High-frequency coherent edge fluctuations in a high-pedestal-pressure quiescent H-mode plasma

A set of high frequency coherent (HFC) modes (f=80-250 kHz) is observed with beam emission spectroscopy measurements of density fluctuations in the pedestal of a strongly shaped quiescent H-mode plasma on DIII-D, with characteristics predicted for kinetic ballooning modes (KBM): propagation in the ion-diamagnetic drift direction; a frequency near 0.2-0.3 times the ion-diamagnetic frequency; inferred toroidal mode numbers of n～10-25; poloidal wave numbers of k(θ)～0.17-0.4 cm(-1); and high measured decorrelation rates (τ(c)(-1)～ω(s)～0.5×10(6) s(-1)). Their appearance correlates with saturation of the pedestal pressure.     

INTERACTION OF A MODEL EPIDERMAL LIPID WITH A VEGETABLE OIL ADDUCT

A study of the interaction between a model epidermal lipid and 2(alkoyloxy)-1-[(alkoyloxy)methyl]-ethyl-7-(4 heptyl-5,6-dicarboxyl-2-cyclo-hexene-1-yl)heptanoate, (G2) was made by use of small angle X-ray diffraction. The small angle X-ray diffraction pattern of the epidermal lipid model was first compared to the X-ray pattern obtained from human stratum corneum. Increase in the water content of the model epidermal lipid from 32% to 35% caused a shift in the broad diffraction peak from 50-80Å to 50-70Å. No additional shift was found at further addition of water. The addition of G2 to the 32% water model also caused a shift toward smaller interlayer spacing. The effect of G2 was most dramatic for the model epidermal lipid at the lowest water content.     

Enantioselective functionalisation of the C-2' position of 1,2,3,4,5-pentamethylazaferrocene via sparteine mediated lithiation: potential new ligands for asymmetric catalysis

The s-BuLi-sparteine base combination deprotonated the C-2' position of 1,2,3,4,5-pentamethylazaferrocene and subsequent reaction with a range of electrophiles gave C-2 substituted products in 76-93% yield and approximately 80% ee. The products could be recrystallised to enrich ee's to >90%. Resubjection of the initial addition products ( approximately 80% ee) to the deprotonation conditions led to a kinetic resolution to give products with >90% ee and superior overall yields compared to recrystallisation for the cases where the electrophiles were Ph2CO, MeI and Ph2S2. Transmetallation of the 2-lithiopentamethylazaferrocene ( approximately 80% ee) with ZnCl2 allowed palladium catalysed cross coupling with a variety of C-2 haloaryl, heteroaryl and vinyl groups to give some novel C-2' substituted pentamethylazaferrocene derivatives in 61-77% yield in 80% ee. Potential N,N-chelate ligands were recrystallised to >95% ee. A novel C2-symmetric bis-pentamethylazaferrocene could be synthesised by an iron catalysed oxidative coupling of the enatioenriched C-2 lithio derivative and in the presence of a PhMe-Et2O solvent mixture proceeded in 97% ee.     

Structure and collapse of a surface-grown strong polyelectrolyte brush on sapphire

We have used neutron reflectometry to investigate the behavior of a strong polyelectrolyte brush on a sapphire substrate, grown by atom-transfer radical polymerization (ATRP) from a silane-anchored initiator layer. The initiator layer was deposited from vapor, following treatment of the substrate with an Ar/H(2)O plasma to improve surface reactivity. The deposition process was characterized using X-ray reflectometry, indicating the formation of a complete, cross-linked layer. The brush was grown from the monomer [2-(methacryloyloxy)ethyl]trimethylammonium chloride (METAC), which carries a strong positive charge. The neutron reflectivity profile of the swollen brush in pure water (D(2)O) showed that it adopted a two-region structure, consisting of a dense surface region ～100 ? thick, in combination with a diffuse brush region extending to around 1000 ? from the surface. The existence of the diffuse brush region may be attributed to electrostatic repulsion from the positively charged surface region, while the surface region itself most probably forms due to polyelectrolyte adsorption to the hydrophobic initiator layer. The importance of electrostatic interactions in maintaining the brush region is confirmed by measurements at high (1 M) added 1:1 electrolyte, which show a substantial transfer of polymer from the brush to the surface region, together with a strong reduction in brush height. On addition of 10(-4) M oppositely charged surfactant (sodium dodecyl sulfate), the brush undergoes a dramatic collapse, forming a single dense layer about 200 ? in thickness, which may be attributed to the neutralization of the monomers by adsorbed dodecyl sulfate ions in combination with hydrophobic interactions between these dodecyl chains. Subsequent increases in surfactant concentration result in slow increases in brush height, which may be caused by stiffening of the polyelectrolyte chains due to further dodecyl sulfate adsorption.     

Efficient approximation of the dynamics of one-dimensional quantum spin systems

In this Letter we show that an arbitrarily good approximation to the propagator e(itH) for a 1D lattice of n quantum spins with Hamiltonian H may be obtained with polynomial computational resources in n and the error epsilon and exponential resources in |t|. Our proof makes use of the finitely correlated state or matrix product state formalism exploited by numerical renormalization group algorithms like the density matrix renormalization group. There are two immediate consequences of this result. The first is that Vidal's time-dependent density matrix renormalization group will require only polynomial resources to simulate 1D quantum spin systems for logarithmic |t|. The second consequence is that continuous-time 1D quantum circuits with logarithmic |t| can be simulated efficiently on a classical computer, despite the fact that, after discretization, such circuits are of polynomial depth.     

Composition of Pinot Noir Wine from Grapevine Red Blotch Disease-Infected Vines Managed with Exogenous Abscisic Acid Applications

Grapevine red blotch disease (GRBD) has negative effects on grape development and impacts berry ripening. Abscisic acid (ABA) is a plant growth regulator involved in the initiation of berry ripening. Exogenous abscisic acid application was compared to an unsprayed control on GRBD-positive Pinot noir vines during two vintages, and the total monomeric anthocyanin, total phenolics, phenolic composition, and volatile profile were measured in wines. In addition, untargeted metabolites were profiled using high-resolution LC-MS/MS. Results showed that the wine composition varied by vintage year and was not consistent with ABA application. Wines from the ABA treatment had a lower total anthocyanin and total phenolic content in one year. The untargeted high-resolution LC-MS/MS analysis showed a higher abundance of phenolic compounds in ABA wines in 2019, but lower in 2018. The wine volatile compounds of ABA treatments varied by vintage. There were higher levels of free β-damascenone, β-ionone, nerol, and several fermentation-derived esters, acids, and alcohols in ABA wines, but these were not observed in 2019. Lower 3-isobutyl-2-methoxypyrazine (IBMP) was also observed in wines with ABA treatment in 2019. The results demonstrated that ABA application to the fruit zones did not consistently mitigate the adverse impacts of GRBD on Pinot noir wines.