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Well-dispersed chiral Ag2S quantum dots (Ag2S QDs) were facilely synthesized by using N-acetyl-L-cysteine (NALC) as the chiral ligand and loaded onto nanosheets of two-dimensional (2D) few-layer carbon nitride (C3N4). The resultant nanocomposite (Ag2S QDs/few-layer C3N4) shows enhanced electrochemiluminescence (ECL) while maintaining the chirality of Ag2S QDs, which can be used for the chiral discrimination of the enantiomers of tyrosine (Tyr). Due to the higher affinity of chiral Ag2S QDs toward L-Tyr than toward its enantiomer, the ECL intensity of Ag2S QDs/few-layer C3N4 is significantly decreased after its incubation with L-Tyr, and thus the Tyr enantiomers can be discriminated. The developed ECL chiral sensor exhibits high stability and reproducibility. The universality of the ECL chiral sensor for the discrimination of other chiral amino acids is also studied, and the results indicate that it can work only in the case of chiral aromatic amino acids.

In this study, a facile synthesis of two ionized carbon dots (CDs-2 and CDs-3) is reported, in which different ionic pairs are formed at the surface of the carbon core. In contrast to CDs-3, the accumulation of carbon core can be clearly observed in the TEM image of CDs-2. This is due to the linkage of the dibromine alkyl group. Compared with naked CDs in the absence of the ionic pair, the maximum emission wavelength undergoes a red-shift of nearly 60 nm. Moreover, protic solvents (water, ethanol and N,N′-dimethyl formamide) have an apparent effect on the emission intensities of CDs-2 and CDs-3. The time-resolved average lifetimes of CDs-2 and CDs-3 are calculated as 56.34 ns and 54.50 ns, respectively. Furthermore, they both have much better fluorescence stability in the solution with pH ranging from 2 to 11 due to the presence of the imidazolium cation. It is interesting to see that CDs-2 and CDs-3 have much different responses towards Cu2+ and Fe2+. The CDs-3 solution generates clear fluorescence quenching when treated with Fe2+. In brief, we believe that these findings can inspire more research developments in the synthesis and further application of functional CDs.

Tubular mesoporous silica (T-mSiO2) was facilely synthesized through a co-template method by using cetyltrimethylammonium bromide and α-Fe2O3 as the dual templates, and then disulfide (–SS–) bonds and carboxyl groups (–COOH) were introduced to the resultant T-mSiO2 via the reaction with 2-carboxyethyl 2-pyridyl disulphide. The obtained –SS– grafted T-mSiO2 (SS-T-mSiO2) was then grafted with chitosan (CS) via the amidation reaction between the –COOH groups on SS-T-mSiO2 and the –NH2 groups on CS. The CS grafted SS-T-mSiO2 (CS-SS-T-mSiO2) was fully characterized by various technologies such as transmission electron microscopy, energy dispersive X-ray spectroscopy and Fourier transform infrared spectroscopy. Finally, the as-synthesized CS-SS-T-mSiO2 was used as the carrier for redox and pH dual-triggered delivery of 5-fluorouracil (5-FU), an anti-cancer drug, and the results indicate that the developed CS-SS-T-mSiO2 might be a potential responsive carrier for redox and pH dual-triggered drug delivery.

The second (H2) and third (H3) harmonic generations in surface acoustic wave (SAW) resonators based on the YZ-cut LiNbO 3 operating in both longitudinal leaky SAW (LLSAW) mode and Rayleigh SAW mode were investigated and compared. For the Rayleigh SAW mode, the patterns and trends of nonlinearly excited harmonics in the YZ-cut LiNbO 3 were the same as those of 128° YX LiNbO 3 except that the peaks of nonlinear harmonic responses in YZ-cut LiNbO 3 were denser than the latter. However, for the YZ-cut LiNbO 3 LLSAW resonators, the peaks of the nonlinear harmonic responses would be 20 to 30 dBm lower than those in the Rayleigh SAW resonators. For the YZ-cut LiNbO 3 LLSAW resonators, we found that the quasi-periodic peaks in the nonlinear harmonics response would disappear at a substrate thickness of 500 μm. Results showed that the nonlinear harmonic generation concerns in SAW filters and duplexers may be substantially reduced by the use of longitudinal leaky SAW based on YZ-cut LiNbO 3 .

In this study, a sensitive and selective electrochemical sensing platform for the detection of Sudan I was developed with CuO nanoparticles-decorated 3D N-doped porous carbon (CuO/3DNPC). 3D N-doped porous carbon (3DNPC) was first prepared by calcining the precursors of 3D integrated polysaccharides, and then it was decorated with CuO nanoparticles by hydrothermal method. The CuO/3DNPC modified electrode showed high sensitivity and wide linear range for the detection of Sudan I due to the excellent electrocatalytic activity of CuO and the accelerated electron transfer by 3DNPC. In addition, the proposed CuO/3DNPC also exhibited high selectivity, high reproducibility and stability in the detection of Sudan I. Finally, the CuO/3DNPC based Sudan I sensor was applied in the detection of Sudan I in ketchup and chilli sauces, and the results demonstrated the potential of the developed CuO/3DNPC as a promising electrode material for accurate assay of Sudan I in food samples.

Poly(acrylic acid-co-acrylamide) (P(AA-co-AM)) hydrogels with upper critical solution temperature (UCST) were synthesized via radical copolymerization technology, which were then incorporated with SiO2@polypyrrole (SiO2@PPy) for the construction of light-, thermo- and pH-responsive drug delivery system. The synthesized SiO2@PPy@P(AA-co-AM) hydrogels were then examined by Fourier transform infrared (FT-IR) spectrometry, field emission scanning electron microscopy (FESEM), thermogravimetry (TG) and differential thermogravimetric (DTG). Finally, the designed SiO2@PPy@P(AA-co-AM) hydrogels were used for controlled delivery of 5-fluorouracil (5-FU), an anti-cancer drug. An encapsulation ratio of up to 92.2% was obtained when 5-FU was encapsulated in the SiO2@PPy@P(AA-co-AM) hydrogels, and the cumulative release of 5-FU could reach 83.9% with the near-infrared (NIR) irradiation of 6 h at pH 7.4. During the controlled release of 5-FU, PPy in the system could convert the NIR irradiation to heat as a photo-thermal transducer while maintaining the temperature in the UCST range of P(AA-co-AM). In addition, SiO2 in the hydrogels acted as a gatekeeper to prevent the burst release of 5-FU.

In this study, an electroactive rotaxane, (S,S)-crown-3, consisting of a polymeric chiral ionic liquid as a flexible axle and 18-crown-6 as the wheel, was designed and synthesized. It is worth noting that a stimuli-responsive system was developed, in which the wheel could switch its location between the chiral carbamido group and ionic pair of the ionic polymers under an external force. Next, (S,S)-crown-3 was employed as a modification on the surface of glassy electrode. In contrast to previous study, the developed probe presented a clear discrimination of an electrochemical signal in the absence of Cu(ii). Under the external force (different pH values), l-isomers of amino acids (tryptophan, tyrosine, and cysteine) could form stable host-guest interactions with the chiral carbamido group, producing higher peak currents than the d-isomers. Compared to the absence of the crown, (S,S)-crown-3 showed much better recognition efficiency. The value of IL/ID for tryptophan could reach 39.8. In brief, the present study describes a powerful method for the synthesis of an electroactive rotaxane with great enantiorecognition capability.

Conductive materials are valuable supports and widely applied in electrochemical analysis. In the current article, a mesoporous organosilica sphere (S,S)-CPMO-3 with the chiral group and electroactive units is presented. The organosilicon framework is composed of free ions belonging to the ionic liquid and the chiral group arising from (1S,2S)-1,2-diaminocyclohexane. Next, a bare electrode was modified by the as-synthesized composite material to construct the new electrochemical sensor (S,S)-CPMO-3-GCE. It was observed that (S,S)-CPMO-3-GCE exhibited favourable enantioselective recognition in the response of the peak current (Ip) and the peak potential (Ep) to the different configurations of amino acids. Taking tryptophan as an example, the value of IL/ID is 13.84 and the peak-to-peak potential approaches 48 mV. In addition, cysteine and tyrosine were successfully distinguished by the sensor. In summary, this study not only introduces a route for the synthesis of a conductive material, but also opens up its further potential in enantioselective recognition.

A novel ultraviolet (UV)- and visible-light-active 3D graphene aerogels (3DGA)/Sb2WO6 hybrid photocatalyst was prepared by electrostatic self-assembly (ESSA) method. The photocatalytic activity of the 3DGA/Sb2WO6 hybrid was studied by monitoring the change in the concentration of methyl orange (MO) under UV-light and visible-light irradiation. The results demonstrated that the as-prepared hybrid exhibited significantly enhanced efficiency for the photodegradation of MO in comparison with pure Sb2WO6. This was ascribed to the efficient separation of the photogenerated electrons (e–) and holes (h+) with the aid of 3DGA as well as the generated reactive superoxide radical anions (O2•–). Moreover, the 3DGA/Sb2WO6 hybrid exhibited high recyclability, because the highly hydrophobic 3DGA in the hybrid was very advantageous to the separation of the hybrid photocatalyst from the MO solutions.

Mesenchymal stem cells (MSC) are highly regarded as a potential treatment for retinal degenerative disorders like retinitis pigmentosa and age-related macular degeneration. However, donor cell heterogeneity and inconsistent protocols for transplantation have led to varied outcomes in clinical trials. We previously showed that genetically-modifying MSCs to express erythropoietin (MSCEPO) improved its regenerative capabilities in vitro. Hence, in this study, we sought to prove its potential in vivo by transplanting MSCsEPO in a rat retinal degeneration model and analyzing its retinal transcriptome using RNA-Seq. Firstly, MSCsEPO were cultured and expanded before being intravitreally transplanted into the sodium iodate-induced model. After the procedure, electroretinography (ERG) was performed bi-weekly for 30 days. Histological analyses were performed after the ERG assessment. The retina was then harvested for RNA extraction. After mRNA-enrichment and library preparation, paired-end RNA-Seq was performed. Salmon and DESeq2 were used to process the output files. The generated dataset was then analyzed using over-representation (ORA), functional enrichment (GSEA), and pathway topology analysis tools (SPIA) to identify enrichment of key pathways in the experimental groups. The results showed that the MSCEPO-treated group had detectable ERG waves (P Padj EPO-treated retinal degeneration model as well as a profile of pro-survival genes that can be used as candidates for further genetic enhancement studies on stem cells.

Rational design and synthesis of high performance active materials is one of the most challenging tasks in supercapacitors. Herein, a new three-dimensional (3D) reduced graphene oxide (RGO)/carbon nanospheres (CNS)/polyaniline (PANI) ternary nanocomposites were prepared facilely and applied as supercapacitor electrode materials. The as-prepared RGO/CNS/PANI ternary nanocomposites were characterized by field-emission scanning electron microscopy (FESEM), Fourier transform infrared (FT-IR) spectra and X-ray powder diffraction (XRD), respectively. An enhanced specific capacitance was demonstrated compared with other binary nanocomposites RGO/PANI, RGO/CNS and pure RGO or PANI. The RGO/CNS/PANI exhibited a high specific capacitance of 583 F g −1 at a current density of 1 A g −1 and excellent cyclic stability with 86% of its initial capacitance at a large current density of 10 A g −1 after 1000 charge/discharge cycles. In addition, high rate capability (72% capacity retention from 1 to 10 A g −1 ) was obtained due to the synergistic effects of RGO/CNS and PANI. The results indicated that the ternary nanocomposites of RGO/CNS/PANI could be a promising material for supercapacitor electrodes.

Alfa-cyclodextrin (α-CD) based chiral sensing device is proposed for electrochemical recognition of tyrosine (Tyr) isomers. α-CD was first modified with Cu 2+ , and then the obtained Cu 2+ -modified α-CD (Cu 2 -α-CD) was integrated to chitosan (CS) to form a coordination-driven self-assembly. The amino group and phenolic hydroxyl group of Tyr could form three intermolecular H-bonds with the high-energy water molecules confined in the cavity of Cu 2 -α-CD. The host (self-assembly) −guest (Tyr isomers) interactions are different for D- and L-Tyr due to the opposite steric configurations of the Tyr isomers, resulting in significantly discernable electrochemical differences in both peak currents and peak potentials and consequently effective chiral recognition of Tyr isomers. The temperature-sensitivity and chiral specificity of the proposed self-assembly are also investigated in this work. Finally, the percentage of D-Tyr in a racemic mixture can be accurately predicted with the CS/Cu 2 -α-CD self-assembly, showing its potential in practical applications.

Sulfur-doped titanium dioxide (S-TiO2) was hydrothermally synthesized using thiourea as the sulfur source, and then it was successfully integrated to the three-dimensional graphene aerogels (3DGA). The obtained nanocomposites of S-TiO2 and 3DGA (S-TiO2-3DGA) were characterized by XRD, SEM, TEM, XPS and UV–vis diffuse reflectance spectroscopy. When the nanocomposites were applied for the photodegradation of methyl orange (MO), the photocatalytic activity of TiO2 was significantly improved by doping of S and integration with 3DGA, which might be due to the narrowed bandgap of S-TiO2 and the good conductive ability and 3D structure of 3DGA. More importantly, the hydrophobic property of 3DGA makes it easy to separate the S-TiO2-3DGA from the water phase, resulting in excellent recyclability and high stability of the photocatalyst.

We report the facile synthesis of N-doped carbon-graphene-manganese oxide (N/C-G-MnO) that can serve as precious metal-free electrocatalysts for oxygen reduction reaction (ORR). The N/C-G-MnO is synthesized via polymerization of m -phenylenediamine adsorbed on graphene using KMnO 4 as the oxidant, followed by pyrolyzation of the resulting N- and MnO 2 -containing poly( m -phenylenediamine). That is, poly( m -phenylenediamine) plays multi-roles in the synthesis of the ORR catalysts: (i) Serving as interlayer spacer to prevent graphene sheets from restacking during the thermal annealing, (ii) Function as the source of N-doped carbon (N/C) and MnO for the simultaneous doping of graphene. The N/C-G-MnO exhibits better ORR activity, long-term stability and methanol tolerance than those of the commercial Pt (5%)/C catalyst.

Sulfur and nitrogen codoped three-dimensional graphene-MnS (MnS/S,N-3DG) hybrids are facilely synthesized via a hydrothermal method followed by freeze-drying and pyrolysis treatment. The obtained MnS/S,N-3DG as an electrocatalyst for oxygen reduction reaction (ORR) shows excellent electrocatalytic performance. The codoped S and N as well as the introduced MnS significantly promote the electrocatalytic activity of graphene and efficiently catalyze the ORR process through a mixture of two-electron transfer pathway and four-electron transfer pathway (electron transfer number equals to 3.8 or 3.9), which is even better than the commercial Pt (5%)/C catalyst. Moreover, the developed MnS/S,N-3DG electrocatalyst possesses excellent long-term stability and methanol tolerance, and could be a promising cathode electrocatalyst in future energy conversion and storage systems.

Blindness and vision impairment are caused by irremediable retinal degeneration in affected individuals worldwide. Cell therapy for a retinal replacement can potentially rescue their vision, specifically for those who lost the light sensing photoreceptors in the eye. As such, well-characterized retinal cells are required for the replacement purposes. Stem cell-based therapy in photoreceptor and retinal pigment epithelium transplantation is well received, however, the drawbacks of retinal transplantation is the limited clinical protocols development, insufficient number of transplanted cells for recovery, the selection of potential stem cell sources that can be differentiated into the target cells, and the ability of cells to migrate to the host tissue. Dental pulp stem cells (DPSC) belong to a subset of mesenchymal stem cells, and are recently being studied due to its high capability of differentiating into cells of the neuronal lineage. In this review, we look into the potential uses of DPSC in treating retinal degeneration, and also the current data supporting its application.

The inhibition of carbohydrate-hydrolyzing enzymes in human digestive organs is crucial in controlling blood sugar levels, which is important in treating type 2 diabetes. In the current study, pahangensin A (1), a bis-labdanic diterpene characterized previously in the rhizomes of Alpinia pahangensis Ridl., was identified as an active dual inhibitor for α-amylase (IC50 =114.80 μm) and α-glucosidase (IC50 =153.87 μm). This is the first report on the dual α-amylase and α-glucosidase inhibitory activities of a bis-labdanic diterpene. The Lineweaver-Burk plots of compound 1 indicate that it is a mixed-type inhibitor with regard to both enzymes. Based on molecular docking studies, compound 1 docked in a non-active site of both enzymes. The dual inhibitory activity of compound 1 makes it a suitable natural alternative in the treatment of type 2 diabetes.

Blindness and vision loss contribute to irreversible retinal degeneration, and cellular therapy for retinal cell replacement has the potential to treat individuals who have lost light sensitive photoreceptors in the retina. Retinal cells are well characterized in function, and are a subject of interest in cellular replacement therapy of photoreceptors and the retinal pigment epithelium. However, retinal cell transplantation is limited by various factors, including the choice of potential stem cell source that can show variability in plasticity as well as host tissue integration. Dental pulp is one such source that contains an abundance of stem cells. In this study we used dental pulp-derived mesenchymal stem cells (DPSCs) to mitigate sodium iodate (NaIO3) insult in a rat model of retinal degeneration. Sprague-Dawley rats were first given an intravitreal injection of 3 × 105 DPSCs as well as a single systemic administration of NaIO3 (40 mg/kg). Electroretinography (ERG) was performed for the next two months and was followed-up by histological analysis. The ERG recordings showed protection of DPSC-treated retinas within 4 weeks, which was statistically significant (* P ≤ .05) compared to the control. Retinal thickness of the control was also found to be thinner (*** P ≤ .001). The DPSCs were found integrated in the photoreceptor layer through immunohistochemical staining. Our findings showed that DPSCs have the potential to moderate retinal degeneration. In conclusion, DPSCs are a potential source of stem cells in the field of eye stem cell therapy due to its protective effects against retinal degeneration.

Retinal disorders account for a large proportion of ocular disorders that can lead to visual impairment or blindness, and yet our limited knowledge in the pathogenesis and choice of appropriate animal models for new treatment modalities may contribute to ineffective therapies. Although genetic in vivo models are favored, the variable expressivity and penetrance of these heterogeneous disorders can cause difficulties in assessing potential treatments against retinal degeneration. Hence, an attractive alternative is to develop a chemically-induced model that is both cost-friendly and standardizable. Sodium iodate is an oxidative chemical that is used to simulate late stage retinitis pigmentosa and age-related macular degeneration. In this study, retinal degeneration was induced through systemic administration of sodium iodate (NaIO3) at varying doses up to 80 mg/kg in Sprague-Dawley rats. An analysis on the visual response of the rats by electroretinography (ERG) showed a decrease in photoreceptor function with NaIO3 administration at a dose of 40 mg/kg or greater. The results correlated with the TUNEL assay, which revealed signs of DNA damage throughout the retina. Histomorphological analysis also revealed extensive structural lesions throughout the outer retina and parts of the inner retina. Our results provided a detailed view of NaIO3-induced retinal degeneration, and showed that the administration of 40 mg/kg NaIO3 was sufficient to generate disturbances in retinal function. The pathological findings in this model reveal a degenerating retina, and can be further utilized to develop effective therapies for RPE, photoreceptor, and bipolar cell regeneration.

Poly(melamine) (PMel) was synthesized via the electropolymerization of melamine monomer, which was then characterized by field-emission scanning electron microscopy (FESEM), cyclic voltammetry (CV) and electrochemical impedance spectroscopy (EIS). The possible polymerization mechanisms of melamine were also revealed by FT-IR spectroscopy and UV-Vis spectroscopy. Next, the PMel modified GCE (PMel/GCE) was used for the simultaneous determination of nitrite (NO2-) and tartrazine, and the parameters were optimized. The kinetic study showed that the electrochemical oxidation of nitrite and tartrazine at the surface of PMel/GCE is a typical surface-controlled electrode process. Under the optimun conditions, the developed sensor outperformed those previously reported, and it also exhibited high selectivity and reproducibility. Finally, the PMel/GCE was used for the simultaneous determination of nitrite and tartrazine in foodstuffs, and the results indicated that the proposed sensor could be a promising candidate for accurate determination of nitrite and tartrazine in real food samples.

Erythropoietin (EPO) is a glycoprotein hormone conventionally thought to be responsible only in producing red blood cells in our body. However, with the discovery of the presence of EPO and EPO receptors in the retinal layers, the EPO seems to have physiological roles in the eye. In this review, we revisit the role of EPO in the eye. We look into the biological role of EPO in the development of the eye and the physiologic roles that it has. Apart from that, we seek to understand the mechanisms and pathways of EPO that contributes to the therapeutic and pathological conditions of the various ocular disorders such as diabetic retinopathy, retinopathy of prematurity, glaucoma, age-related macular degeneration, optic neuritis, and retinal detachment. With these understandings, we discuss the clinical applications of EPO for treatment of ocular disorders, modes of administration, EPO formulations, current clinical trials, and its future directions.

Poly(aniline- co - m -aminophenol)(PANMA)/graphene/NiO nanocomposite was synthesized and applied as a supercapacitor electrode for the first time. Graphene/NiO nanocomposite was first synthesized via a hydrothermal synthesis method from Ni(NO 3 ) 2 ·6H 2 O, urea, and graphite oxide. NiO nanoparticles were distributed uniformly on both sides of the graphene. Then, PANMA was deposited in situ on the surface of the graphene/NiO nanocomposite via the copolymerization of aniline and m -aminophenol. The obtained nanocomposite has a similar porous morphology with that of PANMA. Experimental results indicate that the synergistic contributions from PANMA, graphene and NiO enable the composite electrode with substantially improved energy storage performance metrics. The nanocomposite shows a high specific capacitance of 562 F g −1 at a current density of 0.5 A g −1 , a good rate capability even at high current densities and a better long-term cycling stability.

Pristine chitosan beads were modified with sulfur (S)-containing functional groups to produce thiolated chitosan beads (ETB), thereby increasing S donor ligands and crosslinks. The effect of temperature, heating time, carbon disulfide (CS2)/chitosan ratio, and pH on total S content of ETB was examined using Fourier transform infrared spectroscopy and X-ray photoelectron spectroscopy. The total S content of ETB increased with increasing CS2/chitosan ratio and decreased with decreasing pH and increasing temperature (>60 °C) and heating time (at 60 °C). Spectroscopic analyses revealed the presence of thiol (–SH)/thione, disulfide (–S–S–), and sulfonate groups in ETB. The thiolation mechanism involves decomposition of dithiocarbamate groups, thereby forming thiourea crosslinks and trithiocarbonate, resulting in –SH oxidation to produce –S–S– crosslinks. The partially formed ETB crosslinks contribute to its acid stability and are thermodynamically feasible in adsorbing Cd and Cu. The S-containing functional groups added to chitinous wastes act as sorbents for metal remediation from acidic environments. Refereed/Peer-reviewed

Graphene–polyaniline–MnO 2 (G–P–Mn) hybrids were synthesized via a facile approach that includes the reduction of graphene oxide (GO) to graphene (G) by aniline and then followed by oil–water interfacial polymerization of aniline to polyaniline (PANI) using a binary oxidant of KMnO 4 and (NH 4 ) 2 S 2 O 8 . PANI was orderly nanofibered and MnO 2 -doped due to interfacial polymerization and the use of binary oxidant. The hybrids conclude electrical double layer capacitance of G and pseudo capacitance of PANI and MnO 2 , showing enhanced specific capacitance of 800.1 F g −1 at 0.4 A g −1 with good cycling stability.

This case report aims to share the successful management of Epithelial Downgrowth (ED) which occurred following persistent wound leak, after Removal of Silicone Oil (ROSO) via the anterior chamber. A teenage male with history of high myopia underwent bilateral phacoemulsification and implantation of Multifocal Intraocular Lens (MFIOLs). Four months later, he complained of left eye floaters and blurring of vision. Fundus showed left vitreous haemorrhage with lens subluxation. Left 23 gauge pars plana vitrectomy revealed multiple retinal tears. Endolaser and gas injection with MFIOL repositioning was done. Retinal redetachment and MFIOL subluxation occurred six weeks postoperatively. Revision vitrectomy with silicone oil and explantation of MFIOL was performed rendering left eye aphakic. Four months later, he underwent ROSO via a superior corneal incision. Positive Seidels was seen two weeks post-ROSO and resuturing was performed. Unfortunately, advancing ED was noted at the superior cornea. One month after ROSO, scleral fixated IOL implantation with manual removal of ED and intracameral injection of 5-fluorouracil (5-FU) were performed. Twelve months postoperatively, cornea remained clear with a pinhole vision of 6/7.5 and retina was flat. In conclusion, wound leak after ROSO via the anterior chamber in aphakic individuals may predispose to ED. Key to treatment of this sight threatening condition is thoughtful anterior segment examination. Manual removal of the membrane combined with 5-FU injection during secondary lens implantation surgery is an effective treatment.

A simple method to synthesize Zn 2+ doped poly(aniline- co - m -aminophenol) (PANMA), Zn-PANMA, for supercapacitors is reported. Capacitive behaviors of the copolymer based supercapacitor in 1 M H 2 SO 4 electrolyte were examined by electrochemical impedance spectroscopy (EIS), cyclic voltammetry (CV), and galvanostatic charge/discharge. The morphological characteristics of Zn-PANMA and PANMA doped with Fe 3+ and Cu 2+ were investigated by field emission scanning microscopy (FESEM), explaining the different capacitive behaviors of these transition metal ions doped PANMA. A specific capacitance of Zn-PANMA as high as 631 F g −1 was achieved at a current density of 0.5 A g −1 , due to the enhancement of the electrochemical properties of the copolymer by Zn 2+ doping. Moreover, the specific capacitance still remained 71.7% after cycling for 800 times, exhibiting a good cycling performance and structure stability of Zn-PANMA.

A general purpose finite element model that yielded directly the nonlinear frequency response of the second harmonic generation in SAW IDT resonators was developed. The model enabled us to study the effects of the nonlinear material constants, voltage drive, duty factor, and IDT geometry on f-2f nonlinear interactions. Specifically we have applied our model to the study of nonlinear frequency response of second harmonic generation in lithium niobate YX-127o SAW IDT resonators. Lithium niobate was chosen because a complete set of its nonlinear material constants was known and published in the literature. A complete set of nonlinear piezoelectric equations along with their material constants for a lithium niobate YX-127o SAW IDT 836 MHz resonator was implemented in a finite element program. Two sets of finite element matrix equations were derived for the fundamental SAW mode and its 2nd harmonic mode, respectively. We demonstrated how two frequency domain interfaces could be coupled together to simulate the f-2f nonlinear interactions. The fundamental Rayleigh SAW mode was excited by a drive voltage at the IDT that in turn generated the 2nd harmonic mode at twice the frequency. A higher voltage drive lead to higher 2f interactions. Effects of the 2nd harmonic generation on the fundamental SAW mode and its Q were observed when the voltage drive was greater than 0.5V. For example, when the drive voltage was 0.1V the fundamental mode was clean. But when the drive voltage was increased to 0.5V the fundamental mode exhibited Q reduction and stronger f-2f interactions were observed, namely, there were stronger interactions of the 2f BAW mode with the f SAW mode. There was an optimal duty factor of 0.4 to 0.5 for the least f-2f interactions. Thinner electrode thickness resulted in stronger f-2f interactions.

The nonlinear characteristics of SAW resonators have been of great interest recently. We present a new nonlinear solution algorithm for the f-2f nonlinear coupling phenomenon in SAW IDT resonators. Specifically we have applied our algorithm to obtain the f-2f frequency response of the lithium niobate YX-127o SAW IDT resonators. Lithium niobate was chosen because a complete set of its nonlinear material constants was known and published in the literature. The algorithm consisted of solving the nonlinear finite amplitude model in the time domain to obtain the time dependent response, and then performing a fast Fourier transform of the time dependent response. In order to minimize the transient response, the initial conditions for the time domain solution were obtained from the frequency response of the linear model. Results were presented for a one-electrode IDT SAW resonator at increasing drive voltages. The charge on the electrode IDT for the nonlinearly generated 2f mode increased with the square of the magnitude of f mode drive level voltage.

Changes in soil nutrients have been applied in legal investigations of the time of death or to locate a clandestine grave. However, research on forensic soil chemistry under the tropical climate conditions in Malaysia is at its infancy, with few data available for forensic investigations. This study aims to study changes of soil nutrients (i.e. ammonia, phosphate and nitrate) as well as soil pH and electrical conductivity (EC), and the associated stages of decomposition of rat carcasses (n = 3) under controlled tropical climate conditions. The results showed differences in soil pH between control and carcass soils. Soil EC and concentrations of ammonia and phosphate increased during early decomposition stages, and declined thereafter. Nitrate concentration increased at the later stage of decomposition. We also found that the top layer of soil (i.e. 5 cm from surface) rendered a significant pattern of soil nutrient dynamics compared with soil at 10 cm from the surface, possibly due to a slower rate of vertical transfer and the washing-off effect. We suggest that the soil EC value and changes of soil nutrients in the top 5 cm of the soil layer have potential in forensic investigation to determine the minimum post-mortem interval and serve as an indicator for hidden graves and cadaver decomposition islands.

A novel double-potential technique is applied for the electrodeposition of Pt nanoparticles (PtNPs) with controllable size on poly( m -phenylenediamine) (P m PD). The double-potential technique is comprised of the control of the electrodeposition time of PtNPs, followed by the electromodulation of PtNPs size. Oxidation of methanol on the resulting PtNPs/P m PD was investigated, indicating that PtNPs/P m PD exhibits excellent catalytic activity and satisfactory poisoning-tolerance toward methanol oxidation, which is due to the synergistic effect of PtNPs and P m PD. The results demonstrate that PtNPs/P m PD can be a promising electrode material used in the direct methanol fuel cell (DMFC).

An electrochemical immunosensing method was developed based on poly( m -aminophenol) (P m AP) immobilized goat anti-human IgG (anti-IgG). Glutaraldehyde (GA) was used as a coupling reagent, its two aldehyde groups reacted with the amino groups of P m AP electrodeposited on the expanded graphite (EG) surfaces and the amino groups of anti-IgG, respectively. In this immunoassay, human IgG was fixed as the target antigen, horseradish peroxidase (HRP)-conjugated goat anti-human IgG (HRP-anti-IgG) as the probing antibody and poly(methylene blue) (PMB) as the electron mediator. The oxidation peak current of PMBH (the reduction state of PMB) was proportional to the concentration of IgG in the range from 5 to 60 μg mL −1 , and the detection limit was 0.19 μg mL −1 (signal-to-noise ratio of 3). The proposed system reduced complexity and costs which are considered as the most wanted features in the point-of-care diagnostics application of clinical screening of multiple diseases.

Chitosan has low uptake for most heavy metals as well as high solubility in monoprotic acids. To address these problems, sulfur-containing functional groups have been introduced to enhance the sorption of heavy metals via formation of strong coordination bonds with heavy metals and also to improve its stability. The approaches to sulfur enrichment to the chitosan structure include grafting of sulfur-containing molecules to C2 amine or C6 hydroxyl groups. Crosslinking and grafting agents such as glutaraldehyde and epichlorohydrin have also been used in chitosan modification. In this review, special emphasis is placed on the synthesis pathways of sulfur-functionalization of chitin and chitosan and their metal uptakes. Generally, the uptake of soft acid metals such as Hg(II) and Cd(II) has been shown to increase with increasing sulfur content of modified chitosan. However, other factors such as the availability of thiol and amine groups as well as surface area of the modified chitosan also influence metal sorption. Refereed/Peer-reviewed

Polysaccharides of sodium carboxymethyl cellulose (CMC) and chitosan (CS) were integrated together via amidation reactions between the carboxyl groups on sodium CMC and the amino groups on CS. Compared with individual sodium CMC and CS, the integrated polysaccharides with a mass ratio of 1:1, CMC-CS (1:1), exhibited a three-dimensional (3D) porous network structure, resulting in a significantly enhanced hydrophility due to the exposed polar functional groups in the CMC-CS (1:1). Chiral interfaces were constructed with the integrated polysaccharides and used for electrochemical enantiorecognition of tryptophan (Trp) isomers. The CMC-CS (1:1) chiral interfaces exhibited excellent selectivity toward the Trp isomers owing to the highly hydrophilic feature of CMC-CS (1:1) and the different steric hindrance during the formation of H bonds between Trp isomers and CMC-CS (1:1). Also, the optimization in the preparation of integrated polysaccharides such as mass ratio and combination mode (amidation or electrostatic interactions) was investigated. The CMC-CS (1:1) presented the ability of determining the percentage of d-Trp in racemic mixtures, and thus, the proposed electrochemical chiral interfaces could be regarded as a potential biosensing platform for enantiorecognition of chiral compounds.

A series of isomeric poly(ether ether ketone)s were synthesized using microwave-assisted method by nucleophilic substitution reaction of hydroquinone and 4,4′-biphenol with 4,4′-difluorobenzophenone (DFBP) or 2,4′-DFBP in the presence of anhydrous K2CO3. The polymers with inherent viscosities in the range of 0.20–0.71 dlg−1 were obtained in quantitative yields and had excellent thermal stability as shown by the temperature of 5% weight loss in nitrogen above 410°C. X-ray diffraction patterns confirmed the semicrystalline character of some of the polymers. The results also indicate that the reaction time was shortened remarkably and the reaction temperature could be controlled easily. POLYM. ENG. SCI., 2011. © 2010 Society of Plastics Engineers

The electrolysis of catechol was studied in the pH values of 1 to 10. The results from the rotating ring-disk electrode (RRDE) experiments show that at low pH values, the electrochemical polymerization of catechol was performed by one step, and at higher pH values, the electrochemical polymerization of catechol was carried out by two steps, i.e. oxidation of catechol and followed by polymerization. The intermediates generated at the disk were detected at the ring electrode in the ring potential region of-0.2to 0 V (vs. Ag/AgCl). One of reasons for the decrease in the ratio of ir to id with increasing the ring potential is caused by formation of positively charged intermediates at the disk electrode. This ratio increases with increasing the rotation rate of the RRDE, which indicates that the intermediates are not stable. A shielding effect during polymerization of catechol was observed when the ring potential was set at 0.1 V (vs. Ag/AgCl). The electron spin resonance (ESR) of polycatechol shows that polycatechol possesses unpaired electrons. The images of polycatechol films synthesized at different conditions are described.

Biochar has an alkaline and porous structure that could be a potential material for recycling phosphorous (P) from urine. Sawdust (SD) was pyrolyzed to produce sawdust biochar (SDB), and then impregnated with magnesium (Mg) to produce Mg-impregnated biochar (SDBM). Artificial human urine (AHU) solution was used for a batch sorption study, and various sorption parameters (i.e., sorbent/solution ratio, pH of AHU, and initial total P concentration of AHU) were optimized. The concentration of total P was measured using an inductively coupled plasma-optical emission spectroscopy (ICP-OES). The surface morphology and elemental analysis for SDB, SDBM and the struvite-loaded SDBM (SMSDB) were investigated using scanning electron spectroscopy-energy dispersive x-ray spectroscopy (SEM-EDX). The total P sorption capacity for SDBM (32755 mg/g) was higher than that of SDB (7782 mg/g) and SD (10682 mg/g). The optimum total P removal for SDBM (21.2%) was achieved at a sorbent/solution ratio of 0.06g/L at pH 9. Sorption of total P may have occurred on the heterogeneous surface of SDBM. The presence of struvite crystals indicates that phosphate was adsorbed and then precipitated on the surface of SDBM.

Cassava stem biochar (CSB) was produced by pyrolyzing CS at 500°C for 2 hours at nitrogen environment. Proximate and ultimate analyses were conducted on CS and CSB. Batch sorption experiment on synthetic MG wastewater was optimized for the sorbent dosage, MG solution pH and contact time. Sorption data was analysedwith linearized sorption kinetic and linearized isotherm models. Pyrolysis of CS produced carbon-rich and stable CSB yield of 11.94%. The optimum sorption sorbent dosage, MG solution pH and contact time 1.67 g/L, > pH 7.4 and 10 minutes respectively. The sorption of MG by CSB was best described by the pseudo-second-order kinetic model and the Langmuir isotherm model. The Langmuir sorption capacity of CSB was 40.5 mg/g. Monolayer of MG molecules formed chemical bonds on the homogenous surface of CSB. Keywords : Manihotesculenta Crantz charcoal; black carbon; adsorption.

Pd nanoparticles with uniform, self-assembled pompon-like nanostructure were synthesized by thermal decomposition of palladium acetate under microwave irradiation with methyl isobutyl ketone (MIBK) as a solvent in the presence of a little amount of ethylene glycol (EG) and KOH without using any special stabilizers. The as-synthesized Pd nano-pompons were characterized by transmission electron microscopy, X-ray photoelectron spectroscopy and X-ray powder diffraction. The results show that the as-prepared Pd nano-pompons with the average diameters in the range of 28–81 nm were self-assemblies organized by hundreds of smaller primary nanoparticles with an average dimension of about 2.4 nm. The sizes of Pd nano-pompons can be well controlled by adjusting the concentration of palladium acetate. A little amount of EG and KOH also plays an important role in controlling the size, uniformity and dispersion of Pd nano-pompons. The Pd nano-pompons can be easily supported on γ-Al 2 O 3 and their catalytic activity was examined preliminarily.

Co particles were synthesized with mean particle sizes in the range of 3.2–171.4 nm in ambient atmosphere by reduction of cobalt salt with sodium borohydride as the reducing reagent, a combination of alcohols as solvents and a triblock copolymer P123 (EO 20 PO 70 EO 20 ) as the surfactant. The particle size and its distribution were controlled by varying the synthesis parameters such as the viscosity of the medium, the amount of alcohols or P123 in the reaction system. FT-IR and X-ray photoelectron spectroscopy (XPS) measurements confirmed the interaction between the oxygen atoms of P123 and Co 2+ or Co 0 . Detailed surface analyses by XPS and HRTEM revealed that the synthesized particles consisted of Co 0 metal surrounded by amorphous CoO, Co 2 B and chemisorbed P123.

Poly(ether ether ketone) (PEEK) was synthesized with a good yield, by nucleophilic substitution reaction of 4,4’-difluorobenzophenone (DFBP) with hydroquinone (HQ) in the presence of anhydrous potassium carbonate (K2CO3) under microwave (MW) irradiation. The highest yield of 96.1% was obtained using sulfolane as the solvent and with a reaction time of only 55 min. The reaction time was reduced greatly compared with conventional heating. The product was characterised by infrared spectroscopy (IR), X-ray diffraction (XRD), thermogravimetric analysis (TGA) and differential scanning calorimetry (DSC). The polymer, having inherent viscosities of 0.71 dlg-1, has excellent thermal stability as shown by 10% weight loss in nitrogen at about 563 °C. The XRD pattern confirmed the semicrystalline character of PEEK synthesized.

Using two different methods, Ru nanoparticles have been synthesized by chemical reduction of ruthenium nitrosyl nitrate in ethylene glycol using Poly (N-vinyl-2-pyrrolidone) (PVP) as a stabilizer. In a one-step reaction, the average diameters of Ru nanoparticles were controlled in the range of 1.2–6.5 nm with narrow size distributions by changing the synthesis procedure and reaction conditions. In the seeding growth reaction, the Ru nanoparticle size was also precisely controlled by varying the seeds to Ru3+ ions ratio, ruthenium particles with different sizes (3.8–7.3 nm) were synthesized.

This paper investigates the photorefractive properties of iron doped lithium niobate with different [Li]/[Nb] ratios. The experimental results show two photorefractive centres for iron doped near-stoichiometric lithium niobate crystal. Besides Fe2+ and Fe3+ ions, small polarons and bipolarons are considered as another photoactive centre.

Alumina nanofibers of high aspect ratio with surface area of >300 m2 g−1 has been prepared successfully in bulk quantities by the sol–gel method. The synthesis parameters including the binary water–alcohol solvent system to aluminium isopropoxide ratio, pH, type of solvent and aging temperature affect the uniformity and formation of nanofibers. It is proposed that alumina nanofibers were formed by the curling of the nanosheets upon condensation after the hydrolysis. The phase evolution of alumina nanofibers from pseudoboehmite to α phase has been shown by XRD and FTIR. 27Al NMR investigations show that the Al atoms are six and four coordinated. The morphology of the alumina nanofibers does not change much as the calcination temperature was increased. In addition, the average pore size increases and the BET surface area decreases as a function of calcination temperature. The thermal behavior of alumina nanofibers was investigated by TGA.

A novel design method for high Q piezoelectric resonators was presented and proposed using the 3-D equations of linear piezoelectricity with quasi-electrostatic approximation which include losses attributed to mechanical damping in solid and resistance in current conduction. There is currently no finite element software for estimating the Q of a resonator without apriori assumptions of the resonator im- pedance or damping. There is a necessity for better and more realistic modeling of resonators and filters due to miniaturization and the rapid advances in frequency ranges in telecommunication. We presented new three-dimensional finite element models of quartz and barium titanate resonators with mechanical damping and resistance in current conduction. Lee, Liu and Ballato's 3-D equations of linear piezoelectricity with quasi-electro- static approximation which include losses attributed to mechanical damping in solid and resistance in current conduction were formulated in a weak form and implemented in COMSOL. The resulting finite element model could predict the Q and other electrical parameters for any piezoelectric resonator without apriori as- sumptions of damping or resistance. Forced and free vibration analyses were per- formed and the results for the Q and other electrical parameters were obtained. Comparisons of the Q and other electrical parameters obtained from the free vibra- tion analysis with their corresponding values from the forced vibration analysis were found to be in excellent agreement. Hence, the frequency spectra obtained from the free vibration analysis could be used for designing high Q resonators. Results for quartz thickness shear AT-cut and SC-cut resonators and thickness stretch poled barium titanate resonators were presented. An unexpected benefit of the model was the prediction of resonator Q with energy losses via the mounting supports.

A series of narrowly distributed nanoparticles with different sizes of platinum oxide stabilized by polyvinylpyrrolidone (PVP) were synthesized by hydrolytic decomposition of platinum chloride. The as-synthesized nanoparticles were characterized by UV–vis, TEM, and XPS examination. Studies on the parameters influencing the size of the as-synthesized platinum oxide nanoparticles were carried out. The pH of the solution was demonstrated to be the main factor affecting the particle diameter. The particles size also decreased with the increasing molar ratio of stabilizer (PVP):PtCl 4 . The influence of the concentration of sodium acetate on the rate of hydrolytic decomposition and the condensation reaction was studied. It was found that increasing the concentration of sodium acetate increased the rate of the condensation reaction nearly linearly.

Chitosan-stabilized Pt (chi-Pt) or Pd (chi-Pd) colloidal nanoparticles catalyst prepared with various chitosan–metal molar ratios and reducing agents were characterized. Chitosan could stabilize Pt and Pd with minimum chitosan:M ratio of 5:1 and 2:1 respectively. The finest and well-dispersed particles of chi-Pt or chi-Pd were obtained when methanol or NaBH 4 were used as the reducing agents. Chi-Pt and chi-Pd reduced by hydrazine gave aggregated particles in all chitosan molar ratios. Chitosan could control particle size of Pt or Pd to within 1.9–2.2 nm when CH 3 OH or NaBH 4 was used as the reducing agents. Palladium or Platinum catalysis on cyclooctene hydrogenation gave cyclooctane. Hydrogenation of octene catalyzed by chi-Pd gave octane, 2-octene and 3-octene while chi-Pt prepared by methanol reduction showed 99.99% selectivity and conversion to octane. The catalytic activity of chi-Pt was higher than chi-Pd for both the hydrogenations.

Polyvinylpyrrolidone stabilized Pt and Pd colloids with mean particle sizes ranging from 1.5 to 3.1 nm were prepared and are effective catalysts for the selective hydrogenation of polyunsaturated soybean oil at 35 °C and atmospheric pressure. The rate constants for the three stages of hydrogenation from linoleneate to linoleate to oleate and to stearate were determined and their ratios, which signify the selectivity were calculated. Pt and Pd catalysts show different rates of hydrogenation towards the double bonds. Pt catalyst has lower oleate selectivity leading to higher yields of saturated product but lower percentage of trans-isomer than the Pd catalyst at comparable mean particle size of 1.5 nm. The oleate selectivity increases while the linoleate selectivity as well as the activity decreases with an increase of the mean particle size. An intermediate trans,trans-linoleate was detected for the Pt catalyst with larger particle mean size.

Seafood processing waste is a potentially rich source of several useful products including chitin (Meanwell and Shama 2008), and has long been generated in large tonnages worldwide (Chang et al. 2007). Chitin is economical and is the second most abundant bio-waste material after cellulose (Shahidi et al. 1999). Annual worldwide chitin production from arthropods (e.g., crustaceans and insects), molluscs (e.g., squid and cuttlefish) and fungi is estimated at about 100 × 109 t (Tharanathan and Kittur 2003). A steady supply of chitinous waste materials from the seafood processing industry has been the major source of commercial products such as chitin and chitosan (Hayes 2012). The increasing consumption of krill oil and mushrooms has also been an additional source for commercial chitin (Nicol and Hosie 1993; Vetter 2007).

The role of boron species in selective hydrogenation of o-chloronitrobenzene (o-CNB) over polymer-stabilized ruthenium colloids has been studied. Of the two kinds of boron species (boride and borate) present in ruthenium colloids prepared by NaBH4 reduction, it was verified that only borate had a significant effect on the hydrogenation of o-CNB, while boride performed as a spectator. When metal cations were added into ruthenium colloidal catalyst system as modifiers, respectively, we observed that the synergetic effect between borate and metal cations occurred in these systems. It is suggested that metal complex ions were formed between the metal cations and borate ions.