William Roxburgh, Botanic Garden, near Calcutta, [India], to James Edward Smith

In addition to other items he is sending by Mr Brown also sending seeds, and box of insects gathered by Mr Le Beck, they both wish to become members of the Linnean Society; Le Beck will be a valuable correspondent as he intends to spend his life in India. Recently drew and described a new species of 'Dolphinus'; as large as common dolphin but without dorsal fin, 60 teeth in each jaw, and chiefly inhabits the Ganges river, calls it 'D. gangetica'. [Francis] Buchanan is visiting them; he will send Smith plants

Mechanism of Gold(I)-Catalyzed Rearrangements of Acetylenic Amine-<i>N</i>-Oxides: Computational Investigations Lead to a New Mechanism Confirmed by Experiment

Quantum mechanical studies of the mechanism of gold-catalyzed rearrangements of acetylenic amine-<i>N</i>-oxides to piperidinones or azepanones have revealed a new mechanism involving a concerted heteroretroene reaction, formally a 1,5 hydrogen shift from the <i>N</i>-alkyl groups to the vinyl position of a gold-coordinated methyleneisoxazolidinium or methyleneoxazinanium. Density functional calculations (B3LYP, B3LYP-D3) on the heteroretroene mechanism reproduce experimental regioselectivities and provide an explanation as to why the hydrogen is transferred from the smaller amine substituent. In support of the proposed mechanism, new experimental investigations show that the hydrogen shift is concerted and that gold carbenes are not involved as reaction intermediates

[3,3]-Sigmatropic Rearrangement versus Carbene Formation in Gold-Catalyzed Transformations of Alkynyl Aryl Sulfoxides: Mechanistic Studies and Expanded Reaction Scope

Gold-catalyzed intramolecular oxidation of terminal alkynes with an arenesulfinyl group as the tethered oxidant is a reaction of high impact in gold chemistry, as it introduced to the field the highly valued concept of gold carbene generation via alkyne oxidation. The proposed intermediacy of α-oxo gold carbenes in these reactions, however, has never been substantiated. Detailed experimental studies suggest that the involvement of such reactive intermediates in the formation of dihydro­benzo­thiepinones is highly unlikely. Instead, a [3,3]-sigmatropic rearrangement of the initial cyclization intermediate offers a reaction path that can readily explain the high reaction efficiency and the lack of sulfonium formation. With internal alkyne substrates, however, the generation of a gold carbene species becomes competitive with the [3,3]-sigmatropic rearrangement. This reactive intermediate, nevertheless, does not proceed to afford the Friedel–Crafts-type cyclization product. Extensive density functional theory studies support the mechanistic conclusion that the cyclized product is formed via an intramolecular [3,3]-sigmatropic rearrangement instead of the previously proposed Friedel–Crafts-type cyclization. With the new mechanistic insight, the product scope of this versatile formation of mid-sized sulfur-containing cyclo­alkenones has been expanded readily to various dihydro­benzo­thiocinones, a tetrahydro­benzo­cyclo­nonenone, and even those without the entanglement of a fused benzene ring. Besides gold, Hg­(OTf)₂ can be an effective catalyst, thereby offering a cheap alternative for this intramolecular redox reaction

Deuteration as a Means to Tune Crystallinity of Conducting Polymers

The effects of deuterium isotope substitution on conjugated polymer chain stacking of poly­(3-hexylthiophene) is studied experimentally by X-ray diffraction (XRD) in combination with gel permeation chromatography and theoretically using density functional theory and quantum molecular dynamics. For four P3HT materials with different levels of deuteration (pristine, main-chain deuterated, side-chain deuterated, and fully deuterated), the XRD measurements show that main-chain thiophene deuteration significantly reduces crystallinity, regardless of the side-chain deuteration. The reduction of crystallinity due to the main-chain deuteration is a quantum nuclear effect resulting from a static zero-point vibrational energy combined with a dynamic correlation of the dipole fluctuations. The quantum molecular dynamics simulations confirm the interchain correlation of the proton–proton and deuteron–deuteron motions but not of the proton–deuteron motion. Thus, isotopic purity is an important factor affecting stability and properties of conjugated polymer crystals, which should be considered in the design of electronic and spintronic devices

Relationships between best-corrected visual acuity (BCVA) and orientation discrimination threshold (ODT) in patients with different classifications of age-related macular degeneration (AMD).

<p>Relationships between best-corrected visual acuity (BCVA) and orientation discrimination threshold (ODT) in patients with different classifications of age-related macular degeneration (AMD).</p

Method to calculate the normalized effective area size (NEAS) of each lesion.

<p><b>(A)</b> A circular grid representing the macular region with the center at the foveola. The inner circle represents the central 4 deg and outer circle extends to the central 8 deg. Each sector of the inner circle (sectors 1–4) carries a weight of 1/6 and each sector of the outer circle (sectors 5–12) carries a weight of 1/24. As a whole, the central 8 deg had a weight of 1 (4 × 1/6 + 8 × 1/24 = 1). <b>(B)</b> Example of using the grid to estimate the NEAS of a pigment epithelium detachment lesion (PED, 0.833). <b>(C)</b> Example of using the grid to estimate the NEAS of a sub-retinal fluid lesion (SRF, 0.920). The images in panels B and C correspond to the lesions shown in <a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0185070#pone.0185070.g003" target="_blank">Fig 3E and 3F</a>.</p

Smoothed probability density plots showing the distribution of best-corrected visual acuity (BCVA) (A) and orientation discrimination threshold (ODT) (B).

<p>Smoothed probability density plots showing the distribution of best-corrected visual acuity (BCVA) (A) and orientation discrimination threshold (ODT) (B).</p

Demographic data, macular lesions, and their locations, size, and associated normalized effective area size (NEAS) of age-related macular degeneration (AMD) patients with different classifications.

<p>Demographic data, macular lesions, and their locations, size, and associated normalized effective area size (NEAS) of age-related macular degeneration (AMD) patients with different classifications.</p

Optical coherence tomography (OCT) images show examples of lesions in different classifications of age-related macular degeneration (AMD).

<p><b>(A)</b> Dry AMD. Dark arrows indicate drusens; <b>(B)</b> Non-active wet AMD, yellow arrow indicates a pigment epithelium detachment (PED); <b>(C-F)</b> Active wet AMD. Blue stars indicate sub-retinal fluid (SRF), the red star indicates intra-retinal fluid (IRF), and the green triangle indicates scarring.</p

Normalized multivariate-regression weights of different types of lesions for the variation of orientation discrimination threshold (ODT) and best-corrected visual acuity (BCVA).

<p>Normalized weights of lesions’ locations <b>(A)</b>, sizes <b>(B)</b>, and NEAS <b>(C)</b> for ODT; normalized weights of lesions’ locations <b>(D)</b>, sizes <b>(E)</b>, and NEAS <b>(F)</b> for BCVA. A filled bar indicates a significant contribution to the regression model.</p