Mechanical Scrubbing Research Articles

Nanopatterning on Nonplanar and Fragile Substrates with Ice Resists

Electron beam (e-beam) lithography using polymer resists is an important technology that provides the spatial resolution needed for nanodevice fabrication. But it is often desirable to pattern nonplanar structures on which polymeric resists cannot be reliably applied. Furthermore, fragile substrates, such as free-standing nanotubes or thin films, cannot tolerate the vigorous mechanical scrubbing procedures required to remove all residual traces of the polymer resist. Here we demonstrate several examples where e-beam lithography using an amorphous ice resist eliminates both of these difficulties and enables the fabrication of unique nanoscale device structures in a process we call ice lithography. (1, 2) We demonstrate the fabrication of micro- and nanostructures on the tip of atomic force microscope probes, microcantilevers, transmission electron microscopy grids, and suspended single-walled carbon nanotubes. Our results show that by using amorphous water ice as an e-beam resist, a new generation of nanodevice structures can be fabricated on nonplanar or fragile substrates.

Transfer of Salmonella Enteritidis to four types of surfaces after cleaning procedures and cross-contamination to tomatoes

The objectives of the present study were to evaluate the spread of Salmonella Enteritidis to different cutting boards (wood, triclosan-treated plastic, glass, and stainless steel) from contaminated poultry skin (5 log CFU/g) and then to tomatoes and to analyze the effect of different protocols used to clean these surfaces to control contamination. The following procedures were simulated: (1) no cleaning after handling contaminated poultry skin; (2) rinsing in running water; (3) cleaning with dish soap and mechanical scrubbing; and (4) cleaning with dish soap and mechanical scrubbing, followed by disinfection with hypochlorite. The pathogen was recovered from all surfaces following procedure 1, with counts ranging from 1.90 to 2.80 log, as well as from the tomatoes handled on it. Reduced numbers of S. Enteritidis were recovered using the other procedures, both from the surfaces and from the tomatoes. Counts were undetectable after procedure 4. From all surfaces evaluated, wood was the most difficult to clean, and stainless steel was the easiest. The use of hypochlorite as a disinfecting agent helped to reduce cross-contamination.

The influence of important factors on ultrafiltration of oil/water emulsion using PVDF membrane modified by nano-sized TiO2/Al2O3

Polyvinylidene fluoride (PVDF) membranes modified by the nano-sized TiO2/Al2O3 were applied to the separation of oil/water emulsion. Experiments were carried out in a constant flux dead-end Ultrafiltration cell, and the influence of operating parameters such as: trans-membrane pressure (TMP), and feed properties e.g. pH, initial oil concentration, and total dissolved solid (TDS) of the feed solution on membrane performance were investigated. The results show that all the parameters except TDS played an important role in Relative Flux (RF) of this UF process, Moreover, Modified PVDF membrane (MPM) showed a better antifouling character than PVDF membrane (PM) under the same conditions. A satisfying flux recovery was observed for fouled membranes when being washed with pure water, and even better when washing with NaClO solution. However, reversed cleaning by water and mechanical scrubbing led to the RF decreased sharply. It was concluded that MPM may be considered feasible in treating oily wastewater. Due to the enhanced hydrophilicity, all the modified PVDF membranes exhibited higher RF and better antifouling property compared with the control PVDF membrane under the same operational conditions.

Are Dropped Osteoarticular Bone Fragments Safely Reimplantable in Vivo?

There are limited data detailing the appropriate management of nondisposable autologous osteoarticular fragments that have been contaminated by the operating room floor. The goal of the present study was to perform a comprehensive, three-phase investigation to establish an appropriate intraoperative algorithm for the management of the acutely contaminated, but nondisposable, autologous osteoarticular bone fragment. Phase I of the study was performed to quantify the rate of contamination and microbial profile of human osteoarticular fragments that were dropped onto the operating room floor (n = 162). Phase II was performed to assess the feasibility and optimal means of decontaminating 340 similar fragments that underwent controlled contamination with bacteria that were identified in Phase I; decontamination was performed with use of cleansing agents that are routinely available in an operating room. Phase III was performed to assess the effect of each decontamination process on fragment chondrocyte viability through histologic evaluation. The contamination rate in Phase I was 70%. Coagulase-negative Staphylococcus was the most commonly cultured organism. In Phase II, varying exposure time to the chemical agents did not make a significant difference in decontamination rates. Mechanical scrubbing was superior to mechanical saline solution lavage (zero of fifty-six cultures compared with twenty of fifty-six cultures were positive for coagulase-negative Staphylococcus; p < 0.001). As a whole, bactericidal agents were found to be more effective decontaminating agents than normal saline solution. Povidone-iodine and 4% chlorhexidine gluconate were the most effective decontaminating agents, with none of the twenty-eight specimens that were decontaminated with each agent demonstrating positive growth on culture. Phase III demonstrated that the groups that were treated with normal saline solution and povidone-iodine retained the greatest number of live cells and the least number of dead cells. Mechanical scrubbing significantly decreased chondrocyte viability as compared with a normal saline solution wash (p < 0.05). The majority of osteochondral fragments that contact the operating room floor produce positive bacterial cultures. Five minutes of cleansing with a 10% povidone-iodine solution followed by a normal saline solution rinse appears to provide the optimal balance between effective decontamination and cellular toxicity for dropped autologous bone in the operative setting.

Standardized Protocol for Artery-Only Fingertip Replantation

Artery-only fingertip replantation can be reliable if low-resistance flow through the replant is maintained until venous outflow is restored naturally. Injuring the tip of the replant to promote ongoing bleeding augmented with anticoagulation usually accomplishes this; however, such management results in prolonged hospitalization. In this study, we analyzed the outcomes of artery-only fingertip replantation using a standardized postoperative protocol consisting of dextran-40, heparin, and leech therapy. Between 2001 and 2008, we performed 19 artery-only fingertip replants for 17 patients. All patients had the replanted nail plate removed and received intravenous dextran-40, heparin, and aspirin to promote fingertip bleeding and vascular outflow. Anticoagulation was titrated to promote a controlled bleed until physiologic venous outflow was restored by neovascularization. We used medicinal leeches and mechanical heparin scrubbing for acute decongestion. By postoperative day 6, bleeding was no longer promoted. We initiated fluorescent dye perfusion studies to assess circulatory competence and direct further anticoagulant intervention if necessary. The absence of bleeding associated with an initial rise followed by an appropriate fall in fluorescent dye concentration would trigger a weaning of anticoagulation. All of the 19 replants survived. The average length of hospital stay was 9 days (range, 7-17 d). Eleven patients received blood transfusions. The average transfusion was 1.8 units (range, 0-9 units). All patients were happy with the decision to replant, and the cosmetic result. A protocol that promotes temporary, controlled bleeding from the fingertip is protective of artery-only replants distal to the distal interphalangeal joint until physiologic venous outflow is restored. The protocol described is both safe and reliable. The patient should be informed that such replant attempts may result in the need for transfusions and extended hospital stays, factors that can help the physician and patient decide whether to proceed with replantation. Therapeutic IV.

Adjunctive Use of Superoxidized Solution in Chest Wall Necrotizing Soft Tissue Infection

A 39-year-old Indian man presented with necrotizing soft tissue infection of his right forearm and previously undiagnosed diabetes mellitus. The infection progressively worsened to involve his right lateral chest wall despite multiple debridements and systemic antibiotics. His right arm was eventually disarticulated along with wide debridement of the surrounding tissue. Aggressive wound debridement, mechanical scrubbing, and irrigation were then initiated every 8 hours. A superoxidized solution was later introduced as a wound irrigant and dressing agent. The large defect was suitable for split-thickness skin grafting after 16 days of a strict wound management routine with the superoxidized solution.

The potential use of hydrogen peroxide in water well rehabilitation

AbstractA water supply borehole in the Sherwood Sandstone aquifer in Warrington, UK was found to be infested with iron bacteria that resulted in large ochreous deposits and damaged the pump. Before the pump was replaced, the borehole was treated using hydrogen peroxide. Comparison of the borehole condition seen in CCTV surveys carried out before and after treatment shows that previously observed bacterial growths had been removed. A specific capacity curve was constructed from step test data and used to assess the borehole yield under operational conditions. This showed that the iron bacteria had increased drawdown by some 20% and that the treatment had restored the previous yield characteristics. The improvement is thought to be due to a mechanical scrubbing effect caused by the vigorous release of oxygen bubbles during the decay of the peroxide.

Precision microfinishing by electro-chemical honing

Surface condition and shape deviations produced by manufacturing processes have pronounced influence on the functional performance of engineering components. This paper reports a comprehensive study on the influence of several key process parameters of Electro-Chemical Honing (ECH), a precision microfinishing technology, on dominant machining criteria the surface roughness improvement. The current intensity, electrolyte concentration, stick-out pressure and stick grit-size are found to be the major players influencing the response significantly. With distinct coordination of electrolytic dissolution and mechanical scrubbing, ECH can be utilized as a precision microfinishing process for critical components of tribological significance. More than 90% improvement in surface finish with precisely controlled shape deviations can be achieved. Important features of the ECH setup that was designed and developed indigenously are also highlighted.

Calcified Integra membrane: one possible cause of skin graft failure in the second stage of Integra use

The use of Integra as an artificial dermal regeneration template is well established. Following initial use of Integra to resurface the wound bed, the second stage involves removal of the silicone layer and application of a split skin autograft. Previous histological studies have shown that neo-vascularisation of the Integra occurs between 2 and 4 weeks, and therefore, skin grafting over the Integra is recommended at any time after this period. We present a case of an infant with 38% total percentage of body surface area in whom we performed early burn excision and immediate application of Integra. In this case, the second stage of skin grafting was delayed, resulting in the formation of a crusty white membrane over the Integra. Histological analysis with a Von Kossa stain revealed evidence of calcification within the superficial layers of the Integra. Each leg was initially treated differently. In one leg, mechanical scrubbing of this layer was performed. The subsequent results of grafting in this leg were unsatisfactory, and repeat grafting was necessary. In the other leg, tangential excision using a Watson knife was performed before grafting. This produced much better results in terms of skin graft ‘take’. The causes of calcification in biomaterials are discussed, and recommendations are made on the basis of the clinical findings in this particular case.

Experimental investigations on electrochemical honing

Electrochemical honing (ECH) is an electrolytic precision mircofinsihing technology based on the hybridization of the electrochemical machining and conventional honing process principles to provide the controlled functional surface generation and fast material removal capabilities in a single action. This paper presents the distinctive findings of comprehensive experimental investigations designed to explore the influence of key ECH process parameters on the work surface microgeometrical, part-macrogeometrical, and material removal aspects. The current intensity, electrolyte concentration, stick-out pressure, and stick grit size are found to be the major players in the process. Interactions between current intensity, electrolyte concentration, and speed ratio play a vital role, specifically for macrogeometrical performance. Proper electrolyte composition and stick grit-size selections and a distinct coordination of electrolytic dissolution and mechanical scrubbing are crucial for the optimal performance. Work surface characterization reveals a nano-finished plateau-honed work surface featured with a uniform roughness value, impressive surface characteristic parameters, no trace of cold-worked material, or any adverse effect of the process. This, accompanied with precise part macro- geometry, can result in an unexcelled tribological performance of the components. Key features of an ECH set-up that was designed and developed incorporating several unique features are also highlighted.

Carbon nanoparticles grown in the subsurface-region of porous SiO2

Carbon nanoparticles (CNPs) were grown in the subsurface-region of porous SiO2 templates that had been subjected to plasma enhanced chemical vapour deposition. The over-layer multiwall carbon nanotubes (MWCNTs) grown in the surface region of the template were removed by a sonication process. Mechanical scrubbing of the template surface was used to remove the subsurface for investigation. The powder obtained was dispersed in ethanol onto copper-grids for characterization by electron microscopy, electron diffraction and micro-Raman spectroscopy. Elliptical, faceted and grape-shaped CNPs were observed by electron microscopy with electron diffraction patterns showing short range orderings. The Raman spectrum of the CNPs was found to be distinctly different from that of the over-layer MWCNTs in that the D-band (at ∼1385 cm−1) merged with the G-band (at ∼1552 cm−1). It seems that the CNPs in the subsurface-region grew simultaneously with the over-layer MWCNTs. A possible growth mechanism is proposed. The I–V characteristic of the CNPs, recorded by scanning tunnelling microscopy, was found to be asymmetric and characteristic of degenerately doped p–n junction diodes.

Processing of concretes with a high power CO 2 laser

Laser material processing, being a non-contact process, minimizes many of the complexities involved in the decontamination and decommissioning of nuclear facilities. A high power laser beam incident on a concrete surface can produce spalling, glazing or vaporization, depending upon the laser power density and scan speed. This paper presents effect of various laser processing parameters on the efficiency of material removal by surface spalling and glazing. The size of laser beam at constant fluence or energy density had significantly different effect on the spalling process. In thick concrete block cutting the flow or removal of molten material limits the cutting depth. By employing repeated laser glazing followed by mechanical scrubbing process cutting of 150 mm thick concrete block was carried out. Gravitation force was utilized for molten materials to flow out while drilling holes on vertical concrete walls. The dependence of the incident laser beam angle on drilling time was experimentally studied.

A flotation study of refuse pond coal slurry

The flotation behavior of a refuse pond fine coal slurry sample was studied using mechanical and column flotation techniques. Flotation parameters investigated included type and dosage of frother and collector, agitation speed, scrubbing time, slurry pH, etc. for the mechanical flotation cell, and air flow rate, feed flow rate, and wash water flow rate for the column flotation. Flotation kinetics was also studied in the mechanical flotation cell. The results showed that the coal sample was very difficult to clean by flotation. Low yield (5–15%) and low combustible recovery (6–23%) and high product ash (about 22%) were obtained when methyl-isobutyl-carbinol (MIBC) was used as frother and #2 fuel oil as collector. Adjustment of operating parameters such as agitation intensity showed limited effects. However, flotation yield was significantly improved when MIBC and #2 fuel oil were replaced with frother P948 and collector SPP. Mechanical scrubbing was unable to restore the floatability of the coal sample. ‘Ken-Flote’ column flotation was inferior to mechanical flotation for oxidized coal and possible reasons were given.

Drum Side Treated Foil: Advanced Copper Foil Technology for Multilayer Printed Circuit Board Applications

Drum Side Treated Foil is an electrodeposited copper foil with the adhesion promoting treatment applied to the drum, or shiny side, instead of to the more typical matte side. The treated drum side is then laminated to the core prepreg, leaving the matte side exposed. Advantages of this technology, compared with standard copper foil, include: Simplified, non‐subtractive pre‐cleaning, eliminating the need for microetching, pumice cleaning or mechanical scrubbing; improved resist adhesion for higher innerlayer yield; ultra‐low profile for cleaner etching and improved line definition; higher oxide‐to‐prepreg bond strength for improved board reliability; improved controlled impedance consistency and predictability. A technical description of Drum Side Treated Foil’s inherent advantages, processing recommendations and results of several case studies comparing printed circuit board yields with Drum Side Treated Foil vs standard foil are presented in this paper.

Cleaning of SiO2: Differences Between Thermal and Deposited Oxides

ABSTRACTThe effects described in this paper are specific to cleaning with mechanical brush scrubbing. Oxides, both thermally grown and deposited are common cleaning applications for mechanical brush scrubbing. Thermally grown oxides present higher final defect counts after scrubbing with deionized water compared to deposited oxides. In this paper we present our results on the cleaning of unpolished and polished oxide surfaces and show differences in these results to be dependent on the chemistry used for cleaning and the degree of hydrophilicity of the wafer surface.

A micromachined array probe card-characterization

An array probe card fabricated on a silicon wafer for high performance and high pin count applications is characterized. The probe card is capable of providing a very large number of probe tips (>1000) that offer a contact resistance of less than 2 /spl Omega/. A novel approach to replacing the mechanical scrubbing motion with an electrical breakdown process is presented. The probe card is capable of operating at elevated temperatures for extended periods of time, offers alternative probe tip configurations, and is capable of probing a variety of pad metals. Controlled impedance (50 /spl Omega/) striplines that run all the way to the probe tips offer a delay time of 68 ps/cm, 3 GHz bandwidth, and far-end cross-talk of -49 dB/cm at a pitch of 32 /spl mu/m.< <ETX xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">&gt;</ETX>

Clinical Evaluation of the Efficacy and Safety of a New Sonic Toothbrush

The efficacy and safety of a new sonic toothbrush were studied in this single-blind study. The sonic toothbrush combines acoustic vibrations and dynamic fluid activity surrounding the bristles with direct mechanical scrubbing of tooth surfaces. Fifty-one subjects were randomly assigned to either the sonic or the manual toothbrush. Plaque scores were assessed before and after a 2-minute brushing at baseline and 1, 2, and 4 weeks. Gingivitis and sulcular bleeding scores were also taken at each evaluation. To assess long-term safety, 29 subjects returned after 6 months of product use. Repeated measures analysis of variance of the total mean plaque score indicated a significant difference between the devices over time (P < 0.01), with the sonic toothbrush demonstrating a greater level of plaque removal on all tooth surfaces. On average, the plaque reduction from the baseline score for the sonic toothbrush was 3 times greater than the manual brush. However, when broken down by dental region, the sonic toothbrush demonstrated an improved level of plaque removal ranging from 1.5 to 11.9 times better than the manual brush, with the greatest improvement in the interproximal and lingual areas. Both the gingivitis and sulcular bleeding scores exhibited a similar, significant reduction (P < 0.005) over time for both devices with an approximate 17% decrease in the gingivitis index and a 33% decrease in sulcular bleeding sites. Safety assessment after 6 months of use indicated no soft tissue abnormalities which could be attributed to the products.(ABSTRACT TRUNCATED AT 250 WORDS)

Cold-rolled steel alkaline cleaning before annealing : a parametric study

In phosphate-based alkaline electro-cleaning surface oil residues and iron fines are best eliminated by those process steps involving some degree of mechanical scrubbing.

Corneal Ablation in Rabbits Using an Infrared (2.9-μm) Erbium:YAG Laser

The authors used a 2.9-μm infrared erbium:YAG (ER:YAG) laser to ablate the central corneas (a 3.5-mm wide, 180-μm deep area) of ten albino rabbits. In group 1(10 eyes), the central epithelium was removed by mechanical scrubbing to ablate the anterior stroma. In group 2 (10 eyes), a central anterior corneal cap was removed to ablate the midstroma. In group 1, epithelial wound healing occurred in 2 to 3 days. A mild anterior haze was observed with the slit lamp, but it gradually cleared in most eyes of both groups. Histologic specimens were obtained immediately and at 2 and 6 months after ablation for light and transmission and scanning electron microscopy. This acute histopathologic study did not show any endothelial damage even after ablations at 300-μm depth, although there was thermal damage more prominent at the borders of the ablated area for an extension of 40 μm. After 2 months, in the group 1 eyes, the regenerated epithelium appeared normal except for a thickening at the margins of the ablated area. Six months postoperatively there was still epithelial thickening at the margins of the remodeled zone. The basement membrane was present with anchoring filaments and hemidesmosomes. The healing of the anterior (group 1) and midstroma (group 2) occurred with some degree of disorganization of the lamellae and an increase in the population of keratocytes. The density of keratocytes at the ablated areas at 6 months was reduced in comparison with the 2-month observation. By photokeratoscopy, the corneas were smooth and slightly flattened. The authors conclude that corneal ablation using an ER:YAG laser at 2.9 μm may meet the criteria for photorefractive keratectomy (PRK).

An Investigation Into the Ability of Correcting Error in ECH

Summary Electro-chemical Honing (ECH) is a fine machining method which has been well acknowledged as a means to produce excellent surface quality. But experiments show that if the protective ability of the oxide film on the workpiece surface could be fully utilized, and a distinot mechanical scrubbing trace on the workpiece can be guaranteed, it could become a means to correct geometric inaccuracy too. The authors propose the ratio of metal removal with and without mechanical scrubbing λ = 7 with /V without to be used as a characteristic parameter indicating the ability of correcting error (ACE). Equipments concerned have been built, and the λ value of different electrolytes were determined. A series of experiments and investigation have been made on the questions such as: How is the projecttive ability of that oxide film on the workpiece surface. How is the EC dissolution intensity field along the tooth profile. The question whether a minimum error will be retained no matter how long the ECH processes last and so on. A formula for calculating the stock allowance of ECH is derived. The authors believe that a new method of precision machining with very distinguished feature could be developed. The accuracy of which could be of the order of within one micron.