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Sample records for acid etching treatment

  1. Effects of fluoride treatment on phosphoric acid-etching in primary teeth: an AFM observation.

    PubMed

    Choi, Samjin; Rhee, Yeri; Park, Jeong-Hoon; Lee, Gi-Ja; Kim, Kyung-Sook; Park, Jae-Hong; Park, Young-Guk; Park, Hun-Kuk

    2010-07-01

    The aim of this study was to examine the effect of fluoride application on 37% phosphoric acid-etching by atomic force microscopy (AFM) in primary tooth samples based on a clinical protocol used in a pediatric dental hospital. Enamel samples were prepared from 36 exfoliated and non-carious primary teeth. Primary tooth samples were randomly assigned to one of the four groups based on the timing of acid-etching with 37% phosphoric acid after an acidulated phosphate fluoride (APF) pre-treatment. Group 1 received no fluoride application, Group 2 was pre-treated with fluoride and then received acid-etching 2 weeks later. One week separated the fluoride treatment and the acid-etching in Group 3, while Group 4 received acid-etching immediately after the fluoride treatment. The vestibular enamel surfaces of each primary tooth sample were scanned in air at a resolution of 512 x 512 pixels and a scan speed of 0.8 line/s. On the enamel surfaces of the primary teeth after APF pre-treatment, debris were observed although the teeth were smoother than they were prior to APF. As a result, it was concluded that APF treatment is responsible for decreased primary tooth surface roughness. The enamel surfaces etched for 20s showed that acid-etching was effective not only in removing scratches and debris, but also for evaluating enamel rod characteristics. Primary tooth enamel surfaces after etching showed minute structures caused by the decreased hydroxyapatite nanoparticle space, compared to those before etching. Also, acid-etching showed significantly increased roughness effects (p<0.0001, n=9). Finally, as more time elapsed after APF pre-treatment, the roughness was decreased to a lesser degree (p=0.005, n=9). We suggest that primary teeth etching 2 weeks after APF pre-treatment used clinically in pediatric hospitals may be effective to obtain properly etched enamel surfaces.

  2. Investigations of AlGaN/GaN HFETs utilizing post-metallization etching by nitric acid treatment

    NASA Astrophysics Data System (ADS)

    Chou, Bo-Yi; Hsu, Wei-Chou; Lee, Ching-Sung; Liu, Han-Yin; Tsai, Chih-Ming; Ho, Chiu-Sheng

    2013-07-01

    This work investigates AlGaN/GaN heterostructure field-effect transistors (HFETs) processed by using a simple post-metallization etching (PME) treatment. Decreased gate length (LG) can be achieved by using nitric acid (HNO3) PME treatment owing to the high etching selectivity of HNO3 of Ni against the Au and GaN layer. Influences on LG, etched gate profiles and device characteristics with respect to different PME processing parameters by HNO3 treatment are systematically investigated. Optimum device performance is obtained as LG was reduced to 0.5 µm by using a 1 µm long gate mask by immersing the device into a 45% diluted HNO3 solution for 35 s. Improved device performances, including maximum drain-source current density (IDS, max: 657.6 mA mm-1 → 898.5 mA mm-1), drain-source saturation current density at zero gate bias (IDSS0: 448.3 mA mm-1 → 653.4 mA mm-1), maximum extrinsic transconductance (gm, max: 158.3 mS mm-1 → 219.2 mS mm-1), unity-gain cut-off frequency (fT: 12.35 GHz → 22.05 GHz), maximum oscillation frequency (fmax: 17.55 GHz → 29.4 GHz) and power-added efficiency (P.A.E.: 26.3% → 34.5%) compared to the untreated reference device, have been successfully achieved.

  3. From acid etching treatments to tribocorrosive properties of dental implants: do some experimental results on surface treatments have an influence on the tribocorrosion behaviour of dental implants?

    NASA Astrophysics Data System (ADS)

    Geringer, Jean; Demanget, Nicolas; Pellier, Julie

    2013-10-01

    Surface treatments of dental implants aim at promoting osseointegration, i.e. the anchorage of the metallic part. Titanium-, grade II-V, based material is used as a bulk material for dental implants. For promoting the anchorage of this metallic biomaterial in human jaw, some strategies have been applied for improving the surface state, i.e. roughness, topography and coatings. A case study, experimental study, is described with the method of acid etching on titanium grade 4, CpTi. The main goal is to find the right proportion in a mixture of two acids in order to obtain the best surface state. Finally, a pure theoretical prediction is quite impossible and some experimental investigations are necessary to improve the surface state. The described acid etching is compared with some other acid etching treatments and some coatings available on dental implants. Thus, the discussion is focused on the tribocorrosion behaviour of titanium-based materials. The purpose of the coating is that the lifetime under tribocorrosion is limited. Moreover, the surgery related to the implantation has a huge impact on the stability of dental implants. Thus, the performance of dental implants depends on factors related to surgery (implantation) that are difficult to predict from the biomaterial characteristics. From the tribocorrosion point of view, i.e. during the mastication step, the titanium material is submitted to some deleterious factors that cause the performance of dental implants to decrease.

  4. In vitro evaluation of microleakage under orthodontic brackets using two different laser etching, self etching and acid etching methods.

    PubMed

    Hamamci, Nihal; Akkurt, Atilim; Başaran, Güvenç

    2010-11-01

    This study evaluated the microleakage of brackets bonded by four different enamel etching techniques. Forty freshly extracted human premolars were divided randomly into four equal groups and received the following treatment: group 1, acid etching; group 2, self-etching primer (SEP); group 3, erbium:yttrium-aluminum-garnet (Er:YAG) laser etching; and group 4, erbium, chromium:yttrium-scandium-gallium-garnet (Er,Cr:YSGG) laser etching. After photopolymerization, the teeth were kept in distilled water for 1 month and then subjected to 500 thermal cycles. Then, the specimens were sealed with nail varnish, stained with 0.5% basic fuchsin for 24 h, sectioned, and examined under a stereomicroscope. In addition, they were scored for marginal microleakage at the adhesive-enamel and bracket-adhesive interfaces from the incisal and gingival margins. Statistical analyses consisted of the Kruskal-Wallis test and the Mann-Whitney U test with Bonferroni correction. Microleakage occurred between the adhesive-enamel and bracket-adhesive interfaces in all groups. For the adhesive-enamel surface, a significant difference was observed between group 1 and groups 2 (P = 0.011), 3 (P = 0.002), and 4 (P = 0.000) on the gingival side. Overall, significant differences were observed between group 1 and groups 3 (P = 0.003) and 4 (P = 0.000). In dental bonding procedures, acid etching was found to result in the least microleakage. Since etching with a laser decreases the risk of caries and is time-saving, it may serve as an alternative to acid etching.

  5. A comparative study of shear bond strength of orthodontic bracket after acid-etched and Er:YAG treatment on enamel surface

    NASA Astrophysics Data System (ADS)

    Leão, Juliana C.; Mota, Cláudia C. B. O.; Cassimiro-silva, Patricia F.; Gomes, Anderson S. L.

    2016-02-01

    This study aimed to evaluate the shear bond strength (SBS) of teeth prepared for orthodontic bracket bonding with 37% phosphoric acid and Er:YAG laser. Forty bovine incisors were divided into two groups. In Group I, the teeth were conditioned with 37% phosphoric acid and brackets were bonded with Transbond XT; in Group II, the teeth were irradiated with Er:YAG and bonding with Transbond XT. After SBS test, the adhesive remnant index was determined. Adhesion to dental hard tissues after Er:YAG laser etching was inferior to that obtained after acid etching but exceeded what is believed to be clinically sufficient strength, and therefore can be used in patients.

  6. Effect of Hydrofluoric Acid Etching Time on Titanium Topography, Chemistry, Wettability, and Cell Adhesion

    PubMed Central

    Zahran, R.; Rosales Leal, J. I.; Rodríguez Valverde, M. A.; Cabrerizo Vílchez, M. A.

    2016-01-01

    Titanium implant surface etching has proven an effective method to enhance cell attachment. Despite the frequent use of hydrofluoric (HF) acid, many questions remain unresolved, including the optimal etching time and its effect on surface and biological properties. The objective of this study was to investigate the effect of HF acid etching time on Ti topography, surface chemistry, wettability, and cell adhesion. These data are useful to design improved acid treatment and obtain an improved cell response. The surface topography, chemistry, dynamic wetting, and cell adhesiveness of polished Ti surfaces were evaluated after treatment with HF acid solution for 0, 2; 3, 5, 7, or 10 min, revealing a time-dependent effect of HF acid on their topography, chemistry, and wetting. Roughness and wetting increased with longer etching time except at 10 min, when roughness increased but wetness decreased. Skewness became negative after etching and kurtosis tended to 3 with longer etching time. Highest cell adhesion was achieved after 5–7 min of etching time. Wetting and cell adhesion were reduced on the highly rough surfaces obtained after 10-min etching time. PMID:27824875

  7. Comparison of Self-Etch Primers with Conventional Acid Etching System on Orthodontic Brackets

    PubMed Central

    Zope, Amit; Zope-Khalekar, Yogita; Chitko, Shrikant S.; Kerudi, Veerendra V.; Patil, Harshal Ashok; Jaltare, Pratik; Dolas, Siddhesh G

    2016-01-01

    Introduction The self-etching primer system consists of etchant and primer dispersed in a single unit. The etching and priming are merged as a single step leading to fewer stages in bonding procedure and reduction in the number of steps that also reduces the chance of introduction of error, resulting in saving time for the clinician. It also results in smaller extent of enamel decalcification. Aim To compare the Shear Bond Strength (SBS) of orthodontic bracket bonded with Self-Etch Primers (SEP) and conventional acid etching system and to study the surface appearance of teeth after debonding; etching with conventional acid etch and self-etch priming, using stereomicroscope. Materials and Methods Five Groups (n=20) were created randomly from a total of 100 extracted premolars. In a control Group A, etching of enamel was done with 37% phosphoric acid and bonding of stainless steel brackets with Transbond XT (3M Unitek, Monrovia, California). Enamel conditioning in left over four Groups was done with self-etching primers and adhesives as follows: Group B-Transbond Plus (3M Unitek), Group C Xeno V+ (Dentsply), Group D-G-Bond (GC), Group E-One-Coat (Coltene). The Adhesive Remnant Index (ARI) score was also evaluated. Additionally, the surface roughness using profilometer were observed. Results Mean SBS of Group A was 18.26±7.5MPa, Group B was 10.93±4.02MPa, Group C was 6.88±2.91MPa while of Group D was 7.78±4.13MPa and Group E was 10.39±5.22MPa respectively. In conventional group ARI scores shows that over half of the adhesive was remaining on the surface of tooth (score 1 to 3). In self-etching primer groups ARI scores show that there was no or minor amount of adhesive remaining on the surface of tooth (score 4 and 5). SEP produces a lesser surface roughness on the enamel than conventional etching. However, statistical analysis shows significant correlation (p<0.001) of bond strength with surface roughness of enamel. Conclusion All groups might show clinically

  8. In Vitro Evaluation of Microleakage Around Orthodontic Brackets Using Laser Etching and Acid Etching Methods

    PubMed Central

    Toodehzaeim, Mohammad Hossein; Yassaei, Sogra; Karandish, Maryam; Farzaneh, Sedigeh

    2014-01-01

    Objective: path of microleakage between the enamel and adhesive potentially allows microbial ingress that may consequently cause enamel decalcification. The aim of this study was to compare microleakage of brackets bonded either by laser or acid etching techniques. Materials and Method: The specimens were 33 extracted premolars that were divided into three groups as the acid etching group (group 1), laser etching with Er:YAG at 100 mJ and 15 Hz for 15s (group 2), and laser etching with Er:YAG at 140 mJ and 15 Hz for 15s (group 3). After photo polymerization, the teeth were subjected to 500 thermal cycles. Then the specimens were sealed with nail varnish, stained with 2% methylen blue for 24hs, sectioned, and examined under a stereomicroscope. They were scored for marginal microleakage that occurred between the adhesive-enamel and bracket-adhesive interfaces from the occlusal and gingival margins. Data were analyzed with the Kruskal- Wallis test. Results: For the adhesive-enamel and bracket-adhesive surfaces, significant differences were not observed between the three groups. Conclusion: According to this study, the Er:YAG laser with 1.5 and 2.1 watt settings may be used as an adjunctive for preparing the surface for orthodontic bracket bonding. PMID:25628661

  9. Comparative Evaluation of the Etching Pattern of Er,Cr:YSGG & Acid Etching on Extracted Human Teeth-An ESEM Analysis

    PubMed Central

    Mazumdar, Dibyendu; Ranjan, Shashi; Krishna, Naveen Kumar; Kole, Ravindra; Singh, Priyankar; Lakiang, Deirimika; Jayam, Chiranjeevi

    2016-01-01

    Introduction Etching of enamel and dentin surfaces increases the surface area of the substrate for better bonding of the tooth colored restorative materials. Acid etching is the most commonly used method. Recently, hard tissue lasers have been used for this purpose. Aim The aim of the present study was to evaluate and compare the etching pattern of Er,Cr:YSGG and conventional etching on extracted human enamel and dentin specimens. Materials and Methods Total 40 extracted non-diseased teeth were selected, 20 anterior and 20 posterior teeth each for enamel and dentin specimens respectively. The sectioned samples were polished by 400 grit Silicon Carbide (SiC) paper to a thickness of 1.0 ± 0.5 mm. The enamel and dentin specimens were grouped as: GrE1 & GrD1 as control specimens, GrE2 & GrD2 were acid etched and GrE3 & GrD3 were lased. Acid etching was done using Conditioner 36 (37 % phosphoric acid) according to manufacturer instructions. Laser etching was done using Er,Cr:YSGG (Erbium, Chromium : Ytrium Scandium Gallium Garnet) at power settings of 3W, air 70% and water 20%. After surface treatment with assigned agents the specimens were analyzed under ESEM (Environmental Scanning Electron Microscope) at X1000 and X5000 magnification. Results Chi Square and Student “t” statistical analysis was used to compare smear layer removal and etching patterns between GrE2-GrE3. GrD2 and GrD3 were compared for smear layer removal and diameter of dentinal tubule opening using the same statistical analysis. Chi-square test for removal of smear layer in any of the treated surfaces i.e., GrE2-E3 and GrD2-D3 did not differ significantly (p>0.05). While GrE2 showed predominantly type I etching pattern (Chi-square=2.78, 0.05

    0.10) and GrE3 showed type III etching (Chi-square=4.50, p<0.05). The tubule diameters were measured using GSA (Gesellschaft fur Softwareentwicklung und Analytik, Germany) image analyzer and the ‘t’ value of student ‘t’ test was 18.10 which was a

  10. Surface characterization of alkali- and heat-treated Ti with or without prior acid etching

    NASA Astrophysics Data System (ADS)

    An, Sang-Hyun; Matsumoto, Takuya; Miyajima, Hiroyuki; Sasaki, Jun-Ichi; Narayanan, Ramaswamy; Kim, Kyo-Han

    2012-03-01

    Titanium and its alloys are used as implant materials in dental and orthopaedic applications. The material affinities to host bone tissue greatly concern with the recovery period and good prognosis. To obtain a material surface having excellent affinity to bone, acid etching prior to alkali- and heat-treatment of Ti was conducted. The surface characteristics of the prepared sample indicated that the roughness as well as the wettability increased by pre-etching. Bone-like apatite was formed on pre-etched, alkali- and heat-treated Ti surface in simulated body fluid (SBF) within 3 days, while it takes 5 days on the solely alkali- and heat-treated surface. Osteoblastic cells showed better compatibility on the per-etched surface compared to the pure Ti surface or alkali- and heat-treated surface. Moreover, the pre-etched surface showed better pull-off tensile adhesion strength against the deposited apatite. Thus, acid etching prior to alkali- and heat-treatment would be a promising method for enhancing the affinity of Ti to host bone tissue.

  11. Effective diffraction gratings via acidic etching of thermally poled glass

    NASA Astrophysics Data System (ADS)

    Kamenskii, A. N.; Reduto, I. V.; Petrikov, V. D.; Lipovskii, A. A.

    2016-12-01

    Relief diffraction gratings are formed via acidic chemical etching of a periodically poled soda-lime glass. The thermal poling under 1000 V DC is performed at 325 °C using a thermally stable glassy-carbon anodic electrode with periodic grooves, the depth of the grooves being of ∼650 nm. Poling-induced modification of the glass results in deepening the glass anodic surface in the regions under the ribs of the anodic electrode due to volume relaxation and in increasing chemical durability of these regions in acidic media comparatively to the virgin glass. Chemical etching of the poled glass in NH4F:8H2O solution allows additional to the thermal poling shaping of the glass surface via faster dissolution of unpoled/less poled glass regions. The morphology of the glass surface before and after the etching is characterized with atomic force and scanning electron microscopy. About 30 min etching provides the formation of ∼0.9 μm in height relief diffraction gratings with the diffraction efficiency close to the theoretically achievable ∼30% for multi-order diffraction. In vivo measuring of the diffraction efficiency in the course of the etching allows precise fabrication of the gratings.

  12. BOND STRENGTH AND MORPHOLOGY OF ENAMEL USING SELF-ETCHING ADHESIVE SYSTEMS WITH DIFFERENT ACIDITIES

    PubMed Central

    Moura, Sandra Kiss; Reis, Alessandra; Pelizzaro, Arlete; Dal-Bianco, Karen; Loguercio, Alessandro Dourado; Arana-Chavez, Victor Elias; Grande, Rosa Helena Miranda

    2009-01-01

    Objectives: To assess the bond strength and the morphology of enamel after application of self-etching adhesive systems with different acidities. The tested hypothesis was that the performance of the self-etching adhesive systems does not vary for the studied parameters. Material and methods: Composite resin (Filtek Z250) buildups were bonded to untreated (prophylaxis) and treated (burcut or SiC-paper) enamel surfaces of third molars after application of four self-etching and two etch-and-rinse adhesive systems (n=6/condition): Clearfil SE Bond (CSE); OptiBond Solo Plus Self-Etch (OP); AdheSe (AD); Tyrian Self Priming Etching (TY), Adper Scotchbond Multi-Purpose Plus (SBMP) and Adper Single Bond (SB). After storage in water (24 h/37°C), the bonded specimens were sectioned into sticks with 0.8 mm2 cross-sectional area and the microtensile bond strength was tested at a crosshead speed of 0.5 mm/min. The mean bond strength values (MPa) were subjected to two-way ANOVA and Tukey's test (α=0.05). The etching patterns of the adhesive systems were also observed with a scanning electron microscope. Results: The main factor adhesive system was statistically significant (p<0.05). The mean bond strength values (MPa) and standard deviations were: CSE (20.5±3.5), OP (11.3±2.3), AD (11.2±2.8), TY (11.1±3.0), SBMP (21.9±4.0) and SB (24.9±3.0). Different etching patterns were observed for the self-etching primers depending on the enamel treatment and the pH of the adhesive system. Conclusion: Although there is a tendency towards using adhesive systems with simplified application procedures, this may compromise the bonding performance of some systems to enamel, even when the prismless enamel is removed. PMID:19668991

  13. Shear Bond Strength of an Etch-and-rinse Adhesive to Er:YAG Laser- and/or Phosphoric Acid-treated Dentin

    PubMed Central

    Davari, Abdolrahim; Sadeghi, Mostafa; Bakhshi, Hamid

    2013-01-01

    Background and aims. Er:YAG laser irradiation has been claimed to improve the adhesive properties of dentin; therefore, it has been proposed as an alternative to acid etching. The aim of this in vitro study was to investigate the shear bond strength of an etch-and-rinse adhesive system to dentin surfaces following Er:YAG laser and/or phosphoric acid etching. Materials and methods. The roots of 75 sound maxillary premolars were sectioned below the CEJ and the crowns were embedded in auto-polymerizing acrylic resin with the buccal surfaces facing up. The buccal surfaces were ground using a diamond bur and polished until the dentin was exposed; the samples were randomly divided into five groups (n=15) according to the surface treatment: (1) acid etching; (2) laser etching; (3) laser etching followed by acid etching; (4) acid etching followed by laser etching and (5) no acid etching and no laser etching (control group). Composite resin rods (Point 4, Kerr Co) were bonded to treated dentin surfaces with an etch-and-rise adhesive system (Optibond FL, Kerr Co) and light-cured.After storage for two weeks at 37°C and 100% humidity and then thermocycling, bond strength was measured with a Zwick Universal Testing Machine at a crosshead speed of 1 mm/min. Data was analyzed using parametric and non-parametric tests (P<0.05). Results. Mean shear bond strength for acid etching (20.1±1.8 MPa) and acid+laser (15.6±3.5 MPa) groups were significantly higher than those for laser+acid (15.6±3.5 MPa), laser etching (14.1±3.4 MPa) and control (8.1±2.1 MPa) groups. However, there were no significant differences between acid etching and acid+laser groups, and between laser+acid and laser groups. Conclusion. When the cavity is prepared by bur, it is not necessary to etch the dentin surface by Er:YAG laser following acid etching and acid etching after laser etching. PMID:23875083

  14. Temperature Rise Induced by Light Curing Unit Can Shorten Enamel Acid-Etching Time

    PubMed Central

    Najafi Abrandabadi, Ahmad; Sheikh-Al-Eslamian, Seyedeh Mahsa; Panahandeh, Narges

    2015-01-01

    Objectives: The aim of this in-vitro study was to assess the thermal effect of light emitting diode (LED) light curing unit on the enamel etching time. Materials and Methods: Three treatment groups with 15 enamel specimens each were used in this study: G1: Fifteen seconds of etching, G2: Five seconds of etching, G3: Five seconds of etching plus LED light irradiation (simultaneously). The micro shear bond strength (μSBS) of composite resin to enamel was measured. Results: The mean μSBS values ± standard deviation were 51.28±2.35, 40.47±2.75 and 50.00±2.59 MPa in groups 1, 2 and 3, respectively. There was a significant difference between groups 1 and 2 (P=0.013) and between groups 2 and 3 (P=0.032) in this respect, while there was no difference between groups 1 and 3 (P=0.932). Conclusion: Simultaneous application of phosphoric acid gel over enamel surface and light irradiation using a LED light curing unit decreased enamel etching time to five seconds without compromising the μSBS. PMID:27559352

  15. Comparative Evaluation of Tensile – Bond Strength of An Orthodontic Adhesive with and without Fluoride Application, After Acid Etching -An Invitro Study

    PubMed Central

    Yugandhar, G; Ramana, I Venkata; Srinivas, K; Yadav, S. Sarjeev Singh

    2015-01-01

    Background Fixed appliances hinder the effective control of plaque accumulation and white spot lesions may develop under the ill fitting bands or adjacent to the stainless steel brackets during orthodontic treatment particularly the etching process. Aims and Objectives Comparative study of tensile bond strength of an orthodontic adhesive with and without fluoride application after acid etching to know the effect of fluoride on bond strength. Materials and Methods This study is carried out on 90 non carious human premolar teeth, and divided in 6 groups with each group of 15 specimens. In those Groups I and IV were control group acid etch treatment, Group II and V is 1.23% APF gel (acid etch plus APF gel treatment,) and group III and VI is 8% SnF2 (acid etch plus SnF2 treatment). Samples of Group I, II and III bond strength were tested after 24 h and groups IV, V and VI after one month on microtechtensometer machine. The scanning electron microscope (SEM) investigation was carried out for the 2 specimens for the control group after acid etch and 4 specimens after acid etch with fluoride application for fluoride groups. Results Control and SnF2 treated groups was found to be nearly similar to the control group whereas APF treated group showed less focal holes than the other 2 groups. Conclusion Fluoride application after acid etching without having an adverse effect on bond strength but we can prevent the white spot lesions and caries. PMID:26023648

  16. Oxidation and etching behaviors of the InAs surface in various acidic and basic chemical solutions

    NASA Astrophysics Data System (ADS)

    Na, Jihoon; Lee, Seunghyo; Lim, Sangwoo

    2017-04-01

    Indium arsenide (InAs) is the candidate of choice as a new channel material for application in future technologies beyond the Si-based electronic devices because it has a much higher electron mobility than silicon. In this study, the oxidation and etching behaviors of InAs (100) in various acidic and basic solutions, such as HF, HCl, H2SO4, NaOH, KOH, and NH4OH, were investigated. In addition, the effect of pH on the oxidation and etching reactions taking place on the InAs surface was studied using solutions with a pH ranging from 1 to 13. It was observed that the oxidation of the InAs surface was hindered in acidic solutions, which was attributed to the dissolution of the oxidized surface layer. In particular, the treatment of the InAs surface using a strongly acidic solution with a pH of less than 3 produced an oxide-free surface due to the predominant etching of the InAs surface. The addition of H2O2 to the acidic solutions greatly increased the etching rate of the InAs surface, which suggests that the oxidation process is the rate-limiting step in the sequence of reactions that occur during the etching of the InAs surface in acidic solutions. The etching of InAs was suppressed in neutral solutions, which resulted in the formation of a relatively thicker oxide layer on the surface, and mild etching of the InAs surface took place in basic solutions. However, in basic solutions, the addition of H2O2 did not significantly contribute to the increase of the oxidation state of the InAs surface; thus, its effect on the etching rate of InAs was smaller than in acidic solutions.

  17. In vitro short-term bonding performance of zirconia treated with hot acid etching and primer conditioning etching and primer conditioning.

    PubMed

    Xie, Haifeng; Chen, Chen; Dai, Wenyong; Chen, Gang; Zhang, Feimin

    2013-01-01

    This study aimed to investigate and compare the resin bond strengths of zirconia conditioned as follows: alumina sandblasting; alumina sandblasting+application of 10-MDP-containing primer; alumina sandblasting+application of Z-Prime Plus or Metal/Zirconia Primer (new zirconia primers); tribochemical silica coating+silanization; hot acid etching in three different combinations [H2SO4/(NH4)2SO4, HF/HNO3, H2SO4/HF/HNO3]+application of 10-MDP-containing primer. Shear bond strengths (SBS) after water storage for 24 h and 40 days were measured to assess resin bonding performance. Surface and chemical properties of conditioned zirconia surfaces and primers were characterized using scanning electron microscopy, energy dispersive X-ray spectrometry, Fourier transform infrared spectroscopy, and atomic force microscopy. Surface roughness ranked in descending order was: hot acid etching > tribochemical silica coating > alumina sandblasting. Combination of tribochemical silica coating and silanization showed the highest initial SBS (12.46±2.13 MPa) (P<0.01). Etching with H2SO4/(NH4)2SO4 (13.15±3.24 MPa) and HF/HNO3 (13.48±2.15 MPa) showed significantly better bond durability (P<0.01). Hot acid etching seemed to be a promising surface roughening treatment to improve resin-zirconia bonding.

  18. Effect of acid-etching on remineralization of enamel white spot lesions.

    PubMed

    Al-Khateeb, S; Exterkate, R; Angmar-Månsson, B; ten Cate, J M; ten Cate, B

    2000-02-01

    This in vitro study aimed at investigating whether full remineralization would occur in white spot lesions when the surface porosity was increased by acid-etching. The effect of fluoride was also investigated. Enamel blocks with in vitro produced white spot lesions were used. Group A was exposed to a remineralizing solution only. In group B, the lesions were etched with 35% phosphoric acid for 30 s, then treated as in group A. Group C was treated as group A + daily treatment with a fluoride toothpaste slurry (1,000 ppm) for 5 min. Group D was treated as group B + the daily fluoride treatment of group C. The remineralization was measured weekly with Quantitative Light-induced Fluorescence during the experimental period. After 10 weeks of remineralization, mineral profiles were assessed with transverse microradiography. The enamel fluorescence was partly regained. There were significant differences in the lesion depth, mineral content at the surface layer, and integrated mineral loss between the groups. Addition of fluoride accelerated the remineralization only in the beginning; in later stages the process leveled out and even reached a plateau in all the groups. It was concluded that full remineralization was not achieved by etching, by the addition of fluoride, nor by the combination of both treatments in this in vitro study.

  19. An analysis of the shear strength of the bond between enamel and porcelain laminate veneers with different etching systems: acid and Er,Cr:YSGG laser separately and combined.

    PubMed

    Dundar, Berivan; Guzel, Kahraman Gündüz

    2011-11-01

    Conditioning of the enamel surface is now an accepted and widely applied technique used to improve retention in porcelain laminate veneer restorations. The aim of this study was to evaluate strength of the bond between porcelain laminate veneers and tooth surfaces etched with acid and laser, separately and together. The teeth studied comprised 60 incisors extracted for periodontal reasons. These were divided into four groups according to etching method: group 1, acid etching alone; group 2, acid etching followed by laser etching; group 3, laser etching followed by acid etching; group 4, laser etching alone. The teeth were etched with 37% phosphoric acid and a Er,Cr:YSGG laser system. In addition, 60 IPS Empress II cylindrical blocks 2 mm in height and 5 mm in diameter were also prepared for the etched tooth surface. These blocks were bonded to the teeth with dual cured resin cement and shear tests were then performed. After the shear tests, Scanning electron microscopy images of the tooth surfaces were obtained at a magnification of ×3,800. Etching with acid alone yielded the highest mean value of bond shear strength (15.4±3.8 MPa), while laser etching followed by acid etching gave the lowest mean value (11.5±4.6 MPa). The mean values of the bond shear strength for acid etching followed by laser etching and laser etching alone were 13.8±3.9 MPa and 12.8±4.6 MPa, respectively. Statistical analysis revealed no significant differences between the groups. The results suggest that laser etching is easy to apply and less time-consuming. They further suggest that the order in which the acid and laser are applied in combined treatments is important.

  20. Shear bond strength and debonding characteristics of metal and ceramic brackets bonded with conventional acid-etch and self-etch primer systems: An in-vivo study

    PubMed Central

    Mirzakouchaki, Behnam; Sharghi, Reza; Shirazi, Samaneh; Moghimi, Mahsan; Shahrbaf, Shirin

    2016-01-01

    Background Different in-vitro studies have reported various results regarding shear bond strength (SBS) of orthodontic brackets when SEP technique is compared to conventional system. This in-vivo study was designed to compare the effect of conventional acid-etching and self-etching primer adhesive (SEP) systems on SBS and debonding characteristics of metal and ceramic orthodontic brackets. Material and Methods 120 intact first maxillary and mandibular premolars of 30 orthodontic patients were selected and bonded with metal and ceramic brackets using conventional acid-etch or self-etch primer system. The bonded brackets were incorporated into the wire during the study period to simulate the real orthodontic treatment condition. The teeth were extracted and debonded after 30 days. The SBS, debonding characteristics and adhesive remnant indices (ARI) were determined in all groups. Results The mean SBS of metal brackets was 10.63±1.42 MPa in conventional and 9.38±1.53 MPa in SEP system, (P=0.004). No statistically significant difference was noted between conventional and SEP systems in ceramic brackets. The frequency of 1, 2 and 3 ARI scores and debonding within the adhesive were the most common among all groups. No statistically significant difference was observed regarding ARI or failure mode of debonded specimens in different brackets or bonding systems. Conclusions The SBS of metal brackets bonded using conventional system was significantly higher than SEP system, although the SBS of SEP system was clinically acceptable. No significant difference was found between conventional and SEP systems used with ceramic brackets. Total SBS of metal brackets was significantly higher than ceramic brackets. Due to adequate SBS of SEP system in bonding the metal brackets, it can be used as an alternative for conventional system. Key words:Shear bond strength, Orthodontic brackets, Adhesive remnant index, self-etch. PMID:26855704

  1. Influence of previous acid etching on bond strength of universal adhesives to enamel and dentin.

    PubMed

    Torres, Carlos Rocha Gomes; Zanatta, Rayssa Ferreira; Silva, Tatiane Josefa; Huhtala, Maria Filomena Rocha Lima; Borges, Alessandra Bühler

    2017-01-01

    The objective of this study was to evaluate the effect of acid pretreatment on the bond strength of composite resin bonded to enamel and dentin with 2 different universal self-etching adhesives. The null hypothesis was that the acid treatment performed prior to adhesive application would not significantly change the bond strength to enamel or dentin for either universal adhesive tested. A sample of 112 bovine incisors were selected and embedded in acrylic resin. Half were ground until a flat enamel surface was obtained, and the other half were polished until a 6 × 6-mm area of dentin was exposed, resulting into 2 groups (n = 56). The enamel and dentin groups were divided into 2 subgroups according to the adhesive system applied: Futurabond U or Scotchbond Universal. Each of these subgroups was divided into 2 additional subgroups (n = 14); 1 subgroup received phosphoric acid pretreatment, and 1 subgroup did not. The bond strength was assessed with a microtensile test. Data from enamel and dentin specimens were analyzed separately using 1-way analysis of variance. The acid pretreatment did not significantly change the bond strength of the adhesives tested, either to enamel (P = 0.4161) or to dentin (P = 0.4857). The acid etching pretreatment did not affect the bond strength to dentin and enamel when the tested universal multipurpose adhesive systems were used.

  2. Effect of Acid Etching, Silane and Thermal Cycling on the Bond Strength of Metallic Brackets to Ceramic.

    PubMed

    Matos, Natália Regina Santos de; Costa, Ana Rosa; Valdrighi, Heloísa Cristina; Correr, Américo Bortolazzo; Vedovello, Silvia Amélia; Santamaria, Milton; Correr-Sobrinho, Lourenço

    2016-01-01

    The aim of this study was to evaluate the effect of silanes, thermal cycling and acid etching on the shear bond strength (SBS) of metallic brackets to feldspathic ceramic. Feldspathic ceramic cylinders (Groups 1, 2, 5 and 6) were etched for 60 s with 10% hydrofluoric acid and Groups 3, 4, 7 and 8, without acid etching. Two layers of silane Clearfil Ceramic Primer (CCP, Groups 1 to 4) and two layers of RelyX Ceramic Primer (RCP, groups 5 to 8) were applied and dried for 60 s. Brackets were bonded to the cylinders with Transbond XT and light-activated for 40 s with Bluephase G2. All specimens were stored in deionized water at 37 °C for 24 h, and the specimens of groups 1, 3, 5 and 7 were submitted to 7,000 thermal cycles (5 °C/55 °C). After storage, the SBS test was performed at a crosshead speed of 1 mm/min. Data were subjected to three-way ANOVA and Tukey's post hoc test (α=0.05). The adhesive remnant index (ARI) was evaluated at 8x magnification. The SBS of CCP was significantly greater than of RCP (p<0.05), with or without thermal cycling. Thermal cycling significantly reduced the SBS (p<0.05). The groups submitted to acid etching showed significantly higher SBS than those without acid etching (p<0.05). In conclusion, thermal cycling reduced SBS for all groups. The best ceramic surface treatment for bracket bonding was achieved by acid etching and CCP silane. The ARI results showed predominance of score 0 for all groups.

  3. Wetting ability of an acetone/based etch&rinse adhesive after NaOCl-treatment

    PubMed Central

    Aguilera, Fátima S.; Osorio, Raquel; Osorio, Estrella; Moura, Pedro

    2012-01-01

    Objectives: to evaluate the effect of sodium hypochlorite (NaOCl) treatment on surface dentin roughness (Ra) and contact angle (CA) when using Prime&Bond NT adhesive (PB NT). Study Design: Extracted human third molars were sectioned to expose flat, superficial and deep dentin surfaces. CA and Ra were measured (1) before and (2) after 35% H3PO4 etching, and (3) H3PO4 etching + 5% NaOCl treated for 2 minutes before the application of PB NT. CA was measured by the Axisymmetric Drop Shape Analysis Technique using distilled and deionized water and PB NT. Roughness was evaluated with a profilometer, twelve radial measurements were performed in each treatment surface. Data were analyzed with two-way ANOVA and Newman-Keuls multiple comparison test procedures. Results: CA values decreased after acid etching and even more after NaOCl treatment on deep dentin when water was tested. With resin, there were not differences on CA results after H3PO4 neither after NaOCl treatment, in both dentin surfaces. Etching and NaOCl treatment resulted in surface roughness increase. Conclusions: In spite of the higher roughness after NaOCl treatment on superficial and deep dentin, the use of 5% NaOCl for 2 min after dentin demineralization when PB NT was employed did not improved the wettability of dentin, probably due to nanofiller content and/or hydrogen-bonding interactions with residues of the organic matrix on collagen-depleted dentin. Key words:Sodium hypochlorite, contact angle, roughness, Prime&Bond NT, superficial dentin, deep dentin. PMID:22322490

  4. Rolled-Up Nanotech: Illumination-Controlled Hydrofluoric Acid Etching of AlAs Sacrificial Layers

    NASA Astrophysics Data System (ADS)

    Costescu, Ruxandra M.; Deneke, Christoph; Thurmer, Dominic J.; Schmidt, Oliver G.

    2009-12-01

    The effect of illumination on the hydrofluoric acid etching of AlAs sacrificial layers with systematically varied thicknesses in order to release and roll up InGaAs/GaAs bilayers was studied. For thicknesses of AlAs below 10 nm, there were two etching regimes for the area under illumination: one at low illumination intensities, in which the etching and releasing proceeds as expected and one at higher intensities in which the etching and any releasing are completely suppressed. The “etch suppression” area is well defined by the illumination spot, a feature that can be used to create heterogeneously etched regions with a high degree of control, shown here on patterned samples. Together with the studied self-limitation effect, the technique offers a way to determine the position of rolled-up micro- and nanotubes independently from the predefined lithographic pattern.

  5. Bonding durability of single-step adhesives to previously acid-etched dentin.

    PubMed

    Ikeda, Masahiko; Tsubota, Keishi; Takamizawa, Toshiki; Yoshida, Takeshi; Miyazaki, Masashi; Platt, Jeffrey A

    2008-01-01

    This study investigated the effect of phosphoric acid etching on the dentin bond strength of five single-step self-etch adhesive systems; Absolute, Clearfil tri-S Bond, Fluoro Bond Shake One, G-Bond and One-Up Bond F Plus. Bovine mandibular incisors were mounted in self-curing resin and the facial surfaces were wet ground with #600 SiC paper. Adhesives were applied on the prepared dentin surfaces with and without prior phosphoric acid etching and light irradiated. Resin composite was condensed into a mold (ø4x2 mm), light irradiated and stored in water at 37 degrees C. Four groups (n=10) were made per adhesive system: with and without prior acid etching and with and without thermal cycling between 5 degrees C and 55 degrees C for 10,000 cycles. The specimens were tested in a shear mode at a crosshead speed of 1.0 mm/minute. Two-way ANOVA, Student t-test and Tukey HSD test at a level of 0.05 were done. For specimens without prior acid etching, the mean bond strengths to bovine dentin ranged from 12.8 to 17.1 MPa and ranged from 6.7 to 13.3 MPa for specimens with prior acid etching after 24 hours storage in water. When the specimens were subjected to thermal cycling, the mean bond strengths ranged from 10.7 to 24.8 MPa for the specimens without prior acid etching and 4.6 to 13.9 MPa for the specimens with prior acid etching. The changes in dentin bond strength were different among the adhesive systems tested. Failure modes were commonly adhesive failure associated with mixed failure for specimens with prior acid etching. For specimens without prior acid etching, failures in composite and dentin were increased. From the results of this in vitro study, prior acid etching might be not acceptable for increasing the dentin bond strengths of single-step self-etch adhesive systems.

  6. Resin Adaptation of Radicular Dentin Tubules after Endodontic Instrumentation and Acid Etching.

    DTIC Science & Technology

    1983-02-01

    the manuscript. DISCLAIMERS The statements, opinions, and advertisements in the Journal of Endodontics are solely those of the individual authors...I RD-Ai26 872 RESIN ADAPTATION OF RADICULAR DENTIN TUBULES AFTER / I ENDODONTIC INSTRUMENTATION AND ACID ETCHING(U) WALTER I REED ARMY INST OF...Adaptation to Radicular Dentin Tubules SbisoofpeAfter Endodontic Instrumentation and Acid Etching 1982-1983 6. PERFORMING ORG. REPORTNUMBER -, AUTHOR(a) S

  7. Effect of prior acid etching on bonding durability of single-step adhesives.

    PubMed

    Watanabe, Takayuki; Tsubota, Keishi; Takamizawa, Toshiki; Kurokawa, Hiroyasu; Rikuta, Akitomo; Ando, Susumu; Miyazaki, Masashi

    2008-01-01

    This study investigated the effect of prior phosphoric acid etching on the enamel bond strength of five single-step self-etch adhesive systems: Absolute, Clearfil tri-S Bond, Fluoro Bond Shake One, G-Bond and One-Up Bond F Plus. Bovine mandibular incisors were mounted in self-curing resin, and the facial surfaces were wet ground with #600 silicon carbide paper. Adhesives were applied to the enamel surfaces with or without prior phosphoric-acid etching and light irradiated. The resin composites were condensed into a mold and light irradiated. In total, 40 specimens were tested per adhesive system with and without prior acid etching and were further divided into two groups: those stored in water at 37 degrees C for 24 hours without cycling and those stored in water at 37 degrees C for 24 hours followed by thermal cycling between 5 degrees C and 55 degrees C with 10,000 repeats. After storage under each set of conditions, the specimens were tested in shear mode at a crosshead speed of 1.0 mm/minute. Two-way analysis of variance, the Student's t-test and the Tukey HSD test were used to analyze the data at a significance level of 0.05. For the specimens without prior acid etching, the mean bond strengths to enamel ranged from 11.0 to 14.6 MPa after 24-hour storage in water, while the corresponding values for specimens with prior acid etching ranged from 15.2 to 19.3 MPa. When these specimens were subjected to thermal cycling, the mean bond strengths ranged from 11.3 to 17.0 MPa without prior acid etching and from 12.3 to 23.2 MPa with prior acid etching. The changes in enamel bond strengths differed among the adhesive systems tested. After 24-hour storage in water, the most common failure modes were adhesive failure and mixed failure for specimens with and without prior acid etching, respectively. Thus, through a careful choice of adhesive system, prior acid etching can increase the bond strengths of single-step self-etch adhesive systems.

  8. Effect of Lactic Acid Etching on Bonding Effectiveness of Orthodontic Bracket after Water Storage

    PubMed Central

    Alsulaimani, Fahad F.

    2014-01-01

    Objective. To determine the effect of lactic acid at various concentrations on the shear bond strength of orthodontic brackets bonded with the resin adhesive system before and after water storage. Materials and Methods. Hundred extracted human premolars were divided into 5 treatment groups and etched for 30 seconds with one of the following agents: lactic acid solution with (A) 10%, (B) 20%, (C) 30%, and (D) 50%; group E, 37% phosphoric acid (control). Metal brackets were bonded using a Transbond XT. Bonding effectiveness was assessed by shear bond strength after 24 hours and 6 months of water storage at 37°C. The data were analyzed with 2-way analysis of variance and Tukey's Honestly Significant Difference (HSD) test (α = .001). Results. Lactic acid concentration and water storage resulted in significant differences for brackets bond strength (P < .001). 20% lactic acid had significantly higher mean bond strength values (SD) for all conditions: 24 hours [12.2 (.7) MPa] and 6 months [10.1 (.6) MPa] of water storage. 37% phosphoric acid had intermediate bond strength values for all conditions: 24 hours [8.2 (.6) MPa] and 6 months [6.2 (.6) MPa] of water storage. Also, there were differences in bond strength between storage time, with a reduction in values from 24 hours and 6 months for all experimental groups (P < .001). Conclusion. Lactic acid could be used in place of phosphoric acid as an enamel etchant for bonding of orthodontic brackets. PMID:25006465

  9. In situ chemical functionalization of gallium nitride with phosphonic acid derivatives during etching.

    PubMed

    Wilkins, Stewart J; Greenough, Michelle; Arellano, Consuelo; Paskova, Tania; Ivanisevic, Albena

    2014-03-04

    In situ functionalization of polar (c plane) and nonpolar (a plane) gallium nitride (GaN) was performed by adding (3-bromopropyl) phosphonic acid or propyl phosphonic acid to a phosphoric acid etch. The target was to modulate the emission properties and oxide formation of GaN, which was explored through surface characterization with atomic force microscopy, X-ray photoelectron spectroscopy, photoluminescence (PL), inductively coupled plasma-mass spectrometry, and water contact angle. The use of (3-bromopropyl) phosphonic acid and propyl phosphonic acid in phosphoric acid demonstrated lower amounts of gallium oxide formation and greater hydrophobicity for both sample sets, while also improving PL emission of polar GaN samples. In addition to crystal orientation, growth-related factors such as defect density in bulk GaN versus thin GaN films residing on sapphire substrates were investigated as well as their responses to in situ functionalization. Thin nonpolar GaN layers were the most sensitive to etching treatments due in part to higher defect densities (stacking faults and threading dislocations), which accounts for large surface depressions. High-quality GaN (both free-standing bulk polar and bulk nonpolar) demonstrated increased sensitivity to oxide formation. Room-temperature PL stands out as an excellent technique to identify nonradiative recombination as observed in the spectra of heteroepitaxially grown GaN samples. The chemical methods applied to tune optical and physical properties of GaN provide a quantitative framework for future novel chemical and biochemical sensor development.

  10. Cell adhesion and in vivo osseointegration of sandblasted/acid etched/anodized dental implants.

    PubMed

    Kim, Mu-Hyon; Park, Kyeongsoon; Choi, Kyung-Hee; Kim, Soo-Hong; Kim, Se Eun; Jeong, Chang-Mo; Huh, Jung-Bo

    2015-05-06

    The authors describe a new type of titanium (Ti) implant as a Modi-anodized (ANO) Ti implant, the surface of which was treated by sandblasting, acid etching (SLA), and anodized techniques. The aim of the present study was to evaluate the adhesion of MG-63 cells to Modi-ANO surface treated Ti in vitro and to investigate its osseointegration characteristics in vivo. Four different types of Ti implants were examined, that is, machined Ti (control), SLA, anodized, and Modi-ANO Ti. In the cell adhesion study, Modi-ANO Ti showed higher initial MG-63 cell adhesion and induced greater filopodia growth than other groups. In vivo study in a beagle model revealed the bone-to-implant contact (BIC) of Modi-ANO Ti (74.20%±10.89%) was much greater than those of machined (33.58%±8.63%), SLA (58.47%±12.89), or ANO Ti (59.62%±18.30%). In conclusion, this study demonstrates that Modi-ANO Ti implants produced by sandblasting, acid etching, and anodizing improve cell adhesion and bone ongrowth as compared with machined, SLA, or ANO Ti implants. These findings suggest that the application of Modi-ANO surface treatment could improve the osseointegration of dental implant.

  11. Comparison of shear bond strength of reattached incisor fragment using Er,Cr:YSGG laser etching and conventional acid etching: An in vitro study

    PubMed Central

    Kumar, Gyanendra; Goswami, Mridula; Dhillon, Jatinder Kaur

    2016-01-01

    Aim: The aim of this invitro study is to evaluate the shear bond strength of reattached fractured incisor fragments using Er,Cr:YSGG laser and conventional acid etching without additional tooth preparation. Materials and methods: Forty extracted human teeth were divided in two groups of 20 each (Groups A and B). In Group A, fractured surface was treated by an Er, Cr: YSGG laser system (Waterlase MD, Biolase Technology Inc., San Clemente, CA, USA) operating at a wavelength of 2,780 nm and frequency of 20 Hz. In Group B, fractured surface was etched using 37% phosphoric acid (Scotchbond, 3M). In both the groups, further subdivision with 10 sample each was made based on horizontal and oblique fracture. After laser or acid etching, all the samples were reattached using flowable composite resin and light cured. The samples were tested for shear bond strength. Results: Mean shear bond strength for Group A (94.70±39.158) was lower as compared to Group B (121.25±49.937), although the difference was not statistically significant(p value=0.121). Similarly no statistical significant difference was observed amongst the subgroups. (p>0.05) Conclusion: Er,Cr:YSGG laser etching in reattachment of fractured incisor fragment is a good alternative to conventional acid etching. Er,Cr:YSGG showed comparable efficiency in rebonding of fractured teeth fragment as acid etching. PMID:27721563

  12. Evaluating EDTA as a substitute for phosphoric acid-etching of enamel and dentin.

    PubMed

    Imbery, Terence A; Kennedy, Matthew; Janus, Charles; Moon, Peter C

    2012-01-01

    Matrix metalloproteinases (MMPs) are proteolytic enzymes released when dentin is acid-etched. The enzymes are capable of destroying unprotected collagen fibrils that are not encapsulated by the dentin adhesive. Chlorhexidine applied after etching inhibits the activation of released MMPs, whereas neutral ethylenediamine tetra-acetic acid (EDTA) prevents the release of MMPs. The purpose of this study was to determine if conditioning enamel and dentin with EDTA can be a substitute for treating acid-etching enamel and dentin with chlorhexidine. A column of composite resin was bonded to enamel and dentin after conditioning. Shear bond strengths were evaluated after 48 hours and after accelerated aging for three hours in 12% sodium hypochlorite. Shear bond strengths ranged from 15.6 MP a for accelerated aged EDTA enamel specimens to 26.8 MPa for dentin conditioned with EDTA and tested after 48 hours. A three-way ANOVA and a Tukey HSD test found statistically significant differences among the eight groups and the three independent variables (P < 0.05). EDTA was successfully substituted for phosphoric acid-etched enamel and dentin treated with chlorhexidine. Interactions of conditioning agent and aging were significant for dentin but not for enamel. In an effort to reduce the detrimental effects of MMPs, conditioning enamel and dentin with EDTA is an alternative to treating acid-etched dentin and enamel with chlorhexidine.

  13. Grafting of acrylic acid on etched latent tracks induced by swift heavy ions on polypropylene films

    NASA Astrophysics Data System (ADS)

    Mazzei, R.; Fernández, A.; García Bermúdez, G.; Torres, A.; Gutierrez, M. C.; Magni, M.; Celma, G.; Tadey, D.

    2008-06-01

    In order to continue with a systematic study that include different polymers and monomers, the residual active sites produced by heavy ion beams, that remain after the etching process, were used to start the grafting process. To produce tracks, foils of polypropylene (PP) were irradiated with 208Pb of 25.62 MeV/n. Then, these were etched and grafted with acrylic acid (AA) monomers. Experimental curves of grafting yield as a function of grafting time with the etching time as a parameter were measured. Also, the grating yield as a function of the fluence and etching time was obtained. In addition, the permeation of solutions, with different pH, through PP grafted foils was measured.

  14. The effects of acid etching time on surface mechanical properties of dental hard tissues.

    PubMed

    Zafar, Muhammad Sohail; Ahmed, Naseer

    2015-01-01

    The objective of this study was to evaluate the effect of etching time on the surface properties of dental hard tissues including enamel and dentin. For this purpose, samples were prepared using extracted human teeth and treated with 37% phosphoric acid for various length of time using the set protocol. The effects of etching time on surface roughness were assessed using non-contact surface roughness profilometer and surface hardness was measured using nanoindentation technique. All results were analyzed statistically using SPSS computer software. Within the limitation of this study, it was concluded that etching time influences on the surface properties of dental hard tissues particularly the enamel. Enamel surface properties such as roughness and hardness can be altered remarkable as a matter of few seconds. Prolonged etching time than recommended is likely to increase the surface roughness and decrease surface hardness; compromising the bond strength of adhesive materials in clinical applications.

  15. Effect of the application time of phosphoric acid and self-etch adhesive systems to sclerotic dentin

    PubMed Central

    MENA-SERRANO, Alexandra Patricia; GARCIA, Eugenio Jose; PEREZ, Miguel Muñoz; MARTINS, Gislaine Cristine; GRANDE, Rosa Helena Miranda; LOGUERCIO, Alessandro Dourado; REIS, Alessandra

    2013-01-01

    Objectives: To evaluate the effect of application time on the resin-dentin bond strength (µTBS) and etching pattern of adhesive systems applied on sclerotic dentine. Material and Methods: A total of forty-two bovine incisors had their roots removed. The 1-step self-etch GO (SDI), the 2-step self-etch Adper SE Bond (3MESPE) and the 35% phosphoric acid (3MESPE) from the 2-step etch-and-rinse Adper Single Bond 2 (3MESPE) were applied on the bovine incisal surfaces according to the manufacturer's instructions or duplicating the recommended conditioning time. After adhesive application, thirty teeth were restored with composite resin, stored for 24 h in distilled water at 37º C, and sectioned into resin-dentin bonded sticks (0.8 mm2) and tested according to the µTBS at 0.5 mm/min. The etching pattern of the remaining twelve teeth (n=4 for each material) was examined under scanning electron microscopy. Each tooth was divided into a buccal-to-lingual direction into three thirds, and each third randomly assigned to the groups: control (no treatment), according to the manufacturers' instructions and duplicating the recommended application time. The µTBS and the relative percentage of the tubule area opening were evaluated by two-way repeated measures ANOVA and Tukey's tests (α=0.05). Results: The duplication of the conditioning time favored only the GO adhesive (p<0.05). Both application methods significantly increased the tubule area opening (p<0.05) compared to the controls. Conclusions: The efficacy of duplicating the conditioning time was only effective for the 1-step self-etch adhesive system tested. PMID:23739856

  16. Noble Gases and Nitrogen Released from a Lunar Soil Pyroxene Separate by Acid Etching

    NASA Astrophysics Data System (ADS)

    Rider, P. E.

    1993-07-01

    We report initial results from a series of experiments designed to measure recently implanted solar wind (SW) ions in lunar soil mineral grains [1]. An acid-etching technique similar to the CSSE method developed at ETH Zurich was used to make abundance and isotope measurements of the SW noble gas and nitrogen compositions. Among the samples examined was a pyroxene separate from soil 75081. It was first washed with H2O to remove contamination from the sample finger walls and grain surfaces. H2O also acted as a weak acid, releasing gases from near-surface sites. Treatment with H2SO3 followed the water washes. Acid pH (~1.8 to ~1.0) and temperature (~23 degrees C to ~90 degrees C) and duration of acid attack (several minutes to several days) were varied from step to step. Finally, the sample was pyrolyzed in several steps to remove the remaining gases, culminating with a high-temperature pyrolysis at 1200 degrees C. Measurements of the light noble gases were mostly consistent with those from previous CSSE experiments performed on pyroxene [2,3]. It should be noted, however, that the Zurich SEP component was not easily distinguishable in the steps where it was expected to be observed. We suspect our experimental protocol masked the SEP reservoir, preventing us from seeing its distinctive signature. The most interesting results from this sample are its Kr and Xe isotopic and elemental compositions. Pyroxene apparently retains heavy noble gases as well as ilmenite (and plagioclase [4]). The heavy noble gas element ratios from this sample along with those previously reported [5,6] are, however, considerably heavier than the theoretically determined "solar system" values [7,8]. Explanations for the difference include the possibility that the derivations are incorrect, that there is another component of lunar origin mixing with the solar component, or that some type of loss mechanism is altering the noble gas reservoirs of the grains. The Kr and Xe isotopic compositions for

  17. Shear bond strength of resin cement to an acid etched and a laser irradiated ceramic surface

    PubMed Central

    Motro, Pelin Fatma Karagoz; Yurdaguven, Haktan

    2013-01-01

    PURPOSE To evaluate the effects of hydrofluoric acid etching and Er,Cr:YSGG laser irradiation on the shear bond strength of resin cement to lithium disilicate ceramic. MATERIALS AND METHODS Fifty-five ceramic blocks (5 mm × 5 mm × 2 mm) were fabricated and embedded in acrylic resin. Their surfaces were finished with 1000-grit silicon carbide paper. The blocks were assigned to five groups: 1) 9.5% hydrofluoric-acid etching for 60 s; 2-4), 1.5-, 2.5-, and 6-W Er,Cr:YSGG laser applications for 60 seconds, respectively; and 5) no treatment (control). One specimen from each group was examined using scanning electron microscopy. Ceramic primer (Rely X ceramic primer) and adhesive (Adper Single Bond) were applied to the ceramic surfaces, followed by resin cement to bond the composite cylinders, and light curing. Bonded specimens were stored in distilled water at 37℃ for 24 hours. Shear bond strengths were determined by a universal testing machine at 1 mm/min crosshead speed. Data were analyzed using Kruskal-Wallis and Mann-Whitney U-tests (α=0.05). RESULTS Adhesion was significantly stronger in Group 2 (3.88 ± 1.94 MPa) and Group 3 (3.65 ± 1.87 MPa) than in Control group (1.95 ± 1.06 MPa), in which bonding values were lowest (P<.01). No significant difference was observed between Group 4 (3.59 ± 1.19 MPa) and Control group. Shear bond strength was highest in Group 1 (8.42 ± 1.86 MPa; P<.01). CONCLUSION Er,Cr:YSGG laser irradiation at 1.5 and 2.5 W increased shear bond strengths between ceramic and resin cement compared with untreated ceramic surfaces. Irradiation at 6 W may not be an efficient ceramic surface treatment technique. PMID:23755333

  18. Surface changes of biopolymers PHB and PLLA induced by Ar+ plasma treatment and wet etching

    NASA Astrophysics Data System (ADS)

    Slepičková Kasálková, N.; Slepička, P.; Sajdl, P.; Švorčík, V.

    2014-08-01

    Polymers, especially group of biopolymers find potential application in a wide range of disciplines due to their biodegradability. In biomedical applications these materials can be used as a scaffold or matrix. In this work, the influence of the Ar+ plasma treatment and subsequent wet etching (acetone/water) on the surface properties of polymers were studied. Two biopolymers - polyhydroxybutyrate with 8% polyhydroxyvalerate (PHB) and poly-L-lactic acid (PLLA) were used in these experiments. Modified surface layers were analyzed by different methods. Surface wettability was characterized by determination of water contact angle. Changes in elemental composition of modified surfaces were performed by X-ray Photoelectron Spectroscopy (XPS). Surface morphology and roughness was examined using Atomic Force Microscopy (AFM). Gravimetry method was used to study the mass loss. It was found that the modification from both with plasma and wet etching leads to dramatic changes of surface properties (surface chemistry, morphology and roughness). Rate of changes of these features strongly depends on the modification parameters.

  19. Effect of acid etching of glass ionomer cement surface on the microleakage of sandwich restorations.

    PubMed

    Bona, Alvaro Della; Pinzetta, Caroline; Rosa, Vinícius

    2007-06-01

    The purposes of this study were to evaluate the sealing ability of different glass ionomer cements (GICs) used for sandwich restorations and to assess the effect of acid etching of GIC on microleakage at GIC-resin composite interface. Forty cavities were prepared on the proximal surfaces of 20 permanent human premolars (2 cavities per tooth), assigned to 4 groups (n=10) and restored as follows: Group CIE - conventional GIC (CI) was applied onto the axial and cervical cavity walls, allowed setting for 5 min and acid etched (E) along the cavity margins with 35% phosphoric acid for 15 s, washed for 30 s and water was blotted; the adhesive system was applied and light cured for 10 s, completing the restoration with composite resin light cured for 40 s; Group CIN - same as Group CIE, except for acid etching of the CI surface; Group RME - same as CIE, but using a resin modified GIC (RMGIC); Group RMN - same as Group RME, except for acid etching of the RMGIC surface. Specimens were soaked in 1% methylene blue dye solution at 24 degrees C for 24 h, rinsed under running water for 1 h, bisected longitudinally and dye penetration was measured following the ISO/TS 11405-2003 standard. Results were statistically analyzed by Kruskal-Wallis and chi-square tests (a=0.05). Dye penetration scores were as follow: CIE - 2.5; CIN - 2.5; RME - 0.9; and RMN - 0.6. The results suggest that phosphoric acid etching of GIC prior to the placement of composite resin does not improve the sealing ability of sandwich restorations. The RMGIC was more effective in preventing dye penetration at the GIC-resin composite-dentin interfaces than CI.

  20. Metal etching composition

    NASA Technical Reports Server (NTRS)

    Otousa, Joseph E. (Inventor); Thomas, Clark S. (Inventor); Foster, Robert E. (Inventor)

    1991-01-01

    The present invention is directed to a chemical etching composition for etching metals or metallic alloys. The composition includes a solution of hydrochloric acid, phosphoric acid, ethylene glycol, and an oxidizing agent. The etching composition is particularly useful for etching metal surfaces in preparation for subsequent fluorescent penetrant inspection.

  1. Bonding of self-adhesive resin cements to enamel using different surface treatments: bond strength and etching pattern evaluations.

    PubMed

    Lin, Jie; Shinya, Akikazu; Gomi, Harunori; Shinya, Akiyoshi

    2010-08-01

    This study evaluated the shear bond strengths and etching patterns of seven self-adhesive resin cements to human enamel specimens which were subjected to one of the following surface treatments: (1) Polishing with #600 polishing paper; (2) Phosphoric acid; (3) G-Bond one-step adhesive; or (4) Phosphoric acid and G-Bond. After surface treatment, the human incisor specimens were bonded to a resin composite using a self-adhesive resin cement [Maxcem (MA), RelyX Unicem (UN), Breeze (BR), BisCem (BI), seT (SE), Clearfil SA Luting (CL)] or a conventional resin cement [ResiCem (RE)]. Representative morphology formed with self-adhesive resin cements showed areas of etched enamel intermingled with areas of featureless enamel. In conclusion, etching efficacy influenced the bonding effectiveness of self-adhesive resin cements to unground enamel, and that a combined use of phosphoric acid and G-Bond for pretreatment of human enamel surfaces improved the bond strength of self-adhesive resin cements.

  2. Miniature tapered photonic crystal fiber interferometer with enhanced sensitivity by acid microdroplets etching.

    PubMed

    Qiu, Sun-jie; Chen, Ye; Kou, Jun-long; Xu, Fei; Lu, Yan-qing

    2011-08-01

    We fabricate a miniature tapered photonic crystal fiber (PCF) interferometer with enhanced sensitivity by acid microdroplets etching. This method is very simple and cost effective, avoiding elongating the PCF, moving and refixing the device during etching, and measuring. The refractive index sensing properties with different PCF diameters are investigated both theoretically and experimentally. The tapering velocity can be controlled by the microdroplet size and position. The sensitivity greatly increases (five times, 750 nm/RIU) and the size decreases after slightly tapering the PCF. The device keeps low temperature dependence before and after tapering. More uniformly and thinly tapered PCFs can be realized with higher sensitivity (∼100 times) by optimizing the etching process.

  3. Acid-etched microtexture for enhancement of bone growth into porous-coated implants.

    PubMed

    Hacking, S A; Harvey, E J; Tanzer, M; Krygier, J J; Bobyn, J D

    2003-11-01

    We designed an in vivo study to determine if the superimposition of a microtexture on the surface of sintered titanium beads affected the extent of bone ingrowth. Cylindrical titanium intramedullary implants were coated with titanium beads to form a porous finish using commercial sintering techniques. A control group of implants was left in the as-sintered condition. The test group was etched in a boiling acidic solution to create an irregular surface over the entire porous coating. Six experimental dogs underwent simultaneous bilateral femoral intramedullary implantation of a control implant and an acid etched implant. At 12 weeks, the implants were harvested in situ and the femora processed for undecalcified, histological examination. Eight transverse serial sections for each implant were analysed by backscattered electron microscopy and the extent of bone ingrowth was quantified by computer-aided image analysis. The extent of bone ingrowth into the control implants was 15.8% while the extent of bone ingrowth into the etched implants was 25.3%, a difference of 60% that was statistically significant. These results are consistent with other research that documents the positive effect of microtextured surfaces on bone formation at an implant surface. The acid etching process developed for this study represents a simple method for enhancing the potential of commonly available porous coatings for biological fixation.

  4. Inactivation of Matrix-bound MMPs by Cross-linking Agents in Acid Etched Dentin

    PubMed Central

    Scheffel, Débora Lopes Salles; Hebling, Josimeri; Scheffel, Régis Henke; Agee, Kelly A.; Turco, Gianluca; de Souza Costa, Carlos Alberto; Pashley, David H.

    2014-01-01

    Objectives Published TEM analysis of in vivo resin-dentin bonds shows that in 44 months almost 70% of collagen fibrils from the hybrid layer disappear. Matrix metalloproteinases (MMPs) play an important role in that process and are thought to be the main factor responsible for the solubitization of dentin collagen. Therefore, this study aimed to evaluate the inactivation of matrix-bound MMPs by carbodiimide (EDC) or proanthocyanidin (PA) both cross-linking agents, or the MMP-inhibitor, chlorhexidine (CHX), on acid-etched dentin using a simplified MMP assay method. Methods Dentin beams (1×1×6mm) were obtained from mid-coronal dentin of sound third molars and randomly divided into 6 groups (G) according to the dentin treatment: G1: Deionized water (control), G2: 0.1M EDC, G3: 0.5M EDC, G4: 0.5M EDC+35% HEMA, G5: 5% Proanthocyanidin (PA) and G6: 2% CHX. The beams were etched for 15s with 37% phosphoric acid, rinsed and then immersed for 60s in one of the treatment solutions. The total MMP activity of dentin was analyzed for 1 h by colorimetric assay (Sensolyte). Data were submitted to Wilcoxon non-parametric test and Mann-Whitney tests (p>0.05). Results All experimental cross-linking solutions significantly reduced MMP activity compared to control, except 0.1M EDC (53.6% ±16.1). No difference was observed between cross-linking agents and 2% CHX 0.5M EDC + 35% HEMA (92.3% ±8.0) was similar to 0.5M EDC (89.1% ±6.4), 5% PA (100.8% ±10.9) and 2% CHX (83.4% ±10.9). Conclusion Dentin treatment with cross-linking agents is effective to significantly reduce MMP activity. Mixing 0.5M EDC and 35% HEMA did not influence EDC inhibitor potential. PMID:23786610

  5. Synthesis of anatase titanium dioxide nanocaps via hydrofluoric acid etching towards enhanced photocatalysis

    SciTech Connect

    Ding, Kun; Wang, Dan; Yang, Ping; Cheng, Xin

    2016-02-15

    Graphical abstract: Anatase TiO{sub 2} nanocaps prepared by HF-assisted chemical etching method exhibit enhanced photocatalytic activity compared with commercial P25 because of HF served as an etching agent to remove doped impurities. - Highlights: • Anatase TiO{sub 2} nanocaps were synthesized by HF etching process. • The optimal conditions of experiment are 700 °C calcination and 0.2 mL HF solution. • The photocatalytic properties was studied upon UV and Visible irradiation. • The unique TiO{sub 2} nanocaps structure shows excellent photocatalytic activity. - Abstract: Anatase titanium dioxide (TiO{sub 2}) nanocaps were created via a four-step process including the preparation of SiO{sub 2} spheres, the deposition of a TiO{sub 2} layer to fabricate SiO{sub 2}@TiO{sub 2} composite spheres, the calcination for obtaining the crystal structure of anatase phase, and hydrofluoric acid (HF) etching to dissolve SiO{sub 2} cores. The SiO{sub 2}@TiO{sub 2} spheres calcined at 700 °C revealed fine photocatalytic activity. Interestingly, most of samples transformed into TiO{sub 2} nanocaps via HF etching, and TiO{sub 2} nanocaps prepared using optimal conditions exhibited quick degradation (k is 0.052 min{sup −1}) compared with commercial P25 (k is 0.030 min{sup −1}) and the TiO{sub 2} nanostructures etched by a NaOH solution. The excellent photocatalytic performance is attributed to its unique hollow hemispherical nanocaps structure, which is in favor of making full use of incident light. The photocatalysis phenomenon in visible light was also observed after depositing Au nanoparticles on anantase TiO{sub 2} nanocaps.

  6. Effect of EDTA and Phosphoric Acid Pretreatment on the Bonding Effectiveness of Self-Etch Adhesives to Ground Enamel

    PubMed Central

    Ibrahim, Ihab M.; Elkassas, Dina W.; Yousry, Mai M.

    2010-01-01

    Objectives: This in vitro study determined the effect of enamel pretreatment with phosphoric acid and ethylenediaminetetraacetic acid (EDTA) on the bond strength of strong, intermediary strong, and mild self-etching adhesive systems. Methods: Ninety sound human premolars were used. Resin composite cylinders were bonded to flat ground enamel surfaces using three self-etching adhesive systems: strong Adper Prompt L-Pop (pH=0.9–1.0), intermediary strong AdheSE (pH=1.6–1.7), and mild Frog (pH=2). Adhesive systems were applied either according to manufacturer instructions (control) or after pretreatment with either phosphoric acid or EDTA (n=10). After 24 hours, shear bond strength was tested using a universal testing machine at a cross-head speed of 0.5 mm/minute. Ultra-morphological characterization of the surface topography and resin/enamel interfaces as well as representative fractured enamel specimens were examined using scanning electron microscopy (SEM). Results: Neither surface pretreatment statistically increased the mean shear bond strength values of either the strong or the intermediary strong self-etching adhesive systems. However, phosphoric acid pretreatment significantly increased the mean shear bond strength values of the mild self-etching adhesive system. SEM examination of enamel surface topography showed that phosphoric acid pretreatment deepened the same etching pattern of the strong and intermediary strong adhesive systems but converted the irregular etching pattern of the mild self-etching adhesive system to a regular etching pattern. SEM examination of the resin/enamel interface revealed that deepening of the etching pattern was consistent with increase in the length of resin tags. EDTA pretreatment had a negligible effect on ultra-morphological features. Conclusions: Use of phosphoric acid pretreatment can be beneficial with mild self-etching adhesive systems for bonding to enamel. PMID:20922162

  7. Effect of a self-etching primer and phosphoric acid etching on the bond strength of 4-META/MMA-TBB resin to human enamel.

    PubMed

    Nogawa, Hiroshi; Koizumi, Hiroyasu; Saiki, Osamu; Hiraba, Haruto; Nakamura, Mitsuo; Matsumura, Hideo

    2015-01-01

    The purpose of this study was to evaluate the shear bond strength and durability of 4-META/MMA-TBB resin to human enamel. A self-etching primer that contained 4-META (Teeth Primer, TP) and 35-45% or 60-65% concentrations of phosphoric acid (K-Etchant Gel, KE, and Super Bond C&B Red Activator, RA) were used as the surface treatment agents. A methyl methacrylate (MMA)-based self-polymerizing resin (Super-Bond C&B) was used as a luting agent. The shear bond strength was determined both pre and post thermocycling. The results were statistically analyzed with a non-parametric procedure. The post-thermocycling shear bond strength of the TP group was significantly higher than that of other groups, and that of the KE group was significantly higher compared with the RA group. These results demonstrated that 4-META was effective. Furthermore, when the degree of tooth demineralization was compared, surface treatment with less demineralization using TP was the most effective treatment.

  8. Hydrogen content in titanium and a titanium-zirconium alloy after acid etching.

    PubMed

    Frank, Matthias J; Walter, Martin S; Lyngstadaas, S Petter; Wintermantel, Erich; Haugen, Håvard J

    2013-04-01

    Dental implant alloys made from titanium and zirconium are known for their high mechanical strength, fracture toughness and corrosion resistance in comparison with commercially pure titanium. The aim of the study was to investigate possible differences in the surface chemistry and/or surface topography of titanium and titanium-zirconium surfaces after sand blasting and acid etching. The two surfaces were compared by X-ray photoelectron spectroscopy, secondary ion mass spectroscopy, scanning electron microscopy and profilometry. The 1.9 times greater surface hydrogen concentration of titanium zirconium compared to titanium was found to be the major difference between the two materials. Zirconium appeared to enhance hydride formation on titanium alloys when etched in acid. Surface topography revealed significant differences on the micro and nanoscale. Surface roughness was increased significantly (p<0.01) on the titanium-zirconium alloy. High-resolution images showed nanostructures only present on titanium zirconium.

  9. Effect of acid etching on bond strength of nanoionomer as an orthodontic bonding adhesive

    PubMed Central

    Khan, Saba; Verma, Sanjeev K.; Maheshwari, Sandhya

    2015-01-01

    Aims: A new Resin Modified Glass Ionomer Cement known as nanoionomer containing nanofillers of fluoroaluminosilicate glass and nanofiller 'clusters' has been introduced. An in-vitro study aimed at evaluating shear bond strength (SBS) and adhesive remnant index (ARI) of nanoionomer under etching/unetched condition for use as an orthodontic bonding agent. Material and Methods: A total of 75 extracted premolars were used, which were divided into three equal groups of 25 each: 1-Conventional adhesive (Enlight Light Cure, SDS, Ormco, CA, USA) was used after and etching with 37% phosphoric acid for 30 s, followed by Ortho Solo application 2-nanoionomer (Ketac™ N100, 3M, ESPE, St. Paul, MN, USA) was used after etching with 37% phosphoric acid for 30 s 3-nanoionomer was used without etching. The SBS testing was performed using a digital universal testing machine (UTM-G-410B, Shanta Engineering). Evaluation of ARI was done using scanning electron microscopy. The SBS were compared using ANOVA with post-hoc Tukey test for intergroup comparisons and ARI scores were compared with Chi-square test. Results: ANOVA (SBS, F = 104.75) and Chi-square (ARI, Chi-square = 30.71) tests revealed significant differences between groups (P < 0.01). The mean (SD) SBS achieved with conventional light cure adhesive was significantly higher (P < 0.05) (10.59 ± 2.03 Mpa, 95% CI, 9.74-11.41) than the nanoionomer groups (unetched 4.13 ± 0.88 Mpa, 95% CI, 3.79-4.47 and etched 9.32 ± 1.87 Mpa, 95% CI, 8.58-10.06). However, nanoionomer with etching, registered SBS in the clinically acceptable range of 5.9–7.8 MPa, as suggested by Reynolds (1975). The nanoionomer groups gave significantly lower ARI values than the conventional adhesive group. Conclusion: Based on this in-vitro study, nanoionomer with etching can be successfully used as an orthodontic bonding agent leaving less adhesive remnant on enamel surface, making cleaning easier. However, in-vivo studies are needed to confirm the validity

  10. Hydrothermal Etching Treatment to Rutile TiO2 Nanorod Arrays for Improving the Efficiency of CdS-Sensitized TiO2 Solar Cells

    NASA Astrophysics Data System (ADS)

    Wan, Jingshu; Liu, Rong; Tong, Yuzhu; Chen, Shuhuang; Hu, Yunxia; Wang, Baoyuan; Xu, Yang; Wang, Hao

    2016-01-01

    Highly ordered TiO2 nanorod arrays (NRAs) were directly grown on an F:SnO2 (FTO) substrate without any seed layer by hydrothermal route. For a larger surface area, the second-step hydrothermal treatment in hydrochloric acid was carried out to the as-prepared TiO2 NRAs. The results showed that the center portion of the TiO2 nanorods were dissolved in the etching solution to form a nanocave at the initial etching process. As the etching time extended, the tip parts of the nanocave wall split into lots of nanowires with a reduced diameter, giving rise to a remarkable increase of specific surface area for the TiO2 NRAs. The TiO2 films after etching treatment were sensitized by CdS quantum dots (QDs) to fabricate quantum dot-sensitized solar cells (QDSSCs), which exhibited a significant improvement in the photocurrent density in comparison with that of the un-treated device, this mainly attributed to the enhancement of QD loading and diffused reflectance ability. Through modifying the etching TiO2 films with TiCl4, a relatively high power conversion efficiency (PCE) of 3.14 % was obtained after optimizing the etching time.

  11. Hydrothermal Etching Treatment to Rutile TiO2 Nanorod Arrays for Improving the Efficiency of CdS-Sensitized TiO2 Solar Cells.

    PubMed

    Wan, Jingshu; Liu, Rong; Tong, Yuzhu; Chen, Shuhuang; Hu, Yunxia; Wang, Baoyuan; Xu, Yang; Wang, Hao

    2016-12-01

    Highly ordered TiO2 nanorod arrays (NRAs) were directly grown on an F:SnO2 (FTO) substrate without any seed layer by hydrothermal route. For a larger surface area, the second-step hydrothermal treatment in hydrochloric acid was carried out to the as-prepared TiO2 NRAs. The results showed that the center portion of the TiO2 nanorods were dissolved in the etching solution to form a nanocave at the initial etching process. As the etching time extended, the tip parts of the nanocave wall split into lots of nanowires with a reduced diameter, giving rise to a remarkable increase of specific surface area for the TiO2 NRAs. The TiO2 films after etching treatment were sensitized by CdS quantum dots (QDs) to fabricate quantum dot-sensitized solar cells (QDSSCs), which exhibited a significant improvement in the photocurrent density in comparison with that of the un-treated device, this mainly attributed to the enhancement of QD loading and diffused reflectance ability. Through modifying the etching TiO2 films with TiCl4, a relatively high power conversion efficiency (PCE) of 3.14 % was obtained after optimizing the etching time.

  12. Micro-shear bond strength and surface micromorphology of a feldspathic ceramic treated with different cleaning methods after hydrofluoric acid etching

    PubMed Central

    STEINHAUSER, Henrique Caballero; TURSSI, Cecília Pedroso; FRANÇA, Fabiana Mantovani Gomes; do AMARAL, Flávia Lucisano Botelho; BASTING, Roberta Tarkany

    2014-01-01

    Objective The aim of this study was to evaluate the effect of feldspathic ceramic surface cleaning on micro-shear bond strength and ceramic surface morphology. Material and Methods Forty discs of feldspathic ceramic were prepared and etched with 10% hydrofluoric acid for 2 minutes. The discs were randomly distributed into five groups (n=8): C: no treatment, S: water spray + air drying for 1 minute, US: immersion in ultrasonic bath for 5 minutes, F: etching with 37% phosphoric acid for 1 minute, followed by 1-minute rinse, F+US: etching with 37% phosphoric acid for 1 minute, 1-minute rinse and ultrasonic bath for 5 minutes. Composite cylinders were bonded to the discs following application of silane and hydrophobic adhesive for micro-shear bond strength testing in a universal testing machine at 0.5 mm/min crosshead speed until failure. Stereomicroscopy was used to classify failure type. Surface micromorphology of each treatment type was evaluated by scanning electron microscopy at 500 and 2,500 times magnification. Results One-way ANOVA test showed no significant difference between treatments (p=0.3197) and the most common failure types were cohesive resin cohesion followed by adhesive failure. Micro-shear bond strength of the feldspathic ceramic substrate to the adhesive system was not influenced by the different surface cleaning techniques. Absence of or less residue was observed after etching with hydrofluoric acid for the groups US and F+US. Conclusions Combining ceramic cleaning techniques with hydrofluoric acid etching did not affect ceramic bond strength, whereas, when cleaning was associated with ultrasound, less residue was observed. PMID:24676577

  13. Bond strength of composite to dentin: effect of acid etching and laser irradiation through an uncured self-etch adhesive system

    NASA Astrophysics Data System (ADS)

    Castro, F. L. A.; Carvalho, J. G.; Andrade, M. F.; Saad, J. R. C.; Hebling, J.; Lizarelli, R. F. Z.

    2014-08-01

    This study evaluated the effect on micro-tensile bond strength (µ-TBS) of laser irradiation of etched/unetched dentin through an uncured self-etching adhesive. Dentinal surfaces were treated with Clearfil SE Bond Adhesive (CSE) either according to the manufacturer’s instructions (CSE) or without applying the primer (CSE/NP). The dentin was irradiated through the uncured adhesive, using an Nd:YAG laser at 0.75 or 1 W power settings. The adhesive was cured, composite crowns were built up, and the teeth were sectioned into beams (0.49 mm2) to be stressed under tension. Data were analyzed using one-way ANOVA and Tukey statistics (α = 5%). Dentin of the fractured specimens and the interfaces of untested beams were observed under scanning electron microscopy (SEM). The results showed that non-etched irradiated surfaces presented higher µ-TBS than etched and irradiated surfaces (p < 0.05). Laser irradiation alone did not lead to differences in µ-TBS (p > 0.05). SEM showed solidification globules on the surfaces of the specimens. The interfaces were similar on irradiated and non-irradiated surfaces. Laser irradiation of dentin through the uncured adhesive did not lead to higher µ-TBS when compared to the suggested manufacturer’s technique. However, this treatment brought benefits when performed on unetched dentin, since bond strengths were higher when compared to etched dentin.

  14. Instrumentation With Ultrasonic Scalers Facilitates Cleaning of the Sandblasted and Acid-Etched Titanium Implants.

    PubMed

    Park, Jun-Beom; Lee, Sung-Hoon; Kim, NamRyang; Park, Seojin; Jin, Seong-Ho; Choi, Bong-Kyu; Kim, Kack-Kyun; Ko, Youngkyung

    2015-08-01

    Mechanical instrumentation is widely used to debride dental implants, but this may alter the surface properties of titanium, which in turn may influence bacterial adhesion and make it more difficult to remove the biofilm. This in vitro study was performed (1) to assess the amount of biofilm formation on a sand-blasted and acid-etched titanium fixture treated with ultrasonic scalers with metal, plastic, and carbon tips and (2) to evaluate how this treatment of titanium surfaces affects implant cleaning by brushing with dentifrice. The titanium fixtures were treated with various ultrasonic scaler tips, and surface roughness parameters were measured by confocal microscopy. Biofilm was formed on the treated fixtures by using pooled saliva from 10 subjects, and the quantity of the adherent bacteria was compared with crystal violet assay. The fixture surfaces with biofilm were brushed for total of 30 seconds with a toothbrush with dentifrice. The bacteria remaining on the brushed fixture surfaces were quantified by scanning electron microscopy. Surface changes were evident, and the changes of the surfaces were more discernible when metal tips were used. A statistically significant decrease in roughness value (arithmetic mean height of the surface) was seen in the 2 metal-tip groups and the single plastic-tip group. After brushing with dentifrice, the treated surfaces in all the treatment groups showed significantly fewer bacteria compared with the untreated surfaces in the control group, and the parts of the surfaces left untreated in the test groups. Within the limits of this study, treatment of titanium fixture surfaces with ultrasonic metal, plastic, or carbon tips significantly enhanced the bacterial removal efficacy of brushing. Thorough instrumentation that smooths the whole exposed surface may facilitate maintenance of the implants.

  15. Effects of laser and acid etching and air abrasion on mineral content of dentin.

    PubMed

    Malkoc, Meral Arslan; Taşdemir, Serife Tuba; Ozturk, A Nilgun; Ozturk, Bora; Berk, Gizem

    2011-01-01

    The aim of this study was to evaluate the mineral content of dentin prepared using an Er,Cr:YSGG laser at four different power settings, acid etching, and air abrasion. The study teeth comprised 35 molars which were randomly divided into seven equal groups. The occlusal third of the crowns were cut with a slow-speed diamond saw. The groups were as follows: group A, control group; group B, dentin etched with 35% buffered phosphoric acid for 30 s; group C, dentin abraded at 60 psi with 50-µm aluminium oxide for 1 s; groups D-G, dentin irradiated with the Er,Cr:YSGG laser at 1.50 W (group D), 2.25 W (group E), 3.00 W (group F), and 3.50 W (group G). The levels of Mg, P, Ca, K and Na in each dentin slab were measured by inductively coupled plasma-atomic emission spectrometry (ICP-AES). Data were analysed by one way analysis of variance and Tukey HSD tests. There were no significant differences between the groups in the levels of Ca, P and Na, and the Ca/P ratio (p>0.05); however, there were significant differences in the levels of K (p<0.001) and Mg (p=0.13). In addition, the levels of Mg in the air abrasion group were higher than in the other groups (p<0.01). Etching with the Er,Cr:YSGG laser system, air abrasion and acid etching did not affect the levels of Ca, P and Na, or the Ca/P ratio, in the dentin surface.

  16. Investigation of acid-etched CO2 laser ablated enamel surfaces using polarization sensitive optical coherence tomography

    NASA Astrophysics Data System (ADS)

    Nahm, Byung J.; Kang, Hobin; Chan, Kenneth; Fried, Daniel

    2012-01-01

    A carbon dioxide laser operating at the highly absorbed wavelength of 9.3μm with a pulse duration of 10-15μs is ideally suited for caries removal and caries prevention. The enamel thermally modified by the laser has enhanced resistance to acid dissolution. This is an obvious advantage for caries prevention; however, it is often necessary to etch the enamel surface to increase adhesion to composite restorative materials and such surfaces may be more resistant to etching. The purpose of the study was to non-destructively measure the susceptibility of laser-ablated enamel surfaces to acid dissolution before and after acid-etching using Polarization Sensitive Optical Coherence Tomography (PS-OCT). PS-OCT was used to acquire images of bovine enamel surfaces after exposure to laser irradiation at ablative fluence, acid-etching, and a surface softened dissolution model. The integrated reflectivity from lesion and the lesion depth were measured using PS-OCT. Samples were also sectioned for examination by Polarized Light Microscopy (PLM). PS-OCT images showed that acid-etching greatly accelerated the formation of subsurface lesions on both laser-irradiated and non-irradiated surfaces (P<0.05). A 37.5% phosphoric acid etch removed the laser modified enamel layer after 5-10 seconds.

  17. Micro/nanofabrication of poly(L-lactic acid) using focused ion beam direct etching

    NASA Astrophysics Data System (ADS)

    Oyama, Tomoko Gowa; Hinata, Toru; Nagasawa, Naotsugu; Oshima, Akihiro; Washio, Masakazu; Tagawa, Seiichi; Taguchi, Mitsumasa

    2013-10-01

    Micro/nanofabrication of biocompatible and biodegradable poly(L-lactic acid) (PLLA) using focused Ga ion beam direct etching was evaluated for future bio-device applications. The fabrication performance was determined with different ion fluences and fluxes (beam currents), and it was found that the etching speed and fabrication accuracy were affected by irradiation-induced heat. Focused ion beam (FIB)-irradiated surfaces were analyzed using micro-area X-ray photoelectron spectroscopy. Owing to reactions such as the physical sputtering of atoms and radiation-induced decomposition, PLLA was gradually carbonized with increasing C=C bonds. Controlled micro/nanostructures of PLLA were fabricated with C=C bond-rich surfaces expected to have good cell attachment properties.

  18. Influence of pH, bleaching agents, and acid etching on surface wear of bovine enamel

    PubMed Central

    Soares, Ana Flávia; Bombonatti, Juliana Fraga Soares; Alencar, Marina Studart; Consolmagno, Elaine Cristina; Honório, Heitor Marques; Mondelli, Rafael Francisco Lia

    2016-01-01

    ABSTRACT Development of new materials for tooth bleaching justifies the need for studies to evaluate the changes in the enamel surface caused by different bleaching protocols. Objective The aim of this study was to evaluate the bovine dental enamel wear in function of different bleaching gel protocols, acid etching and pH variation. Material and Methods Sixty fragments of bovine teeth were cut, obtaining a control and test areas. In the test area, one half received etching followed by a bleaching gel application, and the other half, only the bleaching gel. The fragments were randomly divided into six groups (n=10), each one received one bleaching session with five hydrogen peroxide gel applications of 8 min, activated with hybrid light, diode laser/blue LED (HL) or diode laser/violet LED (VHL) (experimental): Control (C); 35% Total Blanc Office (TBO35HL); 35% Lase Peroxide Sensy (LPS35HL); 25% Lase Peroxide Sensy II (LPS25HL); 15% Lase Peroxide Lite (LPL15HL); and 10% hydrogen peroxide (experimental) (EXP10VHL). pH values were determined by a pHmeter at the initial and final time periods. Specimens were stored, subjected to simulated brushing cycles, and the superficial wear was determined (μm). ANOVA and Tukey´s tests were applied (α=0.05). Results The pH showed a slight decrease, except for Group LPL15HL. Group LPS25HL showed the highest degree of wear, with and without etching. Conclusion There was a decrease from the initial to the final pH. Different bleaching gels were able to increase the surface wear values after simulated brushing. Acid etching before bleaching increased surface wear values in all groups. PMID:27008254

  19. The Effect of Hydrofluoric Acid Etching Duration on the Surface Micromorphology, Roughness, and Wettability of Dental Ceramics

    PubMed Central

    Ramakrishnaiah, Ravikumar; Alkheraif, Abdulaziz A.; Divakar, Darshan Devang; Matinlinna, Jukka P.; Vallittu, Pekka K.

    2016-01-01

    The current laboratory study is evaluating the effect of hydrofluoric acid etching duration on the surface characteristics of five silica-based glass ceramics. Changes in the pore pattern, crystal structure, roughness, and wettability were compared and evaluated. Seventy-five rectangularly shaped specimens were cut from each material (IPS e-max™, Dentsply Celtra™, Vita Suprinity™, Vita mark II™, and Vita Suprinity FC™); the sectioned samples were finished, polished, and ultrasonically cleaned. Specimens were randomly assigned into study groups: control (no etching) and four experimental groups (20, 40, 80 and 160 s of etching). The etched surfaces’ microstructure including crystal structure, pore pattern, pore depth, and pore width was studied under a scanning electron microscope, and the surface roughness and wettability were analyzed using a non-contact surface profilometer and a contact angle measuring device, respectively. The results were statistically analyzed using one-way analysis of variance (ANOVA) and the post hoc Tukey’s test. The results showed a significant change in the pore number, pore pattern, crystal structure, surface roughness, and wettability with increased etching duration. Etching for a short time resulted in small pores, and etching for longer times resulted in wider, irregular grooves. A significant increase in the surface roughness and wettability was observed with an increase in the etching duration. The findings also suggested a strong association between the surface roughness and wettability. PMID:27240353

  20. The Effect of Hydrofluoric Acid Etching Duration on the Surface Micromorphology, Roughness, and Wettability of Dental Ceramics.

    PubMed

    Ramakrishnaiah, Ravikumar; Alkheraif, Abdulaziz A; Divakar, Darshan Devang; Matinlinna, Jukka P; Vallittu, Pekka K

    2016-05-27

    The current laboratory study is evaluating the effect of hydrofluoric acid etching duration on the surface characteristics of five silica-based glass ceramics. Changes in the pore pattern, crystal structure, roughness, and wettability were compared and evaluated. Seventy-five rectangularly shaped specimens were cut from each material (IPS e-max™, Dentsply Celtra™, Vita Suprinity™, Vita mark II™, and Vita Suprinity FC™); the sectioned samples were finished, polished, and ultrasonically cleaned. Specimens were randomly assigned into study groups: control (no etching) and four experimental groups (20, 40, 80 and 160 s of etching). The etched surfaces' microstructure including crystal structure, pore pattern, pore depth, and pore width was studied under a scanning electron microscope, and the surface roughness and wettability were analyzed using a non-contact surface profilometer and a contact angle measuring device, respectively. The results were statistically analyzed using one-way analysis of variance (ANOVA) and the post hoc Tukey's test. The results showed a significant change in the pore number, pore pattern, crystal structure, surface roughness, and wettability with increased etching duration. Etching for a short time resulted in small pores, and etching for longer times resulted in wider, irregular grooves. A significant increase in the surface roughness and wettability was observed with an increase in the etching duration. The findings also suggested a strong association between the surface roughness and wettability.

  1. Deep Wet Etching in Hydrofluoric Acid, Nitric Acid, and Acetic Acid of Cavities in a Silicon Wafer

    NASA Astrophysics Data System (ADS)

    Yifan, Zhou; Sihai, Chen; Edmond, Samson; Bosseboeuf, Alain

    2013-07-01

    This paper reports an experimental investigation of deep isotropic etching in HF:HNO3:CH3COOH solution for the fabrication of large microcavities in a silicon wafer. The effects of different practical parameters, e.g., back protective layer, etch window diameter and agitation method, are evaluated experimentally and then discussed. Results show that, for the conditions used, the back protective layer has little influence on the etched depth. Experimental etched profiles are in agreement with the mathematical model of Kuiken's assuming a purely diffusion-controlled etching. Vertical anisotropy and asymmetry of etched profiles were observed. A 100 µm deep hemispherical microcavity was obtained for a 60 min etching with magnetic agitation at room temperature.

  2. Improvement of enamel bond strengths for conventional and resin-modified glass ionomers: acid-etching vs. conditioning*

    PubMed Central

    Zhang, Ling; Tang, Tian; Zhang, Zhen-liang; Liang, Bing; Wang, Xiao-miao; Fu, Bai-ping

    2013-01-01

    Objective: This study deals with the effect of phosphoric acid etching and conditioning on enamel micro-tensile bond strengths (μTBSs) of conventional and resin-modified glass ionomer cements (GICs/RMGICs). Methods: Forty-eight bovine incisors were prepared into rectangular blocks. Highly-polished labial enamel surfaces were either acid-etched, conditioned with liquids of cements, or not further treated (control). Subsequently, two matching pre-treated enamel surfaces were cemented together with one of four cements [two GICs: Fuji I (GC), Ketac Cem Easymix (3M ESPE); two RMGICs: Fuji Plus (GC), RelyX Luting (3M ESPE)] in preparation for μTBS tests. Pre-treated enamel surfaces and cement-enamel interfaces were analyzed by scanning electron microscopy (SEM). Results: Phosphoric acid etching significantly increased the enamel μTBS of GICs/RMGICs. Conditioning with the liquids of the cements produced significantly weaker or equivalent enamel μTBS compared to the control. Regardless of etching, RMGICs yielded stronger enamel μTBS than GICs. A visible hybrid layer was found at certain enamel-cement interfaces of the etched enamels. Conclusions: Phosphoric acid etching significantly increased the enamel μTBSs of GICs/RMGICs. Phosphoric acid etching should be recommended to etch the enamel margins before the cementation of the prostheses such as inlays and onlays, using GICs/RMGICs to improve the bond strengths. RMGICs provided stronger enamel bond strength than GICs and conditioning did not increase enamel bond strength. PMID:24190447

  3. Ultrastructure of the surface of dental enamel with molar incisor hypomineralization (MIH) with and without acid etching.

    PubMed

    Bozal, Carola B; Kaplan, Andrea; Ortolani, Andrea; Cortese, Silvina G; Biondi, Ana M

    2015-01-01

    The aim of the present work was to analyze the ultrastructure and mineral composition of the surface of the enamel on a molar with MIH, with and without acid etching. A permanent tooth without clinical MIH lesions (control) and a tooth with clinical diagnosis of mild and moderate MIH, with indication for extraction, were processed with and without acid etching (H3PO4 37%, 20") for observation with scanning electron microscope (SEM) ZEISS (Supra 40) and mineral composition analysis with an EDS detector (Oxford Instruments). The control enamel showed normal prismatic surface and etching pattern. The clinically healthy enamel on the tooth with MIH revealed partial loss of prismatic pattern. The mild lesion was porous with occasional cracks. The moderate lesion was more porous, with larger cracks and many scales. The mineral composition of the affected surfaces had lower Ca and P content and higher O and C. On the tooth with MIH, even on normal looking enamel, the demineralization does not correspond to an etching pattern, and exhibits exposure of crystals with rods with rounded ends and less demineralization in the inter-prismatic spaces. Acid etching increased the presence of cracks and deep pores in the adamantine structure of the enamel with lesion. In moderate lesions, the mineral composition had higher content of Ca, P and Cl. Enamel with MIH, even on clinically intact adamantine surfaces, shows severe alterations in the ultrastructure and changes in ionic composition, which affect the acid etching pattern and may interfere with adhesion.

  4. Color Stability of Enamel following Different Acid Etching and Color Exposure Times

    PubMed Central

    Jahanbin, Arezoo; Basafa, Mohammad; Moazzami, Mostafa; Basafa, Behnoush; Eslami, Neda

    2014-01-01

    Background and aims. The aim of this study was to evaluate the effect of different etching times on enamel color stability after immediate versus delayed exposure to colored artificial saliva (CAS). Materials and methods. Human first premolars were divided into five groups of twenty. A colorimeter was used according to the CIE system on the mid-buccal and mid-lingual surfaces to evaluate initial tooth color. Samples in group A remained unetched. In groups B to E, buccal and lingual surfaces were initially etched with phosphoric acid for 15 and 60 seconds, respectively. Then, the samples in groups A and C were immersed in colored artificial saliva (cola+saliva). In group B, the teeth were immersed in simple artificial saliva (AS). Samples in groups D and E were immersed in AS for 24 and 72 hours, respectively before being immersed in colored AS. The teeth were immersed for one month in each solution before color measurement. During the test period, the teeth were retrieved from the staining solution and stored in AS for five minutes. This was repeated 60 times. Color changes of buccal and lingual surfaces were calculated. Kruskal-Wallis and Wilcoxon tests were used for statistical analysis (α ≤0.05). Results. There were no significant differences between the groups in term of ΔE of buccal (P = 0.148) and lingual surfaces (P = 0.73). Conclusion. Extended time of etching did not result in significant enamel color change. Immediate and delayed exposure of etched enamel to staining solutions did not result in clinically detectable tooth color changes. PMID:25093048

  5. Strength determination of periodontal splints fabricated from acid-etched retained materials.

    PubMed

    Compton, F H; Beagrie, G S; Chernecky, R

    1977-07-01

    Six systems (one polycarboxylate, one polymethyl methacrylate, one unfilled BIS-GMA resin, two combinations of methyl cyanoacrylate and polymethyl methacrylate, and one combination of unfilled BIS-GMA and filled composite resin) were evaluated for in vitro retention to acid-etched human enamel. Also tested were one unfilled-filled resin combination backed by perforated orthodontic band metal and another unfilled resin backed by stainless steel wire mesh. Significant differences in retention were found. Results show that retention depends pril surface and to resist subsequent chemical degradation.

  6. Comparative Study of the Effect of Acid Etching on Enamel Surface Roughness between Pumiced and Non-pumiced Teeth

    PubMed Central

    Abreu, Lucas Guimarães; Paiva, Saul Martins; Pretti, Henrique; Lages, Elizabeth Maria Bastos; Júnior, João Batista Novães; Ferreira, Ricardo Alberto Neto

    2015-01-01

    Background: The objective was to perform a comparative analysis of the effect of acid etching on enamel roughness between pumiced and non-pumiced teeth. Materials and Methods: The sample was composed of 32 dental surfaces divided into two groups: Group 1-16 surfaces having received pumice prophylaxis; and Group 2-16 surfaces not having received pumice prophylaxis. The teeth were kept in saline until the first record of surface roughness prior to etching. For each surface, a roughness graph was obtained through trials using a surface roughness tester. This procedure was repeated two more times at different locations for a total of three readings which, later, were converted in a mean value. The teeth were then acid etched with a 37% phosphoric acid for 60 s, rinsed with water, air dried, and tested with the roughness tester again using the same protocol described for baseline. The Quantikov image analysis program was used to measure the length of the graphs. The average value of the lengths was recorded for each surface before and after etching. The increase in roughness caused by acid etching was calculated and compared between groups. Results: The mean increase in roughness caused by the etching was 301 µm (11.37%) in Group 1 and 214 µm (8.33%) in Group 2. No statistically significant difference was found between samples with and without pumice prophylaxis (P = 0.283). Conclusion: The present study showed that the effect of acid etching on enamel roughness was not significantly affected by prior pumice prophylaxis. PMID:26435607

  7. In vitro remineralization of acid-etched human enamel with Ca 3SiO 5

    NASA Astrophysics Data System (ADS)

    Dong, Zhihong; Chang, Jiang; Deng, Yan; Joiner, Andrew

    2010-02-01

    Bioactive and inductive silicate-based bioceramics play an important role in hard tissue prosthetics such as bone and teeth. In the present study, a model was established to study the acid-etched enamel remineralization with tricalcium silicate (Ca 3SiO 5, C 3S) paste in vitro. After soaking in simulated oral fluid (SOF), Ca-P precipitation layer was formed on the enamel surface, with the prolonged soaking time, apatite layer turned into density and uniformity and thickness increasingly from 250 to 350 nm for 1 day to 1.7-1.9 μm for 7 days. Structure of apatite crystals was similar to that of hydroxyapatite (HAp). At the same time, surface smoothness of the remineralized layer is favorable for the oral hygiene. These results suggested that C 3S treated the acid-etched enamel can induce apatite formation, indicating the biomimic mineralization ability, and C 3S could be used as an agent of inductive biomineralization for the enamel prosthesis and protection.

  8. The effect of topical fluorides, after acid etching of enamel, on the bond strength of directly bonded orthodontic brackets.

    PubMed

    Hirce, J D; Sather, A H; Chao, E Y

    1980-10-01

    This study tests the hypothesis that the beneficial effects of topical fluoride can be realized without reducing the bond strength of the resin adhesive. Twenty-eight groups of four teeth (third molars and premolars) were extracted from twenty-eight patients and stored in distilled water. Twin brackets on Ormesh pads were bonded to all teeth with Endur adhesive. One tooth from each group was bonded according to the manufacturer's instructions. These teeth, Subgroup I, served as controls. Subgroup II teeth were etched for 4 minutes with 50% phosphoric acid containing 2 percent sodium fluoride. Subgroup III teeth received a 3-minute application of a basic phosphate fluoride solution (10(-2)M NA3PO4, 10(3) ppm F) after 1 minute of etching with 50 percent phosphoric acid. Subgroup IV teeth received a 4-minute application of 8 percent stannous fluoride solution after 1 minute of etching with 50 percent phosphoric acid. Each tooth was mounted in a block of improved dental stone; guide wires were used to reproduce bracket orientation. The M.T.S. materials-testing apparatus was used to generate a torsional moment on the bracket at a rate of 1 degree per second. Fluoride uptake by enamel has been shown to be greater in an acid medium or after acid etching. The application of directly bonded orthodontic brackets and pit-and-fissure sealants requires acid etching of the enamel surface. This study supports the use of topical fluoride after acid etching, a procedure that achieves the benefits of increased fluoride uptake without changing the bond strength of the resin adhesive.

  9. Effect of acid labile ether protecting groups on the oxide etch resistance and lithographic performance of 248-nm resists

    NASA Astrophysics Data System (ADS)

    Varanasi, Pushkara R.; Cornett, Kathleen M.; Lawson, Margaret C.

    2000-06-01

    In our attempts to develop etch resistance 248 nm positive resists, we have designed and synthesized thermally stable and acid sensitive methylbenzyl ether (MBE) protected poly(hydroxystyrene) derivatives. Results presented in this paper clearly illustrate that the MBE protecting group provides superior etch resistance to conventional carbonate, ester and acetal/ketal based protecting groups. It is also shown that the MBE protecting group is thermally stable and undergoes acid catalyzed deprotection leading to preferential rearrangement products due to electrophilic ring substitution. Such a rearrangement is shown to provide a unique mechanism to reduce/eliminate resist shrinkage and improve lithographic performance.

  10. Fabrication of Alumina Nanowires from Porous Alumina Membranes by Etching in Phosphoric Acid Solution

    NASA Astrophysics Data System (ADS)

    Wang, Xuehua; Li, Chengyong; Ma, Lianjiao; Cao, Hong; Zhang, Baohua

    Alumina nanowires (ANWs) with high aspect ratios were synthesized by the chemical etching of porous alumina membranes (PAMs) in phosphoric acid solution. The morphology and structure of ANWs were analyzed by SEM and XRD, respectively. The results showed that the typical features of ANWs are around 35 nm in diameter and around 20 μm in length, the crystalline structure of the ANWs was amorphous, which was in accordance with that of the PAMs. Furthermore, the morphology of the PAMs was characterized by AFM and SEM in detail. On the basis of AFM and SEM observations, a possible formation mechanism of ANWs was discussed, and the inhomogeneous of the dissolution between the triple points and the side walls was considered to be the essential factor deciding the formation of ANWs.

  11. Effect of acid vapor etching on morphological and opto-electric properties of flat silicon and silicon nanowire arrays: A comparative study

    NASA Astrophysics Data System (ADS)

    Amri, Chohdi; Ouertani, Rachid; Hamdi, Abderrahmen; Ezzaouia, Hatem

    2016-03-01

    In this paper, we report a comparative study between porous silicon (pSi) and porous silicon nanowires (pSiNWs). Acid Vapor Etching (AVE) treatment has been used to perform porous structure on flat Si and SiNWs array substrates respectively. SiNW structure is prepared by the widely used Silver catalyzed etching method. SEM and TEM images show that AVE treatment induces porous structure in the whole Si wafer and the SiNW sidewall. Comparatively to pSi, pSiNWs exhibit a low reflectivity in the whole spectral range which decreases with etching duration. However, the reflectivity of pSi changes with porous layer thickness. Both pSi and pSiNWs exhibit a significant PL peak situated at 2 eV. PL peaks are attributed to the quantum confinement effect in the silicon nanocrystallites (SiNCs). We discussed the significant enhancement in the peak intensities and a shift toward lower energy displayed in Raman spectra for both pSi and pSiNWs. We reported a correlative study of the AVE treatment effect on the minority carrier life time of flat silicon and SiNW arrays with the passivation effect of chemical induced silicon oxides highlighted by FTIR spectra.

  12. Effect of self-etching primer vs phosphoric acid etchant on bonding to bur-prepared dentin.

    PubMed

    Ogata, M; Harada, N; Yamaguchi, S; Nakajima, M; Tagami, J

    2002-01-01

    This study evaluated the effect of dentin conditioner on tensile bond strength to dentin prepared with different types of burs. A self-etching primer system, Mac-Bond II (MB, Tokuyama Dental) and a phosphoric acid etching system, Single Bond (SB, 3M) were used for conditioning. Twenty-four extracted intact human molars were ground flat to expose occlusal dentin. After the dentin surfaces were polished with #600 SiC paper, the teeth were randomly divided into a control group and three experimental groups according to the bur grits used: #600 SiC paper only as the control, fine cut steel bur (SB600), crosscut steel bur (SB703) and regular grit diamond bur (DB) mounted in a dental handpiece utilizing water cooling. The dentin surfaces were treated with one of two adhesive systems, then composite buildups were done with Clearfil AP-X (Kuraray Medical). After soaking the bond specimens for 24 hours in 37 degrees C water, multiple vertical serial sections (0.7 mm thick, 7-8 slices per one tooth) were made, trimmed to form an hour-glass shape with a 1.0 mm2 cross-section and tensile bond strengths were determined at a crosshead speed of 1 mm/minute. Statistical analysis was made using one and two-way ANOVA and Fisher's PLSD test (p<0.05). Six additional molars were used for SEM observations of the dentin surfaces of each group before and after treatment with the self-etching primer of MB, and another four teeth were used to observe the resin-dentin interface of each group of SB. Using MB, the DB group produced the lowest tensile bond strength (TBS) among the groups that received bur preparation, and there were no statistical differences among SB600, SB703 and the control. For SB, the TBS of SB703 was the highest, and there were no statistical differences among the other groups and the control. The influence of the method used to prepare dentin for micro-tensile bond strength testing was dependent on the adhesive system used.

  13. Mixed matrix membranes with HF acid etched ZSM-5 for ethanol/water separation: Preparation and pervaporation performance

    NASA Astrophysics Data System (ADS)

    Zhan, Xia; Lu, Juan; Tan, Tingting; Li, Jiding

    2012-10-01

    The mixed matrix membranes (MMMs) were prepared from crosslinked PDMS incorporated with HF acid etched ZSM-5. ZSM-5 zeolite was etched with a series of HF aqueous-acetone solution and characterized by SEM, BET, XRD and FT-IR. It was found that HF etching process was very effective for removing organic impurities in zeolite and micro-pores were observed out of the surface of zeolite particles, which enhanced the hydrophobicity and surface roughness of ZSM-5 successfully. Both tensile strength and swelling resistance of ZSM-5/PDMS MMMs increased with the rising concentration of HF solution, which can mainly be attributed to the improved zeolite-PDMS interfacial adhesion resulted from the intrusion of PDMS into micro-pores out of the ZSM-5 surface. Subsequently, the sorption experiment was performed with the results suggesting preferential sorption of ethanol by MMMs. Moreover, the sorption selectivity of ZSM-5/PDMS MMMs increased notably as the concentration of HF solution increased. The pervaporation performance of ethanol/water mixtures using MMMs was also investigated in detail. The MMMs filled with etched ZSM-5 showed much better selectivity than that filled with non-etched ones, with a little expense of permeability. It was found that with the same zeolite loading, increasing the HF acid concentration in etching process enhanced the zeolite-PDMS interfacial adhesion which promoted the ethanol selectivity of MMMs, while depressed the total permeation flux a little. In addition, both ethanol permeation and the selectivity increased with an increase of the zeolite loading from 10% to 30%. Nevertheless, excessive zeolite loading or decreasing thickness of selective layer led to the poor selectivity to ethanol. A decline of the ethanol selectivity was also observed as the feed ethanol concentration as well as feed temperature increased.

  14. Effect of a fluoride-releasing self-etch acidic primer on the shear bond strength of orthodontic brackets.

    PubMed

    Bishara, Samir E; Ajlouni, Raed; Laffoon, John F; Warren, John J

    2002-06-01

    Conventional adhesive systems use three different agents--an enamel conditioner, a primer solution, and an adhesive resin--during the bonding of orthodontic brackets to enamel. A unique characteristic of some new bonding systems in operative dentistry is that they combine the conditioning and priming agents into a single application. Combining conditioning and priming saves time and should be more cost-effective to the clinician and indirectly to the patient. The purpose of this study was to assess and compare the effects of self-etching primers, including a fluoride-releasing primer, on the shear bond strength of orthodontic brackets. The brackets were bonded to extracted human teeth according to one of four protocols. In group 1 (control), teeth were etched with 37% phosphoric acid; after the sealant was applied, the brackets were bonded with Transbond XT (3M Unitek, Monrovia, Calif) and light cured for 20 seconds. In group 2, a self-etch acidic primer (3M ESPE, St Paul, Minn) was applied as suggested by the manufacturer, and the brackets were then bonded with Transbond XT as in the first group. In group 3, an experimental self-etch primer EXL #547 (3M ESPE) was applied to the teeth as suggested by the manufacturer, and the brackets were then bonded as in groups 1 and 2. In group 4, a fluoride-releasing self-etch primer, One-Up Bond F (J. Mortia, USA Inc. Irvine, Calif) that also has a novel dye-sensitized photo polymerization initiator system was applied as suggested by the manufacturer, and the brackets were then bonded as in the other groups. The present in vitro findings indicated that the shear bond strengths of the four groups were significantly different (P = .001). Duncan multiple range tests indicated that One-Up Bond F (mean +/- SD strength, 5.1+/-2.5 MPa) and Prompt L-Pop (strength, 7.1+/-4.4 MPa) had significantly lower shear bond strengths than both the EXL #547 self-etch primer (strength, 9.7+/-3.7 MPa) or the phosphoric acid etch and the

  15. Optical investigation of the intergrowth structure and accessibility of Brønsted acid sites in etched SSZ-13 zeolite crystals by confocal fluorescence microscopy.

    PubMed

    Sommer, Linn; Svelle, Stian; Lillerud, Karl Petter; Stöcker, Michael; Weckhuysen, Bert M; Olsbye, Unni

    2010-11-02

    Template decomposition followed by confocal fluorescence microscopy reveals a tetragonal-pyramidal intergrowth of subunits in micrometer-sized nearly cubic SSZ-13 zeolite crystals. In order to accentuate intergrowth boundaries and defect-rich areas within the individual large zeolite crystals, a treatment with an etching NaOH solution is applied. The defective areas are visualized by monitoring the spatial distribution of fluorescent tracer molecules within the individual SSZ-13 crystals by confocal fluorescence microscopy. These fluorescent tracer molecules are formed at the inner and outer crystal surfaces by utilizing the catalytic activity of the zeolite in the oligomerization reaction of styrene derivatives. This approach reveals various types of etching patterns that are an indication for the defectiveness of the studied crystals. We can show that specially one type of crystals, denoted as core-shell type, is highly accessible to the styrene molecules after etching. Despite the large crystal dimensions, the whole core-shell type SSZ-13 crystal is utilized for catalytic reaction. Furthermore, the confocal fluorescence microscopy measurements indicate a nonuniform distribution of the catalytically important Brønsted acid sites underlining the importance of space-resolved measurements.

  16. Characterization and adsorption properties of diatomaceous earth modified by hydrofluoric acid etching.

    PubMed

    Tsai, Wen-Tien; Lai, Chi-Wei; Hsien, Kuo-Jong

    2006-05-15

    This work was a study of the chemical modification of diatomaceous earth (DE) using hydrofluoric acid (HF) solution. Under the experimental conditions investigated, it was found that HF under controlled conditions significantly etched inward into the interior of the existing pore structure in the clay mineral due to its high content of silica, leaving a framework possessing a larger BET surface area (ca. 10 m2 g(-1)) in comparison with that (ca. 4 m2 g(-1)) of its precursor (i.e., DE). Further, the results indicated that the HF concentration is a more determining factor in creating more open pores than other process parameters (temperature, holding time, and solid/liquid ratio). This observation was also in close agreement with the examinations by the silicon analysis, scanning electron microscopy, X-ray diffraction, and Fourier transform infrared spectroscopy. The adsorption kinetics and the adsorption isotherm of methylene blue onto the resulting clay adsorbent can be well described by a pseudo-second-order reaction model and the Freundlich model, respectively.

  17. Plasma treatment of dentin surfaces for improving self-etching adhesive/dentin interface bonding

    PubMed Central

    Dong, Xiaoqing; Li, Hao; Chen, Meng; Wang, Yong; Yu, Qingsong

    2015-01-01

    This study is to evaluate plasma treatment effects on dentin surfaces for improving self-etching adhesive and dentin interface bonding. Extracted unerupted human third molars were used after crown removal to expose dentin. One half of each dentin surface was treated with atmospheric non-thermal argon plasmas, while another half was untreated and used as the same tooth control. Self-etching adhesive and universal resin composite was applied to the dentin surfaces as directed. After restoration, the adhesive-dentin bonding strength was evaluated by micro-tensile bonding strength (μTBS) test. Bonding strength data was analyzed using histograms and Welch’s t-test based on unequal variances. μTBS test results showed that, with plasma treatment, the average μTBS value increased to 69.7±11.5 MPa as compared with the 57.1±17.5 MPa obtained from the untreated controls. After 2 months immersion of the restored teeth in 37 °C phosphate buffered saline (PBS), the adhesive-dentin bonding strengths of the plasma-treated specimens slightly decreased from 69.7±11.5 MPa to 63.9±14.4 MPa, while the strengths of the untreated specimens reduced from 57.1±17.5 MPa to 48.9±14.6 MPa. Water contact angle measurement and scanning electron microscopy (SEM) examination verified that plasma treatment followed by water rewetting could partially open dentin tubules, which could enhance adhesive penetration to form thicker hybrid layer and longer resin tags and consequently improve the adhesive/dentin interface quality. PMID:26273561

  18. Effects of dextrose and lipopolysaccharide on the corrosion behavior of a Ti-6Al-4V alloy with a smooth surface or treated with double-acid-etching.

    PubMed

    Faverani, Leonardo P; Assunção, Wirley G; de Carvalho, Paulo Sérgio P; Yuan, Judy Chia-Chun; Sukotjo, Cortino; Mathew, Mathew T; Barao, Valentim A

    2014-01-01

    Diabetes and infections are associated with a high risk of implant failure. However, the effects of such conditions on the electrochemical stability of titanium materials remain unclear. This study evaluated the corrosion behavior of a Ti-6Al-4V alloy, with a smooth surface or conditioned by double-acid-etching, in simulated body fluid with different concentrations of dextrose and lipopolysaccharide. For the electrochemical assay, the open-circuit-potential, electrochemical impedance spectroscopy, and potentiodynamic test were used. The disc surfaces were characterized by scanning electron microscopy and atomic force microscopy. Their surface roughness and Vickers microhardness were also tested. The quantitative data were analyzed by Pearson's correlation and independent t-tests (α = 0.05). In the corrosion parameters, there was a strong lipopolysaccharide correlation with the Ipass (passivation current density), Cdl (double-layer capacitance), and Rp (polarization resistance) values (p<0.05) for the Ti-6Al-4V alloy with surface treatment by double-acid-etching. The combination of dextrose and lipopolysaccharide was correlated with the Icorr (corrosion current density) and Ipass (p<0.05). The acid-treated groups showed a significant increase in Cdl values and reduced Rp values (p<0.05, t-test). According to the topography, there was an increase in surface roughness (R2 = 0.726, p<0.0001 for the smooth surface; R2 = 0.405, p = 0.036 for the double-acid-etching-treated surface). The microhardness of the smooth Ti-6Al-4V alloy decreased (p<0.05) and that of the treated Ti-6Al-4V alloy increased (p<0.0001). Atomic force microscopy showed changes in the microstructure of the Ti-6Al-4V alloy by increasing the surface thickness mainly in the group associated with dextrose and lipopolysaccharide. The combination of dextrose and lipopolysaccharide affected the corrosion behavior of the Ti-6Al-4V alloy surface treated with double-acid-etching. However, no

  19. Early bone response to sandblasted, dual acid-etched and H2O2/HCl treated titanium implants: an experimental study in the rabbit.

    PubMed

    He, F M; Yang, G L; Li, Y N; Wang, X X; Zhao, S F

    2009-06-01

    The aim of this study was to evaluate the influence of a roughened H(2)O(2)/HCl heat-treated titanium surface on peri-implant bone formation at an early stage in vivo. 24 Ti(6)Al(4)V alloy implants were used; half were treated by sandblasted and dual acid-etched treatments (control group), while the others were treated by sandblasted, dual acid-etched and H(2)O(2)/HCl heat treatments (test group). The morphology and roughness were analyzed by field emission SEM and atomic force microscopy. The implants were inserted into the femora of 12 adult white rabbits. After 2 and 4 weeks, femora block specimens were prepared for histological and histomorphometric analysis. SEM micrographs showed that multilevel and different sized pits were formed on both surfaces. New bone formation was observed on both implant surfaces. Test implants demonstrated a greater mean percentage of bone-implant contact as compared with controls at 2 (46.84 vs. 41.81, p=0.000) and 4 weeks (49.43 vs. 44.87, p=0.006) of healing. It is concluded that the H(2)O(2)/HCl heat-treated rough titanium surface promoted enhanced bone apposition during the early stages of new bone formation around the implant.

  20. Effect of acid etching duration on tensile bond strength of composite resin bonded to erbium:yttrium-aluminium-garnet laser-prepared dentine. Preliminary study.

    PubMed

    Chousterman, M; Heysselaer, D; Dridi, S M; Bayet, F; Misset, B; Lamard, L; Peremans, A; Nyssen-Behets, C; Nammour, S

    2010-11-01

    The purpose of this study was to compare the tensile bond strength of composite resin bonded to erbium:yttrium-aluminium-garnet (Er:YAG) laser-prepared dentine after different durations of acid etching. The occlusal third of 68 human third molars was removed in order to expose the dentine surface. The teeth were randomly divided into five groups: group B (control group), prepared with bur and total etch system with 15 s acid etching [37% orthophosphoric acid (H(3)PO(4))]; group L15, laser photo-ablated dentine (200 mJ) (laser irradiation conditions: pulse duration 100 micros, air-water spray, fluence 31.45 J/ cm(2), 10 Hz, non-contact hand pieces, beam spot size 0.9 mm, irradiation speed 3 mm/s, and total irradiation time 2 x 40 s); group L30, laser prepared, laser conditioned and 30 s acid etching; group L60, laser prepared, laser conditioned and 60 s acid etching; group L90, laser prepared, laser conditioned and 90 s acid etching. A plot of composite resin was bonded onto each exposed dentine and then tested for tensile bond strength. The values obtained were statistically analysed by analysis of variance (ANOVA) coupled with the Tukey-Kramer test at the 95% level. A 90 s acid etching before bonding showed the best bonding value (P < 0.05) when compared with all the other groups including the control group. There is no significance difference between other groups, nor within each group and the control group. There was a significant increase in tensile bond strength of the samples acid etched for 90 s.

  1. Comparison of bond strength and surface morphology of dental enamel for acid and Nd-YAG laser etching

    NASA Astrophysics Data System (ADS)

    Parmeswearan, Diagaradjane; Ganesan, Singaravelu; Ratna, P.; Koteeswaran, D.

    1999-05-01

    Recently, laser pretreatment of dental enamel has emerged as a new technique in the field of orthodontics. However, the changes in the morphology of the enamel surface is very much dependent on the wavelength of laser, emission mode of the laser, energy density, exposure time and the nature of the substance absorbing the energy. Based on these, we made a comparative in vitro study on laser etching with acid etching with reference to their bond strength. Studies were conducted on 90 freshly extracted, non carious, human maxillary or mandibular anteriors and premolars. Out of 90, 60 were randomly selected for laser irradiation. The other 30 were used for conventional acid pretreatment. The group of 60 were subjected to Nd-YAG laser exposure (1060 nm, 10 Hz) at differetn fluences. The remaining 30 were acid pretreated with 30% orthophosphoric acid. Suitable Begg's brackets were selected and bound to the pretreated surface and the bond strength were tested using Instron testing machine. The bond strength achieved through acid pretreatment is found to be appreciably greater than the laser pretreated tooth. Though the bond strength achieved through the acid pretreated tooth is found to be significantly greater than the laser pretreated specimens, the laser pretreatement is found to be successful enough to produce a clinically acceptable bond strength of > 0.60 Kb/mm. Examination of the laser pre-treated tooth under SEM showed globule formation which may produce the mechanical interface required for the retention of the resin material.

  2. Effect of fluoride on the morphology of calcium phosphate crystals grown on acid-etched human enamel.

    PubMed

    Fan, Y; Sun, Z; Moradian-Oldak, J

    2009-01-01

    The aim of this study was to examine the effect of fluoride ion concentration on the morphology of calcium phosphate crystals grown on acid-etched enamel as a model for tooth enamel erosion. Samples were immersed in calcification solution for 16 h and changes in crystal morphology were monitored by field emission scanning electron microscopy. Without fluoride, plate-like octacalcium phosphate crystals (20 nm thick, 2-10 microm wide) were formed. With 1-10 mg/l fluoride, arrays of denser needle-like nanocrystals (20-30 nm wide, >500 nm in length) were formed. We conclude that there is a minimal fluoride concentration (1 mg/l) that dramatically affects the morphology of calcium phosphate crystals grown on etched enamel in vitro.

  3. Effect of Fluoride on the Morphology of Calcium Phosphate Crystals Grown on Acid-Etched Human Enamel

    PubMed Central

    Fan, Y.; Sun, Z.; Moradian-Oldak, J.

    2009-01-01

    The aim of this study was to examine the effect of fluoride ion concentration on the morphology of calcium phosphate crystals grown on acid-etched enamel as a model for tooth enamel erosion. Samples were immersed in calcification solution for 16 h and changes in crystal morphology were monitored by field emission scanning electron microscopy. Without fluoride, plate-like octacalcium phosphate crystals (20 nm thick, 2–10 μm wide) were formed. With 1–10 mg/l fluoride, arrays of denser needle-like nanocrystals (20–30 nm wide, >500 nm in length) were formed. We conclude that there is a minimal fluoride concentration (1 mg/l) that dramatically affects the morphology of calcium phosphate crystals grown on etched enamel in vitro. PMID:19321991

  4. Micro/nanofabrication of poly({sub L}-lactic acid) using focused ion beam direct etching

    SciTech Connect

    Oyama, Tomoko Gowa; Nagasawa, Naotsugu; Taguchi, Mitsumasa; Hinata, Toru; Washio, Masakazu; Oshima, Akihiro; Tagawa, Seiichi

    2013-10-14

    Micro/nanofabrication of biocompatible and biodegradable poly({sub L}-lactic acid) (PLLA) using focused Ga ion beam direct etching was evaluated for future bio-device applications. The fabrication performance was determined with different ion fluences and fluxes (beam currents), and it was found that the etching speed and fabrication accuracy were affected by irradiation-induced heat. Focused ion beam (FIB)-irradiated surfaces were analyzed using micro-area X-ray photoelectron spectroscopy. Owing to reactions such as the physical sputtering of atoms and radiation-induced decomposition, PLLA was gradually carbonized with increasing C=C bonds. Controlled micro/nanostructures of PLLA were fabricated with C=C bond-rich surfaces expected to have good cell attachment properties.

  5. Influence of duration of phosphoric acid pre-etching on bond durability of universal adhesives and surface free-energy characteristics of enamel.

    PubMed

    Tsujimoto, Akimasa; Barkmeier, Wayne W; Takamizawa, Toshiki; Watanabe, Hidehiko; Johnson, William W; Latta, Mark A; Miyazaki, Masashi

    2016-08-01

    The purpose of this study was to evaluate the influence of duration of phosphoric acid pre-etching on the bond durability of universal adhesives and the surface free-energy characteristics of enamel. Three universal adhesives and extracted human molars were used. Two no-pre-etching groups were prepared: ground enamel; and enamel after ultrasonic cleaning with distilled water for 30 s to remove the smear layer. Four pre-etching groups were prepared: enamel pre-etched with phosphoric acid for 3, 5, 10, and 15 s. Shear bond strength (SBS) values of universal adhesive after no thermal cycling and after 30,000 or 60,000 thermal cycles, and surface free-energy values of enamel surfaces, calculated from contact angle measurements, were determined. The specimens that had been pre-etched showed significantly higher SBS and surface free-energy values than the specimens that had not been pre-etched, regardless of the aging condition and adhesive type. The SBS and surface free-energy values did not increase for pre-etching times of longer than 3 s. There were no significant differences in SBS values and surface free-energy characteristics between the specimens with and without a smear layer. The results of this study suggest that phosphoric acid pre-etching of enamel improves the bond durability of universal adhesives and the surface free-energy characteristics of enamel, but these bonding properties do not increase for phosphoric acid pre-etching times of longer than 3 s.

  6. Effect of pretreatment with mildly acidic hypochlorous acid on adhesion to caries-affected dentin using a self-etch adhesive.

    PubMed

    Kunawarote, Sitthikorn; Nakajima, Masatoshi; Foxton, Richard M; Tagami, Junji

    2011-02-01

    Caries-affected dentin is covered with a thicker and organically enriched smear layer than normal dentin. This may affect the demineralization ability and the infiltration of self-etch adhesives, thus reducing the efficacy of bonding to caries-affected dentin. This study evaluated the adhesion of a two-step self-etching adhesive to normal and caries-affected dentin after pretreatment with mildly acidic hypochlorous acid (HOCl) solutions. We used a microtensile bond strength (μTBS) test to compare the μTBS of Clearfil SE Bond to either caries-affected dentin or to normal dentin, after pretreatment for 5 s with one of three solutions (806 mM NaOCl, or 0.95 or 1.91 mM HOCl). The μTBS of the self-etch adhesive was significantly lower to caries-affected dentin than to normal dentin. Pretreatment with 0.95 mM HOCl improved the μTBS of the self-etch adhesive to caries-affected dentin, but there was no significant difference compared with normal dentin. On the other hand, pretreatment with 806 mM NaOCl or 1.91 mM HOCl did not demonstrate a significant improvement in the μTBS to caries-affected dentin. None of the pretreatments demonstrated a negative effect on adhesion to normal dentin.

  7. Morphology of resin-dentin interfaces after Er,Cr:YSGG laser and acid etching preparation and application of different bonding systems.

    PubMed

    Beer, Franziska; Buchmair, Alfred; Körpert, Wolfram; Marvastian, Leila; Wernisch, Johann; Moritz, Andreas

    2012-07-01

    The goal of this study was to show the modifications in the ultrastructure of the dentin surface morphology following different surface treatments. The stability of the adhesive compound with dentin after laser preparation compared with conventional preparation using different bonding agents was evaluated. An Er,Cr:YSGG laser and 36% phosphoric acid in combination with various bonding systems were used. A total of 100 caries-free human third molars were used in this study. Immediately after surgical removal teeth were cut using a band saw and 1-mm thick dentin slices were created starting at a distance of 4 mm from the cusp plane to ensure complete removal of the enamel. The discs were polished with silicon carbide paper into rectangular shapes to a size of 6 × 4 mm (±0,2 mm).The discs as well as the remaining teeth stumps were stored in 0.9% NaCl at room temperature. The specimens were divided into three main groups (group I laser group, group II etch group, group III laser and etch group) and each group was subdivided into three subgroups which were allocated to the different bonding systems (subgroup A Excite, subgroup B Scotchbond, subgroup C Syntac). Each disc and the corresponding tooth stump were treated in the same way. After preparation the bonding composite material was applied according to the manufacturers' guidelines in a hollow tube of 2 mm diameter to the disc as well as to the corresponding tooth stump. Shear bond strength testing and environmental scanning electron microscopy were used to assess the morphology and stability of the resin-dentin interface. The self-etching bonding system showed the highest and the most constant shear values in all three main groups, thus enabling etching with phosphoric acid after laser preparation to be avoided. Thus we conclude that laser preparation creates a surface texture that allows prediction of the quality of the restoration without the risk of negative influences during the following treatment steps. This

  8. Surface Topographical Changes of a Failing Acid-Etched Long-Term in Function Retrieved Dental Implant.

    PubMed

    Monje, Alberto; González-García, Raúl; Fernández-Calderón, María Coronada; Hierro-Oliva, Margarita; González-Martín, María Luisa; Del Amo, Fernando Suarez-Lopez; Galindo-Moreno, Pablo; Wang, Hom-Lay; Monje, Florencio

    2016-02-01

    The aim of the present study was to report the main topographical and chemical changes of a failing 18-year in function retrieved acid-etching implant in the micro- and nanoscales. A partially edentulous 45 year old rehabilitated with a dental implant at 18 years of age exhibited mobility. After careful examination, a 3.25 × 13-mm press-fit dental implant was retrieved. Scanning electron microscope (SEM) analysis was carried out to study topographical changes of the retrieved implant compared with an unused implant with similar topographical characteristics. Moreover, X-ray photoelectron spectroscopy (XPS) analysis was used to study the surface composition of the retrieved failing implant. Clear changes related to the dual dioxide layer are present as visible in ≥×500 magnification. In addition, it was found that, for the retrieved implant, the surface composition consisted mainly of Ti2p, O1s, C1s, and Al2p. Also, a meaningful decrease of N and C was noticed, whereas the peaks of Ti2p, Al2p, and O1s increased when analyzing deeper (up to ×2000s) in the sample. It was shown that the superficial surface of a retrieved press-fit dual acid-etched implant 18 years after placement is impaired. However, the causes and consequences for these changes cannot be determined.

  9. Relation between etch-pit morphology and step retreat velocity on a calcite surface in aspartic acid solution

    NASA Astrophysics Data System (ADS)

    Yoshino, Toru; Kagi, Hiroyuki; Kamiya, Natsumi; Kokawa, Ryohei

    2010-04-01

    Effects of L-aspartic acid ( L-Asp) on dissolution of calcite were investigated. The step retreat velocity and dissolution rate of calcite were measured simultaneously using an AFM flow-through system. The etch-pit morphology of calcite was observed using confocal laser scanning microscopy. Results show that the etch-pit morphologies changed drastically depending on the L-Asp concentration ([ L-Asp]) in the order of rhomboidal, pentagonal, and triangular (not perfectly, but retaining an extra step). The change in obtuse step directions and appearance of the [0 1 0] step triggered these morphological changes. Addition of L-Asp accelerated all step retreats at [ L-Asp]<0.01 M, which implied the effect of L-Asp on the diffusive barrier. In contrast, at [ L-Asp]>0.01 M, L-Asp inhibited the retreats of obtuse steps and [0 1 0] step, although the retreat velocities of acute steps were constant irrespective of [ L-Asp]. These results suggest that the directional changes and the inhibition of retreat velocities of obtuse steps were attributed to the generation of [ 4 1 1] and [4 5 1] steps caused by L-Asp. Moreover, we confirmed the preferential effects of L-Asp on the [4 8 1] + to [ 4 4 1] ± step edge, and proposed the preferential effects of L-Asp on the [ 4 1 1] to [4 5 1] step edge.

  10. Effect of etching with cysteamine assisted phosphoric acid on gallium nitride surface oxide formation

    NASA Astrophysics Data System (ADS)

    Wilkins, S. J.; Paskova, T.; Ivanisevic, A.

    2013-08-01

    In-situ functionalization of polar GaN was performed by adding cysteamine to a phosphoric acid etchant in order to study its effect on photoluminescence and oxide formation on the surfaces. The functionalization was characterized by atomic force microscopy, x-ray photoelectron spectroscopy, photoluminescence (PL), and water contact angle measurements. Two sets of polar GaN samples with different dislocation densities were evaluated, thin GaN layers residing on sapphire and thick free-standing GaN separated from sapphire substrate aiming to reveal the effect of material quality on in-situ functionalization. The addition of cysteamine to the phosphoric acid solution was found to result in: (i) decreased surface roughness, (ii) no change to hydrophobicity, (iii) decreased oxygen content especially at high-temperature treatments. The effect of the in-situ functionalization on the PL efficiency was more pronounced in the free-standing sample than in the film residing on the sapphire, which was attributed to a higher crystal quality free from strain.

  11. Comparison of shear bond strength and surface structure between conventional acid etching and air-abrasion of human enamel.

    PubMed

    Olsen, M E; Bishara, S E; Damon, P; Jakobsen, J R

    1997-11-01

    Recently, air-abrasion technology has been examined for potential applications within dentistry, including the field of orthodontics. The purpose of this study was to compare the traditional acid-etch technique with an air-abrasion surface preparation technique, with two different sizes of abrading particles. The following parameters were evaluated: (a) shear bond strength, (b) bond failure location, and (c) enamel surface preparation, as viewed through a scanning electron microscope. Sixty extracted human third molars were pumiced and divided into three groups of 20. The first group was etched with a 37% phosphoric acid gel for 30 seconds, rinsed for 30 seconds, and dried for 20 seconds. The second and third groups were air-abraded with (a) a 50 microm particle and (b) a 90 microm particle of aluminum oxide, with the Micro-etcher microabrasion machine (Danville Engineering Inc.). All three groups had molar stainless steel orthodontic brackets bonded to the buccal surface of each tooth with Transbond XT bonding system (3M Unitek). A Zwick Universal Testing Machine (Calitek Corp.) was used to determine shear bond strengths. The analysis of variance was used to compare the three groups. The Adhesive Remnant Index (ARI) was used to evaluate the residual adhesive on the enamel after bracket removal. The chi square test was used to evaluate differences in the ARI scores among the groups. The significance for all tests was predetermined at p < or = 0.05. The results indicated that there was a significant difference in shear bond strength among the three groups (p = 0.0001). The Duncan Multiple Range test showed a significant decrease in shear bond strength in the air-abraded groups. The chi square test revealed significant differences among the ARI scores of the acid-etched group and the air-abraded groups (chi(2) = 0.0001), indicating no adhesive remained on the enamel surface after debonding when air-abrasion was used. In conclusion, the current findings indicate that

  12. UV-induced graft polymerization of acrylic acid in the sub-micronchannels of oxidized PET track-etched membrane

    NASA Astrophysics Data System (ADS)

    Korolkov, Ilya V.; Mashentseva, Anastassiya A.; Güven, Olgun; Taltenov, Abzal A.

    2015-12-01

    In this article, we report on functionalization of track-etched membrane based on poly(ethylene terephthalate) (PET TeMs) oxidized by advanced oxidation systems and by grafting of acrylic acid using photochemical initiation technique for the purpose of increasing functionality thus expanding its practical application. Among advanced oxidation processes (H2O2/UV) system had been chosen to introduce maximum concentration of carboxylic acid groups. Benzophenone (BP) photo-initiator was first immobilized on the surfaces of cylindrical pores which were later filled with aq. acrylic acid solution. UV-irradiation from both sides of PET TeMs has led to the formation of grafted poly(acrylic acid) (PAA) chains inside the membrane sub-micronchannels. Effect of oxygen-rich surface of PET TeMs on BP adsorption and subsequent process of photo-induced graft polymerization of acrylic acid (AA) were studied by ESR. The surface of oxidized and AA grafted PET TeMs was characterized by UV-vis, ATR-FTIR, XPS spectroscopies and by SEM.

  13. Comparison of alkaline phosphatase activity of MC3T3-E1 cells cultured on different Ti surfaces: modified sandblasted with large grit and acid-etched (MSLA), laser-treated, and laser and acid-treated Ti surfaces

    PubMed Central

    Li, Lin-Jie; Kim, So-Nam

    2016-01-01

    PURPOSE In this study, the aim of this study was to evaluate the effect of implant surface treatment on cell differentiation of osteoblast cells. For this purpose, three surfaces were compared: (1) a modified SLA (MSLA: sand-blasted with large grit, acid-etched, and immersed in 0.9% NaCl), (2) a laser treatment (LT: laser treatment) titanium surface and (3) a laser and acid-treated (LAT: laser treatment, acid-etched) titanium surface. MATERIALS AND METHODS The MSLA surfaces were considered as the control group, and LT and LAT surfaces as test groups. Alkaline phosphatase expression (ALP) was used to quantify osteoblastic differentiation of MC3T3-E1 cell. Surface roughness was evaluated by a contact profilometer (URFPAK-SV; Mitutoyo, Kawasaki, Japan) and characterized by two parameters: mean roughness (Ra) and maximum peak-to-valley height (Rt). RESULTS Scanning electron microscope revealed that MSLA (control group) surface was not as rough as LT, LAT surface (test groups). Alkaline phosphatase expression, the measure of osteoblastic differentiation, and total ALP expression by surface-adherent cells were found to be highest at 21 days for all three surfaces tested (P<.05). Furthermore, ALP expression levels of MSLA and LAT surfaces were significantly higher than expression levels of LT surface-adherent cells at 7, 14, and 21 days, respectively (P<.05). However, ALP expression levels between MSLA and LAT surface were equal at 7, 14, and 21 days (P>.05). CONCLUSION This study suggested that MSLA and LAT surfaces exhibited more favorable environment for osteoblast differentiation when compared with LT surface, the results that are important for implant surface modification studies. PMID:27350860

  14. Influence of pre-surface treatment on the morphology of silicon nanowires fabricated by metal-assisted etching

    NASA Astrophysics Data System (ADS)

    Shiu, Shu-Chia; Lin, Shin-Bo; Hung, Shih-Che; Lin, Ching-Fuh

    2011-01-01

    Herein we demonstrate an improved metal-assisted etching method to achieve highly dense and uniform silicon nanowire arrays. A pre-surface treatment was applied on a silicon wafer before the process of metal-assisted etching in silver nitrate and hydrogen fluoride solution. The treatment made silver ion continuously reduce on silver nuclei adherence on the silicon surface, leading to formation of dense silver nanoparticles. Silver nanoparticles acting as local redox centers cause the formation of dense silicon nanowire arrays. In contrast, an H-terminated silicon surface made silver ion reduce uniformly on the silicon surface to form silver flakes. The silicon nanowires fabricated with a pre-surface treatment reveals higher density than those fabricated without a pre-surface treatment. The volume fraction improves from 18 to 38%. This improvement reduces the solar-weighted reflectance to as low as 3.3% for silicon nanowires with a length of only 0.87 μm. In comparison, the silicon nanowires fabricated without a pre-surface treatment have to be as long as 1.812 μm to achieve the same reflectance.

  15. An In Vitro Comparison of the Bond Strength of Composite to Superficial and Deep Dentin, Treated With Er:YAG Laser Irradiation or Acid-Etching.

    PubMed

    Alaghehmand, Homayoon; Nezhad Nasrollah, Fatemeh; Nokhbatolfoghahaei, Hanieh; Fekrazad, Reza

    2016-01-01

    Introduction: The aim of this study was to compare the micro-shear bond strength of composite resin on superficial and deep dentin after conditioning with phosphoric acid and Erbium-Doped Yttrium Aluminum Garnet (Er:YAG) laser. Methods: Thirty human molars were selected, roots were removed and crowns were bisected to provide a total of 60 half-crowns. Specimens were ground to expose superficial and deep dentin. Samples were assigned to six groups: (1) AS (acid etching of superficial dentin); (2) AD (acid etching of deep dentin); (3) LS (Er:YAG laser irradiation on superficial dentin); (4) LD (Er:YAG laser irradiation on deep dentin); (5) LAS (Er:YAG laser irradiation on superficial dentin followed by acid etching); (6) LAD (Er:YAG laser irradiation on deep dentin followed by acid etching) The adhesive protocol was performed. Samples were thermocycled and micro-shear bond strength was tested to failure. The data were submitted to statistical analysis with one-way analysis of variance (ANOVA) and Tukey post hoc test. Results: The AS group, demonstrated the greatest amount of micro-shear bond strength. Statistical analysis showed a decrease in bond strength in laser-treated groups which was more significant for deep dentin. Conclusion: Preparation of dentin with laser did not improve bonding to superficial and deep dentin.

  16. An In Vitro Comparison of the Bond Strength of Composite to Superficial and Deep Dentin, Treated With Er:YAG Laser Irradiation or Acid-Etching

    PubMed Central

    Alaghehmand, Homayoon; Nezhad Nasrollah, Fatemeh; Nokhbatolfoghahaei, Hanieh; Fekrazad, Reza

    2016-01-01

    Introduction: The aim of this study was to compare the micro-shear bond strength of composite resin on superficial and deep dentin after conditioning with phosphoric acid and Erbium-Doped Yttrium Aluminum Garnet (Er:YAG) laser. Methods: Thirty human molars were selected, roots were removed and crowns were bisected to provide a total of 60 half-crowns. Specimens were ground to expose superficial and deep dentin. Samples were assigned to six groups: (1) AS (acid etching of superficial dentin); (2) AD (acid etching of deep dentin); (3) LS (Er:YAG laser irradiation on superficial dentin); (4) LD (Er:YAG laser irradiation on deep dentin); (5) LAS (Er:YAG laser irradiation on superficial dentin followed by acid etching); (6) LAD (Er:YAG laser irradiation on deep dentin followed by acid etching) The adhesive protocol was performed. Samples were thermocycled and micro-shear bond strength was tested to failure. The data were submitted to statistical analysis with one-way analysis of variance (ANOVA) and Tukey post hoc test. Results: The AS group, demonstrated the greatest amount of micro-shear bond strength. Statistical analysis showed a decrease in bond strength in laser-treated groups which was more significant for deep dentin. Conclusion: Preparation of dentin with laser did not improve bonding to superficial and deep dentin. PMID:28144437

  17. Changes in the surface of bone and acid-etched and sandblasted implants following implantation and removal

    PubMed Central

    Eroglu, Cennet Neslihan; Ertugrul, Abdullah Seckin; Eskitascioglu, Murat; Eskitascioglu, Gurcan

    2016-01-01

    Objective: The aim of this study was to determine whether there are any changes in the surface of bone or implant structures following the removal of a screwed dental implant. Materials and Methods: For this, six individual samples of acid-etched and sandblasted implants from three different manufacturers’ implant systems were used. They were screwed in a D1 bovine bone, and they were removed after primary stabilization. The bone and implant surfaces are evaluated with scanning electron microscope. Results: Through examination of the surfaces of the bone prior to implantation and of the used and unused implant surfaces, it was found that inhomogeneity in the implant surface can cause microcracking in the bone. Conclusions: This is attributed to the stress induced during the implantation of self-tapping implants and suggests that a tap drill may be required in some instances to protect the implant surface. PMID:27011744

  18. Redox buffered hydrofluoric acid etchant for the reduction of galvanic attack during release etching of MEMS devices having noble material films

    DOEpatents

    Hankins, Matthew G.

    2009-10-06

    Etchant solutions comprising a redox buffer can be used during the release etch step to reduce damage to the structural layers of a MEMS device that has noble material films. A preferred redox buffer comprises a soluble thiophosphoric acid, ester, or salt that maintains the electrochemical potential of the etchant solution at a level that prevents oxidation of the structural material. Therefore, the redox buffer preferentially oxidizes in place of the structural material. The sacrificial redox buffer thereby protects the exposed structural layers while permitting the dissolution of sacrificial oxide layers during the release etch.

  19. Photopolymerization of phosphoric acid ester-based self-etch dental adhesives

    PubMed Central

    ZHANG, Ying; WANG, Yong

    2014-01-01

    The objective of the study was to gain more understanding on the photopolymerization mechanism and the role of individual monomers in the polymerization behavior of a PAE-based self-etch adhesive system with the presence of HAp and water. The photo-polymerization process of the model adhesive system (2MP / HEMA) was monitored by using real-time attenuated total reflectance Fourier transform infrared (ATR/FT-IR) technique. The effect of monomer ratio, HAp incorporation, and water content were investigated. The degree of conversion (DC) and the polymerization rate (PR) of the adhesives were determined to evaluate the polymerization efficacy. The results showed that the DC and PR increased consistently as the 2MP content increased from 30% to 70%, while they declined drastically as the 2MP content was further elevated to 100%. The incorporation of HAp considerably increased the DC and PR; however, the increase in water content was found to have negative influence on the photopolymerization. PMID:23370865

  20. Photoelectrochemical etching of gallium nitride surface by complexation dissolution mechanism

    NASA Astrophysics Data System (ADS)

    Zhang, Miao-Rong; Hou, Fei; Wang, Zu-Gang; Zhang, Shao-Hui; Pan, Ge-Bo

    2017-07-01

    Gallium nitride (GaN) surface was etched by 0.3 M ethylenediamine tetraacetic acid disodium (EDTA-2Na) via photoelectrochemical etching technique. SEM images reveal the etched GaN surface becomes rough and irregular. The pore density is up to 1.9 × 109 per square centimeter after simple acid post-treatment. The difference of XPS spectra of Ga 3d, N 1s and O 1s between the non-etched and freshly etched GaN surfaces can be attributed to the formation of Ga-EDTA complex at the etching interface between GaN and EDTA-2Na. The proposed complexation dissolution mechanism can be broadly applicable to almost all neutral etchants under the prerequisite of strong light and electric field. From the point of view of environment, safety and energy, EDTA-2Na has obvious advantages over conventionally corrosive etchants. Moreover, as the further and deeper study of such nearly neutral etchants, GaN etching technology has better application prospect in photoelectric micro-device fabrication.

  1. Synergistic Effect of Atmospheric Pressure Plasma Pre-Treatment on Alkaline Etching of Polyethylene Terephthalate Fabrics and Films

    NASA Astrophysics Data System (ADS)

    A. Elabid Amel, E.; Guo, Ying; Shi, Jianjun; Ding, Ke; Zhang, Jing

    2016-04-01

    Dyeing of PET materials by traditional methods presents several problems. Plasma technology has received enormous attention as a solution for the environmental problems related with textile surface modifications, and there has been a rapid development and commercialization of plasma technology over the past decade. In this work, the synergistic effect of atmospheric pressure plasma on alkaline etching and deep coloring of dyeing properties on polyethylene terephthalate (PET) fabrics and films was investigated. The topographical changes of the PET surface were investigated by atomic force microscopy (AFM) images, which revealed a smooth surface morphology of the untreated sample whereas a high surface roughness for the plasma and/or alkaline treated samples. The effects of atmospheric pressure plasma on alkaline etching of the structure and properties of PET were investigated by means of differential scanning calorimetry (DSC), the main objective of performing DSC was to investigate the effect of the plasma pre-treatment on the Tg and Tm. Using a tensile strength tester YG065H and following a standard procedure the maximum force and elongation at maximum force of PET materials was investigated. Oxygen and argon plasma pre-treatment was found to increase the PET fabric weight loss rate. The color strength of PET fabrics was increased by various plasma pre-treatment times. The penetration of plasma and alkaline reactive species deep into the PET structure results in better dyeability and leaves a significant effect on the K/S values of the plasma pre-treated PET. It indicated that plasma pre-treatment has a great synergistic effect with the alkaline treatment of PET.

  2. Effect of a Cooling Step Treatment on a High-Voltage GaN LED During ICP Dry Etching

    NASA Astrophysics Data System (ADS)

    Lin, Yen-Sheng; Hsiao, Sheng-Yu; Tseng, Chun-Lung; Shen, Ching-Hsing; Chiang, Jung-Sheng

    2017-02-01

    In this study, a lower dislocation density for a GaN surface and a reduced current path are observed at the interface of a SiO2 isolation sidewall, using high-resolution transmission electron microscopy. This is grown using a 3-min cooling step treatment during inductivity coupled plasma dry etching. The lower forward voltage is measured, the leakage current decreases from 53nA to 32nA, and the maximum output power increases from 354.8 W to 357.2 W for an input current of 30 mA. The microstructure and the optoelectronic properties of high-voltage light-emitting-diodes is proven to be affected by the cooling step treatment, which allows enough time to release the thermal energy of the SiO2 isolation well.

  3. Comparison of Shear Bond Strength of Orthodontic Brackets Bonded to Enamel Prepared By Er:YAG Laser and Conventional Acid-Etching

    PubMed Central

    Hosseini, M.H.; Namvar, F.; Chalipa, J.; Saber, K.; Chiniforush, N.; Sarmadi, S.; Mirhashemi, A.H.

    2012-01-01

    Introduction: The purpose of this study was to compare shear bond strength (SBS) of orthodontic brackets bonded to enamel prepared by Er:YAG laser with two different powers and conventional acid-etching. Materials and Methods: Forty-five human premolars extracted for orthodontic purposes were randomly assigned to three groups based on conditioning method: Group 1- conventional etching with 37% phosphoric acid; Group 2- irradiation with Er:YAG laser at 1 W; and Group 3- irradiation with Er:YAG laser at 1.5 W. Metal brackets were bonded on prepared enamel using a light-cured composite. All groups were subjected to thermocycling process. Then, the specimens mounted in auto-cure acryle and shear bond strength were measured using a universal testing machine with a crosshead speed of 0.5 mm per second. After debonding, the amount of resin remaining on the teeth was determined using the adhesive remnant index (ARI) scored 1 to 5. One-way analysis of variance was used to compare shear bond strengths and the Kruskal-Wallis test was performed to evaluate differences in the ARI for different etching types. Results: The mean and standard deviation of conventional acid-etch group, 1W laser group and 1.5W laser group was 3.82 ± 1.16, 6.97 ± 3.64 and 6.93 ± 4.87, respectively. Conclusion: The mean SBS obtained with an Er:YAG laser operated at 1W or 1.5W is approximately similar to that of conventional etching. However, the high variability of values in bond strength of irradiated enamel should be considered to find the appropriate parameters for applying Er:YAG laser as a favorable alternative for surface conditioning. PMID:22924098

  4. Evaluation of modifying the bonding protocol of a new acid-etch primer on the shear bond strength of orthodontic brackets.

    PubMed

    Ajlouni, Raed; Bishara, Samir E; Oonsombat, Charuphan; Denehy, Gerald E

    2004-06-01

    The purpose of the study was to evaluate the shear bond strength of orthodontic brackets when light curing both the self-etch primer and the adhesive in one step. Fourty eight teeth were bonded with self-etch primer Angel I (3M/ESPE, St Paul, Minn) and divided into three groups. In group I (control), 16 teeth were stored in deionized water for 24 hours before debonding. In group II, 16 teeth were debonded within half-an-hour to simulate when the initial archwires were ligated. In group III, 16 additional teeth were bonded using exactly the same procedure as in groups I and II, but the light cure used for 10 seconds after applying the acid-etch primer was eliminated, and the light cure used for 20 seconds after the precoated bracket was placed over the tooth. This saved at least two minutes of the total time of the bonding procedure. The teeth in this group were also debonded within half-an-hour from the time of initial bonding. The teeth debonded after 24 hours of water storage at 37 degrees C had a mean shear bond strength of 6.0 +/- 3.5 MPa, the group that was debonded within half-an-hour of two light exposures had a mean shear bond strength of 5.9 +/- 2.7 MPa, and the mean for the group with only one light cure exposure was 4.3 +/- 2.6 MPa. Light curing the acid-etch primer together with the adhesive after placing the orthodontic bracket did not significantly diminish the shear bond strength as compared with light curing the acid-etch primer and the adhesive separately.

  5. Surface Characterization and Osteoconductivity Evaluation of Micro/Nano Surface Formed on Titanium Using Anodic Oxidation Combined with H2O2 Etching and Hydrothermal Treatment.

    PubMed

    Park, Eun-Jin; Song, Yo-Han; Hwang, Moon-Jin; Song, Ho-Jun; Park, Yeong-Joon

    2015-08-01

    In this study, surface characteristics and osteoconductivity were investigated for the micro/nanostructured oxide layers fabricated on titanium using anodic oxidation (ANO), chemical etching (Et), and hydrothermal treatment (HT). Commercially pure titanium (CP-Ti) disks were anodic-oxidized using DC-type power supply in 1 M phosphoric acid electrolyte (P-ANO group). These specimens were further chemically etched using 30% H2O2 solution at 60 °C for 10 min (P-ANO-Et group). The P-ANO-Et-HT group was fabricated by hydrothermally treating the P-ANO-Et specimens in phosphorus-containing alkaline solution at 190 °C for 8 hrs. The P-ANO group showed a porous surface that was evenly covered with micro- and sub-micro pores. The size of these pores was decreased in the P-ANO-Et group. The P-ANO-Et-HT group showed a porous surface that was covered with nano-sized crystallites. Anatase TiO2 structure was observed in P-ANO-Et-HT group. The results of XPS demonstrated that the P-ANO-Et-HT group had a well-crystallized TiC2 structure, while the P-ANO and P-ANO-Et groups had an amorphous and phosphate-containing structure. Hydrophilicity of the P-ANO-Et-HT group was the highest. After MG63 osteoblast-like cells were cultured on the specimens for 3 hrs, SEM images of the cells cultured on P-ANO-Et-HT group specimens showed low initial adhesion. However, the osteoconductivity of these specimens increased more rapidly compared to that of the micro-structured surfaces. These results could be applied to fabricate titanium implants with an optimum micro/nano-surface for enhancing their osteoconductivity.

  6. Impact of recess etching and surface treatments on ohmic contacts regrown by molecular-beam epitaxy for AlGaN/GaN high electron mobility transistors

    NASA Astrophysics Data System (ADS)

    Joglekar, S.; Azize, M.; Beeler, M.; Monroy, E.; Palacios, T.

    2016-07-01

    Ohmic contacts fabricated by regrowth of n+ GaN are favorable alternatives to metal-stack-based alloyed contacts in GaN-based high electron mobility transistors. In this paper, the influence of reactive ion dry etching prior to regrowth on the contact resistance in AlGaN/GaN devices is discussed. We demonstrate that the dry etch conditions modify the surface band bending, dangling bond density, and the sidewall depletion width, which influences the contact resistance of regrown contacts. The impact of chemical surface treatments performed prior to regrowth is also investigated. The sensitivity of the contact resistance to the surface treatments is found to depend upon the dangling bond density of the sidewall facets exposed after dry etching. A theoretical model has been developed in order to explain the observed trends.

  7. Fabrication, characterization, and biological assessment of multilayer DNA coatings on sandblasted-dual acid etched titanium surface.

    PubMed

    Liu, Li; Song, Li-Na; Yang, Guo-Li; Zhao, Shi-Fang; He, Fu-Ming

    2011-06-01

    As local gene therapy has received attention, immobilizing functional gene onto irregular oral implant surface has become an advanced challenge. Electrostatic layer-by-layer (LBL) assembly technique could achieve this goal and allow local and efficient administration of genes to the target cells. In this study, multilayers of cationic lipid/plasmid DNA (pEGFP-C1) complex (LDc) and anionic hyaluronic acid were assembled onto sandblasted-dual acid etched titanium disks by the LBL technique. Surface characteristics of the coatings were performed by x-ray photospectroscopy (XPS), contact angle measurements, and scanning electron microscopy (SEM). The cell biological characteristics of the coatings were evaluated by in vitro experiments. SEM results demonstrated that the porous titanium surface was gradually flattened with the increase of the multilayer. The XPS survey indicated that the N element was found from the coating. The coating degradation and pEGFP-C1 releasing kinetics showed that the more assembled layer numbers were, the larger the amount of DNA released in the first 30 h. MC3T3-E1 cells were cultured directly on the DNA-loaded surface. Higher enhanced green fluorescent protein (EGFP) expression efficiency was achieved by increasing the number of layers when cells were cultured after 24 or 72 h. The MC3T3-E1 cell viability on the surface of multilayer DNA coatings was significantly higher than that on control porous titanium surface. It was concluded that the approach established by the LBL technique had great potential in immobilizing gene coatings onto the porous titanium surface and subsequently influenced the function of the cultured cell.

  8. Petrologic and experimental evidence for the etching of garnets by organic acids in the upper Jurassic Morrision Formation, northwestern New Mexico.

    USGS Publications Warehouse

    Hansley, P.L.

    1987-01-01

    Etching of garnets and partial to complete dissolution of other aluminosilicate minerals were caused by high concentrations of organic acids generated during the maturation of epigenetic organic matter (predominantly type-III kerogen) in the Morrison Formation. The presence of authigenic phases that form near 100oC indicates that temperatures were high enough during diagenesis to cause the thermal degradation of kerogen.-from Author

  9. Ultrasonic recovery of copper and iron through the simultaneous utilization of Printed Circuit Boards (PCB) spent acid etching solution and PCB waste sludge.

    PubMed

    Huang, Zhiyuan; Xie, Fengchun; Ma, Yang

    2011-01-15

    A method was developed to recover the copper and iron from Printed Circuit Boards (PCB) manufacturing generated spent acid etching solution and waste sludge with ultrasonic energy at laboratory scale. It demonstrated that copper-containing PCB spent etching solution could be utilized as a leaching solution to leach copper from copper contained PCB waste sludge. It also indicated that lime could be used as an alkaline precipitating agent in this method to precipitate iron from the mixture of acidic PCB spent etching solution and waste sludge. This method provided an effective technique for the recovery of copper and iron through simultaneous use of PCB spent acid solution and waste sludge. The leaching rates of copper and iron enhanced with ultrasound energy were reached at 93.76% and 2.07% respectively and effectively separated copper from iron. Followed by applying lime to precipitate copper from the mixture of leachate and rinsing water produced by the copper and iron separation, about 99.99% and 1.29% of soluble copper and calcium were settled as the solids respectively. Furthermore the settled copper could be made as commercial rate copper. The process performance parameters studied were pH, ultrasonic power, and temperature. This method provided a simple and reliable technique to recover copper and iron from waste streams generated by PCB manufacturing, and would significantly reduce the cost of chemicals used in the recovery.

  10. Effect of adhesive hydrophilicity and curing-time on the permeability of resins bonded to water vs. ethanol-saturated acid-etched dentin

    PubMed Central

    Cadenaro, Milena; Breschi, Lorenzo; Rueggeberg, Frederick A.; Agee, Kelli; Di Lenarda, Roberto; Carrilho, Marcela; Tay, Franklin R.; Pashley, David H.

    2009-01-01

    Objective This study examined the ability of five comonomer blends (R1-R5) of methacrylate-based experimental dental adhesives solvated with 10 mass% ethanol, at reducing the permeability of acid-etched dentin. The resins were light-cured for 20, 40 or 60 s. The acid-etched dentin was saturated with water or 100% ethanol. Method Human unerupted third molars were converted into crown segments by removing the occlusal enamel and roots. The resulting crown segments were attached to plastic plates connected to a fluid-filled system for quantifying fluid flow across smear layer-covered dentin, acid-etched dentin and resin-bonded dentin. The degree of conversion of the resins was measured using Fourier transform infrared spectroscopy. Result Application of the most hydrophobic comonomer blend (R1) to water-saturated dentin produced the smallest reductions in dentin permeability (31.9, 44.1 and 61.1% after light-curing for 20, 40 or 60 s respectively). Application of the same blend to ethanol-saturated dentin reduced permeability of 74.1, 78.4 and 81.2%, respectively (p<0.05). Although more hydrophilic resins produced larger reductions in permeability, the same trend of significantly greater reductions in ethanol-saturated dentin over that of water-saturated dentin remained. This result can be explained by the higher solubility of resins in ethanol vs. water. Significance The largest reductions in permeability produced by resins were equivalent but not superior, to those produced by smear layers. Resin sealing of dentin remains a technique-sensitive step in bonding etch-and-rinse adhesives to dentin. PMID:18571228

  11. Effect of Surface Treatments after HF Etching on Oxidation of Si

    NASA Astrophysics Data System (ADS)

    Egawa, Masatoshi; Ikoma, Hideaki

    1994-02-01

    Oxidation of the Si surfaces treated in various solvents after HF etching was investigated by means of the Schottky diode characteristics and X-ray photoelectron spectroscopy (XPS). The solvents employed were deionized water, ethanol ( C2H5OH), trichloroethylene ( CHCl:CCl2), 1,1,1-trichloroethane ( CH3CCl3), dichloromethane ( CH2Cl2) and acetone ( CH3COCH3). The effect of rinsing of the Si substrate in deionized water under a reduced pressure was also studied. The XPS data showed that the Si surface is oxidized the most in acetone. The degree of oxidation was the next highest in deionized water and then in ethanol. On the other hand, Si oxidation was substantially suppressed in solvents which do not include oxidant groups such as OH and CO. In deionized water under reduced pressure, oxidation was also considerably retarded. A possible oxidation kinetics are proposed to explain the experimental results. In this model, co-existence of both oxidant groups such as OH radicals and dissolved oxygen in the solvent is assumed to enhance oxidation. First OH radicals attack the Si-F and/or the Si-H bonds on the Si surface, resulting in the formation of the unterminated and the OH-terminated Si surface. Then, the Si surface is predominantly oxidized further by dissolved oxygen. Hence, oxidation can efficiently be suppressed by removing either the oxidant group or dissolved oxygen. This is in good agreement with the experimental results. The oxidation kinetics in acetone is also speculated.

  12. Surface Properties and Osteoblastic Cytocompatibility of Two Blasted and Acid-Etched Titanium Implant Systems with Distinct Microtopography

    PubMed Central

    Mesquita, Pedro; Gomes, Pedro de Sousa; Sampaio, Paula; Juodzbalys, Gintaras; Afonso, Américo

    2012-01-01

    ABSTRACT Objectives The aim of this study is to compare two commercially available screw-type sandblasted and acid-etched (SLA) Ti implant systems from Eckermann Laboratorium S.L., with similar geometry and distinct microtopography, regarding surface properties and osteoblastic cytocompatibility. Material and Methods Implant I (referred as a conventional SLA system) and Implant II (a system patented as Eckcyte®) were characterized for macro and microtopograpphy, surface roughness and chemical composition. For the cytocompatibility studies, human bone marrow osteoblastic cells were seeded over the implants' surface, and the cell response was assessed for cell adhesion and proliferation, alkaline phosphatase (ALP) activity and matrix mineralization. Results Implant I presented a rough surface with irregularly shaped and sized cavities among flatter-appearing areas, whereas Implant II exhibited a homogeneous rough microporous surface. Compared to Implant I, Implant II presented higher Ra values (0.8 [SD 0.008] μm and 1.21 [SD 0.15] μm, respectively, P < 0.05) and also increased values of Rz, Rt and Rsm, a more negative value of Rsk, and similar RKu values. XPS showed the expected presence of Ti, O, C and N; Al, Si, F, P and Ca were detected in low concentrations. Implant II exhibited significantly lower Al levels. Both implants supported the adhesion, proliferation and differentiation of osteoblastic cells. Implant II showed a thicker fibrilar cell layer and an earlier onset and more abundant matrix mineralization. Conclusions The homogeneous rough and microporous surface of Implant II is most probably a main contributor for its improved cell response. PMID:24422006

  13. Uniform nano-ripples on the sidewall of silicon carbide micro-hole fabricated by femtosecond laser irradiation and acid etching

    SciTech Connect

    Khuat, Vanthanh; Chen, Tao; Gao, Bo; Si, Jinhai Ma, Yuncan; Hou, Xun

    2014-06-16

    Uniform nano-ripples were observed on the sidewall of micro-holes in silicon carbide fabricated by 800-nm femtosecond laser and chemical selective etching. The morphology of the ripple was analyzed using scanning electronic microscopy. The formation mechanism of the micro-holes was attributed to the chemical reaction of the laser affected zone with mixed solution of hydrofluoric acid and nitric acid. The formation of nano-ripples on the sidewall of the holes could be attributed to the standing wave generated in z direction due to the interference between the incident wave and the reflected wave.

  14. Treatment of Amino Acid Metabolism Disorders

    MedlinePlus

    ... amino acid metabolism disorders Treatment of amino acid metabolism disorders E-mail to a friend Please fill ... This is an amino acid that helps remove ammonia from the blood. Babies with HCY may need ...

  15. Treatment of Fatty Acid Oxidation Disorders

    MedlinePlus

    ... of fatty acid oxidation disorders Treatment of fatty acid oxidation disorders E-mail to a friend Please ... page It's been added to your dashboard . Fatty acid oxidation disorders are rare health conditions that affect ...

  16. Effect of acid etching on marginal adaptation of mineral trioxide aggregate to apical dentin: microcomputed tomography and scanning electron microscopy analysis.

    PubMed

    Al-Fouzan, Khalid; Al-Garawi, Ziad; Al-Hezaimi, Khalid; Javed, Fawad; Al-Shalan, Thakib; Rotstein, Ilan

    2012-12-01

    The present investigation assessed the effect of acid etching on marginal adaptation of white- and gray-colored mineral trioxide aggregate (MTA) to apical dentin using microcomputed tomography (micro-CT) and scanning electron microscopy (SEM). Sixty-four extracted single-rooted human maxillary teeth were used. Following root-end resection and apical preparation, the teeth were equally divided into four groups according to the following root end filling materials: (i) white-colored MTA (WMTA), (ii) etched WMTA (EWMTA), (iii) gray-colored MTA (GMTA) and (iv) etched GMTA (EGMTA). After 48 h, the interface between root-end filling materials and the dentinal walls was assessed using micro-CT and SEM. Data were statistically analyzed using the Kruskal-Wallis and Dunn tests. Micro-CT analysis revealed gap volumes between the apical cavity dentin walls and EGMTA, GMTA, EWMTA and WMTA of (0.007 1±0.004) mm(3), (0.053±0.002) mm(3), (0.003 6±0.001) mm(3) and (0.005 9±0.002) mm(3) respectively. SEM analysis revealed gap sizes for EGMTA, WMTA, EWMTA and GMTA to be (492.3±13.8) µm, (594.5±17.12) µm, (543.1±15.33) µm and (910.7±26.2) µm respectively. A significant difference in gap size between root end preparations filled with GMTA and EGMTA was found (P<0.05). No significance difference in gap size between WMTA and EWMTA were found in either SEM or micro-CT analysis. In conclusion, pre-etching of apical dentin can provide a better seal for GMTA but not for WMTA.

  17. Effects of etching and adhesive applications on the bond strength between composite resin and glass-ionomer cements

    PubMed Central

    PAMIR, Tijen; ŞEN, Bilge Hakan; EVCIN, Özgür

    2012-01-01

    Objective This study determined the effects of various surface treatment modalities on the bond strength of composite resins to glass-ionomer cements. Material and Methods Conventional (KetacTM Molar Quick ApplicapTM) or resin-modified (PhotacTM Fil Quick AplicapTM) glass-ionomer cements were prepared. Two-step etch-rinse & bond adhesive (AdperTM Single Bond 2) or single-step self-etching adhesive (AdperTM PromptTM L-PopTM) was applied to the set cements. In the etch-rinse & bond group, the sample surfaces were pre-treated as follows: (1) no etching, (2) 15 s of etching with 35% phosphoric acid, (3) 30 s of etching, and (4) 60 s of etching. Following the placement of the composite resin (FiltekTM Z250), the bond strength was measured in a universal testing machine and the data obtained were analyzed with the two-way analysis of variance (ANOVA) followed by the Tukey's HSD post hoc analysis (p=0.05). Then, the fractured surfaces were examined by scanning electron microscopy. Results The bond strength of the composite resin to the conventional glass-ionomer cement was significantly lower than that to the resin-modified glass-ionomer cement (p<0.001). No significant differences were determined between the self-etching and etch-rinse & bond adhesives at any etching time (p>0.05). However, a greater bond strength was obtained with 30 s of phosphoric acid application. Conclusions The resin-modified glass-ionomer cement improved the bond strength of the composite resin to the glass-ionomer cement. Both etch-rinse & bond and self-etching adhesives may be used effectively in the lamination of glass-ionomer cements. However, an etching time of at least 30 s appears to be optimal. PMID:23329245

  18. Refined tip preparation by electrochemical etching and ultrahigh vacuum treatment to obtain atomically sharp tips for scanning tunneling microscope and atomic force microscope.

    PubMed

    Hagedorn, Till; El Ouali, Mehdi; Paul, William; Oliver, David; Miyahara, Yoichi; Grütter, Peter

    2011-11-01

    A modification of the common electrochemical etching setup is presented. The described method reproducibly yields sharp tungsten tips for usage in the scanning tunneling microscope and tuning fork atomic force microscope. In situ treatment under ultrahigh vacuum (p ≤10(-10) mbar) conditions for cleaning and fine sharpening with minimal blunting is described. The structure of the microscopic apex of these tips is atomically resolved with field ion microscopy and cross checked with field emission.

  19. Refined tip preparation by electrochemical etching and ultrahigh vacuum treatment to obtain atomically sharp tips for scanning tunneling microscope and atomic force microscope

    SciTech Connect

    Hagedorn, Till; Ouali, Mehdi El; Paul, William; Oliver, David; Miyahara, Yoichi; Gruetter, Peter

    2011-11-15

    A modification of the common electrochemical etching setup is presented. The described method reproducibly yields sharp tungsten tips for usage in the scanning tunneling microscope and tuning fork atomic force microscope. In situ treatment under ultrahigh vacuum (p {<=}10{sup -10} mbar) conditions for cleaning and fine sharpening with minimal blunting is described. The structure of the microscopic apex of these tips is atomically resolved with field ion microscopy and cross checked with field emission.

  20. Evaluation of over-etching technique in the endodontically treated tooth restoration

    PubMed Central

    Migliau, Guido; Piccoli, Luca; Besharat, Laith Konstantinos; Di Carlo, Stefano; Pompa, Giorgio

    2015-01-01

    Summary The main purpose of a post-endodontic restoration with posts is to guarantee the retention of the restorative material. The aim of the study was to examine, through the push-out test, how bond strength between the post and the dentin varied with etching time with 37% orthophosphoric acid, before cementation of a glass fiber post. Moreover, it has been examined if over-etching (application time of the acid: 2 minutes) was an effective technique to improve the adhesion to the endodontic substrate, after highlighting the problems of adhesion concerning its anatomical characteristics and the changes after the endodontic treatment. Highest bond strength values were found by etching the substrate for 30 sec., while over-etching didn’t improve bond strength to the endodontic substrate. PMID:26161247

  1. Dry etching of metallization

    NASA Technical Reports Server (NTRS)

    Bollinger, D.

    1983-01-01

    The production dry etch processes are reviewed from the perspective of microelectronic fabrication applications. The major dry etch processes used in the fabrication of microelectronic devices can be divided into two categories - plasma processes in which samples are directly exposed to an electrical discharge, and ion beam processes in which samples are etched by a beam of ions extracted from a discharge. The plasma etch processes can be distinguished by the degree to which ion bombardment contributes to the etch process. This, in turn is related to capability for anisotropic etching. Reactive Ion Etching (RIE) and Ion Beam Etching are of most interest for etching of thin film metals. RIE is generally considered the best process for large volume, anisotropic aluminum etching.

  2. Influence of acid-base conditioning on the bond strength of five luting agents employing self-etching primer to enamel and dentin.

    PubMed

    Yokomichi, Rie; Taira, Yohsuke; Soeno, Kohyoh; Atsuta, Mitsuru

    2005-06-01

    The purpose of this study was to evaluate the effect of multi-step conditioning (PA-AD conditioning) with phosphoric acid and sodium hypochlorite on the bond strength of five luting materials to enamel and dentin. Three commercial self-etching/priming systems (Panavia, Linkmax, and Multibond) and two experimental systems (ED/Super-Bond and EDFe/Super-Bond) were used. The surfaces of bovine enamel or dentin were bonded to a stainless steel rod. Tensile bond strength was determined after 24-hour immersion in water. PA-AD conditioning significantly improved the bond strength between enamel and three of the systems (Panavia, ED/Super-Bond, and EDFe/Super-Bond), but did not have any effect on Linkmax and Multibond. Likewise, PA-AD conditioning did not significantly improve the bond strength of Panavia, Linkmax, Multibond, and ED/Super-Bond to dentin. Highest bond strength to dentin (19.7 MPa) was obtained when self-etching primer containing ferric chloride (EDFe/Super-Bond) was used, but additional PA-AD conditioning significantly weakened the bonding (12.6 MPa).

  3. Development of Corrosion Resistant Surface Treatments for Aluminum Alloys for Spot-Weld Bonding

    DTIC Science & Technology

    1975-03-01

    success- fully. Both surface treatments, ammonium tartrate anodize and FPL etch/ dichromate seal, were carried forward in the program until an...Phosphoric Acid Anodize 3. Sulfuric Acid Anodize 4. Chromic Acid Anodize 5. Ammonium Tartrate Anodize 6. FPL Etch plus Dichromate Seal 7. A.R. Aluminum...Etch Plus Dichromate Seal Low Voltage Ammonium Tartrate Anodize Low Voltage Sulfuric Acid Anodize Low Voltage Phos- phoric Acid Anodize 30-280

  4. Process for etching mixed metal oxides

    DOEpatents

    Ashby, C.I.H.; Ginley, D.S.

    1994-10-18

    An etching process is described using dicarboxylic and tricarboxylic acids as chelating etchants for mixed metal oxide films such as high temperature superconductors and ferroelectric materials. Undesirable differential etching rates between different metal oxides are avoided by selection of the proper acid or combination of acids. Feature sizes below one micron, excellent quality vertical edges, and film thicknesses in the 100 Angstrom range may be achieved by this method. 1 fig.

  5. Process for etching mixed metal oxides

    DOEpatents

    Ashby, Carol I. H.; Ginley, David S.

    1994-01-01

    An etching process using dicarboxylic and tricarboxylic acids as chelating etchants for mixed metal oxide films such as high temperature superconductors and ferroelectric materials. Undesirable differential etching rates between different metal oxides are avoided by selection of the proper acid or combination of acids. Feature sizes below one micron, excellent quality vertical edges, and film thicknesses in the 100 Angstom range may be achieved by this method.

  6. Influence of laser etching on enamel and dentin bond strength of Silorane System Adhesive.

    PubMed

    Ustunkol, Ildem; Yazici, A Ruya; Gorucu, Jale; Dayangac, Berrin

    2015-02-01

    The aim of this in vitro study was to evaluate the shear bond strength (SBS) of Silorane System Adhesive to enamel and dentin surfaces that had been etched with different procedures. Ninety freshly extracted human third molars were used for the study. After the teeth were embedded with buccal surfaces facing up, they were randomly divided into two groups. In group I, specimens were polished with a 600-grit silicon carbide (SiC) paper to obtain flat exposed enamel. In group II, the overlying enamel layer was removed and exposed dentin surfaces were polished with a 600-grit SiC paper. Then, the teeth in each group were randomly divided into three subgroups according to etching procedures: etched with erbium, chromium:yttrium-scandium-gallium-garnet laser (a), etched with 35% phosphoric acid (b), and non-etched (c, control). Silorane System Adhesive was used to bond silorane restorative to both enamel and dentin. After 24-h storage in distilled water at room temperature, a SBS test was performed using a universal testing machine at a crosshead speed of 1 mm/min. The data were analyzed using two-way ANOVA and Bonferroni tests (p < 0.05). The highest SBS was found after additional phosphoric acid treatment in dentin groups (p < 0.05). There were no statistically significant differences between the laser-etched and non-etched groups in enamel and dentin (p > 0.05). The SBS of self-etch adhesive to dentin was not statistically different from enamel (p > 0.05). Phosphoric acid treatment seems the most promising surface treatment for increasing the enamel and dentin bond strength of Silorane System Adhesive.

  7. Copper-assisted, anti-reflection etching of silicon surfaces

    DOEpatents

    Toor, Fatima; Branz, Howard

    2014-08-26

    A method (300) for etching a silicon surface (116) to reduce reflectivity. The method (300) includes electroless deposition of copper nanoparticles about 20 nanometers in size on the silicon surface (116), with a particle-to-particle spacing of 3 to 8 nanometers. The method (300) includes positioning (310) the substrate (112) with a silicon surface (116) into a vessel (122). The vessel (122) is filled (340) with a volume of an etching solution (124) so as to cover the silicon surface (116). The etching solution (124) includes an oxidant-etchant solution (146), e.g., an aqueous solution of hydrofluoric acid and hydrogen peroxide. The silicon surface (116) is etched (350) by agitating the etching solution (124) with, for example, ultrasonic agitation, and the etching may include heating (360) the etching solution (124) and directing light (365) onto the silicon surface (116). During the etching, copper nanoparticles enhance or drive the etching process.

  8. Bonding with self-etching primers--pumice or pre-etch? An in vitro study.

    PubMed

    Fitzgerald, Ian; Bradley, Gerard T; Bosio, Jose A; Hefti, Arthur F; Berzins, David W

    2012-04-01

    The purpose of this study was to compare the shear bond strengths (SBSs) of orthodontic brackets bonded with self-etching primer (SEP) using different enamel surface preparations. A two-by-two factorial study design was used. Sixty human premolars were harvested, cleaned, and randomly assigned to four groups (n = 15 per group). Teeth were bathed in saliva for 48 hours to form a pellicle. Treatments were assigned as follows: group 1 was pumiced for 10 seconds and pre-etched for 5 seconds with 37 per cent phosphoric acid before bonding with SEP (Transbond Plus). Group 2 was pumiced for 10 seconds before bonding. Group 3 was pre-etched for 5 seconds before bonding. Group 4 had no mechanical or chemical preparation before bonding. All teeth were stored in distilled water for 24 hours at 37°C before debonding. The SBS values and adhesive remnant index (ARI) score were recorded. The SBS values (± 1 SD) for groups 1-4 were 22.9 ± 6.6, 16.1 ± 7.3, 36.2 ± 8.2, and 13.1 ± 10.1 MPa, respectively. Two-way analysis of variance and subsequent contrasts showed statistically significant differences among treatment groups. ARI scores indicated the majority of adhesive remained on the bracket for all four groups. Pre-etching the bonding surface for 5 seconds with 37 per cent phosphoric acid, instead of pumicing, when using SEPs to bond orthodontic brackets, resulted in greater SBSs.

  9. A review of the developments of self-etching primers and adhesives -Effects of acidic adhesive monomers and polymerization initiators on bonding to ground, smear layer-covered teeth.

    PubMed

    Ikemura, Kunio; Kadoma, Yoshinori; Endo, Takeshi

    2011-01-01

    This paper reviews the developments of self-etching primers and adhesives, with a special focus on the effect of acidic adhesive monomers and polymerization initiators on bonding to ground, smear layer-covered teeth. Ionized acidic adhesive monomers chemically interact with tooth substrates and facilitate good bonding to ground dentin. Polymerization initiators in self-etching primers further promote effective bonding to ground dentin. To promote bonding to both dentin and enamel, phosphonic acid monomers such as 6-methacryloyloxyhexyl phosphonoacetate (6-MHPA) were developed. These novel adhesive monomers also have a water-soluble nature and are hence endowed with sufficient demineralization capability. A new single-bottle, self-etching, 2-hydroxyethyl methacrylate (HEMA)-free adhesive comprising 6-MHPA and 4-acryloyloxyethoxycarbonylphthalic acid (4-AET) was developed. This novel adhesive enabled strong adhesion to both ground enamel and dentin, but its formulation stability was influenced by pH value of the adhesive. To develop hydrolytically stable, single-bottle, self-etching adhesives, hydrolytically stable, radical-polymerizable acidic monomers with amide or ether linkages have been developed.

  10. Human dental implants with a sandblasted, acid-etched surface retrieved after 5 and 10 years: a light and scanning electron microscopy evaluation of two cases.

    PubMed

    Mangano, Carlo; Perrotti, Vittoria; Raspanti, Mario; Mangano, Francesco; Luongo, Giuseppe; Piattelli, Adriano; Iezzi, Giovanna

    2013-01-01

    The aim of the present study was a light and scanning electron microscopy (SEM) evaluation of the peri-implant tissues around sandblasted, acid-etched implants, retrieved from man, after a loading period of 5 and 10 years, respectively. Two implants (Leone Implant System) had been retrieved for a fracture of the prosthetic superstructure respectively after 5 and 10 years of loading. Both implants were stable before retrieval and had been retrieved using a 5-mm trephine bur. One implant was treated to obtain thin ground sections, while the other underwent evaluation under SEM. Compact, mature lamellar bone was present over most of the implant perimeter in close contact with the implant surface and with many remodeling areas. Under SEM, small concavities, completely filled by mineralized bone, were present on the implant surface. The present histologic results showed that these implants were well integrated over the long term, and the peri-implant bone was undergoing continuous remodeling at the interface.

  11. Histological and immunohistochemical evaluation of the peri-implant soft tissues around machined and acid-etched titanium healing abutments: a prospective randomised study.

    PubMed

    Degidi, Marco; Artese, Luciano; Piattelli, Adriano; Scarano, Antonio; Shibli, Jamil A; Piccirilli, Marcello; Perrotti, Vittoria; Iezzi, Giovanna

    2012-06-01

    A close spatial correlation has been described between the roughness of intraoral materials and the rate of bacterial colonisation. The aim of the present study in man was to conduct a comparative immunohistochemical evaluation of the inflammatory infiltrate, microvessel density, the nitric oxide synthases 1 and 3 and the vascular endothelial growth factor expression, the proliferative activity, and the B and T lymphocyte and histiocyte positivity in the peri-implant soft tissues around machined and acid-etched titanium healing caps. Ten patients participated in this study. The patients were enrolled consecutively. All patients received dental implants left to heal in a non-submerged mode. Healing caps were inserted in all implants. Half of the implants were supplied randomly with machined caps of titanium (control), while the other half were provided randomly with acid-etched titanium caps (test). After a 6-month healing period, a gingival biopsy was performed with a circular scalpel around the healing caps of both groups. The inflammatory infiltrate was mostly present in test specimens. Their extension was much larger than that of the control samples. A higher number of T and B lymphocytes were observed in test specimens. Higher values of microvessel density and a higher expression of vascular endothelial growth factor intensity were observed in the test samples. Furthermore, the Ki-67, NOS1 and NOS3 expression was significantly higher in the test specimens. All these results showed that the tissues around test healing caps underwent a higher rate of restorative processes, most probably correlated to the higher inflammation processes observed in these tissues.

  12. Surface passivation of silicon nanowires based metal nano-particle assisted chemical etching for photovoltaic applications

    NASA Astrophysics Data System (ADS)

    Ben Rabha, Mohamed; Khezami, Lotfi; Jemai, Abdelbasset Bessadok; Alhathlool, Raed; Ajbar, Abdelhamid

    2017-03-01

    Metal Nano-particle Assisted Chemical Etching (MNpACE) is an extraordinary developed wet etching method for producing uniform semiconductor nanostructure (silicon nanowires) from patterned metallic film on crystalline silicon surface. The metal films facilitate the etching in HF and H2O2 solution and produce silicon nanowires (SiNWs).The creation of different SiNWs morphologies by changing the etching time and its effects on optical and optoelectronic properties was investigated. The combination effect of formed SiNWs and stain etching treatment in acid (HF/HNO3/H2O) solution on the surface morphology of Si wafers as well as on the optical and optoelectronic properties especially a PL response at 640 nm are presented. As a results, the effective lifetime (τeff) and surface recombination velocity (Seff) evolution of SiNWs after stain etching treatment showed significant improvements and less than 1% reflectance was achieved over the wavelength range of 400-800 nm and more than 36% reduction was observed compared to untreated surface. It has, thus, been demonstrated that all these factors may lead to improved energy efficiency from 8% to nearly 14.2% for a cell with SiNWs treated in acid (HF/HNO3/H2O) solution.

  13. New Etch Monitoring Technique

    NASA Astrophysics Data System (ADS)

    Kaiser, Christina; Adamcyk, Martin; Levy, Yuval; Tiedje, Tom; Young, Jeff F.; Kelson, Itzhak

    2000-05-01

    Plasma etching is an important tool for the development of various types of nanostructures. The development of specific plasma etching procedures is often time-consuming. We will describe an new technique for IN-SITU monitoring of the etch rate and sidewall profile of 1D GRATINGS in a remote plasma etcher. The technique involves monitoring the energy loss of alpha particles that propagate through the layer being etched. Samples to be etched are impregnated by a thin near-surface layer of 224Ra nuclei that decay by alpha particle emission. The energy spectrum of the alpha particles is acquired at intervals in the etch process. The etch rate on flat surfaces can be determined quite simply by measuring the change in the peak energy of the transmitted particles. By using a simple geometric model that employs the Bethe Bloch formula for energy loss of charges particles the etch profile of masked samples can also be inferred.

  14. Tobacco etch virus infectivity in Capsicum spp. is determined by a maximum of three amino acids in the viral virulence determinant VPg.

    PubMed

    Perez, Kari; Yeam, Inhwa; Kang, Byoung-Cheorl; Ripoll, Daniel R; Kim, Jinhee; Murphy, John F; Jahn, Molly M

    2012-12-01

    Potyvirus resistance in Capsicum spp. has been attributed to amino acid substitutions at the pvr1 locus that cause conformational shifts in eukaryotic translation initiation factor eIF4E. The viral genome-linked protein (VPg) sequence was isolated and compared from three Tobacco etch virus (TEV) strains, highly aphid-transmissible (HAT), Mex21, and N, which differentially infect Capsicum genotypes encoding Pvr1(+), pvr1, and pvr1(2). Viral chimeras were synthesized using the TEV-HAT genome, replacing HAT VPg with Mex21 or N VPg. TEV HAT did not infect pepper plants homozygous for either the pvr1 or pvr1(2) allele. However, the novel chimeric TEV strains, TEVHAT(Mex21-VPg) and TEV-HAT(N-VPg), infected pvr1 and pvr1(2) pepper plants, respectively, demonstrating that VPg is the virulence determinant in this pathosystem. Three dimensional structural models predicted interaction between VPg and the susceptible eIF4E genotype in every case, while resistant genotypes were never predicted to interact. To determine whether there is a correlation between physical interaction of VPg with eIF4E and infectivity, the effects of amino acid variation within VPg were assessed. Interaction between pvr1(2) eIF4E and N VPg was detected in planta, implying that the six amino acid differences in N VPg relative to HAT VPg are responsible for restoring the physical interaction and infectivity.

  15. Acid peptic diseases: pharmacological approach to treatment

    PubMed Central

    Mejia, Alex; Kraft, Walter K

    2011-01-01

    Acid peptic disorders are the result of distinctive, but overlapping pathogenic mechanisms leading to either excessive acid secretion or diminished mucosal defense. They are common entities present in daily clinical practice that, owing to their chronicity, represent a significant cost to healthcare. Key elements in the success of controlling these entities have been the development of potent and safe drugs based on physiological targets. The histamine-2 receptor antagonists revolutionized the treatment of acid peptic disorders owing to their safety and efficacy profile. The proton-pump inhibitors (PPIs) represent a further therapeutic advance due to more potent inhibition of acid secretion. Ample data from clinical trials and observational experience have confirmed the utility of these agents in the treatment of acid peptic diseases, with differential efficacy and safety characteristics between and within drug classes. Paradigms in their speed and duration of action have underscored the need for new chemical entities that, from a single dose, would provide reliable duration of acid control, particularly at night. Moreover, PPIs reduce, but do not eliminate, the risk of ulcers in patients taking NSAIDs, reflecting untargeted physiopathologic pathways and a breach in the ability to sustain an intragastric pH of more than 4. This review provides an assessment of the current understanding of the physiology of acid production, a discussion of medications targeting gastric acid production and a review of efficacy in specific acid peptic diseases, as well as current challenges and future directions in the treatment of acid-mediated diseases. PMID:21822447

  16. Rapid formation of AgnX(X = S, Cl, PO4, C2O4) nanotubes via an acid-etching anion exchange reaction

    NASA Astrophysics Data System (ADS)

    Li, Jingjing; Yang, Wenlong; Ning, Jiqiang; Zhong, Yijun; Hu, Yong

    2014-05-01

    This work presents a rapid nanotube fabrication method for a series of silver compounds AgnX, such as Ag2S, AgCl, Ag3PO4, and Ag2C2O4, from pregrown Ag2CO3 nanorod templates. The anion exchange process involved takes place in non-aqueous solutions just at room temperature and completes within 10 minutes. An acid-etching anion exchange reaction mechanism has been proved underneath the transformation process from Ag2CO3 nanorods to AgnX nanotubes by the observation of an intermediate yolk-shell nanostructure. It has been found that the final structure of the products can be conveniently controlled by simply varying the concentration of HnX acids, and the organic solvents employed play a vital role in the formation of the nanotubes by effectively controlling the diffusion rates of different species of reacting ions. As a demonstration, the as-prepared AgCl and Ag3PO4 nanotubes exhibit enhanced photocatalytic activity and favorable recyclability for the photodegradation of rhodamine B (RhB) under visible-light irradiation.This work presents a rapid nanotube fabrication method for a series of silver compounds AgnX, such as Ag2S, AgCl, Ag3PO4, and Ag2C2O4, from pregrown Ag2CO3 nanorod templates. The anion exchange process involved takes place in non-aqueous solutions just at room temperature and completes within 10 minutes. An acid-etching anion exchange reaction mechanism has been proved underneath the transformation process from Ag2CO3 nanorods to AgnX nanotubes by the observation of an intermediate yolk-shell nanostructure. It has been found that the final structure of the products can be conveniently controlled by simply varying the concentration of HnX acids, and the organic solvents employed play a vital role in the formation of the nanotubes by effectively controlling the diffusion rates of different species of reacting ions. As a demonstration, the as-prepared AgCl and Ag3PO4 nanotubes exhibit enhanced photocatalytic activity and favorable recyclability for the

  17. Ion beam etching process for high-density spintronic devices and its damage recovery by the oxygen showering post-treatment process

    NASA Astrophysics Data System (ADS)

    Jeong, Junho; Endoh, Tetsuo

    2017-04-01

    The electric short fail trend of the perpendicular magnetic tunnel junctions (p-MTJs) caused by the ion beam etching (IBE) process is studied at various ion beam angles and cell-to-cell space widths. The number of electric short fails increases markedly at an ion beam angle greater than 35° and a cell-to-cell space width less than 30 nm at the assumed MTJ height including a hard mask (HM) of 20 nm. In order to recover these electric short fails, we propose the selective oxidation process called the oxygen showering post-treatment (OSP). By the OSP process, the number of electric short fails in sub-30-nm-spaced MTJ arrays is reduced from 25 to 0.8%, and the magnetoresistance (MR) is increased from 99 to 120%. By this result, we can verify that the damaged layer is recovered successfully by the OSP, and that the OSP can be a universal post-treatment process even beyond the 20 nm design rule for use in both reactive ion etching and IBE schemes.

  18. Effects of Acid Treatment on Dental Zirconia: An In Vitro Study

    PubMed Central

    Xie, Haifeng; Shen, Shuping; Qian, Mengke; Zhang, Feimin; Chen, Chen; Tay, Franklin R.

    2015-01-01

    The aim of this study was to evaluate the effects of hydrofluoric (HF) acid, acetic acid, and citric acid treatments on the physical properties and structure of yttria-stabilized tetragonal zirconia polycrystal (Y-TZP) at ambient temperature. In total, 110 bar-shaped zirconia specimens were randomly assigned to 11 groups. The specimens in the control group (C) received no surface treatment, while those in the Cage group were hydrothermally aged at 134°C and 0.2 MPa for 20 h. Ten specimens each were immersed at ambient temperature in 5% and 40% HF acid for 2 h (40HF0), 1 day (5HF1, 40HF1), and 5 days (5HF5, 40HF5), while 10 each were immersed at ambient temperature in 10% acetic acid and 20% citric acid for 7 (AC7, CI7) and 14 days (AC14, CI14). X-ray diffraction (XRD) was used to quantitatively estimate the monoclinic phase. Furthermore, flexural strength, surface roughness, and surface Vickers hardness were measured after treatment. Scanning electron microscopy (SEM) was used to characterize the surface morphology. The Cage group specimens exhibited an increased monoclinic phase and flexural strength. Furthermore, 40% HF acid immersion decreased the flexural strength and surface hardness and deteriorated the surface finish, while 5% HF acid immersion only decreased the surface hardness. All the HF acid-immersed specimens showed an etched surface texture on SEM observations, while the other groups did not. These findings suggest that the treatment of Y-TZP with 40% HF acid at ambient temperature causes potential damage, while treatment with 5% HF acid, acetic acid, and citric acid is safe. PMID:26301413

  19. [Injection treatment with hyaluronic acid].

    PubMed

    Jerosch, J

    2015-11-01

    This article presents the spectrum of indications for the use of hyaluronic acid (HA) based on the recommendations of the European League Against Rheumatism (EULAR), the American College of Rheumatology (ACR), the Osteoarthritis Research Society International (OARSI), the International Institute for Health and Clinical Excellence (NICE) and the European Society for Clinical and Economic Aspects of Osteoporosis and Osteoarthritis (ESCEO) taking the reality of patient care in Europe into account.

  20. UV Spectra of Amino Acid Immobilized at Nanoparticles Formation through Nanosphere Lithography (NSL) by Plasma Treatment

    SciTech Connect

    Mohamad, Farizan; Agam, Mohd Arif; Nur, Hadi

    2011-05-25

    The modifying of nanospheres structures by plasma treatments to the fabricated nanoparticles arrays by Nanosphere Lithography (NSL) techniques to create Periodic Particles Arrays (PPAs) with different size, shape and orientation. Spectra of amino acid that immobilized to the nanoparticles arrays under Ultra Violet (UV) spectrums were studied. The PPAs with different sizes, shapes and orientation were fabricated by plasma treatment of 5 sec, 7 sec and 10 sec to the Polystyrene Nanosphere (PSN). Plasma treatment will effect to the PSN including etching part of the PSN to produce a much bigger channel to the single layer template of the PSN. Metal was deposited at interstitial sites between of the polymer balls and later removed by dissolving them in organic solvent, leaving a hexagonal pattern of metal structures at the interstitial sites. The nanoparticles immobilized with the standard amino acid, which later investigated under UV spectrums. The spectrums shows the possibilities use as biosensor devices.

  1. Alkaline etch system qualification

    SciTech Connect

    Goldammer, S.E.; Pemberton, S.E.; Tucker, D.R.

    1997-04-01

    Based on the data from this qualification activity, the Atotech etch system, even with minimum characterization, was capable of etching production printed circuit products as good as those from the Chemcut system. Further characterization of the Atotech system will improve its etching capability. In addition to the improved etch quality expected from further characterization, the Atotech etch system has additional features that help reduce waste and provide for better consistency in the etching process. The programmable logic controller and computer will allow operators to operate the system manually or from pre-established recipes. The evidence and capabilities of the Atotech system made it as good as or better than the Chemcut system for etching WR products. The Printed Wiring Board Engineering Department recommended that the Atotech system be released for production. In December 1995, the Atotech system was formerly qualified for production.

  2. Effect of cavity preparation method on microtensile bond strength of a self-etching primer vs phosphoric acid etchant to enamel.

    PubMed

    de Souza-Zaroni, Wanessa Christine; Delfino, Carina Sinclér; Ciccone-Nogueira, Juliane Cristina; Palma-Dibb, Regina Guenka; Corona, Silmara Aparecida Milori

    2007-10-01

    This study evaluated the effect of cavity preparation using air abrasion or carbide bur on bond strength to enamel treated with a self-etching primer (Tyrian SPE) or a phosphoric acid etchant. Twenty-four molars were divided into three groups: high-speed; standard handpiece (ST air abrasion) or supersonic handpiece (SP air abrasion) of the same air-abrasive system. The enamel surfaces were treated with one of the two etchants and the same adhesive agent One Step Plus, and then composite buildups were done with Filtek Z250. After 24 h at 37 degrees C, beams (0.8 mm2) were obtained and subjected to tensile stress in a universal testing machine (0.5 mm/min). The data were submitted to analysis of variance and Tukey's test (P < 0.05). For the conditioning agents, it was observed that the specimens conditioned with phosphoric acid presented superior results than the specimens that used Tyrian SPE. For the preparation techniques, it was verified that the SP air abrasion groups showed the highest bond strengths and carbide-bur groups presented the lowest bond strengths when the specimens were conditioned with Tyrian SPE. It can be concluded that the influence of the cavity preparation method was dependent on the conditioning system used, only when using carbide-bur preparation technique.

  3. Rapid formation of Ag(n)X(X = S, Cl, PO4, C2O4) nanotubes via an acid-etching anion exchange reaction.

    PubMed

    Li, Jingjing; Yang, Wenlong; Ning, Jiqiang; Zhong, Yijun; Hu, Yong

    2014-06-07

    This work presents a rapid nanotube fabrication method for a series of silver compounds AgnX, such as Ag2S, AgCl, Ag3PO4, and Ag2C2O4, from pregrown Ag2CO3 nanorod templates. The anion exchange process involved takes place in non-aqueous solutions just at room temperature and completes within 10 minutes. An acid-etching anion exchange reaction mechanism has been proved underneath the transformation process from Ag2CO3 nanorods to AgnX nanotubes by the observation of an intermediate yolk-shell nanostructure. It has been found that the final structure of the products can be conveniently controlled by simply varying the concentration of HnX acids, and the organic solvents employed play a vital role in the formation of the nanotubes by effectively controlling the diffusion rates of different species of reacting ions. As a demonstration, the as-prepared AgCl and Ag3PO4 nanotubes exhibit enhanced photocatalytic activity and favorable recyclability for the photodegradation of rhodamine B (RhB) under visible-light irradiation.

  4. Quantification of proteins using enhanced etching of Ag coated Au nanorods by the Cu2+/bicinchoninic acid pair with improved sensitivity

    NASA Astrophysics Data System (ADS)

    Liu, Wenqi; Hou, Shuai; Yan, Jiao; Zhang, Hui; Ji, Yinglu; Wu, Xiaochun

    2015-12-01

    Plasmonic nanosensors show great potential in ultrasensitive detection, especially with the plasmon peak position as the detection modality. Herein, a new sensitive but simple total protein quantification method termed the SPR-BCA assay is demonstrated by combining plasmonic nanosensors with protein oxidation by Cu2+. The easy tuning of localized surface plasmon resonance (LSPR) features of plasmonic nanostructures makes them ideal sensing platforms. We found that the Cu2+/bicinchoninic acid (BCA) pair exhibits accelerated etching of Au@Ag nanorods and results in the LSPR peak shift. A linear relationship between Cu2+ and the LSPR shift is found in a double logarithmic coordinate. Such double logarithm relationship is transferred to the concentration of proteins. Theoretical simulation shows that Au nanorods with large aspect ratios and small core sizes show high detection sensitivity. Via optimized sensor design, we achieved an increased sensitivity (the limit of detection was 3.4 ng ml-1) and a wide working range (0.5 to 1000 μg ml-1) compared with the traditional BCA assay. The universal applicability of our method to various proteins further proves its potential in practical applications.Plasmonic nanosensors show great potential in ultrasensitive detection, especially with the plasmon peak position as the detection modality. Herein, a new sensitive but simple total protein quantification method termed the SPR-BCA assay is demonstrated by combining plasmonic nanosensors with protein oxidation by Cu2+. The easy tuning of localized surface plasmon resonance (LSPR) features of plasmonic nanostructures makes them ideal sensing platforms. We found that the Cu2+/bicinchoninic acid (BCA) pair exhibits accelerated etching of Au@Ag nanorods and results in the LSPR peak shift. A linear relationship between Cu2+ and the LSPR shift is found in a double logarithmic coordinate. Such double logarithm relationship is transferred to the concentration of proteins. Theoretical

  5. Biomimetic Deposition of Hydroxyapatite by Mixed Acid Treatment of Titanium Surfaces.

    PubMed

    Zhao, J M; Park, W U; Hwang, K H; Lee, J K; Yoon, S Y

    2015-03-01

    A simple chemical method was established for inducing bioactivity of Ti metal. In the present study, two kinds of mixed acid solutions were used to treat Ti specimens to induce Ca-P formation. Following a strong mixed acid activation process, Ca-P coatings successfully formed on the Ti surfaces in the simulated body fluid. Strong mixed acid etching was used to increase the roughness of the metal surface, because the porous and rough surfaces allow better adhesion between Ca-P coatings and substrate. Nano-scale modification of titanium surfaces can alter cellular and tissue responses, which may benefit osseointegration and dental implant therapy. Some specimens were treated with a 5 M NaOH aqueous solution, and then heat treated at 600 °C in order to form an amorphous sodium titanate layer on their surface. This treated titanium metal is believed to form a dense and uniform bone-like apatite layer on its surface in a simulated body fluid (SBF). This study proved that mixed acid treatment is not only important for surface passivation but is also another bioactive treatment for titanium surfaces, an alternative to alkali treatment. In addition, mixed acid treatment uses a lower temperature and shorter time period than alkali treatment.

  6. From Hypo- to Hypersuppression: Effect of Amino Acid Substitutions on the RNA-Silencing Suppressor Activity of the Tobacco etch potyvirus HC-Pro

    PubMed Central

    Torres-Barceló, Clara; Martín, Susana; Daròs, José-Antonio; Elena, Santiago F.

    2008-01-01

    RNA silencing participates in several important functions: from the regulation of cell metabolism and organism development to sequence-specific antiviral defense. Most plant viruses have evolved proteins that suppress RNA silencing and that in many cases are multifunctional. Tobacco etch potyvirus (TEV) HC-Pro protein suppresses RNA silencing and participates in aphid-mediated transmission, polyprotein processing, and genome amplification. In this study, we have generated 28 HC-Pro amino acid substitution mutants and quantified their capacity as suppressors of RNA silencing in a transient expression assay. Most mutations either had no quantitative effect or completely abolished silencing suppression (10 in each class), 3 caused a significant decrease in the activity, and 5 significantly increased it, revealing an unexpected high frequency of mutations conferring hypersuppressor activity. A representative set of the mutant alleles, containing both hypo- and hypersuppressors, was further analyzed for their effect on TEV accumulation and the strength of induced symptoms. Whereas TEV variants with hyposuppressor mutants were far less virulent than wild-type TEV, those with hypersuppressor alleles induced symptoms that were not more severe than those characteristic of the wild-type virus, suggesting that there is not a perfect match between suppression and virulence. PMID:18780745

  7. Effects of rhBMP-2 on Sandblasted and Acid Etched Titanium Implant Surfaces on Bone Regeneration and Osseointegration: Spilt-Mouth Designed Pilot Study

    PubMed Central

    Kim, Nam-Ho; Lee, So-Hyoun; Ryu, Jae-Jun; Choi, Kyung-Hee; Huh, Jung-Bo

    2015-01-01

    This study was conducted to evaluate effects of rhBMP-2 applied at different concentrations to sandblasted and acid etched (SLA) implants on osseointegration and bone regeneration in a bone defect of beagle dogs as pilot study using split-mouth design. Methods. For experimental groups, SLA implants were coated with different concentrations of rhBMP-2 (0.1, 0.5, and 1 mg/mL). After assessment of surface characteristics and rhBMP-2 releasing profile, the experimental groups and untreated control groups (n = 6 in each group, two animals in each group) were placed in split-mouth designed animal models with buccal open defect. At 8 weeks after implant placement, implant stability quotients (ISQ) values were recorded and vertical bone height (VBH, mm), bone-to-implant contact ratio (BIC, %), and bone volume (BV, %) in the upper 3 mm defect areas were measured. Results. The ISQ values were highest in the 1.0 group. Mean values of VBH (mm), BIC (%), and BV (%) were greater in the 0.5 mg/mL and 1.0 mg/mL groups than those in 0.1 and control groups in buccal defect areas. Conclusion. In the open defect area surrounding the SLA implant, coating with 0.5 and 1.0 mg/mL concentrations of rhBMP-2 was more effective, compared with untreated group, in promoting bone regeneration and osseointegration. PMID:26504807

  8. Radiation induced deposition of copper nanoparticles inside the nanochannels of poly(acrylic acid)-grafted poly(ethylene terephthalate) track-etched membranes

    NASA Astrophysics Data System (ADS)

    Korolkov, Ilya V.; Güven, Olgun; Mashentseva, Anastassiya A.; Atıcı, Ayse Bakar; Gorin, Yevgeniy G.; Zdorovets, Maxim V.; Taltenov, Abzal A.

    2017-01-01

    Poly(ethylene terephthalate) PET, track-etched membranes (TeMs) with 400 nm average pore size were UV-grafted with poly(acrylic acid) (PAA) after oxidation of inner surfaces by H2O2/UV system. Carboxylate groups of grafted PAA chains were easily complexed with Cu2+ ions in aqueous solutions. These ions were converted into metallic copper nanoparticles (NPs) by radiation-induced reduction of copper ions in aqueous-alcohol solution by gamma rays in the dose range of 46-250 kGy. Copper ions chelating with -COOH groups of PAA chains grafted on PET TeMs form polymer-metal ion complex that prevent the formation of agglomerates during reduction of copper ions to metallic nanoparticles. The detailed analysis by X-Ray diffraction technique (XRD), transmission electron microscopy (TEM), scanning electron microscopy (SEM) and energy-dispersive X-ray spectroscopy (EDX) confirmed the deposition of copper nanoparticles with the average size of 70 nm on the inner surface of nanochannels of PET TeMs. Samples were also investigated by FTIR, ESR spectroscopies to follow copper ion reduction.

  9. Quantification of proteins using enhanced etching of Ag coated Au nanorods by the Cu(2+)/bicinchoninic acid pair with improved sensitivity.

    PubMed

    Liu, Wenqi; Hou, Shuai; Yan, Jiao; Zhang, Hui; Ji, Yinglu; Wu, Xiaochun

    2016-01-14

    Plasmonic nanosensors show great potential in ultrasensitive detection, especially with the plasmon peak position as the detection modality. Herein, a new sensitive but simple total protein quantification method termed the SPR-BCA assay is demonstrated by combining plasmonic nanosensors with protein oxidation by Cu(2+). The easy tuning of localized surface plasmon resonance (LSPR) features of plasmonic nanostructures makes them ideal sensing platforms. We found that the Cu(2+)/bicinchoninic acid (BCA) pair exhibits accelerated etching of Au@Ag nanorods and results in the LSPR peak shift. A linear relationship between Cu(2+) and the LSPR shift is found in a double logarithmic coordinate. Such double logarithm relationship is transferred to the concentration of proteins. Theoretical simulation shows that Au nanorods with large aspect ratios and small core sizes show high detection sensitivity. Via optimized sensor design, we achieved an increased sensitivity (the limit of detection was 3.4 ng ml(-1)) and a wide working range (0.5 to 1000 μg ml(-1)) compared with the traditional BCA assay. The universal applicability of our method to various proteins further proves its potential in practical applications.

  10. Long-term bonding effectiveness of simplified etch-and-rinse adhesives to dentin after different surface pre-treatments

    PubMed Central

    Verma, Radhika; Singh, Udai Pratap; Tyagi, Shashi Prabha; Nagpal, Rajni; Manuja, Naveen

    2013-01-01

    Objective: To evaluate the effect of 2% chlorhexidine (CHX) and 30% proanthocyanidin (PA) application on the immediate and long-term bond strength of simplified etch-and-rinse adhesives to dentin. Materials and Methods: One hundred twenty extracted human molar teeth were ground to expose the flat dentin surface. The teeth were equally divided into six groups according to the adhesives used, either Tetric N Bond or Solobond M and pretreatments given either none, CHX, or PA. Composite cylinder was bonded to each specimen using the respective adhesive technique. Half the samples from each group (n = 10) were then tested immediately. The remaining samples were tested after 6 month storage in distilled water. Results: The mean bond strength of samples was not significantly different upon immediate testing being in the range of 8.4(±0.7) MPa. The bond strength fell dramatically in the control specimens after 6 month storage to around 4.7(±0.33) MPa, while the bond strength was maintained in the samples treated with both CHX and PA. Conclusion: Thirty percent PA was comparable to 2% CHX with respect to preservation of the resin dentin bond over 6 months. PMID:23956543

  11. Bacterial Cyanuric Acid Hydrolase for Water Treatment

    PubMed Central

    Yeom, Sujin; Mutlu, Baris R.; Aksan, Alptekin

    2015-01-01

    Di- and trichloroisocyanuric acids are widely used as water disinfection agents, but cyanuric acid accumulates with repeated additions and must be removed to maintain free hypochlorite for disinfection. This study describes the development of methods for using a cyanuric acid-degrading enzyme contained within nonliving cells that were encapsulated within a porous silica matrix. Initially, three different bacterial cyanuric acid hydrolases were compared: TrzD from Acidovorax citrulli strain 12227, AtzD from Pseudomonas sp. strain ADP, and CAH from Moorella thermoacetica ATCC 39073. Each enzyme was expressed recombinantly in Escherichia coli and tested for cyanuric acid hydrolase activity using freely suspended or encapsulated cell formats. Cyanuric acid hydrolase activities differed by only a 2-fold range when comparing across the different enzymes with a given format. A practical water filtration system is most likely to be used with nonviable cells, and all cells were rendered nonviable by heat treatment at 70°C for 1 h. Only the CAH enzyme from the thermophile M. thermoacetica retained significant activity under those conditions, and so it was tested in a flowthrough system simulating a bioreactive pool filter. Starting with a cyanuric acid concentration of 10,000 μM, more than 70% of the cyanuric acid was degraded in 24 h, it was completely removed in 72 h, and a respike of 10,000 μM cyanuric acid a week later showed identical biodegradation kinetics. An experiment conducted with water obtained from municipal swimming pools showed the efficacy of the process, although cyanuric acid degradation rates decreased by 50% in the presence of 4.5 ppm hypochlorite. In total, these experiments demonstrated significant robustness of cyanuric acid hydrolase and the silica bead materials in remediation. PMID:26187963

  12. Metal etching with reactive gas cluster ion beams using pickup cell

    SciTech Connect

    Toyoda, Noriaki; Yamada, Isao

    2012-11-06

    Mixed gas cluster ion beams were formed using pickup cell for metal etching. O{sub 2} neutral clusters pick up acetic acid and formed mixed cluster beam. By using O{sub 2}-GCIB with acetic acid, enhancement of Cu etching was observed. Because of dense energy deposition by GCIB, etching of Cu proceeds by CuO formation, enhancement of chemical reaction with acetic acid and desorption of etching products. Surface roughening was not observed on poly crystalline Cu because of the small dependence of etching rate on crystal orientation. Halogen free and low-temperature metal etching with GCIB using pickup cell is possible.

  13. Sputtered gold mask for deep chemical etching of silicon

    NASA Technical Reports Server (NTRS)

    Pisciotta, B. P.; Gross, C.; Olive, R. S.

    1975-01-01

    Sputtered mask resists chemical attack from acid and has adherence to withstand prolonged submergence in etch solution without lifting from silicon surface. Even under prolonged etch conditions with significant undercutting, gold mask maintained excellent adhesion to silicon surface and imperviousness to acid.

  14. Nanoparticle-based etching of silicon surfaces

    DOEpatents

    Branz, Howard [Boulder, CO; Duda, Anna [Denver, CO; Ginley, David S [Evergreen, CO; Yost, Vernon [Littleton, CO; Meier, Daniel [Atlanta, GA; Ward, James S [Golden, CO

    2011-12-13

    A method (300) of texturing silicon surfaces (116) such to reduce reflectivity of a silicon wafer (110) for use in solar cells. The method (300) includes filling (330, 340) a vessel (122) with a volume of an etching solution (124) so as to cover the silicon surface 116) of a wafer or substrate (112). The etching solution (124) is made up of a catalytic nanomaterial (140) and an oxidant-etchant solution (146). The catalytic nanomaterial (140) may include gold or silver nanoparticles or noble metal nanoparticles, each of which may be a colloidal solution. The oxidant-etchant solution (146) includes an etching agent (142), such as hydrofluoric acid, and an oxidizing agent (144), such as hydrogen peroxide. Etching (350) is performed for a period of time including agitating or stirring the etching solution (124). The etch time may be selected such that the etched silicon surface (116) has a reflectivity of less than about 15 percent such as 1 to 10 percent in a 350 to 1000 nanometer wavelength range.

  15. The Effects of Using a Commercial Grade Plasma Etching Chamber to Etch Anodized Niobium Surfaces

    NASA Astrophysics Data System (ADS)

    Epperson, Christiana; Drake, Dereth; Winska, Kalina

    2015-11-01

    Anodized niobium surfaces are used in particle accelerators for construction of the superconducting cavities. These surfaces must be cleaned regularly to remove containments and maintain the surface smoothness. The most common method used is that of chemically etching the surface using acid baths; however, this process can affect the smoothness of the layer and is extremely time consuming and hazardous. Plasma etching is one alternative that has shown great promise. We are using a commercial grade plasma etching chamber to clean anodized niobium samples that have varying oxide layer thicknesses. Spectral profiles of the surfaces of the samples are taken before and after etching. All measured results are compared to a simple theoretical model in order to determine the effects of the etching process on each surface.

  16. SURFACE TREATMENT OF METALLIC URANIUM

    DOEpatents

    Gray, A.G.; Schweikher, E.W.

    1958-05-27

    The treatment of metallic uranium to provide a surface to which adherent electroplates can be applied is described. Metallic uranium is subjected to an etchant treatment in aqueous concentrated hydrochloric acid, and the etched metal is then treated to dissolve the resulting black oxide and/or chloride film without destroying the etched metal surface. The oxide or chloride removal is effected by means of moderately concentrated nitric acid in 3 to 20 seconds.

  17. SEMICONDUCTOR TECHNOLOGY: Wet etching characteristics of a HfSiON high-k dielectric in HF-based solutions

    NASA Astrophysics Data System (ADS)

    Yongliang, Li; Qiuxia, Xu

    2010-03-01

    The wet etching properties of a HfSiON high-k dielectric in HF-based solutions are investigated. HF-based solutions are the most promising wet chemistries for the removal of HfSiON, and etch selectivity of HF-based solutions can be improved by the addition of an acid and/or an alcohol to the HF solution. Due to densification during annealing, the etch rate of HfSiON annealed at 900 °C for 30 s is significantly reduced compared with as-deposited HfSiON in HF-based solutions. After the HfSiON film has been completely removed by HF-based solutions, it is not possible to etch the interfacial layer and the etched surface does not have a hydrophobic nature, since N diffuses to the interface layer or Si substrate formation of Si-N bonds that dissolves very slowly in HF-based solutions. Existing Si-N bonds at the interface between the new high-k dielectric deposit and the Si substrate may degrade the carrier mobility due to Coulomb scattering. In addition, we show that N2 plasma treatment before wet etching is not very effective in increasing the wet etch rate for a thin HfSiON film in our case.

  18. Improved wet bonding of methyl methacrylate-tri-n-butylborane resin to dentin etched with ten percent phosphoric acid in the presence of ferric ions.

    PubMed

    Iwasaki, Yasuhiko; Toida, Tetsuya; Nakabayashi, Nobuo

    2004-03-01

    The objective of this study was to determine the influence of dissolved dentinal substances in demineralized dentin on the hybridization of resin for bonding to dentin. It was hypothesized that these substances, including polyelectrolytes, significantly change the substrates, which could then be assessed by the addition of Na(+), Ca(2+), or Fe(3+) in 10% phosphoric acid. Bovine dentin specimens were etched for 10 s with a solution of 10% phosphoric acid (control) or of 22.0 mM dissolved sodium chloride (10P-Na), calcium chloride (10P-Ca), or ferric chloride (10P-Fe). The specimens were then rinsed, blot-dried, and primed three times with 5% 4-methacryloyloxyethyl trimellitate anhydride in acetone for 60 s. Methyl methacrylate-tri-n-butylborane resin was then applied. The tensile bond strength of each of the dumbbell-shaped specimens was then measured. The fractured surfaces and modified cross-sections were examined by scanning electron microscopy. The cross-sections were soaked in 6N HCl for 10 s and then in 1% sodium hypochlorite for 30 min to determine the resin content in the hybridized specimens. Shrinkage of the demineralized dentins upon drying was assessed by atomic force microscopy. The tensile bond strengths were 10.8 +/- 4.5 (control), 15.0 +/- 7.0 (10P-Na), 19.3 +/- 5.5 (10P-Ca), and 27.8 +/- 8.1 (10P-Fe) MPa. The atomic force microscopy studies showed that Fe(3+) minimized the shrinkage by drying for 10 s but Ca(2+) and Na(+) did not decrease the shrinkage the same as the control. The results support the hypothesis that the monomer permeability of wet demineralized dentin is effectively improved by dissolving ferric ions in the phosphoric acid, resulting in a greater bond strength and higher resin content in the hybridized dentin. The dissolved dentinal substances, including the polyelectrolytes, had a significant influence on the characteristics of the demineralized dentin, changing the degree of hybridization and bonding.

  19. Simulation of Plasma Etching

    NASA Astrophysics Data System (ADS)

    Moroz, Paul; Moroz, Daniel

    2016-09-01

    Plasma is an indispensable tool in materials processing. It provides chemically and physically active species and directional flows of energetic species enabling deep etching with good straight profiles required by the industry. At present time, the only feasible methods of simulating the resulting feature profiles are those which fall within the scope of feature-scale (FS) simulation methods, utilizing engineering-type of reactions of incoming species with solid materials. At the same time, the molecule dynamics (MD) methods are emerging as an important alternative approach to simulating extremely small features with sizes below of a few nanometers. In our presentation, we discuss both FS methods implemented into the FPS3D code and MD methods implemented into the MDSS code. We also discuss the ways of extracting information about the reactions and interactions used in FS codes from the MD simulations utilizing the approach of interatomic potentials. For this presentation, we selected two types of simulation cases for etching. The first type considers simulation of mostly etching and implantation, such as during Si etching by chlorine-argon plasma. The second type considers ALE (atomic layer etch) when etching is done by a cyclic process of surface passivation/activation with the following process of etching/removal of a single atomic layer per cycle or per a few cycles, allowing ultimate processing accuracy. The simulations are carried out with both FS and MD codes to provide the data for relation and comparison between those two very different approaches.

  20. Effect of MTAD on the shear bond strength of self-etch adhesives to dentin

    PubMed Central

    Mortazavi, Vajihesadat; Khademi, Abbasali; Khosravi, Kazem; Fathi, Mohammadhossein; Ebrahimi–Chaharom, Mohammadesmaeil; Shahnaseri, Shirin; Khalighinejad, Navid; Badrian, Hamid

    2012-01-01

    Background: As the use of different irrigants to eliminate residual debris and smear layer in the field of endodontic is unavoidable, by considering the effect of irrigants on the bond strength of resin composite restorations, this study was designed to evaluate the effect of a mixture of a tetracycline isomer, an acid, and a detergent (MTAD) on the shear bond strength of two self-etch adhesives, Clearfil SE Bond and Adper Prompt L- Pop to dentin. Materials and Methods: The crowns of 80 extracted premolars were transversally sectioned to expose dentin. Flat dentin surfaces were wet abraded with 320-grit abrasive paper and randomly assigned to eight groups according to two self-etch adhesive and four dentin surface treatments: direct application over smear layer (no treatment), etching with 35% phosphoric acid for 15s, 1 min 5.25% NaOCl/1 min MTAD and 20min 1.3% NaOCl/5min MTAD. Shear bond strength was tested 24 h after storage in distilled water at 37°C in incubator. Data were analyzed using one-way ANOVA followed by duncan post-hoc (α=0.05). Results: Phosphoric acid etching prior to SE Bond application significantly decreased the shear bond strength to dentin (P<0.05). Application of MTAD clinical protocol (20min 1.3% NaOCl/5min MTAD) did not significantly decrease the shear bond strength of self-etch adhesives to dentin (P=0.745) Conclusions: Based on the results of present investigation, it seems that the use of clinical protocol of 1.3% NaOCl as a root canal irrigant and a 5-min application of MTAD as a final rinse to remove the smear layer has no adverse effect on the shear bond strength of self-etch adhesives to dentin. PMID:22363359

  1. [Azelaic acid in the treatment of acne].

    PubMed

    Nazzaro-Porro, M; Passi, S; Picardo, M; Breathnach, A S; Zina, G

    1989-04-01

    This review is an update of the literature accumulated over the past 6 years following the original observation that topically applied azelaic acid, a non-toxic C9 dicarboxylic acid, has a beneficial therapeutic effect on acne vulgaris. These studies have shown that azelaic acid has a modulating influence on the process of keratinization, and that it acts as a keratolytic and anti-comedogenic agent. There is evidence that it inhibits mitochondrial and microsomal oxido-reductases, including 5-alpha-reductase, and that it may interfere with the process of sebogenesis. It has a spectrum of antimicrobial activity, both in vitro and in vivo, against aerobic microorganisms and is effective against the anaerobic Propionibacterium acnes. Extensive multi-centre clinical trials have established that topical azelaic acid (a 20% cream) is an effective treatment for all types of acne. It compares well with other agents, such as topical tretinoin or benzoyl-peroxide, or oral tetracycline. It is non-irritant, and does not give rise to allergic or photo-toxic reactions. Its use is not associated with teratogenicity, possible endocrine unbalance, or the disadvantages of antibiotic treatment. It can be applied for long periods, in recurrences, and as maintenance "spot" therapy against individual lesions.

  2. Influence of different repair procedures on bond strength of adhesive filling materials to etched enamel in vitro.

    PubMed

    Hannig, Christian; Hahn, Petra; Thiele, Patrick-Philipp; Attin, Thomas

    2003-01-01

    Contamination of etched enamel with repair bond agents during repair of dental restorations may interfere with the bonding of composite to enamel. This study examined the bond strength of adhesive filling materials to etched bovine enamel after pre-treatment with the repair systems Monobond S, Silibond and Co-Jet. The materials Tetric Ceram, Dyract and Definite and their corresponding bonding agents (Syntac Single Comp, Prime & Bond NT, Etch and Prime) were tested in combination with the repair systems. One hundred and thirty-five enamel specimens were etched (37% phosphoric acid, 60 seconds) and equally distributed among three groups (A-C). In Group A, the repair materials were applied on etched enamel followed by applying the composite materials without using their respective bonding material. In Group B, the composite materials were placed on etched enamel after applying the repair materials and bonding agents. In control Group C, the composite materials and bonding agents were applied on etched enamel without using the repair systems. In each sub-group, every composite material was applied on 15 specimens. Samples were stored in artificial saliva for 14 days and thermocycled 1,000 times (5 degrees C/55 degrees C). The shear bond strength of the samples were then determined in a universal testing machine (ISO 10477). Applying Monobond or Silibond followed by the use of its respective bonding agents resulted in a bond strength that was not statistically different from the controls for all filling materials (Group C). The three composites that used Monobond and Silibond without applying the corresponding bonding agent resulted in bond strengths that were significantly lower than the controls. Utilizing the Co-Jet-System drastically reduced the bond strength of composites on etched enamel. Contamination of etched enamel with the repairing bonding agents Monobond and Silibond does not interfere with bond strength if the application of Monobond and Silibond is

  3. Dry etched SiO2 Mask for HgCdTe Etching Process

    NASA Astrophysics Data System (ADS)

    Chen, Y. Y.; Ye, Z. H.; Sun, C. H.; Deng, L. G.; Zhang, S.; Xing, W.; Hu, X. N.; Ding, R. J.; He, L.

    2016-09-01

    A highly anisotropic etching process with low etch-induced damage is indispensable for advanced HgCdTe (MCT) infrared focal plane array (IRFPA) detectors. The inductively coupled plasma (ICP) enhanced reactive ion etching technique has been widely adopted in manufacturing HgCdTe IRFPA devices. An accurately patterned mask with sharp edges is decisive to accomplish pattern duplication. It has been reported by our group that the SiO2 mask functions well in etching HgCdTe with high selectivity. However, the wet process in defining the SiO2 mask is limited by ambiguous edges and nonuniform patterns. In this report, we patterned SiO2 with a mature ICP etching technique, prior to which a thin ZnS film was deposited by thermal evaporation. The SiO2 film etching can be terminated at the auto-stopping point of the ZnS layer thanks to the high selectivity of SiO2/ZnS in SF6 based etchant. Consequently, MCT etching was directly performed without any other treatment. This mask showed acceptable profile due to the maturity of the SiO2 etching process. The well-defined SiO2 pattern and the etched smooth surfaces were investigated with scanning electron microscopy and atomic force microscope. This new mask process could transfer the patterns exactly with very small etch-bias. A cavity with aspect-ratio (AR) of 1.2 and root mean square roughness of 1.77 nm was achieved first, slightly higher AR of 1.67 was also get with better mask profile. This masking process ensures good uniformity and surely benefits the delineation of shrinking pixels with its high resolution.

  4. Plasma etching: Yesterday, today, and tomorrow

    SciTech Connect

    Donnelly, Vincent M.; Kornblit, Avinoam

    2013-09-15

    The field of plasma etching is reviewed. Plasma etching, a revolutionary extension of the technique of physical sputtering, was introduced to integrated circuit manufacturing as early as the mid 1960s and more widely in the early 1970s, in an effort to reduce liquid waste disposal in manufacturing and achieve selectivities that were difficult to obtain with wet chemistry. Quickly, the ability to anisotropically etch silicon, aluminum, and silicon dioxide in plasmas became the breakthrough that allowed the features in integrated circuits to continue to shrink over the next 40 years. Some of this early history is reviewed, and a discussion of the evolution in plasma reactor design is included. Some basic principles related to plasma etching such as evaporation rates and Langmuir–Hinshelwood adsorption are introduced. Etching mechanisms of selected materials, silicon, silicon dioxide, and low dielectric-constant materials are discussed in detail. A detailed treatment is presented of applications in current silicon integrated circuit fabrication. Finally, some predictions are offered for future needs and advances in plasma etching for silicon and nonsilicon-based devices.

  5. Effect of Alkaline pH on Polishing and Etching of Single and Polycrystalline Silicon

    NASA Astrophysics Data System (ADS)

    Venkatesh, R. Prasanna; Prasad, Y. Nagendra; Kwon, Tae-Young; Kang, Young-Jae; Park, Jin-Goo

    2012-07-01

    In this paper, the polishing and etching behavior of single and polycrystalline silicon were studied. Prior to chemical mechanical polishing (CMP) process, the surfaces were treated with dilute hydrofluoric acid (DHF) to remove native oxides. The surface analysis shows that the poly contains trace amount of oxygen even after DHF treatment. The static and dynamic etch rates, and removal rates were measured as a function of slurry pH. The single silicon showed a higher static etch rate than the poly. After static etch rate measurements, poly showed higher surface roughness and more hydrophilic which indicates that the surface of poly is different from single crystal silicon. The friction force between pad and substrate and pad temperature was also measured as a function of pH during polishing in order to get more understanding of polishing process. At all the pH values being investigated, poly showed lower dynamic and removal rates, higher friction force and higher temperature. This indicates that the removal of poly in CMP is predominantly by mechanical actions. Also, these results, suggest a mechanism in which the oxygen present in the poly grain boundaries strongly influences the etching and removal mechanism.

  6. Ion beam sputter etching

    NASA Technical Reports Server (NTRS)

    Banks, Bruce A.; Rutledge, Sharon K.

    1986-01-01

    An ion beam etching process which forms extremely high aspect ratio surface microstructures using thin sputter masks is utilized in the fabrication of integrated circuits. A carbon rich sputter mask together with unmasked portions of a substrate is bombarded with inert gas ions while simultaneous carbon deposition occurs. The arrival of the carbon deposit is adjusted to enable the sputter mask to have a near zero or even slightly positive increase in thickness with time while the unmasked portions have a high net sputter etch rate.

  7. Influence of microhybrid resin and etching times on bleached enamel for the bonding of ceramic brackets.

    PubMed

    Firoozmand, Leily Macedo; Brandão, Juliana Viana Pereira; Fialho, Melissa Proença Nogueira

    2013-01-01

    The aim of this study was to evaluate the shear bond strength (SBS) of polycrystalline ceramic brackets (PCB) bonded after bleaching treatment using different composite resins and enamel etching times. A total of 144 bovine incisors were randomly divided into two study groups (n = 72, each) as follows: G1, enamel bleached with 35% hydrogen peroxide, and G2 (control group), enamel unbleached. After the bleaching treatment, the samples were stored in artificial saliva for 14 days. These groups were further divided into two subgroups (n = 36, each) as follows: GA, brackets bonded with Transbond XT (3M) and GB, brackets bonded with Filtek Z250 (3M). For each resin used, three different etching times with 37% phosphoric acid (15, 30 and 60 seconds) were tested. SBS tests were performed using a universal testing machine (EMIC), and the adhesive remnant index (ARI) score was verified. Significant differences among the three experimental conditions and interactions between the groups were observed. The type of composite resin accounted for 24% of the influence on the bond strength, whereas the etching time and bleaching treatment accounted for 14.5% and 10% of the influence on bond strength, respectively. The ARI revealed that the most common area of adhesion failure was at the composite resin-bracket interface. The type of composite resin, etching time and external bleaching significantly influenced the SBS of PCB on enamel, even after 14 days of saliva storage.

  8. Acid mine water treatment using engineered wetlands

    NASA Astrophysics Data System (ADS)

    Kleinmann, Robert L. P.

    1990-03-01

    During the last two decades, the United States mining industry has greatly increased the amount it spends on pollution control. The application of biotechnology to mine water can reduce the industry's water treatment costs (estimated at over a million dollars a day) and improve water quality in streams and rivers adversely affected by acidic mine water draining from abandoned mines. Biological treatment of mine waste water is typically conducted in a series of small excavated ponds that resemble, in a superficial way, a small marsh area. The ponds are engineered to first facilitate bacterial oxidation of iron; ideally, the water then flows through a composted organic substrate that supports a population of sulfate-reducing bacteria. The latter process raises the pH. During the past four years, over 400 wetland water treatment systems have been built on mined lands as a result of research by the U.S. Bureau of Mines. In general, mine operators find that the wetlands reduce chemical treatment costs enough to repay the cost of wetland construction in less than a year. Actual rates of iron removal at field sites have been used to develop empirical sizing criteria based on iron loading and pH. If the pH is 6 or above, the wetland area (m2) required is equivalent to the iron load (grams/day) divided by 10. Theis requirement doubles at a pH of 4 to 5. At a pH below 4, the iron load (grams/day) should be divided by 2 to estimate the area required (m2).

  9. Electrolytic etching process provides effective bonding surface on stainless steel

    NASA Technical Reports Server (NTRS)

    1966-01-01

    Electrolytic etching process prepares surfaces of a stainless steel shell for reliable, high strength adhesive bonding to dielectric materials. The process uses a 25 percent aqueous solution of phosphoric acid.

  10. Enhanced blood compatibility of metallocene polyethylene subjected to hydrochloric acid treatment for cardiovascular implants.

    PubMed

    Jaganathan, Saravana Kumar; Mohandas, Hemanth; Sivakumar, Gunalan; Kasi, Palaniappan; Sudheer, Theertha; Avineri Veetil, Sruthi; Murugesan, Selvakumar; Supriyanto, Eko

    2014-01-01

    Blood compatibility of metallocene polyethylene (mPE) was investigated after modifying the surface using hydrochloric acid. Contact angle of the mPE exposed to HCl poses a decrease in its value which indicates increasing wettability and better blood compatibility. Surface of mPE analyzed by using FTIR revealed no significant changes in its functional groups after treatment. Furthermore, scanning electron microscope images supported the increasing wettability through the modifications like pit formations and etching on the acid rendered surface. To evaluate the effect of acid treatment on the coagulation cascade, prothrombin time (PT) and activated partial thromboplastin time (APTT) were measured. Both PT and APTT were delayed significantly (P < 0.05) after 60 min exposure implying improved blood compatibility of the surfaces. Hemolysis assay of the treated surface showed a remarkable decrease in the percentage of lysis of red blood cells when compared with untreated surface. Moreover, platelet adhesion assay demonstrated that HCl exposed surfaces deter the attachment of platelets and thereby reduce the chances of activation of blood coagulation cascade. These results confirmed the enhanced blood compatibility of mPE after HCl exposure which can be utilized for cardiovascular implants like artificial vascular prostheses, implants, and various blood contacting devices.

  11. Chemical downstream etching of tungsten

    SciTech Connect

    Blain, M.G.; Jarecki, R.L.; Simonson, R.J.

    1998-07-01

    The downstream etching of tungsten and tungsten oxide has been investigated. Etching of chemical vapor deposited tungsten and e-beam deposited tungsten oxide samples was performed using atomic fluorine generated by a microwave discharge of argon and NF{sub 3}. Etching was found to be highly activated with activation energies approximated to be 6.0{plus_minus}0.5thinspkcal/mol and 5.4{plus_minus}0.4thinspkcal/mol for W and WO{sub 3}, respectively. In the case of F etching of tungsten, the addition of undischarged nitric oxide (NO) directly into the reaction chamber results in the competing effects of catalytic etch rate enhancement and the formation of a nearly stoichiometric WO{sub 3} passivating tungsten oxide film, which ultimately stops the etching process. For F etching of tungsten oxide, the introduction of downstream NO reduces the etch rate. {copyright} {ital 1998 American Vacuum Society.}

  12. Effect of Ethylene diamine tetra acetic acid and sodium hypochlorite solution conditioning on microtensile bond strength of one-step self-etch adhesives

    PubMed Central

    Kasraei, Shahin; Azarsina, Mohadese; Khamverdi, Zahra

    2013-01-01

    Background: Attempts to improve bond strength of self-etch adhesives can enhance the durability of composite restorations. Aims: The aim of the present study was to evaluate the effect of collagen and smear layer removal with sodium hypochlorite solution (NaOCl) and EDTA on micro-tensile bond strength (μTBS) of self-etch adhesives to dentin. Settings and Design: It was an in-vitro study. Materials and Methods: Seventy-two teeth were divided into eight groups and their crowns were ground perpendicular to their long axis to expose dentin. The teeth were polished with silicon-carbide papers. The groups were treated as follows: No conditioning, 0.5-M EDTA conditioning, 2.5% NaOCl conditioning, NaOCl + EDTA conditioning. The surfaces were rinsed and blot-dried. Clearfil S3 and I-Bond were applied according to manufacturers’ instructions and restored with Z100 composite. After 500 cycles of thermo-cycling between 5°C and 55°C, the samples were sectioned and tested for μTBS. Statistical Analysis: Data were analyzed by two-way ANOVA and Tukey-HSD test. Results: The highest μTBS was recorded with Clearfil S3 + NaOCl + EDTA, and the lowest was recorded with I-Bond without conditioning. μTBS in EDTA-and EDTA + NaOCl-treated groups was significantly higher than the control and NaOCl-conditioned groups. Conclusions: Application of EDTA or EDTA + NaOCl before one-step self-etch adhesives increased μTBS. PMID:23833459

  13. Atomic force microscopy observation of enamel surfaces treated with self-etching primer.

    PubMed

    Hashimoto, Yusuke; Hashimoto, Yoshiya; Nishiura, Aki; Matsumoto, Naoyuki

    2013-01-01

    Orthodontists use a self-etching adhesive system when attaching brackets to enamel. The purpose of this study was to evaluate the erosion effects of common clinically used adhesive systems on human enamel surfaces by atomic force microscopy (AFM). Four commercially available adhesive systems (i. e., Kurasper F, Beauty Ortho Bond, Orthophia LC, and Transbond XT) were applied to ground enamel surfaces of extracted human teeth. Enamel surface roughness (ESR), absolute depth profile (ADP), and surface hardness were evaluated by AFM. The ESR and ADP were significantly higher after the pretreatment with the phosphoric acid-etching adhesive system than after the pretreatments with the three self-etching adhesive systems. The surface nanohardness decreased after the pretreatment with the phosphoric acid-etching adhesive system but increased after the pretreatments with the self-etching adhesive systems. These results suggest that the use of a self-etching primer for enamel conditioning might prevent decalcification caused by phosphoric acid etching.

  14. Micromorphology of ceramic etching pattern for two CAD-CAM and one conventional feldspathic porcelain and need for post-etching cleaning.

    PubMed

    Onisor, Ioana; Rocca, Giovanni Tommaso; Krejci, Ivo

    2014-01-01

    The aim of this in vitro study was to observe the effect of hydrofluoric acid (HF) on the surface of two glass ceramics for Cerec and to compare it with the effect on a conventional glass ceramic. Discs were cut from a feldspathic ceramic block (VitaMKII) and from a leucite reinforced glass ceramic (IPS EMPRESS CAD) for Cerec. 5% and 9% HF concentrations were used during 1 min and 2 min each. Afterwards samples were thoroughly water rinsed for 30 s. Half of the 9% HF 1 min samples were subsequently submitted to a complex post-etching cleaning. All samples were observed under a scanning electron microscope (SEM). The conventional feldspathic ceramic samples were built up on a refractory die and a platinum foil. They were treated with 9% HF for 2 min and water rinsed for 30 s. Half of the samples were submitted to the same post-etching cleaning protocol. All samples were examined under SEM and EDX. The Cerec ceramic samples and the platinum foil ones were clean and free of any precipitate after 30 s of water rinsing. Acid concentration, times of application and the postetching cleaning treatment did not influence the cleanliness of the samples. A thick layer of deposit was observed only on the refractory die samples. This was only diminished after the post-etching treatment. The EDX analysis detected the presence of fluoride (F) only on the refractory die samples.

  15. Lignor process for acidic rock drainage treatment.

    PubMed

    Zhuang, J M; Walsh, T

    2004-09-01

    The process using lignosulfonates for acidic rock drainage (ARD) treatment is referred to as the Lignor process. Lignosulfonates are waste by-products produced in the sulfite pulping process. The present study has shown lignosulfonates are able to protect lime from developing an external surface coating, and hence to favor its dissociation. Further, the addition of lignosulfonates to ARD solutions increased the dotting and settling rate of the formed sludge. The capability of lignosulfonates to form stable metal-lignin complexes makes them very useful in retaining metal ions and thus improving the long-term stability of the sludge against leaching. The Lignor process involves metal sorption with lignosulfonates, ARD neutralization by lime to about pH 7, pH adjustment with caustic soda to 9.4 - 9.6, air oxidation to lower the pH to a desired level, and addition of a minimum amount of FeCl3 for further removal of dissolved metals. The Lignor process removes all concerned metals (especially Al and Mn) from the ARD of the Britannia Mine (located at Britannia Beach, British Columbia, Canada) to a level lower than the limits of the B.C. Regulations. Compared with the high-density sludge (HDS) process, the Lignor process has many advantages, such as considerable savings in lime consumption, greatly reduced sludge volume, and improved sludge stability.

  16. Effects of alkali or acid treatment on the isomerization of amino acids.

    PubMed

    Ohmori, Taketo; Mutaguchi, Yuta; Doi, Katsumi; Ohshima, Toshihisa

    2012-10-01

    The effect of alkali treatment on the isomerization of amino acids was investigated. The 100×D/(D+L) values of amino acids from peptide increased with increase in the number of constituent amino acid residues. Furthermore, the N-terminal amino acid of a dipeptide was isomerized to a greater extent than the C-terminal residue.

  17. Orthodox etching of HVPE-grown GaN

    SciTech Connect

    Weyher, J.L.; Lazar, S.; Macht, L.; Liliental-Weber, Z.; Molnar,R.J.; Muller, S.; Nowak, G.; Grzegory, I.

    2006-08-10

    Orthodox etching of HVPE-grown GaN in molten eutectic of KOH + NaOH (E etch) and in hot sulfuric and phosphoric acids (HH etch) is discussed in detail. Three size grades of pits are formed by the preferential E etching at the outcrops of threading dislocations on the Ga-polar surface of GaN. Using transmission electron microscopy (TEM) as the calibration tool it is shown that the largest pits are formed on screw, intermediate on mixed and the smallest on edge dislocations. This sequence of size does not follow the sequence of the Burgers values (and thus the magnitude of the elastic energy) of corresponding dislocations. This discrepancy is explained taking into account the effect of decoration of dislocations, the degree of which is expected to be different depending on the lattice deformation around the dislocations, i.e. on the edge component of the Burgers vector. It is argued that the large scatter of optimal etching temperatures required for revealing all three types of dislocations in HVPE-grown samples from different sources also depends upon the energetic status of dislocations. The role of kinetics for reliability of etching in both etches is discussed and the way of optimization of the etching parameters is shown.

  18. Effects of Etch-and-Rinse and Self-etch Adhesives on Dentin MMP-2 and MMP-9

    PubMed Central

    Mazzoni, A.; Scaffa, P.; Carrilho, M.; Tjäderhane, L.; Di Lenarda, R.; Polimeni, A.; Tezvergil-Mutluay, A.; Tay, F.R.; Pashley, D.H.; Breschi, L.

    2013-01-01

    Auto-degradation of collagen matrices occurs within hybrid layers created by contemporary dentin bonding systems, by the slow action of host-derived matrix metalloproteinases (MMPs). This study tested the null hypothesis that there are no differences in the activities of MMP-2 and -9 after treatment with different etch-and-rinse or self-etch adhesives. Tested adhesives were: Adper Scotchbond 1XT (3M ESPE), PQ1 (Ultradent), Peak LC (Ultradent), Optibond Solo Plus (Kerr), Prime&Bond NT (Dentsply) (all 2-step etch-and-rinse adhesives), and Adper Easy Bond (3M ESPE), Tri-S (Kuraray), and Xeno-V (Dentsply) (1-step self-etch adhesives). MMP-2 and -9 activities were quantified in adhesive-treated dentin powder by means of an activity assay and gelatin zymography. MMP-2 and MMP-9 activities were found after treatment with all of the simplified etch-and-rinse and self-etch adhesives; however, the activation was adhesive-dependent. It is concluded that all two-step etch-and-rinse and the one-step self-etch adhesives tested can activate endogenous MMP-2 and MMP-9 in human dentin. These results support the role of endogenous MMPs in the degradation of hybrid layers created by these adhesives. PMID:23128110

  19. Influence of etching time on bond strength in dentin irradiated with erbium lasers.

    PubMed

    Ferreira, Leila Soares; Apel, Christian; Francci, Carlos; Simoes, Alyne; Eduardo, Carlos P; Gutknecht, Norbert

    2010-11-01

    The purpose of this in vitro study was to evaluate the effect of etching time on the tensile bond strength (TBS) of a conventional adhesive bonded to dentin previously irradiated with erbium:yttrium-aluminum-garnet (Er:YAG) and erbium, chromium:yttrium-scandium-gallium-garnet (Er,Cr:YSGG) lasers. Buccal and lingual surfaces of 45 third molars were flattened until the dentin was exposed and randomly assigned to three groups (n = 30) according to the dentin treatment: control (not irradiated), irradiated with Er:YAG (1 W; 250 mJ; 4 Hz; 80.6 J/cm(2)) laser or Er,Cr:YSGG (4 W; 200 mJ; 20 Hz; 71.4 J/cm(2)) laser, and into three subgroups (n = 10) according to acid etching time (15 s, 30 s or 60 s) for each experimental group. After acid etching, the adhesive was applied, followed by the construction of an inverted cone of composite resin. The samples were immersed in distilled water (37 degrees C for 24 h) and subjected to TBS test [50 kilogram-force (kgf), 0.5 mm/min]. Data were analyzed by analysis of variance (ANOVA) and Tukey statistical tests (P < or = 0.05). Control group samples presented significant higher TBS values than those of all lased groups. Both irradiated groups exhibited similar TBS values. Samples subjected to the different etching times in each experimental group presented similar TBS. Based on the conditions of this in vitro study we concluded that Er:YAG and Er,Cr:YSGG laser irradiation of the dentin weakens the bond strength of the adhesive. Moreover, increased etching time is not able to modify the bonding strength of the adhesive to irradiated dentin.

  20. Self-etch adhesive systems: a literature review.

    PubMed

    Giannini, Marcelo; Makishi, Patrícia; Ayres, Ana Paula Almeida; Vermelho, Paulo Moreira; Fronza, Bruna Marin; Nikaido, Toru; Tagami, Junji

    2015-01-01

    This paper presents the state of the art of self-etch adhesive systems. Four topics are shown in this review and included: the historic of this category of bonding agents, bonding mechanism, characteristics/properties and the formation of acid-base resistant zone at enamel/dentin-adhesive interfaces. Also, advantages regarding etch-and-rinse systems and classifications of self-etch adhesive systems according to the number of steps and acidity are addressed. Finally, issues like the potential durability and clinical importance are discussed. Self-etch adhesive systems are promising materials because they are easy to use, bond chemically to tooth structure and maintain the dentin hydroxyapatite, which is important for the durability of the bonding.

  1. Unveiling the wet chemical etching characteristics of polydimethylsiloxane film for soft micromachining applications

    NASA Astrophysics Data System (ADS)

    Kakati, A.; Maji, D.; Das, S.

    2017-01-01

    Micromachining of a polydimethylsiloxane (PDMS) microstructure by wet chemical etching is explored for microelectromechanical systems (MEMS) and microfluidic applications. A 100 µm thick PDMS film was patterned with different microstructure designs by wet chemical etching using a N-methyl-2-pyrrolidone (C16H36FN) and tetra-n-butylammonium fluoride (C5H9NO) mixture solution with 3:1 volume ratio after lithography for studying etching characteristics. The patterning parameters, such as etch rate, surface roughness, pH of etchant solution with time, were thoroughly investigated. A detailed study of surface morphology with etching time revealed nonlinear behaviour of the PDMS surface roughness and etch rate. A maximum rate of 1.45 µm min-1 for 10 min etching with surface roughness of 360 nm was achieved. A new approach of wet chemical etching with pH controlled doped etchant was introduced for lower surface roughness of etched microstructures, and a constant etch rate during etching. Variation of the etching rate and surface roughness by pH controlled etching was performed by doping 5-15 gm l-1 of silicic acid (SiO2x H2O) into the traditional etchant solution. PDMS etching by silicic acid doped etchant solution showed a reduction in surface roughness from 400 nm to 220 nm for the same 15 µm etching. This study is beneficial for micromachining of various MEMS and microfluidic structures such as micropillars, microchannels, and other PDMS microstructures.

  2. Surface modification with alumina blasting and H2SO4-HCl etching for bonding two resin-composite veneers to titanium.

    PubMed

    Taira, Yohsuke; Egoshi, Takafumi; Kamada, Kohji; Sawase, Takashi

    2014-02-01

    The purpose of this study was to investigate the effect of an experimental surface treatment with alumina blasting and acid etching on the bond strengths between each of two resin composites and commercially pure titanium. The titanium surface was blasted with alumina and then etched with 45wt% H2SO4 and 15wt% HCl (H2SO4-HCl). A light- and heat-curing resin composite (Estenia) and a light-curing resin composite (Ceramage) were used with adjunctive metal primers. Veneered specimens were subjected to thermal cycling between 4 and 60°C for 50,000 cycles, and the shear bond strengths were determined. The highest bond strengths were obtained for Blasting/H2SO4-HCl/Estenia (30.2 ± 4.5 MPa) and Blasting/Etching/Ceramage (26.0 ± 4.5 MPa), the values of which were not statistically different, followed by Blasting/No etching/Estenia (20.4 ± 2.4 MPa) and Blasting/No etching/Ceramage (0.8 ± 0.3 MPa). Scanning electron microscopy observations revealed that alumina blasting and H2SO4-HCl etching creates a number of micro- and nanoscale cavities on the titanium surface, which contribute to adhesive bonding.

  3. Formation of nanostructured silicon surfaces by stain etching.

    PubMed

    Ayat, Maha; Belhousse, Samia; Boarino, Luca; Gabouze, Noureddine; Boukherroub, Rabah; Kechouane, Mohamed

    2014-01-01

    In this work, we report the fabrication of ordered silicon structures by chemical etching of silicon in vanadium oxide (V2O5)/hydrofluoric acid (HF) solution. The effects of the different etching parameters including the solution concentration, temperature, and the presence of metal catalyst film deposition (Pd) on the morphologies and reflective properties of the etched Si surfaces were studied. Scanning electron microscopy (SEM) was carried out to explore the morphologies of the etched surfaces with and without the presence of catalyst. In this case, the attack on the surfaces with a palladium deposit begins by creating uniform circular pores on silicon in which we distinguish the formation of pyramidal structures of silicon. Fourier transform infrared spectroscopy (FTIR) demonstrates that the surfaces are H-terminated. A UV-Vis-NIR spectrophotometer was used to study the reflectance of the structures obtained. A reflectance of 2.21% from the etched Si surfaces in the wavelength range of 400 to 1,000 nm was obtained after 120 min of etching while it is of 4.33% from the Pd/Si surfaces etched for 15 min.

  4. Formation of nanostructured silicon surfaces by stain etching

    PubMed Central

    2014-01-01

    In this work, we report the fabrication of ordered silicon structures by chemical etching of silicon in vanadium oxide (V2O5)/hydrofluoric acid (HF) solution. The effects of the different etching parameters including the solution concentration, temperature, and the presence of metal catalyst film deposition (Pd) on the morphologies and reflective properties of the etched Si surfaces were studied. Scanning electron microscopy (SEM) was carried out to explore the morphologies of the etched surfaces with and without the presence of catalyst. In this case, the attack on the surfaces with a palladium deposit begins by creating uniform circular pores on silicon in which we distinguish the formation of pyramidal structures of silicon. Fourier transform infrared spectroscopy (FTIR) demonstrates that the surfaces are H-terminated. A UV-Vis-NIR spectrophotometer was used to study the reflectance of the structures obtained. A reflectance of 2.21% from the etched Si surfaces in the wavelength range of 400 to 1,000 nm was obtained after 120 min of etching while it is of 4.33% from the Pd/Si surfaces etched for 15 min. PMID:25435830

  5. Acid mine water aeration and treatment system

    DOEpatents

    Ackman, Terry E.; Place, John M.

    1987-01-01

    An in-line system is provided for treating acid mine drainage which basically comprises the combination of a jet pump (or pumps) and a static mixer. The jet pump entrains air into the acid waste water using a Venturi effect so as to provide aeration of the waste water while further aeration is provided by the helical vanes of the static mixer. A neutralizing agent is injected into the suction chamber of the jet pump and the static mixer is formed by plural sections offset by 90 degrees.

  6. A wet etching technique for accurate etching of GaAs/AlAs distributed Bragg reflectors

    SciTech Connect

    Bacher, K.; Harris, J.S. Jr.

    1995-07-01

    The authors have demonstrated a wet etching technique capable of producing accurate and uniform etch depths in distributed Bragg reflectors (DBRs) and other GaAs/AlAs superlattice structures. The process utilizes two selective etchants, citric acid/hydrogen peroxide in a 4:1 ratio and phosphoric acid/hydrogen peroxide/water in a 3:1:50 ratio, to sequentially etch away each pair of superlattice layers. The authors have used this technique to expose a 680 {angstrom} thick conduction GaAs layer buried beneath a 15 period, 2.1 {micro}m thick, undoped GaAs/AlAs DBR mirror. Transmission line measurements pads were formed on the exposed layer to determine the contact and sheet resistance. Comparison with a similar layer on the surface of the wafer reveals that the exposed layer is easily contacted with only a slight increase in sheet resistance indicating less than 125 {angstrom} of overetching, 0.6% of the total etch depth.

  7. Individualized Learning Package about Etching.

    ERIC Educational Resources Information Center

    Sauer, Michael J.

    An individualized learning package provides step-by-step instruction in the fundamentals of the etching process. Thirteen specific behavioral objectives are listed. A pretest, consisting of matching 15 etching terms with their definitions, is provided along with an answer key. The remainder of the learning package teaches the 13 steps of the…

  8. Experimental investigation of photoresist etching by kHz AC atmospheric pressure plasma jet

    NASA Astrophysics Data System (ADS)

    Wang, Lijun; Zheng, Yashuang; Wu, Chen; Jia, Shenli

    2016-11-01

    In this study, the mechanism of the photoresist (PR) etching by means of a kHz AC atmospheric pressure plasma jet (APPJ) is investigated. The scanning electron (SEM) and the polarizing microscope are used to perform the surface analysis, and the mechanical profilometry is applied to diagnose the etch rate. The results show that granulated structure with numerous microparticles appears at the substrate surface after APPJ treatment, and the etch rate in the etch center is the fastest and gradually slows down to the edge of etch region. In addition, the pin-ring electrode APPJ has the highest etch rate at but easy to damage the Si wafer, the double-ring APPJ is the most stable but requires long time to achieve the ideal etch result, and the etch rate and the etch result of the multi-electrode APPJ fall in between. Ar APPJ had much higher PR etch rate and more irregular etch trace than He APPJ. It is speculated that Ar APPJ is more energetic and effective in transferring reactive species to the PR surface. It is also observed that the effective etch area initially increases and then decreases as plasma jet outlet to the PR surface distance increases.

  9. [Hemoperfusion in the treatment of acute valproic acid intoxication].

    PubMed

    Peces, R; Fernández, E J; Sánchez, R J; Peces, C; Montero, A; Selgas, R

    2007-01-01

    Valproic acid is increasingly used in the treatment of epilepsy, and also prescribed for bipolar affective disorders, schizoaffective disorders, schizophrenia and migraine prophylaxis. Valproic acid intoxication with suicide attempt is a relatively common clinical problem that can result in coma, respiratory depression, pancytopenia, hemodynamic instability and death. The drug's relatively low molecular weight, small volume of distribution and saturable protein-binding render it potentially amenable to exracorporeal removal (hemodialysis, hemoperfusion or hemofiltration ), but published experience is scarce. We describe a case report involving valproic acid intoxication with ingestion of ethanol, who was successfully treated with charcoal hemoperfusion. With this treatment the half-life of valproic acid was reduced with rapid lowering of valproic acid levels and clinical improvement. Based on our experience in this patient and a review of previously reported cases, charcoal hemoperfusion should be considered for serious valproic acid intoxication because free as well as bound drug fractions are eliminated via this technique.

  10. Ultrasonic metal etching for metallographic analysis

    NASA Technical Reports Server (NTRS)

    Young, S. G.

    1971-01-01

    Ultrasonic etching delineates microstructural features not discernible in specimens prepared for metallographic analysis by standard chemical etching procedures. Cavitation bubbles in ultrasonically excited water produce preferential damage /etching/ of metallurgical phases or grain boundaries, depending on hardness of metal specimens.

  11. Enlargement of halloysite clay nanotube lumen by selective etching of aluminum oxide.

    PubMed

    Abdullayev, Elshad; Joshi, Anupam; Wei, Wenbo; Zhao, Yafei; Lvov, Yuri

    2012-08-28

    Halloysite clay tubes have 50 nm diameter and chemically different inner and outer walls (inner surface of aluminum oxide and outer surface of silica). Due to this different chemistry, the selective etching of alumina from inside the tube was realized, while preserving their external diameter (lumen diameter changed from 15 to 25 nm). This increases 2-3 times the tube lumen capacity for loading and further sustained release of active chemical agents such as metals, corrosion inhibitors, and drugs. In particular, halloysite loading efficiency for the benzotriazole increased 4 times by selective etching of 60% alumina within the tubes' lumens. Specific surface area of the tubes increased over 6 times, from 40 to 250 m(2)/g, upon acid treatment.

  12. 300 Area waste acid treatment system closure plan. Revision 1

    SciTech Connect

    1996-03-01

    This section provides a description of the Hanford Site, identifies the proposed method of 300 Area Waste Acid Treatment System (WATS) closure, and briefly summarizes the contents of each chapter of this plan.

  13. 15. INTERIOR MIDDLE BAY DETAIL VIEW, FACING WEST. ACID TREATMENT, ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    15. INTERIOR MIDDLE BAY DETAIL VIEW, FACING WEST. ACID TREATMENT, CUTTING EQUIPMENT, LOCKERS ABANDONED ON SITE. TRACKS FOR MOVEMENT OF MATERIALS VISIBLE HANGING FROM CEILING. - NASA Industrial Plant, Missile Research Laboratory, 12214 Lakewood Boulevard, Downey, Los Angeles County, CA

  14. Surface treatment of barium gallogermanate laser glass

    NASA Astrophysics Data System (ADS)

    Yang, Gang; Qian, Qi; Yang, Zhongmin

    2011-01-01

    The surface of barium gallogermanate glass is modified through HCl solution etching to remove the surface defects and contaminations. The etching process and mechanism for barium gallogermanate glass in hydrochloric acid are investigated, and its optimum conditions are determined. However, the HCl etching induces the insoluble etch product containing minute crystal particles on glass surface. By heating BGG glass at the optical fiber drawing temperature, the deposited surface layer turned to be amorphous again and results in the increase of the transmittance of glass. The results indicated that the HCl etching combined with subsequent high-temperature heat treatment is an effective approach to improve the surface quality of barium gallogermanate glass, which would reduce the optical loss of the final optical fiber.

  15. Plasma etching of cesium iodide

    NASA Astrophysics Data System (ADS)

    Yang, X.; Hopwood, J.; Tipnis, S.; Nagarkar, V.; Gaysinskiy, V.

    2002-01-01

    Thick films of cesium iodide (CsI) are often used to convert x-ray images into visible light. Spreading of the visible light within CsI, however, reduces the resolution of the resulting image. Anisotropic etching of the CsI film into an array of micropixels can improve the image resolution by confining light within each pixel. The etching process uses a high-density inductively coupled plasma to pattern CsI samples held by a heated, rf-biased chuck. Fluorine-containing gases such as CF4 are found to enhance the etch rate by an order of magnitude compared to Ar+ sputtering alone. Without inert-gas ion bombardment, however, the CF4 etch becomes self-limited within a few microns of depth due to the blanket deposition of a passivation layer. Using CF4+Ar continuously removes this layer from the lateral surfaces, but the formation of a thick passivation layer on the unbombarded sidewalls of etched features is observed by scanning electron microscopy. At a substrate temperature of 220 °C, the minimum ion-bombardment energy for etching is Ei~50 eV, and the rate depends on Ei1/2 above 65 eV. In dilute mixtures of CF4 and Ar, the etch rate is proportional to the gas-phase density of atomic fluorine. Above 50% CF4, however, the rate decreases, indicating the onset of net surface polymer deposition. These observations suggest that anisotropy is obtained through the ion-enhanced inhibitor etching mechanism. Etching exhibits an Arrhenius-type behavior in which the etch rate increases from ~40 nm/min at 40 °C to 380 nm/min at 330 °C. The temperature dependence corresponds to an activation energy of 0.13+/-0.01 eV. This activation energy is consistent with the electronic sputtering mechanism for alkali halides.

  16. 300 Area waste acid treatment system closure plan

    SciTech Connect

    LUKE, S.N.

    1999-05-17

    The Hanford Facility Dangerous Waste Permit Application is considered to be a single application organized into a General Information Portion (document number DOERL-91-28) and a Unit-Specific Portion. The scope of the Unit-Specific Portion includes closure plan documentation submitted for individual, treatment, storage, and/or disposal units undergoing closure, such as the 300 Area Waste Acid Treatment System. Documentation contained in the General Information Portion is broader in nature and could be used by multiple treatment, storage, and/or disposal units (e.g., the glossary provided in the General Information Portion). Whenever appropriate, 300 Area Waste Acid Treatment System documentation makes cross-reference to the General Information Portion, rather than duplicating text. This 300 Area Waste Acid Treatment System Closure Plan (Revision 2) includes a Hanford Facility Dangerous Waste Permit Application, Part A, Form 3. Information provided in this closure plan is current as of April 1999.

  17. Plasma etching for advanced polymer optical devices

    NASA Astrophysics Data System (ADS)

    Bitting, Donald S.

    Plasma etching is a common microfabrication technique which can be applied to polymers as well as glasses, metals, and semiconductors. The fabrication of low loss and reliable polymer optical devices commonly makes use of advanced microfabrication processing techniques similar in nature to those utilized in standard semiconductor fabrication technology. Among these techniques, plasma/reactive ion etching is commonly used in the formation of waveguiding core structures. Plasma etching is a powerful processing technique with many potential applications in the emerging field of polymer optical device fabrication. One such promising application explored in this study is in the area of thin film-substrate adhesion enhancement. Two approaches involving plasma processing were evaluated to improve substrate-thin film adhesion in the production of polymer waveguide optical devices. Plasma treatment of polymer substrates such as polycarbonate has been studied to promote the adhesion of fluoropolymer thin film coatings for waveguide device fabrication. The effects of blanket oxygen plasma etchback on substrate, microstructural substrate feature formation, and the long term performance and reliability of these methods were investigated. Use of a blanket oxygen plasma to alter the polycarbonate surface prior to fluoropolymer casting was found to have positive but limited capability to improve the adhesive strength between these polymers. Experiments show a strong correlation between surface roughness and adhesion strength. The formation of small scale surface features using microlithography and plasma etching on the polycarbonate surface proved to provide outstanding adhesion strength when compared to any other known treatment methods. Long term environmental performance testing of these surface treatment methods provided validating data. Test results showed these process approaches to be effective solutions to the problem of adhesion between hydrocarbon based polymer

  18. Submicron patterned metal hole etching

    DOEpatents

    McCarthy, Anthony M.; Contolini, Robert J.; Liberman, Vladimir; Morse, Jeffrey

    2000-01-01

    A wet chemical process for etching submicron patterned holes in thin metal layers using electrochemical etching with the aid of a wetting agent. In this process, the processed wafer to be etched is immersed in a wetting agent, such as methanol, for a few seconds prior to inserting the processed wafer into an electrochemical etching setup, with the wafer maintained horizontal during transfer to maintain a film of methanol covering the patterned areas. The electrochemical etching setup includes a tube which seals the edges of the wafer preventing loss of the methanol. An electrolyte composed of 4:1 water: sulfuric is poured into the tube and the electrolyte replaces the wetting agent in the patterned holes. A working electrode is attached to a metal layer of the wafer, with reference and counter electrodes inserted in the electrolyte with all electrodes connected to a potentiostat. A single pulse on the counter electrode, such as a 100 ms pulse at +10.2 volts, is used to excite the electrochemical circuit and perform the etch. The process produces uniform etching of the patterned holes in the metal layers, such as chromium and molybdenum of the wafer without adversely effecting the patterned mask.

  19. Method for surface treatment of a cadmium zinc telluride crystal

    DOEpatents

    James, Ralph; Burger, Arnold; Chen, Kuo-Tong; Chang, Henry

    1999-01-01

    A method for treatment of the surface of a CdZnTe (CZT) crystal that reduces surface roughness (increases surface planarity) and provides an oxide coating to reduce surface leakage currents and thereby, improve resolution. A two step process is disclosed, etching the surface of a CZT crystal with a solution of lactic acid and bromine in ethylene glycol, following the conventional bromine/methanol etch treatment, and after attachment of electrical contacts, oxidizing the CZT crystal surface.

  20. Method for surface treatment of a cadmium zinc telluride crystal

    DOEpatents

    James, R.; Burger, A.; Chen, K.T.; Chang, H.

    1999-08-03

    A method for treatment of the surface of a CdZnTe (CZT) crystal is disclosed that reduces surface roughness (increases surface planarity) and provides an oxide coating to reduce surface leakage currents and thereby, improve resolution. A two step process is disclosed, etching the surface of a CZT crystal with a solution of lactic acid and bromine in ethylene glycol, following the conventional bromine/methanol etch treatment, and after attachment of electrical contacts, oxidizing the CZT crystal surface. 3 figs.

  1. ZERODUR: bending strength data for etched surfaces

    NASA Astrophysics Data System (ADS)

    Hartmann, Peter; Leys, Antoine; Carré, Antoine; Kerz, Franca; Westerhoff, Thomas

    2014-07-01

    In a continuous effort since 2007 a considerable amount of new data and information has been gathered on the bending strength of the extremely low thermal expansion glass ceramic ZERODUR®. By fitting a three parameter Weibull distribution to the data it could be shown that for homogenously ground surfaces minimum breakage stresses exist lying much higher than the previously applied design limits. In order to achieve even higher allowable stress values diamond grain ground surfaces have been acid etched, a procedure widely accepted as strength increasing measure. If surfaces are etched taking off layers with thickness which are comparable to the maximum micro crack depth of the preceding grinding process they also show statistical distributions compatible with a three parameter Weibull distribution. SCHOTT has performed additional measurement series with etch solutions with variable composition testing the applicability of this distribution and the possibility to achieve further increase of the minimum breakage stress. For long term loading applications strength change with time and environmental media are important. The parameter needed for prediction calculations which is combining these influences is the stress corrosion constant. Results from the past differ significantly from each other. On the basis of new investigations better information will be provided for choosing the best value for the given application conditions.

  2. Polysulfone affinity membranes for the treatment of amino acid mixtures.

    PubMed

    Rodemann, K; Staude, E

    1995-06-20

    Affinity membranes for the treatment of solutions containing amino acids were obtained via lithiating polysulfone that was subsequently converted with glycidylether. From this polymer asymmetric ultrafiltration membranes were cast. The membranes were reacted with iminodiacetic acid yielding membranes fitted out with bidentate chelates. The same reaction path was applied to commercially available symmetric microfiltration membranes. The chelate-bearing membranes were complexed with Cu, Ni, and Zn ions. For the experiments with amino acids only the Cu-complexed membranes were used. The complexation constants for histidine and tryptophan for six different membranes were determined. Because of the affinity of these two amino acids for the complexed Cu ions, they could easily be separated from solutions containing amino acids such as alanine, glycine, and valine. Also, concentrating very dilute amino acid solutions was carried out successfully.

  3. Improvement in etching rate for epilayer lift-off with surfactant

    NASA Astrophysics Data System (ADS)

    Wu, Fan-Lei; Horng, Ray-Hua; Lu, Jian-Heng; Chen, Chun-Li; Kao, Yu-Cheng

    2013-03-01

    In this study, the GaAs epilayer is quickly separated from GaAs substrate by epitaxial lift-off (ELO) process with mixture etchant solution. The HF solution mixes with surfactant as mixture etchant solution to etch AlAs sacrificial layer for the selective wet etching of AlAs sacrificial layer. Addiction surfactants etchant significantly enhance the etching rate in the hydrofluoric acid etching solution. It is because surfactant provides hydrophilicity to change the contact angle with enhances the fluid properties of the mixture etchant between GaAs epilayer and GaAs substrate. Arsine gas was released from the etchant solution because the critical reaction product in semiconductor etching is dissolved arsine gas. Arsine gas forms a bubble, which easily displaces the etchant solution, before the AlAs layer was undercut. The results showed that acetone and hydrofluoric acid ratio of about 1:1 for the fastest etching rate of 13.2 μm / min. The etching rate increases about 4 times compared with pure hydrofluoric acid, moreover can shorten the separation time about 70% of GaAs epilayer with GaAs substrate. The results indicate that etching ratio and stability are improved by mixture etchant solution. It is not only saving the epilayer and the etching solution exposure time, but also reducing the damage to the epilayer structure.

  4. Northern Arabia Etched Terrain

    NASA Technical Reports Server (NTRS)

    2002-01-01

    (Released 23 May 2002) The Science Many places on Mars display scabby, eroded landscapes that commonly are referred to as etched terrain. These places have a ragged, tortured look that reveals a geologic history of intense deposition and erosion. This THEMIS image shows such a place. Here a 10 km diameter crater is superposed on the floor of a 40 km diameter crater, most of which is outside of the image but apparent in the MOLA context image. The rugged crater rim material intermingles with low, flat-topped mesas and layers with irregular outlines along with dune-like ridges on many of the flat surfaces. The horizontal layers that occur throughout the scene at different elevations are evidence of repeated episodes of deposition. The apparent ease with which these deposits have been eroded, most likely by wind, suggests that they are composed of poorly consolidated material. Air-fall sediments are the likely candidate for this material rather than lava flows. The dune-like ridges are probably inactive granule ripples produced from the interaction of wind and erosional debris. The large interior crater displays features that are the result of deposition and subsequent erosion. Its raised rim is barely discernable due to burial while piles and blocks of slumped material along the interior circumference attest to the action of erosion. Some of the blocks retain the same texture as the surrounding undisrupted surface. It appears as if the crater had been buried long enough for the overlying material to be eroded into the texture seen today. Then at some point this overburden foundered and collapsed into the crater. Continuing erosion has caused the upper layer to retreat back from what was probably the original rim of the crater, producing the noncircular appearance seen today. The length of time represented by this sequence of events as well as the conditions necessary to produce them are unknown. The Story Have you ever seen an ink etching, where the artistic cross

  5. Hydrothermal acid treatment for sugar extraction from Golenkinia sp.

    PubMed

    Choi, Sun-A; Choi, Won-Il; Lee, Jin-Suk; Kim, Seung Wook; Lee, Gye-An; Yun, Jihyun; Park, Ji-Yeon

    2015-08-01

    In this study, hydrothermal acid treatment for efficient recovery of sugar from Golenkinia sp. was investigated. The initial glucose and XMG (xylose, mannose, and galactose) contents of a prepared Golenkinia sp. solution (40g/L) were 15.05 and 5.24g/L, respectively. The microalgal cell walls were hydrolyzed, for sugar recovery, by enzymatic saccharification and/or hydrothermal acid treatment. Among the various hydrothermal acid treatment conditions, the most optimal were the 2.0% H2SO4 concentration at 150°C for 15min, under which the glucose- and XMG-extraction yields were 71.7% and 64.9%, respectively. By pH 4.8, 50°C enzymatic hydrolysis after optimal hydrothermal acid treatment, the glucose- and XMG-extraction yields were additionally increased by 8.3% and 0.8%, respectively. After hydrothermal acid treatment, the combination with the enzymatic hydrolysis process improved the total sugar yield of Golenkinia sp. to 75.4%.

  6. Layer by layer etching of LaAlSiOx

    NASA Astrophysics Data System (ADS)

    Hayashi, Hisataka

    2016-09-01

    In order to fabricate a gate transistor with high-k oxide materials, removal of high-k oxide films after gate electrode etching is necessary for the formation of ohmic contacts on source and drain regions. It is crucial that the removal process of high-k oxide film by dry etching is highly selective to and low in damage to the Si substrate in order to avoid the degradation of device performances. Sasaki et al. have achieved a high LaAlSiOx-to-Si selectivity of 6.7 using C4F8/Ar/H2 plasma. In the LaAlSiOx etching process using C4F8/Ar/H2 plasma, H2 plays a role in breaking the metal-oxygen bond to enhance etching of LaAlSiOx. Based on this result, the process was decomposed into two steps: a surface modification step using H2 plasma to break the metal-oxygen bond, and a removal step using C4F8/Ar plasma. A sequential layer by layer etching could realize low damage etching, similar to atomic layer etching. Therefore, a sequential LaAlSiOx etching process using a H2 surface modification step followed by a removal step using C4F8/Ar plasma is investigated. Experiments were carried out on 300 mm diameter wafers using the 100/13.56 MHz dual frequency superimposed capacitively coupled plasma reactor. The etching gases were H2 and C4F8/Ar for each step, respectively. Plasma process conditions were 100 MHz power of 1000 W (plasma generation), 13.56MHz power varied from 0 W to 300W (ion energy control). The substrate temperature was 40 °C. 15nm thick LaAlSiOx blanket film was used for evaluation of the etched amount. Film thickness was measured by X-ray fluorescent analysis thickness meter before and after plasma exposure. The etched amount of LaAlSiOx by the C4F8/Ar plasma step doubled with H2 modification. It is confirmed that when the C4F8/Ar plasma treatment time is sufficient to remove the surface modification layer, a self-limiting reaction is realized. Furthermore, it is confirmed that the etched amount per step can be controlled by control of the ion energy of H2

  7. Levulinic acid production by two-step acid-catalyzed treatment of Quercus mongolica using dilute sulfuric acid.

    PubMed

    Jeong, Hanseob; Jang, Soo-Kyeong; Hong, Chang-Young; Kim, Seon-Hong; Lee, Su-Yeon; Lee, Soo Min; Choi, Joon Weon; Choi, In-Gyu

    2017-02-01

    The objectives of this research were to produce a levulinic acid by two-step acid-catalyzed treatment of Quercus mongolica and to investigate the effect of treatment parameter (reaction temperature range: 100-230°C; sulfuric acid (SA) concentration range: 0-2%) on the levulinic acid yield. After 1(st) step acid-catalyzed treatment, most of the hemicellulosic C5 sugars (15.6gg/100gbiomass) were released into the liquid hydrolysate at the reaction temperature of 150°C in 1% SA; the solid fraction, which contained 53.5% of the C6 sugars, was resistant to further loss of C6 sugars. Subsequently, 2(nd) step acid-catalyzed treatment of the solid fractions was performed under more severe conditions. Finally, 16.5g/100g biomass of levulinic acid was produced at the reaction temperature of 200°C in 2% SA, corresponding to a higher conversion rate than during single-step treatment.

  8. Etching and Growth of GaAs

    NASA Technical Reports Server (NTRS)

    Seabaugh, A. C.; Mattauch, R., J.

    1983-01-01

    In-place process for etching and growth of gallium arsenide calls for presaturation of etch and growth melts by arsenic source crystal. Procedure allows precise control of thickness of etch and newly grown layer on substrate. Etching and deposition setup is expected to simplify processing and improve characteristics of gallium arsenide lasers, high-frequency amplifiers, and advanced integrated circuits.

  9. Controlled in situ etch-back

    NASA Technical Reports Server (NTRS)

    Mattauch, R. J.; Seabaugh, A. C. (Inventor)

    1981-01-01

    A controlled in situ etch-back technique is disclosed in which an etch melt and a growth melt are first saturated by a source-seed crystal and thereafter etch-back of a substrate takes place by the slightly undersaturated etch melt, followed by LPE growth of a layer by the growth melt, which is slightly supersaturated.

  10. Etching Of Semiconductor Wafer Edges

    DOEpatents

    Kardauskas, Michael J.; Piwczyk, Bernhard P.

    2003-12-09

    A novel method of etching a plurality of semiconductor wafers is provided which comprises assembling said plurality of wafers in a stack, and subjecting said stack of wafers to dry etching using a relatively high density plasma which is produced at atmospheric pressure. The plasma is focused magnetically and said stack is rotated so as to expose successive edge portions of said wafers to said plasma.

  11. Parameters affecting the formation of perfluoroalkyl acids during wastewater treatment.

    PubMed

    Guerra, P; Kim, M; Kinsman, L; Ng, T; Alaee, M; Smyth, S A

    2014-05-15

    This study examined the fate and behaviour of perfluoroalkyl acids (PFAAs) in liquid and solid samples from five different wastewater treatment types: facultative and aerated lagoons, chemically assisted primary treatment, secondary aerobic biological treatment, and advanced biological nutrient removal treatment. To the best of our knowledge, this is the largest data set from a single study available in the literature to date for PFAAs monitoring study in wastewater treatment. Perfluorooctanoic acid (PFOA) was the predominant PFAA in wastewater with levels from 2.2 to 150ng/L (influent) and 1.9 to 140ng/L (effluent). Perfluorooctanesulfonic acid (PFOS) was the predominant compound in primary sludge, waste biological sludge, and treated biosolids with concentrations from 6.4 to 2900ng/g dry weight (dw), 9.7 to 8200ng/gdw, and 2.1 to 17,000ng/gdw, respectively. PFAAs were formed during wastewater treatment and it was dependant on both process temperature and treatment type; with higher rates of formation in biological wastewater treatment plants (WWTPs) operating at longer hydraulic retention times and higher temperatures. PFAA removal by sorption was influenced by different sorption tendencies; median log values of the solid-liquid distribution coefficient estimated from wastewater biological sludge and final effluent were: PFOS (3.73)>PFDA (3.68)>PFNA (3.25)>PFOA (2.49)>PFHxA (1.93). Mass balances confirmed the formation of PFAAs, low PFAA removal by sorption, and high PFAA levels in effluents.

  12. Method of etching zirconium diboride

    SciTech Connect

    Heath, L.S.; Kwiatkowski, B.

    1988-03-31

    The invention described herein may be manufactured, used, and licensed by or for the Government for governmental purposes without the payment to us of any royalty thereon. This invention relates in general to a method of etching, zirconium diboride(ZrB/sub 2/) and, in particular, to a method of dry etching a thin film of ZrB/sub 2/ that has been deposited onto a substrate and patterned using photolithography. U.S. patent application S.N. 156, 124, filed 16 February, 1988, of Linda S. Heath for Method of Etching Titanium Diboride and assigned to a common assignee and with which this application is copending describes and claims a method of etching titanium diboride with a dry etch. Zirconium diboride, like titanium diboride, TiB/sub 2/, has become of interest in laboratory research because of its resistance to change or degradation at high temperatures. By adjusting the process parameters, one is able to attain etch rates of 67 to 140 A/min for ZrB/sub 2/. This is useful for patterning ZrB/sub 2/ as a diffusion barrier or a Schottky contact to semiconductors. The ZrB/sub 2/ film may be on a GaAs substrate.

  13. Decontamination of metals using chemical etching

    DOEpatents

    Lerch, Ronald E.; Partridge, Jerry A.

    1980-01-01

    The invention relates to chemical etching process for reclaiming contaminated equipment wherein a reduction-oxidation system is included in a solution of nitric acid to contact the metal to be decontaminated and effect reduction of the reduction-oxidation system, and includes disposing a pair of electrodes in the reduced solution to permit passage of an electrical current between said electrodes and effect oxidation of the reduction-oxidation system to thereby regenerate the solution and provide decontaminated equipment that is essentially radioactive contamination-free.

  14. Nano silver-catalyzed chemical etching of polycrystalline silicon wafer for solar cell application

    NASA Astrophysics Data System (ADS)

    Chen, S. R.; Liang, Z. C.; Wang, D. L.

    2016-03-01

    Silver nanoparticles were deposited on the surface of polycrystalline silicon wafer via vacuum thermal evaporation and metal-catalyzed chemical etching (MCCE) was conducted in a HF-H2O2 etching system. Treatment of the etched silicon wafer with HF transformed the textured structure on the surface from nanorods into nanocones. An etching time of 30 s and treatment with HF resulted in nanocones with uniform size distribution and a reflectivity as low as 1.98% across a spectral range from 300 to 1000 nm.

  15. Uniform vertical trench etching on silicon with high aspect ratio by metal-assisted chemical etching using nanoporous catalysts.

    PubMed

    Li, Liyi; Liu, Yan; Zhao, Xueying; Lin, Ziyin; Wong, Ching-Ping

    2014-01-08

    Recently, metal-assisted chemical etching (MaCE) has been proposed as a promising wet-etching method for the fabrication of micro- and nanostructures on silicon with low cost. However, uniform vertical trench etching with high aspect ratio is still of great challenge for traditional MaCE. Here we report an innovated MaCE method, which combined the use of a nanoporous gold thin film as the catalyst and a hydrofluoric acid (HF)-hydrogen peroxide (H2O2) mixture solution with a low HF-to-H2O2 concentration ratio (ρ) as the etchant. The reported method successfully fabricated vertical trenches on silicon with a width down to 2 μm and an aspect ratio of 16. The geometry of the trenches was highly uniform throughout the 3D space. The vertical etching direction was favored on both (100)- and (111)-oriented silicon substrates. The reported method was also capable of producing multiple trenches on the same substrate with individually-tunable lateral geometry. An etching mechanism including a through-catalyst mass-transport process and an electropolishing-favored charge-transport process was identified by a comparative study. The novel method fundamentally solves the problems of distortion and random movement of isolated catalysts in MaCE. The results mark a breakthrough in high-quality silicon trench-etching technology with a cost of more than 2 orders of magnitude lower than that of the currently available methods.

  16. Femtosecond laser etching of dental enamel for bracket bonding.

    PubMed

    Kabas, Ayse Sena; Ersoy, Tansu; Gülsoy, Murat; Akturk, Selcuk

    2013-09-01

    The aim is to investigate femtosecond laser ablation as an alternative method for enamel etching used before bonding orthodontic brackets. A focused laser beam is scanned over enamel within the area of bonding in a saw tooth pattern with a varying number of lines. After patterning, ceramic brackets are bonded and bonding quality of the proposed technique is measured by a universal testing machine. The results are compared to the conventional acid etching method. Results show that bonding strength is a function of laser average power and the density of the ablated lines. Intrapulpal temperature changes are also recorded and observed minimal effects are observed. Enamel surface of the samples is investigated microscopically and no signs of damage or cracking are observed. In conclusion, femtosecond laser exposure on enamel surface yields controllable patterns that provide efficient bonding strength with less removal of dental tissue than conventional acid-etching technique.

  17. Dry Ice Etches Terrain

    NASA Technical Reports Server (NTRS)

    2007-01-01

    [figure removed for brevity, see original site] Figure 1

    Every year seasonal carbon dioxide ice, known to us as 'dry ice,' covers the poles of Mars. In the south polar region this ice is translucent, allowing sunlight to pass through and warm the surface below. The ice then sublimes (evaporates) from the bottom of the ice layer, and carves channels in the surface.

    The channels take on many forms. In the subimage shown here (figure 1) the gas from the dry ice has etched wide shallow channels. This region is relatively flat, which may be the reason these channels have a different morphology than the 'spiders' seen in more hummocky terrain.

    Observation Geometry Image PSP_003364_0945 was taken by the High Resolution Imaging Science Experiment (HiRISE) camera onboard the Mars Reconnaissance Orbiter spacecraft on 15-Apr-2007. The complete image is centered at -85.4 degrees latitude, 104.0 degrees East longitude. The range to the target site was 251.5 km (157.2 miles). At this distance the image scale is 25.2 cm/pixel (with 1 x 1 binning) so objects 75 cm across are resolved. The image shown here has been map-projected to 25 cm/pixel . The image was taken at a local Mars time of 06:57 PM and the scene is illuminated from the west with a solar incidence angle of 75 degrees, thus the sun was about 15 degrees above the horizon. At a solar longitude of 219.6 degrees, the season on Mars is Northern Autumn.

  18. Effects of ursodeoxycholic acid treatment on essential fatty acid deficiency in patients with biliary atresia.

    PubMed

    Yamashiro, Y; Ohtsuka, Y; Shimizu, T; Nittono, H; Urao, M; Miyano, T; Kawakami, S; Hayasawa, H

    1994-03-01

    To assess whether ursodeoxycholic acid (UDCA) treatment has any beneficial effect on essential fatty acid (EFA) deficiency in patients who have had a Kasai operation for extrahepatic atresia (EBA), responses of serum fatty acids to UDCA administration (15 mg/kg/d) were investigated in eight jaundice-free patients and in eight patients with jaundice (serum total bilirubin > or = 1.0 mg/dL). All patients were also given taurine supplementation (100 mg/kg/d). Serum fatty acid composition was determined before and 6 months after UDCA treatment. Serum total bile acid concentration and serum total bilirubin value, as a part of conventional liver function tests, were measured before and during UDCA therapy. Before UDCA treatment, the concentrations of linoleic acid and arachidonic acid were significantly lower (P > .05 for the former; P > .01 for the latter) in both the jaundice and jaundice-free groups than in the controls. After 6 months of treatment, the linoleic acid concentration significantly increased (P > .05), to the normal range, in the jaundice-free group, but not in the jaundice group. The arachidonic acid concentration did not increase significantly in either group. The serum total bile acid concentration was lower in six of the eight jaundice-free patients and in four of the eight jaundice patients. The serum total bilirubin value decreased in six of the eight jaundice-free patients and in four of the eight jaundice patients; however, the degree of improvement was not statistically significant in either group. No side effects developed, and there were no changes in blood chemistry values unrelated to liver disease.(ABSTRACT TRUNCATED AT 250 WORDS)

  19. Graphene-Assisted Chemical Etching of Silicon Using Anodic Aluminum Oxides as Patterning Templates.

    PubMed

    Kim, Jungkil; Lee, Dae Hun; Kim, Ju Hwan; Choi, Suk-Ho

    2015-11-04

    We first report graphene-assisted chemical etching (GaCE) of silicon by using patterned graphene as an etching catalyst. Chemical-vapor-deposition-grown graphene transferred on a silicon substrate is patterned to a mesh with nanohole arrays by oxygen plasma etching using an anodic- aluminum-oxide etching mask. The prepared graphene mesh/silicon is immersed in a mixture solution of hydrofluoric acid and hydro peroxide with various molecular fractions at optimized temperatures. The silicon underneath graphene mesh is then selectively etched to form aligned nanopillar arrays. The morphology of the nanostructured silicon can be controlled to be smooth or porous depending on the etching conditions. The experimental results are systematically discussed based on possible mechanisms for GaCE of Si.

  20. Comparison the effectiveness of pyruvic acid 50% and salicylic acid 30% in the treatment of acne

    PubMed Central

    Jaffary, Fariba; Faghihi, Gita; Saraeian, Sara; Hosseini, Sayed Mohsen

    2016-01-01

    Background: Acne vulgaris is a chronic inflammatory disease of the pilosebaceous follicles and one of the most common skin diseases. The peeling method has been recently found to be effective for acne treatment. This study aimed to compare the efficacy of pyruvic acid 50% and salicylic acid 30% peeling in the treatment of mild to moderate acne. Materials and Methods: In a prospective single-blinded clinical trial, 86 patients with acne were randomly assigned into two groups. In both groups, the routine treatment of acne (topical solution of erythromycin 4%, triclorocarban soap, and sunscreen) were used twice a day for 8 weeks. In addition, salicylic acid 30% for the control group and pyruvic acid 50% for the case group were used. In both groups, acne severity index (ASI) was calculated before and at week 2, 4, 6, and 8 of the treatment. Patient satisfaction was assessed at the end of the treatment. Side effects were recorded using a checklist. Results: In both groups, the reduction in the number of comedones, papules, and ASI were statistically significant (P < 0.001) in the course of treatment. However, it was not significant regarding the number of pustules (P = 0.09). None of the number of comedone, papules, pustules, and ASI was statistically different between study groups. Both treatment groups had similar side effects except for scaling in the fifth session, which was significantly lower in salicylic acid – treated patients (P = 0.015). Conclusion: Both pyruvic acid 50% and salicylic acid 30% are effective in the improvement of mild to moderate acne with no significant difference in efficacy and side effects. PMID:27904577

  1. Eighteen-month clinical performance of a self-etching primer in unprepared class V resin restorations.

    PubMed

    Brackett, Willliam W; Brackett, Martha Goel; Dib, Alejandro; Franco, Guillermo; Estudillo, Hugo

    2005-01-01

    This study evaluated the clinical performance of unprepared Class V resin composites, placed using a self-etching primer and a single-bottle adhesive, over a period of 18 months. Thirty-eight pairs of restorations of Renew hybrid resin composite (BISCO, Inc) were placed using adhesives from the same manufacturer in caries-free cervical erosion/abfraction lesions. Based on insensitivity to air, the dentin in 76% of these lesions was considered to be sclerotic. The restorations were placed without abrasion of tooth surfaces, except for cleaning with plain pumice. One of each pair was placed using Tyrian, a self-etching primer and the other was placed using One-Step, a single-bottle adhesive placed after acid etching. Both the etchant and self-etching primer were applied for 20 seconds. The restorations were clinically evaluated at baseline, 6, 12 and 18 months, using modified Ryge/USPHS criteria. For both adhesives, very low retention of 50% to 56% of the restorations was observed over 18 months, leading to the conclusion that tooth surfaces must receive some additional treatment prior to restoration with these adhesives. No statistically significant difference (p=0.75) between the two adhesives was observed in overall performance, and dentinal sclerosis and axial depth did not appear to be important factors in the study.

  2. EFFECT OF AN ADDITIONAL HYDROPHILIC VERSUS HYDROPHOBIC COAT ON THE QUALITY OF DENTINAL SEALING PROVIDED BY TWO-STEP ETCH-AND-RINSE ADHESIVES

    PubMed Central

    Silva, Safira Marques de Andrade; Carrilho, Marcela Rocha de Oliveira; Marquezini, Luiz; Garcia, Fernanda Cristina Pimentel; Manso, Adriana Pigozzo; Alves, Marcelo Corrêa; de Carvalho, Ricardo Marins

    2009-01-01

    Objective: To test the hypothesis that the quality of the dentinal sealing provided by two-step etch-and-rinse adhesives cannot be altered by the addition of an extra layer of the respective adhesive or the application of a more hydrophobic, non-solvated resin. Material and Methods: full-crown preparations were acid-etched with phosphoric acid for 15 s and bonded with Adper Single Bond (3M ESPE), Excite DSC (Ivoclar/Vivadent) or Prime & Bond NT (Dentsply). The adhesives were used according to the manufacturers' instructions (control groups) or after application to dentin they were a) covered with an extra coat of each respective system or b) coated with a non-solvated bonding agent (Adper Scotchbond Multi-Purpose Adhesive, 3M ESPE). Fluid flow rate was measured before and after dentin surfaces were acid-etched and bonded with adhesives. Results: None of the adhesives or experimental treatments was capable to block completely the fluid transudation across the treated dentin. Application of an extra coat of the adhesive did not reduce the fluid flow rate of adhesive-bonded dentin (p>0.05). Conversely, the application of a more hydrophobic non-solvated resin resulted in significant reductions in the fluid flow rate (p<0.05) for all tested adhesives. Conclusions: The quality of the dentinal sealing provided by etch-and-rinse adhesives can be significantly improved by the application of a more hydrophobic, non-solvated bonding agent. PMID:19466248

  3. DEVELOPMENT OF SRB TREATMENT SYSTEMS FOR ACID MINE DRAINAGE

    EPA Science Inventory

    Over the past decade, significant advances have been made in the development of sulfate- reducing bacteria (SRB) technology to treat acid mine drainage (AMD), Bench-scale testing, field demonstrations, and engineered applications of SRBs for the treatment of AMD will be presented...

  4. Atomic layer etching removal of damaged layers in a contact hole for low sheet resistance

    SciTech Connect

    Kim, Jong Kyu; Cho, Sung Il; Lee, Sung Ho; Kim, Chan Kyu; Min, Kyung Suk; Yeom, Geun Young

    2013-11-15

    A damaged layer remains on silicon substrates after high-aspect-ratio contact (HARC) etching when using a fluorocarbon gas. Atomic layer etching (ALET) is a technique that can be applied to remove the damaged layer of silicon, removing about 1.36 Å per etch cycle. The characteristics of contact damage removal by ALET are investigated and compared with the conventional damage removal technique of low-power CF{sub 4} plasma etching. The low-power CF{sub 4} plasma etching technique not only has inadequate etch depth control, but also introduces secondary damage by implanting impurities about 25 Å into the contact bottom of the silicon surface. However, ALET allows contact damage to be removed effectively without introducing secondary damage to the substrate, and with precision etch depth control at the angstrom scale. When ALET is applied subsequent to low-power CF{sub 4} plasma etching, the fluorine- and carbon-damaged silicon is effectively removed in about 10 cycles. The sheet resistance of HARC etched silicon decreases from 142 to 137 Ω/□ after using low-power CF{sub 4} plasma etching, and subsequent ALET treatment further decreases the sheet resistance to 129 Ω/□, which is close to the reference value of 124 Ω/□.

  5. Free amino acids: an innovative treatment for ocular surface disease.

    PubMed

    Rusciano, Dario; Roszkowska, Anna Maria; Gagliano, Caterina; Pezzino, Salvatore

    2016-09-15

    Amino acids are the basic constituents of living organisms, and have both a structural and an active dynamic role in tissue and cell physiology. Human tears contain 23 amino acids, the relative proportion of which may change with the different physiological states of the eye surface. In this review, we present a collection of data from the published literature that indicate an active role of amino acids in the maintenance of eye surface homeostasis. Moreover, another series of published clinical data indicate that supplementation of amino acids, either as food supplements or as a topical treatment in enriched eye drops, is beneficial to the eye surface, and may improve its healing in cases of eye surface disease due to different causes.

  6. Comparison of clindamycin 1% and benzoyl peroxide 5% gel to a novel composition containing salicylic acid, capryloyl salicylic acid, HEPES, glycolic acid, citric acid, and dioic acid in the treatment of acne vulgaris.

    PubMed

    Baumann, Leslie S; Oresajo, Christian; Yatskayer, Margarita; Dahl, Amanda; Figueras, Kristian

    2013-03-01

    This study evaluated the tolerance and efficacy of 2 facial skin products in subjects with acne using the following acne treatments: 1) treatment A, a combination of salicylic acid, capryloyl salicylic acid, HEPES, glycolic acid, citric acid, and dioic acid, and 2) treatment B (BenzaClin®, clindamycin 1% and benzoyl peroxide 5% gel). The treatment design included the split-face application of treatment A and treatment B and the full-face application of the cleanser, moisturizer, and sunscreen. Data were collected through physician visual assessments, subject irritation questionnaires and assessments, along with clinical photography. Results showed similar tolerance and efficacy for both treatments.

  7. State of the art etch-and-rinse adhesives

    PubMed Central

    Pashley, David H; Tay, Franklin R; Breschi, Lorenzo; Tjäderhane, Leo; Carvalho, Ricardo M; Carrilho, Marcela; Tezvergil-Mutluay, Arzu

    2013-01-01

    Etch-and-rinse adhesive systems are the oldest of the multi-generation evolution of resin bonding systems. In the 3-step version, they involve acid-etching, priming and application of a separate adhesive. Each step can accomplish multiple goals. This review explores the therapeutic opportunities of each separate step. Acid-etching, using 32-37% phosphoric acid (pH 0.1-0.4) not only simultaneously etches enamel and dentin, but the low pH kills many residual bacteria. Some etchants include anti-microbial compounds such as benzalkonium chloride that also inhibits matrix metalloproteinases (MMPs) in dentin. Primers are usually water and HEMA-rich solutions that ensure complete expansion of the collagen fibril meshwork and wet the collagen with hydrophilic monomers. However, water alone can re-expand dried dentin and can also serve as a vehicle for protease inhibitors or protein cross-linking agents that may increase the durability of resin-dentin bonds. In the future, ethanol or other water-free solvents may serve as dehydrating primers that may also contain antibacterial quaternary ammonium methacrylates to inhibit dentin MMPs and increase the durability of resin-dentin bonds. The complete evaporation of solvents is nearly impossible. Manufacturers may need to optimize solvent concentrations. Solvent-free adhesives can seal resin-dentin interfaces with hydrophobic resins that may also contain fluoride and antimicrobial compounds. Etch-and-rinse adhesives produce higher resin-dentin bonds that are more durable than most 1 and 2-step adhesives. Incorporation of protease inhibitors in etchants and/or cross-linking agents in primers may increase the durability of resin-dentin bonds. The therapeutic potential of etch-and-rinse adhesives has yet to be fully exploited. PMID:21112620

  8. Regenerative Electroless Etching of Silicon.

    PubMed

    Kolasinski, Kurt W; Gimbar, Nathan J; Yu, Haibo; Aindow, Mark; Mäkilä, Ermei; Salonen, Jarno

    2017-01-09

    Regenerative electroless etching (ReEtching), described herein for the first time, is a method of producing nanostructured semiconductors in which an oxidant (Ox1 ) is used as a catalytic agent to facilitate the reaction between a semiconductor and a second oxidant (Ox2 ) that would be unreactive in the primary reaction. Ox2 is used to regenerate Ox1 , which is capable of initiating etching by injecting holes into the semiconductor valence band. Therefore, the extent of reaction is controlled by the amount of Ox2 added, and the rate of reaction is controlled by the injection rate of Ox2 . This general strategy is demonstrated specifically for the production of highly luminescent, nanocrystalline porous Si from the reaction of V2 O5 in HF(aq) as Ox1 and H2 O2 (aq) as Ox2 with Si powder and wafers.

  9. Rapid acid treatment of Escherichia coli: transcriptomic response and recovery

    PubMed Central

    Kannan, Geetha; Wilks, Jessica C; Fitzgerald, Devon M; Jones, Brian D; BonDurant, Sandra S; Slonczewski, Joan L

    2008-01-01

    Background Many E. coli genes show pH-dependent expression during logarithmic growth in acid (pH 5–6) or in base (pH 8–9). The effect of rapid pH change, however, has rarely been tested. Rapid acid treatment could distinguish between genes responding to external pH, and genes responding to cytoplasmic acidification, which occurs transiently following rapid external acidification. It could reveal previously unknown acid-stress genes whose effects are transient, as well as show which acid-stress genes have a delayed response. Results Microarray hybridization was employed to observe the global gene expression of E. coli K-12 W3110 following rapid acidification of the external medium, from pH 7.6 to pH 5.5. Fluorimetric observation of pH-dependent tetR-YFP showed that rapid external acidification led to a half-unit drop in cytoplasmic pH (from pH 7.6 to pH 6.4) which began to recover within 20 s. Following acid treatment, 630 genes were up-regulated and 586 genes were down-regulated. Up-regulated genes included amino-acid decarboxylases (cadA, adiY, gadA), succinate dehydrogenase (sdhABCD), biofilm-associated genes (bdm, gatAB, and ymgABC), and the Gad, Fur and Rcs regulons. Genes with response patterns consistent with cytoplasmic acid stress were revealed by addition of benzoate, a membrane-permeant acid that permanently depresses cytoplasmic pH without affecting external pH. Several genes (yagU, ygiN, yjeI, and yneI) were up-regulated specifically by external acidification, while other genes (fimB, ygaC, yhcN, yhjX, ymgABC, yodA) presented a benzoate response consistent with cytoplasmic pH stress. Other genes (the nuo operon for NADH dehydrogenase I, and the HslUV protease) showed delayed up-regulation by acid, with expression rising by 10 min following the acid shift. Conclusion Transcriptomic profiling of E. coli K-12 distinguished three different classes of change in gene expression following rapid acid treatment: up-regulation with or without recovery, and

  10. Inductively coupled plasma reactive ion etching of III-nitride semiconductors

    NASA Astrophysics Data System (ADS)

    Shah, A. P.; Laskar, M. R.; Rahman, A. A.; Gokhale, M. R.; Bhattacharya, A.

    2013-02-01

    III-Nitride semiconductor materials are resistant to most wet chemical etch processes, and hence the only viable alternative is to use dry etching for device processing. However, the conventional Reactive Ion Etching (RIE) process results in very slow etch-rates because of low reactive ion density, and larger surface damage due to high energy ion bombardment. Using Inductively Coupled Plasma (ICP) RIE, a very fast etch-rate and smooth morphology is achieved due to independent control of ion density and ion energy. In this paper, we present our results on ICP-RIE of epitaxial III-N materials, namely c-plane and a-plane oriented GaN, AlN, AlxGa1-xN using various chlorine plasma chemistries based on Cl2 and BCl3. We have examined the role of BCl3 deoxidising pre-treatment on the etching of AlGaN alloys.

  11. Effect of acid concentration and treatment time on acid-alcohol modified jackfruit seed starch properties.

    PubMed

    Dutta, Himjyoti; Paul, Sanjib Kumar; Kalita, Dipankar; Mahanta, Charu Lata

    2011-09-15

    The properties of starch extracted from jackfruit (Artocarpus heterophyllus Lam.) seeds, collected from west Assam after acid-alcohol modification by short term treatment (ST) for 15-30min with concentrated hydrochloric acid and long term treatment (LT) for 1-15days with 1M hydrochloric acid, were investigated. Granule density, freeze thaw stability, solubility and light transmittance of the treated starches increased. A maximum decrease in the degree of polymerisation occurred in ST of 30min (2607.6). Jackfruit starch had 27.1±0.04% amylose content (db), which in ST initially decreased and then increased with the severity of treatment; in LT the effect was irregular. The pasting profile and granule morphology of the treated samples were severely modified. Native starch had the A-type crystalline pattern and crystalline structure increased on treatment. FTIR spectra revealed slight changes in bond stretching and bending. Colour measurement indicated that whiteness increased on treatment. Acid modified jackfruit seed starch can have applications in the food industry.

  12. Sludge recycle and reuse in acid mine drainage treatment

    SciTech Connect

    Keefer, G.B.; Sack, W.A.

    1983-03-01

    Neutralization of acid mine drainage produces vast quantities of iron-rich sludge, and large quantities of unused lime remain in the sludge after treatment. In a study in which sludge was recycled to increase lime utilization, sludge was mixed with raw acid mine drainage and settled out in an intermediate clarifier. The clarifier supernatant was then treated by lime addition, aeration and sedimentation. The low-pH sludge was withdrawn from the intermediate clarifier. The iron was recovered by acidification and used as wastewater coagulant. The recycle scheme resulted in a 30% decrease in lime requirements, and the resultant coagulant performed well when compared with stock iron coagulant solutions.

  13. Acidic and hydrogen peroxide treatment of polyaluminum chloride (PACL) sludge from water treatment.

    PubMed

    Kwon, J H; Park, K Y; Park, J H; Lee, S H; Ahn, K H

    2004-01-01

    The water treatment sludge including coagulants cannot be easily removed by conventional dewatering methods. The possibility of hydrogen peroxide (H2O2) oxidation as a pretreatment to enhance the dewaterability of polyaluminum chloride (PACl) sludge from water works was investigated. H2O2 treatment alone was not effective but H2O2 treatment under acidic condition significantly reduced both the cake water content and specific resistance to filtration (SRF), indicating the enhancement of dewaterability and filterability. The filterability after acid/H2O2 treatment was comparable to polymer conditioning and even more dewatered cake than polymer conditioning was produced. By H202 combined with sulfuric acid (H2SO4), leached iron caused Fenton's reaction, which showed a potential to significantly reduce the amount of solids mass and to produce more compact cake with higher filterability.

  14. Effect of 82% Lactic Acid in Treatment of Melasma

    PubMed Central

    Singh, Rashmi; Goyal, Sapna; Ahmed, Qazi Rais; Gupta, Narendra; Singh, Sujata

    2014-01-01

    Melasma is an acquired, chronic, and symmetrical hypermelanosis, characterized by brown patches of variable darkness on sun exposed areas of body. There are numerous modalities of treatment currently in use for this disease, of which the chemical peeling is very commonly used. Therefore, the present work was done to see the effect of 82% lactic acid peel in the treatment of melasma. A total number of 20 patients of either sex attending the OPD of dermatology department with clinically evident melasma were included in the study. 82% Lactic acid peel was applied on the face for 12 weeks in each patient. Patients were evaluated clinically and photographically at various intervals and in follow-up till 24 weeks. Assessment of patient satisfaction and side effects were also noted. All the subjects completed the study. Application of this peel for 12 weeks significantly decreased the melasma area severity index score and also melasma severity scale score. Patient and physician analogue scales also showed the improvement by the treatment. Regarding the adverse effects, burning sensation was the only side effect noted in our study. In conclusion, 82% lactic acid peel is well tolerated and can be used for the treatment of melasma. PMID:27355080

  15. Chemical etching of boron-rich layer and its impact on high efficiency n-type silicon solar cells

    NASA Astrophysics Data System (ADS)

    Ryu, Kyungsun; Upadhyaya, Ajay; Song, Hyun-Jin; Choi, Chel-Jong; Rohatgi, Ajeet; Ok, Young-Woo

    2012-08-01

    This paper reports on an effective chemical etching treatment to remove a boron-rich layer which has a significant negative impact on n-type silicon (Si) solar cells with boron emitter. A nitric acid-grown oxide/silicon nitride stack passivation on the boron-rich layer-etched boron emitter markedly decreases the emitter saturation current density J0e from 430 to 100 fA/cm2. This led to 1.6% increase in absolute cell efficiency including 22 mV increase in open-circuit voltage Voc and 1.9 mA/cm2 increase in short-circuit current density Jsc. This resulted in screen-printed large area (239 cm2) n-type Si solar cells with efficiency of 19.0%.

  16. Effect of dimethyl sulfoxide on bond durability of fiber posts cemented with etch-and-rinse adhesives

    PubMed Central

    Shafiei, Fereshteh; Sarafraz, Zahra

    2016-01-01

    PURPOSE This study was undertaken to investigate whether use of an adhesive penetration enhancer, dimethyl sulfoxide (DMSO), improves bond stability of fiber posts to root dentin using two two-step etch-and-rinse resin cements. MATERIALS AND METHODS Forty human maxillary central incisor roots were randomly divided into 4 groups after endodontic treatment and post space preparation, based on the fiber post/cement used with and without DMSO pretreatment. Acid-etched root dentin was treated with 5% DMSO aqueous solution for 60 seconds or with distilled water (control) prior to the application of Excite DSC/Variolink II or One-Step Plus/Duo-link for post cementation. After micro-slicing the bonded root dentin, push-out bond strength (P-OBS) test was performed immediately or after 1-year of water storage in each group. Data were analyzed using three-way ANOVA and Student's t-test (α=.05). RESULTS A significant effect of time, DMSO treatment, and treatment × time interaction were observed (P<.001). DMSO did not affect immediate bonding of the two cements. Aging significantly reduced P-OBS in control groups (P<.001), while in DMSO-treated groups, no difference in P-OBS was observed after aging (P>.05). CONCLUSION DMSO-wet bonding might be a beneficial method in preserving the stability of resin-dentin bond strength over time when fiber post is cemented with the tested etch-and-rinse adhesive cements. PMID:27555893

  17. Glycyrrhizic Acid in the Treatment of Liver Diseases: Literature Review

    PubMed Central

    Li, Jian-yuan; Cao, Hong-yan; Cheng, Gen-hong; Sun, Ming-yu

    2014-01-01

    Glycyrrhizic acid (GA) is a triterpene glycoside found in the roots of licorice plants (Glycyrrhiza glabra). GA is the most important active ingredient in the licorice root, and possesses a wide range of pharmacological and biological activities. GA coupled with glycyrrhetinic acid and 18-beta-glycyrrhetic acid was developed in China or Japan as an anti-inflammatory, antiviral, and antiallergic drug for liver disease. This review summarizes the current biological activities of GA and its medical applications in liver diseases. The pharmacological actions of GA include inhibition of hepatic apoptosis and necrosis; anti-inflammatory and immune regulatory actions; antiviral effects; and antitumor effects. This paper will be a useful reference for physicians and biologists researching GA and will open the door to novel agents in drug discovery and development from Chinese herbs. With additional research, GA may be more widely used in the treatment of liver diseases or other conditions. PMID:24963489

  18. Modification of the Surface Topography and Composition of Ultrafine and Coarse Grained Titanium by Chemical Etching

    PubMed Central

    Nazarov, Denis V.; Zemtsova, Elena G.; Solokhin, Alexandr Yu.; Valiev, Ruslan Z.; Smirnov, Vladimir M.

    2017-01-01

    In this study, we present the detailed investigation of the influence of the etching medium (acidic or basic Piranha solutions) and the etching time on the morphology and surface relief of ultrafine grained (UFG) and coarse grained (CG) titanium. The surface relief and morphology have been studied by means of scanning electron microscopy (SEM), atomic force microscopy (AFM), and the spectral ellipsometry. The composition of the samples has been determined by X-ray fluorescence analysis (XRF) and X-ray Photoelectron Spectroscopy (XPS). Significant difference in the etching behavior of UFG and CG titanium has been found. UFG titanium exhibits higher etching activity independently of the etching medium. Formed structures possess higher homogeneity. The variation of the etching medium and time leads to micro-, nano-, or hierarchical micro/nanostructures on the surface. Significant difference has been found between surface composition for UFG titanium etched in basic and acidic Piranha solution. Based on the experimental data, the possible reasons and mechanisms are considered for the formation of nano- and microstructures. The prospects of etched UFG titanium as the material for implants are discussed. PMID:28336849

  19. Removal of coagulant aluminum from water treatment residuals by acid.

    PubMed

    Okuda, Tetsuji; Nishijima, Wataru; Sugimoto, Mayo; Saka, Naoyuki; Nakai, Satoshi; Tanabe, Kazuyasu; Ito, Junki; Takenaka, Kenji; Okada, Mitsumasa

    2014-09-01

    Sediment sludge during coagulation and sedimentation in drinking water treatment is called "water treatment residuals (WTR)". Polyaluminum chloride (PAC) is mainly used as a coagulant in Japan. The recycling of WTR has been desired; one method for its reuse is as plowed soil. However, WTR reuse in this way is inhibited by the aluminum from the added PAC, because of its high adsorption capacity for phosphate and other fertilizer components. The removal of such aluminum from WTR would therefore be advantageous for its reuse as plowed soil; this research clarified the effect of acid washing on aluminum removal from WTR and on plant growth in the treated soil. The percentage of aluminum removal from raw WTR by sulphuric acid solution was around 90% at pH 3, the percentage decreasing to 40% in the case of a sun-dried sample. The maximum phosphate adsorption capacity was decreased and the available phosphorus was increased by acid washing, with 90% of aluminum removal. The enhancement of Japanese mustard spinach growth and the increased in plant uptake of phosphates following acid washing were observed.

  20. Osteogenic activity of titanium surfaces with hierarchical micro-/nano-structures obtained by hydrofluoric acid treatment.

    PubMed

    Liang, Jianfei; Xu, Shanshan; Shen, Mingming; Cheng, Bingkun; Li, Yongfeng; Liu, Xiangwei; Qin, Dongze; Bellare, Anuj; Kong, Liang

    2017-01-01

    An easier method for constructing the hierarchical micro-/nano-structures on the surface of dental implants in the clinic is needed. In this study, three different titanium surfaces with microscale grooves (width 0.5-1, 1-1.5, and 1.5-2 μm) and nanoscale nanoparticles (diameter 20-30, 30-50, and 50-100 nm, respectively) were obtained by treatment with different concentrations of hydrofluoric acid (HF) and at different etching times (1%, 3 min; 0.5%, 12 min; and 1.5%, 12 min, respectively; denoted as groups HF1, HF2, and HF3). The biological response to the three different titanium surfaces was evaluated by in vitro human bone marrow-derived mesenchymal stem cell (hBMMSC) experiments and in vivo animal experiments. The results showed that cell adhesion, proliferation, alkaline phosphatase activity, and mineralization of hBMMSCs were increased in the HF3 group. After the different surface implants were inserted into the distal femurs of 40 rats, the bone-implant contact in groups HF1, HF2, and HF3 was 33.17%±2.2%, 33.82%±3.42%, and 41.04%±3.08%, respectively. Moreover, the maximal pullout force in groups HF1, HF2, and HF3 was 57.92±2.88, 57.83±4.09, and 67.44±6.14 N, respectively. The results showed that group HF3 with large micron grooves (1.5-2.0 μm) and large nanoparticles (50-100 nm) showed the best bio-functionality for the hBMMSC response and osseointegration in animal experiments compared with other groups.

  1. Osteogenic activity of titanium surfaces with hierarchical micro-/nano-structures obtained by hydrofluoric acid treatment

    PubMed Central

    Liang, Jianfei; Xu, Shanshan; Shen, Mingming; Cheng, Bingkun; Li, Yongfeng; Liu, Xiangwei; Qin, Dongze; Bellare, Anuj; Kong, Liang

    2017-01-01

    An easier method for constructing the hierarchical micro-/nano-structures on the surface of dental implants in the clinic is needed. In this study, three different titanium surfaces with microscale grooves (width 0.5–1, 1–1.5, and 1.5–2 μm) and nanoscale nanoparticles (diameter 20–30, 30–50, and 50–100 nm, respectively) were obtained by treatment with different concentrations of hydrofluoric acid (HF) and at different etching times (1%, 3 min; 0.5%, 12 min; and 1.5%, 12 min, respectively; denoted as groups HF1, HF2, and HF3). The biological response to the three different titanium surfaces was evaluated by in vitro human bone marrow-derived mesenchymal stem cell (hBMMSC) experiments and in vivo animal experiments. The results showed that cell adhesion, proliferation, alkaline phosphatase activity, and mineralization of hBMMSCs were increased in the HF3 group. After the different surface implants were inserted into the distal femurs of 40 rats, the bone–implant contact in groups HF1, HF2, and HF3 was 33.17%±2.2%, 33.82%±3.42%, and 41.04%±3.08%, respectively. Moreover, the maximal pullout force in groups HF1, HF2, and HF3 was 57.92±2.88, 57.83±4.09, and 67.44±6.14 N, respectively. The results showed that group HF3 with large micron grooves (1.5–2.0 μm) and large nanoparticles (50–100 nm) showed the best bio-functionality for the hBMMSC response and osseointegration in animal experiments compared with other groups. PMID:28243092

  2. Combinatorial localized dissolution analysis: Application to acid-induced dissolution of dental enamel and the effect of surface treatments.

    PubMed

    Parker, Alexander S; Al Botros, Rehab; Kinnear, Sophie L; Snowden, Michael E; McKelvey, Kim; Ashcroft, Alexander T; Carvell, Mel; Joiner, Andrew; Peruffo, Massimo; Philpotts, Carol; Unwin, Patrick R

    2016-08-15

    A combination of scanning electrochemical cell microscopy (SECCM) and atomic force microscopy (AFM) is used to quantitatively study the acid-induced dissolution of dental enamel. A micron-scale liquid meniscus formed at the end of a dual barrelled pipette, which constitutes the SECCM probe, is brought into contact with the enamel surface for a defined period. Dissolution occurs at the interface of the meniscus and the enamel surface, under conditions of well-defined mass transport, creating etch pits that are then analysed via AFM. This technique is applied to bovine dental enamel, and the effect of various treatments of the enamel surface on acid dissolution (1mM HNO3) is studied. The treatments investigated are zinc ions, fluoride ions and the two combined. A finite element method (FEM) simulation of SECCM mass transport and interfacial reactivity, allows the intrinsic rate constant for acid-induced dissolution to be quantitatively determined. The dissolution of enamel, in terms of Ca(2+) flux ( [Formula: see text] ), is first order with respect to the interfacial proton concentration and given by the following rate law: [Formula: see text] , with k0=0.099±0.008cms(-1). Treating the enamel with either fluoride or zinc ions slows the dissolution rate, although in this model system the partly protective barrier only extends around 10-20nm into the enamel surface, so that after a period of a few seconds dissolution of modified surfaces tends towards that of native enamel. A combination of both treatments exhibits the greatest protection to the enamel surface, but the effect is again transient.

  3. Semiconductor etching by hyperthermal neutral beams

    NASA Technical Reports Server (NTRS)

    Minton, Timothy K. (Inventor); Giapis, Konstantinos P. (Inventor)

    1999-01-01

    An at-least dual chamber apparatus and method in which high flux beams of fast moving neutral reactive species are created, collimated and used to etch semiconductor or metal materials from the surface of a workpiece. Beams including halogen atoms are preferably used to achieve anisotropic etching with good selectivity at satisfactory etch rates. Surface damage and undercutting are minimized.

  4. Methods for dry etching semiconductor devices

    DOEpatents

    Bauer, Todd; Gross, Andrew John; Clews, Peggy J.; Olsson, Roy H.

    2016-11-01

    The present invention provides methods for etching semiconductor devices, such aluminum nitride resonators. The methods herein allow for devices having improved etch profiles, such that nearly vertical sidewalls can be obtained. In some examples, the method employs a dry etch step with a primary etchant gas that omits BCl.sub.3, a common additive.

  5. A survey of some metallographic etching reagents for restoration of obliterated engraved marks on aluminium-silicon alloy surfaces.

    PubMed

    Uli, Norjaidi; Kuppuswamy, R; Amran, Mohd Firdaus Che

    2011-05-20

    A brief survey to assess the sensitivity and efficacy of some common etching reagents for revealing obliterated engraved marks on Al-Si alloy surfaces is presented. Experimental observations have recommended use of alternate swabbing of 10% NaOH and 10% HNO(3) on the obliterated surfaces for obtaining the desired results. The NaOH etchant responsible for bringing back the original marks resulted in the deposition of some dark coating that has masked the recovered marks. The coating had been well removed by dissolving it in HNO(3) containing 10-20% acid. However, the above etching procedure was not effective on aluminium (99% purity) and Al-Zn-Mg-Cu alloy surfaces. Also the two reagents (i) immersion in 10% aq. phosphoric acid and (ii) alternate swabbing of 60% HCl and 40% NaOH suggested earlier for high strength Al-Zn-Mg-Cu alloys [23] were quite ineffective on Al-Si alloys. Thus different aluminium alloys needed different etching treatments for successfully restoring the obliterated marks. Al-Si alloys used in casting find wide applications especially in the manufacture of engine blocks of motor vehicles. Hence, the results presented in this paper are of much relevance in serial number restoration problems involving this alloy.

  6. Fatty acid facts, Part I. Essential fatty acids as treatment for depression, or food for mood?

    PubMed

    Pawels, E K J; Volterrani, D

    2008-10-01

    The epidemic character of depressive disorders has prompted further research into dietary habits that could make an etiological contribution. One clear change in the diet of the population in developed countries has been the replacement of omega-3 polyunsaturated fatty acids by saturated fats and trans-fats as well as by omega-6 polyunsaturated fatty acids. Omega-3 and omega-6 fatty acids are essential fatty acids, and the members of the -3 and -6 series are crucial for human health. In biochemical processes there is a competition between these two series. A higher dietary intake of omega-6 results in the excessive incorporation of these molecules in the cell membrane with numerous pathological consequences, presumably due to the formation of proinflammatory eicosanoids. Members of the omega-3 family and their derivatives modulate the inflammatory action. Essential fatty acids play a major role in brain development and brain functioning. The omega-3 series members docosahexaenoic acid (DHA) and eicosapentaenoic acid (EPA) provide fluidity to the cell membrane, facilitating certain processes including neurotransmission and ion channel flow. It is thought that omega-3 deficiency during the fetal and postnatal period may have a long-term effect at various levels. Epidemiological studies have demonstrated a positive association between omega-3 deficits and mood disorders. As for treatment, there is convincing evidence that add-on omega-3 fatty acids to standard antidepressant pharmacotherapy results in improved mood. There is no evidence that fatty acid monotherapy has a mood-elevating effect, with a possible exception for childhood depression. There are indications that omega-3 has a prophylactic effect on perinatal depression and has a negative effect on natural killer cell activity and T-lymphocyte function. These observations need further study in view of the popularity of self-medication.

  7. Cathepsin K in treatment monitoring following intravenous zoledronic acid

    PubMed Central

    JAHN, OLIVER; WEX, THOMAS; KLOSE, SILKE; KROPF, SIEGFRIED; ADOLF, DANIELA; PIATEK, STEFAN

    2014-01-01

    Cathepsin K (CatK) is mainly expressed by osteoclasts and plays an important role in bone resorption. As CatK is expressed and secreted by osteoclasts during active bone resorption, it may be a useful and specific biochemical marker of osteoclastic activity. Therefore, CatK serum levels were studied for monitoring the treatment of females with postmenopausal osteoporosis by zoledronic acid. The serum CatK levels were determined in nine postmenopausal females before and after 3, 6 and 12 months of treatment. The levels were significantly reduced after 3 and 6 months (P<0.05), whereas they returned to baseline after 1 year. Taken together, the serum level of CatK may be suitable for monitoring anti-osteoporotic therapy in association with treatment response. PMID:25279169

  8. Thermal compression chip interconnection using organic solderability preservative etched substrate by plasma processing.

    PubMed

    Cho, Sung-Won; Choi, JoonYoung; Chung, Chin-Wook

    2014-12-01

    The solderability of copper organic solderbility preservative (CuOSP) finished substrate was enhanced by the plasma etching. To improve the solderability of TC interconnection with the CuOSP finished substrate, the plasma etching process is used. An Oxygen-Hydrogen plasma treatment process is performed to remove OSP material. To prevent the oxidation by oxygen plasma treatment, hydrogen reducing process is also performed before TC interconnection process. The thickness of OSP material after plasma etching is measured by optical reflection method and the component analysis by Auger Electron Spectroscopy is performed. From the lowered thickness, the bonding force of TC interconnection after OSP etching process is lowered. Also the electrical open/short test was performed after assembling the completed semiconductor packaging. The improved yield due to the plasma etching process is achieved.

  9. [Hyaluronic Acid (hyalgan(r)) in the treatment of gonarthritis.].

    PubMed

    Pavelka, K; Vlasáková, V; Vítová, J; Stehlíková, H; Slanský, J

    1995-01-01

    The authors made an open multicentre clinical study with the administration of hyaluronic acid (Hyalgan(R) - Fidia) in patients with gonarthritis. The study comprised 31 patients with gonarthritis grade II-III according to Kellgren, 30 of whom completed the study. Hyalgan was administered to the patients - vials á 2 ml in five injections in weekly intervals by the intraarticular route. The patients were followed up for another three months after completed treatment. A significant decline of pain on the visual analogue scale (VAS) was recorded already two weeks after onset of treatment (p = 0.001) and this decline persisted for another 13 weeks after termination of treatment. The algofunctional indices (Lequesne, Jezek) also declined after the first injection, whereby a statistically significant reduction was recorded still after 12 weeks, as compared with values before the onset of treatment (p = 0.001). Similar results were obtained also in objective evaluations (effusion, temperature above joint, tenderness). Already after the second injection a significantly shorter time was required for a 20 m walk. The mean daily paracetamol consumption declined from a mean value of 1496 +/- 777 mg before administration to 670 6 661 mg at the end of the investigation (p = 0.00006). Undesirable effects (increased intensity of pain after puncture) was recorded in one patient (3.3%). Evidence was provided that Hyalgan(R) belongs as to its profile of effectiveness among so-called SYSADOAs (symptomatic slow acting drugs for OA). Treatment is quite safe. Key words: knee osteoarthritis, hyaluronic acid, i. a. treatment.

  10. Improvement of polycrystalline silicon wafer solar cell efficiency by forming nanoscale pyramids on wafer surface using a self-mask etching technique.

    PubMed

    Lin, Hsin-Han; Chen, Wen-Hwa; Hong, Franklin C-N

    2013-05-01

    The creation of nanostructures on polycrystalline silicon wafer surface to reduce the solar reflection can enhance the solar absorption and thus increase the solar-electricity conversion efficiency of solar cells. The self-masking reactive ion etching (RIE) was studied to directly fabricate nanostructures on silicon surface without using a masking process for antireflection purpose. Reactive gases comprising chlorine (Cl2), sulfur hexafluoride (SF6), and oxygen (O2) were activated by radio-frequency plasma in an RIE system at a typical pressure of 120-130 mTorr to fabricate the nanoscale pyramids. Poly-Si wafers were etched directly without masking for 6-10 min to create surface nanostructures by varying the compositions of SF6, Cl2, and O2 gas mixtures in the etching process. The wafers were then treated with acid (KOH:H2O = 1:1) for 1 min to remove the damage layer (100 nm) induced by dry etching. The damage layer significantly reduced the solar cell efficiencies by affecting the electrical properties of the surface layer. The light reflectivity from the surface after acid treatment could be significantly reduced to <10% for the wavelengths between 500 and 900 nm. The effects of RIE and surface treatment conditions on the surface nanostructures and the optical performance as well as the efficiencies of solar cells will be presented and discussed. The authors have successfully fabricated large-area (156 × 156 mm(2)) subwavelength antireflection structure on poly-Si substrates, which could improve the solar cell efficiency reproducibly up to 16.27%, higher than 15.56% using wet etching.

  11. Improvement of polycrystalline silicon wafer solar cell efficiency by forming nanoscale pyramids on wafer surface using a self-mask etching technique

    PubMed Central

    Lin, Hsin-Han; Chen, Wen-Hwa; Hong, Franklin C.-N.

    2013-01-01

    The creation of nanostructures on polycrystalline silicon wafer surface to reduce the solar reflection can enhance the solar absorption and thus increase the solar-electricity conversion efficiency of solar cells. The self-masking reactive ion etching (RIE) was studied to directly fabricate nanostructures on silicon surface without using a masking process for antireflection purpose. Reactive gases comprising chlorine (Cl2), sulfur hexafluoride (SF6), and oxygen (O2) were activated by radio-frequency plasma in an RIE system at a typical pressure of 120–130 mTorr to fabricate the nanoscale pyramids. Poly-Si wafers were etched directly without masking for 6–10 min to create surface nanostructures by varying the compositions of SF6, Cl2, and O2 gas mixtures in the etching process. The wafers were then treated with acid (KOH:H2O = 1:1) for 1 min to remove the damage layer (100 nm) induced by dry etching. The damage layer significantly reduced the solar cell efficiencies by affecting the electrical properties of the surface layer. The light reflectivity from the surface after acid treatment could be significantly reduced to <10% for the wavelengths between 500 and 900 nm. The effects of RIE and surface treatment conditions on the surface nanostructures and the optical performance as well as the efficiencies of solar cells will be presented and discussed. The authors have successfully fabricated large-area (156 × 156 mm2) subwavelength antireflection structure on poly-Si substrates, which could improve the solar cell efficiency reproducibly up to 16.27%, higher than 15.56% using wet etching. PMID:23847751

  12. Post-synthetic Anisotropic Wet-Chemical Etching of Colloidal Sodalite ZIF Crystals

    PubMed Central

    Avci, Civan; Ariñez-Soriano, Javier; Carné-Sánchez, Arnau; Guillerm, Vincent; Carbonell, Carlos; Imaz, Inhar; Maspoch, Daniel

    2016-01-01

    Controlling the shape of metal-organic framework (MOF) crystals is important for understanding their crystallization and useful for myriad applications. However, despite the many advances in shaping of inorganic nanoparticles, post-synthetic shape control of MOFs and, in general, molecular crystals remains embryonic. Herein we report using a simple wet-chemistry process at room temperature to control the anisotropic etching of colloidal ZIF-8 and ZIF-67 crystals. Our work enables uniform reshaping of these porous materials into unprecedented morphologies, including cubic and tetrahedral crystals, and even hollow boxes, via acid-base reaction and subsequent sequestration of leached metal ions. Etching tests on these ZIFs reveal that etching occurs preferentially in the crystallographic directions richer in metal-ligand bonds; that, among these directions, the etching rate tends to be faster on the crystal surfaces of higher dimensionality; and that the etching can be modulated by adjusting the pH of the etchant solution. PMID:26458081

  13. Note: Dissolved hydrogen detection in power transformer oil based on chemically etched fiber Bragg grating.

    PubMed

    Jiang, Jun; Ma, Guo-ming; Song, Hong-tu; Zhou, Hong-yang; Li, Cheng-rong; Luo, Ying-ting; Wang, Hong-bin

    2015-10-01

    A fiber Bragg grating (FBG) sensor based on chemically etched cladding to detect dissolved hydrogen is proposed and studied in this paper. Low hydrogen concentration tests have been carried out in mixed gases and transformer oil to investigate the repeatability and sensitivity. Moreover, to estimate the influence of etched cladding thickness, a physical model of FBG-based hydrogen sensor is analyzed. Experimental results prove that thin cladding chemically etched by HF acid solution improves the response to hydrogen detection in oil effectively. At last, the sensitivity of FBG sensor chemically etched 16 μm could be as high as 0.060 pm/(μl/l), increased by more than 30% in comparison to un-etched FBG.

  14. Post-Synthetic Anisotropic Wet-Chemical Etching of Colloidal Sodalite ZIF Crystals.

    PubMed

    Avci, Civan; Ariñez-Soriano, Javier; Carné-Sánchez, Arnau; Guillerm, Vincent; Carbonell, Carlos; Imaz, Inhar; Maspoch, Daniel

    2015-11-23

    Controlling the shape of metal-organic framework (MOF) crystals is important for understanding their crystallization and useful for myriad applications. However, despite the many advances in shaping of inorganic nanoparticles, post-synthetic shape control of MOFs and, in general, molecular crystals remains embryonic. Herein, we report using a simple wet-chemistry process at room temperature to control the anisotropic etching of colloidal ZIF-8 and ZIF-67 crystals. Our work enables uniform reshaping of these porous materials into unprecedented morphologies, including cubic and tetrahedral crystals, and even hollow boxes, by an acid-base reaction and subsequent sequestration of leached metal ions. Etching tests on these ZIFs reveal that etching occurs preferentially in the crystallographic directions richer in metal-ligand bonds; that, along these directions, the etching rate tends to be faster on the crystal surfaces of higher dimensionality; and that the etching can be modulated by adjusting the pH of the etchant solution.

  15. Ion-beam-assisted etching of diamond

    NASA Technical Reports Server (NTRS)

    Efremow, N. N.; Geis, M. W.; Flanders, D. C.; Lincoln, G. A.; Economou, N. P.

    1985-01-01

    The high thermal conductivity, low RF loss, and inertness of diamond make it useful in traveling wave tubes operating in excess of 500 GHz. Such use requires the controlled etching of type IIA diamond to produce grating like structures tens of micrometers deep. Previous work on reactive ion etching with O2 gave etching rates on the order of 20 nm/min and poor etch selectivity between the masking material (Ni or Cr) and the diamond. An alternative approach which uses a Xe(+) beam and a reactive gas flux of NO2 in an ion-beam-assisted etching system is reported. An etching rate of 200 nm/min was obtained with an etching rate ratio of 20 between the diamond and an aluminum mask.

  16. Selective Si Etching Using HCl Vapor

    NASA Astrophysics Data System (ADS)

    Isheden, C.; Hellström, P. E.; Radamson, H. H.; Zhang, S.-L.; Östling, M.

    2004-01-01

    Selective Si etching using HCl in a reduced pressure chemical vapor deposition reactor in the temperature range 800 1000°C is investigated. At 900°C, the etch process is anisotropic, exhibiting the densely packed (100), (311) and (111) surfaces. This behavior indicates that the etch process is limited by surface reaction, since the etch rate in the directions with higher atomic concentration is lower. When the temperature is decreased to 800°C, etch pits occur. A more isotropic etch is obtained at 1000°C, however at this temperature the masking oxide is attacked and the etch surface is rough. Thus the temperature has to be under the present process conditions, confined to a narrow window to yield desirable properties.

  17. The effect of additional etching and curing mechanism of composite resin on the dentin bond strength

    PubMed Central

    Lee, In-Su; Son, Sung-Ae; Hur, Bock; Kwon, Yong-Hoon

    2013-01-01

    PURPOSE The aim of this study was to evaluate the effects of additional acid etching and curing mechanism (light-curing or self-curing) of a composite resin on the dentin bond strength and compatibility of one-step self-etching adhesives. MATERIALS AND METHODS Sixteen human permanent molars were randomly divided into eight groups according to the adhesives used (All-Bond Universal: ABU, Clearfil S3 Bond: CS3), additional acid etching (additional acid etching performed: EO, no additional acid etching performed: EX), and composite resins (Filtek Z-250: Z250, Clearfil FII New Bond: CFNB). Group 1: ABU-EO-Z250, Group 2: ABU-EO-CFNB, Group 3: ABU-EX-Z250, Group 4: ABU-EX-CFNB, Group 5: CS3-EO-Z250, Group 6: CS3-EO-CFNB, Group 7: CS3-EX-Z250, Group 8: CS3-EX-CFNB. After bonding procedures, composite resins were built up on dentin surfaces. After 24-hour water storage, the teeth were sectioned to make 10 specimens for each group. The microtensile bond strength test was performed using a microtensile testing machine. The failure mode of the fractured specimens was examined by means of an optical microscope at ×20 magnification. The data was analyzed using a one-way ANOVA and Scheffe's post-hoc test (α=.05). RESULTS Additional etching groups showed significantly higher values than the no additional etching group when using All-Bond Universal. The light-cured composite resin groups showed significantly higher values than the self-cured composite resin groups in the Clearfil S3 Bond. CONCLUSION The additional acid etching is beneficial for the dentin bond strength when using low acidic one-step self-etch adhesives, and low acidic one-step self-etch adhesives are compatible with self-cured composite resin. The acidity of the one-step self-etch adhesives is an influencing factor in terms of the dentin bonding strength and incompatibility with a self-cured composite resin. PMID:24353889

  18. Emerging Technology Summary. ACID EXTRACTION TREATMENT SYSTEM FOR TREATMENT OF METAL CONTAMINATED SOILS

    EPA Science Inventory

    The Acid Extraction Treatment System (AETS) is intended to reduce the concentrations and/or teachability of heavy metals in contaminated soils so the soil can be returned to the site from which it originated. The objective of the project was to determine the effectiveness and com...

  19. Comparison between phosphoric acid and hydrochloric acid in microabrasion technique for the treatment of dental fluorosis

    PubMed Central

    Bassir, Mahshid Mohammadi; Bagheri, Golnaz

    2013-01-01

    Purpose: To compare the effectiveness of phosphoric acid (H3PO4)-pumice compound with conventional hydrochloric acid (HCl)-pumice compound in treating different severities of dental fluorosis with the microabrasion technique. Materials and Methods: Sixty-seven anterior teeth from seven patients with different severities of dental fluorosis were treated. In each patient, half of the teeth were treated with HCl-pumice compound and the other half with H3PO4-pumice compound (split-mouth design). Both treatment compounds were applied for 30-second periods and treatment continued up to 10 minutes. Before and after treatment, standardized photographs were taken. The photographs were compared by two experienced observers unaware of the modality of treatment. Two indices of aesthetics, improvement in appearance (IA) and degree of stain removal (DSR), were determined according to a visual analog scale. The inter- and intra-correlation coefficients were made; then, statistical analyses were calculated using Mann-Whitney and t-test. Results: There were no significant differences in interobserver evaluation. Improvements in aesthetic indices were observed in all fluorotic teeth by both compounds; however, the mean treatment time with HCl-pumice was significantly lower than H3PO4-pumice. Conclusion: The H3PO4-pumice compound improved aesthetic indices in fluorotic teeth similar to the HCl-pumice compound. PMID:23349575

  20. Nitric-phosphoric acid treatment of TRU wastes

    SciTech Connect

    Smith, J.R.; Pierce, R.A.; Sturcken, E.F.

    1993-09-30

    A general process is being developed for the treatment of solid TRU and hazardous organic waste. Experimental data indicates that 100 lb/hr of aliphatic organic (plastics) and 1,000 lb/hr of non-aliphatic organic compounds can be quantitatively oxidized in a 1,000 gallon reaction vessel. The process uses dilute nitric acid in a concentrated phosphoric acid media as the main oxidant for the organic compounds. Phosphoric acid allows oxidation at temperatures up to 200{degrees}C and is relatively non-corrosive on 304-L stainless steel, especially at room temperature. Many organic materials have been completely oxidized to CO{sub 2}, CO, and inorganic acids in a 0.1M HNO{sub 3}/14.8M H{sub 3}PO{sub 4} solution. Addition of 0.001M Pd{sup 2+} reduces the CO to near 1% of the released carbon gases. To accomplish complete oxidation the solution temperature must be maintained above 130--150{degrees}C. Organic materials quantitatively destroyed include neoprene, cellulose, EDTA, TBP, tartaric acid, and nitromethane. The oxidation is usually complete in a few hours for soluble organic materials. The oxidation rate for non-aliphatic organic solids is moderately fast and surface area dependent. Polyethylene is quantitatively oxidized in 1.0M HNO{sub 3}/13.8M H{sub 3}PO{sub 4} solution while contained in pressure vessels heated with microwave energy. This is probably due to the high concentrations of NO{sub 2}{center_dot} obtained in the reaction environment.

  1. [PREPARATIONS OF PAMIDRONOVIC ACID IN COMPLEX TREATMENT ON OSTEOGENESIS IMPERFECTA].

    PubMed

    Zyma, A M; Guk, Yu M; Magomedov, O M; Gayko, O G; Kincha-Polishchuk, T A

    2015-07-01

    Modern view of drug therapy in the complex treatment of orthopedic manifestations of osteogenesis imperfecta (OI) was submitted. Developed and tested system of drug correction of structural and functional state of bone tissue (BT) using drugs pamidronovic acid, depending on osteoporosis severity and type of disease. Such therapy is appropriate to apply both independently and in conjunction with surgery to correct deformations of long bones of the lower extremities. Effectiveness and feasibility of the proposed methods of drug therapy was proved, most patients resume features walking and support.

  2. Treatment of vinasse from tequila production using polyglutamic acid.

    PubMed

    Carvajal-Zarrabal, Octavio; Nolasco-Hipólito, Cirilo; Barradas-Dermitz, Dulce Ma; Hayward-Jones, Patricia M; Aguilar-Uscanga, Ma Guadalupe; Bujang, Kopli

    2012-03-01

    Vinasse, the wastewater from ethanol distillation, is characterised by high levels of organic and inorganic matter, high exit process temperature (ca. 90°C) and low pH (3.0-4.5). In this study, the treatment of tequila vinasse was achieved by a flocculation-coagulation process using poly-γ-glutamic acid (PGA). Results showed that the use of PGA (250-300 ppm) combined with sodium hypochlorite and sand filtration managed to remove about 70% of the turbidity and reduced chemical oxygen demand (COD) by 79.5% with the extra benefit of colour removal. PGA showed its best flocculating activity at pH 2.5-3.5 and a temperature of 30-55°C. Such a treatment may be a solution for small tequila companies for which other solutions to deal with their vinasse may not be economically affordable.

  3. Bond strength of resin-reinforced glass ionomer cements after enamel etching.

    PubMed

    Cortes, O; Garcia-Godoy, F; Boj, J R

    1993-12-01

    This study evaluated the shear bond strength of resin-reinforced glass ionomers to enamel etched or unetched. Human, non-carious extracted permanent molars stored in distilled water were used. Flat buccal and lingual enamel surfaces were ground wet on 600-grit silicon carbide paper. The teeth were then distributed at random into six groups of 5 teeth (10 surfaces) each: Group 1: Fuji II LC, no enamel etching; Group 2: Fuji II LC, enamel etched with 10% phosphoric acid for 10 seconds; Group 3: Dyract, no enamel etching; Group 4: Dyract, enamel etched with 10% phosphoric acid for 10 seconds; Group 5: Photac-Fil, no enamel etching; Group 6: Photac-Fil, enamel etched with 10% phosphoric acid for 10 seconds. Cylindrical samples of the glass ionomers were prepared in plastic molds and bonded to the enamel surface according to the manufacturers' instructions. All samples were placed in distilled water for 24 hours, and sheared with an Instron at a crosshead speed of 0.5 mm/minute. The results (in MPa) were: Group 1: 11.29 +/- 4.84; Group 2: 19.64 +/- 5.43; Group 3: 8.26 +/- 3.61; Group 4: 22.04 +/- 5.40; Group 5: 2.05 +/- 3.05; Group 6: 9.12 +/- 6.61. ANOVA and Student-Newman-Keuls procedure revealed that on etched enamel, Fuji II LC and Dyract had a significantly higher bond strength than all the other groups tested (P < 0.0001), but not significantly different between each other. With these two groups, cohesive failure within the material was recorded in all samples while in the unetched samples, all specimens displayed an adhesive failure (glass ionomer-enamel interface). All samples with Photac-Fil, with or without enamel etching had adhesive failures.

  4. In-Plasma Photo-Assisted Etching

    NASA Astrophysics Data System (ADS)

    Economou, Demetre

    2015-09-01

    A methodology to precisely control the ion energy distribution (IED) on a substrate allowed the study of silicon etching as a function of ion energy at near-threshold energies. Surprisingly, a substantial etching rate was observed, independent of ion energy, when the ion energy was below the ion-assisted etching threshold (~ 16 eV for etching silicon with chlorine plasma). Careful experiments led to the conclusion that this ``sub-threshold'' etching was due to photons, predominately at wavelengths <1700 Å. Among the plasmas investigated, photo-assisted etching (PAE) was lowest in Br2/Ar gas mixtures and highest in HBr/Cl2/Ar. Above threshold etching rates scaled with the square root of ion energy. PAE rates scaled with the product of surface halogen coverage (measured by X-ray photoelectron spectroscopy) and Ar emission intensity (7504 Å). Scanning electron and atomic force microscopy (SEM and AFM) revealed that photo-etched surfaces were very rough, quite likely due to the inability of the photo-assisted process to remove contaminants from the surface. In-plasma PAE may be be a complicating factor for processes that require low ion energies, such as atomic layer etching. On the other hand PAE could produce sub-10 nm high aspect ratio (6:1) features by highly selective plasma etching to transfer nascent nanopatterns in silicon. Work supported by DOE Plasma Science Center and NSF.

  5. The effect of various treatment conditions on natural zeolites: ion exchange, acidic, thermal and steam treatments.

    PubMed

    Ates, Ayten; Hardacre, Christopher

    2012-04-15

    Two different natural zeolites having different phase compositions were obtained from different regions of Turkey and modified by ion-exchange (0.5M NH(4)NO(3)) and acid leaching using 1M HCl. The natural and modified samples were treated at low temperature (LT), high temperature (HT) and steam (ST) conditions and characterised by XRF, XRD, BET, FTIR, DR-UV-Vis, NH(3)-TPD and TGA. Ion-exchange with NH(4)(+) of natural zeolites results in the exchange of the Na(+) and Ca(2+) cations and the partial exchange of the Fe(3+) and Mg(2+) cations. However, steam and acidic treatments cause significant dealumination and decationisation, as well as loss of crystalline, sintering of phases and the formation of amorphous material. The presence of mordenite and quartz phases in the natural zeolites increases the stability towards acid treatment, whereas the structure of clinoptilolite-rich zeolites is mostly maintained after high temperature and steam treatments. The natural and modified zeolites treated at high temperature and in steam were found to be less stable compared with synthetic zeolites, resulting in a loss of crystallinity, a decrease in the surface area and pore volume, a decrease in the surface acidity as well as dealumination, and decationisation.

  6. Selective protection of poly(tetra-fluoroethylene) from effects of chemical etching

    DOEpatents

    Martinez, Robert J.; Rye, Robert R.

    1991-01-01

    A photolithographic method for treating an article formed of polymeric material comprises subjecting portions of a surface of the polymeric article to ionizing radiation; and then subjecting the surface to chemical etching. The ionizing radiation treatment according to the present invention minimizes the effect of the subseuent chemical etching treatment. Thus, selective protection from the effects of chemical etching can be easily provided. The present invention has particular applicability to articles formed of fluorocarbons, such as PTFE. The ionizing radiation employed in the method may comprise Mg(k.alpha.) X-rays or lower-energy electrons.

  7. Gambogic acid-loaded biomimetic nanoparticles in colorectal cancer treatment

    PubMed Central

    Zhang, Zhen; Qian, Hanqing; Yang, Mi; Li, Rutian; Hu, Jing; Li, Li; Yu, Lixia; Liu, Baorui; Qian, Xiaoping

    2017-01-01

    Gambogic acid (GA) is expected to be a potential new antitumor drug, but its poor aqueous solubility and inevitable side effects limit its clinical application. Despite these inhe rent defects, various nanocarriers can be used to promote the solubility and tumor targeting of GA, improving antitumor efficiency. In addition, a cell membrane-coated nanoparticle platform that was reported recently, unites the customizability and flexibility of a synthetic copolymer, as well as the functionality and complexity of natural membrane, and is a new synthetic biomimetic nanocarrier with improved stability and biocompatibility. Here, we combined poly(lactic-co-glycolic acid) (PLGA) with red blood-cell membrane (RBCm), and evaluated whether GA-loaded RBCm nanoparticles can retain and improve the antitumor efficacy of GA with relatively lower toxicity in colorectal cancer treatment compared with free GA. We also confirmed the stability, biocompatibility, passive targeting, and few side effects of RBCm-GA/PLGA nanoparticles. We expect to provide a new drug carrier in the treatment of colorectal cancer, which has strong clinical application prospects. In addition, the potential antitumor drug GA and other similar drugs could achieve broader clinical applications via this biomimetic nanocarrier. PMID:28280328

  8. Retinoic acid and glycolic acid combination in the treatment of acne scars

    PubMed Central

    Chandrashekar, BS; Ashwini, KR; Vasanth, Vani; Navale, Shreya

    2015-01-01

    Introduction: Acne is a prevalent condition in society affecting nearly 80-90% of adolescents often resulting in secondary damage in the form of scarring. Retinoic acid (RA) is said to improve acne scars and reduce postinflammatory hyperpigmentation while glycolic acid (GA) is known for its keratolytic properties and its ability to reduce atrophic acne scars. There are studies exploring the combined effect of retinaldehyde and GA combination with positive results while the efficacy of retinoic acid and GA (RAGA) combination remains unexplored. Aim: The aim of this study remains to retrospectively assess the efficacy of RAGA combination on acne scars in patients previously treated for active acne. Materials and Methods: A retrospective assessment of 35 patients using topical RAGA combination on acne scars was done. The subjects were 17-34 years old and previously treated for active acne. Case records and photographs of each patient were assessed and the acne scars were graded as per Goodman and Baron's global scarring grading system (GSGS), before the start and after 12 weeks of RAGA treatment. The differences in the scar grades were noted to assess the improvement. Results: At the end of 12 weeks, significant improvement in acne scars was noticed in 91.4% of the patients. Conclusion: The RAGA combination shows efficacy in treating acne scars in the majority of patients, minimizing the need of procedural treatment for acne scars. PMID:25821727

  9. Surface modification via wet chemical etching of single-crystalline silicon for photovoltaic application.

    PubMed

    Reshak, A H; Shahimin, M M; Shaari, S; Johan, N

    2013-11-01

    The potential of solar cells have not been fully tapped due to the lack of energy conversion efficiency. There are three important mechanisms in producing high efficiency cells to harvest solar energy; reduction of light reflectance, enhancement of light trapping in the cell and increment of light absorption. The current work represent studies conducted in surface modification of single-crystalline silicon solar cells using wet chemical etching techniques. Two etching types are applied; alkaline etching (KOH:IPA:DI) and acidic etching (HF:HNO3:DI). The alkaline solution resulted in anisotropic profile that leads to the formation of inverted pyramids. While acidic solution formed circular craters along the front surface of silicon wafer. This surface modification will leads to the reduction of light reflectance via texturizing the surface and thereby increases the short circuit current and conversion rate of the solar cells.

  10. Method for etching thin films of niobium and niobium-containing compounds for preparing superconductive circuits

    DOEpatents

    Kampwirth, Robert T.; Schuller, Ivan K.; Falco, Charles M.

    1981-01-01

    An improved method of preparing thin film superconducting electrical circuits of niobium or niobium compounds in which a thin film of the niobium or niobium compound is applied to a nonconductive substrate, and covered with a layer of photosensitive material. The sensitive material is in turn covered with a circuit pattern exposed and developed to form a mask of the circuit in photoresistive material on the surface of the film. The unmasked excess niobium film is removed by contacting the substrate with an aqueous etching solution of nitric acid, sulfuric acid and hydrogen fluoride, which will rapidly etch the niobium compound without undercutting the photoresist. A modification of the etching solution will permit thin films to be lifted from the substrate without further etching.

  11. Method for etching thin films of niboium and niobium-containing compounds for preparing superconductive circuits

    DOEpatents

    Kampwirth, R.T.; Schuller, I.K.; Falco, C.M.

    1979-11-23

    An improved method of preparing thin film superconducting electrical circuits of niobium or niobium compounds is provided in which a thin film of the niobium or niobium compound is applied to a nonconductive substrate and covered with a layer of photosensitive material. The sensitive material is in turn covered with a circuit pattern exposed and developed to form a mask of the circuit in photoresistive material on the surface of the film. The unmasked excess niobium film is removed by contacting the substrate with an aqueous etching solution of nitric acid, sulfuric acid, and hydrogen fluoride, which will rapidly etch the niobium compound without undercutting the photoresist. A modification of the etching solution will permit thin films to be lifted from the substrate without further etching.

  12. Etching of glass microchips with supercritical water.

    PubMed

    Karásek, Pavel; Grym, Jakub; Roth, Michal; Planeta, Josef; Foret, František

    2015-01-07

    A novel method of etching channels in glass microchips with the most tunable solvent, water, was tested as an alternative to common hydrogen fluoride-containing etchants. The etching properties of water strongly depend on temperature and pressure, especially in the vicinity of the water critical point. The chips were etched at the subcritical, supercritical and critical temperature of water, and the resulting channel shape, width, depth and surface morphology were studied by scanning electron microscopy and 3D laser profilometry. Channels etched with the hot water were compared with the chips etched with standard hydrogen fluoride-containing solution. Depending on the water pressure and temperature, the silicate dissolved from the glass could be re-deposited on the channel surface. This interesting phenomenon is described together with the conditions necessary for its utilization. The results illustrate the versatility of pure water as a glass etching and surface morphing agent.

  13. Etching method for photoresists or polymers

    NASA Technical Reports Server (NTRS)

    Lerner, Narcinda R. (Inventor); Wydeven, Theodore J., Jr. (Inventor)

    1991-01-01

    A method for etching or removing polymers, photoresists, and organic contaminants from a substrate is disclosed. The method includes creating a more reactive gas species by producing a plasma discharge in a reactive gas such as oxygen and contacting the resulting gas species with a sacrificial solid organic material such as polyethylene or polyvinyl fluoride, reproducing a highly reactive gas species, which in turn etches the starting polymer, organic contaminant, or photoresist. The sample to be etched is located away from the plasma glow discharge region so as to avoid damaging the substrate by exposure to high energy particles and electric fields encountered in that region. Greatly increased etching rates are obtained. This method is highly effective for etching polymers such as polyimides and photoresists that are otherwise difficult or slow to etch downstream from an electric discharge in a reactive gas.

  14. Laser-driven fusion etching process

    DOEpatents

    Ashby, Carol I. H.; Brannon, Paul J.; Gerardo, James B.

    1989-01-01

    The surfaces of solid ionic substrates are etched by a radiation-driven chemical reaction. The process involves exposing an ionic substrate coated with a layer of a reactant material on its surface to radiation, e.g. a laser, to induce localized melting of the substrate which results in the occurrance of a fusion reaction between the substrate and coating material. The resultant reaction product and excess reactant salt are then removed from the surface of the substrate with a solvent which is relatively inert towards the substrate. The laser-driven chemical etching process is especially suitable for etching ionic salt substrates, e.g., a solid inorganic salt such as LiNbO.sub.3, such as used in electro-optical/acousto-optic devices. It is also suitable for applications wherein the etching process is required to produce an etched ionic substrate having a smooth surface morphology or when a very rapid etching rate is desired.

  15. Laser-driven fusion etching process

    DOEpatents

    Ashby, C.I.H.; Brannon, P.J.; Gerardo, J.B.

    1987-08-25

    The surfaces of solids are etched by a radiation-driven chemical reaction. The process involves exposing a substrate coated with a layer of a reactant material on its surface to radiation, e.g., a laser, to induce localized melting of the substrate which results in the occurrence of a fusion reaction between the substrate and coating material. The resultant reaction product and excess reactant salt are then removed from the surface of the substrate with a solvent which is relatively inert towards the substrate. The laser-driven chemical etching process is especially suitable for etching ionic substrates, e.g., LiNbO/sub 3/, such as used in electro-optical/acousto-optic devices. It is also suitable for applications wherein the etching process is required to produce an etched ionic substrate having a smooth surface morphology or when a very rapid etching rate is desired.

  16. Enhanced volatile fatty acid production from excess sludge by combined free nitrous acid and rhamnolipid treatment.

    PubMed

    Wu, Qing-Lian; Guo, Wan-Qian; Bao, Xian; Zheng, He-Shan; Yin, Ren-Li; Feng, Xiao-Chi; Luo, Hai-Chao; Ren, Nan-Qi

    2017-01-01

    VFA production from excess sludge (ES) was greatly enhanced by a low-cost and high-efficient treatment: 0.67mg/L free nitrous acid (FNA) pretreatment combined with 0.04g/g TSS rhamnolipid (RL) addition (FNA+RL), which significantly shortened fermentation time to 3days and increased VFA production to 352.26mgCOD/g VSS (5.42 times higher than raw ES). Propionic and acetic acids were the two leading components (71.86% of the total VFA). Mechanism investigation manifested FNA+RL improved the biodegradability of ES, achieved positive synergetic effect on solubilization, hydrolysis and acidification efficiencies, and inhibited methanation. Microbial community distribution further explained the above phenomena. The bacteria related to polysaccharides/protein utilization and VFA generation, including Clostridium, Megasphaera and Proteiniborus, were mainly observed in FNA+RL, whereas gas-forming bacteria Anaerolineae and acid-consuming bacteria Proteobacteria were assuredly suppressed. Besides, Propionibacterineae associated with propionic acid generation was exclusively enriched in sole RL and FNA+RL.

  17. Omega 3 polyunsaturated fatty acids and the treatment of depression.

    PubMed

    Deacon, Gelinda; Kettle, Christine; Hayes, David; Dennis, Christina; Tucci, Joseph

    2017-01-02

    Depression is a common, recurrent, and debilitating illness that has become more prevalent over the past 100 years. This report reviews the etiology and pathophysiology of depression, and explores the role of omega 3 polyunsaturated fatty acids (n-3 PUFA) as a possible treatment. In seeking to understand depression, genetic factors and environmental influences have been extensively investigated. Research has led to several hypotheses for the pathophysiological basis of depression but a definitive pathogenic mechanism, or group thereof, has hitherto remained equivocal. To date, treatment has been based on the monoamine hypothesis and hence, selective serotonin reuptake inhibitors have been the most widely used class of medication. In the last decade, there has been considerable interest in n-3 PUFAs and their role in depression. These fatty acids are critical for development and function of the central nervous system. Increasing evidence from epidemiological, laboratory, and randomized placebo-controlled trials suggests deficiency of dietary n-3 PUFAs may contribute to development of mood disorders, and supplementation with n-3 PUFAs may provide a new treatment option. Conclusions based on systematic reviews and meta-analyses of published trials to date vary. Research into the effects of n-3 PUFAs on depressed mood is limited. Furthermore, results from such have led to conflicting conclusions regarding the efficacy of n-3 PUFAs in affecting reduction in symptoms of depression. PUFAs are generally well tolerated by adults and children although mild gastrointestinal effects are reported. There is mounting evidence to suggest that n-3 PUFAs play a role in depression and deserve greater research efforts.

  18. Etching radical controlled gas chopped deep reactive ion etching

    DOEpatents

    Olynick, Deidre; Rangelow, Ivo; Chao, Weilun

    2013-10-01

    A method for silicon micromachining techniques based on high aspect ratio reactive ion etching with gas chopping has been developed capable of producing essentially scallop-free, smooth, sidewall surfaces. The method uses precisely controlled, alternated (or chopped) gas flow of the etching and deposition gas precursors to produce a controllable sidewall passivation capable of high anisotropy. The dynamic control of sidewall passivation is achieved by carefully controlling fluorine radical presence with moderator gasses, such as CH.sub.4 and controlling the passivation rate and stoichiometry using a CF.sub.2 source. In this manner, sidewall polymer deposition thicknesses are very well controlled, reducing sidewall ripples to very small levels. By combining inductively coupled plasmas with controlled fluorocarbon chemistry, good control of vertical structures with very low sidewall roughness may be produced. Results show silicon features with an aspect ratio of 20:1 for 10 nm features with applicability to nano-applications in the sub-50 nm regime. By comparison, previous traditional gas chopping techniques have produced rippled or scalloped sidewalls in a range of 50 to 100 nm roughness.

  19. Shear bond strength and microleakage of a self-etching adhesive for fissure sealing after different types of aging.

    PubMed

    Schuldt, Christoph; Birlbauer, Sebastian; Pitchika, Vinay; Crispin, Alexander; Hickel, Reinhard; Kühnisch, Jan

    2016-01-01

    The aim of this study was to evaluate shear bond strength (SBS) and microleakage of a self-etching adhesive (Adper Prompt L-Pop) in comparison to acid etching prior fissure sealing. Each procedure was tested with 3 aging procedures (1-day water storage, 3-month water storage and 1-day water storage/5,000× thermocycling). SBS was determined according to ISO standard 29022. Additional 30 third molars were utilized for the microleakage analyses. Data were analyzed using Mann-Whitney-U-Test and multiple linear regression models. The SBS of the self-etching adhesive were significantly lower (14.9, 11.9, and 13.0 MPa) than those of conventional fissure sealing (19.1, 18.2, and 15.6 MPa). Multiple linear regression models predicted that material and alteration significantly influenced SBS. The microleakage revealed no difference between both groups (1.3% vs. 1.2%). It can be concluded that the selfetching adhesive might be a pre-treatment alternative for fissure sealing in terms of the easier and shorter clinical workflow.

  20. Controlled ion implant damage profile for etching

    DOEpatents

    Arnold, Jr., George W.; Ashby, Carol I. H.; Brannon, Paul J.

    1990-01-01

    A process for etching a material such as LiNbO.sub.3 by implanting ions having a plurality of different kinetic energies in an area to be etched, and then contacting the ion implanted area with an etchant. The various energies of the ions are selected to produce implant damage substantially uniformly throughout the entire depth of the zone to be etched, thus tailoring the vertical profile of the damaged zone.

  1. Selective etching of silicon carbide films

    DOEpatents

    Gao, Di; Howe, Roger T.; Maboudian, Roya

    2006-12-19

    A method of etching silicon carbide using a nonmetallic mask layer. The method includes providing a silicon carbide substrate; forming a non-metallic mask layer by applying a layer of material on the substrate; patterning the mask layer to expose underlying areas of the substrate; and etching the underlying areas of the substrate with a plasma at a first rate, while etching the mask layer at a rate lower than the first rate.

  2. Evaluation of shear bond strength of orthodontic brackets bonded with Er-YAG laser etching

    PubMed Central

    Raji, S. Hamid; Birang, Reza; Majdzade, Fateme; Ghorbanipour, Reza

    2012-01-01

    Background: Based on contradictory findings concerning the use of lasers for enamel etching, the purpose of this study was to investigate the shear bond strength of teeth prepared for bonding with Er-YAG laser etching and compare them with phosphoric acid etching. Materials and Methods: In this in vitro study forty – eight premolars, extracted for orthodontic purposes were randomly divided in to three groups. Thirty-two teeth were exposed to laser energy for 25 s: 16 teeth at 100 mj setting and 16 teeth at 150 mj setting. Sixteen teeth were etched with 37% phosphoric acid. The shear bond strength of bonded brackets with the Transbond XT adhesive system was measured with the Zwick testing machine. Descriptive statistics, Kolmogorov–Smirnov test, of homogeneity of variances, one- way analysis of variances and Tukey's test and Kruskal Wallis were used to analyze the data. Results: The mean shear bond strength of the teeth lased with 150 mj was 12.26 ± 4.76 MPa, which was not significantly different from the group with acid etching (15.26 ± 4.16 MPa). Irradiation with 100 mj resulted in mean bond strengths of 9.05 ± 3.16 MPa, which was significantly different from that of acid etching (P < 0.001). Conclusions: laser etching at 150 and 100 mj was adequate for bond strength but the failure pattern of brackets bonded with laser etching is dominantly at adhesive – enamel interface and is not safe for enamel during debonding. PMID:23087733

  3. Bioelectrochemical treatment of acid mine drainage dominated with iron.

    PubMed

    Lefebvre, Olivier; Neculita, Carmen M; Yue, Xiaodi; Ng, How Yong

    2012-11-30

    Treatment of acid mine drainage (AMD) dominated with iron (Fe), the most common metal, is a long-term expensive commitment, the goal of which is to increase the pH and remove Fe. In the present study, a proton exchange membrane microbial fuel cell (MFC) showed promise for the efficient treatment of an AMD dominated with ferric iron (pH 2.4±0.1; 500 mg L(-1) Fe(3+)). Briefly, Fe(3+) was reduced to Fe(2+) at the cathode of the MFC, followed by Fe(2+) re-oxidation and precipitation as oxy(hydroxi)des. Oxygen reduction and cation transfer to the cathode of the MFC further caused a rise in pH. A linear relationship was observed between the charge transferred in the MFC and the performance of the system up to 880 C. Optimal conditions were found at a charge of 662 C, achieved within 7 d at an acetate concentration of 1.6 g L(-1) in a membrane MFC. This caused the pH to rise to 7.9 and resulted in a Fe removal of 99%. Treated effluent met the pH discharge limits of 6.5-9. The maximum power generation achieved under these conditions averaged 8.6±2.3 W m(-3), which could help reduce the costs of full-scale bioelectrochemical treatment of AMD dominated with Fe.

  4. Topical tranexamic acid as a promising treatment for melasma

    PubMed Central

    Ebrahimi, Bahareh; Naeini, Farahnaz Fatemi

    2014-01-01

    Background: In recent times, tranexamic acid (TA) is claimed to have whitening effects especially for ultraviolet-induced hyperpigmentation including melasma. The aim of our study was to evaluate the efficacy and safety of topical solution of TA and compare it with combined solution of hydroquinone and dexamethasone as the gold standard treatment of melasma in Iranian women. Materials and Methods: This was a double-blind split-face trial of 12 weeks which was conducted in Isfahan, Iran. Fifty Iranian melasma patients applied topical solution of 3% TA on one side of the face, and topical solution of 3% hydroquinone + 0.01% dexamethasone on the other side two times a day. The Melasma Area and Severity Index (MASI) and the side effects were evaluated at baseline and every 4 weeks before and after photographs to be compared by a dermatologist were taken. The patient satisfaction was documented at week 12. Results: A repeated measurement analysis was used to evaluate the changes in the MASI score before and after treatments. A significant decreasing trend was observed in the MASI score of both groups with no significant difference between them during the study (P < 0.05). No differences were seen in patients’ and investigator's satisfaction of melasma improvement between two groups (P < 0.05). However, the side effects of hydroquinone + dexamethasone were significantly prominent compared with TA (P = 0.01). Conclusion: This study's results introduce the topical TA as an effective and safe medication for the treatment of melasma. PMID:25422661

  5. Method for dry etching of transition metals

    DOEpatents

    Ashby, C.I.H.; Baca, A.G.; Esherick, P.; Parmeter, J.E.; Rieger, D.J.; Shul, R.J.

    1998-09-29

    A method for dry etching of transition metals is disclosed. The method for dry etching of a transition metal (or a transition metal alloy such as a silicide) on a substrate comprises providing at least one nitrogen- or phosphorus-containing {pi}-acceptor ligand in proximity to the transition metal, and etching the transition metal to form a volatile transition metal/{pi}-acceptor ligand complex. The dry etching may be performed in a plasma etching system such as a reactive ion etching (RIE) system, a downstream plasma etching system (i.e. a plasma afterglow), a chemically-assisted ion beam etching (CAIBE) system or the like. The dry etching may also be performed by generating the {pi}-acceptor ligands directly from a ligand source gas (e.g. nitrosyl ligands generated from nitric oxide), or from contact with energized particles such as photons, electrons, ions, atoms, or molecules. In some preferred embodiments of the present invention, an intermediary reactant species such as carbonyl or a halide ligand is used for an initial chemical reaction with the transition metal, with the intermediary reactant species being replaced at least in part by the {pi}-acceptor ligand for forming the volatile transition metal/{pi}-acceptor ligand complex.

  6. Advanced plasma etch technologies for nanopatterning

    NASA Astrophysics Data System (ADS)

    Wise, Rich

    2012-03-01

    Advances in patterning techniques have enabled the extension of immersion lithography from 65/45nm through 14/10nm device technologies. A key to this increase in patterning capability has been innovation in the subsequent dry plasma etch processing steps. Multiple exposure techniques such as litho-etch-litho-etch, sidewall image transfer, line/cut mask and self-aligned structures have been implemented to solution required device scaling. Advances in dry plasma etch process control, across wafer uniformity and etch selectivity to both masking materials and have enabled adoption of vertical devices and thin film scaling for increased device performance at a given pitch. Plasma etch processes such as trilayer etches, aggressive CD shrink techniques, and the extension of resist trim processes have increased the attainable device dimensions at a given imaging capability. Precise control of the plasma etch parameters affecting across design variation, defectivity, profile stability within wafer, within lot, and across tools have been successfully implemented to provide manufacturable patterning technology solutions. IBM has addressed these patterning challenges through an integrated Total Patterning Solutions team to provide seamless and synergistic patterning processes to device and integration internal customers. This paper will discuss these challenges and the innovative plasma etch solutions pioneered by IBM and our alliance partners.

  7. Advanced plasma etch technologies for nanopatterning

    NASA Astrophysics Data System (ADS)

    Wise, Rich

    2013-10-01

    Advances in patterning techniques have enabled the extension of immersion lithography from 65/45 nm through 14/10 nm device technologies. A key to this increase in patterning capability has been innovation in the subsequent dry plasma etch processing steps. Multiple exposure techniques, such as litho-etch-litho-etch, sidewall image transfer, line/cut mask, and self-aligned structures, have been implemented to solution required device scaling. Advances in dry plasma etch process control across wafer uniformity and etch selectivity to both masking materials have enabled adoption of vertical devices and thin film scaling for increased device performance at a given pitch. Plasma etch processes, such as trilayer etches, aggressive critical dimension shrink techniques, and the extension of resist trim processes, have increased the attainable device dimensions at a given imaging capability. Precise control of the plasma etch parameters affecting across-design variation, defectivity, profile stability within wafer, within lot, and across tools has been successfully implemented to provide manufacturable patterning technology solutions. IBM has addressed these patterning challenges through an integrated total patterning solutions team to provide seamless and synergistic patterning processes to device and integration internal customers. We will discuss these challenges and the innovative plasma etch solutions pioneered by IBM and our alliance partners.

  8. Dry etching technologies for reflective multilayer

    NASA Astrophysics Data System (ADS)

    Iino, Yoshinori; Karyu, Makoto; Ita, Hirotsugu; Kase, Yoshihisa; Yoshimori, Tomoaki; Muto, Makoto; Nonaka, Mikio; Iwami, Munenori

    2012-11-01

    We have developed a highly integrated methodology for patterning Extreme Ultraviolet (EUV) mask, which has been highlighted for the lithography technique at the 14nm half-pitch generation and beyond. The EUV mask is characterized as a reflective-type mask which is completely different compared with conventional transparent-type of photo mask. And it requires not only patterning of absorber layer without damaging the underlying multi reflective layers (40 Si/Mo layers) but also etching multi reflective layers. In this case, the dry etch process has generally faced technical challenges such as the difficulties in CD control, etch damage to quartz substrate and low selectivity to the mask resist. Shibaura Mechatronics ARESTM mask etch system and its optimized etch process has already achieved the maximal etch performance at patterning two-layered absorber. And in this study, our process technologies of multi reflective layers will be evaluated by means of optimal combination of process gases and our optimized plasma produced by certain source power and bias power. When our ARES™ is used for multilayer etching, the user can choose to etch the absorber layer at the same time or etch only the multilayer.

  9. Method for dry etching of transition metals

    DOEpatents

    Ashby, Carol I. H.; Baca, Albert G.; Esherick, Peter; Parmeter, John E.; Rieger, Dennis J.; Shul, Randy J.

    1998-01-01

    A method for dry etching of transition metals. The method for dry etching of a transition metal (or a transition metal alloy such as a silicide) on a substrate comprises providing at least one nitrogen- or phosphorous-containing .pi.-acceptor ligand in proximity to the transition metal, and etching the transition metal to form a volatile transition metal/.pi.-acceptor ligand complex. The dry etching may be performed in a plasma etching system such as a reactive ion etching (RIE) system, a downstream plasma etching system (i.e. a plasma afterglow), a chemically-assisted ion beam etching (CAIBE) system or the like. The dry etching may also be performed by generating the .pi.-acceptor ligands directly from a ligand source gas (e.g. nitrosyl ligands generated from nitric oxide), or from contact with energized particles such as photons, electrons, ions, atoms, or molecules. In some preferred embodiments of the present invention, an intermediary reactant species such as carbonyl or a halide ligand is used for an initial chemical reaction with the transition metal, with the intermediary reactant species being replaced at least in part by the .pi.-acceptor ligand for forming the volatile transition metal/.pi.-acceptor ligand complex.

  10. Hepatic arachidonic acid metabolism is disrupted after hexachlorobenzene treatment.

    PubMed

    Billi de Catabbi, Silvia C; Faletti, Alicia; Fuentes, Federico; San Martín de Viale, Leonor C; Cochón, Adriana C

    2005-04-15

    Hexaclorobenzene (HCB), one of the most persistent environmental pollutants, can cause a wide range of toxic effects including cancer in animals, and hepatotoxicity and porphyria both in humans and animals. In the present study, liver microsomal cytochrome P450 (CYP)-dependent arachidonic acid (AA) metabolism, hepatic PGE production, and cytosolic phospholipase A2 (cPLA2) activity were investigated in an experimental model of porphyria cutanea tarda induced by HCB. Female Wistar rats were treated with a single daily dose of HCB (100 mg kg(-1) body weight) for 5 days and were sacrificed 3, 10, 17, and 52 days after the last dose. HCB treatment induced the accumulation of hepatic porphyrins from day 17 and increased the activities of liver ethoxyresorufin O-deethylase (EROD), methoxyresorufin O-demethylase (MROD), and aminopyrine N-demethylase (APND) from day 3 after the last dose. Liver microsomes from control and HCB-treated rats generated, in the presence of NADPH, hydroxyeicosatetraenoic acids (HETEs), epoxyeicosatrienoic acids (EETs), 11,12-Di HETE, and omega-OH/omega-1-OH AA. HCB treatment caused an increase in total NADPH CYP-dependent AA metabolism, with a higher response at 3 days after the last HCB dose than at the other time points studied. In addition, HCB treatment markedly enhanced PGE production and release in liver slices. This HCB effect was time dependent and reached its highest level after 10 days. At this time cPLA2 activity was shown to be increased. Unexpectedly, HCB produced a significant decrease in cPLA2 activity on the 17th and 52nd day. Our results demonstrated for the first time that HCB induces both the cyclooxygenase and CYP-dependent AA metabolism. The effects of HCB on AA metabolism were previous to the onset of a marked porphyria and might contribute to different aspects of HCB-induced liver toxicity such as alterations of membrane fluidity and membrane-bound protein function. Observations also suggested that a possible role of cPLA2

  11. Restoration of obliterated engraved marks on steel surfaces by chemical etching reagent.

    PubMed

    Song, Qingfang

    2015-05-01

    Chemical etching technique is widely used for restoration of obliterated engraved marks on steel surface in the field of public security. The consumed thickness of steel surface during restoration process is considered as a major criterion for evaluating the efficiency of the chemical etching reagent. The thinner the consumed thickness, the higher the restoration efficiency. According to chemical principles, maintaining the continuous oxidative capabilities of etching reagents and increasing the kinetic rate difference of the reaction between the engraved and non-engraved area with the chemical etching reagent can effectively reduce the consumed steel thickness. The study employed steel surface from the engine case of motorcycle and the car frame of automobile. The chemical etching reagents are composed of nitric acid as the oxidizer, hydrofluoric acid as the coordination agent and mixed with glacial acetic acid or acetone as the solvents. Based on the performance evaluation of three different etching reagents, the one composed of HNO3, HF and acetone gave the best result.

  12. AFM and SEM study of the effects of etching on IPS-Empress 2 TM dental ceramic

    NASA Astrophysics Data System (ADS)

    Luo, X.-P.; Silikas, N.; Allaf, M.; Wilson, N. H. F.; Watts, D. C.

    2001-10-01

    The aim of this study was to investigate the effects of increasing etching time on the surface of the new dental material, IPS-Empress 2 TM glass ceramic. Twenty one IPS-Empress 2 TM glass ceramic samples were made from IPS-Empress 2 TM ingots through lost-wax, hot-pressed ceramic fabrication technology. All samples were highly polished and cleaned ultrasonically for 5 min in acetone before and after etching with 9.6% hydrofluoric acid gel. The etching times were 0, 10, 20, 30, 60, 90 and 120 s respectively. Microstructure was analysed by scanning electron microscopy (SEM) and atomic force microscopy (AFM) was used to evaluate the surface roughness and topography. Observations with SEM showed that etching with hydrofluoric acid resulted in preferential dissolution of glass matrix, and that partially supported crystals within the glass matrix were lost with increasing etching time. AFM measurements indicated that etching increased the surface roughness of the glass-ceramic. A simple least-squares linear regression was used to establish a relationship between surface roughness parameters ( Ra, RMS), and etching time, for which r2>0.94. This study demonstrates the benefits of combining two microscopic methods for a better understanding of the surface. SEM showed the mode of action of hydrofluoric acid on the ceramic and AFM provided valuable data regarding the extent of surface degradation relative to etching time.

  13. Maleic acid treatment of biologically detoxified corn stover liquor.

    PubMed

    Kim, Daehwan; Ximenes, Eduardo A; Nichols, Nancy N; Cao, Guangli; Frazer, Sarah E; Ladisch, Michael R

    2016-09-01

    Elimination of microbial and enzyme inhibitors from pretreated lignocellulose is critical for effective cellulose conversion and yeast fermentation of liquid hot water (LHW) pretreated corn stover. In this study, xylan oligomers were hydrolyzed using either maleic acid or hemicellulases, and other soluble inhibitors were eliminated by biological detoxification. Corn stover at 20% (w/v) solids was LHW pretreated LHW (severity factor: 4.3). The 20% solids (w/v) pretreated corn stover derived liquor was recovered and biologically detoxified using the fungus Coniochaeta ligniaria NRRL30616. After maleic acid treatment, and using 5 filter paper units of cellulase/g glucan (8.3mg protein/g glucan), 73% higher cellulose conversion from corn stover was obtained for biodetoxified samples compared to undetoxified samples. This corresponded to 87% cellulose to glucose conversion. Ethanol production by yeast of pretreated corn stover solids hydrolysate was 1.4 times higher than undetoxified samples, with a reduction of 3h in the fermentation lag phase.

  14. Sulfidogenic fluidized bed treatment of real acid mine drainage water.

    PubMed

    Sahinkaya, Erkan; Gunes, Fatih M; Ucar, Deniz; Kaksonen, Anna H

    2011-01-01

    The treatment of real acid mine drainage water (pH 2.7-4.3) containing sulfate (1.5-3.34 g/L) and various metals was studied in an ethanol-fed sulfate-reducing fluidized bed reactor at 35°C. The robustness of the process was tested by increasing stepwise sulfate, ethanol and metal loading rates and decreasing feed pH and hydraulic retention time. Highest sulfate reduction rate (4.6g/L day) was obtained with feed sulfate concentration of 2.5 g/L, COD/sulfate ratio of 0.85 and HRT of 12 h. The corresponding sulfate and COD removal efficiencies were about 90% and 80%, respectively. The alkalinity produced in sulfidogenic ethanol oxidation neutralized the acidic mine water. Highest metal precipitation efficiencies were observed at HRT of 24 h, the percent metal removal being over 99.9% for Al (initial concentration 55 mg/L), Co (9.0 mg/L), Cu (49 mg/L), Fe (435 mg/L), Ni (3.8 mg/L), Pb (7.5 mg/L) and Zn (6.6 mg/L), and 94% for Mn (7.21 mg/L).

  15. One-Year Clinical Evaluation of the Bonding Effectiveness of a One-Step, Self-Etch Adhesive in Noncarious Cervical Lesion Therapy

    PubMed Central

    Faye, Babacar; Sarr, Mouhamed; Bane, Khaly; Aidara, Adjaratou Wakha; Niang, Seydina Ousmane; Kane, Abdoul Wakhabe

    2015-01-01

    This study evaluated the one-year clinical performance of a one-step, self-etch adhesive (Optibond All-in-One, Kerr, CA, USA) combined with a composite (Herculite XRV Ultra, Kerr Hawe, CA, USA) to restore NCCLs with or without prior acid etching. Restorations performed by the same practitioner were evaluated at baseline and after 3, 6, and 12 months using modified USPHS criteria. At 6 months, the recall rate was 100%. The retention rate was 84.2% for restorations with prior acid etching, but statistically significant differences were observed between baseline and 6 months. Without acid etching, the retention rate was 77%, and no statistically significant difference was noted between 3 and 6 months. Marginal integrity (93.7% with and 87.7% without acid etching) and discoloration (95.3% with and 92.9% without acid etching) were scored as Alpha or Bravo, with better results after acid etching. After one year, the recall rate was 58.06%. Loss of pulp vitality, postoperative sensitivity, or secondary caries were not observed. After one year retention rate was of 90.6% and 76.9% with and without acid conditioning. Optibond All-in-One performs at a satisfactory clinical performance level for restoration of NCCLs after 12 months especially after acid etching. PMID:25810720

  16. Nanofabrication on monocrystalline silicon through friction-induced selective etching of Si3N4 mask.

    PubMed

    Guo, Jian; Yu, Bingjun; Wang, Xiaodong; Qian, Linmao

    2014-01-01

    A new fabrication method is proposed to produce nanostructures on monocrystalline silicon based on the friction-induced selective etching of its Si3N4 mask. With low-pressure chemical vapor deposition (LPCVD) Si3N4 film as etching mask on Si(100) surface, the fabrication can be realized by nanoscratching on the Si3N4 mask and post-etching in hydrofluoric acid (HF) and potassium hydroxide (KOH) solution in sequence. Scanning Auger nanoprobe analysis indicated that the HF solution could selectively etch the scratched Si3N4 mask and then provide the gap for post-etching of silicon substrate in KOH solution. Experimental results suggested that the fabrication depth increased with the increase of the scratching load or KOH etching period. Because of the excellent masking ability of the Si3N4 film, the maximum fabrication depth of nanostructure on silicon can reach several microns. Compared to the traditional friction-induced selective etching technique, the present method can fabricate structures with lesser damage and deeper depths. Since the proposed method has been demonstrated to be a less destructive and flexible way to fabricate a large-area texture structure, it will provide new opportunities for Si-based nanofabrication.

  17. Ultradeep fused silica glass etching with an HF-resistant photosensitive resist for optical imaging applications

    NASA Astrophysics Data System (ADS)

    Nagarah, John M.; Wagenaar, Daniel A.

    2012-03-01

    Microfluidic and optical sensing platforms are commonly fabricated in glass and fused silica (quartz) because of their optical transparency and chemical inertness. Hydrofluoric acid (HF) solutions are the etching media of choice for deep etching into silicon dioxide substrates, but processing schemes become complicated and expensive for etching times greater than 1 h due to the aggressiveness of HF migration through most masking materials. We present here etching into fused silica more than 600 µm deep while keeping the substrate free of pits and maintaining a polished etched surface suitable for biological imaging. We utilize an HF-resistant photosensitive resist (HFPR) which is not attacked in 49% HF solution. Etching characteristics are compared for substrates masked with the HFPR alone and the HFPR patterned on top of Cr/Au and polysilicon masks. We used this etching process to fabricate suspended fused silica membranes, 8-16 µm thick, and show that imaging through the membranes does not negatively affect image quality of fluorescence microscopy of biological tissue. Finally, we realize small through-pore arrays in the suspended membranes. Such devices will have applications in planar electrophysiology platforms, especially where optical imaging is required.

  18. Control over the permeation of silica nanoshells by surface-protected etching with water.

    PubMed

    Hu, Yongxing; Zhang, Qiao; Goebl, James; Zhang, Tierui; Yin, Yadong

    2010-10-14

    We demonstrate a water-based etching strategy for converting solid silica shells into porous ones with controllable permeability. It overcomes the challenges of the alkaline-based surface-protected etching process that we previously developed for the production of porous and hollow silica nanostructures. Mild etching around the boiling point of water partially breaks the imperfectly condensed silica network and forms soluble monosilicic acid, eventually producing mesoscale pores in the silica structures. With the surface protection from poly(vinyl pyrrolidone) (PVP), it is possible to maintain the overall shape of the silica structures while at the same time to create porosity inside. By using bulky PVP molecules which only protect the near-surface region, we are able to completely remove the interior silica and produce hollow particles. Because the etching is mild and controllable, this process is particularly useful for treating small silica particles or core-shell particles with very thin silica shells for which the alkaline-based etching method has been difficult to control. We demonstrated the precise control of the permeation of the chemical species through the porous silica shells by using a model reaction which involves the etching of Ag encapsulated inside Ag@SiO(2) by a halocarbon. It is expected that the water-based surface-protected etching method can be conveniently extended to the production of various porous silica shells containing functional materials whose diffusion to outside and/or reaction with outside species can be easily controlled.

  19. Shear bond strength of resin to acid/pumice-microabraded enamel.

    PubMed

    Royer, M A; Meiers, J C

    1995-01-01

    The effect of enamel microabrasion techniques consisting of either 18% hydrochloric acid in pumice or a commercially available abrasive/10% hydrochloric acid mixture, PREMA, on composite/enamel shear bond strengths was investigated. Sixty extracted third molars had the bonding surface flattened and were divided into six treatment groups (n=10) with the enamel treated prior to bonding as follows: Group 1-- untreated; Group 2--37% phosphoric acid etched for 30 seconds; Group 3--18% hydrochloric acid/pumice mixture applied for five 20-second treatments; Group 4--similar to Group 3 with additional 37% phosphoric acid etch; Group 5--treated with PREMA compound applied for five 20-second treatments; Group 6--similar to Group 5 treatment with additional 37% phosphoric acid. Herculite XR composite resin was then bonded to all samples using a VLC unit. Samples were tested in shear, and fractured enamel surfaces were evaluated using light microscopy to determine the enamel-to-resin failures. Resin bond strengths to microabraded and H3PO4-etched enamel were similar to bond strengths of untreated H3PO4-etched enamel and were significantly better than bond strengths to PREMA-treated or unetched enamel.

  20. Enhanced electromagnetic loss of polybenzoxazole copolymerized with etched multiwalled carbon nanotube via direct Friedel-Crafts acylation

    NASA Astrophysics Data System (ADS)

    Chen, Yong; Qian, Jun; Teng, Xin; Zhang, Kan; Zhuang, Qixin; Han, Zhewen

    2014-04-01

    Etched multiwalled carbon nanotube (EMCNT) was prepared via an in situ reaction between Si and MCNT induced by the reaction between Na and I2. Subsequently, EMCNTs was subjected to a copolymerization reaction with 4,6-diaminoresorcinol salt (DAR·2HCl) and terephthalic acid (TA) in polyphosphoric acid (PPA) by Friedel-Crafts acylation reaction without any acid treatment or modification. The structure and morphology of the as-prepared poly(p-phenylene benzobisoxazole) (PBO)/EMCNT nanocomposites were characterized by x-ray diffraction (XRD), Raman spectra, and transmission electron microscopy (TEM). The scanning electronic microscope (SEM) images indicated that the EMCNTs can disperse in PBO matrix uniformly without agglomeration. And the electromagnetic properties of the obtained PBO/EMCNT nanocomposites characterized by vector network analyzer (VNA) showed that the introduced PBO/EMCNT composites exhibited a greater enhancement in dielectric loss and magnetic loss than PBO.

  1. The Comparison of Hydrochloric Acid and Phosphoric Acid Treatments in the Preparation of Montmorillonite Catalysts for RNA Synthesis.

    PubMed

    Aldersley, Michael Frank; Joshi, Prakash C; Huang, Yixing

    2017-02-16

    The treatment of clay minerals with a preliminary acid wash and titration to pH 7 has proven to generate catalysts for the most interesting of oligomerization reactions in which activated RNA-nucleotides generate oligomers up to 40-mers. Significantly, not all clay minerals become catalytic following this treatment and none are catalytic in the absence of such treatment. The washing procedure has been modified and explored further using phosphoric acid and the outcomes are compared to those obtained when clay samples are prepared following a hydrochloric acid wash.

  2. The Comparison of Hydrochloric Acid and Phosphoric Acid Treatments in the Preparation of Montmorillonite Catalysts for RNA Synthesis

    NASA Astrophysics Data System (ADS)

    Aldersley, Michael Frank; Joshi, Prakash C.; Huang, Yixing

    2017-02-01

    The treatment of clay minerals with a preliminary acid wash and titration to pH 7 has proven to generate catalysts for the most interesting of oligomerization reactions in which activated RNA-nucleotides generate oligomers up to 40-mers. Significantly, not all clay minerals become catalytic following this treatment and none are catalytic in the absence of such treatment. The washing procedure has been modified and explored further using phosphoric acid and the outcomes are compared to those obtained when clay samples are prepared following a hydrochloric acid wash.

  3. Solid Lipid Nanoparticles Loaded with Retinoic Acid and Lauric Acid as an Alternative for Topical Treatment of Acne Vulgaris.

    PubMed

    Silva, Elton Luiz; Carneiro, Guilherme; De Araújo, Lidiane Advíncula; Trindade, Mariana de Jesus Vaz; Yoshida, Maria Irene; Oréfice, Rodrigo Lambert; Farias, Luis de Macêdo; De Carvalho, Maria Auxiliadora Roque; Dos Santos, Simone Gonçalves; Goulart, Gisele Assis Castro; Alves, Ricardo José; Ferreira, Lucas Antônio Miranda

    2015-01-01

    Topical therapy is the first choice for the treatment of mild to moderate acne and all-trans retinoic acid is one of the most used drugs. The combination of retinoids and antimicrobials is an innovative approach for acne therapy. Recently, lauric acid, a saturated fatty acid, has shown strong antimicrobial activity against Propionibacterium acnes. However, topical application of retinoic acid is followed by high incidence of side-effects, including erythema and irritation. Solid lipid nanoparticles represent an alternative to overcome these side-effects. This work aims to develop solid lipid nanoparticles loaded with retinoic acid and lauric acid and evaluate their antibacterial activity. The influence of lipophilic stearylamine on the characteristics of solid lipid nanoparticles was investigated. Solid lipid nanoparticles were characterized for size, zeta potential, encapsulation efficiency, differential scanning calorimetry and X-ray diffraction. The in vitro inhibitory activity of retinoic acid-lauric acid-loaded solid lipid nanoparticles was evaluated against Propionibacterium acnes, Staphylococcus aureus and Staphylococcus epidermidis. High encapsulation efficiency was obtained at initial time (94 ± 7% and 100 ± 4% for retinoic acid and lauric acid, respectively) and it was demonstrated that lauric acid-loaded-solid lipid nanoparticles provided the incorporation of retinoic acid. However, the presence of stearylamine is necessary to ensure stability of encapsulation. Moreover, retinoic acid-lauric acid-loaded solid lipid nanoparticles showed growth inhibitory activity against Staphylococcus epidermidis, Propionibacterium acnes and Staphylococcus aureus, representing an interesting alternative for the topical therapy of acne vulgaris.

  4. Ursodeoxycholic Acid for Treatment of Enlarged Polycystic Liver.

    PubMed

    Iijima, Takashi; Hoshino, Junichi; Suwabe, Tatsuya; Sumida, Keiichi; Mise, Koki; Kawada, Masahiro; Imafuku, Aya; Hayami, Noriko; Hiramatsu, Rikako; Hasegawa, Eiko; Sawa, Naoki; Takaichi, Kenmei; Ubara, Yoshifumi

    2016-02-01

    Patients with autosomal dominant polycystic kidney disease and polycystic liver disease (PLD) often have elevated serum levels of alkaline phosphatase (ALP) and gamma-glutamyl transpeptidase (GGT). Ursodeoxycholic acid (UDCA) is used to treat biliary tract diseases, but its effect on PLD remains unclear. UDCA was administered for 1 year at a dose of 300 mg daily to seven PLD patients with elevated ALP or GGT levels who were selected for this treatment by experienced clinicians. Laboratory data and liver volumes were compared among three time points: 1 year before UDCA treatment, at the start of UDCA therapy, and 1 year after the start of therapy. Median GGT did not show a significant change between 1 year before UDCA (180 IU/L) and the start of UDCA therapy (209 IU/L), but it decreased significantly to 98 IU/L after 1 year of UDCA therapy (P = 0.015 vs. the start of therapy). ALP showed a significant increase from 1 year before UDCA (456 IU/L) to the start of UDCA therapy (561 IU/L), and then decreased significantly after 1 year of UDCA therapy (364 IU/L). Median liver volume did not show any significant changes among these three time points of assessment. UDCA may be effective for reducing biliary enzyme levels and inhibiting the growth of liver cysts in patients with PLD.

  5. SAXS study on the morphology of etched and un-etched ion tracks in apatite

    NASA Astrophysics Data System (ADS)

    Nadzri, A.; Schauries, D.; Afra, B.; Rodriguez, M. D.; Mota-Santiago, P.; Muradoglu, S.; Hawley, A.; Kluth, P.

    2015-04-01

    Natural apatite samples were irradiated with 185 MeV Au and 2.3 GeV Bi ions to simulate fission tracks. The resulting track morphology was investigated using synchrotron small angle x-ray scattering (SAXS) measurements before and after chemical etching. We present preliminary results from the SAXS measurement showing the etching process is highly anisotropic yielding faceted etch pits with a 6-fold symmetry. The measurements are a first step in gaining new insights into the correlation between etched and unetched fission tracks and the use of SAXS as a tool for studying etched tracks.

  6. Optimization of HNA etching parameters to produce high aspect ratio solid silicon microneedles

    NASA Astrophysics Data System (ADS)

    Hamzah, A. A.; Abd Aziz, N.; Yeop Majlis, B.; Yunas, J.; Dee, C. F.; Bais, B.

    2012-09-01

    High aspect ratio solid silicon microneedles with a concave conic shape were fabricated. Hydrofluoric acid-nitric acid-acetic acid (HNA) etching parameters were characterized and optimized to produce microneedles that have long and narrow bodies with smooth surfaces, suitable for transdermal drug delivery applications. The etching parameters were characterized by varying the HNA composition, the optical mask's window size, the etching temperature and bath agitation. An L9 orthogonal Taguchi experiment with three factors, each having three levels, was utilized to determine the optimal fabrication parameters. Isoetch contours for HNA composition with 0% and 10% acetic acid concentrations were presented and a high nitric acid region was identified to produce microneedles with smooth surfaces. It is observed that an increase in window size indiscriminately increases the etch rate in both the vertical and lateral directions, while an increase in etching temperature beyond 35 °C causes the etching to become rapid and uncontrollable. Bath agitation and sample placement could be manipulated to achieve a higher vertical etch rate compared to its lateral counterpart in order to construct high aspect ratio microneedles. The Taguchi experiment performed suggests that a HNA composition of 2:7:1 (HF:HNO3:CH3COOH), window size of 500 µm and agitation rate of 450 RPM are optimal. Solid silicon microneedles with an average height of 159.4 µm, an average base width of 110.9 µm, an aspect ratio of 1.44, and a tip angle and diameter of 19.2° and 0.38 µm respectively were successfully fabricated.

  7. Simulation of Etching Profiles Using Level Sets

    NASA Technical Reports Server (NTRS)

    Hwang, Helen; Govindan, T. R.; Meyyappan, M.; Arnold, James O. (Technical Monitor)

    1998-01-01

    Using plasma discharges to etch trenches and via holes in substrates is an important process in semiconductor manufacturing. Ion enhanced etching involves both neutral fluxes, which are isotropic, and ion fluxes, which are anisotropic. The angular distributions for the ions determines the degree of vertical etch, while the amount of the neutral fluxes determines the etch rate. We have developed a 2D profile evolution simulation which uses level set methods to model the plasma-substrate interface. Using level sets instead of traditional string models avoids the use of complicated delooping algorithms. The simulation calculates the etch rate based on the fluxes and distribution functions of both ions and neutrals. We will present etching profiles of Si substrates in low pressure (10s mTorr) Ar/Cl2 discharges for a variety of incident ion angular distributions. Both ion and neutral re-emission fluxes are included in the calculation of the etch rate, and their contributions to the total etch profile will be demonstrated. In addition, we will show RIE lag effects as a function of different trench aspect ratios. (For sample profiles, please see http://www.ipt.arc.nasa.gov/hwangfig1.html)

  8. Gallium nitride nanowires by maskless hot phosphoric wet etching

    NASA Astrophysics Data System (ADS)

    Bharrat, D.; Hosalli, A. M.; Van Den Broeck, D. M.; Samberg, J. P.; Bedair, S. M.; El-Masry, N. A.

    2013-08-01

    We demonstrate gallium nitride (GaN) nanowires formation by controlling the selective and anisotropic etching of N-polar GaN in hot phosphoric acid. Nanowires of ˜109/cm,2 total height of ˜400 nm, and diameters of 170-200 nm were obtained. These nanowires have both non-polar {11¯00}/ {112¯0} and semi-polar {1011¯} facets. X-Ray Diffraction characterization shows that screw dislocations are primarily responsible for preferential etching to create nanowires. Indium gallium nitride multi-quantum wells (MQWs) grown on these GaN nanowires showed a blue shift in peak emission wavelength of photoluminescence spectra, and full width at half maximum decreased relative to MQWs grown on planar N-polar GaN, respectively.

  9. Etch selectivity of a wet chemical formulation for premetal cleaning

    NASA Astrophysics Data System (ADS)

    Epton, Jeremy W.; Jarrett, Deborah L.; Doohan, Ian J.

    2001-04-01

    This paper examines the relative etching rates of doped and thermal silicon dioxide when using NSSL etchant, comprising of a mixture of ammonium fluoride, water and ammonium dihydrogen phosphate [(NH4)H2PO4] and investigates their dependence on both temperature and mixture composition. The possible reaction mechanism is discussed and compared with the known mechanism for standard buffered oxide etchants (BOE). The observed etch selectivity and mechanisms of BOE and NSSL are also compared with the behavior of a third chemical formulation, referred to as mixed oxide etchant, which comprises of ammonium fluoride (NH4F) solution, diammonium hydrogen phosphate [(NH4)2HPO4] and orthophosphoric acid (H3PO4). It is concluded that no major change in oxide selectivity is observed if either BOE or NSSL etchants are used in the metal pre-clean process.

  10. Preliminary surface analysis of etched, bleached, and normal bovine enamel

    SciTech Connect

    Ruse, N.D.; Smith, D.C.; Torneck, C.D.; Titley, K.C. )

    1990-09-01

    X-ray photoelectron spectroscopic (XPS) and secondary ion-mass spectroscopic (SIMS) analyses were performed on unground un-pumiced, unground pumiced, and ground labial enamel surfaces of young bovine incisors exposed to four different treatments: (1) immersion in 35% H2O2 for 60 min; (2) immersion in 37% H3PO4 for 60 s; (3) immersion in 35% H2O2 for 60 min, in distilled water for two min, and in 37% H3PO4 for 60 s; (4) immersion in 37% H3PO4 for 60 s, in distilled water for two min, and in 35% H2O2 for 60 min. Untreated unground un-pumiced, unground pumiced, and ground enamel surfaces, as well as synthetic hydroxyapatite surfaces, served as controls for intra-tooth evaluations of the effects of different treatments. The analyses indicated that exposure to 35% H2O2 alone, besides increasing the nitrogen content, produced no other significant change in the elemental composition of any of the enamel surfaces investigated. Exposure to 37% H3PO4, however, produced a marked decrease in calcium (Ca) and phosphorus (P) concentrations and an increase in carbon (C) and nitrogen (N) concentrations in unground un-pumiced specimens only, and a decrease in C concentration in ground specimens. These results suggest that the reported decrease in the adhesive bond strength of resin to 35% H2O2-treated enamel is not caused by a change in the elemental composition of treated enamel surfaces. They also suggest that an organic-rich layer, unaffected by acid-etching, may be present on the unground un-pumiced surface of young bovine incisors. This layer can be removed by thorough pumicing or by grinding. An awareness of its presence is important when young bovine teeth are used in a model system for evaluation of resin adhesiveness.

  11. Mechanisms of Hydrocarbon Based Polymer Etch

    NASA Astrophysics Data System (ADS)

    Lane, Barton; Ventzek, Peter; Matsukuma, Masaaki; Suzuki, Ayuta; Koshiishi, Akira

    2015-09-01

    Dry etch of hydrocarbon based polymers is important for semiconductor device manufacturing. The etch mechanisms for oxygen rich plasma etch of hydrocarbon based polymers has been studied but the mechanism for lean chemistries has received little attention. We report on an experimental and analytic study of the mechanism for etching of a hydrocarbon based polymer using an Ar/O2 chemistry in a single frequency 13.56 MHz test bed. The experimental study employs an analysis of transients from sequential oxidation and Ar sputtering steps using OES and surface analytics to constrain conceptual models for the etch mechanism. The conceptual model is consistent with observations from MD studies and surface analysis performed by Vegh et al. and Oehrlein et al. and other similar studies. Parameters of the model are fit using published data and the experimentally observed time scales.

  12. Optical fiber nanoprobe preparation for near-field optical microscopy by chemical etching under surface tension and capillary action.

    PubMed

    Mondal, Samir K; Mitra, Anupam; Singh, Nahar; Sarkar, S N; Kapur, Pawan

    2009-10-26

    We propose a technique of chemical etching for fabrication of near perfect optical fiber nanoprobe (NNP). It uses photosensitive single mode optical fiber to etch in hydro fluoric (HF) acid solution. The difference in etching rate for cladding and photosensitive core in HF acid solution creates capillary ring along core-cladding boundary under a given condition. The capillary ring is filled with acid solution due to surface tension and capillary action. Finally it creates near perfect symmetric tip at the apex of the fiber as the height of the acid level in capillary ring decreases while width of the ring increases with continuous etching. Typical tip features are short taper length (approximately 4 microm), large cone angle (approximately 38 degrees ), and small probe tip dimension (<100 nm). A finite difference time domain (FDTD) analysis is also presented to compare near field optics of the NNP with conventional nanoprobe (CNP). The probe may be ideal for near field optical imaging and sensor applications.

  13. Selective enamel etching: effect on marginal adaptation of self-etch LED-cured bond systems in aged Class I composite restorations.

    PubMed

    Souza-Junior, E J; Prieto, L T; Araújo, C T P; Paulillo, L A M S

    2012-01-01

    The aim of this study was to evaluate the influence of previous enamel etch and light emitting diode (LED) curing on gap formation of self-etch adhesive systems in Class I composite restorations after thermomechanical aging (TMA). Thus, on 192 human molars, a box-shaped Class I cavity was prepared maintaining enamel margins. Self-etch adhesives (Clearfil SE and Clearfil S3) were used to restore the preparation with a microhybrid composite. Before application of the adhesives, half of the teeth were enamel etched for 15 seconds with 37% phosphoric acid; the other half were not etched. For the photoactivation of the adhesives and composite, three light-curing units (LCUs) were used: one polywave (Ultra-Lume LED 5, UL) and two single-peak (FlashLite 1401, FL and Radii-cal, RD) LEDs. After this, epoxy resin replicas of the occlusal surface were made, and the specimens were submitted to TMA. New replicas were made from the aged specimens for marginal adaptation analysis by scanning electron microscopy. Data were submitted to Kruskal-Wallis and Wilcoxon tests (α=0.05). Before TMA, when enamel was etched before the application of S3, no gap formation was observed; however, there were gaps at the interface for the other tested conditions, with a statistical difference (p≤0.05). After TMA, the selective enamel etching previous to the S3 application, regardless of the LCU, promoted higher marginal adaptation compared to the other tested groups (p≤0.05). Prior to TMA, higher marginal integrity was observed, in comparison with specimens after TMA (p≤0.05). With regard to Clearfil SE and Clearfil Tri-S cured with FL, no differences of gap formation were found between before and after aging (5.3 ± 3.8 and 7.4 ± 7.5, respectively), especially when the Clearfil Tri-S was used in the conventional protocol. When cured with RD or UL and not etched, Clearfil Tri-S presented the higher gap formation. In conclusion, additional enamel etching promoted better marginal integrity

  14. Etch-a-Sketch Nanoelectronics

    NASA Astrophysics Data System (ADS)

    Levy, Jeremy

    2009-10-01

    The popular children's toy Etch-a-Sketch has motivated the invention of a new material capable of writing and erasing wires so small they approach the spacing between atoms. The interface between two normally insulating materials, strontium titanate and lanthanum aluminate, can be switched between the insulating and conducting state with the use of the sharp metallic probe of an atomic-force microscope. By ``sketching'' this probe in various patterns, one can create electronic materials with remarkably diverse properties. This material system shows promise both for ultra-high density storage and as possible replacements for silicon-based logic (CMOS). This work is supported by the National Science Foundation, Defense Advanced Research Projects Agency, Army Research Office and Air Force Office of Scientific Research.

  15. Nanoscale etching and flattening of metals with ozone water.

    PubMed

    Hatsuki, Ryuji; Yamamoto, Takatoki

    2012-06-13

    Etchants used for metal etching are generally harmful to the environment. We propose an environmentally friendly method that uses ozone water to etch metals. We measured the dependencies of ozone water etching on the temperature and ozone concentration for several metals and evaluated the surface roughness of the etched surfaces. The etching rate was proportional to the dissolved ozone concentration, and the temperature and the surfaces were smoothed by etching.

  16. Wet etching of InSb surfaces in aqueous solutions: Controlled oxide formation

    NASA Astrophysics Data System (ADS)

    Aureau, D.; Chaghi, R.; Gerard, I.; Sik, H.; Fleury, J.; Etcheberry, A.

    2013-07-01

    This paper investigates the wet etching of InSb surfaces by two different oxidant agents: Br2 and H2O2 and the consecutive oxides generation onto the surfaces. The strong dependence between the chemical composition of the etching baths and the nature of the final surface chemistry of this low band-gap III-V semiconductor will be especially highlighted. One aqueous etching solution combined hydrobromic acid and Bromine (HBr-Br2:H2O) with adjusted concentrations. The other solution combines orthophosphoric and citric acids with hydrogen peroxide (H3PO4-H2O2:H2O). Depending on its composition, each formulation gave rise to variable etching rate. The dosage of Indium traces in the etching solution by atomic absorption spectroscopy (AAS) gives the kinetic variation of the dissolution process. The variations on etching rates are associated to the properties and the nature of the formed oxides on InSb surfaces. Surface characterization is specifically performed by X-ray photoelectron spectroscopy (XPS). A clear evidence of the differences between the formed oxides is highlighted. Atomic force microscopy is used to monitor the surface morphology and pointed out that very different final morphologies can be reached. This paper presents new results on the strong variability of the InSb oxides in relation with the InSb reactivity toward environment interaction.

  17. Effect of wet etching process on the morphology and transmittance of fluorine doped tin oxide (FTO)

    NASA Astrophysics Data System (ADS)

    Triana, S. L.; Kusumandari; Suryana, R.

    2016-11-01

    Wet etching process was performed on the surface of FTO. The FTO coated glasses subtrates with size of 2×2 cm covered by screen were patterned using zinc powder and concentrated hydrochloric acid (1 M). The substrates were then cleaned in ultrasonic baths of special detergent(helmanex) diluted in deionized water and isopropanol in sequence. The screens with various of hole size denotes by T32, T49 and T55 were used in order to create a pattern of surface textured. The atomic force microscopy (AFM) image revealed that wet etching process changes the morphology of FTO. It indicates that texturization occured. Moreover, from the UV-Vis Spectrophotometer measurement, the transmittance of FTO increase after wet etching process. The time of etching and pattern of screen were affect to the morphology and the transmittance of FTO.

  18. Silver ion mediated shape control of platinum nanoparticles: Removal of silver by selective etching leads to increased catalytic activity

    SciTech Connect

    Grass, Michael E.; Yue, Yao; Habas, Susan E.; Rioux, Robert M.; Teall, Chelsea I.; Somorjai, G.A.

    2008-01-09

    A procedure has been developed for the selective etching of Ag from Pt nanoparticles of well-defined shape, resulting in the formation of elementally-pure Pt cubes, cuboctahedra, or octahedra, with a largest vertex-to-vertex distance of {approx}9.5 nm from Ag-modified Pt nanoparticles. A nitric acid etching process was applied Pt nanoparticles supported on mesoporous silica, as well as nanoparticles dispersed in aqueous solution. The characterization of the silica-supported particles by XRD, TEM, and N{sub 2} adsorption measurements demonstrated that the structure of the nanoparticles and the mesoporous support remained conserved during etching in concentrated nitric acid. Both elemental analysis and ethylene hydrogenation indicated etching of Ag is only effective when [HNO{sub 3}] {ge} 7 M; below this concentration, the removal of Ag is only {approx}10%. Ethylene hydrogenation activity increased by four orders of magnitude after the etching of Pt octahedra that contained the highest fraction of silver. High-resolution transmission electron microscopy of the unsupported particles after etching demonstrated that etching does not alter the surface structure of the Pt nanoparticles. High [HNO{sub 3}] led to the decomposition of the capping agent, polyvinylpyrollidone (PVP); infrared spectroscopy confirmed that many decomposition products were present on the surface during etching, including carbon monoxide.

  19. Towards energy positive wastewater treatment by sludge treatment using free nitrous acid.

    PubMed

    Wang, Qilin; Hao, Xiaodi; Yuan, Zhiguo

    2016-02-01

    Free nitrous acid (FNA i.e. HNO2) was revealed to be effective in enhancing biodegradability of secondary sludge. Also, nitrite-oxidizing bacteria were found to be more susceptible to FNA than ammonium-oxidizing bacteria. Based on these findings, a novel FNA-based sludge treatment technology is proposed to enhance energy recovery from wastewater/sludge. Energy analysis indicated that the FNA-based technology would make wastewater treatment become an energy generating process (yielding energy at 4 kWh/PE/y; kWh/PE/y: kilowatt hours per population equivalent per year), rather than being a large energy consumer that it is today (consuming energy at 24 kWh/PE/y). Importantly, FNA required for the sludge treatment could be produced as a by-product of wastewater treatment. This proposed FNA-based technology is economically and environmentally attractive, and can be easily implemented in any wastewater treatment plants. It only involves the installation of a simple sludge mixing tank. This article presents the concept of the FNA-based technology.

  20. A Sustainable Approach for Acid Rock Drainage Treatment using Clinoptilolite

    NASA Astrophysics Data System (ADS)

    Li, L. Y.; Xu, W.; Grace, J. R.

    2009-04-01

    Problems related to acid rock drainage (ARD) occur along many highways of British Columbia. The ARD problem at Pennask Creek along Highway 97C in the Thompson-Okanagan region is an ideal site for pilot study to investigate a possible remediation solution. The highway was opened in 1991. An ARD problem was identified in 1997. Both sides of Highway 97C are producing acidified runoff from both cut rock surface and a fractured ditch. This runoff eventually enters Pennask Creek, the largest spawning source of rainbow trout in British Columbia. The current remediation technique using limestone for ARD treatment appears to be unnecessarily expensive, to generate additional solid waste and to not be optimally effective. A soil mineral natural zeolite - clinoptilolite - which is inexpensive and locally available, has a high metal adsorption capacity and a significant buffering capacity. Moreover, the clinoptilolite materials could be back-flushed and reused on site. An earlier batch adsorption study from our laboratory demonstrated that clinoptilolite has a high adsorption capacity for Cu, Zn, Al, with adsorption concentrations 131, 158 and 215 mg/kg clinoptilolite, respectively, from ARD of pH 3.3. Removal of metals from the loaded clinoptilolite by back-flushing was found to depend on the pH, with an optimum pH range for extraction of 2.5 to 4.0 for a contact time of one hour. The rank of desorption effectiveness was EDTA > NaCl > NaNO3 > NaOAC > NaHCO3 > Na2CO3 > NaOH > Ca(OH)2. A novel process involving cyclic adsorption on clinoptilolite followed by regeneration of the sorbent by desorption is examined for the removal of heavy metals from acid rock drainage. Experimental results show that the adsorption of zinc and copper depends on the pH and on external mass transfer. Desorption is assisted by adding NaCl to the water. A slurry bubble column was able to significantly reduce the time required for both adsorption and desorption in batch tests. XRD analysis indicated

  1. High density plasma etching of magnetic devices

    NASA Astrophysics Data System (ADS)

    Jung, Kee Bum

    Magnetic materials such as NiFe (permalloy) or NiFeCo are widely used in the data storage industry. Techniques for submicron patterning are required to develop next generation magnetic devices. The relative chemical inertness of most magnetic materials means they are hard to etch using conventional RIE (Reactive Ion Etching). Therefore ion milling has generally been used across the industry, but this has limitations for magnetic structures with submicron dimensions. In this dissertation, we suggest high density plasmas such as ECR (Electron Cyclotron Resonance) and ICP (Inductively Coupled Plasma) for the etching of magnetic materials (NiFe, NiFeCo, CoFeB, CoSm, CoZr) and other related materials (TaN, CrSi, FeMn), which are employed for magnetic devices like magnetoresistive random access memories (MRAM), magnetic read/write heads, magnetic sensors and microactuators. This research examined the fundamental etch mechanisms occurring in high density plasma processing of magnetic materials by measuring etch rate, surface morphology and surface stoichiometry. However, one concern with using Cl2-based plasma chemistry is the effect of residual chlorine or chlorinated etch residues remaining on the sidewalls of etched features, leading to a degradation of the magnetic properties. To avoid this problem, we employed two different processing methods. The first one is applying several different cleaning procedures, including de-ionized water rinsing or in-situ exposure to H2, O2 or SF6 plasmas. Very stable magnetic properties were achieved over a period of ˜6 months except O2 plasma treated structures, with no evidence of corrosion, provided chlorinated etch residues were removed by post-etch cleaning. The second method is using non-corrosive gas chemistries such as CO/NH3 or CO2/NH3. There is a small chemical contribution to the etch mechanism (i.e. formation of metal carbonyls) as determined by a comparison with Ar and N2 physical sputtering. The discharge should be NH3

  2. Treatment of odorous volatile fatty acids using a biotrickling filter.

    PubMed

    Tsang, Y F; Chua, H; Sin, S N; Chan, S Y

    2008-02-01

    In this study, a novel fibrous bioreactor was developed for treating odorous compounds present in contaminated air. The first stage of this work was a preliminary study which aimed at investigating the feasibility of using the fibrous bioreactor for the removal of malodorous volatile fatty acids (VFA) that is a common odorous contaminant generated from anaerobic degradation of organic compounds. The kinetics of microbial growth and VFA degradation in the selected culture, and the performance of the submerged bioreactor at different VFA mass loadings were studied. Above 95% of VFA removal efficiencies were achieved at mass loadings up to 22.4 g/m(3)/h. In the second stage, the odour treatment process was scaled up with system design and operational considerations. A trickling biofilter with synthetic fibrous packing medium was employed. The effects of inlet VFA concentration and empty bed retention time (EBRT) on the process performance were investigated. The bioreactor was effective in removing VFA at mass loadings up to 32 g/m(3)/h, beyond which VFA started to accumulate in the recirculation liquid, indicating the biofilm was unable to degrade all of the VFA introduced. Although VFA accumulated in the liquid phase, the removal efficiency remained above 99%. This suggested that the biochemical reaction rather than gas-liquid mass transfer was the limiting step of the treatment process. In addition, the biotrickling filter was stable for long-term operation with relatively low and steady pressure drop, no clogging and degeneration of the packing material occurred during the four-month study.

  3. Galvanic etch stop for Si in KOH

    NASA Astrophysics Data System (ADS)

    Connolly, E. J.; French, P. J.; Xia, X. H.; Kelly, J. J.

    2004-08-01

    Etch stops and etch-stopping techniques are essential 'tools' for 2D and 3D MEMS devices. Until now, use of a galvanic etch stop (ES) for micromachining in alkaline solutions was usually prohibited due to the large Au:Si area needed and/or high oxygen content required to achieve the ES. We report a new galvanic ES which requires a Au:exposed silicon area ratio of only ~1. Thus for the first time a practical galvanic ES for KOH has been achieved. The ES works by adding small amounts of sodium hypochlorite, NaOCl, to KOH solutions. Essentially the NaOCl increases the oxygen content in the KOH etchant. The dependancy of the galvanic ES on KOH concentration and temperature is investigated. Also, we report on the effects of the added NaOCl on etch rates. SEM images are used to examine the galvanically etch-stopped membranes and their surface morphology. For 33% KOH solutions the galvanic etch stop worked well, producing membranes with uniform thickness ~6 µm (i.e. slightly greater than the deposited epilayer). For 20% KOH solutions, the galvanic etch stop still worked, but the resulting membranes were a little thicker (~10 µm).

  4. Fe-catalyzed etching of graphene layers

    NASA Astrophysics Data System (ADS)

    Cheng, Guangjun; Calizo, Irene; Hight Walker, Angela; PML, NIST Team

    We investigate the Fe-catalyzed etching of graphene layers in forming gas. Fe thin films are deposited by sputtering onto mechanically exfoliated graphene, few-layer graphene (FLG), and graphite flakes on a Si/SiO2 substrate. When the sample is rapidly annealed in forming gas, particles are produced due to the dewetting of the Fe thin film and those particles catalyze the etching of graphene layers. Monolayer graphene and FLG regions are severely damaged and that the particles catalytically etch channels in graphite. No etching is observed on graphite for the Fe thin film annealed in nitrogen. The critical role of hydrogen indicates that this graphite etching process is catalyzed by Fe particles through the carbon hydrogenation reaction. By comparing with the etched monolayer and FLG observed for the Fe film annealed in nitrogen, our Raman spectroscopy measurements identify that, in forming gas, the catalytic etching of monolayer and FLG is through carbon hydrogenation. During this process, Fe particles are catalytically active in the dissociation of hydrogen into hydrogen atoms and in the production of hydrogenated amorphous carbon through hydrogen spillover.

  5. Etch Characteristics of GaN using Inductively Coupled Cl2 Plasma Etching

    NASA Astrophysics Data System (ADS)

    Rosli, Siti Azlina; Aziz, A. Abdul

    2008-05-01

    In this study, the plasma characteristics and GaN etch properties of inductively coupled Cl2/Ar plasmas were investigated. It has shown that the results of a study of inductively coupled plasma (ICP) etching of gallium nitride by using Cl2/Ar is possible to meet the requirement (anisotropy, high etch rate and high selectivity), simultaneously. We have investigated the etching rate dependency on the percentage of Argon in the gas mixture, the total pressure and DC voltage. We found that using a gas mixture with 20 sccm of Ar, the optimum etch rate of GaN was achieved. The etch rate were found to increase with voltage, attaining a maximum rate 2500 Å/min at -557 V. The addition of an inert gas, Ar is found to barely affect the etch rate. Surface morphology of the etched samples was verified by scanning electron microscopy and atomic force microscopy. It was found that the etched surface was anisotropic and the smoothness of the etched surface is comparable to that of polished wafer.

  6. Characterization of limestone reacted with acid-mine drainage in a pulsed limestone bed treatment system at the Friendship Hill National Historical Site, Pennsylvania, USA

    USGS Publications Warehouse

    Hammarstrom, J.M.; Sibrell, P.L.; Belkin, H.E.

    2003-01-01

    Armoring of limestone is a common cause of failure in limestone-based acid-mine drainage (AMD) treatment systems. Limestone is the least expensive material available for acid neutralization, but is not typically recommended for highly acidic, Fe-rich waters due to armoring with Fe(III) oxyhydroxide coatings. A new AMD treatment technology that uses CO2 in a pulsed limestone bed reactor minimizes armor formation and enhances limestone reaction with AMD. Limestone was characterized before and after treatment with constant flow and with the new pulsed limestone bed process using AMD from an inactive coal mine in Pennsylvania (pH = 2.9, Fe = 150 mg/l, acidity = 1000 mg/l CaCO3). In constant flow experiments, limestone is completely armored with reddish-colored ochre within 48 h of contact in a fluidized bed reactor. Effluent pH initially increased from the inflow pH of 2.9 to over 7, but then decreased to 6 during operation. Limestone removed from a pulsed bed pilot plant is a mixture of unarmored, rounded and etched limestone grains and partially armored limestone and refractory mineral grains (dolomite, pyrite). The ???30% of the residual grains in the pulsed flow reactor that are armored have thicker (50- to 100-??m), more aluminous coatings and lack the gypsum rind that develops in the constant flow experiment. Aluminium-rich zones developed in the interior parts of armor rims in both the constant flow and pulsed limestone bed experiments in response to pH changes at the solid/solution interface. ?? 2003 Elsevier Ltd. All rights reserved.

  7. Dry etching method for compound semiconductors

    DOEpatents

    Shul, R.J.; Constantine, C.

    1997-04-29

    A dry etching method is disclosed. According to the present invention, a gaseous plasma comprising, at least in part, boron trichloride, methane, and hydrogen may be used for dry etching of a compound semiconductor material containing layers including aluminum, or indium, or both. Material layers of a compound semiconductor alloy such as AlGaInP or the like may be anisotropically etched for forming electronic devices including field-effect transistors and heterojunction bipolar transistors and for forming photonic devices including vertical-cavity surface-emitting lasers, edge-emitting lasers, and reflectance modulators. 1 fig.

  8. Dry etching method for compound semiconductors

    SciTech Connect

    Shul, Randy J.; Constantine, Christopher

    1997-01-01

    A dry etching method. According to the present invention, a gaseous plasma comprising, at least in part, boron trichloride, methane, and hydrogen may be used for dry etching of a compound semiconductor material containing layers including aluminum, or indium, or both. Material layers of a compound semiconductor alloy such as AlGaInP or the like may be anisotropically etched for forming electronic devices including field-effect transistors and heterojunction bipolar transistors and for forming photonic devices including vertical-cavity surface-emitting lasers, edge-emitting lasers, and reflectance modulators.

  9. Method of sputter etching a surface

    DOEpatents

    Henager, Jr., Charles H.

    1984-01-01

    The surface of a target is textured by co-sputter etching the target surface with a seed material adjacent thereto, while the target surface is maintained at a pre-selected temperature. By pre-selecting the temperature of the surface while sputter etching, it is possible to predetermine the reflectance properties of the etched surface. The surface may be textured to absorb sunlight efficiently and have minimal emittance in the infrared region so as to be well-suited for use as a solar absorber for photothermal energy conversion.

  10. Method of sputter etching a surface

    DOEpatents

    Henager, C.H. Jr.

    1984-02-14

    The surface of a target is textured by co-sputter etching the target surface with a seed material adjacent thereto, while the target surface is maintained at a pre-selected temperature. By pre-selecting the temperature of the surface while sputter etching, it is possible to predetermine the reflectance properties of the etched surface. The surface may be textured to absorb sunlight efficiently and have minimal emittance in the infrared region so as to be well-suited for use as a solar absorber for photothermal energy conversion. 4 figs.

  11. Electroless epitaxial etching for semiconductor applications

    DOEpatents

    McCarthy, Anthony M.

    2002-01-01

    A method for fabricating thin-film single-crystal silicon on insulator substrates using electroless etching for achieving efficient etch stopping on epitaxial silicon substrates. Microelectric circuits and devices are prepared on epitaxial silicon wafers in a standard fabrication facility. The wafers are bonded to a holding substrate. The silicon bulk is removed using electroless etching leaving the circuit contained within the epitaxial layer remaining on the holding substrate. A photolithographic operation is then performed to define streets and wire bond pad areas for electrical access to the circuit.

  12. Etching and Chemical Control of the Silicon Nitride Surface.

    PubMed

    Brunet, Marine; Aureau, Damien; Chantraine, Paul; Guillemot, François; Etcheberry, Arnaud; Gouget-Laemmel, Anne Chantal; Ozanam, François

    2017-01-25

    Silicon nitride is used for many technological applications, but a quantitative knowledge of its surface chemistry is still lacking. Native oxynitride at the surface is generally removed using fluorinated etchants, but the chemical composition of surfaces still needs to be determined. In this work, the thinning (etching efficiency) of the layers after treatments in HF and NH4F solutions has been followed by using spectroscopic ellipsometry. A quantitative estimation of the chemical bonds found on the surface is obtained by a combination of infrared absorption spectroscopy in ATR mode, X-ray photoelectron spectroscopy, and colorimetry. Si-F bonds are the majority species present at the surface after silicon nitride etching; some Si-OH and a few Si-NHx bonds are also present. No Si-H bonds are present, an unfavorable feature for surface functionalization in view of the interest of such mildly reactive groups for achieving stable covalent grafting. Mechanisms are described to support the experimental results, and two methods are proposed for generating surface SiH species: enriching the material in silicon, or submitting the etched surface to a H2 plasma treatment.

  13. Hierarchical silicon etched structures for controlled hydrophobicity/superhydrophobicity.

    PubMed

    Xiu, Yonghao; Zhu, Lingbo; Hess, Dennis W; Wong, C P

    2007-11-01

    Silicon surface hydrophobicity has been varied by using silane treatments on silicon pyramid surfaces generated by KOH anisotropic etching. Results demonstrated that by altering the surface hydrophobicity, the apparent contact angle changed in accord with the Wenzel equation for surface structures with inclined side walls. Hierarchical structures were also constructed from Si pyramids where nanostructures were added by Au-assisted electroless HF/H2O2 etching. Surface hydrophobicity and superhydrophobicity were achieved by surface modification with a variety of silanes. Stability of the Cassie state of superhydrophobicity is described with respect to the Laplace pressure as indicated by the water droplet meniscus in contact with the hierarchical structures. The contact angle hysteresis observed is also discussed with respect to water/substrate adhesion.

  14. Recovering obliterated engraved marks on aluminium surfaces by etching technique.

    PubMed

    Baharum, Mohd Izhar Mohd; Kuppuswamy, R; Rahman, Azari Abd

    2008-05-20

    A study has been made of the characteristics of restoration of obliterated engraved marks on aluminium surfaces by etching technique. By etching different reagents on 0.61mm thick sheets of aluminium (99wt%) on which some engraved marks had been erased to different depths it was found that the reagent 60% hydrochloric acid and 40% sodium hydroxide on alternate swabbing on the surfaces was found to be the most sensitive one for these metal surfaces. This reagent was able to restore marks in the above plates erased down to 0.04mm below the bottom of the engraving. The marks also presented excellent contrast with the background. This reagent was further experimented with similar aluminium surfaces, but of relatively greater thickness of 1.5mm. It was noticed that the recovery depth increased slightly to 0.06mm; this suggested the dependence of recovery depth on the thickness of the sheet metal. Further, the depth of restoration decreased in cases where the original number was erased and over which a new number was engraved; the latter results are similar to those of steel surfaces reported earlier [M.A.M. Zaili, R. Kuppuswamy, H. Harun, Restoration of engraved marks on steel surfaces by etching technique, Forensic Sci. Int. 171 (2007) 27-32].

  15. Fabrication of tapered single mode fiber by chemical etching and used as a chemical sensor based on evanescent field absorption

    NASA Astrophysics Data System (ADS)

    Gangopadhyay, Tarun K.; Halder, A.; Das, S.; Paul, M. C.; Pal, M.; Salza, M.; Gagliardi, G.

    2010-12-01

    Single mode tapered fiber (SMTF) has been fabricated with core diameter of 8 μm and reduced cladding diameter up to 11 μm by hydrofluoric acid (HF) etching technique. To obtain the required cladding diameter, the time of etching has been optimized by using different HF concentrations. The mechanism as well as kinetics path of etching reaction on standard optical fiber is discussed. This study is related to surface catalyzed dissociation of HF followed by direct reaction with adsorbate molecules and the surface silicon oxide molecules. The etched tapered fibers are then packaged on quartz substrate to use as sensor element. Finally, the etched fiber is used as an element within chemical sensor based on evanescent field absorption. In this experiment, a 419-ppm cobalt nitrate solution is used for sensing.

  16. Effects of texturization due to chemical etching and laser on the optical properties of multicrystalline silicon for applications in solar cells

    NASA Astrophysics Data System (ADS)

    Vera, D.; Mass, J.; Manotas, M.; Cabanzo, R.; Mejia, E.

    2016-02-01

    In this work we carried out the texturization of surfaces of multicrystalline silicon type-p in order to decrease the reflection of light on the surface, using the chemical etching method and then a treatment with laser. In the first method, it was immersed in solutions of HF:HNO3:H2O, HF:HNO3:CH3COOH, HF:HNO3:H3PO4, in the proportion 14:01:05, during 30 seconds, 1, 2 and 3 minutes. Subsequently with a laser (ND:YAG) grids were generated beginning with parallel lines separated 50μm. The samples were analyzed by means of diffuse spectroscopy (UV-VIS) and scanning electron micrograph (SEM) before and after the laser treatment. The lowest result of reflectance obtained by HF:HNO3:H2O during 30 seconds, was of 15.5%. However, after applying the treatment with laser the reflectance increased to 17.27%. On the other hand, the samples treated (30 seconds) with acetic acid and phosphoric acid as diluents gives as a result a decrease in the reflectance values after applying the laser treatment from 21.97% to 17.79% and from 27.73% to 20.03% respectively. The above indicates that in some cases it is possible to decrease the reflectance using jointly the method of chemical etching and then a laser treatment.

  17. Case Report: Valproic Acid and Risperidone Treatment Leading to Development of Hyperammonemia and Mania

    ERIC Educational Resources Information Center

    Carlson, Teri; Reynolds, Charles A.; Caplan, Rochelle

    2007-01-01

    This case report describes two children who developed hyperammonemia together with frank manic behavior during treatment with a combination of valproic acid and risperidone. One child had been maintained on valproic acid for years and risperidone was added. In the second case, valproic acid was introduced to a child who had been treated with…

  18. Etch proximity correction through machine-learning-driven etch bias model

    NASA Astrophysics Data System (ADS)

    Shim, Seongbo; Shin, Youngsoo

    2016-03-01

    Accurate prediction of etch bias has become more important as technology node shrinks. A simulation is not feasible solution in full chip level due to excessive runtime, so etch proximity correction (EPC) often relies on empirically obtained rules or models. However, simple rules alone cannot accurately correct various pattern shapes, and a few empirical parameters in model-based EPC is still not enough to achieve satisfactory OCV. We propose a new approach of etch bias modeling through machine learning (ML) technique. A segment of interest (and its surroundings) are characterized by some geometric and optical parameters, which are received by an artificial neural network (ANN), which then outputs predicted etch bias of the segment. The ANN is used as our etch bias model for new EPC, which we propose in this paper. The new etch bias model and EPC are implemented in commercial OPC tool and demonstrated using 20nm technology DRAM gate layer.

  19. Carrier-lifetime-controlled selective etching process for semiconductors using photochemical etching

    DOEpatents

    Ashby, Carol I. H.; Myers, David R.

    1992-01-01

    The minority carrier lifetime is significantly much shorter in semiconductor materials with very high impurity concentrations than it is in semiconductor materials with lower impurity concentration levels. This phenomenon of reduced minority carrier lifetime in semiconductor materials having high impurity concentration is utilized to advantage for permitting highly selective semiconductor material etching to be achieved using a carrier-driven photochemical etching reaction. Various means may be employed for increasing the local impurity concentration level in specific near-surface regions of a semiconductor prior to subjecting the semiconductor material to a carrier-driven photochemical etching reaction. The regions having the localized increased impurity concentration form a self-aligned mask inhibiting photochemical etching at such localized regions while the adjacent regions not having increased impurity concentrations are selectively photochemically etched. Liquid- or gas-phase etching may be performed.

  20. Treatment and prevention systems for acid mine drainage and halogenated contaminants

    DOEpatents

    Jin, Song [Fort Collins, CO; Fallgren, Paul H [Laramie, WY; Morris, Jeffrey M [Laramie, WY

    2012-01-31

    Embodiments include treatments for acid mine drainage generation sources (10 perhaps by injection of at least one substrate (11) and biologically constructing a protective biofilm (13) on acid mine drainage generation source materials (14). Further embodiments include treatments for degradation of contaminated water environments (17) with substrates such as returned milk and the like.

  1. Damaged silicon contact layer removal using atomic layer etching for deep-nanoscale semiconductor devices

    SciTech Connect

    Kim, Jong Kyu; Cho, Sung Il; Lee, Sung Ho; Kim, Chan Kyu; Min, Kyung Suk; Kang, Seung Hyun; Yeom, Geun Young

    2013-11-15

    Silicon atomic layer etching (ALET) using Cl{sub 2} is applied to remove the damaged layer on a 30 nm contact silicon surface formed by high-energy reactive ions during high aspect ratio contact etching, and its effects on the damage removal characteristics are investigated. Compared to a conventional damage removal method, such as the low-power CF{sub 4} plasma treatment technique, ALET produces less secondary damage to the substrate and gives exact etch depth control and extremely high etch selectivity to the contact SiO{sub 2} insulating pattern mold. When ALET is applied after a conventional damage removal technique, the sheet resistance of the damaged contact silicon surface is improved to a level close to that of a clean silicon surface, while exact atomic-scale depth control is maintained without changes in the pattern mold profile.

  2. Freeze fracture and freeze etching.

    PubMed

    Chandler, Douglas E; Sharp, William P

    2014-01-01

    Freeze fracture depends on the property of frozen tissues or cells, when cracked open, to split along the hydrophobic interior of membranes, thus revealing broad panoramas of membrane interior. These large panoramas reveal the three-dimensional contours of membranes making the methods well suited to studying changes in membrane architecture. Freshly split membrane faces are visualized by platinum or tungsten shadowing and carbon backing to form a replica that is then cleaned of tissue and imaged by TEM. Etching, i.e., removal of ice from the frozen fractured specimen by sublimation prior to shadowing, can also reveal the true surfaces of the membrane as well as the extracellular matrix and cytoskeletal networks that contact the membranes. Since the resolution of detail in the metal replicas formed is 1-2 nm, these methods can also be used to visualize macromolecules or macromolecular assemblies either in situ or displayed on a mica surface. These methods are available for either specimens that have been chemically fixed or specimens that have been rapidly frozen without chemical intervention.

  3. Ascorbic acid supplementation does not improve efficacy of meso-dimercaptosuccinic acid treatment in lead-exposed suckling rats.

    PubMed

    Varnai, Veda Marija; Piasek, Martina; Blanusa, Maja; Juresa, Dijana; Sarić, Marija; Kostial, Krista

    2003-10-01

    It was suggested that ascorbic acid as a natural chelating agent can influence lead toxicokinetics and improve chelating properties of dimercaptosuccinic acid (DMSA) in adult rats. In this paper potential benefits of ascorbic acid supplementation, alone or combined with DMSA, in decreasing lead retention in suckling rats were evaluated. Such data in young mammals are not available. L-Ascorbic acid (daily dose 650 mg/kg b.wt.) and/or DMSA (daily dose 91 mg/kg b.wt.) were administered orally to suckling Wistar rats either during ongoing 8-day oral lead exposure (as acetate; daily dose 2 mg lead/kg b.wt.) or after 3-day lead exposure (total dose 12 mg lead/kg b.wt.). Lead concentrations were analysed in the carcass (skeleton), liver, kidneys and brain by atomic absorption spectrometry. By ascorbic acid supplementation lead retention was not reduced under either lead exposure condition. Lead concentration was even increased in the carcass. Treatment with DMSA under both exposure conditions significantly reduced lead in all analysed tissues. Combined treatment with ascorbic acid and DMSA during ongoing lead exposure was substantially less effective than DMSA treatment alone, and did not affect DMSA efficacy when administered after lead exposure. It was concluded that ascorbic acid administered either during or after lead exposure in suckling rats has no beneficial effect on either lead retention or DMSA chelation effectiveness.

  4. Essential fatty acids in the treatment of dry eye syndrome: A myth or reality?

    PubMed Central

    Al Mahmood, Ammar M.; Al-Swailem, Samar A.

    2014-01-01

    Dry eye is a common condition that can severely impair the quality of life. Systemic and topical omega-3 fatty acids and omega-6 fatty acids have been used as treatment for patients with dry eye disease and showed promising results. Further multicenter randomized controlled trials are required in order to establish a standardized protocol for the treatment of dry eye syndrome with those essential fatty acids. PMID:25278796

  5. Metal assisted anodic etching of silicon

    NASA Astrophysics Data System (ADS)

    Lai, Chang Quan; Zheng, Wen; Choi, W. K.; Thompson, Carl V.

    2015-06-01

    Metal assisted anodic etching (MAAE) of Si in HF, without H2O2, is demonstrated. Si wafers were coated with Au films, and the Au films were patterned with an array of holes. A Pt mesh was used as the cathode while the anodic contact was made through either the patterned Au film or the back side of the Si wafer. Experiments were carried out on P-type, N-type, P+-type and N+-type Si wafers and a wide range of nanostructure morphologies were observed, including solid Si nanowires, porous Si nanowires, a porous Si layer without Si nanowires, and porous Si nanowires on a thick porous Si layer. Formation of wires was the result of selective etching at the Au-Si interface. It was found that when the anodic contact was made through P-type or P+-type Si, regular anodic etching due to electronic hole injection leads to formation of porous silicon simultaneously with metal assisted anodic etching. When the anodic contact was made through N-type or N+-type Si, generation of electronic holes through processes such as impact ionization and tunnelling-assisted surface generation were required for etching. In addition, it was found that metal assisted anodic etching of Si with the anodic contact made through the patterned Au film essentially reproduces the phenomenology of metal assisted chemical etching (MACE), in which holes are generated through metal assisted reduction of H2O2 rather than current flow. These results clarify the linked roles of electrical and chemical processes that occur during electrochemical etching of Si.Metal assisted anodic etching (MAAE) of Si in HF, without H2O2, is demonstrated. Si wafers were coated with Au films, and the Au films were patterned with an array of holes. A Pt mesh was used as the cathode while the anodic contact was made through either the patterned Au film or the back side of the Si wafer. Experiments were carried out on P-type, N-type, P+-type and N+-type Si wafers and a wide range of nanostructure morphologies were observed

  6. Black Germanium fabricated by reactive ion etching

    NASA Astrophysics Data System (ADS)

    Steglich, Martin; Käsebier, Thomas; Kley, Ernst-Bernhard; Tünnermann, Andreas

    2016-09-01

    A reactive ion etching technique for the preparation of statistical "Black Germanium" antireflection surfaces, relying on self-organization in a Cl2 etch chemistry, is presented. The morphology of the fabricated Black Germanium surfaces is the result of a random lateral distribution of pyramidal etch pits with heights around (1450 ± 150) nm and sidewall angles between 80° and 85°. The pyramids' base edges are oriented along the <110> crystal directions of Germanium, indicating a crystal anisotropy of the etching process. In the Vis-NIR, the tapered Black Germanium surface structure suppresses interface reflection to <2.5 % for normal incidence and still to <6 % at an angle of incidence of 70°. The presented Black Germanium might find applications as low-cost AR structure in optoelectronics and IR optics.

  7. Epoxy bond and stop etch fabrication method

    DOEpatents

    Simmons, Jerry A.; Weckwerth, Mark V.; Baca, Wes E.

    2000-01-01

    A class of epoxy bond and stop etch (EBASE) microelectronic fabrication techniques is disclosed. The essence of such techniques is to grow circuit components on top of a stop etch layer grown on a first substrate. The first substrate and a host substrate are then bonded together so that the circuit components are attached to the host substrate by the bonding agent. The first substrate is then removed, e.g., by a chemical or physical etching process to which the stop etch layer is resistant. EBASE fabrication methods allow access to regions of a device structure which are usually blocked by the presence of a substrate, and are of particular utility in the fabrication of ultrafast electronic and optoelectronic devices and circuits.

  8. Semiconductor structure and recess formation etch technique

    DOEpatents

    Lu, Bin; Sun, Min; Palacios, Tomas Apostol

    2017-02-14

    A semiconductor structure has a first layer that includes a first semiconductor material and a second layer that includes a second semiconductor material. The first semiconductor material is selectively etchable over the second semiconductor material using a first etching process. The first layer is disposed over the second layer. A recess is disposed at least in the first layer. Also described is a method of forming a semiconductor structure that includes a recess. The method includes etching a region in a first layer using a first etching process. The first layer includes a first semiconductor material. The first etching process stops at a second layer beneath the first layer. The second layer includes a second semiconductor material.

  9. Influence of the LED curing source and selective enamel etching on dentin bond strength of self-etch adhesives in class I composite restorations.

    PubMed

    Souza-Junior, Eduardo José; Araújo, Cíntia Tereza Pimenta; Prieto, Lúcia Trazzi; Paulillo, Luís Alexandre Maffei Sartini

    2012-11-01

    The aim of this study was to evaluate the influence of the LED curing unit and selective enamel etching on dentin microtensile bond strength (μTBS) for self-etch adhesives in class I composite restorations. On 96 human molars, box-shaped class I cavities were made maintaining enamel margins. Self-etch adhesives (Clearfil SE - CSE and Clearfil S(3) - S3) were used to bond a microhybrid composite. Before adhesive application, half of the teeth were enamel acid-etched and the other half was not. Adhesives and composites were cured with the following light curing units (LCUs): one polywave (UltraLume 5 - UL) and two single-peak (FlashLite 1401 - FL and Radii Cal - RD) LEDs. The specimens were then submitted to thermomechanical aging and longitudinally sectioned to obtain bonded sticks (0.9 mm(2)) to be tested in tension at 0.5 mm/min. The failure mode was then recorded. The μTBS data were submitted to a three-way ANOVA and Tukey's (α = 0.05). For S3, the selective enamel-etching provided lower μTBS values (20.7 ± 2.7) compared to the non-etched specimens (26.7 ± 2.2). UL yielded higher μTBS values (24.1 ± 3.2) in comparison to the photoactivation approach with FL (18.8 ±3.9) and RD (19.9 ±1.8) for CSE. The two-step CSE was not influenced by the enamel etching (p ≥ 0.05). Enamel acid etching in class I composite restorations affects the dentin μTBS of the one-step self-etch adhesive Clearfil S(3), with no alterations for Clearfil SE bond strength. The polywave LED promoted better bond strength for the two-step adhesive compared to the single-peak ones.

  10. Influence of Etching Mode on Enamel Bond Durability of Universal Adhesive Systems.

    PubMed

    Suzuki, T; Takamizawa, T; Barkmeier, W W; Tsujimoto, A; Endo, H; Erickson, R L; Latta, M A; Miyazaki, M

    2016-01-01

    The purpose of this study was to determine the enamel bond durability of three universal adhesives in different etching modes through fatigue testing. The three universal adhesives used were Scotchbond Universal, Prime&Bond Elect universal dental adhesive, and All-Bond Universal light-cured dental adhesive. A single-step self-etch adhesive, Clearfil S(3) Bond Plus was used as a control. The shear bond strength (SBS) and shear fatigue strength (SFS) to human enamel were evaluated in total-etch mode and self-etch mode. A stainless steel metal ring with an internal diameter of 2.4 mm was used to bond the resin composite to the flat-ground (4000-grit) tooth surfaces for determination of both SBS and SFS. For each enamel surface treatment, 15 specimens were prepared for SBS and 30 specimens for SFS. The staircase method for fatigue testing was then used to determine the SFS of the resin composite bonded to the enamel using 10-Hz frequencies for 50,000 cycles or until failure occurred. Scanning electron microscopy was used to observe representative debonded specimen surfaces and the resin-enamel interfaces. A two-way analysis of variance and the Tukey post hoc test were used for analysis of the SBS data, whereas a modified t-test with Bonferroni correction was used for the SFS data. All adhesives in total-etch mode showed significantly higher SBS and SFS values than those in self-etch mode. Although All-Bond Universal in self-etch mode showed a significantly lower SBS value than the other adhesives, there was no significant difference in SFS values among the adhesives in this mode. All adhesives showed higher SFS:SBS ratios in total-etch mode than in self-etch mode. With regard to the adhesive systems used in this study, universal adhesives showed higher enamel bond strengths in total-etch mode. Although the influence of different etching modes on the enamel-bonding performance of universal adhesives was found to be dependent on the adhesive material, total-etch mode

  11. Preferential Treatment: Interaction Between Amino Acids and Minerals

    NASA Astrophysics Data System (ADS)

    Crapster-Pregont, E. J.; Cleaves, H. J.; Hazen, R. M.

    2008-12-01

    Amino acids are the building blocks of proteins and are important for some models of the origin of life. Polymerization of amino acids from dilute solution is unlikely without a scaffold or catalyst. The surfaces of early Earth minerals are the most likely candidates for this role. The surface adsorption behavior of 12 amino acids (L-alanine, L-serine, L-aspartic acid, L-proline, L- phenylalanine, L-valine, L-arginine, d-amino valeric acid, glycine, L-lysine, L-isoleucine, and B-alanine) on 21 minerals (quartz, calcite, enstatite, illite, olivine, pyrrhotite, pyrite, alkali basalt, albite, analcime, chlorite, barite, hydroxyl apatite, hematite, magnetite, aluminum hydroxide, kaolin, silica gel, corundum, rutile, and montmorillonite) was determined via batch adsorption experiments. Absorption was determined for concentrations between 10-4M and 10-6M in the presence of 0.1M NaCl, and between pH values of 3 and 9 at 25 degrees C. The equilibrated solutions were centrifuged, filtered, derivatized using a fluorescent amino group tag (dansyl-chloride) and analyzed by HPLC. Adsorption was standardized using BET surface area measurements for each mineral to give the number of mols of each amino acid adsorbed per square meter for each mineral. The results indicate an enormous difference in the adsorption of amino acids between minerals, along with major differences in the adsorption of individual amino acids on the same mineral surface. There is also a change in the absorbance of amino acids as the pH changes. Many previous studies of amino acid concentration and catalysis by minerals have used clay minerals because of their high surface areas, however, this data suggests that the surfaces of minerals such as calcite, quartz and pyrite have even higher affinities for amino acids. The results suggest mineral surfaces that could be optimal locations for the polymerization of molecules linked to the origin of life.

  12. Effect of etching time and light source on the bond strength of metallic brackets to ceramic.

    PubMed

    Gonçalves, Paulo Roberto Amaral; Moraes, Rafael Ratto de; Costa, Ana Rosa; Correr, Américo Bortolazzo; Nouer, Paulo Roberto Aranha; Sinhoreti, Mário Alexandre Coelho; Correr-Sobrinho, Lourenço

    2011-01-01

    This study evaluated the bond strength of brackets to ceramic testing different etching times and light sources for photo-activation of the bonding agent. Cylinders of feldspathic ceramic were etched with 10% hydrofluoric acid for 20 or 60 s. After application of silane on the ceramic surface, metallic brackets were bonded to the cylinders using Transbond XT (3M Unitek). The specimens for each etching time were assigned to 4 groups (n=15), according to the light source: XL2500 halogen light, UltraLume 5 LED, AccuCure 3000 argon laser, and Apollo 95E plasma arc. Light-activation was carried out with total exposure times of 40, 40, 20 and 12 s, respectively. Shear strength testing was carried out after 24 h. The adhesive remnant index (ARI) was evaluated under magnification. Data were subjected to two-way ANOVA and Tukey's test (α=0.05). Specimens etched for 20 s presented significantly lower bond strength (p<0.05) compared with those etched for 60 s. No significant differences (p>0.05) were detected among the light sources. The ARI showed a predominance of scores 0 in all groups, with an increase in scores 1, 2 and 3 for the 60 s time. In conclusion, only the etching time had significant influence on the bond strength of brackets to ceramic.

  13. Method for anisotropic etching in the manufacture of semiconductor devices

    DOEpatents

    Koontz, Steven L.; Cross, Jon B.

    1993-01-01

    Hydrocarbon polymer coatings used in microelectronic manufacturing processes are anisotropically etched by atomic oxygen beams (translational energies of 0.2-20 eV, preferably 1-10 eV). Etching with hyperthermal (kinetic energy>1 eV) oxygen atom species obtains highly anisotropic etching with sharp boundaries between etched and mask-protected areas.

  14. Method for anisotropic etching in the manufacture of semiconductor devices

    NASA Technical Reports Server (NTRS)

    Koontz, Steven L. (Inventor); Cross, Jon B. (Inventor)

    1993-01-01

    Hydrocarbon polymer coatings used in microelectronic manufacturing processes are anisotropically etched by hyperthermal atomic oxygen beams (translational energies of 0.2 to 20 eV, preferably 1 to 10 eV). Etching with hyperthermal oxygen atom species obtains highly anisotropic etching with sharp boundaries between etched and mask protected areas.

  15. Metal assisted anodic etching of silicon.

    PubMed

    Lai, Chang Quan; Zheng, Wen; Choi, W K; Thompson, Carl V

    2015-07-07

    Metal assisted anodic etching (MAAE) of Si in HF, without H2O2, is demonstrated. Si wafers were coated with Au films, and the Au films were patterned with an array of holes. A Pt mesh was used as the cathode while the anodic contact was made through either the patterned Au film or the back side of the Si wafer. Experiments were carried out on P-type, N-type, P(+)-type and N(+)-type Si wafers and a wide range of nanostructure morphologies were observed, including solid Si nanowires, porous Si nanowires, a porous Si layer without Si nanowires, and porous Si nanowires on a thick porous Si layer. Formation of wires was the result of selective etching at the Au-Si interface. It was found that when the anodic contact was made through P-type or P(+)-type Si, regular anodic etching due to electronic hole injection leads to formation of porous silicon simultaneously with metal assisted anodic etching. When the anodic contact was made through N-type or N(+)-type Si, generation of electronic holes through processes such as impact ionization and tunnelling-assisted surface generation were required for etching. In addition, it was found that metal assisted anodic etching of Si with the anodic contact made through the patterned Au film essentially reproduces the phenomenology of metal assisted chemical etching (MACE), in which holes are generated through metal assisted reduction of H2O2 rather than current flow. These results clarify the linked roles of electrical and chemical processes that occur during electrochemical etching of Si.

  16. Plasma/Neutral-Beam Etching Apparatus

    NASA Technical Reports Server (NTRS)

    Langer, William; Cohen, Samuel; Cuthbertson, John; Manos, Dennis; Motley, Robert

    1989-01-01

    Energies of neutral particles controllable. Apparatus developed to produce intense beams of reactant atoms for simulating low-Earth-orbit oxygen erosion, for studying beam-gas collisions, and for etching semiconductor substrates. Neutral beam formed by neutralization and reflection of accelerated plasma on metal plate. Plasma ejected from coaxial plasma gun toward neutralizing plate, where turned into beam of atoms or molecules and aimed at substrate to be etched.

  17. Dislocation Etching Solutions for Mercury Cadmium Selenide

    DTIC Science & Technology

    2014-09-01

    Dislocation Etching Solutions for Mercury Cadmium Selenide by Kevin Doyle and Sudhir Trivedi ARL-CR-0744 September 2014...Etching Solutions for Mercury Cadmium Selenide Kevin Doyle and Sudhir Trivedi Sensors and Electron Devices Directorate, ARL prepared by...Solutions for Mercury Cadmium Selenide 5a. CONTRACT NUMBER W811NF-12-2-0019 5b. GRANT NUMBER 5c. PROGRAM ELEMENT NUMBER 6. AUTHOR(S) Kevin Doyle and

  18. Treatment of Irradiated Mice with High-Dose Ascorbic Acid Reduced Lethality

    PubMed Central

    Sato, Tomohito; Kinoshita, Manabu; Yamamoto, Tetsuo; Ito, Masataka; Nishida, Takafumi; Takeuchi, Masaru; Saitoh, Daizoh; Seki, Shuhji; Mukai, Yasuo

    2015-01-01

    Ascorbic acid is an effective antioxidant and free radical scavenger. Therefore, it is expected that ascorbic acid should act as a radioprotectant. We investigated the effects of post-radiation treatment with ascorbic acid on mouse survival. Mice received whole body irradiation (WBI) followed by intraperitoneal administration of ascorbic acid. Administration of 3 g/kg of ascorbic acid immediately after exposure significantly increased mouse survival after WBI at 7 to 8 Gy. However, administration of less than 3 g/kg of ascorbic acid was ineffective, and 4 or more g/kg was harmful to the mice. Post-exposure treatment with 3 g/kg of ascorbic acid reduced radiation-induced apoptosis in bone marrow cells and restored hematopoietic function. Treatment with ascorbic acid (3 g/kg) up to 24 h (1, 6, 12, or 24 h) after WBI at 7.5 Gy effectively improved mouse survival; however, treatments beyond 36 h were ineffective. Two treatments with ascorbic acid (1.5 g/kg × 2, immediately and 24 h after radiation, 3 g/kg in total) also improved mouse survival after WBI at 7.5 Gy, accompanied with suppression of radiation-induced free radical metabolites. In conclusion, administration of high-dose ascorbic acid might reduce radiation lethality in mice even after exposure. PMID:25651298

  19. PASSIVE TREATMENT OF ACID ROCK DRAINAGE FROM A SUBSURFACE MINE

    EPA Science Inventory

    Acidic, metal-contaminated drainages are a critical problem facing many areas of the world. Acid rock drainage results when metal sulfide minerals, particularly pyrite, are oxidized by exposure to oxygen and water. The deleterious effects of these drainages on receiving streams a...

  20. Emergency esophagogastrectomy for treatment of hydrochloric acid injury.

    PubMed

    Horváth, O P; Oláh, T; Zentai, G

    1991-07-01

    Eight patients with severe hydrochloric acid injury of the esophagus and stomach had early esophagogastrectomy. Four patients survived and 6 to 8 weeks later underwent successful substernal colon replacement. The value of early diagnosis and subsequent aggressive surgical management of patients who have ingested hydrochloric acid is stressed.

  1. Back-etch method for plan view transmission electron microscopy sample preparation of optically opaque films.

    PubMed

    Yao, Bo; Coffey, Kevin R

    2008-04-01

    Back-etch methods have been widely used to prepare plan view transmission electron microscopy (TEM) samples of thin films on membranes by removal of the Si substrate below the membrane by backside etching. The conventional means to determine when to stop the etch process is to observe the color of the light transmitted through the sample, which is sensitive to the remaining Si thickness. However, most metallic films thicker than 75 nm are opaque, and there is no detectable color change prior to film perforation. In this paper, a back-etch method based on the observation of an abrupt change of optical reflection contrast is introduced as a means to determine the etch endpoint to prepare TEM samples for these films. As the acid etchant removes the Si substrate material a rough interface is generated. This interface becomes a relatively smooth and featureless region when the etchant reaches the membrane (film/SiO2). This featureless region is caused by the mirror reflection of the film plane (film/SiO2 interface) through the optically transparent SiO2 layer. The lower etch rate of SiO2 (compared with Si) gives the operator enough time to stop the etching without perforating the film. A clear view of the morphology and control of Si roughness during etching are critical to this method, which are discussed in detail. The procedures of mounting wax removal and sample rinsing are also described in detail, as during these steps damage to the membrane may easily occur without appropriate consideration. As examples, the preparation of 100-nm-thick Fe-based amorphous alloy thin film and 160-nm-thick Cu-thin film samples for TEM imaging is described.

  2. Investigation of Nitride Morphology After Self-Aligned Contact Etch

    NASA Technical Reports Server (NTRS)

    Hwang, Helen H.; Keil, J.; Helmer, B. A.; Chien, T.; Gopaladasu, P.; Kim, J.; Shon, J.; Biegel, Bryan (Technical Monitor)

    2001-01-01

    Self-Aligned Contact (SAC) etch has emerged as a key enabling technology for the fabrication of very large-scale memory devices. However, this is also a very challenging technology to implement from an etch viewpoint. The issues that arise range from poor oxide etch selectivity to nitride to problems with post etch nitride surface morphology. Unfortunately, the mechanisms that drive nitride loss and surface behavior remain poorly understood. Using a simple langmuir site balance model, SAC nitride etch simulations have been performed and compared to actual etched results. This approach permits the study of various etch mechanisms that may play a role in determining nitride loss and surface morphology. Particle trajectories and fluxes are computed using Monte-Carlo techniques and initial data obtained from double Langmuir probe measurements. Etched surface advancement is implemented using a shock tracking algorithm. Sticking coefficients and etch yields are adjusted to obtain the best agreement between actual etched results and simulated profiles.

  3. Wet-etching of precipitation-based thin film microstructures for micro-solid oxide fuel cells

    NASA Astrophysics Data System (ADS)

    Rupp, Jennifer L. M.; Muecke, Ulrich P.; Nalam, Prathima C.; Gauckler, Ludwig J.

    In micro-solid oxide fuel cells (μ-SOFCs) ceramic thin films are integrated as free-standing membranes on micromachinable substrates such as silicon or Foturan ® glass ceramic wafers. The processing of μ-SOFCs involves unavoidable dry- or wet-chemical etching for opening the substrate below the free-standing fuel cell membranes. In the first part of this paper current dry- and wet-chemical etchants for structuring of ceria-based electrolyte materials are reviewed, and compared to the etch-rates of common μ-SOFCs substrates. Wet-chemical etchants such as hydrofluoric acid are of high interest in μ-SOFC processing since they allow for homogeneous etching of ceria-based electrolyte thin films contrary to common dry-etching methods. In addition, HF acid is the only choice for substrate etching of μ-SOFC based on Foturan ® glass ceramic wafers. Etching of Ce 0.8Gd 0.2O 1.9- x spray pyrolysis electrolyte thin films with 10% HF:H 2O is investigated. The etch-resistance and microstructures of these films show a strong dependency on post deposition annealing, i.e. degree of crystallinity, and damage for low acid exposure times. Their ability to act as a potential etch-resistance for μ-SOFC membranes is broadly discussed. Guidance for thermal annealing and etching of Ce 0.8Gd 0.2O 1.9- x thin films for the fabrication of Foturan ®-based μ-SOFCs is given.

  4. Gate modulation of anodically etched gallium arsenide nanowire random network

    NASA Astrophysics Data System (ADS)

    Aikawa, Shinya; Yamada, Kohei; Asoh, Hidetaka; Ono, Sachiko

    2016-06-01

    Gallium arsenide nanowires (GaAs NWs) formed by anodic etching show an electrically semi-insulating behavior because of charge carrier depletion caused by high interface state density. Here, we demonstrate the gate modulation of an anodically etched GaAs NW random network. By applying a reverse bias voltage after anodic etching of bulk GaAs, hydrogen ion exposure of the depleted NW region occurs, and then the interface state density is possibly decreased owing to the reduction in the amount of excess As generated at the interface between the amorphous Ga2O3 and GaAs layers. Consequently, the drain current of the thin-film transistor (TFT) with the GaAs NW random network was increased and was changed by the gate voltage. In contrast, the random network film remained in the insulator in the absence of reverse electrolysis treatment. The TFT performance is still insufficient but may be improved by optimizing the hydrogen ion exposure conditions.

  5. Preparation of low-molecular-weight hyaluronic acid by ozone treatment.

    PubMed

    Wu, Yue

    2012-06-20

    Recently, low-molecular-weight hyaluronic acid has been reported to have novel features, such as free radical scavenging activities, antioxidant activities, promotion of excisional wound healing, etc. In the present work, degradation of native hyaluronic acid by ozone treatment was performed for preparation of low-molecular-weight hyaluronic acid. The molecular weight of native hyaluronic acid was reduced from 1535 to 87 kDa for 120 min at 40°C. The rate of reduction of molecular weight was 94.33%. The FT-IR, 13C NMR, and UV-vis spectra suggested that there was no obvious modification of chemical structure of low-molecular-weight hyaluronic acid. The use of degradation of native hyaluronic acid by ozone treatment can be a useful alternative for production of low-molecular-weight hyaluronic acid.

  6. Effect of Cl{sub 2}- and HBr-based inductively coupled plasma etching on InP surface composition analyzed using in situ x-ray photoelectron spectroscopy

    SciTech Connect

    Bouchoule, S.; Vallier, L.; Patriarche, G.; Chevolleau, T.; Cardinaud, C.

    2012-05-15

    A Cl{sub 2}-HBr-O{sub 2}/Ar inductively coupled plasma (ICP) etching process has been adapted for the processing of InP-based heterostructures in a 300-mm diameter CMOS etching tool. Smooth and anisotropic InP etching is obtained at moderate etch rate ({approx}600 nm/min). Ex situ x-ray energy dispersive analysis of the etched sidewalls shows that the etching anisotropy is obtained through a SiO{sub x} passivation mechanism. The stoichiometry of the etched surface is analyzed in situ using angle-resolved x-ray photoelectron spectroscopy. It is observed that Cl{sub 2}-based ICP etching results in a significantly P-rich surface. The phosphorous layer identified on the top surface is estimated to be {approx}1-1.3-nm thick. On the other hand InP etching in HBr/Ar plasma results in a more stoichiometric surface. In contrast to the etched sidewalls, the etched surface is free from oxides with negligible traces of silicon. Exposure to ambient air of the samples submitted to Cl{sub 2}-based chemistry results in the complete oxidation of the P-rich top layer. It is concluded that a post-etch treatment or a pure HBr plasma step may be necessary after Cl{sub 2}-based ICP etching for the recovery of the InP material.

  7. Chemically Etched Open Tubular and Monolithic Emitters for Nanoelectrospray Ionization Mass Spectrometry

    SciTech Connect

    Kelly, Ryan T.; Page, Jason S.; Luo, Quanzhou; Moore, Ronald J.; Orton, Daniel J.; Tang, Keqi; Smith, Richard D.

    2006-11-15

    We have developed a new procedure for fabricating fused silica emitters for electrospray ionization-mass spectrometry (ESI-MS) in which the end of a bare fused silica capillary is immersed into aqueous hydrofluoric acid, and water is pumped through the capillary to prevent etching of the interior. Surface tension causes the etchant to climb the capillary exterior, and the etch rate in the resulting meniscus decreases as a function of distance from the bulk solution. Etching continues until the silica touching the hydrofluoric acid reservoir is completely removed, essentially stopping the etch process. The resulting emitters have no internal taper, making them much less prone to clogging compared to e.g. pulled emitters. The high aspect ratios and extremely thin walls at the orifice facilitate very low flow rate operation; stable ESI-MS signals were obtained for model analytes from 5-μm-diameter emitters at a flow rate of 5 nL/min with a high degree of inter-emitter reproducibility. In extensive evaluation, the etched emitters were found to enable approximately four times as many LC-MS analyses of proteomic samples before failing compared with conventional pulled emitters. The fabrication procedure was also employed to taper the ends of polymer monolith-containing silica capillaries for use as ESI emitters. In contrast to previous work, the monolithic material protrudes beyond the fused silica capillaries, improving the monolith-assisted electrospray process.

  8. Effect of post-annealing on the plasma etching of graphene-coated-copper.

    PubMed

    Hui, L S; Whiteway, E; Hilke, M; Turak, A

    2014-01-01

    High temperature deposition of graphene on Cu by chemical vapor deposition can be used to produce high quality films. However, these films tend to have a non-equilibrium structure, with relatively low graphene adhesion. In this study, samples of graphene grown on copper foils by high temperature CVD were post-deposition annealed at temperatures well below the critical temperature of Cu. Resistance to etching under plasma was examined to assess the mechanical robustness of the graphene on the Cu surface, analyzed using optical and Raman microscopies. We found a correlation between the post-annealing time and etching time for the complete removal of graphene from Cu. Etching rates, minimum etch times, and surface appearance were observed to vary depending on the etching plasma (air, oxygen or nitrogen). Oxygen plasmas were found to be the least aggressive, emphasizing the improved adhesion with post-annealing treatments. Our results imply that the etching of graphene on Cu, and hence the adhesion of graphene, can be controlled by proper annealing and choice of plasma gas.

  9. Malic acid or orthophosphoric acid-heat treatments for protecting sunflower (Helianthus annuus) meal proteins against ruminal degradation and increasing intestinal amino acid supply.

    PubMed

    Arroyo, J M; González, J; Ouarti, M; Silván, J M; Ruiz del Castillo, M L; de la Peña Moreno, F

    2013-02-01

    The protection of sunflower meal (SFM) proteins by treatments with solutions of malic acid (1 M) or orthophosphoric acid (0.67 M) and heat was studied in a 3 × 3 Latin-square design using three diets and three rumen and duodenum cannulated wethers. Acid solutions were applied to SFM at a rate of 400 ml/kg under continuous mixing. Subsequently, treated meals were dried in an oven at 150°C for 6 h. Diets (ingested at 75 g/kg BW0.75) were isoproteic and included 40% Italian ryegrass hay and 60% concentrate. The ratio of untreated to treated SFM in the concentrate was 100 : 0 in the control diet and around 40 : 60 in diets including acid-treated meals. The use of acid-treated meals did not alter either ruminal fermentation or composition of rumen contents and led to moderate reductions of the rumen outflow rates of untreated SFM particles, whereas it did not affect their comminution and mixing rate. In situ effective estimates of by-pass (BP) and its intestinal effective digestibility (IED) of dry matter (DM), CP and amino acids (AAs) were obtained considering both rates and correcting the particle microbial contamination in the rumen using 15N infusion techniques. Estimates of BP and IED decreased applying microbial correction, but these variations were low in agreement with the small contamination level. Protective treatments increased on average the BP of DM (48.5%) and CP (267%), mainly decreasing both the soluble fraction and the degradation rate but also increasing the undegradable fraction, which was higher using orthophosphoric acid. Protective treatments increased the IED of DM (108%) and CP, but this increase was lower using orthophosphoric acid (11.8%) than malic acid (20.7%). Concentrations of AA were similar among all meals, except for a reduction in lysine concentrations using malic acid (16.3%) or orthophosphoric acid (20.5%). Protective treatments also increased on average the BP of all AA, as well as the IED of most of them. Evidence of higher

  10. Solution of Azelaic Acid (20%), Resorcinol (10%) and Phytic Acid (6%) Versus Glycolic Acid (50%) Peeling Agent in the Treatment of Female Patients with Facial Melasma

    PubMed Central

    Faghihi, Gita; Taheri, Azam; Shahmoradi, Zabihollah; Nilforoushzadeh, Mohammad Ali

    2017-01-01

    Background: Melasma, a common acquired disorder of hyperpigmentation, especially in women, is often resistant to therapy. This study was aimed to evaluate the efficacy and safety of azelaic acid, resorcinol and phytic acid solution in chemical peeling of melasma in comparison to 50% glycolic acid. Materials and Methods: This clinical trial was performed, on 42 female patients with bilateral melasma. Severity of melasma was assessed by melasma area and severity index (MASI). Combination of (20% azelaic acid + 10% resorcinol + 6% phytic acid) was used as a new peeling agent on the right side of the face and 50% glycolic acid on the left side every 2 weeks for 6 times. Follow-up was carried out for 3 months after the last session. Any decrease in MASI score and unwanted complications following peeling were evaluated and compared during the trial. Results: Patients showed marked improvement as calculated with MASI score before and after treatment in both sides of the face. The efficacy of combination formula (azelaic acid, resorcinol and phytic acid) was similar to glycolic acid, but with fewer complications. There was no statistically difference in improvement between two groups (P > 0.05). However, the patient's discomfort following procedures was significantly lower with azelaic acid, resorcinol and phytic compared with the glycolic acid peels (P < 0.05) and there was the same duration in the beginning of the therapeutic response in both groups. Conclusion: Results showed that triple-combination was found to be an effective and safe peeling agent in the treatment of melasma and it was as effective as 50% glycolic acid peel. PMID:28299301

  11. Hydrothermal etching preparation and growth process of γ-MnOOH with novel hexagram morphology

    NASA Astrophysics Data System (ADS)

    Yang, Xing; Zhou, Haiyan; Lv, Jing; Kang, Liping; Lei, Zhibin; Liu, Zong-huai

    2015-04-01

    Well-defined single crystal γ-MnOOH with novel hexagram morphology was prepared by hydrothermal treating a suspension of ethyl acetate and KMnO4 at 200 °C for 48 h, and its formation process had been investigated on the basis of XRD, FESEM, TEM, HRTEM, and SAED analyses. In keeping hydrothermal treatment temperature and reaction time, ethyl acetate played an important role in controlling the crystal phase and morphology of the obtained materials, which was used as both reducing agent and etchant. It hydrolyzed into acetic acid and ethanol slowly and caused an acidic reaction environment accompanied with hydrothermal reaction. The acetic acid was adsorbed on the lateral of γ-MnOOH with multiple branched nanorods, which caused a soft etching process and the lateral of the multiple branched nanorods became sharper and thinner and finally transformed into γ-MnOOH with hexagram morphology. The prepared γ-MnOOH with novel hexagram morphology is expected to be used for a fundamental study in surface science and for potential applications such as adsorbent, electro-catalyst, sensing and so on.

  12. Omega-3 polyunsaturated fatty acids in the treatment of hypertriglyceridaemia.

    PubMed

    Pirillo, Angela; Catapano, Alberico Luigi

    2013-12-20

    Hypertriglyceridaemia (HTG) is an independent risk factor for cardiovascular disease; high-risk patients with HTG, such as those with metabolic syndrome or diabetes, may benefit from hypolipidaemic therapies. Several lipid-lowering drugs act by reducing triglyceride (TG) levels, including fibrates, nicotinic acid and omega-3 fatty acids. The omega-3 polyunsaturated fatty acids eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA) dose-dependently reduce plasma TG levels; the effect tends to be greater in patients with higher TG levels at baseline. Evidence from clinical trials suggests that EPA+DHA doses of ≥ 2 g/day are required to achieve significant effects. The optimal TG-lowering doses of EPA+DHA are 3-4 g/day, with little evidence to support lipid-altering efficacy of doses of EPA and DHA <1g/day. Predicted changes in fasting serum TG levels at the recommended dietary intakes of EPA and/or DHA of 200-500 mg/day are -3.1% to -7.2%. Reductions of plasma TG levels at the optimal doses are from 25-35% up to 45% in the presence of severely elevated TG levels (≥ 500 mg/dl; ≥ 5.65 mmol/l), along with a reduction in non-high-density lipoprotein-cholesterol (non-HDL-C) and an increase in HDL-C. This observation has also been confirmed in statin-treated patients.

  13. Asymmetrically modulating the insulator-metal transition of thermochromic VO2 films upon heating and cooling by mild surface-etching

    NASA Astrophysics Data System (ADS)

    Kang, Litao; Xie, Lingli; Chen, Zhang; Gao, Yanfeng; Liu, Xuguang; Yang, Yongzhen; Liang, Wei

    2014-08-01

    The reversible thermochromic insulator-metal transition (IMT) of VO2 is believed to start from suitable nucleating defects, but the role of specific defects during the IMT has remained elusive. In this work, we performed a simple, mild but effective acid etching treatment on pure-phase VO2 films to adjust the surface state of the VO2 particles while leaving the phase composition, crystallinity, grain size, and stoichiometry unchanged. By continuously etching VO2 particles, the poor crystallized layers on the particle surface were removed, and the particle connections became loose, resulting in significant shifts of the IMT toward higher temperatures. In stark contrast, the reversal IMT (i.e., metal-insulator transition, MIT) parameters remained relatively steady during the etching process. These experimental results correlate directly the IMT characteristics with the states (e.g., local defects, stress, and connection) of the particle surface, and further enable us to asymmetrically modulate the IMT parameters, while keeping the MIT (i.e., metal-insulator transition, the reversal of IMT) almost constant. This work illustrates the potential for particle surface engineering in thermochromic VO2 films.

  14. Salicylic Acid Induction of Flavonoid Biosynthesis Pathways in Wheat Varies by Treatment

    PubMed Central

    Gondor, Orsolya K.; Janda, Tibor; Soós, Vilmos; Pál, Magda; Majláth, Imre; Adak, Malay K.; Balázs, Ervin; Szalai, Gabriella

    2016-01-01

    Salicylic acid is a promising compound for the reduction of stress sensitivity in plants. Although several biochemical and physiological changes have been described in plants treated with salicylic acid, the mode of action of the various treatments has not yet been clarified. The present work reports a detailed comparative study on the effects of different modes of salicylic acid application at the physiological, metabolomic, and transcriptomic levels. Seed soaking and hydroponic treatments were found to induce various changes in the protective mechanisms of wheat plants. The possible involvement of the flavonoid metabolism in salicylic acid-related stress signaling was also demonstrated. Different salicylic acid treatments were shown to induce different physiological and biochemical processes, with varying responses in the leaves and roots. Hydroponic treatment enhanced the level of oxidative stress, the expression of genes involved in the flavonoid metabolism and the amount of non-enzymatic antioxidant compounds, namely ortho-hydroxycinnamic acid and the flavonol quercetin in the leaves, while it decreased the ortho-hydroxycinnamic acid and flavonol contents and enhanced ascorbate peroxidase activity in the roots. In contrast, seed soaking only elevated the gene expression level of phenylalanine ammonia lyase in the roots and caused a slight increase in the amount of flavonols. These results draw attention to the fact that the effects of exogenous salicylic acid application cannot be generalized in different experimental systems and that the flavonoid metabolism may be an important part of the action mechanisms induced by salicylic acid. PMID:27733857

  15. Salicylic Acid Induction of Flavonoid Biosynthesis Pathways in Wheat Varies by Treatment.

    PubMed

    Gondor, Orsolya K; Janda, Tibor; Soós, Vilmos; Pál, Magda; Majláth, Imre; Adak, Malay K; Balázs, Ervin; Szalai, Gabriella

    2016-01-01

    Salicylic acid is a promising compound for the reduction of stress sensitivity in plants. Although several biochemical and physiological changes have been described in plants treated with salicylic acid, the mode of action of the various treatments has not yet been clarified. The present work reports a detailed comparative study on the effects of different modes of salicylic acid application at the physiological, metabolomic, and transcriptomic levels. Seed soaking and hydroponic treatments were found to induce various changes in the protective mechanisms of wheat plants. The possible involvement of the flavonoid metabolism in salicylic acid-related stress signaling was also demonstrated. Different salicylic acid treatments were shown to induce different physiological and biochemical processes, with varying responses in the leaves and roots. Hydroponic treatment enhanced the level of oxidative stress, the expression of genes involved in the flavonoid metabolism and the amount of non-enzymatic antioxidant compounds, namely ortho-hydroxycinnamic acid and the flavonol quercetin in the leaves, while it decreased the ortho-hydroxycinnamic acid and flavonol contents and enhanced ascorbate peroxidase activity in the roots. In contrast, seed soaking only elevated the gene expression level of phenylalanine ammonia lyase in the roots and caused a slight increase in the amount of flavonols. These results draw attention to the fact that the effects of exogenous salicylic acid application cannot be generalized in different experimental systems and that the flavonoid metabolism may be an important part of the action mechanisms induced by salicylic acid.

  16. Acid pre-treatment method for in situ ore leaching

    DOEpatents

    Mallon, R.G.; Braun, R.L.

    1975-10-28

    An acid leaching method is described for the recovery of a desired element from a subterranean rubblized body of primary ore containing the element and also having associated therewith a carbonate mineral wherein the rubblized ore body is flooded with an aqueous acidic solution in order to release carbon dioxide from the associated carbonate mineral. After a substantial portion of the available carbon dioxide is released and removed from the ore body, as by venting to the atmosphere, an oxidizing gas is introduced into the flooded, rubblized ore to oxidize the ore and form an acid leach solution effective in the presence of the dissolved oxidizing gas to dissolve the ore and cause the desired element to go into solution. The leach solution is then circulated to the surface where the metal values are recovered therefrom.

  17. Obeticholic acid for the treatment of primary biliary cirrhosis.

    PubMed

    Trivedi, Palak J; Hirschfield, Gideon M; Gershwin, M Eric

    2016-01-01

    Primary biliary cirrhosis (PBC) is characterized by progressive nonsuppurative destruction of small bile ducts, resulting in intrahepatic cholestasis, fibrosis and ultimately end-stage liver disease. Timely intervention with ursodeoxycholic acid is associated with excellent survival, although approximately one-third of all patients fail to achieve biochemical response, signifying a critical need for additional therapeutic strategies. Obeticholic acid (OCA) is a potent ligand of the nuclear hormone receptor farnesoid X receptor (FXR). Activation of FXR inhibits bile acid synthesis and protects against toxic accumulation in models of cholestasis and facilitates hepatic regeneration in preclinical studies. Data from recent Phase II and III controlled trials suggest a therapeutic impact of OCA in PBC biochemical nonresponders, as evidenced by change in proven laboratory surrogates of long-term outcome. Dose-dependent pruritus is a common adverse effect, but may be overcome through dose-titration. Longer term studies are needed with focus on safety and long-term clinical efficacy.

  18. Two modes of surface roughening during plasma etching of silicon: Role of ionized etch products

    NASA Astrophysics Data System (ADS)

    Nakazaki, Nobuya; Tsuda, Hirotaka; Takao, Yoshinori; Eriguchi, Koji; Ono, Kouichi

    2014-12-01

    Atomic- or nanometer-scale surface roughening has been investigated during Si etching in inductively coupled Cl2 plasmas, as a function of rf bias power or ion incident energy Ei, by varying feed gas flow rate, wafer stage temperature, and etching time. The experiments revealed two modes of surface roughening which occur depending on Ei: one is the roughening mode at low Ei < 200-300 eV, where the root-mean-square (rms) roughness of etched surfaces increases with increasing Ei, exhibiting an almost linear increase with time during etching (t < 20 min). The other is the smoothing mode at higher Ei, where the rms surface roughness decreases substantially with Ei down to a low level < 0.4 nm, exhibiting a quasi-steady state after some increase at the initial stage (t < 1 min). Correspondingly, two different behaviors depending on Ei were also observed in the etch rate versus √{Ei } curve, and in the evolution of the power spectral density distribution of surfaces. Such changes from the roughening to smoothing modes with increasing Ei were found to correspond to changes in the predominant ion flux from feed gas ions Clx+ to ionized etch products SiClx+ caused by the increased etch rates at increased Ei, in view of the results of several plasma diagnostics. Possible mechanisms for the formation and evolution of surface roughness during plasma etching are discussed with the help of Monte Carlo simulations of the surface feature evolution and classical molecular dynamics simulations of etch fundamentals, including stochastic roughening and effects of ion reflection and etch inhibitors.

  19. Two modes of surface roughening during plasma etching of silicon: Role of ionized etch products

    SciTech Connect

    Nakazaki, Nobuya Tsuda, Hirotaka; Takao, Yoshinori; Eriguchi, Koji; Ono, Kouichi

    2014-12-14

    Atomic- or nanometer-scale surface roughening has been investigated during Si etching in inductively coupled Cl{sub 2} plasmas, as a function of rf bias power or ion incident energy E{sub i}, by varying feed gas flow rate, wafer stage temperature, and etching time. The experiments revealed two modes of surface roughening which occur depending on E{sub i}: one is the roughening mode at low E{sub i} < 200–300 eV, where the root-mean-square (rms) roughness of etched surfaces increases with increasing E{sub i}, exhibiting an almost linear increase with time during etching (t < 20 min). The other is the smoothing mode at higher E{sub i}, where the rms surface roughness decreases substantially with E{sub i} down to a low level < 0.4 nm, exhibiting a quasi-steady state after some increase at the initial stage (t < 1 min). Correspondingly, two different behaviors depending on E{sub i} were also observed in the etch rate versus √(E{sub i}) curve, and in the evolution of the power spectral density distribution of surfaces. Such changes from the roughening to smoothing modes with increasing E{sub i} were found to correspond to changes in the predominant ion flux from feed gas ions Cl{sub x}{sup +} to ionized etch products SiCl{sub x}{sup +} caused by the increased etch rates at increased E{sub i}, in view of the results of several plasma diagnostics. Possible mechanisms for the formation and evolution of surface roughness during plasma etching are discussed with the help of Monte Carlo simulations of the surface feature evolution and classical molecular dynamics simulations of etch fundamentals, including stochastic roughening and effects of ion reflection and etch inhibitors.

  20. Plasma etching a ceramic composite. [evaluating microstructure

    NASA Technical Reports Server (NTRS)

    Hull, David R.; Leonhardt, Todd A.; Sanders, William A.

    1992-01-01

    Plasma etching is found to be a superior metallographic technique for evaluating the microstructure of a ceramic matrix composite. The ceramic composite studied is composed of silicon carbide whiskers (SiC(sub W)) in a matrix of silicon nitride (Si3N4), glass, and pores. All four constituents are important in evaluating the microstructure of the composite. Conventionally prepared samples, both as-polished or polished and etched with molten salt, do not allow all four constituents to be observed in one specimen. As-polished specimens allow examination of the glass phase and porosity, while molten salt etching reveals the Si3N4 grain size by removing the glass phase. However, the latter obscures the porosity. Neither technique allows the SiC(sub W) to be distinguished from the Si3N4. Plasma etching with CF4 + 4 percent O2 selectively attacks the Si3N4 grains, leaving SiC(sub W) and glass in relief, while not disturbing the pores. An artifact of the plasma etching reaction is the deposition of a thin layer of carbon on Si3N4, allowing Si3N4 grains to be distinguished from SiC(sub W) by back scattered electron imaging.

  1. Pulsed plasma etching for semiconductor manufacturing

    NASA Astrophysics Data System (ADS)

    Economou, Demetre J.

    2014-07-01

    Power-modulated (pulsed) plasmas have demonstrated several advantages compared to continuous wave (CW) plasmas. Specifically, pulsed plasmas can result in a higher etching rate, better uniformity, and less structural, electrical or radiation (e.g. vacuum ultraviolet) damage. Pulsed plasmas can also ameliorate unwanted artefacts in etched micro-features such as notching, bowing, micro-trenching and aspect ratio dependent etching. As such, pulsed plasmas may be indispensable in etching of the next generation of micro-devices with a characteristic feature size in the sub-10 nm regime. This work provides an overview of principles and applications of pulsed plasmas in both electropositive (e.g. argon) and electronegative (e.g. chlorine) gases. The effect of pulsing the plasma source power (source pulsing), the electrode bias power (bias pulsing), or both source and bias power (synchronous pulsing), on the time evolution of species densities, electron energy distribution function and ion energy and angular distributions on the substrate is discussed. The resulting pulsed plasma process output (etching rate, uniformity, damage, etc) is compared, whenever possible, to that of CW plasma, under otherwise the same or similar conditions.

  2. Degradation in the Fatigue Strength of Dentin by Cutting, Etching and Adhesive Bonding

    PubMed Central

    Lee, H.-H.; Majd, H.; Orrego, S.; Majd, B.; Romberg, E.; Mutluay, M.M.; Arola, D.

    2014-01-01

    The processes involved in placing resin composite restorations may degrade the fatigue strength of dentin and increase the likelihood of fractures in restored teeth. Objective The objective of this study was to evaluate the relative changes in strength and fatigue behavior of dentin caused by bur preparation, etching and resin bonding procedures using a 3-step system. Methods Specimens of dentin were prepared from the crowns of unrestored 3rd molars and subjected to either quasi-static or cyclic flexural loading to failure. Four treated groups were prepared including dentin beams subjected to a burr treatment only with a conventional straight-sided bur, or etching treatment only. An additional treated group received both bur and etching treatments, and the last was treated by bur treatment and etching, followed by application of a commercial resin adhesive. The control group consisted of “as sectioned” dentin specimens. Results Under quasi-static loading to failure there was no significant difference between the strength of the control group and treated groups. Dentin beams receiving only etching or bur cutting treatments exhibited fatigue strengths that were significantly lower (p≤0.0001) than the control; there was no significant difference in the fatigue resistance of these two groups. Similarly, the dentin receiving bur and etching treatments exhibited significantly lower (p≤0.0001) fatigue strength than that of the control, regardless of whether an adhesive was applied. Significance The individual steps involved in the placement of bonded resin composite restorations significantly decrease the fatigue strength of dentin, and application of a bonding agent does not increase the fatigue strength of dentin. PMID:24985539

  3. Evaluation of the effect of surface preparation using phosphoric acid and luting cement on the flexural strength of porcelain laminate veneering material

    PubMed Central

    Guruprasada; Rivankar, N.; Dhiman, R.K.; Viswambaran, M.

    2015-01-01

    Background Conventionally HF acid has been used for etching ceramic veneer restorations before their cementation. Studies are lacking regarding the effectiveness of phosphoric acid as a substitute for HF acid for etching the ceramic veneers. The purpose of this study was to evaluate the effectiveness of surface preparation of porcelain laminate veneers using phosphoric acid, as compared to HF acid etching in providing the necessary surface roughness conducive to development of an effective bond between the ceramic laminate and the resin luting cement. Methods 210 porcelain discs of 15 mm diameter and 0.9 mm thickness were prepared. These study samples were divided into seven groups of thirty samples each. Surfaces of the first (control) and the second group of samples were not prepared. The surfaces of other five groups were prepared with different surface treatments. Further all the groups of specimens were coated with a layer of resin luting cement. Flexural strength of each specimen was determined using universal testing machine and the results were compared. Results The combination surface treatment using alumina surface abrasion followed by etching with phosphoric acid provided the highest flexural strength with the mean flexural strength of 101.11 MPa, followed by alumina surface abrasion (95.41 MPa), and phosphoric acid surface etching (81.68 MPa). Conclusion Laminate veneers surface treated using 50 μm alumina abrasion followed by etching with phosphoric acid showed the highest flexural strengths after resin coating compared to other groups. PMID:26843743

  4. Study on the etching process GaAs-based VCSEL

    NASA Astrophysics Data System (ADS)

    Feng, Yuan; Liu, Guojun; Hao, Yongqin; Yan, Changling; Zhang, Jiabin; Li, Yang; Li, Zaijin

    2016-11-01

    Wet etching process is a key technology in fabrication of VCSEL and their array in order to improve opto-electric characteristics of high-power VCSEL, devices with multi-ring distribution hole VCSEL is fabricated. The H3PO4 etching solution was used in the wet etching progress and etching rate is studied by changing etching solution concentration and etching time. The optimum technological conditions were determined by studying the etching morphology and etching depth of the GaAs-VCSEL. The tested results show that the complete morphology and the appropriate depth can be obtained by using the concentration ratio of 1:1:10, which can meet the requirements of GaAs-based VCSEL micro- structure etching process.

  5. Geometric characteristics of silicon cavities etched in EDP

    NASA Astrophysics Data System (ADS)

    Ju, Hui; Ohta, Takayuki; Ito, Masafumi; Sasaki, Minoru; Hane, Kazuhiro; Hori, Masaru

    2007-05-01

    Etching characteristics of hexagonal and triangular cavities on a lang1 1 1rang-oriented silicon wafer in the etchant of ethylene diamine, pyrocatechol and water (EDP/EPW) were investigated. The patterns are aligned to keep the sides perpendicular to lang1 1 0rang crystal orientations, in order that the sidewalls of cavities are parallel to {1 1 0} crystalline planes. RIE-ICP etching is used to define the depth of the triangular and hexagonal cavities, and EDP etching is followed for different etching times. The final self-etch-stop profiles of cavities are determined by the dimension of mask patterns and the depth of cavities in the wafer. The etching process of the hexagon and triangle cavities is modeled, based on the crystal structure and wet etching principle. The results of etched cavities confirm the condition to determine the final etching profiles.

  6. The Effects of Prophylactic Ozone Pretreatment of Enamel on Shear Bond Strength of Orthodontic Brackets Bonded with Total or Self-Etch Adhesive Systems

    PubMed Central

    Cehreli, Sevi Burcak; Guzey, Asli; Arhun, Neslihan; Cetinsahin, Alev; Unver, Bahtiyar

    2010-01-01

    Objectives: The aim of this in vitro study is to determine (1) shear bond strength (SBS) of brackets bonded with self-etch and total-etch adhesive after ozone treatment (2) bond failure interface using a modified Adhesive Remnant Index (ARI). Methods: 52 premolars were randomly assigned into four groups (n=13) and received the following treatments: Group 1: 30 s Ozone (Biozonix, Ozonytron, Vehos Medikal, Ankara, Turkey) application + Transbond Plus Self-Etching Primer (SEP) (3M) + Transbond XT (3M), Group 2: Transbond Plus SEP + Transbond XT, Group 3: 30 s Ozone application + 37% orthophosphoric acid + Transbond XT Primer (3M) + Transbond XT, Group 4: 37% orthophosphoric acid + Transbond XT Primer + Transbond XT. All samples were stored in deionised water at 37°C for 24 hours. Shear debonding test was performed by applying a vertical force to the base of the bracket at a cross-head speed of 1 mm/min. Results: The mean SBS results were Group 1: 10.48 MPa; Group 2: 8.89 MPa; Group 3: 9.41 MPa; Group 4: 9.82 MPa. One-Way Variance Test revealed that the difference between the groups was not statistically significant (P=0.267). Debonded brackets were examined by an optical microscope at X16 magnification to determine the bond failure interface using a modified ARI. The results were (mean) Group 1: 2.38; Group 2: 1.31; Group 3: 3.00; Group 4: 1.92. Multiple comparisons showed that Groups 1 and 2, 2 and 3, 3 and 4 were statistically different (P=0.014, P<.001 and P=0.025). Conclusions: Ozone treatment prior to bracket bonding does not affect the shear bond strength. PMID:20922155

  7. MODULAR FIELD-BIOREACTOR FOR ACID MINE DRAINAGE TREATMENT

    EPA Science Inventory

    The presentation focuses on the improvements to engineered features of a passive technology that has been used for remediation of acid rock drainage (ARD). This passive remedial technology, a sulfate-reducing bacteria (SRB) bioreactor, takes advantage of the ability of SRB that,...

  8. Epidermodysplasia verruciformis: successful treatment with squaric acid dibutylester.

    PubMed

    Kehdy, Jessica; Erickson, Corrine; Rady, Peter; Tyring, Stephen; Gaspari, Anthony A

    2015-08-01

    Epidermodysplasia verruciformis (EV) is a rare disorder characterized by disseminated cutaneous warts in predisposed patients who are highly susceptible to genus ß-papillomavirus infections. We present the case of a 40-year-old lymphocytopenic woman with a balanced chromosomal translocation and a 25-year history of refractory EV that was successfully treated with squaric acid dibutylester (SADBE) contact immunotherapy.

  9. Maleic acid treatment of biologically detoxified corn stover liquor

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Elimination of microbial and/or enzyme inhibitors from pretreated lignocellulose is critical for effective cellulose conversion and yeast fermentation of liquid hot-water (LHW) pretreated corn stover. In this study, xylan oligomers were hydrolyzed using either maleic acid or hemicellulases. Other so...

  10. Could peracetic acid be an alternative treatment in aquaculture?

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Peracetic acid (PAA) is an antimicrobial disinfectant used in agriculture, food processing and medical facilities. It has recently been tested as a means to control infestations of Ichthyophthirius multifiliis and Saprolegnia parasitica. Free-swimming theronts of I. multifiliis can be eliminated u...

  11. Dynamic peracetic acid (PAA) exposure, a treatment strategy against ectoparasites

    Technology Transfer Automated Retrieval System (TEKTRAN)

    The search for alternative therapeutic agents is a difficult and laborious task. The use of peracetic acid (PAA) has recently been evaluated as an alternative compound for disinfection (Gustavino et al., 2005). In addition to having a broad antimicrobial spectrum, PAA does not contribute to the form...

  12. The Promotion of Indole-3-acetic Acid Oxidation in Pea Buds by Gibberellic Acid and Treatment 1

    PubMed Central

    Ockerse, Ralph; Waber, Jack

    1970-01-01

    Terminal buds of dark-grown pea (Pisum sativum) seedlings have an indole-3-acetic acid oxidase which does not require Mn2+ and 2,4-dichlorophenol as cofactors. Oxidase activity is at least 50 times higher in buds of tall peas than in dwarf seedlings. Administration of gibberellic acid to dwarf peas stimulates both growth and indoleacetic acid oxidase activity to the same levels as in tall seedlings. By contrast, indoleacetic acid oxidation assayed in the presence of Mn2+ and 2,4-dichlorophenol proceeds at similar rates regardless of gibberellin application. Treatment of tall peas with the growth retardant AMO-1618 reduces growth and oxidase activity. Such treated seedlings are indistinguishably dwarf. The enzyme does not appear to be polyphenol oxidase, nor do the results suggest that reduced activity in dwarf buds is due to higher levels of a dialyzable inhibitor. The peroxidative nature of the oxidase is probable. PMID:5500209

  13. Operational Lessons Learned During Bioreactor Demonstrations for Acid Rock Drainage Treatment

    EPA Science Inventory

    The U.S. Environmental Protection Agency’s Mine Waste Technology Program (MWTP) has emphasized the development of biologically-based treatment technologies for acid rock drainage (ARD). Progressively evolving technology demonstrations have resulted in significant advances in sul...

  14. Operational Lessons Leaned During bioreactor Demonstrations for Acid Rock Drainage Treatment

    EPA Science Inventory

    The U.S. Environmental Protection Agency's Mine Waste Technology Program (MWTP) has emphasized the development of biologically-based treatment technologies for acid rock drainage (ARD). Progressively evolving technology demonstrations have resulted in significant advances in sulf...

  15. ICP Etching of SiC

    SciTech Connect

    Grow, J.M.; Lambers, E.S.; Ostling, M.; Pearton, S.J.; Ren, F.; Shul, R.J.; Wang, J.J.; Zetterling, C.-M.

    1999-02-04

    A number of different plasma chemistries, including NF{sub 3}/O{sub 2}, SF{sub 6}/O{sub 2}, SF{sub 6}/Ar, ICl, IBr, Cl{sub 2}/Ar, BCl{sub 3}/Ar and CH{sub 4}/H{sub 2}/Ar, have been investigated for dry etching of 6H and 3C-SiC in a Inductively Coupled Plasma tool. Rates above 2,000 {angstrom} cm{sup {minus}1} are found with fluorine-based chemistries at high ion currents. Surprisingly, Cl{sub 2}-based etching does not provide high rates, even though the potential etch products (SiCi{sub 4} and CCl{sub 4}) are volatile. Photoresist masks have poor selectivity over SiC in F{sub 2}-based plasmas under normal conditions, and ITO or Ni are preferred.

  16. Etching of nanopatterns in silicon using nanopantography

    NASA Astrophysics Data System (ADS)

    Xu, Lin; Nasrullah, Azeem; Chen, Zhiying; Jain, Manish; Ruchhoeft, Paul; Economou, Demetre J.; Donnelly, Vincent M.

    2008-01-01

    Nanopantography is a technique for parallel writing of nanopatterns over large areas. A broad ion beam impinges on a substrate containing many microfabricated electrostatic lenses that focus ions to spots at the substrate surface. Here, etching of nanopatterns is demonstrated. The substrate was continuously titled about x and y axes with 0.11° precision, corresponding to a translation of the ion foci of 1.5nm on the substrate. With tilting in one direction, 15nm full width at half maximum trenches 45nm deep were etched into a Si wafer using an Ar+ beam in a Cl2 ambient. T-shaped patterns were etched by tilting the substrates in two directions.

  17. Electrochemical treatment of perfluorooctanoic acid (PFOA) and perfluorooctane sulfonic acid (PFOS) in groundwater impacted by aqueous film forming foams (AFFFs).

    PubMed

    Schaefer, Charles E; Andaya, Christina; Urtiaga, Ana; McKenzie, Erica R; Higgins, Christopher P

    2015-09-15

    Laboratory experiments were performed to evaluate the use of electrochemical treatment for the decomposition of perfluorooctanoic acid (PFOA) and perfluorooctane sulfonic acid (PFOS), as well as other perfluoroalkyl acids (PFAAs), in aqueous film forming foam (AFFF)-impacted groundwater collected from a former firefighter training area and PFAA-spiked synthetic groundwater. Using a commercially-produced Ti/RuO2 anode in a divided electrochemical cell, PFOA and PFOS decomposition was evaluated as a function of current density (0-20 mA/cm(2)). Decomposition of both PFOA and PFOS increased with increasing current density, although the decomposition of PFOS did not increase as the current density was increased above 2.5 mA/cm(2). At a current density of 10 mA/cm(2), the first-order rate constants, normalized for current density and treatment volume, for electrochemical treatment of both PFOA and PFOS were 46 × 10(-5) and 70 × 10(-5) [(min(-1)) (mA/cm(2))(-1) (L)], respectively. Defluorination was confirmed for both PFOA and PFOS, with 58% and 98% recovery as fluoride, respectively (based upon the mass of PFOA and PFOS degraded). Treatment of other PFAAs present in the groundwater also was observed, with shorter chain PFAAs generally being more recalcitrant. Results highlight the potential for electrochemical treatment of PFAAs, particularly PFOA and PFOS, in AFFF-impacted groundwater.

  18. PERIODS OF VERTEBRAL COLUMN SENSITIVITY TO BORIC ACID TREATMENT IN CD-1 MICE IN UTERO

    EPA Science Inventory

    Periods of vertebral column sensitivity to boric acid treatment in CD-1 mice in utero.

    Cherrington JW, Chernoff N.

    Department of Toxicology, North Carolina State University, Raleigh, NC 27695, USA. jana_cherrington@hotmail.com

    Boric acid (BA) has many uses as...

  19. Effect of oxalic acid treatment on sediment arsenic concentrations and lability under reducing conditions.

    PubMed

    Sun, Jing; Bostick, Benjamin C; Mailloux, Brian J; Ross, James M; Chillrud, Steven N

    2016-07-05

    Oxalic acid enhances arsenic (As) mobilization by dissolving As host minerals and competing for sorption sites. Oxalic acid amendments thus could potentially improve the efficiency of widely used pump-and-treat (P&T) remediation. This study investigates the effectiveness of oxalic acid on As mobilization from contaminated sediments with different As input sources and redox conditions, and examines whether residual sediment As after oxalic acid treatment can still be reductively mobilized. Batch extraction, column, and microcosm experiments were performed in the laboratory using sediments from the Dover Municipal Landfill and the Vineland Chemical Company Superfund sites. Oxalic acid mobilized As from both Dover and Vineland sediments, although the efficiency rates were different. The residual As in both Dover and Vineland sediments after oxalic acid treatment was less vulnerable to microbial reduction than before the treatment. Oxalic acid could thus improve the efficiency of P&T. X-ray absorption spectroscopy analysis indicated that the Vineland sediment samples still contained reactive Fe(III) minerals after oxalic acid treatment, and thus released more As into solution under reducing conditions than the treated Dover samples. Therefore, the efficacy of enhanced P&T must consider sediment Fe mineralogy when evaluating its overall potential for remediating groundwater As.

  20. Radicals Are Required for Thiol Etching of Gold Particles.

    PubMed

    Dreier, Timothy A; Ackerson, Christopher J

    2015-08-03

    Etching of gold with an excess of thiol ligand is used in both synthesis and analysis of gold particles. Mechanistically, the process of etching gold with excess thiol is unclear. Previous studies have obliquely considered the role of oxygen in thiolate etching of gold. Herein, we show that oxygen or a radical initiator is a necessary component for efficient etching of gold by thiolates. Attenuation of the etching process by radical scavengers in the presence of oxygen, and the restoration of activity by radical initiators under inert atmosphere, strongly implicate the oxygen radical. These data led us to propose an atomistic mechanism in which the oxygen radical initiates the etching process.

  1. Model polymer etching and surface modification by a time modulated RF plasma jet: role of atomic oxygen and water vapor

    NASA Astrophysics Data System (ADS)

    Luan, P.; Knoll, A. J.; Wang, H.; Kondeti, V. S. S. K.; Bruggeman, P. J.; Oehrlein, G. S.

    2017-01-01

    The surface interaction of a well-characterized time modulated radio frequency (RF) plasma jet with polystyrene, poly(methyl methacrylate) and poly(vinyl alcohol) as model polymers is investigated. The RF plasma jet shows fast polymer etching but mild chemical modification with a characteristic carbonate ester and NO formation on the etched surface. By varying the plasma treatment conditions including feed gas composition, environment gaseous composition, and treatment distance, we find that short lived species, especially atomic O for Ar/1% O2 and 1% air plasma and OH for Ar/1% H2O plasma, play an essential role for polymer etching. For O2 containing plasma, we find that atomic O initiates polymer etching and the etching depth mirrors the measured decay of O atoms in the gas phase as the nozzle-surface distance increases. The etching reaction probability of an O atom ranging from 10-4 to 10-3 is consistent with low pressure plasma research. We also find that adding O2 and H2O simultaneously into Ar feed gas quenches polymer etching compared to adding them separately which suggests the reduction of O and OH density in Ar/O2/H2O plasma.

  2. [Injuries caused by acids and bases - emergency treatment].

    PubMed

    Reifferscheid, Florian; Stuhr, Markus; Kaiser, Guido; Freudenberg, Matthias; Kerner, Thoralf

    2014-06-01

    Emergency medical care for injuries caused by acids and bases is challenging for rescue services. They have to deal with operational safety, detection of the toxic agent, emergency medical care of the patient and handling of the rescue mission. Because of the rareness of such situations experience and routine are largely missing. This article highlights some basic points for the therapy and provides support for such rescue missions.

  3. Alternative process for thin layer etching: Application to nitride spacer etching stopping on silicon germanium

    SciTech Connect

    Posseme, N. Pollet, O.; Barnola, S.

    2014-08-04

    Silicon nitride spacer etching realization is considered today as one of the most challenging of the etch process for the new devices realization. For this step, the atomic etch precision to stop on silicon or silicon germanium with a perfect anisotropy (no foot formation) is required. The situation is that none of the current plasma technologies can meet all these requirements. To overcome these issues and meet the highly complex requirements imposed by device fabrication processes, we recently proposed an alternative etching process to the current plasma etch chemistries. This process is based on thin film modification by light ions implantation followed by a selective removal of the modified layer with respect to the non-modified material. In this Letter, we demonstrate the benefit of this alternative etch method in term of film damage control (silicon germanium recess obtained is less than 6 A), anisotropy (no foot formation), and its compatibility with other integration steps like epitaxial. The etch mechanisms of this approach are also addressed.

  4. Single beam determination of porosity and etch rate in situ during etching of porous silicon

    NASA Astrophysics Data System (ADS)

    Foss, S. E.; Kan, P. Y. Y.; Finstad, T. G.

    2005-06-01

    A laser reflection method has been developed and tested for analyzing the etching of porous silicon (PS) films. It allows in situ measurement and analysis of the time dependency of the etch rate, the thickness, the average porosity, the porosity profile, and the interface roughness. The interaction of an infrared laser beam with a layered system consisting of a PS layer and a substrate during etching results in interferences in the reflected beam which is analyzed by the short-time Fourier transform. This method is used for analysis of samples prepared with etching solutions containing different concentrations of HF and glycerol and at different current densities and temperatures. Variations in the etch rate and porosity during etching are observed, which are important effects to account for when optical elements in PS are made. The method enables feedback control of the etching so that PS films with a well-controlled porosity are obtainable. By using different beam diameters it is possible to probe interface roughness at different length scales. Obtained porosity, thickness, and roughness values are in agreement with values measured with standard methods.

  5. Supplementation with long chain polyunsaturated fatty acids in treatment of atopic dermatitis in children

    PubMed Central

    Kaczmarski, Maciej; Sawicka-Żukowska, Małgorzata; Bobrus-Chociej, Anna

    2013-01-01

    Some recent studies indicate that unsaturated fatty acids, components of cellular membranes and precursors of immunomodulators, play a significant role in the pathogenesis of some symptoms of atopic dermatitis. Since they cannot be synthesized by the human body, they must be provided with nutrition as the so called exogenous fatty acids: linoleic (a precursor of arachidonic acid) and α-linolenic acid (a precursor of eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA)). Their deficiency facilitates the development of some disorders, e.g. of the cardiovascular system or of the nervous system, or becomes the cause of intensification of ailments in their course e.g. pruritus and dryness in atopic dermatitis. Though clinical examinations to date confirm the efficacy of fatty acid supplementation in treatment of atopic dermatitis, their results are not explicit. PMID:24278056

  6. Optimization of plasma deposition and etching processes for commercial multicrystalline silicon solar cells

    SciTech Connect

    Ruby, D.S.; Wilbanks, W.L.; Fleddermann, C.B.; Rosenblum, M.D.; Roncin, S.; Narayanan, S.

    1996-06-01

    The authors conducted an investigation of plasma deposition and etching processes on full-size multicrystalline (mc-Si) cells processed in commercial production lines, so that any improvements obtained will be immediately relevant to the PV industry. In one case, the authors performed a statistically designed multiparameter experiment to determine the optimum PECVD-nitride deposition conditions specific to EFG silicon from ASE Americas, Inc. In a related effort, they studied whether plasma-etching techniques can use standard screen-printed gridlines as etch masks to form self-aligned, patterned-emitter profiles on mc-Si cells from Solarex Corp. Initial results found a statistically significant improvement of about half an absolute percentage point in cell efficiency when the self-aligned emitter etchback was combined with the PECVD-nitride surface passivation treatment. Additional improvement is expected when the successful bulk passivation treatment is also added to the process.

  7. Resistant starch improvement of rice starches under a combination of acid and heat-moisture treatments.

    PubMed

    Hung, Pham Van; Vien, Ngo Lam; Lan Phi, Nguyen Thi

    2016-01-15

    The effects of a combination of acid and heat-moisture treatment on formation of resistant starch (RS) and characteristics of high-amylose, normal and waxy rice starches were investigated in this study. The degrees of polymerization of the rice starches treated with citric acid, lactic acid or acetic acid were significantly reduced as compared to the native starches. The RS contents of acid and heat-moisture treated rice starches were in a range of 30.1-39.0%, significantly higher than those of native rice starches (6.3-10.2%) and those of heat-moisture treated rice starches (18.5-23.9%). The acid and heat-moisture treatments reduced swelling power and viscosity, but increased solubility of the starches, while the crystalline structure did not change. Among the organic acids used, citric acid had the most impact on starch characteristics and RS formation, followed by lactic acid and acetic acid. The results are useful in production of RS for functional food application.

  8. Direct fabrication of compound-eye microlens array on curved surfaces by a facile femtosecond laser enhanced wet etching process

    NASA Astrophysics Data System (ADS)

    Bian, Hao; Wei, Yang; Yang, Qing; Chen, Feng; Zhang, Fan; Du, Guangqing; Yong, Jiale; Hou, Xun

    2016-11-01

    We report a direct fabrication of an omnidirectional negative microlens array on a curved substrate by a femtosecond laser enhanced chemical etching process, which is utilized as a molding template for duplicating bioinspired compound eyes. The femtosecond laser treatment of the curved glass substrate employs a common x-y-z stage without rotating the sample surface perpendicular to the laser beam, and uniform, omnidirectional-aligned negative microlenses are generated after a hydrofluoric acid etching. Using the negative microlens array on the concave glass substrate as a molding template, we fabricate an artificial compound eye with 3000 positive microlenses of 95-μm diameter close-packed on a 5-mm polymer hemisphere. Compared to the transferring process, the negative microlenses directly fabricated on the curved mold by our method are distortion-free, and the duplicated artificial eye presents clear and uniform imaging capabilities. This work provides a facile and efficient route to the fabrication of microlenses on any curved substrates without complicated alignment and motion control processes, which has the potential for the development of new microlens-based devices and systems.

  9. Distinguishing shocked from tectonically deformed quartz by the use of the SEM and chemical etching

    USGS Publications Warehouse

    Gratz, A.J.; Fisler, D.K.; Bohor, B.F.

    1996-01-01

    Multiple sets of crystallographically-oriented planar deformation features (PDFs) are generated by high-strain-rate shock waves at pressures of > 12 GPa in naturally shocked quartz samples. On surfaces, PDFs appear as narrow (50-500 nm) lamellae filled with amorphosed quartz (diaplectic glass) which can be etched with hydrofluoric acid or with hydrothermal alkaline solutions. In contrast, slow-strain-rate tectonic deformation pressure produces wider, semi-linear and widely spaced arrays of dislocation loops that are not glass filled. Etching samples with HF before examination in a scanning electron microscope (SEM) allows for unambiguous visual distinction between glass-filled PDFs and glass-free tectonic deformation arrays in quartz. This etching also reveals the internal 'pillaring' often characteristic of shock-induced PDFs. This technique is useful for easily distinguishing between shock and tectonic deformation in quartz, but does not replace optical techniques for characterizing the shock features.

  10. Etching of InP by H3PO4, H2O2 Solutions

    NASA Astrophysics Data System (ADS)

    Mouton, A.; Sundararaman, C. S.; Lafontaine, H.; Poulin, S.; Currie, J. F.

    1990-10-01

    This paper deals with the chemical etching of (100) InP using a phosphoric acid and hydrogen peroxide mixture. It is shown that the etching rate is strongly dependent on the relative concentration of the two species; it is maximal for an equivolumic solution, and depending on the dilution it ranges from 70 to 20 Å/min. The activation energy of a non-diluted solution is approximately 14 kcal/mol. The post-etch surface state of the sample analysed by SEM and XPS, shows a very smooth surface for all concentrations, and the formation of a InPO4\\cdotxH2O layer. This solution can be used as a very precise etchant in devices processes.

  11. Analysis of p-Si macropore etching using FFT-impedance spectroscopy.

    PubMed

    Ossei-Wusu, Emmanuel; Carstensen, Jürgen; Föll, Helmut

    2012-06-20

    The dependence of the etch mechanism of lithographically seeded macropores in low-doped p-type silicon on water and hydrofluoric acid (HF) concentrations has been investigated. Using different HF concentrations (prepared from 48 and 73 wt.% HF) in organic electrolytes, the pore morphologies of etched samples have been related to in situ impedance spectra (IS) obtained by Fast Fourier Transform (FFT) technique. It will be shown that most of the data can be fitted with a simple equivalent circuit model. The model predicts that the HF concentration is responsible for the net silicon dissolution rate, while the dissolution rate selectivity at the pore tips and walls that ultimately enables pore etching depends on the water content. The 'quality' of the pores increases with decreasing water content in HF/organic electrolytes.

  12. Effects of chlorhexidine in self-etching adhesive: 24 hours results.

    PubMed

    Nishitani, Yoshihiro; Hosaka, Keiichi; Hoshika, Tomohiro; Yoshiyama, Masahiro; Pashley, David H

    2013-01-01

    It is known that chlorhexidine (CHX) does not inhibit micro-tensile bond strengths (MTBS) when it is used in etch-and-rinse adhesives. In that technique, CHX is applied to dentin as a primer after phosphoric acid-etching before bonding with Single Bond. It would be more convenient if it is possible to incorporate CHX into the adhesive. The purpose of this study was to compare the MTBS and the FT-IR percent conversion of an all-in-one self-etching adhesives contained varying concentration of CHX. Extracted human third molars were bonded with a control all-in-one adhesive or experimental versions containing 0.5, 1, 2 or 5% CHX. The MTBS and the percent conversion of experimental adhesives containing up to 1% CHX were not significantly CHX-free control adhesives. However, addition of 2 or especially 5% CHX experimental adhesives produced significant reductions in both the MTBS and the percent conversion.

  13. Addition of Grape Seed Extract Renders Phosphoric Acid a Collagen-stabilizing Etchant.

    PubMed

    Liu, Y; Dusevich, V; Wang, Y

    2014-08-01

    Previous studies found that grape seed extract (GSE), which is rich in proanthocyanidins, could protect demineralized dentin collagen from collagenolytic activities following clinically relevant treatment. Because of proanthocyanidin's adverse interference to resin polymerization, it was believed that GSE should be applied and then rinsed off in a separate step, which in effect increases the complexity of the bonding procedure. The present study aimed to investigate the feasibility of combining GSE treatment with phosphoric acid etching to address the issue. It is also the first attempt to formulate collagen-cross-linking dental etchants. Based on Fourier-transformed infrared spectroscopy and digestion assay, it was established that in the presence of 20% to 5% phosphoric acid, 30 sec of GSE treatment rendered demineralized dentin collagen inert to bacterial collagenase digestion. Based on this positive result, the simultaneous dentin etching and collagen protecting of GSE-containing phosphoric acid was evaluated on the premise of a 30-second etching time. According to micro-Raman spectroscopy, the formulation containing 20% phosphoric acid was found to lead to overetching. Based on scanning and transmission electronic microscopy, this same formulation exhibited unsynchronized phosphoric acid and GSE penetration. Therefore, addition of GSE did render phosphoric acid a collagen-stabilizing etchant, but the preferable phosphoric acid concentration should be <20%.

  14. Nanometer scale high-aspect-ratio trench etching at controllable angles using ballistic reactive ion etching

    SciTech Connect

    Cybart, Shane; Roediger, Peter; Ulin-Avila, Erick; Wu, Stephen; Wong, Travis; Dynes, Robert

    2012-11-30

    We demonstrate a low pressure reactive ion etching process capable of patterning nanometer scale angled sidewalls and three dimensional structures in photoresist. At low pressure the plasma has a large dark space region where the etchant ions have very large highly-directional mean free paths. Mounting the sample entirely within this dark space allows for etching at angles relative to the cathode with minimal undercutting, resulting in high-aspect ratio nanometer scale angled features. By reversing the initial angle and performing a second etch we create three-dimensional mask profiles.

  15. Dry-etching resistance of fluoropolymers for 157-nm single-layer resists

    NASA Astrophysics Data System (ADS)

    Kawaguchi, Yasuhide; Irisawa, Jun; Kodama, Shun-ichi; Okada, Shinji; Takebe, Yoko; Kaneko, Isamu; Yokokoji, Osamu; Ishikawa, Seiichi; Irie, Shigeo; Hagiwara, Takuya; Itani, Toshiro

    2003-06-01

    Novel fluoropolymers having partially fluorinated monocyclic (5-membered and 6-membered ring) structure have been synthesized with radical cyclo-polymerization, which have C-F bond in the polymer main chain and also possess fluorocontaining acidic alcohol group. These polymers have excellent transparency lower than 1.0 μm-1 at 157nm wavelength, a small amount of outgassing, high sensitivity and good adhesion to the wafer. However, this fluoropolymer have lower etching resistance (half of conventional KrF resists) and it must be improved for applying to the single-layer resist. In this paper, we show the new model of the estimation of the dry-etching resistance for designing polymer compositions. It is well known that the model using carbon-atom-density as a parameter is useful for estimating dry-etching resistance. However, these models did not agree with the results of our fluoropolymers. Our new model was focused on the surface area and the volume of the polymer. We succeeded to explain the relationship between the dry-etching resistance and the composition of the fluoropolymer. According to this model, the compositions of fluoropolymer such as protective groups, protective ration and co-polymer units were optimized to improve their etching resistance.

  16. Evaluation of Cu Ion Concentration Effects on Cu Etching Rate in Chemical-Mechanical Polishing Slurry

    NASA Astrophysics Data System (ADS)

    Nishizawa, Hideaki; Sugiura, Osamu; Matsumura, Yoshiyuki; Kinoshita, Masaharu

    2007-04-01

    The effects of Cu ion concentration of the different solutions on Cu etching rate were investigated. From the dipping experiment of Cu substrates in different solutions of malic acid, hydrogen peroxide (H2O2), benzotriazole (BTA), and Cu ions, it was revealed that Cu etching rate is increased if the concentration of Cu(II) ions added in the solution is high. This is considered to be caused by the effect of Cu(II) ions on H2O2 molecules. In the solution of pH 7, the Cu etching rate increased markedly between 1.7× 10-4 and 3.4× 10-4 M Cu(II) ion concentrations. The maximum increase in the etching rate was from 990 to 2200 nm/min at a H2O2 concentration of 2 wt %. In the solution of pH 3, a marked change in the etching rate was not observed. Our results show that the concentration of Cu ions on the polishing pad in chemical-mechanical polishing (CMP) process is very important.

  17. Formation of Mach angle profiles during wet etching of silica and silicon nitride materials

    NASA Astrophysics Data System (ADS)

    Ghulinyan, M.; Bernard, M.; Bartali, R.; Pucker, G.

    2015-12-01

    In integrated circuit technology peeling of masking photoresist films is a major drawback during the long-timed wet etching of materials. It causes an undesired film underetching, which is often accompanied by a formation of complex etch profiles. Here we report on a detailed study of wedge-shaped profile formation in a series of silicon oxide, silicon oxynitride and silicon nitride materials during wet etching in a buffered hydrofluoric acid (BHF) solution. The shape of etched profiles reflects the time-dependent adhesion properties of the photoresist to a particular material and can be perfectly circular, purely linear or a combination of both, separated by a knee feature. Starting from a formal analogy between the sonic boom propagation and the wet underetching process, we model the wedge formation mechanism analytically. This model predicts the final form of the profile as a function of time and fits the experimental data perfectly. We discuss how this knowledge can be extended to the design and the realization of optical components such as highly efficient etch-less vertical tapers for passive silicon photonics.

  18. Maskless micro/nanofabrication on GaAs surface by friction-induced selective etching

    PubMed Central

    2014-01-01

    In the present study, a friction-induced selective etching method was developed to produce nanostructures on GaAs surface. Without any resist mask, the nanofabrication can be achieved by scratching and post-etching in sulfuric acid solution. The effects of the applied normal load and etching period on the formation of the nanostructure were studied. Results showed that the height of the nanostructure increased with the normal load or the etching period. XPS and Raman detection demonstrated that residual compressive stress and lattice densification were probably the main reason for selective etching, which eventually led to the protrusive nanostructures from the scratched area on the GaAs surface. Through a homemade multi-probe instrument, the capability of this fabrication method was demonstrated by producing various nanostructures on the GaAs surface, such as linear array, intersecting parallel, surface mesas, and special letters. In summary, the proposed method provided a straightforward and more maneuverable micro/nanofabrication method on the GaAs surface. PMID:24495647

  19. [Fatty acids in treatment and prevention of depression].

    PubMed

    Wilczyńska, Agnieszka

    2013-01-01

    The increase of incident rates for depression and other psychiatric disorders is a serious threat for all communities. The study presents data verifying the relationship between the level of omega-3 PUFAs in the blood and an increased risk of depression, including the parallel standard therapy with antidepressants or not. There is an increasing number of evidences that fatty acids like DHA, AA and EPA are linked to depression. In epidemiological studies and clinical trials a correlation between the decline of omega-3 PUFA intake and an increasing risk for developing depression is considered.

  20. Treatment of endometriosis with local acetylsalicylic acid injection: experimental study in rabbits.

    PubMed

    Siqueira, Juliana Menezes; Barreto, Adriana Beatriz; Saad-Hossne, Rogério

    2011-01-01

    The objective of the present study was to estimate the effects of introduction of acetylsalicylic acid solution into peritoneal implants in autologous endometrium as a method for treating endometriosis. Forty adult female rabbits were subdivided into 4 groups of 10 rabbits each, and endometriosis was induced via autotransplantation of endometrial fragments into the peritoneal cavity. At 30 days after induction of endometriosis, all animals were randomly assigned to 1 of 2 protocols. In protocol 1, animals were evaluated at 24 hours after treatment; group 1 (control) received physiologic solution, and group 2 received acetylsalicylic acid. In protocol 2, animals were evaluated at 10 days after treatment, group 3 (control) and group 4 received acetylsalicylic acid. After measuring the lesion, the endometriotic focus was removed and prepared for mounting on slides for histologic analysis. Imaging software was used for analysis of the total remaining area of endometrial tissue. The affected area in acetylsalicylic acid-treated animals was smaller than that in control animals at 24 hours and 10 days after treatment; a significant difference was found between control and treated groups (p < .001). Statistical analysis comparing protocols 1 and 2 demonstrated no differences between controls groups or acetylsalicylic acid groups (p = .30), and no differences between times (p = .75). Acetylsalicylic acid solution led to less growth (or higher involution) of endometrial implants. Acetylsalicylic acid injected directly into endometriotic foci was effective in their destruction. This presents new perspectives for treatment of endometriosis and for clinical applications based on further clinical studies.

  1. Malonic acid suppresses mucin-type O-glycan degradation during hydrazine treatment of glycoproteins.

    PubMed

    Goso, Yukinobu

    2016-03-01

    Hydrazine treatment is frequently used for releasing mucin-type O-glycans (O-glycans) from glycoproteins because the method provides O-glycans that retain a reducible GalNAc at their reducing end, which is available for fluorescent labeling. However, many O-glycans are degraded by "peeling" during this treatment. In the current study, it was found that malonic acid suppressed O-glycan degradation during hydrazine treatment of bovine fetuin or porcine gastric mucin in both the gas and liquid phases. This is paradoxical because the release of O-glycans from glycoproteins occurs under alkaline conditions. However, malonic acid seems to prevent the degradation through its acidic property given that other weak acids also prevented the degradation. Accordingly, disodium malonate did not suppress O-glycan degradation. Application of this method to rat gastric mucin demonstrated that the majority of the major O-glycans obtained in the presence of malonic acid were intact, whereas those obtained in the absence of malonic acid were degraded. These results suggest that hydrazine treatment in the presence of malonic acid would allow glycomic analysis of native mucin glycoproteins.

  2. Hyperargininemia: clinical course and treatment with sodium benzoate and phenylacetic acid.

    PubMed

    Mizutani, N; Maehara, M; Hayakawa, C; Kato, T; Watanabe, K; Suzuki, S

    1983-01-01

    In a patient with hyperargininemia, oral administration of sodium benzoate or phenylacetic acid together with an essential amino acid mixture was used to prevent hyperammonemia and to decrease plasma and CSF concentrations of arginine. Sodium benzoate reduced the plasma ammonia levels, which was confirmed by the increase of urinary excretion of hippuric acid. Phenylacetic acid also controlled hyperammonemia, and EEG findings also improved. By these treatments, plasma and CSF concentrations of arginine showed a slight decrease, but were far above the normal range. There was no clinical improvement, and spasticity of the lower and upper extremities was progressive with mental deterioration.

  3. Effect of ceramic etching protocols on resin bond strength to a feldspar ceramic.

    PubMed

    Bottino, M A; Snellaert, A; Bergoli, C D; Özcan, M; Bottino, M C; Valandro, L F

    2015-01-01

    This study sought to evaluate the resin microtensile bond strength (MTBS) stability of a leucite-reinforced ceramic after different ceramic etching protocols. The microtensile test had 40 ceramic blocks (5×5×6 mm) assigned to five groups (n=8), in accordance with the following surface etching protocols: NE nonetched (control); 9HF: hydrofluoric (HF) acid etching (9%HF)+wash/dry; 4HF: 4%HF+wash/dry; 5HF: 5%HF+wash/dry; and 5HF+N: 5%HF+neutralizer+wash/dry+ultrasonic-cleaning. Etched ceramic surfaces were treated with a silane agent. Next, resin cement blocks were built on the prepared ceramic surface and stored for 24 hours in distilled water at 37°C. The specimens were then sectioned to obtain microtensile beams (32/block), which were randomly assigned to the following conditions, nonaged (immediate test) and aged (water storage for 150 days plus 12,000 thermal cycles), before the microtensile test. Bond strength data were submitted to one-way analysis of variance and Tukey test (α=0.05). Additional ceramic samples were subjected to the different ceramic etching protocols and evaluated using a scanning electron microscope (n=2) and atomic force microscopy (n=2). Aging led to a statistically significant decrease in the MTBS for all groups, except the untreated one (NE). Among the groups submitted to the same aging conditions, the untreated (NE) revealed inferior MTBS values compared to the 9HF and 4HF groups. The 5HF and 5HF+N groups had intermediate mean values, being statistically similar to the higher values presented by the 9HF and 4HF groups and to the lower value associated with the NE group. The neutralization procedure did not enhance the ceramic/resin cement bond strength. HF acid etching is a crucial step in resin/ceramic bonding.

  4. Occurrence of several acidic drugs in sewage treatment plants in Switzerland and risk assessment.

    PubMed

    Tauxe-Wuersch, A; De Alencastro, L F; Grandjean, D; Tarradellas, J

    2005-05-01

    The occurrence and fate of five acidic drugs (Mefenamic acid, Ibuprofen, Ketoprofen, Diclofenac and Clofibric acid) were analysed in three sewage treatment plants (STP) over 4-7 consecutive days. The results point out that the five substances were persistent in wastewater effluents after municipal wastewater treatment. At the most, half of Mefenamic acid was eliminated. Ibuprofen was well removed (80%) by one sewage treatment plant. The removal of Ibuprofen is dependent on the residence time of wastewater in the STPs. A long raining period induce an important decrease of removal of Ibuprofen and Ketoprofen. Removal rates showed a great variability according to sewage treatment plants and types of treatments (e.g. biological, physico-chemical). The concentrations of Ibuprofen, Mefenamic acid and Diclofenac were relatively high in the effluents (150-2000 ng/l), showing a potential contamination of surface water. An environmental risk assessment is presented. Mefenamic acid seems to present a risk for the aquatic environment, with a ratio PEC/PNEC higher than one.

  5. TREATMENT OF ACID MINE DRAINAGE USING FISHBONE APATITE IITM

    SciTech Connect

    Neal A. Yancey

    2006-10-01

    ABSTRACT. In 2000, a reactive barrier was installed on the East Fork of Ninemile Creek near Wallace, Idaho to treat acid mine discharge. The barrier was filled with fishbone derived Apatite IITM to remove the contaminants of concern (Zn, Pb, and Cd) and raise the pH of the acidic mine discharge. Metal removal has been achieved by a combination of chemical, biological, and physical precipitation. Flow for the water ranges from 5 to 35 gallons per minute. The water is successfully being treated, but the system experienced varying degrees of plugging. In 2002, gravel was mixed with the Apatite IITM to help control plugging. In 2003 the Idaho National Laboratory was ask to provide technical support to the Coeur d’Alene Basin Commission to help identify a remedy to the plugging issue. Air sparging was employed to treat the plugging issues. Plastic packing rings were added in the fall of 2005, which have increased the void space in the media and increased flows during the 10 months of operation since the improvements were made.

  6. Gastric acid inhibition in the treatment of peptic ulcer hemorrhage.

    PubMed

    Ghassemi, Kevin A; Kovacs, Thomas O G; Jensen, Dennis M

    2009-12-01

    Upper gastrointestinal bleeding from peptic ulcer disease is a common clinical event, resulting in considerable patient morbidity and significant health care costs. Inhibiting gastric acid secretion is a key component in improving clinical outcomes, including reducing rebleeding, transfusion requirements, and surgery. Raising intragastric pH promotes clot stability and reduces the influences of gastric acid and pepsin. Patients with high-risk stigmata for ulcer bleeding (arterial bleeding, nonbleeding visible vessels, and adherent clots) benefit significantly from and should receive high-dose intravenous proton pump inhibitors (PPIs) after successful endoscopic hemostasis. For patients with low-risk stigmata (flat spots or clean ulcer base), oral PPI therapy alone is sufficient. For oozing bleeding (an intermediate risk finding), successful endoscopic hemostasis and oral PPI are recommended. Using intravenous PPIs before endoscopy appears to reduce the frequency of finding high-risk stigmata on later endoscopy, but has not been shown to improve clinical outcomes. High-dose oral PPIs may be as effective as intravenous infusion in achieving positive clinical outcomes, but this has not been documented by randomized studies and its cost-effectiveness is unclear.

  7. Nanofiltration and granular activated carbon treatment of perfluoroalkyl acids.

    PubMed

    Appleman, Timothy D; Dickenson, Eric R V; Bellona, Christopher; Higgins, Christopher P

    2013-09-15

    Perfluoroalkyl acids (PFAAs) are of concern because of their persistence in the environment and the potential toxicological effects on humans exposed to PFAAs through a variety of possible exposure routes, including contaminated drinking water. This study evaluated the efficacy of nanofiltration (NF) and granular activated carbon (GAC) adsorption in removing a suite of PFAAs from water. Virgin flat-sheet NF membranes (NF270, Dow/Filmtec) were tested at permeate fluxes of 17-75 Lm(-2)h(-1) using deionized (DI) water and artificial groundwater. The effects of membrane fouling by humic acid on PFAA rejection were also tested under constant permeate flux conditions. Both virgin and fouled NF270 membranes demonstrated >93% removal for all PFAAs under all conditions tested. GAC efficacy was tested using rapid small-scale columns packed with Calgon Filtrasorb300 (F300) carbon and DI water with and without dissolved organic matter (DOM). DOM effects were also evaluated with F600 and Siemens AquaCarb1240C. The F300 GAC had <20% breakthrough of all PFAAs in DI water for up to 125,000 bed volumes (BVs). When DOM was present, >20% breakthrough of all PFAAs by 10,000 BVs was observed for all carbons.

  8. Production of γ-Amino Butyric Acid in Tea Leaves wit Treatment of Lactic Acid Bacteria

    NASA Astrophysics Data System (ADS)

    Watanabe, Yuko; Hayakawa, Kiyoshi; Ueno, Hiroshi

    Lactic acid bacteria was searched for producing termented tea that contained a lot of γ-amino butyric acid(GABA). Also examined were the growth condition, GABA production and changes in catechin contents in the tea leaves. Lactobacillus brevis L12 was found to be suitable for the production of fermented tea since it gave as much GABA as gabaron tea when tea leaves being suspended with water at 10% and incubated for 4 days at 25°C. The amount of GABA produced was more than calculated based upon the content of glutamic acid in tea leaves. It is probable to assume that glutamate derived from glutamine and theanine is converted into GABA.

  9. Study on sapphire microstructure processing technology based on wet etching

    NASA Astrophysics Data System (ADS)

    Shang, Ying-Qi; Qi, Hong; Ma, Yun-Long; Wu, Ya-Lin; Zhang, Yan; Chen, Jing

    2017-03-01

    Aiming at the problem that sapphire surface roughness is quite large after wet etching in sapphire microstructure processing technology, we optimize the wet etching process parameters, study on the influences of concentration and temperature of etching solution and etching time on the sapphire surface roughness and etching rate, choose different process parameters for the experiment and test and analyze the sapphire results after wet etching. Aiming at test results, we also optimize the process parameters and do experiment. Experimental results show that, after optimizing the parameters of etching solution, surface roughness of etched sapphire is 0.39 nm, effectively with reduced surface roughness, improved light extraction efficiency and meeting the production requirements of high-precision optical pressure sensor.

  10. Doxycycline as a matrix metalloproteinase inhibitor to prevent bond degradation: the effect of acid and neutral solutions on dentin bond strength.

    PubMed

    Oliveira, Hellen de Lacerda; Tedesco, Tamara Kerber; Rodrigues-Filho, Leonardo Eloy; Soares, Fabio Zovico Maxnuck; Rocha, Rachel de Oliveira

    2016-01-01

    The aim of this in vitro study was to evaluate the pH effect of doxycycline solutions on the immediate dentin bond strength of a total-etch adhesive system. Twenty human molars were divided into 4 groups (n = 5) after acid etching according to surface treatment: 10% acidic doxycycline, 10% neutral doxycycline, 2% chlorhexidine, and control. Composite resin blocks were made and subjected to microtensile testing. Mean bond strength values were submitted to a 1-way analysis of variance and a Tukey test (α = 0.05). No statistically significant differences between the experimental groups were found (P = 0.093). The chlorhexidine group showed the highest number of pretesting failures. The application of either acidic or neutral doxycycline solution prior to the dentin adhesive did not influence the bond strength of the total-etch adhesive system evaluated.

  11. Bone-bonding properties of Ti metal subjected to acid and heat treatments.

    PubMed

    Kawai, Toshiyuki; Takemoto, Mitsuru; Fujibayashi, Shunsuke; Neo, Masashi; Akiyama, Haruhiko; Yamaguchi, Seiji; Pattanayak, Deepak K; Matsushita, Tomiharu; Nakamura, Takashi; Kokubo, Tadashi

    2012-12-01

    The effects of surface treatment on the bone-bonding properties of Ti metal were examined by both mechanical detaching test and histological observation after implantation into rabbit tibiae for various periods ranging from 4 to 26 weeks. The bone-bonding ability of Ti metal, which is extremely low as it is abraded, was hardly increased by simple heat treatment at 600 °C or treatment with H(2)SO(4)/HCl mixed acid alone, but was markedly increased by the heat treatment after the acid treatment. Even Ti metal that had been previously subjected to NaOH treatment showed considerably high bone-bonding ability after acid and heat treatments. Such high bonding abilities were attributed to their high apatite-forming ability in the body environment. Their high apatite-forming abilities were attributed to a high positive surface charge, and not to the type of crystalline phase or specific roughness of their surfaces. The present study has demonstrated that acid and subsequent heat treatments are effective for conferring stable fixation properties on Ti metal implants.

  12. Phytic acid as a potential treatment for Alzheimer's pathology: evidence from animal and in vitro models

    PubMed Central

    Anekonda, Thimmappa S.; Wadsworth, Teri L.; Sabin, Robert; Frahler, Kate; Harris, Christopher; Petriko, Babett; Ralle, Martina; Woltjer, Randy; Quinn, Joseph F.

    2010-01-01

    Alzheimer’s disease (AD) causes progressive age-dependent cortical and hippocampal dysfunctions leading to abnormal intellectual capacity and memory. We propose a novel protective treatment for AD pathology with phytic acid (inositol hexakisphosphate), a phytochemical found in food grains and a key signaling molecule in mammalian cells. We evaluated the protective and beneficial effects of phytic acid against amyloid beta pathology in MC65 cells and the Tg2576 mouse model. In MC65 cells, 48–72-hour treatment with phytic acid provided complete protection against amyloid precursor protein-C-terminal fragment-induced cytotoxicity by attenuating levels of increased intracellular calcium, hydrogen peroxide, superoxide, beta amyloid oligomers, and moderately up-regulated the expression of autophagy (beclin-1) protein. In a tolerance paradigm, wild type mice were treated with 2% phytic acid in drinking water for 70 days. Phytic acid was well tolerated. Ceruloplasmin activity, brain copper and iron levels and brain superoxide dismutase and ATP levels were unaffected by the treatment. There was a significant increase in brain levels of cytochrome oxidase and a decrease in lipid peroxidation with phytic acid administration. In a treatment paradigm, 12-month old Tg2576 and wild type mice were treated with 2% phytic acid or vehicle for 6 months. Brain levels of copper, iron, and zinc were unaffected. The effects of phytic acid were modest on the expression of APP trafficking-associated protein AP180, autophagy-associated proteins (beclin-1, LC3B), sirtuin 1, the ratio of phosphorylated AMP-activated protein kinase (PAMPK) to AMPK, soluble Aβ1-40, and insoluble Aβ1-42. These results suggest that phytic acid may provide a viable treatment option for AD. PMID:20930278

  13. Phytic acid as a potential treatment for alzheimer's pathology: evidence from animal and in vitro models.

    PubMed

    Anekonda, Thimmappa S; Wadsworth, Teri L; Sabin, Robert; Frahler, Kate; Harris, Christopher; Petriko, Babett; Ralle, Martina; Woltjer, Randy; Quinn, Joseph F

    2011-01-01

    Alzheimer's disease (AD) causes progressive, age-dependent cortical and hippocampal dysfunction leading to abnormal intellectual capacity and memory. We propose a novel protective treatment for AD pathology with phytic acid (inositol hexakisphosphate), a phytochemical found in food grains and a key signaling molecule in mammalian cells. We evaluated the protective and beneficial effects of phytic acid against amyloid-β (Aβ) pathology in MC65 cells and the Tg2576 mouse model. In MC65 cells, 48-72-hour treatment with phytic acid provided complete protection against amyloid precursor protein-C-terminal fragment-induced cytotoxicity by attenuating levels of increased intracellular calcium, hydrogen peroxide, superoxide, Aβ oligomers, and moderately upregulated the expression of autophagy (beclin-1) protein. In a tolerance paradigm, wild type mice were treated with 2% phytic acid in drinking water for 70 days. Phytic acid was well tolerated. Ceruloplasmin activity, brain copper and iron levels, and brain superoxide dismutase and ATP levels were unaffected by the treatment. There was a significant increase in brain levels of cytochrome oxidase and a decrease in lipid peroxidation with phytic acid administration. In a treatment paradigm, 12-month old Tg2576 and wild type mice were treated with 2% phytic acid or vehicle for 6 months. Brain levels of copper, iron, and zinc were unaffected. The effects of phytic acid were modest on the expression of AβPP trafficking-associated protein AP180, autophagy-associated proteins (beclin-1, LC3B), sirtuin 1, the ratio of phosphorylated AMP-activated protein kinase (PAMPK) to AMPK, soluble Aβ1-40, and insoluble Aβ1-42. These results suggest that phytic acid may provide a viable treatment option for AD.

  14. Etch Profile Simulation Using Level Set Methods

    NASA Technical Reports Server (NTRS)

    Hwang, Helen H.; Meyyappan, Meyya; Arnold, James O. (Technical Monitor)

    1997-01-01

    Etching and deposition of materials are critical steps in semiconductor processing for device manufacturing. Both etching and deposition may have isotropic and anisotropic components, due to directional sputtering and redeposition of materials, for example. Previous attempts at modeling profile evolution have used so-called "string theory" to simulate the moving solid-gas interface between the semiconductor and the plasma. One complication of this method is that extensive de-looping schemes are required at the profile corners. We will present a 2D profile evolution simulation using level set theory to model the surface. (1) By embedding the location of the interface in a field variable, the need for de-looping schemes is eliminated and profile corners are more accurately modeled. This level set profile evolution model will calculate both isotropic and anisotropic etch and deposition rates of a substrate in low pressure (10s mTorr) plasmas, considering the incident ion energy angular distribution functions and neutral fluxes. We will present etching profiles of Si substrates in Ar/Cl2 discharges for various incident ion energies and trench geometries.

  15. Technique for etching monolayer and multilayer materials

    DOEpatents

    Bouet, Nathalie C. D.; Conley, Raymond P.; Divan, Ralu; Macrander, Albert

    2015-10-06

    A process is disclosed for sectioning by etching of monolayers and multilayers using an RIE technique with fluorine-based chemistry. In one embodiment, the process uses Reactive Ion Etching (RIE) alone or in combination with Inductively Coupled Plasma (ICP) using fluorine-based chemistry alone and using sufficient power to provide high ion energy to increase the etching rate and to obtain deeper anisotropic etching. In a second embodiment, a process is provided for sectioning of WSi.sub.2/Si multilayers using RIE in combination with ICP using a combination of fluorine-based and chlorine-based chemistries and using RF power and ICP power. According to the second embodiment, a high level of vertical anisotropy is achieved by a ratio of three gases; namely, CHF.sub.3, Cl.sub.2, and O.sub.2 with RF and ICP. Additionally, in conjunction with the second embodiment, a passivation layer can be formed on the surface of the multilayer which aids in anisotropic profile generation.

  16. Effects of chemical etching on the surface quality and the laser induced damage threshold of fused silica optics

    NASA Astrophysics Data System (ADS)

    Pfiffer, Mathilde; Cormont, Philippe; Néauport, Jérôme; Lambert, Sébastien; Fargin, Evelyne; Bousquet, Bruno; Dussauze, Marc

    2016-12-01

    Effects of deep wet etching on the surface quality and the laser induced damage probability have been studied on fused silica samples. Results obtained with a HF/HNO3 solution and a KOH solution were compared on both polished pristine surface and scratched surfaces. The hydrofluoric solution radically deteriorated the surface quality creating a haze on the whole surface and increasing considerably the roughness. For both solutions, neither improvement nor deterioration of the laser damage performances has been observed on the etched surfaces while the laser damage resistance of scratches has been increased to the level of the surface. We conclude that laser damage performances are equivalent with both solutions but an acid etching induces surface degradation that is not experienced with basic etching.

  17. Factors Governing the Emergence of Resistance to Nalidixic Acid in Treatment of Urinary Tract Infection

    PubMed Central

    Greenwood, David; O'Grady, Francis

    1977-01-01

    Cultures of Escherichia coli were exposed to nalidixic acid in an in vitro model in which the conditions of drug-organism interaction resembled those of bacterial cystitis treatment. Results obtained in this way suggested that emergence of bacterial resistance should not be a major problem in treatment of uncomplicated urinary infection; such cases might indeed respond to a less intensive course of treatment than is usual. More prolonged, high-dosage therapy with nalidixic acid may be required for patients with more complicated infections if the risk of failure from the emergence of bacterial resistance is to be minimized. PMID:337890

  18. A postmarketing surveillance study of dexrabeprazole in the treatment of acid peptic disorders.

    PubMed

    Jain, S C

    2009-02-01

    Dexrabeprazole [R(+) rabeprazole] is a novel proton-pump inhibitor which has recently become available in India for the treatment of acid peptic diseases. Experimental and clinical studies have shown superiority of dexrabeprazole (at half the recommended rabeprazole dose) over rabeprazole in terms of favourable pharmacokinetics, better efficacy and faster and greater healing activity. Results of present study in a large population of 4931 patients of acid peptic disorders, reconfirmed safety and efficacy of dexrabeprazole 10 mg once daily in the treatment of gastro-oesophageal reflux disease and also showed its effectiveness in the treatment of patients with peptic ulcers (gastric/duodenal).

  19. Wet KOH etching of freestanding AlN single crystals

    NASA Astrophysics Data System (ADS)

    Bickermann, M.; Schmidt, S.; Epelbaum, B. M.; Heimann, P.; Nagata, S.; Winnacker, A.

    2007-03-01

    We investigated defect-selective wet chemical etching of freestanding aluminum nitride (AlN) single crystals and polished cuts in a molten NaOH-KOH eutectic at temperatures ranging from 240 to 400 °C. Due to the strong anisotropy of the AlN wurtzite structure, different AlN faces get etched at very different etching rates. On as-grown rhombohedral and prismatic facets, defect-related etching features could not be traced, as etching these facets was found to mainly emphasize features present already on the un-etched surface. On nitrogen polar basal planes, hexagonal pyramids/hillocks exceeding 100 μm in diameter may form within seconds of etching at 240 °C. They sometimes are arranged in lines and clusters, thus we attribute them to defects on the surface, presumably originating in the bulk material. On aluminum polar basal planes, the etch pit density which saturates after approx. 2-3 min of total etching time at 350 °C equals the density of a certain type of dislocations (presumably screw dislocations) threading the surface. Smaller etch pits form around annealed indentations, in the vicinity of some bigger etch pits after repeated etching, and sometimes also isolated on the surface area. Although alternate explanations exist, we attribute these etch pits to threading mixed and edge dislocations. This paper features etching parameters optimized for different planes and models on the formation of etching features especially on the polar faces. Finally, the issue of reliability and reproducibility of defect detection and evaluation by wet chemical etching is addressed.

  20. High index contrast polysiloxane waveguides fabricated by dry etching

    SciTech Connect

    Madden, S. J.; Zhang, M. Y.; Choi, D.-Y.; Luther-Davies, B.; Charters, R.

    2009-05-15

    The authors demonstrate the production of low loss enhanced index contrast waveguides by reactive ion etching of IPG trade mark sign polysiloxane thin films. The use of a silica mask and CHF{sub 3}/O{sub 2} etch gas led to large etch selectivity between the silica and IPG trade mark sign of >20 and etch rates of >100 nm/min. This work indicates that compact optical circuits could be successfully fabricated for telecommunication applications using polysiloxane films.

  1. Comparison of trichostatin A and valproic acid treatment regimens in a mouse model of kidney fibrosis

    SciTech Connect

    Van Beneden, Katrien; Geers, Caroline; Pauwels, Marina; Mannaerts, Inge; Wissing, Karl M.; Van den Branden, Christiane; Grunsven, Leo A. van

    2013-09-01

    Histone deacetylase (HDAC) inhibitors are promising new compounds for the therapy of fibrotic diseases. In this study we compared the effect of two HDAC inhibitors, trichostatin A and valproic acid, in an experimental model of kidney fibrosis. In mice, doxorubicin (adriamycin) can cause nephropathy characterized by chronic proteinuria, glomerular damage and interstitial inflammation and fibrosis, as seen in human focal segmental glomerulosclerosis. Two treatment regimens were applied, treatment was either started prior to the doxorubicin insult or delayed until a significant degree of proteinuria and fibrosis was present. Pre-treatment of trichostatin A significantly hampered glomerulosclerosis and tubulointerstitial fibrosis, as did the pre-treatment with valproic acid. In contrast, the development of proteinuria was only completely inhibited in the pre-treated valproic acid group, and not in the pre-treated trichostatin A animals. In the postponed treatment with valproic acid, a complete resolution of established doxorubicin-induced proteinuria was achieved within three days, whereas trichostatin A could not correct proteinuria in such a treatment regimen. However, both postponed regimens have comparable efficacy in maintaining the kidney fibrosis to the level reached at the start of the treatments. Moreover, not only the process of fibrosis, but also renal inflammation was attenuated by both HDAC inhibitors. Our data confirm a role for HDACs in renal fibrogenesis and point towards a therapeutic potential for HDAC inhibitors. The effect on renal disease progression and manifestation can however be different for individual HDAC inhibitors. - Highlights: • Valproic acid is a potent antiproteinuric drug, whereas trichostatin A is not. • Trichostatin A and valproic acid reduce kidney fibrosis in doxorubicin nephropathy. • Both valproic acid and trichostatin A attenuate renal inflammation.

  2. Comprehensive Treatment of Periorbital Region with Hyaluronic Acid

    PubMed Central

    Rocha, Camila Roos Mariano Da; Bastos, Julien Toni De; Silva, Priscila Mara Chaves e

    2015-01-01

    The periorbital subunit is one of the first facial regions to show signs of aging, primarily due to volume depletion of the soft tissue and bony resorption. Surgical and office-based nonsurgical procedures form an important basis for periorbital rejuvenation. It is important to make a detailed clinical evaluation of the patient to indicate the most appropriate procedure to be performed. With the objective of showing a nonsurgical procedure for the rejuvenation of the periorbital area, the authors describe a technique of applying fillers in the upper and lower periorbital regions, paying attention to the anatomy of this facial region and the type of product to be used besides the expected results of the procedure and its possible adverse effects and complications. The nonsurgical rejuvenation of the periorbicular region with hyaluronic acid is a new and innovative technique. In the opinion of the authors, it is a great aesthetic impact area and consequently brings high satisfaction to patients. PMID:26155325

  3. Downhole seismic monitoring of an acid treatment in the Beowawe Geothermal Field

    SciTech Connect

    Batra, R.; Albright, J.N.; Bradley, C.

    1984-01-01

    During the acid treatment of a subeconomic well at the Beowawe Geothermal Field, numerous seismic events were detected of which 22 could be located. The events occurred following a first stage of the acid treatment and generally define a trend paralleling the surface trace of the Malpais fault. No seismic signals were detected following a second stage of the acid treatment, despite the injection of almost twice as much additional fluid. It is postulated that the cause of seismic events following the first stage was due to shear failure of chemically weakened cemented fracturs or joints in the reservoir. Presumably reservoir strain was sufficiently reduced to preclude further rock failure during the second day of treatment.

  4. Use of lower-end technology etch platforms for high-etch loads

    NASA Astrophysics Data System (ADS)

    Nemelka, Jefferson O.

    2003-12-01

    In order to meet the needs of multiple customers with varying design specifications, merchant photomask suppliers need to provide photomasks for a wide range of design patterns. Some masks require etching less than 1% of the total mask film, while others require etching over 80% of the mask. Etching masks with these extremes in pattern loads can often require upgrading existing tool sets, particularly as the mask specifications become tighter. One alternative to upgrading tools is to develop new load-specific processes on existing lower-end tools, which requires a substantial amount of development work. Dry etching MoSi Embedded Attenuating Phase Shift Material using sulfur hexafluoride and helium under all etch loads presents challenges in the Unaxis Generation II mask etch platform. Etch processes developed for low load masks cannot always be used for high load masks due to problems in maintaining a stable process with good performance. In order to improve the etch performance for high MoSi loads (> 70% clear), a Gen II specific hardware design which can adversely affect uniformity at high loads was identified and eliminated as a dominant source of non-uniformity. A DOE studying total gas flow, He/SF6 ratio, pressure, ICP, and RIE power was then used to identify a stable process window for high MoSi loads. Another DOE studying the effects of pressure, ICP power, and RIE power on process uniformity was then carried out within the stable process window. Process conditions were identified which produced highly loaded 248nm and 193nm EAPSM masks with phase uniformity below 3°. Sidewall profiles were vertical for 193nm MoSi films but were slightly tapered for 248nm MoSi films, both with less than 5nm of CD bias.

  5. Wettability investigating on the wet etching textured multicrystalline silicon wafer

    NASA Astrophysics Data System (ADS)

    Liu, Xiangju; Niu, Yuchao; Zhai, Tongguang; Ma, Yuying; Zhen, Yongtai; Ma, Xiaoyu; Gao, Ying

    2016-02-01

    In order to investigate the wettability properties of multicrystalline silicon (mc-Si), the different surface structures were fabricated on the as-cut p-type multi-wire slurry sawn mc-Si wafers, such as as-cut, polished and etched in various acid solutions. The contact angles and the XRD spectra of these samples were measured. It was noted that both the surface structures and the use of surfactant, such as Tween 80, made a stronger effect on wettability of the Si wafer. Due to the lipophilic groups of Tween 80 combined with the Si atoms while the hydrophilic groups of it were outward, a lipophilic surface of Si changed into a hydrophilic one and the rougher the surface, the stronger the hydrophily. Thus, it is feasible to add an appropriate surfactant into the etching solution during black-Si wafer fabrication for solar cells. In addition, different crystal plains of Si had different dangling bond density, so that their surface energies were different. A surface with higher surface energy could attract more water atoms and its wettability was better. However, the effect of crystal plain on the surface wettability was much weaker than surface morphology.

  6. CR-39 track etching and blow-up method

    DOEpatents

    Hankins, Dale E.

    1987-01-01

    This invention is a method of etching tracks in CR-39 foil to obtain uniformly sized tracks. The invention comprises a step of electrochemically etching the foil at a low frequency and a "blow-up" step of electrochemically etching the foil at a high frequency.

  7. New phase formation in titanium aluminide during chemical etching

    SciTech Connect

    Takasaki, Akito; Ojima, Kozo; Taneda, Youji . Dept. of Mathematics and Physics)

    1994-05-01

    A chemical etching technique is widely used for metallographic observation. Because this technique is based on a local corrosion phenomenon on a sample, the etching mechanism, particularly for two-phase alloys, can be understood by electrochemical consideration. This paper describes formation of a new phase in a Ti-45Al (at.%) titanium aluminide during chemical etching, and the experimental results are discussed electrochemically.

  8. Dopant Selective Reactive Ion Etching of Silicon Carbide

    NASA Technical Reports Server (NTRS)

    Okojie, Robert (Inventor)

    2016-01-01

    A method for selectively etching a substrate is provided. In one embodiment, an epilayer is grown on top of the substrate. A resistive element may be defined and etched into the epilayer. On the other side of the substrate, the substrate is selectively etched up to the resistive element, leaving a suspended resistive element.

  9. Corn starch granules with enhanced load-carrying capacity via citric acid treatment.

    PubMed

    Kim, Jong-Yea; Huber, Kerry C

    2013-01-02

    This research investigated conditions by which maize starch granule porosity and load-carrying capacity (LCC) might be enhanced via treatment with varying citric acid concentrations (0.5-1.5 M), temperatures (40-60 °C), and lengths of treatment (1-8 h). At the lowest temperatures (40 and 50 °C), citric acid treatment induced minimal physicochemical changes to granules. In contrast, both aqueous and oil LCCs of starches treated at 60 °C (0.5 M citric acid, 2 h) were almost doubled (15.69 and 14.48 mL/10 g starch, respectively), recovering 92% of the granular starch after treatment. Such treatment increased starch hydration capacity (0.97-1.91) and reduced gelatinization enthalpy (10.6-7.4 J/g). More severe treatment conditions adversely impacted aqueous LCC (due to excessive granule swelling), but improved oil absorption. The basis for LCC enhancement by citric acid treatment was ascribed to leaching of starch material from granules and partial disruption of the granule crystalline structure, as opposed to starch hydrolysis or chemical substitution.

  10. Virulence of viable but nonculturable S. Typhimurium LT2 after peracetic acid treatment.

    PubMed

    Jolivet-Gougeon, A; Sauvager, F; Bonnaure-Mallet, M; Colwell, R R; Cormier, M

    2006-11-01

    S. Typhimurium LT2 cells suspended in sterilized sewage effluent water (SEW) and in distilled water microcosms were exposed to 0, 7, 15 and 20 mg/l peracetic acid, and tested for viability and virulence. After treatment for one hour, colony forming units decreased by at least 5 log units at peracetic acid concentration of 7 mg/l. In SEW, at peracetic acid concentration of 15 mg/l, the cells were nonculturable (VNC), but retained virulence as demonstrated by invasion assays of HeLa cells. Higher concentrations (greater than or equal to 20 mg/l) resulted in bacterial death, i.e. substrate non-responsive cells. Despite morphological alterations of the bacteria after peracetic acid treatment, visualized by transmission electronic microscopy, conservation of both adhesive and invasive capacities was confirmed by scanning electron microscopy after exposure to 0-15 mg/l peracetic acid. Public health professionals need to recognize that peracetic acid-treated Salmonella is capable of modifying its physiological characteristics, including entering and recovering from the viable but nonculturable state, and may remain virulent after a stay in SEW followed by peracetic acid treatment.

  11. Therapeutic paracetamol treatment in older persons induces dietary and metabolic modifications related to sulfur amino acids.

    PubMed

    Pujos-Guillot, Estelle; Pickering, Gisèle; Lyan, Bernard; Ducheix, Gilles; Brandolini-Bunlon, Marion; Glomot, Françoise; Dardevet, Dominique; Dubray, Claude; Papet, Isabelle

    2012-02-01

    Sulfur amino acids are determinant for the detoxification of paracetamol (N-acetyl-p-aminophenol) through sulfate and glutathione conjugations. Long-term paracetamol treatment is common in the elderly, despite a potential cysteine/glutathione deficiency. Detoxification could occur at the expense of anti-oxidative defenses and whole body protein stores in elderly. We tested how older persons satisfy the extra demand in sulfur amino acids induced by long-term paracetamol treatment, focusing on metabolic and nutritional aspects. Effects of 3 g/day paracetamol for 14 days on fasting blood glutathione, plasma amino acids and sulfate, urinary paracetamol metabolites, and urinary metabolomic were studied in independently living older persons (five women, five men, mean (±SEM) age 74 ± 1 years). Dietary intakes were recorded before and at the end of the treatment and ingested sulfur amino acids were evaluated. Fasting blood glutathione, plasma amino acids, and sulfate were unchanged. Urinary nitrogen excretion supported a preservation of whole body proteins, but large-scale urinary metabolomic analysis revealed an oxidation of some sulfur-containing compounds. Dietary protein intake was 13% higher at the end than before paracetamol treatment. Final sulfur amino acid intake reached 37 mg/kg/day. The increase in sulfur amino acid intake corresponded to half of the sulfur excreted in urinary paracetamol conjugates. In conclusion, older persons accommodated to long-term paracetamol treatment by increasing dietary protein intake without any mobilization of body proteins, but with decreased anti-oxidative defenses. The extra demand in sulfur amino acids led to a consumption far above the corresponding population-safe recommendation.

  12. Modeling and optimizing the design of matrix treatments in carbonate reservoirs with self-diverting acid systems

    NASA Astrophysics Data System (ADS)

    Bulgakova, G. T.; Kharisov, R. Ya; Sharifullin, A. R.; Pestrikov, A. V.

    2015-01-01

    Application of a self-diverting-acid based on viscoelastic surfactant (SDVA) is a promising technology for improving the efficacy of acid treatment in oil and gas-bearing carbonate reservoirs. In this study, we present a mathematical model for assessing SDVA flow and reaction with carbonate rock using the SDVA rheological characteristics. The model calculates the technological parameters for acidizing operations and the prediction of well productivity after acid treatment, in addition to technical and economic optimization of the acidizing process by modeling different acid treatment options with varying volumes, injection rates, process fluids stages and initial economic scenarios.

  13. Etching of polymers, proteins and bacterial spores by atmospheric pressure DBD plasma in air

    NASA Astrophysics Data System (ADS)

    Kuzminova, A.; Kretková, T.; Kylián, O.; Hanuš, J.; Khalakhan, I.; Prukner, V.; Doležalová, E.; Šimek, M.; Biederman, H.

    2017-04-01

    Many studies proved that non-equilibrium discharges generated at atmospheric pressure are highly effective for the bio-decontamination of surfaces of various materials. One of the key processes that leads to a desired result is plasma etching and thus the evaluation of etching rates of organic materials is of high importance. However, the comparison of reported results is rather difficult if impossible as different authors use diverse sources of atmospheric plasma that are operated at significantly different operational parameters. Therefore, we report here on the systematic study of the etching of nine different common polymers that mimic the different structures of more complicated biological systems, bovine serum albumin (BSA) selected as the model protein and spores of Bacillus subtilis taken as a representative of highly resistant micro-organisms. The treatment of these materials was performed by means of atmospheric pressure dielectric barrier discharge (DBD) sustained in open air at constant conditions. All tested polymers, BSA and spores, were readily etched by DBD plasma. However, the measured etching rates were found to be dependent on the chemical structure of treated materials, namely on the presence of oxygen in the structure of polymers.

  14. Influence of nitric acid treatment in different media on X-ray structural parameters of coal

    SciTech Connect

    Sudip Maity; Ashim Choudhury

    2008-11-15

    The treatment of coal with nitric acid in aqueous and non-aqueous media introduces changes in the chemical and spatial structure of the organic mass. Four coals of different rank have been treated with nitric acid in aqueous and glacial acetic acid media for assessing the changes in the structural parameters by the X-ray diffraction (XRD) technique. Slow-scan XRD has been performed for the raw and treated coals, and X-ray structural parameters (d002, Lc, and Nc) and aromaticity (fa) have been determined by profile-fitting software. Considerable variation of the structural parameters has been observed with respect to the raw coals. The d002 values have decreased in aqueous medium but increased in acetic acid medium; however, Lc, Nc, and fa values have increased in aqueous medium but decreased in acetic acid medium. It is also observed that considerable oxidation takes place during nitric acid treatment in aqueous medium, but nitration is the predominant phenomenon in acetic acid medium. Disordering of the coal structure increases in acetic acid medium, but a reverse trend is observed in the aqueous medium. As a result, structurally modified coals (SMCs) are derived as new coal-derived substances. 15 refs., 6 figs., 3 tabs.

  15. Emission Properties of Porous Silicon Electron Emitters Formed by Pulsed Anodic Etching

    NASA Astrophysics Data System (ADS)

    Hu, W. B.; Zhao, W.; Fan, J. L.; Wu, S. L.; Zhang, J. T.

    2017-02-01

    Porous silicon (PS) layers were formed by pulsed anodic etching and subsequently processed by electrochemical oxidization (ECO) and high-pressure water vapor annealing (HWA), and their morphologies and oxidation degrees were analyzed. The electron emitters based on these PS layers were fabricated, and their emission properties were investigated. The experimental results show that a PS layer formed by pulsed anodic etching has a better pore-diameter homogeneity in the longitudinal direction, and it can obtain good oxidation quality more easily by the combined treatment of ECO and HWA. The as-formed PS electron emitters have better emission properties in comparison with those based on PS layers prepared by constant-current anodic etching.

  16. Alleviation of postharvest chilling injury of tomato fruit by salicylic acid treatment.

    PubMed

    Aghdam, Morteza Soleimani; Asghari, Mohammadreza; Khorsandi, Orojali; Mohayeji, Mehdi

    2014-10-01

    Tomato fruit at the mature green stage were treated with salicylic acid at different concentration (0, 1 and 2 mM) and analyzed for chilling injury (CI), electrolyte leakage (EL), malondialdehyde (MDA) and proline contents and phospholipase D (PLD) and lipoxygenase (LOX) activities during cold storage. PLD and LOX activities were significantly reduced by salicylic acid treatment. Compared with the control fruit, salicylic acid treatment alleviated chilling injury, reduced electrolyte leakage, malondialdehyde content and increased proline content. Our result suggest that the reduce activity of PLD and LOX, by salicylic acid may be a chilling tolerance strategy in tomato fruit. Inhibition of PLD and LOX activity during low temperature storage could ameliorate chilling injury and oxidation damage and enhance membrane integrity in tomato fruit.

  17. Is total-etch dead? Evidence suggests otherwise.

    PubMed

    Alex, Gary

    2012-01-01

    Both the total-etch and self-etching systems of today have the potential to provide durable adhesive interface, and despite the proclamations of some, total-etch is alive and well. Indeed, evidence indicates that a viable and growing market remains for total-etch adhesive systems. This paper will discuss the origins, evolution, and idiosyncrasies of the total-etch technique as well as its place in dentistry today. New innovations, the use of antimicrobials to inhibit matrix metalloproteinases (MMPs), and sensitivity issues will also be discussed.

  18. Chemically assisted ion beam etching of polycrystalline and (100)tungsten

    NASA Technical Reports Server (NTRS)

    Garner, Charles

    1987-01-01

    A chemically assisted ion-beam etching technique is described which employs an ion beam from an electron-bombardment ion source and a directed flux of ClF3 neutrals. This technique enables the etching of tungsten foils and films in excess of 40 microns thick with good anisotropy and pattern definition over areas of 30 sq mm, and with a high degree of selectivity. (100) tungsten foils etched with this process exhibit preferred-orientation etching, while polycrystalline tungsten films exhibit high etch rates. This technique can be used to pattern the dispenser cathode surfaces serving as electron emitters in traveling-wave tubes to a controlled porosity.

  19. Formic acid-based treatments for control of Varroa destructor in a Mediterranean area.

    PubMed

    Satta, Alberto; Floris, Ignazio; Eguaras, Martin; Cabras, Paolo; Garau, Vincenzo Luigi; Melis, Marinella

    2005-04-01

    Two formic acid autumnal treatments, gel packets (BeeVar formulation) and impregnated paperwick (Liebig-Dispenser), were tested in apiary to evaluate their effectiveness against Varroa destructor Anderson & Trueman and their residues in honey in a Mediterranean region (Sardinia, Italy). Both treatments were efficient in the apiary control of the varroosis, with values of percentage of mite mortality ranging between 93.6 and 100%, without statistical differences between them. The more gradual release of formic acid from the gel application allowed a longer action (2 wk for each treatment) compared with the Liebig-Dispenser (approximately 3d for each treatment). The rate of daily evaporation ranged between approximately 5 and 9 g/d from BeeVar and approximately 26 and 35 g/d from the Liebig-Dispenser, in the first and second treatment, respectively. The total amount of formic acid administered per hive during all the treatment period was approximately 200 g for either treatment. A significantly higher adult bee mortality was recorded in the Liebig-Dispenser-treated hives compared with the BeeVar-treated group. On the contrary, BeeVar treatment produced an interruption of brood reared, whereas the extension of the sealed brood area of the Liebig-Dispenser-treated hives was not significantly different from that of the control hives. Neither queen mortality nor robbing activity was observed due to the treatments. Formic acid residues in honey collected in the nest were 3,855 +/- 2,061 and 3,030 +/- 1,624 mg/kg for the BeeVar- and the Liebig-Dispenser-treated hives, respectively. After 21 d from the end of the treatment, the residues fell to 1,261 +/- 1,054 and 794 +/- 518 mg/kg for the honey sampled from the BeeVar and Liebig-Dispenser groups, respectively.

  20. Micromorphology and bond strength evaluation of adhesive interface of a self-adhering flowable composite resin-dentin: Effect of surface treatment.

    PubMed

    Shafiei, Fereshteh; Saadat, Maryam

    2016-05-01

    This study evaluated the effect of dentin surface treatment on the micromorphology and shear bond strength (SBS) of a self-adhering flowable composite, Vertis Flow (VF). Flat dentin surfaces obtained from sixty extracted human molars were divided into six groups (n = 10) according to the following surface treatments: (G1) control, no treatment; (G2) self-etching adhesive, Optibond All-in-One; (G3) phosphoric acid etching for 15 s; (G4) polyacrylic acid for 10 s; (G5) EDTA for 60 s; and G6) sodium hypochlorite (NaOCl) for 15 s. After restoration using VF, SBS was measured in MPa. Data were analyzed using one-way ANOVA and Tamhane test (α = 0.05). Six additional specimens were prepared for scanning electron microscopy analysis. SBS was significantly affected by surface treatment (P < 0.001). SBS of six groups from the highest to the lowest were as follows: (G3) 13.5(A); (G5) 8.98(AB); (G2) 8.85(AB); (G4) 8.21(AB); (G1) 7.53(BC); and (G6) 4.49(C) (groups with the same superscript letter were statistically similar). Morphological analysis revealed numerous long resin tags at the adhesive interface for acid-etched group, with a few short resin tags for the control group and small gap formation for NaOCl-treated group. In conclusion, dentin surface treatments tested differently affected bonding performance of VF; only acid-etching effectively improved this.

  1. Platelet-derived Factor Concentrates with Hyaluronic Acid Scaffolds for Treatment of Deep Burn Wounds

    PubMed Central

    Minabe, Toshiharu; Yamakawa, Tomomi; Araki, Jun; Sano, Hitomi; Yoshimura, Kotaro

    2016-01-01

    Summary: A deep burn wound is a critical condition that generally necessitates vascularized tissue coverage. We performed the injection of platelet-derived factor concentrates combined with non–cross-linked hyaluronic acid scaffolds for 2 patients with critical burn wounds with bone and tendon exposure and achieved successful healing. Hyaluronic acid was considered to have served as a controlled-release carrier of platelet-derived factors, being clinically effective for the treatment of deep burn wounds. PMID:27826482

  2. Biochemical changes in grape rootstocks resulted from humic acid treatments in relation to nematode infection

    PubMed Central

    Kesba, Hosny H; El-Beltagi, Hossam S

    2012-01-01

    Objective To investigate the effect of humic acid on nematode infected, resistant and susceptible grapes in relation to lipid peroxidation and antioxidant mechanisms on selected biochemical parameters known as proactive substances. Methods The grape rootstocks, superior, superior/freedom and freedom were reacted differently to Meloidogyne incognita and Rotylenchulus reniformis according to rootstock progenitor. Two weeks after inoculation, two commercial products of humic acid were applied at the rate of (2, 4 mL or grams/plant) as soil drench. After 4 months, nematode soil populations were extracted and counted. A subsample of roots from each plant was stained and gall numbers, embedded stages per root were calculated, final population, nematode build up (Pf/Pi), average of eggs/eggmass were estimated. Subsamples of fresh root of each treatment were chemically analyzed. Results Freedom reduced significantly the nematode criteria and build up. Humic acid granules appeared to be more suppressive to nematode build up on superior and the higher dose on superior/freedom than liquid treatments. On freedom, all treatments reduced significantly the nematode build up regardless to the material nature. The higher dose was more effective than the lower one. As a result of humic acid applications, the malondialdehyde (MDA) and H2O2 contents were significantly reduced after humic acid treatments while the antioxidant compounds glutathione (GSH), ascorbic acid (ASA) and total phenol contents were significantly increased when compared with check. Antioxidant defense enzymes ascorbate peroxidase (APX), superoxide dismutase (SOD), catalase (CAT) and polyphenol oxidase (PPO)showed significant increase in their specific activities in treated plants compared with nematode treated check. Conclusions Humic acid treatments improve the yield of grape by increasing the contents of antioxidant compounds and the specific activities of antioxidant enzymes. PMID:23569915

  3. Biomachining: metal etching via microorganisms.

    PubMed

    Díaz-Tena, Estíbaliz; Barona, Astrid; Gallastegui, Gorka; Rodríguez, Adrián; López de Lacalle, L Norberto; Elías, Ana

    2017-05-01

    The use of microorganisms to remove metal from a workpiece is known as biological machining or biomachining, and it has gained in both importance and scientific relevance over the past decade. Conversely to mechanical methods, the use of readily available microorganisms is low-energy consuming, and no thermal damage is caused during biomachining. The performance of this sustainable process is assessed by the material removal rate, and certain parameters have to be controlled for manufacturing the machined part with the desired surface finish. Although the variety of microorganisms is scarce, cell concentration or density plays an important role in the process. There is a need to control the temperature to maintain microorganism activity at its optimum, and a suitable shaking rate provides an efficient contact between the workpiece and the biological medium. The system's tolerance to the sharp changes in pH is quite limited, and in many cases, an acid medium has to be maintained for effective performance. This process is highly dependent on the type of metal being removed. Consequently, the operating parameters need to be determined on a case-by-case basis. The biomachining time is another variable with a direct impact on the removal rate. This biological technique can be used for machining simple and complex shapes, such as series of linear, circular, and square micropatterns on different metal surfaces. The optimal biomachining process should be fast enough to ensure high production, a smooth and homogenous surface finish and, in sum, a high-quality piece. As a result of the high global demand for micro-components, biomachining provides an effective and sustainable alternative. However, its industrial-scale implementation is still pending.

  4. Using 80% trichloroacetic acid in the treatment of ingrown toenails*

    PubMed Central

    Barreiros, Hugo; Matos, Diogo; Goulão, João; Serrano, Pedro; João, Alexandre; Brandão, Francisco Menezes

    2013-01-01

    BACKGROUND Ingrown nails are a very common problem. There are different stages of disease and diverse therapeutic options. Phenol and sodium hydroxide are commonly used agents for chemical matricectomy but both frequently entail excessive healing times. OBJECTIVE This prospective study aimed mainly to evaluate the efficacy of partial nail avulsion and selective chemical cauterization of the matrix using 80% TCA in the treatment of the ingrowing nail. METHODS One-hundred-and-thirty-three patients with 197 ingrown toenails were included in this study. Preoperatively, we tried to find predisposing factors to the disease. In the postoperative period, patients were evaluated for potential complications at days 3, 30, 180, 270 and 360. Pain was measured before surgery, as well as 24 hours and 72 hours after surgery. RESULTS There were only 3 cases (out of 197) of ingrown nail recurrence. Preoperatively, we found the presence of drainage in 82% of patients, which, following the first visit after surgery, was reduced to 19%. Persistent granulation tissue was found in 3% of the patients (versus 75% prior to surgery). The most frequent predisposing factors for the ingrown nail were excessive trimming of the lateral nail plate (63%), plantar hyperhidrosis (58%) and heavy nail folds (39%). Pain was substantially reduced after surgery. CONCLUSION It is assumed that chemical procedures for the ingrown toenail are associated with delayed healing times but our results demonstrated quick recovery. Using 80% TCA for selective matricectomy in the ingrown toenail is an effective, quick and easy method. PMID:24474095

  5. Bulk Etch Rate and Swell Rate of CR-39

    NASA Astrophysics Data System (ADS)

    Clarkson, David; Ume, Rubab; Sheets, Rebecca; Regan, Sean; Sangster, Craig; Padalino, Stephen; McLean, James

    2016-10-01

    The use of CR-39 plastic as a Solid State Nuclear Track Detector is an effective technique for obtaining data in high-energy particle experiments including inertial confinement fusion. To reveal particle tracks after irradiation, CR-39 is chemically etched in NaOH at 80°C, producing micron-scale signal pits at the nuclear track sites. The development of these pits depends on both the bulk etch rate and the faster etch rate along the track, and is complicated by swelling as water is absorbed. Contrary to common etching models, we find the bulk etch rate to be depth dependent within 15 μ m of the surface, as revealed by swelling TASTRACK CR-39 pieces to their maximum capacity prior to etching. The bulk etch rate was measured using the standard mass method as well as the fission fragment track diameter method. Combining models of swelling and etching rates predicts the progress of bulk etching during a standard etch, without pre-swelling. This result has implications for the understanding the chemistry of the etch process, as well as the outcome of CR-39 surface preparation methods. Funded in part by a LLE contract through the DOE.

  6. Evolution of titanium residue on the walls of a plasma-etching reactor and its effect on the polysilicon etching rate

    SciTech Connect

    Hirota, Kosa Itabashi, Naoshi; Tanaka, Junichi

    2014-11-01

    The variation in polysilicon plasma etching rates caused by Ti residue on the reactor walls was investigated. The amount of Ti residue was measured using attenuated total reflection Fourier transform infrared spectroscopy with the HgCdTe (MCT) detector installed on the side of the reactor. As the amount of Ti residue increased, the number of fluorine radicals and the polysilicon etching rate increased. However, a maximum limit in the etching rate was observed. A mechanism of rate variation was proposed, whereby F radical consumption on the quartz reactor wall is suppressed by the Ti residue. The authors also investigated a plasma-cleaning method for the removal of Ti residue without using a BCl{sub 3} gas, because the reaction products (e.g., boron oxide) on the reactor walls frequently cause contamination of the product wafers during etching. CH-assisted chlorine cleaning, which is a combination of CHF{sub 3} and Cl{sub 2} plasma treatment, was found to effectively remove Ti residue from the reactor walls. This result shows that CH radicals play an important role in deoxidizing and/or defluorinating Ti residue on the reactor walls.

  7. Surface engineering of SiC via sublimation etching

    NASA Astrophysics Data System (ADS)

    Jokubavicius, Valdas; Yazdi, Gholam R.; Ivanov, Ivan G.; Niu, Yuran; Zakharov, Alexei; Iakimov, Tihomir; Syväjärvi, Mikael; Yakimova, Rositsa

    2016-12-01

    We present a technique for etching of SiC which is based on sublimation and can be used to modify the morphology and reconstruction of silicon carbide surface for subsequent epitaxial growth of various materials, for example graphene. The sublimation etching of 6H-, 4H- and 3C-SiC was explored in vacuum (10-5 mbar) and Ar (700 mbar) ambient using two different etching arrangements which can be considered as Si-C and Si-C-Ta chemical systems exhibiting different vapor phase stoichiometry at a given temperature. The surfaces of different polytypes etched under similar conditions are compared and the etching mechanism is discussed with an emphasis on the role of tantalum as a carbon getter. To demonstrate applicability of such etching process graphene nanoribbons were grown on a 4H-SiC surface that was pre-patterned using the thermal etching technique presented in this study.

  8. Dry-etch resistance of fluorine functionalized polymers

    NASA Astrophysics Data System (ADS)

    Koh, Meiten; Ishikawa, Takuji; Araki, Takayuki; Aoyama, Hirokazu; Yamashita, Tsuneo; Yamazaki, Tamio; Watanabe, Hiroyuki; Toriumi, Minoru; Itani, Toshiro

    2002-07-01

    The reactive ion etch (RIE) properties of fluorine funtionalized polymers in which fluorine atoms were incorporated in the main chain were examined. There was a tendency that the etching rates of these polymers were higher as lower the fluorine contents. The existing four models such as the Ohnishi model, the Kunz model, the Ohfuji model and the Kishimura model were applied to explain the correlation between the etching rates and the polymer compositions or structures, but the errors were too large to explain the relationship. A new model has developed to explain the effect of the fluorine incorporation to the dry etch resistance. The model assumed that there would be a correlation between the number of main chain fluorine atoms and the dry etch resistance, and the main chain fluorine incorporation would increase the dry etch resistance. The model could explain the dry etch resistance of the main chain fluorine incorporated polymers with adequate accuracy.

  9. Structure dependent hydrogen induced etching features of graphene crystals

    NASA Astrophysics Data System (ADS)

    Thangaraja, Amutha; Shinde, Sachin M.; Kalita, Golap; Papon, Remi; Sharma, Subash; Vishwakarma, Riteshkumar; Sharma, Kamal P.; Tanemura, Masaki

    2015-06-01

    H2 induced etching of graphene is of significant interest to understand graphene growth process as well as to fabricate nanoribbons and various other structures. Here, we demonstrate the structure dependent H2 induced etching behavior of graphene crystals. We synthesized graphene crystals on electro-polished Cu foil by an atmospheric pressure chemical vapor deposition process, where some of the crystals showed hexagonal shaped snowflake-dendritic morphology. Significant differences in H2 induced etching behavior were observed for the snowflake-dendritic and regular graphene crystals by annealing in a gas mixture of H2 and Ar. The regular graphene crystals were etched anisotropically creating hexagonal holes with pronounced edges, while etching of all the dendritic crystals occurred from the branches of lobs creating symmetrical fractal structures. The etching behavior provides important clue of graphene nucleation and growth as well as their selective etching to fabricate well-defined structures for nanoelectronics.

  10. Recent advances in delivery of drug-nucleic acid combinations for cancer treatment.

    PubMed

    Li, Jing; Wang, Yan; Zhu, Yu; Oupický, David

    2013-12-10

    Cancer treatment that uses a combination of approaches with the ability to affect multiple disease pathways has been proven highly effective in the treatment of many cancers. Combination therapy can include multiple chemotherapeutics or combinations of chemotherapeutics with other treatment modalities like surgery or radiation. However, despite the widespread clinical use of combination therapies, relatively little attention has been given to the potential of modern nanocarrier delivery methods, like liposomes, micelles, and nanoparticles, to enhance the efficacy of combination treatments. This lack of knowledge is particularly notable in the limited success of vectors for the delivery of combinations of nucleic acids with traditional small molecule drugs. The delivery of drug-nucleic acid combinations is particularly challenging due to differences in the physicochemical properties of the two types of agents. This review discusses recent advances in the development of delivery methods using combinations of small molecule drugs and nucleic acid therapeutics to treat cancer. This review primarily focuses on the rationale used for selecting appropriate drug-nucleic acid combinations as well as progress in the development of nanocarriers suitable for simultaneous delivery of drug-nucleic acid combinations.

  11. Porous siliconformation and etching process for use in silicon micromachining

    DOEpatents

    Guilinger, Terry R.; Kelly, Michael J.; Martin, Jr., Samuel B.; Stevenson, Joel O.; Tsao, Sylvia S.

    1991-01-01

    A reproducible process for uniformly etching silicon from a series of micromechanical structures used in electrical devices and the like includes providing a micromechanical structure having a silicon layer with defined areas for removal thereon and an electrochemical cell containing an aqueous hydrofluoric acid electrolyte. The micromechanical structure is submerged in the electrochemical cell and the defined areas of the silicon layer thereon are anodically biased by passing a current through the electrochemical cell for a time period sufficient to cause the defined areas of the silicon layer to become porous. The formation of the depth of the porous silicon is regulated by controlling the amount of current passing through the electrochemical cell. The micromechanical structure is then removed from the electrochemical cell and submerged in a hydroxide solution to remove the porous silicon. The process is subsequently repeated for each of the series of micromechanical structures to achieve a reproducibility better than 0.3%.

  12. Development of Wet-Etching Tools for Precision Optical Figuring

    SciTech Connect

    Rushford, M C; Dixit, S N; Hyde, R; Britten, J A; Nissen, J; Aasen, M; Toeppen, J; Hoaglan, C; Nelson, C; Summers, L; Thomas, I

    2004-01-27

    This FY03 final report on Wet Etch Figuring involves a 2D thermal tool. Its purpose is to flatten (0.3 to 1 mm thickness) sheets of glass faster thus cheaper than conventional sub aperture tools. An array of resistors on a circuit board was used to heat acid over the glass Optical Path Difference (OPD) thick spots and at times this heating extended over the most of the glass aperture. Where the acid is heated on the glass it dissolves faster. A self-referencing interferometer measured the glass thickness, its design taking advantage of the parallel nature and thinness of these glass sheets. This measurement is used in close loop control of the heating patterns of the circuit board thus glass and acid. Only the glass and acid were to be moved to make the tool logistically simple to use in mass production. A set of 4-circuit board, covering 80 x 80-cm aperture was ordered, but only one 40 x 40-cm board was put together and tested for this report. The interferometer measurement of glass OPD was slower than needed on some glass profiles. Sometimes the interference fringes were too fine to resolve which would alias the sign of the glass thickness profile. This also caused the phase unwrapping code (FLYNN) to struggle thus run slowly at times taking hours, for a 10 inch square area. We did extensive work to improve the speed of this code. We tried many different phase unwrapping codes. Eventually running (FLYNN) on a farm of networked computers. Most of the work reported here is therefore limited to a 10-inch square aperture. Researched into fabricating a better interferometer lens from Plexiglas so to have less of the scattered light issues of Fresnel lens groves near field scattering patterns, this set the Nyquest limit. There was also a problem with the initial concept of wetting the 1737 glass on its bottom side with acid. The wetted 1737 glass developed an Achromatic AR coating, spoiling the reflection needed to see glass thickness interference fringes. In response

  13. Cyclosporine A and palmitic acid treatment synergistically induce cytotoxicity in HepG2 cells.

    PubMed

    Luo, Yi; Rana, Payal; Will, Yvonne

    2012-06-01

    Immunosuppressant cyclosporine A (CsA) treatment can cause severe side effects. Patients taking immunosuppressant after organ transplantation often display hyperlipidemia and obesity. Elevated levels of free fatty acids have been linked to the etiology of metabolic syndromes, nonalcoholic fatty liver and steatohepatitis. The contribution of free fatty acids to CsA-induced toxicity is not known. In this study we explored the effect of palmitic acid on CsA-induced toxicity in HepG2 cells. CsA by itself at therapeutic exposure levels did not induce detectible cytotoxicity in HepG2 cells. Co-treatment of palmitic acid and CsA resulted in a dose dependent increase in cytotoxicity, suggesting that fatty acid could sensitize cells to CsA-induced cytotoxicity at the therapeutic doses of CsA. A synergized induction of caspase-3/7 activity was also observed, indicating that apoptosis may contribute to the cytotoxicity. We demonstrated that CsA reduced cellular oxygen consumption which was further exacerbated by palmitic acid, implicating that impaired mitochondrial respiration might be an underlying mechanism for the enhanced toxicity. Inhibition of c-Jun N-terminal kinase (JNK) attenuated palmitic acid and CsA induced toxicity, suggesting that JNK activation plays an important role in mediating the enhanced palmitic acid/CsA-induced toxicity. Our data suggest that elevated FFA levels, especially saturated FFA such as palmitic acid, may be predisposing factors for CsA toxicity, and patients with underlying diseases that would elevate free fatty acids may be susceptible to CsA-induced toxicity. Furthermore, hyperlipidemia/obesity resulting from immunosuppressive therapy may aggravate CsA-induced toxicity and worsen the outcome in transplant patients.

  14. Safety and tolerability of gamma-hydroxybutyric acid in the treatment of alcohol-dependent patients.

    PubMed

    Beghè, F; Carpanini, M T

    2000-04-01

    Gamma-hydroxybutyric acid (GHB) has been in clinical use in Italy since 1991 for treatment of alcohol dependence. Results of phase III and phase IV studies have shown that the drug is effective and well tolerated in the treatment of alcohol withdrawal syndrome and in reducing alcohol consumption and alcohol craving. Pharmacosurveillance indicates that abuse of gamma-hydroxybutyric acid is a limited phenomenon in clinical settings when the drug is dispensed under strict medical surveillance and entrusted to a referring familiar member of the patient.

  15. Effect of the treatment by slightly acidic electrolyzed water on the accumulation of γ-aminobutyric acid in germinated brown millet.

    PubMed

    Li, Xingfeng; Hao, Jianxiong; Liu, Xianggui; Liu, Haijie; Ning, Yawei; Cheng, Ruhong; Tan, Bin; Jia, Yingmin

    2015-11-01

    The accumulation of γ-aminobutyric acid and the microbial decontamination are concerned increasingly in the production of sprouts. In this work, the effect of the treatment by slightly acidic electrolyzed water on the accumulation of γ-aminobutyric acid in the germinated brown millet was evaluated by high performance liquid chromatography during germination. The results showed that slightly acidic electrolyzed water with appropriate available chlorine (15 or 30 mg/L) could promote the accumulation of γ-aminobutyric acid by up to 21% (P < 0.05). However, the treatment with slightly acidic electrolyzed water could not enhance the sprouts growth of the germinated brown millet. The catalase and peroxidase activities of the germinated brown millet during germination were in agreement with the sprouts growth. Our results suggested that the accumulation of γ-aminobutyric acid was independent of the length of sprouts in germinated grains. Moreover, the treatment with slightly acidic electrolyzed water significantly reduced the microbial counts in the germinated millet (P < 0.05) and the treatment with high available chlorine concentration (15 and 30 mg/L) showed stronger anti-infection potential in the germinated brown millet than that of lower available chlorine concentration (5 mg/L). In conclusion, the treatment with slightly acidic electrolyzed water is an available approach to improve the accumulation of γ-aminobutyric acid and anti-infection potential in the germinated brown millet, and it can avoid too long millet sprouts.

  16. Modeling of plasma etch profiles with ions and reactive neutrals

    NASA Astrophysics Data System (ADS)

    Wang, Chungdar Daniel

    1999-11-01

    The simulation of plasma etch profiles of semiconductor trenches in the wafer processing of integrated circuits is developed in a mixed analytic/numerical approach. The main contributions of this study are the derivation and use of explicit analytical expressions for the etch rates and the computation of the etch profiles by standard computer packages. The computation of the etch profiles is efficient, is used as a benchmark for more complex numerical computer codes and illuminates the parameter dependence. The etch rate due to the ions is assumed proportional to the ion energy flux as suggested by experimental evidence. The shadowing due to the mask is included in the simplified derivation of the ion energy flux in cylindrical velocity coordinates for a two-temperature ion drifting Maxwellian. Neutrals with varying sticking coefficients are modeled by interpolation between the etch rate for shadowed neutrals with unity sticking coefficients and isotropic neutrals. The etch profiles are determined by the method of characteristics from the nonlinear evolution equation for the etch profile surface. Standard Matlab packages for the graphics and integration of the ordinary differential equations for the characteristics make the computation of etch profiles more efficient and more transparent than many complicated computer codes. The SEM images for trenches etched in silicon in a SF6 plasma in a RIE reactor are modeled by the simulation method for etch profiles. The etch rate is a linear combination of the etch rates of ions and neutrals in the ion flux-limited regime. Monte Carlo simulation of ion distribution functions in a chlorine plasma are fit by a simulated annealing procedure to a set of two-temperature drifting Maxwellians. The Monte Carlo simulations are noisy due to insufficient numbers of simulation particles. Smoothing of the distribution functions produces the expected bimodal ion distribution functions in the ICP reactor. The resultant etch profiles for

  17. Digital Electrochemical Etching of Compound Semiconductors

    DTIC Science & Technology

    1992-05-26

    Cd is stripped by oxidation to Cd2+. Underpotentials are chosen so that only the top atomic layer of an element is removed. Potentials sufficient to...the compound. The two potentials of the square wave correspond to underpotential stripping potentials for Cd and Te respectively. Directions for the...for the etching of CdTe. For CdTe, Te is stripped by reduction to Tel while Cd is stripped by oxidation to Cd2 . Underpotentials are chosen o that only

  18. Superior Pre-Osteoblast Cell Response of Etched Ultrafine-Grained Titanium with a Controlled Crystallographic Orientation.

    PubMed

    Baek, Seung Mi; Shin, Myeong Hwan; Moon, Jongun; Jung, Ho Sang; Lee, See Am; Hwang, WoonBong; Yeom, Jong Taek; Hahn, Sei Kwang; Kim, Hyoung Seop

    2017-03-07

    Ultrafine-grained (UFG) Ti for improved mechanical performance as well as its surface modification enhancing biofunctions has attracted much attention in medical industries. Most of the studies on the surface etching of metallic biomaterials have focused on surface topography and wettability but not crystallographic orientation, i.e., texture, which influences the chemical as well as the physical properties. In this paper, the influences of texture and grain size on roughness, wettability, and pre-osteoblast cell response were investigated in vitro after HF etching treatment. The surface characteristics and cell behaviors of ultrafine, fine, and coarse-grained Ti were examined after the HF etching. The surface roughness during the etching treatment was significantly increased as the orientation angle from the basal pole was increased. The cell adhesion tendency of the rough surface was promoted. The UFG Ti substrate exhibited a higher texture energy state, rougher surface, enhanced hydrophilic wettability, and better cell adhesion and proliferation behaviors after etching than those of the coarse- and fine-grained Ti substrates. These results provide a new route for enhancing both mechanical and biological performances using etching after grain refinement of Ti.

  19. Superior Pre-Osteoblast Cell Response of Etched Ultrafine-Grained Titanium with a Controlled Crystallographic Orientation

    NASA Astrophysics Data System (ADS)

    Baek, Seung Mi; Shin, Myeong Hwan; Moon, Jongun; Jung, Ho Sang; Lee, See Am; Hwang, Woonbong; Yeom, Jong Taek; Hahn, Sei Kwang; Kim, Hyoung Seop

    2017-03-01

    Ultrafine-grained (UFG) Ti for improved mechanical performance as well as its surface modification enhancing biofunctions has attracted much attention in medical industries. Most of the studies on the surface etching of metallic biomaterials have focused on surface topography and wettability but not crystallographic orientation, i.e., texture, which influences the chemical as well as the physical properties. In this paper, the influences of texture and grain size on roughness, wettability, and pre-osteoblast cell response were investigated in vitro after HF etching treatment. The surface characteristics and cell behaviors of ultrafine, fine, and coarse-grained Ti were examined after the HF etching. The surface roughness during the etching treatment was significantly increased as the orientation angle from the basal pole was increased. The cell adhesion tendency of the rough surface was promoted. The UFG Ti substrate exhibited a higher texture energy state, rougher surface, enhanced hydrophilic wettability, and better cell adhesion and proliferation behaviors after etching than those of the coarse- and fine-grained Ti substrates. These results provide a new route for enhancing both mechanical and biological performances using etching after grain refinement of Ti.

  20. Superior Pre-Osteoblast Cell Response of Etched Ultrafine-Grained Titanium with a Controlled Crystallographic Orientation

    PubMed Central

    Baek, Seung Mi; Shin, Myeong Hwan; Moon, Jongun; Jung, Ho Sang; Lee, See Am; Hwang, WoonBong; Yeom, Jong Taek; Hahn, Sei Kwang; Kim, Hyoung Seop

    2017-01-01

    Ultrafine-grained (UFG) Ti for improved mechanical performance as well as its surface modification enhancing biofunctions has attracted much attention in medical industries. Most of the studies on the surface etching of metallic biomaterials have focused on surface topography and wettability but not crystallographic orientation, i.e., texture, which influences the chemical as well as the physical properties. In this paper, the influences of texture and grain size on roughness, wettability, and pre-osteoblast cell response were investigated in vitro after HF etching treatment. The surface characteristics and cell behaviors of ultrafine, fine, and coarse-grained Ti were examined after the HF etching. The surface roughness during the etching treatment was significantly increased as the orientation angle from the basal pole was increased. The cell adhesion tendency of the rough surface was promoted. The UFG Ti substrate exhibited a higher texture energy state, rougher surface, enhanced hydrophilic wettability, and better cell adhesion and proliferation behaviors after etching than those of the coarse- and fine-grained Ti substrates. These results provide a new route for enhancing both mechanical and biological performances using etching after grain refinement of Ti. PMID:28266643

  1. Etching of moldavities under natural conditions

    NASA Technical Reports Server (NTRS)

    Knobloch, V.; Knoblochova, Z.; Urbanec, Z.

    1983-01-01

    The hypothesis that a part of the lechatellierites which originated by etching from a basic moldavite mass became broken off after deposition of moldavite in the sedimentation layer is advanced. Those found close to the original moldavite were measured for statistical averaging of length. The average length of lechatelierite fibers per cubic mm of moldavite mass volume was determined by measurement under a microscope in toluene. The data were used to calculate the depth of the moldavite layer that had to be etched to produce the corresponding amount of lechatelierite fragments. The calculations from five "fields" of moldavite surface, where layers of fixed lechatelierite fragments were preserved, produced values of 2.0, 3.1, 3.5, 3.9 and 4.5. Due to inadvertent loss of some fragments the determined values are somewhat lower than those found in references. The difference may be explained by the fact that the depth of the layer is only that caused by etching after moldavite deposition.

  2. Effect of bonding material, etching time and silane on the bond strength of metallic orthodontic brackets to ceramic.

    PubMed

    Costa, Ana Rosa; Correr, Américo Bortolazzo; Puppin-Rontani, Regina Maria; Vedovello, Silvia Amélia; Valdrighi, Heloísa Cristina; Correr-Sobrinho, Lourenço; Vedovello Filho, Mário

    2012-01-01

    The purpose of this study was to evaluate the bond strength of metallic orthodontic brackets to feldspathic ceramic with different etching times, bonding materials and with or without silane application. Cylinders of feldspathic ceramic were etched with 10% hydrofluoric acid for 20 or 60 s. For each etching time, half of the cylinders received two layers of silane. Metallic brackets were bonded to the cylinders using Transbond XT (3M Unitek) or Fuji Ortho LC (GC). Light-activation was carried out with total exposure time of 40 s using UltraLume 5. Shear bond strength testing was performed after 24 h storage. Data were submitted to three-way ANOVA and Tukey's test (α=0.05). The adhesive remnant index (ARI) was used to evaluate the amount of adhesive remaining on the ceramic surface at ×8 magnification. Specimens etched for 60 s had significantly higher bond strength compared with 20 s. The application of silane was efficient in increasing the shear bond strength between ceramic and both fixed materials. Transbond XT showed significantly higher (p<0.05) bond strength than Fuji Orth LC. There was a predominance of ARI score 0 (clean ceramic failure surface) for all groups, with an increase in scores 1, 2 and 3 (adhesive material increasingly present on ceramic failure aspect) for the 60-s etching time. In conclusion, 60-s etching time, silane and Transbond XT improved significantly the shear bond strength of brackets to ceramic.

  3. Effect of a functional monomer (MDP) on the enamel bond durability of single-step self-etch adhesives.

    PubMed

    Tsuchiya, Kenji; Takamizawa, Toshiki; Barkmeier, Wayne W; Tsubota, Keishi; Tsujimoto, Akimasa; Berry, Thomas P; Erickson, Robert L; Latta, Mark A; Miyazaki, Masashi

    2016-02-01

    The present study aimed to determine the effect of the functional monomer, 10-methacryloxydecyl dihydrogen phosphate (MDP), on the enamel bond durability of single-step self-etch adhesives through integrating fatigue testing and long-term water storage. An MDP-containing self-etch adhesive, Clearfil Bond SE ONE (SE), and an experimental adhesive, MDP-free (MF), which comprised the same ingredients as SE apart from MDP, were used. Shear bond strength (SBS) and shear fatigue strength (SFS) were measured with or without phosphoric acid pre-etching. The specimens were stored in distilled water for 24 h, 6 months, or 1 yr. Although similar SBS and SFS values were obtained for SE with pre-etching and for MF after 24 h of storage in distilled water, SE with pre-etching showed higher SBS and SFS values than MF after storage in water for 6 months or 1 yr. Regardless of the pre-etching procedure, SE showed higher SBS and SFS values after 6 months of storage in distilled water than after 24 h or 1 yr. To conclude, MDP might play an important role in enhancing not only bond strength but also bond durability with respect to repeated subcritical loading after long-term water storage.

  4. Unveiling the shape-diversified silicon nanowires made by HF/HNO3 isotropic etching with the assistance of silver.

    PubMed

    Chen, Chia-Yun; Wong, Ching-Ping

    2015-01-21

    Hydrofluoric (HF)/nitric (HNO3)/acetic (CH3COOH) acid, normally referred to as the HNA method, is a widely utilized technique for performing isotropic etching on silicon (Si) in industrial Si-based processing and device construction. Here, we reported a novel etching strategy based on a HF/HNO3 process with the assistance of silver (Ag) nano-seeds, offering good controllability in preparing diversified Si nanostructure arrays with particularly smooth top surfaces. The involved mechanism was visualized by systematically investigating both the time and temperature dependencies on the etching kinetics with various ratios of HF to HNO3. Moreover, by testing different Ag(+)-ion containing oxidants on Si etching, we have re-examined the state-of-the-art metal-assisted chemical etching (MaCE) using HF/AgNO3 etchants. In contrast with previous reports, we found that the interplay of hole injections from Ag(+) and NO3(-) ions to the valence band of Si collectively contributes to the unidirectional dissolution of Si. Finally, we explored the engineering of the Ag nano-seeds to regularize the orientation of the etched nanowires formed on non-Si (100) wafers, which further provides a reliable pathway for constructing the desired morphologies of one-dimensional Si nanostructures regardless of wafer orientation.

  5. Modeling of free fatty acid dynamics: insulin and nicotinic acid resistance under acute and chronic treatments.

    PubMed

    Andersson, Robert; Kroon, Tobias; Almquist, Joachim; Jirstrand, Mats; Oakes, Nicholas D; Evans, Neil D; Chappel, Michael J; Gabrielsson, Johan

    2017-02-21

    Nicotinic acid (NiAc) is a potent inhibitor of adipose tissue lipolysis. Acute administration results in a rapid reduction of plasma free fatty acid (FFA) concentrations. Sustained NiAc exposure is associated with tolerance development (drug resistance) and complete adaptation (FFA returning to pretreatment levels). We conducted a meta-analysis on a rich pre-clinical data set of the NiAc-FFA interaction to establish the acute and chronic exposure-response relations from a macro perspective. The data were analyzed using a nonlinear mixed-effects framework. We also developed a new turnover model that describes the adaptation seen in plasma FFA concentrations in lean Sprague-Dawley and obese Zucker rats following acute and chronic NiAc exposure. The adaptive mechanisms within the system were described using integral control systems and dynamic efficacies in the traditional [Formula: see text] model. Insulin was incorporated in parallel with NiAc as the main endogenous co-variate of FFA dynamics. The model captured profound insulin resistance and complete drug resistance in obese rats. The efficacy of NiAc as an inhibitor of FFA release went from 1 to approximately 0 during sustained exposure in obese rats. The potency of NiAc as an inhibitor of insulin and of FFA release was estimated to be 0.338 and 0.436 [Formula: see text], respectively, in obese rats. A range of dosing regimens was analyzed and predictions made for optimizing NiAc delivery to minimize FFA exposure. Given the exposure levels of the experiments, the importance of washout periods in-between NiAc infusions was illustrated. The washout periods should be [Formula: see text]2 h longer than the infusions in order to optimize 24 h lowering of FFA in rats. However, the predicted concentration-response relationships suggests that higher AUC reductions might be attained at lower NiAc exposures.

  6. Fourier transform infrared photoacoustic spectroscopy study of physicochemical interaction between human dentin and etch-&-rinse adhesives in a simulated moist bond technique.

    PubMed

    Ubaldini, Adriana L M; Baesso, Mauro L; Sehn, Elizandra; Sato, Francielle; Benetti, Ana R; Pascotto, Renata C

    2012-06-01

    The purpose of this study was to provide the physicochemical interactions at the interfaces between two commercial etch-&-rinse adhesives and human dentin in a simulated moist bond technique. Six dentin specimens were divided into two groups (n=3) according to the use of two different adhesive systems: (a) 2-hydroxyethylmethacrylate (HEMA) and 4-methacryloxyethyl trimellitate anhydrate (4-META), and (b) HEMA. The Fourier transform infrared photoacoustic spectroscopy was performed before and after dentin treatment with 37% phosphoric acid, with adhesive systems and also for the adhesive systems alone. Acid-conditioning resulted in a decalcification pattern. Adhesive treated spectra subtraction suggested the occurrence of chemical bonding to dentin expressed through modifications of the OH stretching peak (3340 cm(-1)) and symmetric CH stretching (2900 cm(-1)) for both adhesives spectra; a decrease of orthophosphate absorption band (1040 to 970 cm(-1)) for adhesive A and a better resolved complex band formation (1270 to 970 cm(-1)) for adhesive B were observed. These results suggested the occurrence of chemical bonding between sound human dentin and etch-&-rinse adhesives through a clinical typical condition.

  7. Evaluation of the tensile bond strength of an adhesive system self-etching in dentin irradiated with Er:YAG laser

    NASA Astrophysics Data System (ADS)

    de Mello, Andrea M. D.; Mello, Fabiano A. S.; Matson, Edmir; Mattos, Adriana B.; Mello, Guilerme S.

    2001-04-01

    Since Buonocore, several researchers have been seeking for the best adhesive system and treatment for the enamel and dentin surfaces. The use of the acid has been presented as one of the best techniques of dentin conditioning, because this promotes the removal of the 'smear layer' and exhibition of dentinal structure, for a best penetration and micro-retention of the adhesive system. However, some conditioning methods have been appearing in the literature, for the substitution or interaction with the acid substances, as the laser. The objective of this work is to evaluate the tensile bond strength of the adhesive system 'self-etching' associated to a composed resin, in dentin surfaces conditioned with the Er:YAG laser. For this study, freshly extracted human teeth were used and in each one the dentinal surfaces, which were treated with three sandpapers of different granulations to obtain a standard of the smear layer, before the irradiation of the laser and of the restoring procedure. After these procedures the specimens were storage in distilled water at 37 degrees for 24 hours. Soon after, they were submitted to the tensile strength test. After analyzing the results, we can conclude that the use of the Er:YAG laser can substitute the drill without the need of conditioning, when using the adhesive system 'self etching' in the dentinal surfaces because there was a decline in the strength of adhesion in the groups conditioned with the laser.

  8. Three step deep reactive ion etch for high density trench etching

    NASA Astrophysics Data System (ADS)

    Lips, B.; Puers, R.

    2016-10-01

    A three step Deep Reactive Ion Etch (DRIE) process is developed to etch trenches of 10μm wide to a depth of 130μm into silicon with an etch rate of 2.5μm min-1. The aim of this process is to obtain sidewalls with an angle close to 90°. The process allows the etching of multiple trenches with high aspect ratios that are closely placed together. A three step approach is used as opposed to the more conventional two step approach in an attempt to improve the etching selectivity with respect to the masking material. By doing so, a simple AZ6632 positive photoresist could be used instead of the more commonly used metal masks which are harder to remove afterwards. In order to develop this process, four parameters, which are the bias power, processing pressure, step times and number of cycles, are evaluated an optimized on a PlasmaPro 300 Cobra DRIE tool from Oxford Plasma Technology.

  9. Morphological evaluation of new total etching and self etching adhesive system interfaces with dentin

    PubMed Central

    Hegde, Mithra N; Hegde, Priyadarshini; Chandra, C Ravi

    2012-01-01

    Aim: The purpose of this study is to evaluate the resin-dentin interface, quality of the hybrid layer of total-etching and self-etching adhesive systems under scanning electron microscopy (SEM). Materials and Methods: Class V cavities were prepared in 40 extracted human molars. In Group I XP bond (Dentsply), in Group II Adper Single Bond II (3M ESPE), in Group III Adper Easy One (3M ESPE), and in Group IV Xeno V (Dentsply) were applied. Teeth were restored with resin composite, subjected to thermocycling, and sectioned in Buccolingual plane. The samples were demineralized using 6N HCl, for 30 sec, and deproteinized with 2.5% NaOCl for 10 min, gold sputtered, and viewed using a scanning electron microscope. Results: Among the total-etch systems used, the XP Bond showed a clear, thick hybrid layer, with long resin tags and few voids. Among the self-etch adhesive systems, the Xeno V did not show a cl