Eignungsvergleich verschiedener Schwarzpappelhölzer zur Zellstoffgewinnung

Zusammenfassung Beschreibung der untersuchten 1 Schwarzpappelarten. Wicktebestimmungen. Faserl?ngenmessungen. Mikroskopische Untersuchungen an Holzquerschnitten. Analysen der H?lzer. Bestimmung des Reinzellulosegehaltes und der Baftfestigkeit der Pentosane nach drei verschiedenen Verfahren: Chlorierung, Sulfataufschlu? und Natriumchloritaujschlu?. Erkl?rung für die au?erordentlich hohen Festigkeiten der Zellstoffe im Gebiete optimaler Ausbeute. Die überlegenheit der Pappelh?lzer gegenüber Buchenholz zur Herstellung von Papier- und Kunstfaserzellstoffen. Zusammenfassung.     

Air flow in cavities of labyrinth seals

The leakage flow rate through a sequence of labyrinth seal cavities, and the associated pressure and the circumferential velocity distributions are calculated for seals used in turbomachinery. Computational Fluid Dynamics is used to justify the use of bulk cavity variables, and to analyze the details of the flow in a single cavity under steady state, axisymmetric conditions. Periodic, analytic solutions of the continuity and circumferential momentum equations are obtained for the case of time dependent flow generated by a non-axisymmetric rotation of the shaft. The dynamic stiffness and damping coefficients necessary for the lateral stability analysis of the rotor are then calculated. The results compare reasonably well to experimentally obtained values.     

Influence of sample preparation on analytical results: drug analysis [GC/MS] on hair snippets versus hair powder using various extraction methods

We investigate the nucleotide sequences of 23 retroelements (4 mammalian retroviruses, 1 human, 3 yeast, 2 plant, and 13 invertebrate retrotransposons) in terms of their oligonucleotide composition in order to address the problem of relationship between retrotransposons and retroviruses, and the coadaptation of these retroelements to their host genomes. We have identified by computer analysis over-represented 3-through 6-mers in each sequence. Our results indicate retrotransposons are heterogeneous in contrast to retroviruses, suggesting different modes of evolution by slippage-like mechanisms. Moreover, we have calculated the Observed/Expected number ratio for each of the 256 tetramers and analysed the data using a multivariate approach. The tetramer composition of retroelement sequences appears to be influenced by host genomic factors like methylase activity.     

Simulation and Fabrication of Stronger,Larger, and Faster Walking Biohybrid Machines

Advancing biologically driven soft robotics and actuators will involve employing different scaffold geometries and cellular constructs to enable a controllable emergence for increased production of force. By using hydrogel scaffolds and muscle tissue, soft biological robotic actuators that are capable of motility have been successfully engineered with varying morphologies. Having the flexibility of altering geometry while ensuring tissue viability can enable advancing functional output from these machines through the implementation of new construction concepts and fabrication approaches. This study reports a forward engineering approach to computationally design the next generation of biological machines via direct numerical simulations. This was subsequently followed by fabrication and characterization of high force producing biological machines. These biological machines show millinewton forces capable of driving locomotion at speeds above 0.5 mm s^?1. It is important to note that these results are predicted by computational simulations, ultimately showing excellent agreement of the predictive models and experimental results, further providing the ability to forward design future generations of these biological machines. This study aims to develop the building blocks and modular technologies capable of scaling force and complexity of these devices for applications toward solving real world problems in medicine, environment, and manufacturing.     

A branch and bound algorithm for scheduling unit size jobs on parallel batching machines to minimize makespan

In this paper, we present a branch and bound algorithm for the parallel batch scheduling of jobs having different processing times, release dates and unit sizes. There are identical machines with a fixed capacity and the number of jobs in a batch cannot exceed the machine capacity. All batched jobs are processed together and the processing time of a batch is given by the greatest processing time of jobs in that batch. We compare our method to a mixed integer program as well as a method from the literature that is capable of optimally solving instances with a single machine. Computational experiments show that our method is much more efficient than the other two methods in terms of solution time for finding the optimal solution.     

Highly Hydrophobic ZIF‐8/Carbon Nitride Foam with Hierarchical Porosity for Oil Capture and Chemical Fixation of CO2

The introduction of hierarchical porosity into metal‐organic frameworks (MOFs) has been of considerable interest in gas separation and heterogeneous catalysis due to the efficient mass transfer kinetics through meso/macropores. Here, a facile, scalable approach is reported for the preparation of carbon nitride (CN) foams as structural templates with micrometer‐sized pores and high nitrogen content of 25.6 wt% by the fast carbonization of low‐cost melamine foam. The nitrogen functionalities of CN foam facilitate chemical anchoring and growth of ZIF‐8 (zeolitic imidazolate frameworks) crystals, which leads to the development of hierarchical porosity. The growth of ZIF‐8 crystals also renders CN foam, which is hydrophilic in nature, highly hydrophobic exhibiting 135° of water contact angle due to the enhanced surface roughness, thus creating a natural shield for the MOF crystals against water. The introduction of ZIF‐8 crystals onto the CN foam enables selective absorption of oils up to 58 wt% from water/oil mixtures and also facilitates the highly efficient conversion of CO₂ to chloropropene carbonate in a quantitative yield with excellent product selectivity. Importantly, this present approach could be extended to the vast number of MOF structures, including the ones suffering from water instability, for the preparation of highly functional materials for various applications.     

The production and characterization of poly(lactic acid) fibers dyeable with anionic dyes using octaammonium polyhedral oligomeric silsesquioxane nanoparticle

In this study, acid dyeable poly(lactic acid) (PLA) fiber was produced with the addition of octaammonium polyhedral oligomeric silsesquioxane (OA-POSS) nanoparticle during the melt spinning. The tensile, thermal and morphological properties of the fiber samples were characterized by tensile testing, differential scanning calorimetry, scanning electron microscopy and transmission electron microscopy. Two different anionic dyes, a disulphonated 1:2 premetallised acid dye and monosulphonated non-metallised, were used. The effects of dyeing conditions including dyeing temperature and time, OA-POSS concentration, anionic dye types and concentrations were investigated on the dyeability properties of the PLA fiber samples. It was concluded that the percent crystallinity and the tensile strength of pure PLA fiber decreased as the added amount of OA-POSS increased. According to the dyeing results, the addition of OA-POSS greatly improved the dyeability of the PLA fiber with anionic dyes by introducing ion–ion interaction between the terminal ammonium groups of POSS nanoparticle and the sulphonyl groups of dye molecules.     

Carbonization of petroleum feedstocks II: Chemical constitution of feedstock asphaltenes and mesophase development

The characterization of the asphaltene fractions of a range of petroleum feedstocks by FT-IR, ¹H and ¹³C NMR spectroscopy indicated distinct differences in the molecular structure of the asphaltenes. Some of these differences could be related to the variations in the size of the principal optical texture of the semi-cokes produced by carbonization. The principal optical texture size was observed to increase steadily with the increasing hydrogen aromaticity of the asphaltenes over the whole range of the feedstocks used. There was no consistent correlation, however, between the carbon aromaticity of the asphaltenes and the optical texture size. The correlation between the hydrogen aromaticity and the principal optical texture size was attributed to structural differences among the asphaltenes that are critically important for the mesophase development.     

Phospholipid studies of marine organisms: V1 new α-methoxy acids fromHigginsia tethyoides

The phospholipids of the demospongeHigginsia tethyoides are shown to have at least 16 long-chain α-methoxy acids, which represent a new class of fatty acids. Among them are the saturated α-methoxy acids containing 19–24 carbon atoms. The monounsaturated compounds are 2-OMe-Δ¹⁷-24:1, 2-OMe-Δ¹⁸-25:1, 2-OMeΔ¹⁹-26:1 and 2-OMe-Δ²¹-28:1. The major diunsatured ones were shown to be 2-OMe-Δ^{5, 19}-26:2 and 2-OMe-Δ^{7, 21}-28:2. Small amounts of 2-OMe-23∶1, 2-OMe-26∶3; 2-OMe-27∶1 and 2-OMe-28∶3 were also encountered. Structures of the minor monounsaturated compounds were tentatively assigned as 2-methoxy-16-tricosenoic acid and 2-methoxy-20-heptacosenoic acids. The double bonds of the fatty acids show all-cis configuration. Circular dichroism measurements indicate an R-configuration for the α-methoxy acids. The major component of the total phospholipid acid mixture is 5,9,23-triacontatrienoic acid. Possible biosynthetic routes to these unusual phospholipid acids are discussed. The major phospholipids were phosphatidylethanolamine, phosphatidylglycerol and phosphatidylserine. The distribution of fatty acids among the phospholipids was also investigated.