The prediction of mechanical properties of injection moulding parts by vacuum casting

The behaviour of vacuum cast prototypes and injection moulding parts in mechanical tests was compared. The mechanical tests were made using real production parts as references. Distinct correlations were found between vacuum cast prototypes and injection moulding parts. In this light, vacuum cast prototypes can be used for the evaluation of injection moulding products with certain limitations. Vacuum casting is best suited for the evaluation of such mechanical properties of injection moulding products as tensile, flexural and compression strength, while impact strength is the property that is most difficult to evaluate.     

CoLn dinuclear complexes (Ln = Gd,Tb, Dy,Ho and Er) as platforms for 1,5-dicyanamide-bridged tetranuclear Co2Ln2 complexes: A magneto-structural and theoretical study

Five acetate-diphenoxo triply-bridged Co^II-Ln^III complexes (Ln^III = Gd, Tb, Dy, Ho, Er) of formula [Co(μ-L)(μ-Ac)Ln(NO₃)₂] and two diphenoxo doubly-bridged Co^II-Ln^III complexes (Ln^III = Gd, Tb) of formula [Co(H₂O)(μ-L)Ln(NO₃)₃]·S (S = H₂O or MeOH), were prepared in one pot reaction from the compartmental ligand N,N′,N′′-trimethyl-N,N′′-bis(2-hydroxy-3-methoxy-5-methylbenzyl)diethylene triamine (H₂L). The diphenoxo doubly-bridged Co^II-Ln^III complexes were used as platforms to obtain 1,5-dicyanamide-bridged tetranuclear Co^II-Ln^III complexes (Ln^III = Gd, Tb, Dy, Ho, Er). All exhibit ferromagnetic interactions between the Co^II and Ln^III ions and in the case of the Gd^III complexes, the J_CoGd were estimated to be ∼+0.7 cm⁻¹. Compound 3 exhibits slow relaxation of the magnetization.     

Spectral shifts and structures of phenol...Ar(n) clusters

A laser spectroscopic investigation of phenol...Ar(n) (n = 1-6) clusters in the first electronically excited state (S(1)) and the cationic ground state (D(0)) is reported. Resonance enhanced two-photon ionisation (R2PI) spectra have been recorded for the investigation of the S(1) state. The origins of S(1)← S(0) (S(1)0(0)) transition of phenol...Ar(n) (n = 1, 2,4-6) are all red shifted compared to the S(1)0(0) state of the monomer by 33 cm(-1), 67 cm(-1), 10 cm(-1), 20 cm(-1), 44 cm(-1), respectively. However, the origin of the phenolAr(3) cluster is blue shifted by 25 cm(-1). For the investigation of the ionic ground state photoionization efficiency (PIE) and mass-analyzed-threshold ionization (MATI) spectroscopy have been applied. The spectra of phenol...Ar(3) and phenol...Ar(4) yield values for the ionization energy (IE) of 68,077 ± 15 cm(-1) and 67,948 ± 15 cm(-1). With the combination of theoretical methods and R2PI, PIE and MATI spectroscopy, the major species present have been positively identified.     

Synthesis of mono- and dihydroxy-substituted 2-aminocyclooctanecarboxylic acid enantiomers

(1R,2S,6R)-2-Amino-6-hydroxycyclooctanecarboxylic acid (?)-10 was synthesized from (1R,2S)-2-aminocyclooct-5-enecarboxylic acid (+)-2 via an iodolactone intermediate, while (1R,2S,3R,4S)-2-amino-5,6-dihydroxycyclooctanecarboxylic acid (?)-12 was prepared by using the OsO₄-catalyzed oxidation of Boc-protected amino ester (?)-5. The stereochemistry and relative configurations of the synthesized compounds were determined by 1D and 2D NMR spectroscopy (based on 2D NOE cross-peaks and ³J(H,H) coupling constants) and X-ray crystallography.     

Structural and electronic trends among group 15 polyhedral fullerenes

We have investigated the structural and electronic characteristics of tetrahedral, octahedral, and icosahedral fullerenes composed of group 15 elements phosphorus, arsenic, antimony, and bismuth. Systematic quantum chemical studies at the DFT and MP2 levels of theory were performed to obtain periodic trends for the structural principles, stabilities, and electronic properties of the elemental nanostructures. Calibration calculations for polyhedral clusters with up to 20 atoms showed the applied theoretical approaches to be in good agreement with high-level CCSD(T)/cc-pVTZ results. By studying fullerenes up to P₈₈₈, As₅₄₀, Sb₆₂₀, and Bi₆₂₀, we found their structures and stabilities to converge smoothly toward their experimental bulk counterparts. The diameters of the largest studied cages were 4.8, 3.7, 4.8, and 5.1?nm for the P, As, Sb, and Bi fullerenes, respectively. Comparisons with the experimentally known allotropes of the studied elements suggest the predicted polyhedral cages to be thermodynamically stable. All studied group 15 polyhedral fullerenes were found to be semiconducting, and density of states analysis illustrated clear periodic trends in their electronic structure. Relativistic effects become increasingly important when moving from P to Bi and taking the spin?Corbit effects into account by using a two-component procedure had a significant positive effect on the relative stability of bismuth clusters.     

Experimental determination of the berry phase in a superconducting charge pump

We present the first measurements of the Berry phase in a superconducting Cooper pair pump. A fixed amount of Berry phase is accumulated to the quantum-mechanical ground state in each adiabatic pumping cycle, which is determined by measuring the charge passing through the device. The dynamic and geometric phases are identified and measured quantitatively from their different response when pumping in opposite directions. Our observations, in particular, the dependencies of the dynamic and geometric effects on the superconducting phase bias across the pump, agree with the basic theoretical model of coherent Cooper pair pumping.     

Hyperpolarized [1-13C]-ascorbic and dehydroascorbic acid: vitamin C as a probe for imaging redox status in vivo

Dynamic nuclear polarization (DNP) of (13)C-labeled metabolic substrates in vitro and their subsequent intravenous administration allow both the location of the hyperpolarized substrate and the dynamics of its subsequent conversion into other metabolic products to be detected in vivo. We report here the hyperpolarization of [1-(13)C]-ascorbic acid (AA) and [1-(13)C]-dehydroascorbic acid (DHA), the reduced and oxidized forms of vitamin C, respectively, and evaluate their performance as probes of tumor redox state. Solution-state polarization of 10.5 ± 1.3% was achieved for both forms at pH 3.2, whereas at pH 7.0, [1-(13)C]-AA retained polarization of 5.1 ± 0.6% and [1-(13)C]-DHA retained 8.2 ± 1.1%. The spin-lattice relaxation times (T(1)'s) for these labeled nuclei are long at 9.4 T: 15.9 ± 0.7 s for AA and 20.5 ± 0.9 s for DHA. Extracellular oxidation of [1-(13)C]-AA and intracellular reduction of [1-(13)C]-DHA were observed in suspensions of murine lymphoma cells. The spontaneous reaction of DHA with the cellular antioxidant glutathione was monitored in vitro and was approximately 100-fold lower than the rate observed in cell suspensions, indicating enzymatic involvement in the intracellular reduction. [1-(13)C]-DHA reduction was also detected in lymphoma tumors in vivo. In contrast, no detectable oxidation of [1-(13)C]-AA was measured in the same tumors, consistent with the notion that tumors maintain a reduced microenvironment. This study demonstrates that hyperpolarized (13)C-labeled vitamin C could be used as a noninvasive biomarker of redox status in vivo, which has the potential to translate to the clinic.     

Atomic layer deposition of crystalline molybdenum oxide thin films and phase control by post-deposition annealing

Molybdenum forms a range of oxides with different stoichiometries and crystal structures, which lead to different properties and performance in diverse applications. Herein, crystalline molybdenum oxide thin films with controlled phase composition are deposited by atomic layer deposition. The MoO₂(thd)₂ and O₃ as precursors enable well-controlled growth of uniform and conformal films at 200–275 °C. The as-deposited films are rough and, in most cases, consist of a mixture of α- and β-MoO₃ as well as an unidentified suboxide MoO_x (2.75 ≤ x ≤ 2.89) phase. The phase composition can be tuned by changing deposition conditions. The film stoichiometry is close to MoO₃ and the films are relatively pure, the main impurity being hydrogen (2–7 at-%), with ≤1 at-% of carbon and nitrogen. Post-deposition annealing is studied in situ by high-temperature X-ray diffraction in air, O₂, N₂, and forming gas (10% H₂/90% N₂) atmospheres. Phase-pure films of MoO₂ and α-MoO₃ are obtained by annealing at 450 °C in forming gas and O₂, respectively. The ability to tailor the phase composition of MoO_x films deposited by scalable atomic layer deposition method represents an important step towards various applications of molybdenum oxides.     

High- and low-adhesive superhydrophobicity on the liquid flame spray-coated board and paper: structural effects on surface wetting and transition between the low- and high-adhesive states

Surface wetting is an important and relevant phenomenon in several different fields. Scientists have introduced a large number of applications where special surface wetting could be exploited. Here, we study wetting phenomena on high- and low-adhesive superhydrophobic liquid flame spray (LFS)-generated TiO₂ coatings on paper and pigment-coated board substrates using water–ethanol solution as a probe liquid. Submicrometer-scale air gaps, which exist on superhydrophobic surfaces below the liquid droplets, were more stable with the ethanol increment than the larger-scale micrometric air gaps. With the droplet ethanol concentration of 15 wt%, static contact angle as high as 155?±?2° was measured on the LFS–TiO₂-coated board. Transition from the low-adhesive wetting state to the high-adhesive state was demonstrated on the LFS–TiO₂-coated paper. The LFS method enables efficient roll-to-roll production of surfaces with special wetting properties on economically viable board and paper substrate materials.