A novel cellulose/chitosan composite nanofiltration membrane prepared with piperazine and trimesoyl chloride by interfacial polymerization.

Bamboo cellulose (BC) is one of the most abundant renewable, hydrophilic, inexpensive, and biodegradable organic materials. The cellulose membrane is one of the best materials for replacing petroleum-based polymer films used for water purification. In this study, -methylmorpholine--oxide (NMMO) was used as a solvent to dissolve cellulose and chitosan, and a regenerated cellulose/chitosan membrane (BC/CSM) was prepared by phase inversion.

Chitosan/ nanofibrillated cellulose aerogel with highly oriented microchannel structure for rapid removal of Pb (II) ions from aqueous solution.

Among the heavy metal ions, Pb (II) can cause serious diseases in the nervous and cardiovascular systems even at an ultralow concentration. Nowadays, various materials with high adsorption capacity have been developed for heavy metal ions adsorption. However, most of them have a low adsorption rate and may take a long time to achieve adsorption equilibrium.

A three-dimensional DNA walker amplified FRET sensor for detection of telomerase activity based on the MnO nanosheet-upconversion nanoparticle sensing platform.

A novel fluorescent sensing platform for telomerase activity assay was developed by coupling a three-dimensional (3D) DNA walker with the MnO nanosheet-upconversion nanoparticle (UCNPs) complex-based fluorescence resonance energy-transfer (FRET) system.

Inhalation Exposure Analysis of Lung-Inhalable Particles in an Approximate Rat Central Airway.

Rats have been widely used as surrogates for evaluating the adverse health effects of inhaled airborne particulate matter. This paper presents a computational fluid and particle dynamics (CFPD) study of particle transport and deposition in an approximate rat central airway model. The geometric model was constructed based on magnetic resonance (MR) imaging data sourced from previous study.

Insight into the rheological behaviors of a polyanionic collagen fabricated with poly(γ-glutamic acid)-NHS ester.

The rheological behaviors of a polyanionic collagen, fabricated using poly(γ-glutamic acid)-N-hydroxysuccinimide (γ-PGA-NHS) as a novel modifier, were investigated in this study. It was found that both of the native and modified collagen solutions were pseudoplastic fluids, as shown from the steady-shear tests. While the storage modulus and loss modulus of collagen increased with increasing the amount of γ-PGA-NHS, or with increasing the degree of esterification of γ-PGA-NHS; meanwhile, the dynamic denaturation temperature determined by dynamic temperature sweep was also increased, indicating an improved thermal stability of collagen solution modified by γ-PGA-NHS.

Dual-functionalized hyaluronic acid as a facile modifier to prepare polyanionic collagen.

Hyaluronic acid (HA) is a natural polysaccharide possesses outstanding physiological activities. In this work, HA was activated as a novel collagen modifier via the esterification reaction between N-hydroxysuccinimide (NHS) and the carboxyl groups of HA. Both of Fourier transform infrared spectroscopy (FTIR) and H- nuclear magnetic resonance (NMR) spectra indicated the successful synthesis of HA-NHS esters.

Rheology, Non-Isothermal Crystallization Behavior, Mechanical and Thermal Properties of PMMA-Modified Carbon Fiber-Reinforced Poly(Ethylene Terephthalate) Composites.

Poly(ethylene terephthalate) (PET) composites containing carbon fiber (CF) or polymethyl methacrylate (PMMA)-grafted carbon fiber (PMMA-g-CF) were prepared by melt compounding. The rheology, non-isothermal crystallization behavior, and mechanical and thermal properties of pure PET, PET/CF and PET/PMMA-g-CF composites were investigated. The results show that the addition of CF or PMMA-g-CF significantly increases the storage modulus (G'), loss modulus (G″), and complex viscosity (η*) of the composites at low frequency.

The Preparation of Nano-SiO₂/Dialdehyde Cellulose Hybrid Materials as a Novel Cross-Linking Agent for Collagen Solutions.

Nano-SiO₂ was immobilized onto dialdehyde cellulose (DAC) to prepare SiO₂/DAC hybrid materials. Fourier transform infrared spectra (FTIR), thermogravimetric analysis and field emission scanning electron microscopy of SiO₂/DAC indicated that nano-SiO₂ had been successfully hybridized with DAC. X-ray diffraction suggested that the structure of DAC was influenced by the nano-SiO₂.

Induction, Resonance, and Secondary Electrostatic Interaction on Hydrogen Bonding in the Association of Amides and Imides.

Both computations and experiments have confirmed that amides have stronger self-associations than imides. While this intriguing phenomenon is usually explained in the term of secondary electrostatic repulsion from the additional spectator carbonyl groups in imides, recently it was proposed that the π resonance effect from the spectator carbonyl which alters the balance between the acidity of the hydrogen-bond (H-bond) donor and the basicity of the H-bond acceptor is the major cause. In this work, we examined the roles of π resonance and the secondary electrostatic interaction in the formation of amide and imide dimers by deactivating the π conjugation from the spectator carbonyl and flipping the spectator carbonyl using the block-localized wave function method which is the simplest variant of valence bond theory.

A robust salt-tolerant superoleophobic chitosan/nanofibrillated cellulose aerogel for highly efficient oil/water separation.

Marine pollution caused by frequent oil spill accidents has already produced catastrophic influence on marine ecological environments. Even though traditional superhydrophobic/superoleophilic surface-coated materials have demonstrated to be effective for oil/water separation, they still suffer from complicated fabrication procedures, mechanical damages and loss of their superoleophobicity in high-salinity environments. Herein, a robust salt-tolerant superoleophobic aerogel was introduced for highly efficient oil/seawater separation, which was fabricated by incorporating nanofibrillated cellulose (NFC) into chitosan (CS) matrix through freeze-drying method.

Fluorescence studies on the aggregation behaviors of collagen modified with NHS-activated poly(γ-glutamic acid).

The poly(γ-glutamic acid)-NHS (γ-PGA-NHS) esters were used to endow collagen with both of excellent water-solubility and thermal stability via cross-linking reaction between γ-PGA-NHS and collagen. In the present work, the effect of γ-PGA-NHS on the aggregation of collagen molecules was studied by fluorescence techniques. The fluorescence emission spectra of pyrene in collagen solutions and the intrinsic fluorescence emission spectra of collagen suggested different effects of γ-PGA-NHS on collagen molecules: inhibiting aggregation below critical aggregation concentration (CAC) and promoting aggregation above CAC.

Manganese(II), lead(II) and cadmium(II) coordination complexes containing a tetrazole-based acylamide ligand: synthesis and the influence of the metal ions on the structures.

Three new manganese(II), lead(II) and cadmium(II) coordination complexes have been prepared by reaction of N-(1H-tetrazol-5-yl)cinnamamide (HNTCA) with divalent metal salts (MnCl, PbCl and CdCl) in a mixed-solvent system, affording mononuclear to trinuclear structures namely, bis(methanol-κO)bis[5-(3-phenylprop-2-enamido)-1H-1,2,3,4-tetrazol-1-ido-κN,O]manganese(II), [Mn(CHNO)(CHOH)], (1), bis[μ-5-(3-phenylprop-2-enamido)-1H-1,2,3,4-tetrazol-1-ido]-κN,O:N;κN:N,O-bis{aqua[5-(3-phenylprop-2-enamido)-1H-1,2,3,4-tetrazol-1-ido-κN,O]lead(II)}, [Pb(CHNO)(HO)], (2), and hexakis[μ-5-(3-phenylprop-2-enamido)-1H-1,2,3,4-tetrazol-1-ido-κN,O:N]tricadmium(II), [Cd(CHNO)], (3). The structures of these three compounds reveal that the nature of the metal ions and the side groups of the organic building blocks have a significant effect on the structures of the coordination compounds formed. Intermolecular hydrogen bonds link the molecules into two-dimensional [complex (1)] and three-dimensional hydrogen-bonded networks.

A Critical Check for the Role of Resonance in Intramolecular Hydrogen Bonding.

Although resonance-assisted H-bonds (RAHBs) are well recognized, the role of π resonance in RAHBs is controversial, as the seemingly enhanced H-bonds in unsaturated compounds may result from the constraints imposed by the σ skeleton. Herein the block-localized wave function (BLW) method, which can derive optimal yet resonance-quenched structures with related physiochemical properties, was employed to examine the correlation between π resonance and the strength of intramolecular RAHBs. Examination of a series of paradigmatic molecules with RAHBs and their saturated analogues showed that it is inappropriate to compare a conjugated system with its saturated counterpart, as they may have quite different σ frameworks.

The Origin of the Non-Additivity in Resonance-Assisted Hydrogen Bond Systems.

The concept of resonance-assisted hydrogen bond (RAHB) has been widely accepted, and its impact on structures and energetics can be best studied computationally using the block-localized wave function (BLW) method, which is a variant of ab initio valence bond (VB) theory and able to derive strictly electron-localized structures self-consistently. In this work, we use the BLW method to examine a few molecules that result from the merging of two malonaldehyde molecules. As each of these molecules contains two hydrogen bonds, these intramolecular hydrogen bonds may be cooperative or anticooperative, depended on their relative orientations, and compared with the hydrogen bond in malonaldehyde.

Visible light-assisted efficient degradation of dye pollutants with biomass-supported TiO hybrids.

The objective of this work was to develop a novel organic-inorganic hybrid nanomaterial from agricultural biomass waste for environmental applications. The sugarcane bagasse (SB) supported TiO hybrids were firstly synthesized via a sol-gel method. A series of characterizations were carried out to reveal the structures and components of obtained hybrids.

Preparation and Characterization of Antibacterial Cellulose/Chitosan Nanofiltration Membranes.

: Presently, most nanofiltration membranes are prepared with non-biodegradable petrochemical materials. This process is harmful to the ecosystem and consumes a large amount of non-renewable energy. In this study, biodegradable and biocompatible antibacterial cellulose/chitosan nanofiltration membranes (BC/CS-NFMs) were fabricated and characterized for their mechanical strength, antimicrobial activity, salt and dye filtration performance, and polyethylene glycol (PEG) retention using Thermal gravimetric analysis (TGA), Field emission scanning electron microscopy(FE-SEM), Fourier transform infrared spectroscopy(FT-IR), and X-ray diffraction (XRD).

Effect of carboxymethylcellulose on fibril formation of collagen in vitro.

The effect of carboxymethylcellulose (CMC) on the fibril formation of collagen in vitro was studied by turbidity measurements and atomic force microscopy (AFM). The kinetics curves of fibril formation indicated that the rate of collagen fibrillogenesis was decreased with the addition of CMC, meanwhile the final turbidity was obviously increased as the CMC/collagen ratio reached 30%. The AFM images of collagen-CMC solutions showed that the number of nucleation sites of collagen fibrillogenesis was significantly increased with the presence of CMC, while the diameter of immature collagen fibrils was obviously decreased.

Water resources management in the urban agglomeration of the Lake Biwa region, Japan: An ecosystem services-based sustainability assessment.

An innovative ecosystem services-based sustainability assessment was conducted in the important urban agglomeration of the Lake Biwa region, Japan, covering the time period from 1950 to 2014. A 22-indicator system was established that was based on the major ecosystem services of Lake Biwa and its water courses, i.e.

The preparation of poly(γ-glutamic acid)-NHS ester as a natural cross-linking agent of collagen.

γ-PGA-NHS ester, which was prepared using poly(γ-glutamic acid) (γ-PGA) and N-hydroxysuccinimide (NHS) as the raw materials, was synthesized to be a novel cross-linker of collagen. Fourier transform infrared spectra analysis suggested that the products displayed the characteristic absorption peak of ester. Results from nuclear magnetic resonance analysis indicated that the esterification degree of γ-PGA-NHS ester was increased with the increase of NHS.

Decomposition pathways of polytetrafluoroethylene by co-grinding with strontium/calcium oxides.

Waste polytetrafluoroethylene (PTFE) could be easily decomposed by co-grinding with inorganic additive such as strontium oxide (SrO), strontium peroxide (SrO) and calcium oxide (CaO) by using a planetary ball mill, in which the fluorine was transformed into nontoxic inorganic fluoride salts such as strontium fluoride (SrF) or calcium fluoride (CaF). Depending on the kind of additive as well as the added molar ratio, however, the reaction mechanism of the decomposition was found to change, with different compositions of carbon compounds formed. CO gas, the mixture of strontium carbonate (SrCO) and carbon, only SrCO were obtained as reaction products respectively with equimolar SrO, excess SrO and excess SrO to the monomer unit CF of PTFE were used.

Simple and rapid chemiluminescence aptasensor for Hg in contaminated samples: A new signal amplification mechanism.

Detection of ultralow concentration of heavy metal ion Hg is important for human health protection and environment monitoring because of the gradual accumulation in environmental and biological fields. Herein, we report a convenient chemiluminescence (CL) biosensing platform for ultrasensitive Hg detection by signal amplification mechanism from positively charged gold nanoparticles ((+)AuNPs). It is based on (+)AuNPs charge effect and aptamer conformation change induced by target to stimulate the generation of CL in the presence of HO and luminol without high salt medium.

Mechanochemical processing of molybdenum and vanadium sulfides for metal recovery from spent catalysts wastes.

This work describes the mechanochemical transformations of molybdenum and vanadium sulfides into corresponding molybdate and vanadate, to serve as a new environment-friendly approach for processing hazardous spent hydrodesulphurization (HDS) catalysts solid waste to achieve an easy recovery of not only molybdenum and vanadium but also nickel and cobalt. Co-grinding the molybdenum and vanadium sulfides with oxidants and sodium carbonate stimulates solid-state reactions without any heating aid to form metal molybdates and vanadates. The reactions proceed with an increase in grinding time and were enhanced by using more sodium carbonate and stronger oxidant.