Enamel loss and adhesive remnants following bracket removal and various clean-up procedures in vitro

This study evaluated the enamel loss and composite remnants after debonding and clean-up. The tested null hypothesis is that there are no differences between different polishing systems regarding removing composite remnants without damaging the tooth surface. Brackets were bonded to 75 extracted human molars and removed after a storage period of 100 hours. The adhesive remnant index (ARI) was evaluated. The clean-up was carried out with five different procedures: 1. carbide bur; 2. carbide bur and Brownie and Greenie silicone polishers; 3. carbide bur and Astropol polishers; 4. carbide bur and Renew polishers; and 5. carbide bur, Brownie, Greenie and PoGo polishers. Silicone impressions were made at baseline (T0) and after debonding (T1) and polishing (T2) to produce plaster replicas. The replicas were analysed with a three-dimensional laser scanner and measured with analytical software. Statistical analysis was performed with the Kruskal-Wallis test and pairwise Wilcoxon tests with Bonferroni-Holm adjustment (α = 0.05). Enamel breakouts after debonding were detectable in 27 per cent of all cases, with a mean volume loss of 0.02 mm(3) (±0.03 mm(3)) and depth of 44.9 μm (±48.3 μm). The overall ARI scores was 3 with a few scores of 1 and 2. The composite remnants after debonding had a mean volume of 2.48 mm(3) (±0.92 mm(3)). Mean volume loss due to polishing was 0.05 mm(3) (±0.26 mm(3)) and the composite remnants had a mean volume of 0.22 mm(3) (±0.32 mm(3)). There were no statistically significant differences in volumetric changes after polishing (P = 0.054) between the different clean-up methods. However, sufficient clean-up without enamel loss was difficult to achieve.

Accessing federal data bases for contaminated site clean-up technologies /

"May 1991"

Assessing UST corrective action technologies : early screening of clean-up technologies for the saturated zone /

Mode of access: Internet.

To review issues related to the clean up of Department of Defense national priority list sites and compliance with the Solid Waste Disposal Act [microform] : hearing before the Environmental Restoration Panel of the Readiness Subcommittee of the Committee on Armed Services, House of Representatives, One Hundredth Congress, second session, hearing held September 27, 1988.

At head of title: H.A.S.C. no. 100-95.

Hazardous waste, responsible party clean up efforts require improved oversight : report to the chairman, Subcommittee on Commerce, Transportation and Tourism, Committee on Energy and Commerce, House of Representatives /

"B-221269"--P. [1].

An interactive environmental site assessment audit for Wagner Creek river basin clean up project

The primary purpose of this thesis was to design and create an Interactive Audit to conduct Environmental Site Assessments according to American Society of Testing Material's (ASTM) Phase I Standards at the Wagner Creek study area. ArcPad and ArcIMS are the major software that were used to create the model and ArcGIS Desktop was used for data analysis and to export shapefile symbology to ArcPad. Geographic Information Systems (GIS) is an effective tool to deploy these purposes. This technology was utilized to carry out data collection, data analysis and to display data interactively on the Internet. Electronic forms, customized for mobile devices were used to survey sites. This is an easy and fast way to collect and modify field data. New data such as land use, recognized environmental conditions, and underground storage tanks can be added into existing datasets. An updated map is then generated and uploaded to the Internet using ArcIMS technology. The field investigator has the option to generate and view the Inspection Form at the end of his survey on site, or print a hardcopy at base. The mobile device also automatically generates preliminary editable Executive Reports for any inspected site.

First principles modelling of nucleation and growth during atomic layer deposition onto III-V substrates

Atomic layer deposition (ALD) is now used in semiconductor fabrication lines to deposit nanometre-thin oxide films, and has thus enabled the introduction of high-permittivity dielectrics into the CMOS gate stack. With interest increasing in transistors based on high mobility substrates, such as GaAs, we are investigating the surface treatments that may improve the interface characteristics. We focus on incubation periods of ALD processes on III-V substrates. We have applied first principles Density Functional Theory (DFT) to investigate detailed chemistry of these early stages of growth, specifically substrate and ALD precursor interaction. We have modelled the ‘clean-up’ effect by which organometallic precursors: trimethylaluminium (TMA) or hafnium and titanium amides clean arsenic oxides off the GaAs surface before ALD growth of dielectric commences and similar effect on Si3N4 substrate. Our simulations show that ‘clean-up’ of an oxide film strongly depends on precursor ligand, its affinity to the oxide and the redox character of the oxide. The predominant pathway for a metalloid oxide such as arsenic oxide is reduction, producing volatile molecules or gettering oxygen from less reducible oxides. An alternative pathway is non-redox ligand exchange, which allows non-reducible oxides (e.g. SiO2) to be cleaned-up. First principles study shows also that alkylamides are more susceptible to decomposition rather than migration on the oxide surface. This improved understanding of the chemical principles underlying ‘clean-up’ allows us to rationalize and predict which precursors will perform the reaction. The comparison is made between selection of metal chlorides, methyls and alkylamides precursors.

Gas chromatographic electron capture negative ionization mass spectrometric (GC/ECNI/MS) determination of unique fluorinated compounds in the sediments of Lake Ontario and the effect of high-boiling alcohols (as injection solvents) on chromatographic behaviour of polycyclic aromatic hydrocarbons in gas chromatography

Part I - Fluorinated Compounds A method has been developed for the extraction, concentration, and determination of two unique fluorinated compounds from the sediments of Lake Ontario. These compounds originated from a common industrial landfill, and have been carried to Lake Ontario by the Niagara River. Sediment samples from the Mississauga basin of Lake Ontario have been evaluated for these compounds and a depositional trend was established. The sediments were extracted by accelerated solvent extraction (ASE) and then underwent clean-up, fractionation, solvent exchange, and were concentrated by reduction under nitrogen gas. The concentrated extracts were analyzed by gas chromatography - electron capture negative ionization - mass spectrometry. The depositional profile determined here is reflective of the operation of the landfill and shows that these compounds are still found at concentrations well above background levels. These increased levels have been attributed to physical disturbances of previously deposited contaminated sediments, and probable continued leaching from the dumpsite. Part II - Polycyclic Aromatic Hydrocarbons Gas chromatography/mass spectrometry is the most common method for the determination of polycyclic aromatic hydrocarbons (PAHs) from various matrices. Mass discrimination of high-boiling compounds in gas chromatographic methods is well known. The use of high-boiling injection solvents shows substantial increase in the response of late-eluting peaks. These solvents have an increased efficiently in the transfer of solutes from the injector to the analytical column. The effect of I-butanol, I-pentanol, cyclopentanol, I-hexanol, toluene and n-octane, as injection solvents, was studied. Higher-boiling solvents yield increased response for all PAHs. I -Hexanol is the best solvent, in terms of P AH response, but in this solvent P AHs were more susceptible to chromatographic problems such as peak splitting and tailing. Toluene was found to be the most forgiving solvent in terms of peak symmetry and response. It offered the smallest discrepancies in response, and symmetry over a wide range of initial column temperatures.

[Summary of the reorganization and merger of the Illinois Department of the Lottery, the Illinois Liquor Control Commission, and the Illinois Racing Board with the Illinois Department of Revenue, pursuant to Executive Order 9, which took effect on June 1, 2003]

In accordance with 15-ILCS 15/11, from Chapter 127, paragraph 1811, the following report is offered to summarize the reorganization of the Department of the Lottery, the Liquor Control Commission, and the Illinois Racing Board merger with the Department of Revenue, pursuant to Executive Order 9, which took effect on June 1, 2003. As part of the governor's ongoing effort to streamline state government and improve efficiency, the consolidation eliminated duplication by integrating administrative functions of the agencies with the Department of Revenue. The change resulted in savings of $3 million on an annual basis from 29 fewer positions and a reduction of leased office space at 7 Lottery locations throughout the state. Streamlined operations were achieved by merging human resource management, procurement, accounting, information technology, and other administrative support services. In addition, Lottery headquarters in Springfield and Chicago, as well as sales district office locations throughout the state were merged with existing Department of Revenue offices, significantly reducing state lease costs. Core functions of the Lottery, Liquor Control Commission, and Racing Board remain intact, and the boards and commission that oversee these entities retain their regulatory responsibilities. The department is considering recommending "clean-up" legislation to replace statutory references to the "Department of the Lottery" with the "Division of the Lottery" or "Department of Revenue Division of the Lottery".

Comprehensive Two-Dimensional Gas Chromatography: Instrumental and Methodological Development

Comprehensive two-dimensional gas chromatography (GC×GC) offers enhanced separation efficiency, reliability in qualitative and quantitative analysis, capability to detect low quantities, and information on the whole sample and its components. These features are essential in the analysis of complex samples, in which the number of compounds may be large or the analytes of interest are present at trace level. This study involved the development of instrumentation, data analysis programs and methodologies for GC×GC and their application in studies on qualitative and quantitative aspects of GC×GC analysis. Environmental samples were used as model samples. Instrumental development comprised the construction of three versions of a semi-rotating cryogenic modulator in which modulation was based on two-step cryogenic trapping with continuously flowing carbon dioxide as coolant. Two-step trapping was achieved by rotating the nozzle spraying the carbon dioxide with a motor. The fastest rotation and highest modulation frequency were achieved with a permanent magnetic motor, and modulation was most accurate when the motor was controlled with a microcontroller containing a quartz crystal. Heated wire resistors were unnecessary for the desorption step when liquid carbon dioxide was used as coolant. With use of the modulators developed in this study, the narrowest peaks were 75 ms at base. Three data analysis programs were developed allowing basic, comparison and identification operations. Basic operations enabled the visualisation of two-dimensional plots and the determination of retention times, peak heights and volumes. The overlaying feature in the comparison program allowed easy comparison of 2D plots. An automated identification procedure based on mass spectra and retention parameters allowed the qualitative analysis of data obtained by GC×GC and time-of-flight mass spectrometry. In the methodological development, sample preparation (extraction and clean-up) and GC×GC methods were developed for the analysis of atmospheric aerosol and sediment samples. Dynamic sonication assisted extraction was well suited for atmospheric aerosols collected on a filter. A clean-up procedure utilising normal phase liquid chromatography with ultra violet detection worked well in the removal of aliphatic hydrocarbons from a sediment extract. GC×GC with flame ionisation detection or quadrupole mass spectrometry provided good reliability in the qualitative analysis of target analytes. However, GC×GC with time-of-flight mass spectrometry was needed in the analysis of unknowns. The automated identification procedure that was developed was efficient in the analysis of large data files, but manual search and analyst knowledge are invaluable as well. Quantitative analysis was examined in terms of calibration procedures and the effect of matrix compounds on GC×GC separation. In addition to calibration in GC×GC with summed peak areas or peak volumes, simplified area calibration based on normal GC signal can be used to quantify compounds in samples analysed by GC×GC so long as certain qualitative and quantitative prerequisites are met. In a study of the effect of matrix compounds on GC×GC separation, it was shown that quality of the separation of PAHs is not significantly disturbed by the amount of matrix and quantitativeness suffers only slightly in the presence of matrix and when the amount of target compounds is low. The benefits of GC×GC in the analysis of complex samples easily overcome some minor drawbacks of the technique. The developed instrumentation and methodologies performed well for environmental samples, but they could also be applied for other complex samples.

Numerical Study Of Pile-Up In Bulk Metallic Glass During Spherical Indentation

Pile-up around indenter is usually observed during instrumented indentation tests on bulk metallic glass. Neglecting the pile-up effect may lead to errors in evaluating hardness, Young's modulus, stress-strain response, etc. Finite element analysis was employed to implement numerical simulation of spherical indentation tests on bulk metallic glass. A new model was proposed to describe the pile-up effect. By using this new model, the contact radius and hardness of Zr41.2Ti13.8Cu12.5Ni10Be22.5 bulk metallic glass were obtained under several different indenter loads with pile-up, and the results agree well with the data generated by numerical simulation.

Channels that heat up

This paper considers an additive noise channel where the time-κ noise variance is a weighted sum of the squared magnitudes of the previous channel inputs plus a constant. This channel model accounts for the dependence of the intrinsic thermal noise on the data due to the heat dissipation associated with the transmission of data in electronic circuits: the data determine the transmitted signal, which in turn heats up the circuit and thus influences the power of the thermal noise. The capacity of this channel (both with and without feedback) is studied at low transmit powers and at high transmit powers. At low transmit powers, the slope of the capacity-versus-power curve at zero is computed and it is shown that the heating-up effect is beneficial. At high transmit powers, conditions are determined under which the capacity is bounded, i.e., under which the capacity does not grow to infinity as the allowed average power tends to infinity. © 2009 IEEE.

Polycyclic aromatic hydrocarbons (PAHS) (I): Measures of prevention and control

Measures of prevention and control against polycyclic aromatic hydrocarbons (PAHs) focus on an official food control, a code of best practice to reduce PAHs levels by controlling industry and in the development of a chemopreventive strategy. Regulation (EU) 835/2011 establishes maximum levels of PAHs for each food group. In addition, Regulations (EU) 333/2007 and 836/2011 set up the methods of sampling and analysis for its official control. Scientific studies prove that the chemopreventive strategy is effective against these genotoxic compounds effects. Most chemopreventive compounds studied with proven protective effects against PAHs are found in fruit and vegetables.

Treatment of estrogens and androgens in dairy wastewater by a constructed wetland system.

Constructed wetland systems (CWS) have been used as a low cost bio-filtration system to treat farm wastewater. While studies have shown that CWS are efficient in removing organic compounds and pathogens, there is limited data on the presence of hormones in this type of treatment system. The objective of this study was to evaluate the ability of the CWS to reduce estrogenic and androgenic hormone concentration in dairy wastewater. This was achieved through a year long study on dairy wastewater samples obtained froma surface flow CWS. Analysis of hormonal levels was performed using a solid phase extraction (SPE) sample clean-up method, combined with reporter gene assays (RGAs) which incorporate relevant receptors capable of measuring total estrogenic or androgenic concentrations as low as 0.24 ng L1 and 6.9 ng L1 respectively. Monthly analysis showed a mean removal efficiency for estrogens of 95.2%, corresponding to an average residual concentration of 3.2 ng L1 17b-estradiol equivalent (EEQ), below the proposed lowest observable effect concentration (LOEC) of 10 ng L1. However, for one month a peak EEQ concentration of 115 ng L1 was only reduced to 18.8 ng L1. The mean androgenic activity peaked at 360 ng L1 and a removal efficiency of 92.1% left an average residual concentration of 32.3 ng L1 testosterone equivalent (TEQ). The results obtained demonstrate that this type of CWS is an efficient system for the treatment of hormones in dairy wastewater. However, additional design improvements may be required to further enhance removal efficiency of peak hormone concentrations.

Avaliação ecotoxicológica de solos contaminados por ibuprofeno

Os produtos farmacêuticos são substâncias químicas muito utilizados em medicina, veterinária e ainda na agricultura. Nos anos 90, foi descoberta a presença de fármacos em meio aquático, verificando-se que a sua remoção nas Estações de Tratamento de Águas Residuais (ETAR) não era completa. Durante as duas últimas décadas foi identificada a presença de mais de oitenta compostos no meio ambiente e actualmente são considerados poluentes emergentes. Podem contaminar solos e águas, depois de serem usados e excretados (inalterados ou metabolizados) por humanos e animais, ou quando são indevidamente lançados directamente no meio ambiente. Os estudos ecotoxicológicos efectuados com estes poluentes têm sido direccionados, sobretudo, para as águas, existindo uma ausência de trabalhos sobre solos. O Ibuprofeno (IB) é um anti-inflamatório não esteróide, utilizado também como analgésico e antipirético, sendo um dos produtos farmacêuticos mais vendidos em todo o mundo, o que justifica a sua forte presença no meio ambiente. Por isso, e dada a ausência de trabalhos ecotoxicológicos de solos contaminados por fármacos, o IB foi o produto farmacêutico selecionado para a realização deste trabalho. A ecotoxicidade pode ser avaliada através de bioensaios. Estes têm a capacidade de avaliar a toxicidade de uma determinada substância de forma global, usando organismos vivos que funcionam como bio-indicadores. O presente trabalho tem como objectivos avaliar o impacte causado nos solos pelo IB, testar a toxicidade de dois processos de descontaminação para remover o referido fármaco dos solos assim como avaliar a toxicidade provocada por águas residuais, de três unidades hospitalares e de uma indústria farmacêutica. Esta avaliação foi efectuada através de ensaios de toxicidade aguda de germinação e de alongamento de raiz de sementes de alface, variedade bola de manteiga (Lactuca sativa), em solo arenoso. Os ensaios de ecotoxicidade aguda em solos contaminados por IB foram realizados para uma gama de concentrações entre 0,1 e 1000 μg/L. Verificou-se uma redução do número de sementes germinadas e do comprimento médio da planta no solo contaminado com 0,5 e 20 μg/L de IB. No solo contaminado com 1000 μg/L de IB observou-se uma redução da germinação, acompanhada por uma indução de crescimento da raiz da espécie Lactuca sativa. Os dois tratamentos de descontaminação de solos, reagente de Fenton e Nanopartículas de ferro zero valente, revelaram toxicidade, tendo-se obtido uma percentagem de germinação entre 32,2 ± 3,5 e 48,5 ± 6,2 e inibição do crescimento da raiz do organismo teste em cerca de 85,0 %. Em relação às águas residuais hospitalares verificou-se uma redução da percentagem de germinação entre 31,1 ± 5,0 e 72,3 ± 12,4 e uma inibição do crescimento da raiz situada entre 13,0 ± 6,4 e 20,2 ± 10,0 %. Para a água residual industrial ocorreu uma inibição da percentagem de germinação de 60,5 ± 13,1, contudo nas plantas germinadas observou-se uma indução do crescimento da raiz de 14,9 ± 7,7 %.