Properties of Phase transitions of a Higher Order

The following is a thermodynamic analysis of a III order (and some aspects of a IV order) phase transition. Such a transition can occur in a superconductor if the normal state is a diamagnet. The equation for a phase boundary in an H-T (H is the magnetic field, T, the temperature) plane is derived. by considering two possible forms of the gradient energy, it is possible to construct a field theory which describes a III or a IV order transition and permits a study of thermal fluctuations and inhomogeneous order parameters.Comment: 13 pages, revtex, no figure

Organic acids as cloud condensation nuclei: Laboratory studies of highly soluble and insoluble species

International audienceThe ability of sub-micron-sized organic acid particles to act as cloud condensation nuclei (CCN) has been examined at room temperature using a newly constructed continuous-flow, thermal-gradient diffusion chamber (TGDC). The organic acids studied were: oxalic, malonic, glutaric, oleic and stearic. The CCN properties of the highly soluble acids - oxalic, malonic and glutaric - match very closely Köhler theory predictions which assume full dissolution of the dry particle and a surface tension of the growing droplet equal to that of water. In particular, for supersaturations between 0.3 and 0.6, agreement between the dry particle diameter which gives 50% activation and that calculated from Köhler theory is to within 3nm on average. In the course of the experiments, considerable instability of glutaric acid particles was observed as a function of time and there is evidence that they fragment to some degree to smaller particles. Stearic acid and oleic acid, which are both highly insoluble in water, did not activate at supersaturations of 0.6% with dry diameters up to 140nm. Finally, to validate the performance of the TGDC, we present results for the activation of ammonium sulfate particles that demonstrate good agreement with Köhler theory if solution non-ideality is considered. Our findings support earlier studies in the literature that showed highly soluble organics to be CCN active but insoluble species to be largely inactive

Torque ripples minimization of DTC IPMSM drive for the EV propulsion system using a neural network

This paper deals with a Direct Torque Control (DTC) of an Interior Permanent Magnet Synchronous Motor (IPMSM) for the Electric Vehicle (EV) propulsion system using a Neural Network (NN). The Conventional DTC with optimized switching lookup table and three level torque controller generates relatively large torque ripples in an electric vehicle motor drive. For reducing the torque ripples, a three level torque controller is hereby replaced by the five level torque controller. Furthermore, the switching lookup table of the five level torque controller based DTC is replaced with a Neural Network. These DTC schemes of an IPMSM drive are simulated using MATLAB/SIMULINK. The simulated results are compared with the conventional DTC and it is found that the ripples in the torque, as well as in the stator current, are reduced drastically

Qualitative observation of reversible phase change in astrochemical ethanethiol ices using infrared spectroscopy

Here we report the first evidence for a reversible phase change in an ethanethiol ice prepared under astrochemical conditions. InfraRed (IR) spectroscopy was used to monitor the morphology of the ice using the Ssingle bondH stretching vibration, a characteristic vibration of thiol molecules. The deposited sample was able to switch between amorphous and crystalline phases repeatedly under temperature cycles between 10 K and 130 K with subsequent loss of molecules in every phase change. Such an effect is dependent upon the original thickness of the ice. Further work on quantitative analysis is to be carried out in due course whereas here we are reporting the first results obtained

Percutaneous trigger thumb release: a safe push-pull technique

Background: Stenosing tenosynovitis of the thumb is an inflammation of flexor tendon sheath of A1 pulley. Percutaneous release has recently gained popularity. Successful percutaneous release depends upon proper prediction of the location of the A1 pulley and circumventing injury to the neurovascular bundles. The aim of this study was to determine the safety of percutaneous release of trigger thumb.Methods: Twenty eight patients were included in the study between 2015 and 2018. All the patients were percutaneously released using push-pull technique. Steroid injection was given following the release. Quinnell grading, patient questionnaire and visual analogue scale score was used to assess the patients at 2 weeks, 6 weeks and 6 months and 1 year.Results: Satisfactory results were found in 93% of patients. Two patients complained of pain and swelling till third week. No digital nerve injury occurred in any patients.Conclusions: Percutaneous trigger thumb release using this push-pull technique is a simple and a safe technique with very minimal complications.

Spatial Structures in a Generalized Ginzburg-Landau Free Energy

Searching for characteristic signatures of a higher order phase transition (specifically of order three or four), we have calculated the spatial profiles and the energies of a spatially varying order parameter in one dimension. In the case of a $p^{th}$ order phase transition to a superconducting ground state, the free energy density depends on temperature as $a^p$, where $a = a_o(1-T/T_c)$ is the reduced temperature. The energy of a domain wall between two degenerate ground states is $\epsilon_p \simeq a^{p-1/2}$. We have also investigated the effects of a supercurrent in a narrow wire. These effects are limited by a critical current which has a temperature dependence $J_c(T) \simeq a^{(2p-1)/2}$. The phase slip center profiles and their energies are also calculated. Given the suggestion that the superconducting transtion in \bkbox, for $x = 0.4$, may be of order four, these predictions have relevance for future experiments.Comment: 7 pages, 5 figure

Unusual medial tibial plateau fracture fixation using dual plating

Background: Medial tibial plateau fractures is a subtype of proximal tibial fractures that involve the articular surface and can present in several distinct patterns. Purpose of this study was to assess the clinical outcome of stabilizing these biplanar medial tibial plateau fractures using dual plating technique through a single incision.Methods: Between 2017 to 2019, 12 men and 8 women with closed medial tibial plateau fracture who underwent reconstruction using two plates through a posteromedial approach were included in the study group. The fractures were classified using the three column concept of Lou.Results: One patient had an articular step off that was unacceptable and two patients had an acceptable articular step off. Functional assessment was done using the objective scoring of Oxford knee score criteria and radiological assessment was done using the Rasmussen modified score.Conclusions: Biplanar reconstruction using dual plates is a reliable and safe technique to reconstruct complex medial tibial plateau fractures