SciCombinator

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Concept: Abrasion

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Lacerations, abrasions, burns, and puncture wounds are common in the outpatient setting. Because wounds can quickly become infected, the most important aspect of treating a minor wound is irrigation and cleaning. There is no evidence that antiseptic irrigation is superior to sterile saline or tap water. Occlusion of the wound is key to preventing contamination. Suturing, if required, can be completed up to 24 hours after the trauma occurs, depending on the wound site. Tissue adhesives are equally effective for low-tension wounds with linear edges that can be evenly approximated. Although patients are often instructed to keep their wounds covered and dry after suturing, they can get wet within the first 24 to 48 hours without increasing the risk of infection. There is no evidence that prophylactic antibiotics improve outcomes for most simple wounds. Tetanus toxoid should be administered as soon as possible to patients who have not received a booster in the past 10 years. Superficial mild wound infections can be treated with topical agents, whereas deeper mild and moderate infections should be treated with oral antibiotics. Most severe infections, and moderate infections in high-risk patients, require initial parenteral antibiotics. Severe burns and wounds that cover large areas of the body or involve the face, joints, bone, tendons, or nerves should generally be referred to wound care specialists.

Concepts: Bacteria, Infection, Wound, Antibiotic, Topical, Route of administration, Traumatology, Abrasion

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OBJECTIVE: To determine risk factors associated with infection and traumatic lacerations and to see if a relationship exists between infection and time to wound closure after injury. METHODS: Consecutive patients presenting with traumatic lacerations at three diverse emergency departments were prospectively enrolled and 27 variables were collected at the time of treatment. Patients were followed for 30 days to determine the development of a wound infection and desire for scar revision. RESULTS: 2663 patients completed follow-up and 69 (2.6%, 95% CI 2.0% to 3.3%) developed infection. Infected wounds were more likely to receive a worse cosmetic rating and more likely to be considered for scar revision (RR 2.6, 95% CI 1.7 to 3.9). People with diabetes (RR 2.70, 95% CI 1.1 to 6.5), lower extremity lacerations (RR 4.1, 95% CI 2.5 to 6.8), contaminated lacerations (RR 2.0, 95% CI 1.2  to 3.4) and lacerations greater than 5 cm (RR 2.9, 95% CI 1.6 to 5.2) were more likely to develop an infection. There were no differences in the infection rates for lacerations closed before 3% (95% CI 2.3% to 3.8%) or after 1.2% (95% CI 0.03% to 6.4%) 12 h. CONCLUSIONS: Diabetes, wound contamination, length greater than 5 cm and location on the lower extremity are important risk factors for wound infection. Time from injury to wound closure is not as important as previously thought. Improvements in irrigation and decontamination over the past 30 years may have led to this change in outcome.

Concepts: Myocardial infarction, Wound healing, Infection, Risk, Injury, Wound, Chronic wound, Abrasion

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Wound repair is a key feature distinguishing living from nonliving matter. Single cells are increasingly recognized to be capable of healing wounds. The lack of reproducible, high-throughput wounding methods has hindered single-cell wound repair studies. This work describes a microfluidic guillotine for bisecting single Stentor coeruleus cells in a continuous-flow manner. Stentor is used as a model due to its robust repair capacity and the ability to perform gene knockdown in a high-throughput manner. Local cutting dynamics reveals two regimes under which cells are bisected, one at low viscous stress where cells are cut with small membrane ruptures and high viability and one at high viscous stress where cells are cut with extended membrane ruptures and decreased viability. A cutting throughput up to 64 cells per minute-more than 200 times faster than current methods-is achieved. The method allows the generation of more than 100 cells in a synchronized stage of their repair process. This capacity, combined with high-throughput gene knockdown in Stentor, enables time-course mechanistic studies impossible with current wounding methods.

Concepts: Wound healing, Wound, First aid, Traumatology, Chronic wound, Abrasion

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Over the last century, humans from industrialized societies have witnessed a radical increase in some dental diseases. A severe problem concerns the loss of dental materials (enamel and dentine) at the buccal cervical region of the tooth. This “modern-day” pathology, called non-carious cervical lesions (NCCLs), is ubiquitous and worldwide spread, but is very sporadic in modern humans from pre-industrialized societies. Scholars believe that several factors are involved, but the real dynamics behind this pathology are far from being understood. Here we use an engineering approach, finite element analysis (FEA), to suggest that the lack of dental wear, characteristic of industrialized societies, might be a major factor leading to NCCLs. Occlusal loads were applied to high resolution finite element models of lower second premolars (P2) to demonstrate that slightly worn P2s envisage high tensile stresses in the buccal cervical region, but when worn down artificially in the laboratory the pattern of stress distribution changes and the tensile stresses decrease, matching the results obtained in naturally worn P2s. In the modern industrialized world, individuals at advanced ages show very moderate dental wear when compared to past societies, and teeth are exposed to high tensile stresses at the buccal cervical region for decades longer. This is the most likely mechanism explaining enamel loss in the cervical region, and may favor the activity of other disruptive processes such as biocorrosion. Because of the lack of dental abrasion, our masticatory apparatus faces new challenges that can only be understood in an evolutionary perspective.

Concepts: Science, Finite element method, Teeth, Tooth enamel, Computational fluid dynamics, Finite element method in structural mechanics, Abrasion, Wear

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Assessing the impact of glaciation on Earth’s surface requires understanding glacial erosion processes. Developing erosion theories is challenging because of the complex nature of the erosion processes and the difficulty of examining the ice/bedrock interface of contemporary glaciers. We demonstrate that the glacial erosion rate is proportional to the ice-sliding velocity squared, by quantifying spatial variations in ice-sliding velocity and the erosion rate of a fast-flowing Alpine glacier. The nonlinear behavior implies a high erosion sensitivity to small variations in topographic slope and precipitation. A nonlinear rate law suggests that abrasion may dominate over other erosion processes in fast-flowing glaciers. It may also explain the wide range of observed glacial erosion rates and, in part, the impact of glaciation on mountainous landscapes during the past few million years.

Concepts: Water, Earth, Glacier, Erosion, Antarctica, Abrasion, Glaciology, Glacial erratic

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To determine if the number of emergency department (ED) rechecks, persistent fluorescein uptake, ophthalmology referrals, or complications would be affected by the prescription of topical tetracaine for pain relief from simple corneal abrasions (SCAs).

Concepts: Hospital, Observational study, Ophthalmology, Fluorescein, Corneal ulcer, Dublin, Abrasion, Corneal abrasion

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A fretting wear experiment with uranium has been performed on a linear reciprocating tribometer with ball-on-disk contact. This study focused on the fretting behavior of the uranium under different atmospheres (Ar, Air (21% O₂ + 78% N₂), and O₂) and vacuum conditions (1.05 and 1 × 10−4 Pa). Evolution of friction was assessed by coefficient of friction (COF) and friction-dissipated energy. The oxide of the wear surface was evaluated by Raman spectroscopy. The result shows that fretting wear behavior presents strong atmosphere and vacuum condition dependence. With increasing oxygen content, the COF decreases due to abrasive wear and formation of oxide film. The COF in the oxygen condition is at least 0.335, and it has a maximum wear volume of about 1.48 × 10⁷ μm³. However, the COF in a high vacuum condition is maximum about 1.104, and the wear volume is 1.64 × 10⁶ μm³. The COF in the low vacuum condition is very different: it firstly increased and then decreased rapidly to a steady value. It is caused by slight abrasive wear and the formation of tribofilm after thousands of cycles.

Concepts: Oxide, Pressure, Atmosphere, Pascal, Friction, Tribology, Abrasion, Wear

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Cistanche deserticola Y. C. Ma, a precious parasitic medicinal herb distributed in desert areas in the Northwest of China, also known as “desert ginseng”, has been used in China for thousands of years for its nourishing effects. The phenylethanoid glycosides (PeGs) have been proven as the main effective compounds due to their neuroprotective effects and were used for quality control. In this study, echinacoside content, a representative PeG, total phenolic content, DPPH scavenging activity, and PAL activity were determined in different tissues of C. deserticola. Our results showed that most indices had a similar pattern of scale > cambium ring > pith and bottom part > middle part > upper part. Besides, stereomicroscopic observation showed that the scale surface was densely covered with physical wounds formed during vertical and broadwise growth in sand. Thus, wound area was quantified and a linear regression analysis was conducted between wound area and PAL activity, total phenolics, and echinacoside content. Our results suggested that physical wounding caused by sand might play an important role in echinacoside biosynthesis which has never been noticed in C. deserticola development. Furthermore, the coexistence of the highest PAL activity and highest echinacoside accumulation in scale tissue might indicate that the biosynthetic site of echinacoside in C. deseticola Y. C. Ma is mainly in the scale tissue.

Concepts: Regression analysis, Linear regression, Wound healing, Wound, Abrasion, Cistanche deserticola

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The aim of this review was to compile recent evidence related to nanofilled resin composite materials regarding the properties and clinical performance. Special attention was given to mechanical properties, such as strength, hardness, abrasive wear, water sorption, and solubility. The clinical performance of nanocomposite materials compared with hybrid resin composites was also addressed in terms of retention and success rates, marginal adaptation, color match, and surface roughness. A search of English peer-reviewed dental literature (2003-2017) from PubMed and MEDLINE databases was conducted using the terms “nanocomposites” or “nanofilled resin composite” and “clinical evaluation.” The list was screened, and 82 papers that were relevant to the objectives of this work were included in the review. Mechanical properties of nanocomposites are generally comparable to those of hybrid composites but higher than microfilled composites. Nanocomposites presented lower abrasive wear than hybrids but higher sorption values. Their clinical performance was comparable to that of hybrid composites.

Concepts: Materials science, Composite material, Boeing 787, Abrasion, Dental composite, Nanocomposite, Composite materials, Pykrete

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The aim was to investigate the effect of machining instruments on machinability of dental ceramics. Four dental ceramics, including two zirconia ceramics were machined by three types (SiC, diamond vitrified, and diamond sintered) of wheels with a hand-piece engine and two types (diamond and carbide) of burs with a high-speed air turbine. The machining conditions used were abrading speeds of 10,000 and 15,000 r.p.m. with abrading force of 100 gf for the hand-piece engine, and a pressure of 200 kPa and a cutting force of 80 gf for the air-turbine hand-piece. The machinability efficiency was evaluated by volume losses after machining the ceramics. A high-abrading speed had high-abrading efficiency (high-volume loss) compared to low-abrading speed in all abrading instruments used. The diamond vitrified wheels demonstrated higher volume loss for two zirconia ceramics than those of SiC and diamond sintered wheels. When the high-speed air-turbine instruments were used, the diamond points showed higher volume losses compared to the carbide burs for one ceramic and two zirconia ceramics with high-mechanical properties. The results of this study indicated that the machinability of dental ceramics depends on the mechanical and physical properties of dental ceramics and machining instruments. The abrading wheels show autogenous action of abrasive grains, in which ground abrasive grains drop out from the binder during abrasion, then the binder follow to wear out, subsequently new abrasive grains come out onto the instrument surface (autogenous action) and increase the grinding amount (volume loss) of grinding materials.

Concepts: Carbon, Silicon carbide, Ceramic materials, Ceramic, Sintering, Abrasion, Machining, Abrasive