Identification of Phenolic Compounds by LC-MS/MS and Evaluation of Bioactive Properties of Two Edible Halophytes: Limonium effusum and L. sinuatum

This work aimed to evaluate the phenolic content and in vitro antioxidant, antimicrobial and enzyme inhibitory activities of the methanol extracts and their fractions of two edible halophytic Limonium species, L. effusum (LE) and L. sinuatum (LS). The total phenolic content resulted about two-fold higher in the ethyl acetate fraction of LE (522.82 ± 5.67 mg GAE/g extract) than in that of LS (274.87 ± 1.87 mg GAE/g extract). LC-MS/MS analysis indicated that tannic acid was the most abundant phenolic acid in both species (71,439.56 ± 3643.3 µg/g extract in LE and 105,453.5 ± 5328.1 µg/g extract in LS), whereas hyperoside was the most abundant flavonoid (14,006.90 ± 686.1 µg/g extract in LE and 1708.51 ± 83.6 µg/g extract in LS). The antioxidant capacity was evaluated by DPPH and TAC assays, and the stronger antioxidant activity in ethyl acetate fractions was highlighted. Both species were more active against Gram-positive bacteria than Gram negatives and showed considerable growth inhibitions against tested fungi. Interestingly, selective acetylcholinesterase (AChE) activity was observed with LE and LS. Particularly, the water fraction of LS strongly inhibited AChE (IC₅₀ = 0.199 ± 0.009 µg/mL). The ethyl acetate fractions of LE and LS, as well as the n-hexane fraction of LE, exhibited significant antityrosinase activity (IC₅₀ = 245.56 ± 3.6, 295.18 ± 10.57 and 148.27 ± 3.33 µg/mL, respectively). The ethyl acetate fraction and methanol extract of LS also significantly inhibited pancreatic lipase (IC₅₀ = 83.76 ± 4.19 and 162.2 ± 7.29 µg/mL, respectively). Taken together, these findings warrant further investigations to assess the potential of LE and LS as a bioactive source that can be exploited in pharmaceutical, cosmetics and food industries.     

Sufficient Global Optimality Conditions for Bivalent Quadratic Optimization

We prove a sufficient global optimality condition for the problem of minimizing a quadratic function subject to quadratic equality constraints where the variables are allowed to take values –1 and 1. We extend the condition to quadratic problems with matrix variables and orthonormality constraints, and in particular to the quadratic assignment problem.     

Sensor Platform with a Custom‐tailored Aptamer for Diagnosis of Synthetic Cannabinoids

Synthetic cannabinoids (SCs) are the large group of abused drugs and detection of them is still a challenge. Hence, new methods for analysis of SCs are being investigated. We aimed to develop a novel system for selective analysis of SCs. First, various custom‐tailored aptamers against the target SCs were selected through GO‐SELEX process. Toggling between different SC analytes during successive rounds of selection was performed to generate cross‐reactive aptamers. Then, the amino‐capped aptamers were synthesized and easily attached to the cysteamine‐covered gold electrodes. Analytical parameters and selectivity of the aptasensors were compared by using electrochemical techniques. After comparison of the analytical features and selectivity towards target analytes, one of the aptamers designated as Apta‐1 was chosen for further measurements. The aptasensor was tested by using differential pulse voltammetry technique against JWH‐018 (5‐pentanoic acid), selected as a model for SCs. The linearity and limit of detection were determined as 0.01–1.0 ng/mL and 0.036 ng/mL. Finally, sample application in synthetic urine samples was successfully performed with standard addition method, as confirmed by LC‐QTOF/MS. JWH‐018 (4‐hydroxypentyl), JWH‐073 (3‐hydroxybutyl), JWH‐250 (5‐hidroxypentyl) and HU‐210 were used to test the selectivity of the aptasensor and the system was shown to recognize all these SCs. Also other illegal drugs did not significantly interfere with the signal responses.     

Size and Shape Prediction of Colloidal Metal Oxide MgBaFeO Particles from Light Scattering Measurements

The size and structure of colloidal metal oxide (MgBaFeO) particles are determined using an Elliptically Polarized Light Scattering (EPLS) technique. The approach is based on a hybrid experimental/theoretical study where the experimental data are compared against predictions obtained using a T-Matrix model that accounts for particle shape irregularities. A power-law distribution function with two parameters is employed to account for the particle size distribution. The refractive index of the particles in ethyl alcohol is calculated based on the Maxwell-Garnet formula. The experiments are conducted using a second-generation nephelometer. It is shown that the current EPLS measurements can effectively be used for identification of both the shape and the size of the colloids.     

Immobilization of Tyrosinase in Poly(2-thiophen-3-yl-alkyl ester) Derivatives

In this study, construction of novel biosensors for the determination of phenolic compound was performed via immobilization of tyrosinase during the electrochemical synthesis of conducting block copolymers of 2-thiophen-3-yl-alkyl ester derivatives with 3,4-ethylenedioxythiophene and synthesis of poly(3,4-ethylenedioxythiophene) (PEDOT). The resultant biosensors were characterized in terms of their maximum reaction rates, Michaelis–Menten constants (K_m), temperature and pH stabilities. All the copolymer matrices represented higher reaction rates and higher K_m values in comparison to both polypyrrole and PEDOT matrices and a relation between the morphology of the matrice and the kinetic parameters was observed. Biosensors maintained their activity even at temperatures as high as 80°C and could be used at pHs higher than 8 with high precision. The amount of phenolics in actual samples (red wines) was investigated using electrodes, and results were compared with those found from Folin–Ciocalteau method. Hence, the present study has proven the suitability of these copolymers to be used as polymer matrices for enzyme immobilization.     

Synthesis and characterization of soft polymeric nanoparticles and composites with tunable properties

Polymeric particles comprising acrylonitrile (AN)‐based core and acrylamide derivative–based shell in the submicron range with positive and negative charges were synthesized via microemulsion polymerization. 2‐Acrylamido‐2‐methylpropane sulfonic acid (AMPS) and 3‐(acrylamidopropyl)‐trimethyl ammonium chloride (APTMACl) were used as shell‐forming charged monomers onto AN core for the synthesis of p(AN‐co‐AMPS) and p(AN‐co‐APTMACl), respectively, using an oil‐in‐water emulsion system. To tune the characteristics of the core–shell particles, AN moieties in the core were amidoximated to change the nature of the core from hydrophobic (nitrile) to hydrophilic (amidoxime) nature. Additionally, colloidal magnetite particles (Fe₃O₄) produced by chemical coprecipitation technique under alkaline and inert conditions were also included inside p(AN‐co‐AMPS) and p(AN‐co‐APTMACl) particles as dual‐responsive nanocomposites against pH and magnetic field. With the magnetic properties, AN‐based core with modifiable characteristics and acrylamide‐based polyelectrolyte shells with variable charges and sizes were further used as drug carriers. For potential targeted drug delivery application of the synthesized soft particles and their composites Naproxen and Trimethoprim were used as model drugs, and he release studies were carried in phosphate buffer saline (pH = 7.4) at ambient temperature. © 2010 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem, 2010     

Scheduling unit-length jobs with precedence constraints of small height

We consider the problem of scheduling unit-length jobs on identical machines subject to precedence constraints. We show that natural scheduling rules fail when the precedence constraints form a collection of stars or a collection of complete bipartite graphs. We prove that the problem is in fact NP-hard on collections of stars when the input is given in a compact encoding, whereas it can be solved in polynomial time with standard adjacency list encoding. On a subclass of collections of stars and on collections of complete bipartite graphs we show that the problem can be solved in polynomial time even when the input is given in compact encoding, in both cases via non-trivial algorithms.     

Microfluidic DNA amplification—A review

The application of microfluidic devices for DNA amplification has recently been extensively studied. Here, we review the important development of microfluidic polymerase chain reaction (PCR) devices and discuss the underlying physical principles for the optimal design and operation of the device. In particular, we focus on continuous-flow microfluidic PCR on-chip, which can be readily implemented as an integrated function of a micro-total-analysis system. To overcome sample carryover contamination and surface adsorption associated with microfluidic PCR, microdroplet technology has recently been utilized to perform PCR in droplets, which can eliminate the synthesis of short chimeric products, shorten thermal-cycling time, and offers great potential for single DNA molecule and single-cell amplification. The work on chip-based PCR in droplets is highlighted.