C/C-SiC component for metallic phase change materials

Thanks to their high energy density and thermal conductivity, metallic Phase Change Materials (mPCM) have shown great potential to improve the performance of thermal energy storage systems. However, the commercial application of mPCM is still limited due to their corrosion behavior with conventional container materials. This work first addresses on a fundamental level, whether carbon-based composite-ceramics are suitable for corrosion critical components in a thermal storage system. The compatibility between the mPCM AlSi₁₂ and the Liquid Silicon Infiltration (LSI)-based carbon fiber reinforced silicon carbide (C/C-SiC) composite is then investigated via contact angle measurements, microstructure analysis, and mechanical testing after exposure. The results reveal that the C/C-SiC composite maintains its mechanical properties and microstructure after exposure in the strongly corrosive mPCM. Based on these results, efforts were made to design and manufacture a container out of C/C-SiC for the housing of mPCM in vehicle application. The stability of the component filled with mPCM was proven nondestructively via computer tomography (CT). Successful thermal input- and output as well as thermal storage ability were demonstrated using a system calorimeter under conditions similar to the application. The investigated C/C-SiC composite has significant application potential as a structural material for thermal energy storage systems with mPCM.     

Synthetic Peroxides Promote Apoptosis of Cancer Cells by Inhibiting P-Glycoprotein ABCB5

This article discloses a new horizon for the application of peroxides in medical chemistry. Stable cyclic peroxides are demonstrated to have cytotoxic activity against cancer cells; in addition a mechanism of cytotoxic action is proposed. Synthetic bridged 1,2,4,5-tetraoxanes and ozonides were effective against HepG2 cancer cells and some ozonides selectively targeted liver cancer cells (the selectivity indexes for compounds 11 b and 12 a are 8 and 5, respectively). In some cases, tetraoxanes and ozonides were more selective than paclitaxel, artemisinin, and artesunic acid. Annexin V flow-cytometry analysis revealed that the active ozonides 22 a and 23 a induced cell death of HepG2 by apoptosis. Further study showed that compounds 22 a and 23 a exhibited a strong inhibitory effect on P-glycoprotein (P-gp/ABCB5)-overexpressing HepG2 cancer cells. ABCB5 is a key player in the multidrug-resistant phenotype of liver cancer. Peroxides failed to demonstrate a direct correlation between oxidative potential and their biological activity. To our knowledge this is the first time that peroxide diastereoisomers have been found to show stereospecific antimalarial action against the chloroquine-sensitive 3D7 strain of Plasmodium falciparum. Stereoisomeric ozonide 12 b is 11 times more active than stereoisomeric ozonide 12 a (IC₅₀=5.81 vs 65.18 μm ). Current findings mean that ozonides merit further investigation as potential therapeutic agents for drug-resistant hepatocellular carcinoma.     

Photochlorierung und metallorganische Folgereaktionen eines verzweigten Poly(carbosilans)

Photochlorination and Metalorganic Following Reactions of a Cross-linked Poly(carbosilane) The synthesis of a perchlorinated cross-linked poly(carbosilane) of the general composition [(Cl₂Si)_1,5(SiCl) (CCl₂)₃]_x ( II ) was achieved through the photochlorination of [(Cl₂Si)_1,5(SiCl)(CH₂)₃]_x ( I ). The perchlorinated product was investigated by elemental analysis and spectroscopic methods. Furthermore the permethylated and perphenylated compounds [(Me₂Si)_1,5(SiMe)(CMe₂)₃]_x ( III ) and [(Ph₂Si)_1,5(SiPh)(CPh₂)₃]_x ( IV ) were synthesized by reactions with methyl- and phenyllithium. The products obtained were characterized by elemental analysis and ¹H, ¹³C, ²⁹Si NMR and IR spectroscopy. The number and weight averages M_n and M_w were determined by gel permeation chromatography.     

A novel germanium/carbon nanotubes nanocomposite for lithium storage material

A new nanocomposite of Ge/carbon nanotubes (n-Ge/CNTs) was reported by a facile precursor method through a pyrolysis technique. Among it, germanium nanoparticles are encapsulated with a thin layer of amorphous carbon, which benefits to keep a good electronic contact with carbon nanotubes. Germanium nanoparticles are mainly supported inside the carbon nanotubes, which can effectively buffer the volume changes of Germanium. The composite was an effectively mixed (Li⁺ and e⁻) conducting network, which is vital to a quick Li insertion. The composite was shown to exhibit a reversible capacity of about 750 mAh g⁻¹ (74.4 mA g⁻¹) and an improved rate performance, compared with that of CNTs processed as the same condition. Our results demonstrated the composite to be a good active Li-storage material for Li batteries.     

Long‐term testing of a high temperature polymer electrolyte membrane fuel cell: The effect of reactant gases

The investigations have been conducted with different oxidants and fuels with the aim of determining the state‐of‐the‐art of commercially available high temperature polymer electrolyte fuel cells based on polybenzimidazole for its application in combined heat and power generation systems. The fuel cell test performed with synthetic reformate (?63 μV/h) showed an increase of anode charge and mass transfer resistances. This behavior has suggested that CO may be generated from the CO₂ included in the synthetic reformate via reverse water gas shift reaction. The fuel cell test performed with pure O₂ developed the highest degradation rates (?70 μV/h) due to fast oxidative degradation of membrane electrode assembly materials such as cathode catalyst and membrane. Fuel cell operation with H₂/air exhibited the lowest degradation rates (?57 μV/h) and it requires longer investigating times to identify the different degradation mechanisms. Moreover, fuel cell tests performed with air suggested longer break‐in procedures to complete catalyst activation and redistribution of electrolyte. © 2015 American Institute of Chemical Engineers AIChE J, 62: 217–227, 2016     

Ketone bodies,glucose and glutamine as lipogenic precursors in human diploid fibroblasts

Incorporation of [¹⁴C] from acetoacetate, D(-)- and L(+)-3-hydroxybutyrate, glucose, glutamine, acetate and palmitate in cellular lipids were studied in cultures in human diploid fibroblasts (HDF). The results showed that acetoacetate was 2–10 times more effective as a lipogenic precursor than was either D- or L-3-hydroxybutyrate. Its extent of incorporation into lipids was 2- to 8-fold more than the other precursors examined under conditions when the overall rates of nonsaponifiable and saponi-fiable lipogenesis as measured by³H₂O incorporation were essentially unchanged. Acetoacetate supported both saponifiable and nonsaponifiable lipid syntheses with half-saturation values (K_m app.) of 185 μM and 30 μM, respectively. Glucose stimulated acetoacetate incorporation into lipids whereas, conversely, acetoacetate inhibited [¹⁴C] glucose incorporation into lipids. The presence of low density lipoproteins (LDL) cholesterol (@40 μg cholesterol/mL) inhibited the incorporation of [¹⁴C] from acetoacetate 56% into nonsaponifiable lipids; the inhibition was consistently higher (75%) when [¹⁴C] glucose or glutamine were the precrusors. The loss of 3-hydroxy-3-methyl-glutaryl CoA (HMG CoA) reductase activity upon addition of LDL-cholesterol was greater than the suppression of [¹⁴C] incorporation from acetoacetate or glucose into nonsaponifiable lipids. In the presence of glucose, [¹⁴C] acetoacetate was incorporated into 3-βOH sterols (digitonin precipitable). 7.7±1.1 times more effectively than was [¹⁴C] glucose. The results suggest that HDF would be a suitable model to investigate the effects of various precrusors of HMG CoA on the rate of cholesterol biosynthesis.     

Investigation of the performance of carbide cutting tools with hard coatings in hard milling based on the response surface methodology

Machining of hard materials has become a great challenge for several decades. One of the problems in this machining process is early tool wear, and this affects the machinability of hard materials. In order to increase machinability, cutting tools are widely coated with nanostructured physical vapor deposition hard coatings. The main characteristics of such advanced hard coatings are high microhardness and toughness as well as good adhesion to the substrate. In this paper, the influence of hard coatings (nanolayer AlTiN/TiN, multilayer nanocomposite TiAlSiN/TiSiN/TiAlN, and commercially available TiN/TiAlN) and cutting parameters (cutting speed, feed rate, and depth of cut) on cutting forces and surface roughness were investigated during face milling of AISI O2 cold work tool steel (～61 HRC). The experiments were conducted based on 3¹³ factorial design by response surface methodology, and response surface equations of cutting forces and surface roughness were obtained. In addition, the cutting forces obtained with the coated and uncoated tools were compared. The results showed that the interaction of coating type and depth of cut affects surface roughness. The hard coating type has no significant effect on cutting forces, while the cutting force F _z is approximately two times higher in the case of uncoated tool.     

Spatial planning for landscape: mapping the pitfalls

While welcoming the European Landscape Convention and acknowledging the successes of conservation organizations such as the National Trust in Britain, the Czech Village Restoration Scheme and the French eco‐musées, this paper identifies some of the pitfalls that must be avoided if the fine words of the Convention are to be translated into effective action. These include problems with designation, conflicts between different types of conservation, and the side effects of gentrification and increased tourism. There is a call for more research to break down barriers to understanding between countries, between disciplines, and between academics and practitioners.