Laser and other cleaning procedures for aerospace moulds and a study of mould release agents

A selection of cleaning procedures are discussed which may be used to remove epoxide resin flash contamination bonded on metal and carbon fibre reinforced composite mould tooling that is used in the aerospace industry. Laser ablation, dry ice blasting and chemical cleaning using sodium hydride are three cleaning procedures studied in depth and have been used to treat a range of industrially sourced and model substrates, and contaminants. The effectiveness of the different cleaning regimes have been evaluated using Scanning Electron Microscopy, Atomic Force Microscopy, Auger Electron Spectroscopy, X-ray Photoelectron Spectroscopy and other analytical characterisation techniques. The necessity to clean aerospace tooling arises when moulded parts cannot be easily released from mould tooling and this is associated with mould release residues that have built up over a number of moulding cycles and eventually cause the moulding to stick. A comprehensive literature review of non-stick coatings is given and alternative mould non-silicone based release coatings are evaluated using the above analytical techniques. Coatings investigated include; fluoroalkylsilane, fluoropolymers and metal-fluoropolymer composites and the problems and merits associated with each are discussed.EThOS - Electronic Theses Online ServiceGBUnited Kingdo

Surface cleaning technologies for the removal of crosslinked epoxide resin

This study provides details of the use of laser ablation and sodium hydride cleaning processes for the removal of crosslinked epoxide and other residues from resin transfer moulding (RTM) tool substrates, as used in the aerospace industry. The requirement for removal of such contamination is so that the mould can be re-used, following the subsequent application of an external release agent. These tools are, typically, fabricated from steel, nickel or CFRP composite materials; this paper focuses on the use of nickel substrates. The requirement to clean large surface areas quickly to satisfy commercial restraints, compromises the degree of absolute cleanliness that can be obtained. However, in applications where cleaning time is not a constraint, laser cleaning can be a very gentle and efficient process; typically Nd:YAG lasers find application in this area. In contrast, high power lasers are desirable for industrial scale applications where large areas need to be cleaned quickly. In this instance pulsed CO2 lasers can be used. The use of sodium hydride was also found to be highly successful in removing crosslinked organic contamination providing that suitable hard rinse and drying operations were also carried out

A cadaveric study of the anterolateral ligament: re-introducing the lateral capsular ligament.

PURPOSE: The purpose of this study was to verify and characterize the anatomical properties of the anterolateral capsule, with the aim of establishing a more accurate anatomical description of the anterolateral ligament (ALL). Furthermore, microscopic analysis of the tissue was performed to determine whether the ALL can morphologically be classified as ligamentous tissue, as well as reveal any potential functional characteristics. METHODS: Three different modalities were used to validate the existence of the ALL: magnetic resonance imagining (MRI), anatomical dissection, and histological analysis. Ten fresh-frozen cadaveric knee specimens underwent MRI, followed by anatomical dissection which allowed comparison of MRI to gross anatomy. Nine additional fresh-frozen cadaveric knees (19 total) were dissected for a further anatomical description. Four specimens underwent H&E staining to look at morphological characteristics, and one specimen was analysed using immunohistochemistry to locate peripheral nervous innervation. RESULTS: The ALL was found in all ten knees undergoing MRI and all nineteen knees undergoing anatomical dissection, with MRI being able to predict its corresponding anatomical dissection. The ALL was found to have bone-to-bone attachment points from the lateral femoral epicondyle to the lateral tibia, in addition to a prominent meniscal attachment. Histological sectioning showed ALL morphology to be characteristic of ligamentous tissue, having dense, regularly organized collagenous bundles. Immunohistochemistry revealed a large network of peripheral nervous innervation, indicating a potential proprioceptive role. CONCLUSION: From this study, the ALL is an independent structure in the anterolateral compartment of the knee and may serve a proprioceptive role in knee mechanics

Hot and cold cleaning methods: CO2 and Nd:YAG laser ablation, sodium hydride immersion and CO2 cryoblasting

Cleaning of RTM moulds – the problem! The removal of loosely bound or weakly adsorbed contamination from surfaces can usually be achieved using conventional cleaning methods such as solvents or proprietory aqueous-based cleaning solutions. However, the removal of fully crosslinked material which might be strongly adsorbed or chemisorbed onto surfaces, such as paints or adhesives, presents a much greater challenge. Similarly, residual epoxide resins remaining on the inside surfaces of resin transfer mould (RTM) tooling post curing are strongly adhered to the mould surface and need to be removed so that the mould can be reused. The mould materials are typically steel or nickel but may be compositebased. Conventional methods cannot fully remove residual epoxide material without the use of hazardous chemicals and mechanical removal can easily result in damage to the underlying mould which may compromise its reuse. Therefore, a number of novel cleaning solutions have been investigated to address the challenging problem of how to remove fully crosslinked epoxide resins from RTM mould surfaces

NASHA hyaluronic acid for the treatment of shoulder osteoarthritis: a prospective, single-arm clinical trial

Background: Osteoarthritis of the shoulder or glenohumeral joint is a painful condition that can be debilitating. Intra-articular injection with hyaluronic acid should be considered for patients not responding adequately to physical therapy or anti-inflammatory medication. Methods: This was a single-arm, open-label, prospective study of a single intra-articular injection of NASHA (non-animal hyaluronic acid) in patients with symptomatic glenohumeral osteoarthritis. Patients were followed up for 26 weeks post-treatment, during which time rescue medication with acetaminophen was permissible. The study objective was to demonstrate that a single injection of NASHA is well tolerated with an over-6-month 25% reduction in shoulder pain on movement, assessed using a 100-mm visual analog scale. Results: Forty-one patients were enrolled, all of whom received study treatment. The mean decrease in shoulder pain on movement score over the 6-month study period was -20.1 mm (95% CI: -25.2, -15.0 mm), corresponding to a mean reduction of 29.5% (22.0, 37.0%). Statistically significant improvements were also observed in shoulder pain at night and patient global assessment. There was no clear change over time in the percentage of patients using rescue medication and mean weekly doses were below 3500 mg. Seventeen patients (41.5%) experienced adverse events, all of which were mild or moderate. Two adverse events (both shoulder pain) were deemed related to study treatment. Conclusion: This study provides preliminary evidence that a single injection of NASHA may be efficacious over 6 months and well tolerated in patients with symptomatic glenohumeral osteoarthritis. Larger studies are needed for confirmation.Bioventus LLC, Durham, NC, USAOpen access journalThis item from the UA Faculty Publications collection is made available by the University of Arizona with support from the University of Arizona Libraries. If you have questions, please contact us at [email protected]

A review and comparative study of release coatings for optimised abhesion in resin transfer moulding applications

In this study, a number of abhesion promoting coatings were considered in terms of their physicochemical and release properties. The techniques used to further this study include; FEGSEM, AFM, profilometry, AFM, XPS, AES, SSIMS, FTIR and contact angle analysis for coating physical and chemical characterisation along with PF-AFM and other adhesion and mechanical tests to determine surface release properties. These coatings were applied to metal substrates and were based upon silicone, fluoropolymer or metal-PTFE composite chemistry, all being potentially useful as release films for resin transfer moulding (RTM) applications. The semi-permanent Frekote B15/710 NC mould release coating system, which is based on PDMS, proved extremely effective in terms of release against a cured epoxide applied under pressure. Although fluoroalkylsilane coatings offer a number of technological advantages for release applications they generally produce very thin coatings which conform any existing surface topography and adhesion through mechanical interlocking occurs. The commercial PTFE-based coatings were found to provide poor release properties due to the presence of surface microcracks which allowed epoxide penetration when cured under elevated pressure and temperature. Electroless Ni/PTFE composite coatings comprise hard nickel-phosphorus matrix containing a very fine dispersion of PTFE particles. The matrix proved sufficiently robust for industrial applications and the low friction and surface energy provided by the embedded PTFE combined with macroscopic scale surface roughness provided efficient mould release

The acute toxicity of copper to Gammarus fasciatus say, a freshwater amphipod

Gammarus fasclatus could, and possible should, be used as the experimental organism in conjunction with other organisms being used in laboratory bioassays.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/47981/1/128_2005_Article_BF01685414.pd

Total knee replacement after high tibial osteotomy: Time-to-event analysis and predictors

© 2021 Joule Inc. or its licensors. BACKGROUND: An important aim of high tibial osteotomy (HTO) is to prevent or delay the need for total knee replacement (TKR). We sought to estimate the frequency and timing of conversion from HTO to TKR and the factors associated with it. METHODS: We prospectively evaluated patients with osteoarthritis (OA) of the knee who underwent medial opening wedge HTO from 2002 to 2014 and analyzed the cumulative incidence of TKR in July 2019. The presence or absence of TKR on the HTO limb was identified from the orthopedic surgery reports and knee radiographs contained in the electronic medical records for each patient at London Health Sciences Centre. We used cumulative incidence curves to evaluate the primary outcome of time to TKR. We used multivariable Cox proportional hazards analysis to assess potential preoperative predictors including radiographic disease severity, malalignment, correction size, pain, sex, age, body mass index (BMI) and year of surgery. RESULTS: Among 556 patients who underwent 643 HTO procedures, the cumulative incidence of TKR was 5% (95% confidence interval [CI] 3%–7%) at 5 years and 21% (95% CI 17%–26%) at 10 years. With the Cox proportional hazards multivariable model, the following preoperative factors were significantly associated with an increased rate of conversion: radiographic OA severity (adjusted hazard ratio [HR] 1.96, 95% CI 1.12–3.45), pain (adjusted HR 0.85, 95% CI 0.75–0.96)], female sex (adjusted HR 1.67, 95% CI 1.08–2.58), age (adjusted HR 1.50 per 10 yr, 95% CI 1.17–1.93) and BMI (adjusted HR 1.31 per 5 kng/m2, 95% CI 1.12–1.53). INTERPRETATION: We found that 79% of knees did not undergo TKR within 10 years after undergoing medial opening wedge HTO. The strongest predictor of conversion to TKR is greater radiographic disease at the time of HTO

Validation of loci at 2q14.2 and 15q21.3 as risk factors for testicular cancer.

Testicular germ cell tumor (TGCT), the most common cancer in men aged 18 to 45 years, has a strong heritable basis. Genome-wide association studies (GWAS) have proposed single nucleotide polymorphisms (SNPs) at a number of loci influencing TGCT risk. To further evaluate the association of recently proposed risk SNPs with TGCT at 2q14.2, 3q26.2, 7q36.3, 10q26.13 and 15q21.3, we analyzed genotype data on 3,206 cases and 7,422 controls. Our analysis provides independent replication of the associations for risk SNPs at 2q14.2 (rs2713206 at P = 3.03 × 10-2; P-meta = 3.92 × 10-8; nearest gene, TFCP2L1) and rs12912292 at 15q21.3 (P = 7.96 × 10-11; P-meta = 1.55 × 10-19; nearest gene PRTG). Case-only analyses did not reveal specific associations with TGCT histology. TFCP2L1 joins the growing list of genes located within TGCT risk loci with biologically plausible roles in developmental transcriptional regulation, further highlighting the importance of this phenomenon in TGCT oncogenesis