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.     

Electrochemical probe DNA design in PCR amplicon sequence for the optimum detection of microbiological diseases

Direct electrochemical genosensor was developed for the detection of a probe sequence relative position in a PCR amplicon for the optimum detection of bacterial and microbiological diseases, in this study. The genosensor relies on a label-free electrochemical detection. The amino-linked inosine modified (guanine-free) coequal capture probes which were chosen from different parts of a PCR amplicon, immobilized on to disposable pencil graphite electrodes (PGE) by electrostatically and covalently. As a model case Hepatitis B virus (HBV) genome amplicon was used for the detection and specification. Hybridization was occurred after surface coverage with denatured amplicons. After hybridization, optimum probe sequence position was identified by using the differences between the responses of guanine oxidation signals. The results of this study might have a great convenience for the microbiological diseases detection applications such as DNA micro arrays.     

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.     

Bandwidth of bipartite permutation graphs in polynomial time

We give the first polynomial-time algorithm that computes the bandwidth of bipartite permutation graphs. Bandwidth is an NP-complete graph layout problem that is notorious for its difficulty even on small graph classes. For example, it remains NP-complete on caterpillars of hair length at most 3, a very restricted subclass of trees. Much attention has been given to designing approximation algorithms for computing the bandwidth, as it is NP-hard to approximate the bandwidth of general graphs with a constant factor guarantee. The problem is considered important even for approximation on restricted classes, with several distinguished results in this direction. Prior to our work, polynomial-time algorithms for exact computation of bandwidth were known only for caterpillars of hair length at most 2, chain graphs, cographs, and most interestingly, interval graphs.