Discharge formation in a copper vapor laser: optimal pumping conditions

The electrophysical process in the discharge circuit of a copper vapor laser (CVL) is investigated. It is shown that the pumping of the active medium of a CVL in gas-discharge tubes (GDT) with electrodes located in cold buffer zones is carried out in two stages. At the first (preparatory) stage, the capacitive components of the laser discharge circuit are charged from the storage capacitor, and at the second stage, the active medium is directly pumped. The transition from the preparatory stage to the pumping stage is carried out as a result of a breakdown. It is shown that breakdown is a transient process of discharge development from a glowing to a non-thermal arc discharge and is characterized by a sharp change in the cathode potential drop across the GDT. The inductance of the discharge circuit is a factor that determines the efficiency of pumping the active medium since the release of the energy stored in the inductance at the preparatory stage provides heating of the cathode spot and determines the conditions for the occurrence of thermal emission of electrons from the GDT cathode

Optimal pumping parameters of a copper vapor laser under breakdown conditions

The active medium of pulsed-periodic copper vapor lasers (CVL) is characterized by a high prepulse electron concentration ne0 1013 cm–3. Therefore, it was assumed that the development of the discharge under these conditions is carried out without the breakdown stage. However, as studies have shown, the development of a discharge in gas discharge tubes (GDT) with electrodes located in cold buffer zones (CBZ) is carried out with a breakdown stage

Multispectral anti-reflection coatings based on YbF3/ZnS materials on ZnGeP2 substrate by the IBS method for Mid-IR laser applications

A multispectral anti-reflective coating of high radiation strength for laser applications in the IR spectrum for nonlinear ZnGeP2 crystals has been developed for the first time. The coating was constructed using YbF3/ZnS. The developed coating was obtained by a novel approach using ion-beam deposition of these materials on a ZnGeP2 substrate. It has a high LIDT of more than 2 J/cm2. Optimal layer deposition regimes were found for high film density and low absorption, and good adhesion of the coating to the substrate was achieved. At the same time, there was no dissociation of the double compound under high-energy ions

Optical AR coatings of the Mid-IR band for ZnGeP2 single crystals based on ZnS and oxide aluminum

In this work, the parameters of antireflection interference coatings based on alternating layers of ZnS/Al2O3 on the laser-induced damage threshold (LIDT) of ZGP crystals under the action of Ho:YAG laser radiation at a wavelength of 2.097 μm were determined. The coating deposition was carried out using the ion-beam sputtering method. The LIDT of the sample with a coating based on alternating layers ZnS and Al2O3 was equal to WEo = 3.45 J/cm2, and the LIDT of the uncoated sample was equal to WEo = 2.23 J/cm2. An increase in the optical breakdown threshold by ~55% was observed after the deposition of an AR coating based on ZnS and Al2O3 materials. An assumption was made about the absence of local fluctuations in the composition and mechanical stresses in the case of the coated sample, namely that this leads to good adhesion of the multilayer coating to the polished surface of the crystal, and as a result to an increase in the optical breakdown threshold as compared to the uncoated sample due to closure of the dangling chemical bonds and bulk defects emerging on the polished surface

Are mild cleansers appropriate for hand hygiene in the COVID era? An in vitro investigation of the antiviral efficacy of different hand hygiene products

Background: Washing hands with soap and lukewarm water for 20 s is a fundamental measure advocated especially within the UK to help control the spread of viral disease. However, these practices can induce irritant contact dermatitis, particularly in healthcare professionals (HCPs). HCPs typically manage their condition by replacing soap or alcohol-based hand sanitizers with cleansers containing mild surfactants and/or emollient ingredients [skin-friendly cleansers (SFCs)] to mitigate skin damage and/or using topical emollients after washing for repair. Despite this widespread practice, there is very limited evidence supporting the efficacy of these interventions in the prevention of viral propagation. Methodology: Within this study a range of viruses comprising human coronavirus (HCoV), herpes simplex virus (HSV)-1, influenza (IVA), adenovirus (Ad), and murine norovirus (MNV) were tested against multiple hand wash products, including SFCs. In vitro analysis using plaque assays and tissue culture infectious dose 50 (TCID50) were used to assess virus infectability after incubation with the test products (soaps and SFCs) over a range of concentrations and time points. Transmission electron microscopy (TEM) was used to determine virus architecture and size, while viral replication genes were measured by reverse transcription-polymerase chain reaction (RT-PCR). Results/conclusions: Enveloped viruses demonstrated greater susceptibility over a range of test products, suggesting some SFCs are a suitable alternative to soap (depending on the presence of a viral envelope). However, no virucidal activity was observed for non-enveloped viruses. Water type (i.e., soft/hard) and pre-exposed hand hygiene conditions (i.e., clean/dirty) made little difference to the effectiveness of both soaps and SFCs. Therefore, new hand hygiene regimens should be implemented based on trying to encompass all viruses with varying structures, with specific emphasis on the absence of a viral envelope

Effect of dopants on laser-induced damage threshold of ZnGeP2

The effect of doping Mg, Se, and Ca by diffusion into ZnGeP2 on the optical damage threshold at a wavelength of 2.1 μm has been studied. It has been shown that diffusion-doping with Mg and Se leads to an increase in the laser-induced damage threshold (LIDT) of a single crystal (monocrystal), ZnGeP2; upon annealing at a temperature of 750 °C, the damage threshold of samples doped with Mg and Se increases by 31% and 21% from 2.2 ± 0.1 J/cm2 to 2.9 ± 0.1 and 2.7 ± 0.1 J/cm2, respectively. When ZnGeP2 is doped with Ca, the opposite trend is observed. It has been suggested that the changes in the LIDT depending on the introduced impurity by diffusion can be explained by the creation of additional energy dissipation channels due to the processes of radiative and fast non-radiative relaxation through impurity energy levels, which further requires experimental confirmation

Evaluation of Measurement Properties and Differential Item Functioning in the English and French Versions of the University of California, Los Angeles, Loneliness Scale-6: A Scleroderma Patient-Centered Intervention Network (SPIN) Study

Objective: Loneliness has been associated with poorer health-related quality of life but has not been studied in patients with systemic sclerosis (SSc). The current study was undertaken to examine and compare the psychometric properties of the English and French versions of the University of California, Los Angeles, Loneliness Scale-6 (ULS-6) in patients with SSc during the COVID-19 pandemic. Methods: This study used baseline cross-sectional data from 775 adults enrolled in the Scleroderma Patient-Centered Intervention Network (SPIN) COVID-19 Cohort. Reliability and validity of ULS-6 scores overall and between languages were evaluated using confirmatory factor analysis (CFA), differential item functioning (DIF) through the multiple-indicator multiple-cause (MIMIC) model, omega/alpha calculation, and correlations of hypothesized convergent relationships. Results: CFA for the total sample supported the single-factor structure (comparative fit index [CFI] 0.96, standardized root mean residual [SRMR] 0.03), and all standardized factor loadings for items were large (0.60–0.86). The overall MIMIC model with language as a covariate fit well (CFI 0.94, SRMR 0.04, root mean square error of approximation 0.11). Statistically significant DIF was found for 3 items across language (βitem2 = 0.14, P < 0.001; βitem4 = –0.07, P = 0.01; βitem6 = 0.13, P < 0.001), but these small differences were without practical measurement implications. Analyses demonstrated high internal consistency with no language-based convergent validity differences. Conclusion: Analyses demonstrated evidence of acceptable reliability and validity of ULS-6 scores in English- and French-speaking adults with SSc. DIF analysis supported use of the ULS-6 to examine comparative experiences of loneliness without adjusting for language

Pain levels and associated factors in the Scleroderma Patient-centered Intervention Network (SPIN) cohort: a multicentre cross-sectional study

Background: Pain is an important and detrimental feature of systemic sclerosis but is often overlooked or deprioritised in research and clinical care. Raynaud's phenomenon, arthritis, and cutaneous ulcers are among the commonly reported disease manifestations of systemic sclerosis that could be associated with pain. We aimed to assess levels of pain intensity and interference and to evaluate disease factors associated with pain intensity and interference. Methods: In this multicentre cross-sectional study, participants from the Scleroderma Patient-centered Intervention Network cohort who completed pain intensity and interference measures (Patient Reported Outcomes Information System-29 profile, version 2·0) as part of baseline assessments were included. Patients were recruited from 46 centres in Australia, Canada, France, Mexico, Spain, the UK, and the USA between April 15, 2014, and Jan 7, 2020. Eligible patients included those aged 18 years or older who met the criteria for systemic sclerosis devised by the American College of Rheumatology and the European League Against Rheumatism. Associations of pain intensity and pain interference with systemic sclerosis-related variables and overlap syndromes, controlling for sociodemographic variables, were assessed with multiple linear regression. Continuous independent variables were standardised. Findings: Among 2157 participants with systemic sclerosis (268 [12%] males and 1889 [88%] females), 1870 (87%) reported mild, moderate, or severe pain (defined as ≥1 on a 0 to 10 scale), and 815 (38%) reported moderate or severe pain (defined as ≥5). Moreover, 757 (35%) participants reported moderate or severe pain interference. Greater pain intensity was independently associated with female sex (0·58 points [95% CI 0·26–0·90]), non-White race or ethnicity (0·50 points [0·21–0·79]), fewer years in formal education (0·30 points per SD [0·19–0·41]), country (reference: USA; Canada: 0·29 points [0·01–0·57] and UK: 0·58 points [0·21–0·95]), greater body-mass index (0·35 points per SD [0·24–0·45]); joint contractures (0·67 points [0·39–0·94]), digital ulcers (0·33 points [0·10–0·55]), gastrointestinal involvement (0·66 points [0·33–0·98]), skin involvement (measured using modified Rodnan skin score; 0·22 points per SD [0·10–0·35]), rheumatoid arthritis (0·96 points [0·50–1·43]), and Sjögren's syndrome (0·42 points [0·01–0·83]). Pain interference results were similar. Interpretation: Pain is common among people with systemic sclerosis. Controlling for sociodemographic variables, greater pain was associated with multiple systemic sclerosis-related manifestations, including joint contractures, digital ulcers, gastrointestinal involvement, skin involvement, and the presence of overlap syndromes. Health-care providers should work with patients to address pain, including identifying and addressing systemic sclerosis manifestations associated with their pain, and supporting behavioural approaches to minimise impact on function and quality of life. Funding: Canadian Institutes of Health Research, Arthritis Society, The Lady Davis Institute for Medical Research of the Jewish General Hospital, Jewish General Hospital Foundation, McGill University, Scleroderma Society of Ontario, Scleroderma Canada, Sclérodermie Québec, Scleroderma Manitoba, Scleroderma Atlantic, Scleroderma Association of BC, Scleroderma SASK, Scleroderma Australia, Scleroderma New South Wales, Scleroderma Victoria, and Scleroderma Queensland

Randomized controlled trial of an internet-based self-guided hand exercise program to improve hand function in people with systemic sclerosis: the Scleroderma Patient-centered Intervention Network Hand Exercise Program (SPIN-HAND) trial

BACKGROUND: Systemic sclerosis (scleroderma; SSc) is a rare autoimmune connective tissue disease. Functional impairment of hands is common. The Scleroderma Patient-centered Intervention Network (SPIN)-HAND trial compared effects of offering access to an online self-guided hand exercise program to usual care on hand function (primary) and functional health outcomes (secondary) in people with SSc with at least mild hand function limitations. METHODS: The pragmatic, two-arm, parallel-group cohort multiple randomized controlled trial was embedded in the SPIN Cohort. Cohort participants with Cochin Hand Function Scale (CHFS) scores ≥ 3 and who indicated interest in using the SPIN-HAND Program were randomized (3:2 ratio) to an offer of program access or to usual care (targeted N = 586). The SPIN-HAND program consists of 4 modules that address (1) thumb flexibility and strength; (2) finger bending; (3) finger extension; and (4) wrist flexibility and strength. The primary outcome analysis compared CHFS scores 3 months post-randomization between participants offered versus not offered the program. Secondary outcomes were CHFS scores 6 months post-randomization and functional health outcomes (Patient-Reported Outcomes Measurement Information System profile version 2.0 domain scores) 3 and 6 months post-randomization. RESULTS: In total, 466 participants were randomized to intervention offer (N = 280) or usual care (N = 186). Of 280 participants offered the intervention, 170 (61%) consented to access the program. Of these, 117 (69%) viewed at least one hand exercise instruction video and 77 (45%) logged into the program website at least 3 times. In intent-to-treat analyses, CHFS scores were 1.2 points lower (95% CI − 2.8 to 0.3) for intervention compared to usual care 3 months post-randomization and 0.1 points lower (95% CI − 1.8 to 1.6 points) 6 months post-randomization. There were no statistically significant differences in other outcomes. CONCLUSION: The offer to use the SPIN-HAND Program did not improve hand function. Low offer uptake, program access, and minimal usage among those who accessed the program limited our ability to determine if using the program would improve function. To improve engagement, the program could be tested in a group format or as a resource to support care provided by a physical or occupational therapist. TRIAL REGISTRATION: NCT03419208. Registered on February 1, 2018

Patterns of patient-reported symptoms and association with sociodemographic and systemic sclerosis disease characteristics: a scleroderma Patient-centered Intervention Network (SPIN) Cohort cross-sectional study

Background: Systemic sclerosis is a heterogenous disease in which little is known about patterns of patient-reported symptom clusters. We aimed to identify classes of individuals with similar anxiety, depression, fatigue, sleep disturbance, and pain symptoms and to evaluate associated sociodemographic and disease-related characteristics. Methods: This multi-centre cross-sectional study used baseline data from Scleroderma Patient-centered Intervention Network Cohort participants enrolled from 2014 to 2020. Eligible participants completed the PROMIS-29 v2.0 measure. Latent profile analysis was used to identify homogeneous classes of participants based on patterns of anxiety, depression, fatigue, sleep disturbance, and pain scores. Sociodemographic and disease-related characteristics were compared across classes. Findings: Among 2212 participants, we identified five classes, including four classes with “Low” (565 participants, 26%), “Normal” (651 participants, 29%), “High” (569 participants, 26%), or “Very High” (193 participants, 9%) symptom levels across all symptoms. Participants in a fifth class, “High Fatigue/Sleep/Pain and Low Anxiety/Depression” (234 participants, 11%) had similar levels of fatigue, sleep disturbance, and pain as in the “High” class but low anxiety and depression symptoms. There were significant and substantive trends in sociodemographic characteristics (age, education, race or ethnicity, marital or partner status) and increasing disease severity (diffuse disease, tendon friction rubs, joint contractures, gastrointestinal symptoms) across severity-based classes. Disease severity and sociodemographic characteristics of “High Fatigue/Sleep/Pain and Low Anxiety/Depression” class participants were similar to the “High” severity class. Interpretation: Most people with systemic sclerosis can be classified by levels of patient-reported symptoms, which are consistent across symptoms and highly associated with sociodemographic and disease-related variables, except for one group which reports low mental health symptoms despite high levels of other symptoms and substantial disease burden. Studies are needed to better understand resilience in systemic sclerosis and to identify and facilitate implementation of cognitive and behavioural strategies to improve coping and overall quality of life. Funding: National Institute of Nursing Research (F31NR019007), Canadian Institutes of Health Research, Arthritis Society Canada, the Lady Davis Institute for Medical Research, the Jewish General Hospital Foundation, McGill University, Scleroderma Society of Ontario, Scleroderma Canada, Sclérodermie Québec, Scleroderma Manitoba, Scleroderma Atlantic, Scleroderma Association of BC, Scleroderma SASK, Scleroderma Australia, Scleroderma New South Wales, Scleroderma Victoria, and Scleroderma Queensland