Melt miscibility of HDPE/UHMWPE,LDPE/UHMWPE,and LLDPE/UHMWPE blends detected by dynamic rheometer

The dynamic rheological behavior of high density polyethylene (HDPE)/ultrahigh molecular weight polyethylene (UHMWPE) blends, low density polyethylene (LDPE)/UHMWPE blends and linear low density polyethylene (LLDPE)/ UHMWPE blends was measured in parallel plate rheometer at 200°C. The analysis of log-additivity rule, Cole-Cole plots and Han curves of the three series blends indicated that the LDPE/UHMWPE blends were miscible in the melt, while the HDPE/UHMWPE blends and LLDPE/UHMWPE blends showed phase separation. The DSC results of LLDPE/UHMWPE blends and HDPE/UHMWPE blends were consistent with the rheological properties, while for the thermal properties of LDPE/UHMWPE blends, results revealed three endothermic peaks, which indicated a liquid-solid phase separation in LDPE/UHMWPE blends.     

Polyoxotungstate nanoclusters supported on silica as an efficient solid-phase microextraction fiber of polycyclic aromatic hydrocarbons

A highly porous silica-supported tungstophosphoric acid (PW) nanocluster was prepared for use in solid-phase microextraction (SPME) of polycyclic aromatic hydrocarbons (PAHs). The PWs represent a class of discrete transition metal-oxide nanoclusters and their structures resemble discrete fragments of metal-oxide structures of definite size and shape. Transition metal-oxide nanoclusters display large structural diversity, and their monodisperse sizes can be tuned from several Ångstroms up to 10 nm. The highly porous silica-supported tungstophosphoric acid nanocluster material is found to be capable of efficiently extracting PAHs from aqueous sample solutions. The nanomaterial was immobilized on a stainless steel wire for fabrication of the SPME fiber. Following thermal desorption, the PAHs were quantified by GC-MS. Analytical merits include limits of detection that range from 0.02 to 0.1 pg mL^?1 and a dynamic range as wide as from 0.001 to 100 ng mL^?1. Under optimum conditions, the repeatability for one fiber (n?=?3), expressed as the relative standard deviation, is between 4.3 % and 8.6 %. The method is simple, rapid, and inexpensive. The thermal stability of the fiber and the high relative recovery make this method superior to conventional methods of extraction.

The highly porous silica-supported tungstophosphoric acid nanocluster material is found to be capable of efficiently extracting PAHs from aqueous sample solutions. The prepared nanomaterial was immobilized onto a stainless steel wire for fabrication of the SPME fiber. Following thermal desorption, the PAHs were quantified by GC-MS.     

Thermally stimulated discharge current (TSDC) characteristics in β-phase PVDF–BaTiO3 nanocomposites

β-phase polyvinylidene fluoride (PVDF)–BaTiO₃ nanocomposite samples have been prepared by solution mixing method. XRD data represent that the crystallinity of PVDF decreases with increase in loading level of BaTiO₃ nanoparticles. DSC curve represents that the melting point of PVDF is lightly affected by loading concentration of BaTiO₃. The morphology and microstructure of PVDF and PVDF embedded by BaTiO₃ nanofillers were investigated by using inverted contrast microscopy (ICM) and scanning electron microscopy (SEM). FTIR interferrometry is proven that PVDF and BaTiO₃ are not chemically interacting; therefore, interaction of BaTiO₃ is van der Waals type of interaction. The thermally stimulated discharge current (TSDC) of PVDF and PVDF–BaTiO₃ nanocomposites sample was characterized by single peak. The observed TSDC peak is discussed on the basis of dipolar and interfacial polarization.     

Spin-trapped Radicals: Determination by LC-TSP-MS and LC-ESI-MS

The 4-POBN[α-(4-pyridyl-l-oxide)-N-tert-butyl-nitrone] radical adducts of ethyl and pentyl radicals were determined by a combination of high performance liquid chromatography (HPLC) combined with electron paramagnetic resonance (EPR) with HPLC-electrospray (ESI)-mass spectrometry and HPLC-thermospray (TSP)-MS. The identifIcation of the peak corresponding to the spin-trapped radical was done by performing HPLC-EPR under the same chromatographic conditions as the HPLC-MS. The radical adducts could be determined by both techniques, even though for ESI only 12 μL/min of the total 1 mL/min HPLC flow rate could be directed into the ion source.     

A wide range optical pH sensor for living cells using Au@Ag nanoparticles functionalized carbon nanotubes based on SERS signals

p-Aminothiophenol (pATP) functionalized multi-walled carbon nanotubes (MWCNTs) have been demonstrated as an efficient pH sensor for living cells. The proposed sensor employs gold/silver core-shell nanoparticles (Au@Ag NPs) functionalized MWCNTs hybrid structure as the surface-enhanced Raman scattering (SERS) substrate and pATP molecules as the SERS reporters, which possess a pH-dependent SERS performance. By using MWCNTs as the substrate to be in a state of aggregation, the pH sensing range could be extended to pH 3.0～14.0, which is much wider than that using unaggregated Au@Ag NPs without MWCNTs. Furthermore, the pH-sensitive performance was well retained in living cells with a low cytotoxicity. The developed SERS-active MWCNTs-based nanocomposite is expected to be an efficient intracellular pH sensor for bio-applications.     

Production of Pt nanoparticles-supported chelating group-modified graphene for direct methanol fuel cells

In this study, Pt nanoparticles (NPs) were supported on reduced graphene oxide with the aid of disodium ethylenediamine-tetraacetate, where the Pt iona were initially attached to EDTA-functionalized graphene oxide (EDTA-GO) sheets and then the metal ion and the graphene oxide were reduced simultaneously by ethylene glycol. Electrochemical properties of the catalysts were studied by measuring cyclic voltammetries, and functional groups of the synthesized materials were investigated by Fourier transform infrared spectrometry. Average sizes and lattice parameters were measured by scanning electron microscopy, transmission electron microscopy images, and X-ray diffraction. The results showed that Pt NPs were successfully deposited on the EDTA-GO with the crystallite size of about 2.3 nm. The prepared catalysts demonstrated an enhanced tolerance towards CO poisoning, when EDTA-GO was used as supports. This suggests that EDTA plays a crucial role in the dispersion and electrocatalytic activity of the metal nanoparticles.     

Antitumoral and MMP-2 inhibition activity of raloxifene or tamoxifen loaded nanoparticles containing dimethyl-β-cyclodextrin

A new nanoparticle formulation has been developed by using dimethyl-β-cyclodextrin (DM-β-CD) with raloxifene HCl or tamoxifene citrate. Both drugs are insoluble in water and represent as low bioavailibilities when given orally. Tamoxifen has an FDA approval for breast cancer prevention and the treatment. Raloxifene is approved for osteoprosis treatment. Both drugs were selected as a model drug antitumoural activity and MMP-2 inhibition studies were evaluated on breast cancer cell lines MCF-7 and MDA-MB 231. MMP-2 is known to be responsible for tumour invasion and initation the of angiogenesis. DM-β-CD and sodium taurocholate (NaTC) have been used as absorption enhancers to increase penetration effect of raloxifene/tamoxifen on the tumour cells and aimed to provide high antitumoral activity and MMP-2 inhibition results by developed nanoparticle formulations. The effects of two absorption enhancers were compared. The highest antitumoral activity was observed for DM-β-CD—raloxifene HCl nanoparticle formulation and also MMP-2 enzyme inhibit effectively.     

Use of hydroxylapatite composite membranes for analysis of bisphenol A

This study evaluates solid-phase micro-extraction (SPME) coupled with gas chromatography–mass spectrometry (GC–MS) to determine trace levels of bis-phenol A in water and leached from plastic containers. In our study, we used very thin composite membranes prepared in the laboratory. The extraction using headspace post-derivatization with bis(trimethylsilyl) trifluoroacetamide (BSTFA), containing 1 % trimethylchlorosilane (TMCS) vapor, following SPME was compared with extraction without derivatization. The SPME experimental procedures to extract bis-phenol A in water were optimized with a relatively polar polyacrylate (PA)-coated fiber, an extraction time of 50 min, and desorption at 300 °C for 2 min. Headspace derivatization following SPME was performed using 7 μL of BSTFA with 1 % TMCS at 65 °C for 30 s. The precision was 5.2 % without derivatization and 9.0 % headspace derivatization. The detection limit was determined to be at the nanogram per liter level. When SPME was used following headspace derivatization, the detection limit was one order of magnitude better than that achieved without derivatization. The results of this study reveal the adequacy of the SPME–GC–MS method for analyzing bisphenol A leached from plastic containers. The concentrations of bisphenol A leached from plastic containers into water ranged from 0.7 to 78.5 μg L^?1.     

Adsorption of polyprotic acid at the water/air interface

A rigorous thermodynamic treatment appropriate for surface adsorption from mixed aqueous solution of alkali and polyprotic acid was derived. Those equations were applied to mixed aqueous solution/air systems of alkali metal hydroxide and Fe^III complex with ethylenediamine- N, N, N′,N′-tetraacetate (Fe-EDTA). Surface density of each species arising from Fe-EDTA was separately evaluated, and thus, surface activity of Fe-EDTA was studied, especially its dependence on pH and how it is influenced by the counter cations. Fe-EDTA was positively adsorbed at the water/air interface at very low pHs and negatively at high pHs. The pH range of positive adsorption of Fe-EDTA with potassium ion, as a counter ion, was wider than that with sodium ion. Thus, potassium ion, a structure breaker, tended to smooth surface adsorption of Fe-EDTA at the water/air interface, whereas sodium ion, a structure maker, tended to withdraw Fe-EDTA from the interfacial region.     

Synthesis and preparation of nanoparticles composed of amphiphilic poly(γ-glutamic acid) with different hydrophobic side chains and their potential of membrane disruptive activity

In the development of nanoparticle-based vaccine adjuvants, the interaction between nanoparticles (NPs) and the cells is a key factor. To control them, we focused on the relationship between the hydrophobicity of the side chains and the cell membrane. In this study, amphiphilic poly(γ-glutamic acid) (γ-PGA), using various types of hydrophobic side chains, was synthesized and used to prepare NPs for evaluating the membrane disruptive activity. When leucine ethyl ester (Leu), methionine ethyl ester (Met), or tryptophan ethyl ester (Trp) was grafted, each polymer formed monodispersed NPs at physiological conditions. Significantly, NPs composed of Leu and Trp showed a membrane disruptive activity at the endosomal environment (pH 5–6.5), while NPs composed of Met did not show. This might be due to the weak hydrophobicity of Met compared to that of Leu and Trp, which demonstrated that the interaction between NPs and cells could be controlled by designing the polymer compositions.     

Analysis of drug interactions with very low density lipoprotein by high-performance affinity chromatography

High-performance affinity chromatography (HPAC) was utilized to examine the binding of very low density lipoprotein (VLDL) with drugs, using R/S-propranolol as a model. These studies indicated that two mechanisms existed for the binding of R- and S-propranolol with VLDL. The first mechanism involved non-saturable partitioning of these drugs with VLDL, which probably occurred with the lipoprotein’s non-polar core. This partitioning was described by overall affinity constants of 1.2 (±0.3)?×?10⁶ M^?1 for R-propranolol and 2.4 (±0.6)?×?10⁶ M^?1 for S-propranolol at pH 7.4 and 37 °C. The second mechanism occurred through saturable binding by these drugs at fixed sites on VLDL, such as represented by apolipoproteins on the surface of the lipoprotein. The association equilibrium constants for this saturable binding at 37 °C were 7.0 (±2.3)?×?10⁴ M^?1 for R-propranolol and 9.6 (±2.2)?×?10⁴ M^?1 for S-propranolol. Comparable results were obtained at 20 and 27 °C for the propranolol enantiomers. This work provided fundamental information on the processes involved in the binding of R- and S-propranolol to VLDL, while also illustrating how HPAC can be used to evaluate relatively complex interactions between agents such as VLDL and drugs or other solutes.     

A colorimetric assay for d-Penicillamine in urine and plasma samples based on the aggregation of gold nanoparticles

We report herein the development of a highly sensitive colorimetric method for detection of d-Penicillamine using citrate-capped gold nanoparticles (AuNPs). This assay relies upon the distance-dependent of gold nanoparticles surface plasmon resonance band of gold nanoparticles. By replacing the thiol-containing chelator drug, d-Penicillamine, with citrate on the gold nanoparticles surface, a new peak appearing at a longer wavelength intensifies and shifts further to the red from the original peak position due to aggregation of gold nanoparticles which depends on ionic strength, gold nanoparticles and d-Penicillamine concentration. During this process, the plasmon band at 521 nm decreases gradually along with the formation of a new red-shifted band at 630 nm. The calibration curve which is derived from the ratio intensities of absorbance at longer wavelength (630 nm) to original wavelength (521 nm) displays a linear relation in the range of 5.0 × 10^?6–3.0 × 10^?4 M d-Penicillamine. Lower limit of detection for d-Penicillamine, at the signal-to-noise ratio of 3 (3σ), was 3.8 × 10^?6 M. The developed methodology was successfully applied for the determination of d-Penicillamine in human urine and plasma.     

The impact of immobilized metal affinity chromatography (IMAC) resins on DNA aptamer selection

DNA aptamers are single-stranded oligonucleotides which can form various secondary and tertiary structures. They can recognize a broad range of targets ranging from small molecules, such as ions, vitamins, antibiotics, to high molecular weight structures, including enzymes and antibodies. DNA aptamers are extensively studied as a potential source of new pharmaceutical drugs due to their inexpensive synthesis, low immunogenicity, and high specificity. The commonly used aptamer selection procedure is systematic evolution of ligands by exponential enrichment (SELEX) where the target molecule is immobilized on an appropriate chromatography resin. For peptide/protein targets, immobilized metal affinity chromatography (IMAC) resins are frequently used. There is a broad range of commercially available resins which can be used for IMAC. They are characterized by different metal ions, linker types, and bead materials. In this study, we tested the impact of different IMAC resins on the DNA aptamer selection process during eight SELEX cycles. A histidine-tagged 29 amino acid peptide corresponding to the interdomain connecting loop of human proliferating cell nuclear antigen was used as a selection target. Different resin materials containing the same metal ion (Co²⁺) were tested. Simultaneously, agarose resins containing identical linkers, but different metal ions (Co²⁺, Cu²⁺, Ni²⁺, and Zn²⁺) were analyzed. The results of this study clearly demonstrated the impact of the metal ion and resin material on the DNA aptamer selection progress. The presented data indicate that for successful IMAC resin-based SELEX, the determination of the optimal resin might be crucial.     

A label-free electrochemical biosensor for microRNA detection based on apoferritin-encapsulated Cu nanoparticles

MicroRNAs (miRNAs), a class of small endogenous nonprotein-coding RNAs, regulate a wide range of biological processes, and their abnormal expressions are related to the growth and development of plants. Thus, a simple, rapid, and highly sensitive assay for miRNA detection is of great significance. In this work, a label-free and ultrasensitive assay for miRNA detection using protein cage nanoparticles has been developed. Apoferritin-encapsulated Cu nanoparticles (Cu-apoferritin) could be immobilized on the electrode through special reaction between amino and carboxyl. Hybridization event between the probe DNA and the target miRNA-159a is confirmed by electrochemical oxidation signal after Cu released into the detection buffer by adjusting the pH. This assay is highly selective and sensitive with a low detection limit of 3.5 fM. Moreover, the developed method can even discriminate single-base mismatched strand between the complementary targets. The effect of abscisic acid on the expression level of miRNA-159a in Arabidopsis thaliana seeds was also investigated.     

New EDTA determination method based on ion chromatography with suppressed conductimetric detection

A novel direct method for the determination of EDTA in alkaline radioactive evaporator residue solution was developed and validated based on ion chromatography with suppressed conductimetric detection and anion exchange columns (A Supp 4, 4 mm × 250 mm and A Supp 5, 4 mm × 150 mm). The yttrium-EDTA complex resulted one single chromatographic peak in the eluent and allowed the correct determination of EDTA in an alkaline, high concentration radioactive waste water. Depending on coexisting substances, suitable eluent is 10.0 mM carbonate buffer/pH 10.6 or 10.75 (t _R,Y–EDTA = 7.01 and 6.4 min, respectively). For 10.0 mM carbonate buffer/pH 10.6 and isocratic flow rate of 1.0 cm³/min, a linear calibration curve was obtained from 5 to 40 mg/dm³ (r > 0.999) EDTA. Good resolution was achieved from commonly coexisting anions (chloride, nitrite, nitrate, sulphate, phosphate, bromide and citrate). The developed simple ion chromatographic method was applied for the assay of EDTA in various radioactive alkaline solutions.     

Calorimetry and thermal analysis studies on the binding of 13-phenylalkyl and 13-diphenylalkyl berberine analogs to tRNAphe

The interaction of 13- monophenylalkyl and diphenylalkyl berberine analogs with tRNA^phe has been investigated using various thermochemical techniques like thermal melting, isothermal titration calorimetry, and differential scanning calorimetry experiments. Thermal melting studies revealed that all the analogs stabilized the tRNA^phe better than berberine. The binding affinity for the analogs was of the order of 10⁵ M^?1. Calorimetry results suggested that the binding of these analogs was predominantly entropy driven with small negative enthalpy contribution to the standard molar Gibbs energy. The temperature dependence of the standard molar enthalpy changes yielded negative values of standard molar heat capacity changes for the complexation revealing substantial hydrophobic contribution in the RNA binding of these analogs. An enthalpy–entropy compensation behavior was also seen in all the systems. The diphenylalkyl analogs were found to be more effective tRNA^phe binders compared to the monophenylalkyl analogs. The utility of the present work lies in understanding the structural and energetic aspects of the interaction of these berberine analogs with tRNA, which may be useful in the development of RNA-targeted drugs.     

Weak acid–base interaction induced assembly for the formation of rambutan-like poly(styrene-alt-maleic anhydride)/silica composite microspheres

To investigate the effect of surface functionality on the morphology of polymer/silica composite, poly(styrene-alt-maleic anhydride) (SMA) spheres prepared via precipitation polymerization method was employed. In water/ethanol solution, diethanolamine (DEA) was used to catalyze the hydrolysis reaction of tetraethoxysilane (TEOS), and rambutan-like poly(styrene-alt-maleic anhydride)/silica (SMA/SiO₂) microspheres were synthesized through in situ sol–gel process. The obtained structure and morphology were characterized by FTIR, NMR, TEM, SEM, and TGA. The results showed that the hydrolyzed SMA chains on the surface was crucial to the nucleation and growth of silica, and the morphologies of SMA/SiO₂ composite microspheres can be controlled by the amount of DEA and the ratio of SMA/TEOS. In addition, the SMA/SiO₂ microspheres were used to prepare hierarchical structure of SMA/SiO₂/Ag particles, which were utilized for the construction of surface-enhanced Raman scattering substrate (SERS).     

Interactions of collagen and cellulose in their blends with 1-ethyl-3-methylimidazolium acetate as solvent

Collagen/cellulose blended solutions with collagen/cellulose mass ratio (Col/Cel) of 0, 1/40, 1/20, 1/10 and 1/5 were prepared using [Emim]Ac as solvent. The interactions between the two polymers before and after regeneration were investigated. In steady shear flow, all of the experimental viscosity values were greater than those of the estimated values calculated from the log-additivity rule for each sample, suggesting interactions between the two polymers in solutions. All solutions exhibited shear thinning behavior and the flow curves could be described by Cross model. Zero shear viscosity (η ₀) versus Col/Cel was examined and a linear increase (from 8.73 to 16.39 Pa·s) can be observed for η ₀ as Col/Cel ≤ 1/10, while there was only a slight increase (from 16.39 to 18.42 Pa·s) in η ₀ as Col/Cel increased to 1/5. Dynamic rheology results suggested the existence of aggregates in solution with Col/Cel = 1/10. Furthermore, the activation energy of solution was 84.5 kJ mol^?1 as Col/Cel = 1/10, higher than that of cellulose solution (44.2 kJ mol^?1). Regenerated films were prepared and characterized to trace back the interactions between the two polymers in [Emim]Ac. Fourier transform infrared spectroscopy indicated the hydrogen-bond interaction between collagen and cellulose in films. The denaturation temperature of collagen in films with Col/Cel ≤ 1/10 could be improved, but it was decreased with the increase of collagen content, and finally was reduced to be close to that of collagen as Col/Cel = 1/5. The features of dynamic mechanical analysis for films were indicative of the lack of homogeneity between collagen and cellulose as Col/Cel = 1/5. Atomic force microscopy images further confirmed the phase-separation when Col/Cel = 1/5.     

Analysis of Genetic Diversity of Certain Species of Piper Using RAPD-Based Molecular Markers

The utility of RAPD markers in assessing genetic diversity and phenetic relationships of six different species of Piper from Northeast India was investigated. Polymerase chain reaction (PCR) with four arbitrary 10-mer oligonucleotide primers applied to the six species produced a total of 195 marker bands, of which, 159 were polymorphic. On average, six RAPD fragments were amplified per reaction. In the UPGMA phenetic dendrogram based on Jaccard’s coefficient, the different accessions of Piper showed a high level of genetic variation. This study may be useful in identifying diverse genetic stocks of Piper, which may then be conserved on a priority basis.