Middle Holocene marine flooding and human response in the south Yangtze coastal plain, East China

Coastal flooding catastrophes have affected human societies on coastal plains around the world on several occasions in the past, and are threatening 21st century societies under global warming and sea-level rise. However, the role of coastal flooding in the interruption of the Neolithic Liangzhu culture in the lower Yangtze valley, East China coast has been long contested. In this study, we used a well-dated Neolithic site (the Yushan site) close to the present coastline to demonstrate a marine drowning event at the terminal stage of the Liangzhu culture and discuss its linkage to relative sea-level rise. We analysed sedimentology, chronology, organic elemental composition, diatoms and dinoflagellate cysts for several typical profiles at the Yushan site. The field and sedimentary data provided clear evidence of a palaeo-typhoon event that overwhelmed the Yushan site at ∼2560 BCE, which heralded a period of marine inundation and ecological deterioration at the site. We also infer an acceleration in sea-level rise at 2560–2440 BCE from the sedimentary records at Yushan, which explains the widespread signatures of coastal flooding across the south Yangtze coastal plain at that time. The timing of this mid-Holocene coastal flooding coincided with the sudden disappearance of the advanced and widespread Liangzhu culture along the lower Yangtze valley. We infer that extreme events and flooding accompanying accelerated sea-level rise were major causes of vulnerability for prehistoric coastal societies

Surface-Plasmon-Coupled Fluorescence Enhancement Based on Ordered Gold Nanorod Array Biochip for Ultrasensitive DNA Analysis

An innovative gold nanorod (GNR) array biochip was developed to systematically investigate the localized surface plasmon resonance (LSPR)-coupled fluorescence enhancement for signal amplification in molecular beacon detection. An ordered GNR assembly in vertical standing array on a glass surface was fabricated as plasmonic substrates, resulting in dramatically intensified LSPR between adjacent nanoparticles as compared to that from an ensemble of random nanorods. We have shown that the plasmonic response of the nanoarray can be tuned by the proper choice of GNR size to overlap the fluorophore excitation and emission wavelengths greater than 600 nm. Plasmon-induced fluorescence enhancement was found to be distance-dependent with the competition between quenching and enhancement by the metal nanostructures. The augmented fluorescence enhancement by the GNR array can efficiently overcome the quenching effect of the gold nanoparticle even at close proximity. The enhancement correlates with the spectral overlap between the fluorophore excitation/emission and the plasmonic resonance of the GNR array, indicating a surface-plasmon-enhanced excitation and radiative mechanism for the amplification. From these results, the applicability of the ordered GNR array chip was extended to molecular fluorescence enhancement for practical use as a highly functional and ultrasensitive plasmonic DNA biochip in molecular beacon fashion

Dynamic Kinetic Resolution via Dual-Function Catalysis of Modified Cinchona Alkaloids: Asymmetric Synthesis of α-Hydroxy Carboxylic Acids

A highly enantioselective catalytic transformation of racemic α-hydroxy acids to optically active α-hydroxy acids is reported. A new procedure was developed for the condensation of racemic α-hydroxy acids with trichloromethyl chloroformate (diphosgene) at room temperature in the presence of activated charcoal to form 5-substituted-1,3-dioxolane-2,4-diones in 90−100% yield. An efficient dynamic kinetic resolution of 5-aryl dioxolanediones was realized via a modified cinchona alkaloid-catalyzed alcoholytic opening of the dioxolanedione ring, generating a variety of optically active α-hydroxy esters in 91−96% ee and 61−85% chemical yield. In this dynamic kinetic resolution, the modified cinchona alkaloid was found to serve dual catalytic roles, mediating both the rapid racemization of the 5-aryl dioxolanediones and the enantioselective alcoholytic ring opening of the 5-aryl dioxolanediones. Consequently, both enantiomers of the 5-aryl dioxolanediones were converted to highly enantiomerically enriched aromatic α-hydroxy esters in yields (61−85%), far exceeding the maximum of 50% for a normal kinetic resolution. This development not only represents an expansion of the scope of asymmetric acyl-transfer catalysis of synthetic catalysts but also provides a new approach for the development of efficient chemical dynamic kinetic resolutions promoted by a single catalyst. 5-Alkyl dioxolanediones were resolved by a conventional but highly enantioselective kinetic resolution to provide α-hydroxy acids and esters in high optical purity and good yields

Directional links extracted from the study area (number under or above each link is index).

Directional links extracted from the study area (number under or above each link is index).</p

The project schedule of VMS installation process is {4,3,7,8,6,36,5,27}, and the saturated number of VMS is 8 in test area (number in square under VMS means installation precedence order).

<p>The project schedule of VMS installation process is {4,3,7,8,6,36,5,27}, and the saturated number of VMS is 8 in test area (number in square under VMS means installation precedence order).</p

Optimizing location of variable message signs using GPS probe vehicle data - Fig 3

<p>Move direction for the tabu search algorithm (the assumed value above links indicates guidance utility if VMS located on that link): (a) two consecutive links have similar large guidance utility; (b) several consecutive links have similar large guidance utility.</p

Test area in Beijing urban road OpenStreetMap contributors (openstreetmap.org).

<p>Test area in Beijing urban road OpenStreetMap contributors (<a href="http://openstreetmap.org" target="_blank">openstreetmap.org</a>).</p

Comparison of VMS location in different classification number of guidance utility <i>a</i> and information coverage <i>b</i>.

<p>Comparison of VMS location in different classification number of guidance utility <i>a</i> and information coverage <i>b</i>.</p

The location allocation order of VMS as <i>a</i> = 4,<i>b</i> = 4.

<p>The location allocation order of VMS as <i>a</i> = 4,<i>b</i> = 4.</p

Data of index 1–10 links in test area during peak hours.

<p>Data of index 1–10 links in test area during peak hours.</p