Plasma stencilling methods for cell patterning

In this paper we describe plasma stencilling techniques for patterning 10 mammalian cell lines on hydrophobic and cell repellent poly(dimethylsiloxane) (PDMS), methylated glass and bacterial grade polystyrene surfaces. An air plasma produced with a Tesla generator operating at atmospheric pressure was used with microengineered stencils for patterned surface oxidation, selectively transforming the surface to a hydrophilic state to enable cell adhesion and growth. Plasma stencilling obviates the need for directly patterning cell adhesion molecules. Instead, during cell culture, adhesion proteins from the media assemble in a bioactive form on the hydrophilic regions. Critically, the removal of protein patterning prior to cell culture provides the option to also use PDMS–PDMS plasma bonding to incorporate cell patterns within microfluidic systems. Linear patterns were generated using PDMS microchannel stencils, and polyimide stencils with through holes were used for the production of cellular arrays. For the production of smaller cellular arrays, a novel microcapillary-based dielectric barrier discharge system was developed. A numerical method to characterise the cell patterns is also introduced and was used to demonstrate that plasma stencilling is highly effective, with complete patterns confined during long term cell culture (>10 days). In summary, plasma stencilling is simple, rapid, inexpensive, reproducible and a potentially universal cell line patterning capability.

PbMn(SO4)2: A new chiral antiferromagnet

PbMn(SO₄)₂ has been synthesized in an evacuated quartz tube. The nuclear and magnetic crystal structures have been determined using powder X-ray and neutron diffraction. This material crystallizes in the enantiomorphic space group pair P4₁2₁2(92) and P4₃2₁2(96), forming a double-helical arrangement of Pb²⁺ and Mn²⁺ cations. The Mn²⁺O₆ octahedra are distorted. Each 3d⁵ Mn²⁺ has four nearest-neighbors and four next-nearest-neighbors adopting a frustrating arrangement. The compound orders antiferromagnetically at 5.5 K. Field dependent specific heat and magnetization measurements show that T_N is suppressed to 3.3 K when μ₀H=9 T.     

Possibility of predicting separations in supercritical fluid chromatography with the solvation parameter model

In order to obtain a selection of optimal chromatographic columns for the separation of chlorotriazine pesticides in packed column supercritical fluid chromatography (pSFC), a multi-criteria approach is applied. For this purpose, prediction of the separations is carried out, based on quantitative structure–retention relationships, then Derringer's desirability function is proposed to determine the stationary phase that will result in the most desirable separation. The best SFC separation obtained was then optimized using a mobile phase gradient. Besides, the accuracy of the solvation parameter model as SFC retention predictive model is assessed.     

Separation,preconcentration and determination of Pb(Ⅱ) in water samples using microcrystalline triphenylmethane loaded with quinolin-8-olate

This paper described a novel method for the preconcentration of Pb(Ⅱ) using microcrystalline triphenylmethane loaded with quinolin-8-olate prior to the determination by flame atomic absorption spectrometry.Pb(Ⅱ) could be enriched by controlling appropriate condition.The preconcentration factor could reach to 200 and the detection limit of Pb(Ⅱ) was 0.074μg/L.The recovery was in a range of 93.5-103%with relative standard deviation of 1.0-2.2%.The proposed method had been successfully applied to the determ...     

A new monoterpenoid indole alkaloid from Rauvolfia yunnanensis

One new monoterpenoid indole alkaloid, 11-methoxyburnamine-17-O-3′,4′,5′-trimethoxybenzoate (1), was isolated from Rauvolfia yunnanensis Tsiang. Its structure was identified by spectroscopic evidences.     

Study on synthesis and distribution in vivo of 5-Fu-cholic acid conjugate

A series of hepatic targeting drugs,5-Fu-cholic acid conjugate T1-T5,were synthesized.5-Fu and cholic acid was selected as starting material,after N-hydroxymethylation,condensation,hydrogenolysis to obtain carboxylated 5-Fu 5a--e.Carboxylated 5-Fu 5a--e were eondensated with intermediate 3-hydroxyethyl cholic acid benzyl ester 6 to get 7a-e,7a-e were deproteeted to get T1-T5.     

Synthesis of （S） and （R）-tilisolol hydrochloride

Tilisolol hydrochloride 1,a non-selectiveβ-adrenoceptor blocker,was developed as a drug for the treatment of hypertension and angina pectoris.The optical active forms of 1,1a and 1b were synthesized from inexpensive phthalic anhydride 2 in eight steps with 13%(S) and 15%(R) overall yield.     

Cycling,twisting, and sewing in the group theoretic approach to strings

The general theory for cycling transformations in the group theoretic approach to strings is presented. It leads to a simple physical interpretation of the method which is discussed. We also demonstrate that twisting and sewing, i.e. factorization are an inevitable consequence of the method. We show that there exists a particularly simple choice of cycling transformations that leads to very great simplifications in the results for excited string scattering.     

The interval number of a planar graph: Three intervals suffice

Suppose each vertex of a graph G is assigned a subset of the real line consisting of at most t closed intervals. This assignment is called a t-interval representation of G when vertex v is adjacent to vertex w if and only if some interval for v intersects some interval for w. The interval number i(G) of a graph G is the smallest number t such that G has a t-interval representation. It is proved that i(G) ≤ 3 whenever G is planar and that this bound is the best possible. The related concepts of displayed interval number and depth-r interval number are discussed and their maximum values for certain classes of planar graphs are found.     

Mixed alkali effects in Na/Ag β-alumina

Mixed Na/Ag β-aluminas show the characteristic mixed alkali effect. Pronounced minima in conductivity isotherms are accompanied by a corresponding maximum in the activation energy. An entirely new effect is a change in ac response at high frequencies. In the region of the so-called Jonscher dispersion, where σ_ac = Aωⁿ, n falls from about 0.6 in pure Ag and Na β-aluminas to about 0.2 near the conductivity minimum. It is suggested that this reflects the disappearance of collective many-body interactions among the mobile cations.