Small-angle X-ray Diffraction Patterns Research Articles

Using Multiscale Simulations as a Tool to Interpret Equatorial X-ray Fiber Diffraction Patterns from Skeletal Muscle.

Synchrotron small-angle X-ray diffraction is the method of choice for nm-scale structural studies of striated muscle under physiological conditions and on millisecond time scales. The lack of generally applicable computational tools for modeling X-ray diffraction patterns from intact muscles has been a significant barrier to exploiting the full potential of this technique. Here, we report a novel "forward problem" approach using the spatially explicit computational simulation platform MUSICO to predict equatorial small-angle X-ray diffraction patterns and the force output simultaneously from resting and isometrically contracting rat skeletal muscle that can be compared to experimental data. The simulation generates families of thick-thin filament repeating units, each with their individually predicted occupancies of different populations of active and inactive myosin heads that can be used to generate 2D-projected electron density models based on known Protein Data Bank structures. We show how, by adjusting only a few selected parameters, we can achieve a good correspondence between experimental and predicted X-ray intensities. The developments presented here demonstrate the feasibility of combining X-ray diffraction and spatially explicit modeling to form a powerful hypothesis-generating tool that can be used to motivate experiments that can reveal emergent properties of muscle.

Ionic Liquid-Intercalated Montmorillonite Interfacial-Reinforced Polymer Composite Scaffold

Montmorillonite is often used to enhance the mechanical and biological properties of polymer materials, but the weak interaction between the enhanced phase and the matrix limits the enhancement effect. Herein, ionic liquids were introduced as interfacial compatibilizer to improve the dispersion of the enhanced phase in the matrix and interaction between them, and a composite scaffold with enhanced mechanical properties was prepared by selective laser sintering. Specifically, the positively charged terminations of 1-n-butyl-3-methylimidazolium in ionic liquids were anchored to the montmorillonite interlayer domain under electrostatic action. At the same time, the long carbon chain at the other end extends in the opposite direction to increase the layer spacing of the montmorillonite, which provides enough space for the intercalation of the polyetheretherketone molecular chain. First, the blue shift of the diffraction peak in the small-angle X-ray diffraction pattern proves the successful insertion of ionic liquids into the interlayered domain of montmorillonite. In addition, the compression test results show that the compressive strength of the modified composite scaffold was increased by 23%, reaching 31.53 MPa. Besides, the composite scaffold exhibits good biomineralization capacity, which may be attributed to ion modification providing more apatite-shaped nucleation sites. These results suggested that the method of modifying inorganic fillers with ionic liquids to enhance mechanical properties and promote mineralization may be an effective means for bone scaffold modification.

Abstract P505: Rv Sarcomeres From Lv-hfref Patients With Low Papi Have Abnormal Rv Thick Filament Structure

Patients with left heart failure and reduced ejection fraction (HFrEF) have variable RV failure that, if present, drastically worsens outcomes. In a cohort of 21 HFrEF patients from two hospital sites, we have previously shown (Aslam et al, Eur J HF; 2020: volume 23, pages 339-341) that like global function, RV myocyte maximum calcium-activated myocyte tension (T max ) is quite variable (COV 27%). To determine if a relationship between RV myocyte function and indices of RV chamber function exists, we trained a random forest classifier based on 41 clinical variables, including hemodynamic, laboratory, and echocardiographic data, and queried the importance of each. This revealed that the most predictive model for reduced T max was based on the pulmonary artery pulsatility index (PAPi), an established clinical index of RV failure. To gain insight into potential mechanisms for depressed T max in HFrEF patients with a low PAPi, we obtained small angle x-ray diffraction patterns in 5 HFrEF patients with depressed PAPi and T max and compared this to 5 non-failing (NF) controls. The equatorial intensity ratio I(1,1)/I(1,0) was reduced in low T max RV muscle fibers vs. controls (0.250.06 vs. 0.180.02, P<0.0001), suggesting myosin heads are more associated with the thick filament backbone. In meridional reflections, we find a significant decrease in M3 band spacing (14.340.03 nm in NF vs. 14.300.01 nm in HFrEF; P=0.0013) suggesting more myosin heads are in the “OFF” configuration. The latter may underly tension reduction in RV myocytes from failing RV HFrEF patients. Ongoing studies will examine these structural changes in HFrEF patients with a broader range of PAPi and T max to test if this association applies. These findings focus attention on thick filament structural and configuration abnormalities as potential culprits underlying RV disease in HFrEF. Further studies using novel sarcomere enhancers will test if these changes can be remedied, and if so, in which patients.

Surface Functionalization of Doxorubicin loaded MCM-41 Mesoporous Silica Nanoparticles by 3-Aminopropyltriethoxysilane for Selective Anticancer 9 Effect on A549 and A549/DOX Cells

In this study, MCM-41 mesoporous silica nanoparticles were successfully synthesized by the condensation of a tetraorthosilicate precursor on a template self-assembled by cetyltrimethylammonium bromide in alkaline. The small-angle x-ray diffraction patterns of MCM-41 indicate that silica nanoparticles possess hexagonal structures with a high degree of structural ordering. Transmission electron microscopy images show that the size of the MCM-41 particles is around 100-120 nm, and the pore sizes range from 2 nm to 4 nm. In addition, the specific surface area of MCM-41 obtained by Brunauer–Emmett–Teller analysis is as high as 987 m2.g−1 and the pore size extracted from nitrogen physical adsorption isotherms is in accordance with the TEM result. Thermogravimetric analysis, Fourier-transform infrared spectroscopy, Zeta potential measurements and photoluminescence measurements show that 3-aminopropyltriethoxysilane (APTES) and doxorubicin were grafted and loaded successfully onto MCM-41 nanoparticles. An assay on fibroblasts, A549 and doxorubicin-resistant A549/DOX cells indicates that the prepared MCM41 grafting APTES nanoparticles are safe to normal cells and toxic to cancer cells in vitro.

Mesoporous KIT-6 supported Cr and Co-based catalysts for microwave-assisted non-oxidative ethane dehydrogenation

Abstract In the present study, mono and bi-metallic catalysts containing Cr and Co were prepared by impregnating the hydrothermally prepared mesoporous KIT-6 support with 5–10 wt% total metal content. The well-ordered three-dimensional mesoporous structure of the KIT-6 support was confirmed by small angle X-ray diffraction (XRD) patterns. N2 adsorption-desorption analysis results showed that the mesoporous structure of KIT-6 was preserved after metal loading. Structural bonds of KIT-6 support and prepared catalysts were determined by Fourier-transform infrared (FT-IR) spectroscopy. The pyridine adsorbed diffuse reflectance FT-IR (DRIFT) spectroscopy results revealed the presence of Lewis acid sites on the surface of the catalysts. Activity experiments were carried out in a microwave-heated continuous-flow fixed bed reactor system at temperature range of 350–650 °C and feed ratios of Ethane/Argon: 1/2, 1/1, 2/1 with a gas hourly space velocity (GHSV) of 18,000 ml/h.gcat. The 5Cr@KIT-6 catalyst exhibited high ethane conversion (63.5%) while the highest ethylene/hydrogen ratio (0.98) was obtained with the 2.5Cr2.5Co@KIT-6 catalyst at 450 °C. It was concluded that high temperatures (above 450 °C) facilitate the formation of side reactions and the production of aromatic compounds. The high catalytic activities of mesoporous catalysts were thought to be due to hot spots in the microwave reactor system.

Mixed Metal Oxide Mesoporous Nanoparticles For Environmental Remediation

Mesoporous mixed metal oxides (SnO2(x) -TiO2 (1-x) , x= 0.75,0.50 and 0.25) were synthesized by evaporation induced self assembly using cationic surfactant, Cetyl Trimethyl Ammonium Bromide (CTAB) as the structure directing agent. The small angle X-ray diffraction pattern of mesoporous SnO2 and SnO2-TiO2 mixed metal oxides revealed the presence of well defined mesostructure in the metal oxides. The mixed metal oxide system has crystallized in orthorhombic structure, resembling the host lattice. Mesopore channels were collapsed upon calcinations at 550°C. The optical absorption of the SnO2 has been extended into the visibleregion upon incorporation of “Ti”. A remarkable enhancement of the photocatalytic degradation efficiency (60% ) of (SnO2(0.5) -TiO2 (0.5) was observed against aqueous solution of methylene blue dye.

Influence of processing parameters on barrier properties of nitrile rubber/nanoclay nanocomposite membrane against organic solvent

The present study focuses on the influence of layered silicate nanoparticles on barrier properties of a rubber/nanoclay nanocomposite (RCN). Most of the previous works deal with the importance of the surface chemistry of the nanoclay on the performance of the material. In this paper were rather investigated the effect of the processing conditions. Elastomer nanocomposites based on nitrile butadiene rubber and layered silicate nanoparticles were prepared using three different techniques: chemical dissolution, mixing in an internal mixer and melt-mixing with a twin-screw extruder. Chemical resistance to methanol was assessed using gravimetric method and mass transfer kinetic parameters were then deduced. Mass uptake results clearly showed that extruded RCN exhibited the highest chemical resistance. Barrier properties were subsequently correlated to the morphological structure of the rubber/nanoclay system. Small-angle X-ray diffraction patterns indicated that this improvement was due to a preferred alignment of the nanoparticle in the structure. Further, inspection revealed an anisotropic orientation profile of the nanoclay layers over the thickness of a sheet-like extruded material. In addition, a neat decrease of chemical sorption was spotted with mixing and chemically processed RCN materials over the unfilled rubber. The state of dispersion of clay nanoparticles was also probed in these nanocomposites using X-ray diffraction. The findings suggested an intercalation during processing. Further, transmission electron microscopy observations were suggesting a bimodal state of dispersion over spotting individual nClay platelets along with the layered stacks. Improvement of mass transport kinetic parameters was recorded over increasing the shear stress as well as the residence time when RCN were prepared in the internal mixer.

Synthesis of a high-surface area V2O5/TiO2-SiO2 catalyst and its application in the visible light photocatalytic degradation of methylene blue.

In the present study, we synthesized several high-surface area V2O5/TiO2–SiO2 catalysts (vanado titanium silicate, VTS). The synthesized materials were characterized by PXRD, FE-SEM/EDAX, TEM, FTIR, UV-Vis, XPS, fluorescence and photocatalytic activity studies. The small-angle powder X-ray diffraction pattern shows that the 110 and 200 planes are merged to become a single broad peak. Field-emission scanning electron microscopy shows that the titanosilicate is spherical in shape and V2O5 has a hexagonal rod-shaped morphology. The presence of various metal ions, such as V, Ti, Si and O, was observed by energy dispersive X-ray analysis and X-ray photoelectron spectroscopy. The transmission electron microscopy image shows clear hexagonal mesoporous fringes with V2O5 distribution. The BET surface area analysis shows that the VTS catalysts have higher surface areas than pure V2O5. Fourier transform infrared spectroscopic analysis shows the presence of Ti4+ ions connected to the silanol groups. The bandwidths of pure titanosilicate, V2O5 and their composites were calculated from their diffuse reflectance ultraviolet-visible spectra. The bandwidth was tuned by heterojunctions in the studied catalysts. The photoluminescence spectra of the VTS catalysts show a distinct behaviour as compared to those of the pure components. The photocatalytic activity of methylene blue degradation was determined with pure constituents and catalysts. VTS-1 (TS and VO weight ratio 2 : 1) shows higher conversion than other catalysts, pure titanosilicate and V2O5. This is probably due to the heterojunctions and higher surface area in VTS-1. Kinetic studies reveal that direct sunlight shows higher activity than pure visible light. A plausible physical and chemical mechanism for the photocatalytic activity is proposed.

One-Pot Hydrothermal Synthesis of Benzalkonium-Templated Mesostructured Silica Antibacterial Agents.

Novel mesostructured silica microparticles are synthesized, characterized, and investigated as a drug delivery system (DDS) for antimicrobial applications. The materials exhibit a relatively high density (0.56 g per 1 g SiO2) of benzalkonium chloride (BAC), pore channels of 18 Å in width, and a high surface area (1500 m2/g). Comparison of the small-angle X-ray diffraction (SAXRD) pattern with Barrett-Joyner-Halenda (BJH) pore size distribution data suggests that the 18 Å pores exhibit short-range ordering and a wall thickness of ca. 12 Å. Drug release studies demonstrate pH-responsive controlled release of BAC without additional surface modification of the materials. Prolonged drug release data were analyzed using a power law (Korsmeyer-Peppas) model and indicate substantial differences in release mechanism in acidic (pH 4.0, 5.0, 6.5) versus neutral (pH 7.4) solutions. Microbiological assays demonstrate a significant time-dependent reduction in Staphylococcus aureus and Salmonella enterica viability above 10 and 130 mg L-1 of the synthesized materials, respectively. The viability of cells is reduced over time compared to control samples. The findings will help in widening the use of BAC as a disinfectant and bactericidal agent, especially in pharmaceutical and food industries where Gram-positive and Gram-negative bacterial contamination is common.

Molecular simulation and experimental validation of resorcinol adsorption on Ordered Mesoporous Carbon (OMC)

Numerous research works have been devoted in the adsorption area using experimental approaches. All these approaches are based on trial and error process and extremely time consuming. Molecular simulation technique is a new tool that can be used to design and predict the performance of an adsorbent. This research proposed a simulation technique that can greatly reduce the time in designing the adsorbent. In this study, a new Rhombic ordered mesoporous carbon (OMC) model is proposed and constructed with various pore sizes and oxygen contents using Materials Visualizer Module to optimize the structure of OMC for resorcinol adsorption. The specific surface area, pore volume, small angle X-ray diffraction pattern, and resorcinol adsorption capacity were calculated by Forcite and Sorption module in Materials Studio Package. The simulation results were validated experimentally through synthesizing OMC with different pore sizes and oxygen contents prepared via hard template method employing SBA-15 silica scaffold. Boric acid was used as the pore expanding reagent to synthesize OMC with different pore sizes (from 4.6 to 11.3 nm) and varying oxygen contents (from 11.9% to 17.8%). Based on the simulation and experimental validation, the optimal pore size was found to be 6 nm for maximum adsorption of resorcinol.

Computer Simulation Studies of Structure Characteristics of Ordered Mesoporous Carbons and its Naphthalene Adsorption Performance

Through naphthalene-adsorption experiments, we were able to draw some valuable conclusions about adsorption capacity, the adsorption isotherm, adsorption kinetics, and adsorption thermodynamics, although the experiments could not directly reveal the exact location and state of adsorption on the surface of ordered mesoporous carbons (OMCs). In fact, due to the restrictions of characterization technology, human factors, and experimental conditions, we still do not understand the microscopic structure of OMCs very well. However, molecular simulation technology could compensate for these disadvantages. In this study, the Grand Canonical Monte Carlo method has been used to simulate the naphthalene adsorption behavior in the OMC-structure model for the first time. The atomic structure model of OMCs was built firstly by using molecular modeling techniques and was characterized by calculating the accessible solvent surface area, total pore volume, and small-angle X-ray diffraction patterns. The calculated results showed that the structural model of OMCs was reasonable and that the structural characteristics were in agreement with experimental data. The adsorption isotherm curve is of the type Langmuir IV, which is a typical characteristic of ordered mesoporous materials. Also, the adsorption isotherm curve revealed that the adsorption capacity of naphthalene on OMCs gradually increased to a balance, with the maximum capacity reaching 105.4 mg g–1. Additionally, as the number of naphthalene molecules increased, the adsorption state was observed progressing from a monolayer to a multilayer state in the mesopores. This work deepened the understanding of the adsorption state of naphthalene for OMCs on the mesoscopic level. It also demonstrated that the GCMC method is effective for studying the adsorption process and gives useful guidance on research of the structure-activity relationship and performance prediction of carbon material.

Physicochemical properties of a high molecular weight levan from Brenneria sp. EniD312

A high molecular weight levan was produced by a novel levansucrase and some properties of this polymer were investigated. The levan exhibited a poroid microstructure as well as series of individual ellipsoidal or spheroidal particles. The weight-average molecular weight (M¯w) of the levan was determined to be 1.41×108Da. In a 0.1% solution, the levan showed a mean diameter of 176nm, while in a 1% solution the diameter was 182nm. The decomposition temperature was determined to be 216.67°C, with an endothermic peak at 147.41°C and a melting enthalpy of 76.9J/g. The small angle X-ray diffraction pattern showed a distinctive peak pattern between 15° and 40° (2q). The levan solution showed a shear-thinning behaviour. These results suggest this levan could be a good additive in the food processing industry, as well as an important bio-based material in the medicinal or chemical industry.

Novel and Economic Approach for Synthesis of Mesoporous Silica Template and Ordered Carbon Mesoporous By Using Cation Exchange Resin

Background: Porous carbon materials are promising candidate supports for various applications. Different approaches have been applied for preparation of various types of porous carbon materials which in the most of them; disordered structures as well as relatively broad pore size distribution are obtained. The most reliable method for preparing of the ordered carbon mesoporous is nano-casting using mesoporous silicas as a hard template. However one of the challenges in the nano-casting preparation is the mother silica template usually produced from expensive initial ingredients, complicated and consuming process. Therefore, in the present work, the synthesis of the ordered silica mesoporous using commercial water glass as the silica source is reported in which the silicic acid has been prepared using cation-exchange resin. Furthermore, the adsorption properties and phenolic compounds removal capability of the templated carbon mesoporous were compared with the mesoporous carbon prepared by SBA-15 and activated carbon. Method: The structural order and textural properties of the materials have been evaluated by SAXRD (Small Angle X-Ray Diffraction), SEM (Scanning Electron Microscopy), TEM (Transmission Electron Microscopy) and nitrogen adsorption–desorption analysis. Finally, the adsorption of phenolic compounds on the carbon mesoporous has been studied. Results: From SAXRD patterns it was deduced that the silicic acid amount has a considerable effect on the final order of the mesostructure. Also, the nitrogen adsorption-desorption isotherms of different silica samples represent Type IV isotherms. The formation of well-oredered hexagonal (P6mm) arrays of mesopores could be clearly observed from SEM and TEM micrographs. Moreover, the carbon templated from the optimized mesoporous silica revealed the well-ordered mesostructure along with type IV adsorption isotherm confirming the nanoporous carbon has been successfully templated. The microstructural images show the almost similar structure of the mother silica template. In addition, EDS analysis of the silica and carbon templated sample confirms the almost elimination of sodium. Finally, the performance the nanoporous carbon materials for phenolic compounds removal was investigated. It is noteworthy that the adsorption capacity and equilibrium point in the case of the prepared nanoporous carbon materials is very close to that of obtained for carbon prepared by SBA-15. Furthermore the results showed the mesoporous carbon samples exhibit considerably much higher adsorption capability in comparison to commercial activated carbon. Finally the kinetic evaluation indicates that the phenolic compounds adsorption is accordance to the pseudosecond- order kinetic model over the entire adsorption time. Conclusion: The impurity-free and well-ordered hexagonal mesoporous silica particles have been successfully synthesized by commercial water-glass using cation exchange resin. The resultant silica has high surface area (778.3 m2/g), pore volume (1.1 cm3 /g) and pore size (6.1 nm), completely comparable to mesoporous silica (SBA-15) produced by TEOS as a silica source. Moreover, the carbon nanoporous templated by the prepared mesoporous silica has a well ordered structure, high surface area (1033.9m2/g) and pore volume (1.08 cm3/g). Finally the results showed the prepared mesoporous carbon could be considered as a suitable candidate for phenolic compounds removal from water and waste water, as well. Furthermore, the experimental results also showed that the adsorption process and equilibrium data were well fitted by pseudo second-order kinetic. Keywords: Adsorption, 4-chlorophenol, phenol, mesoporous carbon, mesoporous silica, water glass, cation exchange.

Chitosan-rectorite nanospheres immobilized on polystyrene fibrous mats via alternate electrospinning/electrospraying techniques for copper ions adsorption

Chitosan (CS), as a kind of well characterized biopolymer, has been used for heavy metal adsorption due to its low cost and high efficacy. However, when used directly, chitosan particles had small surface area and weak mechanical strength which is unfavorable to metal adsorption and reused. Besides, it cannot be easily recycled that may cause a secondary pollution. In this paper, CS and layered silicate rectorite (REC) were fully mixed and the mixtures were subsequently electrosprayed nano-sized spheres, which were immobilized on the surface of electrospun polystyrene (PS) mats for metal adsorption. The morphology analysis taken from SEM confirmed that CS-REC nanospheres were loaded on the surface of PS fibrous mats. Small Angle X-ray diffraction patterns showed that the interlayer distance of REC in composite mats was enlarged by the intercalation of CS chains; such structure meant bigger surface area which was helpful for metal adsorption. The data of contact angle implied that PS mats coated with CS-REC nanospheres exhibited better hydrophilicity than PS mats, which was conductive to adsorption rate. Besides, the copper ions adsorption of composite mats was tested at different conditions including the adsorption time, the initial pH and the initial concentration of copper ion. The results demonstrated that PS mats coated with CS-REC nanospheres had the adsorption capacity up to 134mg/g. In addition, the addition of REC containing Ca2+ could also improve the metal adsorption because of cation exchange. The desorption assay indicated that PS mats immobilized with CS and CS-REC still kept high adsorption ability which retained 74% and 78% after three adsorption-desorption cycles.

Strategy for chemotherapeutic delivery using a nanosized porous metal-organic framework with a central composite design.

BackgroundEnhancing drug delivery is an ongoing endeavor in pharmaceutics, especially when the efficacy of chemotherapy for cancer is concerned. In this study, we prepared and evaluated nanosized HKUST-1 (nanoHKUST-1), nanosized metal-organic drug delivery framework, loaded with 5-fluorouracil (5-FU) for potential use in cancer treatment.Materials and methodsNanoHKUST-1 was prepared by reacting copper (II) acetate [Cu(OAc)2] and benzene-1,3,5-tricarboxylic acid (H3BTC) with benzoic acid (C6H5COOH) at room temperature (23.7°C±2.4°C). A central composite design was used to optimize 5-FU-loaded nanoHKUST-1. Contact time, ethanol concentration, and 5-FU:material ratios were the independent variables, and the entrapment efficiency of 5-FU was the response parameter measured. Powder X-ray diffraction, scanning electron microscopy (SEM), transmission electron microscopy (TEM), and nitrogen adsorption were used to determine the morphology of nanoHKUST-1. In addition, 5-FU release studies were conducted, and the in vitro cytotoxicity was evaluated.ResultsEntrapment efficiency and drug loading were 9.96% and 40.22%, respectively, while the small-angle X-ray diffraction patterns confirmed a regular porous structure. The SEM and TEM images of the nanoHKUST-1 confirmed the presence of round particles (diameter: approximately 100 nm) and regular polygon arrays of mesoporous channels of approximately 2–5 nm. The half-maximal lethal concentration (LC50) of the 5-FU-loaded nanoHKUST-1 was approximately 10 µg/mL.ConclusionThe results indicated that nanoHKUST-1 is a potential vector worth developing as a cancer chemotherapeutic drug delivery system.

SBA-15:TiO2 nanocomposites. I. Synthesis with ionic liquids and properties

Nanosized titanium dioxide (TiO2) has been extensively studied due to its unique properties and broad applicability. However, to our knowledge, the assessment on how reaction media and synthesis routes affect TiO2 properties synthesized with SBA-15 type mesoporous silica is unprecedented. In this work, SBA-15/TiO2 nanocomposites were prepared in different reaction media, varying ionic liquids (CMITf2N and CMIBF4) with and without isopropyl alcohol. X-ray diffraction results showed that CMIBF4 greatly favors TiO2 anatase crystalline phase, and a single phase material was obtained using 0.032 of CMIBF4 without alcohol. On the other hand, the presence of CMITf2N slightly favored TiO2 rutile crystalline phase. Small Angle X-ray diffraction patterns revealed that ordered mesoporous SBA-15/TiO2 nanocomposites were obtained with lower ionic liquid concentration, whilst materials prepared with higher concentration lost their ordered mesoporous structure. Scanning electron microscopy images showed that materials prepared with ionic liquid and isopropyl alcohol displayed much smaller SBA-15 particle size: around 0.1 μm, instead of the standard 1 μm. Nitrogen adsorption–desorption analysis showed that the nanocomposites exhibited a narrow pore size distribution with high surface areas of up to 680 m2/g, pore volumes of up to 1.8 cm3/g and mean pore diameter of up to 10.4 nm, thus being very promising for application in photocatalysis and photoprotection.

X-ray recordings reveal how a human disease-linked skeletal muscle α-actin mutation leads to contractile dysfunction.

In humans, mutant skeletal muscle α-actin proteins are associated with contractile dysfunction, skeletal muscle weakness and a wide range of primarily skeletal muscle diseases. Despite this knowledge, the exact molecular mechanisms triggering the contractile dysfunction remain unknown. Here, we aimed to unravel these. Hence, we used a transgenic mouse model expressing a well-described D286G mutant skeletal muscle α-actin protein and recapitulating the human condition of contractile deregulation and severe skeletal muscle weakness. We then recorded and analyzed the small-angle X-ray diffraction patterns of isolated membrane-permeabilized myofibers. Results showed that upon addition of Ca(2+), the intensity changes of the second (1/19 nm(-1)) and sixth (1/5.9 nm(-1)) actin layer lines and of the first myosin meridional reflection (1/14.3 nm(-1)) were disrupted when the thin-thick filament overlap was optimal (sarcomere length of 2.5-2.6 μm). However these reflections were normal when the thin and thick filaments were not interacting (sarcomere length>3.6 μm). These findings demonstrate, for the first time, that the replacement of just one amino acid in the skeletal muscle α-actin protein partly prevents actin conformational changes during activation, disrupting the strong binding of myosin molecules. This leads to a limited myosin-related tropomyosin movement over the thin filaments, further affecting the amount of cross-bridges, explaining the contractile dysfunction.

Synthesis and Luminescence of Eu‐N2,N6‐Bis(2‐hydroxyethyl)pyridine‐2,6‐dicarboxamide Complexes Containing Mesoporous Material

AbstractLigand N2,N6‐bis(2‐hydroxyethyl)pyridine‐2,6‐dicarboxamide (L=BHPC) was synthesized and used to construct lanthanide‐based mesoporous material Eu‐L‐MCM‐41. In the structure of resulting Eu‐L‐MCM‐41, Eu3+ was chelated by BHPC, and the Eu‐L complexes were anchored into the forming MCM‐41 host by the reaction between the hydroxyl group and active Si‐OH. The mesoporous material Eu‐L‐MCM‐41 was characterized by UV, IR, small‐angle X‐ray diffraction (SAXRD) patterns, nitrogen adsorption/desorption isotherms, TGA and fluorescence spectra. The results indicate that ligand and Eu3+ have been introduced into the MCM‐41 host, and Eu‐L‐MCM‐41 exhibits characteristic luminescence of Eu3+.

Synthesis of lanthanide-based SBA-15 mesoporous hybrids by a novel route

AbstractThe ligand N

Bidentate salen Cu(II) complex functionalized on mesoporous MCM-41 as novel nano catalyst for the oxidative coupling of thiols into disulfides using urea hydrogen peroxide (UHP)

Functionalized Copper(II) complex into nano dimensional mesoreactor was successfully prepared. The Copper(II) complex with N–O donor Schiff base ligand was readily trapped into mesoporous silica MCM-41 through the post grafting method. N–O Chelating Schiff-base-MCM-41 has been derived from 5-bromo-salicylaldehyde and 3-aminopropyltriethoxysilane which was functionalized on MCM-41 via silicon alkoxide route. This compound was characterized by FT-IR, TGA, small angle X-ray diffraction patterns, ICP/MS analysis and N2 sorption–desorption analysis. The catalytic property of Cu–salen–MCM-41 was considered for the preparation of disulfides using urea hydrogen peroxide as oxidant. The reaction progress is simple and proceeds under mild and heterogeneous conditions in acetonitrile at the ambient of temperature. The corresponding disulfides have been achieved with high purity and good to excellent yields; also, no over oxidation to sulfoxide or sulfone was observed in all cases. The catalyst can be recovered and reused several times without significant loss of stability and activity.