Effects of static magnetic field on growth of leptospire, Leptospira interrogans serovar canicola: immunoreactivity and cell division

The effects of the exposure of the bacterium, Leptospira interrogans serovar canicola to a constant magnetic field with magnetic flux density from a permanent ferrite magnet=140+/-5 mT were studied. Changes in Leptospira cells after their exposure to the field were determined on the basis of changes in their growth behavior and agglutination immunoreactivity with a homologous antiserum using dark-field microscopy together with visual imaging. The data showed that the exposed Leptospira cells have lower densities and lower agglutination immunoreactivity than the unexposed control group. Interestingly, some of the exposed Leptospira cells showed abnormal morphologies such as large lengths. We discussed some of the possible reasons for these observations.     

Low temperature solution-phase growth of ZnSe and ZnSe/CdSe core/shell nanowires

High quality ZnSe nanowires (NWs) and complementary ZnSe/CdSe core/shell species have been synthesized using a recently developed solution-liquid-solid (SLS) growth technique. In particular, bismuth salts as opposed to pre-synthesized Bi or Au/Bi nanoparticles have been used to grow NWs at low temperatures in solution. Resulting wires are characterized using transmission electron microscopy and possess mean ensemble diameters between 15 and 28 nm with accompanying lengths ranging from 4-10 μm. Subsequent solution-based overcoating chemistry results in ZnSe wires covered with CdSe nanocrystals. By varying the shell's growth time, different thicknesses can be obtained and range from 8 to 21 nm. More interestingly, the mean constituent CdSe nanocrystal diameter can be varied and results in size-dependent shell emission spectra.     

Effect of composition on the stability of liposomal irinotecan prepared by a pH gradient method

Liposomal irinotecan was prepared by pH gradient loading. The parameters that govern this process, including drug loading time, incubation temperature, buffer composition for hydration, and deltapH, were studied. The uptake of irinotecan into liposomal systems in response to the magnitude of the pH gradient was examined. The drug uptake was maximum when the magnitude of deltapH approached 3.7. The effect of the formulation of the liposomes on the stability of the drug delivery system was also studied. Liposomes composed of lipids with a high phase transition temperature, L-alpha-distearoyl-phosphatidyl-choline and hydrogenated soy phosphatidylcholine, were more stable than those composed of lipids with lower phase transition temperatures. Incorporating distearoyl phosphatidylethanolamine-poly (ethylene glycol)2000 into liposomes helped to reduce the size of the liposomes. In addition, the retention of a drug within liposomes was found to be slightly enhanced by including dimyristoylphosphatidylglycerol or dextran sulfate in the liposome formulation.     

Stem cell bioprocessing: fundamentals and principles

In recent years, the potential of stem cell research for tissue engineering-based therapies and regenerative medicine clinical applications has become well established. In 2006, Chung pioneered the first entire organ transplant using adult stem cells and a scaffold for clinical evaluation. With this a new milestone was achieved, with seven patients with myelomeningocele receiving stem cell-derived bladder transplants resulting in substantial improvements in their quality of life. While a bladder is a relatively simple organ, the breakthrough highlights the incredible benefits that can be gained from the cross-disciplinary nature of tissue engineering and regenerative medicine (TERM) that encompasses stem cell research and stem cell bioprocessing. Unquestionably, the development of bioprocess technologies for the transfer of the current laboratory-based practice of stem cell tissue culture to the clinic as therapeutics necessitates the application of engineering principles and practices to achieve control, reproducibility, automation, validation and safety of the process and the product. The successful translation will require contributions from fundamental research (from developmental biology to the ‘omics’ technologies and advances in immunology) and from existing industrial practice (biologics), especially on automation, quality assurance and regulation. The timely development, integration and execution of various components will be critical—failures of the past (such as in the commercialization of skin equivalents) on marketing, pricing, production and advertising should not be repeated. This review aims to address the principles required for successful stem cell bioprocessing so that they can be applied deftly to clinical applications.     

Workspace analysis of fully restrained cable-driven manipulators

For Cable-Driven Parallel Manipulators (CDPMs), employing redundant driving cables is necessary to obtain the full manipulation of the moving platform because of the unilateral driving property of the cables. Unlike rigid-link manipulators, the workspace of CDPMs is always determined and characterized by positive tension status of driving cables. In addition, it has been realized that the Tension Factor (TF) reflecting the relative tension distribution among the driving cables is an appropriate measure to evaluate the quality of tension restraint for CDPMs. However, since redundant cables are employed to drive the moving platform, the TF values are not unique for a particular moving platform pose. Therefore, how to determine the workspace and obtain the optimal TF value so as to generate a workspace with optimized performance become the major subjects of this paper. It is shown that the workspace can be generally formed from tension conditions verified by a recursive dimension-reduction approach and that the optimal TF value at every pose can be efficiently determined through a linear optimization approach, although it is essentially a nonlinear optimization problem. Computational examples are provided to demonstrate the effectiveness of the proposed algorithms.     

Effects of exogenous glycosaminoglycans on human chondrocytes cultivated on type II collagen scaffolds

Cartilage extracellular matrix (ECM) is composed primarily of type II collagen (COL II) and large, networks of proteoglycans (PGs) that contain glycosaminoglycans such as hyaluronic acid (HA) and chondroitin sulfate (CS). Since cartilage shows little tendency for self-repair, injuries are kept unhealed for years and can eventually lead to further degeneration. During the past decades, many investigations have pursued techniques to stimulate articular cartilage repair or regeneration. The current study assessed the effects of exogenous glycosaminoglycans (GAGs) including CS-A, CS-B, CS-C, heparan sulfate and HA, administration on human chondrocytes in terms of proliferation and matrix synthesis, while the cells were seeded and grown on the genipin-crosslinked collagen type II (COL II) scaffold. DNA content was measured by Hoechst dye intercalation, matrix deposition was evaluated by DMMB dye. Expression of collagen II and aggrecan mRNAs was assessed by RT-PCR, followed by gel electrophoresis. In a 28-day in vitro culture, administration of 5 μg/ml CS-A, 50 μg/ml CS-B, 50 μg/ml CS-C, 5 μg/ml HS, and 500 kDa HA led to significant increase in biosynthesis rate of PGs. Gene expression of aggrecan and collagen II were upregulated by CS-A, CS-C and HA. These results showed considerable relevance of GAGs to the issue of in vitro/ex vivo neo-cartilage synthesis for tissue engineering and regenerative medical applications.     

Miniaturized flow fractionation device assisted by a pulsed electric field for nanoparticle separation

Electric field flow fractionation (EFFF) is a powerful separation technique based on an electrical field perpendicular to a pressure-driven flow. Previous studies of microelectric field flow fractionation (micro-EFFF) indicate that separation performance was limited due to a weak effective electric field caused by polarization layers on the electrode surfaces. In this work, we report on a micro-EFFF device that uses a pulsed voltage scheme to overcome these limitations. The device was fabricated in indium tin oxide (ITO)-coated glass with ITO as electrodes. The effective electric field for pulsed voltage operation was found to be 50-fold stronger when compared with constant voltage operation. A strong influence of pulsed voltage frequency on nanoparticle retention times was observed. Using pulsed voltage, improved separation of polystyrene particles of different surface charge and particle size is demonstrated. Pulsed voltage also offers more parameters compared to the constant voltage mode, e.g., pulse frequency, duty cycle, and waveform to optimize the retention behavior of analytes.     

Sequence-specific electrochemical detection of asymmetric PCR amplicons of traditional Chinese medicinal plant DNA

In this study, an electrochemistry-based approach to detect nucleic acid amplification products of Chinese herbal genes is reported. Using asymmetric polymerase chain reaction and electrochemical techniques, single-stranded target amplicons are produced from trace amounts of DNA sample and sequence-specific electrochemical detection based on the direct hybridization of the crude amplicon mix and immobilized DNA probe can be achieved. Electrochemically active intercalator Hoechst 33258 is bound to the double-stranded duplex formed by the target amplicon hybridized with the 5'-thiol-derivated DNA probe (16-mer) on the gold electrode surface. The electrochemical current signal of the hybridization event is measured by linear sweep voltammetry, the response of which can be used to differentiate the sequence complementarities of the target amplicons. To improve the reproducibility and sensitivity of the current signal, issues such as electrode surface cleaning, probe immobilization, and target hybridization are addressed. Factors affecting hybridization efficiency including the length and binding region of the target amplicon are discussed. Using our approach, differentiation of Chinese herbal species Fritillaria (F. thunbergii and F. cirrhosa) based on the 16-mer unique sequences in the spacer region of the 5S-rRNA is demonstrated. The ability to detect PCR products using a nonoptical electrochemical detection technique is an important step toward the realization of portable biomicrodevices for on-spot bacterial and viral detections.     

Quantum Circuit Design and Analysis for Database Search Applications

In this paper, we show how quantum Boolean circuits can be used to implement the oracle and the inversion-about-average function in Grover's search algorithm. Before illustrating how this can be done, we present the circuit design principle using the satisfiability (SAT) problem as an example. Then, based on this principle, we show the quantum circuits for two different kinds of applications. The first one is searching a phone book. Although this is a typical example of Grover's algorithm, we show that it is impractical as a real-world application. As the second application, we give the quantum circuits for a more practical application-breaking a symmetric cryptosystem. Although these two applications have quite different types of search criteria, they are both one-way functions and the proposed circuits can actually be generalized to any such problems. In this perspective, we conclude this paper by proposing a template of quantum circuits that is capable of searching the solution of a certain class of one-way functions.     

Synthesis and characterization of highly ordered mesoporous YSZ by tri-block copolymer

A highly ordered mesoporous yttria-stabilized zirconia (YSZ) has been successfully prepared by evaporation-induced self-assembly method (EISA) using tri-block copolymer Pluronic F127 as a structure-directing agent and inorganic chlorides as precursors in a non-aqueous medium. The characterization of the mesoporous YSZ materials was carried out by using small angle X-ray diffraction (SAXRD), transmission electron microscopy (TEM) and N₂ adsorption/desorption. The well ordered mesoporous YSZ is thermally stable up to 600^∘C with an average pore size of 5.4 nm and specific surface area of 90 m²/g. The walls of mesoporous YSZ are composed of ∼6.5 nm nano-crystalline domains.