Structural Diversity of Six Coordination Polymers Based on the Designed X-Shaped Ligand 1,1,1,1-Tetrakis[(3-pyridiniourea)methyl]methane.

In this study, six coordination polymers (CPs), {[Ag2(L)(CF3SO3)]·CF3SO3·2H2O·DMF}n (1), {[Ag(L)]·SbF6·4DMF·H2O}n (2), {[Zn(L)0.5(I)2]·3.75H2O}n (3), {[Cd2(L)(I)4(H2O)(DMF)]·4H2O·3DMF}n (4), {[Hg2(L)(I)4]·H2O·4DMF}n (5) and {[Hg2(L)(Cl)4]·2H2O·3DMF}n (6), were obtained based on the designed X-shaped urea-based ligand. X-ray single crystal diffraction analysis revealed that complex 1 displayed a 3D (3,4)-connected {6·8²}{64·8²}-tcj net. Complex 2 featured a 2D 4-connected {4³·6³} sheet. Complexes 3 and 5 exhibited a 1D polymeric loop chain. Complex 4 displayed a 1D polymeric fishbone chain. Complex 6 showed a 2D 4-connected {44·6²}-sql sheet. Structural comparison revealed that not only the metal ions, but also the anions played crucial roles in the control of final structures.

Au-PEDOT/rGO nanocomposites functionalized graphene electrochemical transistor for ultra-sensitive detection of acetaminophen in human urine.

A novel graphene electrochemical transistor (GECT) sensor based on Au-poly(3,4-ethylenedioxythiophene)/reduced graphene oxide (Au-PEDOT/rGO) nanocomposites functionalized the gate electrode and monolayer graphene as channel was proposed and constructed for the ultra-sensitive detection of acetaminophen (AP). Au-PEDOT/rGO nanocomposites were synthesized by a simple one-pot method to modify the gate electrode of GECT. With the high catalytic activity of Au nanoparticles, the good conductivity and stability of PEDOT, the large specific surface area and abundant adhesion sites of rGO, the sensitivity and stability of the device for AP detection could be effectively improved. The sensing mechanism of the device was that the electrochemical reactions of the AP on the surface of gate electrode causes the effective gate voltage on the GECT to change, thereby adjusting the carrier concentration and current of the graphene channel. Combined with the excellent catalytic properties of Au-PEDOT/rGO nanocomposites and the high carrier mobility of the graphene channel, the resulting device has remarkable sensing performance for AP, with a detection limit as low as 1 nM and a linear range from 1 nM to 8 mM. In addition, the device has good anti-interference ability and accuracy in the detection of AP in urine samples and tablets, which proved that it could be used to determine AP in human non-invasive and pharmaceutical products. The GECT sensor based on Au-PEDOT/rGO provides an efficient, sensitive and cost-effective sensing platform for AP detection, and is expected to realize in vitro diagnosis of diseases.

Solvent evaporation induced aggregating assembly approach to three-dimensional ordered mesoporous silica with ultralarge accessible mesopores.

A solvent evaporation induced aggregating assembly (EIAA) method has been demonstrated for synthesis of highly ordered mesoporous silicas (OMS) in the acidic tetrahydrofuran (THF)/H(2)O mixture by using poly(ethylene oxide)-b-poly(methyl methacrylate) (PEO-b-PMMA) as the template and tetraethylorthosilicate (TEOS) as the silica precursor. During the continuous evaporation of THF (a good solvent for PEO-b-PMMA) from the reaction solution, the template molecules, together with silicate oligomers, were driven to form composite micelles in the homogeneous solution and further assemble into large particles with ordered mesostructure. The obtained ordered mesoporous silicas possess a unique crystal-like morphology with a face centered cubic (fcc) mesostructure, large pore size up to 37.0 nm, large window size (8.7 nm), high BET surface area (508 m(2)/g), and large pore volume (1.46 cm(3)/g). Because of the large accessible mesopores, uniform gold nanoparticles (ca. 4.0 nm) can be introduced into mesopores of the OMS materials using the in situ reduction method. The obtained Au/OMS materials were successfully applied to fast catalytic reduction of 4-nitrophenol in the presence of NaHB(4) as the reductant. The supported catalysts can be reused for catalytic reactions without significant decrease in catalysis performance even after 10 cycles.

Facile synthesis of hierarchically mesoporous silica particles with controllable cavity in their surfaces.

Novel and uniform mesoporous silica particles with controllable cavities in their surface have been fabricated using PAA and CTAB as dual templates in a mild reaction system. Herein, a series of hierarchically distinct silica particles can be obtained by simply adjusting the mass ratios (R) of PAA to CTAB. When the R value continues to decrease, the corresponding number and opening size of these cavities are also increased. However, if no PAA added, only unique monodisperse mesoporous silica spheres with uniform size of approximately 400 nm can be obtained. These specific silica particles were characterized by means of small-angle X-ray diffraction (XRD), scanning electron microscope (SEM), transmission electron microscope (TEM), Fourier-transform infrared (FT-IR) spectra, and nitrogen adsorption-desorption measurements. Results show that these unique mesoporous silica particles totally behave as an hexagonally ordered mesophase. The maximum BET surface area can be as high as 891 m(2)/g, and the maximum pore volumes can be as large as 0.27 cm(3)/g. Notably, the specific cavity features including opening size and cavity number almost do not change after calcination treatment. Moreover, a possible formation mechanism of the hierarchically distinct silica particles has been put forward, considering that the specific interface instability effect, the reduction in the surface free energy, and the synergic self-assembly of PAA and CTAB in solution can play a key role in mediating the formation of the hierarchical silica nanostructures. In general, the synthesis route is simple and straightforward for the preparation of the other biomineral nanostructures and may play an important role in microencapsulation.

Comparative efficacy and safety of local and peripheral venous thrombolytic therapy with urokinase for thrombosed hemodialysis arteriovenous fistulas.

Arteriovenous fistula (AVF) thrombosis is a common complication in patients undergoing hemodialysis, and early intervention is required. Urokinase has been used as a thrombolytic agent for declotting the thrombosed access. However, the optimal route for infusing urokinase remains to be determined. In the present retrospective observational study, 49 patients who underwent local venous infusion and 57 patients with peripheral venous infusion of urokinase were included. A urokinase dosage of 300,000 U was administered until successful thrombolysis, which was a maximum of three times. Age, sex, period of dialysis, time of AVF placement, systolic and diastolic blood pressure and thrombus age were similar between the two groups. The efficacy of urokinase infusion via the two routes in resolving thrombosed AVFs, defined as successful fibrinolysis, and the safety, defined as the number of bleeding events, was compared. The cumulative thrombolysis success rate following three sessions of thrombolytic therapy in the local venous thrombolysis group was higher compared with that in the peripheral venous thrombolysis group (85.7 vs. 68.4%; P=0.04). The local thrombolysis group exhibited less ecchymosis (4.1 vs. 14.0%; P=0.07), epistaxis (2.0 vs. 10.5%; P=0.08) and gingival bleeding (4.1 vs. 19.3%; P=0.02) events compared with the peripheral thrombolysis group. Further analyses demonstrated that systolic [odds ratio (OR)=1.10; 95% confidence interval (CI), 1.03-1.17; P<0.01] and diastolic (OR=1.08; 95% CI, 1.02-1.14; P<0.05) blood pressure were protective factors, whereas thrombus age (OR=0.91; 95% CI, 0.84-0.99; P<0.05) was a risk factor for thrombolysis success among patients who underwent local thrombolytic therapy. Overall, the results suggest that local venous infusion of urokinase is superior to peripheral venous infusion for the treatment of patients with thrombosed fistulas.

Direct triblock-copolymer-templating synthesis of ordered nitrogen-containing mesoporous polymers.

Ordered nitrogen-containing mesoporous carbonaceous polymers have been synthesized via a direct triblock-copolymer-templating process by using soluble, low-molecular-weight urea-phenol-formaldehyde (UPF) resin as an organic precursor and amphiphilic triblock copolymer Pluronic F127 as a template. Characterization using small-angle X-ray scattering (SAXS), N(2) sorption, transmission electron microscopy (TEM), elemental analysis, thermogravimetric analysis (TG), Fourier transform infrared (FTIR), and water adsorption techniques reveals that the obtained nitrogen-containing mesoporous polymers possess ordered structures, high surface areas (385-420 m(2)/g), large pore sizes (3.1-3.6nm) and pore volumes (0.25-0.44cm(3)/g), and high nitrogen content (2.69-2.94%). Various mesostructures, such as two-dimensional (2-D) hexagonal (space group, p6mm) and 3-D body-centered cubic (Im3 m) symmetries, can be obtained by simply adjusting the mass ratio of UPF/F127. The content of nitrogen in the mesoporous polymers can also be easy varied by changing the amount of urea and the reaction time of UPF resin precursors. Compared with the nitrogen-free mesoporous polymer, the obtained mesoporous carbonaceous polymers show a more hydrophilic nature and thus evidently higher water adsorption capacity. The presence of nitrogen groups can also significantly improve the adsorption performance of Fe(III) ions.

A "teardown" method to create large mesotunnels on the pore walls of ordered mesoporous silica.

A "teardown" method to create large mesotunnels (approximately 9 nm) on the pore walls of ordered mesoporous silicas is demonstrated by digesting the organic constituents from polymer-silicate nanocomposites. The ordered mesostructured polymer-silicate composites were first obtained via the evaporation-induced triconstituent co-assembly method by using a low-molecular-weight phenolic resin (resols) as an organic precursor; prehydrolyzed TEOS as an inorganic precursor, and triblock copolymer F127 as a template. All of organic components including F127 and phenolic resins are removed by the microwave digestion (MWD) method from mesostructured polymer-silica composites. While the removal of triblock copolymer F127 generates main pore channels, the phenolic resins can also be torn down from the pore walls, yielding mesotunnels between the channels. The resulting silica products exhibit ordered 2-D hexagonal mesostructure, large pore volume (up to 1.92 cm(3)/g), and very large pore size (up to 22.9 nm), which is even larger than their mesostructural cell parameter (14.2 nm). TEM images confirm the existence of mesotunnels on the silica pore walls. FT-IR and (29)Si solid-state NMR results reveal that these silica products have a large number of silanol groups.

Highly ordered mesoporous carbonaceous frameworks from a template of a mixed amphiphilic triblock-copolymer system of PEO-PPO-PEO and reverse PPO-PEO-PPO.

A series of highly ordered mesoporous carbonaceous frameworks with diverse symmetries have been successfully synthesized by using phenolic resols as a carbon precursor and mixed amphiphilic surfactants of poly(ethylene oxide)-b-poly(propylene oxide)-b-poly(ethylene oxide) (PEO-PPO-PEO) and reverse PPO-PEO-PPO as templates by the strategy of evaporation-induced organic-organic self-assembly (EISA). The transformation of the ordered mesostructures from face-centered (Fd3m) to body-centered cubic (Im3m), then 2D hexagonal (P6mm), and eventually to cubic bicontinuous (Ia3d) symmetry has been achieved by simply adjusting the ratio of triblock copolymers to resol precursor and the relative content of PEO-PPO-PEO copolymer F127, as confirmed by small-angle X-ray scattering (SAXS), transmission electron microscopy (TEM), and nitrogen-sorption measurements. The blends of block copolymers can interact with resol precursors and tend to self-assemble into cross-linking micellar structures during the solvent-evaporation process, which provides a suitable template for the construction of mesostructures. The assembly force comes from the hydrogen-bonding interactions between organic mixed micelles and the resol-precursor matrix. The BET surface area for the mesoporous carbonaceous samples calcined at 600 degrees C under nitrogen atmosphere is around 600 m2 g(-1), and the pore size can be adjusted from 2.8 to 5.4 nm. An understanding of the organic-organic self-assembly behavior in the mixed amphiphilic surfactant system would pave the way for the synthesis of mesoporous materials with controllable structures.