Effect of aquo-organic solvents on the aggregation of hydroxyethyl-based dimeric surfactants

The self-assembly behavior of Gemini surfactants i.e. alkanediyl-α,α-bis(hydroxyethylmethylhexadecylammonium bromide) (16-s-16 MEA, 2Br − ; s = 4 and 6) was investigated in pure water and in water–organic mixtures (10 and 20 % v/v) of acetonitrile (ACN), dimethyl sulfoxide (DMSO), and dimethylformamide (DMF) by conducticty and surface tension method at 300–320 K. The critical micelle concentration (CMC), degree of micellar ionization ( α ), surface excess concentration ( Γ max ), minimum molecular area at the interface (A min ), surface pressure at the CMC ( π CMC ), and thermodynamic parameters i.e. standard Gibbs free energies of micellization ( ΔG ° m ), Gibbs free energy of adsorption ( ΔG ° ads ), Gibbs free energy of transfer ( ΔG ° trans ), standard Gibbs free energy of micellization per mole of surfactant monomer ( ΔG ° tail ), enthalpy ( ΔH ° m ), and entropy ( ΔS ° m ), of micellization of the Gemini surfactant have also been determined. The CMC value increases with increasing spacer of Gemini surfactant (16-4-16, MEA 2Br − < 16-6-16, MEA 2Br − ), volume percentage of solvents and temperatures. Acetonitrile shows the higher CMC values as compare to other solvents. The surface excess concentration value increases with inceasing volume perentage of solvents. The negative free energy of adsorption shows a greater propensity for adsorption at the air-solution interface than for micellization.

Drivers of Variation in Health Care Spending Across US Counties

The Digital Revolution in Healthcare

Diagnostic Challenge: The Case of a 70‐Year‐Old Man Who Presents With Progressive Vision Loss and Headaches

ABSTRACT A 70‐year‐old presents with 6 weeks of progressive bilateral vision loss and headaches. He was also recently treated for presumed sciatica. His exam on admission is notable for poor visual acuity (no light perception), optic nerve atrophy bilaterally with swelling and disc hemorrhage on the left eye and left foot drop. MRI orbits reveals diffusion restriction and enhancement of bilateral optic nerves extending into the optic chiasm. He undergoes bilateral temporal artery biopsy due to concern for giant cell arteritis and high‐dose steroids with no improvement in vision and both biopsies are normal. Ultimately, full neuro‐axis imaging reveals evidence of leptomeningeal enhancement of the cerebellum, cervical and thoracic spine, and cauda equina nerve roots, as well as bilateral posterior semicircular canal enhancement and developing hydrocephalus. A CNS diagnosis is made via lumbar puncture, though ultimately the patient eventually expires in the hospital.

An Adaptive Learning Rate Based Novel Recurrent Neural Network Modeling and Control of Complex Non‐Linear Dynamical Systems

ABSTRACT A Double Internal Loop Recurrent Neural Network (DILRNN) with an adaptive learning rate is proposed for the modeling and control of non‐linear dynamical plants. The structure of DILRNN is an alteration of the Fully Connected Recurrent Neural Network (FCRNN). DILRNN contains three feedback loops taken primarily from the context layer to the hidden layer, the time delay of the output layer to the hidden layer, and the time delay of output to output. The parameters of DILRNN are updated using the gradient descent‐based dynamic Back‐Propagation (BP) algorithm. The Adaptive Learning Rate (ALR) scheme is implemented to ensure that the learning rate value is determined properly in each iteration and improves the performance of the learning algorithm. The effectiveness of the suggested strategy is assessed by considering both the Multiple Input Single Output (MISO) and Multiple Input Multiple Output (MIMO) systems and comparing them with state‐of‐the‐art methods. The simulation outcomes show that the proposed model outperforms the Feed Forward Neural Network (FFNN) and other Recurrent Neural Network (RNN) models, which were taken into evaluation in terms of their output and error. Next, a DILRNN controller is implemented using the proposed model to control non‐linear dynamical systems. The controller's response is evaluated both in the absence and presence of a disturbance signal to assess the recovery capability of the controller. The response and error of the proposed controller are compared with other neural network controllers and elementary PID controllers.

Optimized Heat Treatment for Electron Beam Powder Bed Fusion Processed IN718: Correlating Microstructure, Texture, and Mechanical Properties

This study investigates the microstructure and mechanical properties of Inconel 718 (IN718) manufactured via electron beam melting (EBM). The EBM‐processed IN718 exhibits a unique grain structure with columnar grains along the build direction (BD) and equiaxed grains perpendicular to it. Contrary to typical solidification textures, the strongest texture intensities are observed for (110) and (111) orientations, attributed to in situ δ phase precipitation during high‐temperature processing. The microstructure notably lacks cellular structures common in additively manufactured materials, instead featuring δ phase formed through in‐situ aging. A tailored heat treatment strategy is developed to control δ phase precipitation at grain boundaries, mitigating grain boundary sliding (GBS). This treatment results in <100> texture and large columnar grains, leading to a twofold increase in yield strength compared to the as‐printed (AP) condition. Interestingly, the AP EBM IN718 shows no signs of dynamic strain aging (DSA), distinguishing it from conventionally processed IN718. This comprehensive analysis of microstructure, texture, and mechanical behavior provides valuable insights for optimizing EBM processing and heat treatment of IN718 for enhanced performance in high‐temperature applications.

Superior Shock Resistance of Magnesium and Magnesium–Aluminum Alloys with Cerium Addition

This study investigates the shock response of forged and annealed commercially pure magnesium (Cp – Mg) and its cerium (Ce)‐alloyed variants (Mg – 0.5Ce and Mg – 3Al – 0.5Ce). Shock loading is performed using a conventional shock tube setup at two pressure levels along the forging direction (FD). Under low‐pressure conditions, all materials deform without fracturing, with Cp – Mg exhibiting the highest deflection. However, at higher pressure, Cp – Mg discs fracture, displaying brittle cleavage, whereas Mg – 0.5Ce and Mg – 3Al – 0.5Ce absorb impact energy without failure due to their superior strength–ductility balance. Among the Ce‐alloyed variants, Mg – 3Al – 0.5Ce demonstrates slightly better shock resistance, exhibiting lower deflection and effective strain. Shock loading does not alter the grain size but results in a high density of predominantly extension twins that complements slip activity in all materials, particularly at higher pressures and in Cp – Mg. Post‐shock analysis reveals the greatest reduction in basal texture intensity in Cp – Mg, while Mg – 0.5Ce and Mg – 3Al – 0.5Ce show a moderate decrease. This reduction is attributed to slip and twinning, with Cp – Mg displaying the highest twinning activity. Local misorientation analysis indicates strain localization and stress concentrations at twin–matrix interfaces. Overall, Mg – 0.5Ce and Mg – 3Al – 0.5Ce exhibit superior shock resistance compared to Cp – Mg, owing to their higher toughness, lower twin density, and increased non‐basal slip activity.

Flower‐Like Polyaniline‐Modified Yttrium Phosphate Nanocomposite: An Effective Adsorbent for Cr(VI) Removal via Adsorption–Reduction Mechanism

In this study, flower‐like polyaniline‐modified yttrium phosphate (PANI‐YPO 4 ) nanocomposites are investigated as a promising adsorbent for removing hexavalent chromium (Cr(VI)) from both wastewater as well as aqueous solutions. The PANI‐YPO 4 nanocomposite is synthesized using an in situ oxidative polymerization method followed by hydrothermal synthesis of yttrium phosphate. Morphological analysis by field emission scanning electron microscopy and transmission electron microscopy reveals a flower‐like structure of the nanocomposite. The PANI‐YPO 4 nanocomposite shows the highest removal percentage of 99.1% toward Cr(VI) in a wide pH range of 2–5, with a 0.4 g L −1 adsorbent dose, 10 ppm initial concentration, and a 60‐minute equilibrium time as compared to sole yttrium phosphate (53.7%) and polyaniline (69.8%). The Langmuir maximum adsorption capacity for Cr(VI) removal by PANI‐YPO 4 is 91.0 mg g −1 . Moreover, the nanocomposite shows successful regeneration and reuse for up to five cycles with 85% removal efficiency. The proposed adsorption mechanism involves the electrostatic interaction between Cr(VI) and the PANI‐YPO 4 nanocomposite, accompanied by the in situ chemical reduction of Cr(VI) to Cr(III). Additionally, the PANI‐YPO 4 nanocomposite exhibits an impressive adsorption efficiency of 99% for real chromium wastewater solutions. Thus, the PANI‐YPO 4 nanocomposite is a promising material for efficiently removing Cr(VI) from contaminated water sources, emphasizing its potential for future environmental remediation applications.

Understanding the Mechanochemical Effect of High‐Pressure Torsion on AA2195–0.025 wt% Sc Alloy

The severe plastic strain‐induced mechanochemical alterations in a AA2195‐0.025Sc alloy is experimentally investigated. The alloy is subjected to high‐pressure torsion (HPT) processing at room temperature. Microstructural and microchemistry evolution is systematically characterized by scanning electron microscopy, transmission electron microscopy, and atom probe tomography techniques. Precipitate dissolution (Al 3 (LiScZr) and Al 2 Cu precipitates) and grain fragmentation occurs at an onset strain of 1.0 and continues till strain 4 resulting in disappearance of precipitates and appearance of high segregation at grain boundaries. Thereafter, at higher strains, the segregated solutes form nanoclusters at grain boundaries, triple junctions and HPT‐induced vacancy cluster sites. Diffusion calculations are performed to account for the experimentally observed changes in precipitate state by evaluating the increased atomic mobility of solutes (Li, Sc, and Zr) by HPT‐induced vacancies, dislocations, and grain boundaries. Enhanced atomic mobility of Li can be attributed to the high density of vacancies, dislocations, and grain boundaries, whereas solute drag by moving grain boundaries result in enhanced diffusion of Sc and Zr. The increase in Sc and decrease in Zr in the reprecipitated phases could be attributed to the rapid diffusion of Sc along grain boundaries along with trapping of Zr at grain boundaries.

Investigation of Iron‐Aluminide‐Like Phase Composition in Complex Concentrated Fe 32 Cu 12 Ni 11 Ti 16 Al 29 Alloy

Complex‐concentrated alloys based on the combination of the 3d transition elements and aluminum are promising candidates for future lightweight high‐temperature applications. However, the thermodynamically driven phase composition of these alloys has not been clearly understood, leading to conflicting results. In this work, investigations on theFe 32Cu 12Ni 11Ti 16Al 29$\text{Fe}_{32} \text{Cu}_{12} \text{Ni}_{11} \text{Ti}_{16} \text{Al}_{29}$ alloy are carried out with an emphasis on identifying the crystal structure(s). The microstructure and crystal structures are studied using a combination of scanning electron microscopy and X‐Ray diffraction. The alloy possesses a two‐phase microstructure with a Fe‐rich matrix and Cu‐rich precipitates after aging heat treatment. The matrix is found to possess theL 2 1 $\text{L} 2_{1}$ crystal structure in combination withCu 3 Al $\text{Cu}_{3} \text{Al}$ precipitates, having a characteristic A2 structure. The phase fractions, precipitate size, and morphology are studied using quantitative microscopy. The thermodynamic origin of the phase composition is explained by using the results from binary and ternary subsystems and the Miedema's model for binary interactions. Finally, an overaging phenomenon in the studied alloy system is correlated in terms of microhardness measurements.