•The nanostructured Co-ferrite particles were synthesized by the sol–gel method.•The RSM method was used to optimize the initial parameter to the best result.•The annealing temperature was the most ...important factor.•The amount of EDTA was the next significant variable.•A vibrating sample magnetometer was used for magnetic property measurement.
The nanoparticles of cobalt ferrite were synthesized by using ethylene glycol and ethylenediaminetetraacetic acid precursors-based sol–gel method. In this study, special attention has been paid to investigate the role of the basic chemical parameters used in the manufacture of the cobalt ferrite by the sol–gel process, as well as the heat treatment on the structures, morphologies and magnetic properties of the obtained materials. These particles were structurally characterized by using X-ray diffraction and scanning electron microscopy and the results confirmed the formation of the spherically shaped nanoparticles of cobalt ferrite with a size of 14–39nm. The synthetic method reported here has the capability of producing nanostructured pure single-phase CoFe2O4 powder at a comparatively lower annealing temperature and offers the potential of a simpler, more cost-effective route than other reported methods. It has been found that EDTA and EG to total metal ions ratio and heat-treatment temperature have a noticeable influence on the properties of the resultant particles. The saturation magnetization varies from 50 to 83emu/g and the coercive field ranges from 525 to 960Oe that are suitable for magnetic recording purpose.
•Mild, acute sleep restriction has surprisingly robust, negative consequences to sustained vigilance.•Alpha burst activity is a sensitive electrophysiological index of drowsiness.•These findings have ...direct implications for scenarios demanding sustained vigilance.
The current study investigated the behavioral, cognitive, and electrophysiological impact of mild (only a few hours) and acute (one night) sleep loss via simultaneously recorded behavioural and physiological measures of vigilance.
Participants (N = 23) came into the lab for two testing days where their brain activity and vigilance were recorded and assessed. The night before the testing session, participants either slept from 12am to 9am (Normally Rested), or from 1am to 6am (Sleep Restriction).
Vigilance was reduced and sleepiness was increased in the Sleep Restricted vs. Normally Rested condition, and this was exacerbated over the course of performing the vigilance task. As well, sleep restriction resulted in more intense alpha bursts. Lastly, EEG spectral power differed in Sleep Restricted vs. Normally Rested conditions as sleep onset progressed, particularly for frequencies reflecting arousal (e.g., delta, alpha, beta).
The findings of this study suggest that only one night of mild sleep loss significantly increases sleepiness and, importantly, reduces vigilance. In addition, this sleep loss has a clear impact on the physiology of the brain in ways that reflect reduced arousal.
Understanding the neural correlates and cognitive processes associated with loss of sleep may lead to important advancements in identifying and preventing deleterious or potentially dangerous, sleep-related lapses in vigilance.
•An extended ELECTREI method based on VIKOR is introduced.•consider ELECTREI partial ranking problem and try to mitigate this problem with regard to relations between VIKOR and ELECTRE.•The proposed ...method considers the fuzziness in the decision data and group decision making process.
Many decision problems in real-world deal with conflicting criteria, uncertainty and imprecise information. Some also allow a group of decision makers (DMs) to make their opinions independently. Multi-criteria decision making (MCDM) is a well known decision method that can make the quality of group multiple criteria decisions better by creating a more explicit, rational and efficient process. A group of MCDM models known as “outranking methods” have been used to rank a set of alternatives. ELECTRE I is an outranking method which is simple, but provides partial ranking. So we consider VIKOR and try to mitigate this problem with regard to relations between VIKOR and ELECTRE. The objective of this paper is to extend ELECTRE I method based on VIKOR to rank a set of alternatives versus a set of criteria to show the decision maker’s preferences.
The results of in-water vortex-induced vibration (VIV) experiments on circular cylinders artificially covered with barnacles are reported. The paper focusses on the effects of the partial coverage ...and the shape of the fouling elements. An artificial barnacle typical of marine fouling was synthesised using 3-D printing. Coverage ratios of 80, 50 and 30% were examined and the results compared with those from a smooth cylinder. The Reynolds number ranged from 5.8 × 10
3
to 6.6 × 10
4
. The experimental results show that the fouling reduced the peak VIV amplitude, narrowed the synchronisation region and lowered the hydrodynamic force coefficients such as the coefficients of lift force RMS, the mean drag force and the fluctuating drag force RMS. The shape of the artificial barnacles had little effect on the maximum oscillation amplitude. The coverage ratio appeared to have a lower impact on the lift force than those on the amplitude and the frequency responses.
There are shreds of evidence that osteoarthritis is a risk factor for cardiovascular disease. Regular exercise and ozone therapy independently can prevent such diseases; however, their combined ...effect was not investigated until now. The current study was aimed to compare the independent and combined effects of aerobic training and ozone therapy on mitochondrial fission 1 protein (FIS1) and mitofusin 2 (MFN2) gene expressions, KI67 protein expression, and percentage collagen deposition in the heart tissue of rats with osteoarthritis. Thirty rats were randomly divided into five groups (six per group), named healthy control, osteoarthritis control, osteoarthritis training, osteoarthritis ozone, and osteoarthritis training + ozone. The interventions were performed according to the group name (aerobic training: run on the treadmill five sessions/week, 30 – 50 min/session for 8 weeks; ozone therapy: 20 μg/mL, once/week, for three weeks). Rat heart tissue was collected 48 h after the last intervention. Data were analyzed using two-way ANOVA and
P
< 0.05 was considered as significant effect. The results showed that osteoarthritis intervention significantly increased the expression of FIS-1 and MFN-2 genes as well as the percentage of collagen degradation in heart tissue. Osteoarthritis also decreased expression of the heart KI67 protein. Aerobic training and ozone therapy independently positively affect mentioned variables; however, the synergic effect was seen just for the percentage of collagen degradation. In conclusion, the present study confirms effectiveness of the aerobic exercise and ozone therapy concerning research variables and shows that combination of the exercise and ozone therapy had a greater effect than using either alone in improving collagen degradation.
Effects of suppression devices on the vortex induced vibration (VIV) of inclined cylinders appear not to have received previous due attentions. The current paper reports the results of some towing ...tank experiments on the vortex induced cross-flow vibrations of bare and helically straked cylinders in vertical and inclined arrangements. Rigid test cylinders were mounted on a single degree of freedom elastic support. The inclination angles examined were θ=0°, ±20° and ±45°. The Reynolds number ranged from 4000 to 45000 and the reduced velocity from 1 to 16. With all tests the mass ratio and the mass-damping parameters were kept constant.
Test results on “inclined bare” and “inclined helically straked” cylinders showed that the peak amplitude of the cross-flow oscillations decreased as the inclination angle increased. The suppression ratio remained almost the same with the vertical and inclined cylinders. The validity of the so called “Independence Principle” (IP) was also examined against the test data obtained in the current study. The IP, to some degrees, was valid in the case of “inclined bare” cylinders. In the case of “inclined helically straked” cylinders, the IP outcomes were almost entirely inconsistent with actual test data. In addition, the up- and downstream effects on the VIV response of the inclined bare and helically straked cylinders were discussed. Hilbert Transform of the VIV responses showed that it was able to efficiently discriminate signals belonging to the lock-in, initial and lower branches of the response.
•In-water small scale towing-tank experiments in a uniform flow were conducted.•Effects of helical strakes on the dynamics of the VIV in inclined cylinders were studied.•The suppression ratio remained almost the same with different inclination angles.•The "Independence Principle" (IP), was partly valid in the case of bare cylinders.
•The IP was almost entirely invalid in the case of helically straked cylinders.
Non-ribosomal peptide synthetases (NRPSs) assemble metabolites of medicinal and commercial value. Both serine and threonine figure prominently in these processes and separately can be converted to ...the additional NRPS building blocks 2,3-diaminopropionate (Dap) and 2,3-diaminobutyrate (Dab). Here we bring extensive bioinformatics, in vivo and in vitro experimentation to compose a unified view of the biosynthesis of these widely distributed non-canonical amino acids that both derive by pyridoxal-mediated β-elimination of the activated O-phosphorylated substrates followed by β-addition of an amine donor. By examining monobactam biosynthesis in Pseudomonas and in Burkholderia species where it is silent, we show that (2S,3R)-Dab synthesis depends on an l-threonine kinase (DabA), a β-replacement reaction with l-aspartate (DabB) and an argininosuccinate lyase-like protein (DabC). The growing clinical importance of monobactams to both withstand Ambler Class B metallo-β-lactamases and retain their antibiotic activity make reprogrammed precursor and NRPS synthesis of modified monobactams a feasible and attractive goal.
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•DabABC operons in natural product and monobactam BGCs biosynthesize (2S,3R)-Dab•Presence of the dabABC operon differentiates C4-methylated monobactam BGCs•Dual functions of DabB and DabC give (2S,3R)-Dab or l-Dap with/without l-Thr kinase•Results enable the enzymatic production of further functionalized Dap and Dab analogs
Chemistry
Repair welds are frequently used to fix defects in the manufacturing process, remedy in-service degradations, and for the life extension of ageing steel components and pressure vessels. Nevertheless, ...repair welds may exert detrimental impacts on the integrity of these structures in the long term. The primary focus of the current study is on the vee-and-weld repairs made in girth welds of steel pipes/components. The subject has not been the focal point for previous researchers. The hysteresis responses of specimens with original welds, partial and full repair welds and repeated repair welds were studied. Specimens with full repair welds featured apparent strain softening under strain cycling. Specimens with original or partial repair welds demonstrated a relatively stable strain cycling behaviour. Under stress cycling, the repair welding accelerated the strain ratcheting and reduced the number of cycles to failure. The effects varied depending on the extent of the repair (full or partial) and its repetition (single or double).
Four groups of the series of rare earth (RE) substituted cobalt ferrite Co1−x REx Fe2 O4; x = 0–0.2 in steps of 0.05 and RE is Nd and Eu were prepared using the sol–gel method at annealing ...temperatures 550° C. The materials were characterized by powder X-ray Diffraction (XRD), Field Emission Scanning Electron Microscopes (FESEM) and Fourier Transform Infrared spectroscopy (FTIR). The phase identification of the materials by XRD reveals the single-phase nature of the materials. The crystallite sizes of the materials were varied by altering the substitution content within the range of a minimum of 11 nm–31 nm. The magnetic parameters have been studied by using vibrating sample magnetometer (VSM). The saturation magnetization of the ferrite materials at room temperature decreases with the reduction of size. This has been attributed to increased surface to volume ratio and spin canting phenomena. The substituted rare-earth ions inhibit the grain growth of the materials in a systematic manner compared with that of the pure cobalt ferrite materials. There is an improvement in coercivities of the rare earth substituted cobalt ferrite especially for 5% Neodymium substituted cobalt ferrite with approximately 2 kOe coercive field. This is attributed to the contribution from the single ion anisotropy of the rare-earth ions present in the crystal lattice and the effects of a change in magnetic structures on the surface of the nanoparticles.
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•Nanostructured rare earth doped Co-ferrite particles were synthesized by sol–gel.•The coercivity of as high as 2 kOe is achieved for 5% substituted cobalt ferrite.•The saturation magnetization is decreasing by increasing Nd3+ substitution content.•Obtained nanoparticles are single-domain particles.
The carbapenem family of β-lactam antibiotics displays a remarkably broad spectrum of bactericidal activity, exemplified by meropenem's phase II clinical trial success in patients with pulmonary ...tuberculosis, a devastating disease for which β-lactam drugs historically have been notoriously ineffective. The discovery and validation of l,d-transpeptidases (Ldts) as critical drug targets of bacterial cell-wall biosynthesis, which are only potently inhibited by the carbapenem and penem structural classes, gave an enzymological basis for the effectiveness of the first antitubercular β-lactams. Decades of study have delineated mechanisms of β-lactam inhibition of their canonical targets, the penicillin-binding proteins; however, open questions remain regarding the mechanisms of Ldt inhibition that underlie programs in drug design, particularly the optimization of kinetic behavior and potency. We have investigated critical features of mycobacterial Ldt inhibition and demonstrate here that the covalent inhibitor meropenem undergoes both reversible reaction and nonhydrolytic off-loading reactions from the cysteine transpeptidase Ldt
through a high-energy thioester adduct. Next-generation carbapenem optimization strategies should minimize adduct loss from unproductive mechanisms of Ldt adducts that reduce effective drug concentration.
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