Effects of solar radiation modification on the ocean carbon cycle:An earth system modeling study

Solar radiation modification(SRM,also termed as geoengineering)has been proposed as a potential option to counteract anthropogenic warming.The underlying idea of SRM is to reduce the amount of sunlight reaching the atmosphere and surface,thus offsetting some amount of global warming.Here,the authors use an Earth system model to investigate the impact of SRM on the global carbon cycle and ocean biogeochemistry.The authors simulate the temporal evolution of global climate and the carbon cycle from the pre-industrial period to the end of this century under three scenarios:the RCP4.5 CO_(2) emission pathway,the RCP8.5 CO_(2) emission pathway,and the RCP8.5 CO_(2) emission pathway with the implementation of SRM to maintain the global mean surface temperature at the level of RCP4.5.The simulations show that SRM,by altering global climate,also affects the global carbon cycle.Compared to the RCP8.5 simulation without SRM,by the year 2100,SRM reduces atmospheric CO_(2) by 65 ppm mainly as a result of increased CO_(2) uptake by the terrestrial biosphere.However,SRM-induced change in atmospheric CO_(2) and climate has a small effect in mitigating ocean acidification.By the year 2100,relative to RCP8.5,SRM causes a decrease in surface ocean hydrogen ion concentration([H^(+)])by 6% and attenuates the seasonal amplitude of[H^(+)]by about 10%.The simulations also show that SRM has a small effect on globally integrated ocean net primary productivity relative to the high-CO_(2) simulation without SRM.This study contributes to a comprehensive assessment of the effects of SRM on both the physical climate and the global carbon cycle.

Simulation Analysis of Flow Characteristics in the Vortex Diode with Double Tangential Tube

The paper analyzed flow characteristics in vortex diode with double tangential tube by numerical simulation. Compared to traditional vortex diode with one tangential tube, the structure of double tangential tube can reduce the forward resistance and improve overall performance. The symmetrical design adopted in vortex diode with double tangential tube;the internal flow field in chamber showed symmetrical distribution in the reverse flow, which can improve the flow stability and accelerate the convergence speed in simulation.

Response of ocean acidification to atmospheric carbon dioxide removal

Artificial CO_(2)removal from the atmosphere(also referred to as negative CO_(2)emissions)has been proposed as a potential means to counteract anthropogenic climate change.Here we use an Earth system model to examine the response of ocean acidification to idealized atmospheric CO_(2)removal scenarios.In our simulations,atmospheric CO_(2)is assumed to increase at a rate of 1%per year to four times its pre-industrial value and then decreases to the pre-industrial level at a rate of 0.5%,1%,2%per year,respectively.Our results show that the annual mean state of surface ocean carbonate chemistry fields including hydrogen ion concentration([H^(+)]),pH and aragonite saturation state respond quickly to removal of atmospheric CO_(2).However,the change of seasonal cycle in carbonate chemistry lags behind the decline in atmospheric CO_(2).When CO_(2)returns to the pre-industrial level,over some parts of the ocean,relative to the pre-industrial state,the seasonal amplitude of carbonate chemistry fields is substantially larger.Simulation results also show that changes in deep ocean carbonate chemistry substantially lag behind atmospheric CO_(2)change.When CO_(2)returns to its pre-industrial value,the whole-ocean acidity measured by[H^(+)]is 15%-18%larger than the pre-industrial level,depending on the rate of CO_(2)decrease.Our study demonstrates that even if atmospheric CO_(2)can be lowered in the future as a result of net negative CO_(2)emissions,the recovery of some aspects of ocean acidification would take decades to centuries,which would have important implications for the resilience of marine ecosystems.

Promoting chondrogenesis by targeted delivery to the degenerating cartilage in early treatment of osteoarthritis

Osteoarthritis(OA)is a highly incident total joint degenerative disease with cartilage degeneration as the primary pathogenesis.The cartilage matrix is mainly composed of collagen,a matrix protein with a hallmark triplehelix structure,which unfolds with collagen degradation on the cartilage surface.A collagen hybridizing peptide(CHP)is a synthetic peptide that binds the denatured collagen triple helix,conferring a potential diseasetargeting possibility for early-stage OA.Here,we constructed an albumin nanoparticle(An)conjugated with CHP,loaded with a chondrogenesis-promoting small molecule drug,kartogenin(KGN).The CHP-KGN-An particle exhibited sustained release of KGN in vitro and prolonged in vivo retention selectively within the degenerated cartilage in the knee joints of model mice with early-stage OA.Compared to treatment with KGN alone,CHP-KGN-An robustly attenuated cartilage degradation,synovitis,osteophyte formation,and subchondral bone sclerosis in OA model mice and exhibited a more prominent effect on physical activity improvement and pain alleviation.Our study showcases that targeting the degenerated cartilage by collagen hybridization can remarkably promote the efficacy of small molecule drugs and may provide a novel delivery strategy for earlystage OA therapeutics.

Biomass chemical looping gasification for syngas production using modified hematite as oxygen carriers

Syngas is a clean energy carrier and a major industrial feedstock. In this paper, syngas was produced via biomass chemical looping gasification(CLG) process. Hematite, the most common Fe-based oxygen carrier(OC), was modified with different metal oxides(CeO_(2), CaO and MgO) by the impregnation method. The hematite modified by CeO_(2), CaO and MgO was namely as CeO_(2)-hematite(CeO_(2)-H), CaO-hematite(CaO-H) and MgO-hematite(MgO-H), respectively. The introduction of CeO_(2), CaO and MgO enhanced the reactivity of lattice oxygen of hematite. The optimum condition for syngas production had been explored as the mass ratio of oxygen carrier to biomass(O/B) of 0.2, the mass ratio of steam to biomass(S/B) of0.75 and temperature of 800℃in the biomass CLG process. The CeO_(2)-H exhibited the most wonderful performance compared to that for CaO-H and MgO-H. The crystal composition of OC influenced greatly in the CLG process. CeFeO_(3)had a good oxygen mobility property and lattice oxygen releasing capacity due to the most oxygen vacancy distributed on the OC surface and the most active lattice oxygen, which is conducive to the biomass chemical looping gasification process for syngas production, leading to the highest gasification efficiency of 95.86% and gas yield of 1.20 m^(3)/kg of the three. Cyclic test proved that CeO_(2)-H had well sintering resistance and cyclic performance.

Continuous-wave terahertz diffraction tomography for measuring three-dimensional refractive index maps

Three-dimensional(3D)refractive index(RI)distribution is important to reveal the object’s inner structure.We implemented terahertz(THz)diffraction tomography with a continuous-wave single-frequency THz source for measuring 3D RI maps.The off-axis holographic interference configuration was employed to obtain the quantitative scattered field of the object under each rotation angle.The 3D reconstruction algorithm adopted the filtered backpropagation method,which can theoretically calculate the exact scattering potential from the measured scattered field.Based on the Rytov approximation,the 3D RI distribution of polystyrene foam spheres was achieved with high fidelity,which verified the feasibility of the proposed method.

Continuous-wave terahertz in-line holographic diffraction tomography with the scattering fields reconstructed by a physics-enhanced deep neural network

Diffraction tomography is a promising,quantitative,and nondestructive three-dimensional(3D)imaging method that enables us to obtain the complex refractive index distribution of a sample.The acquisition of the scattered fields under the different illumination angles is a key issue,where the complex scattered fields need to be retrieved.Presently,in order to develop terahertz(THz)diffraction tomography,the advanced acquisition of the scattered fields is desired.In this paper,a THz in-line digital holographic diffraction tomography(THz-IDHDT)is proposed with an extremely compact optical configuration and implemented for the first time,to the best of our knowledge.A learning-based phase retrieval algorithm by combining the physical model and the convolution neural networks,named the physics-enhanced deep neural network(PhysenNet),is applied to reconstruct the THz in-line digital hologram,and obtain the complex amplitude distribution of the sample with high fidelity.The advantages of the PhysenNet are that there is no need for pretraining by using a large set of labeled data,and it can also work for thick samples.Experimentally with a continuous-wave THz laser,the PhysenNet is first demonstrated by using the thin samples and exhibits superiority in terms of imaging quality.More importantly,with regard to the thick samples,PhysenNet still works well,and can offer 2D complex scattered fields for diffraction tomography.Furthermore,the 3D refractive index maps of two types of foam sphere samples are successfully reconstructed by the proposed method.For a single foam sphere,the relative error of the average refractive index value is only 0.17%,compared to the commercial THz time-domain spectroscopy system.This demonstrates the feasibility and high accuracy of the THz-IDHDT,and the idea can be applied to other wavebands as well.

Government Subsidies,Resource Misallocation and Manufacturing Productivity

Government subsidies for some firms will have effects on the market entry,exit and scale of firms,result in misallocation of resource between firms,and reduce manufacturing productivity.Using data of Chinese industrial enterprises from 1998 to 2007,this paper studies the effect and micro-mechanism of misallocation caused by government subsidy on manufacturing productivity.Decomposition of manufacturing productivity indicates there is resource misallocation between firms and decreasing of manufacturing productivity.Empirical study shows that government subsidies constitute an important factor inducing this resource misallocation.Subsidies change extensive and intensive margins of market,distort resource allocation between firms and reduce manufacturing productivity,and the resource misallocation is more serious in industries with higher proportion of state-owned assets.Specifically,subsidies hinder entry and exit of firms in extensive margins,with subsidized firms having lower propability of market entry and exit compared with unsubsidized firms;subsidies promote scale of subsidized firms and crowds out market share of unsubsidized firms in intensive margins.The implication of this paper is that when providing subsidies government should take into consideration their effect on the firms’dynamic and resource allocation in the frame of general equilibrium.