Flux and fluence dependence of disorder produced during implantation of 11B in silicon

The flux and fluence dependence of disorder produced in silicon during the implantation of ¹¹B has been investigated at room temperature, -50°C. and -120°C. Implantations were carried out with 200 keV ¹¹B ions using current densities in the range from 0.06μA/cm² to 15μA/cm², and the disorder monitored by measuring the energy spectra of backscattered protons which were incident on the sample at 450 keV parallel to a (110) axis. Significant differences in the dependence of the disorder on ¹¹B flux and fluence were observed between the implantations performed at room temperature and those carried out at the two lower temperatures.     

An Efficient Process for the Synthesis of Renin Inhibitor,ABT-517

An efficient process for the preparation of renin inhibitor, ABT-517 is described. The process avoids solvent extractions or chromatographic purifications and is used on multi-kilogram scale.     

Charge Transfer Complexes of 1-Naphthylmethyl Cotton Cellulose

A cotton cellulose derivative that forms charge-transfer complexes was prepared in yarn form. A charge-transfer complex is composed of two partners, one referred to as the donor and the other as an acceptor of electrical charge. In the present investigation, a donor was chemically bound to the cotton. It was shown that the modified donor cellulose adsorbs various acceptors from solution. Celluloses possessing donor or acceptor moieties are potentially useful as chromatographic agents and also in medicinal chemistry where a controlled release of a chemical agent is desired.     

A Total Synthesis of (±)-Trichodiene

Trichodiene (1), a sesquiterpene hydrocarbon, was isolated from the extract of mycelium of Trichothecium roseum. The structure of trichodiene (1) was elucidated by Nozoe and Machida in 1970 via degradation and spectroscopy.¹ Trichodiene (1) has been shown to be the biogenetic precursor of the trichothecane family of sesquiterpenoids as characterized by the cytotoxic fungal metabolite (-)-trichodermin (2).^2,3 The structure and absolute stereochemistry of (-)-trichodermin (2) were determined by X-ray diffraction and, therefore, the structure and absolute stereochemistry of trichodiene (1) are now firmly established.⁴ We wish to report a total synthesis of (±)-trichodiene (1) via previously reported lactone 3.^5,6     

Sterically congested macrobicycles with heteroatomic bridgehead functionality

A series of cyclophanes composed of two triarylelement caps linked by two-atom bridges has been synthesized. The bridgehead functional groups include phosphines in combination with amines, hydrosilanes, methylsilanes, and ethoxysilanes. Computational studies accurately predicted that when the bridgehead substituents are small (lone pairs or protons), an in_,in bridgehead stereochemistry is strongly favored, but larger bridgehead substituents favor the formations of in_,out stereoisomers. The X-ray structures, spectra, and reactivity of these compounds are discussed, as well as the resolution of one of the cyclophanes into pure enantiomers.     

Synthesis and X-Ray Crystal Structure of Methyl D,L-Desmeihyl-Holantosaminide

4-Acetamido-2,4,6-trideoxy-D,L-arabino-hexopyranose, a desmethyl analog of N-acetyl-L-hoTantosamine, the glycosidic residue of the cardenolide HoTarosine A and holantosines C and D, has been prepared via a novel intramolecular rearrangement of an amino alcohol and has been characterized by single-crystal X-ray diffraction.     

Catalyst free,base free microwave irradiated synthesis of aryl nitrites from potassium aryltrifluoroborates and bismuth nitrate

A mixture of bismuth nitrate pentahydrate and potassium aryltrifluoroborate in toluene under microwave heating at 120 °C for 20 min provides an interesting and mild reaction protocol for the synthesis of aryl nitrite. The conversion to aryl nitrites from aryltrifluoroborates without transition metal catalyst and base in high yields is remarkable.     

Effect of Shear Displacement and Stress Changes on Fracture Hydraulic Aperture and Flow Anisotropy

Transport in Porous Media - Fluid flow in fractures has the potential to drastically change the economic, environmental, and safety risks associated with a subsurface operation. This work focuses...     

Mass Activated Droplet Sorting (MADS) Enables High‐Throughput Screening of Enzymatic Reactions at Nanoliter Scale

Microfluidic droplet sorting enables the high‐throughput screening and selection of water‐in‐oil microreactors at speeds and volumes unparalleled by traditional well‐plate approaches. Most such systems sort using fluorescent reporters on modified substrates or reactions that are rarely industrially relevant. We describe a microfluidic system for high‐throughput sorting of nanoliter droplets based on direct detection using electrospray ionization mass spectrometry (ESI‐MS). Droplets are split, one portion is analyzed by ESI‐MS, and the second portion is sorted based on the MS result. Throughput of 0.7 samples s^?1 is achieved with 98 % accuracy using a self‐correcting and adaptive sorting algorithm. We use the system to screen ≈15 000 samples in 6 h and demonstrate its utility by sorting 25 nL droplets containing transaminase expressed in vitro. Label‐free ESI‐MS droplet screening expands the toolbox for droplet detection and recovery, improving the applicability of droplet sorting to protein engineering, drug discovery, and diagnostic workflows.