A Haptics and Virtual Reality Simulator for Cataract Surgery

A haptics and virtual reality simulator for cataract surgery is presented. As a computer-based surgical training platform, this simulator provides realistic haptic feedback as well as vivid 3D visualization. Simulations of a series of surgical tasks and exercises are implemented, including micro-dexterity, eyeball balancing, corneal incision construction, phaco sculpting, lens cracking and lens quadrants removal. Novel algorithms for recreation of visual and haptic effects as well as physics simulation encountered in cataract surgery are presented

A Haptics and Virtual Reality Simulator for Cataract Surgery

A haptics and virtual reality simulator for cataract surgery is presented. As a computer-based surgical training platform, this simulator provides realistic haptic feedback as well as vivid 3D visualization. Simulations of a series of surgical tasks and exercises are implemented, including micro-dexterity, eyeball balancing, corneal incision construction, phaco sculpting, lens cracking and lens quadrants removal. Novel algorithms for recreation of visual and haptic effects as well as physics simulation encountered in cataract surgery are presented

Nanosecond Molecular Dynamics of Hybrid Triplex and Duplex of Polycation Deoxyribonucleic Guanidine Strands with a Complimentary DNA Strand

Replacement of the phosphodiester linkages of the polyanion DNA with guanidinium linkers provides the polycation deoxyribonucleic guanidine (DNG). Molecular dynamics studies to 1120 ps of the hybrid triplex and 1420 ps of the hybrid duplex formed from octameric DNG strands d(Tg)8 with a complementary DNA oligomer strand d(Ap)8 have been carried out with water explicitly as solvent and Na+Cl- as counterions under periodic boundary conditions using the CHARMM force field and Ewald summation method. The Watson−Crick and Hoogstein hydrogen-bonding patterns of the A/T tracts remained intact without any structural restraints for both hybrid duplex and triplex structures throughout the simulation. And for the hybrid duplex and triplex structures, both 5‘ and 3‘ ends were only partially frayed. In agreement with our previous thermodynamic study the hybrid triplex is more favorable than the hybrid duplex in the simulations. This conclusion is reached by the comparison of the extent of 5‘ end fraying and the bifurcating properties of the two systems. The structural histories of the DNG·DNA·DNG triplex and DNG·DNA duplex were determined by examining histograms from the last 1400 ps (duplex) and 1100 ps (triplex) of the dynamics run. These include the hydrogen-bonding pattern (sequence recognition) and base pair opening occurrences, minor groove width narrowing, and tract bending for the hybrid duplex and triplex structures. The bending angle measured between the local axis vectors of the first and last helical axis segments is about 30° for the averaged structures of both hybrid duplex and Watson−Crick portion of the hybrid triplex. Propeller twist (associated with three centered hydrogen bonding) up to −30°, native to DNA AT base pairing, was also observed for the duplex structure. The helical rise and twist parameters of the duplex structure and the duplex portion of the triplex structure assume a more B-DNA like conformation. However, the sugar pucker and other helical, axis, and base pair parameters of the two structures equilibrate at a A and B complex conformation, from base to base and base pair to base pair, which suggests a more A-DNA like overall conformation. Water spines are observed during the dynamics runs for both hybrid duplex and triplex structures in both minor and major grooves. The counterions remain in their positions through the dynamics run for the triplex system

Conformational Propensities of Peptides Mimicking Transmembrane Helix 5 and Motif C in Wild-Type and Mutant Vesicular Acetylcholine Transporters

Vesicular acetylcholine transporter (VAChT) is a member of the major facilitator superfamily (MFS). It contains conserved sequence motifs originally defined in the bacterial multidrug resistance transporter family of the MFS. Motif C (GSLV227A228PPFGGIL) is located at the C-terminal end of transmembrane helix 5 (TM 5) in VAChT. The motif is rich in glycine and proline residues that often have special roles in backbone conformations of TMs. The A228G mutant of VAChT transports >3-fold faster than wild-type does [Chandrasekaran et al. (2006) J. Neurochem. 98, 1551−1559.]. In the current study, the structure of Loop 4/5, TM 5, and motif C were taken from a three-dimensional homology model for human VAChT. The peptide was immersed in implicit membrane and energy-minimized, and molecular dynamics (MD) were simulated. Kinking and wobbling occur in otherwise helical peptide at the hinge residues L226 and V227. MD also were simulated for A228G single mutant and V227L−A228A double mutant peptides to investigate the structural roles of the A228G mutation and β-branching at V227. Mutant peptides exhibit increased wobbling at the hinge residues, but in the double mutant the increase is less. Because motif C participates in the interface that mediates hypothesized rocker-switch reorientation of the acetylcholine binding site during transport, dynamics in motif C might be an important contributor to transport rate

Table_1_An empirical assessment of a modified artificially intelligent device use acceptance model—From the task-oriented perspective.DOCX

Artificial intelligence (AI) is a cutting-edge technology that has been widely applied in tourism operations. To enhance tourists' experience, many tourism suppliers introduced AI devices to interact with tourists. Previous studies classified AI devices as task- and social- oriented based on their functions; however, current models that explain customers' intention to use AI devices did not reflect the discrepancy between the two different types. Therefore, this paper attempts to fill this gap by proposing a theoretical model for the use of task-oriented AI devices. Based on the multi-stage appraisal framework and the Structural Equation Modeling analysis, this paper presents the following findings: (1) utilitarian motivation, interaction convenience, and task-technology fit are the factors appraised in the first stage; (2) perceived competence and flow experience are the factors appraised in the second stage; (3) utilitarian motivation, interaction convenience, and task-technology fit are positively associated with perceived competence. (4) Perceived competence positively influences flow experience, which further affects customers' switching intention from task-oriented AI devices to human service; (5) the serial mediating effect of perceived competence and flow experience between the stimulus mentioned in the first appraisal stage and the switching intention is confirmed. This study reveals the underlying psychological mechanism when customers use task-oriented AI devices, and it provides a theoretical framework for task-oriented AI device adoption.</p

Dinuclear Co(II)Co(III) Mixed-Valence and Co(III)Co(III) Complexes with N- and O-Donor Ligands: Characterization and Water Oxidation Studies

The tridentate ligand N-methyl-N,N-bis(2-pyridylmethyl)amine (L) has been employed to synthesize a dinuclear Co(II)Co(III) mixed-valence complex containing μ-methoxo and μ-carboxylato bridging ligands, [LCoII(μ-carboxylato)bis(μ-methoxo)CoIIIL](ClO4)2. In this complex, the two pseudo-octahedral Co centers have an identical ligand environment, yet the average Co–N and Co–O bond distances at the two Co ions differ significantly. Electrochemical, spectroscopic, and magnetic susceptibility measurements confirm that it belongs to a localized Class II mixed-valence system, despite the presence of a short Co···Co distance of 3.021 Å. Oxidation of this Co(II)Co(III) complex leads to formation of the corresponding Co(III)Co(III) complex that was characterized structurally and spectroscopically. In addition, dinuclear and trinuclear μ-hydroxo Co(III) complexes have been obtained in the presence of phosphate anions and absence of methanol, respectively, suggesting that an additional bridging ligand is needed to stabilize the CoIIIbis(μ-hydroxo)CoIII fragment. Moreover, the ability of the mixed-valence Co(II)Co(III) complex and the three related Co(III) complexes to electrocatalytically oxidize water was also investigated. The observed limited water oxidation catalytic ability for these systems suggests that a multinuclear Co cluster and/or presence of O-rich ligands may be needed for the generation of efficient molecular Co-based water oxidation catalysts

Dinuclear Co(II)Co(III) Mixed-Valence and Co(III)Co(III) Complexes with N- and O-Donor Ligands: Characterization and Water Oxidation Studies

The tridentate ligand N-methyl-N,N-bis(2-pyridylmethyl)amine (L) has been employed to synthesize a dinuclear Co(II)Co(III) mixed-valence complex containing μ-methoxo and μ-carboxylato bridging ligands, [LCoII(μ-carboxylato)bis(μ-methoxo)CoIIIL](ClO4)2. In this complex, the two pseudo-octahedral Co centers have an identical ligand environment, yet the average Co–N and Co–O bond distances at the two Co ions differ significantly. Electrochemical, spectroscopic, and magnetic susceptibility measurements confirm that it belongs to a localized Class II mixed-valence system, despite the presence of a short Co···Co distance of 3.021 Å. Oxidation of this Co(II)Co(III) complex leads to formation of the corresponding Co(III)Co(III) complex that was characterized structurally and spectroscopically. In addition, dinuclear and trinuclear μ-hydroxo Co(III) complexes have been obtained in the presence of phosphate anions and absence of methanol, respectively, suggesting that an additional bridging ligand is needed to stabilize the CoIIIbis(μ-hydroxo)CoIII fragment. Moreover, the ability of the mixed-valence Co(II)Co(III) complex and the three related Co(III) complexes to electrocatalytically oxidize water was also investigated. The observed limited water oxidation catalytic ability for these systems suggests that a multinuclear Co cluster and/or presence of O-rich ligands may be needed for the generation of efficient molecular Co-based water oxidation catalysts

Oxidative Reactivity of (N2S2)PdRX Complexes (R = Me, Cl; X = Me, Cl, Br): Involvement of Palladium(III) and Palladium(IV) Intermediates

A series of (N2S2)­PdRX complexes (N2S2 = 2,11-dithia[3.3]­(2,6)­pyridinophane; R = X = Me, <b>1</b>; R = Me, X = Cl, <b>2</b>; R = Me, X = Br, <b>3</b>; R = X = Cl, <b>4</b>) were synthesized, and their structural and electronic properties were investigated. X-ray crystal structures show that for the corresponding Pd­(II) complexes the N2S2 ligand adopts a κ² conformation, with the pyridine N donors binding in the equatorial plane. Cyclic voltammetry (CV) studies suggest that the Pd­(III) oxidation state is accessible at moderate redox potentials. In situ EPR, ESI-MS, UV–vis, and low-temperature electrochemical studies were employed to detect the formation of Pd­(III) species during the oxidation of Pd­(II) precursors. In addition, the [(N2S2)­Pd^IVMe₂]­(PF₆)₂ ([<b>1</b>²⁺]­(PF₆)₂) complex was isolated by oxidation of <b>1</b> with 2 equiv of FcPF₆, and its structural characterization reveals an octahedral Pd­(IV) center. The reversible Pd^IV/III redox couple for the Pd­(IV) species supports the observed formation of the Pd­(III)–dimethyl species upon chemical reduction of <b>1</b>²⁺. In addition, reactivity studies reveal ethane, MeCl, and MeBr elimination upon one-electron oxidation of <b>1</b> (as well as the one-electron reduction of <b>1</b>²⁺), <b>2</b>, and <b>3</b>, respectively. Mechanistic studies suggest the initial formation of a Pd­(III) species, followed by methyl group transfer/disproportionation and subsequent reductive elimination from a Pd­(IV) intermediate, although a halogen radical pathway cannot be completely excluded during C–halide bond formation. Interestingly, computational results suggest that the N2S2 ligand stabilizes to a greater extent the Pd­(IV) vs the Pd­(III) oxidation state, likely due to steric rather than electronic effects

Additional file 1 of Changes in the physiological activity of parenchyma cells in Dalbergia odorifera xylem and its relationship with heartwood formation

Supplementary Material

Genome-wide association study of handgrip strength in the Northern Chinese adult twins

Currently, new loci related to handgrip strength have been identified in genome-wide association studies. However, this topic is an understudied area in the Chinese population. A total of 135 dizygotic twin pairs recruited from the Qingdao Twin Registry system were included in the present study. Using GEMMA, VEAGSE2, and PASCAL software for SNP-based analysis, gene-based analysis, and pathway-based analysis, respectively. The resulting SNPs were subjected to eQTL analysis. Although none of the loci reach the statistically significant level (p −8), we found 19 SNPs exceeding the suggestive significant level (p −5). After imputation, 162 SNPs reached suggestive evidence level for handgrip strength. A total of 1,118 genes reached the nominal significance level (p p  Genetic variants may involve in regulatory domains, functional genes, and biological pathways that mediate handgrip strength.</p