Stokes vector measurement based on snapshot polarization-sensitive spectral interferometry.

This paper describes a Stokes vector measurement method based on a snapshot polarization-sensitive spectral interferometry. We measure perpendicular linearly polarized complex wave information of an anisotropic object in the spectral domain from which an accurate Stokes vector can be extracted. The proposed Stokes vector measurement method is robust to the object plane 3-D pose variation and external noise, and it provides a reliable snapshot solution in numerous spectral polarization-related applications.

Polymorphism of GeSbTe superlattice nanowires.

Scaling-down of phase change materials to a nanowire (NW) geometry is critical to a fast switching speed of nonvolatile memory devices. Herein, we report novel composition-phase-tuned GeSbTe NWs, synthesized by a chemical vapor transport method, which guarantees promising applications in the field of nanoscale electric devices. As the Sb content increased, they showed a distinctive rhombohedral-cubic-rhombohedral phase evolution. Remarkable superlattice structures were identified for the Ge(8)Sb(2)Te(11), Ge(3)Sb(2)Te(6), Ge(3)Sb(8)Te(6), and Ge(2)Sb(7)Te(4) NWs. The coexisting cubic-rhombohedral phase Ge(3)Sb(2)Te(6) NWs exhibited an exclusively uniform superlattice structure consisting of 2.2 nm period slabs. The rhombohedral phase Ge(3)Sb(8)Te(6) and Ge(2)Sb(7)Te(4) NWs adopted an innovative structure; 3Sb(2) layers intercalated the Ge(3)Sb(2)Te(6) and Ge(2)Sb(1)Te(4) domains, respectively, producing 3.4 and 2.7 nm period slabs. The current-voltage measurement of the individual NW revealed that the vacancy layers of Ge(8)Sb(2)Te(11) and Ge(3)Sb(2)Te(6) decreased the electrical conductivity.

Multi-Load Topology Optimization Design for the Structural Safety Maintenance of Low- and Intermediate-Level Radioactive Waste Packaging Containers in the Case of a Collision.

This paper presents an optimized design approach using nonlinear dynamic analysis and finite element methods to ensure the structural integrity of square-shaped containers made from ductile cast iron for intermediate- and low-level radioactive waste packaging. Ductile cast iron, with its spherical graphite structure, effectively distributes stress throughout the material, leading to a storage capacity increase of approximately 18%. Considering the critical need for containers that maintain integrity under extreme conditions like earthquakes, the design focuses on mitigating stress concentrations at the corners of square structures. Nonlinear dynamic analyses were conducted in five drop directions: three specified by ASTM-D5276 standards and two additional directions to account for different load patterns. Fractures were observed in four out of the five scenarios. For each direction where fractures occurred, equivalent loads causing similar displacement fields were applied to linear static models, which were then used for multi-load topology optimization. Three optimized models were derived, each increasing the volume by 1.4% to 1.6% compared to the original model, and the design that best met the structural integrity requirements during drop scenarios was selected. To further enhance the optimization process, weights were assigned to different load conditions based on numerical analysis results, balancing the impact of maximum stress, average stress, and plastic deformation energy. The final model, with its increased storage capacity and enhanced structural integrity, offers a practical solution for radioactive waste management, overcoming limitations in previous designs by effectively addressing complex load conditions.

Hydrogen and carbon monoxide generation from laser-induced graphitized nanodiamonds in water.

Nanodiamonds (ND) were found to generate hydrogen (H2) and carbon monoxide (CO) from water at a remarkable rate under pulsed laser (532 nm) irradiation. The transformation of diamond structure into graphitic layers takes place to form an onion-like carbon structure. The CO generation suggests the oxidative degradation reaction of graphitic layers, C + H2O → CO + 2H(+) + 2e(-), which produced a unique laser-induced reaction: C + H2O → CO + H2. Au, Pt, Pd, Ag, and Cu nanoparticles on the ND enhance both gas evolution rates (~2 times for Au) and graphitization and, specifically, Au was found to be the most efficient amongst other nanoparticles. The enhancement effect was ascribed to effective charge separation between the metal nanoparticles and ND. The Au-ND hybrid on the reduced graphene oxide produced consistently a greater photocurrent than the ND upon visible light irradiation.

Germanium-tin alloy nanocrystals for high-performance lithium ion batteries.

Germanium-tin (Ge(1-x)Sn(x)) alloy nanocrystals were synthesized using a gas-phase laser photolysis reaction of tetramethyl germanium and tetramethyl tin. A composition tuning was achieved using the partial pressure of precursors in a closed reactor. For x < 0.1, cubic phase alloy nanocrystals were exclusively produced without separation of the tetragonal phase Sn metal. In the range of x = 0.1-0.4, unique Ge(1-x)Sn(x)-Sn alloy-metal hetero-junction nanocrystals were synthesized, where the Sn metal domain becomes dominant with x. Thin graphitic carbon layers usually sheathed the nanocrystals. We investigated the composition-dependent electrochemical properties of these nanocrystals as anode materials of lithium ion batteries. Incorporation of Sn (x = 0.05) significantly increased the capacities (1010 mA h g(-1) after 50 cycles) and rate capabilities, which promises excellent electrode materials for the development of high-performance lithium batteries.

Selection of Optimal Lower Instrumented Vertebra for Adolescent Idiopathic Scoliosis Surgery.

Adolescent idiopathic scoliosis (AIS) affects approximately 2% of adolescents across all ethnicities. The objectives of surgery for AIS are to halt curve progression, correct the deformity in 3 dimensions, and preserve as many mobile spinal segments as possible, avoiding junctional complications. Despite ongoing development in algorithms and classification systems for the surgical treatment of AIS, there is still considerable debate about selecting the appropriate fusion level. In this study, we review the literature on fusion selection and present current concepts regarding the lower instrumented vertebra in the selection of the fusion level for AIS surgery.

Sacropelvic Fixation for Adult Deformity Surgery Comparing Iliac Screw and Sacral 2 Alar-Iliac Screw Fixation: Systematic Review and Updated Meta-Analysis.

OBJECTIVE: Two commonly used techniques for spinopelvic fixation in adult deformity surgery are iliac screw (IS) and sacral 2 alar-iliac screw (S2AI) fixations. In this article, we systematically meta-analyzed the complications of sacropelvic fixation for adult deformity surgery comparing IS and S2AI. METHODS: The PubMed, Embase, Web of Science, and Cochrane clinical trial databases were systematically searched until March 29, 2023. The proportion of postoperative complications, including implant failure, revision, screw prominence, and wound complications after sacropelvic fixation, were pooled with a random-effects model. Subgroup analyses for the method of sacropelvic fixation were conducted. RESULTS: Ten studies with a total of 1,931 patients (IS, 925 patients; S2AI, 1,006 patients) were included. The pooled proportion of implant failure was not statistically different between the IS and S2AI groups (21.9% and 18.9%, respectively) (p = 0.59). However, revision was higher in the IS group (21.0%) than that in the S2AI group (8.5%) (p = 0.02). Additionally, screw prominence was higher in the IS group (9.6%) than that in the S2AI group (0.0%) (p < 0.01), and wound complication was also higher in the IS group (31.7%) than that in the S2AI group (3.9%) (p < 0.01). CONCLUSION: IS and S2AI fixations showed that both techniques had similar outcomes in terms of implant failure. However, S2AI was revealed to have better outcomes than IS in terms of revision, screw prominence, and wound complications.

The Effect of Boron (B) and Copper (Cu) on the Microstructure and Graphite Morphology of Spheroidal Graphite Cast Iron.

This study examines the impacts of copper and boron in parts per million (ppm) on the microstructure and mechanical properties of spheroidal graphite cast iron (SCI). Boron's inclusion increases the ferrite content whereas copper augments the stability of pearlite. The interaction between the two significantly influences the ferrite content. Differential scanning calorimetry (DSC) analysis indicates that boron alters the enthalpy change of the α + Fe3C → γ conversion and the α → γ conversion. Scanning electron microscope (SEM) analysis confirms the locations of copper and boron. Mechanical property assessments using a universal testing machine show that the inclusion of boron and copper decreases the tensile strength and yield strength of SCI, but simultaneously enhances elongation. Additionally, in SCI production, the utilization of copper-bearing scrap and trace amounts of boron-containing scrap metal, especially in the casting of ferritic nodular cast iron, offers potential for resource recycling. This highlights the importance of resource conservation and recycling in advancing sustainable manufacturing practices. These findings provide critical insights into the effects of boron and copper on SCI's behavior, contributing to the design and development of high-performance SCI materials.

Three-dimensional structure of twinned and zigzagged one-dimensional nanostructures using electron tomography.

Electron tomography and high-resolution transmission electron microscopy were used to characterize the unique three-dimensional (3D) structures of twinned Zn(3)P(2) (tetragonal) and InAs (zinc blende) nanowires synthesized by the vapor transport method. The Zn(3)P(2) nanowires adopt a unique superlattice structure that consists of twinned octahedral slice segments having alternating orientations along the axial [111] direction of a pseudo cubic unit cell. The apexes of the octahedral slice segment are indexed as six equivalent <112> directions at the [111] zone axis. At each 30 degrees turn, the straight and zigzagged morphologies appear repeatedly at the <112> and <011> zone axes, respectively. The 3D structure of the twinned Zn(3)P(2) nanowires is virtually the same as that of the twinned InAs nanowires. In addition, we analyzed the 3D structure of zigzagged CdO (rock salt) nanowires and found that they include hexahedral segments, whose six apexes are matched to the <011> directions, linked along the [111] axial direction. We also analyzed the unique 3D structure of rutile TiO(2) (tetragonal) nanobelts; at each 90 degrees turn, the straight morphology appears repeatedly, while the in-between twisted form appears at the [011] zone axis. We suggest that the TiO(2) nanobelts consist of twinned octahedral slices whose six apexes are indexed by the <011>/<001> directions with the axial [010] direction.

Geometry-dependent terahertz emission of silicon nanowires.

THz emission was observed from the vertically aligned silicon nanowire (Si NW) arrays, upon the excitation using a fs Ti-sapphire laser pulse (800 nm). The Si NWs (length = 0.3 approximately 9 microm) were synthesized by the chemical etching of n-type silicon substrates. The THz emission exhibits significant length dependence; the intensity increases sharply up to a length of 3 mum and then almost saturates. Their efficient THz emission is attributed to strong local field enhancement by coherent surface plasmons, with distinctive geometry dependence.

Room-temperature ferromagnetism and terahertz emission of Mn-doped InGaAs and GaAsSb nanowires.

Ferromagnetic Mn-doped In(0.05)Ga(0.95)As and GaAs(0.95)Sb(0.05) nanowires were synthesized by chemical vapor transport and their Mn concentration was about 2%. The Mn doped homogeneously into both the single-crystalline zinc blende InGaAs and GaAsSb without the formation of metal clusters. X-ray magnetic circular dichroism and magnetic moment measurements revealed their distinctive room-temperature ferromagnetic behaviors. While the incorporation of In enhances the ferromagnetism, that of Sb reduces it, which can be ascribed to the increase or decrease of the dopant-acceptor hybridization. These GaAs-based NWs exhibit an efficient terahertz emission at room temperature, due to a strong local field enhancement by coherent surface plasmons. The Mn doping significantly enhances the intensity and bandwidth of the terahertz emission, with an excellent correlation with their magnetization.

Identification of up-regulated genes in malignant glioma with subtraction hybridization: preliminary screening studies.

PURPOSE: This investigation is intended to obtain differentially expressed genes related to human malignant glioma using Subtractive hybridization. MATERIALS AND METHODS: Subtractive hybridization is potentially faster methods for identifying differentially expressed genes associated with a particular disease state. We identified 7 over-expressed genes which were not homologous to any of the known genes in the Genbank database. RESULTS: Using semi-quantitative reverse transcription-polymerase chain reaction (RT-PCR), the mRNA expression levels of these 7 genes were higher in human glioblastomas tissue than in non-tumor brain tissue. In order to learn more about the expression profile of these genes, RT-PCR was performed using various commercially available human carcinoma cell lines. Some of these new genes were over-expressed in human glioma cell line, but not the expressed in other human cancer cell line. CONCLUSION: Theses cloned new genes may play a role in brain tumorigenesis. Further studies including verification of oncogene, cancer protein, and glioblastoma induction in animal model are needed.

Dural arteriovenous fistula associated with meningioma: spontaneous disappearance after tumor removal.

A 45-year-old woman presented with a non-dominant transverse-sigmoid sinus dural arteriovenous fistula (AVF) associated with convexity meningioma on the same side. The dural AVF disappeared spontaneously after surgical removal of the meningioma, even though there was no manipulation of the dural AVF. Dural AVFs are usually acquired lesions, and may develop after trauma, surgery, and dural sinus thrombosis. Dural AVFs of the acquired origins are rarely associated with brain tumor. Dural AVFs associated with a tumor may develop even in the absence of sinus occlusion.

Phase evolution of tin nanocrystals in lithium ion batteries.

Sn-based nanostructures have emerged as promising alternative materials for commercial lithium-graphite anodes in lithium ion batteries (LIBs). However, there is limited information on their phase evolution during the discharge/charge cycles. In the present work, we comparatively investigated how the phases of Sn, tin sulfide (SnS), and tin oxide (SnO2) nanocrystals (NCs) changed during repeated lithiation/delithiation processes. All NCs were synthesized by a convenient gas-phase photolysis of tetramethyl tin. They showed excellent cycling performance with reversible capacities of 700 mAh/g for Sn, 880 mAh/g for SnS, and 540 mAh/g for SnO2 after 70 cycles. Tetragonal-phase Sn (ß-Sn) was produced upon lithiation of SnS and SnO2 NCs. Remarkably, a cubic phase of diamond-type Sn (α-Sn) coexisting with ß-Sn was produced by lithiation for all NCs. As the cycle number increased, α-Sn became the dominant phase. First-principles calculations of the Li intercalation energy of α-Sn (Sn8) and ß-Sn (Sn4) indicate that Sn4Li(x) (x ≤ 3) is thermodynamically more stable than Sn8Li(x) (x ≤ 6) when both have the same composition. α-Sn maintains its crystalline form, while ß-Sn becomes amorphous upon lithiation. Based on these results, we suggest that once α-Sn is produced, it can retain its crystallinity over the repeated cycles, contributing to the excellent cycling performance.

Convenient metal embedment into mesoporous silica channels for high catalytic performance in AB dehydrogenation.

The infiltration of palladium nanoparticles (PdNPs) into the channels of SBA-15 was conveniently achieved via an incipient wetness procedure employing a tetraglyme solution. Electron tomography demonstrated that PdNPs were outgrown preferentially from the channels. The resultant Pd/SBA-15 showed high performance in the dehydrogenation kinetics of ammonia borane.

Photo-induced cation exchange reaction of germanium chalcogenide nanocrystals synthesized using gas-phase laser photolysis reaction.

Germanium chalcogenide GeS(x)Se(1-x) nanocrystals (NC) were synthesized using a novel gas-phase laser photolysis reaction. The composition was simply controlled by the partial pressure of precursors in a closed reactor. Remarkably, these ligand-free NC undergo the photo-induced cation exchange reaction to produce a series of Cd, Zn, Pb, and Ag chalcogenide NC in aqueous solution, which is governed by the thermodynamic driving force based on solubility.

Tetragonal phase germanium nanocrystals in lithium ion batteries.

Various germanium-based nanostructures have recently demonstrated outstanding lithium ion storage ability and are being considered as the most promising candidates to substitute current carbonaceous anodes of lithium ion batteries. However, there is limited understanding of their structure and phase evolution during discharge/charge cycles. Furthermore, the theoretical model of lithium insertion still remains a challenging issue. Herein, we performed comparative studies on the cycle-dependent lithiation/delithiation processes of germanium (Ge), germanium sulfide (GeS), and germanium oxide (GeO2) nanocrystals (NCs). We synthesized the NCs using a convenient gas phase laser photolysis reaction and attained an excellent reversible capacity: 1100-1220 mAh/g after 100 cycles. Remarkably, metastable tetragonal (ST12) phase Ge NCs were constantly produced upon lithiation and became the dominant phase after a few cycles, completely replacing the original phase. The crystalline ST12 phase persisted through 100 cycles. First-principles calculations on polymorphic lithium-intercalated structures proposed that the ST12 phase Ge12Lix structures at x ≥ 4 become more thermodynamically stable than the cubic phase Ge8Lix structures with the same stoichiometry. The production and persistence of the ST12 phase can be attributed to a stronger binding interaction of the lithium atoms compared to the cubic phase, which enhanced the cycling performance.

Germanium sulfide(II and IV) nanoparticles for enhanced performance of lithium ion batteries.

Germanium sulfide (GeS and GeS2) nanoparticles were synthesized by novel gas-phase laser photolysis and subsequent thermal annealing. They showed excellent cycling performance for lithium ion batteries, with a maximum capacity of 1010 mA h g(-1) after 100 cycles. Metastable tetragonal phase Ge nanoparticles were suggested as active materials for a reversible lithium insertion-extraction process.

Charge-selective surface-enhanced Raman scattering using silver and gold nanoparticles deposited on silicon-carbon core-shell nanowires.

The deposition of silver (Ag) or gold (Au) nanoparticles (NPs) on vertically aligned silicon-carbon (Si-C) core-shell nanowires (NWs) produces sensitive substrates for surface-enhanced Raman spectroscopy (SERS). The undoped and 30% nitrogen (N)-doped graphitic layers of the C shell (avg thickness of 20 nm) induce a higher sensitivity toward negatively (-) and positively (+) charged dye molecules, respectively, showing remarkable charge selectivity. The Ag NPs exhibit higher charge selectivity than the Au NPs. The Ag NPs deposited on p- and n-type Si NWs also exhibit (-) and (+) charge selectivity, respectively, which is higher than that of the Au NPs. The X-ray photoelectron spectroscopy analysis indicates that the N-doped graphitic layers donate more electrons to the metal NPs than the undoped ones. More distinct electron transfer occurs to the Ag NPs than to the Au NPs. First principles calculations of the graphene-metal adducts suggest that the large electron transfer capacity of the N-doped graphitic layers is due to the formation of a N→Ag coordinate bond involving the lone pair electrons of the N atoms. We propose that the more (-) charged NPs on the N-doped graphitic layers prefer the adsorption of (+) charged dyes, enhancing the SERS intensity. The charge selectivity of the Si NW substrates can also be rationalized by the greater electron transfer from the n-type Si to the metal NPs.

Nanodiamonds as photocatalysts for reduction of water and graphene oxide.

Detonated nanodiamonds (NDs) exhibit remarkable photocatalytic activity towards the hydrogen gas generation upon 532 nm laser pulse irradiation. Hydrogenation dramatically increases the quantum yield, suggesting that hydrogen-terminated sites work as electron reservoirs. NDs can also be used as effective photocatalysts to reduce graphene oxide. The resulting composites exhibit high and stable photocurrent generation upon visible light irradiation.