When is a background equivalent? Sparse chromatic context revisited

In a nation-wide survey among Danish doctors, the compliance and reasons for non-compliance with universal precautions (UP) and the associated circumstances of mucocutaneous blood exposure (MCE) were studied. Of 9384 questionnaires, 6256 (67%) were returned and 6005 were eligible for analysis. Only 35% complied with the basic principles of UP. Compliance with protective barrier use in surgical versus non-surgical specialties was: Gloves 63.0% and 23.4%, masks 55.2% and 17.6% and protective eyewear 11.5% and 4.0% respectively. Common given reasons for non-compliance were: "Interferes with working skills", "forget", "wear spectacles", "not available", "too much trouble to get" or "gloves do not fit". Of 741 MCE described in detail, an estimated 84-98% were potentially preventable if appropriate barriers had been worn. More than half of MCE were preventable by two interventions only: Compulsory use of protective eyewear during operations and of gloves during insertion of peripheral i.v.-catheters. In conclusion compliance with UP is unacceptably low and the majority of MCE were potentially preventable if appropriate barriers had been worn.     

Classification of laser irradiation and safety measures

The use of lasers in medicine and especially surgery is rapidly expanding in many disciplines from clinical laboratory to the office practice and operating room. It is essential that users of this powerful tool have knowledge of their potential hazards and the measures to protect patients and personnel against injuries or undesired effects. Below, we have included information about the way lasers are classified; the development of protective standards; the current status of protection standards that apply to lasers, especially those used in medicine/surgery; the specific kinds of hazards associated with medical/surgical applications; and the measures by which hazards have been controlled. Since laser technology is still a young field, it is likely that problems unknown at present will occur and methodologies for controlling hazards will evolve. The American National Standards Committee produced the first consensus standard Z136.1 in 1973. The Standard was revised in 1976 to accommodate differences in biological effects for different wavelengths in the visible spectrum. The ANSI Standard has been revised again in 1980, and currently (1984) there are two additional standards in preparation, Z136.2 and 136.3, which treat the safe use of light-emitting diodes and the safe use of lasers in the health care environment, respectively. Most surgical and medical lasers are Class III or IV. Some lasers have a Class IV therapy level beam plus a Class I or II alignment beam. When using lasers, it is possible to generate incandescence or fluorescence in an irradiated object. This can occur even with protective eyewear, because the correlated radiations are usually of a different wavelength. Generally, this should not be a problem when beams are directed at biological material. However, hazard could be caused by lasers designed to produce fluorescence. Control of correlative radiation in a laser system is required in the federal regulations. Hazards of lasers may be grouped as those to the eye, skin and associated hazards, fire, x-rays, electrical, fumes, toxic materials, etc. Effects on tissue are governed by the following factors:--the energy or power density of the beam;--the absorption in tissue at the laser wavelength;--the time the beam is held at a given area.;--the protective effects of heat removal by thermal conduction and by circulation. Eye hazards include thermal burns or acoustical disruption (shock waves) from high-powered or high-energy beams in the visible and near infrared wavelengths. Direct beam exposure or specular or diffuse reflaction from these very high-power lasers can also cause injuries to other parts of the retina. For example, beams can directly penetrate through the sclera and cause retinal injury. Near ultraviolet (less than 400 hm) and far infrared (.3000 hm including CO2 lasers) can cause moderate to severe corneal burns. Far ultraviolet (200-315 nm), mid infrared (1400-3000 nanometers) can cause welders' flash or snow blindness and chronic exposure could cause cataract, and exposure to ultraviolet rays may be carcinogenic. For CO2 lasers, the far infrared radiation is attenuated by plastic goggles, or by glasses, or quartz. Other eyewear with special filters is used for different lasers. The whole personnel who may be exposed to direct beams, specular reflections, and many times diffuse reflections must wear protective eyewear. In all cases the surgeon and others viewing the procedure through the endoscope need glasses or suitable protective lenses installed in the endoscope. Persons who are not viewing the beam may not need to wear protective glasses with the same level of optical density. Glasses may be selected to provide protection for lasers operating in the visible wavelength to the point where the normal aversion response could protect the individual.     

Late clear corneal wound failure after trivial trauma

A clear corneal cataract wound ruptured after trivial trauma. The wound did not meet the criteria for wound stability as previously recommended. This case illustrates the potential public health hazard with the increasing use of clear corneal cataract surgery. Proper wound design can eliminate this risk. Patients without proper wound design should be cautioned to wear protective eyewear to avoid serious or blinding trauma.     

Syphilis and gonorrhea

Syphilis and gonorrhea are prevalent in the United States; thus it is likely that the practicing dentist will encounter these sexually transmitted diseases. Oral-genital contact can result in oral and oropharyngeal lesions of both syphilis and gonorrhea. In most states, the law mandates reporting of these sexually transmitted diseases to local health departments. Dentists must wear gloves, masks, and protective eyewear for all procedures resulting in physical contact between the patient and practitioner. Universal infection control procedures must be carefully followed to ensure against disease transmission from the symptomatic as well as the asymptomatic disease carrier.     

Formation of a chromophoric complex between alendronate and copper(II) ions

Sports-related eye injuries are quite common, yet the number of athletes who utilize protective eyewear is extremely low. The purpose of this study was to determine if there is a significant visual field loss associated with wearing eye protection. One of the authors was subjected to standard kinetic visual field testing with and without eye goggles. No significant difference was revealed. Physicians, physical therapists, and trainers should promote the use of protective eyewear and reassure athletes that they will not lose visual field.     

选择性激光熔化成形CoCrWMo合金工艺优化及摩擦磨损性能

对选择性激光熔化成形CoCrWMo合金的工艺参数进行优化,并对最佳工艺下合金试样的摩擦磨损性能进行分析。结果表明:选择性激光熔化最佳工艺参数为激光功率280 W,扫描速度800 mm?s?1,铺粉层厚0.03 mm,扫描间距0.10 mm,扫描策略为旋转扫描法（层与层之间旋转15°）。该工艺下激光体能量密度为117 J?mm?3,试样相对密度为99.4%,上表面粗糙度（Ra）为4.98 μm,显微硬度为HV 386,抗拉强度为984 MPa,屈服强度为663 MPa,断后伸长率为12.9%。在干摩擦下,CoCrWMo合金的平均摩擦系数随施加载荷的增加呈下降趋势;受磨损过程中应变诱导马氏体转变的影响,合金平均磨损率呈现先增高后降低的变化规律,主要磨损机制为磨粒磨损和粘着磨损。     

Air bag-related corneal rupture after radial keratotomy

PURPOSE: We studied a case of air bag-associated corneal rupture in a patient who had previously undergone radial keratotomy surgery. METHODS: The patient was struck in the right eye when his driver's side air bag inflated during a low-speed collision. RESULTS: Inflation of the air bag resulted in rupture of the patient's right cornea. The rupture involved all but one of his old radial keratotomy wounds. CONCLUSIONS: Patients who have undergone radial keratotomy may be at increased risk for corneal rupture caused by air bag trauma. These patients may benefit by wearing protective eyewear while driving cars equipped with air bags.     

Comparison of the microstructures and abrasive wear properties of stellite hardfacing alloys deposited by arc welding and laser cladding

The microstructure of cobalt-based hardfacing alloys deposited by manual metal arc (MMA) welding, tungsten inert gas (TIG) welding, and laser cladding has been investigated as part of a study attempting to establish the relationship between microstructure and abrasive wear properties. For typical deposition conditions, the differences in freezing rates associated with the three processes are found to give rise to large differences in microstructure. The MMA process is found to lead to the largest degree of dilution of the hardfacing deposit; the TIG and laser deposits exhibited much lower levels of mixing with the base plate. For the deposition conditions used in this study and for the alloys examined, the scale of the microstructure decreases in the order MMA, TIG, and laser cladding, leading to an increase in the deposit hardness in the same order. It is found that with alumina as an abrasive, the wear rate persistently is higher with the MMA deposits (which have the coarsest microstructure with the lowest starting hardness), the weight loss being approximately linear with time. The laser and TIG deposits, which have more refined microstructures and slightly higher carbon concentrations, both are found to exhibit significantly lower wear rates. Initially, the TIG samples are the most resistant to abrasion, even though their microstructure compares with that of the laser samples; this is a consequence of their higher ductility associated with a lower rate of strain hardening. The laser samples, which contain a lower matrix iron concentration, strain harden more rapidly; consequently, they exhibit an initial decrease in wear rate. With the much harder silicon carbide abrasive, all samples show similar wear rates which do not decrease with time. The wear data are found to correlate with scanning and transmission electron microscopy observations, and it is possible to rationalize the interaction among microstructure, abrasive, and alloy deposition processes.     

No passport is required to incorporate cultural appreciation into perioperative nursing practice

As you read this issue of the Journal and celebrate OR Nurse Week, think about your daily opportunities to practice the principles of international nursing. Look for chances to appreciate cultural values different from your own as you provide patient care and interact with visiting international colleagues. Adopt a global perspective to perioperative nursing.     

Microstructure and Wear Resistance of Laser Clad Cobalt-Based Alloy／SiCp Composite Coating

The SiCp (20%) reinforced cobalt-based alloy composite coatings deposited by lasercladding on IF steel were introduced. The microstructure across the whole section of such coat-ings was examined using optical microscope, scanning electron microscope (SEM) and X-raydiffractometer (XRD), and the wear resistance of the coatings was measured by MM-200 typewear testing machine. The results show that the SiCp is completely dissolved during laser clad-ding and the primary phase in the coatings is r-Co. The other phases, such as SizW, CoWSi,Cr3Si and CoSi2, are formed by carbon, silicon reacting with other elements existing in themelting pool. There are various crystallization morphologies in different zones, such as planarcrystallization at the interface, followed by cellular and dendrite crystallization from interface tothe surface. The direction of solidification changes from one direction perpendicular to interfaceto multi-directions at the central and upper regions of the clad. The wear resistance of the cladis improved by adding SiCp.     

Microstructure and wear properties of laser clad Fe−Cr−Mn−C alloys

The laser surface cladding technique was used to formin situ Fe-Cr-Mn-C alloys on AISI 1016 steel substrate. In this process mixed powders containing Cr, Mn, and C with a ratio of 10∶1∶1 were delivered using a screw feed, gravity flow carrier gas aided system into the melt pool generated by a 10 kw CO₂ laser. This technique produced ultrafine microstructure in the clad alloy. The microstructure of the laser surface clad region was investigated by optical, scanning, and transmission electron microscopy and X-ray microanalysis techniques. Microstructural study showed a high degree of grain refinement and an increase in solid solubility of alloying elements which, in turn, produced a fine distribution of complex types of carbide precipitates in the ferrite matrix because of the high cooling rate. An alloy of this composition does not show any martensitic or retained austenite phase. In preliminary wear studies the laser clad Fe-Cr-Mn-C alloys exhibited far superior wear properties compared to Stellite 6 during block-on-cylinder tests. The improved wear resistance is attributed to the fine distribution of metastable M₆C carbides.     

Microstructure and wear properties

The laser surface cladding technique was used to formin situ Fe-Cr-Mn-C alloys on AISI 1016 steel substrate. In this process mixed powders containing Cr, Mn, and C with a ratio of 10:1:1 were delivered using a screw feed, gravity flow carrier gas aided system into the melt pool generated by a 10 kw CO₂ laser. This technique produced ultrafine microstructure in the clad alloy. The microstructure of the laser surface clad region was investigated by optical, scanning, and transmission electron microscopy and X-ray microanalysis techniques. Microstructural study showed a high degree of grain refinement and an increase in solid solubility of alloying elements which, in turn, produced a fine distribution of complex types of carbide precipitates in the ferrite matrix because of the high cooling rate. An alloy of this composition does not show any martensitic or retained austenite phase. In preliminary wear studies the laser clad Fe-Cr-Mn-C alloys exhibited far superior wear properties compared to Stellite 6 during block-on-cylinder tests. The improved wear resistance is attributed to the fine distribution of metastable M₆C carbides.     

Effects of Aluminization Via Thermo-Chemical Diffusion on the Wear Behavior of Structural Materials for High-Temperature Gas-Cooled Reactors

We explore the effects of thermo-chemical aluminization on wear resistance of candidate alloys Incoloy 800HT and Inconel 617 for high-temperature gas-cooled reactor (HTGR) components. Aluminized samples were conditioned for 22 days in a once-through helium loop to simulate oxidizing conditions of HTGRs. The tribological performance of unconditioned and conditioned samples was tested using pin-on-disk tribometer in an air environment at 750 °C for 800HT and 900 °C for 617. Aluminized 800HT exhibited superior wear resistance compared to that of the as-received 800HT due to harder Fe-Al intermetallic compounds that formed at the surface of the alloy. Aluminized 617 exhibited wear resistance superior to that of the as-received 617 at higher loads but inferior resistance at lower loads. Conditioned 800HT as well as aluminized and then conditioned 800HT exhibited negligible wear when the protective oxide remained intact during tribotesting. When the oxide wore through, aluminized and then conditioned 800HT exhibited superior wear resistance compared to that of conditioned 800HT due to the increased hardness of intermetallic zones. Aluminized and then conditioned 617 exhibited inferior wear resistance compared to that of conditioned 617 due to significant ceramic wear of the aluminum oxide. Connections between surface hardness, chemical composition, initial friction coefficients, and wear resistance are established.

     

Effect of artificial tribological layer on sliding wear behavior of H13 steel

An artificial tribological layer was formed on the worn surface during sliding, through supplying MoS2 , Fe2 O 3 or their equiponderant mixtures onto the sliding interface of H13/GCr15 steels.The effect of this tribological layer on the wear behavior of H13 steel was studied.The worn surfaces and subsurfaces of H13 steel were thoroughly characterized by using X-ray diffraction (XRD), scanning electron microscopy (SEM) and energy dispersive spectrometry (EDS); the wear mechanisms were explored.The research results demonstrated that tribological layer did not exist during sliding of H13 steel with no additive, but it formed with the addition of MoS2 , Fe2 O 3 or their equiponderant mix-tures.When there was no tribological layer, the wear rate rapidly increased with an increase of the load.In this case, adhesive and abrasive wear prevailed.As the additives were supplied, the artificial tribological layer was observed to be immediately formed and stably existed on worn surfaces.This tribological layer presented an obvious protective function from wear and friction.Hence, the wear rate and friction coefficient were significantly decreased.MoS2 as tribological layer seemed to present more obvious protective function than Fe2 O 3 .By supplying their mixture, the artificial tribological layer possessed not only the load-carrying capacity of Fe2 O 3 , but also the lubricative capacity of MoS2 .These two simultaneous capacities could improve the friction and wear properties of H13 steel further.     

激光表面淬火后铁基烧结凸轮的组织与性能研究

本论文研究了铁基烧结凸轮材料经宽带激光表面淬火前后的显微组织、硬度及其摩擦学特性。研究结果表明：经激光表面淬火后，铁基烧结凸轮材料的耐磨性得到了显著的改善，摩擦系数也明显降低。在摩擦过程中，摩擦表而形成一具有高硬度的表面层，在摩擦表而层的最表层还覆盖着一层表面膜。该表面膜的存在可进一步改善铁基烧结凸轮材料的耐磨性。     

Effect of Various Nanoparticles on Tribo-Layers and Wear Behavior of TC11 Alloy

Multilayer graphene (MLG), Fe₂O₃, and their nanocomposites with various proportions and amounts were applied as additives and directly participated in the formation of tribo-layers during sliding wear of TC11 alloy against AISI 52100 steel. Their ingredients and amounts were found to exert substantial effects on the additive-containing tribo-layers and wear behavior. Irrespective of the added amount of MLG or Fe₂O₃, the formed tribo-layers, because of the lack of load-bearing or lubricant capacity, readily lost stability and protection function, causing a high wear rate. However, a small quantity of MLG/Fe₂O₃ nanocomposites could result in a remarkable decrease in the wear rate. This was attributed to the stable existence and continuous protection of a friction-reduced and wear-resistant double-layer tribo-layer. In particular, Fe₂O₃-rich nanocomposite additives produced more protective tribo-layers to markedly improve the wear resistance of TC11 alloy.     

Pathogen-specific risk factors and protective factors for acute diarrheal disease in urban Brazilian infants

To evaluate potential risk factors and protective factors for acute diarrheal disease in urban infants, 500 infants < or = 12 months old with diarrhea and 500 age-matched control subjects coming to a S?o Paulo emergency room were studied. On multivariate analysis, these apparently sporadic community-acquired cases of diarrhea were significantly associated with hospitalization in the month before onset (odds ratio [OR], 3.4), day care center exposure (OR, 2.0), prior diarrhea in another household member (OR, 4.4), and low family income (OR, 1.8). Breast-feeding infants < 6 months old (OR, 0.3) and boiling household drinking water (OR, 0.4) were protective. Enteropathogenic Escherichia coli (EPEC; OR, 12.0) and Salmonella (OR, 7/0, discordant pairs) infections were associated with prior hospitalization, rotavirus infections were associated with day care (OR, 6/0), and breast-feeding was protective against EPEC infections (OR, 0.1). These results suggest that certain preventive strategies can prevent a substantial proportion of cases of diarrheal disease in Brazilian infants.     

Preventing vicarious traumatization of mental health therapists: Identifying protective practices.

This qualitative study identified protective practices that mitigate risks of vicarious traumatization (VT) among mental health therapists. The sample included six peer-nominated master therapists, who responded to the question, “How do you manage to sustain your personal and professional well-being, given the challenges of your work with seriously traumatized clients?” Data analysis was based upon Lieblich, Tuval-Mashiach, and Zilber’s (1998) typology of narrative analysis. Findings included nine major themes salient across clinicians’ narratives of protective practices: countering isolation (in professional, personal and spiritual realms); developing mindful self-awareness; consciously expanding perspective to embrace complexity; active optimism; holistic self-care; maintaining clear boundaries; exquisite empathy; professional satisfaction; and creating meaning. Findings confirm and extend previous recommendations for ameliorating VT and underscore the ethical responsibility shared by employers, educators, professional bodies, and individual practitioners to address this serious problem. The novel finding that empathic engagement with traumatized clients appeared to be protective challenges previous conceptualizations of VT and points to exciting new directions for research, theory, training, and practice. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Abrasive Wear Behavior and Mechanism of High Chromium Cast Iron

The abrasive wear behavior of high chromium cast iron(containing 12.9mass%chromium)austenitized at1 050 ℃for 2hand austempered in salt bath at 320℃for 4hwas evaluated.Abrasive wear was performed using alumina abrasive under four different loads,namely 50,100,150,and 200 N,for 36 000 cycles.The worn surfaces and wear debris were analyzed by scanning electron microscopy,laser confocal microscopy and X-ray diffraction.Microhardness profiles were also obtained in order to analyze the strain-hardening effects beneath the contact surfaces.Results indicate that the retained austenite in high chromium cast iron has experienced induced martensitic transformation after tests,for small amounts of retained austenite could be detected by X-ray diffraction.In addition,there is a close relationship between wear mechanism and test load.Under the condition of lower test load,the wear mechanism is an uninterrupted and repeated process,during which matrix is cut at first and then fine carbides flake off.As to higher test load,scratching and spalling induced by cleavage fracture of blocky carbide are the wear mechanism.     

Current status of neonatal screening for congenital adrenal hyperplasia

Randomized trials are the optimal approach for evaluations of treatment efficacy but may not always be feasible. We study the adequacy of the case-control design in evaluating efficacy in a situation where the investigated therapy, namely the administration of magnesium sulfate for the prevention of eclampsia in patients with preeclampsia, has a suspected strong protective effect. A total of 66 cases of eclampsia were ascertained from among deliveries occurring between 1977 and 1992 at two hospitals in Houston, Texas. Randomly selected preeclamptic controls were matched to cases based on hospital and month of delivery. Magnesium sulfate administration prior to seizure occurrence had a strong protective effect against eclampsia in patients with preeclampsia (OR, 0.02; 95% CI, 0.01-0.05). This protective effect remained when controls were stratified by the degree of severity of preeclampsia (mild-to-moderate OR, 0.03, 95% CI, 0.01-0.09 and severe OR, 0.005; 95% CI, 0.0005-0.04) and when cases were stratified by the timing of the first seizure (antepartum and intrapartum seizures OR, 0.01; 95% CI, 0.003-0.05 and postpartum seizures OR, 0.03; 95% CI, 0.005-0.15). The effect also remained after adjustment for other important predictors in a multivariate logistic regression model (OR, 0.11; 95% CI, 0.03-0.38). The results of this study are in support of a recent randomized trial on the efficacy of magnesium sulfate as a prophylactic agent against eclampsia. Although there are serious potential sources of bias in this study, the magnitude of the protective effect of magnesium sulfate minimizes the likelihood that this effect can be explained by bias. Observational studies could be appropriate complements or alternatives to randomized trials in situations where a strong treatment effect is expected.