd. All rights reserved.

A Nation at War. Annual Strategy Conference (17th) Held at Carlisle Barracks, PA on 11-13 April 2006

DTIC Science & Technology

2007-01-01

have the opportunity to come here learn for themselves that Americans are generous, hard -working people who value faith and family.” That is...particularly hard on the military and ought to be avoided. As learned the hard way, deploying to a crisis or conflict zone where the situational...phenomena—more women in the workplace, telecommuting , changing careers, 64 people working longer—will need to be reflected in the military structure

Experimental study on joining of AA6063 and AISI 1040 steel

NASA Astrophysics Data System (ADS)

Hynes, N. Rajesh Jesudoss; Raja, S.

2018-05-01

Feasibility of joining of dissimilar metals with different physical, chemical and thermal properties such as AA6063 alloy and AISI 1040 steel is worthwhile study, since it has tremendous applications in all most of all engineering domains. The mechanism of bonding is studied using scanning electron microscopy. Impact strength of AA2024/AISI joints, axial shortening distance, micro hardness distribution and joint strength are determined. Micro hardness profile shows increased hardness value at the joint interface, due to grain refinement.

The impact of standard and hard-coded parameters on the hydrologic fluxes in the Noah-MP land surface model

NASA Astrophysics Data System (ADS)

Thober, S.; Cuntz, M.; Mai, J.; Samaniego, L. E.; Clark, M. P.; Branch, O.; Wulfmeyer, V.; Attinger, S.

2016-12-01

Land surface models incorporate a large number of processes, described by physical, chemical and empirical equations. The agility of the models to react to different meteorological conditions is artificially constrained by having hard-coded parameters in their equations. Here we searched for hard-coded parameters in the computer code of the land surface model Noah with multiple process options (Noah-MP) to assess the model's agility during parameter estimation. We found 139 hard-coded values in all Noah-MP process options in addition to the 71 standard parameters. We performed a Sobol' global sensitivity analysis to variations of the standard and hard-coded parameters. The sensitivities of the hydrologic output fluxes latent heat and total runoff, their component fluxes, as well as photosynthesis and sensible heat were evaluated at twelve catchments of the Eastern United States with very different hydro-meteorological regimes. Noah-MP's output fluxes are sensitive to two thirds of its standard parameters. The most sensitive parameter is, however, a hard-coded value in the formulation of soil surface resistance for evaporation, which proved to be oversensitive in other land surface models as well. Latent heat and total runoff show very similar sensitivities towards standard and hard-coded parameters. They are sensitive to both soil and plant parameters, which means that model calibrations of hydrologic or land surface models should take both soil and plant parameters into account. Sensible and latent heat exhibit almost the same sensitivities so that calibration or sensitivity analysis can be performed with either of the two. Photosynthesis has almost the same sensitivities as transpiration, which are different from the sensitivities of latent heat. Including photosynthesis and latent heat in model calibration might therefore be beneficial. Surface runoff is sensitive to almost all hard-coded snow parameters. These sensitivities get, however, diminished in total runoff. It is thus recommended to include the most sensitive hard-coded model parameters that were exposed in this study when calibrating Noah-MP.

Modeling of the flow stress for AISI H13 Tool Steel during Hard Machining Processes

NASA Astrophysics Data System (ADS)

Umbrello, Domenico; Rizzuti, Stefania; Outeiro, José C.; Shivpuri, Rajiv

2007-04-01

In general, the flow stress models used in computer simulation of machining processes are a function of effective strain, effective strain rate and temperature developed during the cutting process. However, these models do not adequately describe the material behavior in hard machining, where a range of material hardness between 45 and 60 HRC are used. Thus, depending on the specific material hardness different material models must be used in modeling the cutting process. This paper describes the development of a hardness-based flow stress and fracture models for the AISI H13 tool steel, which can be applied for range of material hardness mentioned above. These models were implemented in a non-isothermal viscoplastic numerical model to simulate the machining process for AISI H13 with various hardness values and applying different cutting regime parameters. Predicted results are validated by comparing them with experimental results found in the literature. They are found to predict reasonably well the cutting forces as well as the change in chip morphology from continuous to segmented chip as the material hardness change.

Graphene oxide and hydroxyapatite as fillers of polylactic acid nanocomposites: preparation and characterization.

PubMed

Marques, Paula A A P; Gonçalves, Gil; Singh, Manoj K; Grácio, José

2012-08-01

Graphene and its derivatives have attracted great research interest for their potential applications in electronics, energy, materials and biomedical areas. When incorporated appropriately, these atomically thin carbon sheets are expected to improve physical properties of host polymers at extremely small loading. Herein, we report a novel two-step method for the preparation of PLLA/Hap/graphene oxide nanocomposites with augmented mechanical properties when compared to PLLA/Hap and neat PLLA. The presence of graphene oxide (GO) had a positive effect on the dispersion of hydroxyapatite particles on the polymeric matrix contributing for a good homogeneity of the final nanocomposite. PLLA nanocomposites prepared with 30% (w/w) of Hap and 1% (w/w) of GO showed the highest hardness and storage modulus values indicating an efficient load transfer between the fillers and the PLLA matrix. These materials may find interesting biomedical applications as for example bone screws. The following step on the study of these materials will be in vitro tests to access the biocompatibility of these new nanocomposites.

Biscuits fortified with micro-encapsulated shrimp oil: characteristics and storage stability.

PubMed

Takeungwongtrakul, Sirima; Benjakul, Soottawat

2017-04-01

Characteristics and storage stability of biscuits fortified with micro-encapsulated shrimp oil (MSO) were determined. The addition of MSO increased spread ratio, whilst decreased the thickness of biscuit. The highest hardness of biscuit was obtained with addition of 9 or 12% MSO. Biscuit surface showed higher redness and yellowness when MSO was incorporated ( p  < 0.05). The addition of MSO up to 6% had no adverse effect on biscuit quality and acceptability. When biscuits added with 6% MSO were stored under different illumination conditions (light and dark), lipid oxidation in all samples increased throughout the storage of 12 days. Light accelerated lipid oxidation of biscuits as evidenced by the increases in both peroxide values and abundance of volatile compounds. No marked change in EPA, DHA and astaxanthin contents were noticeable in biscuit fortified with MSO after 12 days of storage. Therefore, the biscuit could be fortified with MSO up to 6% and must be stored in dark to assure its oxidative stability.

Effects of cooking methods and temperatures on nutritional and quality characteristics of anchovy (Engraulis encrasicholus).

PubMed

Uran, Harun; Gokoglu, Nalan

2014-04-01

The aim of this study was to determine the nutritional and quality characteristics of anchovy after cooking. The fish were cooked by different methods (frying, baking and grilling) at two different temperatures (160 °C, 180 °C). Crude ash, crude protein and crude fat contents of cooked fish increased due to rise in dry matter contents. While cooking methods affected mineral content of anchovy, cooking temperature did not affect. The highest values of monounsaturated fatty acids were found in baked samples. Polyunsaturated fatty acids in baked samples were also high and similar in fried samples. Fried samples, which were the most preferred, lost its nutritional characteristics more than baked and grilled samples. Grilled and baked fish samples can be recommended for healthy consumption. However, grilled fish samples had hard texture due to more moisture loss than other methods. Therefore, it is concluded that baking is the best cooking method for anchovy.

Investigation of mechanical properties for open cellular structure CoCrMo alloy fabricated by selective laser melting process

NASA Astrophysics Data System (ADS)

Azidin, A.; Taib, Z. A. M.; Harun, W. S. W.; Che Ghani, S. A.; Faisae, M. F.; Omar, M. A.; Ramli, H.

2015-12-01

Orthodontic implants have been a major focus through mechanical and biological performance in advance to fabricate shape of complex anatomical. Designing the part with a complex mechanism is one of the challenging process and addition to achieve the balance and desired mechanical performance brought to the right manufacture technique to fabricate. Metal additive manufacturing (MAM) is brought forward to the newest fabrication technology in this field. In this study, selective laser melting (SLM) process was utilized on a medical grade cobalt-chrome molybdenum (CoCrMo) alloy. The work has focused on mechanical properties of the CoCrMo open cellular structures samples with 60%, 70%, and 80% designed volume porosity that could potentially emulate the properties of human bone. It was observed that hardness values decreased as the soaking time increases except for bottom face. For compression test, 60% designed volume porosity demonstrated highest ultimate compressive strength compared to 70% and 80%.

Effect of different flours on quality of legume cakes to be baked in microwave-infrared combination oven and conventional oven.

PubMed

Ozkahraman, Betul Canan; Sumnu, Gulum; Sahin, Serpil

2016-03-01

The objective of this study was to compare the quality of legume cakes baked in microwave-infrared combination (MW-IR) oven with conventional oven. Legume cake formulations were developed by replacing 10 % wheat flour by lentil, chickpea and pea flour. As a control, wheat flour containing cakes were used. Weight loss, specific volume, texture, color, gelatinization degree, macro and micro-structure of cakes were investigated. MW-IR baked cakes had higher specific volume, weight loss and crust color change and lower hardness values than conventionally baked cakes. Larger pores were observed in MW-IR baked cakes according to scanning electron microscope (SEM) images. Pea flour giving the hardest structure, lowest specific volume and gelatinization degree was determined to be the least acceptable legume flour. On the other hand, lentil and chickpea flour containing cakes had the softest structure and highest specific volume showing that lentil and chickpea flour can be used to produce functional cakes.

Human population growth and temperature increase along with the increase in urbanisation, motor vehicle numbers and green area amount in the sample of Erzurum city, Turkey.

PubMed

Yilmaz, Sevgi; Toy, Süleyman; Demircioglu Yildiz, Nalan; Yilmaz, Hasan

2009-01-01

In the study, main purpose was to determine the effect of population growth along with the increase in urbanisation, motor vehicle use and green area amount on the temperature values using a 55-year data set in Erzurum, which is hardly industrialised, and one of the coldest cities with highest elevation in Turkey. Although the semi-decadal increases, means of which are 0.1 degrees C for mean, minimum and maximum temperatures, are not clear enough to make a strong comment even in the lights of figures or tables, it was found as the result of the statistical analysis that population growth and increases in the number of vehicles, the number of buildings and the green area amount in the city have no significant effect on mean temperatures. However, the relationships between population growth and maximum temperature; and the number of vehicles and minimum temperature were found to be statistically significant.

Evolution of residual stress, free volume, and hardness in the laser shock peened Ti-based metallic glass

DOE Office of Scientific and Technical Information (OSTI.GOV)

Wang, Liang; Wang, Lu; Nie, Zhihua

Laser shock peening (LSP) with different cycles was performed on the Ti-based bulk metallic glasses (BMGs). The sub-surface residual stress of the LSPed specimens was measured by high-energy X-ray diffraction (HEXRD) and the near-surface residual stress was measured by scanning electron microscope/focused ion beam (SEM/FIB) instrument. The sub-surface residual stress in the LSP impact direction (about-170MPa) is much lower than that perpendicular to the impact direction (about -350 MPa), exhibiting anisotropy. The depth of the compressive stress zone increases from 400 mu m to 500 mu m with increasing LSP cycles. The highest near-surface residual stress is about -750 MPa.more » LSP caused the free volume to increase and the maximum increase appeared after the first LSP process. Compared with the hardness (567 +/- 7 HV) of the as-cast BMG, the hardness (590 +/- 9 HV) on the shocked surface shows a hardening effect due to the hardening mechanism of compressive residual stress; and the hardness (420 +/- 9 HV) on the longitudinal section shows a softening effect due to the softening mechanism of free volume.« less

Thermal Conductivity and Elastic Modulus Evolution of Thermal Barrier Coatings under High Heat Flux Conditions

NASA Technical Reports Server (NTRS)

Zhu, Dongming; Miller, Robert A.

1999-01-01

Laser high heat flux test approaches have been established to obtain critical properties of ceramic thermal barrier coatings (TBCs) under near-realistic temperature and thermal gradients that may he encountered in advanced engine systems. Thermal conductivity change kinetics of a thin ceramic coating were continuously monitored in real time at various test temperatures. A significant thermal conductivity increase was observed during the laser simulated engine heat flux tests. For a 0.25 mm thick ZrO2-8%Y2O3 coating system, the overall thermal conductivity increased from the initial value of 1.0 W/m-K to 1. 15 W/m-K, 1. 19 W/m-K and 1.5 W/m-K after 30 hour testing at surface temperatures of 990C, 1100C, and 1320C. respectively. Hardness and modulus gradients across a 1.5 mm thick TBC system were also determined as a function of laser testing time using the laser sintering/creep and micro-indentation techniques. The coating Knoop hardness values increased from the initial hardness value of 4 GPa to 5 GPa near the ceramic/bond coat interface, and to 7.5 GPa at the ceramic coating surface after 120 hour testing. The ceramic surface modulus increased from an initial value of about 70 GPa to a final value of 125 GPa. The increase in thermal conductivity and the evolution of significant hardness and modulus gradients in the TBC systems are attributed to sintering-induced micro-porosity gradients under the laser-imposed high thermal gradient conditions. The test techniques provide a viable means for obtaining coating data for use in design, development, stress modeling, and life prediction for various thermal barrier coating applications.

Outdoor ground impedance models.

PubMed

Attenborough, Keith; Bashir, Imran; Taherzadeh, Shahram

2011-05-01

Many models for the acoustical properties of rigid-porous media require knowledge of parameter values that are not available for outdoor ground surfaces. The relationship used between tortuosity and porosity for stacked spheres results in five characteristic impedance models that require not more than two adjustable parameters. These models and hard-backed-layer versions are considered further through numerical fitting of 42 short range level difference spectra measured over various ground surfaces. For all but eight sites, slit-pore, phenomenological and variable porosity models yield lower fitting errors than those given by the widely used one-parameter semi-empirical model. Data for 12 of 26 grassland sites and for three beech wood sites are fitted better by hard-backed-layer models. Parameter values obtained by fitting slit-pore and phenomenological models to data for relatively low flow resistivity grounds, such as forest floors, porous asphalt, and gravel, are consistent with values that have been obtained non-acoustically. Three impedance models yield reasonable fits to a narrow band excess attenuation spectrum measured at short range over railway ballast but, if extended reaction is taken into account, the hard-backed-layer version of the slit-pore model gives the most reasonable parameter values.

Maintenance of raw and cooked ready-to-eat product quality of infused poultry meats with selected plant extracts during electron beam irradiation and after storage

NASA Astrophysics Data System (ADS)

Rababah, Taha

The purpose of this study included: preparing plant extracts and evaluating these extracts for total phenolics and antioxidant activities (AA); infusing extract/combination that demonstrates superior AA into chicken breast and irradiating at 3.0 kGy; evaluating the physicochemical properties of irradiated and non-irradiated raw and cooked chicken breast at 5°C for 12 days and -20°C for 9 months; and selecting the extracts that demonstrated desirable AA, infusing these extracts into chicken breast and evaluating head-space volatiles, and conducting sensory evaluation. The total phenolic content and AA of the plant extracts ranged from 24.8 to 92.5 mg/g dry material (conjugated diene of methyl linoleate) and 3.4 to 86.3%, respectively. The AA of plant extracts using oxidative stability instrument were 4.6 to 10.2 h (Induction time). Green tea and grape seed extracts had the highest AA within several plant extracts, and were selected to retard lipid oxidation in further studies. Fresh boneless and skinless chicken breast meats were vacuum infused with varying concentrations of antioxidants: Green tea and grape seed extracts alone/in combination and tert-butylhydroquinone. The results showed that irradiation had no significant effect on pH, water holding capacity, but increased the redness and carbonyls in raw meats (p < 0.05). Irradiation increased shear force, hardness, and chewiness of cooked meats. Infusion of plant extracts into meats increased lightness and decreased redness as well as hardness and shear force. Irradiation increased TBARS, hexanal, and pentanal values in raw and cooked meats. Addition of plant extracts decreased the amount of TBARS, hexanal, pentanal, and carbonyl values. Similar results were observed when the samples were stored at -20°C for 9 months. Descriptive sensory flavor results showed that irradiation did not affect the flavor attributes. Consumer, descriptive, and instrumental results showed that irradiation increased toughness, green tea improved the meat color, and the panel indicated that irradiation decreased the tenderness of the samples. Infusion of extracts/combinations into chicken meats increased lightness and decreased redness as well as the hardness of products. Infusion of chicken meat with plant extracts is an effective method to minimize physicochemical properties, volatile developments, and sensory quality caused by irradiation.

Usefulness of the Left Ventricular Myocardial Contraction Fraction in Healthy Men and Women to Predict Cardiovascular Morbidity and Mortality

PubMed Central

Chuang, Michael L.; Gona, Philimon; Salton, Carol J.; Yeon, Susan B.; Kissinger, Kraig V.; Blease, Susan J.; Levy, Daniel; O'Donnell, Christopher J.; Manning, Warren J.

2013-01-01

We sought to determine whether depressed myocardial contraction fraction (MCF, the ratio of left ventricular (LV) stroke volume to myocardial volume) predicts cardiovascular disease (CVD) events in initially healthy adults. A subset (N=318, 60±9 yrs, 158 men) of the Framingham Heart Study Offspring cohort free of clinical CVD underwent volumetric cardiovascular magnetic resonance (CMR) imaging in 1998–1999. LV ejection fraction (EF), mass and MCF were determined. “Hard” CVD events comprised cardiovascular death, myocardial infarction, stroke or new heart failure. A Cox proportional hazards model adjusting for Framingham Coronary Risk Score (FCRS) was used to estimate hazard ratios for incident hard CVD events for sex-specific quartiles of MCF, LV mass and LVEF. The lowest quartile of LV mass and highest quartiles of MCF and EF served as referent. Kaplan-Meier survival plots and the log rank test were used to compare event-free survival. MCF was greater in women (0.58±0.13) than men (0.52±0.11), p<0.01. Nearly all (99%) participants had EF ≥ 0.55. Over up to 9-year (median 5.2) follow-up, 31 participants (10%) experienced an incident hard CVD event. Lowest-quartile MCF was 7 times more likely to develop hard CVD (hazard ratio 7.11, p=0.010) compared to the lowest quartile, and the elevated hazards persisted even after adjustment for LV mass (hazard ratio=6.09, p=0.020). The highest-quartile LV mass/height2.7 had nearly five-fold risk (hazard ratio 4.68, p=0.016). Event-free survival was shorter in lowest-quartile MCF, p = 0.0006, but not in lowest-quartile LVEF. Conclusion: In a cohort of adults initially without clinical CVD, lowest-quartile MCF conferred an increased hazard for hard CVD events after adjustment for traditional CVD risk factors and LV mass. PMID:22381161

Signatures of Synchrotron: Low-cutoff X-ray emission and the hard X-ray spectrum of Cas A

NASA Astrophysics Data System (ADS)

Stage, Michael D.; Fedor, Emily Elizabeth; Martina-Hood, Hyourin

2018-06-01

In soft X-rays, bright, young Galactic remnants (Cas A, Kepler, Tycho, etc.) present thermal line emission and bremsstrahlung from ejecta, and synchrotron radiation from the shocks. Their hard X-ray spectra tend to be dominated by power-law sources. However, it can be non-trivial to discriminate between contributions from processes such as synchrotron and bremsstrahlung from nonthermally accelerated electrons, even though the energies of the electrons producing this radiation may be very different. Spatially-resolved spectroscopic analysis of 0.5-10 keV observations with, e.g., Chandracan provide leverage in identifying the processes and their locations. Previously, Stage & Allen (2006), Allen & Stage (2007) and Stage & Allen (2011) identified regions characterized by high-cutoff synchrotron radiation. Extrapolating synchrotron model fits to the emission in the Chandra band, they estimated the synchrotron contribution to the hard X-ray spectrum at about one-third the observed flux, fitting the balance with nonthermal bremsstrahlung emission produced by nonthermal electrons in the ejecta. Although it is unlikely this analysis missed regions of the highest-cutoff synchrotron emission, which supplies the bulk of the synchrotron above 15 keV, it may have missed regions of lower-cutoff emission, especially if they are near bright ejecta and the reverse shock. These regions cannot explain the emission at the highest energies (~50 keV), but may make significant contributions to the hard spectrum at lower energies (~10 keV). Using the technique described in Fedor, Martina-Hood & Stage (this meeting), we revisit the analysis to include regions that may be dominated by low-cutoff synchrotron, located in the interior of the remnant, and/or correlated with the reverse shock. Identifying X-ray emission from accelerated electrons associated with the reverse-shock would have important implications for synchrotron and non-thermal bremsstrahlung radiation above the 10 keV.

Fermi Observations of GRB 090510: A Short Hard Gamma-Ray Burst with an Additional, Hard Power-Law Component from 10 keV to GeV Energies

DOE PAGES

Ackermann, M.; Asano, K.; Atwood, W. B.; ...

2010-05-27

We present detailed observations of the bright short-hard gamma-ray burst GRB 090510 made with the Gamma-ray Burst Monitor (GBM) and Large Area Telescope (LAT) on board the Fermi observatory. GRB 090510 is the first burst detected by the LAT that shows strong evidence for a deviation from a Band spectral fitting function during the prompt emission phase. The time-integrated spectrum is fit by the sum of a Band function with E peak = 3.9 ± 0.3 MeV, which is the highest yet measured, and a hard power-law component with photon index –1.62 ± 0.03 that dominates the emission below ≈20more » keV and above ≈100 MeV. The onset of the high-energy spectral component appears to be delayed by ~0.1 s with respect to the onset of a component well fit with a single Band function. A faint GBM pulse and a LAT photon are detected 0.5 s before the main pulse. During the prompt phase, the LAT detected a photon with energy 30.5 +5.8 –2.6 GeV, the highest ever measured from a short GRB. Observation of this photon sets a minimum bulk outflow Lorentz factor, Γ≳ 1200, using simple γγ opacity arguments for this GRB at redshift z = 0.903 and a variability timescale on the order of tens of ms for the ≈100 keV-few MeV flux. Stricter high confidence estimates imply Γ ≳ 1000 and still require that the outflows powering short GRBs are at least as highly relativistic as those of long-duration GRBs. Finally, implications of the temporal behavior and power-law shape of the additional component on synchrotron/synchrotron self-Compton, external-shock synchrotron, and hadronic models are considered.« less

On the trends of Fukui potential and hardness potential derivatives in isolated atoms vs. atoms in molecules.

PubMed

Bhattacharjee, Rituparna; Roy, Ram Kinkar

2014-10-28

In the present study, trends of electronic contribution to molecular electrostatic potential [Vel(r¯)(r=0)], Fukui potential [v(+)f|(r=0) and v(-)f|(r=0)] and hardness potential derivatives [Δ(+)h(k) and Δ(-)h(k)] for isolated atoms as well as atoms in molecules are investigated. The generated numerical values of these three reactivity descriptors in these two electronically different situations are critically analyzed through the relevant formalism. Values of Vel(r¯) (when r → 0, i.e., on the nucleus) are higher for atoms in molecules than that of isolated atoms. In contrast, higher values of v(+)|(r=0) and v(-)|(r=0) are observed for isolated atoms compared to the values for atoms in a molecule. However, no such regular trend is observed for the Δ(+)h(k) and Δ(-)h(k) values, which is attributed to the uncertainty in the Fukui function values of atoms in molecules. The sum of Fukui potential and the sum of hardness potential derivatives in molecules are also critically analyzed, which shows the efficacy of orbital relaxation effects in quantifying the values of these parameters. The chemical consequence of the observed trends of these descriptors in interpreting electron delocalization, electronic relaxation and non-negativity of atomic Fukui function indices is also touched upon. Several commonly used molecules containing carbon as well as heteroatoms are chosen to make the investigation more insightful.

In vitro starch digestibility, pasting and textural properties of mung bean: effect of different processing methods.

PubMed

Kaur, Maninder; Sandhu, Kawaljit Singh; Ahlawat, RavinderPal; Sharma, Somesh

2015-03-01

Mung bean was subjected to different processing conditions (soaking, germination, cooking and autoclaving) and their textural, pasting and in vitro starch digestibility characteristics were studied. A significant reduction in textural properties (hardness, cohesiveness, gumminess and chewiness) after cooking and autoclaving treatment of mung bean was observed. Flours made from differently processed mung bean showed significant differences (P < 0.05) in their pastin g characteristics. Peak and final viscosity were the highest for flour from germinated mung bean whereas those made from autoclaved mung bean showed the lowest value. in vitro starch digestibility of mung bean flours was assessed enzymatically using modified Englyst method and the parameters studied were readily digestible starch (RDS), slowly digestible starch (SDS), resistant starch (RS) and total starch (TS) content. Various processing treatments increased the RDS contents of mung bean, while the SDS content was found to be the highest for soaked and the lowest for the autoclaved sample. Germinated sample showed higher amount of digestible starch (RDS + SDS) as compared to raw and soaked samples. Flours from raw and soaked samples showed significantly low starch hydrolysis rate at all the temperatures with total hydrolysis of 29.9 and 31.2 %, respectively at 180 min whereas cooked and autoclaved samples showed high hydrolysis rates with 50.2 and 53.8 % of these hydrolyzing within 30 min of hydrolysis.

Physicochemical and Rheological Properties of a Dairy Dessert, Enriched with Chickpea Flour

PubMed Central

Aguilar-Raymundo, Victoria Guadalupe; Vélez-Ruiz, Jorge Fernando

2018-01-01

Dairy desserts are complex mixtures and matrices including main components such as milk, sugar, starch, hydrocolloids, colorants and flavors, with a proteinaceous structure; they are widely consumed and present a semisolid consistency. In this work, the physicochemical and rheological properties of a dairy dessert with the addition of chickpea flour (raw and cooked, at four concentrations) were studied to determine the effect of the flour. The results indicated that luminosity (L*: 62.75–83.29), pH (6.35–7.11) and acidity (1.56–3.56) changed with the type of flour. The flow properties of the custards exhibited a non-Newtonian behavior that was well fitted by three flow models. The studied custard systems were stored for twelve days at 4 °C. The physicochemical and flow properties of the custards changed notably as a function of flour addition and storage time. From all samples, only four were analyzed with oscillatory tests, showing their mechanical spectra with elastic behavior. The dessert texture was also measured, founding that those formulated with Blanco Noroeste chickpea flour exhibited the highest values of hardness (0.356–0.391 N) through the twelve days. It can be concluded that those custard systems with the highest content of flour presented a very good response as a potential new dairy product. PMID:29463036

Investigation of microstructural alterations in M50 and 52100 steel using nanoindentation

NASA Astrophysics Data System (ADS)

Paulson, Kristin R.

Bearing steels are used in rolling elements and are designed to withstand heavy loads for an extended period of time. At the end of life, microstructural alterations within the material have been observed and are linked to failure. In this study, a three ball-on-rod fatigue tester was used to test M50 and 52100 steel cylindrical rods at differing loads of 4.0 GPa, 4.5 GPa, and 5.0 GPa and in lubricated and unlubricated conditions to 108 cycles in an attempt to produce microstructural alterations. Microstructural alterations characterized as butterflies were observed and investigated further in two M50 samples that were tested at 4.5 GPa to 10 8 cycles in the lubricated and unlubricated condition. Microstructural alterations characterized as dark etching regions (DER), and white etching bands (WEBs) were not observed. Additionally, hardness was investigated cross sectionally as a function of depth and location within the wear track produced by the fatigue test. No conclusive evidence was derived from the hardness measurements as a function of depth in relation to the formation of microstructural alterations or the stress experienced subsurface within the material. Hardness measurements performed specifically within a butterfly wing, however, returned hardness values significantly higher than the matrix hardness values.

Fate of Mycobacterium avium subsp. paratuberculosis in Swiss hard and semihard cheese manufactured from raw milk.

PubMed

Spahr, U; Schafroth, K

2001-09-01

Raw milk was artificially contaminated with declumped cells of Mycobacterium avium subsp. paratuberculosis at a concentration of 10(4) to 10(5) CFU/ml and was used to manufacture model hard (Swiss Emmentaler) and semihard (Swiss Tisliter) cheese. Two different strains of M. avium subsp. paratuberculosis were tested, and for each strain, two model hard and semihard cheeses were produced. The survival of M. avium subsp. paratuberculosis cells was monitored over a ripening period of 120 days by plating out homogenized cheese samples onto 7H10-PANTA agar. In both the hard and the semihard cheeses, counts decreased steadily but slowly during cheese ripening. Nevertheless, viable cells could still be detected in 120-day cheese. D values were calculated at 27.8 days for hard and 45.5 days for semihard cheese. The most important factors responsible for the death of M. avium subsp. paratuberculosis in cheese were the temperatures applied during cheese manufacture and the low pH at the early stages of cheese ripening. Since the ripening period for these raw milk cheeses lasts at least 90 to 120 days, the D values found indicate that 10(3) to 10(4) cells of M. avium subsp. paratuberculosis per g will be inactivated.

Fate of Mycobacterium avium subsp. paratuberculosis in Swiss Hard and Semihard Cheese Manufactured from Raw Milk

PubMed Central

Spahr, U.; Schafroth, K.

2001-01-01

Raw milk was artificially contaminated with declumped cells of Mycobacterium avium subsp. paratuberculosis at a concentration of 104 to 105 CFU/ml and was used to manufacture model hard (Swiss Emmentaler) and semihard (Swiss Tisliter) cheese. Two different strains of M. avium subsp. paratuberculosis were tested, and for each strain, two model hard and semihard cheeses were produced. The survival of M. avium subsp. paratuberculosis cells was monitored over a ripening period of 120 days by plating out homogenized cheese samples onto 7H10-PANTA agar. In both the hard and the semihard cheeses, counts decreased steadily but slowly during cheese ripening. Nevertheless, viable cells could still be detected in 120-day cheese. D values were calculated at 27.8 days for hard and 45.5 days for semihard cheese. The most important factors responsible for the death of M. avium subsp. paratuberculosis in cheese were the temperatures applied during cheese manufacture and the low pH at the early stages of cheese ripening. Since the ripening period for these raw milk cheeses lasts at least 90 to 120 days, the D values found indicate that 103 to 104 cells of M. avium subsp. paratuberculosis per g will be inactivated. PMID:11526024

An in vitro investigation of wear resistance and hardness of composite resins.

PubMed

Cao, Liqun; Zhao, Xinyi; Gong, Xu; Zhao, Shouliang

2013-01-01

The aim of the present study was to investigate the wear resistance and hardness of five kinds of composite resins. Sixty-five specimens were fabricated with one nano-hybrid (Charisma Diamond), two micro-hybrid (3MZ250, Clearfil AP-X) and two packable (3MP60, Surefil) composite resins, according to a randomized complete block design (n=13, 8 for wear test; 5 for hardness test). The composites were filled in a rectangular mold, and light polymerization. After storage in 37°C deionized water for 24h, all specimens were tested with a custom-made toothbrush machine with a stainless-steel ball as antagonist (3N loads, 1Hz, 6×10(5) cycles) immersed in calcium fluoride slurry. Wear volume, hardness and surface structure of each tested material was examined by a three-dimensional non-contact optical profilometer, Vickers indentation technique and scanning electron microscope. The volume loss ranked from least to most as follows: Charisma Diamond, P60, Z250, Clearfil AP-X and Surefil. Regarding hardness, the rank from highest to lowest as follows: Clearfil AP-X, P60, Surefil, Z250, Charisma Diamond. The interactions between wear resistance and microhardness were not significant. The custom-made machine is considered suitable to simulate sliding of an antagonist cusp on an opposing occlusal composite restoration. Nanofilled composite may have superior wear compared to other composite resins.

[Investigation on noncarious hard tissue lesions of teeth in teachers of one university in Shanghai municipality].

PubMed

Chen, Yi-li; Zhang, Zhe-dan; Guo, Jian-qing; Zhu, Ya-ping; Wang, Qun; Gao, Ling-yu

2011-06-01

To investigate the condition of four kinds of noncarious hard tissue lesions of the teeth in teachers of one university in Shanghai municipality and provide guidance about oral health care. The table and the standard on oral health survey authorized by WHO were adopted, condition of four kinds of noncarious hard tissue lesions of teeth in 776 teachers of East China University of Science was investigated and analyzed using SPSS16.0 software package. The average wedge-shaped defect teeth was 5.54±3.87, the incidence was 30.41%, caries incidence of the first bicuspid was the highest(29.52%). The incidence of tetracycline pigmentation teeth was 3.09%, the incidence of enamel hypoplasia was 2.06%, and the incidence of dental fluorosis was 1.55%. The average wedge-shaped defect teeth is higher than the data over the country, the incidence of dental textural anomaly is lower. The behaviors of oral health care of university teachers in Shanghai municipality remains to be further strengthened.

Investigating the technical adequacy of curriculum-based measurement in written expression for students who are deaf or hard of hearing.

PubMed

Cheng, Shu-Fen; Rose, Susan

2009-01-01

This study investigated the technical adequacy of curriculum-based measures of written expression (CBM-W) in terms of writing prompts and scoring methods for deaf and hard-of-hearing students. Twenty-two students at the secondary school-level completed 3-min essays within two weeks, which were scored for nine existing and alternative curriculum-based measurement (CBM) scoring methods. The technical features of the nine scoring methods were examined for interrater reliability, alternate-form reliability, and criterion-related validity. The existing CBM scoring method--number of correct minus incorrect word sequences--yielded the highest reliability and validity coefficients. The findings from this study support the use of the CBM-W as a reliable and valid tool for assessing general writing proficiency with secondary students who are deaf or hard of hearing. The CBM alternative scoring methods that may serve as additional indicators of written expression include correct subject-verb agreements, correct clauses, and correct morphemes.

Surface enhancement of cold work tool steels by friction stir processing with a pinless tool

NASA Astrophysics Data System (ADS)

Costa, M. I.; Verdera, D.; Vieira, M. T.; Rodrigues, D. M.

2014-03-01

The microstructure and mechanical properties of enhanced tool steel (AISI D2) surfaces produced using a friction stir welding (FSW) related procedure, called friction stir processing (FSP), are analysed in this work. The surface of the tool steel samples was processed using a WC-Co pinless tool and varying processing conditions. Microstructural analysis revealed that meanwhile the original substrate structure consisted of a heterogeneous distribution of coarse carbides in a ferritic matrix, the transformed surfaces consisted of very small carbides, homogenously distributed in a ferrite- bainite- martensite matrix. The morphology of the surfaces, as well as its mechanical properties, evaluated by hardness and tensile testing, were found to vary with increasing tool rotation speed. Surface hardness was drastically increased, relative to the initial hardness of bulk steel. This was attributed to ferrite and carbide refinement, as well as to martensite formation during solid state processing. At the highest rotation rates, tool sliding during processing deeply compromised the characteristics of the processed surfaces.

Impulsive phase transport

NASA Technical Reports Server (NTRS)

Canfield, Richard C.; Bely-Dubau, Francoise; Brown, John C.; Dulk, George A.; Emslie, A. Gordon; Enome, Shinzo; Gabriel, Alan H.; Kundu, Mukul R.; Melrose, Donald; Neidig, Donald F.

1986-01-01

The transport of nonthermal electrons is explored. The thick-target electron beam model, in which electrons are presumed to be accelerated in the corona and typically thermalized primarily in the chromosphere and photosphere, is supported by observations throughout the electromagnetic spectrum. At the highest energies, the anisotropy of gamma-ray emission above 10 MeV clearly indicates that these photons are emitted by anisotropically-directed particles. The timing of this high-energy gamma-radiation with respect to lower-energy hard X-radiation implies that the energetic particles have short life-times. For collisional energy loss, this means that they are stopped in the chromosphere or below. Stereoscopic (two-spacecraft) observations at hard X-ray energies (up to 350 keV) imply that these lower-energy (but certainly nonthermal) electrons are also stopped deep in the chromosphere. Hard X-ray images show that, in spatially resolved flares whose radiation consists of impulsive bursts, the impulsive phase starts with X-radiation that comes mostly from the foot-points of coronal loops whose coronal component is outlined by microwaves.

Note: equation of state and the freezing point in the hard-sphere model.

PubMed

Robles, Miguel; López de Haro, Mariano; Santos, Andrés

2014-04-07

The merits of different analytical equations of state for the hard-sphere system with respect to the recently computed high-accuracy value of the freezing-point packing fraction are assessed. It is found that the Carnahan-Starling-Kolafa and the branch-point approximant equations of state yield the best performance.

Incomparable hardness and modulus of biomimetic porous polyurethane films prepared by directional melt crystallization of a solvent

NASA Astrophysics Data System (ADS)

An, Suyeong; Kim, Byoungsoo; Lee, Jonghwi

2017-07-01

Porous materials with surprisingly diverse structures have been utilized in nature for many functional purposes. However, the structures and applications of porous man-made polymer materials have been limited by the use of processing techniques involving foaming agents. Herein, we demonstrate for the first time the outstanding hardness and modulus properties of an elastomer that originate from the novel processing approach applied. Polyurethane films of 100-μm thickness with biomimetic ordered porous structures were prepared using directional melt crystallization of a solvent and exhibited hardness and modulus values that were 6.8 and 4.3 times higher than those of the random pore structure, respectively. These values surpass the theoretical prediction of the typical model for porous materials, which works reasonably well for random pores but not for directional pores. Both the ordered and random pore structures exhibited similar porosities and pore sizes, which decreased with increasing solution concentration. This unexpectedly significant improvement of the hardness and modulus could open up new application areas for porous polymeric materials using this relatively novel processing technique.

Welding-Induced Microstructure Evolution of a Cu-Bearing High-Strength Blast-Resistant Steel

NASA Astrophysics Data System (ADS)

Caron, Jeremy L.; Babu, Sudarsanam Suresh; Lippold, John C.

2011-12-01

A new high strength, high toughness steel containing Cu for precipitation strengthening was recently developed for naval, blast-resistant structural applications. This steel, known as BlastAlloy160 (BA-160), is of nominal composition Fe-0.05C-3.65Cu-6.5Ni-1.84Cr-0.6Mo-0.1V (wt pct). The evident solidification substructure of an autogenous gas tungsten arc (GTA) weld suggested fcc austenite as the primary solidification phase. The heat-affected zone (HAZ) hardness ranged from a minimum of 353 HV in the coarse-grained HAZ (CGHAZ) to a maximum of 448 HV in the intercritical HAZ (ICHAZ). After postweld heat treatment (PWHT) of the spot weld, hardness increases were observed in the fusion zone (FZ), CGHAZ, and fine-grained HAZ (FGHAZ) regions. Phase transformation and metallographic analyses of simulated single-pass HAZ regions revealed lath martensite to be the only austenitic transformation product in the HAZ. Single-pass HAZ simulations revealed a similar hardness profile for low heat-input (LHI) and high heat-input (HHI) conditions, with higher hardness values being measured for the LHI samples. The measured hardness values were in good agreement with those from the GTA weld. Single-pass HAZ regions exhibited higher Charpy V-notch impact toughness than the BM at both test temperatures of 293 K and 223 K (20 °C and -50 °C). Hardness increases were observed for multipass HAZ simulations employing an initial CGHAZ simulation.

Hard decoding algorithm for optimizing thresholds under general Markovian noise

NASA Astrophysics Data System (ADS)

Chamberland, Christopher; Wallman, Joel; Beale, Stefanie; Laflamme, Raymond

2017-04-01

Quantum error correction is instrumental in protecting quantum systems from noise in quantum computing and communication settings. Pauli channels can be efficiently simulated and threshold values for Pauli error rates under a variety of error-correcting codes have been obtained. However, realistic quantum systems can undergo noise processes that differ significantly from Pauli noise. In this paper, we present an efficient hard decoding algorithm for optimizing thresholds and lowering failure rates of an error-correcting code under general completely positive and trace-preserving (i.e., Markovian) noise. We use our hard decoding algorithm to study the performance of several error-correcting codes under various non-Pauli noise models by computing threshold values and failure rates for these codes. We compare the performance of our hard decoding algorithm to decoders optimized for depolarizing noise and show improvements in thresholds and reductions in failure rates by several orders of magnitude. Our hard decoding algorithm can also be adapted to take advantage of a code's non-Pauli transversal gates to further suppress noise. For example, we show that using the transversal gates of the 5-qubit code allows arbitrary rotations around certain axes to be perfectly corrected. Furthermore, we show that Pauli twirling can increase or decrease the threshold depending upon the code properties. Lastly, we show that even if the physical noise model differs slightly from the hypothesized noise model used to determine an optimized decoder, failure rates can still be reduced by applying our hard decoding algorithm.

Hard magnetic property enhancement of Co{sub 7}Hf-based ribbons by boron doping

DOE Office of Scientific and Technical Information (OSTI.GOV)

Chang, H. W.; Liao, M. C.; Shih, C. W.

2014-11-10

Hard magnetic property enhancement of melt spun Co{sub 88}Hf{sub 12} ribbons by boron doping is demonstrated. B-doping could not only remarkably enhance the magnetic properties from energy product ((BH){sub max}) of 2.6 MGOe and intrinsic coercivity ({sub i}H{sub c}) of 1.5 kOe for B-free Co{sub 88}Hf{sub 12} ribbons to (BH){sub max} = 7.7 MGOe and {sub i}H{sub c} = 3.1 kOe for Co{sub 85}Hf{sub 12}B{sub 3} ribbons but also improve the Curie temperature (T{sub C}) of 7:1 phase. The (BH){sub max} value achieved in Co{sub 85}Hf{sub 12}B{sub 3} ribbons is the highest in Co-Hf alloy ribbons ever reported, which is about 15% higher thanmore » that of Co{sub 11}Hf{sub 2}B ribbons spun at 16 m/s [M. A. McGuire, O. Rios, N. J. Ghimire, and M. Koehler, Appl. Phys. Lett. 101, 202401 (2012)]. The structural analysis confirms that B enters the orthorhombic Co{sub 7}Hf (7:1) crystal structure as interstitial atoms, forming Co{sub 7}HfB{sub x}, in the as-spun state. Yet B may diffuse out from the 7:1 phase after post-annealing, leading to the reduction of Curie temperature and the magnetic properties. The uniformly refined microstructure with B-doping results in high remanence (B{sub r}) and improves the squareness of demagnetization curve. The formation of interstitial-atom-modified Co{sub 7}HfB{sub x} phase and the microstructure refinement are the main reasons to give rise to the enhancement of hard magnetic properties in the B-containing Co{sub 7}Hf-based ribbons.« less

Effect of the addition of nano-sized sodium hexametaphosphate to fluoride toothpastes on tooth demineralization: an in vitro study.

PubMed

Dalpasquale, Giovanna; Delbem, Alberto Carlos Botazzo; Pessan, Juliano Pelim; Nunes, Gabriel Pereira; Gorup, Luiz Fernando; Neto, Francisco Nunes Souza; de Camargo, Emerson Rodrigues; Danelon, Marcelle

2017-06-01

This study evaluated the effect of toothpastes containing 1100 ppm F associated with nano-sized sodium hexametaphosphate (HMPnano) on enamel demineralization in vitro using a pH-cycling model. Bovine enamel blocks (4 mm × 4 mm, n = 72) selected by initial surface hardness (SHi) were randomly allocated into six groups (n = 12), according to the test toothpastes: without fluoride or HMPnano (Placebo), 550 ppm F (550F), 1100 ppm F (1100F), 1100F plus HMPnano at concentrations of 0.25% (1100F/0.25%HMPnano), 0.5% (1100F/0.5%HMPnano), and 1.0% (1100F/1.0%HMPnano). Blocks were treated 2×/day with slurries of toothpastes and submitted to five pH cycles (demineralizing/remineralizing solutions) at 37 °C. Next, final surface hardness (SHf), integrated loss subsurface hardness (ΔKHN), integrated mineral loss (g HA p × cm -3 ), and enamel fluoride (F) concentrations were determined. Data were analyzed by ANOVA and Student-Newman-Keuls test (p < 0.001). Toothpaste with 1100F/0.5%HMPnano led to the lowest mineral loss and the highest mineral concentration among all groups, which were 26% (SHf) and 21% (ΔKHN) lower and ~58% higher (g HA p × cm -3 ) when compared to 1100F (p < 0.001). Similar values of enamel F were observed for all fluoridated toothpastes (p > 0.001). The addition of 0.5%HMPnano to a 1100 F toothpaste significantly enhances its effects against enamel demineralization when compared to its counterpart without HMPnano in vitro. Toothpaste containing 1100 ppm F associated with HMPnano has a higher potential to reduce the demineralization compared to 1100 ppm F. This toothpaste could be a viable alternative to patients at high risk of caries.

Prognostic value of myocardial perfusion SPECT versus exercise electrocardiography in patients with ST-segment depression on resting electrocardiography.

PubMed

De Lorenzo, Andrea; Hachamovitch, Rory; Kang, Xingping; Gransar, Heidi; Sciammarella, Maria G; Hayes, Sean W; Friedman, John D; Cohen, Ishac; Germano, Guido; Berman, Daniel S

2005-01-01

The value of exercise-induced ST-segment depression for the prognostic evaluation of patients with 1 mm of ST depression or greater on the resting electrocardiogram is controversial. Patients who underwent exercise myocardial perfusion single photon emission computed tomography (MPS) and had resting ST depression of 1 mm or greater with a nondiagnostic exercise electrocardiographic response (n = 1122) were followed up for 3.4 +/- 2.3 years. Those with paced rhythm, pre-excitation, left bundle branch block, or myocardial revascularization within the first 60 days after MPS were excluded. Additional exercise-induced ST-segment depression was considered significant if > or = 2 mm MPS was scored semiquantitatively by use of a 20-segment model of the left ventricle; the percentage of myocardium involved with stress defects (% myo) was derived by normalizing to the maximal possible score of 80. Hard events were defined as nonfatal myocardial infarction or cardiac death. A Cox analysis was used to determine independent predictors of hard events among clinical, exercise, and nuclear variables. Hard event rates increased as a function of % myo for either patients with exercise-induced ST depression (1.4%/y for normal MPS vs 4.1%/y for % myo >10%, P < .03) or those without it (0.7%/y for normal MPS vs 3.0%/y for % myo >10%, P = .0001). Age, diabetes mellitus, shortness of breath as the presenting symptom, and % myo were independent predictors of hard events. Exercise-induced ST depression was predictive of hard events only when it was 3 mm or greater. The presence and extent of perfusion defects, reflected in the % myo, had incremental prognostic value over clinical variables and also over all degrees of exercise-induced ST depression. Although MPS effectively risk-stratifies patients with resting ST depression of 1 mm or greater, the prognostic value of exercise-induced ST depression is limited in these patients, with a small added risk when severe (> or = 3 mm).

Prognostic value of high-dose dobutamine stress magnetic resonance imaging in 1,493 consecutive patients: assessment of myocardial wall motion and perfusion.

PubMed

Korosoglou, Grigorios; Elhmidi, Yacine; Steen, Henning; Schellberg, Dieter; Riedle, Nina; Ahrens, Johannes; Lehrke, Stephanie; Merten, Constanze; Lossnitzer, Dirk; Radeleff, Jannis; Zugck, Christian; Giannitsis, Evangelos; Katus, Hugo A

2010-10-05

This study sought to determine the prognostic value of wall motion and perfusion assessment during high-dose dobutamine stress (DS) cardiac magnetic resonance imaging (MRI) in a large patient cohort. DS-MRI offers the possibility to integrate myocardial perfusion and wall motion analysis in a single examination for the detection of coronary artery disease (CAD). A total of 1,493 consecutive patients with suspected or known CAD underwent DS-MRI, using a standard protocol in a 1.5-T magnetic resonance scanner. Wall motion and perfusion were assessed at baseline and during stress, and outcome data including cardiac death, nonfatal myocardial infarction ("hard events"), and "late" revascularization performed >90 days after the MR scans were collected during a 2 ± 1 year follow-up period. Fifty-three hard events, including 14 cardiac deaths and 39 nonfatal infarctions, occurred during the follow-up period, whereas 85 patients underwent "late" revascularization. Using multivariable regression analysis, an abnormal result for wall motion or perfusion during stress yielded the strongest independent prognostic value for both hard events and late revascularization, clearly surpassing that of clinical and baseline magnetic resonance parameters (for wall motion: adjusted hazard ratio [HR] of 5.9 [95% confidence interval (CI): 2.5 to 13.6] for hard events and of 3.1 [95% CI: 1.7 to 5.6] for late revascularization, and for perfusion: adjusted HR of 5.4 [95% CI: 2.3 to 12.9] for hard events and of 6.2 [95% CI: 3.3 to 11.3] for late revascularization, p < 0.001 for all). DS-MRI can accurately identify patients who are at increased risk for cardiac death and myocardial infarction, separating them from those with normal findings, who have very low risk for future cardiac events. (Prognostic Value of High Dose Dobutamine Stress Magnetic Resonance Imaging; NCT00837005). Copyright © 2010 American College of Cardiology Foundation. Published by Elsevier Inc. All rights reserved.

Effects of combined plasma chromizing and shot peening on the fatigue properties of a Ti6Al4V alloy

NASA Astrophysics Data System (ADS)

Yu, Shouming; Liu, Daoxin; Zhang, Xiaohua; Du, Dongxing

2015-10-01

A plasma chromizing treatment was conducted on Ti6Al4V samples by employing the recently developed double glow plasma surface alloying technology. The Cr-alloyed layer consisted of four sub-layers, namely the Cr deposition, Cr2Ti, CrTi4, and Cr-Ti solid-solution layers. The local hardness and moduli were determined via nanoindentation. In addition, the fatigue properties of the samples were evaluated by using a rotating-bending fatigue machine under a given load. The results showed that the hardness or elastic moduli of the adjacent sub-layers differed significantly and the fatigue properties of the Ti6Al4V alloy deteriorated with the plasma chromizing treatment. This deterioration stemmed mainly from cracks initiated at the interfaces between the sub-layers and the microstructural changes of the substrate; these changes were induced by the high temperature used in the plasma chromizing process. However, the fatigue life of the plasma-chromized samples was increased by a shot peening post-treatment. The fatigue life of the samples resulting from this combination of treatments was slightly higher than that of the single-shot-peened Ti6Al4V substrate. In fact, the sample retaining only the Cr-Ti solid-solution layer (that is, the first three sub-layers were removed), when shot-peened, exhibited the highest fatigue life among all the tested samples; this was attributed to that sample having the highest residual compressive stress, the significant work hardening, and the good hardness to toughness balance.

EVOLUTION OF THE CROSS-CORRELATION AND TIME LAG OF 4U 1735-44 ALONG THE BRANCHES

DOE Office of Scientific and Technical Information (OSTI.GOV)

Lei Yajuan; Zhang Haotong; Zhang Chengmin

We analyze the cross-correlation function between the soft and hard X-rays of atoll source 4U 1735-44 with RXTE data, and find anti-correlated soft and hard time lags of about a hecto-second. In the island state, the observations do not show any obvious correlations, and most observations of the banana branch show a positive correlation. However, anti-correlations are detected in the upper banana branch. These results are different from those of Z-sources (Cyg X-2, GX 5-1), where anti-correlations are detected in the horizontal branch and upper normal branch. In this case, the lag timescales of both this atoll and Z-sources aremore » found to be similar, at a magnitude of several tens to hundreds of seconds. As a comparison, it is noted that anti-correlated lags lasting thousands of seconds have been reported from several black hole candidates in their intermediate states. In addition, for an observation containing four segments that show positive or anti-correlation, we analyze the spectral evolution with the hybrid model. In the observation, the anti-correlation is detected at the highest flux. The fitting results show that the Comptonized component is not the lowest at the highest flux, which suggests that the anti-correlation corresponds to the transition between the soft and hard states. Finally, we compare the corresponding results of atoll source 4U 1735-44 with those observed in Z-sources and black hole candidates, and the possible origins of the anti-correlated time lags are discussed.« less

Effect of Ar ion on the surface properties of low density polyethylene.

PubMed

Zaki, M F

2016-04-15

In this paper, low-density polyethylene (LDPE) was irradiated by argon ion with different fluences up to 10(15) ions/cm(2). The optical, chemical and hardness properties have been investigated using UV-Vis spectroscopy, Fourier transform infrared spectroscopy (FTIR), scanning electron microscope (SEM) and micro-indentation tester, respectively. The results showed the ion beam bombardment induced decreases in the transmittance of the irradiated polymer samples. This change in transmittance can be attributed to the formation of conjugated bonds i.e. possible formation of defects and/or carbon clusters. The indirect optical band gap decreased from 3.0 eV for the pristine sample to 2.3 eV for that sample irradiated with the highest fluence of the Ar ion beam. Furthermore, the number of carbon atoms and clusters increased with increasing Ar ion fluences. FTIR spectra showed the formation of new bands of the bombarded polymer samples. Furthermore, polar groups were created on the surface of the irradiated samples which refer to the increase of the hydrophilic nature of the surface of the irradiated samples. The Vicker's hardness increased from 4.9 MPa for the pristine sample to 17.9 MPa for those bombarded at the highest fluence. This increase is attributed to the increase in the crosslinking and alterations of the bombarded surface into hydrogenated amorphous carbon, which improves the hardness of the irradiated samples. The bombarded LDPE surfaces may be used in special applications to the field of the micro-electronic devices and shock absorbers. Copyright © 2016 Elsevier B.V. All rights reserved.

Political Compromise Makes the World Go 'Round

ERIC Educational Resources Information Center

Everett, Diana

2007-01-01

Compromise in any context is often hard to accept. It feels like a person is giving up on his or her ideals. This is especially true in dealing with politics. Legislative and congressional bills can be written with the highest of ideals in mind. By the time the bill progresses through committees and the floor debate process, it can look like a…

Southern pulpwood production, 1966

Treesearch

Dwane D. Van Hooser; Joe F. Christopher

1967-01-01

Pulpwood production in the South rose 7 percent in 1966, to 33,061,243 cords. This is the highest output on record and the ninth consecutive increase in annual production. Pine round-wood accounted for 57 percent of the increase, and residues or byproducts from other wood-using industries, 26 percent. The remainder was due to an increase in the harvest of hard-wood...

Nano-indentation investigations of (As2Se3)1-x: Snx and (As4S3Se3)1-x: Snx glasses

NASA Astrophysics Data System (ADS)

Harea, D. V.; Harea, E. E.; Iaseniuc, O. V.; Iovu, M. S.

2015-02-01

Experimental results on some physical and optical properties of (As2Se3)1-x:Snx and (As4S3Se3)1-x:Snx (x = 0-10 at %) glasses and amorphous films (d~2.0 μm) are presented. The bulk chalcogenide glasses are studied by X-ray diffraction spectroscopy and nanoindentation methods. It is established that the addition of these amounts of tin (x = 0-10 at %) does not lead to significant changes in the physical properties of the glass, such as values of stress and Young's modulus related to the modification of the density and compactness. It has been found that the addition of these amounts of tin in (As4S3Se3)1-x:Snx does not lead to significant changes in the glass physical properties, such as values of stress and Young's modulus related to the modification of the density and compactness. The study of the photoplastic effect is performed in situ, with illumination of the bulk and thin film samples during indentation as well as their indentation after illumination with a green laser (λ = 532 nm) at a power of P = 50 mV/cm2. The hardness is calculated from load-displacement curves by the Oliver-Pharr method. A sharp increase in hardness is registered if the tin concentration exceeds a value of 34% Sn. The hardness H of (As2Se3)1-x:Snx films varies between 115 and 130 kg/mm2. It is found that the hardness H of amorphous thin films is generally higher than the hardness of bulk samples with the same chemical composition. In this study, we are focused on the mechanical characteristics of high-purity As2Se3: Snx thin films. Keyword: Chalcogenide glasses, hardness,

A method for determining and exploring the distribution of organic matters and hardness salts in natural waters

NASA Astrophysics Data System (ADS)

Sargsyan, Suren

2017-11-01

A question regarding how organic matters in water are associated with hardness salts hasn't been completely studied. For partially clarifying this question, a water fractional separation and investigation method has been recommended. The experiments carried out by the recommended method showed that the dynamics of the distribution of total hardness and permanganate oxidation values in the fractions of frozen and melted water samples coincided completely based on which it has been concluded that organic matters in natural waters are associated with hardness salts and always distributed in this form. All these findings are useful information for the deep study of macro- and microelements in water.

The stability of amoxicillin trihydrate and potassium clavulanate combination in aqueous solutions.

PubMed

Jerzsele, Akos; Nagy, Gábor

2009-12-01

The effect of various environmental factors on the stability of aqueous solutions of amoxicillin-clavulanic acid combination in a veterinary water-soluble powder product was investigated. In the swine industry, the combination is administered via the drinking water, where both substances are quickly decomposed depending on several environmental factors. The degradation rate of the substances was determined in solutions of different water hardness levels (German hardness of 2, 6 and 10) and pH values (3.0, 7.0 and 10.0), and in troughs made of different materials (metal or plastic). Increasing the water hardness decreased the stability of both substances, amoxicillin being more stable at each hardness value than clavulanate. Amoxicillin trihydrate proved to be most stable at an acidic pH, while increasing the pH decreased its stability (P < 0.05). Maximum stability of potassium clavulanate was experienced at neutral pH, while its decomposition rate was significantly higher at acidic and alkaline pH values (P < 0.01). The stability of the amoxicillin-clavulanic acid combination depends mainly on the less stable clavulanate, although the effect of metallic ions significantly increased the decomposition rate of amoxicillin, rendering it less stable in metal troughs than clavulanate (P < 0.05). Therefore, the amoxicillin-clavulanic acid combination should be administered to the animals in soft water, at neutral pH and in plastic troughs.

Toxicity of manganese to Ceriodaphnia dubia and Hyalella azteca

USGS Publications Warehouse

Lasier, P.J.; Winger, P.V.; Bogenrieder, K.J.

2000-01-01

Manganese is a toxic element frequently overlooked when assessing toxicity of effluents, sediments and pore waters. Manganese can be present at toxic levels in anoxic solutions due to its increased solubility under chemically-reducing conditions, and it can remain at those levels for days in aerated test waters due to slow precipitation kinetics. Ceriodaphnia dubia and Hyalella azteca are freshwater organisms often used for toxicity testing and recommended for assessments of effluents and pore waters. Lethal and reproductive-inhibition concentrations of Mn were determined for C. dubia in acute 48h tests and chronic 3-brood tests using animals <24 h old and between 24 and 48 h old. Sensitivity of H. azteca was determined with 7d old animals in acute 96h tests. Tests were run at three levels of water hardness to assess the amelioratory effect, which was often significant. Manganese concentrations were measured analytically at test initiation and after 96 h for calculations of toxicity endpoints and determinations of Mn precipitation during the tests. Minimal amounts of Mn (below 3%) precipitated within 96 h. LC50s determined for H. azteca progressively increased from 3.0 to 8.6 to 13.7 mg Mn/L in soft, moderately-hard and hard waters, respectively. The tolerance of C. dubia to Mn was not significantly different between moderately-hard and hard waters, but was significantly lower in soft water. There was no significant difference in Mn sensitivity between the ages of C. dubia tested. Acute LC50 values for C. dubia averaged 6.2, 14.5 and 15.2 mg Mn/L and chronic IC50 values averaged 3.9, 8.5 and 11.5 mg Mn/L for soft, moderately-hard and hard waters, respectively. Manganese toxicity should be considered when assessing solutions with concentrations near these levels.

Rational design of the exchange-spring permanent magnet.

PubMed

Jiang, J S; Bader, S D

2014-02-12

The development of the optimal exchange-spring permanent magnet balances exchange hardening, magnetization enhancement, and the feasibility of scalable fabrication. These requirements can be met with a rational design of the microstructural characteristics. The magnetization processes in several model exchange-spring structures with different geometries have been analyzed with both micromagnetic simulations and nucleation theory. The multilayer geometry and the soft-cylinders-in-hard-matrix geometry have the highest achievable figure of merit (BH)max, while the soft-spheres-in-hard-matrix geometry has the lowest upper limit for (BH)max. The cylindrical geometry permits the soft phase to be larger and does not require strict size control. Exchange-spring permanent magnets based on the cylindrical geometry may be amenable to scaled-up fabrication.

Identifying a Robust and Practical Quasar Accretion-Rate Indicator Using the Chandra Archive

NASA Astrophysics Data System (ADS)

Shemmer, Ohad

2017-09-01

Understanding the rapid growth of supermassive black holes and the assembly of their host galaxies is severely limited by the lack of reliable estimates of black-hole mass and accretion rate in distant quasars. We propose to utilize the Chandra archive to identify the most reliable and practical Eddington-ratio indicator by investigating diagnostics of quasar accretion power in the hard-X-ray, C IV, and Hbeta spectral bands of a carefully-selected sample of optically-selected sources. We will perform a ``stress test'' to each of these diagnostics, relying critically on the hard-X-ray observable properties, and deliver a prescription for the most robust Eddington-ratio estimate that can be utilized economically at the highest accessible redshifts.

RC64, a Rad-Hard Many-Core High- Performance DSP for Space Applications

NASA Astrophysics Data System (ADS)

Ginosar, Ran; Aviely, Peleg; Gellis, Hagay; Liran, Tuvia; Israeli, Tsvika; Nesher, Roy; Lange, Fredy; Dobkin, Reuven; Meirov, Henri; Reznik, Dror

2015-09-01

RC64, a novel rad-hard 64-core signal processing chip targets DSP performance of 75 GMACs (16bit), 150 GOPS and 38 single precision GFLOPS while dissipating less than 10 Watts. RC64 integrates advanced DSP cores with a multi-bank shared memory and a hardware scheduler, also supporting DDR2/3 memory and twelve 3.125 Gbps full duplex high speed serial links using SpaceFibre and other protocols. The programming model employs sequential fine-grain tasks and a separate task map to define task dependencies. RC64 is implemented as a 300 MHz integrated circuit on a 65nm CMOS technology, assembled in hermetically sealed ceramic CCGA624 package and qualified to the highest space standards.

RC64, a Rad-Hard Many-Core High-Performance DSP for Space Applications

NASA Astrophysics Data System (ADS)

Ginosar, Ran; Aviely, Peleg; Liran, Tuvia; Alon, Dov; Mandler, Alberto; Lange, Fredy; Dobkin, Reuven; Goldberg, Miki

2014-08-01

RC64, a novel rad-hard 64-core signal processing chip targets DSP performance of 75 GMACs (16bit), 150 GOPS and 20 single precision GFLOPS while dissipating less than 10 Watts. RC64 integrates advanced DSP cores with a multi-bank shared memory and a hardware scheduler, also supporting DDR2/3 memory and twelve 2.5 Gbps full duplex high speed serial links using SpaceFibre and other protocols. The programming model employs sequential fine-grain tasks and a separate task map to define task dependencies. RC64 is implemented as a 300 MHz integrated circuit on a 65nm CMOS technology, assembled in hermetically sealed ceramic CCGA624 package and qualified to the highest space standards.

Bioaccumulation, stress, and swimming impairment in Daphnia magna exposed to multiwalled carbon nanotubes, graphene, and graphene oxide.

PubMed

Cano, Amanda M; Maul, Jonathan D; Saed, Mohammad; Shah, Smit A; Green, Micah J; Cañas-Carrell, Jaclyn E

2017-08-01

The use of carbon-based nanomaterials (CNMs) such as multiwalled carbon nanotubes (MWCNTs), graphene, and graphene oxide (GO) is increasing across many applications because of their unique and versatile properties. These CNMs may enter the aquatic environment through many pathways, creating the potential for organism exposure. The present study addresses the bioaccumulation and toxicity seen in Daphnia magna exposed to CNMs dispersed in sodium dodecyl benzene sulfonate (SDBS). In study I, D. magna were exposed to varying outer diameters of MWCNTs for 24 h in moderately hard or hard freshwater. Bioaccumulation of MWCNT was found in all treatments, with the highest concentrations (0.53 ± 0.27 μg/g) in D. magna exposed in hard freshwater (p < 0.005). The median lethal concentration (LC50) was determined for D. magna exposed to CNMs in moderately hard and hard freshwater. In study II, D. magna were exposed to CNMs for 72 h in moderately hard freshwater to assess swimming velocity and generation of reactive oxygen species (ROS) detected by dichlorofluorescein fluorescence. An overall decrease was seen in D. magna swimming velocity after exposure to CNMs. The generation of ROS was significantly higher (1.54 ± 0.38 dichlorofluorescein mM/mg dry wt) in D. magna exposed to MWCNTs of smaller outer diameters than in controls after 72 h (p < 0.05). These results suggest that further investigation of CNM toxicity and behavior in the aquatic environment is needed. Environ Toxicol Chem 2017;36:2199-2204. © 2017 SETAC. © 2017 SETAC.

Use of Multiple Linear Regression Models for Setting Water Quality Criteria for Copper: A Complementary Approach to the Biotic Ligand Model.

PubMed

Brix, Kevin V; DeForest, David K; Tear, Lucinda; Grosell, Martin; Adams, William J

2017-05-02

Biotic Ligand Models (BLMs) for metals are widely applied in ecological risk assessments and in the development of regulatory water quality guidelines in Europe, and in 2007 the United States Environmental Protection Agency (USEPA) recommended BLM-based water quality criteria (WQC) for Cu in freshwater. However, to-date, few states have adopted BLM-based Cu criteria into their water quality standards on a state-wide basis, which appears to be due to the perception that the BLM is too complicated or requires too many input variables. Using the mechanistic BLM framework to first identify key water chemistry parameters that influence Cu bioavailability, namely dissolved organic carbon (DOC), pH, and hardness, we developed Cu criteria using the same basic methodology used by the USEPA to derive hardness-based criteria but with the addition of DOC and pH. As an initial proof of concept, we developed stepwise multiple linear regression (MLR) models for species that have been tested over wide ranges of DOC, pH, and hardness conditions. These models predicted acute Cu toxicity values that were within a factor of ±2 in 77% to 97% of tests (5 species had adequate data) and chronic Cu toxicity values that were within a factor of ±2 in 92% of tests (1 species had adequate data). This level of accuracy is comparable to the BLM. Following USEPA guidelines for WQC development, the species data were then combined to develop a linear model with pooled slopes for each independent parameter (i.e., DOC, pH, and hardness) and species-specific intercepts using Analysis of Covariance. The pooled MLR and BLM models predicted species-specific toxicity with similar precision; adjusted R 2 and R 2 values ranged from 0.56 to 0.86 and 0.66-0.85, respectively. Graphical exploration of relationships between predicted and observed toxicity, residuals and observed toxicity, and residuals and concentrations of key input parameters revealed many similarities and a few key distinctions between the performances of the two models. The pooled MLR model was then applied to the species sensitivity distribution to derive acute and chronic criteria equations similar in form to the USEPA's current hardness-based criteria equations but with DOC, pH, and hardness as the independent variables. Overall, the MLR is less responsive to DOC than the BLM across a range of hardness and pH conditions but more responsive to hardness than the BLM. Additionally, at low and intermediate hardness, the MLR model is less responsive than the BLM to pH, but the two models respond comparably at high hardness. The net effect of these different response profiles is that under many typical water quality conditions, MLR- and BLM-based criteria are quite comparable. Indeed, conditions where the two models differ most (high pH/low hardness and low pH/high hardness) are relatively rare in natural aquatic systems. We suggest that this MLR-based approach, which includes the mechanistic foundation of the BLM but is also consistent with widely accepted hardness-dependent WQC in terms of development and form, may facilitate adoption of updated state-wide Cu criteria that more accurately account for the parameters influencing Cu bioavailability than current hardness-based criteria.

Gait of dairy cows on floors with different slipperiness.

PubMed

Telezhenko, E; Magnusson, M; Bergsten, C

2017-08-01

This study assessed the slip resistance of different types of solid flooring in cattle housing using a range of technical tests and gait analysis. Dynamic and static coefficient of friction, skid resistance, and abrasiveness were tested on concrete flooring with a smooth finish, a grooved pattern, or a tamped pattern, acid-resistant mastic asphalt, soft rubber mats, and a worn slatted concrete floor. Coefficients of friction and skid resistance were tested under clean and slurry-soiled conditions. Linear kinematic variables were assessed in 40 cows with trackway measurements after the cows passed over the floors in a straight walk. All gait variables were assessed as deviations from those obtained on the slatted concrete floor, which was used as a baseline. The coefficient of friction tests divided the floors into 3 categories: concrete flooring, which had a low coefficient of friction (0.29-0.41); mastic asphalt flooring, which had medium values (0.38-0.45); and rubber mats, which had high values (0.49-0.57). The highest abrasion (g/10 m) was on the asphalt flooring (4.48), and the concrete flooring with a tamped pattern had significantly higher abrasiveness (2.77) than the other concrete floors (1.26-1.60). Lowest values on the skid-resistance tests (dry/wet) were for smooth concrete (79/35) and mastic asphalt (65/47), especially with a slurry layer on the surface. Gait analysis mainly differentiated floors with higher friction and abrasion by longer strides and better tracking. Step asymmetry was lower on floors with high skid-resistance values. The most secure cow gait, in almost every aspect, was observed on soft rubber mats. Relationships between gait variables and physical floor characteristics ranged from average to weak (partial correlations 0.54-0.16). Thus, none of the physical characteristics alone was informative enough to characterize slip resistance. With reference to gait analysis, the abrasiveness of the hard surfaces was more informative than the coefficient of friction, but the effect of pattern was better detected by skid-resistance measurements. Consequently, several physical characteristics are needed to objectively describe the slip resistance of cattle floors. Soft rubber mats gave better tracking than hard, solid floors, even with a grooved surface or a tamped pattern. Copyright © 2017 American Dairy Science Association. Published by Elsevier Inc. All rights reserved.

Comparison of mechanical properties of three machinable ceramics with an experimental fluorophlogopite glass ceramic.

PubMed

Leung, Brian T W; Tsoi, James K H; Matinlinna, Jukka P; Pow, Edmond H N

2015-09-01

Fluorophlogopite glass ceramic (FGC) is a biocompatible, etchable, and millable ceramic with fluoride releasing property. However, its mechanical properties and reliability compared with other machinable ceramics remain undetermined. The purpose of this in vitro study was to compare the mechanical properties of 3 commercially available millable ceramic materials, IPS e.max CAD, Vitablocs Mark II, and Vita Enamic, with an experimental FGC. Each type of ceramic block was sectioned into beams (n=15) of standard dimensions of 2×2×15 mm. Before mechanical testing, specimens of the IPS e.max CAD group were further fired for final crystallization. Flexural strength was determined by the 3-point bend test with a universal loading machine at a cross head speed of 1 mm/min. Hardness was determined with a hardness tester with 5 Vickers hardness indentations (n=5) using a 1.96 N load and a dwell time of 15 seconds. Selected surfaces were examined by scanning electron microscopy and energy-dispersive x-ray spectroscopy. Data were analyzed by the 1-way ANOVA test and Weibull analysis (α=.05). Weibull parameters, including the Weibull modulus (m) as well as the characteristic strength at 63.2% (η) and 10.0% (B10), were obtained. A significant difference in flexural strength (P<.001) was found among groups, with IPS e.max CAD (341.88 ±40.25 MPa)>Vita Enamic (145.95 ±12.65 MPa)>Vitablocs Mark II (106.67 ±18.50 MPa), and FGC (117.61 ±7.62 MPa). The Weibull modulus ranged from 6.93 to 18.34, with FGC showing the highest Weibull modulus among the 4 materials. The Weibull plot revealed that IPS e.max CAD>Vita Enamic>FGC>Vitablocs Mark II for the characteristic strength at both 63.2% (η) and 10.0% (B10). Significant difference in Vickers hardness among groups (P<.001) was found with IPS e.max CAD (731.63 ±30.64 H(V))>Vitablocs Mark II (594.74 ±25.22 H(V))>Vita Enamic (372.29 ±51.23 H(V))>FGC (153.74 ±23.62 H(V)). The flexural strength and Vickers hardness of IPS e.max CAD were significantly higher than those of the 3 materials tested. The FGC's flexural strength was comparable with Vitablocs Mark II. The FGC's Weibull modulus was the highest, while its Vickers hardness was the lowest among the materials tested. Copyright © 2015 Editorial Council for the Journal of Prosthetic Dentistry. Published by Elsevier Inc. All rights reserved.

Do Work Beliefs Moderate the Relationship Between Work Interruptions, Wellbeing and Psychosomatic Symptoms?

PubMed Central

Zoupanou, Zoi(e); Rydstedt, Leif W.

2017-01-01

The purpose of this study was to explore the moderating effects of work beliefs in the relationship between work interruptions and general health, wellbeing and reports of psychosomatic symptoms. Self-report data were gathered from 310 employees from different occupational sectors. Results revealed that beliefs in hard work and morality ethic moderated the positive appraisal of work interruptions and acted as protective factors on impaired general health and wellbeing. The relationship was stronger among employees who endorsed strong beliefs in hard work and did not have regard for morality/ethics as a value. Likewise, beliefs in delay of gratification and morality/ethics moderated positive appraisal of work interruptions and reduced psychosomatic complaints. More specifically, the relationship was stronger among employees who had strong belief in the values of delayed gratification and weaker morality/ethics. These findings indicate that organisations should adopt work ideology or practices focused on work values particularly of hard work, delay of gratification and conformity to morality as protective factors that reduce the impact of work interruptions on employees’ general health and wellbeing. PMID:28580023

Foot length, chest and head circumference measurements in detection of Low birth weight neonates in Mekelle, Ethiopia: a hospital based cross sectional study.

PubMed

Hadush, Marta Yemane; Berhe, Amanuel Hadgu; Medhanyie, Araya Abrha

2017-04-21

Low birth weight (Birth weight < 2500 g) is a leading cause of prenatal and neonatal deaths. The early identification of Low birth weight (LBW) neonates is essential for any comprehensive initiative to improve their chance of survival. However, a large proportion of births in developing countries take place at home and birth weight statistics are not available. Therefore, there is a need to develop simple, inexpensive and practical methods to identify low birth weight (LBW) neonates soon after birth. This is a hospital based cross sectional study. Four hundred twenty two (422) live born neonates were included and anthropometric measurements were carried out within 24 h of birth by three trained nurses. Birth weight was measured by digital scale. Head and chest circumference were measured by using non extendable measuring tape and foot length with hard transparent plastic ruler. Data was entered into SPSS version 20 for analysis. Characteristics of study participants were analyzed using descriptive statistics such as frequency and percentage for categorical data and mean and standard deviation for continuous data. Correlation with birth weight using Pearson's correlation coefficient and linear regression were used to identify the association between dependent and independent variables. Receiver operating characteristic (ROC) curve was used to evaluate accuracy of the anthropometric measurements to predict LBW. The prevalence of low birth weight was found to be 27%. All anthropometric measurements had a positive correlation with birth weight, chest circumference attaining the highest correlation with birth weight (r = 0.85) and foot length had the weakest correlation (r = 0.74). Head circumference had the highest predictive value for birth weight (AUC = 0.93) followed by Chest circumference (AUC = 0.91). A cut off point of chest circumference 30.15 cm had 84.2% sensitivity, 85.4% specificity and diagnostic accuracy (P < 0.001). A cut off point of head circumference 33.25 had the highest positive predictive value (77%). Chest circumference and head circumference were found to be better surrogate measurements to identify low birth weight neonates.

A comparative evaluation of groundwater suitability for irrigation and drinking purposes in two intensively cultivated districts of Punjab, India

NASA Astrophysics Data System (ADS)

Kumar, Manish; Kumari, Kalpana; Ramanathan, Al.; Saxena, Rajinder

2007-11-01

Punjab is the most cultivated state in India with the highest consumption of fertilizers. Patiala and Muktsar districts are two agricultural dominated districts of Punjab located in extreme south-east and south-west of the state. This paper highlights temporal variations of the groundwater quality and compares its suitability for irrigation and drinking purpose in these two districts. Water samples were collected in March and September 2003, representing the pre-monsoon and post-monsoon seasons, respectively. Water samples were analysed for almost all major cations, anions, dissolved heavy metals and turbidity. Parameters like sodium adsorption ratio, % sodium, residual sodium carbonate, total hardness, potential salinity, Kelley’s ratio, magnesium ratio, index of base exchange and permeability index were calculated on the basis of chemical data. A questionnaire was also used to investigate perception of villagers on taste and odour. Comparison of the concentration of the chemical constituents with WHO (world health organization) drinking water standards of 2004 and various classifications show that present status of groundwater in Patiala is better for irrigation and drinking purposes except for a few locations with a caution that it may deteriorate in near future. In Muktsar, groundwater is not suitable for drinking. Higher total hardness (TH) and total dissolved solids at numerous places indicate the unsuitability of groundwater for drinking and irrigation. Results obtained in this forms baseline data for the utility of groundwater. In terms of monsoon impact, Patiala groundwater shows dilution and flushing but Muktsar samples show excessive leaching of different chemical components into the groundwater leading to the enrichment of different anions and cations indicating pollution from extraneous sources. No clear correlation between the quality parameters studied here and perceived quality in terms of satisfactory taste response were obtained at electrical conductivity values higher than the threshold minimum acceptable value.

Comparisons between vs30 and spectral response for 30 sites in Newcastle, Australia from collocated seismic cone penetrometer, active- and passive-source vs data

USGS Publications Warehouse

Volti, Theodora; Burbidge, David; Collins, Clive; Asten, Michael W.; Odum, Jackson K.; Stephenson, William J.; Pascal, Chris; Holzschuh, Josef

2016-01-01

Although the time‐averaged shear‐wave velocity down to 30 m depth (VS30) can be a proxy for estimating earthquake ground‐motion amplification, significant controversy exists about its limitations when used as a single parameter for the prediction of amplification. To examine this question in absence of relevant strong‐motion records, we use a range of different methods to measure the shear‐wave velocity profiles and the resulting theoretical site amplification factors (AFs) for 30 sites in the Newcastle area, Australia, in a series of blind comparison studies. The multimethod approach used here combines past seismic cone penetrometer and spectral analysis of surface‐wave data, with newly acquired horizontal‐to‐vertical spectral ratio, passive‐source surface‐wave spatial autocorrelation (SPAC), refraction microtremor (ReMi), and multichannel analysis of surface‐wave data. The various measurement techniques predicted a range of different AFs. The SPAC and ReMi techniques have the smallest overall deviation from the median AF for the majority of sites. We show that VS30 can be related to spectral response above a period T of 0.5 s but not necessarily with the maximum amplification according to the modeling done based on the measured shear‐wave velocity profiles. Both VS30 and AF values are influenced by the velocity ratio between bedrock and overlying sediments and the presence of surficial thin low‐velocity layers (<2  m thick and <150  m/s), but the velocity ratio is what mostly affects the AF. At 0.20.5  s do the amplification curves consistently show higher values for soft site classes and lower for hard classes.

A color contrast aided density imaging technique to differentiate between dental hard tissues and its relevance.

PubMed

Shetty, Devi Charan; Urs, Aadithya B; Manchanda, Adesh; Sirohi, Yuthicka

2011-01-01

Radiographic interpretation of a disease requires knowledge about normal structures. The calcifying jaw diseases can range from radiolucent areas to varying degrees of calcification. Therefore, it is vital to differentiate radiographically between various hard tissues. We have illustrated the use of computed tomography scan to quantify the calcified structures as dentin and enamel in a case of ameloblastic fibro-odontoma. The enamel, dentin and cementum showed different values. The "Dentascan" can be used to distinguish the hard tissues in a variety of calcifying diseases of jaws.

In Vitro Comparative Study of Two Different Bleaching Agents on Micro-hardness Dental Enamel.

PubMed

Fatima, Nazish; Ali Abidi, Syed Yawar; Meo, Ashraf Ali

2016-02-01

To evaluate the effect of home-use bleaching agent containing 16% Carbamide Peroxide (CP) and in-office bleaching agent containing 38% Hydrogen Peroxide (HP) on enamel micro-hardness. An in vitroexperimental study. Department of Operative Dentistry and Science of Dental Materials at Dr. Ishrat-ul-Ebad Khan Institute of Oral Health Sciences, Dow University of Health Sciences and Material Engineering Department of NED University of Engineering and Technology, Karachi, from July to December 2014. Atotal of 90 enamel slabs from 45 sound human 3rd molar were randomly divided into 3 groups. Each group contained 30 specimens (n=30). Group 1 was kept in artificial saliva at 37°C in incubator during the whole experiment. However, Groups 2 and 3 were treated with power whitening gel and tooth whitening pen respectively. After bleaching session, specimens were thoroughly rinsed with deionized water again for 10 seconds and then stored in artificial saliva at 37°C in incubator. Artificial saliva was changed after every 2 days. The Vickers hardness tester (Wolpert 402 MVD, Germany) was adjusted to a load of 0.1 kg (100 gm) and dwell time of 5 seconds. Three Vickers were performed on each specimen using a hardness tester according to the ISO 6507-3:1998 specification. Micro-hardness measurements were performed before and after bleaching at day 1, 7 and 14. In the control group, the baseline micro-hardness was 181.1 ±9.3 which was reduced after the storage on day 1, 7 and 14 (p = 0.104). In Group 2, baseline micro-hardness was 180.4 ±10.1 which was reduced to 179.79 ±10.0 units after day 1. Whereas, on day 7 and 14, the values of micro-hardness were 179.8 ±10 and 179.7 ±10.29, respectively (p=0.091). Furthermore, the baseline micro-hardness in Group 3 was 174.0 ±22.9 units which was reduced to 173 ±23 on day 1, 170 ±30 on day 7 and 173 ±23 on day 14 (p = 0.256). The statistically insignificant difference was found among micro-hardness values of different bleaching agents (p = 0.118). Bleaching with 38% Hydrogen Peroxide (HP) and 16% Carbamide Peroxide (CP) resulted in insignificant effect on surface micro-hardness of enamel.

Experimental investigation and modelling of surface roughness and resultant cutting force in hard turning of AISI H13 Steel

NASA Astrophysics Data System (ADS)

Boy, M.; Yaşar, N.; Çiftçi, İ.

2016-11-01

In recent years, turning of hardened steels has replaced grinding for finishing operations. This process is compared to grinding operations; hard turning has higher material removal rates, the possibility of greater process flexibility, lower equipment costs, and shorter setup time. CBN or ceramic cutting tools are widely used hard part machining. For successful application of hard turning, selection of suitable cutting parameters for a given cutting tool is an important step. For this purpose, an experimental investigation was conducted to determine the effects of cutting tool edge geometry, feed rate and cutting speed on surface roughness and resultant cutting force in hard turning of AISI H13 steel with ceramic cutting tools. Machining experiments were conducted in a CNC lathe based on Taguchi experimental design (L16) in different levels of cutting parameters. In the experiments, a Kistler 9257 B, three cutting force components (Fc, Ff and Fr) piezoelectric dynamometer was used to measure cutting forces. Surface roughness measurements were performed by using a Mahrsurf PS1 device. For statistical analysis, analysis of variance has been performed and mathematical model have been developed for surface roughness and resultant cutting forces. The analysis of variance results showed that the cutting edge geometry, cutting speed and feed rate were the most significant factors on resultant cutting force while the cutting edge geometry and feed rate were the most significant factor for the surface roughness. The regression analysis was applied to predict the outcomes of the experiment. The predicted values and measured values were very close to each other. Afterwards a confirmation tests were performed to make a comparison between the predicted results and the measured results. According to the confirmation test results, measured values are within the 95% confidence interval.

Novel platens to measure the hardness of a pentagonal shaped tablet.

PubMed

Malladi, Jaya; Sidik, Kurex; Wu, Sutan; McCann, Ryan; Dougherty, Jeffrey; Parab, Prakash; Carragher, Thomas

2017-03-01

Tablet hardness, a measure of the breaking force of a tablet, is based on numerous factors. These include the shape of the tablet and the mode of the application of force. For instance, when a pentagonal-shaped tablet was tested with a traditional hardness tester with flat platens, there was a large variation in hardness measurements. This was due to the propensity of vertices of the tablet to crush, referred to as an "improper break". This article describes a novel approach to measure the hardness of pentagonal-shaped tablets using modified platens. The modified platens have more uniform loading than flat platens. This is because they reduce loading on the vertex of the pentagon and apply forces on tablet edges to generate reproducible tablet fracture. The robustness of modified platens was assessed using a series of studies, which included feasibility and Gauge Repeatability & Reproducibility (R&R) studies. A key finding was that improper breaks, generated frequently with a traditional hardness tester using flat platens, were eliminated. The Gauge R&R study revealed that the tablets tested with novel platens generated consistent values in hardness measurements, independent of batch, hardness level, and day of testing, operator and tablet dosage strength.

Housing and Demographic Risk Factors Impacting Foot and Musculoskeletal Health in African Elephants [Loxodonta africana] and Asian Elephants [Elephas maximus] in North American Zoos.

PubMed

Miller, Michele A; Hogan, Jennifer N; Meehan, Cheryl L

2016-01-01

For more than three decades, foot and musculoskeletal conditions have been documented among both Asian [Elephas maximus] and African [Loxodonta africana] elephants in zoos. Although environmental factors have been hypothesized to play a contributing role in the development of foot and musculoskeletal pathology, there is a paucity of evidence-based research assessing risk. We investigated the associations between foot and musculoskeletal health conditions with demographic characteristics, space, flooring, exercise, enrichment, and body condition for elephants housed in North American zoos during 2012. Clinical examinations and medical records were used to assess health indicators and provide scores to quantitate conditions. Using multivariable regression models, associations were found between foot health and age [P value = 0.076; Odds Ratio = 1.018], time spent on hard substrates [P value = 0.022; Odds Ratio = 1.014], space experienced during the night [P value = 0.041; Odds Ratio = 1.008], and percent of time spent in indoor/outdoor exhibits during the day [P value < 0.001; Odds Ratio = 1.003]. Similarly, the main risk factors for musculoskeletal disorders included time on hard substrate [P value = 0.002; Odds Ratio = 1.050] and space experienced in indoor/outdoor exhibits [P value = 0.039; Odds Ratio = 1.037]. These results suggest that facility and management changes that decrease time spent on hard substrates will improve elephant welfare through better foot and musculoskeletal health.

Housing and Demographic Risk Factors Impacting Foot and Musculoskeletal Health in African Elephants [Loxodonta africana] and Asian Elephants [Elephas maximus] in North American Zoos

PubMed Central

Miller, Michele A.; Hogan, Jennifer N.; Meehan, Cheryl L.

2016-01-01

For more than three decades, foot and musculoskeletal conditions have been documented among both Asian [Elephas maximus] and African [Loxodonta africana] elephants in zoos. Although environmental factors have been hypothesized to play a contributing role in the development of foot and musculoskeletal pathology, there is a paucity of evidence-based research assessing risk. We investigated the associations between foot and musculoskeletal health conditions with demographic characteristics, space, flooring, exercise, enrichment, and body condition for elephants housed in North American zoos during 2012. Clinical examinations and medical records were used to assess health indicators and provide scores to quantitate conditions. Using multivariable regression models, associations were found between foot health and age [P value = 0.076; Odds Ratio = 1.018], time spent on hard substrates [P value = 0.022; Odds Ratio = 1.014], space experienced during the night [P value = 0.041; Odds Ratio = 1.008], and percent of time spent in indoor/outdoor exhibits during the day [P value < 0.001; Odds Ratio = 1.003]. Similarly, the main risk factors for musculoskeletal disorders included time on hard substrate [P value = 0.002; Odds Ratio = 1.050] and space experienced in indoor/outdoor exhibits [P value = 0.039; Odds Ratio = 1.037]. These results suggest that facility and management changes that decrease time spent on hard substrates will improve elephant welfare through better foot and musculoskeletal health. PMID:27415763

Aircraft accident report : ground spoiler activation in flight/hard landing Valujet Airlines Flight 558, Douglas DC-9-32, N922VV Nashville, Tennessee, January 7, 1996

DOT National Transportation Integrated Search

1996-12-11

Adopted: December 11,1996. Notation 6781. This report explains the ground spoiler activation in flight and subsequent hard landing of ValuJet Airlines flight 558, N922VV, a Douglas DC-9-32 at Nashville International Airport, Nashville, Tennessee. The...

Soft Power and Hard Measures: Large-Scale Assessment, Citizenship and the European Union

ERIC Educational Resources Information Center

Rutkowski, David; Engel, Laura C.

2010-01-01

This article explores the International Civic and Citizenship Education Study (ICCS) with particular emphasis on the European Union's (EU's) involvement in the regional portion. Using the ICCS, the EU actively combines hard measures with soft power, allowing the EU to define and steer cross-national rankings of values of EU citizenship. The…

Relationship between solvent retention capacity and protein molecular weight distribution, quality characteristics, and breadmaking functionality of hard red spring wheat flour

USDA-ARS?s Scientific Manuscript database

In order to investigate suitability of solvent retention capacity (SRC) test for quality assessment of hard red spring (HRS) wheat flour, ten HRS genotypes from six locations in North Dakota State were analyzed for SRC and flour and breadmaking quality characteristics. The SRC values were significa...

DOE Office of Scientific and Technical Information (OSTI.GOV)

Deibler, Lisa Anne; Brown, Arthur; Puskar, Joseph D.

Drawn 304L stainless steel tubing was subjected to 42 different annealing heat treatments with the goal of initializing a microstructural model to select a heat treatment to soften the tubing from a hardness of 305 Knoop to 225–275 Knoop. The amount of recrystallization and grain size caused by 18 heat treatments were analyzed via optical microscopy and image analysis, revealing the full range of recrystallization from 0 to 100%. The formation of carbides during the longer duration and higher-temperature heat treatments was monitored via transmission electron microscope evaluation. The experimental results informed a model which includes recovery, recrystallization, and grainmore » growth to predict microstructure and hardness. After initialization of the model, it was able to predict hardness with a R 2 value of 0.95 and recrystallization with an R 2 value of 0.99. As a result, the model was then utilized in the design and testing of a heat treatment to soften the tubing.« less

Annealing of Co-Cr dental alloy: effects on nanostructure and Rockwell hardness.

PubMed

Ayyıldız, Simel; Soylu, Elif Hilal; Ide, Semra; Kılıç, Selim; Sipahi, Cumhur; Pişkin, Bulent; Gökçe, Hasan Suat

2013-11-01

The aim of the study was to evaluate the effect of annealing on the nanostructure and hardness of Co-Cr metal ceramic samples that were fabricated with a direct metal laser sintering (DMLS) technique. Five groups of Co-Cr dental alloy samples were manufactured in a rectangular form measuring 4 × 2 × 2 mm. Samples fabricated by a conventional casting technique (Group I) and prefabricated milling blanks (Group II) were examined as conventional technique groups. The DMLS samples were randomly divided into three groups as not annealed (Group III), annealed in argon atmosphere (Group IV), or annealed in oxygen atmosphere (Group V). The nanostructure was examined with the small-angle X-ray scattering method. The Rockwell hardness test was used to measure the hardness changes in each group, and the means and standard deviations were statistically analyzed by one-way ANOVA for comparison of continuous variables and Tukey's HSD test was used for post hoc analysis. P values of <.05 were accepted as statistically significant. The general nanostructures of the samples were composed of small spherical entities stacked atop one another in dendritic form. All groups also displayed different hardness values depending on the manufacturing technique. The annealing procedure and environment directly affected both the nanostructure and hardness of the Co-Cr alloy. Group III exhibited a non-homogeneous structure and increased hardness (48.16 ± 3.02 HRC) because the annealing process was incomplete and the inner stress was not relieved. Annealing in argon atmosphere of Group IV not only relieved the inner stresses but also decreased the hardness (27.40 ± 3.98 HRC). The results of fitting function presented that Group IV was the most homogeneous product as the minimum bilayer thickness was measured (7.11 Å). After the manufacturing with DMLS technique, annealing in argon atmosphere is an essential process for Co-Cr metal ceramic substructures. The dentists should be familiar with the materials that are used in clinic for prosthodontics treatments.

Characterization, photophysical and DFT calculation study on 2-(2,4-difluorophenyl)-1-(4-methoxyphenyl)-1H-imidazo[4,5-f][1,10]phenanthroline ligand.

PubMed

Jayabharathi, Jayaraman; Thanikachalam, Venugopal; Venkatesh Perumal, Marimuthu

2012-09-01

The synthesized imidazole derivative 2-(2,4-difluorophenyl)-1-(4-methoxyphenyl)-1H-imidazo[4,5-f][1,10] phenanthroline (dfpmpip) has been characterized using IR, mass, (1)H, (13)C NMR and elemental analysis. The photophysical properties of dfpmpip have been studied using UV-visible and fluorescence spectroscopy in different solvents. The solvent effect on the absorption and fluorescence bands has been analyzed by a multi-component linear regression. Theoretically calculated bond lengths, bond angles and dihedral angles are found to be slightly higher than that of X-ray Diffraction (XRD) values of its parent compound. The charge distribution has been calculated from the atomic charges by non-linear optical (NLO) and natural bond orbital (NBO) analysis. Since the synthesized imidazole derivative has the largest μ(g)β(0) value, the reported imidazole can be used as potential NLO material. The energies of the highest occupied molecular orbital (HOMO) and lowest unoccupied molecular orbital (LUMO) levels and the molecular electrostatic potential (MEP) energy surface studies evidenced the existence of intramolecular charge transfer (ICT) within the molecule. Theoretical calculations regarding the chemical potential (μ), hardness (η) and electrophilicity index (ω) have also been calculated. Copyright © 2012 Elsevier B.V. All rights reserved.

Microstructural characterization of ultrasonic impact treated aluminum-magnesium alloy

NASA Astrophysics Data System (ADS)

Tran, Kim Ngoc Thi

Aluminum 5456-H116 has high as-welded strength, is formable, and highly corrosion resistant, however, it can become sensitized when exposed to elevated temperatures for a prolonged time. Sensitization results in the formation of a continuous β phase at the grain boundaries that is anodic to the matrix. Thus the grain boundaries become susceptible to stress corrosion cracking (SCC) and intergranular corrosion cracking (IGC). Cracking issues on aluminum superstructures have prompted the use of a severe plastic deformation processes, such as ultrasonic impact treatment (UIT), to improve SCC resistance. This study correlated the effects of UIT on the properties of 5456-H116 alloy to the microstructural evolution of the alloy and helped develop a fundamental understanding of the mechanisms that cause the microstructural evolution. Ultrasonic impact treatment produces a deformed layer at the surface ˜ 10 to 18 µm thick that is characterized by micro-cracks, tears, and voids. Ultrasonic impact treatment results in grain refinement within the deformation layer and extending below the deformed layer. The microstructure exhibits weak crystallographic texture with larger fraction of high angle grain boundaries. Nanocrystalline grains within the deformation layer vary in size from 2 to 200 nm in diameter and exhibit curved or wavy grain boundaries. The nanocrystalline grains are thermally stable up to 300°C. Above 300°C, grain growth occurs with an activation energy of ˜ 32 kJ/mol. Below the deformation layer, the microstructure is characterized by submicron grains, complex structure of dislocations, sub-boundaries, and Moiré fringes depicting overlapping grains. The deformation layer does not exhibit the presence of a continuous β phase, however below the deformation layer; a continuous β phase along the grain boundaries is present. In general the highest hardness and yield strength is at the UIT surface which is attributed to the formation of nanocrystalline grains. Although the highest hardness and yield strength was observed at the UIT surface, the results were mixed with some lower values. The lower hardness and yield strength values at the UIT surface are attributed to the voids and micro cracking/micro voids observed in the deformation layer. The fracture mode was transgranular ductile fracture with micro void coalescence and dimples. Both UIT and untreated material exhibit similar levels of intergranular corrosion susceptibility. Corrosive attack was intergranular with slightly deeper attack in the untreated material. Numerical simulation modeling showed that the calculated residual stress under the tool, ˜80 MPa, is of the same order of magnitude as the compressive residual stresses measured by XRD measurements near the surface. Modeling also showed that high effective strains were induced almost immediately. The UIT process also resulted in rapid localized heating to a maximum temperature of ˜32°C during the first eleven pin tool cycles. The model also showed that during UIT processing, the material undulates as the pin tool impacts and retracts from the surface of the material. The undulations represent the elastic response of the surface to the compressive stresses built up during a pin tool cycle.

Virial Coefficients for the Liquid Argon

NASA Astrophysics Data System (ADS)

Korth, Micheal; Kim, Saesun

2014-03-01

We begin with a geometric model of hard colliding spheres and calculate probability densities in an iterative sequence of calculations that lead to the pair correlation function. The model is based on a kinetic theory approach developed by Shinomoto, to which we added an interatomic potential for argon based on the model from Aziz. From values of the pair correlation function at various values of density, we were able to find viral coefficients of liquid argon. The low order coefficients are in good agreement with theoretical hard sphere coefficients, but appropriate data for argon to which these results might be compared is difficult to find.

The use of the durometer to measure rock hardness in geomorphology. Advantages and limitations.

NASA Astrophysics Data System (ADS)

Feal-Pérez, Alejandra; Blanco-Chao, Ramón; Valcarcel-Díaz, Marcos; Combes, Martín. A.

2010-05-01

The durometer is a hardness tester developed to measure hardness of metallic materials that has been recently introduced to measure rock hardness in weathering studies. Aoki & Matsukura (2007) highlight some advantages of the durometer compared with the Schmidt Rock Test Hammer: the smaller plunge allows measurements in small surfaces such as taffoni or rock carvings, the wider measurement range and the lower impact energy. This last makes it a non destructive method that can be used on relatively soft rocks. In this work the durometer Equotip (©) has been tested in different environments in the field and in the laboratory to explore its applicability and limitations. We applied the device on small rock samples of granite and limestone and a T-test showed that smaller sample size gave smaller hardness values (p < 0.01). Testing the effects of water content, there were no statistically significant differences between water saturated and dry samples. The influence of rock surface roughness was evaluated applying the durometer in ancient rock carvings in medium to coarse grain granites. We compared the values obtained inside and outside the grooves of the carvings using two different support rings, one flat and one concave. The flat ring was not able to reach the bottom of the groove, meanwhile the concave ring adjusts fairly well given its semi spherical section. A t-test confirmed the difference (p < 0.01) between lower rebound values obtained in the grooves using the flat ring and the higher and less scattered values obtained when the concave ring is used. As a very sensitive device, there are some problems in the use related with rock roughness and rock grain size. In weathered medium to coarse grained rocks, with very irregular surfaces, is not easy to get a good contact between the plunge and the rock surface. A poor contact caused by surface roughness causes the scattering and lowering of rebound values. On the contrary, in homogeneous fine grained rocks and in uniform rock surfaces the device gave very good results. The data obtained in glacial, nival and rock coastal environments showed the potential of the device in the identification of changes in rock hardness. We were able to asses the changes in the weathering degree of glacial striations and marked differences in the rock surfaces subjected or not to abrasion. A. Feal-Pérez is supported by the grant AP2006-03854 (Spanish Ministry of Education)

Superhard nanocomposite of dense polymorphs of boron nitride: Noncarbon material has reached diamond hardness

NASA Astrophysics Data System (ADS)

Dubrovinskaia, Natalia; Solozhenko, Vladimir L.; Miyajima, Nobuyoshi; Dmitriev, Vladimir; Kurakevych, Oleksandr O.; Dubrovinsky, Leonid

2007-03-01

The authors report a synthesis of unique superhard aggregated boron nitride nanocomposites (ABNNCs) showing the enhancement of hardness up to 100% in comparison with single crystal c-BN. Such a great hardness increase is due to the combination of the Hall-Petch and the quantum confinement effects. The decrease of the grain size down to 14nm and the simultaneous formation of the two dense BN phases with hexagonal and cubic structures within the grains at nano- and subnanolevel result in enormous mechanical property enhancement with maximum hardness of 85(5)GPa. Thus, ABNNC is the first non-carbon-based bulk material with the value of hard-ness approaching that of single crystal and polycrystalline diamond and aggregated diamond nanorods. ABNNC also has an unusually high fracture toughness for superhard materials (K1C=15MPam0.5) and wear resistance (WH=11; compare, for industrial polycrystalline diamond, WH=3-4), in combination with high thermal stability (above 1600K in air), making it an exceptional superabrasive.

Application of face centred central composite design to optimise compression force and tablet diameter for the formulation of mechanically strong and fast disintegrating orodispersible tablets.

PubMed

Pabari, Ritesh M; Ramtoola, Zebunnissa

2012-07-01

A two factor, three level (3(2)) face centred, central composite design (CCD) was applied to investigate the main and interaction effects of tablet diameter and compression force (CF) on hardness, disintegration time (DT) and porosity of mannitol based orodispersible tablets (ODTs). Tablet diameters of 10, 13 and 15 mm, and CF of 10, 15 and 20 kN were studied. Results of multiple linear regression analysis show that both the tablet diameter and CF influence tablet characteristics. A negative value of regression coefficient for tablet diameter showed an inverse relationship with hardness and DT. A positive value of regression coefficient for CF indicated an increase in hardness and DT with increasing CF as a result of the decrease in tablet porosity. Interestingly, at the larger tablet diameter of 15 mm, while hardness increased and porosity decreased with an increase in CF, the DT was resistant to change. The optimised combination was a tablet of 15 mm diameter compressed at 15 kN showing a rapid DT of 37.7s and high hardness of 71.4N. Using these parameters, ODTs containing ibuprofen showed no significant change in DT (ANOVA; p>0.05) irrespective of the hydrophobicity of the ibuprofen. Copyright © 2012 Elsevier B.V. All rights reserved.

Dose dependence of nano-hardness of 6H-SiC crystal under irradiation with inert gas ions

NASA Astrophysics Data System (ADS)

Yang, Yitao; Zhang, Chonghong; Su, Changhao; Ding, Zhaonan; Song, Yin

2018-05-01

Single crystal 6H-SiC was irradiated by inert gas ions (He, Ne, Kr and Xe ions) to various damage levels at room temperature. Nano-indentation test was performed to investigate the hardness change behavior with damage. The depth profile of nano-hardness for 6H-SiC decreased with increasing depth for both the pristine and irradiated samples, which was known as indentation size effect (ISE). Nix-Gao model was proposed to determine an asymptotic value of nano-hardness by taking account of ISE for both the pristine and irradiated samples. In this study, nano-hardness of the irradiated samples showed a strong dependence on damage level and showed a weak dependence on ions species. From the dependence of hardness on damage, it was found that the change of hardness demonstrated three distinguishable stages with damage: (I) The hardness increased with damage from 0 to 0.2 dpa and achieved a maximum of hardening fraction ∼20% at 0.2 dpa. The increase of hardness in this damage range was contributed to defects produced by ion irradiation, which can be described well by Taylor relation. (II) The hardness reduced rapidly with large decrement in the damage range from 0.2 to 0.5 dpa, which was considered to be from the covalent bond breaking. (III) The hardness reduced with small decrement in the damage range from 0.5 to 2.2 dpa, which was induced by extension of the amorphous layer around damage peak.

Synthesis and properties of nanocrystalline Bi-Te based thermoelectric materials for energy application

NASA Astrophysics Data System (ADS)

Almohaimeed, Sulaiman

Thermoelectric phenomenon is the science associated with converting thermal energy into electricity based on the Seebeck effect. Bismuth telluride Bi 2Te3 is currently considered to be the state-of-the art thermoelectric material with high efficiency for low temperature applications and is therefore attractive for energy harvesting processes. Nanostructures thermoelectric materials provide a novel way to enhance thermoelectric properties and are considered to be the efficient building blocks for thermoelectric devices. In this work, n- and p-type bulk nanocrystalline Bismuth telluride thermoelectric materials were prepared by mechanical alloying / ball milling technique. The produced nano-crystalline powder were then consolidated using hot compaction under inert atmosphere. The novel processing of these materials maintained the nanostructure in both n- and p-type. Structural properties of the n- and p-types were characterized using X ray diffraction, scanning electron microscopy and transmission electron microscope. These techniques proved that the average grian size of the milled thermoelectric materials was about 20 nm. Accordingly, a Significant improvement in the figure of merit (ZT) is achieved through significant lattice thermal conductivity reduction and Seebeck coefficient improvement. The maximum ZT value for the n-type nanocrystalline thermoelectric was 1.67 at 373 K while the maximum ZT value for the p-type was 1.78 at the same temperature. These values are considered to be the highest values reported for similar materials. Evaluation of the mechanical properties was also performed through microhardness measurement using Vickers micro-hardness test, which shows an enhancement in mechanical properties for the produced materials.

Investigation of Hydraulic Binding Characteristics of Lime Based Mortars Used in Historical Masonry Structures

NASA Astrophysics Data System (ADS)

Binal, Adil

2017-10-01

In the historic masonry structures, hard and large rock fragments were used as the construction materials. The hydraulic binder material prepared to keep this used material in its entirety is a different material than the cement used today. Khorasan mortar made by using aggregate and lime exhibits a more flexible structure than the concrete. This feature allows the historic building to be more durable. There is also a significant industrial value because of the use of Khorasan mortar in the restoration of historic masonry structures. Therefore, the calculation of the ideal mixture of Khorasan mortar and the determination of its mechanical and physical properties are of great importance regarding preserving historic buildings. In this study, the mixtures of different lime and brick fractions were prepared. It was determined that Khorasan mortar shows the highest compressive strength in mixtures with water/lime ratio of 0.55 and lime/aggregate ratio of 0.66. By keeping the mixing ratio constant, it was observed that the strengths of the samples kept in the humidity chamber for different curing times increased day by day. The early strength values of samples with the high lime/aggregate ratio (l/a: 0.83) were higher than those with the low lime/aggregate ratio (l/a: 0.5). For the samples with low lime/aggregate ratio, there was an increase in the strength values depending on the curing period. As the cure duration increases, a chemical reaction takes place between the lime and the brick fracture, and as a result of this reaction, the strength values are increased.

Efficacy of Mucograft vs Conventional Resorbable Collagen Membranes in Guided Bone Regeneration Around Standardized Calvarial Defects in Rats: A Histologic and Biomechanical Assessment.

PubMed

Ramalingam, Sundar; Basudan, Amani; Babay, Nadir; Al-Rasheed, Abdulaziz; Nooh, Nasser; Nagshbandi, Jafar; Aldahmash, Abdullah; Atteya, Muhammad; Al-Hezaimi, Khalid

2016-01-01

Guided bone regeneration (GBR) using a porcine-derived collagen matrix (Mucograft [MG], Geistlich) has not yet been reported. The aim of this histologic and biomechanical study was to compare the efficacy of MG versus resorbable collagen membranes (RCMs) in facilitating GBR around standardized rat calvarial defects. Forty female Wistar albino rats with a mean age and weight of 6 to 9 weeks and 250 to 300 g, respectively, were used. With the rats under general anesthesia, the skin over the calvaria was exposed using a full-thickness flap. A 4.6-mm-diameter standardized calvarial defect was created in the left parietal bone. For treatment, the rats were randomly divided into four groups (n = 10 per group): (1) MG group: the defect was covered with MG; (2) RCM group: the defect was covered with an RCM; (3) MG + bone group: the defect was filled with bone graft particles and covered by MG; and (4) RCM + bone group: the defect was filled with bone graft particles and covered by an RCM. Primary closure was achieved using interrupted resorbable sutures. The animals were sacrificed at 8 weeks after the surgical procedures. Qualitative histologic analysis and biomechanical assessment to identify hardness and elastic modulus of newly formed bone (NFB) were performed. Collected data were statistically analyzed using one-way analysis of variance. Histologic findings revealed NFB with fibrous connective tissue in all groups. The quantity of NFB was highest in the RCM + bone group. Statistically significant differences in the hardness (F = 567.69, dfN = 3, dfD = 36, P < .001) and elastic modulus (F = 294.19, dfN = 3, dfD = 36, P < .001) of NFB were found between the groups. Although the RCM + bone group had the highest mean ± standard deviation (SD) hardness of NFB (531.4 ± 24.9 MPa), the RCM group had the highest mean ± SD elastic modulus of NFB (18.63 ± 1.89 GPa). The present study demonstrated that RCMs are better than MG at enhancing new bone formation in standardized rat calvarial defects when used along with mineralized particulate graft material.

An Experimental Investigation on Hardness and Microstructure of Heat Treated EN 9 Steel

NASA Astrophysics Data System (ADS)

Biswas, Palash; Kundu, Arnab; Mondal, Dhiraj

2017-08-01

In the modern engineering world, extensive research has led to the development of some special grades of steel, often suited for enhanced functions. EN 9 steel is one such grade, having major applications in power plants, automobile and aerospace industry. Different heat treatment processes are employed to achieve high hardness and high wear resistance, but machinability subsequently decreases. Existing literature is not sufficient to achieve a balance between hardness and machinability. The aim of this experimental work is to determine the hardness values and observe microstructural changes in EN9 steel, when it is subjected to annealing, normalizing and quenching. Finally, the effects of tempering after each of these heat treatments on hardness and microstructure have also been shown. It is seen that the tempering after normalizing the specimen achieved satisfactory results. The microstructure was also observed to be consisting of fine grains.

Effect of white tea and xylitol on structure and properties of demineralized enamel and jawbone

NASA Astrophysics Data System (ADS)

Auerkari, EI; Kiranahayu, R.; Emerita, D.; Sumariningsih, P.; Sarita, D.; Adiwirya, MS; Suhartono, AW

2018-05-01

White tea and xylitol have been suggested as potential agents to combat dental caries and osteoporosis through enhanced remineralization. This investigation aimed to determine the effects of exposure to white tea with and without xylitol on the structure, composition and hardness of demineralized human dental enamel. For control, samples of untreated and demineralized enamel and samples of untreated rat jawbone were subjected to similar measurements. For demineralization, the enamel samples were immersed for two days at 50°C in an acetate solution (pH 4.0). All samples were then soaked for two weeks at 37°C in a solution containing three different concentrations of white tea, xylitol or both, and an optional addition of the remineralization ingredients including Ca, P and F. For enamel samples without preceding demineralization and without added remineralization ingredients, the results showed highest mean hardness after immersion in a solution containing both white tea and xylitol, practically independently of their applied concentration level. However, for demineralized enamel samples with added remineralization ingredients, the resulting mean hardness was also dependent on concentration of white tea and xylitol. With sufficient concentration, hardness was again higher for combined white tea and xylitol than for either of these used alone.

Tribological Characteristics of Submicron SiC(p)-GR(p)/Zn-35Al-1Mg Composites in Semisolidification Casting process

NASA Astrophysics Data System (ADS)

Liu, S.; Fang, Z. W.; Li, L. X.

2018-05-01

Uniform SiC(p)-GR(p)/Zn-35Al-1Mg composites were prepared by powder pressing and semisolidification stirring-casting process by adding submicron silicon carbide and graphite reinforcement particles in an aluminum-zinc alloy matrix. Micro Vickers hardness and microstructures of the novel composites were studied, and their wear properties and wear temperature were measured for different load and friction conditions. The results show that silicon carbide and graphite particles homogeneously mix in the matrix, while contained silicon carbide particles improve the matrix hardness to 8.4%, graphite improves the matrix hardness to 16.8%, but two of them, combined, reduce the matrix hardness to 7.6%; the rate of temperature rise of the zinc-aluminum matrix alloy is the highest than the other three composites and is up to 48.5° C/s at 1.69MPa. At 0.56MPa and sliding 26.4km, the graphite composite anti-wear effect is optimal, while at 1.13MPa, the wear resistance of silicon carbide and graphite compound particles is the best; in the other case of only silicon carbide particles, the wear resistance is increased to 35% at 1.69MPa and 26.4km, and its anti-wear effects are excellent.

Characterizing the Effect of Laser Power on Laser Metal Deposited Titanium Alloy and Boron Carbide

NASA Astrophysics Data System (ADS)

Akinlabi, E. T.; Erinosho, M. F.

2017-11-01

Titanium alloy has gained acceptance in the aerospace, marine, chemical, and other related industries due to its excellent combination of mechanical and corrosion properties. In order to augment its properties, a hard ceramic, boron carbide has been laser cladded with it at varying laser powers between 0.8 and 2.4 kW. This paper presents the effect of laser power on the laser deposited Ti6Al4V-B4C composites through the evolving microstructures and microhardness. The microstructures of the composites exhibit the formation of α-Ti phase and β-Ti phase and were elongated towards the heat affected zone. These phases were terminated at the fusion zone and globular microstructures were found growing epitaxially just immediately after the fusion zone. Good bondings were formed in all the deposited composites. Sample A1 deposited at a laser power of 0.8 kW and scanning speed of 1 m/min exhibits the highest hardness of HV 432 ± 27, while sample A4 deposited at a laser power of 2.0 kW and scanning speed of 1 m/min displays the lowest hardness of HV 360 ± 18. From the hardness results obtained, ceramic B4C has improved the mechanical properties of the primary alloy.

Effect of postsecondary education on the economic status of persons who are deaf or hard of hearing.

PubMed

Schley, Sara; Walter, Gerard G; Weathers, Robert R; Hemmeter, Jeffrey; Hennessey, John C; Burkhauser, Richard V

2011-01-01

This article examines the effect that postsecondary education has on earnings and the duration of time spent in the Social Security disability programs for young persons who are deaf or hard of hearing. Our hypothesis is that investments in postsecondary training increase the likelihood of employment for persons who are deaf or hard of hearing and thus reduce dependency on disability-related income support programs. A longitudinal data set based upon records from the National Technical Institute for the Deaf and Social Security administrative records is used for this analysis. We find that those who graduate, even those who graduate with vocational degrees, experience significant earnings benefits and reductions in the duration of time spent on federal disability programs when compared with those who do not graduate with a degree. This finding suggests that reductions in the duration of time spent on Social Security programs are not limited to those with the highest level of scholastic aptitude and that investments in post-secondary education can benefit a broad group of deaf and hard-of-hearing persons. In addition, the data show that individuals who attend college, but withdraw before graduation, fair no better economically than individuals who never attended college.

Microstructure and Dry Sliding Wear Resistance of Laser Cladding Ti-Al-Si Composite Coating

NASA Astrophysics Data System (ADS)

Zhang, H. X.; Yu, H. J.; Chen, C. Z.; Dai, J. J.

In order to improve the wear resistance of Ti alloys, different mass ratios of Ti-Si-Al powders were designed to fabricate hard phases reinforced intermetallic matrix composite coatings on the Ti-6Al-4V substrate by laser cladding. The corresponding coatings were characterized by X-ray diffraction (XRD), scanning electron microscope (SEM), energy dispersive spectrometer (EDS) and high resolution transmission microscopy (HRTEM). The HV-1000 hardness tester and MM200 wear test machine were employed to test the hardness and the wear resistance of the composite coatings, respectively. The composite coatings mainly consisted of the reinforcements of Ti5Si3, Ti3AlC2 and Ti7Al5Si12 and the matrix of Ti3Al, TiAl, TiAl3 and α-Ti. The micro-hardness of the Ti-35Al-15Si coating was from 956 HV0.2 to 1130 HV0.2, which was approximately 3-4 times of the substrate and the highest in the three samples. The wear rate of the Ti-35Al-15Si coating was 0.023cm3ṡmin-1, which was about 1/4 of the Ti-6Al-4V substrate. It was the lowest in the three samples.

An in vitro investigation of wear resistance and hardness of composite resins

PubMed Central

Cao, Liqun; Zhao, Xinyi; Gong, Xu; Zhao, Shouliang

2013-01-01

Purpose: The aim of the present study was to investigate the wear resistance and hardness of five kinds of composite resins. Materials and Methods: Sixty-five specimens were fabricated with one nano-hybrid (Charisma Diamond), two micro-hybrid (3MZ250, Clearfil AP-X) and two packable (3MP60, Surefil) composite resins, according to a randomized complete block design (n=13, 8 for wear test; 5 for hardness test). The composites were filled in a rectangular mold, and light polymerization. After storage in 37°C deionized water for 24h, all specimens were tested with a custom-made toothbrush machine with a stainless-steel ball as antagonist (3N loads, 1Hz, 6×105 cycles) immersed in calcium fluoride slurry. Wear volume, hardness and surface structure of each tested material was examined by a three-dimensional non-contact optical profilometer, Vickers indentation technique and scanning electron microscope. Results: The volume loss ranked from least to most as follows: Charisma Diamond, P60, Z250, Clearfil AP-X and Surefil. Regarding hardness, the rank from highest to lowest as follows: Clearfil AP-X, P60, Surefil, Z250, Charisma Diamond. The interactions between wear resistance and microhardness were not significant. Conclusions: The custom-made machine is considered suitable to simulate sliding of an antagonist cusp on an opposing occlusal composite restoration. Nanofilled composite may have superior wear compared to other composite resins. PMID:23844265

Assessment of adhesion formation after laparoscopic intraperitoneal implantation of Dynamesh IPOM mesh

PubMed Central

Jałyński, Marek; Piskorz, Łukasz; Brocki, Marian

2013-01-01

Introduction Formation of adhesions after laparoscopic hernia repair using the intra-peritoneal onlay mesh (IPOM) procedure can lead to intestinal obstruction or mesh erosion into intestinal lumen. The aims of this study included: measurement of adhesion formation with Dynamesh IPOM after laparoscopic intraperitoneal implantation, and assessment of the occurrence of isolated adhesions at the fastening sites of slowly absorbable sutures. Material and methods Twelve healthy pigs underwent laparoscopic implantation of 2 Dynamesh IPOM mesh fragments each, one was fastened with PDSII, and the other with Maxon sutures. An assessment of adhesion formation was carried out after 6 weeks and included an evaluation of surface area, hardness according to the Zhulke scale, and index values. The occurrence of isolated adhesions at slowly absorbable suture fixation points was also analyzed. Results Adhesions were noted in 83.3% of Dynamesh IPOM meshes. Adhesions covered on average 37.7% of the mesh surface with mean hardness 1.46 and index value 78.8. In groups fixed with PDS in comparison to Maxon sutures adhesions covered mean 31.6% vs. 42.5% (p = 0.62) of the mesh surface, mean hardness was 1.67 vs.1.25 (p = 0.34) and index 85.42 vs. 72.02 (p = 0.95). Conclusions The Dynamesh IPOM mesh, in spite of its anti-adhesive layer of PVDF, does not prevent the formation of adhesions. Adhesion hardness, surface area, and index values of the Dynamesh IPOM mesh are close to the mean values of these parameters for other commercially available 2-layer meshes. Slowly absorbable sutures used for fastening did not increase the risk of adhesion formation. PMID:23847671

The physical properties of generic latanoprost ophthalmic solutions are not identical.

PubMed

Kolko, Miriam; Koch Jensen, Peter

2017-06-01

To compare various characteristics of Xalatan ® and five generic latanoprost ophthalmic solutions. Drop size, volume, pH values, buffer capacity, viscosity, hardness of bottles and costs were determined. Drop sizes were measured in triplicates by micropipettes, and the number of drops counted in three separate bottles of each generic product was determined. pH values were measured in triplicates by a calibrated pH meter. Buffer capacity was exploited by titrating known quantities of strong base into 2.5 ml of each brand and interpolated to neutral pH. Kinematic viscosity was determined by linear regression of timed gravity flow from a vertical syringe through a 21-G cannula. The hardness of the bottles was evaluated by gradually increasing tension on a hook placed around each bottle until a drop was expelled reading the tension on an attached spring scale. Drop sizes and the number of drops in the bottles varied significantly between the generic drugs. The control value of pH in the brand version (Xalatan ® ) was markedly lower compared to the generic latanoprost products. Titration of Xalatan ® to neutrality required substantially more NaOH compared to the generic latanoprost products. Finally, the viscosity revealed a significant variability between brands. Remarkable differences were found in bottle shapes, bottle hardness and costs of the latanoprost generics. Generic latanoprost eye drops should not be considered identical to the original brand version as regards to drop size, volumes, pH values, buffer capacity, viscosity, hardness of bottles and costs. It is likely that these issues affect compliance and intraocular pressure (IOP)-lowering effect. Therefore, re-evaluation of the requirements for introducing generic eye drops seems reasonable. © 2017 Acta Ophthalmologica Scandinavica Foundation. Published by John Wiley & Sons Ltd.

Raising Cash under Duress and the Role of Cash Value Life Insurance: An Educational Example

ERIC Educational Resources Information Center

Russell, David T.; Chong, James T.; Phillips, G. Michael

2018-01-01

Consumers face hard choices when they need cash quickly. Hard choices can lead to emotional or economically unsound decisions. Traditional classroom discussions of raising funds to pay for expenses usually focus on generating income, borrowing, or the sale of real and financial assets, if hardship is discussed at all. However, many families have…

A study to evaluate cephalometric hard tissue profile of Tamil population for orthognathic surgery.

PubMed

Nachiappan, S; Tharanikumar, S; Chandran, Ajay; Anusudha, P; Nandini, G D; Balasubramaniam, Murali

2015-08-01

The primary aim of this study is to compare, the cephalometric hard tissue profile values and analysis between Tamil and Caucasian population. The study also aims to create a better understanding in the facial proportions of Tamil Nadu population and to have better diagnosis and treatment planning for orthognathic surgery for Tamil population in Tamil Nadu.

Influence of 10 % Cold Rolling Reduction on Ageing Behaviour of Hot Rolled Al-Cu-Si-Mn-Mg Alloy

NASA Astrophysics Data System (ADS)

Ghosh, S. K.

2014-10-01

In the current study, the effect of 10 % cold rolling on the different ageing phenomena of Al-Cu-Si-Mn-Mg alloy was investigated. Both hot rolled and cold rolled alloys were subjected to both natural and artificial ageing processes. Hardness was measured to understand the change in the mechanical property of the alloy before and after rolling and also during ageing processes. From microscopy, it was evident that the cold rolling and subsequent ageing provided the alloy with a structure in which CuAl2 precipitates were uniformly distributed. The alloy exhibited the peak hardness value of 92 VHN after 2 days of natural ageing, whereas the cold deformed (10 %) alloy exhibited the higher peak hardness value of 139 VHN after 3 days of natural ageing. Peak hardness of the alloy reached 94 VHN, when hot rolled alloy was subjected to ageing at 250 °C for 1 h, whereas 10 % cold rolling followed by ageing (100 °C, 15 min) demonstrated accelerated and elevated hardening. The ageing behaviours thus obtained permit the alloy to provide a range of desirable combinations of strength and ductility for high strength weight saving applications.

The facts that the physical-chemical properties of modern tablets distinguish them from natural food lumps

NASA Astrophysics Data System (ADS)

Urakov, A.; Urakova, N.; Reshetnikov, A.; Kopylov, M.; Kasatkin, A.; Baymurzin, D.; Gabdrafikov, R.

2017-02-01

It was found that pharmaceutical companies produce drugs in tablet form, physical or physical-chemical properties that are radically different from those of the properties of natural food lumps, in that adult converts food in our mouth before swallowing. It was shown that the conventional shape, color, size, volume, specific gravity, hardness, osmotic and acid activity of modern tablets impair the physical and physicochemical properties of the liquid contents of the stomach is much stronger than such “building” materials, such as chalk, clay, sand, river pebbles and gravel. The results showed, that the value of the specific hardness, deforming tablets, can distinguish modern tablets from each other by more than 5000 times. Therefore, introduction tablets inside without information of ability injuring their action leads to the fact that soft and “unsalted” tablets almost nothing damage, and too “salty” and solid tablets damage the gums, lips, tongue, teeth and dental structures. To reduce the traumatic action tablets offered standardize osmoticity, corrosion and hardness within the range of safe values for soft and hard tissues of the oral cavity and improve standard introduction of tablets in the mouth.

Synthesis, spectral and theoretical studies of Ni(II), Pd(II) and Pt(II) complexes of 5-mercapto-1,2,4-triazole-3-imine-2‧-hydroxynaphyhaline

NASA Astrophysics Data System (ADS)

Gaber, Mohamed; El-Ghamry, Hoda; Atlam, Faten; Fathalla, Shaimaa

2015-02-01

Ni(II), Pd(II) and Pt(II) complexes of 5-mercapto-1,2,4-triazole-3-imine-2‧-hydroxynaphthaline have been isolated and characterized by elemental analysis, IR, 1H NMR, EI-mass, UV-vis, molar conductance, magnetic moment measurements and thermogravimetric analysis. The molar conductance values indicated that the complexes are non-electrolytes. The magnetic moment values of the complexes displayed diamagnetic behavior for Pd(II) and Pt(II) complexes and tetrahedral geometrical structure for Ni(II) complex. From the bioinorganic applications point of view, the interaction of the ligand and its metal complexes with CT-DNA was investigated using absorption and viscosity titration techniques. The Schiff-base ligand and its metal complexes have also been screened for their antimicrobial and antitumor activities. Also, theoretical investigation of molecular and electronic structures of the studied ligand and its metal complexes has been carried out. Molecular orbital calculations were performed using DFT (density functional theory) at B3LYP level with standard 6-31G(d,p) and LANL2DZ basis sets to access reliable results to the experimental values. The calculations were performed to obtain the optimized molecular geometry, charge density distribution, extent of distortion from regular geometry, the highest occupied molecular orbital (HOMO), the lowest unoccupied molecular orbital (LUMO), Mulliken atomic charges, reactivity index (ΔE), dipole moment (D), global hardness (η), softness (σ), electrophilicity index (ω), chemical potential and Mulliken electronegativity (χ).

Mechanical property studies of human gallstones.

PubMed

Stranne, S K; Cocks, F H; Gettliffe, R

1990-08-01

The recent development of gallstone fragmentation methods has increased the significance of the study of the mechanical properties of human gallstones. In the present work, fracture strength data and microhardness values of gallstones of various chemical compositions are presented as tested in both dry and simulated bile environments. Generally, both gallstone hardness and fracture strength values were significantly less than kidney stone values found in previous studies. However, a single calcium carbonate stone was found to have an outer shell hardness exceeding those values found for kidney stones. Diametral compression measurements in simulated bile conclusively demonstrated low gallstone fracture strength as well as brittle fracture in the stones tested. Based on the results of this study, one may conclude that the wide range of gallstone microhardnesses found may explain the reported difficulties previous investigators have experienced using various fragmentation techniques on specific gallstones. Moreover, gallstone mechanical properties may be relatively sensitive to bile-environment composition.

Claudio Pellegrini and the World’s First Hard X-ray Free-Electron Laser

DOE Office of Scientific and Technical Information (OSTI.GOV)

Pellegrini, Claudio

2015-10-20

President Obama welcomed SLAC's Claudio Pellegrini inside the Oval Office on Tuesday morning as a recipient of the Enrico Fermi Award, one of the highest honors the U.S. government can give to a scientist. Pellegrini, a visiting scientist and consulting professor at SLAC and distinguished professor emeritus at the University of California, Los Angeles, received the award for research that aided in the development of X-ray free-electron lasers (XFELs) including SLAC's Linac Coherent Light Source (LCLS), a DOE Office of Science User Facility that started up in 2009. Here, Pellegrini describes his efforts that contributed to the realization of SLAC’smore » Linac Coherent Light Source, the world’s first hard X-ray free-electron laser.« less

Claudio Pellegrini and the World’s First Hard X-ray Free-Electron Laser

ScienceCinema

Pellegrini, Claudio

2018-01-16

President Obama welcomed SLAC's Claudio Pellegrini inside the Oval Office on Tuesday morning as a recipient of the Enrico Fermi Award, one of the highest honors the U.S. government can give to a scientist. Pellegrini, a visiting scientist and consulting professor at SLAC and distinguished professor emeritus at the University of California, Los Angeles, received the award for research that aided in the development of X-ray free-electron lasers (XFELs) including SLAC's Linac Coherent Light Source (LCLS), a DOE Office of Science User Facility that started up in 2009. Here, Pellegrini describes his efforts that contributed to the realization of SLAC’s Linac Coherent Light Source, the world’s first hard X-ray free-electron laser.

Wear characterization of nano-hydroxyapatite with addition of titanium (HA-Ti)

NASA Astrophysics Data System (ADS)

Rosmamuhamadani, R.; Arawi, A. Z. O.; Talari, M. K.; Mahat, M. M.; Bonnia, N. N.; Sabrina; Yahaya, M.; Sulaiman, S.; Ismail, M. I. S.

2018-04-01

Hydroxyapatite (Ca10 (PO4)6(OH)2, HA), is an attractive material of an inorganic compound whose chemical composition and crystallographic structures are similar to the composition of the bone. A natural source such as egg shells is composed of 94 wt. % of calcium carbonate (CaCO3), which can be calcined as calcium oxide (CaO) by the calcinations process. The efficient temperature to produce CaO is 900 °C for 2 hours. The synthesis of nano-HA was done by the mixing the diammonium phosphate (DAP) and calcium hydroxide (Ca(OH)2) and subjected into a microwave for 30 minutes at 1100 W irradiation power. Ball milling process was used for 30 minutes to mix the nano-HA with different compositions of titanium. These were pressed to form pallets by hand hydraulic pump (force=2300 psi). The pallets then were sintered at 1200 °C with the heating rate of 3 °C/min for 2 hours. The pallets were tested by several mechanical testing including hardness, compression strength and wear. From the results, HA-25wt. %Ti composite gave the highest hardness, compression and coefficient of friction for wear test values which were 89.6 Hv, 82.5MPa and 0.76μ respectively. It showed that by adding Ti to nano-HA, the mechanical properties of nano-HA could be enhanced. The microstructure analyses by optical micrograph showed that nano-HA-Ti particles displayed shape likes needle morphology. The particles showed the high tendency to form the agglomerations.

A Burst and Simultaneous Short-term Pulsed Flux Enhancement fom the Magnetar Candidate 1E 1048.1-5937

NASA Technical Reports Server (NTRS)

Gavriil, Fotis P.; Kaspi, Victoria M.; Woods, Peter M.; Lyutikov, Maxim

2005-01-01

We report on the latest X-ray burst detected from the direction of the Anomalous X-ray Pulsar (AXP) 1E 1048.1-5937 using the Rossi X-ray Timing Explorer (RXTE). Following the burst the AXP was observed further with RXTE, XMM-Newton and Chandra. We find a simultaneous increase of approx. 3.7 times the quiescent value (approx. 5 sigma) in the pulsed component of the pulsar's flux during the tail of the burst which identifies the AXP as the burst's origin. The burst was overall very similar to the two others reported from this source in 2001. The unambiguous identification of 1E 1048.1-5937 as the burster here suggests it was in 2001 as well. Pre- and post-burst observations revealed no change in the total flux or spectrum of the quiescent emission. Comparing all three bursts detected thus far from this source we find that this event was the most fluent (170+/-42 x 10(exp -10) erg cm-2), had the highest peak flux (71+/-16 x 10(exp -10) erg/s/sq cm), the longest duration (approx. 411 s). The epoch of the burst peak was consistent with the arrival time of 1E 1048.1-5937's pulse peak. The burst exhibited significant spectral evolution with the trend going from hard to soft. Although the average spectrum of the burst was comparable in hardness (Gamma approx. 1) to those of the 2001 bursts, the peak of this burst was much harder (Gamma approx. 0.5).

Rapid disintegrating tablets of simvastatin dispersions in polyoxyethylene–polypropylene block copolymer for maximized disintegration and dissolution

PubMed Central

Balata, Gehan F; Zidan, Ahmad S; Abourehab, Mohamad AS; Essa, Ebtessam A

2016-01-01

The objective of this research was to improve the dissolution of simvastatin and to incorporate it in rapid disintegrating tablets (RDTs) with an optimized disintegration and dissolution characteristics. Polyoxyethylene–polypropylene block copolymer (poloxamer 188) was employed as a hydrophilic carrier to prepare simvastatin solid dispersions (SDs). Fourier transform infrared spectroscopy, differential scanning calorimetry (DSC) and X-ray diffractometry were employed to understand the interaction between the drug and the carrier in the solid state. The results obtained from Fourier transform infrared spectroscopy showed absence of any chemical interaction between the drug and poloxamer. The results of differential scanning calorimetry and X-ray diffractometry confirmed the conversion of simvastatin to distorted crystalline state. The SD of 1:2 w/w drug to carrier ratio showed the highest dissolution; hence, it was incorporated in RDT formulations using a 32 full factorial design and response surface methodology. The initial assessments of RDTs demonstrated an acceptable flow, hardness, and friability to indicate good mechanical strength. The interaction and Pareto charts indicated that percentage of croscarmellose sodium incorporated was the most important factor affecting the disintegration time and dissolution parameter followed by the hardness value and their interaction effect. Compression force showed a superior influence to increase RDT’s porosity and to fasten disintegration rather than swelling action by croscarmellose sodium. On the other hand, croscarmellose sodium was most important for the initial simvastatin release. The results suggest the potential use of poloxamer 188-based SD in RDT for the oral delivery of poor water-soluble antihyperlipidemic drug, simvastatin. PMID:27757012

Acute toxicity of three fire-retardant and two fire-suppressant foam formulations to the early life stages of rainbow trout (Oncorhynchus mykiss)

USGS Publications Warehouse

Gaikowski, Mark P.; Hamilton, Steven J.; Buhl, Kevin J.; McDonald, Susan F.; Summers, Cliff H.; Linder, G.; Krest, S.; Sparling, D.; Little, E.

1996-01-01

Laboratory studies were conducted with five early life stages of rainbow trout, Oncorhynchus mykiss, to determine the acute toxicities of five fire-fighting chemical formulations in standardized soft and hard water. Eyed egg, embryo–larvae, swim-up fry, and 60- and 90-d posthatch juveniles were exposed to three fire retardants (Fire-Trol LCG-R, Fire-Trol GTS-R, and Phos-Chek D75-F) and two fire-suppressant foams (Phos-Chek WD-881 and Silv-Ex). Swim-up fry were generally the most sensitive life stage, whereas the eyed-egg was the least sensitive. Toxicity of fire-fighting formulations was greater in hard water than in soft water for all life stages tested with Fire-Trol GTS-R and Silv-Ex and for 90-d-old juveniles tested with Fire-Trol LCG-R. The fire-suppressant foams were more toxic than the fire retardants. The 96-h median lethal concentrations (LC50s) were ranked from the most toxic to the least toxic formulation as follows (ranges are the lowest and highest 96-h LC50 calculated for each formulation): Phos-Chek WD-881 (11–44 mg/L), Silv-Ex (11–78 mg/L), Phos-Chek D75-F (218–>3,600 mg/L), Fire-Trol GTS-R (207–>6,000 mg/L), and Fire-Trol LCG-R (872–>10,000 mg/L). Toxicity values suggest that accidental entry of fire-fighting chemicals into aquatic environments could adversely affect fish populations.

Groundwater quality in the Chemung River Basin, New York, 2008

USGS Publications Warehouse

Risen, Amy J.; Reddy, James E.

2011-01-01

The second groundwater quality study of the Chemung River Basin in south-central New York was conducted as part of the U.S. Geological Survey 305(b) water-quality-monitoring program. Water samples were collected from five production wells and five private residential wells from October through December 2008. The samples were analyzed to characterize the chemical quality of the groundwater. Five of the wells are screened in sand and gravel aquifers, and five are finished in bedrock aquifers. Two of these wells were also sampled for the first Chemung River Basin study of 2003. Samples were analyzed for 6 physical properties and 217 constituents, including nutrients, major inorganic ions, trace elements, radionuclides, pesticides, volatile organic compounds, phenolic compounds, organic carbon, and four types of bacterial analyses. Results of the water-quality analyses for individual wells are presented in tables, and summary statistics for specific constituents are presented by aquifer type. The results are compared with Federal and New York State drinking-water standards, which typically are identical. Water quality in the study area is generally good, but concentrations of some constituents equaled or exceeded current or proposed Federal or New York State drinking-water standards; these were: sodium (one sample), total dissolved solids (one sample), aluminum (one sample), iron (one sample), manganese (four samples), radon-222 (eight samples), trichloroethene (one sample), and bacteria (four samples). The pH of all samples was typically neutral or slightly basic (median 7.5); the median water temperature was 11.0 degrees Celsius (?C). The ions with the highest median concentrations were bicarbonate (median 202 milligrams per liter [mg/L]) and calcium (median 59.0 mg/L). Groundwater in the study area is moderately hard to very hard, but more samples were hard or very hard (121 mg/L as calcium carbonate (CaCO3) or greater) than were moderately hard (61-120 mg/L as CaCO3); the median hardness was 205 mg/L as CaCO3. The maximum concentration of nitrate plus nitrite was 3.67 mg/L as nitrogen, which did not exceed established drinking-water standards for nitrate plus nitrite (10 mg/L as nitrogen). The trace elements with the highest median concentrations were strontium (median 196.5 micrograms per liter [(u or mu)g/L]), barium (median 186 (u or mu)g/L), and iron (median 72.5 (u or mu)g/L in unfiltered water). Five pesticides and pesticide degradates were detected among four samples at concentrations of 0.11 (u or mu)g/L or less; they included herbicides and herbicide degradates. Six volatile organic compounds (VOCs) were detected among four samples; these included four solvents, methyl tert-butyl ether, and one trihalomethane. Trichloroethene, a solvent, was detected in one production well at 5.5 (u or mu)g/L; the Federal and New York State Maximum Contaminant Level (MCL) (5 (u or mu)g/L) was exceeded. The highest radon-222 activities were in samples from bedrock wells [maximum 1,740 picocuries per liter (pCi/L)]; eight of the wells sampled exceeded a proposed U.S. Environmental Protection Agency (USEPA) drinking-water standard of 300 pCi/L. Any detection of coliform bacteria indicates a potential violation of New York State health regulations; total coliform bacteria were detected in four samples, and fecal coliform bacteria were detected in one sample.μμμ

[Development of a system for static measurement of skin-muscle hardness and a fundamental study on its applications].

PubMed

Honda, T

1990-10-01

There have been many attempts to quantitatively measure the hardness of skin-muscle, but no objective method for doing so has been established, because there is no universal standard for the hardness of organisms. The author considered elasticity and viscosity as the most important mechanical properties of the hardness of skin-muscle and applied the Maxwell model, in which a spring and a dash-pot are arranged in a series, to the static mechanical behavior of skin-muscle. A relatively large globular pressing body with a radius of 5 mm was set as a transducer in the measuring system, so that the conformity of the practically measured values to those calculated theoretically by the model was increased. Strain of skin-muscle is expressed as a function of the load, which includes indices of elasticity (1/M) (M(N/mm2) = E/(1-lambda 2) (E: Young's modulus, lambda:Poisson's ratio)) and viscosity (1/eta) (eta:modulus of viscosity) in a particular region. Because hardness is defined as the degree of resistance against transformation by loading, decreases in the indices of both elasticity and viscosity mean increases of hardness. With 150 male and female office workers chosen as the subjects, the model was examined and the indices were calculated. The results were as follows. 1) Very good conformity of practically measured values to those calculated theoretically by the Maxwell model was recognized within the range of load velocity from 0.3 G to 3.0 G (N/sec). 2) In both males and females the regions with values nearest to those of a Newtonian fluid were, in descending order, the distal phalanxes of digiti 2-4, the palm, the distal phalanx of the first digitus and the arm. In reverse order these regions approached complete elasticity. 3) In males it was suggested that the element of viscosity in the region of the biceps brachii muscle and the hardness in the regions of the brachioradialis, the flexor carpi radialis and palmalis longus muscles and the distal phalanxes of the 4th and the 5th digiti were increased with age. In females, a decrease in hardness in the region of the biceps brachii muscle with age was observed. 4) The indices of not only elasticity, but also of viscosity in females were higher than those in males. The results showed that for both elasticity and viscosity, the hardness of skin-muscles in males were higher than that in females. Furthermore, the index of plasticity was determined by examining the mark remaining after unloading, and good correlation of the index to age was observed.(ABSTRACT TRUNCATED AT 400 WORDS)

Physico-chemical characteristics of groundwater in and around Surat City (India).

PubMed

Raval, Viral H; Malik, G M

2010-10-01

Groundwater samples were collected from different locations of Surat city, Gujarat (India). These samples from 32 locations of Surat city were analysed for their physico-chemical characteristics involving pH, colour, odour, hardness, chloride, alkalinity, COD, sulfate, TDS, SS, iron, Cu, boron, chromium, temperature and Langelier Saturation Index. On comparing the results against drinking water quality standards laid by Indian Council of Medical Research (ICMR) and World Health Organization (WHO), it is found that most of the water samples are non-potable. Most of the samples indicated Total Alkalinity, Hardness, Chloride and TDS values much higher than the permissible level stipulated by ICMR and WHO. Even at some places Langelier Saturation Index values found higher too. The high values of these parameters may have health implications and therefore these need attention.

The Relationship Between the Accumulated Number of Role Transitions and Hard Drug Use Among Hispanic Emerging Adults

PubMed Central

Allem, Jon-Patrick; Soto, Daniel; Baezconde-Garbanati, Lourdes; Unger, Jennifer

2014-01-01

Emerging adults (ages 18 to 25) who experience multiple role transitions in a short period of time may engage in hard drug use as a maladaptive coping strategy to avoid negative emotions from stress. Given the collectivistic values Hispanics encounter growing up, they may experience additional role transitions due to their group oriented cultural paradigm. This study examined whether those who experience many role transitions are at greater risk for hard drug use compared to those who experience few transitions among Hispanic emerging adults. Participants completed surveys indicating their hard drug use in emerging adulthood, role transitions in the past year of emerging adulthood, age, gender, and hard drug use in high school. Simulation analyses indicated that an increase in the number of role transitions, from 0 to 13, was associated with a 14% (95% CI, 4 to 29) higher probability of hard drug use. Specific role transitions were found to be associated with hard drug use, such as starting to date or experiencing a breakup. Intervention/prevention programs may benefit from acknowledging individual reactions to transitions in emerging adulthood, as these processes may be catalysts for personal growth where identities are consolidated, and decisions regarding hard drug use are formed. PMID:25715073

Influence of photoactivation method and mold for restoration on the Knoop hardness of resin composite restorations.

PubMed

Brandt, William Cunha; Silva-Concilio, Lais Regiane; Neves, Ana Christina Claro; de Souza-Junior, Eduardo Jose Carvalho; Sinhoreti, Mario Alexandre Coelho

2013-09-01

The aim of this study was to evaluate in vitro the Knoop hardness in the top and bottom of composite photo activated by different methods when different mold materials were used. Z250 (3M ESPE) and XL2500 halogen unit (3M ESPE) were used. For hardness test, conical restorations were made in extracted bovine incisors (tooth mold) and also metal mold (approximately 2 mm top diameter × 1.5 mm bottom diameter × 2 mm in height). Different photoactivation methods were tested: high-intensity continuous (HIC), low-intensity continuous (LIC), soft-start, or pulse-delay (PD), with constant radiant exposure. Knoop readings were performed on top and bottom restoration surfaces. Data were submitted to two-way ANOVA and Tukey's test (p = 0.05). On the top, regardless of the mold used, no significant difference in the Knoop hardness (Knoop hardness number, in kilograms-force per square millimeter) was observed between the photoactivation methods. On the bottom surface, the photoactivation method HIC shows higher means of hardness than LIC when tooth and metal were used. Significant differences of hardness on the top and in the bottom were detected between tooth and metal. The photoactivation method LIC and the material mold can interfere in the hardness values of composite restorations.

The Relationship Between the Accumulated Number of Role Transitions and Hard Drug Use among Hispanic Emerging Adults.

PubMed

Allem, Jon-Patrick; Soto, Daniel; Baezconde-Garbanati, Lourdes; Unger, Jennifer

2015-01-01

Emerging adults (ages 18 to 25) who experience multiple role transitions in a short period of time may engage in hard drug use as a maladaptive coping strategy to avoid negative emotions from stress. Given the collectivistic values Hispanics encounter growing up, they may experience additional role transitions due to their group-oriented cultural paradigm. This study examined whether those who experience many role transitions are at greater risk for hard drug use compared to those who experience few transitions among Hispanic emerging adults. Participants completed surveys indicating their hard drug use in emerging adulthood, role transitions in the past year of emerging adulthood, age, gender, and hard drug use in high school. Simulation analyses indicated that an increase in the number of role transitions, from 0 to 13, was associated with a 14% (95% CI, 4 to 29) higher probability of hard drug use. Specific role transitions were found to be associated with hard drug use, such as starting to date or experiencing a breakup. Intervention/prevention programs may benefit from acknowledging individual reactions to transitions in emerging adulthood, as these processes may be catalysts for personal growth where identities are consolidated and decisions regarding hard drug use are formed.

[Determination of Hard Rate of Alfalfa (Medicago sativa L.) Seeds with Near Infrared Spectroscopy].

PubMed

Wang, Xin-xun; Chen, Ling-ling; Zhang, Yun-wei; Mao, Pei-sheng

2016-03-01

Alfalfa (Medicago sativa L.) is the most commonly grown forage crop due to its better quality characteristics and high adaptability in China. However, there was 20%-80% hard seeds in alfalfa which could not be identified easily from non hard seeds which would cause the loss of seed utilization value and plant production. This experiment was designed for 121 samples of alfalfa. Seeds were collected according to different regions, harvested year and varieties. 31 samples were artificial matched as hard rates ranging from 20% to 80% to establish a model for hard seed rate by near infrared spectroscopy (NIRS) with Partial Least Square (PLS). The objective of this study was to establish a model and to estimate the efficiency of NIRS for determining hard rate of alfalfa seeds. The results showed that the correlation coefficient (R2(cal)) of calibration model was 0.981 6, root mean square error of cross validation (RMSECV) was 5.32, and the ratio of prediction to deviation (RPD) was 3.58. The forecast model in this experiment presented the satisfied precision. The proposed method using NIRS technology is feasible for identification and classification of hard seed in alfalfa. A new method, as nondestructive testing of hard seed rate, was provided to theoretical basis for fast nondestructive detection of hard seed rates in alfalfa.

Evaluation of rebreathing potential on bedding for infant use.

PubMed

Kanetake, Jun; Aoki, Yasuhiro; Funayama, Masato

2003-06-01

Rebreathing is thought to be associated with sudden infant death syndrome (SIDS). The aim of the present study was to evaluate the rebreathing potential of different types of Japanese infant bedding. The rebreathing potential of various combinations of infant bedding was measured using a mechanically simulated breathing model. The types of bedding included five types of mattresses, four types of o-nesyo sheets (waterproof sheets) and a towel. The half-life of the expiratory CO2 concentration, t1/2-value was calculated as the index of the rebreathing potential. The softness of the bedding was also measured. There was a moderate proportional correlation between the t1/2-value and the softness (correlation coefficient = 0.509). When a new hard infant mattress was used, the t1/2-values were 13.6-14.1 s, and when o-nesyo sheet was added, the values were 14.1-16.2 s. When other mattresses were used with the o-nesyo sheet, the values were 14.1-19.2 s. Adding a towel onto the bedding, the t1/2-value (18.5-22.3 s) was prolonged without exception. It is difficult to estimate the rebreathing potential of the bedding on the basis its appearance or its softness. All infants should be placed on appropriate bedding in case they turn to a prone-sleeping position. Our recommendations to avoid rebreathing are as follows: (i) a new hard mattress specifically designed for babies should be used; (ii) a towel should not be used; (iii) an o-nesyo sheet may be used with a new hard infant mattress if necessary.

Effect of CrO3 Sealing Time on Anodized A12024-T3

NASA Astrophysics Data System (ADS)

Korda, Akhmad A.; Hidayat, R. Z.

2016-08-01

The effect of CrO3 sealing time on anodized aluminum alloy has been investigated. A1 2024-T3 were used as substrate. Anodizing was carried out using chromic acid. CrO3 sealing was conducted in CrO3 solution for 30, 60, 90, 120 and 150 minutes. As comparison, other specimens were also prepared as anodized and boiled water sealing. Thickness of the coating was observed by optical microscope. Anodized and sealing layer was analyzed by X- ray diffraction. The hardness of as anodized, boiled water sealing and CrO3 sealing were compared. The highest hardness is achieved by CrO3 sealed specimen and followed by boiled water sealing and as anodized specimens. The longer the processes of CrO3 sealing the higher layer thickness and therefore the higher hardness of the oxide layer. The best resistance to electrolyte penetration is achieved by the CrO3 sealed specimen followed by boiled water sealed and as anodized specimens. The higher thickness of oxide layer, the higher the resistance against electrolyte penetration.

Wheat flour confectionery products as a source of inorganic nutrients: iron and manganese contents in hard biscuits.

PubMed

Sebecić, Blazenka; Dragojević, I Vedrina; Horvatić, M

2002-06-01

To evaluate some wheat flour based hard biscuits produced in Croatia with regard to their Fe and Mn contents and thereby their functionality, Fe and Mn are determined by cold-vapor atomic absorption spectrometry (CVAAS) in seven biscuits: classic white wheat flour biscuits and in dietetic biscuits enriched with whole wheat grain flour or whole wheat grain grits, soya flour and milk. Presented data show that Fe contents in seven analyzed biscuits range from 9.32 up to 24.80 mg/kg while Mn contents range from 3.76-16.37 mg/kg depending on type and share of cereal milling products and mineral content of other raw materials used. Thus, enriched biscuits produced from wheat flour type 850 and whole wheat grain flour, having the highest concentrations of Fe and Mn, were about 150% and 250%, respectively, richer in those elements in comparison with classic white flour biscuits of Petit Beurre type. Data show that wheat flour based hard biscuits, particularly enriched biscuits, can be considered as a good additional source of Fe and Mn in diets.

Influence of extrusion-cooking parameters on some quality aspects of precooked pasta-like products.

PubMed

Wójtowicz, A; Mościcki, L

2009-06-01

The present article aims to evaluate some quality parameters and texture characteristics of precooked wheat pasta-like products. Using the methods for pasta and instant noodles the tested parameters were water absorption, starch gelatinization degree, cooking losses, and hardness. The texture profile was characterized using Zwick apparatus by cutting test with the head speed of 10 mm/min and expressed as hardness and firmness of hydrated products. SEM pictures were used to illustrate the internal structure of dry and cooked pasta-like products. Dough moisture content and process conditions influenced all tested quality parameters of the pasta-like products processed on a modified single screw extrusion-cooker TS-45 with L: D = 16: 1. Good organoleptical quality (notes higher than 4 in a 5-point scale) and firm texture were observed for common wheat flour pasta processed at 30% m.c. Hardness and firmness of hydrated products lowered with a longer hydration time in hot water. The firmest texture and low stickiness was observed for products with a highest starch gelatinization degree.

Elastic properties of dense solid phases of hard cyclic pentamers and heptamers in two dimensions.

PubMed

Wojciechowski, K W; Tretiakov, K V; Kowalik, M

2003-03-01

Systems of model planar, nonconvex, hard-body "molecules" of fivefold and sevenfold symmetry axes are studied by constant pressure Monte Carlo simulations with variable shape of the periodic box. The molecules, referred to as pentamers (heptamers), are composed of five (seven) identical hard disks "atoms" with centers forming regular pentagons (heptagons) of sides equal to the disk diameter. The elastic compliances of defect-free solid phases are computed by analysis of strain fluctuations and the reference (equilibrium) state is determined within the same run in which the elastic properties are computed. Results obtained by using pseudorandom number generators based on the idea proposed by Holian and co-workers [Holian et al., Phys. Rev. E 50, 1607 (1994)] are in good agreement with the results generated by DRAND48. It is shown that singular behavior of the elastic constants near close packing is in agreement with the free volume approximation; the coefficients of the leading singularities are estimated. The simulations prove that the highest density structures of heptamers (in which the molecules cannot rotate) are auxetic, i.e., show negative Poisson ratios.

Development of 2024 AA-Yttrium composites by Spark Plasma Sintering

NASA Astrophysics Data System (ADS)

Vidyasagar, CH S.; Karunakar, D. B.

2018-04-01

The method of fabrication of MMNCs is quite a challenge, which includes advanced processing techniques like Spark Plasma Sintering (SPS), etc. The objective of the present work is to fabricate aluminium based MMNCs with the addition of small amounts of yttrium using Spark Plasma Sintering and to evaluate their mechanical and microstructure properties. Samples of 2024 AA with yttrium ranging from 0.1% to 0.5 wt% are fabricated by Spark Plasma Sintering (SPS). Hardness of the samples is determined using Vickers hardness testing machine. The metallurgical characterization of the samples is evaluated by Optical Microscopy (OM), Field Emission Scanning Electron Microscopy (FE-SEM). Unreinforced 2024 AA sample is also fabricated as a benchmark to compare its properties with those of the composite developed. It is found that the yttrium addition increases the above mentioned properties by altering the precipitation kinetics and intermetallic formation to some extent and then decreases gradually when yttrium wt% increases beyond 0.3 wt%. High density (˂ 99.75) is achieved in the samples and highest hardness achieved is 114 Hv, fabricated by spark plasma sintering and uniform distribution of yttrium is observed.

Carbon dioxide exchange in compact and semi-open sorghum inflorescences

DOE Office of Scientific and Technical Information (OSTI.GOV)

Eastin, J.D.; Sullivan, C.Y.

Carbon dioxide exchange rates were monitored in light and dark in compact and semi-open heads of sorghum (Sorghum bicolor (L.) Moench). Developmental stages ranged from bottom to hard dough in the grain. Highest CO/sub 2/ uptake in both head types occurred at the bloom stage when net uptake rates for semi-open and compact type heads were 3.9 and 1.2 mg CO/sub 2/ g dry wt/sup -1/ hr/sup -1/, respectively. Beginning at the milk stage, a net CO/sub 2/ evolution on the order of 1 to 1.4 mg g dry wt/sup -1/ hr/sup -1/ occurred in compact heads in the light.more » The semi-open head type continued a small net CO/sub 2/ uptake in the light through the milk and soft dough stages. Both head types evolved CO/sub 2/ at hard dough stage. Dark respiration was similar in both head types and decreased from about 4 to 1 mg CO/sub 2/ g dry wt/sup -1/ hr/sup -1/ from bloom to hard dough. 16 references, 1 figure.« less

Measurements of the hard-x-ray reflectivity of iridium

DOE Office of Scientific and Technical Information (OSTI.GOV)

Romaine, S.; Bruni, R.; Gorenstein, P.

2007-01-10

In connection with the design of a hard-x-ray telescope for the Constellation X-Ray Observatory we measured the reflectivity of an iridium-coated zerodur substrate as a function of angle at 55, 60, 70, and 80 keV at the National Synchrotron Light Source of Brookhaven National Laboratory. The optical constants were derived from the reflectivity data. The real component of the index of refraction is in excellent agreement with theoretical values at all four energies. However, the imaginary component, which is related to the mass attenuation coefficient, is 50% to 70% larger at 55, 60, and 70 keV than theoretical values.

Measurements of the hard-x-ray reflectivity of iridium.

PubMed

Romaine, S; Bruni, R; Gorenstein, P; Zhong, Z

2007-01-10

In connection with the design of a hard-x-ray telescope for the Constellation X-Ray Observatory we measured the reflectivity of an iridium-coated zerodur substrate as a function of angle at 55, 60, 70, and 80 keV at the National Synchrotron Light Source of Brookhaven National Laboratory. The optical constants were derived from the reflectivity data. The real component of the index of refraction is in excellent agreement with theoretical values at all four energies. However, the imaginary component, which is related to the mass attenuation coefficient, is 50% to 70% larger at 55, 60, and 70 keV than theoretical values.

Effect of accelerated aging on the cross-link density of medical grade silicones.

PubMed

Mahomed, Aziza; Pormehr, Negin Bagheri

2016-11-25

Four specimens of Nagor silicone of different hardness (soft, medium and hard) were swollen, until they reached equilibrium (i.e. constant mass) in five liquids at 25°C, before and after accelerated aging. For the specimens swollen before accelerated aging, the greatest swelling was obtained in methyl cyclohexane, while for the specimens swollen after accelerated aging, the greatest swelling was obtained in cyclohexane. The cross-link density, υ, was also calculated from the swelling measurements for all the specimens, before and after accelerated aging, using the Flory-Rehner equation. The softer silicones, which swelled the most, had lower υ values than harder silicones. The amount of swelling (measured in terms of ϕ) and υ varied significantly (p<0.05) in some cases, between the different silicone hardness and between different liquids. Furthermore, the cross-link density, υ, significantly (p<0.05) increased after accelerated aging in most liquids.Note: ϕ is defined as the volume fraction of polymer in its equilibrium swollen state. A probability value of statistical significance of 0.05 or 5% was selected, hence if a p value of less than 0.05 was obtained, the null hypothesis was rejected (i.e. significant if p<0.05).

Simulation and experimental analysis of nanoindentation and mechanical properties of amorphous NiAl alloys.

PubMed

Wang, Chih-Hao; Fang, Te-Hua; Cheng, Po-Chien; Chiang, Chia-Chin; Chao, Kuan-Chi

2015-06-01

This paper used numerical and experimental methods to investigate the mechanical properties of amorphous NiAl alloys during the nanoindentation process. A simulation was performed using the many-body tight-binding potential method. Temperature, plastic deformation, elastic recovery, and hardness were evaluated. The experimental method was based on nanoindentation measurements, allowing a precise prediction of Young's modulus and hardness values for comparison with the simulation results. The indentation simulation results showed a significant increase of NiAl hardness and elastic recovery with increasing Ni content. Furthermore, the results showed that hardness and Young's modulus increase with increasing Ni content. The simulation results are in good agreement with the experimental results. Adhesion test of amorphous NiAl alloys at room temperature is also described in this study.

A study to evaluate cephalometric hard tissue profile of Tamil population for orthognathic surgery

PubMed Central

Nachiappan, S.; Tharanikumar, S.; Chandran, Ajay; Anusudha, P.; Nandini, G. D.; Balasubramaniam, Murali

2015-01-01

The primary aim of this study is to compare, the cephalometric hard tissue profile values and analysis between Tamil and Caucasian population. The study also aims to create a better understanding in the facial proportions of Tamil Nadu population and to have better diagnosis and treatment planning for orthognathic surgery for Tamil population in Tamil Nadu. PMID:26538943

Reducing the influence of the surface roughness on the hardness measurement using instrumented indentation test

NASA Astrophysics Data System (ADS)

Maslenikov, I.; Useinov, A.; Birykov, A.; Reshetov, V.

2017-10-01

The instrumented indentation method requires the sample surface to be flat and smooth; thus, hardness and elastic modulus values are affected by the roughness. A model that accounts for the isotropic surface roughness and can be used to correct the data in two limiting cases is proposed. Suggested approach requires the surface roughness parameters to be known.

The Impact of the HIV/AIDS and Economic Crises on Orphans and Other Vulnerable Children in Zimbabwe

ERIC Educational Resources Information Center

Chitiyo, George; Chitiyo, Morgan

2009-01-01

Zimbabwe, like most of Sub-Saharan Africa, has been hard-hit by HIV/ AIDS. National estimates reported by the Ministry of Health and Child Welfare put the prevalence rates of HIV in the age group between 15 and 49 at 15.3% (World Health Organization [WHO], UNICEF, & UNAIDS, 2008). This is one of the highest HIV/AIDS prevalence rates in the…

Novel hard compositions and methods of preparation

DOEpatents

Sheinberg, Haskell

1983-08-23

Novel very hard compositions of matter are prepared by using in all embodiments only a minor amount of a particular carbide (or materials which can form the carbide in situ when subjected to heat and pressure); and no strategic cobalt is needed. Under a particular range of conditions, densified compositions of matter of the invention are prepared having hardnesses on the Rockwell A test substantially equal to the hardness of pure tungsten carbide and to two of the hardest commercial cobalt-bonded tungsten carbides. Alternately, other compositions of the invention which have slightly lower hardnesses than those described above in one embodiment also possess the advantage of requiring no tungsten and in another embodiment possess the advantage of having a good fracture toughness value. Photomicrographs show that the shapes of the grains of the alloy mixture with which the minor amount of carbide (or carbide-formers) is mixed are radically altered from large, rounded to small, very angular by the addition of the carbide. Superiority of one of these hard compositions of matter over cobalt-bonded tungsten carbide for ultra-high pressure anvil applications was demonstrated.

Hard-hard coupling assisted anomalous magnetoresistance effect in amine-ended single-molecule magnetic junction

NASA Astrophysics Data System (ADS)

Tang, Y.-H.; Lin, C.-J.; Chiang, K.-R.

2017-06-01

We proposed a single-molecule magnetic junction (SMMJ), composed of a dissociated amine-ended benzene sandwiched between two Co tip-like nanowires. To better simulate the break junction technique for real SMMJs, the first-principles calculation associated with the hard-hard coupling between a amine-linker and Co tip-atom is carried out for SMMJs with mechanical strain and under an external bias. We predict an anomalous magnetoresistance (MR) effect, including strain-induced sign reversal and bias-induced enhancement of the MR value, which is in sharp contrast to the normal MR effect in conventional magnetic tunnel junctions. The underlying mechanism is the interplay between four spin-polarized currents in parallel and anti-parallel magnetic configurations, originated from the pronounced spin-up transmission feature in the parallel case and spiky transmission peaks in other three spin-polarized channels. These intriguing findings may open a new arena in which magnetotransport and hard-hard coupling are closely coupled in SMMJs and can be dually controlled either via mechanical strain or by an external bias.

Novel hard compositions and methods of preparation

DOEpatents

Sheinberg, H.

1983-08-23

Novel very hard compositions of matter are prepared by using in all embodiments only a minor amount of a particular carbide (or materials which can form the carbide in situ when subjected to heat and pressure); and no strategic cobalt is needed. Under a particular range of conditions, densified compositions of matter of the invention are prepared having hardnesses on the Rockwell A test substantially equal to the hardness of pure tungsten carbide and to two of the hardest commercial cobalt-bonded tungsten carbides. Alternately, other compositions of the invention which have slightly lower hardnesses than those described above in one embodiment also possess the advantage of requiring no tungsten and in another embodiment possess the advantage of having a good fracture toughness value. Photomicrographs show that the shapes of the grains of the alloy mixture with which the minor amount of carbide (or carbide-formers) is mixed are radically altered from large, rounded to small, very angular by the addition of the carbide. Superiority of one of these hard compositions of matter over cobalt-bonded tungsten carbide for ultra-high pressure anvil applications was demonstrated. 3 figs.

High Capacity of Hard Carbon Anode in Na-Ion Batteries Unlocked by PO x Doping

DOE Office of Scientific and Technical Information (OSTI.GOV)

Li, Zhifei; Ma, Lu; Surta, Todd Wesley

2016-08-12

The capacity of hard carbon anodes in Na-ion batteries 2.5 rarely reaches values beyond 300 mAh/g. We report that doping POx into local structures of hard carbon increases its reversible capacity from 283 to 359 mAh/g. We confirm that the doped POx is redox inactive by X-ray adsorption near edge structure measurements, thus not contributing to the higher capacity. We observe two significant changes of hard carbon's local structures caused by doping. First, the (002) d-spacing inside the turbostratic nanodomains is increased, revealed by both laboratory and synchrotron X-ray diffraction. Second, doping turns turbostratic nanodomains more defective along ab planes,more » indicated by neutron total scattering and the associated pair distribution function studies. The local structural changes of hard carbon are correlated to the higher capacity, where both the plateau and slope regions in the potential profiles are enhanced. Our study demonstrates that Na-ion storage in hard carbon heavily depends on carbon local structures, where such structures, despite being disordered, can be tuned toward unusually high capacities.« less

Effect of water hardness on the production and microbicidal efficacy of slightly acidic electrolyzed water.

PubMed

Forghani, Fereidoun; Park, Joong-Hyun; Oh, Deog-Hwan

2015-06-01

Slightly acidic electrolyzed water (SAEW) has been proved as an effective sanitizer against microorganisms attached to foods. However, its physical properties and inactivation efficacy are affected by several factors such as water hardness. Therefore, in this study the effect of water hardness on SAEW properties were studied. Pure cultures of foodborne bacteria were used in vitro and in vivo to evaluate the inactivation efficacy of the SAEWs produced. Results obtained showed water hardness to be an important factor in the production of SAEW. Low water hardness may result in the necessity of further optimization of production process. In this study the addition of 5% HCl and 2 M NaCl at 1.5 mL/min flow rate was found to be the best electrolyte concentration for the optimization of SAEW production from low hardness water (34 ± 2 mg/L). Furthermore, the results showed that pre-heating was a better approach compared to post-production heating of SAEW, resulting in higher ACC values and therefor better sanitization efficacy. Copyright © 2014 Elsevier Ltd. All rights reserved.

The effect of stunning methods and season on muscle texture hardness in Atlantic salmon (Salmo salar L.).

PubMed

Merkin, Grigory V; Stien, Lars Helge; Pittman, Karin; Nortvedt, Ragnar

2014-06-01

Commercially collected records of Atlantic salmon (Salmo salar L.) muscle texture hardness were used to evaluate the effect of slaughter procedures and seasonality on texture quality. A database collected by Marine Harvest® contained flesh hardness records of Atlantic salmon slaughtered at processing plants in Norway from summer 2010 to summer 2011. The fish were slaughtered either by (1) percussion followed by automated bleeding ("Percussive") or (2) live chilling with exposure to carbon dioxide (CO2 ) followed by manual severing gill arches and bleeding ("CO2 ") or (3) live chilling with exposure to CO2 followed by percussive stunning and at the end automated bleeding ("CO2 ·percussive"). Hardness in salmon muscle cutlets was measured in Newtons (N) by Materials Testing Machine Zwick 500N. The hardness in salmon varied significantly over the study period (P < 0.05, mixed effect model) and showed the softest value of 21.2 (± 0.7) Newton (N) in summer 2011 and hardest 24.1 (± 0.2) N in autumn 2010. Slaughter procedures had a significant effect on salmon muscle hardness (P < 0.05, mixed effect model), where percussion followed by automated bleeding resulted in the hardest value (24.0 ± 0.4 N) as compared with CO2 stunning (21.8 ± 0.2 N) and combination of CO2 and percussive stunning (23.1 ± 0.15 N). CO2 is suspected as a causal factor in accelerated postmortem softening of the salmon muscle. Commercial use of CO2 in combination with live chilling results in accelerated postmortem softening of the muscle tissue in salmon and should be avoided. © 2014 Institute of Food Technologists®

Reliability and validity of quantifying absolute muscle hardness using ultrasound elastography.

PubMed

Chino, Kentaro; Akagi, Ryota; Dohi, Michiko; Fukashiro, Senshi; Takahashi, Hideyuki

2012-01-01

Muscle hardness is a mechanical property that represents transverse muscle stiffness. A quantitative method that uses ultrasound elastography for quantifying absolute human muscle hardness has been previously devised; however, its reliability and validity have not been completely verified. This study aimed to verify the reliability and validity of this quantitative method. The Young's moduli of seven tissue-mimicking materials (in vitro; Young's modulus range, 20-80 kPa; increments of 10 kPa) and the human medial gastrocnemius muscle (in vivo) were quantified using ultrasound elastography. On the basis of the strain/Young's modulus ratio of two reference materials, one hard and one soft (Young's moduli of 7 and 30 kPa, respectively), the Young's moduli of the tissue-mimicking materials and medial gastrocnemius muscle were calculated. The intra- and inter-investigator reliability of the method was confirmed on the basis of acceptably low coefficient of variations (≤6.9%) and substantially high intraclass correlation coefficients (≥0.77) obtained from all measurements. The correlation coefficient between the Young's moduli of the tissue-mimicking materials obtained using a mechanical method and ultrasound elastography was 0.996, which was equivalent to values previously obtained using magnetic resonance elastography. The Young's moduli of the medial gastrocnemius muscle obtained using ultrasound elastography were within the range of values previously obtained using magnetic resonance elastography. The reliability and validity of the quantitative method for measuring absolute muscle hardness using ultrasound elastography were thus verified.

Reliability and Validity of Quantifying Absolute Muscle Hardness Using Ultrasound Elastography

PubMed Central

Chino, Kentaro; Akagi, Ryota; Dohi, Michiko; Fukashiro, Senshi; Takahashi, Hideyuki

2012-01-01

Muscle hardness is a mechanical property that represents transverse muscle stiffness. A quantitative method that uses ultrasound elastography for quantifying absolute human muscle hardness has been previously devised; however, its reliability and validity have not been completely verified. This study aimed to verify the reliability and validity of this quantitative method. The Young’s moduli of seven tissue-mimicking materials (in vitro; Young’s modulus range, 20–80 kPa; increments of 10 kPa) and the human medial gastrocnemius muscle (in vivo) were quantified using ultrasound elastography. On the basis of the strain/Young’s modulus ratio of two reference materials, one hard and one soft (Young’s moduli of 7 and 30 kPa, respectively), the Young’s moduli of the tissue-mimicking materials and medial gastrocnemius muscle were calculated. The intra- and inter-investigator reliability of the method was confirmed on the basis of acceptably low coefficient of variations (≤6.9%) and substantially high intraclass correlation coefficients (≥0.77) obtained from all measurements. The correlation coefficient between the Young’s moduli of the tissue-mimicking materials obtained using a mechanical method and ultrasound elastography was 0.996, which was equivalent to values previously obtained using magnetic resonance elastography. The Young’s moduli of the medial gastrocnemius muscle obtained using ultrasound elastography were within the range of values previously obtained using magnetic resonance elastography. The reliability and validity of the quantitative method for measuring absolute muscle hardness using ultrasound elastography were thus verified. PMID:23029231

Reply to "Comment on 'Calculations for the one-dimensional soft Coulomb problem and the hard Coulomb limit' ".

PubMed

Gebremedhin, Daniel H; Weatherford, Charles A

2015-02-01

This is a response to the comment we received on our recent paper "Calculations for the one-dimensional soft Coulomb problem and the hard Coulomb limit." In that paper, we introduced a computational algorithm that is appropriate for solving stiff initial value problems, and which we applied to the one-dimensional time-independent Schrödinger equation with a soft Coulomb potential. We solved for the eigenpairs using a shooting method and hence turned it into an initial value problem. In particular, we examined the behavior of the eigenpairs as the softening parameter approached zero (hard Coulomb limit). The commenters question the existence of the ground state of the hard Coulomb potential, which we inferred by extrapolation of the softening parameter to zero. A key distinction between the commenters' approach and ours is that they consider only the half-line while we considered the entire x axis. Based on mathematical considerations, the commenters consider only a vanishing solution function at the origin, and they question our conclusion that the ground state of the hard Coulomb potential exists. The ground state we inferred resembles a δ(x), and hence it cannot even be addressed based on their argument. For the excited states, there is agreement with the fact that the particle is always excluded from the origin. Our discussion with regard to the symmetry of the excited states is an extrapolation of the soft Coulomb case and is further explained herein.

Toxicity of cadmium to goldfish, Carassius auratus, in hard, and soft water

DOE Office of Scientific and Technical Information (OSTI.GOV)

McCarty, L.S.; Henry, J.A.C.; Houston, A.H.

1978-01-01

Variations in cadmium form and concentration and in selected water quality parameters (pH, dissolved oxygen, total hardness, total alkalinity, conductivity) were monitored during static bioassays conducted with relatively soft (approximately 20 mg/L as CaCO/sub 3/) and hard (approximately 140 mg/L as CaCO/sub 3/) waters. Cadmium concentrations were reasonably stable in soft water, and with the exception of total hardness, water quality was not greatly altered during assay. Cumulative mortality curves were of a simple sigmoidal type and readily analyzed by conventional procedures. LC50 values of 2.76, 2.13, and 1.78 mg Cd/L were estimated on the basis of 48-, 96-, andmore » 240-h periods of observation. During hard-water trials there were transient increases in the amount of particulate cadmium present and sharp decreases in total cadmium levels. Several parameters (pH, total alkalinity, conductivity) exhibited transient and/or sustained variations of a cadmium concentration-dependent type. Mortality curves were typically biphasic. The extent of first-phase mortality was significantly correlated with the magnitude of the initial pH decline and the amount of cadmium present in centrifugable form. Conventional procedures did not result in rectification of 240-h cumulative mortality curves, and the 240-h LC50 value (40.2 mg Cd/L) is considered to be inherently less precise than those obtained on the basis of 48- and 96-h periods of observation (46.9, 46.8 mg Cd/L).« less

Cultural values associated with substance use among Hispanic emerging adults in Southern California.

PubMed

Escobedo, Patricia; Allem, Jon-Patrick; Baezconde-Garbanati, Lourdes; Unger, Jennifer B

2018-02-01

Hispanic emerging adults are a priority population for substance use prevention, yet few studies have examined whether traditional Hispanic cultural values serve as risk or protective factors for substance use among emerging adults. This study examined the relationship between familism, respeto, fatalism, and substance use among Hispanic emerging adults. Participants (ages 18 to 25) completed surveys indicating identification with familism, respeto, and fatalism, past month use of tobacco, marijuana, hard drugs and binge drinking. Separate logistic regression models examined the association between cultural values and each substance use outcome, controlling for acculturation, age and gender. Among participants (n=1445, mean age=23, 60% female), 21% reported past month cigarette use, 18% reported past month alternative tobacco product (ATP) use, 25% reported past month marijuana use, 44% reported past month binge drinking, and 7% reported past month hard drug use. Higher fatalism scores were associated with increased ATP use. Higher familism scores were associated with binge drinking, while higher respeto scores were associated with decreased binge drinking, marijuana, and hard drug use. These findings suggest that substance use prevention and intervention programs should emphasize how substance use interferes with caring and honoring parents (respeto) and family cohesion and functioning (familism). Programs that highlight these cultural values and beliefs may be beneficial for Hispanic emerging adults and members of other collectivistic cultures. Copyright © 2017 Elsevier Ltd. All rights reserved.

Giant magnetoresistance (GMR) behavior of electrodeposited NiFe/Cu multilayers: Dependence of non-magnetic and magnetic layer thicknesses

NASA Astrophysics Data System (ADS)

Kuru, Hilal; Kockar, Hakan; Alper, Mursel

2017-12-01

Giant magnetoresistance (GMR) behavior in electrodeposited NiFe/Cu multilayers was investigated as a function of non-magnetic (Cu) and ferromagnetic (NiFe) layer thicknesses, respectively. Prior to the GMR analysis, structural and magnetic analyses of the multilayers were also studied. The elemental analysis of the multilayers indicated that the Cu and Ni content in the multilayers increase with increasing Cu and NiFe layer thickness, respectively. The structural studies by X-ray diffraction revealed that all multilayers have face centred cubic structure with preferred (1 1 0) crystal orientation as their substrates. The magnetic properties studied with the vibrating sample magnetometer showed that the magnetizations of the samples are significantly affected by the layer thicknesses. Saturation magnetisation, Ms increases from 45 to 225 emu/cm3 with increasing NiFe layer thickness. The increase in the Ni content of the multilayers with a small Fe content causes an increase in the Ms. And, the coercivities ranging from 2 to 24 Oe are between the soft and hard magnetic properties. Also, the magnetic easy axis of the multilayers was found to be in the film plane. Magnetoresistance measurements showed that all multilayers exhibited the GMR behavior. The GMR magnitude increases with increasing Cu layer thickness and reaches its maximum value of 10% at the Cu layer thickness of 1 nm, then it decreases. And similarly, the GMR magnitude increases and reaches highest value of pure GMR (10%) for the NiFe layer thickness of 3 nm, and beyond this point GMR decreases with increasing NiFe layer thickness. Some small component of the anisotropic magnetoresistance was also observed at thin Cu and thick NiFe layer thicknesses. It is seen that the highest GMR values up to 10% were obtained in electrodeposited NiFe/Cu multilayers up to now. The structural, magnetic and magnetoresistance properties of the NiFe/Cu were reported via the variations of the thicknesses of Cu and NiFe layers with stressing the role of layer thicknesses on the high GMR behavior.

Enhancement of the wear resistance and microhardness of aluminum alloy by Nd:YaG laser treatment.

PubMed

Hussein, Haitham T; Kadhim, Abdulhadi; Al-Amiery, Ahmed A; Kadhum, Abdul Amir H; Mohamad, Abu Bakar

2014-01-01

Influence of laser treatment on mechanical properties, wear resistance, and Vickers hardness of aluminum alloy was studied. The specimens were treated by using Nd:YaG laser of energy 780 mj, wavelength 512 nm, and duration time 8 ns. The wear behavior of the specimens was studied for all specimens before and after treatment by Nd:YaG laser and the dry wear experiments were carried out by sing pinon-disc technique. The specimens were machined as a disk with diameter of 25 mm and circular groove in depth of 3 mm. All specimens were conducted by scanning electron microscopy (SEM), energy-dispersive X-ray fluorescence analysis (EDS), optical microscopy, and Vickers hardness. The results showed that the dry wear rate was decreased after laser hardening and increased Vickers hardness values by ratio of 2.4:1. The results showed that the values of wear rate for samples having circular grooves are less than samples without grooves after laser treatment.

Comparative study on microstructure and martensitic transformation of aged Ni-rich NiTi and NiTiCo shape memory alloys

NASA Astrophysics Data System (ADS)

El-Bagoury, Nader

2016-05-01

In this article the influence of aging heat treatment conditions of 250, 350, 450 and 550 °C for 3 h on the microstructure, martensitic transformation temperatures and mechanical properties of Ni51Ti49Co0 and Ni47 Ti49Co4 shape memory alloys was investigated. This comparative study was carried out using X-ray diffraction analysis, scanning electron microscope, energy dispersive spectrometer, differential scanning calorimeter and Vickers hardness tester. The results show that the microstructure of both aged alloys contains martensite phase and Ti2Ni in addition to some other precipitates. The martensitic transformation temperature was increased steadily by increasing the ageing temperature and lowering the value of valence electron number (ev/a) and concentration. Moreover, the hardness measurements were gradually increased at first by increasing the aging temperature from 250 to 350 °C. Further elevating in aging temperature to 450 and 550 °C decreases the hardness value.

Characteristics of ADC12/nano Al2O3composites with Addition of Ti Produced By Stir Casting Method

NASA Astrophysics Data System (ADS)

Zulfia, A.; Krisiphala; Ferdian, D.; Utomo, B. W.; Dhaneswara, D.

2018-03-01

The mechanical properties and microstructure of ADC12/nano Al2O3 matrix composites have been studied in this work. The composites were produced by stir casting method. ADC 12 as matrix composites was combined by Mg and Ti. The addition of Ti was varied from 0.02 to 0.08 wt-% as grain refinement wetting to improve mechanical properties such as tensile strength, hardness and wear resistance, while Mg addition was to promote wetting between ADC 12 and nano Al2O3. The optimum tensile strength was found at 0.04 wt-% addition of Ti with value of 132.5 MPa, further adding more Ti cause a poisoning mechanism that will hindered the grain refining process and reduce the tensile strength. The hardness and wear resistance of composites would also increase because of the refinement process. and the added Magnesium in the material that will form Mg2Si primary phases who have a high hardness value.

Evolution of hardness, microstructure, and strain rate sensitivity in a Zn-22% Al eutectoid alloy processed by high-pressure torsion

NASA Astrophysics Data System (ADS)

Kawasaki, Megumi; Lee, Han-Joo; Choi, In-Chul; Jang, Jae-il; Ahn, Byungmin; Langdon, Terence G.

2014-08-01

Severe plastic deformation (SPD) is an attractive processing method for refining microstructures of metallic materials to give ultrafine grain sizes within the submicrometer to even the nanometer levels. Experiments were conducted to discuss the evolution of hardness, microstructure and strain rate sensitivity, m, in a Zn-22% Al eutectoid alloy processed by high- pressure torsion (HPT). The data from microhardness and nanoindentation hardness measurements revealed that there is a significant weakening in the Zn-Al alloy during HPT despite extensive grain refinement. Excellent room-temperature (RT) plasticity was observed in the alloy after HPT from nanoindentation creep in terms of an increased value of m. The microstructural changes with increasing numbers of HPT turns show a strong correlation with the change in the m value. Moerover, the excellent RT plasticity in the alloy is discussed in terms of the enhanced level of grain boundary sliding and the evolution of microsturucture.

Cross-Cultural Faculty Values.

ERIC Educational Resources Information Center

Keim, Marybelle C.

1992-01-01

Compares the terminal values of 24 visiting scholars from the People's Republic of China based at a midwestern community college with resident faculty values. The Chinese scholars ranked freedom, equality, and self-respect highest, whereas U.S. schools gave highest rankings to salvation, family security, and self-respect. Contrasts findings with a…

Spectroscopic studies and quantum chemical investigations of (3,4-dimethoxybenzylidene) propanedinitrile

NASA Astrophysics Data System (ADS)

Gupta, Ujval; Kumar, Vinay; Singh, Vivek K.; Kant, Rajni; Khajuria, Yugal

2015-04-01

The Fourier Transform Infrared (FTIR), Ultra-Violet Visible (UV-Vis) spectroscopy and Thermogravimetric (TG) analysis of (3,4-dimethoxybenzylidene) propanedinitrile have been carried out and investigated using quantum chemical calculations. The molecular geometry, harmonic vibrational frequencies, Mulliken charges, natural atomic charges and thermodynamic properties in the ground state have been investigated by using Hartree Fock Theory (HF) and Density Functional Theory (DFT) using B3LYP functional with 6-311G(d,p) basis set. Both HF and DFT methods yield good agreement with the experimental data. Vibrational modes are assigned with the help of Vibrational Energy Distribution Analysis (VEDA) program. UV-Visible spectrum was recorded in the spectral range of 190-800 nm and the results are compared with the calculated values using TD-DFT approach. Stability of the molecule arising from hyperconjugative interactions, charge delocalization have been analyzed using natural bond orbital (NBO) analysis. The results obtained from the studies of Highest Occupied Molecular Orbital (HOMO) and Lowest Unoccupied Molecular Orbital (LUMO) are used to calculate molecular parameters like ionization potential, electron affinity, global hardness, electron chemical potential and global electrophilicity.

Pulverizing processes affect the chemical quality and thermal property of black, white, and green pepper (Piper nigrum L.).

PubMed

Liu, Hong; Zheng, Jie; Liu, Pengzhan; Zeng, Fankui

2018-06-01

In this study, the effects of different pulverizing methods on the chemical attributes and thermal properties of black, white and green pepper were evaluated. Cryogenic grinding minimally damaged the lipid, moisture, crude protein, starch, non-volatile ether extract, piperine, essential oil and the typical pepper essential oil compounds of the spices. The pulverizing methods and storage significantly affected the compositions of the fatty acid in the peppers, except for palmitic acid and lignoceric acid. The amino acid contents and the thermo-gravimetric analysis curve were hardly influenced by the grinding techniques. The use of cryogenic grinding to prepare pepper ensured the highest quality of pepper products. Regardless of grinding technique, the values of moisture, piperine, unsaturated fatty acids, essential oil, monoterpenes, and the absolute concentrations of typical pepper essential oil constituents (except caryophyllene oxide) decreased, whereas the amino acid, lipid, protein, starch, and non-volatile ether extract content as well as the thermal properties were insignificantly changed after storage at 4 °C for 6 months.

Investigating the Capability of IRS-P6-LISS IV Satellite Image for Pistachio Forests Density Mapping (case Study: Northeast of Iran)

NASA Astrophysics Data System (ADS)

Hoseini, F.; Darvishsefat, A. A.; Zargham, N.

2012-07-01

In order to investigate the capability of satellite images for Pistachio forests density mapping, IRS-P6-LISS IV data were analyzed in an area of 500 ha in Iran. After geometric correction, suitable training areas were determined based on fieldwork. Suitable spectral transformations like NDVI, PVI and PCA were performed. A ground truth map included of 34 plots (each plot 1 ha) were prepared. Hard and soft supervised classifications were performed with 5 density classes (0-5%, 5-10%, 10-15%, 15-20% and > 20%). Because of low separability of classes, some classes were merged and classifications were repeated with 3 classes. Finally, the highest overall accuracy and kappa coefficient of 70% and 0.44, respectively, were obtained with three classes (0-5%, 5-20%, and > 20%) by fuzzy classifier. Considering the low kappa value obtained, it could be concluded that the result of the classification was not desirable. Therefore, this approach is not appropriate for operational mapping of these valuable Pistachio forests.

Biting Force and Muscle Activity in Implant-Supported Single Mandibular Overdentures Opposing Fixed Maxillary Dentition.

PubMed

Al-Magaleh, Wafaʼa R; Abbas, Nadia A; Amer, Ashraf A; Abdelkader, Ann A; Bahgat, Basma

2016-04-01

This study aimed to investigate the relation between biting force and masticatory muscle activity in patients treated by 3 modalities of single mandibular dentures. Forty implants were placed in 10 patients with completely edentulous mandibles. The study was divided into 3 treatment stages. Initially, each patient received a conventional mandibular complete denture. At the second stage, 4 mandibular implants were placed and the denture was refitted to their abutments. Third stage comprised connecting the denture to the implants through ball attachments. During each treatment stage, maximum biting force and muscle activity were measured during maximum clenching and chewing of soft and hard food. Biting force demonstrated a statistically significant increase by time for the 3 treatment stages. The highest muscle activity was recorded for the conventional denture followed by the implant-supported overdenture without attachment, whereas the lowest values were recorded for the implant-supported overdenture with attachment. Biting force was related mainly to the quality of denture support. Muscle activity was higher in patients with conventional denture than with implant-supported prostheses (with or without attachments).

Annealing of Co-Cr dental alloy: effects on nanostructure and Rockwell hardness

PubMed Central

Soylu, Elif Hilal; İde, Semra; Kılıç, Selim; Sipahi, Cumhur; Pişkin, Bulent; Gökçe, Hasan Suat

2013-01-01

PURPOSE The aim of the study was to evaluate the effect of annealing on the nanostructure and hardness of Co-Cr metal ceramic samples that were fabricated with a direct metal laser sintering (DMLS) technique. MATERIALS AND METHODS Five groups of Co-Cr dental alloy samples were manufactured in a rectangular form measuring 4 × 2 × 2 mm. Samples fabricated by a conventional casting technique (Group I) and prefabricated milling blanks (Group II) were examined as conventional technique groups. The DMLS samples were randomly divided into three groups as not annealed (Group III), annealed in argon atmosphere (Group IV), or annealed in oxygen atmosphere (Group V). The nanostructure was examined with the small-angle X-ray scattering method. The Rockwell hardness test was used to measure the hardness changes in each group, and the means and standard deviations were statistically analyzed by one-way ANOVA for comparison of continuous variables and Tukey's HSD test was used for post hoc analysis. P values of <.05 were accepted as statistically significant. RESULTS The general nanostructures of the samples were composed of small spherical entities stacked atop one another in dendritic form. All groups also displayed different hardness values depending on the manufacturing technique. The annealing procedure and environment directly affected both the nanostructure and hardness of the Co-Cr alloy. Group III exhibited a non-homogeneous structure and increased hardness (48.16 ± 3.02 HRC) because the annealing process was incomplete and the inner stress was not relieved. Annealing in argon atmosphere of Group IV not only relieved the inner stresses but also decreased the hardness (27.40 ± 3.98 HRC). The results of fitting function presented that Group IV was the most homogeneous product as the minimum bilayer thickness was measured (7.11 Å). CONCLUSION After the manufacturing with DMLS technique, annealing in argon atmosphere is an essential process for Co-Cr metal ceramic substructures. The dentists should be familiar with the materials that are used in clinic for prosthodontics treatments. PMID:24353888

Microstructural optimization of solid-state sintered silicon carbide

NASA Astrophysics Data System (ADS)

Vargas-Gonzalez, Lionel R.

Silicon carbide armor, manufactured through solid-state sintering, liquid-phase sintering, and hot-pressing, is being used by the United States Armed Forces for personal and vehicle protection. There is a lack of consensus, however, on which process results in the best-performing ballistic armor. Previous studies have shown that hot-pressed ceramics processed with secondary oxide and/or rare earth oxides, which exhibit high fracture toughness, perform well in handling and under ballistic impact. This high toughness is due to the intergranular nature of the fracture, creating a tortuous path for cracks and facilitating crack deflection and bridging. However, it has also been shown that higher-hardness sintered SiC materials might perform similarly or better to hot-pressed armor, in spite of the large fracture toughness deficit, if the microstructure (density, grain size, purity) of these materials are improved. In this work, the development of theoretically-dense, clean grain boundary, high hardness solid-state sintered silicon carbide (SiC) armor was pursued. Boron carbide and graphite (added as phenolic resin to ensure the carbon is finely dispersed throughout the microstructure) were used as the sintering aids. SiC batches between 0.25--4.00 wt.% carbon were mixed and spray dried. Cylindrical pellets were pressed at 13.7 MPa, cold-isostatically pressed (CIP) at 344 MPa, sintered under varying sintering soaking temperatures and heating rates, and varying post hot-isostatic pressing (HIP) parameters. Carbon additive amounts between 2.0--2.5 wt.% (based on the resin source), a 0.36 wt.% B4C addition, and a 2050°C sintering soak yielded parts with high sintering densities (˜95.5--96.5%) and a fine, equiaxed microstructure (d50 = 2.525 mum). A slow ramp rate (10°C/min) prevented any occurrence of abnormal grain growth. Post-HIPing at 1900°C removed the remaining closed porosity to yield a theoretically-dense part (3.175 g/cm3, according to rule of mixtures). These parts exhibited higher density and finer microstructure than a commercially-available sintered SiC from Saint-Gobain (Hexoloy Enhanced, 3.153 g/cm3 and d50 = 4.837 mum). Due to the optimized microstructure, Verco SiC parts exhibited the highest Vickers (2628.30 +/- 44.13 kg/mm 2) and Knoop (2098.50 +/- 24.8 kg/mm2) hardness values of any SiC ceramic, and values equal to those of the "gold standard" hot-pressed boron carbide (PAD-B4C). While the fracture toughness of hot-pressed SiC materials (˜4.5 MPa m ) are almost double that of Verco SiC (2.4 MPa m ), Verco SiC is a better performing ballistic product, implying that the higher hardness of the theoretically-dense, clean-grain boundary, fine-grained SiC is the defining mechanical property for optimization of ballistic behavior.

Effect of the irradiance distribution from light curing units on the local micro-hardness of the surface of dental resins.

PubMed

Haenel, Thomas; Hausnerová, Berenika; Steinhaus, Johannes; Price, Richard B T; Sullivan, Braden; Moeginger, Bernhard

2015-02-01

An inhomogeneous irradiance distribution from a light-curing unit (LCU) can locally cause inhomogeneous curing with locally inadequately cured and/or over-cured areas causing e.g. monomer elution or internal shrinkage stresses, and thus reduce the lifetime of dental resin based composite (RBC) restorations. The aim of the study is to determine both the irradiance distribution of two light curing units (LCUs) and its influence on the local mechanical properties of a RBC. Specimens of Arabesk TOP OA2 were irradiated for 5, 20, and 80s using a Bluephase® 20i LCU in the Low mode (666mW/cm(2)), in the Turbo mode (2222mW/cm(2)) and a Celalux® 2 (1264mW/cm(2)). The degree of conversion (DC) was determined with an ATR-FTIR. The Knoop micro-hardness (average of five specimens) was measured on the specimen surface after 24h of dark and dry storage at room temperature. The irradiance distribution affected the hardness distribution across the surface of the specimens. The hardness distribution corresponded well to the inhomogeneous irradiance distributions of the LCU. The highest reaction rates occurred after approximately 2s light exposure. A DC of 40% was reached after 3.6 or 5.7s, depending on the LCU. The inhomogeneous hardness distribution was still evident after 80s of light exposure. The irradiance distribution from a LCU is reflected in the hardness distribution across the surface. Irradiance level of the LCU and light exposure time do not affect the pattern of the hardness distribution--only the hardness level. In areas of low irradiation this may result in inadequate resin polymerization, poor physical properties, and hence premature failure of the restorations as they are usually much smaller than the investigated specimens. It has to be stressed that inhomogeneous does not necessarily mean poor if in all areas of the restoration enough light intensity is introduced to achieve a high degree of cure. Copyright © 2014 Academy of Dental Materials. Published by Elsevier Ltd. All rights reserved.

Microhardness of dual-polymerizing resin cements and foundation composite resins for luting fiber-reinforced posts.

PubMed

Yoshida, Keiichi; Meng, Xiangfeng

2014-06-01

The optimal luting material for fiber-reinforced posts to ensure the longevity of foundation restorations remains undetermined. The purpose of this study was to evaluate the suitability of 3 dual-polymerizing resin cements and 2 dual-polymerizing foundation composite resins for luting fiber-reinforced posts by assessing their Knoop hardness number. Five specimens of dual-polymerizing resin cements (SA Cement Automix, G-Cem LincAce, and Panavia F2.0) and 5 specimens of dual-polymerizing foundation composite resins (Clearfil DC Core Plus and Unifil Core EM) were polymerized from the top by irradiation for 40 seconds. Knoop hardness numbers were measured at depths of 0.5, 2.0, 4.0, 6.0, 8.0, and 10.0 mm at 0.5 hours and 7 days after irradiation. Data were statistically analyzed by repeated measures ANOVA, 1-way ANOVA, and the Tukey compromise post hoc test (α=.05). At both times after irradiation, the 5 resins materials showed the highest Knoop hardness numbers at the 0.5-mm depth. At 7 days after irradiation, the Knoop hardness numbers of the resin materials did not differ significantly between the 8.0-mm and 10.0-mm depths (P>.05). For all materials, the Knoop hardness numbers at 7 days after irradiation were significantly higher than those at 0.5 hours after irradiation at all depths (P<.05). At 7 days after irradiation, the Knoop hardness numbers of the 5 resin materials were found to decrease in the following order: DC Core Plus, Unifil Core EM, Panavia F2.0, SA Cement Automix, and G-Cem LincAce (P<.05). The Knoop hardness number depends on the depth of the cavity, the length of time after irradiation, and the material brand. Although the Knoop hardness numbers of the 2 dual-polymerizing foundation composite resins were higher than those of the 3 dual-polymerizing resin cements, notable differences were seen among the 5 materials at all depths and at both times after irradiation. Copyright © 2014 Editorial Council for the Journal of Prosthetic Dentistry. Published by Elsevier Inc. All rights reserved.

Effect of Chicory Fiber and Smoking on Quality Characteristics of Restructured Sausages.

PubMed

Choi, Hyun-Su; Choi, Hyung-Gyu; Choi, Yeong-Seok; Kim, Jong-Hee; Lee, Ju-Ho; Jung, Eun-Hee; Lee, Sang-Hwa; Choi, Yang-Il; Choi, Jung-Seok

2016-01-01

This study was conducted to investigate the effects of chicory fiber for the replacement of fat and smoking on quality characteristics of restructured sausages. Treatments were as follows; Pork backfat 20%, T1: Pork backfat 10% + Chicory fiber 10%, T2: CONTROL + Smoking, T3: T1 + Smoking. The addition of chicory fiber significantly reduced the moisture, fat, hardness and pH values, whereas the smoking treatment increased the fat, redness and pH values of restructured sausages (p<0.01). Additionally, interaction of them significantly affected the ash, chewiness and hardness values of restructured sausages. As a result, although the addition of chicory fiber decreased the quality characteristics of sausage, smoking treatment improved the reduced quality. Therefore, the chicory fiber and smoking treatment is helpful to develop restructured sausage products with reduced fat and compensated quality.

Matrix Interdiction Problem

NASA Astrophysics Data System (ADS)

Kasiviswanathan, Shiva Prasad; Pan, Feng

In the matrix interdiction problem, a real-valued matrix and an integer k is given. The objective is to remove a set of k matrix columns that minimizes in the residual matrix the sum of the row values, where the value of a row is defined to be the largest entry in that row. This combinatorial problem is closely related to bipartite network interdiction problem that can be applied to minimize the probability that an adversary can successfully smuggle weapons. After introducing the matrix interdiction problem, we study the computational complexity of this problem. We show that the matrix interdiction problem is NP-hard and that there exists a constant γ such that it is even NP-hard to approximate this problem within an n γ additive factor. We also present an algorithm for this problem that achieves an (n - k) multiplicative approximation ratio.

Long-term outcomes of bone augmentation on soft and hard-tissue stability: a systematic review.

PubMed

Lutz, Rainer; Neukam, Friedrich W; Simion, Massimo; Schmitt, Christian M

2015-09-01

Peri-implant hard-tissue augmentation is a widely used clinical procedure. The present review aimed to analyse the current literature regarding medium- and long-term data concerning the stability of peri-implant tissues after hard-tissue augmentation prior or immediately with implant placement. An electronic literature search was performed using Medline (PubMed) databases detecting clinical studies focusing on hard- and soft-tissue stability around dental implants placed either in augmented alveolar ridges or simultaneously with peri-implant bone grafting. The search was limited to articles published between 1995 and December 2014, focusing on clinical studies with a prospective study design assessing peri-implant bone and soft tissue stability over time with a minimum follow-up of 12 months. Recent publications were also searched manually to find any relevant studies that might have been missed using the search criteria noted above. Thirty-seven articles met the inclusion criteria and were included in this systematic review. Since the outcome measures and methods, as well as types of grafts and implants used were so heterogeneous, the performance of meta-analysis was impossible. The highest level of evidence was achieved by randomized clinical trials. Different hard-tissue augmentation procedures seem to show stable peri-implant tissues, although, up to now, long-term stability of the augmented buccal bone is assessed by only few studies. Further research should concentrate on combining three-dimensional radiographic data with non-invasive methods as digital surface measuring techniques or ultrasound evaluation. © 2015 John Wiley & Sons A/S. Published by John Wiley & Sons Ltd.

Submicron cubic boron nitride as hard as diamond

DOE Office of Scientific and Technical Information (OSTI.GOV)

Liu, Guoduan; Kou, Zili, E-mail: kouzili@scu.edu.cn, E-mail: yanxz@hpstar.ac.cn; Lei, Li

Here, we report the sintering of aggregated submicron cubic boron nitride (sm-cBN) at a pressure of 8 GPa. The sintered cBN compacts exhibit hardness values comparable to that of single crystal diamond, fracture toughness about 5-fold that of cBN single crystal, in combination with a high oxidization temperature. Thus, another way has been demonstrated to improve the mechanical properties of cBN besides reducing the grain size to nano scale. In contrast to other ultrahard compacts with similar hardness, the sm-cBN aggregates are better placed for potential industrial application, as their relative low pressure manufacturing perhaps be easier and cheaper.

Hard X-ray Flux from Low-Mass Stars in the Cygnus OB2 Association

NASA Astrophysics Data System (ADS)

Caramazza, M.; Drake, J. J.; Micela, G.; Flaccomio, E.

2009-05-01

We investigate the X-ray emission in the 20-40 keV band expected from the flaring low-mass stellar population in Cygnus OB2 assuming that the observed soft X-ray emission is due to a superposition of flares and that the ratio of hard X-ray to soft X-ray emission is described by a scaling found for solar flares by Isola and co-workers. We estimate a low-mass stellar hard X-ray flux in the 20-40 keV band in the range ~7×1031-7×1033 erg/s and speculate the limit of this values. Hard X-ray emission could lie at a level not much below the current observed flux upper limits for Cygnus OB2. Simbol-X, with its broad energy band (10-100 keV) and its sensitivity should be able to detect this emission and would provide insights into the hard X-ray production of flares on pre-main sequence stars.

INFLUENCE OF THE FINAL TEMPERATURE OF INVESTMENT HEALTING ON THE TENSILE STRENGTH AND VICKERS HARDNESS OF CP TI AND TI-6AL-4V ALLOY

PubMed Central

Oliveira, Pedro César Garcia; Adabo, Gelson Luis; Ribeiro, Ricardo Faria; da Rocha, Sicknan Soares; Ávila, Fabiano Araújo; do Valle, Accácio Lins

2007-01-01

The aim of the work was to evaluate the influence of the temperature of investment healting on the tensile strength and Vickers hardness of CP Ti and Ti-6Al-4V alloy casting. Were obtained for the tensile strength test dumbbell rods that were invested in the Rematitan Plus investment and casting in the Discovery machine cast. Thirty specimens were obtained, fiftten to the CP Titanium and fifteen to the Ti-6Al-4V alloy, five samples to each an of the three temperatures of investment: 430°C (control group), 480°C and 530°C. The tensile test was measured by means of a universal testing machine, MTS model 810, at a strain of 1.0 mm/min. After the tensile strenght test the specimens were secctioned, embedded and polished to hardness measurements, using a Vickers tester, Micromet 2100. The means values to tensile tests to the temperatures 430°C, 480 and 530: CP Ti (486.1 – 501.16 – 498.14 –mean 495.30 MPa) and Ti-6Al-4V alloy (961.33 – 958.26 – 1005.80 – mean 975.13 MPa) while for the Vickers hardness the values were (198.06, 197.85, 202.58 – mean 199.50) and (352.95, 339.36, 344.76 – mean 345.69), respectively. The values were submitted to Analysis of Variance (ANOVA) and Tukey,s Test that indicate differences significant only between the materials, but not between the temperature, for both the materias. It was conclued that increase of the temperature of investment its not chance the tensile strength and the Vickers hardness of the CP Titanium and Ti-6Al-4V alloy. PMID:19089099

Dielectric properties, optimum formulation and microwave baking conditions of chickpea cakes.

PubMed

Alifakı, Yaşar Özlem; Şakıyan, Özge

2017-03-01

The aim of this study was to correlate dielectric properties with quality parameters, and to optimize cake formulation and baking conditions by response surface methodology. Weight loss, color, specific volume, hardness and porosity were evaluated. The samples with different DATEM (0.4, 0.8 and 1.2%) and chickpea flour concentrations (30, 40 and 50%) were baked in microwave oven at different power (300, 350, 400 W) and baking times (2.50, 3.0, 3.50 min). It was found that microwave power showed significant effect on color, while baking time showed effect on weight loss, porosity, hardness, specific volume and dielectric properties. Emulsifier level affected porosity, specific volume and dielectric constant. Chickpea flour level affected porosity, color, hardness and dielectric properties of cakes. The optimum microwave power, baking time, DATEM level and chickpea flour level were found as 400 W, 2.84 min, 1.2% and 30%, respectively. The comparison between conventionally baked and the microwave baked cakes at optimum points showed that color difference, weight loss, specific volume and porosity values of microwave baked cakes were less than those of conventionally baked cakes, on the other hand, hardness values were higher. Moreover, a negative correlation between dielectric constant and porosity, and weight loss values were detected for microwave baked samples. A negative correlation between dielectric loss factor and porosity was observed. These correlations indicated that quality characteristics of a microwave baked cake sample can be assessed from dielectric properties. These correlations provides understanding on the behavior of food material during microwave processing.