Subsequent Rinse Research Articles

Evaluation of the effect of sodium hypochlorite gel on composite bonding strength to enamel of primary teeth after salivary contamination: in vitro study

The study investigated the effect of 2%s odium hypochlorite gel application after post-etching salivary contamination on composite bonding strength to primary teeth enamel. The sample consisted of 79 primary human teeth that were extracted no more than one month ago. The sample was randomly divided into four groups: (1) the control group (A) comprised 10 primary teeth, and composites were applied in the traditional manner without any salivary contamination; (2) the second group (B) consisted of 23 primary teeth in which salivary contamination was conducted after etching followed by re-etching and follow-up; (3) the third group (C) comprised 23 primary teeth in which saliva contamination was done after etching followed by washing, drying, and follow-up; and (4) the fourth group (D) comprised 23 primary teeth, in which salivary contamination was conducted after etching followed by application of sodium hypochlorite gel and follow-up. The samples were tested using the Testometric Tensile Strength Device (Testometric M350-10 kN, Testometric Ltd., UK) to measure the composite bonding strength to enamel of primary teeth. The arithmetic mean strength values in the research sample were ordered as followed: (A=13.39 MPa) > (D=11.82 MPa) > (C=8.07 MPa) > (B=6.15 MPa). The application of sodium hypochlorite gel after salivary contamination significantly improved the composite bonding strength to primary teeth enamel when compared with re-etching or only washing and drying. 15 s exposition of sodium hypochlorite gel with subsequent rinse and drying is recommended in case of saliva contamination of etched primary tooth enamel surface.

Quantitative Oral HPV16 and HPV18 Detection in Persons Attending Dental Clinics.

This study aimed to assess quantitative human papillomavirus (HPV) type 16 and HPV18 detection in oral rinses obtained in dental offices in Seattle, Washington. We evaluated oral rinses collected during dental visits from 2016 to 2018. Multiplex TaqMan quantitative polymerase chain reaction was used to determine HPV16 and HPV18 viral load (VL). Of 15,313 persons, 152 (1%) had detectable oral HPV16/18. Men were at higher risk of oral HPV16/18 infection than women (1.6% vs. 0.6%; odds ratio, 3.2; 95% confidence interval, 2.1-4.4). Compared with women, men with HPV16 were older (median, 55 vs. 48 years; P < 0.001) and had higher VL (39.7 vs. 1.1 copies/mL, P < 0.001). Of 39 with HPV16 at baseline and a second oral rinse, 13 remained positive at subsequent rinse; of 8 with HPV18 at baseline, 2 remained positive at subsequent rinse. Persons with consecutive positive test results were all men and had higher baseline VL compared with those with first positive and second negative samples. Oral rinse is an acceptable method of HPV testing, and persons are interested in testing. Overall HPV16/18 prevalence was low, and detection was more frequent among men than women, especially at higher copy numbers. HPV16 persistence was more common in men with high VL at baseline test. Future studies are needed to evaluate the feasibility of an effective secondary prevention strategy for oropharyngeal cancer using quantitative oral HPV detection.

Evaluation of Biochar Nitrate Extraction Methods

Biochar amendment to soil is a method used to mitigate losses of nitrogen leaching through agricultural soils. Multiple methods for extraction of nitrogen have been used, and recent studies have indicated that traditional soil extraction methods underestimate biochar nitrate. This study evaluated the nitrate extraction efficiency of a KCl extraction method under different temperature (20 and 50 °C) and duration (24 and 96 h) conditions. Increasing the duration of extraction from 24 to 96 h did not have a significant impact on extraction efficiency. However, increasing temperature resulted in nitrate extraction efficiencies above 90%. Rinsing the biochar once with deionized (DI) water following filtration after extraction increased the extraction efficiency significantly, but any subsequent rinses were not significant. This study recommends extracting nitrate from biochar using 2 M KCl at 50 °C for a period of 24 h with one additional rinse to increase nitrate recovery above 90%. However, future studies should evaluate this procedure for different types of biochar produced from alternative biomasses and at varying temperatures.

Geolocation of Cu Wires During Sensitive IC Acid Decapsulation

Abstract Copper wires are susceptible to damage during acid decapsulation and must be protected by stopping the process at the right moment. This article describes the development and evaluation of a method that uses polarization current measurements for end-of-etch detection and subsequent rinse.

Dicamba and 2,4-D residues following applicator cleanout: A potential point source to the environment and worker exposure

This paper presents a survey of pesticide residues in tanks following application and throughout the cleanout procedure as conducted by 46 volunteer operators across Colorado. While many pesticides were detected, this paper focuses on dicamba and 2,4-D, which were detected by liquid chromatography/tandem mass spectroscopy (LC-MS/MS). An exponential decrease in concentration was observed with sequential rinses, although this decrease may be more rapid for more water-soluble pesticides. More than 95% of the pesticide in the prerinse solution was removed by the end of the third rinse in all but three operator samples. Concentrations after three rinses were 0.41 ± 0.25 and 3.3 ± 1.1 mg/L for dicamba and 2,4-D, respectively. These concentrations suggest that the recommended practice of three rinses may not be adequate to eliminate off-target effects or point sources of pesticide waste, and that the recommended standard of personal protective equipment is essential to prevent worker exposure to the chemicals.Implications: This paper demonstrates that the waste generated during cleanout of pesticide application devices constitutes a potential source of pollution and worker exposure. In particular, while the first rinse of pesticide containers is often treated as hazardous waste and reapplied to crops, the remaining rinses are not. This work demonstrates that the wastewater generated in subsequent rinses can have high enough concentrations to impact worker health, cause off-target effects on crops, and potentially constitute a point source of pesticides. The practical implication is for improved recommendations and regulations regarding pesticide applicators and their cleanout process.

Assessment of bioburden on human and animal tissues: Part 1—Results of method development and validation studies

Recovered human and animal tissues are used extensively in surgery for wound repair and reconstruction. In preparation for the validation of chemical disinfection and radiation sterilization processes, studies were performed on the development and validation of quantitative bioburden recovery methods for human bone and soft tissue and also for porcine dermis. The use of a swab-based method was not considered due to the known poor efficiency of recovery for this technique. The "exhaustive extraction" and "inoculated product" approaches to validation of a bioburden recovery efficiency factor have inherent strengths and weaknesses; in this study, tissues were inoculated and also subjected to a series of extractions to determine if/when "exhaustion" occurred. Femoral and tibial shaft rings, iliac crest wedges, sections of Achilles tendon, a soft tissue composite sample, and porcine dermis, were inoculated at several sites with Bacillus atrophaeus spores, and then subjected to either shaking by hand, mechanical shaking, or sonication plus mechanical shaking. Each of these methods of agitation were performed in combination with three rinse (extraction) fluids: phosphate buffer (Butterfield's buffer), phosphate buffer with 0.2% polysorbate 80 (a surfactant), and water with 1% peptone and 1% polysorbate 80 (Fluid D). The highest recovery efficiencies were observed with sonication plus mechanical shaking; of the three extraction media, Fluid D gave the highest first-rinse recovery efficiency (65%) and Butterfield's buffer gave the lowest (39%). Each of the three recovery methods, however appeared to reach "exhaustion", a subsequent rinse giving less than 10% of the recovery found in the first rinse. The results demonstrated the importance of performing bioburden method development and validation studies. The method validation strategy described here, using a combination of tissue inoculation and repetitive extraction, showed the superiority of sonication plus mechanical shaking using Fluid D as the rinse medium. In addition, the use of only the exhaustive extraction approach could have resulted in the development of a methodology that consistently underestimated the bioburden present on/in recovered tissue.

Solar Cell Texturing: A Simplified Recipe

A method for cost reduction and green processing of silicon-based solar cells by replacing cleaning baths with simplified rinsing processes is presented. Reduction of the amount of chemical and water used is demonstrated. The rinsing processes can be used for acidic texturing using HF/HNO3 or alkaline-based texturing using KOH. Rinses with low-concentration of chemicals have been show to be just as effective as concentrated chemicals. Results show that the initial texturing topology and reflectivity is not affected by the subsequent rinses and the doping uniformity is also the same as with the standard chemicals.

PH-responsive behavior of selectively quaternized diblock copolymers adsorbed at the silica/aqueous solution interface

The desorption and subsequent pH-responsive behavior of selectively quaternized poly(2-(dimethylamino)ethyl methacrylate)- block-poly(2-(diethylamino)ethyl methacrylate) (PDMA–PDEA) films at the silica/aqueous solution interface has been characterized. The copolymer films were prepared at pH 9, where micelle-like surface aggregates are spontaneously formed on silica. The subsequent rinse with a copolymer-free electrolyte solution adjusted to pH 9 causes partial desorption of the weakly or non-quaternized copolymers, but negligible desorption for the highly quaternized copolymers. Further rinsing with a pH 4 electrolyte solution results in additional desorption and extension (swelling) of the remaining adsorbed copolymer film normal to the interface. This pH-responsive behavior is reversible for two pH cycles (9–4–9–4) as monitored by both quartz crystal microbalance with dissipation monitoring (QCM-D) and also ζ potential measurements. The magnitude of the pH-responsive behavior depends on the mean degree of quaternization of the PDMA block. Moreover, a combination of contact angle data, ζ potential measurements and in situ atomic force microscopy (AFM) studies indicates that the pH-responsive behavior is influenced not only by the number of cationic binding sites on the adsorbed copolymer chains but also by the adsorbed layer structure.

Nondestructive quantitative synchrotron grazing incidence X-ray scattering analysis of cylindrical nanostructures in supported thin films

Nondestructive nanostructural analysis is indispensable in the development of nanomaterials and nanofabrication processes for use in nanotechnology applications. This paper demonstrates a quantitative, nondestructive analysis of nanostructured thin films supported on substrates and their templated nanopores by using grazing incidence X-ray scattering and data analysis with a derived scattering theory. The analysis disclosed that vertically oriented nanodomain cylinders had formed in 20–100 nm thick films supported on substrates, which consisted of a mixture of poly(styrene-b-methyl methacrylate) (PS-b-PMMA) and PMMA homopolymer, and that the PMMA nanodomain cylinders were selectively etched out by ultraviolet light exposure and a subsequent rinse with acetic acid, resulting in a well ordered nanostructure consisting of hexagonally packed cylindrical nanopores.

Instrumental and sensory quantification of oral coatings retained after swallowing semi-solid foods

After a mouthful of food has been swallowed, some food material is always retained in the mouth. With semi-solid foods this is in the form of a coating that adheres to the oral mucosa. The amount and location of this material may play an important role in food sensations. In this study two quantitative methods of describing the coatings, generated by a set of 16 model custards varying in degree of lubrication (fat content) and degree of viscosity (starch concentration) are investigated. In the first method, a trained quantitative descriptive analysis panel (N=8) was instructed to take single mouthfuls of semi-solid foods, swallow and then rinse twice for 5s with water and spit out. The turbidity of the rinse water was then measured. During the same session, sensory assessments of the products were obtained. In the second method the thickness of the coating on the anterior and middle one-thirds of the tongue was quantified using a pair of opto-electronic reflectance sensors mounted on a probe which was placed on the tongue, one sensor measuring the anterior part of the tongue the other the posterior (middle third) of the tongue. Turbidity of the first rinse related strongly to the food's viscosity, as well as to sensory attributes associated with the food's fat content and viscosity, such as perceived thickness, creaminess and fattiness. Turbidity of subsequent rinses related primarily to fat content. These results indicate that turbidity of rinse water is a useful tool in fundamental (e.g., food texture research) as well as applied research (e.g., product development and quality assurance in food industry). Reflectance varied primarily with fat content and did not relate well to sensory attributes.

Microemulsion formation and detergency with oily soils: III. Performance and mechanisms

AbstractThe objective of this study was to investigate the correlation between oily soil removal efficiency and low oil‐water interfacial tension (IFT) generated by microemulsion formation. A mixture of sodium dioctyl sulfosuccinate, alkyl diphenyl oxide disulfonate, and sorbitan monooleate was selected as a detergent formulation to evaluate detergency performance for two highly hydrophobic oils: hexadecane and motor oil. The maximum detergency corresponds to formation of a Winsor Type III microemulsion as well as to the supersolubilization region, which is a Winsor Type I microemulsion close to the Winsor Type III region. In addition, the oil removal in the rinse step is almost as high as that in the wash step for both regions. We propose the following mechanism to explain these results: During the wash step, the contact angle of the oil on the fabric surface is progressively increased, resulting in the detachment of the oil droplets. However, owing to the very low IFT, the spreading effect is dominant, thereby causing incomplete oil removal. During the subsequent rinse step, the IFT increases, passing through a composition at which the rollup mechanism causes additional oil removal. These results demonstrate that microemulsion formation and the resulting IFT reduction are important mechanisms in oily soil detergency.

A Method for the Aqueous Deacidification of Oxidized Paper

Concentrated aqueous solutions of pH-neutral salts were evaluated for their effectiveness at deacidifying photo-oxidized filter paper. Short immersions in these solutions successfully neutralized acidic paper sheets. However, subsequent rinses to remove excess salt were necessary to prevent yellowing upon thermal aging. Sheets treated with concentrated solutions of calcium chloride showed no significant chemical damage from the treatment and deteriorated more slowly during thermal aging compared with untreated sheets. Sample papers that were given a dilute alkaline rinse after the concentrated salt treatment degraded less upon thermal aging than papers treated with either solution alone. This method of neutral deacidification was also evaluated for use prior to chemical reduction of oxidized paper with sodium borohydride. A treatment procedure involving steps of deacidification, chemical reduction, and alkalization was found to greatly stabilize photo-oxidized papers against thermal aging, as well as to produce a bleaching effect.

Enzymatic lipid removal from surfaces—lipid desorption by a pH-induced “electrostatic explosion”

Removal of lipidic molecules from surfaces can be accomplished using detergents containing lipases. Surface cleaning is usually performed under alkaline conditions due to increased solubility of the hydrolysis products, especially free fatty acids. This paper shows that removal of a triacylglycerol film from a surface can be dramatically enhanced in a sequential system where pH is shifted to alkaline conditions after an initial lipolytic reaction period at or below neutral pH. Data from three different biophysical techniques, attenuated total reflection Fourier transform infrared spectroscopy (ATR-FTIR), quartz crystal microbalance with dissipation monitoring (QCM-D), and total internal reflection fluorescence spectroscopy (TIRF) clearly show the effects of such cleaning procedure. Initially the reaction is carried out at pH below the p K a value of the fatty acids formed upon triacylglycerol hydrolysis, and the protonated fatty acids accumulate in the film. The mechanism of lipid removal, induced by increasing pH to a value above the fatty acid p K a, is explained by a burst caused by electrostatic repulsion between rapidly ionised fatty acids, i.e. by an “electrostatic explosion”. Performing the initial hydrolysis at pH 6 and the subsequent rinse at pH 10, using triolein as model substrate, lipid removal from surfaces by both commercial detergent lipases and non-commercial lipases was significantly improved compared to a reaction at constant pH 10.

The Cu/n-GaAs schottky barrier diodes prepared by anodization process

The metal-insulating semiconductor (MIS) Cu/n-GaAs diodes with thin anodic-insulating layer, which is formed by anodic oxidazation on the n-GaAs substrate in aqueous 4C2H6O2+2H2O+0.1H3PO4 electrolyte with pH=2.02; anodically untreated control Cu/n-GaAs diodes; and anodically treated Cu/n-GaAs diodes (several steps of anodization in the same electrolyte followed by a dip in diluted aqueous HCl solution and a subsequent rinse in deionized water) have been prepared. The anodization has increased the barrier heights as well as the ideality factors. We have obtained barrier heights of approximately 0.68 eV, 0.90 eV, and 0.92 eV for the control sample, anodically treated sample, and MIS sample, respectively, adding the contribution caused by image-force effect only. Thus, the barrier height has been increased by at least 140 meV. Furthermore, we have calculated a mean tunneling-barrier height of x=0.025 eV for the MIS Cu/n-GaAs Schottky barrier diode (SBD).

Barrier height enhancement in the Au/n-GaAs Schottky diodes with anodization process

We have fabricated Au/n-GaAs Schottky barrier diodes with different surface treatments. Prior to Au evaporation on the n-GaAs(100), the first kind of samples has consisted of dip in the 5H2SO4+H2O2+H2O solution and then H2O+HCl solution, followed by a rinse in de-ionized water (sample AuG1), the second kind of sample has consisted of several steps of anodization in aqueous 4C2H6O2+2H2O+0.1H3PO4 electrolyte with pH=2.02 each followed by a dip in diluted aqueous HCl solution and a subsequent rinse in de-ionized water (sample AuG2), and the third kind of samples one anodization step only (MIS sample AuG3). We have found the lowest values of both the barrier heights and ideality factors for the reference sample AuG1. The anodization, on the other hand, has increased the barrier heights as well as the ideality factors. Furthermore, the barrier heights of approximately 0.80, 0.90, and 1.01 eV for the AuG1, AuG2, and AuG3 diodes, respectively, have been obtained adding the contribution due to image force effect.

High-barrier height Sn/p-Si schottky diodes with interfacial layer by anodization process

We have fabricated the Sn/p-Si Schottky barrier diodes with different surface treatments. Prior to the Sn evaporation on the p-Si(0 0 1), the first kinds of samples consisted of a dip in diluted aqueous HF solution followed by a rinse in de-ionized water (sample 1, SD1), the second kinds of samples several steps of anodization in aqueous KOH solution each followed by a dip in diluted aqueous HF solution and a subsequent rinse in de-ionized water (sample 2, SD2), and the third kinds of samples one anodization step only (sample 3, SD3). We have found the lowest values of both the barrier heights and ideality factors with the diodes of preparation type SD2. The anodization, on the other hand, have increased both, the barrier heights as well as the ideality factors. The extrapolation of the barrier heights versus ideality factors plot to the ideality factor determined by the image force effect have given the laterally homogeneous barrier heights of approximately 0.75 and 0.92 eV for the SD2 and SD3 diodes. Furthermore, we have calculated a mean tunneling barrier height of χ=0.12 eV for the MIS Sn/p-Si diodes with the anodic oxide layer.

The role of plasma coating on the permeation of cytokine-inducing substances through dialyser membranes

We studied the effects of coating of dialyser membranes with plasma proteins on the permeation of bacteria-derived cytokine-inducing substances (CIS). An in vitro dialysis circuit using polysulphone (PS) or modified cellulose triacetate (mCT) dialysers was used. Precoating of the dialysers was performed by recirculation of 10% normal human plasma for 30 min in the blood compartment and subsequent rinse with pyrogen-free saline. Samples from the blood compartment were tested for induction of interleukin-1 alpha (IL-1 alpha), interleukin-1 beta (IL-1 beta) and tumour necrosis factor (TNF alpha) at various time points after challenging the dialysate with sterile culture supernatants from Pseudomonas aeruginosa. Contamination of the dialysate resulted in the appearance of CIS in the blood compartment of both polysuphone modified cellulose triacetate (IL-1 alpha: PS, time 0: 81 +/- 11 pg/ml, time 60 min: 4747 +/- 1822 pg/ml, P < 0.05; mCT, time 0: 235 +/- 141 pg/ml, time 60 min: 1632 +/- 531 pg/ml, P < 0.05). The plasma protein layer reduced the penetration of CIS significantly only for polysulphone (IL-1 alpha: PS, time 60: 4747 +/- 1822 versus 880 +/- 525 pg/ml, P < 0.05; modified cellulose triacetate, time 60 min: 1632 +/- 531 pg/ml versus 930 +/- 326 pg/ml). Samples from the blood compartment contained < 6 pg/ml LAL-reactive material at all time points. We conclude that plasma coating of polysulphone dialysers reduces the permeability for CIS derived from Pseudomonas, either by reducing the effective pore size or by adsorption of proteins that bind CIS.(ABSTRACT TRUNCATED AT 250 WORDS)

Variability in Broiler Carcass Bacterial Load at Three Abattoirs, as Measured by a Hydrophobic Grid Membrane Filter Interpreter

In this observational study, the variability of broiler carcass bacterial load was investigated at three federally inspected abattoirs, using an automated hydrophobic grid membrane filter interpreter system. The measurement protocol involved: whole carcass rinses aided by a mechanical carcass shaker; filtration of rinse solutions through hydrophobic grid membrane filters (HGMF) (ISO-GRID®, QA Laboratories, Ltd., Toronto, Ont.); and use of an automated HGMF interpreter (MI-100 HGMF Interpreter System, Richard Brancker Research, Ltd., Ottawa, Ont.). Carcass and lot mean bacterial loads were measured, respectively, in units of log10 most probable number (MPN) of mesophylic aerobic colony forming units per gram of carcass (LgMPN/g), and slaughter lot mean LgMPN/g (LMLgMPN/g). Whole carcass rinses were conducted on a total of 1,917 carcasses, among 96 slaughter lots from three abattoirs. Overall, the LgMPN/g ranged from 1.054 to 4.180 with a mean of 2.585 and a variance of 0.263. These corresponded to MPN/g counts from 11 to 15,135 and a geometric mean of 385 MPN/g. Statistically significant differences were observed between abattoirs and between lots within abattoirs. The intra-abattoir correlation coefficient of LgMPN/g was r = 0.180 (p < 0.001). The within abattoir intralot correlation coefficient was r = 0.259 (p < 0.001). In this data set, approximately 56, 26, and 18% of the variability in LgMPN/g were attributed to factors operating at the individual bird, lot, and abattoir levels of organization, respectively. Factors significantly associated with LMLgMPN/g included: abattoir (p < 0.001), transportation time from farm to abattoir (p < 0.001), and waiting time from arrival at the abattoir yard to actual slaughter (p = 0.002). Analysis of a series of five repeat rinses, conducted on one bird from each of the 96 study lots, demonstrated that bacterial counts in the second to fifth sequential rinses were positively associated with the bacterial count of the first rinse. Also, after adjusting for the initial count, a pattern of decreasing counts was observed in subsequent rinses.

Thermal desorption mass spectrometric and x-ray photoelectron studies of etched surfaces of polytetrafluoroethylene

The etching of polytetrafluoroethylene (PTFE) with Na solutions is known to lead to a loss of F, a loss which is correlated with enhanced adhesion. Subsequent heating partially restores surface F with a concurrent loss of adhesion strength. We have combined X-ray photoelectron spectroscopy (XPS) and gas phase mass spectroscopy for in situ measurements of the processes that occur as the fluorocarbon is heated. An array of volatile products, which vary with the specific treatment, desorb from etched PTFE. Among these are: N 2 and low molecular weight fluorocarbons, the amounts of which monotonically decrease with increasing exposure to the etching solution (and probably result from the bulk); species such as CO and CO 2, which in part result from surface impurities; and water and acetone which result from the rinse steps following the etching process. XPS measurements show that etching produces a major loss of surface F and a gain of surface O. The latter probably results from the subsequent rinse steps. Heating produces a substantial recovery in surface F with only a small decrease in the surface O, and the gain in surface F is shown to occur at a higher temperature than the desorption of any species from the surface. Thus, desorption of products from the surface is decoupled, in terms of both the distribution of products and their relative temperatures, from the surface changes as monitored by XPS. This decoupling suggests that the increase in surface F results from diffusion of low molecular weight fluorocarbons from the bulk or a transition region, or from a rearrangement of the sponge-like surface region produced in the etching process.

Accumulation of Cu and Zn in human dental plaque in vivo.

The rentention of copper and zinc in dental plaque in vivo after repeated mouth rinses with aqueous solutions of salts of these elements was measured by neutron activation analysis. The reduction in acidogenicity of plaque after exposure to the metal ions was also monitored. A significant reduction (p < 0.05) in acid formation was seen in plaque exposed to five subsequent rinses. The mean amounts of Cu and Zn in plaque increased more than 10-fold after five rinses. It is concluded that these metals are retained in plaque and that their concentrations in plaque increase with repeated applications.