phase sensitive detector described here has two principal applications: a- to produce a d.c out put proportional to- the amplitude of an incoming a,c signal and indicate, by the outut polarity, the phase of the signal with respect to an internal reference. b- to detect the presence of a signal of known phase and frequency which would otherwise be lost in «background noise» and to measure its am...

in this paper a new algorithm is presented for coherent radar detection of targets, when distribution of the interference (clutter and noise) is non-gaussian. the neyman-pearson criterion is used for optimal detection and several successive received samples from a radar range cell are used for detection in the same cell. on the basis of recent empirical evidences, the interference distribution ...

1,N6-Etheno-7-deaza-2,8-diazaadenosine (4) was synthesized from 8-aza-7-deazaadenosine (6) in 64% overall yield. The starting material 6 was obtained by the direct glycosylation of 8-aza-7-deazaadenine (7) with 1-O-acetyl-2,3,5-tri-O-benzoyl-beta-d-ribofuranose (8) (NO2 CH3, BF3 x Et2O; 77% yield). Compound 4 was transformed into 7-deaza-2,8-diazaadenosine (5). The fluorescence of compound 4 sh...

Unlike the facile synthesis of β-monofluoromethyl alcohols by nucleophilic monofluoromethylation of epoxides, the synthesis of β-difluoromethyl alcohols by nucleophilic difluoromethylation of epoxides still remains a challenge. Herein, studies on tackling this problem with PhSO(NTBS)CF2H (2; TBS=tert-butyldimethylsilyl) are reported. The preorganization of 2 and epoxides with BF3⋅Et2O was found...

The spontaneous etching of boron oxide (B2O3) by hydrogen fluoride (HF) gas is important during thermal atomic layer after BCl3 converts the surface various metal oxides to a B2O3 layer. In this study, chemical vapor (CVE) HF was experimentally monitored using Fourier transform infrared (FTIR) spectroscopy and quadrupole mass spectrometry (QMS). also analyzed density functional theory (DFT). fi...

A highly efficient procedure for the preparation of N,N'-alkylidenebisamides in the presence of BF3.SiO2 as a catalyst is described. N,N'-alkylidenebisamides have been prepared via one-pot three-component condensation reaction of various aldehydes and amides. All of the reactions proceeded in high yields and in moderately short reaction times.

Nano-silica supported boron trifluoride (BF3.SiO2) is an efficient, reusable and eco-friendly catalyst for chemoselective thioacetalization of aldehydes and ketones. So, this catalyst was applied for transthioacetalization of acetals and acylals into their corresponding 1,3-dithiolanes or 1,3-dithianes  in good to excellent yields. The reactions were carried out at room temperature under solven...

Conditions enabling the single-step preparative synthesis of chiral 4-fluoropolyhydro-2H-chromenes in good yields through a reaction between monoterpenoid alcohols with para-menthane skeleton and aldehydes were developed for the first time. The BF3·Et2O/H2O system is used both as a catalyst and as a fluorine source. The reaction can involve aliphatic aldehydes as well as aromatic aldehydes cont...