Bounds on the number of Hadamard designs of even order

A new lower bound on the number of non‐isomorphic Hadamard symmetric designs of even order is proved. The new bound improves the bound on the number of Hadamard designs of order 2n given in [12] by a factor of 8n ? 1 for every odd n > 1, and for every even n such that 4n ? 1 > 7 is a prime. For orders 8, 10, and 12, the number of non‐isomorphic Hadamard designs is shown to be at least 22,478,260, 1.31 × 10¹⁵, and 10²⁷, respectively. For orders 2n = 14, 16, 18 and 20, a lower bound of (4n ? 1)! is proved. It is conjectured that (4n ? 1)! is a lower bound for all orders 2n ≥ 14. © 2001 John Wiley & Sons, Inc. J Combin Designs 9: 363‐378, 2001     

Synthesis and characterization of physically crosslinked N‐vinylcaprolactam,acrylic acid,methacrylic acid,and N,N‐dimethylacrylamide hydrogels

Physically crosslinked hydrogels based on N‐vinylcaprolactam/acrylic acid and N‐vinylcaprolactam/methacrylic acid were prepared via free radical polymerization. These temperature responsive hydrogels were characterized in terms of glass transition, phase separation temperature, potentiometric titration and swelling properties. Results showed that phase transition temperature was dependent on the pH value of the solution; increasing pH led to higher lower critical solution temperature (LCST) values which was related to the dissociative behaviors of the carboxylic group of MAc in the buffered solutions. Additionally, with the incorporation of N,N‐dimethylacrylamide into the system, cloud point measurements and MDSC showed an increased in the LCST. This increase was based on hydrophilicity, the hydrophilic–hydrophobic balance was disturbed, and consequently, the LCST behavior was shifted. The pKa of the copolymers ranged between 5.6 and 6.5, while for the terpolymers pKa ranged between 5.3 and 6. At high pH (>10), the ? COOH group is deprotonated and negatively charged (? COO^?), while at low pH (1–3) the carboxylic group remains protonated which results in hydrogen bonding between the hydroxyl groups (from NaOH) and the excess of HCl. These results correlate with swelling studies where above the pKa value the hydrogels dissolved rapidly compared to below pKa they did not dissolve at all. © 2013 Wiley Periodicals, Inc. J. Polym. Sci., Part B: Polym. Phys. 2013 , 51, 1555–1564     

Plasma-enhanced atomic layer deposition of Co using Co（MeCp）2 precursor

Cobalt（Co） thermal or plasma enhanced atomic layer deposition（PE-ALD） was investigated using a novel metal organic precursor,Co（MeCp）₂, and NH₃ or H₂ or their plasma as a reactant.The growth characteristics,electrical and microstructural properties were investigated.Especially, PE-ALD produced Co thin films at low growth temperature down to 100℃.Interestingly,the low temperature growth of Co films showed the formation of columnar structure at substrate temperature below 300℃.The growth characteristics and films properties of PE-ALD Co using bis（η-methylcyclopentadienyl） Co（Ⅱ）（Co（MeCp）₂） was compared with those of PE-ALD Co using other Cp based metal organic precursors, bis-cyclopentadienyl cobalt（II）（CoCP₂） and cyclopentadienyl isopropyl acetarrudinato-cobalt（Co（CpAMD））.     

DNA G-quadruplex and its potential as anticancer drug target

G-quadruplex secondary structures are four-stranded globular nucleic acid structures form in the specific DNA and RNA G-rich sequences with biological significance such as human telomeres,oncogene-promoter regions,replication initiation sites,and 5′and 3′-untranslated(UTR)regions.The non-canonical G-quadruplex secondary structures can readily form under physiologically relevant ionic conditions and are considered to be new molecular target for cancer therapeutics.This review discusses the essential progress in our lab related to the structures and functions of biologically relevant DNA G-quadruplexes in human gene promoters and telomeres,and the opportunities presented for the development of G-quadruplex-targeted smallmolecule drugs.     

Averaging in SU(2) open quantum random walk

We study the average position and the symmetry of the distribution in the SU（2） open quantum random walk （OQRW）. We show that the average position in the central limit theorem （CLT） is non-uniform compared with the average position in the non-CLT. The symmetry of distribution is shown to be even in the CLT.     

The BOSCO solar cell – a both sides collecting and contacted structure

The BOSCO solar cell represents a bifacial structure with double‐sided collection. The structure allows the use of standard module interconnection technology and favours the use of material with low to medium diffusion length and low resistivity for maximum benefit towards other structures, such as Al‐BSF and PERC. Within this work, we present first results on different multicrystalline silicon materials yielding a monofacial efficiency of 17.4% on large‐area wafers from block‐cast mc‐Si. This value represents a gain of ～0.7%_abs compared to Al‐BSF cells processed in parallel. The applicability for bifacial operation is demonstrated by a significantly increased quantum efficiency for rear side illumination. These results make the BOSCO solar cell concept a promising candidate to further boost the output of utility‐scale PV plants even when using low‐cost wafers of low to medium diffusion length material.

     

Mechanical and biodegradation performance of short natural fibre polyhydroxybutyrate composites

The work outlined in this paper describes the evaluation of polyhydroxybutyrate (PHB) based natural fibre composites via an extrusion – injection moulding process. Virgin PHB was compounded with two different naturally occuring plant fibres, hemp and jute, and a third, regenerated cellulose fibre, lyocell. Composite materials containing 10–30 wt% of each type of fibre were obtained by twin screw extrusion and the resultant material was injection moulded to produce tensile samples suitable for mechanical characterisation. Mechanical properties were determined using tensile, impact and flexural testing. Melt flow index and water absorption studies were also carried out on the biocomposite materials, and Fourier transform infrared spectroscopy was used to examine the bonding between the polymer and each fibre type. The rate of biodegradation was also observed by placing composite samples in compost and measuring weight loss weekly. The biocomposites produced using this method were shown to have increased rates of biodegradation whilst exhibiting significantly improved flexural properties.     

Pt||ZrO2 nanoelectrode array synthesized through the sol–gel process: evaluation of their sensing capability

Homogeneous, circular Pt||ZrO₂ nanoelectrodes have been synthesized through the sol–gel chemistry and the dip-coating process. These nanoelectrode arrays have been evaluated as a platform for electropolymerization of phenol, as model. We have shown that the microstructure of the polymer depends on the confined environment of the electrode and on the position of the –OH group of the monomer. Additionally, these nanoelectrodes have been tested as an electrochemical sensor for dihydroxybenzene isomers in aqueous medium. These Pt||ZrO ₂ nanoelectrodes exhibit a detection limit of 2?×?10^?7?M for resorcinol and 1?×?10^?6?M for catechol.     

Quartz microfluidic chip for tumour cell identification by Raman spectroscopy in combination with optical traps

Three important technical innovations are reported here towards Raman-activated cell sorting. Firstly, a microfluidic chip made of quartz is introduced which integrates injection of single cells, trapping by laser fibres and sorting of cells. Secondly, a chip holder was designed to provide simple, accurate and stable adjustment of chips, microfluidic connections and the trapping laser fibres. The new setup enables to the collection of Raman spectra of single cells at 785 nm excitation with 10 s exposure time. Lastly, a new type of modelling the various background contributions is described, improving Raman-based cell identification by the classification algorithm linear discriminant analysis. Mean sensitivity and specificity determined by iterated 10-fold cross validation were 96 and 99 %, respectively, for the distinction of leucocytes extracted from blood, breast cancer cells BT-20 and MCF-7, and leukaemia cells OCI-AML3.