Octylammonium Iodide Induced in-situ Healing Behavior at Perovskite / Carbon Interface: the "Slow-Release Effect" Caused by Carbon Black Adsorption.

"Perovskite / Carbon" interface has remained a key bottleneck for the hole-conductor-free perovskite solar cells based on carbon-electrode (CPSCs), due to problems like loose physics contact, defects, energy mismatch, poor chemical coupling, etc. A previous study shows that octylammonium iodide (OAI) blending in carbon paste induced a kind of "in-situ healing" effect for "perovskite / carbon" interface, and improved power conversion efficiency from ≈13% to >19%. Here the beneath mechanism is further explored by careful examination of the interaction between OAI molecule and carbon black (CB) nanoparticles. It comes to show that, the famous "CB adsorption" plays a key role during the "healing" processes. Due to CB adsorption behavior, the mass ratio between OAI and CB influences much on the healing effect. By suitably adjusting the mass ratio between OAI and CB, and increasing the light harvest of perovskite, an efficiency of 19.41% is achieved for the hole-conductor-free CPSCs. Device efficiency and the charge-extraction and recombination process are tracked with the storage period, continuous improvement appears for devices assembled by relatively higher CB mass. A kind of "slow-release effect" is revealed during the OAI-induced "in-situ healing" process, which is caused by the famous "CB adsorption" behavior.

Metabolic effects of diclofenac on the aquatic food chain - 1 H-NMR study of water flea-zebrafish system.

In the environment, aquatic organisms are not only directly exposed to pollutants, but the effects can be exacerbated along the food chain. In this study, we investigated the effect of the food (water flea) on the secondary consumer (zebrafish) with the exposure diclofenac (DCF) Both organisms were exposed to an environmentally relevant concentrations (15 µg/L) of diclofenac for five days, and zebrafish were fed exposed and non-exposed water fleas, respectively. Metabolites of the water fleas were directly analyzed using HRMAS NMR, and for zebrafish, polar metabolite were extracted and analyzed using liquid NMR. Metabolic profiling was performed and statistically significant metabolites which affected by DCF exposure were identified. There were more than 20 metabolites with variable importance (VIP) score greater than 1.0 in comparisons in fish groups, and identified metabolites differed depending on the effect of exposure and the effect of food. Specifically, exposure to DCF significantly increased alanine and decreased NAD + in zebrafish, which means energy demand was increased. Additionally, the effects of exposed food decreased in guanosine, a neuroprotective metabolite, which explained that the neurometabolic pathway was perturbated by the feeding of exposed food. Our results which short-term exposed primary consumers to pollutants indirectly affected the metabolism of secondary consumers suggest that the long-term exposure further study remains to be investigated.

A Theranostic Probe for Promotion of Skin Wound Healing by Exudate-Triggered H2S Release with Self-Monitoring Ability.

Hydrogen sulfide (H2S) as an endogenous gasotransmitter plays a critical role in promotion of wound healing. However, the current H2S release system lacks the in situ monitoring ability, which may lead to insufficient or overdose release of H2S and serious side effects. Herein, we develop a self-monitoring theranostic probe TPATCF-S, which can quickly release H2S under water stimuli associated with a self-monitoring ability by a color change from colorless to deep blue. With a full thickness dermal defect as a model, the TPATCF-S absorbed on alginate dressings can be used for wound exudate-responsive release of H2S to efficiently promote skin wound healing.

Multiple amplification-based fluorometric aptasensor for highly sensitive detection of Staphylococcus aureus.

Rapid and accurate detection and identification of Staphylococcus aureus (S. aureus) are of great significance for food safety, environmental monitoring, early clinical diagnosis, and prevention of the spread of drug-resistant bacteria. Herein, we design a fluorometric aptasensor for ultra-sensitive, specific, and rapid detection of S. aureus. The apasensor combines the enrichment and separation of magnetic nanoparticles (MNPs), the biotin-streptavidin conjugation system, and a single S. aureus can release four signaling probes for signal amplification. Aptamer acts as a specific biorecognition element of S. aureus. Four FAM-labeled partially complementary sequences (FAM-pcDNAs) were used as signaling probes. The aptamers were sequential hybridized with the four FAM-pcDNAs to form aptamer&pcDNAs, which were then bound to MNPs via the biotin-streptavidin. When the aptamer specifically recognizes and binds to S. aureus, the FAM-pcDNAs signaling probes are replaced and released into the supernatant. The concentration of S. aureus can be quantified by measuring the fluorescence intensity (λexc/em = 492/520 nm) of the replaced signaling probe FAM-pcDNAs. The results show that the proposed fluorometric aptasensor displays good specificity, ultra-high sensitivity (1.23 cfu/mL), wide linear range (1 ~ 108 cfu/mL), and fast detection speed (~ 1.5 h). The recovery test verifies further that the proposed fluorometric aptasensor can detect S. aureus in spiked blood samples. Since aptamers are easy to customize, we believe that fluorometric aptasensors based on multiple amplification have broad prospects in the construction of practical high-performance biosensors for bacterial detection. KEY POINTS: • Multiple amplification-based fluorometric aptasensor for S. aureus is developed • The aptasensor displays high specificity with a LOD of 1.23 CFU/mL • The aptasensor can directly detect S. aureus in spiked blood samples.

Can Vacuum Deposition Apply to Bismuth-Doped γ-CsPbI3 Perovskite? Revealing the Role of Bi3+ in the Formation of Black Phase.

The B-site doped CsPbI3 has been demonstrated to be very promising for photovoltaics owing to its low black phase transition temperature. Though B-site doped black-CsPbI3 perovskites have been successfully achieved by solution-processing, it is unclear whether these systems are available by other methods such as vacuum deposition. In this work, heterovalent doped CsPb1-xBixI3 is targeted. To incorporate Bi3+ into the final film via vacuum deposition, the solid solution precursor Pb1-xBixI2 (0.01 ≤ x ≤ 0.04) is developed. However, these coevaporated films not only are dominated by another hexagonal perovskite phase but also fail to decrease the black phase transition temperature. The role of Bi3+ in the formation of the black phase is further studied by solution methods with different types of precursors. It is demonstrated that the key factor in the low-temperature black phase transition is small grain size, as well as the colloid size within the precursor solution, rather than simple substitution of Pb2+ with Bi3+.

An asymmetric semi-circular bend method for investigating fracture behavior of brittle rocks under dynamic mixed mode I/II loading.

Understanding the fracture behavior of brittle rocks under dynamic mixed mode I/II loading is imperative and beneficial for the stability analysis of rock engineering structures. However, available research studies on the dynamic mixed mode fracture of brittle rocks are rather rare, and existing testing methods own some complexity in the specimen preparation or experimental operation. In this study, a novel and efficient experimental method is developed for investigating the fracture behavior of brittle rocks under mixed mode I/II impact loading. For the first time, the asymmetric semi-circular bend (ASCB) specimen is introduced into a split Hopkinson pressure bar loading system to obtain dynamic mixed mode fracture toughness of granite. By virtue of digital image correlation techniques combined with high-speed photography, the progressive fracture processes of specimens with different mode mixity are also visualized. Results show that the dynamic force equilibrium and the crack tip initiation are satisfied for all the tests, validating the feasibility and reliability of this method. The fracture path of the ASCB specimen under dynamic mixed mode I/II loading deviates from the original loading direction and finally generates a curved crack, which is quite different from the straight fracture path under pure mode I loading. In addition, experimental results indicate the significant loading rate dependence of the dynamic fracture toughness, and the dynamic effective fracture toughness under mode I loading is greater than that under mode II loading at a given loading rate. Our proposed method is convenient and reliable to investigate dynamic mixed mode I/II fracture of brittle rocks.

Substituent Effect on the Selective Separation and Complexation of Trivalent Americium and Lanthanides by N,O-Hybrid 2,9-Diamide-1,10-phenanthroline Ligands in Ionic Liquid.

The extraction and complexation of trivalent americium (Am) and lanthanides (Ln) by four 2,9-diamide-1,10-phenanthroline (DAPhen) ligands with different alkyl substituent groups on the diamide moiety in an ionic liquid (IL), C4mimNTf2, were studied through a combination of batch extraction, spectroscopic, and calorimetric approaches. All four DAPhen ligands can achieve selective separation of Am(III) from Eu(III), but the detailed extractability and the extraction kinetics are affected significantly by the length of the alkyl substituent groups. UV-vis absorption spectrophotometric titrations indicate that Ln(III) coordinates with all four ligands in a 1:2 mode in the ionic liquid and the binding strength decreases with the increase of the alkyl chain length. The complexation of the DAPhen ligands with Ln(III) in the ionic liquid is driven by highly positive entropies and opposed by endothermic enthalpies. A luminescence spectroscopy study suggests that each DAPhen ligand coordinates in a tetradentate form with Eu(III). This work further unravels the unique extraction and coordination behavior in an ionic liquid system and offers additional guidelines to design more efficient DAPhen ligands for Ln(III)/An(III) separation.

Complexation and Separation of Trivalent Actinides and Lanthanides by a Novel DGA Derived from Macrocyclic Crown Ether: Synthesis, Extraction, and Spectroscopic and Density Functional Theory Studies.

A DGA-arm-grafted macrocyclic aza-crown ether ligand (Cr6DGA) was synthesized, and its solvent extraction behavior toward trivalent americium and europium in nitric acid medium was studied. The effects of various parameters such as the contact time, temperature, concentration of the extractant, and acidity on the extraction by Cr6DGA were investigated. It was found that in 3 mol/L HNO3, the SFEu/Am value was about 2. The complexation energies calculated by DFT showed that the Eu(III) complexes were more stable than the corresponding Am(III) complexes in gas, aqueous, and organic phases. Furthermore, the coordination study showed that the metal/ligand ratio of the extracted species was 1:2 by mass spectrometry (MS) analysis. The time-resolved laser-induced fluorescence spectra (TRLFS) further proved that the extracted species contained one water molecule, and so the composition of the extracted complexes may be [EuL2NO3(H2O)]2+ or [EuL2(NO3)2(H2O)]+. Finally, DFT calculations revealed that [EuL2(NO3)2(H2O)]+ is a more stable species and the binding energy of Eu(III) with the DGA unit is lower than that with the crown unit.

Modification of an ultrathin C60 interlayer on the electronic structure and molecular packing of C8-BTBT on HOPG.

X-ray photoelectron spectroscopy (XPS), ultraviolet photoelectron spectroscopy (UPS), atomic force microscopy (AFM) and X-ray diffraction (XRD) were applied to investigate the electronic structure and molecular packing of C8-BTBT on HOPG with an ultrathin C60 interlayer. It was found that C8-BTBT displays a Vollmer-Weber (V-W) growth mode on HOPG, with an ultrathin C60 interlayer (0.7 nm). Compared to the uniform lying-down growth mode as directly grown on HOPG, the C8-BTBT molecules here adopt a lying-down orientation at low coverage with some small tilt angles because the π-π interaction between C8-BTBT and HOPG is partly disturbed by the C60 interlayer, delivering a higher highest occupied molecular orbital (HOMO) in C8-BTBT. An interface dipole of 0.14 eV is observed due to electron transport from C8-BTBT to C60. The upward and downward band bending in C8-BTBT and C60, respectively, near the C8-BTBT/C60 interface reduces the hole transport barrier at the interface, facilitating the hole injection from C60 to C8-BTBT, while a large electron transfer barrier from C60 to C8-BTBT is detected at this interface, which effectively limits electron injection from C60 to C8-BTBT. The HOMO of C8-BTBT near the interface is largely lifted up by the C60 insertion layer, which causes a p-doping effect and increases the hole mobility in C8-BTBT. Furthermore, owing to the lowest occupied molecular orbital (LUMO) of C60 residing in the gap of C8-BTBT, charge transfer occurs between C60 and the trap states in C8-BTBT to effectively passivate the trapping states. Our efforts aid a better understanding of the electron structure and film growth of anisotropic molecules and provide a useful strategy to improve the performance of C8-BTBT-based devices.

Type-II Interface Band Alignment in the vdW PbI2-MoSe2 Heterostructure.

Energy band alignments at heterostructure interfaces play key roles in device performance, especially between two-dimensional atomically thin materials. Herein, van der Waals PbI2-MoSe2 heterostructures fabricated by in situ PbI2 deposition on monolayer MoSe2 are comprehensively studied using scanning tunneling microscopy/spectroscopy, atomic force microscopy, photoemission spectroscopy, and Raman and photoluminescence (PL) spectroscopy. PbI2 grows on MoSe2 in a quasi layer-by-layer epitaxial mode. A type-II interface band alignment is proposed between PbI2 and MoSe2 with the conduction band minimum (valence band maximum) located at PbI2 (MoSe2), which is confirmed by first-principles calculations and the existence of interfacial excitons revealed using temperature-dependent PL. Our findings provide a scalable method to fabricate PbI2-MoSe2 heterostructures and new insights into the electronic structures for future device design.

Performance and Mechanism for the Selective Separation of Trivalent Americium from Lanthanides by a Tetradentate Phenanthroline Ligand in Ionic Liquid.

The selective separation of trivalent americium from lanthanides in a nitric acid medium by a tetradentate ligand, N,N'-diethyl-N,N'-ditolyl-2,9-diamide-1,10-phenanthroline (Et-Tol-DAPhen), in an ionic liquid (IL), C4mimNTf2, was studied by batch solvent extraction and spectroscopic approaches. The effect of various parameters such as the contact time, temperature, extractant concentration, and acidity on the extraction of Am3+ and Eu3+ have been evaluated. A significant enhancement in the extraction ability of Et-Tol-DAPhen dissolved in IL was observed as compared to that in molecular diluents under low-acid conditions. The chemical stoichiometry of Am3+ and Eu3+ complexes during extraction was determined to be 1:2 (metal/ligand) by slope analysis of the extraction data. The extraction mechanism of Am3+ and Eu3+ by Et-Tol-DAPhen in IL was determined to be cation exchange on the basis of the effect of nitrate, NTf2-, and C4mim+ ions on extraction. The coordination chemistry of Ln3+ with the ligand in C4mimNTf2 was studied by spectroscopic titrations, which helped to further identify and confirm the extracted species as well as the extraction mechanism. Results from the present study emphasize the unique role of IL in altering the extraction behavior and suggest that the Et-Tol-DAPhen/IL system has potential applications in trivalent actinide/lanthanide separation under low-acid conditions.

Cerebrolysin Ameliorates Focal Cerebral Ischemia Injury Through Neuroinflammatory Inhibition via CREB/PGC-1α Pathway.

Neuroinflammation is one of the important factors aggravating brain injury after ischemic stroke. We aimed to investigate the effects of cerebrolysin (CBL) on neuroinflammation in vivo and in vitro and the underlying mechanisms. The gene expressions of pro-inflammatory factors and anti-inflammatory factors were analyzed by real time PCR in rat transient middle cerebral artery occlusion (tMCAO) model, lipopolysaccharides-induced neuroinflammatory mice model and LPS-treated mouse primary microglia cells. The neuroprotective effects of CBL were evaluated by infarct size, Longa test and Rotarod test for long-term functional recovery in rats subjected to ischemia. The role of CREB/PGC-1α pathway in anti-neuroinflammatory effect of CBL was also determined by real time PCR and Western blotting. In the tMCAO model, administration of CBL at 3 h post-ischemia reduced infarct volume, promoted long-term functional recovery, decreased the gene expression of pro-inflammatory factors and increased the gene expression of anti-inflammatory factors. Correspondingly, in LPS-induced neuroinflammatory mice model, CBL treatment attenuated sickness behavior, decreased the gene expression of pro-inflammatory factors, and increased the gene expression of anti-inflammatory factors. In in vitro and in vivo experiments, CBL increased the protein expression levels of PGC-1α and phosphorylated CREB to play anti-inflammatory effect. Additionally, the application of the specific CREB inhibitor, 666-15 compound could effectively reverse the anti-inflammatory effect of CBL in primary mouse microglia cells and anti-ischemic brain injury of CBL in rats subjected to tMCAO. In conclusion, CBL ameliorated cerebral ischemia injury through reducing neuroinflammation partly via the activation of CREB/PGC-1α pathway and may play a therapeutic role as anti-neuroinflammatory agents in the brain disorders associated with neuroinflammation.

Structural and Stability Trends of the Complexation of Hexavalent Actinides with Two Dipicolinic Acid Derivatives: An Experimental and Theoretical Study.

Revealing the complexation behavior of high-valent actinides in solutions is of great importance to better understand the fundamental chemistry of actinides as well as to control the separation property of actinides in nuclear fuel cycles. In this work, the complexation of hexavalent actinide cations U(VI), Np(VI), and Pu(VI) with two dipicolinic acid derivatives, 6-(dimethylcarbamoyl)picolinic acid (DMAPA, denoted as HL) and N2,N2,N6,N6-tetramethylpyridine-2,6-dicarboxamide (TMPDA), in aqueous solutions were investigated by absorption spectrophotometry, X-ray crystallography, and DFT calculations. Formation of 1/1 and 1/2 (metal:ligand) complexes of U(VI), Np(VI), and Pu(VI) with DMAPA were identified and the corresponding stability constants were determined. The binding strengths of the three hexavalent actinide cations with DMAPA follow the order of U(VI) > Np(VI) > Pu(VI) in both 1/1 and 1/2 complexes, indicating that the driving force for the complexation is mainly electrostatic interactions. In addition, the relationships between the features of the absorption spectra and the symmetry of Pu(VI) and Np(VI) complexes with DMAPA have been established. The crystal structure of the 1/2 U(VI)/DMAPA complex as well as the DFT optimized structures of An(VI)/DMAPA complexes shed additional light on the structural characters of the hexavalent actinide cation complexes. In contrast to DMAPA, TMPDA exhibits no observable complexation with the three hexavalent actinide cations in aqueous solution, which could be attributed to low electron density on the donor atoms of TMPDA as well as steric hindrance effect by dimethyl carbamoyl groups as elucidated by DFT calculations. The results from this work provide new insights into the complexation trends of hexavalent actinide cations in aqueous solutions.

PbI2-MoS2 Heterojunction: van der Waals Epitaxial Growth and Energy Band Alignment.

van der Waals (vdW) epitaxy offers a promising strategy without lattice and processing constraints to prepare atomically clean and electronically sharp interfaces for fundamental studies and electronic device demonstrations. Herein, PbI2 was thermally deposited at high-vacuum conditions onto CVD-grown monolayer MoS2 flakes in a vdW epitaxial manner to form 3D-2D heterojunctions, which are promising for vdW epitaxial growth of perovskite films. X-ray diffraction, X-ray photoemission spectroscopy, Raman, and atomic force microscopy measurements reveal the structural properties of the high-quality heterojunctions. Photoluminescence (PL) measurements reveal that the PL emissions from the bottom MoS2 flakes are greatly quenched compared to their as-grown counterparts, which can be ascribed to the band alignment-induced distinct interfacial charge-transfer behaviors. Strong interlayer excitons can be detected at the PbI2/MoS2 interface, indicating an effective type II band alignment, which can be further confirmed by ultraviolet photoemission spectroscopy measurements. The results provide a new material platform for the application of the vdW heterojunctions in electronic and optoelectronic devices.

A homogeneous p-n junction diode by selective doping of few layer MoSe2 using ultraviolet ozone for high-performance photovoltaic devices.

The realization of p-n homojunctions, which can be achieved via spatially controlled carrier-type modulation, remains a challenge for two-dimensional transition metal dichalcogenides. Here, we report an effective method to tune intrinsic n-type few-layer MoSe2 to p-type through controlling precisely the ultraviolet-ozone treatment time, which can be attributed to the surface charge transfer from the underlying MoSe2 to MoOx (x < 3). The resulting hole mobility and concentration are ∼20.1 cm2 V-1 s-1 and ∼1.9 × 1012 cm-2, respectively, and the on-off ratio is ∼105, which are comparable to the values of pristine n-type MoSe2. Moreover, the lateral p-n homojunction prepared by partially treating MoSe2 displays a high rectification ratio of 2.4 × 104, an ideality factor of 1.1, and a high photoresponsivity of 0.23 A W-1 to the 633 nm laser at Vd = 0 V and Vg = 0 V due to the built-in potential in the p-n homojunction area. Our findings ensure the MoSe2 p-n diode as a promising candidate for future low-power operating photodevices.

Selective Separation and Complexation of Trivalent Actinide and Lanthanide by a Tetradentate Soft-Hard Donor Ligand: Solvent Extraction, Spectroscopy, and DFT Calculations.

Recently, phenanthroline-based ligands have received increasing attention due to their excellent separation capabilities for trivalent actinides over lanthanide. In this work, we designed a soft-hard donor combined tetradentate phenanthroline-based extractant, tetraethyl (1,10-phenanthrolin-2,9-diyl)phosphonate (C2-POPhen), for the selective separation of trivalent Am(III) over Ln(III) from HNO3 media. The solvent extraction and complexation behaviors of Am(III) and Ln(III) by C2-POPhen were investigated both experimentally and theoretically. C2-POPhen could selectively extract Am(III) over Eu(III) with an extremely fast extraction kinetics. NMR titration studies suggest that only 1:1 complexes of Ln(III) with C2-POPhen formed in CH3OH in the presence of a significant amount of nitrate, while both 1:1 and 2:1 complexes species could form between C2-POPhen and Ln(III) perchlorate in CH3OH without nitrate ions. The stability constants for the complexation of Am(III) and Ln(III) with C2-POPhen in CH3OH were determined by spectrophotometric titrations and the Am(III) complexes are approximately 1 order of magnitude stronger than those of Ln(III), which is consistent with the extraction results. Theoretical calculations indicate that the Am-N bonds in Am/C2-POPhen complexes possess more covalent characters than the Eu-N bonds in Eu/C2-POPhen complexes, shedding light on the underlying chemical force responsible for the Am/Eu selectivity by C2-POPhen. This work represents the first report utilizing phenanthroline-based phosphonate ligands for selective separation of actinides from highly acidic solutions.

Complexation of Pu(vi) with N,N,N',N'-tetramethyl-3-oxa-glutar-amide (TMOGA) and related ligands: optical properties and coordination modes.

The complexation of hexavalent plutonyl Pu(vi) with N,N,N',N'-tetramethyl-3-oxa-glutar-amide (TMOGA) and its carboxylate analogs, N,N-dimethyl-3-oxa-glutaramic acid (DMOGA) and oxydiacetic acid (ODA), has been studied in 1.0 M NaClO4 by absorption spectrophotometry and density functional theory (DFT). Both 1 : 1 and 1 : 2 complexes of Pu(vi) with TMOGA, DMOGA and ODA have been identified and their stability constants were obtained and compared with those of hexavalent U(vi) and pentavalent Np(v). The resultant stability constants indicate that the ability of the three ligands to complex with Pu(vi) decreases in the order of ODA > DMOGA > TMOGA. While for one given ligand, the stability constants of both the 1 : 1 and 1 : 2 complexes decrease generally in the order U(vi) > Pu(vi) > Np(v). The trends of the complexation strength have been elucidated by the calculated Mulliken atomic charges of the central metal cations. Furthermore, the coordination modes of the Pu(vi) complexes with TMOGA, DMOGA and ODA have been illustrated by analyses of the optical features of the complexes as well as by DFT calculations. The results demonstrate that the 1 : 2 Pu(vi)/TMOGA complex is centrosymmetric, while the 1 : 2 complexes of Pu(vi) with DMOGA and ODA are non-centrosymmetric. Moreover, different coordination modes have been observed in actinyl complexes with the same ligand, suggesting the structurally similar actinyl ions (U(vi), Pu(vi) and Np(v)) could exhibit quite different coordination behavior due to the variation of cation size and electronic structure.

[Hypopharyngeal and cervical esophageal repairing].

OBJECTIVE: To explore the ways of repairing the hypopharyngeal and cervial esophageal breach postoperatively. METHOD: 6 kinds of operations in 29 patients with hypopharyngeal and cervical esophageal repairing were analyzed. RESULT: In 9 patients laryngeal function reserved, 8 cases recovered their function of swallow and speech postoperatively. One received a laryngectomy in II stage for wrong swallow. In 20 cases without laryngeal function, 17 cases can swallow, but 3 cases had fistula. The 1, 3 and 5 year survival rates were 92%, 64.7% and 46.2% respectively. CONCLUSION: The firsthand suture and pectoralis major myocutaneous flap were better for the hypopharyngeal repairing of the patients with laryngeal function. The glossus flap, laryngeal tissue flap, pectoralis major myocutaneous flap and gastric-pharyngeal tally are useful for the digestive canal reconstruction of the patients with laryngectomy.