Using a cross-flow microfluidic chip for monodisperse UV-photopolymerized microparticles

In this paper, we report a microfluidic chip containing a cross-junction channel for the manipulation of UV-photopolymerized microparticles. Hydrodynamic-focusing is used to form a series of using 365 nm UV light to solidify the hydrogel droplets. We were able to control the size of the hydrogel droplets from 75 to 300 μm in diameter by altering the sample and by changing the flow rate ratio of the mineral oil in the center inlet channel to that of the side inlet channels. We found that the size of the emulsions increases with an increase in average velocity of the dispersed phase flow (polymer solution flow). The size of the emulsions decreases with an average velocity increase of the continuous phase flow (mineral oil flow). Experimental data show that the emulsions are very uniform. The developed microfluidic chip has the advantages of ease of fabrication, low cost, and high throughput. The emulsions generated are very uniform and have good regularity.     

Generation of droplets with different concentrations using gradient-microfluidic droplet generator

This study successfully uses the micro-mixers and flow-focusing devices, which are integrated into a gradient-microfluidic droplet generator, to generate the different sizes of the droplets with different concentrations simultaneously and applies these microcapsules for drug release. The sizes of these four types of droplet with different concentrations are uniformity with a coefficient of variation less than 5% and can be precisely controlled by adjusting the water phase flow rate and oil phase flow rate. Moreover, Ca-alginate microcapsules with different concentrations of the bovine serum albumin are used for uniform size drug release, and the Ca-alginate microcapsule size is from 60 to 105 μm in diameter. This developed microfluidic chip has the advantages of actively controlling the droplet diameter, simultaneously generating uniform-sized droplets with different concentrations, and having a simple process and a high throughput. This preparation approach for Ca-alginate microcapsules of four different concentrations will provide many potential applications for drug delivery and pharmaceutical area.     

A developed competitive immunoassay based on impedance measurements for methamphetamine detection

In this study, an electro-microchip was successfully used to detect the impedance signals of various methamphetamine (MET) concentrations based on the developed competitive immunoassay method. MET is a commonly used drug often abused by drug addicts and can cause irregular behavior; therefore, MET concentration detection is important for quantitative analysis. In this study, gold nanoparticles (AuNPs) were introduced into an electro-microchip through the specific binding of antibodies, thus constructing a bridge between two electrodes and allowing electrons to move between them. The decreasing impedance value can be easily measured with a commercial LCR meter. According to the collected measurements, a significant difference was observed in impedance signals after 13?min when MET concentrations were reduced. Additionally, a clear, distinguished impedance (a steep slope for both impedance and MET concentration) in the frequency effect (100?Hz?C1?MHz) was observed at 100?Hz. When the concentration of the anti-MET antibody?Ccolloidal gold conjugates was diluted 100×, the detectable limit for MET concentration was 1?ng/mL with 0.5???g/mL of BSA?CMET conjugate. Therefore, the developed electro-microchip is advantageous because it is effective with small sample volumes (30???L), is a form of rapid quantitative measurement, and works with smaller detectable concentrations than other existing commercial detection products which have the best limit of detection of 100?ng/mL.     

The crystal structures of three azonaphtharylamide pigments

The single crystal X-ray structures of three structurally related azonaphtharylamide pigments are reported. Two azo pigments derived from 4-amino-3-nitrotoluene as diazo component (1a and b) crystallize in the centrosymmetric space group P2₁/c while the third (1c), an analogue of 1b but derived from 2,5-dichloroaniline as diazo component, crystallizes in the chiral space group P2₁2₁2₁. The compounds adopt the ketohydrazone tautomeric forms with intramolecular, but no intermolecular, hydrogen bonding. The application performance of the products is discussed in relation to the molecular and crystal structures. X-ray powder diffraction, supported by FTIR spectroscopic and DSC analysis, demonstrate that pigment 1a shows polymorphism. The application performances of the two polymorphs of this pigment are compared.     

A PSO-based approach to cell formation problems with alternative process routings

Group technology (GT) has been extensively applied to cellular manufacturing system (CMS) design for decades due to many benefits such as decreased number of part movements among cells and increased machine utilisation in cells. This paper considers cell formation problems with alternative process routings and proposes a discrete particle swarm optimisation (PSO) approach to minimise the number of exceptional parts outside machine cells. The approach contains two main steps: machine partition and part-routing assignment. Through inheritance and random search, the proposed algorithm can effectively partition machines into different cells with consideration of multiple part process routings. The computational results are compared with those obtained by using simulated annealing (SA)-based and tabu search (TS)-based algorithms. Experimental results demonstrate that the proposed algorithm can find equal or fewer exceptional elements than existing algorithms for most of the test problems selected from the literature. Moreover, the proposed algorithm is further tailed to incorporate various production factors in order to extend its applicability. Four sample cases are tested and the results suggest that the algorithm is capable of solving more practical cell formation problems.     

The impact of value diversity on information system development projects

Diversity of personal values among participants in an information system project is typically considered to create harmful team conflict, as do other forms of personal diversity. However, recent research establishes that information and knowledge diversity among project team members contribute to project success, leading one to question accepted thought regarding diversity of values. We model the impact of value diversity on project performance through theoretical layers of diversity, conflict, and teamwork quality. An empirical test supports hypotheses that value diversity adds to both beneficial and detrimental conflict. Project managers should compose teams with diverse project values but must control for potential detrimental effects.     

Reviewing ligand-based rational drug design: the search for an ATP synthase inhibitor

Following major advances in the field of medicinal chemistry, novel drugs can now be designed systematically, instead of relying on old trial and error approaches. Current drug design strategies can be classified as being either ligand- or structure-based depending on the design process. In this paper, by describing the search for an ATP synthase inhibitor, we review two frequently used approaches in ligand-based drug design: The pharmacophore model and the quantitative structure-activity relationship (QSAR) method. Moreover, since ATP synthase ligands are potentially useful drugs in cancer therapy, pharmacophore models were constructed to pave the way for novel inhibitor designs.     

Impacts of Coulomb Interactions on the Magnetic Responses of Excitonic Complexes in Single Semiconductor Nanostructures

We report on the diamagnetic responses of different exciton complexes in single InAs/GaAs self-assembled quantum dots (QDs) and quantum rings (QRs). For QDs, the imbalanced magnetic responses of inter-particle Coulomb interactions play a crucial role in the diamagnetic shifts of excitons (X), biexcitons (XX), and positive trions (X⁻). For negative trions (X⁻) in QDs, anomalous magnetic responses are observed, which cannot be described by the conventional quadratic energy shift with the magnetic field. The anomalous behavior is attributed to the apparent change in the electron wave function extent after photon emission due to the strong Coulomb attraction by the hole in its initial state. In QRs, the diamagnetic responses of X and XX also show different behaviors. Unlike QDs, the diamagnetic shift of XX in QRs is considerably larger than that of X. The inherent structural asymmetry combined with the inter-particle Coulomb interactions makes the wave function distribution of XX very different from that of X in QRs. Our results suggest that the phase coherence of XX in QRs may survive from the wave function localization due to the structural asymmetry or imperfections.     

An immunoassay using antibody-gold nanoparticle conjugate, silver enhancement and flatbed scanner

This study reports a convenient immunoassay using antibody-gold nanoparticle (Ab-AuNP) conjugate as a reporter molecule and a flatbed scanner for the optical scanning and measuring of the immuno-reaction signal. The silver enhancement reaction, a signal amplification method in which silver ions are reduced to silver metal, is introduced to magnify the detection signal. The whole framework of the study is based on (1) the direct immunoassay (two-layer format) in which the antigen is directly immobilized on the chip, and (2) the sandwich immunoassay [three-layer format, process similar to enzyme-linked immunosorbent assay (ELISA)], which contains a primary antibody, a secondary antibody (antibody-nanoparticle conjugate) and antigens. The experimental data show that the micro-scale silver precipitation phenomenon is catalyzed by Ab-AuNP conjugates. This reaction can be observed by the naked eye, even at an IgG-AuNPs concentration of 5 pM. The relationships between sample concentration and detection signal are discussed, and the detection limit (sandwich assay) for the sample antigen is 1 ng/mL. Using a flatbed scanner, Ab-AuNP conjugates and a silver enhancement reaction, a new immunoassay is constructed.     

An optimization approach for joint pricing and ordering problem in an integrated inventory system with order-size dependent trade credit

Under a business trading environment, it is common for the trade credit to depend on the order size. Therefore, it is important to discuss the single-supplier and single-buyer supply chain problem which includes order-size dependent trade credit. In this study, an integrated inventory model with a price sensitive demand rate, determining jointly economic lot size of the buyer’s ordering and the supplier’s production batch, are developed to maximize the total profit per unit time. An efficient algorithm is provided to obtain the optimal solution, and then numerical examples are presented to illustrate the theoretical results. Finally, the comparison between whether an optimal solution is jointly or independently determined is also provided.