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

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

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 Agreement and correlation of abdominal skeletal muscle area measured by CT and MR imaging in cirrhotic patients

Additional file 1. Table S1. The original data of the baseline clinical characteristics of the patients

Late First-Row Transition Metal Complexes of a Tetradentate Pyridinophane Ligand: Electronic Properties and Reactivity Implications

The synthesis and structural comparison are reported herein for a series of late first-row transition metal complexes using a macrocyclic pyridinophane ligand, <i>N</i>,<i>N</i>′-di-<i>tert</i>-butyl-2,11-diaza­[3.3]­(2,6)­pyridinophane (^tBuN4). The ^tBuN4 ligand enforces a distorted octahedral geometry in complexes [(^tBuN4)­M^II(MeCN)₂]­(OTf)₂ (M = Fe^II, Co^II, Ni^II, Cu^II), [(^tBuN4)­Zn^II(MeCN)­(OTf)]­(OTf), and [(^tBuN4)­Fe^III(OMe)₂]­(OTf), with elongated axial M–N_amine distances compared to the equatorial M–N_py distances. The geometry of [(^tBuN4)­Cu^I(MeCN)]­(OTf) is pentacoordinate with weak axial interactions with the amine N-donors of ^tBuN4. Complexes [(^tBuN4)­M­(MeCN)₂]­(OTf)₂ (M = Fe, Co) exhibit magnetic properties that are intermediate between those expected for high spin and low spin complexes. Electrochemical studies of (^tBuN4)­M complexes suggest that ^tBuN4 is suitable to stabilize Co^I, Ni^I, Co^III, Fe^III solvato-complexes, while the electrochemical oxidation of (^tBuN4)­NiCl₂ complex leads to formation of a Ni^III species, supporting the ability of the ^tBuN4 ligand to stabilize first row transition metal complexes in various oxidation states. Importantly, the [(^tBuN4)­M^II(MeCN)₂]²⁺ complexes exhibit two available <i>cis</i> coordination sites and thus can mediate reactions involving exogenous ligands. For example, the [(^tBuN4)­Cu^II(MeCN)₂]²⁺ species acts as an efficient Lewis acid and promotes an uncommon hydrolytic coupling of nitriles. In addition, initial UV–vis and electron paramagnetic resonance (EPR) studies show that the [(^tBuN4)­Fe^II(MeCN)₂]²⁺ complex reacts with oxidants such as H₂O₂ and peracetic acid to form high-valent Fe transient species. Overall, these results suggest that the (^tBuN4)­M^II systems should be able to promote redox transformations involving exogenous substrates

Late First-Row Transition Metal Complexes of a Tetradentate Pyridinophane Ligand: Electronic Properties and Reactivity Implications

The synthesis and structural comparison are reported herein for a series of late first-row transition metal complexes using a macrocyclic pyridinophane ligand, <i>N</i>,<i>N</i>′-di-<i>tert</i>-butyl-2,11-diaza­[3.3]­(2,6)­pyridinophane (^tBuN4). The ^tBuN4 ligand enforces a distorted octahedral geometry in complexes [(^tBuN4)­M^II(MeCN)₂]­(OTf)₂ (M = Fe^II, Co^II, Ni^II, Cu^II), [(^tBuN4)­Zn^II(MeCN)­(OTf)]­(OTf), and [(^tBuN4)­Fe^III(OMe)₂]­(OTf), with elongated axial M–N_amine distances compared to the equatorial M–N_py distances. The geometry of [(^tBuN4)­Cu^I(MeCN)]­(OTf) is pentacoordinate with weak axial interactions with the amine N-donors of ^tBuN4. Complexes [(^tBuN4)­M­(MeCN)₂]­(OTf)₂ (M = Fe, Co) exhibit magnetic properties that are intermediate between those expected for high spin and low spin complexes. Electrochemical studies of (^tBuN4)­M complexes suggest that ^tBuN4 is suitable to stabilize Co^I, Ni^I, Co^III, Fe^III solvato-complexes, while the electrochemical oxidation of (^tBuN4)­NiCl₂ complex leads to formation of a Ni^III species, supporting the ability of the ^tBuN4 ligand to stabilize first row transition metal complexes in various oxidation states. Importantly, the [(^tBuN4)­M^II(MeCN)₂]²⁺ complexes exhibit two available <i>cis</i> coordination sites and thus can mediate reactions involving exogenous ligands. For example, the [(^tBuN4)­Cu^II(MeCN)₂]²⁺ species acts as an efficient Lewis acid and promotes an uncommon hydrolytic coupling of nitriles. In addition, initial UV–vis and electron paramagnetic resonance (EPR) studies show that the [(^tBuN4)­Fe^II(MeCN)₂]²⁺ complex reacts with oxidants such as H₂O₂ and peracetic acid to form high-valent Fe transient species. Overall, these results suggest that the (^tBuN4)­M^II systems should be able to promote redox transformations involving exogenous substrates

Table_7_Comprehensive identification and analysis of circRNAs during hickory (Carya cathayensis Sarg.) flower bud differentiation.xlsx

Flower bud differentiation represents a crucial transition from vegetative growth to reproductive development. Carya cathayensis (hickory) is an important economic species in China, with a long juvenile period that hinders its commercial development. In recent years, circular RNAs (circRNAs) have been widely studied and identified as sponges for miRNA regulation of mRNA expression. However, little is known regarding the role of circRNAs in flower buds. In this study, we sequenced circRNAs at three developmental stages (undifferentiated, differentiating, and fully differentiated) in both female and male buds. A total of 6,931 circRNAs were identified in the three developmental stages and 4,449 and 2,209 circRNAs were differentially expressed in female and male buds, respectively. Gene ontology demonstrated that many circRNA host genes participated in various processes, for example, cellular and intracellular pH regulation. Function annotation identified 46 differentially expressed circRNAs involved in flowering regulation, with 28 circRNAs found only in female buds, 4 found only in male buds, and 11 found in both female and male buds. A circRNA-miRNA-mRNA network was predicted based on 13 flowering-related circRNAs and their seven putative interacting miRNAs to describe the regulatory mechanism. Our preliminary results demonstrated a potential involvement of circRNA in bud differentiation. They provided a preliminary theoretical basis for how circRNA might participate in flower development in hickory, perhaps in woody plants.</p

Image_2_Comprehensive identification and analysis of circRNAs during hickory (Carya cathayensis Sarg.) flower bud differentiation.jpeg

Flower bud differentiation represents a crucial transition from vegetative growth to reproductive development. Carya cathayensis (hickory) is an important economic species in China, with a long juvenile period that hinders its commercial development. In recent years, circular RNAs (circRNAs) have been widely studied and identified as sponges for miRNA regulation of mRNA expression. However, little is known regarding the role of circRNAs in flower buds. In this study, we sequenced circRNAs at three developmental stages (undifferentiated, differentiating, and fully differentiated) in both female and male buds. A total of 6,931 circRNAs were identified in the three developmental stages and 4,449 and 2,209 circRNAs were differentially expressed in female and male buds, respectively. Gene ontology demonstrated that many circRNA host genes participated in various processes, for example, cellular and intracellular pH regulation. Function annotation identified 46 differentially expressed circRNAs involved in flowering regulation, with 28 circRNAs found only in female buds, 4 found only in male buds, and 11 found in both female and male buds. A circRNA-miRNA-mRNA network was predicted based on 13 flowering-related circRNAs and their seven putative interacting miRNAs to describe the regulatory mechanism. Our preliminary results demonstrated a potential involvement of circRNA in bud differentiation. They provided a preliminary theoretical basis for how circRNA might participate in flower development in hickory, perhaps in woody plants.</p

Table_9_Comprehensive identification and analysis of circRNAs during hickory (Carya cathayensis Sarg.) flower bud differentiation.xlsx

Flower bud differentiation represents a crucial transition from vegetative growth to reproductive development. Carya cathayensis (hickory) is an important economic species in China, with a long juvenile period that hinders its commercial development. In recent years, circular RNAs (circRNAs) have been widely studied and identified as sponges for miRNA regulation of mRNA expression. However, little is known regarding the role of circRNAs in flower buds. In this study, we sequenced circRNAs at three developmental stages (undifferentiated, differentiating, and fully differentiated) in both female and male buds. A total of 6,931 circRNAs were identified in the three developmental stages and 4,449 and 2,209 circRNAs were differentially expressed in female and male buds, respectively. Gene ontology demonstrated that many circRNA host genes participated in various processes, for example, cellular and intracellular pH regulation. Function annotation identified 46 differentially expressed circRNAs involved in flowering regulation, with 28 circRNAs found only in female buds, 4 found only in male buds, and 11 found in both female and male buds. A circRNA-miRNA-mRNA network was predicted based on 13 flowering-related circRNAs and their seven putative interacting miRNAs to describe the regulatory mechanism. Our preliminary results demonstrated a potential involvement of circRNA in bud differentiation. They provided a preliminary theoretical basis for how circRNA might participate in flower development in hickory, perhaps in woody plants.</p

Table_11_Comprehensive identification and analysis of circRNAs during hickory (Carya cathayensis Sarg.) flower bud differentiation.xlsx

Flower bud differentiation represents a crucial transition from vegetative growth to reproductive development. Carya cathayensis (hickory) is an important economic species in China, with a long juvenile period that hinders its commercial development. In recent years, circular RNAs (circRNAs) have been widely studied and identified as sponges for miRNA regulation of mRNA expression. However, little is known regarding the role of circRNAs in flower buds. In this study, we sequenced circRNAs at three developmental stages (undifferentiated, differentiating, and fully differentiated) in both female and male buds. A total of 6,931 circRNAs were identified in the three developmental stages and 4,449 and 2,209 circRNAs were differentially expressed in female and male buds, respectively. Gene ontology demonstrated that many circRNA host genes participated in various processes, for example, cellular and intracellular pH regulation. Function annotation identified 46 differentially expressed circRNAs involved in flowering regulation, with 28 circRNAs found only in female buds, 4 found only in male buds, and 11 found in both female and male buds. A circRNA-miRNA-mRNA network was predicted based on 13 flowering-related circRNAs and their seven putative interacting miRNAs to describe the regulatory mechanism. Our preliminary results demonstrated a potential involvement of circRNA in bud differentiation. They provided a preliminary theoretical basis for how circRNA might participate in flower development in hickory, perhaps in woody plants.</p