γ Irradiation of Bulk MgB2 Superconductor

Current–voltage (I–V) characteristics of MgB₂ bulk sintered superconductor, prepared from the commercially available powder (Alfa-Aesar), have been investigated before and after several γ irradiations up to 5000 MR. A minor increase in the normal state resistance of the sample was observed up to 5000 MR without any change in its critical temperature (T _c ). I–V characteristics before and after γ irradiation with different doses up to 5000 MR were shown and fitted to the expression V∝I ^β(T,B) where β approaches unity near T _c before and after γ irradiation. A decrease in the critical currents (I _c ) with γ irradiation up to 1000 MR was observed; after which they start to increase with higher irradiations up to 5000 MR without exceeding the critical currents before irradiation.     

Interdialytic blood pressure obtained by ambulatory blood pressure measurement and left ventricular structure in hypertensive hemodialysis patients

Unlike in subjects with normal renal function, the relationship between hypertension and cardiovascular morbidity and mortality in dialysis patients is still being debated. In order to clarify this issue, we performed 44-hour ambulatory blood pressure measurements (ABPM) during the interdialytic period in a group of 164 hypertensive patients, the blood pressure (BP) control based on conventional antihypertensive strategy previously, on chronic hemodialysis treatment in the Mediterranean region of Turkey. These results were then compared with their echocardiographic data. This is a cross-sectional analysis. The mean ABPM during 44 hours was close to the manually measured predialysis value, but there was a gradual increase in the ABPM values in the interdialytic period. When divided into a group with mild or no left ventricular hypertrophy (LVH) (45 patients) and severe LVH (119 patients), the latter had significantly higher BP levels in all separate periods, while the difference in predialysis BP was not significant. Patients with severe LVH had larger left atrium and left ventricular diameters, and consumed more antihypertensive drugs. Systolic BP during the night before dialysis showed the strongest relation to LVH, but interdialytic weight gain was also independently related to LVH. Yet, 56% of the patients with systolic BP <135 had severe LVH. There is not only an association between BP and presence of LVH, but it is shown that volume expansion is also an important independent determinant of LVH. This may explain the difficulty in identifying hypertension as a cardiac risk factor in these patients.     

Heuristic-based neural networks for stochastic dynamic lot sizing problem

Multi-period single-item lot sizing problem under stochastic environment has been tackled by few researchers and remains in need of further studies. It is mathematically intractable due to its complex structure. In this paper, an optimum lot-sizing policy based on minimum total relevant cost under price and demand uncertainties was studied by using various artificial neural networks trained with heuristic-based learning approaches; genetic algorithm (GA) and bee algorithm (BA). These combined approaches have been examined with three domain-specific costing heuristics comprising revised silver meal (RSM), revised least unit cost (RLUC), cost benefit (CB). It is concluded that the feed-forward neural network (FF-NN) model trained with BA outperforms the other models with better prediction results. In addition, RLUC is found the best operating domain-specific heuristic to calculate the total cost incurring of the lot-sizing problem. Hence, the best paired heuristics to help decision makers are suggested as RLUC and FF-NN trained with BA.     

C-banding visualized by atomic force microscopy

C-banding is a method used for studying chromosome rearrangements near centromeres and for investigating polymorphisms. In human chromosomes, the C-bands are located at the centromere of all the chromosomes and the distal long arm of the Y chromosome. In this study, we aimed to detect the structural changes in chromosomes during the stages of C-banding by atomic force microscopy. We observed crater-like structures in the chromosomes after 2xSSC (saline sodium citrate) treatment and measured the relative difference between the heights of chromatid and centromere of the chromosomes. Results showed that the relative difference was 3 nm in chromosomes 1, 9, 16, and Y, whereas in the other chromosomes this value was 11.6 nm. After Giemsa staining, the relative difference increased by a factor of 16 in chromosomes 1, 9, 16, and Y. The other chromosomes showed no such increase, which is in accordance with our suggestion that nonhiston proteins associated with DNA in constitutive heterochromatin can make the constitutive heterochromatin resistant to C-banding.     

In vitro bioaccessibility of coenzyme Q10 in enriched yoghurts

In this study, the aim was to determine the bioaccessibilities of coenzyme Q10 (CoQ10) in yoghurt samples produced using enriched skim milk with different coenzyme Q10 preparations. First, emulsified coenzyme Q10, γ‐cyclodextrin/coenzyme Q10 complex and nanoparticle coenzyme Q10 were prepared with the reference coenzyme Q10 standard. These coenzyme Q10 preparations were added into the milk to produce coenzyme Q10 enriched yoghurt samples. Nanoparticle coenzyme Q10 was obtained as in spherical shape with 176.00 ± 50.62 nm diameter. Coenzyme Q10 bioaccessibility was found as 50.59 ± 1.88% in control yoghurt. The yoghurt enriched nanoparticle coenzyme Q10 had the highest coenzyme Q10 bioaccessibility (73.81 ± 1.61%) among the produced yoghurts (P < 0.01). Coenzyme Q10 bioaccessibilities were also found as 63.75 ± 0.91% and 46.83 ± 1.27% in yoghurts enriched with emulsified coenzyme Q10, and γ‐cyclodextrin/coenzyme Q10 complex, respectively.     

Comments on “On-line optimal tracking control of continuous-time systems”

In this note, we discuss a previously published paper by Chou et al. [Chou JH, Hsieh CH, Sun JH. On-line optimal tracking control of continuous-time systems. Mechatronics 2004;14:587–97]. The method proposed by authors is based on a sequential on-line identification and optimal control idea. We show that the identification part is not correct in the suggested form and we modify the identification part by suggesting a version of recursive least-squares algorithm. In addition, the identifiability of an arbitrary system is questioned and a counter-example is given. Next, we show that the application of optimal control to the identified linear moving model is not based on any theoretical basis and we present reasons why the method will not work for general systems. In summary, it is shown that the combined on-line identification and control method will not work in general as claimed. Finally, we propose an alternative control method to be applied for dimensionally restricted systems.     

Analysis,design, and optimization of structures with integral compliant mechanisms for mid‐frequency response

A multi‐scale paradigm is proposed that utilizes periodic, small‐scale, integral compliant mechanisms within larger‐scale structures for the attenuation of vibro‐acoustic response. Amplification principles serve as the basis for the design of these mechanisms in achieving reduced energy transmission. The spectral finite element method is exploited for a force–velocity and energy flow analysis of the resultant truss‐like structures. A genetic algorithm is employed to optimize structure size for greatest effectiveness in the frequency range of interest. This study demonstrates that a significant decrease in structural vibration is achievable and suggests promising applications including the design of acoustic isolation panels for broadband vehicle noise reduction. Copyright © 2007 John Wiley & Sons, Ltd.