489 research outputs found
Метод экспертных оценок в лингводидактике
Рассматривается использование метода экспертных оценок как в общей системе научно-педагогической экспертной деятельности, так и в рамках ее лингводидактического аспекта. Дается характеристика процедуры проведения экспертизы, а также оценивается перспективность обращения к интеллектуальным компьютерным системам как инструментам экспертного анализа
Intrapancreatic accessory spleen
A case of accessory spleen located in the tail of the pancreas in a stillbirth male foetus is reported. The congenital anomaly was revealed at autopsy. The intrapancreatic
spleen was well demarcated and was composed of red and white pulp; however, same pancreatic ducts were intermingled with the splenic parenchyma. As well as the intrapancreatic lesion another minute accessory spleen was also found at the hilum of the proper organ. Since a lack of morphological features of trisomy 13 syndrome were found in the foetus, the ectopic spleens were regarded as incidental findings
Gallic acid
Anhydrous 3,4,5-trihydroxybenzoic acid, C7H6O5, is essentially planar, with its non-H atoms exhibiting mean and maximum deviations from coplanarity of 0.014 and 0.0377 (5) Å, respectively. The C—C—C—OH torsion angle about the bond linking the carboxyl group to the benzene ring is −0.33 (10)°. In the crystal, the –COOH groups form centrosymmetric hydrogen-bonded cyclic dimers [graph set R
2
2(8)] and the phenolic –OH groups participate in both intra- and intermolecular hydrogen bonds, forming a three-dimensional network structure
Hoodigogenin A from Hoodia gordonii
The title molecule (systematic name: 12-O-β-tigloyl-3β,14β-dihydroxypregn-5-en-20-one), C26H38O5, isolated from aerial parts of Hoodia gordonii, has its steroid A and C rings in chair conformations, its B ring in a half-chair conformation, and its five-membered ring in an envelope conformation. The OH group at the C/D ring junction forms an intramolecular hydrogen bond with the keto substituent. The OH group on the A ring forms an intermolecular hydrogen bond with the tiglate C=O group, propagating [010] chains in the crystal structure
3,6,9,16,19,22-Hexaazatricyclo[22.2.2.211,14]triaconta-1(27),11 (30),12,14(29),24(28),25-hexaene hexakis(p-toluenesulfonate) dihydrate
In the title compound, C24H44N6
6+·6C7H7O3S−·2H2O, the macrocycle crystallizes in its hexaprotonated form, accompanied by six p-toluenesulfonate ions and two water molecules, and lies on an inversion center. The three independent p-toluenesulfonate anions and their inversion equivalents at (1 − x, 1 − y, 1 − z) are linked to the macrocyclic cation through N—H⋯O hydrogen bonds. Of these, two p-toluenesulfonate ions are located on opposite sides of the macrocyclic plane and are linked to bridgehead N atoms via N—H⋯O hydrogen bonds. The remaining four p-toluenesulfonate ions bridge two adjacent macrocyclic cationic units through N—H⋯O hydrogen bonding involving other N atoms, forming a chain along the a axis. The water molecules, which could not be located and may be disordered, do not interact with the macrocycle; however, they form hydrogen bonds with anions
Crystal science fundamentals
The fundamentals of crystal science notably crystallography, crystal chemistry, crystal defects, crystal morphology and the surface chemistry of crystals are introduced with particular emphasis on organic crystals
Impact Of Sleep Restriction And Recovery On Motivation During Repeated Cognitive Performance Testing
Introduction: Both motivation and sleep deprivation affect cognitive performance. Especially during long-lasting studies with repeated cognitive performance tasks there is concern that subjects will lose motivation over time. Results may be confounded due to changes in motivation.
Methods: In an ongoing study, 29 healthy volunteers performed 55 cognitive performance tasks at three-hourly intervals in a 12-day inpatient study. After two baseline nights with 8 h time in bed (TIB) the intervention group (N=20; mean age 26 ± 4 years, 9 females) underwent chronic sleep restriction for 5 nights (5 h TIB) with a following recovery night of 8 h TIB. The control group (N=9; mean age 25 ± 5 years, 3 females) had the opportunity to sleep 8 hours every night. Participants completed the Karolinska Sleepiness Scale (KSS) and a questionnaire about their motivation (from 1=very little/not motivated to 5=very motivated) at 6 p.m. on all days.
Results: Wilcoxon signed-rank tests showed a significant decrease in motivation (p=.0439) and a significant increase in subjective sleepiness (p=.0184) from baseline (motivation: 2.8 ± 0.6 (SD), sleepiness: 3.2 ± 1.2) to the last day of chronic sleep restriction (motivation: 2.2 ± 0.5, sleepiness: 5.1 ± 1.8) for the experimental group. Motivation remained low after recovery sleep (2.2 ± 0.8; p=.0198). Sleepiness and motivation scores showed a significant Spearman correlation (r=-0.43, p<0.001).
Discussion: Chronic sleep restriction for five days leads to an increase in sleepiness and a decrease in motivation. One night of recovery is insufficient to reverse the motivation loss, contrasting with the beneficial effect on sleepiness. During chronic sleep restriction conditions subjective motivation seems to decrease as a function of subjective sleepiness
4-(8-Ethoxy-2,3-dihydro-1H-cyclopenta[c]quinolin-4-yl)butane-1-peroxol
In the title molecule, C18H23NO3, the hydroperoxybutyl substituent is nearly fully extended, with the four torsion angles in the range 170.23 (10)–178.71 (9)°. The O—O distance in the hydroperoxide group is 1.4690 (13) Å. This group acts as an intermolecular hydrogen-bond donor to a quinoline N atom. This results in dimeric units about the respective inversion centers, with graph-set notation R
2
2(18)
3-(Trimethylsilyl)prop-2-ynyl p-toluenesulfonate
In the title compound, C13H18O3SSi, the SO3 group displays a partial rotational (ca 50°) disorder about the C—S bond, with relative proportions 0.7744 (13):0.2256 (13). This disorder also forces the propynyl CH2 group to be disordered
The first oxazoline adduct of Zn(acac)2: bis(acetylacetonato-κ2 O,O′)(2-phenyl-2-oxazoline-κN)zinc(II)
The title material, [Zn(C5H7O2)2(C9H9NO)], was synthesized by the treatment of bis(acetylacetonato)zinc(II) monohydrate with 2-phenyl-2-oxazoline. The Zn atom is coordinated by two chelating acetylacetonate groups and one oxazoline ligand in the apical position of a slightly distorted square-pyramidal metal–ligand geometry
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