Cloning and Characterization of the ∆6 Polyunsaturated Fatty Acid Elongase from the Green Microalga <Emphasis Type="Italic">Parietochloris incisa</Emphasis>

The very-long-chain polyunsaturated fatty acid (VLC-PUFA), arachidonic acid (ARA, 20:4ω-6) is a component of neuron tissues such as brain and retina cells and a primary substrate for the biosynthesis of biologically active eicosanoids. The green freshwater microalga Parietochloris incisa (Trebouxiophyceae) has been shown to accumulate an extraordinary high content of ARA-rich triacylglycerols. It was thus interesting to characterize the genes involved in lipid biosynthesis in this alga. We report here the identification of a cDNA encoding for a P. incisa PUFA elongase (PiELO1) and demonstrate that the expression of PiELO1 in yeast Saccharomyces cereviseae confers its elongase activity on C18 ∆6 PUFA. Phylogenetic analysis indicated that PiELO1 is highly similar to functionally characterized ∆6 PUFA elongase genes from other green algae and lower plants. Quantitative real-time PCR expression studies showed that PiELO1 is upregulated under nitrogen starvation, the condition triggering and enhancing storage oil and ARA accumulation in P. incisa.     

The Relationship Between Phosphorus Content and Physical Properties of Electroless Nickel Deposits

The physical properties of electroless nickel deposits are intimately related to their composition. The work presented shows the relationship between deposit hardness, both as-plated and heat-treated and phosphorus content.

It is shown that in both cases maximum hardnesses are obtained with deposits of lower phosphorus content. Care must be taken with low phosphorus deposits to avoid over heat- treatment and recommendations for suitable times and temperatures are made.     

A new family of BiO(ClxBr1 − x) visible light sensitive photocatalysts

A new family of BiO(Cl_xBr_1 − x) photocatalysts have been synthesized by a hydrothermal method. The photocatalytic activity of the new material was measured on the degradation of Rhodamine B (RhB) and Acetophenone (AP) and photooxidation of potassium iodide in water under UV–vis and visible light (λ ≥ 420 nm) irradiations. In comparison to Degussa P25, the new photoactive material with x = 0.5 demonstrated 3 times higher rate in removing aqueous RhB under visible light irradiation. A morphology, chemical composition and crystalline structure of BiO(Cl_xBr_1 − x) were characterized using scanning electron microscopy and powder X-ray diffraction. The values of their unit cell parameters depend on Cl/Br ratio and they change according to the Vegard's law.     

Gravitational and microwave-assisted thawing during milk whey cryoconcentration

Cryoconcentration technology was successfully used to produce milk whey concentrates. Effect of cryoconcentration stage and thawing mode on process efficiency and physico-chemical characteristics of the concentrated and ice fractions were studied. It was found that the effect of the cryoconcentration stage was significant, whereas the thawing mode had no effect. Microwave-assisted thawing mode was an efficient procedure and was faster than gravitational mode. Whey concentrate with 37.72 ± 0.69% of total dry matter was obtained. Proteins were concentrated up to 6.49 ± 0.31% (w/v). The concentrated fraction was rich in potassium ions. To achieve high process efficiency, the whey should be completely frozen and thawed in three cryoconcentration stages because the process efficiency drastically decreased at the fourth cryoconcentration stage, because of high dry matter content of the frozen solution obtained in the preceding stage.     

Oscillating-cup technique for yield stress and density measurement

We discuss a possibility for simultaneous measurement of different viscometric properties by the oscillating-cup technique. The emphasis is on the following problems related to liquid metal viscometry: identification of non-Newtonian fluid flow and combined viscosity/density measurement. The cases of Bingham and Newtonian fluids are analysed in detail. The basic features of nonlinear fluid flow, viscometer oscillations, modelling of experiment and data processing are systematized and interpreted in terms of linear viscous fluids.     

PROSE treatment of corneal ectasia

PurposeProsthetic replacement of the ocular surface ecosystem (PROSE) uses custom designed and fabricated prosthetic devices in a treatment that restores vision, supports healing, reduces symptoms and improves quality of life in patients with complex corneal disease. We report the success rate for PROSE treatment of corneal ectasia.MethodsRecords of 59 patients with corneal ectasia seen in consultation over 6 months were reviewed. Candidacy for treatment, topographic indices, change in visual acuity, achievement of satisfactory fit, device wear status and change in visual function at 6 months were recorded.ResultsSixteen eyes were non-candidates because conventional correction was adequate. Trial devices were inserted but not dispensed for 13 eyes. No eyes were excluded for severity of ectasia. In the remaining 89 eyes, satisfactory fit was achieved and a device was dispensed. Twenty-one eyes (15 patients) had undergone penetrating keratoplasty. Device wear at 6 months was documented in 78/89 eyes (88%). NEI VFQ-25 score improved 27.6 points (p < 0.001) on a 100 point scale in patients wearing a device at 6 months.ConclusionAll candidate eyes with corneal ectasia could be fitted with a PROSE device. PROSE treatment has a high success rate when measured by ability to achieve satisfactory fit, impact on visual acuity and 6 month data on both rate of continued wear and impact on visual function. PROSE treatment is an alternative to penetrating keratoplasty for patients with corneal ectasia who are contact lens intolerant.     

Vapor–liquid equilibrium in the sodium carbonate–sodium bicarbonate–water–CO2-system

Vapor–liquid equilibria of the carbon dioxide loaded sodium carbonate–water system were measured in the temperature range 40–80 °C and for sodium carbonate concentrations 8–12 wt%. In addition the vapor pressure of water over 10–30 wt% sodium carbonate solutions for the temperature range 27–100 °C was measured in an ebulliometer. The system was modeled using the electrolyte-NRTL model. Experimental vapor–liquid data from this study as well as data available in the literature from 25 to 195 °C and for sodium carbonate concentrations from 0.5 to 12 wt% were used for parameter fitting. The average deviation of the model predictions compared to all experimental data found is 9.8% for the partial pressure of CO₂. For vapor pressure of water the standard deviation is 0.6% up to 100 °C and 30 wt% sodium carbonate solutions.     

Design of X-ray supermirrors

A new approach is proposed for the design of wide band-pass multilayer optical elements operating in the hard X-ray spectral region. The method, based on the combination of analytical and numerical methods, solves the inverse problem consisting of inferring the composition profile of a depth-graded multilayer coating. The key feature of our approach consists in using an analytical expression for the depth-distribution of the period as initial solution for direct computer calculations. This allows a global minimization of the merit function and a many-fold decrease of the computer run time. Simulations of two particular cases are presented: a constant reflectivity over a wide spectral range and a complicated reflectivity profile. The best choice of material pairs for composing a depth-graded multilayer structure is discussed from the viewpoint of maximum achievable reflectivity and least number of bi-layers. Features of depth-graded multilayer mirrors, which are distinctive from conventional periodic mirrors, are examined. The factors influencing the optical quality of broad-band multilayers are also considered.