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Currently, the photovoltaic industry is playing a huge role and growing rapidly. Carbon etching and silicide deposition are common phenomena in furnaces during photovoltaic crystal pulling processes, both of which shorten the service life of graphite components and pollute silicon-based materials; these processes also generate waste graphite components with SiC. Therefore, studying its generation mechanism can help conserve and reuse graphite components in furnaces. This study investigated took photovoltaic crystal pulling waste graphite infusion cylinders used during photovoltaic crystal pulling with significantly different apparent morphologies as the research object. Through systematic characterization and thermodynamic analysis, we investigated the physical and chemical reactions occurring during the generation of SiC in various regions of a discarded graphite infusion cylinder. We derived the SiC delamination, infiltration, and stacking mechanism to explain the formation of the apparent morphological characteristics of the waste graphite infusion cylinder. The generation mechanism of SiC in graphite infusion cylinders during photovoltaic crystal pulling was described to provide suggestions for prolonging the service life of graphite infusion cylinders and treating waste graphite infusion cylinders.

PurposeThe purpose of this study is to propose an innovative methodology in solving the lean production design from semiconductor crystal-ingot pulling manufacturing which is an important industry. Due to the complexity of the system, it is computationally prohibited by an analytical approach; thus, simulation optimization is adopted for this study.Design/methodology/approachFour control factors that affect the system’s performance, including the pulling strategy, machine limitations, dispatching rules and batch-size control, are identified to generate the future-state value stream mapping. Taguchi two-step procedure and simulation optimization are used to determine the optimal parameter values for a robust system.FindingsThe proposed methodology improved the system performances by 6.42 and 12.02 per cent for service level and throughput, respectively.Research limitations/implicationsThis study does not investigate operations management issues such as setup reduction, demand forecasting and layout design.Practical implicationsA real-world crystal-ingot pulling manufacturing factory was used for the case study. The results are promising and are readily applied to other industrial applications.Social implicationsThe improved performances, service level and throughout rate, can result in an improved customer satisfaction level and a reduced resources consumption, respectively.Originality/valueThe proposed methodology innovatively solved a practical application and the results are promising.

Experimental studies on the solidification of ammonium-chloride-water alloys in relatively large containments reveal conditions that lead to the formation of numerous crystal avalanches. Columnar segments that occasionally slide downwards along a vertical mushy zone further fragmentate and so crystal multiplication occurs. As a condition for this phenomenon solidification-induced solutal buoyancy that leads to a rising interdendritic flow was identified for the present case. The interaction with sedimentation-induced downward flow ahead of a vertical columnar region results in a redirection of the interdendritic flow and thus, to local conditions that slow down further solidification or even lead to remelting. Gravity is then pulling loose segments downwards. In larger containment, the flow in the bulk melt is generally unsteady and even turbulent. Thus, the outlined flow-solidification/melting interplay happens frequently at numerous positions but in a stochastic manner.

The search for unconventional superconductivity has been focused on materials with strong spin-orbit coupling and unique crystal lattices. Doped bismuth selenide (Bi2Se3 ) is a strong candidate, given the topological insulator nature of the parent compound and its triangular lattice. The coupling between the physical properties in the superconducting state and its underlying crystal symmetry is a crucial test for unconventional superconductivity. In this paper, we report direct evidence that the superconducting magnetic response couples strongly to the underlying trigonal crystal symmetry in the recently discovered superconductor with trigonal crystal structure, niobium (Nb)-doped Bi2Se3 . As a result, the in-plane magnetic torque signal vanishes every 60°. More importantly, the superconducting hysteresis loop amplitude is enhanced along one preferred direction, spontaneously breaking the rotational symmetry. This observation indicates the presence of nematic order in the superconducting ground state of Nb-doped Bi2Se3 .

We report on the spectroscopic and laser properties of a Tm,Ho:GSAG (gadolinium scandium aluminium garnet) crystal which was grown by the micro-pulling-down (µ-PD) method. The crystal, doped with 4 at.% of Tm3+ and 0.75 at.% of Ho3+, was characterized under diode pumping at 782 nm and 1688 nm, corresponding to both possible thulium excitation schemes. In the pulsed regime, slope efficiencies up to 27.8% (with 1688 nm pumping) were achieved, with maximum output power up to 170 mW. Continuous-wave lasing at 2.1 µm was also demonstrated for this pumping, reaching 151 mW output power with a slope efficiency of 12%. Using a birefringent filter, a broad tuning range of up to 138 nm was obtained. These findings confirm µ-PD grown Tm,Ho:GSAG as a promising gain medium for compact, efficient, and tunable solid-state lasers emitting radiation around 2.1 µm.

In this paper, the influence of withdraw speed on the directional solidification structure of the single crystal blade was studied. The influence of 2.7 mm/min, 5.4 mm/min, and 9.5 mm/min drawing speed on temperature field, temperature gradient, and microstructure were analyzed. The results show that as the casting speed increases, the temperature gradient G decreases, the degree of downward depression of the temperature field also increases, and more stray grains appear at the single crystal blade platform. In addition, it is also found that the increase in the withdrawal speed helps to reduce the secondary dendrite arm spacing and refine the grains. This paper provides a theoretical basis for optimizing the directional solidification process of single crystal blades.

Guanine-rich nucleic acid sequences challenge the replication, transcription, and translation machinery by spontaneously folding into G-quadruplexes, the unfolding of which requires forces greater than most polymerases can exert 1 , 2 . Eukaryotic cells contain numerous helicases that can unfold G-quadruplexes 3 . The molecular basis of the recognition and unfolding of G-quadruplexes by helicases remains poorly understood. DHX36 (also known as RHAU and G4R1), a member of the DEAH/RHA family of helicases, binds both DNA and RNA G-quadruplexes with extremely high affinity 4 – 6 , is consistently found bound to G-quadruplexes in cells 7 , 8 , and is a major source of G-quadruplex unfolding activity in HeLa cell lysates 6 . DHX36 is a multi-functional helicase that has been implicated in G-quadruplex-mediated transcriptional and post-transcriptional regulation, and is essential for heart development, haematopoiesis, and embryogenesis in mice 9 – 12 . Here we report the co-crystal structure of bovine DHX36 bound to a DNA with a G-quadruplex and a 3′ single-stranded DNA segment. We show that the N-terminal DHX36-specific motif folds into a DNA-binding-induced α-helix that, together with the OB-fold-like subdomain, selectively binds parallel G-quadruplexes. Comparison with unliganded and ATP-analogue-bound DHX36 structures, together with single-molecule fluorescence resonance energy transfer (FRET) analysis, suggests that G-quadruplex binding alone induces rearrangements of the helicase core; by pulling on the single-stranded DNA tail, these rearrangements drive G-quadruplex unfolding one residue at a time. A mechanism for the unfolding of guanine-rich DNA ‘quadruplexes’ by helicases is suggested, based on the structure of a DNA-bound helicase.

Single crystals of Y3(Ga,Al)5O12:Ce(YAGG:Ce) co-doped with various Mg were grown by the micro-pulling-down method, focusing on the Ga2Al3 and Ga3Al2 compositions. The scintillation properties were systematically investigated as a function of Mg concentration. The results revealed that Mg co-doping strongly influenced both the light yield and the scintillation decay time. In particular, Y3Ga3Al2O12:Ce0.33at%,Mg0.033at% exhibited the highest light yield of 44,300 photons/MeV, comparable to that of Gd3Ga3Al2O12:Ce (GAGG:Ce) (46,000 photons/MeV), while maintaining a fast scintillation decay time of approximately 49 ns. In contrast, higher Mg concentration (0.2at%) led to a deterioration in both light yield and decay characteristics, suggesting the activation of non-radiative processes. For Y3Ga2Al3O12, the light yield was generally lower than that of Y3Ga3Al2O12, although low level Mg co-doping still improved performance compared with non-doped samples. These findings demonstrate that the optimal Mg concentration enables the simultaneous enhancement of light yield and reduction of scintillation decay time, and that Ga3Al2 compositions are more favorable than Ga2Al3 under low Mg doping. This study provides the first systematic evaluation of Mg co-doping dependence in YAGG and highlights its potential as a promising scintillator material for next-generation photon-counting computed tomography (PCCT). The results not only identify optimal compositions for improved scintillation performance but also provide a foundation for further optimization, including investigations of broader Mg concentrations, alternative alkaline-earth dopants, and the underlying mechanisms governing co-doping effects.

Crystals can be found in many shapes but do not usually grow as spirals. Here we show that applying a non-uniform layer of a polymer blend onto slender centimeter-size organic crystals prestrains the crystals into hybrid dynamic elements with spiral shapes that respond reversibly to environmental variations in temperature or humidity by curling. Exposure to humidity results in partial uncurling within several seconds, whereby a logarithmic-type spiral crystal is transformed into an Archimedean one. Conical helices obtained by lateral pulling of the spirals can wind around solid objects similar to plant tendrils or lift suspended objects with a positive correlation between the actuator’s elongation and the cargo mass. The morphological, kinematic, and kinetic attributes turn these hybrid materials into an attractive platform for flexible sensors and soft robots, while they also provide an approach to morph crystalline fibers in non-natural spiral habits inaccessible with the common crystallization approaches. The growth of crystals as spirals is unusual and this morphology can be applied to the development of flexible sensors and soft robots when the crystals respond to external stimuli. Here, the authors report the incorporation of a non-uniform layer of a polymer blend onto slender centimeter-size organic crystals to produce crystals having spiral shapes that respond reversibly to environmental variations.

The Czochralski (Cz) process is a crucial method for producing high-quality single-crystal silicon for semiconductor applications. This study introduces a Monte Carlo-finite element (MC-FE) optimization model to enhance Cz puller performance by refining five key parameters: crystal rotation speed, crucible rotation speed, insulation thermal conductivity, melt level, and thermal gap. A finite element model has been developed to incorporate conduction, convection, and radiation heat transfer, with a segregated solver employed to simulate silicon ingot growth. The MC-FE optimization reduced the objective function from 1.0 to 0.13 with an 87% improvement, achieving a flatter crystal front with maximum deflection decreasing from − 36.0 to − 10.4 mm. The optimized process increased the melt temperature from 1442 to 1517 °C at a 10 mm crystal length, enhancing thermal gradient stability. The V / G ratio, important for defect minimization, was flattened from a steep drop of 0.205 to 0.098 mm/min·K to a more uniform 0.185 to 0.158 mm/min·K range. Optimized parameters, including an increased crystal rotation speed of 9 RPM and a reduced thermal gap of 10 mm, contributed to a well-defined hot–cold thermal zone separation that supports stable crystal growth. These findings demonstrate the effectiveness of MC-FE optimization in improving the efficiency and quality of large-scale silicon crystal growth in semiconductor manufacturing.