A new cure kinetics model to simulate thermomechanical behavior of polymeric sealants for automotive applications

Accurate prediction of the cure level of thermoset polymers is essential to simulate the thermomechanical behavior of polymeric thermoset sealants, which is strongly dependent on cure level. Conventional cure kinetics models, however, fail to accurately predict the cure levels of thermoset sealants subjected to a complex temperature program. Herein, we propose a new cure kinetics model that greatly enhances cure level predictability by considering temperature derivatives. The validity of our model was verified by simulating the thermomechanical behavior of a polymeric sealant using a user material subroutine (UMAT) of ABAQUS software. Experimental results from an appropriately designed thermomechanical test were compared with simulation results obtained from the UMAT.

Analysis of perspective air preparation network designs in launch complex temperature control systems

The purpose of the research is to perform a comparative analysis of compressed air preparation systems on the basis of moisture content. The article discusses conventional and perspective methods for drying compressed air using condensation, adsorption and membrane technologies. The article considers a temperature control system with the required dew point of minus 25°С at the exit under standard conditions, which corresponds to the dew point temperature plus 3 °С at a pressure of 1.0 MPa, or class 4 according to GOST R ISO 8573-1–2016. The main advantages of using advanced technological drying system designs are described, including the design of a modern drier with a rotary adsorber that can reduce the dew point temperature of compressed air to minus 25…30 °С at 1.0 MPa pressure without any losses on the adsorbent regeneration. This research is the first to analyze the applicability of modern adsorption and membrane modules to the launch complex functions. All the air drying designs were considered in this paper in relation to air temperature control systems based on air refrigerators using the I-d hygrometric chart for variable pressures.

A Bayesian semi-parametric model for thermal proteome profiling

The thermal stability of proteins can be altered when they interact with small molecules, other biomolecules or are subject to post-translation modifications. Thus monitoring the thermal stability of proteins under various cellular perturbations can provide insights into protein function, as well as potentially determine drug targets and off-targets. Thermal proteome profiling is a highly multiplexed mass-spectrommetry method for monitoring the melting behaviour of thousands of proteins in a single experiment. In essence, thermal proteome profiling assumes that proteins denature upon heating and hence become insoluble. Thus, by tracking the relative solubility of proteins at sequentially increasing temperatures, one can report on the thermal stability of a protein. Standard thermodynamics predicts a sigmoidal relationship between temperature and relative solubility and this is the basis of current robust statistical procedures. However, current methods do not model deviations from this behaviour and they do not quantify uncertainty in the melting profiles. To overcome these challenges, we propose the application of Bayesian functional data analysis tools which allow complex temperature-solubility behaviours. Our methods have improved sensitivity over the state-of-the art, identify new drug-protein associations and have less restrictive assumptions than current approaches. Our methods allows for comprehensive analysis of proteins that deviate from the predicted sigmoid behaviour and we uncover potentially biphasic phenomena with a series of published datasets.

Satellite Sea Surface Temperature Product Comparison for the Southern African Marine Region

Several satellite-derived Sea Surface Temperature (SST) products were compared to determine their potential for research and monitoring applications around the southern African marine region. This study provides the first detailed comparison for the region, demonstrating good overall agreement (variance < 0.4 °C2) between merged SST products for most of the South African marine region. However, strong disagreement in absolute SST values (variance of 0.4–1.2 °C2 and differences of up to 6 °C) was observed at well-known oceanographic features characterized by complex temperature structures and strong SST gradients. Strong seasonal bias in the discrepancy between SST was observed and shown to follow seasonal increases in cloud cover or local oceanographic dynamics. Disagreement across the L4 products showed little dependence on their spatial resolutions. The periods of disagreement were characterized by large deviations among all products, which resulted mainly from the lack of input observations and reliance on interpolation schemes. This study demonstrates that additional methods such as the ingestion of additional in situ observations or daytime satellite acquisitions, especially along the west coast of southern Africa, might be required in regions of strong SST gradient, to improve their representations in merged SST products. The use of ensemble means may be more appropriate when conducting research and monitoring in these regions of high SST variance.

Large-Scale Field Validation and Practical Application of a Multi-Well Thermal Interaction Model for Temperature Simulation

The wellbore and formation temperature environment around a system of multiple wells in close proximity is complex. Temperature simulation and prediction for a single isolated well is simplified by axisymmetric assumptions. Realistic multi-well environments do not have obvious symmetry and are interactive given different operating states including possibly a mix of producer versus injector wells. A simulation model of thermal interaction between closely spaced wells has been developed in a collaborative project. A large-scale validation of the model is presented here. An important field application is presented for a subsea well template where movement tolerances must be tightly controlled. Large-scale validation was conducted for an offshore platform development where more than 30 wells were drilled and brought onto production over a period of 4-5 years. As each well was drilled and completed, temperature logs where recorded which thereby gave a digital signature of the complex thermal environment below mudline as it evolved over time. The simulation model temperature for each well was corroborated against well temperature logs. A simultaneous boundary-condition of flowing wellhead temperatures and pressures for each well was compared against the model predictions. Also, a detailed predictive case study is presented for a 6 well subsea template. Model temperatures were used to assess the impact of cement height on wellhead movement within the template structure which featured lockdowns and tight tolerances on allowable movement within the housing profile. Predicted temperatures from the multi-well model agree closely with logs and correlate closely with characteristic temperature excursions from geothermal below the mudline down to the well path kick-off zone. Since the logs occur over time and account for a changing well population, the model is shown to accurately capture the time evolution of the complex temperature environment. The model explains unusual temperature log signatures as the result of sidetracks and the radial extent of heat affected zones from the parent wellbore. The subsea case study highlights the importance of predicting the complex multi-well temperature environment by demonstrating its impact on the wellhead movement given the uncertainty of cement tops for deeper shoes of combined conductor/surface casings. This learning informs subsea template design and selection with port options for cement grout and top-up jobs. Although the multi-well temperature model has been presented previously along with some field data validation, the large-scale study presented provides further and significant model validation. Extensive data over time and corroboration with unusual temperature log phenomena demonstrate model accuracy. The utilization of the model in the design and specification of a subsea template development provides a real-world example and demonstrates practical application as well as its usefulness.

Observations of internal gravity waves in vicinity of jet streams during SouthTRAC flight on 16 September 2019

&lt;p&gt;The combination of the airborne GLORIA (Gimballed Limb Observer for Radiance Imaging of the Atmosphere) and ALIMA (Airborne LIdar for Middle Atmosphere research) instruments allows for probing of temperature perturbations associated with gravity waves within the range from the troposphere up to the mesosphere. Both instruments were part of the scientific payload of the German HALO (High Altitude and LOng Range Research Aircraft) during the SouthTRAC-GW (Southern hemisphere Transport, Dynamics, and Chemistry - Gravity Waves) mission, aiming at probing gravity waves in the hotspot region around South America and the Antarctic peninsula. For the research flight on 16 September 2019, complex temperature perturbations attributed to internal gravity waves were forecasted well above the Atlantic to the south-west of Buenos Aires, Argentina. The forecasted temperature perturbations were located in a region where the polar front jet stream met with the subtropical jet, with the polar night jet above. We present temperature perturbations observed by GLORIA and ALIMA during the discussed flight and compare the data with ECMWF IFS (European Centre for Medium-Range Weather Forecasts &amp;#8211; Integrated Forecasting System) high-resolution deterministic forecasts, aiming at validating the IFS data and identifying sources of the observed wave patterns.&lt;/p&gt;

Studies of Catalyst-Controlled Regioselective Acetalization and Its Application to Single-Pot Synthesis of Differentially Protected Saccharides.

This article describes the studies of regioselective acetal protection of monosaccharide-based diols using chiral phosphoric acids (CPAs) as the catalysts. These catalyst-controlled regioselective acetalizations were found to proceed with high regioselectivities (up to >25:1 rr) on various <i>D</i>-glucose, <i>D</i>-galactose, <i>D</i>-mannose and <i>L</i>-fucose derived 1,2-diols and could be carried with immobilized and recyclable catalyst. The utility of CPA-catalyzed acetalizations was further demonstrated for the regioselective single-pot preparation of various differentially protected mono- and disaccharide building blocks. The computational and mechanistic studies indicate complex temperature-dependent interplay of two reaction mechanisms, one involving an anomeric phosphate intermediate and another via concerted asynchronous formation of acetal. The computational models explain the steric factors responsible for the observed C2-selectivities and are consistent with the experimentally observed selectivity trends.

Studies of Catalyst-Controlled Regioselective Acetalization and Its Application to Single-Pot Synthesis of Differentially Protected Saccharides.

This article describes the studies of regioselective acetal protection of monosaccharide-based diols using chiral phosphoric acids (CPAs) as the catalysts. These catalyst-controlled regioselective acetalizations were found to proceed with high regioselectivities (up to >25:1 rr) on various <i>D</i>-glucose, <i>D</i>-galactose, <i>D</i>-mannose and <i>L</i>-fucose derived 1,2-diols and could be carried with immobilized and recyclable catalyst. The utility of CPA-catalyzed acetalizations was further demonstrated for the regioselective single-pot preparation of various differentially protected mono- and disaccharide building blocks. The computational and mechanistic studies indicate complex temperature-dependent interplay of two reaction mechanisms, one involving an anomeric phosphate intermediate and another via concerted asynchronous formation of acetal. The computational models explain the steric factors responsible for the observed C2-selectivities and are consistent with the experimentally observed selectivity trends.