This study presents a sustainable surface engineering approach aimed at extending the service life and enabling the restoration of worn 42Cr4 steel components within a circular manufacturing framework. Wear-induced surface degradation is a primary failure mechanism in mechanical systems, leading to increased maintenance costs, energy losses, and excessive consumption of raw materials. In this work, the surface of 42Cr4 steel was modified by Tungsten Inert Gas (TIG) surface remelting assisted by a high-frequency magnetic field. Unlike conventional TIG treatments and post-process magnetic field applications, the proposed method applies the magnetic field in situ during remelting, enabling real-time control of molten pool dynamics. The tribological performance of the treated specimens was evaluated using a ball-on-disc configuration under paraffin lubrication, and friction and wear behavior were systematically quantified. The results indicate that magnetically assisted TIG remelting significantly enhances surface hardness and tribological performance. These improvements are attributed to intensified electromagnetic stirring within the molten pool, which promotes grain refinement, reduces porosity, and ensures a uniform distribution of alloying elements in the remelted layer. As a result, the treated surfaces exhibit improved load-bearing capacity and enhanced resistance to wear under lubricated sliding conditions. From an application perspective, the proposed hybrid process provides an effective and scalable solution for component repair and surface regeneration. Restoring functional surfaces without full component replacement offers clear environmental and economic advantages. In addition, localized surface treatment significantly reduces material consumption and energy demand, thereby supporting resource-efficient and circular economy strategies.

Microfluidic systems enable precise control of fluids at the microscale, yet most are designed without consideration of reuse, cleanability, or material sustainability, leading to short device lifetimes and increased waste. Among microfluidic systems, microdroplet generators represent a particularly stringent test case for reusability due to their narrow channels, sensitivity to surface contamination, and widespread use across chemical, biological, and materials processing. Here, we present a scalable and cost-effective microfluidic platform designed explicitly for reuse, demonstrated using a flow-focusing microdroplet generator as a proof of concept. Mass-manufactured microchannel networks are integrated into a reusable housing composed of mechanically compressed polycarbonate and silicone layers, enabling uniform sealing, robust leak-free operation, and rapid disassembly for cleaning. The modular housing supports component-level replacement rather than full device disposal and allows individual microchannel networks to be reused across multiple operational cycles with minimal impact on performance. To demonstrate recoverability under conditions that would conventionally necessitate device disposal, we examine droplet generation using a high-fouling agar dispersed phase during controlled cooling to the point of gelation, where blockages can be readily cleared and the system reused. These results establish a reusable, mass-manufacturable microfluidic platform that applies circular design principles to microscale fluid handling.

The crystal structure of valganciclovir hydrochloride has been solved and refined using synchrotron X-ray powder diffraction data, and optimized using density functional theory techniques. Valganciclovir hydrochloride crystallizes in space group P212121 (#19) with a = 7.07758(23), b = 11.34599(27), c = 49.3041(22) Å, V = 3,959.22(22) Å3, and Z = 8. Solution and refinement of the structure were made difficult by the limited data range, the relatively large size of the structure, the broad diffraction peaks, the relatively low crystallinity, and the significant preferred orientation. The two independent cations are protonated at the N atoms of the valine side chains. The crystal structure is dominated by alternating layers of ring systems and protonated side chains/anions along the c-axis. In addition to the ammonium–Cl hydrogen bonds, the ring systems and side chains are linked into a three-dimensional network by hydrogen bonds. The two independent cations have very different conformations. N–H···Cl, N–H···O, O–H···N, O–H···O, and O–H···Cl, as well as C–H···Cl, C–H···N, and C–H···O hydrogen bonds, are prominent in the structure. The powder pattern is included in the Powder Diffraction File™ (PDF®) as entry 00-071-1641.

High-energy mixing offers a novel approach to enhancing the efficiency of Portland cements that incorporate supplementary cementitious materials regarding the hydration time and compressive strength formation. This research focused on monitoring the formation and degradation of mineral phases, as well as the compressive strength development and heat flow of mortars, within the first 48 hours, using clinker-efficient Portland composite cements. This study involved mixing Portland cement containing 20 wt% amorphous blast furnace slag and 10 wt% limestone with water using three different high-energy mixing techniques. The results demonstrated that the compressive strength of the Portland composite cements was comparable to that of ordinary Portland cement within a 48-hour period. Rietveld refinement was employed to track the formation of portlandite and the sum of the amorphous phases quartz and tobermorite, as well as the degradation of tricalcium silicate. The decline in tricalcium silicate and the formation of Portlandite showed a significant increase in reaction speed due to high-energy mixing. Additionally, a reduction in calcite content was observed, suggesting that calcium carbonate contributes to the enhanced compressive strength observed within the first 48 hours.

The leucite group structures are tetrahedrally coordinated silicate framework structures with some of the silicate framework cations partially replaced by divalent or trivalent cations. These structures have general formulae A2BSi5O12 and ACSi2O6, where A is a monovalent alkali metal cation, B is a divalent cation, and C is a trivalent cation. These leucites can have crystal structures in several different space groups, dependent on stoichiometry, synthesis conditions, and temperature. Phase transitions are known for temperature changes. This paper reports a high-temperature X-ray powder diffraction study on RbGaSi2O6, which shows a phase transition from I41/a tetragonal to Iad cubic on heating from room temperature to 733 K. On cooling to room temperature, the crystal structure reverts to I41/a tetragonal.

The crystal structures of two arylcyclohexylamine derivatives – methoxmetamine·HCl (2-(3-methoxyphenyl)-2-(methylamino)cyclohexan-1-one hydrochloride, MMXE·HCl) and methoxetamine·HCl (2-(ethylamino)-2-(3-methoxyphenyl)cyclohexan-1-one hydrochloride, MXE·HCl) – have been determined using laboratory X-ray powder diffraction data contained in the Powder Diffraction File™. MMXE·HCl and MXE·HCl exhibit anesthetic and sedative effects and have been illicitly used as recreational drugs due to their dissociative hallucinogenic and euphoriant effects. The structure determination of MMXE·HCl and MXE·HCl was carried out with DASH, and the Rietveld refinements were performed with TOPAS Academic in monoclinic unit cells. The parameters obtained for MMXE·HCl were a = 15.0429(5) Å, b = 14.0721(5) Å, c = 6.5716(2) Å, β = 90.9864(14)°, and V = 1,390.91(8) Å3, with Z = 4 and space group P21/n. The parameters obtained for MXE·HCl were a = 8.7772(5) Å, b = 9.9528(7) Å, c = 8.5841(6) Å, β = 100.276(3)°, and V = 737.86(8) Å3, with Z = 2 and space group P21. The structures were validated by dispersion-corrected DFT calculations. Hirshfeld surface analysis and fingerprint plots calculations are also reported.

CrFeCoNi high-entropy alloy (HEA) powder with an equimolar composition was produced via gas atomization and applied as a coating using the cold-spray technique. X-ray diffraction patterns were analyzed to characterize the microstructure of the raw HEA powder and cold-sprayed coatings using Rietveld refinement methods. The HEA powders exhibited a single-phase face-centered cubic crystal structure with a lattice parameter of 0.357349(1) nm, a low microstrain of 4.3(0.17) × 10−4, and a crystallite size of 225(8) nm, attributed to the rapid cooling during atomization. In contrast, the cold-sprayed coatings exhibited broadened diffraction peaks, with a reduced crystallite size of 67.9(1.2) nm and an increased microstrain of 2.2(0.23) × 10−3, showing crystallite size refinement and an increase in the density of crystalline defects due to severe plastic deformation during deposition. Additional microstructural analysis revealed texture in the {200} plane and intrinsic stacking fault probabilities increasing to 4.4(0.21) × 10−3. These findings highlight microstructural changes produced by the cold-spray process. This study provides valuable insights into optimizing cold-spray parameters and tailoring HEA properties for industrial applications.