Chain Units Research Articles

Best Practice Sharing for Complexity Management in Supply Chains of the Semiconductor Industry

Global supply chain becomes complex because of a fast increasing number of dynamic interactions which need to be handled. The semiconductor industry is characterized by long product life cycles, highly differentiated products, and non-linearity in the manufacturing process; furthermore the semiconductor companies also face a volatile market due to the upstream position in the supply chain of consumer electronics which makes the demand from end-customers hard to forecast.The purpose of this paper is to analyze the key drivers of supply chain complexity in the semiconductor industry from practical view and to find the common ground between them. Several prevalent problems address different aspects of supply chain complexity occurred in daily operations were collected from an international semiconductor company, and discussed at an internal workshop with around forty participants from supply chain, IT or other business units. For each case the main drivers of complexity were mapped from reality to a conceptual model. Possible solutions to manage complexity were brainstormed and structured finally. By gathering all discussion results, these findings can be summarized:1)Different complexity problems might have the same solution2)Human roles, common understanding and communication become very important in complexity management3)Trends for complexity management strategies: for current complexity, manage the value-added complexity which is necessary and reduce non-value added complexity; avoid future non-value added complexityThese empirical results also provide evidence for our hypothesis, that complexity can be viewed from these aspects: process, role, object (state) and analyzed by their individual attributes which have influences on the system. This PROS approach defines a conceptual model to describe a complex system from the theoretical perspective. People get further indications that PROS model is a useful tool to analyze complexity and it can help to separate value added from non-value added complexity.

A 2.5 pJ/b Binary Image Sensor as a Pathfinder for Quanta Image Sensors

This paper presents a pathfinder binary image sensor for exploring low-power dissipation needed for future implementation of gigajot single-bit quanta image sensor (QIS) devices. Using a charge-transfer amplifier design in the readout signal chain and pseudostatic clock gating units for row and column addressing, the 1-Mpixel binary image sensor operating at 1000 frames/s dissipates only 20-mW total power consumption, including I/O pads. The gain and analog-to-digital converter stages together dissipate 2.5 pJ/b, successfully paving the way for future gigajot QIS sensor designs.

Cobalt coordination polymers regulated by in situ ligand transformation

A series of cobalt(II) coordination polymers {[Co(L1)2(H2O)2]·4H2O·2DMF}n (1; HL1 = 4-(3,5-(dicyano-2,6-dipyridyl)dihydropyridyl)benzoic acid; DMF = N,N-dimethylformamide), {[Co(L1a)2(H2O)2]·2H2O}n (2, HL1a = 4-(3,5-dicyano-terpyridyl)benzoic acid), and [Co3(μ3-OH)2(L1a)2(TP)(H2O)2]n (3, TPA = terephthalic acid) are reported, in which the conformation of the primary ligand L1− has been regulated by in situ oxidative dehydrogenation into L1a− in different solvent systems. Single crystal structural analyses reveal that compound 1 exhibits a 44-sql coordination layer structure constructed from cobalt centres and parent L1− ligands; compound 2 is constructed from Co2+ cations doubly connected by L1a− anions, which are generated in situ through oxidative dehydrogenation of L1−; while compound 3 features a rod-packing 3D network with a pcu-type topology, in which cobalt–oxygen chain units are interconnected by L1a− and TP2− mixed ligands. The formation mechanism of L1a− ligand via an in situ oxidative dehydrogenation reaction has been briefly discussed. This current study confirms that in situ ligand transformation is viable for controlled coordination polymer assembly, and is also adaptable to a more complexed ligand system.

Structure of Self-Assembled Mn Atom Chains on Si(001).

Mn has been found to self-assemble into atomic chains running perpendicular to the surface dimer reconstruction on Si(001). They differ from other atomic chains by a striking asymmetric appearance in filled state scanning tunneling microscopy (STM) images. This has prompted complicated structural models involving up to three Mn atoms per chain unit. Combining STM, atomic force microscopy, and density functional theory we find that a simple necklacelike chain of single Mn atoms reproduces all their prominent features, including their asymmetry not captured by current models. The upshot is a remarkably simpler structure for modeling the electronic and magnetic properties of Mn atom chains on Si(001).

P2O5–MsOH-mediated Facile Synthesis of Semi-aromatic Polyketones Bearing 1,4-Cyclohexanediyl Units

Abstract Direct polycondensation of trans-1,4-cyclohexanedicarboxylic acid with several electron-rich arenes in a P2O5–CH3SO3H (MsOH) mixture gave semi-aromatic polyketones bearing 1,4-cyclohexanediyl units in the main chains. The resulting polyketones have sufficiently high thermal stability and excellent transparency.

New triterpenoid saponins with cytotoxic and anti-inflammatory properties from Weigela stelzneri.

Saponins are bioactive compounds occurring in many plant species having a wide range of biological activities such as immunoadjuvant, cytotoxic, analgesic, antimicrobial and anti-inflammatory activities, just to mention a few. The aim of our researches concerns the isolation, structural elucidation and biological investigation of saponins from various plant species [1]. In this context, the study of the roots and leaves of Weigela stelzneri (Caprifoliaceae) led to isolation of four new and two known oleanane-type saponins mainly by medium pressure- and vacuum-liquid chromatography on silica gel (normal and reversed-phase RP-18) [1]. The new compounds were elucidated by a combination of spectroscopic techniques including 1D-, 2D-NMR, and mass spectrometry as glycosides of oleanolic acid, three of them being monodesmosides at C-3 with a branched oligosaccharidic chain made of six sugar units, whereas the known ones were hederagenin derivatives. The six compounds were evaluated for their cytotoxicity against a human cancer cell line (colorectal SW480) and a mouse cancer cell line (mammary EMT6), and for their anti-inflammatory activity. The results show that two new compounds differing only by the first sugar unit of the hexasaccharidic chain at C-3 (arabinopyranosyl instead of xylopyranosyl) exhibited the strongest cytotoxicity on both cell lines (IC50 5.41 µM and 1.54 µM, respectively), which was better than those of the positive controls etoposide and methotrexate. Furthermore, they revealed a significant modulatory effect of the IL-1β production on human lymphocytes stimulated with endotoxins, showing therefore a strong anti-inflammatory potential.

Hyperbranched polyester copolymers for thermal printing papers: The effects of alkyl chain units in the polymer backbone on developing capability

The demand for a safer alternative to bisphenol A (BPA) developer materials for thermal printing systems has recently grown considerably because of the many potential health effects of exposure to BPA. In this study, we tested the use of hyperbranched polymers as replacements for BPA, and determined the structural features of their polymer backbones that control the developing capability of thermal papers. For this purpose, a novel series of hyperbranched polyester copolymers with linear and terminal phenol groups were prepared via one-pot A2 + B3 reactions of phloroglucinol with various feed ratios of terephthaloyl chloride and adipoyl chloride. The variations with the proportion of alkyl chains in the backbones of the structural, thermal, and color-forming reaction properties of the resultant polymers were investigated. Moreover, the preparation of thermal papers with these polymers was carried out and their developing capabilities were compared to those of BPA–based thermal papers.

Assembly of sandwich-type 3-D supramolecular coordination polymers based on hexa-molybdenum chain and {PMo12O40} heteropolyanion

A {PMo12O40}-directed organic–inorganic hybrid compound H3O[Mo6(bpy)6O17][PMo12O40]·2H2O (1) (bpy=2,2′-bipyridine) has been hydrothermally synthesized and characterized by the elemental analysis, IR, XRD, TG analysis and single-crystal X-ray diffraction. In compound 1, Keggin heteropolyanions as templates induce the [MoO4(bpy)] complexes to form unusual wave-liked hexa-molybdenum unit's chains, which are further linked to form pure Mo-oxide-based host layers via supramolecular interaction. {PMo12} as guest units is grafted on the host layer to result in Keggin ions layers. The host cation layers and Keggin ions layers alternately array together to form unique sandwich-type supramolecular networks. In addition, the solid state fluorescent properties, and electro- and photo-catalytic behaviors of compound 1 have been studied.

TMalphaDB and TMbetaDB: web servers to study the structural role of sequence motifs in α-helix and β-barrel domains of membrane proteins.

BackgroundMembrane proteins represent over 25 % of human protein genes and account for more than 60 % of drug targets due to their accessibility from the extracellular environment. The increasing number of available crystal structures of these proteins in the Protein Data Bank permits an initial estimation of their structural properties.DescriptionWe have developed two web servers—TMalphaDB for α-helix bundles and TMbetaDB for β-barrels—to analyse the growing repertoire of available crystal structures of membrane proteins. TMalphaDB and TMbetaDB permit to search for these specific sequence motifs in a non-redundant structure database of transmembrane segments and quantify structural parameters such as ϕ and ψ backbone dihedral angles, χ1 side chain torsion angle, unit bend and unit twist.ConclusionsThe structural information offered by TMalphaDB and TMbetaDB permits to quantify structural distortions induced by specific sequence motifs, and to elucidate their role in the 3D structure. This specific structural information has direct implications in homology modeling of the growing sequences of membrane proteins lacking experimental structure. TMalphaDB and TMbetaDB are freely available at http://lmc.uab.cat/TMalphaDB and http://lmc.uab.cat/TMbetaDB.

Lithium-Salt-Containing High-Molecular-Weight Polystyrene-block-Polyethylene Oxide Block Copolymer Films.

Ionic conductivity in relation to the morphology of lithium-doped high-molecular-weight polystyrene-block-polyethylene oxide (PS-b-PEO) diblock copolymer films was investigated as solid-state membranes for lithium-ion batteries. The tendency of the polyethylene (PEO) block to crystallize was highly suppressed by increasing both the salt-doping level and the temperature. The PEO crystallites completely vanished at a salt-doping ratio of Li/EO>0.08, at which the PEO segments were hindered from entering the crystalline unit of the PEO chain. A kinetically trapped lamella morphology of PS-b-PEO was observed, due to PEO crystallization. The increase in the lamella spacing with increasing salt concentration was attributed to the conformation of the PEO chain rather than the volume contribution of the salt or the previously reported increase in the effective interaction parameter. Upon loading the salt, the PEO chains changed from a compact/highly folded conformation to an amorphous/expanded-like conformation. The ionic conductivity was enhanced by amorphization of PEO and thereby the mobility of the PEO blocks increased upon increasing the salt-doping level.

Solid State Structure of Poly(9,9-dinonylfluorene)

We report on X-ray diffraction and grazing-incidence X-ray diffraction data of poly(9,9-dinonylfluorene) (PF9) in bulk, thin films and in the 1% methylcyclohexane gel. We denote the main crystalline phase as α phase and propose that the unit cell is monoclinic (a = 29.31 Å, b = 23.65 Å, c = 33.33 Å, and γ = 84.70°) in bulk and orthorhombic (a = 28.70 Å, b = 23.48 Å, and c = 33.23 Å) in thin films. This structure corresponds to the layered structure along the a-axis (along the elongated side chains and perpendicular to the seemingly stiff polymer chains) and to the stacking of aromatic main chain units along the b-axis. The polymer chains are aligned along the c-axis. Monoclinic structure agrees with the layer spacing of 14.6 Å, the stacking period d(040) = 5.89 Å and the monomer repeat distance of 8.33 Å. The α phase experiences an order–disorder transition at 170 °C upon heating. In the 1% methylcyclohexane gel, this structural motif is maintained but with the loss of long-range order. This is interpreted as a formation of mesomorphic β phase with an orthorhombic unit cell (a = 29.1 Å, b = 28.1 Å, and c = 16.7 Å). Structural analogues to other 9,9-di-n-alkyl-substituted polyfluorenes are discussed in terms of unit cell parameters and backbone geometry.

Synthesis and liquid crystalline behavior of side chain liquid crystalline polymers containing triphenylene discotic mesogens with different length flexible spacers

A series of side chain liquid crystalline polymers (SCLCPs) containing triphenylene (Tp) units in the side chains, denoted as PMTS (without spacer) and PMTnS (n = 2, 3, 4, 6, which is the number of the methylene units between the main chain and Tp moieties in the side chains), with different lengths of spacers were synthesized through conventional free radical polymerization. The chemical structures of the monomers were confirmed by 1H/13C-NMR, and the phase behaviors were examined by differential scanning calorimetry (DSC), polarized optical microscopy (POM) and wide-angle X-ray diffraction (1D and 2D WAXD). The molecular characterization of the polymers was performed with 1H-NMR, gel permeation chromatography (GPC) and thermogravimetric analysis (TGA). The phase behaviors of the polymers have been investigated by a combination of techniques including DSC, POM, 1D and 2D WAXD. The results showed that the length of spacer has significant effects on the LC phase behavior of polymers. For PMTS and PMT2S, they displayed the columnar phase developed by the Tp moieties and the main chain as a whole due to the strong coupling effect of the Tp moieties and the main chain. For the PMT3S, PMT4S and PMT6S, they formed the symmetry hexagonal columnar (ΦH) phase owing to the decoupling effect. All of these indicated that the “decoupling effect” or “coupling effect” depended on the length of spacers, leading to the different LC phase formation mechanism.

Natural products as sources of new fungicides (II): antiphytopathogenic activity of 2,4-dihydroxyphenyl ethanone derivatives

A series of 17 simple 1-(2,4-dihydroxyphenyl) ethanones were synthesised, and their structures characterised by 1H, 13C NMR and ESI-MS. Their in vitro antifungal activities were evaluated against five phytopathogenic fungi including Glomerella cingulate, Botrytis cirerea, Fusarium graminearum, Curvularia lunata and Fusarium oxysporum f. sp. vasinfectum by the mycelial growth inhibition assay. Compounds 2g and 2h exhibited broad-spectrum inhibitory activity against the mycelial growth of the tested pathogens with IC50 values in the range of 16–36 μg/mL, and in particular being more active to G. cingulate, with IC50 values of 16.50 and 19.25 μg/mL, respectively, than the other pathogens. Preliminary SAR indicated that an α,β-unsaturated ketone unit of the alkyl chain of the compounds is the structure requirement for fungicidal action. The results suggested that 2g and 2h may be promising leads in the development of new antifungal agents.

Statistical thermodynamic properties of a new self-condensing vinyl polymerization system

A new self-condensing vinyl polymerization system consisting of AB f *-type inimers is studied by the principle of statistical mechanics. To obtain the relevant average properties of the system, a differential equation satisfied by the polymeric moment of interest is given, and as a result the zeroth, first, second, and third polymeric moments together with the size distribution function of hyperbranched polymers (HBPs) are explicitly presented. As an application of the method of statistical mechanics, several thermodynamic quantities such as the equilibrium free energy, law of mass action, isothermal compressibility, internal energy, and the specific heat associated with the polymerization are all derived. Furthermore, the scaling behavior of asymptotic size distribution function is discussed, by which a reasonable interpretation of the polydispersity index near the end of polymerization can be made. Also, the expressions of some structural parameters such as the numbers of inimers, terminal units, chain units, branched units, and the degree of branching (DB) are calculated. It is found that a high functionality is helpful to improve the DB of the resultant HBPs. These results show that the functionality f has a significant effect on the thermodynamic quantities and structural properties of HBPs.

Kinetic study, characterization and theoretical studies of oxidative chemical polymerization of para-aminophenol in acid medium using k2cr2o7 as oxidizing agent

The synthesis of poly-p-aminophenol (PPAP) by oxidative chemical polymerization using potassium dichromate as oxidizing agent was carried out. The optimum conditions for the polymerization reaction were investigated. The order of reactions and thermodynamic activation parameters were calculated. A molecular mechanism for the oxidation of p-aminophenol using potassium dichromate is proposed. This mechanism explains the specific features of p-aminophenol oligomerization and polymerization reactions. Spectroscopic studies using IR, UV–vis and elemental analysis have evidenced the structure of polymeric chain. The surface morphology of the obtained polymer was characterized by X-ray diffraction and transmission electron microscopy (TEM). The thermo gravimetric analysis (TGA) was used to confirm the proposed structure and number of water molecules in each polymeric chain unit. Moreover, determinations of dielectric properties of the prepared polymer at the investigated optimum condition were carried out. The a.c conductivity (σ ac ) of (PPAP) was investigated as a function of frequency and temperature. The microscopic conduction mechanism of charge carries over the potential barrier in polymer backbone was found to be classical hopping model. The equilibrium ground state geometric parametric of p-aminophenol (PAP) neutral monomer and radical cation are investigated theoretically using DFT – B3LYP/ 6-311G ** level of calculation. The initiation and propagation steps of oxidative chemical polymerization are theoretically investigated.

Ionic Conduction and Dielectric Relaxation in Poly(ethylene carbonate)-Li Salt Electrolytes

Polymer electrolytes such as poly(ethylene oxide) (PEO)-metal salt complexes have attracted much attention as ion-conductive soft materials for novel battery systems, because of their safety compared with liquid electrolytes, their flexibility and their lightweight. However, the conductivity of typical PEO-based electrolytes is limited to approximately 10-5 S/cm at room temperature, and it is extremely difficult to enhance the lithium (cation) transference number. We believe that the development of novel polymers without PEO chains is one solution for improving the conductivity. So we consider polycarbonates that can be obtained by the alternating copolymerization of carbon dioxide with epoxides and comprise novel polymer candidates for electrolytes. Following the first report of the CO2/epoxide copolymer by Tsuruta et al., there has been considerable development of highly active catalysts for effective polymerization. This copolymer is a remarkable macromolecule because it utilizes CO2as a raw material and has excellent properties; it is biodegradable, easily processed and colored, and has high transparency and low oxygen permeability. We have focused on the chemical structure of the copolymer, which has one alternating carbonate group (-O-(C=O)-O-) in each repeating unit of the main chain. The carbonate group has a large dipole moment, and it can dissolve many types of salts. Carbonate-based organic solvents, such as dimethyl carbonate, are used as the electrolyte solution in Li-ion batteries because of their high dielectric constant. Therefore, we think that the carbonate group can provide a suitable structure for the polymer framework. In this study, we report on the use of poly(ethylene carbonate) (PEC) as a matrix for novel ion-conductive polymer electrolytes [1]. We found that the addition of small amount of TiO2 nano-particulates to the PEC-based electrolytes can enhance lithium transference numbers, t +, which are measured using an electrochemical combination method of DC polarization and AC impedance measurements for Li│electrolyte│Li cells. Moreover, we undertook lithium-7 and fluoride-19 NMR spectroscopic and pulsed field gradient (pfg) diffusion measurements on these electrolytes. The values of self-diffusion coefficients of the lithium cation (D Li) and the estimated t + values for PEC-LiFSI-TiO2 were more than 10-7 cm2/s and 0.8 at 60 oC. The Li-ion conductivities (σ at 60 oC × t + estimated from the electrochemical method) of samples PEO20LiFSI, PEC0.53LiFSI and PEC0.53LiFSI-TiO2 (1 wt%) were calculated to be 5.6×10-5, 2.2×10-4 and 4.3×10-4S/cm, which are superior as a structure to polyether as an electrolyte for flexible batteries. On the other hand, there are no detailed information on the ion-conductive behavior of PEC-based electrolytes. So, we used broadband dielectric spectroscopy (BDS) measurement for the investigation of correlation between ionic conduction and dielectric relaxation behavior over the broad range of salt concentration. We measured BDS data and analyzed dielectric spectra using the Havriliak-Negami functions. Fig. 1 shows salt concentration dependence of relaxation peak for PEC-LiTFSI electrolytes at 40 oC. A strong peak indicates α relaxation derived from segmental motion of PEC main chains. As the salt concentration increased, the α relaxation peak shifted to the high frequency region with increasing the peak area, which is opposite to the behavior of typical PEO-based electrolytes (the peak shifts to the lower frequencies) [2]. This means that the PEC-LiTFSI electrolytes show good conductivities at high salt concentrations because of the fast segmental motion with local ion-rich structures. [1] Y. Tominaga et al.,Chem. Commun., 50,4448 (2014). [2] T. Furukawa et al., Electrochim. Acta, 57,139 (2011). Acknowledgment: This work was financially supported by a Grant-in-Aid for Scientific Research (B) of JSPS KAKENHI (25288095), Japan. Fig.1 Salt concentration dependence of relaxation peaks for PEC-LiTFSI at 40 oC. Figure 1

Effects of solvent concentration and composition on protein dynamics: 13C MAS NMR studies of elastin in glycerol–water mixtures

We use 13C CP MAS NMR to investigate the dependence of elastin dynamics on the concentration and composition of the solvent at various temperatures. For elastin in pure glycerol, line-shape analysis shows that larger-scale fluctuations of the protein backbone require a minimum glycerol concentration of ~0.6g/g at ambient temperature, while smaller-scale fluctuations are activated at lower solvation levels of ~0.2g/g. Immersing elastin in various glycerol–water mixtures, we observe at room temperature that the protein mobility is higher for lower glycerol fractions in the solvent and, thus, lower solvent viscosity. When decreasing the temperature, the elastin spectra approach the line shape for the rigid protein at 245K for all studied samples, indicating that the protein ceases to be mobile on the experimental time scale of ~10−5s. Our findings yield evidence for a strong coupling between elastin fluctuations and solvent dynamics and, hence, such interaction is not restricted to the case of protein–water mixtures. Spectral resolution of different carbon species reveals that the protein-solvent couplings can, however, be different for side chain and backbone units. We discuss these results against the background of the slaving model for protein dynamics.

Synthesis and Characterization of Aliphatic-Aromatic Copolyesters From Pet Waste and ϵ-Caprolactone

Copolyesters containing aliphatic units in the main chain were obtained by reacting Bis(2-hydroxy ethyl terephthalate) (BHET) with ϵ-caprolactone (ϵ-CL) at a high temperature in bulk in the presence of tin octoate as catalyst. Various copolyesters were synthesized by using BHET/ϵ-CL mass ratio ranging from 90/10 to 10/90. Thermal properties were studied by DSC and TGA, and structural characterization was carried out by 1H-NMR spectroscopy. These techniques confirm the insertion of lactones units in PET chains. The degree of randomness of 30/70 to 60/40 copolyesters, determined by 1H-NMR, shows a random microstructure. The other copolyesters exhibit some block copolymer character.

Methyl Cinnamate-Derived Fluorescent Rigid Organogels Based on Cooperative π-π Stacking and C═O···π Interactions Instead of H-Bonding and Alkyl Chains.

A new class of rigid low-molecular-mass organic gelators (LMOGs) was synthesized by McMurry and Heck reactions, and their gels and photophysical properties were investigated. The LMOGs lacked alkyl chain and H-bonding units and produced good gelation ability in selected mixed organic solvents facilitated by cooperative π-π stacking and C═O···π interactions. Sensitive gel-sol transformation by molecular aggregation and disaggregation was easily achieved upon heating and cooling. H-H 2D NOESY and X-ray diffraction (XRD) patterns showed the π-π stacking and C═O···π interactions between tiny methyl acrylate groups as "tails". Importantly, this soft interaction model offers a useful tool for the future design and construction of supramolecular structures. At present, the LMOGs reported herein offer a sensitive gel-formation ability and aggregation-induced emission (AIE) property and thus have promising application potentials as functional soft matter in amorphous materials, photoelectric materials, and so on.

New Copolyesters Containing Aliphatic and Bio-Based Furanic Units by Bulk Copolycondensation

A straightforward substitution of non-renewable aromatic aliphatic copolyesters by renewable homologous furanic aliphatic copolyesters was successfully realized by copolymerization of furanic unit, aliphatic and 1,3-propanediol. Different copolyesters were synthesized and characterized by 1H-NMR, 13C-NMR, FTIR, DSC and TGA. For all copolyesters, the degree of randomness, determined by 1H-NMR, was close to 1, reflecting a random distribution of furanic and aliphatic ester units in polymer chains. The hydrolytic degradation of polymers was performed at pH 4.35 at 37°C over a period of four weeks. The hydrolytic degradation proved a mass loss of about 10%.