Geochemistry of rare earth elements in the mid-late Quaternary sediments of the western Philippine Sea and their paleoenvironmental significance

Based on a δ180 chronology, rare earth elements （REE） and other typical elements in sediments from core MD06-3047 in the western Philippine Sea were analyzed to constrain the provenances of the sediments and investigate quantitative changes in the Asian eolian input to the study area over the last 700 ka. Among the competing processes that might affect REE compositions, sediment provenance is the most important one. Provenance analysis suggests that the study sediments have two provenance end-members; local volcanic sources are dominant, and eolian dust from the Asian continent has a smaller contribution. During glacial periods, eolian input to the western Philippine Sea was enhanced. In contrast, material supply from local volcanics in- creased during interglacial periods. Changes in eolian input to the study area were probably related to the strength of the East Asian winter monsoon （EAWM） as well as aridity in the Asian continent on an orbital time scale, and were partly influenced by local control factors on shorter time scales. Therefore, we propose that the present study expands the application of the REE-based method for quantitatively estimating the eolian component from the mid-latitude northern Pacific to the low-latitude western Pacific. Additionally, the study preliminarily confirms the influence of EAWM-transported eolian materi- al on sedimentation in the western Philippine Sea since 700 ka.

Paleoenvironmental Changes in the Northern Okinawa Trough since 25 ka BP:REE and Organic Carbon Evidence

Paleoenvironmental changes in the northern Okinawa trough covering the last 25 ka were synthetically reconstructed using REE and organic carbon indices of core CSH1.Variations of these parameters revealed three distinct intervals of major sediment provenance changes that can be related to sea-level fluctuation and Tsushima Warm Current evolution.Interval 1（16-24.7 ka BP） is characterized by dominantly fluvial discharge from the Changjiang（Yangtze River） and Huanghe（Yellow River） as well as high primary productivity.In Interval 2（7.3-16 ka BP）,the Changjiang and Huanghe mouths regressed with sea-level rising.The newly formed Tsushima Warm Current could carry some sediment loads of Taiwan to the study core,especially during its late phase（7.3-8.2 ka BP）.Modern oceanographic conditions were finally established since the beginning of Interval 3,leading to more terrigenous contribution from Taiwan,whereas low sea-surface productivity in the study area.

Bulk-Si photonics technology for DRAM interface[Invited]

We present photonics technology based on a bulk-Si substrate for cost-sensitive dynamic random-access memory(DRAM)optical interface application.We summarize the progress on passive and active photonic devices using a local-crystallized Si waveguide fabricated by solid phase epitaxy or laser-induced epitaxial growth on bulk-Si substrate.The process of integration of a photonic integrated circuit(IC)with an electronic IC is demonstrated using a 65 nm DRAM periphery process on 300 mm wafers to prove the possibility of seamless integration with various complementary metal-oxide-semiconductor devices.Using the bulk-Si photonic devices,we show the feasibility of high-speed multidrop interface:the Mach–Zehnder interferometer modulators and commercial photodetectors are used to demonstrate four-drop link operation at 10 Gb∕s,and the transceiver chips with photonic die and electronic die work for the DDR3 DRAM interface at 1.6 Gb∕s under a 1∶4 multidrop configuration.

Thermoelectric characteristics of nanocomposites made of HgSe and Ag nanoparticles for flexible thermoelectric devices

We synthesized thermoelectric nanocomposites by mixing HgSe nanoparticles （NPs） and Ag NPs in a solution and investigated the thermoelectric properties of the nanocomposite thin films on flexible plastic substrates. The X-ray diffraction patterns and the X-ray photoelectron spectra of the nanocomposites demonstrate that cation-exchange reactions occurred spontaneously in the mixed solution of HgSe and Ag NPs and that the HgSe NPs were completely converted to Ag2Se when the Ag NP content was 20 vol.%. The maximum power factor and the thermoelectric figure of merit were obtained as 75 pW/mK2 and 0.043 at 300 K, respectively, when the Ag NP content was 10 vol.%, which is 100 times higher than that of HgSe NP thin films. In addition, the mechanical stability of the thermoelectric nanocomposite film was confirmed through repeated bending tests.