Palladium on Carbon-Catalyzed Cross-Coupling of Aryl Halides with Potassium p-Tolyltrifluoroborate in Air

Palladium supported on carbon (Pd/C) has been shown to be an effective catalyst for the cross-coupling of potassium p-tolyltrifluoroborate with a variety of aryl bromides and iodides. Yields ranging from moderate to good were obtained using Pd/C in ethanol/water mixtures with potassium carbonate as base at 50 °C under an air atmosphere.     

Diverted total synthesis of falcitidin acyl tetrapeptides as new antimalarial leads

We report not only the convergent total synthesis of falcitidin, a natural inhibitor of falcipain-2 from myxobacterium Chitinophaga, but also its diversification into a new antimalarial class of N-acyl tetrapeptides (Acyl-His-Ile-Val-Pro-NH₂). Despite the lack of whole-cell activity of falcitidin itself, our study led to the identification of a trifluoromethyl (CF₃) analogue displaying sub-micromolar IC₅₀ activity against Plasmodium falciparum 3D7 in a standard blood-cell assay, but only when N-tritylated on its histidine (imidazole) residue.     

Selected Thoughts on Hydrophobicity in Drug Design

The fundamental aim of drug design in research and development is to invent molecules with selective affinity towards desired disease-associated targets. At the atomic loci of binding surfaces, systematic structural variations can define affinities between drug candidates and biomolecules, and thereby guide the optimization of safety, efficacy and pharmacologic properties. Hydrophobic interaction between biomolecules and drugs is integral to binding affinity and specificity. Examples of antiviral drug discovery are discussed.     

Novel microwave plasma‐assisted CVD reactor for diamond delta doping

We report on building a novel chemical vapor deposition (CVD) reactor for diamond delta‐doping. The main features of our reactor are: a) the use of rapid gas switching system, (b) the reactor design providing the laminar gas flow. These features provide the creation of ultra‐sharp interfaces between doped and undoped material and minimize the prolonged ”tails” formation in the doping profile. It is proved by optical emission spectroscopy that gas switching time is not more than 10 seconds. Using the novel reactor we have grown the nanometer‐thin layers of boron doped diamond. The FWHM of boron concentration profile is about 2 nm which is proved by SIMS. It is shown that the both single delta‐layer and multiple delta‐layers could be grown using the novel CVD reactor. In principle, the reactor could be used for diamond delta doping with other dopants, like nitrogen, phosphorus etc. (© 2016 WILEY‐VCH Verlag GmbH &Co. KGaA, Weinheim)     

Parallel single-cell optical transit dielectrophoresis cytometer

In this work, we present an optical transit DEP flow cytometer for parallel single-cell analysis. Each cell's dielectric property is inferred from velocity perturbations due to DEP actuation in a microfluidic channel. Dual LED sources facilitate velocity measurement by producing two transit shadows for each cell passing through the channel. These shadows are detected using a 256-pixel linear optical array detector. Massively parallel analysis is possible as each pixel of the detector can independently analyze the passing cells. A wide channel (∼18 mm) was employed to carry many particles simultaneously, and the system was capable of detecting the velocity of over 200 cells simultaneously. We have achieved analysis rates for 10 µm diameter polystyrene spheres response exceeding 250 per second. With appropriate calibration, this DEP cytometer can quantitatively measure the dielectric response. The dielectric response (Clausius–Mossotti factor) of viable CHO cells was measured over the frequency range of 100 kHz to 6 MHz, and the obtained response matches the previously measured values by our group. The DEP cytometer uses simple modular components to achieve high throughput label-free single-cell dielectric analysis and can begin analyzing particles within 10 s after starting to pump the sample into the channel.     

Bioactive Properties and Phenolic Compound Profiles of Turnip-Rooted,Plain-Leafed and Curly-Leafed Parsley Cultivars

Petroselinum crispum Mill., Fuss., is a culinary vegetable used as an aromatic herb that garnishes and flavours a great variety of dishes. In the present study, the chemical profiles and bioactivities of leaf samples from 25 cultivars (three types: plain- and curly-leafed and turnip-rooted) from this species were assessed. Seven phenolic compounds were identified in all the varieties, including apigenin and kaempherol derivates. Apigenin-O-pentoside-O-hexoside was the major compound in all the tested parsley types (20, 22 and 13 mg/g of extract, respectively) and responsible for its excellent antioxidant activity, also investigated in this study. Antimicrobial activities were also explored, and the results revealed a good bioactivity against specific tested pathogens, such as bacteria and fungi. In conclusion, the leaves of all the types of P. crispum are a good source of natural bioactive compounds that confer health benefits, and thus, they should be part of a balanced and diversified diet.     

Direct observations of the leaching of a simulated nuclear waste glass in a radiation environment

The durability of the media proposed for the containment of commercial nuclear waste will be affected not only by the differences in groundwater composition that they might encounter but also by the changes that their own irradiation fields will make to these solutions. Experimental results that question the ability of current leaching experiments to predict the stability of nuclear waste composites are presented.     

A high statistics measurement of the Lambda(+)(c) lifetime

A high statistics measurement of the Lambda(+)(c) lifetime from the Fermilab fixed-target FOCUS photoproduction experiment is presented. We describe the analysis technique with particular attention to the determination of the systematic uncertainty. The measured value of 204.6 +/- 3.4 (stat) +/- 2.5 (syst) fs from 8034 +/- 122 Lambda(+)(c)-->pK(-)pi(+) decays represents a significant improvement over the present world average.     

Formation of paramagnetic mononuclear iron nitrosyl complexes from diamagnetic di- and tetranuclear iron-sulphur nitrosyls: characterisation by EPR spectroscopy and study of thiolate and nitrosyl ligand exchange reactions

The diamagnetic Roussin esters Fe₂(SR)₂(NO)₄ readily underwent exchange with thiols R′SH to yield Fe₂(SR′)₂(NO)₄: the exchange was faster in polar, coordinating solvents where paramagnetic, mononuclear complexes of types [Fe(NO)₂(solvent)₂]⁺ and Fe(NO) ₂(SR)(solvent) were formed. With the corresponding thiolate anions RS^-, the esters Fe₂(SR)₂(NO)₄ formed the mononuclear complexes [Fe(SR)₂(NO)₂]^-, which were fully characterised by EPR spectroscopy for R = H, Me, Et, i-Pr, t-Bu and PhCH₂: assignments of hyperfine couplings were confirmed by use of ¹⁵N. With Fe₂(SR)₂(NO)₄ and a different set of thiolate anion, R′S ^-, in excess, thiol exchange occurred to give [Fe(SR′)₂(NO)₂]^-. A mechanism for formation of Fe₂(SR′)₂(NO)₄ from Fe₂(SR)₂(NO)₄ has been proposed. The paramagnetic mononuclear complexes [Fe(SR)₂(NO)₂] were also readily formed from the diamagnetic clusters [Fe₄S₃(NO)₇]^- and Fe₄S₄(NO)₄, together with [Fe(SR)₃(NO)]^-, and additionally from [Fe(CO)₃NO]^-. [Fe(SMe)₂(NO)₂]^-. was found to be a precursor of isolable Fe₂(SMe)₂(NO)₄, and [Fe(SH)₂ (NO)₂]^- to be the common precursor of both Roussin′s red anion [Fe₂S₂(NO)₄]^- and Roussin's black anion [Fe₄S₃ (NO)₇]^- interconvertible by appropriate adjustment of pH. The nitrosyl groups in these complexes were freely labile, and mononitrosyliron and dinitrosyliron fragments were readily interconvertible: FE(NO) fragments were favoured by the dimethyldithiocarbamate ligand (Me₂NCS ₂) and Fe(NO)₂ fragments by thiolate ligands, RS^-, regardless of the origin of the Fe(NO)_x(x = 1,2) fragment: both mono- and dinitrosyliron complexes persisted with [(i-PrO)₂S₂]^- as ligand. Isotopic labelling showed the occurrence of rapid exchange of nitrogen between nitrosyl ligands and added nitrite in Fe(NO)(S₂CNMe₂)₂ and [Fe(SR)₂(NO)₂]^-