diffi culty in the generation of core-shell NPs with a lipid shell containing various amounts of water, which governs the rigidity of the NPs; larger amounts of interfacial water would result in more fl exible NPs. [13][14][15] Microfl uidic platforms can generate lipid-polymer hybrid NPs via rapid reaction and precise manipulation of fl uids inside microchannels; [16][17][18][19][20] however, the fabrication of hybrid NPs with varying water content has not been achieved by microfl uidics. Here, we develop a two-stage microfl uidic platform that can assemble core-shell poly(lactic-co -glycolic acid) (PLGA)-lipid NPs in a single-step. [ 16,21 ] Lipid-covered PLGA NPs or liposomes that have the same size and surface properties, but varying rigidity as a result of tuning the interfacial water layer, can be realized using the same microchip. It enables us to explore how the rigidity of NPs differentially regulates the cellular uptake and to elucidate the intrinsic mechanism. It also allows the treatment of various diseases through the use of specifi c particles.Particle rigidity is tuned by varying the amounts of interfacial water between the PLGA core and lipid shell of the hybrid NPs; this is achieved by altering the injection order of the PLGA and lipid-poly(ethylene glycol) (PEG) organic solutions in the microfl uidic chip. The microfl uidic device shown in Scheme 1 consists of two stages: 1) The fi rst stage comprises three inlets and a straight synthesis microchannel; 2) The second stage is composed of one centered inlet and a spiral mixing channel (see Supporting Information (SI), Figure S1 for more details). We synthesized particles of varying water content and rigidity using the same chip but different order of the introducing reagents. In mode 1, the fi rst stage is used for generating PLGA NPs through interfacial precipitation, while the second stage forms lipid-coated NPs as a result of hydrophobic attraction between the lipid tail and PLGA (P-L NPs; Scheme 1 A, Figure S2 (SI)). In mode 2, we change the injection order by introducing the lipid solution at the fi rst stage and the PLGA solution at the second stage. In this way, lipids form into a liposome in aqueous solution at the fi rst stage, followed by re-assembly onto the surface of PLGA NPs at the second stage through effective mixing (P-W-L NPs; Scheme 1 B, Figure S2 (SI)). The throughput of NPs by a single chip is 41 mL h −1 (≈8 mg h −1 for P-W-L NPs, and ≈6.5 mg h −1 for P-L NPs). For both mode 1 and mode 2, transmission electron microscopy (TEM) images ( Figure 1 A; Figure S2, SI) show complete lipid coverage on the surface of PLGA NPs. The different injection order of the solutions may result in the presence of interfacial water between the PLGA core and lipid shell of the P-W-L NPs (mode 2) but not in P-L NPs (mode 1), which is confi rmed by cryogenic TEM (cryo-TEM Figure 1 B; see also SI). For the P-L NPs, the lipid shell is tightly attached to the PLGA core, while for the P-W-L Even though much research has shown that nanoparticles (NPs) ca...

The mid-Pleistocene transition (MPT) is widely recognized as a shift in paleoclimatic periodicity from 41- to 100-kyr cycles, which largely reflects integrated changes in global ice volume, sea level, and ocean temperature from the marine realm. However, much less is known about monsoon-induced terrestrial vegetation change across the MPT. Here, on the basis of a 1.7-million-year δ13C record of loess carbonates from the Chinese Loess Plateau, we document a unique MPT reflecting terrestrial vegetation changes from a dominant 23-kyr periodicity before 1.2 Ma to combined 100, 41, and 23-kyr cycles after 0.7 Ma, very different from the conventional MPT characteristics. Model simulations further reveal that the MPT transition likely reflects decreased sensitivity of monsoonal hydroclimate to insolation forcing as the Northern Hemisphere became increasingly glaciated through the MPT. Our proxy-model comparison suggests varied responses of temperature and precipitation to astronomical forcing under different ice/CO2 boundary conditions, which greatly improves our understanding of monsoon variability and dynamics from the natural past to the anthropogenic future.

Mechanical exfoliation from bulk layered crystal is widely used for preparing two-dimensional (2D) layered materials, which involves not only out-of-plane interlayer cleavage but also in-plane fracture. Through a statistical analysis on the exfoliated 2D flakes, we reveal the in-plane cleavage behaviors of six representative layered materials, including graphene, h-BN, 2H phase MoS2, 1T phase PtS2, FePS3, and black phosphorus. In addition to the well-known interlayer cleavage, these 2D layered materials show a distinctive tendency to fracture along certain in-plane crystallography orientations. With theoretical modeling and analysis, these distinct in-plane cleavage behaviors can be understood as a result of the competition between the release of the elastic energy and the increase of the surface energy during the fracture process. More importantly, these in-plane cleavage behaviors provide a fast and noninvasive method using optical microscopy to identify the lattice direction of mechanical exfoliated 2D layered materials.

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