FLAVOUR AND HAZE STABILITY DIFFERENCES DUE TO HOP TANNINS IN ALL-MALT PILSNER BEERS BREWED WITH PROANTHOCYANIDIN-FREE MALT

All-malt Pilsner beers were brewed with proanthocyanidin-free malt (ant 13 × 13 × Rupal). Hopping was with n-hexane tannin-free hop extract with or without n-hexane extracted hop residue or with whole leaf hops. The different beers were analysed chemically and presented to an expert panel to detect possible preferences and differences in bitterness and astringency. The impact of hop proantho-cyanidins on haze formation is comparable to that of malt proanthocyanidins. No differences between the beers were found in triangular tests. Statistical analysis of the paired comparison tests showed that hop proanthocyanidins do not contribute to the bitterness of beer since beer brewed with tannin-free hop extract is slightly more bitter than beer brewed with whole leaf hops. No differences in astringency were noted between beers brewed with or without hop proanthocyanidins and it was found that the panel expressed a very slight preference for beer brewed with n-hexane hop extract over beer brewed with both n-hexane hop extract and extracted hop residue.     

Variable time-step <Emphasis Type="Italic">ϑ</Emphasis>-scheme for nonlinear evolution equations governed by a monotone operator

The single-step ϑ-scheme on a variable time grid is employed for the approximate solution of the initial-value problem for a nonlinear first-order evolution equation. The evolution equation is supposed to be governed by a possibly time-dependent hemicontinuous operator that is (up to a shift) monotone and coercive, and fulfills a certain growth condition. A piecewise constant as well as piecewise linear prolongation of the time-discrete solution is shown to converge towards the exact solution if ϑ≥1/2 (including the Crank-Nicolson scheme). In the appearance of a strongly continuous perturbation of the monotone main part, the method is still convergent if ϑ>1/2 and if the ratio of adjacent step sizes is bounded from above by a power of ϑ/(1−ϑ). Besides convergence also well-posedness of the time-discrete problem as well as a priori error estimates are studied.      

Effect of magnesium deficiency on post-heparin lipase activity and tissue lipoprotein lipase in the rat

Previous studies have provided evidence that Mg deficiency affects lipid metabolism. The present experiments were designed to assess whether the hypertriglyceridemia associated with Mg deficiency was related to alterations in post-heparin lipase activity (PHLA). Mg-deficient and control diets were pair-fed to weanling Wistar rats for eight days and plasma lipoproteins were separated into various density classes by sequential preparative ultracentrifugation. Triglycerides were significantly increased in chylomicrons and in the very low density lipoprotein, low density lipoprotein and high density lipoprotein (HDL) fractions. Cholesterol and phospholipid levels were significantly lower in the HDL fraction. PHLA in deficient rat was substantially lower than in control rats. The inverse correlation between plasma triglyceride concentration and PHLA strongly suggests that hypertriglyceridemia is the result of defective lipolysis of plasma triglycerides in Mg-deficient rats. Further examination of the PHLA was carried out by salt-mediated inhibition of lipoprotein lipase (LPL) and by heparin sepharose affinity chromatography and purified rat LPL antiserum. The results indicate that hepatic lipase is significantly decreased in Mg-deficient rats but the low PHLA is due mainly to a decline in LPL. However, total LPL activity, that is, both the intracellular and the extracellular oools of LPL in adipose tissue, heart and diaphragm, were unaffected by Mg deficiency. The results suggest that the decrease of LPL activity in the plasma of Mg-deficient rats may be due to a selective decrease in the heparin-releasable pool of enzyme.     

Bulk electro-optic deflector-based switches

We propose two novel electro-optic (EO) deflectors based on two new nonrectangular geometries: the parabolic and the half-horn configurations. These devices not only provide excellent deflection angles, but also have the potential to build nonblocking 2 x 2 optical switches. A deflector figure of merit is defined, and comparisons with existing EO deflectors are given. Devices fabricated in LiTaO(3) demonstrate 3 dB of average insertion loss and 3 degrees deflection angles. These results represent the best deflection performances to our knowledge reported to date for bulk EO deflectors.     

A dangerous entanglement

Entrapment of guidewires by inferior vena cava filters can occur during the blind insertion of a jugular or a subclavian central venous catheter. Recently, few case reports have been published in the radiology literature. In addition, others have described endovascular techniques aimed at removing entrapped guidewires, avoiding the possibility of vena cava rupture. Given that a temporary hemodialysis venous catheter is frequently used as a first access, the possibility of entrapping the dialysis catheter guidewire should not be neglected.     

The effect of size on the strength of coarse rock aggregates and large rockfill samples through experimental data

Testing the mechanical response of coarse granular materials requires very large and expensive laboratory equipments. During the 1960s, pioneering experimental programs were carried out on several rockfill dam materials, and those results are still a reference for engineers and researchers. However, only few experimental works have been reported to this day, and due to the scarcity of empirical data, the role of the size effect caused by grain crushing is not well known. To improve understanding of this rarely studied issue and the influence of individual particle strength, this paper analyzes the size effect on rock aggregate crushing strength and its connection with the shear envelope of rockfills. The suitability of the 4-parameter Weibull equation to describe size effects on the crushing strength reported in the literature is discussed. Furthermore, a Weibull statistical analysis was carried out for a wide number of experimental results on rock aggregates, where it has been observed that strength decreases with particle size. In parallel, the results of large triaxial tests on homothetic scaled rockfill samples of 250 and 1,000 mm in diameter reveal that the coarser the material, the higher the amount of grain breakage and the lower the shear strength. The impact of size effects obtained from the experiments is analyzed and discussed in terms of the factor of safety of rockfill slope stability. Furthermore, the results are compared with the only existing theoretical method that links the rock aggregate with the strength of the granular assembly. Good agreement between the empirical results and this theoretical method has been confirmed.     

Silane Deuteration Catalyzed by Ruthenium Bis(dihydrogen) Complexes or Simple Metal Salts

The deuteration of a diverse group of silanes: alkyl‐, aryl‐, alkoxy‐ and chlorosilanes, siloxane and silazane, under an atmosphere of dideuterium (D₂) was explored with ruthenium bis(dihydrogen) dihydride complexes and hydrated metal salts. Deuterium incorporation of greater than 97% for the silanes O(SiMe₂H)₂, Et₃SiH, (EtO)₃SiH and Me₂ClSiH was possible with 0.1 mol% of the ruthenium complex [RuH₂(η²‐H₂)₂(PCyp₃)₂] [0.05 mol% for O(SiMe₂H)₂] when catalysis was conducted in the neat silane at 30 °C under 1 bar of D₂ for 3.5 h. The air‐stable ruthenium trichloride salt RuCl₃⋅x H₂O was also an efficient catalyst for the deuteration of O(SiMe₂H)₂ and Et₃SiH; deuterium incorporations for the two silanes of 93% and 90%, respectively, were possible under the same conditions as for [RuH₂(η²‐H₂)₂(PCyp₃)₂] with 0.1% catalyst loading. Hydrogen–deuterium exchange of O(SiMe₂H)₂ catalyzed by the rhodium trichloride (RhCl₃⋅x H₂O) and iridium trichloride (IrCl₃⋅x H₂O) was similarly efficient as with RuCl₃⋅x H₂O although catalytic alacrity dropped for Et₃SiH.

     

Stress Corrosion Cracking of Stainless Steel Refractory Anchors Prior to Service

This paper presents the results of an examination of cracking discovered in stainless steel anchors in a refractory block destined for inclusion in an ignition hood. Cracking was found to be a result of stress corrosion cracking due to exposure to chlorides from the breakdown of PVC electrical tape in which the anchors had been wrapped to form an expansion coating during the curing of the refractory material into which the anchors were inserted.