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β-Cyclodextrin (β-CD) modified silver nanoparticles (AgNPs), denoted as β-CD/AgNPs, were prepared by a simple one-pot method. Due to the inherent chirality of β-CD, the developed β-CD/AgNPs exhibited higher affinity toward l-tyrosine (l-Tyr) than d-tyrosine (d-Tyr), leading to serious aggregation of AgNPs in the presence of l-Tyr. Consequently, the l-Tyr induced aggregation of AgNPs can result in signal amplification in the differential pulse voltammograms (DPVs) of l-Tyr, which can be applied for the electrochemical chiral discrimination of the Tyr enantiomers. Other chiral amino acids including tryptophan and phenylalanine can also be successfully discriminated with the β-CD/AgNPs, suggesting high universality of the developed chiral sensor.

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.

Here, ionized chiral carbon dots, (S,S)-C-dots-1 (λex = 430 nm, λem = 480 nm), were synthesized via a facile route with relatively high quantum yield (∼24.4%) and used as a fluorescent chiral sensor. One of the advantages of the synthetic process is that it avoids the loss of the chiral center. That is, the chiral bromo compound can directly form an ionic pair with the pyridyl group, which is derived from the amine precursor in the first step. Furthermore, (S,S)-C-dots-1 shows clear discrimination toward different configurations of nonaromatic amino alcohols in the presence of Cu(ii). When the (R)-isomer is added to a solution of (S,S)-C-dots-1 + Cu(ii), it shows much higher fluorescent intensity than the (S)-isomer. The values of IR/IS are 2.9 and 2.3 for 2-aminobutan-1-ol and 2-aminopropan-1-ol, respectively. In summary, we believe that this work can expand the synthetic routes and potential applications of functional carbon dots in the field of enantioselective sensing.

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.

Cat manure (CM) possesses high level of nutrients for growing food crop. However, animal manure may contain toxic elements that may contaminate food crop. Spent coffee ground (SCG) may be used to reduce mobility of heavy metals and reduce crop uptake. In this study, SCG was composted with CM for 31 days to produce a co-compost (SCG-CM) for growing spinach (Spinacia oleracea). The growth rate of spinach was assessed until its maturity, and the metal uptake of spinach shoot was determined thereafter using inductively coupled plasma-optical emission spectroscopy (ICP-OES). The effect of soil treatment with SCG-CM on the height and elemental composition of spinach were compared with that of chicken manure compost (CMC). The prepared composts were primarily organic matter (72.9-81.4 % w/w) with the rest are ash (13.3-23.4 % w/w) and moisture (1.2-2.6 % w/w). Zinc content in SCG-CM (1261 ± 0.1 mg/kg) is significantly higher than that of soil and CMC (p < 0.05) and has exceeded the maximum permissible limit set by European Union Standard (2002) and the Malaysian Compost Quality Standard and Guidelines (2000). Matured spinach reached maximum plant height after 33 days. The amendment of SCG-CM significantly increased the height of spinach (32 ± 6 cm) compared to that of CMC (13 ± 1 cm) (p < 0.05). However, contents of Zn, Cu, Pb and Cd were not increased for spinach grown in the SCG-CM-amended soil, and the level of those elements are below permissible limit set by the Malaysian Food Act 1983 and Food Regulations 1985. This study shows that SCG-CM is effective in improving yield without causing accumulation of toxic trace elements in spinach.

We report on a 32-MHz quartz temperature compensated crystal oscillator (TCXO) fully integrated with commercial CMOS electronics and vacuum packaged at wafer level using a low-temperature MEMS-after quartz process. The novel quartz resonator design provides for stress isolation from the CMOS substrate, thereby yielding classical AT-cut f/T profiles and low hysteresis which can be compensated to±0.2 parts per million over temperature using on-chip third-order compensation circuitry. The TCXO operates at low power of 2.5 mW and can be thinned to as part of the wafer-level eutectic encapsulation. Full integration with large state-of-the-art CMOS wafers is possible using carrier wafer techniques.

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.

Hierarchical mesoporous Co3O4/C@MoS2 core-shell structured materials are synthesized via a two-step calcination and a solvothermal method using cobalt metal-organic frameworks (cobalt-MOFs, ZIF-67) and (NH4)2MoS4 as the precursors of Co3O4/C and MoS2, respectively, which is a new class of core-shell materials as supercapacitor electrode materials. The obtained Co3O4/C@MoS2 exhibits high specific capacitance (1076 F g−1 at 1 A g−1), rate capability (76.9% capacitance retention at 10 A g−1) and cyclic stability (64.5% capacitance retention after 5000 cycles at 10 A g−1). Moreover, the content of MoS2 greatly influences the electrochemical performances of the obtained core-shell materials. The results demonstrate that the as-synthesized ZIF-67 can be used as a promising candidate for designing Co3O4 based core-shell materials used in supercapacitors.

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.

Chitosan-stabilised metallic Pd (CTS-Pd) and Pt (CTS-Pt) nanoparticles were synthesised and used for the hydrogenation of palm oil. With the goal of preparing hydrogenated oil with low trans fatty acid (TFA) content under ambient conditions, Fe anion was added as the secondary metallic precursor to synthesise chitosan-stabilised bimetallic Pd–Fe (CTS-Pd–Fe) and Pt–Fe (CTS-Pt–Fe) nanoparticles. The catalytic hydrogenations with newly prepared nanoparticles were performed in aqueous solution under ambient temperature and atmospheric pressure. The addition of Fe was found to improve the catalytic activity and decrease the selectivity for TFA. Hydrogenation with CTS-Pt–Fe affords the optimal results, producing 3.8% TFA at 92.1% conversion of C18:2 and no TFA was formed until the content of C18:2 was lower than 1.7%. Based on the analyses, it can be demonstrated that the preferential conversion of C18:2 to cis C18:1 and cis C18:1 to C18:0 leads to the low formation of TFA.

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.

Oil palm plantations produce palm kernel shell (PKS) that can be converted into biochar for environment-friendly soil remediation and water treatment. Oxidation with hydrogen peroxide (H2O2) may enhance surface characteristics and the quality of low-rank PKS biochar as a sorbent for environmental decontamination. This study aims to determine the effect of oxidation on the surface characteristics (i.e., specific surface area, surface charge, and chemical properties) of PKS biochar, and compared with that of PKS activated carbon. The surface area for the oxidised PKS biochar was similar to that of PKS biochar, indicating that oxidation did not remove the pore blocking material from the surface area of the PKS biochar. However, oxidation has increased the amount of negatively charged oxygen functional groups in PKS biochar, as indicated by the analyses of the Fourier transform infrared spectroscopy (FTIR) and cation exchange capacity (CEC). The CEC value of raw and activated PKS biochar were similar and 4.6 and 2.6 times lower for PKS biochar and oxidised PKS biochar, respectively. Oxidation caused enlargement of pores on PKS biochar and caused a reduction of specific surface area. More research is required to establish the process conditions to create a greater surface area and sorption capacity.

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.

Mesenchymal stem cells are widely used in many pre-clinical and clinical settings. Despite advances in molecular technology; the migration and homing activities of these cells in in vivo systems are not well understood. Labelling mesenchymal stem cells with gold nanoparticles has no cytotoxic effect and may offer suitable indications for stem cell tracking. Here, we report a simple protocol to label mesenchymal stem cells using 80 nm gold nanoparticles. Once the cells and particles were incubated together for 24 h, the labelled products were injected into the rat subretinal layer. Micro-computed tomography was then conducted on the 15th and 30th day post-injection to track the movement of these cells, as visualized by an area of hyperdensity from the coronal section images of the rat head. In addition, we confirmed the cellular uptake of the gold nanoparticles by the mesenchymal stem cells using transmission electron microscopy. As opposed to other methods, the current protocol provides a simple, less labour-intensive and more efficient labelling mechanism for real-time cell tracking. Finally, we discuss the potential manipulations of gold nanoparticles in stem cells for cell replacement and cancer therapy in ocular disorders or diseases.

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.

A series of 3 wt% Ru embedded on ordered mesoporous carbon (OMC) catalysts with different pore sizes were prepared by autoreduction between ruthenium precursors and carbon sources at 1123 K. Ru nanoparticles were embedded on the carbon walls of OMC. Characterization technologies including power X-ray diffraction (XRD), nitrogen adsorption-desorption, transmission electron microscopy (TEM), and hydrogen temperature-programmed reduction (H2-TPR) were used to scrutinize the catalysts. The catalyst activity for Fischer-Tropsch synthesis (FTS) was measured in a fixed bed reactor. It was revealed that 3 wt% Ru-OMC catalysts exhibited highly ordered mesoporous structure and large surface area. Compared with the catalysts with smaller pores, the catalysts with larger pores were inclined to form larger Ru particles. These 3 wt% Ru-OMC catalysts with different pore sizes were more stable than 3 wt% Ru/AC catalyst during the FTS reactions because Ru particles were embedded on the carbon walls, suppressing particles aggregation, movement and oxidation. The catalytic activity and C5+ selectivity were found to increase with the increasing pore size, however, CH4 selectivity showed the opposite trend. These changes may be explained in terms of the special environment of the active Ru sites and the diffusion of products in the pores of the catalysts, suggesting that the activity and hydrocarbon selectivity are more dependent on the pore size of OMC than on the Ru particle size.

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

Chitosan (CTS)-stabilized bimetallic nanoparticles were prepared at room temperature (rt.) in aqueous solution. Palladium (Pd) and platinum (Pt) were selected as the first metals while iron (Fe) and nickel (Ni) functioned as the second metals. In order to obtain the noble metal core-transition metal shell structures, bimetallic nanoparticles were prepared in a two-step process: the preparation of mono noble metallic (Pd or Pt) nanoparticles and the deposition of transition metals (Fe or Ni) on the surface of the monometallic nanoparticles. The structures of the nanoparticles were studied using X-ray photoelectron spectroscopy (XPS) and transmission electron microscopy (TEM). The XPS results show that Pd and Pt exist mainly in zero valences. The presence of Fe and Ni in the bimetallic nanoparticles affects the binding energy of Pd and Pt. Moreover, the studies of O 1s spectra indicate the presence of Fe or Ni shells. The analyses of TEM micrographs give the particle size and size distributions while the high-resolution TEM (HRTEM) micrographs show the existence of noble metal core lattices. The results confirm the formation of noble metal core-transition metal shell structures.

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 Ce -incorporated structure of cubic large mesoporous molecular sieves, KIT-6, with different Ce contents were synthesized by a direct hydrothermal process. A sample of Ce -loaded KIT-6 material was synthesised by incipent wetness impregnation. Similarly, catalysts with 15 wt.% Co loading on the above supports were also synthesized by incipient wetness impregnation. The supports and catalysts were characterized by X-ray diffraction, diffuse reflectance UV-vis, solid-state 29Si magic-angle spinning nuclear magnetic resonance, H2 -temperature programmed reduction, H2 -temperature programmed desorption and oxygen titration. The structure of the KIT-6 support was well retained after Ce incorporation. Small amounts of Ce in the Co catalyst were found to improve the activity and increase the selectivity to C5+ hydrocarbons for Fischer–Tropsch synthesis, while larger amounts of Ce had the reverse effect. Meanwhile, methane selectivity shows an opposite trend as compared with that of C5+ selectivity. Ce -loaded KIT-6 supported Co catalyst showed lower activity than KIT-6 supported Co catalyst.

The potential of Pleurotus ostreatus spent mushroom compost (PSMC) as a green biosorbent for nickel (II) biosorption was investigated in this study. A novel approach of using the half-saturation concentration of biosorbent to rapidly determine the uptake, kinetics and mechanism of biosorption was employed together with cost per unit uptake analysis to determine the potential of this biosorbent. Fifty per cent nickel (II) biosorption was obtained at a half-saturation constant of 0.7 g biosorbent concentration, initial pH in the range of 4–8, 10 min contact time, 50 mL 50 mg/L nickel (II) initial concentration. The experimental data were well fitted with the Langmuir isotherm model and the maximum nickel (II) biosorption was 3.04 mg/g. The results corresponded well to a second pseudo order kinetic model with the coefficient of determination value of 0.9999. Based on FTIR analysis, the general alkyl, hydroxyl or amino, aliphatic alcohol and carbonyl functional groups of biosorbent were involved in the biosorption process. Therefore, biosorption of nickel (II) must involve several mechanisms simultaneously such as physical adsorption, chemisorption and ion exchange. Cost comparison for PSMC with Amberlite IRC-86 ion exchange resin indicates that the biosorbent has the potential to be developed into a cost effective and environmentally friendly treatment system.

The mycelial growth kinetics, cadmium biosorption capacity and main governing biosorption mechanism of Pleurotus ostreatus (oyster mushroom) have been determined in this study. The fungus mycelium exhibits a sig- moidal (S-shaped) growth curve in which the growth rates for the lag and exponential phases are 0.1 and 0.31 g/L·day, respectively. The grown fungus is subjected to elemental, infra-red and scanning electron microscopy-energy dispersive x-ray spectroscopy analyses, while biosorption data are fitted to established adsorption isotherm models, namely, Langmuir, Freundlich and Dubinin-Radushkevich. It is strongly suggested that the main governing mechanism involved is chemi- sorption due to good fitting of biosorption data to Langmuir and Dubinin-Radushkevich models with possibility of in- volvement of both ion exchange and complexation. Data presented in the study are very useful for design of future pilot- or industrial-scale biosorption water purification systems.

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