Linear, diatomic crystal: single-electron states and large-radius excitons

The large-radius exciton spectrum in a linear crystal with two atoms in the unit cell was obtained using the single-electron eigenfunctions and the band structure, which were found by the zero-range potential (ZRP) method. The ground-state exciton binding energies for the crystal in vacuum appeared to be larger than the corresponding energy gaps for any set of the crystal parameters.Comment: 9 pages, 1 figure, 1 tabl

ВЛИЯНИЕ СОСТОЯНИЯ РАБОЧЕЙ ПОВЕРХНОСТИ РАЗЛИВОЧНОГО КОЛЕСА РОТОРНОЙ МНЛЗ НА КАЧЕСТВО МЕТАЛЛОПРОДУКЦИИ

The paper presents the results obtained when studying how the condition of the casting wheel working surface in the rotary continuous casting machine (CCM) influences the quality of copper metal products on the Southwire modern high-tech continuous casting and rolling line at PJSC «Artemovsk Non-Ferrous Metals Processing Works». Industrial research identified the main defects occurred on the casting wheel working surface during its operation: transverse cracks located on the working surface in planes perpendicular to the casting direction – both at the trapezoid base and on its side faces (10–45 mm long cracks located 7–40 mm apart); dents, longitudinal dimples and scratches along the direction of billet movement mainly in the obtuse angles of the trapezoid and in areas adjacent thereto; deformed wheel profile in the corners of the working channel, primarily due to friction wear. It was found that the main causes of surface and internal cracks in the wheel are challenging temperature modes of operation associated with the technology of copper casting on the rotary CCM. Alternating cycles of heating and cooling of individual sections of the casting wheel cause two-dimensional tensile stresses in its internal layers resulting in cracks. An equally important factor in crack formation is further excessive secondary cooling of the wheel with water as it is followed by reheating of the billet surface. However, a lowered temperature gradient of the wheel surface between the cooling areas will reduce the degree of surface deformation, increase the service life and improve the quality of continuously cast billets and finished steel.Представлены результаты изучения влияния состояния рабочей поверхности разливочного колеса роторной машины непрерывного литья заготовок (МНЛЗ) на качество медной металлопродукции в условиях современной высокотехнологичной линии непрерывного литья и прокатки производства фирмы «Southwire» в ПАО «Артемовский завод по обработке цветных металлов». В ходе промышленных исследований выявлены основные дефекты рабочей поверхности разливочного колеса, образующиеся в процессе его эксплуатации: поперечные трещины, располагающиеся на рабочей поверхности в плоскостях, перпендикулярных направлению разливки, – как на основании трапеции, так и боковых гранях (длина трещин составляет 10–45 мм с расстоянием между ними 7–40 мм); выбоины, продольные углубления и царапины, наблюдаемые вдоль направления движения заготовки преимущественно в тупых углах трапеции и областях, прилегающих к ним; деформация профиля колеса в углах рабочего канала, обусловленная, прежде всего, износом вследствие трения. Установлено, что основными причинами формирования поверхностных и внутренних трещин в колесе являются сложные температурные режимы работы, связанные с технологией разливки меди на МНЛЗ роторного типа. Чередующиеся циклы нагрева и охлаждения отдельных участков разливочного колеса приводят к возникновению двумерных растягивающих напряжений в его внутренних слоях, вследствие чего образуются трещины. Не менее важным фактором появления трещин следует считать последующее чрезмерное вторичное охлаждение колеса водой, поскольку за ним следует повторный нагрев поверхности заготовки. Вместе с тем снижение градиента температур поверхности колеса между зонами охлаждения будет способствовать уменьшению степени деформации его поверхности и увеличению срока эксплуатации, а также повышению качества непрерывнолитой заготовки и готового проката

Determining the Technical and Economic Parameters for Designing Hybrid Power Units for the Budget Segment

The paper addresses the issue of designing environmentally friendly and energy-efficient vehicles in a budget segment based on determining the technical-economic parameters. The fuel efficiency and environmental friendliness of cars have been improved and substantiated through devising a hybrid power system based on the chosen rational technical-economic parameters. We have constructed three-dimensional dependences of energy, consumed by the unit of traction rechargeable batteries, and a relative travel range, on the mass and steady speed. Recommendations have been made on selecting the energy intensity of the unit of traction rechargeable batteries for hybrid vehicles of different mass and the desired travel range under an electricity-only mode. We have established the travel range under an electricity-only mode per a single charge of traction rechargeable batteries within 20 km to 50 km. The choice of a hybrid vehicle has been proposed depending on the expected average daily mileage and the energy intensity of traction rechargeable batteries. This would make it possible for a consumer to make a decision about the choice of a hybrid vehicle based on the individual planned average daily mileage.Conceptual solutions have been developed to construct hybrid power units based on the economic principle of their design. The scientific results have been confirmed in practice using an experimental hybrid concept based on the ZAZ Lanos Pickup. Such an approach makes hybrid vehicles more competitive and economically attractiv

People with high HIV viral load within risk networks: Who are these people and who refers them best?

Introduction: Viral load is one of the most important determinants for HIV transmission. Identification of people with high viral load (PHVL) can be effective in limiting onward HIV transmission. In order to improve the identification of these individuals within risk networks, we determined a) the number of PHVL recruited through risk networks b) their socio-demographic, behavioural and clinical characteristics and c) the characteristics of individuals who referred these PHVL to the study. Methodology: From November 2013 to March 2016, in Odessa, Ukraine, Transmission Reduction Intervention Project (TRIP) was implemented to identify people recently infected with HIV within the risk networks of “seeds” and “venues” where they engaged in risk behaviour. Results: TRIP identified 53 PHVL, of whom 32 (60%) injected drugs; 42 (79%) were unaware of their HIV status; 25 (47%) had more than one sex partner, and only 14 (26%) were using condoms. There were 164 people who referred individuals into the study; 33 of them (20%) referred PHVL. In terms of referrers, those with lower than secondary level of education, not living with a sex partner, and reporting regular condom use were significantly more likely (p < 0.05) to refer PHVL. Most PHVL (38, 72%) and their referrers (27, 82%) were found through venues. Conclusions: In Odessa city, PHVL are at high risk of transmitting HIV as the majority inject drugs, do not know their HIV status, and have unprotected sex and/or multiple partners. Targeting these individuals for HIV prevention, harm reduction and initiation of antiretroviral treatment (ART) is urgent. Copyright © 2019 Korobchuk et al

Phylodynamics and migration data help describe HIV transmission dynamics in internally displaced people who inject drugs in Ukraine.

Internally displaced persons are often excluded from HIV molecular epidemiology surveillance due to structural, behavioral, and social barriers in access to treatment. We test a field-based molecular epidemiology framework to study HIV transmission dynamics in a hard-to-reach and highly stigmatized group, internally displaced people who inject drugs (IDPWIDs). We inform the framework by Nanopore generated HIV pol sequences and IDPWID migration history. In June-September 2020, we recruited 164 IDPWID in Odesa, Ukraine, and obtained 34 HIV sequences from HIV-infected participants. We aligned them to publicly available sequences (N = 359) from Odesa and IDPWID regions of origin and identified 7 phylogenetic clusters with at least 1 IDPWID. Using times to the most recent common ancestors of the identified clusters and times of IDPWID relocation to Odesa, we infer potential post-displacement transmission window when infections likely to happen to be between 10 and 21 months, not exceeding 4 years. Phylogeographic analysis of the sequence data shows that local people in Odesa disproportionally transmit HIV to the IDPWID community. Rapid transmissions post-displacement in the IDPWID community might be associated with slow progression along the HIV continuum of care: only 63% of IDPWID were aware of their status, 40% of those were in antiviral treatment, and 43% of those were virally suppressed. Such HIV molecular epidemiology investigations are feasible in transient and hard-to-reach communities and can help indicate best times for HIV preventive interventions. Our findings highlight the need to rapidly integrate Ukrainian IDPWID into prevention and treatment services following the dramatic escalation of the war in 2022

Phylodynamics and migration data help describe HIV transmission dynamics in internally displaced people who inject drugs in Ukraine

Internally displaced persons are often excluded from HIV molecular epidemiology surveillance due to structural, behavioral, and social barriers in access to treatment. We test a field-based molecular epidemiology framework to study HIV transmission dynamics in a hard-to-reach and highly stigmatized group, internally displaced people who inject drugs (IDPWIDs). We inform the framework by Nanopore generated HIV pol sequences and IDPWID migration history. In June-September 2020, we recruited 164 IDPWID in Odesa, Ukraine, and obtained 34 HIV sequences from HIV-infected participants. We aligned them to publicly available sequences (N = 359) from Odesa and IDPWID regions of origin and identified 7 phylogenetic clusters with at least 1 IDPWID. Using times to the most recent common ancestors of the identified clusters and times of IDPWID relocation to Odesa, we infer potential post-displacement transmission window when infections likely to happen to be between 10 and 21 months, not exceeding 4 years. Phylogeographic analysis of the sequence data shows that local people in Odesa disproportionally transmit HIV to the IDPWID community. Rapid transmissions post-displacement in the IDPWID community might be associated with slow progression along the HIV continuum of care: only 63% of IDPWID were aware of their status, 40% of those were in antiviral treatment, and 43% of those were virally suppressed. Such HIV molecular epidemiology investigations are feasible in transient and hard-to-reach communities and can help indicate best times for HIV preventive interventions. Our findings highlight the need to rapidly integrate Ukrainian IDPWID into prevention and treatment services following the dramatic escalation of the war in 2022

Hepatitis C Virus in people with experience of injection drug use following their displacement to Southern Ukraine before 2020

Abstract Background Due to practical challenges associated with genetic sequencing in low-resource environments, the burden of hepatitis C virus (HCV) in forcibly displaced people is understudied. We examined the use of field applicable HCV sequencing methods and phylogenetic analysis to determine HCV transmission dynamics in internally displaced people who inject drugs (IDPWID) in Ukraine. Methods In this cross-sectional study, we used modified respondent-driven sampling to recruit IDPWID who were displaced to Odesa, Ukraine, before 2020. We generated partial and near full length genome (NFLG) HCV sequences using Oxford Nanopore Technology (ONT) MinION in a simulated field environment. Maximum likelihood and Bayesian methods were used to establish phylodynamic relationships. Results Between June and September 2020, we collected epidemiological data and whole blood samples from 164 IDPWID (PNAS Nexus.2023;2(3):pgad008). Rapid testing (Wondfo® One Step HCV; Wondfo® One Step HIV1/2) identified an anti-HCV seroprevalence of 67.7%, and 31.1% of participants tested positive for both anti-HCV and HIV. We generated 57 partial or NFLG HCV sequences and identified eight transmission clusters, of which at least two originated within a year and a half post-displacement. Conclusions Locally generated genomic data and phylogenetic analysis in rapidly changing low-resource environments, such as those faced by forcibly displaced people, can help inform effective public health strategies. For example, evidence of HCV transmission clusters originating soon after displacement highlights the importance of implementing urgent preventive interventions in ongoing situations of forced displacement

Hepatitis C Virus in people with experience of injection drug use following their displacement to Southern Ukraine before 2020.

Acknowledgements: We acknowledge the assistance of public health workers from the non-governmental organisations “Alliance for Public Health” and “Way Home” in collection of epidemiological and behavioural data and biological samples, and their ongoing efforts of providing preventative measures and infection management to at risk populations in Ukraine. We also express our sincere gratitude towards study participants. We thank Rowena Bull and Chaturaka Rodrigo for their advice with MinION based hepatitis C sequencing protocols.BACKGROUND: Due to practical challenges associated with genetic sequencing in low-resource environments, the burden of hepatitis C virus (HCV) in forcibly displaced people is understudied. We examined the use of field applicable HCV sequencing methods and phylogenetic analysis to determine HCV transmission dynamics in internally displaced people who inject drugs (IDPWID) in Ukraine. METHODS: In this cross-sectional study, we used modified respondent-driven sampling to recruit IDPWID who were displaced to Odesa, Ukraine, before 2020. We generated partial and near full length genome (NFLG) HCV sequences using Oxford Nanopore Technology (ONT) MinION in a simulated field environment. Maximum likelihood and Bayesian methods were used to establish phylodynamic relationships. RESULTS: Between June and September 2020, we collected epidemiological data and whole blood samples from 164 IDPWID (PNAS Nexus.2023;2(3):pgad008). Rapid testing (Wondfo® One Step HCV; Wondfo® One Step HIV1/2) identified an anti-HCV seroprevalence of 67.7%, and 31.1% of participants tested positive for both anti-HCV and HIV. We generated 57 partial or NFLG HCV sequences and identified eight transmission clusters, of which at least two originated within a year and a half post-displacement. CONCLUSIONS: Locally generated genomic data and phylogenetic analysis in rapidly changing low-resource environments, such as those faced by forcibly displaced people, can help inform effective public health strategies. For example, evidence of HCV transmission clusters originating soon after displacement highlights the importance of implementing urgent preventive interventions in ongoing situations of forced displacement