Analysis of the effect of spray mode on coating porosity and hardness when spraying press screws by the high velocity oxy fuel method

Porosity and coating hardness are two very important properties of the coating. In order to achieve low coating porosity and high hardness, a suitable spray mode is desired. In the particular application for press screws with the complex surface, a suitable spray mode plays a significant role in the formation of the coating properties. This paper employs the Taguchi experimental design method combined with ANOVA analysis to evaluate the impact of the spray mode on the porosity and hardness of the coating while spraying the screw surface using the High Velocity Oxy Fuel (HVOF) method. The injection material used is WC HMSP1060-00 +60 % 4070, with its main components being Nickel and Carbide Wolfram. And the press screw material is 1045 steel. The impactful parameters of the spray mode investigated and tested are the flow rate of spray (F) with a range varying from 25 g/min to 35 g/min, spray distance (D) with a range of values varying from 0.25 m to 0.35 m, and an oxygen/propane ratio (R) from 4 to 6. The analysis shows that the spray mode significantly affects the coating properties, and a suitable set of spray parameters is found to achieve low coating porosity and high coating hardness. The spray mode with the lowest porosity is achieved at a spray rate (F) of 35 g/min, a spray distance (D) of 0.3 m, and an oxygen/propane ratio (R) of 6. The interactions between D and R, as well as between F and D, are statistically significant, influencing each other's effects on porosity. However, the interaction between F and R is relatively low, indicating that changes in one parameter have less impact on porosity when the other parameter is varied. Similarly, for the highest coating hardness, the optimal spray mode includes an F of 35 g/min, D of 0.25 m, and R of 6. There is a significant interaction between F and D, while the interaction between F and R is relatively low. Notably, there is no interaction between F and

How has the COVID-19 epidemic affected the risk behaviors of people who inject drugs in a city with high harm reduction service coverage in Vietnam? A qualitative investigation

International audienceAbstract Introduction The COVID-19 outbreak disproportionally affects vulnerable populations including people who inject drugs (PWID). Social distancing and stay-at-home orders might result in a lack of access to medical and social services, poorer mental health, and financial precariousness, and thus, increases in HIV and HCV risk behaviors. This article explores how the HIV/HCV risk behaviors of PWID in Haiphong, a city with high harm reduction service coverage in Vietnam, changed during the early phase of the COVID-19 pandemic, and what shaped such changes, using the risk environment framework. Method We conducted three focus group discussions with peer outreach workers in May 2020 at the very end of the first lockdown, and 30 in-depth interviews with PWID between September and October 2020, after the second wave of infection in Vietnam. Discussions and interviews centered on the impact of the COVID-19 pandemic on their lives, and how their drug use and sexual behaviors changed as a result of the pandemic. Results The national shutdown of nonessential businesses due to the COVID-19 epidemic caused substantial economic challenges to participants, who mostly were in a precarious financial situation before the start of the epidemic. Unsafe injection is no longer an issue among our sample of PWID in Haiphong thanks to a combination of different factors, including high awareness of injection-related HIV/HCV risk and the availability of methadone treatment. However, group methamphetamine use as a means to cope with the boredom and stress related to COVID-19 was common during the lockdown. Sharing of smoking equipment was a standard practice. Female sex workers, especially those who were active heroin users, suffered most from COVID-related financial pressure and may have engaged in unsafe sex. Conclusion While unsafe drug injection might no longer be an issue, group methamphetamine use and unsafe sex were the two most worrisome HIV/HCV risk behaviors of PWID in Haiphong during the social distancing and lockdown periods. These elevated risks could continue beyond the enforced lockdown periods, given PWID in general, and PWID who are also sex workers in particular, have been disproportionately affected during the global crisis

Gender Differences in HIV, HCV risk and Prevention Needs Among People who Inject drug in Vietnam

International audienceWe examined gender differences among people who inject drug (PWID) in Hai Phong, Vietnam in term of blood-borne infections, risk behaviors, and access to care. Using respondent-driven-sampling surveys, we recruited 3146 PWID from 2016 to 2018. Inclusion criteria included a positive urine test for heroin and recent injection marks. There were 155 female PWID (4,9%), including 82 at RDS-2016, 32 at RDS-2017 and 38 at RDS-2018. The age mean was 36.3 ± 7.2 years. The majority of female PWID had less than high school education (90.9%) and were unemployed (51.3%). There was no difference in the proportion of HIV and HCV positive by gender. However, women had several significant differences in risk behaviors than men in multivariable logistic regression. Being a woman was independently associated with being unemployed, being a sex worker, having unstable housing, having uses drugs for less than 5 years, more use of methamphetamine, having a partner who ever injected drugs, and less access to methadone treatment. Interventions targeting female PWID are needed, possibly through community organizations and peer educators

A community-based intervention to decrease the prevalence of HIV viremia among people who inject drugs in Vietnam

International audienceBackground In most low-to-middle-income countries, HIV control at the population level among people who inject drugs (PWID) remains a major challenge. We aimed to demonstrate that an innovative intervention can identify HIV-positive PWID in the community who are not treated efficiently, and get them treated efficiently.Methods Between 2016 and 2020, we implemented an intervention consisting of mass HIV screening of PWID using three annual respondent-driven sampling surveys (RDSS) and a post-intervention evaluation RDSS in community-based organisation (CBO) sites, coupled with peer support to facilitate/improve access to antiretroviral and methadone therapy in Haiphong, Vietnam. The primary outcome was the proportion of identified uncontrolled HIV-positive PWID who achieved viral control. We also estimated the potential effect of the intervention on the proportion of PWID with HIV RNA >1000 copies/mL among all PWID during the study period.Findings Over the three RDSS, 3150 different PWID were screened, i.e. two-thirds of the estimated population size. They all injected heroin, their median age was of 39 years, 95% were male, 26.5% were HIV-infected, and 78.6% of the latter had HIV RNA ≤1000 copies/mL. Among the 177 PWID identified with an unsuppressed viral load, 73 (41.2%) achieved viral suppression at the final visit. HIV viremia decreased from 7.2% at baseline to 2.9% at the final RDSS (p<0.001). Up to 42% of this observed reduction may be explained by the intervention, in the absence of any external intervention targeting PWID during the study period.Interpretation Mass community-based screening using RDSS coupled with CBO support is a powerful tool to rapidly identify untreated HIV-positive PWID and (re)link them to care

Maintaining HIV and HCV prevention and care for people who inject drugs despite COVID-19 in Hai Phong, Vietnam

International audienceBackground: After the emergence of COVID-19, a one-month strict lockdown was imposed in April 2020 in Vietnam, followed by lighter social distancing restrictions over the year. We investigated whether those measures affected people who inject drugs (PWID) in terms of risk behaviors for HIV and HCV and access to prevention and care in the city of Haiphong, a historic hotspot for HIV and drug use.Methodology: We carried out a ‘before-after’ study from 2019 to 2020 using respondent-driven sampling method to enroll PWID. They were interviewed on their socioeconomic situation, drug use and sexual behaviors, relations to care services and tested for drugs and methadone in the urine, for HIV, HCV, and HIV plasma viral load when HIV-positive. Changes following the restrictions were assessed by comparing ‘before’ to ‘after’ data.Results: 780 PWID were enrolled. Mean age was 44 years; 94% were male. All were actively injecting heroin ‘before’, versus 56% ‘after’. Among those, frequency of consumption decreased from 24 to 17 days per month. No changes were observed in the frequency and practices of methamphetamine smoking. The proportion of PWID on MMT increased from 68.7 to 75.3%, and that of PWID engaging in risky behaviors related to drug injection decreased from 6.0 to 1.5%. No HIV seroconversions were observed; HCV incidence was 2.6/100 person-years (95% CI [0.7-6.7]). 9% of PWID reported a monthly income of less than 130USD ‘before’ versus 53% ‘after’.Conclusion: The case of Hai Phong shows that it is possible, during times of COVID-19 pandemic, to maintain access to harm reduction and care and to prevent HIV and HCV transmission among PWID in a resource-limited setting where severe social distancing restrictions are implemented. Further research is needed to assess the consequences of long-term economic difficulties and the impact of actual spread of SARS-Cov2 that has since emerged in Haiphong

Assessment of a psychiatric intervention at community level for people who inject drugs in a low-middle income country: the DRIVE-Mind cohort study in Hai Phong, Viet Nam

International audienceBackground: Access to psychiatric care for people who inject drugs (PWID) is limited/absent and stigmatized in most low-middle-income countries (LMICs). Innovative interventions are needed. We aimed to describe and assess the impact of a community-based psychiatric intervention among PWID in Hai Phong, Vietnam.Methods: In a cohort study with one year psychiatric follow-up, PWID diagnosed with a psychotic disorder, a major depressive episode, or suicide risk, were recruited from the wider Drug-Related Infections in ViEtnam (DRIVE) project in the city of Hai Phong. The community-based psychiatric intervention included specialized follow-up (free consultations with psychiatrists, free medication, referral to mental health department for hospitalization when necessary) and support from community-based organisations (case management, harm reduction, administrative support, linkage to HIV care, methadone maintenance treatment and mental health support). The main outcome was reduction/remission of symptoms. Access to and retention in psychiatric care, quality-of-life and stigmatization were also measured pre and post-intervention.Findings: Among the 1212 participants screened from March to May 2019, 271 met the inclusion criteria, 233 (86.3%) accepted the intervention and 170 completed the follow-up (72.9%). At inclusion, 80.6% were diagnosed with current depression, 44.7% with psychotic disorder and 42.4% with suicide risk. After a one-year follow-up, these proportions dropped to 15.9%, 21.8%, and 22.9% respectively. Quality-of-life and perceived stigma related to mental health were also significantly improved, while drug use decreased only marginally.Interpretation: Community-based psychiatric interventions are both feasible and efficient in the Vietnamese context. Similar interventions should be implemented and evaluated in other, different LMICs

Daily heroin injection and psychiatric disorders: A cross-sectional survey among People Who Inject Drugs (PWID) in Haiphong, Vietnam

International audienc

Factors related to intracerebral haematoma in patients with aneurysmal subarachnoid haemorrhage in Vietnam: a multicentre prospective cohort study

Objectives To investigate the impact of intracerebral haematoma (ICH) on the outcomes and the factors related to an ICH in patients with aneurysmal subarachnoid haemorrhage (aSAH) in a low- and middle-income country.Design A multicentre prospective cohort study.Setting Three central hospitals in Hanoi, Vietnam.Participants This study included all patients (≥18 years) presenting with aSAH to the three central hospitals within 4 days of ictus, from August 2019 to June 2021, and excluded patients for whom the admission Glasgow Coma Scale was unable to be scored or patients who became lost at 90 days of follow-up during the study.Outcome measures The primary outcome was ICH after aneurysm rupture, defined as ICH detected on an admission head CT scan. The secondary outcomes were 90-day poor outcomes and 90-day death.Results Of 415 patients, 217 (52.3%) were females, and the median age was 57.0 years (IQR: 48.0–67.0). ICH was present in 20.5% (85/415) of patients with aSAH. There was a significant difference in the 90-day poor outcomes (43.5% (37/85) and 29.1% (96/330); p=0.011) and 90-day mortality (36.5% (31/85) and 20.0% (66/330); p=0.001) between patients who had ICH and patients who did not have ICH. The multivariable regression analysis showed that systolic blood pressure (SBP) ≥140 mm Hg (adjusted odds ratio (AOR): 2.674; 95% CI: 1.372 to 5.214; p=0.004), World Federation of Neurosurgical Societies (WFNS) grades II (AOR: 3.683; 95% CI: 1.250 to 10.858; p=0.018) to V (AOR: 6.912; 95% CI: 2.553 to 18.709; p&lt;0.001) and a ruptured middle cerebral artery (MCA) aneurysm (AOR: 3.717; 95% CI: 1.848 to 7.477; p&lt;0.001) were independently associated with ICH on admission.Conclusions In this study, ICH was present in a substantial proportion of patients with aSAH and contributed significantly to a high rate of poor outcomes and death. Higher SBP, worse WFNS grades and ruptured MCA aneurysms were independently associated with ICH on admission