Refine
Year of publication
Document Type
- Conference Proceeding (286)
- Article (reviewed) (285)
- Article (unreviewed) (97)
- Part of a Book (77)
- Contribution to a Periodical (74)
- Report (44)
- Patent (38)
- Book (34)
- Doctoral Thesis (5)
- Working Paper (2)
- Other (1)
- Periodical Part (1)
- Study Thesis (1)
Conference Type
- Konferenzartikel (205)
- Konferenz-Abstract (47)
- Konferenz-Poster (16)
- Sonstiges (14)
- Konferenzband (7)
Language
- English (562)
- German (382)
- Other language (1)
Is part of the Bibliography
- yes (945) (remove)
Keywords
- Dünnschichtchromatographie (28)
- Energieversorgung (14)
- Plastizität (13)
- Adsorption (11)
- Finite-Elemente-Methode (11)
- TRIZ (11)
- Materialermüdung (10)
- injury (10)
- Ermüdung (9)
- Geothermie (9)
Institute
- Fakultät Maschinenbau und Verfahrenstechnik (M+V) (945) (remove)
Open Access
- Open Access (400)
- Closed Access (269)
- Closed (138)
- Bronze (88)
- Gold (34)
- Hybrid (32)
- Diamond (25)
- Grün (5)
Uptakes of 9.2 mmol g−1 (40.5 wt %) for CO2 at 273 K/0.1 MPa and 15.23 mmol g−1 (3.07 wt %) for H2 at 77 K/0.1 MPa are among the highest reported for metal–organic frameworks (MOFs) and are found for a novel, highly microporous copper‐based MOF (see picture; Cu turquoise, O red, N blue). Thermal analyses show a stability of the flexible framework up to 250 °C.
Metal–organic frameworks (MOFs) as highly porous materials have gained increasing interest because of their distinct adsorption properties.1–3 They exhibit a high potential for applications in gas separation and storage,4 as sensors5 as well as in heterogeneous catalysis.6 In the last few years, the H2 storage capacity of MOFs has been considerably increased. Mesoporous MOFs show high adsorption capacities for CH4, CO2, and H2 at high pressures.2, 3, 7–10 To increase the uptake of H2 and CO2 by physisorption at ambient pressure, adsorbents with small micropores as well as high specific surface areas and micropore volumes are required.11, 12 Such microporous materials seem to be more appropriate for gas‐mixture separation by physisorption than mesoporous materials. For gas separation in MOFs the interactions between the fluid adsorptive and “open metal sites” (coordinatively unsaturated binding sites) or the ligands are regarded as important.13 Industrial processes, such as natural‐gas purification or biogas upgrading, can be improved with those materials during a vapor‐pressure swing adsorption cycle (VPSA cycle) or a temperature swing adsorption cycle (TSA cycle).14 The microporous MOF series CPO‐27‐M (M=Mg, Co, Ni, Zn), for example, shows very high CO2 uptakes at low pressures (<0.1 MPa).15, 16 Concerning H2 adsorption, the microporous MOF PCN‐12 offers with 3.05 wt % the highest uptake at ambient pressure and 77 K reported to date.17
Herein, we present a novel microporous copper‐based MOF equation image[Cu(Me‐4py‐trz‐ia)] (1; Me‐4py‐trz‐ia2−=5‐(3‐methyl‐5‐(pyridin‐4‐yl)‐4H‐1,2,4‐triazol‐4‐yl)isophthalate) with extraordinarily high CO2 and H2 uptakes at ambient pressure, the H2 uptake being similar to that in PCN‐12. The ligand Me‐4py‐trz‐ia2−, which can be obtained from cheap starting materials by a three‐step synthesis in good yield, combines carboxylate, triazole, and pyridine functions and is adopted from a recently presented series of linkers,18 for which up to now only a few coordination polymers are known.
The present study describes medium-chain-length polyhydroxyalkanoates (mcl-PHAs) production by the Pseudomonas Gl01 strain isolated from mixed microbial communities utilized for PHAs synthesis. A two-step fedbatch fermentation was conducted with glucose and waste rapeseed oil as the main carbon source for obtaining cell growth and mcl-PHAs accumulation, respectively. The results show that the Pseudomonas Gl01 strain is capable of growing and accumulating mcl-PHAs using a waste oily carbon source. The biomass value reached 3.0 g/l of CDW with 20% of PHAs content within 48 h of cultivation. The polymer was purified from lyophilized cells and analyzed by gas chromatography (GC). The results revealed that the monomeric composition of the obtained polyesters depended on the available substrate. When glucose was used in the growth phase, 3-hydroxyundecanoate and 3- hydroxydodecanoate were found in the polymer composition, whereas in the PHAs-accumulating stage, the Pseudomonas Gl01 strain synthesized mcl-PHAs consisting mainly of 3- hydroxyoctanoate and 3-hydroxydecanoate. The transcriptional analysis using reverse-transcription real-time PCR reaction revealed that the phaC1 gene could be transcribed simultaneously to the phaZ gene.
An analytical and numerical study of the wobbling dynamics of friction disks is presented. Of particular interest is the excitation mechanism taking into account two contrarian effects both originating in dry friction: the circulatory terms describing the energy input due to the sliding contacts and the friction induced damping which stabilizes the system. Balance of these terms determines the instability domain in the parameter space. It is shown that there is a slip threshold so that, if the slip is under this limit, the system remains stable. If the slip is larger than this limit, then the criterion of stability is determined by the relation between the friction coefficient and the internal damping. The limit cycle appearing in the unstable domain is also investigated. It is shown that the limit cycle can be described as a kind of a regular reverse precession of the wobbling disc. Its amplitude is limited by the geometric nonlinearity and partial contact loss. Analytic results are compared with numeric simulations.
This work provides a series of methane adsorption isotherms and breakthrough curves on one 5A zeolite and one activated carbon. Breakthrough curves of CH4 were obtained from dynamic column measurements at different temperature and pressure conditions for concentrations of 4.4 – 17.3 mol.‐% in H2/CH4 mixtures. A simple model was developed to simulate the curves using measured and calculated data inputs. The results show that the model predictions agree very well with the experiments.
Regarding the importance of adsorptive removal of carbon monoxide from hydrogen-rich mixtures for novel applications (e.g. fuel cells), this work provides a series of experimental data on adsorption isotherms and breakthrough curves of carbon monoxide. Three recently developed 5A zeolites and one commercial activated carbon were used as adsorbents. Isotherms were measured gravimetrically at temperatures of 278–313 K and pressures up to 0.85 MPa. Breakthrough curves of CO were obtained from dynamic column measurements at temperatures of 298–301 K, pressures ranging from 0.1 MPa to ca. 6 MPa and concentrations of CO in H2/CO mixtures of 5–17.5 mol%. A simple mathematical model was developed to simulate breakthrough curves on adsorbent beds using measured and calculated data as inputs. The number of parameters and the use of correlations to evaluate them were restricted in order to focus the importance of measured values. For the given assumptions and simplifications, the results show that the model predictions agree satisfactorily with the experimental data at the different operating conditions applied.
Cost effectiveness of preventive screening programmes for type 2 diabetes mellitus in Germany
(2010)
As in several other industrialized countries, Germany’s statutory health insurance (SHI) is facing rising healthcare costs as well as the challenges caused by a double-aging society. The early detection and prevention of chronic diseases is considered a possible way to reduce the impact of these developments. However, controversy surrounds the costs and effects in terms of medical and financial outcomes of such programmes.
The engineering company Evomotiv GmbH and the University of Applied Sciences Offenburg have developed a drive concept for light city scooters since 2008. The electrical drive train's goal is the series production of the highly-integrated, non-transmission and non-ferrous wheel-hub motor. The German Federal Ministry of Economy and Technology (BMWi) supports this project. The concept of this wheel-hub motor was awarded with the Bosch-Innovation prize in 2006. In 2011 Evomotiv will test the first prototypes with its cooperation partners on the track.
Thin-layer chromatography is a rapid and reliable working method for quantification of mycotoxins which is suitable for checking EC legislation aflatoxin limits for dried figs without an RP-18 pre-column cleaning step. We describe normal-phase chromatography on silica gel plates with 2.4:0.05:0.1:0.05 ( v/v ) methyl t -butyl ether-water-methanol-cyclohexane as mobile phase and reversed-phase chromatography on RP-18 plates with methanol-4% aqueous ZnSO 4 solution-ethyl methyl ketone 15:15:3 ( v/v ) as mobile phase. Sample pretreatment was by modified QuEChERS (Quick, Easy, Cheap, Effective, Rugged, Safe) extraction with tetrahydrofuran or acetone. NaCl was used as QuEChERS salt. Response was a linear function of amount chromatographed in the ranges 3 to 100 pg per zone for aflatoxins B 2 and G 2 , 10 to 350 pg per zone for the aflatoxins B 1 and G 1 , and 0.25 to 2.5 ng per zone for ochratoxin A. Quantification limits for the aflatoxins were between 13 and 35 pg per zone (equivalent to 1.5 and 2.4 ppb, taking the pre-treatment procedure into account). Ochratoxin A was detectable with a limit of quantification of 970 pg per zone, corresponding to 56 ppb in the sample. Normal phase and RP-18 separations work rapidly, reliably, and at low cost. They are also suitable for checking the content of the mycotoxins patulin, penicillic acid, zearalenone, and deoxynivalenol.
Hydrogen chloride and sulphur dioxide are gaseous by-products of chloridization processes that employ thionyl chloride. Absorption would be a feasible method to clean the rich gas stream. Two serial connectable absorption columns were equipped with the latest generation of packings to effect product recovery. Therefore, several tests concerning the baffle properties had to be performed. In the first experimental section, the hydraulic parameters pressure drop and hold-up were investigated. The hold up value range of the new baffles Raschig Super Ring (RSR) and Raschig Super Pak (RSP) was clearly below that of the former installed packing, Raschig Ring (RR). However, due to the low maximal flow rate, the range of stagnation and flooding could not be measured. The maximal measured pressure drop value was, for RR, only 0.3 mbar/m, which is very low compared to the measurement error. Batch experiments, where the waste gases were produced by reaction of thionyl chloride in water, showed that for the steady state determination of the separation steps it is advisable to use just one column in simplex mode with a defined gas supply by a gas cylinder. The HTU determination for RSR and a HCl/H2O system delivered a value of HTUHCl,OG = 0.14 ± 0.01 m with a variation coefficient of 24.2%.
A diode array HPTLC method for dequalinium chloride in pharmaceutical preparations is presented. For separation a Nano TLC silica gel plate (Merck) is used with the mobile phase methanol-7.8% aqueous NH(4)(+)CH(3)COO(-) (17:3, v/v) over a distance of 6 cm. Dequalinium chloride shows an R(F) value of 0.58. Pure dequalinium chloride is measured in the wavelength range from 200 to 500 nm and shows several by-products, contour plot visualized in absorption, fluorescence and using the Kubelka-Munk transformation. Scanning of a single track in absorption and fluorescence measuring 600 spectra in the range from 200 to 1100 nm takes 30s. As a sample pre-treatment of an ointment it is simply dissolved in methanol and can be quantified in absorption from 315 to 340 nm. The same separation can also be quantified using fluorescence spectrometry in the range from 355 to 370 nm. A new staining method for dequalinium chloride, using sodium tetraphenyl borate/HCl in water allows a fluorescence quantification in the range from 445 to 485 nm. The linearity range of absorption and fluorescence measurements is from 10 to 2000 ng. Sugar-containing preparations like liquids or lozenges with a reduced sample pre-treatment can be reliably quantified only in fluorescence. The total for the quantification of an ointment sample (measuring four standards and five samples), including all sample pre-treatment steps takes less than 45 min!