Influence of a transverse static magnetic field on the magnetic hyperthermia properties and high-frequency hysteresis loops of ferromagnetic FeCo nanoparticles

The influence of a transverse static magnetic field on the magnetic hyperthermia properties is studied on a system of large-losses ferromagnetic FeCo nanoparticles. The simultaneous measurement of the high-frequency hysteresis loops and of the temperature rise provides an interesting insight into the losses and heating mechanisms. A static magnetic field of only 40 mT is enough to cancel the heating properties of the nanoparticles, a result reproduced using numerical simulations of hysteresis loops. These results cast doubt on the possibility to perform someday magnetic hyperthermia inside a magnetic resonance imaging setup.Comment: 6 pages, 3 figure

Loss to Follow-Up Among Adults Attending Human Immunodeficiency Virus Services in England, Wales, and Northern Ireland

AIM: To assess the extent to which human immunodeficiency virus (HIV)-diagnosed adults attending HIV-services in England, Wales, and Northern Ireland are lost to follow-up or attend services intermittently. METHODS: A cohort of HIV-diagnosed adults was created by linking records across the 1998 to 2007 national annual Survey of Prevalent HIV Infections Diagnosed. The records were also linked to the national HIV and acquired immune deficiency syndrome New Diagnoses Database (n = 61,495) and to Office for National Statistics death records. Patterns of HIV-service attendance were analyzed. RESULTS: On average, 90% of adults attending HIV-services in any one year attended the following year. Nearly 5% of adults attending services in any one year were lost to follow-up, a further 4% subsequently attended services intermittently, whereas less than 2% died. Cumulatively, 19% of adults seen for HIV care between 1998 and 2006 were lost to follow-up by the end of 2007. Factors associated with loss to follow-up included being the following: female; aged 15 to 34 years; black-African or "other" ethnicity; not on antiretroviral therapy; recently diagnosed; and infected outside the United Kingdom. CONCLUSIONS: Although the majority of HIV-diagnosed adults in England, Wales, and Northern Ireland attended HIV-services regularly, cumulatively nearly 1 in 5 adults were lost to follow-up between 1998 and 2007. Innovative strategies focusing on those most likely to drop out of regular care should be developed to maintain regular service engagement and to ensure optimal care

Experimental investigation of a radiative heat pipe for waste heat recovery in a ceramics kiln

Following the energy crisis in the 1980s, energy-saving technologies have been investigated and implemented in order to decrease the energy consumption and greenhouse gas emissions of major industrial sectors such as metals, ceramics and concrete. The ceramics industry is still, in Europe, one of the major energy consuming manufacturing processes. Hence energy saving solutions have been investigated in order to decrease the energy consumption of the manufacturing process. The main energy-consuming process is the firing stage with more than 50% of all of the energy required for the process. The energy used during the firing stage is then released during the cooling stage. To improve the heat recovered during the cooling stage, a radiative heat pipe ceiling has been investigated. The heat recovered during the cooling stage is then sent to the drying stage. The proposed system is composed of a radiative heat pipe, a kiln and a ceramics heater. The radiative heat pipe is made of ten parallel pipes of 28 mm diameter and a wall thickness of 2 mm the tubes are connected at the bottom by a 28 mm pipe and a condenser section of 50 mm the condenser is a shell and tube system with 9 pipes of 10 mm. The system was cooled by water. The radiative heat pipe has been tested at different flow rate and ceramics heater temperature. The experimental results shown that the radiative heat pipe was able to recover heat using radiation and natural convection in an enclosed kiln. The system was able to recover up to 4 kW. This paper describes this innovative solution for recovering heat from the cooling stage of an earth roller kiln for tile ceramics manufacturing, transformed into hot clean air for the drying stage of the ceramics manufacturing process

Experimental investigation, CFD and theoretical modeling of two-phase heat transfer in a three-leg multi-channel heat pipe

Copyright © 2022 The Author(s). Muti-channel flat heat pipe is an innovative technology recently used at the rear of photovoltaic cells to absorb and reuse the wasted heat. To better understand the fundamentals of two-phase heat transfer (boiling and condensation) taking place inside multi-channel heat pipes, a unique three-leg heat pipe has been built. This one-of-a-kind heat pipe was used to develop both computational fluid dynamic (CFD) and theoretical models of a multi-channel heat pipe. To simulate the heat pipe operation with ANSYS Fluent, the Volume of Fluid (VOF) approach and Lee model were investigated. Different types of Lee models using user defined function (UDF) were compared and the influence of the condenser's boundary condition, saturation temperature, and mass transfer coefficient on the simulations was studied. For the first time, major limits of the Lee model for the simulation of heat pipes are identified. It is concluded that the available Lee model cannot predict the heat pipe temperature as it shows low physical meaning and can easily be manipulated to adjust the simulation's results. Based on the three-leg heat pipe experimental data, a new multi-channel theoretical model was developed that uses the thermal-electrical resistance analogy to predict the three-leg heat pipe thermal resistance. By selecting the optimum correlations for pool boiling and filmwise condensation, the developed iterative theoretical model was able to predict the three-leg heat pipe thermal resistance with an error of 8.2%.European Union's H2020 Programme ETEKINA and iWAYS under grant agreement numbers 768772 and 958274

Experimental and theoretical investigation of the influence of heat transfer rate on the thermal performance of a multi-channel flat heat pipe

Copyright © 2022 The Authors. Recently, flat heat pipes have been proposed for surface cooling applications to passively extract and recover thermal energy from hot surfaces. For instance, flat heat pipes have recently been proposed as thermal absorber for photovoltaic/thermal (PV/T) applications or for the thermal management of batteries. Following promising surface cooling results, increasing the fundamental knowledge of the two-phase heat transfer taking place inside such multi-channel flat heat pipes can participate to its widespread and lead to further improvement of the technology. Indeed, until now, the investigations have focused on the application only and not on the performance of the flat heat pipe itself. In this regard, this manuscript experimentally and theoretically investigates the thermal performance of a multi-channel flat heat pipe used for surface cooling applications. Heat transfer rates in the range 0–1500W are studied and their impact on the boiling, condensation, and total thermal resistance of the multi-channel flat heat pipe is measured. In order to predict the thermal performance of the multi-channel flat heat pipe at all heat transfer rates, a theoretical model is proposed, which considers the impact of the multi-channel geometry. This model uses a multi-channel thermal resistance network. Furthermore, an important number of two-phase correlations for pool boiling and condensation are compared with experimental data and the optimum equations are integrated into the multi-channel model. As a result, over the whole range of heat transfer rates investigated, the proposed multi-channel flat heat pipe model was able to predict the boiling, condensation, and total thermal resistances of the heat pipe with an average error of 17.2%, 14.4% and 13.1%, respectively. Finally, the impact of the tilt angle is also studied, and infrared imaging of the flat heat pipe surface is presented.UK Innovate project: “High-Power and High-Energy Battery Systems with Integrated Structural Thermal Management for Heavy-Duty Applications” funded by Innovate UK. Project reference: 105302

HIV continuum of care in Europe and Central Asia.

OBJECTIVES: The European Centre for Disease Prevention and Control (ECDC) supports countries to monitor progress in their response to the HIV epidemic. In line with these monitoring responsibilities, we assess how, and to what extent, the continuum of care is being measured across countries. METHODS: The ECDC sent out questionnaires to 55 countries in Europe and Central Asia in 2014. Nominated country representatives were questioned on how they defined and measured six elements of the continuum. We present our results using three previously described frameworks [breakpoints; Joint United Nations Programme on HIV/AIDS (UNAIDS) 90-90-90 targets; diagnosis and treatment quadrant]. RESULTS: Forty countries provided data for at least one element of the continuum. Countries reported most frequently on the number of people diagnosed with HIV infection (37; 93%), and on the number in receipt of antiretroviral therapy (ART) (35; 88%). There was little consensus across countries in their approach to defining linkage to, and retention in, care. The most common breakpoint (>19% reduction between two adjacent elements) related to the estimated number of people living with HIV who were diagnosed (18 of 23; 78%). CONCLUSIONS: We present continuum data from multiple countries that provide both a snapshot of care provision and a baseline against which changes over time in care provision across Europe and Central Asia may be measured. To better inform HIV testing and treatment programmes, standard data collection approaches and definitions across the HIV continuum of care are needed. If countries wish to ensure an unbroken HIV continuum of care, people living with HIV need to be diagnosed promptly, and ART needs to be offered to all those diagnosed

Situation of HIV infections and STIs in the United Kingdom in 2007.

In the United Kingdom (UK) in 2007, an estimated 77,400 persons were living with human immunodeficiency virus (HIV) of whom 28% are unaware of their infection. A total of 7,734 persons were newly diagnosed with HIV infection in 2007, of which 31% were diagnosed late. This highlights the need for wider HIV testing, especially in those areas with a high diagnosed prevalence, as recommended in recent national guidelines. Among newly diagnosed cases of HIV in 2007, 41% acquired their infection through sex between men (four in five of whom acquired their infection in the UK) and 55% through heterosexual contact (four in five of whom acquired their infection abroad, mainly in sub-Saharan Africa). Young persons aged 16 to 24 years are disproportionally affected by sexually transmitted diseases (STIs) accounting for 65% of genital chlamydia infections, 50% of cases of genital warts and 50% of cases of gonorrhoea that were diagnosed in 2007