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Permeability is a key parameter of rock reservoirs, suggesting the flow characteristics of rock reservoirs. Permeability prediction of carbonate reservoirs is still a great challenge due to its complex pore network and wide range permeability. This work is to establish a digital quantum mechanism-based neural network (DQNN) to study the permeability using the digital porosity, coordination number and pore network size. Experiments and artificial neural network methods (ANN) are applied to validate the accuracy of the proposed DQNN method. In these methods, the pore-scale variables extracted from the micro-CT images of 200 carbonate samples are applied. Results show that the permeabilities obtained from experimental, artificial neural network and DQNN methods agree well with each other. Digital pore size, pore throat size and length are better parameters, while coordination number and porosity are relatively secondary parameters for permeability descriptions of carbonate reservoirs. Compared with the ANN method, the proposed DQNN method is superior in low computation time and high ability for complicated problems.

Xenogeneic bone showed great prospects to treat large bone defects due to its bionic composition and structure, but the immunogenicity limited its wide applications. Previously, we developed a pepsin treating method to eliminate the immunogenicity of xenogeneic bone. In this study, we further investigated the effect of pepsin processing time on the biological and mechanical properties. The results indicated that increased pepsin treating time impaired the mechanical properties of xenogeneic bone. And MC3T3-E1 cells showed enhanced adhesion ability, as well as increased production of alkaline phosphatase and calcium nodulus production on the xenogeneic bone processed by pepsin for 24 hr (P24), as compared with xenogeneic bone processed by pepsin for 30 hr (P30) and 36 hr (P36). In addition, we found no significant inflammatory responses after implanting different xenogeneic bone into the intermuscular site of rats. These results suggested that xenogeneic bone processed by pepsin for 24 hr may be a preferable choice when using the xenogeneic bone as biomaterials for further researches.

Tantalum has unique advantages as a biomaterial for repairing bone defects due to its outstanding bioactivity, excellent corrosion resistance, and mechanical properties. Ideal implants for bone repair should be of good biocompatibility and bioactivity, as well as ability to simulate the microstructure and mechanical environment of human bone tissues. Additive manufacturing can facilitate freedom of design for the macrostructure/microstructure of bone implants with controlled mechanical properties; thus, this method has great potential. Additively manufactured tantalum implants provide a novel alternative for bone repair and are gaining increasing attention. This systematic review aims to comprehensively summarize the subsistent evidence from physicochemical, cellular, animal, and clinical studies on additively manufactured tantalum implants in repairing bone defects, for the first time. This work may provide researchers an essential grasp on the advances of additively manufactured tantalum implants. Impact statement Tantalum has unique advantages as a biomaterial. Additive manufacturing facilitates design freedom and additively manufactured tantalum is a novel alternative for bone repair. Studies on additively manufactured tantalum progress greatly, while no review summarizing the progresses was published.

To develop a clean and sustainable carbon anode material derived from biomass with desirable properties for lithium-ion batteries (LIBs), bio-nitrogen (N)-doped composite carbon nanofibrous mats (CNFMs) were made using natural cellulose (CE) and chitosan (CS) by means of two different electrospinning ways (single-nozzle and coaxial-nozzle) coupled with pyrolysis. The conventional CNFMs that had a CE/CS ratio of 5:5 showed the best electrochemical performance, corresponding to a high specific capacity of 327 mAh g−1 at 100 mA g−1, good rate performance with specific capacity of 399 mAh g−1 at 30 mA g−1 and 210 mA g−1 at 1000 mA g−1, as well as excellent cycling stability after 300 cycles. The core–shell CNFMs with a thick outer layer of CS and large average fiber diameter (316 nm) at the same CE/CS ratio had higher pyridinic-N and pyrrolic-N contents but a lower degree of graphitization and BET surface area compared to the conventional CNFMs. It was concluded that the bio-N in CS was more uniformly doped into the CNFMs by the single-nozzle electrospinning way than by the coaxial one, and thus more effectively promoted a comprehensive electrochemical performance.

Endemic arsenism is widely distributed in the world, which can damage multiple organs, especially in skin and liver. The etiology is clear, but the mechanisms involved remain unknown. Ubiquitin-proteasome pathway (UPP) is the main pathway regulating protein degradation of which proteasome subunit beta type-5(PSMB5) plays a dominant role. This paper aims to study the role and mechanism of PSMB5 in sodium arsenite (NaAsO(2))–induced oxidative stress liver injury in L-02 cells. Firstly, L-02 cells were exposed to different concentrations of NaAsO(2) to establish a liver injury model of oxidative stress, and then mechanisms of oxidative stress were studied with carbobenzoxyl-leucyl-leucl-leucll-line (MG132) and knockdown PSMB5 (PSMB5-siRNA). The oxidative stress indicators, levels of 20S proteasome, the transcription and protein expression levels of PSMB5, Cu-Zn superoxide dismutase (SOD1), and glutathione peroxidase 1 (GPx1) were detected. The results demonstrated that NaAsO(2) could induce oxidative stress–induced liver injury and the activity of 20S proteasome and the protein expression of PSMB5, SOD1, and GPx1 decreased. After MG132 or PSMB5-siRNA pretreatment, the gene expression of PSMB decreased. After MG132 or PSMB5-siRNA pretreatment, and then L-02 cells were treated with NaAsO(2), the gene expression of PSMB remarkably decreased; however, the protein expression of SOD1 and GPx1 increased. Overall, NaAsO(2) exposure could induce oxidative stress liver injury and low expression of PSMB5 in L-02 cells, and PSMB5 might play an important role in the regulation of oxidative stress by regulating the expression of SOD1 and Gpx1.

As one of the candidates for the next generation of data storage techniques, organic multilevel resistive memory has attracted more and more attention. Even though many types of materials have been fabricated into memory devices and successfully obtained multilevel memory behaviors, they still suffer from complex fabrication processes, relatively expensive price and poor temperature stability, which hinders the further applications of RRAM techniques. On the other hand, many organics dyes with a conjugated zwitterion structure are commercially available and inexpensive but rarely considered as memory materials. Herein, two commercial dyes, Rhodamine B (Rh B) and Rhodamine 6G (R 6G), were selected as active materials to fabricate memory devices through a one-step method. The as-fabricated memory devices showed ternary write-once-read-many-times (WORM) type memory behaviors, with the retention time up to 5000 s. Benefitted from the strong intermolecular interactions, rhodamine-based memory devices could work stably under 80 °C. Additionally, Rh B and R 6G could also be fabricated on various flexible substrates, such as polyethylene terephthalate (PET), stamps and tree leaves. The ternary memory behaviors could be sustained after bending 1000 times. Our work demonstrates the potential of commercially available dyes for low price and easy-fabrication flexible multilevel resistive memories.

Treatment of bone and joint tuberculosis remains a challenge. The development of tissue-engineered drug-loaded biomaterials has increased the therapeutic options. However, for the treatment of osteoarticular tuberculosis with severe local infection risks and high weight-bearing requirements, it is still necessary to design materials consistent with bone biomechanics, cytocompatibility, and osteogenesis and to provide more effective antimicrobial functions. The antitubercular drugs isoniazid and rifampicin are loaded with gellan gum, and a 3D-printed porous tantalum surface is treated with polydopamine to increase adhesion. The osteogenic induction and differentiation are tested using alkaline phosphatase, alizarin red staining, sirius red staining, and polymerase chain reaction testing. Bone regeneration in vivo is measured by X-ray, micro-computerized tomography, hard tissue sections, and fluorescence staining. The drug is released slowly in vitro and in vivo, increasing the duration of antibacterial action. The composite bio-scaffolds inhibit Staphylococcus aureus growth, have good biocompatibility, and does not inhibit the induction of osteogenic differentiation of rat bone marrow mesenchymal stem cells. The composite bio-scaffold can simultaneously achieve localized long-term controlled drug release and bone regeneration and is a promising route for bone and joint tuberculosis treatment.

This paper gives an experimental study on electrochemical hydrogen bubble evolution at electrode surface partially covered with hydrophobic materials under electrode-normal magnetic field. Base on the method of photoetching and electrochemical co-deposition (PECD), the electrode partially covered with nickel–polytetrafluoroethylene (Ni-PTFE) materials is prepared to generate the controlled hydrogen bubble at specified islet. The anchored bubble evolution at hydrophobic islet is observed under magnetic field. Experimental results show that the hydrogen bubble release from the hydrophobic site is relatively random. Although it is not found that the obvious influence of micro-magnetohydrodynamic convection (MMHDC) on the single bubble release from isolated hydrophobic islet, MMHDC exactly plays the role of facilitating pair of bubbles releases from neighbouring hydrophobic islands. The new developed explanation of the mechanism of MMHDC influence on electrochemical bubble release has been given based on the method of numerical simulation.

Herein, chitosan-alginate core-shell gel beads are directly fabricated by a convenient one-step dripping approach. In particular, the approach exquisitely utilizes both the pH-responsive sol-gel transition property of chitosan and the calcium-responsive sol-gel transition property of alginate. The approach has a variety of benefits such as the simple method, the environmentally-friendly route (without using organic solvents and toxic reagents), the mild conditions (in aqueous solution at room temperature), and the easy post-treatment for the beads. Morphology observation from optical microscopy and scanning electron microscopy demonstrates that the resulting chitosan-alginate beads have a clear core-shell structure with a well-defined border between the core and the shell. The chitosan-alginate core-shell beads shows a good sphericity and monodispersity. Comparison experiments indicate that the shell thickness and the core state (solid or liquid) of the core-shell beads can be modulated by altering the preparation conditions (solution concentrations or pHs). Loading experiments demonstrate that the core-shell structure of the chitosan-alginate beads can be utilized to respectively load various components (e.g., fluorescent dyes, drugs, and nanoparticles) in different layers. Release studies reveal that the chitosan-alginate core-shell beads have attractive capabilities to regulate drug release through the pH-responsive sol-gel transition of the chitosan core as well as the thickness control of the alginate shell.

Polycarbonate (PCL) has been widely used in tissue engineering, but its hydrophobicity and low biological activity limit its further promotion and application. By adding nanoparticles, the hydrophilicity and biological activity of PCL can be improved. In this study, different amounts of Ta (1–10%wt) were added to PCL, and then their mechanical and biological properties were studied in vitro. XRD found that 5%Ta-PCL has the highest crystallinity. At the same time, cell experiments CCK8, cell adhesion, osteogenic differentiation, and osteogenesis related gene expression showed that Ta can enhance the mechanical and biological properties of PCL, while 5% Ta-PCL showed the best mechanical and biological properties. This composite of tantalum and PCL could have a clinical potential for orthopedic implants.

Tantalum (Ta) implants fabricated by current processing techniques inevitably contain more or less oxygen impurities due to the extremely high melting point and high affinity of oxygen for Ta. Therefore, in this study we investigated whether oxygen impurities cause any effects on the bioactivity of Ta. EDS analysis demonstrated the surface oxygen content difference among different fabricated Ta samples, and the surface water contact angle (WCA) of Ta with high oxygen content (HO-Ta) was significantly higher than that of Ta with medium (MO-Ta) and low (LO-Ta) oxygen content. The in vitro cellular experiments showed that MC3T3-E1 cells on Ta with lower oxygen content exhibited better adhesion, growth, morphological development and in vitro osteogenic ability. Similarly, the in vivo animal experiments indicated the better bone regeneration and ingrowth performances of Ta with lower oxygen content. In addition, the highest ROS production was detected in the HO-Ta group, while the lowest in the LO-Ta group. This study suggests that the oxygen content within Ta, which occurs unavoidably due to technical limitations, negatively affects the bioactivity of Ta in a dose-dependent manner, indicating the need to develop techniques to produce orthopedic all-Ta implants.

Despite the brilliant bioactive performance of tantalum as an orthopedic biomaterial verified through laboratory researches and clinical practice in the past decades, scarce evidences about the essential mechanisms of how tantalum contributes to osteogenesis were systematically discussed. Up to now, a few studies have uncovered preliminarily the biological mechanism of tantalum in osteogenic differentiation and osteogenesis; it is of great necessity to map out the panorama through which tantalum contributes to new bone formation. This minireview summarized current advances to demonstrate the probable signaling pathways and underlying molecular cascades through which tantalum orchestrates osteogenesis, which mainly contain Wnt/β-catenin signaling pathway, BMP signaling pathway, TGF-β signaling pathway, and integrin signaling pathway. Limits of subsistent studies and further work are also discussed, providing a novel vision for the study and application of tantalum.

Stickies deriving from the recycled paper had multiple deleterious effects on the paper chemicals, machine run-nability and paper equality. The aim of this study was to synthesize citosan composite microspheres and remove stickies in the recycled paper by microspheres. Citosan-montmorillonite and chitosan-ferroferric oxide composite microspheres were prepared by emulsion cross-linking method. The surface morphology of microparticels was analyzed by Digital microscope (DM) and Scanning electron microscope (SEM). The removal effects of composite microspheres and talc on stickies were compared. It was found that CS-MMT microspheres had excellent thermal stability than chitosan microspheres and CS-Fe3O4 microspheres. The zeta potential of stock increased with the addition of talc,CS-MMT or CS-Fe3O4. Comparing with the plate talc, CS-MMT or CS-Fe3O4 microspheres adsorbed more easily the stickies and removed DCS in the recycled paper. Meanwhile, CS-MMT or CS-Fe3O4 had less negative impact on the strength of paper than talc. It contributed that there was a large number of hydroxyl groups on the surface of composite microspheres. CS-Fe3O4 had magnetic characteristics and the ability of removing Dissolved and Colloidal Substances (DCS) in white water were superior to CS-MMT.

The increasing utilization of silver nanoparticles (Ag NPs) in industry and commerce inevitably raises its release into wastewater. In this work, effects of Ag NPs on system performance and microbial community along the way of a vertical flow constructed wetland (VFCW) were investigated, along with the removal and fate of Ag NPs within the system. Results showed that the performance of control wetland kept stable during the experimental period, and the top substrate layer (soil layer) of wetland could remove most of pollutants in the influent. The study also suggested that addition of Ag NPs did not significantly affect organic matters removal. However, adverse effects were observed on the nitrogen and phosphorus removal. Removal efficiencies of TN, NH4+-N and TP approximately obviously reduced by approximately 10.10%, 8.42% and 28.35% respectively in contrast to before dosing after exposing 100 μg/L Ag NPs for 94 d, while the no dosing wetland with the stable performance. It was found that Ag NPs accumulated in the upper soil layer more than in the lower soil layer, and Ag NPs could enter into the plant tissues. After continuous input of Ag NPs, removal efficiency of Ag NPs was measured as 95.72%, which showed that the CW could effectively remove Ag NPs from the wastewater. The high-throughput sequencing results revealed that Ag NPs caused the shifts in microbial community structures and changed the relative abundances of key functional bacteria, which finally resulted in a lower efficiency of biological nitrogen and phosphorus removal.

The bone-tendon interface (BTI) is a graded structure consisting of bone, mineralized and nonmineralized fibrocartilage, and tendons. Due to the complexity of the BTI structure, BTI healing is particularly challenging. To achieve a better material for BTI healing, polycaprolactone (PCL)/hydroxyapatite (HA)/ZnO films were constructed by the electrospinning method; in addition, the relevant material characteristics were tested. After culturing MC3T-E1 cells, ATDC5 cells, mouse primary fibrochondrocytes, and mouse primary tenocytes on films, PCL-5%HA-1%ZnO films (HA and ZnO weight ratios of 5% and 1%, respectively) displayed superior cell compatibility and cell adhesion. PCL-5%HA-1%ZnO films also promoted osteogenesis, chondrogenesis, fibrocartilage formation, and tendon healing. The antibacterial characteristics of PCL-5%HA-1%ZnO films were also identified in this study. The PCL-5%HA-1%ZnO films have great application potential in the field of BTI repair.

Nonwood materials contain a high percentage of silicon, which causes numerous problems in the chemical recovery section. Researchers previously proposed the method of silicon removal by two-stage causticizing at temperatures of 90ºC to 95ºC, finding that the desilication rate was about 72.9% and the causticizing efficiency was 22.7% when 30% of the causticizing quicklime (calcium oxide; CaO) was added. The present paper deals with the desilication of green liquor recovered from wheat straw black liquor by a low-temperature precausticization method. The results showed that about 89.3% silicon removal and 10.3% causticizing efficiency were achieved under the following precausticizing conditions: added lime amount of 20%, temperature of 20ºC, and reaction time of 60 min. While precausticizing at 90ºC with the same lime amount, only about 63.5% silicon removal and 13.0% causticizing efficiency were gained. Therefore, precausticizing with low temperature was beneficial for silicon removal and retention of carbonate (CO3 2-).

Biomaterials composed of polymers and bioceramics have great prospects to repair large and complicated bone defects. Here, we developed a composite film consisting of poly(e-caprolactone) (PCL) and silicon-substituted hydroxyapatite (Si-HA) nanoparticles to enhance the osteogenic effects of the scaffold for bone tissue engineering applications. The results showed that the Si-HA nanoparticles obtained an even distribution in the PCL matrix, resulting in a homogeneous composite film. Compared to HA-incorporated PCL film, the addition of silicon did not cause hydrophilic alterations to the film surface. With the seeding of mouse calvarial preosteoblasts (MC3T3-E1), the cells exhibited the good behaviors of adhesion and growth on the PCL/Si-HA film. Compared to the PCL/HA films, incorporation of Si-HA nanoparticles in PCL/Si-HA films showed the increased production of alkaline phosphatase (ALP) and calcium content by MC3T3-E1 cells. These results suggested the suitability of the PCL/Si-HA composite film to elicit cellular growth and functional differentiation with the potential for bone tissue engineering applications.

This work investigates the effect of Lorentz force on the growth, coalescence and detachment of a pair of adjacent hydrogen bubbles. The bubbles are electrolytically generated from two horizontal micropores (d = 0.2 mm) with 1 mm between each other which is processed by the printed circuit board technology. The experiment is conducted in the acidic environment (0.5 mol/L H2SO4) with an electrode-normal homogeneous magnetic field (0.9 T) superimposed. The Lorentz force induced by the current distortion around the growing bubble and the rim of micro-electrode brings the so-called micro-magnetohydrodynamic (MMHD) convection in the scale of bubble size. The experiment gave the visualization research of bubble evolution, and it showed that MMHD convection delayed the adjacent bubble coalescence and decreased the bubble growth rate. Based on the computational fluid dynamics (CFD), the MMHD convection around the pair of bubbles is present clearly. It is found that pair of relative lower pressure areas is formed on the outside of pair of bubbles, and the pressure difference makes the bubble coalescence difficult.

Left and right-handed helical barium titanate nanotubes are prepared with the impregnation of Ba(OH) 2 into single-handed helical titania nanotubes. Wide angle X-ray diffraction pattern and transmission electron microscopy image indicate that they are constructed by nanoparticles with a partially crystalline structure. The diffuse reflectance circular dichroism spectra indicate that they exhibit optical activity which was proposed to originate from chiral defects on the inner surfaces of the nanotubes. Both the dielectric constant and tan δ decrease with increasing the frequency. At 10 and 100 Hz, one dielectric constant peak at 9.6 °C and one tan δ peak at 5.0 °C are observed at −120 °C to 180 °C.

In recent years, numerous organic molecules and polymers carrying various functional groups were synthesized and used in fabrication of wearable electronic devices. Compared to previous materials that suffer from poisonousness, stiffness and complex film fabrication, we circumvent above matters by taking advantage of mussel-inspired polydopamine as our active material to realize resistive random access memories (RRAMs). Polydopamine thin films were grown on indium tin oxide glass catalyzed by Cu2 SO4 /H2 O2 and characterized by Fourier infrared spectroscopy (FT-IR), UV/Vis spectroscopy and scanning electron microscopy. The Al/Polydopamine film/ITO devices possess ternary memory behavior with good ternary device yield with two threshold voltages around 1.50 V and 3.50 V, long data retention over 104 s of continuous reading or 104 pulse reading. The two resistance switchings are attributed to defects functioning as charge traps and the formation of conductive filaments. A flexible device based on Al/polydopamine film/ITO/polyethylene terephthalate retains its ternary memory behavior after being bent with a bending radius of 1.54 cm and bending cycles up to 5000, demonstrating good compatibility and flexibility of polydopamine.

Most free drugs that cross the blood–brain barrier are characterized by high liposolubility, but they often have limited clinical applications because of poor dissolution and poor bioavailability. In this study, we prepared donepezil drug-loaded nanoparticles (DZP) with cholesterol-modified pullulan (CHP) as the nanocarrier (DZP-CHP) and surface modified the drug-loaded nanoparticles to improve the water solubility of donepezil while enhancing its targeting and sustained release. We determined the drug loading and encapsulation efficiency of DZP-CHP nanoparticles at different feed ratios. The mean ± SD drug loading and entrapment efficiency were high: 13.52 ± 2.03 and 86.54 ± 1.31. On dynamic light-scattering measurement, mean ± SD particle size was 260.7 ± 1.76 nm, polydispersity index 0.123 ± 0.004, and zeta potential −5.75 ± 0.64 mV. DZP-CHP nanoparticles prepared with the optimal feed ratio (DZP : CHP = 1 : 5) were coated with polysorbate 80, and the adsorption process was determined by isothermal titration calorimetry. We found good affinity between polysorbate 80 and DZP-CHP, with mean ± SD coverage 2.7 ± 0.372. The mean ± SD drug loading and entrapment efficiency of polysorbate 80-emulsified DZP-CHP nanoparticles were 8.25 ± 1.80 and 91.28 ± 4.57, respectively, and the proportion of drug released by 72 h was 42.71%. Compared to DZP-CHP alone, PS-DZP-CHP can enhance the release of donepezil.

Herein, for the first time, quaternary resistive memory based on an organic molecule is achieved via surface engineering. A layer of poly(3,4-ethylenedioxythiophene)-poly(styrenesulfonate) (PEDOT-PSS) was inserted between the indium tin oxide (ITO) electrode and the organic layer (squaraine, SA-Bu) to form an ITO/PEDOT-PSS/SA-Bu/Al architecture. The modified resistive random-access memory (RRAM) devices achieve quaternary memory switching with the highest yield (∼41%) to date. Surface morphology, crystallinity, and mosaicity of the deposited organic grains are greatly improved after insertion of a PEDOT-PSS interlayer, which provides better contacts at the grain boundaries as well as the electrode/active layer interface. The PEDOT-PSS interlayer also reduces the hole injection barrier from the electrode to the active layer. Thus, the threshold voltage of each switching is greatly reduced, allowing for more quaternary switching in a certain voltage window. Our results provide a simple yet powerful strategy as an alternative to molecular design to achieve organic quaternary resistive memory.

The widespread utilization of silver nanoparticles (AgNPs) in industrial and commercial products inevitably raises the release into wastewater. In this study, the influences of AgNPs (0, 50 and 200 μg/L) on the performance and microbial community of CWs were evaluated. Compared with the control system (without AgNPs), the COD removal was not affected, whereas the TN, NH 4 + -N, and TP removals were evidently affected in presence of AgNPs, and the effects had a positive relation with AgNPs concentration. In addition, AgNPs were effectively removed from wastewater and mainly accumulated in the soil layer and plant tissues. The illumina high-throughput sequencing results indicated that there were obvious variations in the microbial community at different AgNPs concentrations, associated with the variations of CW performance. Sequencing analyses also showed that Proteobacteria , Acidobacteria , Bacteroidetes were the dominant phyla. These results may provide valuable information and reference for evaluating the effect of AgNPs on constructed wetlands.

By the design of molecular structure, improved polyurethane was synthesized and the material exhibited excellent mechanic properties, electrical insulation, resistance to chemical corrosion and UV aging. Its tensile and flexural strength were 58.4 MPa and 101.2 MPa; surface and volume resistivity were 9.68 × 1015 Ω and 2.60 × 1016 Ω.cm, respectively; and their loss modulus was less than 13% exposed under serious chemical substance and UV irradiation. Moreover, the properties of the polyurethane were superior to traditional epoxy and unsaturated polyester resin. Herin, resulted composite material poles and cross arms were operation under demonstration line, and accumulated relevant operating parameters.

Highly branched poly(urethane-imide)-epoxy (AHBPUI-EP) cross-linked copolymer was prepared by the reaction of epoxy resin (EP) with amino-terminated highly branched poly(urethane-imide) via A2 + B3 approach. The structure and properties of the AHBPUI-EP cross-linked copolymers were characterized by Fourier transform infrared spectroscopy, differential scanning calorimetry, thermal gravimetric analysis, tensile tests, and X-ray diffraction, respectively. It has been found that the increasing of the Tg of the cross-linked copolymer was resulted from the high density of cross-linking. The thermal stability was enhanced after introducing both imide and epoxy. The initial degradation temperature was up to 332.68 °C. Moreover, the mechanical properties changed with changing the content of EP, imide and the ratio of [A2]/[B3].

A complete series of dppfMX2 (M=Pt, Pd; X=Cl, Br, I) compounds have been synthesized using different routes, and characterized fully. The synthesis of dppfPdI2 has been achieved by reacting Pd(COD)Cl2 with dppf in the presence of NaI. X-ray structures of dppfPdBr2 and dppfPdI2 have also been reported for the first time in this study. A preliminary Suzuki coupling screening study reveals that dppfPdX2 compounds are superior to the conventional Ph3P-based catalysts and bidentate phosphine-based ligands. Reactions carried out under in situ conditions also gave a similar trend, but their respective activities were much lower than that of the fully formed catalysts.

2,6-Dimethoxyphenylphosphirane is readily converted to its oxide and sulfide whose pyrolysis and (perhaps) photolysis lead to the generation of phosphinidene chalcogenides Ar–P Z (Z=O,S). Trapping experiments were carried out under conditions similar to the kinetic studies of the phosphirane chalcogenide pyrolyses that confirmed the formation of free Ar–P Z. The trapping experiments were in accord with carbene-like character for Ar–P Z, and the activation parameters suggest a non-least motion pathway for the addition of Ar–P Z to olefins. This represents quantitative evidence for the validity of the predictions of frontier-orbital theory for species that undergo reactions with small (or no) enthalpic barriers.

2,6-Dimethoxyphenylphosphetane sulfide has been synthesized by condensation of 2,6-dimethoxyphenylphosphine with 1,3-propanediol ditosylate and treatment of the resulting phosphetane with sulfur. Irradiation at 254 nm of the phosphetane sulfide was undertaken to determine the mode of photodissociation and the types of reactive intermediates produced. Evidence is presented for the formation of both the corresponding arylphosphinidene sulfide ArPS and the methylene(thioxo)phosphorane ArP(S)CH2 as transient species.

Pyrolysis and photolysis of phosphiranes and their chalcogenides provide routes for the generation of phosphinidenes R-P and their chalcogenides R-P=Z (Z = O,S). Kinetic studies of the pyrolyses allow the elucidation of the mechanisms of the addition reactions of R-P and R-P=Z. Results are in accord with predictions of frontier orbital theory, including alteration of reactivity by manipulation of frontier orbital symmetry.

2,6-Dimethoxyphenylphosphetane sulfide has been synthesized by condensation of 2,6-dimethoxyphenylphosphine with 1,3-propanediol ditosylate and treatment of the resulting phosphetane with sulfur. Irradiation at 254 nm of the phosphetane sulfide was undertaken to determine the mode of photodissociation and the types of reactive intermediates produced. Evidence is presented for the formation of both the corresponding arylphosphinidene sulfide ArPS and the methylene(thioxo)phosphorane ArP(S)CH2 as transient species.

Both 2-phenyl-2-furylhexamethyltrisilane (1) and 2-phenyl-2-thienylhexamethyltrisilane (2) were synthesized by conventional organometallic reactions. The photolysis of 1 in the presence of 2,3-dimethyl-1,3-butadiene led to normal silylene-olefin addition and silylene CH insertion reactions. However, when 2 was photolyzed in a methanol-cyclohexene system, an apparent radical reaction occurred. We suspect that the sulfur atom of the thienyl group strongly stabilizes a silyl radical. This result was supported by both identifying its typical radical reaction products and examining the ESR spectrum of its adduct with a radical trap.

We investigate the influence of visible light on domain inversion in Mg-doped near stoichiometric lithium niobate crystals and find that the switching electric field decreases about 70% above a threshold light intensity. This effect helps us optically control domain switching and produce bulk domain structures on the micrometre scale. Finally, we introduce a model of photo-induced carriers to explain the origin of the reduction of switching electric field.