Stereoselective syntheses of isomers of 3,7-dimethylnonadecane, a sex pheromone of the alfalfa blotch leafminer (Agromyza frontella (Rondani))

1991 ◽  
Vol 69 (7) ◽  
pp. 1100-1106 ◽  
Author(s):  
David Miller ◽  
François Bilodeau ◽  
Robert H. Burnell
Keyword(s):  
Optical Properties ◽  
Sex Pheromone ◽  
Key Words ◽  
Stereoselective Synthesis ◽  
Starting Material ◽  
The Other ◽  
Stereogenic Center ◽  
Stereoselective Syntheses ◽  
Alfalfa Blotch Leafminer ◽  
Agromyza Frontella

Two related stereoselective syntheses of 3,7-dimethylnonadecane, a sex pheromone of the alfalfa leafminer, are described to show that pulegone can serve as a useful starting material for the preparation of chiral aliphatic isoprenoid compounds. The schemes are designed to place the stereogenic center of pulegone at C.3 in one synthesis and at C.7 in the other so that the optical properties of the products can be compared with one another and with the values calculated using Brewster's rules. Key words: chiral hydrocarbons, stereoselective synthesis, pheromone, Agromyza frontella.

Identification of female sex pheromone in alfalfa blotch leafminer,Agromyza frontella (Rondani)(Diptera: Agromyzidae)

1988 ◽  
Vol 14 (3) ◽  
pp. 947-956 ◽  
Author(s):  
Yves Carri�re ◽  
Jocelyn G. Millar ◽  
Jeremy N. McNeil ◽  
David Miller ◽  
E. W. Underbill
Keyword(s):  
Sex Pheromone ◽  
Female Sex Pheromone ◽  
Female Sex ◽  
Alfalfa Blotch Leafminer ◽  
Agromyza Frontella

scholarly journals Stereoselective synthesis of trans-fused iridoid lactones and their identification in the parasitoid wasp Alloxysta victrix, Part I: Dihydronepetalactones

2012 ◽  
Vol 8 ◽  
pp. 1246-1255 ◽  
Author(s):  
Nicole Zimmermann ◽  
Robert Hilgraf ◽  
Lutz Lehmann ◽  
Daniel Ibarra ◽  
Wittko Francke
Keyword(s):  
Mass Spectrometry ◽  
Stereoselective Synthesis ◽  
Minor Component ◽  
Parasitoid Wasp ◽  
The Other ◽  
Enantiomerically Pure ◽  
Enantioselective Gas Chromatography ◽  
A Minor ◽  
Stereogenic Center ◽  
Reference Samples

Starting from the enantiomers of limonene, all eight stereoisomers of trans-fused dihydronepetalactones were synthesized. Key compounds were pure stereoisomers of 1-acetoxymethyl-2-methyl-5-(2-hydroxy-1-methylethyl)-1-cyclopentene. The stereogenic center of limonene was retained at position 4a of the target compounds and used to stereoselectively control the introduction of the other chiral centers during the synthesis. Basically, this approach could also be used for the synthesis of enantiomerically pure trans-fused iridomyrmecins. Using synthetic reference samples, the combination of enantioselective gas chromatography and mass spectrometry revealed that volatiles released by the endohyperparasitoid wasp Alloxysta victrix contain the enantiomerically pure trans-fused (4R,4aR,7R,7aS)-dihydronepetalactone as a minor component, showing an unusual (R)-configured stereogenic center at position 7.

Practical Correction of Three Fold Astigmatism in the Philips CM TEM

1996 ◽  
Vol 54 ◽  
pp. 418-419
Author(s):  
Arno J. Bleeker ◽  
Mark H.F. Overwijk ◽  
Max T. Otten
Keyword(s):  
Optical Properties ◽  
Phase Contrast ◽  
The Other ◽  
Objective Lens ◽  
Symmetric Part ◽  
A Posteriori ◽  
Contrast Transfer Function ◽  
High Brightness ◽  
Rotationally Symmetric ◽  
Brightness Field

With the improvement of the optical properties of the modern TEM objective lenses the point resolution is pushed beyond 0.2 nm. The objective lens of the CM300 UltraTwin combines a Cs of 0. 65 mm with a Cc of 1.4 mm. At 300 kV this results in a point resolution of 0.17 nm. Together with a high-brightness field-emission gun with an energy spread of 0.8 eV the information limit is pushed down to 0.1 nm. The rotationally symmetric part of the phase contrast transfer function (pctf), whose first zero at Scherzer focus determines the point resolution, is mainly determined by the Cs and defocus. Apart from the rotationally symmetric part there is also the non-rotationally symmetric part of the pctf. Here the main contributors are not only two-fold astigmatism and beam tilt but also three-fold astigmatism. The two-fold astigmatism together with the beam tilt can be corrected in a straight-forward way using the coma-free alignment and the objective stigmator. However, this only works well when the coefficient of three-fold astigmatism is negligible compared to the other aberration coefficients. Unfortunately this is not generally the case with the modern high-resolution objective lenses. Measurements done at a CM300 SuperTwin FEG showed a three fold-astigmatism of 1100 nm which is consistent with measurements done by others. A three-fold astigmatism of 1000 nm already sinificantly influences the image at a spatial frequency corresponding to 0.2 nm which is even above the point resolution of the objective lens. In principle it is possible to correct for the three-fold astigmatism a posteriori when through-focus series are taken or when off-axis holography is employed. This is, however not possible for single images. The only possibility is then to correct for the three-fold astigmatism in the microscope by the addition of a hexapole corrector near the objective lens.

HISTOPATHOLOGY OF THE PIGMENTED TUMORAL-LIKE LESIONS OF THE SKIN AT HUE HOSPITAL OF MEDICINE AND PHARMACY UNIVERSITY

2018 ◽  
Vol 8 (4) ◽  
pp. 65-69
Author(s):  
Mao Nguyen Van ◽  
Dong Tran Nam
Keyword(s):  
Key Words ◽  
Definitive Diagnosis ◽  
The Other ◽  
Cell Tumour ◽  
Cross Sectional ◽  
Skin Tumour ◽  
Clinical Appearance ◽  
The Face ◽  
The Common ◽  
Difficult Cases

Background: Pigmented tumour of the skin is one of the common tumour in human including the benign pigmented tumours (more common) called Nevi tumours and the malignant one called melanoma which was less frequent but the most poor in prognosis. In addition, the others not belonging to these group had the same clinical appearance, so the application of histopathology and immunohistochemistry for the definitive diagnosis was indespensible. Objectives: 1. To describe the macroscopic features of the pigmented tumoral-like lesions; 2. To classify the histopathologic types of the pigmented cell tumours and the other pigmented tumours of the skin. Materials and Method: Cross-sectional research on 55 patients diagnosed as pigmented tumoral lesions by clinician, then all definitively diagnosed by histopathology combining the immunohistochemistry in difficult cases. Results: There was no difference in gender, the disease was discovered most common in adult, especially with the age over 51 years old (58.1%). the most region located was in the face accounting for 60%, following the trunk and limbs (14.6%, 12.8% respectively). All 3 malignant melanomas happened in foot. The most common color of the lesions was black (65.4%), the other ones were rose, grey and blue. Histopathology and immunohisthochemistry showed that the true pigmented cell tumours were 52.6% encompassing benign ones (Nevi tumour) (41.8%), melanoma (5.4%) and lentigo (5.4%). 47.4% was not the true pigmented cell tumour including pigmented basocellular carcinoma (36.4%) and the others less common as histiofibromas, acanthoma and papilloma. Conclusion: the pigmented tumoral-like lesions of the skin could be the true pigmented cell tumours and the others, so the application of the histopathology and the immunohistochemistry after the clinical discovery helps to determine and classify the disease definitely and for the best orientation of treatment as well. Key words: skin tumour, benign pigmented tumour (Nevi), malignant pigmented tumour (melanoma), pigmented basocellular carcinoma

scholarly journals Effect of seed treatment and foliar spray with fungicides in controlling black point disease of wheat

1970 ◽  
Vol 34 (3) ◽  
pp. 425-434 ◽  
Author(s):  
PK Malaker ◽  
IH Mian
Keyword(s):  
Economic Analysis ◽  
Grain Yield ◽  
Key Words ◽  
Seed Weight ◽  
Seed Treatment ◽  
Foliar Spray ◽  
The Other ◽  
Gross Margin ◽  
Black Point ◽  
Wheat Seeds

The efficacy of seed treatment and foliar spray with fungicides in controlling black point incidence of wheat seeds was evaluated in the field. Two seed treating fungicides, namely Vitavax-200 and Homai-80WP were used @ 0.25% of dry seed weight and foliar spray with Tilt-250EC (0.05%) was applied in six different schedules. Untreated and unsprayed controls were also maintained. Seed treatment with either Vitavax-200 or Homai-80WP significantly increased plant population and grain yield, but none of them was found effective in reducing black point incidence. On the other hand, foliar sprays with Tilt-250EC under all the spray schedules except spraying at 70 and 90 DAS significantly minimized the disease severity over unsprayed control. Among the different spray schedules, spraying at 30, 40, 50, 60, 70, 80, and 90 DAS appeared to be most effective, which was similar to spraying at 30, 45, 60, 75, and 90 DAS in reducing black point incidence and increasing grain yield. Economic analysis on yield advantage showed that the highest additional gross margin of Tk. 6120/ha with BCR 2.57 was obtained from five sprays applied at 30, 45, 60, 75, and 90 DAS. Key Words: Seed treatment, foliar spray, black point, wheat. DOI: 10.3329/bjar.v34i3.3968 Bangladesh J. Agril. Res. 34(3) : 425-434, September 2009

Stereoselective Synthesis of Insect Sex Pheromone Analogues Having a Fluorine Atom on Their Double Bonds.

ChemInform ◽  
2005 ◽  
Vol 36 (50) ◽  
Author(s):  
Tong Guan ◽  
Masanori Yoshida ◽  
Daisuke Ota ◽  
Tsuyoshi Fukuhara ◽  
Shoji Hara
Keyword(s):  
Sex Pheromone ◽  
Fluorine Atom ◽  
Stereoselective Synthesis ◽  
Double Bonds ◽  
Insect Sex Pheromone ◽  
Insect Sex

Structural effects on chemo- and enantioselectivity of Candida antarctica lipase B - Resolution of β-amino esters

2002 ◽  
Vol 80 (6) ◽  
pp. 565-570 ◽  
Author(s):  
Szilvia Gedey ◽  
Arto Liljeblad ◽  
László Lázár ◽  
Ferenc Fülöp ◽  
Liisa T Kanerva
Keyword(s):  
Key Words ◽  
Candida Antarctica ◽  
Diisopropyl Ether ◽  
The Other ◽  
Candida Antarctica Lipase B ◽  
Candida Antarctica Lipase ◽  
Structural Effects ◽  
Lipase B ◽  
Amino Esters ◽  
Catalyzed Reactions

The Candida antarctica lipase B-catalyzed reactions of five β-amino esters with neat butyl butanoate and with 2,2,2-trifluoroethyl butanoate in diisopropyl ether were studied, as were the reactions of the same β-amino esters and their N-butanamides with neat butanol. The possibility for sequential resolution, where the amino and ester functions of the substrate both react with an achiral butanoate, became less likely with increasing size of the substrate from ethyl 3-aminobutanoate (1a) to pentanoate (1b) or larger. On the other hand, the alcoholyses of N-acylated β-amino esters successfully proceeded in butanol with E > 100. Gram-scale resolution of the N-butanoylated 1a was performed to demonstrate the usefulness of the method. Key words: lipase, interesterification, acylation, alcoholysis, resolution, β-amino esters.

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