Synthesis,asymmetric aldol reactions,and x‐ray crystallography of some oxadiazinanone derivatives

A series of N₄‐substituted oxadiazinanones have been synthesized from (1R,2S)‐norephedrine by a process of either reductive alkylation or arylation, N‐nitrosation, reduction and cyclization. These derivatives (R = ‐CH₂Ph, ‐CH₂C(CH₃)₃, ‐cyclo‐C₆H₁₁, ‐C₆H₅) have been acylated with propanoyl chloride and employed in the asymmetric Aldol reaction. The observed diastereoselectivities for the formation of the “non‐Evans” syn‐adduct ranged from 88:12 to 99:1. The hydrolysis of the Aldol adducts varied with the nature of the nitrogen substituent.     

Broadband noise prediction when turbulence simulation is available—Derivation of Formulation 2B and its statistical analysis

We show that a simple modification of Formulation 1 of Farassat results in a new analytic expression that is highly suitable for broadband noise prediction when extensive turbulence simulation is available. This result satisfies all the stringent requirements, such as permitting the use of the exact geometry and kinematics of the moving body, which we have set as our goal in the derivation of useful acoustic formulas for the prediction of rotating blade and airframe noise. We also derive a simple analytic expression for the autocorrelation of the acoustic pressure that is valid in the near and far fields. Our analysis is based on the time integral of the acoustic pressure that can easily be obtained at any resolution for any observer time interval and digitally analyzed for broadband noise prediction. We have named this result as Formulation 2B of Farassat. One significant consequence of Formulation 2B is the derivation of the acoustic velocity potential for the thickness and loading terms of the Ffowcs Williams–Hawkings (FW-H) equation. This will greatly enhance the usefulness of the Fast Scattering Code (FSC) by providing a high-fidelity boundary condition input for scattering predictions.     

S-band low noise amplifier using 1μm InGaAs/InAlAs/InP pHEMT

正This paper discusses the design of a wideband low noise amplifier(LNA) in which specific architecture decisions were made in consideration of system-on-chip implementation for radio-astronomy applications.The LNA design is based on a novel ultra-low noise InGaAs/InAlAs/InP pHEMT.Linear and non-linear modelling of this pHEMT has been used to design an LNA operating from 2 to 4 GHz.A common-drain in cascade with a common source inductive degeneration,broadband LNA topology is proposed for wideband applications.The proposed configuration achieved a maximum gain of 27 dB and a noise figure of 0.3 dB with a good input and output return loss(S_(11)—10 dB,S_(22)—11 dB).This LNA exhibits an input 1-dB compression point of-18 dBm,a third order input intercept point of 0 dBm and consumes 85 mW of power from a 1.8 V supply.     

Improved tau polarisation measurement

Using 22 pb⁻¹ of data collected at LEP in 1992 on the peak of the Z resonance, the ALEPH collaboration has measured the polarisation of the tau leptons decaying into ,πν, ρν and a₁ ν from their individual decay product distributions. The measurement of the tau polarisation as a function of the production polar angle yields the two parametersN _τ andN _e, where, in terms of the axial and vector couplingsg _Al andg _Vl,N _l=2g _Vl g_Al/(g _Vl ² +g _Al ² ). This analysis follows to a large extent the methods devised for the 1990 and 1991 data but with improvements which bring a better understanding of the systematic uncertainties. Combining the 1992 measurements with our previously published results yieldsN _τ=0.136±0.012±0.009 andN _e=0.129±0.016±0.005. Assuminge−τ universality, the measurements imply an effective weak mixing angle of sin ² θ _W ^eff =0.2332±0.0014. Deceased     

Ein einfaches Tabellensystem zur Zuordnung von Bruttoformeln zu Massenwerten aus hochaufgel?sten Massenspektren organischer Verbindungen

Zusammenfassung Es wird ein Tabellensystem vorgestellt, mit dem die Zuordnung von Bruttoformeln, zu Massenwerten aus hochaufgelösten Massenspektren organischer Verbindungen möglich ist. Massentabellen nach dem beschriebenen System sind sehr einfach zu benutzen und haben nur sehr geringen Umfang. Auf 8 Seiten hat eine Tabelle Platz, welche die Massen von Bruttoformeln für alle Kombinationen von C, H, N, O mit maximal 5 Stickstoff- und 8 Sauerstoffatomen enthÄlt und, je nach C/H-VerhÄltnis, bis zu Massenzahlen zwischen 600 und 800 reicht. Der geringe Umfang erlaubt es, spezielle Tabellen, welche z.B. Chlor-, Brom-, Metall- oder sonstige Heteroatome enthalten, mit Hilfe einer Tischrechenmaschine selbst herzustellen. Die Berücksichtigung einzelner Heteroatome, welche in der Tabelle nicht enthalten sind, ist durch einfache Zusatzrechnung möglich. Ein Ausschnitt aus einer Tabelle mit Anleitung zur Benutzung ist beigefügt.

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Summary A system is presented for tabulating masses which permits coordination of precise masses resulting from high-resolution mass spectra of organic compounds to elemental composition of ions.The main advantage of the system is the small size and the easy way of handling the table. A table consisting of no more than 8 pages includes for instance all C, H, N, O combinations up to 5 nitrogen and 8 oxygen atoms extending to mass number 600–800 depending on the C/H ratio.By means of a desk-calculator a table can be easily set up for usually not tabulated atoms like chlorine, bromine, metals and so on. Single heteroatoms which are not included in a table can be taken into account by a simple calculation. A section of a table and an instruction for use is added.

     

Allyl group as a protecting group for internucleotide phosphate and thiophosphate linkages in oligonucleotide synthesis: facile oxidation and deprotection conditions

[reaction: see text] The allyl group, which serves as a protecting group for an internucleotide bond for both phosphates and phosphorothioates, can be easily removed by good nucleophiles under weakly basic or neutral conditions. For a practical synthesis on solid support, camphorsulfonyloxaziridine was used as the oxidizing agent for synthesizing DNA, while the Beaucage reagent was used for preparing phosphorothioate oligomers. Both types of oligonucleotides were easily deprotected by concentrated ammonium hydroxide containing 2% mercaptoethanol.     

Core–Shell Structured Chitosan-Polyethylenimine Nanoparticles for Gene Delivery: Improved Stability,Cellular Uptake,and Transfection Efficiency

The delivery of nucleic acids relies on vectors that condense and encapsulate their cargo. Especially nonviral gene delivery systems are of increasing interest. However, low transgene expression levels and limited tolerability of these systems remain a challenge. The improvement of nucleic acid delivery using depolymerized chitosan–polyethylenimine DNA complexes (dCS-PEI/DNA) is investigated. The secore complexes are further combined with chitosan-based shells and functionalized with polyethylene glycol (PEG) and cell penetrating peptides. This modular approach allows to evaluate the effect of functional shell components on physicochemical particle characteristics and biological effects. The optimized ternary complex combines a core-dCS-linear PEI/DNA complex with a shell consisting of dCS-PEG-COOH, which results in improved nucleic acid encapsulation, cellular uptake and transfection potency in human hepatoma HuH-7cells and murine primary hepatocytes. Effects on transgene expression are confirmed in wild-type mice following retrograde intrabiliary infusion. After administration of only 100 ng complexed DNA, ternary complexes induced a high reporter gene signal for three days. It is concluded that ternary coreshell structured nanoparticles comprising functionalized chitosan can be used for in vitro andin vivo gene delivery.