Parallelizing Nonlinear Least-Squares Regression with Application to Analyses of Microalgae

Nonlinear least-squares regression is a valuable tool for gaining chemical insights into complex systems. Yet, the success of nonlinear regression as measured by residual sum of squares (RSS), correlation, and reproducibility of fit parameters strongly depends on the availability of a good initial solution. Without such, iterative algorithms quickly become trapped in an unfavorable local RSS-minimum. For determining an initial solution, a high-dimensional parameter space needs to be screened, a process that is very time-consuming but can be parallelized. Another advantage of parallelization is equally important: After determining initial solutions, the used processors can be tasked to each optimize an initial guess. Even if several of these optimizations become stuck in a shallow local RSS-minimum, other processors continue and improve the regression outcome. A software package for parallel processing-based constrained nonlinear regression (RegressionLab) has been developed, implemented, and tested on a variety of hardware configurations. As proof-of-principle, microalgae to environment interactions have been studied by infrared attenuated total reflection spectroscopy. Additionally, light microscopy has been used to monitor cell production. It is shown that spectroscopic data sets with 10,000?s of data points and >1000 nonlinear model parameters as well as imaging data with 100,000s of data points and >2000 nonlinear model parameters may now be investigated by constrained nonlinear regression. Acceleration factors of up to 8.1 have been obtained which is of high practical relevance when computations take weeks on single-processor machines. Solely using parallel processing, the RSS values may be improved up to a factor of 5.5.     

Evaluation of a Gelatin-Modified Poly(ε-Caprolactone) Film as a Scaffold for Lung Disease

Lung transplantation is a necessary step for the patients with the end stage of chronic obstructive pulmonary disease. The use of artificial lungs is a promising alternative to natural lung transplantation which is complicated and is restricted by low organ donations. For successful lung engineering, it is important to choose the correct combination of specific biological cells and a synthetic carrier polymer. The focus of this study was to investigate the interactions of human lung epithelial cell line NCl-H292 that is involved in lung tissue development with the biodegradable poly(ε-caprolactone) before and after its chemical modification to evaluate potential for use in artificial lung formation. Also, the effect of polymer chemical modification on its mechanical and surface properties has been investigated. The poly(ε-caprolactone) surface was modified using aminolysis followed by immobilization of gelatin. The unmodified and modified polymer surfaces were characterized for roughness, tensile strength, and NCl-H292 metabolic cell activity. The results showed for the first time the possibility for NCI-H292 cells to adhere on this polymeric material. The resazurin assay showed that the metabolic activity at 24?h postseeding of 80% in the presence of the unmodified and greater than 100% in the presence of the modified polymer was observed. The roughness of the poly(ε-caprolactone) increased from 4 to 26?nm and the film strength increased from 0.01 to 0.045 kN when the material was chemically modified. The results obtained to date show potential for using modified poly(ε-caprolactone) as a scaffold for lung tissue engineering.     

Synthesis of the western half of breviones C, D, F and G

The enantioselective synthesis of the diterpenic moiety in the abeo-breviano skeleton is reported. The synthesis is carried out starting from 2-methyl-1,3-cyclohexanedione and EVK in eleven steps following a ring-expansion strategy once the tricyclic perhydrophenantrene skeleton has been obtained. A new Tiffeneau-Demjanov rearrangement under dark conditions is reported in which the insertion of the new methylene group is directed towards the most hindered side of the carbonyl group. This result is new and opposite to those reported in the literature under light (filtered or un-filtered wavelengths) conditions where insertion in the less hindered side is usually preferred.     

A Novel and Efficient One‐Pot Synthesis of 2‐Aminopyrimidinones and Their Self‐Assembly

A three‐component reaction of benzaldehyde derivatives, methyl cyanoacetate, and guanidinium carbonate affords 2‐amino‐4‐aryl‐1,6‐dihydro‐6‐oxopyrimidine‐5‐carbonitriles and the four‐component reaction of benzaldehyde derivatives, methyl cyanoacetate, and guanidinium hydrochloride in the presence of piperidine leads to piperidinium salts of pyrimidinones. X‐ray crystallography data confirm self‐assembly and H‐bonding in these compounds.     

Novel methods to functionalize thiazolo[4,5-c]pyridines

Novel substituted thiazole[4,5-c]pyridines have been synthesized in good yields from unsubstituted thiazole[4,5-c]pyridine using direct C-H coupling reactions and N-oxide rearrangement chemistry.     

Ultrathin Carbon Film Electrodes from Vacuum‐Carbonised Cellulose Nanofibril Composite

A novel way to produce ultrathin transparent carbon layers on tin‐doped indium oxide (ITO) substrates is developed. The ITO surface is coated with cellulose nanofibrils (from sisal) via layer‐by‐layer electrostatic binding with poly(diallyldimethylammonium chloride) or PDDAC acting as the binder. The cellulose nanofibril‐PDDAC composite film is then vacuum‐carbonised at 500 °C. The resulting carbon films are characterised by atomic force microscopy (AFM), small angle X‐ray scattering (SAXS), wide‐angle X‐ray scattering (WAXS), and Raman methods. Smooth carbon films with good adhesion to the ITO substrate are formed. The electrochemical characterisation of the carbon films is based on the oxidation of hydroquinone and the reduction of benzoquinone in aqueous phosphate buffer media. A modest effect of the cellulose nanofibril‐PDDAC film on the rate of electron transfer is observed. The effect of the film on the rate of electron transfer after carbonisation is more dramatic. For a 40‐layer cellulose nanofibril‐PDDAC film after carbonisation a two‐order of magnitude change in the rate of electron transfer occurs presumably due to a better interaction of the hydroquinone/benzoquinone system with the electrode surface.     

Sensitive Determination of Water Insoluble Dyes Used as Marking of Commercial Petroleum Products Using High‐Performance Liquid Chromatography with Electrochemical Detection

This paper describes an analytical method using high‐performance liquid chromatographic (HPLC) separation coupled with electrochemical detection to detect three dyes, Solvent Blue 14 (SB‐14), Solvent Blue 35 (SB‐35) and Solvent Red 24 (SR‐24). The dyes were eluted and separated using a reversed‐phase column (C‐8) under isocratic elution with the mobile phase containing a mixture of acetonitrile/ammonium acetate (5.0 mmol L^?1) at the ratio of 75 : 25 (v/v). Two sample pretreatment methods were tested and successfully applied to quantify SB14, SB‐35 and SR‐24 dyes in gasoline samples. The proposed method was simple, fast and suitable to detect and quantify marker dyes in gasoline sample at low concentration.     

Ketene functionalized polyethylene: control of cross-link density and material properties

The functionalization and cross-linking of polyethylene is synthetically challenging, commonly relying on highly optimized radical based postpolymerization strategies. To address these difficulties, a norbornene monomer containing Meldrum's acid is shown to be effectively copolymerized with polyethylene using a nickel α-iminocarbaxamidato complex, providing high-melting, semicrystalline polymers with a tunable incorporation of the functional comonomer. Upon heating the copolymer to common polyethylene processing temperatures, the thermolysis of Meldrum's acid to ketene provides the desired reactive group. This simple and versatile methodology does not require small molecule radical sources or catalysts, and the dimerization of the in situ generated ketenes is shown to provide tunable cross-linking densities in polyethylene. Subsequent rheological and tensile experiments illustrate the ability to tune cross-linked polyethylene properties by comonomer incorporation and elucidate valuable structure/property relationships in these materials. This study illustrates the power of well-defined and synthetically accessible functional groups in polyolefin synthesis and functionalization.     

Targeting of cancer cells using click-functionalized polymer capsules

Targeted delivery of drugs to specific cells allows a high therapeutic dose to be delivered to the target site with minimal harmful side effects. Combining targeting molecules with nanoengineered drug carriers, such as polymer capsules, micelles and polymersomes, has significant potential to improve the therapeutic delivery and index of a range of drugs. We present a general approach for functionalization of low-fouling, nanoengineered polymer capsules with antibodies using click chemistry. We demonstrate that antibody (Ab)-functionalized capsules specifically bind to colorectal cancer cells even when the target cells constitute less than 0.1% of the total cell population. This precise targeting offers promise for drug delivery applications.     

The Ternary System Nickel/Silicon/Titanium Revisited

The constitution of the ternary system Ni/Si/Ti is investigated over the entire composition range using X‐ray diffraction (XRD), energy dispersive X‐ray spectroscopy (EDS), differential thermal analysis (DTA), and metallography. The solid state phase equilibria are determined for 900 °C. Eight ternary phases are found to be stable. The crystal structures for the phases τ₁NiSiTi, τ₂Ni₄Si₇Ti₄, τ₃Ni₄₀Si₃₁Ti₁₃, τ₄Ni₁₇Si₇Ti₆, and τ₅Ni₃SiTi₂ are corroborated. For the remaining phases the compositions are determined as Ni₆Si₄₁Ti₅₃ (τ₆), Ni₁₆Si₄₂Ti₄₂(τ₇), and Ni₁₂Si₄₅Ti₄₃ (τ₈). The reaction scheme linking the solid state equilibria with the liquidus surface is amended to account for these newly observed phases. The discrepancies between previous experimental conclusions and modeling results are addressed. The liquidus surface is dominated by the primary crystallisation field of τ₁NiSiTi, the only congruently melting phase.