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1.
ACS Appl Mater Interfaces ; 13(43): 50836-50850, 2021 Nov 03.
Artigo em Inglês | MEDLINE | ID: mdl-34689546

RESUMO

Polyetheretherketone (PEEK) is a biocompatible polymer, but its clinical application is largely limited due to its inert surface. To solve this problem, a multifunctional PEEK implant is urgently fabricated. In this work, a dual-metal-organic framework (Zn-Mg-MOF74) coating is bonded to PEEK using a mussel-inspired polydopamine interlayer to prepare the coating, and then, dexamethasone (DEX) is loaded on the coating surface. The PEEK surface with the multifunctional coating provides superior hydrophilicity and favorable stability and forms an alkaline microenvironment when Mg2+, Zn2+, 2,5-dihydroxyterephthalic acid, and DEX are released due to the coating degradation. In vitro results showed that the multifunctional coating has strong antibacterial ability against both Escherichia coli and Staphylococcus aureus; it also improves human umbilical vein endothelial cell angiogenic ability and enhances rat bone marrow mesenchymal stem cell osteogenic differentiation activity. Furthermore, the in vivo rat subcutaneous infection model, chicken chorioallantoic membrane model, and rat femoral drilling model verify that the PEEK implant coated with the multifunctional coating has strong antibacterial and angiogenic ability and promotes the formation of new bone around the implant with a stronger bone-implant interface. Our findings indicate that DEX loaded on the Zn-Mg-MOF74 coating-modified PEEK implant with bacteriostasis, angiogenesis, and osteogenesis properties has great clinical application potential as bone graft materials.


Assuntos
Antibacterianos/farmacologia , Regeneração Óssea/efeitos dos fármacos , Estruturas Metalorgânicas/farmacologia , Neovascularização Patológica/tratamento farmacológico , Adsorção , Animais , Antibacterianos/síntese química , Antibacterianos/química , Benzofenonas/química , Benzofenonas/farmacologia , Dexametasona/química , Dexametasona/farmacologia , Escherichia coli/efeitos dos fármacos , Magnésio/química , Magnésio/farmacologia , Masculino , Estruturas Metalorgânicas/síntese química , Estruturas Metalorgânicas/química , Testes de Sensibilidade Microbiana , Estrutura Molecular , Neovascularização Patológica/microbiologia , Polímeros/química , Polímeros/farmacologia , Ratos , Ratos Sprague-Dawley , Staphylococcus aureus/efeitos dos fármacos , Zinco/química , Zinco/farmacologia
2.
Glob Chang Biol ; 27(24): 6321-6330, 2021 12.
Artigo em Inglês | MEDLINE | ID: mdl-34583427

RESUMO

Despite the strong recommendations from scientists, to till or not to till remains a confusing question for many farmers around the world due to the worries of crop yield decline and negative impacts on soils and environment. A confused understanding of the role of the individual principles of conservation agriculture significantly limits the effectiveness and applicability of soil conservation strategies and frameworks to achieve sustainable agriculture. By distinguishing clearly between the different principles of conservation agriculture, the net effects of no-tillage on improving and sustaining agro-ecosystems are analyzed based on 49 recent meta-analyses in this study. The review shows that no-tillage leads to a significant decline of crop yield (-8.0% to 10.0%, median: -1.9%), whereas residue retention represents the key driver for improving crop production (4.0%-28.0%, median: 8.2%). The efficacy of no-tillage for water erosion control, especially runoff (-24.0% to -0.7%, median: -10.0%), is often insignificant and otherwise lower compared to residue retention (-87.0% to -14.0%, median: -45.5%). Soil carbon sequestration potential under conservation tillage is quite limited or even close to zero, and if any, it can likely be attributed to the associated residue retention (-0.1% to 12.8%, median: 9.7%) rather than no-tillage (-2.0% to 10.0%, median: 4.8%). Our analysis illustrates that in conservation agriculture, no-tillage as the original and central principle of soil management is often less effective than associated supplementary measures, in particular residue retention. Residue retention may therefore play a key role for achieving sustainable land use. An additional benefit of residue retention is the less dramatic change of farming practices compared to no-tillage. The results of this review illustrate that a new framework for assessing the benefits of conservation practices has to be developed. To till, or not to till, is not the question: residue retention seems more critical.


Assuntos
Agricultura , Ecossistema , Sequestro de Carbono , Produção Agrícola , Solo
3.
ChemSusChem ; 14(17): 3614-3621, 2021 Sep 06.
Artigo em Inglês | MEDLINE | ID: mdl-34107177

RESUMO

Three small-molecule acceptors (Por-PDI, TEHPor-PDI, and BBOPor-PDI) with different side chains were synthesized by using a porphyrin core as the electron-donating unit and connecting electron-withdrawing perylene diimide dimers via acetylene bridges. The bulk heterojunction organic solar cells based on the three acceptors and a polymer donor provided power conversion efficiencies (PCEs) of 3.68-5.21 % when the active layers were fabricated with pyridine additives. Though the synthesis of Por-PDI is easier with fewer reaction steps and higher yields, the devices based on Por-PDI showed the best performance with a PCE of 5.21 %. The more ordered intermolecular packing due to the reduced steric hindrance at the porphyrin core of Por-PDI could contribute to the more balanced hole/electron mobilities, higher maximum charge generation rate, and less bimolecular recombination in Por-PDI devices, which are beneficial for the higher PCE.

4.
Sci Total Environ ; 778: 146308, 2021 Jul 15.
Artigo em Inglês | MEDLINE | ID: mdl-33721652

RESUMO

Soil conservation measures (SCM) are believed to be effective in terms of wind erosion control. Currently, most studies regarding the efficacy of SCM in erosion control are based on data of individual experimental sites. A comprehensive understanding of the effectiveness of SCM and related impacting factors at large scale is lacking. A synthesis was conducted in this study based on data compiled from field experiments in major eroded regions of China in order to fully evaluate the efficacy of various SCM practices in erosion reduction, and further assess how their efficacy varied under different environmental conditions. Two main SCM categories were identified, i.e. agricultural measures (AM) used for both crop production and erosion control, and vegetation measures (VM) used for erosion control only. The results showed that SCM could lead to a significant reduction of wind erosion by over a half (0.51). The reduction of wind erosion under VM (0.56) was significantly higher than AM (0.46). Specifically, most AM and all the VM investigated in this study were beneficial for wind erosion control. Multiple cropping was the only practice that significantly increased the wind erosion rate compared to the conventional treatment. We further found that the effectiveness of SCM highly dependent on precipitation, temperature, soil organic carbon concentration, soil water content, soil type, elevation, and vegetation coverage. The responses of the efficacy of AM and VM to these environmental conditions also differed. Another important finding is that the lowest efficacy of SCM in erosion control was observed in regions with the highest erosion risk, indicating the greater challenge in erosion reduction in these regions. The efficacy of SCM quantified in this study can be used as an essential reference for the adoption of SCM in China and the environmental conditions should also be considered carefully when designing a SCM application framework.

5.
Sci Adv ; 6(41)2020 Oct.
Artigo em Inglês | MEDLINE | ID: mdl-33028517

RESUMO

Nanoporous membranes with two-dimensional materials such as graphene oxide have attracted attention in volatile organic compounds (VOCs) and H2 adsorption because of their unique molecular sieving properties and operational simplicity. However, agglomeration of graphene sheets and low efficiency remain challenging. Therefore, we designed hierarchical nanoporous membranes (HNMs), a class of nanocomposites combined with a carbon sphere and graphene oxide. Hierarchical carbon spheres, prepared following Murray's law using chemical activation incorporating microwave heating, act as spacers and adsorbents. Hierarchical carbon spheres preclude the agglomeration of graphene oxide, while graphene oxide sheets physically disperse, ensuring structural stability. The obtained HNMs contain micropores that are dominated by a combination of ultramicropores and mesopores, resulting in high VOCs/H2 adsorption capacity, up to 235 and 352 mg/g at 200 ppmv and 3.3 weight % (77 K and 1.2 bar), respectively. Our work substantially expands the potential for HNMs applications in the environmental and energy fields.

6.
ACS Appl Mater Interfaces ; 12(37): 41852-41860, 2020 Sep 16.
Artigo em Inglês | MEDLINE | ID: mdl-32811138

RESUMO

Recent advances in non-fullerene acceptors (NFAs) have resulted in significant improvement in the power conversion efficiencies (PCEs) of organic solar cells (OSCs). In our efforts to boost open-circuit voltage (VOC) for OSCs, the molecular design employing thiobarbituric acid (TBTA) end groups and an indacenodithieno[3,2-b]thiophene (IDTT) core gives rise to NFAs with significantly raised lowest unoccupied molecular orbital (LUMO) energy level, which, when paired with PCE10, can achieve VOC's over 1.0 V and decent PCEs that outperform the equivalent devices based on the benchmark ITIC acceptor. While the use of a TBTA end group is effective in tuning energy levels, very little is known about how the alkyl substitution on the TBTA group impacts the solar cell performance. To this end, TBTA end groups are alkylated with linear, branched, and aromatic sidechains to understand the influence on thin-film morphology and related device performances. Our study has confirmed the dependence of solar cell performance on the end-group substituents. More importantly, we reveal the presence of an ideal window of crystallinity associated with the medium-length hydrocarbon chains such as ethyl and benzyl. Deviation to the shorter methyl group makes the acceptor too crystalline to mix with the polymer donor and form proper domains, whereas longer and branched alkyl chains are too sterically bulky and hinder charge transport due to nonideal packing. Such findings underline the comprehensive nature of thin-film morphology and the subtle end-group effects for the design of non-fullerene acceptors.

7.
Sci Total Environ ; 736: 139478, 2020 Sep 20.
Artigo em Inglês | MEDLINE | ID: mdl-32485370

RESUMO

No tillage (NT) has been recommended as an essential conservation agriculture (CA) management in terms of water erosion control. However, the term of NT actually represents both NT and NT plus straw mulching (NTS) in a large amount of studies, which is out of the scope of its original meaning. Consequently, the mixed use of the two terms may cause biased estimate of the role of NT in erosion reduction. We aimed to distinguish actual roles of tillage reduction and residue retention in erosion control based on published data from field experiments of China. A database of paired experiments was compiled from 40 published literatures, with tillage practices including conventional tillage, reduced tillage, no tillage, and their combinations with residue retention. Variable-controlling approach was adopted to comprehensively identify the roles of tillage reduction and residue retention in runoff and soil loss reduction. Our results showed that residue retention caused significant decline of both water and sediment loss, whereas tillage reduction only led to insignificant change of runoff and soil loss. No tillage plus residue retention was also beneficial in terms of erosion control, very likely due to the application of residue retention. The results strengthen the higher influence of residue retention over tillage reduction with respect to soil and water conservation. It also challenges the conclusion of previous studies that NT could lead to the reduction of both runoff and soil loss based on the mixed use of NT and NTS. Furthermore, the efficiency of straw mulching in erosion control declines as application duration increases, indicating the effects of CA should not be overestimated in longer-term. The effectiveness of CA in erosion control also differs among various soil types. Overall, this study highlights the necessity of understanding the influences of tillage reduction, residue retention and the combination of the two managements in order to better evaluate and manage CA with respect to water erosion control, but the impacts of application duration of CA and soil types must be properly considered when adopting CA to reduce erosion.

8.
ACS Appl Mater Interfaces ; 12(14): 16387-16393, 2020 Apr 08.
Artigo em Inglês | MEDLINE | ID: mdl-32180392

RESUMO

Ternary organic solar cells (OSCs) provide a convenient and effective means to further improve the power conversion efficiency (PCE) of binary ones via composition control. However, the role of the third component remains to be explored in specific binary systems. Herein, we report ternary blend solar cells by adding the narrow-band-gap donor PCE10 as the mediator into the PBDB-T:IDTT-T binary blend system. The extended absorption, efficient fluorescence resonance energy transfer, enhanced charge dissociation, and induced tighter molecular packing of the ternary blend films enhance the photovoltaic properties of devices and deliver a champion PCE of 10.73% with an impressively high open-circuit voltage (VOC) of 1.03 V. Good miscibility and similar molecular packing behavior of the components guarantee the desired morphology in the ternary blend films, leading to solar cell devices with over 10% PCEs at a range of compositions. Our results suggest that ternary systems with properly aligned energy levels and overlapping absorption among the components hold great promises to further enhance the performance of corresponding binary ones.

9.
Carbon Balance Manag ; 14(1): 14, 2019 Nov 21.
Artigo em Inglês | MEDLINE | ID: mdl-31754840

RESUMO

Climate change has emerged as one of the most important environmental issues worldwide. As the world's biggest developing country, China is participating in combating climate change by promoting a low carbon economy within the context of global warming. This paper summarizes the pathways of China's low carbon economy including the aspects of energy, industry, low carbon cities, circular economy and low carbon technology, afforestation and carbon sink, the carbon emission trading market and carbon emission reduction targets. There are many achievements in the implementation of low carbon policies. For example, carbon emission intensity has been reduced drastically along with the optimizing of energy and industry structure and a nationwide carbon trading market for electricity industry has been established. However, some problems remain, such as the weakness of public participation, the ineffectiveness of unified policies for certain regions and the absence of long-term planning for low carbon cities development. Therefore, we propose some policy recommendations for the future low carbon economy development in China. Firstly, comprehensive and long-term planning should be involved in all the low carbon economy pathways. Secondly, to coordinate the relationship between central and local governments and narrow the gap between poor and rich regions, different strategies of carbon emission performance assessment should be applied for different regions. Thirdly, enterprises should cooperate with scientific research institutions to explored low carbon technologies. Finally, relevant institutions should be regulated to realize comprehensive low carbon transition through reasonable and feasible low carbon pathways in China. These policy recommendations will provide new perspectives for China's future low carbon economy development and guide practices for combating climate change.

10.
ACS Appl Mater Interfaces ; 10(1): 668-675, 2018 Jan 10.
Artigo em Inglês | MEDLINE | ID: mdl-29241328

RESUMO

Small molecules (SMs) with elongated backbones are promising for achieving a higher photovoltaic performance. Herein, a dimeric porphyrin small molecule, ZnP2-DPP, consisting of two porphyrin units linked with an ethynylene as the core and two diketopyrrolopyrrole (DPP) units as the arms is designed and synthesized as an electron donor for solution-processed bulk-heterojunction (BHJ) organic solar cells (OSCs). A significantly enhanced power conversion efficiency of 8.45% with an impressive short-circuit current density (Jsc) up to 19.65 mA cm-2 is achieved for the BHJ OSCs based on ZnP2-DPP under AM 1.5G irradiation (100 mW cm-2) compared to that for the OSCs based on the dimeric porphyrin linked with bis-ethynylenes reported previously. Furthermore, the devices show broad photoelectron responses up to 1000 nm with high near-infrared external quantum efficiency up to 66% at 780 nm. This is the first study reporting SM OSCs displaying such a large Jsc of about 20 mA cm-2 simultaneously with a considerably high and deep photoelectron response of up to 1000 nm.

11.
Science ; 358(6366): 1008-1009, 2017 Nov 24.
Artigo em Inglês | MEDLINE | ID: mdl-29170227
12.
ACS Appl Mater Interfaces ; 9(35): 29917-29923, 2017 Sep 06.
Artigo em Inglês | MEDLINE | ID: mdl-28809536

RESUMO

Ternary organic solar cells (OSCs) are very attractive for further enhancing the power conversion efficiencies (PCEs) of binary ones but still with a single active layer. However, improving the PCEs is still challenging because a ternary cell with one more component is more complicated on phase separation behavior. If the two donors or two acceptors have similar chemical structures, good miscibility can be expected to reduce the try-and-error work. Herein, we report ternary devices based on two small molecule donors with the same backbone but different substituents. Whereas both binary devices show PCEs about 9%, the PCE of the ternary cells is enhanced to 10.17% with improved fill factor and short-circuit current values and external quantum efficiencies almost in the whole absorption wavelength region from 440 to 850 nm. The same backbone enables the donors miscible at molecular level, and the donor with a higher HOMO level plays hole relay process to facilitate the charge transportation in the ternary devices. Since side-chain engineering has been well performed to tune the active materials' energy levels in OSCs, our results suggest that their ternary systems are promising for further improving the binary cells' performance although their absorptions are not complementary.

13.
Chem Commun (Camb) ; 53(37): 5113-5116, 2017 May 04.
Artigo em Inglês | MEDLINE | ID: mdl-28435939

RESUMO

Three conjugated D-A porphyrin dimers (DPP-ZnP-E)2, (DPP-ZnP-E)2-2T and (DPP-ZnP-E)2-Ph linked with diethynylene, diethynylene-dithiophene and diethynylene-phenylene have been developed for bulk heterojunction solar cells with high power conversion efficiencies of 4.50%, 5.50% and 6.42%, respectively, when blended with PC61BM as the electron acceptor material.

14.
ACS Appl Mater Interfaces ; 9(8): 7131-7138, 2017 Mar 01.
Artigo em Inglês | MEDLINE | ID: mdl-28185448

RESUMO

A porphyrin-based molecule DPPEZnP-BzTBO with bulky benzothiophene groups was designed and synthesized as an electron donor material for bulk heterojunction (BHJ) solar cells. The optimized devices under thermal annealing (TA) and then chloroform solvent vapor anneanling (SVA) for 80 s exhibited an outstanding power conversion efficiencie (PCE) of 9.08%. Contrasted with the smaller thienyl substituted analogues we reported previously, DPPEZnP-BzTBO-based BHJ solar cells exhibited a higher open circuit voltage due to the lower highest occupied molecular orbital energy level. The TA post-treatment of the active layers induced the formation of more crystallized components, and the subsequent SVA provided a driving force for the domain growth, resulting in more obvious phase segregation between the donor and the acceptor in nanoscale. Furthermore, the PCEs kept above 95% upon the further SVA treatment within the time range of 60 to 95 s probably because the bulky benzothiophene groups retard the too quick change of crystallinity, providing a wide processing window for the reproducible device fabrication.

15.
ACS Appl Mater Interfaces ; 8(44): 30176-30183, 2016 Nov 09.
Artigo em Inglês | MEDLINE | ID: mdl-27731985

RESUMO

To mimic the natural photosynthetic systems utilizing chlorophylls to absorb light and store light energy, two new porphyrin-based small molecules of PTTR and PTTCNR have been developed for photovoltaic applications. The highest power conversion efficiency of 8.21% is achieved, corresponding to a short-circuit current of 14.30 mA cm-2, open-circuit voltage of 0.82 V, and fill factor of 70.01%. The excellent device performances can be ascribed to the engineering of molecule structure and film morphology. The horizontal conjugation of 3,3″-dihexyl-terthiophene to porphyrin-core with the vertical aliphatic 2-octylundecyl peripheral substitutions, can not only effectively increase the solar flux coverage between the conventional Soret and Q bands of porphyrin unit, but also optimize molecular packing through polymorphism associated with side-chains and the linear π-conjugated backbones. And the additive of 1,8-diiodooctane and subsequent chloroform solvent vapor annealing facilitate the formation of the blend films with [6,6]-phenyl-C71-butyric acid methyl ester (PC71BM) characteristics of bicontinuous, interpenetrating networks required for efficient charge separation and transportation.

16.
ACS Appl Mater Interfaces ; 8(41): 28225-28230, 2016 Oct 19.
Artigo em Inglês | MEDLINE | ID: mdl-27696803

RESUMO

By doping ZnO with porphyrin small molecules (FNEZnP-OE and FNEZnP-T) as cathode electron transport layers (ETLs), the inverted polymer solar cells (i-PSC) with PTB7:PC71BM (PTB7: polythieno[3,4-b]-thiophene-co-benzodithiophene, PC71BM:[6, 6]-phenyl-C71-butyric acid methyl ester) as the active materials exhibit enhanced device performance. While the power conversion efficiency (PCE) of the PSCs with pure ZnO ETL is 7.52%, that of the devices with FNEZnP-T-doped ZnO ETL shows a slightly improved PCE of 8.09%, and that of the PSCs with FNEZnP-OE-doped ZnO ETL is further enhanced up to 9.24% with an over 20% improvement compared to that with pure ZnO ETL. The better performance is contributed by the better interfacial contact and reduced work function induced by 9,9-bis(30-(N,N-dimethylamino)propyl)-2,7-fluorenes and 3,4-bis(2-(2-methoxy-ethoxy)-ethoxy)-phenyls in the porphyrin small molecules. More importantly, the PCE is still higher than 8% even when the thickness of FNEZnP-OE-doped ZnO ETL is up to 110 nm, which are important criteria for eventually making organic photovoltaic modules with roll-to-roll coat processing.

17.
Adv Mater ; 28(23): 4727-33, 2016 Jun.
Artigo em Inglês | MEDLINE | ID: mdl-27062394

RESUMO

A new category of deep-absorbing small molecules is developed. Optimized devices driven by mixed additives show a remarkable short-circuit current of ≈20 mA cm(-2) and a highest power conversion efficiency of 9.06%. A multi-length-scale morphology is formed, which is fully characterized by resonant soft X-ray scattering, high-angle annular dark film image transmission electron microscopy, etc.

18.
Chem Sci ; 7(7): 4301-4307, 2016 Jul 01.
Artigo em Inglês | MEDLINE | ID: mdl-30155076

RESUMO

Porphyrin-based small molecules as donors have long been ignored in bulky heterojunction organic solar cells due to their unfavorable aggregation and the low charge mobility. With the aim of striking a delicate balance between molecular design, morphology, interfacial layer and device fabrication to maximize the power conversion efficiency (PCE) of organic solar cells, three comparable porphyrin-based small molecules with an acceptor-donor-acceptor configuration have been developed for use as donor materials in solution processed small molecule bulk heterojunction organic solar cells. In these molecules, electron-deficient 3-ethylrhodanine is introduced into the electron-rich porphyrin core through 5,15-bis(phenylethynyl) linkers. Structural engineering with 10,20-bis(2-hexylnonyl) aliphatic peripheral substituent on the porphyrin core, instead of the aromatic substituents such as 10,20-bis[3,5-di(dodecyloxyl)phenyl], and 10,20-bis(4-dodecyloxylphenyl), can simultaneously facilitate stronger intermolecular π-π stacking and higher charge transfer mobility in the film, leading to a maximum PCE of 7.70% in a conventional device. The inverted devices have also been demonstrated to have long-term ambient stability and a comparable PCE of 7.55%.

19.
ACS Appl Mater Interfaces ; 7(38): 21495-502, 2015 Sep 30.
Artigo em Inglês | MEDLINE | ID: mdl-26355348

RESUMO

Solvent additive processing is important in optimizing an active layer's morphology and thus improving the performance of organic solar cells (OSCs). In this study, we find that how 1,8-diiodooctane (DIO) additive is removed plays a critical role in determining the film morphology of the bulk heterojunction OSCs in inverted structure based on a porphyrin small molecule. Different from the cases reported for polymer-based OSCs in conventional structures, the inverted OSCs upon the quick removal of the additive either by quick vacuuming or methanol washing exhibit poorer performance. In contrast, the devices after keeping the active layers in ambient pressure with additive dwelling for about 1 h (namely, additive annealing) show an enhanced power conversion efficiency up to 7.78% with a large short circuit current of 19.25 mA/cm(2), which are among the best in small molecule-based solar cells. The detailed morphology analyses using UV-vis absorption spectroscopy, grazing incidence X-ray diffraction, resonant soft X-ray scattering, and atomic force microscopy demonstrate that the active layer shows smaller-sized phase separation but improved structure order upon additive annealing. On the contrary, the quick removal of the additive either by quick vacuuming or methanol washing keeps the active layers in an earlier stage of large scaled phase separation.

20.
Chem Commun (Camb) ; 51(77): 14439-42, 2015 Oct 04.
Artigo em Inglês | MEDLINE | ID: mdl-26248887

RESUMO

A series of unsymmetrical π-conjugated small molecules have been constructed from meso-alkyl substituted porphyrins as the central unit and 3-ethylrhodanine as the terminal group. Using PC71BM as an acceptor, and these small molecules as electron donors in solution-processed bulk-heterojunction solar cells, a high power conversion efficiency of 6.49% has been achieved.

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