Integration of external and internal dosimetry in Switzerland

Individual monitoring regulations in Switzerland are based on the ICRP60 recommendations. The annual limit of 20 mSv for the effective dose applies to the sum of external and internal radiation. External radiation is monitored monthly or quarterly with TLD, DIS or CR-39 dosemeters by 10 approved external dosimetry services and reported as Hp(10) and Hp(0.07). Internal monitoring is done in two steps. At the workplace, simple screening measurements are done frequently in order to recognise a possible incorporation. If a nuclide dependent activity threshold is exceeded then one of the seven approved dosimetry services for internal radiation does an incorporation measurement to assess the committed effective dose E50. The dosimetry services report all the measured or assessed dose values to the employer and to the National Dose Registry. The employer records the annually accumulated dose values into the individual dose certificate of the occupationally exposed person, both the external dose Hp(10) and the internal dose E50 as well as the total effective dose E = Hp(10)+E50. Based on the national dose registry an annual report on the dosimetry in Switzerland is published which contains the statistics for the total effective dose, as well as separate statistics for external and internal exposur

The heating triangle: A quantitative review of self-heating methods for lithium-ion batteries at low temperatures

Lithium-ion batteries at low temperatures have slow recharge times alongside reduced available power and energy. Battery heating is a viable way to address this issue, and self-heating techniques are appealing due to acceptable efficiency and speed. However, there are a lack of studies quantitatively comparing self-heating methods rather than qualitatively, because of the existence of many different batteries with varied heating parameters. In this work, we review the current state-of-the-art self-heating methods and propose the heating triangle as a new quantitative indicator for comparing self-heating methods, towards identifying/developing effective heating approaches. We define the heating triangle which considers three fundamental metrics: the specific heating rate (°C·g·J−1), coefficient of performance (COP) (−), and specific temperature difference (°C·hr), enabling a quantitative assessment of self-heating methods using data reported in the literature. Our analysis demonstrates that very similar metrics are observed for the same type of self-heating method, irrespective of the study case, supporting the universality of the proposed indicator. With the comparison insights, we identify research gaps and new avenues for developing advanced self-heating methods. This work demonstrates the value of the proposed heating triangle as a standardised approach to compare heating methods and drive innovation

Using Semantic Web technologies in the development of data warehouses: A systematic mapping

The exploration and use of Semantic Web technologies have attracted considerable attention from researchers examining data warehouse (DW) development. However, the impact of this research and the maturity level of its results are still unclear. The objective of this study is to examine recently published research articles that take into account the use of Semantic Web technologies in the DW arena with the intention of summarizing their results, classifying their contributions to the field according to publication type, evaluating the maturity level of the results, and identifying future research challenges. Three main conclusions were derived from this study: (a) there is a major technological gap that inhibits the wide adoption of Semantic Web technologies in the business domain;(b) there is limited evidence that the results of the analyzed studies are applicable and transferable to industrial use; and (c) interest in researching the relationship between DWs and Semantic Web has decreased because new paradigms, such as linked open data, have attracted the interest of researchers.This study was supported by the Universidad de La Frontera, Chile, PROY. DI15-0020. Universidad de la Frontera, Chile, Grant Numbers: DI15-0020 and DI17-0043

Diagenetic evolution of lower Jurassic platform carbonates flanking the Tazoult salt wall (Central High Atlas, Morocco)

Platform carbonates diagenesis in salt basins could be complex due to potential alterations of fluids related and non‐related to diapirism. This paper presents the diagenetic history of the Hettangian to Pliensbachian platform carbonates from the Tazoult salt wall area (central High Atlas, Morocco). Low structural relief and outcrop conditions allowed to define the entire diagenetic evolution occurred in the High Atlas diapiric basins since early stages of the diapiric activity up to their tectonic inversion. Precipitation of dolomite and calcite from both warmed marine‐derived and meteoric fluids characterised diagenetic stages during Pliensbachian, when the carbonate platforms were exposed and karstified. Burial diagenesis occurred from Toarcian to Middle Jurassic, due to changes of salt‐induced dynamic related to increase in siliciclastic input, fast diapir rise and rapid burial of Pliensbachian platforms. During this stage, the diapir acted as a physical barrier for fluid circulation between the core and the flanking sediments. In the carbonates and breccias flanking the structures, dolomite and calcite precipitated from basinal brines, whereas carbonate slivers located in the core of the structure, were affected by the circulation of Mn‐rich fluids. The final diagenetic event is characterised by the income of meteoric fluids into the system during uplift caused by Alpine orogeny. These results highlight the relevant influence of diapirism on the diagenetic modifications in salt‐related basins in terms of diagenetic events and involved fluids

Aggregation kinetics of human mesenchymal stem cells under wave motion

Human mesenchymal stem cells (hMSCs) are a primary candidate in cell therapy and regenerative medicine to treat a wide range of diseases in clinical trials. Recent studies showed that hMSC have innate ability to self-assemble into three-dimensional (3D) aggregates that enhances their therapeutic functions with augmented multi-lineage differentiation potential, migration ability, secretion of anti-inflammatory and angiogenic factors, and resistance to ischemic conditions post-transplantation. To date, many laboratory methods have been developed for hMSC aggregation, including hanging drops, centrifugation with microfabricated surface, cell suspension on a low attachment surface, thermal lifting, and microfluidic technologies. However, these methods have limited scalability and/or poor control in aggregate size, and cannot meet the required production in clinical trials. The objective of current study is to investigate the conditions for the scalable production of hMSC aggregates in non-adherent plates under wave motion. The repeated back and forth wave motion induced by rocking provides mixing of bulk medium under low shear stress that facilitates cell-cell collisions and subsequent aggregation. Our results showed that aggregate size can be controlled by adjusting the combination of rocking angle (3˚, 6˚, and 9˚) and rocking speed (10, 15, and 20 rpm). To quantify the impact of fluid shear stress on aggregation kinetics, simulation of shear stress distribution by COMSOL Multiphysics® showed a time-dependent oscillatory function under different rocking condition. In addition, an inverse correlation between aggregate size and maximum shear stress was observed and that both can be regressed by a two-variable linear regression of rocking angle and rocking speed. In the regression, the coefficient of rocking angle is much higher than that of rocking speed, revealing that rocking angle has a more significant effect than rocking speed on both aggregate size and shear stress. In addition to fluid shear stress, the effects of cell binding molecules, the frequency of cell-cell collision, and the extension of cultivation time on aggregate size distribution were also investigated. Analysis of the therapeutic functional supported that hMSCs derived from engineered aggregates in the wave motion system have enhanced their therapeutic properties compared to those from monolayer culture

Numerical methods for the design and description of in vitro expansion processes of human mesenchymal stem cells

Human mesenchymal stem cells (hMSCs) are a valuable source of cells for clinical applications (e.g., treatment of acute myocardial infarction or inflammatory diseases), especially in the field of regenerative medicine. However, for autologous (patient-specific) and allogeneic (off-the-shelf) hMSC-based therapies, in vitro expansion is necessary prior to the clinical application in order to achieve the required cell numbers. Safe, reproducible, and economic in vitro expansion of hMSCs for autologous and allogeneic therapies can be problematic because the cell material is restricted and the cells are sensitive to environmental changes. It is beneficial to collect detailed information on the hydrodynamic conditions and cell growth behavior in a bioreactor system, in order to develop a so called “Digital Twin” of the cultivation system and expansion process. Numerical methods, such as Computational Fluid Dynamics (CFD) which has become widely used in the biotech industry for studying local characteristics within bioreactors or kinetic growth modelling, provide possible solutions for such tasks. In this review, we will present the current state-of-the-art for the in vitro expansion of hMSCs. Different numerical tools, including numerical fluid flow simulations and cell growth modelling approaches for hMSCs, will be presented. In addition, a case study demonstrating the applicability of CFD and kinetic growth modelling for the development of an microcarrier-based hMSC process will be shown

Novel probes for pH and dissolved oxygen measurements in cultivations from millilitre to benchtop scale

Erworben im Rahmen der Schweizer Nationallizenzen (http://www.nationallizenzen.ch)pH value and the concentration of dissolved oxygen (DO) are key parameters to monitor and control cell growth in cultivation studies. Reliable, robust and accurate methods to measure these parameters in cultivation systems in real time guarantee high product yield and quality. This mini-review summarises the current state of the art of pH and DO sensors that are applied to bioprocesses from millilitre to benchtop scale by means of a short introduction on measuring principles and selected applications. Special emphasis is placed on single-use bioreactors, which have been increasingly employed in bioprocess development and production in recent years. Working principles, applications and the particular requirements of sensors in these cultivation systems are given. In such processes, optical sensors for pH and DO are often preferred to electrochemical probes, as they allow semi-invasive measurements and can be miniaturised to micrometre scale or lower. In addition, selected measuring principles of novel sensing technologies for pH and DO are discussed. These include solid-state sensors and miniaturised devices that are not yet commercially available, but show promising characteristics for possible use in bioprocesses in the near future

Meta-analysis of experimental results for heat capacity and thermal conductivity in lithium-ion batteries: A critical review

Scenarios with rapid energy conversion for lithium-ion batteries are increasingly relevant, due to the desire for more powerful electric tools or faster charging electric vehicles. However, higher power means higher cooling requirements, affecting the battery temperature and its thermal gradients. In turn, temperature is a key quantity influencing battery performance, safety and lifetime. Therefore, thermal models are increasingly important for the design and operation of battery systems. Key parameters are specific heat capacity and thermal conductivity. For these parameters, this paper presents a comprehensive review of the experimental results in the literature, where the median values and corresponding uncertainties are summarized. Whenever available, data is analyzed from component to cell level with the discussion of dependencies on temperature, state of charge (SOC) and state of health (SOH). This meta-analysis reveals gaps in knowledge and research needs. For instance, we uncover inconsistencies between the specific heat capacity of electrode-separator stacks and full-cells. For the thermal conductivity, we found that thermal contact resistance and dependencies on battery states have been poorly studied. There is also a lack of measurements at high temperatures, which are required for safety studies. Overall, this study serves as a valuable reference material for both modellers and experimenters

Simulation and measurement of local potentials of modified commercial cylindrical cells:I. Cell preparation and measurements

This work presents a modification approach and first measurements of commercial cylindrical Li-ion cells with multiple local potential probes and an internal temperature sensor. Local potential measurements at low currents show a non-uniform potential distribution along the electrode, dominated by the open circuit voltage (OCV) of the negative electrode. For higher currents, the overpotential along the current collector becomes dominant and instead of a corrugated potential distribution, a significant current dependent voltage gradient can be detected, indicating a highly non-uniform state of charge (SOC) distribution with increasing distance to the current collecting tab. After the discharge operation, a quick potential equalization can be witnessed which results in a non-detectable potential difference between the single electrode sections after 12 min, even though the overall cell voltage relaxation has not reached an equilibrium state yet. The presented modification approach combines the advantages of high quality industrial manufactured cells showing uniform coating thicknesses and packing density with the advantages of special tailor made cells for in situ measurements. Due to the low impact of the modification and its long-term stability, highly reproducible measurements can be conducted at different locations of the electrodes