CONTRIBUTION OF UFA SCIENTISTS TO THE CHEMISTRY OF OPTICALLY ACTIVE SEX PHEROMONE OF PINE SAWFLIES

Pine sawflies of the genera Neodiprion, Diprion and Gilpinia (Diprionidae) are malignant and economically important pests of coniferous trees. The most effective and environmentally safe method of controlling and regulating the number of pine sawflies is the use in traps of synthetically obtained sex feromone, identified for its different species as acetates and propionates of 3,7-dimethyl-2-pentadecan-2-ol (diprionol) in the form of various stereoisomeric forms due to the presence of three asymmetric carbon atoms. At the same time, it was noted that the 2S configuration of the optical centre of the erythro-isomerium is crucial for the stereochemistry of the sex pheromone of pine sawflies. The article presents the results of research of the laboratory of insect bioregulators of the Ufa Institute of chemistry of the UFIC RAS in the field of synthesis of optically active pine Sawfly pheromone, its stereoisomers and analogues based on (S)-(+)-dihydromircene and (-)-mentolactone obtained from available natural monoterpenes – (+)-α-pinene and l-menthol, respectively.

Close-up view of an ongoing merger between the NGC 4839 group and the Coma cluster – a post-merger scenario

ABSTRACT We study a merger of the NGC 4839 group with the Coma cluster using X-ray observations from the XMM–Newton and Chandra telescopes. X-ray data show two prominent features: (i) a long (∼600 kpc in projection) and bent tail of cool gas trailing (towards south-west) the optical centre of NGC 4839, and (ii) a ‘sheath’ region of enhanced X-ray surface brightness enveloping the group, which is due to hotter gas. While at first glance the X-ray images suggest that we are witnessing the first infall of NGC 4839 into the Coma cluster core, we argue that a post-merger scenario provides a better explanation of the observed features and illustrate this with a series of numerical simulations. In this scenario, the tail is formed when the group, initially moving to the south-west, reverses its radial velocity after crossing the apocenter, the ram pressure ceases and the ram pressure-displaced gas falls back towards the centre of the group and overshoots it. Shortly after the apocenter passage, the optical galaxy, dark matter, and gaseous core move in a north-east direction, while the displaced gas continues moving to the south-west. The ‘sheath’ is explained as being due to interaction of the re-infalling group with its own tail of stripped gas mixed with the Coma gas. In this scenario, the shock, driven by the group before reaching the apocenter, has already detached from the group and would be located close to the famous relic to the south-west of the Coma cluster.

Analysis of readymade readers and near–inter-pupillary distance for presbyopic patients in optometric practice in Cape Town, South Africa

Purpose and background: This study has particular significance in ophthalmic dispensing as well as for optometry when considering the use of readymade readers (RMRs) both in private practice and in the public health sector. This study investigated firstly whether the optical centre (OC) distance for a sample of RMRs correlates with the near–inter-pupillary distance (near-IPD) for presbyopic patients, whether induced prism occurs with convergence when reading and whether RMR lenses are free of optical strain. Methods: Near-IPDs (measured by a single individual) were obtained from record cards of 1080 patients (540 male patients and 540 female patients). The OC distances were determined for 60 RMRs using a Nikon PL-2 screen vertometer, and induced prismatic effects were calculated for vertical and horizontal meridians. The presence of optical strain was analysed and graded using crossed polarised filters (within a polariscope). Results: The measured average near-IPD was 59.04 mm (s.d. ±2.87) for the 540 female patients and 61.59 mm (s.d. ±3.08) for the 540 male patients. The measured average RMR OC distance was 64.49 mm (s.d. ±3.74) for female patients and 62.77 mm (s.d. ±1.57) for male patients. Based on the mean near-IPD and the corresponding RMR OC distance, the average horizontal prismatic effect found in RMRs designed for female patients with induced prism was 0.11 pd base-out (5.06 mm outwards) and 0.04 pd base-in (1.26 mm inwards). For male RMRs, this was 0.03 pd base-out (1.32 mm outwards) and 0.02 pd base-in (1.28 mm inwards). When comparing RMR distances with near-IPDs, t = -7.87, p < 0.001 for female patients and t = -3.69, p < 0.001 for male patients. The average vertical differential prismatic effect for female patients was 0.67 pd and it was 0.68 pd for male patients. Optical strain was observed in 66.67% and 56.67% of RMR lenses for female and male patients, respectively. The strain pattern was found to be most severe in the inferior temporal periphery for 34 RMRs for female patients and for 20 RMRs for male patients, followed by the inferior nasal periphery for 27 and 18 lenses (RMRs) for male and female patients, respectively. Conclusion: Most RMRs were found to be within international standard tolerances for horizontally induced prismatic effects, but 10% of female and 36.67% of male RMRs had vertical prismatic effects, which exceeded international standards. Significant optical strain was found in the inferior nasal reading portion of the RMRs. Keywords: Readymade readers (RMR’s); prismatic effect; strain; interpupillary distance; presbyopia; reading