The major cause of sea-level change during ice ages is the exchange of water between ice and ocean and the planet's dynamic response to the changing surface load. Inversion of ∼1,000 observations for the past 35,000 y from localities far from former ice margins has provided new constraints on the fluctuation of ice volume in this interval. Key results are: (i) a rapid final fall in global sea level of ∼40 m in <2,000 y at the onset of the glacial maximum ∼30,000 y before present (30 ka BP); (ii) a slow fall to −134 m from 29 to 21 ka BP with a maximum grounded ice volume of ∼52 × 10 6 km 3 greater than today; (iii) after an initial short duration rapid rise and a short interval of near-constant sea level, the main phase of deglaciation occurred from ∼16.5 ka BP to ∼8.2 ka BP at an average rate of rise of 12 m·ka −1 punctuated by periods of greater, particularly at 14.5-14.0 ka BP at ≥40 mm·y −1 (MWP-1A), and lesser, from 12.5 to 11.5 ka BP (Younger Dryas), rates; (iv) no evidence for a global MWP-1B event at ∼11.3 ka BP; and (v) a progressive decrease in the rate of rise from 8.2 ka to ∼2.5 ka BP, after which ocean volumes remained nearly constant until the renewed sea-level rise at 100-150 y ago, with no evidence of oscillations exceeding ∼15-20 cm in time intervals ≥200 y from 6 to 0.15 ka BP.he understanding of the change in ocean volume during glacial cycles is pertinent to several areas of earth science: for estimating the volume of ice and its geographic distribution through time (1); for calibrating isotopic proxy indicators of ocean volume change (2, 3); for estimating vertical rates of land movement from geological data (4); for examining the response of reef development to changing sea level (5); and for reconstructing paleo topographies to test models of human and other migrations (6). Estimates of variations in global sea level come from direct observational evidence of past sea levels relative to present and less directly from temporal variations in the oxygen isotopic signal of ocean sediments (7). Both yield modeldependent estimates. The first requires assumptions about processes that govern how past sea levels are recorded in the coastal geology or geomorphology as well as about the tectonic, isostatic, and oceanographic contributions to sea level change. The second requires assumptions about the source of the isotopic or chemical signatures of marine sediments and about the relative importance of growth or decay of the ice sheets, of changes in ocean and atmospheric temperatures, or from local or regional factors that control the extent and time scales of mixing within ocean basins.Both approaches are important and complementary. The direct observational evidence is restricted to time intervals or climatic and tectonic settings that favor preservation of the records through otherwise successive overprinting events. As a result, the records become increasingly fragmentary backward in time. The isotopic evidence, in contrast, being recorded in deep-water carbonate marine sediments, extends further...

Artificial photosynthesis holds promise in producing solar fuels and chemicals. Although encouraging achievements have been made in the development of catalysts for reaction/ process modules in artificial photosynthesis, constructing a highly compatible complex reaction system remains a distant prospect. Herein, an artificial thylakoid is proposed and constructed by decorating the inner wall of protamine−titania (PTi) microcapsules with cadmium sulfide quantum dots (CdS QDs) for the photobiocoupled reduction of carbon dioxide (CO 2 ) via a single enzyme (formate dehydrogenase) and multiple enzymes (formate/formaldehyde/alcohol dehydrogenases). The size-selective capsule wall compartmentalizes photocatalytic oxidation and biocatalytic reduction, creating well-directed reaction sequences and protecting enzymes from deactivation. The favorable electronic coupling and band structure between CdS and PTi separate holes and electrons to afford an NADH regeneration rate of 4226 ± 121 μmol g −1 h −1 and optimized yield of 93.03 ± 3.84%. The photobiocoupled system achieves formate and methanol outputs of 1500 and 99 μM h −1 with a single enzyme and multiple enzymes, respectively. Our study may exploit a method for the construction of complex artificial catalytic systems with multiple reactions.

Recent advances in enzyme-photo-coupled catalytic systems are reviewed and highlighted from the perspective of system engineering.

Solar energy conversion by photocatalysis holds promise in energy supply, but its efficiency is hindered by the mismatch in charge generation, transfer, and utilization. In natural photosynthesis, photosystem I (PSI) exhibits an intrinsic quantum efficiency of nearly 100% in solar energy conversion. The elaborate synergy of electron transfer and electron utilization guarantees the conversion of unstable excited electrons to stable electrons in reduced nicotinamide adenine dinucleotide phosphate (NADPH). To demonstrate this in vitro, we report a design of core−shell metal−organic frameworks (MOFs) as an "electron buffer tank" to coordinate electron transfer and electron utilization in photocatalysis. The electrons are generated via the irradiation on photosensitizers (2-aminoterephthalic acid, NH 2 -BDC) in the core and then transferred to Zr 6 O 8 clusters on the shell through the light-induced ligand-to-metal charge transfer mechanism. Neighboring reaction centers, [Cp*Rh(bpydc)H 2 O] 2+ , on the MOFs behave as the electron buffer tank and store these electrons in the form of hydrides for subsequent regeneration of reduced nicotinamide adenine dinucleotide (NADH). The electron lifetime is prolonged from nanoseconds to seconds, leading to 2.27-fold enhancement of electron availability and 2.08-fold enhancement of activity compared to the homogeneous reaction counterpart. The coupling of NADH regeneration and enzyme catalysis further enables the asymmetric reduction of carbonyl to chiral amine. The electron buffer tank concept may offer a generic strategy to coordinate mass transfer and chemical reaction in a broad range of catalytic processes.

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Photoenzymatic coupled catalysis, integrating semiconductor photocatalysis and enzymatic catalysis, exhibits great potential for light-driven synthesis. To make photocatalyst and enzyme at play concertedly, nicotinamide-based cofactors have been widely used as electron carrier. However, these cofactors are easily oxidized into enzymatically inactive form by photo-generated holes. Herein, oxidation mechanism of NADH, one typical nicotinamide-based cofactor, by photo-generated holes was reported. With CdS, g-C3N4 and BiVO4 as hole generators, NADH is oxidized into NAD + or fragmented into ADP-ribose derivatives through multi-step electron transfer. Importantly, fragmentation reaction is inhibited with dopamine and neutral red to coordinate electron transfer between NADH and photo-generated holes.

Metal−organic frameworks (MOFs) for in situ enzyme encapsulation commonly possess weak metal−ligand coordination bonds and rather small pores, which are instable in aqueous solution and present rather high diffusion resistance of reactants. Herein, we prepare a type of hierarchically porous and water-tolerant MOFs through a facile polyphenol treatment method for enzyme encapsulation. In brief, enzymes are first in situ encapsulated in a zeolitic imidazolate framework-8 (ZIF-8) through coprecipitation of enzymes, zinc ions (Zn 2+ ), and 2-imidazole molecules (2-MI). Then, tannic acid (TA, a typical polyphenol) is introduced to functionalize the surface and etch the void of ZIF-8, acquiring the biocatalyst termed as E@ZIF-8@ZnTA. The hierarchically porous structure would accelerate the diffusion process of reactants, whereas the Zn-O bond in a TA-Zn nanocoating would improve the structural stability against water corrosion compared to ZIF-8. Taking glucose oxidase (GOD) as a model enzyme for the catalytic conversion of β-D-glucose, the

Enzyme-photocoupled catalytic systems (EPCSs), combining the natural enzyme with a library of semiconductor photocatalysts, may break the constraint of natural evolution, realizing sustainable solar-to-chemical conversion and non-natural reactivity of the enzyme. The overall efficiency of EPCSs strongly relies on the shuttling of energy-carrying molecules, e.g., NAD+/NADH cofactor, between active centers of enzyme and photocatalyst. However, few efforts have been devoted to NAD+/NADH shuttling. Herein, we propose a strategy of constructing a thylakoid membrane-inspired capsule (TMC) with fortified and tunable NAD+/NADH shuttling to boost the enzyme-photocoupled catalytic process. The apparent shuttling number (ASN) of NAD+/NADH for TMC could reach 17.1, ∼8 times as high as that of non-integrated EPCS. Accordingly, our TMC exhibits a turnover frequency (TOF) of 38 000 ± 365 h–1 with a solar-to-chemical efficiency (STC) of 0.69 ± 0.12%, ∼6 times higher than that of non-integrated EPCS.