Thermophilic biotrickling filtration of a mixture of isobutyraldehyde and 2‐pentanone

In this study, the possibility of the removal of isobutyraldehyde and 2‐pentanone was investigated in biotrickling filters (BTFs) at higher temperature (52–65 °C). First, the biodegradation of isobutyraldehyde and 2‐pentanone in activated sludge was proven by batch experiments at 52 and 62 °C. In batch experiments isobutyraldehyde was also degraded up to a temperature of 72 °C. Thereafter two bioreactors were operated in parallel, one at ambient temperature (BTF25), and one at 52 °C (BTF52). Maximum elimination capacities of 97 and 139 g m^?3 h^?1 were observed in BTF25 and BTF52, respectively, for isobutyraldehyde. Maximum elimination capacities of 53 and 63 g m^?3 h^?1 were obtained for 2‐pentanone in BTF25 and BTF52, respectively. A significant difference was observed in the operational stability of the two reactors. In the reactor at ambient temperature, operational problems such as foam formation, higher biomass accumulation and organic acid production were observed. In the thermophilic reactor these problems did not occur or were less severe. Copyright © 2007 Society of Chemical Industry     

Momentum Exchange in Straight Uniform Compound Channel Flow

Transverse exchange of momentum between the channel and the floodplain in straight uniform compound channel flow is considered in this paper. This process results in the so-called “kinematic effect,” a lowering of the total discharge capacity of a compound channel compared to the case where the channel and the floodplain are considered separately. The mechanisms responsible for the momentum exchange are considered. The transverse shear stress in the mixing region is modeled using a newly developed effective eddy viscosity concept, that contains: (1) the effects of horizontal coherent structures moving on an uneven bottom, taking compression and stretching of the vortices into account and (2) the effects of the three-dimensional bottom turbulence. The model gives a good prediction of the transverse profiles of the streamwise velocity and the transverse shear stress of the flood channel facility experiments. Characteristic features of the lateral profile of the eddy viscosity are also well predicted qualitatively, but in a quantitative sense there is room for improvement. Secondary circulations are shown to be of minor importance in straight uniform compound channel flows.     

Xylanase-mediated in situ production of arabinoxylan oligosaccharides with prebiotic potential in whole meal breads and breads enriched with arabinoxylan rich materials

Multiple studies have revealed the prebiotic activity of cereal derived arabinoxylan oligosaccharides (AXOS). This study investigated the in situ production of AXOS during bread making. In the first part, the AXOS producing capacity of different xylanases was compared in whole meal bread making. Three mesophilic xylanases originating from Bacillus subtilis, Aspergillus niger and Hypocrea jecorina, and one thermophilic xylanase from H. jecorina (HjXynA), were used in different dosages. At dosages that did not impair dough manageability, HjXynA solubilised and cleaved the arabinoxylan fraction to the largest extent, resulting in an AXOS content of 2.1% (dry basis) and an average degree of polymerisation (avDP) of 9. In the second part, the impact of HjXynA on the AXOS levels in dietary fibre enriched breads was studied. Rye or wheat bran fortified breads treated with HjXynA yielded good quality breads with AXOS levels above 2.0% with an avDP of 26 and 19, respectively.     

Diagnosis of pheochromocytoma in a hemodialysis patient through measurement of plasma catecholamines

We report the case of a patient on chronic hemodialysis treatment with paroxysms of severe arterial hypertension accompanied by tachycardia, pallor, sweating and tremor. Measurement of plasma catecholamines revealed norepinephrine level of 4625 pg/mL (reference range 191–225 pg/mL), epinephrine level of 1035 pg/mL (58–76 pg/mL) and dopamine level of 148 pg/mL (50–100 pg/mL). MRI showed a left adrenal mass of 2 cm. After the patient was started on an alpha‐1 adrenergic receptor blocker, she underwent a left adrenalectomy. Anatomopathological examination confirmed the diagnosis of pheochromocytoma. Although urinary testing is not possible in anuric hemodialysis patients, diagnosis of pheochromocytoma can be made through measurement of plasma free metanephrines and/or plasma catecholamines.     

Transition probabilities for the alkali isoelectronic sequences Li I,Na I,K I,Rb I,Cs I,Fr I

Dipole transition probabilities, oscillator strengths, lifetimes (mean lives), and branching ratios derived from a numerical Coulomb approximation are presented for experimentally identified (and some extrapolated) states n ≤ 12, l ≤ 4 for each of the following members of the alkali sequences (Z_net is the net charge of the corresponding ion): Li I

$\text{Z}{}_{\mathrm{<mtext>net</mtext>}}$

=1–15,17–24 Na I

$\text{Z}{}_{\mathrm{<mtext>net</mtext>}}$

=1–24 K L

$\text{Z}{}_{\mathrm{<mtext>net</mtext>}}$

=1–7 Rb I

$\text{Z}{}_{\mathrm{<mtext>net</mtext>}}$

=1–6 Cs I

$\text{Z}{}_{\mathrm{<mtext>net</mtext>}}$

=1–5 Fr I

$\text{Z}{}_{\mathrm{<mtext>net</mtext>}}$

=2,4 The results are presented in transition diagrams and in tables giving energy-level values and transition wavelengths as well. An appendix on hydrogen results for 5 ≤ n ≤ 12, 4 ≤ l ≤ 11 is included to represent the high-angular-momentum states of all members of the alkali isoelectronic sequences.     

The Antibiotic Doxycycline Impairs Cardiac Mitochondrial and Contractile Function

Tetracycline antibiotics act by inhibiting bacterial protein translation. Given the bacterial ancestry of mitochondria, we tested the hypothesis that doxycycline—which belongs to the tetracycline class—reduces mitochondrial function, and results in cardiac contractile dysfunction in cultured H9C2 cardiomyoblasts, adult rat cardiomyocytes, in Drosophila and in mice. Ampicillin and carbenicillin were used as control antibiotics since these do not interfere with mitochondrial translation. In line with its specific inhibitory effect on mitochondrial translation, doxycycline caused a mitonuclear protein imbalance in doxycycline-treated H9C2 cells, reduced maximal mitochondrial respiration, particularly with complex I substrates, and mitochondria appeared fragmented. Flux measurements using stable isotope tracers showed a shift away from OXPHOS towards glycolysis after doxycycline exposure. Cardiac contractility measurements in adult cardiomyocytes and Drosophila melanogaster hearts showed an increased diastolic calcium concentration, and a higher arrhythmicity index. Systolic and diastolic dysfunction were observed after exposure to doxycycline. Mice treated with doxycycline showed mitochondrial complex I dysfunction, reduced OXPHOS capacity and impaired diastolic function. Doxycycline exacerbated diastolic dysfunction and reduced ejection fraction in a diabetes mouse model vulnerable for metabolic derangements. We therefore conclude that doxycycline impairs mitochondrial function and causes cardiac dysfunction.     

The effect of interfacial pressure in the discrete-equation multiphase model

Abgrall and Saurel [Abgrall R, Saurel R. Discrete equations for physical and numerical compressible multiphase mixtures. J Comput Phys 2003;186(2):361-396] presented a discrete-equation two-pressure two-phase model of seven equations. A main characteristic of that model is that the Riemann problems are solved between two pure fluids, and that phase interaction is determined by the Riemann solver. Here we propose a five-equation isentropic simplification of the discrete-equation model, and by examples we show how existing and new models for interfacial closures can be incorporated into it. The interfacial pressure has a determining effect on the final solution. We further show that the discrete-equation model can reproduce results for two-phase shock tubes given in the literature when the adequate interfacial-pressure model is employed. Finally, we compare the present results with those of a continuous five-equation model, and obtain very good agreement.