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Molecules (Basel, Switzerland) Jul 2019Silica-supported metallic species have emerged as valuable green-chemistry catalysts because their high efficiency enables a wide range of applications, even at...
Silica-supported metallic species have emerged as valuable green-chemistry catalysts because their high efficiency enables a wide range of applications, even at industrial scales. As a consequence, the preparation of these systems needs to be finely controlled in order to achieve the desired activity. The present work presents a detailed investigation of an ultrasound-promoted synthetic protocol for the grafting of β-cyclodextrin (β-CD) onto silica. Truly, ultrasound irradiation has emerged as a fast technique for promoting efficient derivatization of a silica surface with organic moieties at low temperature. Three different β-CD silica-grafted derivatives have been obtained, and the ability of β-CD to direct and bind Cu when CD is bonded to silica has been studied. A detailed characterization has been performed using TGA, phenolphthalein titration, FT-IR, diffuse reflectance (DR), DR UV-Vis, as well as the inductively-coupled plasma (ICP) of the β-CD silica-grafted systems and the relative Cu-supported catalysts. Spectroscopic characterization monitored the different steps of the reaction, highlighting qualitative differences in the properties of amino-derivatized precursors and final products. In order to ensure that the Cu-β-CD silica catalyst is efficient and robust, its applicability in Cu(II)-catalyzed alkyne azide reactions in the absence of a reducing agent has been explored. The presence of β-CD and an amino spacer has been shown to be crucial for the reactivity of Cu(II), when supported.
Topics: Catalysis; Copper; Cyclodextrins; Molecular Structure; Silicon Dioxide; Spectrum Analysis; Thermogravimetry
PubMed: 31284697
DOI: 10.3390/molecules24132490 -
Polymers Jul 2019Poly(arylene ether nitrile)s with sulfonic and carboxylic groups (SCPEN) were synthesized to investigate their electrical properties. This new series of copolymers were...
Poly(arylene ether nitrile)s with sulfonic and carboxylic groups (SCPEN) were synthesized to investigate their electrical properties. This new series of copolymers were prepared by copolymerization of phenolphthalein, potassium hydroquinonesulfonate, and 2,6-difluorobenzonitrile, in different mole ratios. Their thermal, mechanical and dielectric properties were investigated in detail. By adjusting the composition of sulfonic and carboxylic groups, it can be concluded that the dielectric constant increases with the increase of sulfonic groups, and mechanical and thermal properties improve with the increase of carboxylic groups. The as-prepared SCPEN films show potential applications in electronic storage materials, which provide insights into the correlation of SCPEN electrical properties with its chemical structure. The structure-property relationship is established to broaden the application of functionalized PEN. Furthermore, SCPEN with rich polar groups may also be used as the polymer matrix to increase the interaction with the filler surface, ensuring a better dispersion of filler in the matrix. This provides a reference for the development of high dielectric materials.
PubMed: 31277253
DOI: 10.3390/polym11071135 -
Polymers Nov 2018A series of commercial difunctional benzoxazine monomers are characterized using thermal and thermo-mechanical techniques before constructing representative polymer...
A series of commercial difunctional benzoxazine monomers are characterized using thermal and thermo-mechanical techniques before constructing representative polymer networks using molecular simulation techniques. Good agreement is obtained between replicate analyses and for the kinetic parameters obtained from differential scanning calorimetry data (and determined using the methods of Kissinger and Ozawa). Activation energies range from 85 to 108 kJ/mol (Kissinger) and 89 to 110 kJ/mol (Ozawa) for the uncatalyzed thermal polymerization reactions, which achieve conversions of between 85% and 97%. Glass transition temperatures determined from differential scanning calorimetry and dynamic mechanical thermal analysis are comparable, ranging from BA-a (151 °C, crosslink density 3.6 × 10 mol cm) containing the bisphenol A moiety to BP-a, based on a phenolphthalein bridge (239 to 256 °C, crosslink density 5.5 to 18.4 × 10 mol cm, depending on formulation). Molecular dynamics simulations of the polybenzoxazines generally agree well with empirical data, indicating that representative networks have been modelled.
PubMed: 30961175
DOI: 10.3390/polym10111250 -
Polymers Oct 2018A molecularly imprinted polymer (MIP) for highly selective solid-phase extraction (SPE) of bisphenol A (BPA) was prepared using phenolphthalein (PP) as the novel dummy...
A Phenolphthalein-Dummy Template Molecularly Imprinted Polymer for Highly Selective Extraction and Clean-Up of Bisphenol A in Complex Biological, Environmental and Food Samples.
A molecularly imprinted polymer (MIP) for highly selective solid-phase extraction (SPE) of bisphenol A (BPA) was prepared using phenolphthalein (PP) as the novel dummy template by bulk polymerization. A particle diameter distribution of 40⁻60 μm, a specific surface area of 359.8 m²·g, and a total pore volume of 0.730 cm³·g for the prepared PP-imprinted polymer (PPMIP) were obtained. Good selectivity and specific adsorption capacity for BPA of the prepared PPMIP were also demonstrated by the chromatographic evaluation and sorption experiments. The PPMIP as a SPE sorbent was evaluated for the selective extraction and clean-up of BPA from complex biological, environmental, and food samples. Meanwhile, an accurate and sensitive analytical method based on the PPMIP-SPE purification procedure coupled with high performance liquid chromatography-diode array detector (HPLC-DAD) detection has been successfully developed for the rapid determination of BPA from these samples, with detection limits of 1.3 ng·mL for bovine serum and milk, 2.6 ng·mL for human urine and edible oil, 5.2 ng·mL for soybean sauce, and 1.3 ng·g for sediment. The BPA recoveries at two different spiking levels were in the range of 82.1⁻106.9%, with relative standard deviation (RSD) values below 7.7%.
PubMed: 30961075
DOI: 10.3390/polym10101150 -
Materials (Basel, Switzerland) Jan 2019The carbonation rate of reinforced concrete is influenced by three parameters, namely temperature, relative humidity, and concentration of carbon dioxide (CO₂) in the...
The carbonation rate of reinforced concrete is influenced by three parameters, namely temperature, relative humidity, and concentration of carbon dioxide (CO₂) in the surroundings. As knowledge of the service lifespan of reinforced concrete is crucial in terms of corrosion, the carbonation process is important to study, and high-performance durable reinforced concretes can be produced to prolong the effects of corrosion. To examine carbonation resistance, accelerated carbonation testing was conducted in accordance with the standards of BS 1881-210:2013. In this study, 10⁻30% of micro palm oil fuel ash (mPOFA) and 0.5⁻1.5% of nano-POFA (nPOFA) were incorporated into concrete mixtures to determine the optimum amount for achieving the highest carbonation resistance after 28 days water curing and accelerated CO₂ conditions up to 70 days of exposure. The effect of carbonation on concrete specimens with the inclusion of mPOFA and nPOFA was investigated. The carbonation depth was identified by phenolphthalein solution. The highest carbonation resistance of concrete was found after the inclusion of 10% mPOFA and 0.5% nPOFA, while the lowest carbonation resistance was found after the inclusion of 30% mPOFA and 1.5% nPOFA.
PubMed: 30609786
DOI: 10.3390/ma12010130 -
Medical Principles and Practice :... 2019Nutraceuticals are advertised and sold with the label claim of being natural and safe herbal products. Due to the absence of clear regulations and guidelines for safety... (Observational Study)
Observational Study
OBJECTIVES
Nutraceuticals are advertised and sold with the label claim of being natural and safe herbal products. Due to the absence of clear regulations and guidelines for safety assessments of these products, nutraceuticals are commonly adulterated in order to increase sales. The objective of the current study was to design a comprehensive evaluation system to assess the safety, efficacy, authenticity according to label claim, and pharmaceutical quality of herbal slimming products in between 2015 and 2017.
METHODS
We designed a comprehensive assessment system to evaluate the safety, authenticity according to label claim, and pharmaceutical quality of slimming nutraceuticals. Six different popular products were evaluated (Zotreem Plus®, Zotreem Extra®, Malaysian Super Slim®, AB Slim®, Chinese Super Slim®, and Metabolites®). The pharmaceutical evaluation included analyzing the samples via high-performance liquid chromatography to determine any possible adulterants. Additionally, the products' physical properties were assessed via pharmacopeial tests. Finally, a microbial evaluation and a cross-sectional observational retrospective prevalence study were conducted to assess the products' safety and efficacy. -Results: The tested products were found to be adulterated with unreported active pharmaceutical ingredients such as sibutramine, sildenafil, phenolphthalein, and orlistat. Furthermore, they contained heterogeneous amounts of adulterants and exhibited an unsatisfactory pharmaceutical and microbial quality. Finally, the observational survey conducted on users showed that high percentages of participants suffered from common side effects such as depression, diarrhea, and hypertension.
CONCLUSIONS
These products threaten the health of consumers. There is a need to raise awareness of the lethal consequences of illegal nutraceuticals.
Topics: Anti-Obesity Agents; Appetite Depressants; Cross-Sectional Studies; Dietary Supplements; Drugs, Chinese Herbal; Egypt; Humans; Nonprescription Drugs; Weight Loss
PubMed: 30517949
DOI: 10.1159/000495986 -
The Turkish Journal of Gastroenterology... Mar 2019Fixed drug eruption (FDE) is a type of drug reaction characterized by localized erythema, hyperpigmentation, and bullous at the same site(s), generally observed... (Review)
Review
Fixed drug eruption (FDE) is a type of drug reaction characterized by localized erythema, hyperpigmentation, and bullous at the same site(s), generally observed following every intake of a causative drug. Delayed-type cellular hypersensitivity (Type IVC) is considered to play a role in FDE etiology. Several antibiotics, barbiturates, oral contraceptives, nonsteroidal anti-inflammatory drugs, laxative-containing phenolphthalein, metronidazole, and quinine are known to be the primary drugs responsible for FDE. Bullous FDE, on the other hand, is a relatively rare form of FDE. Hepatitis B is a significant worldwide health problem, and entecavir is a common nucleoside (deoxyguanosine) analog used for treating hepatitis B; however, it has various side effects, such as lactic acidosis, myalgia, azotemia, hypophosphatemia, headache, diarrhea, pancreatitis, and neuropathy, and, in rare cases, cutaneous drug eruption. Our aim is to present a case of entecavir-associated bullous drug reaction, which has not been reported in the literature. Furthermore, we performed a review of literature to compile previously reported entecavir-associated drug reactions.
Topics: Antiviral Agents; Drug Eruptions; Female; Guanine; Hepatitis B; Hepatitis B virus; Humans; Middle Aged
PubMed: 30459136
DOI: 10.5152/tjg.2018.17887 -
Analytical Sciences : the International... Mar 2019We propose the creation of reusable indicator-sorbed-solids, using anion-exchange resins or kaolin as supports, with the aim to reduce chemical use towards green...
We propose the creation of reusable indicator-sorbed-solids, using anion-exchange resins or kaolin as supports, with the aim to reduce chemical use towards green analytical chemistry. Indicators (phenolphthalein, thymol blue and butterfly pea flower extract as a natural indicator) sorbed on a solid support, were employed in acid-base titration, in both homogenous aqueous and heterogenous aqueous organic phases. Applications of the developed techniques to some real samples, such as vinegar, colored fruit juice and vegetable oil, have been demonstrated.
Topics: Acetic Acid; Adsorption; Anion Exchange Resins; Food Analysis; Fruit and Vegetable Juices; Green Chemistry Technology; Indicators and Reagents; Kaolin; Plant Oils; Titrimetry
PubMed: 30344207
DOI: 10.2116/analsci.18N019 -
Theranostics 2018Saliva as a sample matrix is rapidly gaining interest for disease diagnosis and point-of-care assays because it is easy to collect (non-invasive) and contains many...
Saliva as a sample matrix is rapidly gaining interest for disease diagnosis and point-of-care assays because it is easy to collect (non-invasive) and contains many health-related biomarkers. However, saliva poses particular problems relative to more common urine and blood matrices, which includes low analyte concentrations, lack of understanding of biomolecule transportation and inherent viscosity variability in human samples. While several studies have sought to improve assay sensitivity, few have addressed sample viscosity specifically. The goal of this study is to minimize the effect of sample viscosity on paper-based analytical devices (PADs) for the measurement of pH and nitrite in human saliva. PADs were used to measure salivary pH from 5.0 to 10.0 with a universal indicator consisting of chlorophenol red, phenol red and phenolphthalein. Nitrite determination was performed using the Griess reaction. Artificial saliva with viscosity values between 1.54 and 5.10 mPa∙s was tested on the proposed PAD. To ensure the proposed PADs can be tailored for use in-field analysis, the devices were shipped to Australia and tested with human specimens. Initial experiments showed that viscosity had a significant impact on the calibration curve for nitrite; however, a more consistent curve could be generated when buffer was added after the sample, irrespective of sample viscosity. The linear range for nitrite detection was 0.1 to 2.4 mg/dL using the improved method. The nitrite measurement in artificial saliva also showed a good correlation with the standard spectrophotometry method (=0.8484, paired sample -test, n=20). Measured pH values from samples with varying viscosities correlated well with the results from our pH meter. The inherent variation of salivary viscosity that impacts nitrite and pH results can be addressed using a simple washing step on the PAD without the need for complex procedures.
Topics: Australia; Chemistry Techniques, Analytical; Humans; Hydrogen-Ion Concentration; Nitrites; Paper; Saliva; Sensitivity and Specificity; Specimen Handling; Viscosity
PubMed: 30083260
DOI: 10.7150/thno.24941 -
Sensors (Basel, Switzerland) Jun 2018We present the mixing and merging of two reactive droplets on top of an open surface. A mobile droplet (1.0 M HCl solution + iron oxide particles) is...
We present the mixing and merging of two reactive droplets on top of an open surface. A mobile droplet (1.0 M HCl solution + iron oxide particles) is magnetically-actuated to merge with a sessile droplet (1.0 M NaOH + phenolphthalein). The heat from the exothermic reaction is detected by a thermocouple. We vary the droplet volume (1, 5 and 10 μL), the magnet speed (1.86, 2.79, 3.72 and 4.65 mm/s) and the iron oxide concentration (0.010, 0.020 and 0.040 g/mL) to study their influences on the mixing time, peak temperature and cooling time. The sampled recording of these processes are provided as . We observe the following trends. First, the lower volume of droplet and higher speed of magnet lead to shorter mixing time. Second, the peak temperature increases and cooling time decreases at the increasing speed of magnet. Third, the peak temperature is similar for bigger droplets, and they take longer to cool down. Finally, we also discuss the limitations of this preliminary study and propose improvements. These observations could be used to improve the sensitivity of the open chamber system in measuring the exothermic reaction of biological samples.
PubMed: 29857584
DOI: 10.3390/s18061767