Recent Advances of Flexible MXene and its Composites for Supercapacitors.

MXenes have unique properties such as high electrical conductivity, excellent mechanical properties, rich surface chemistry, and convenient processability. These characteristics make them ideal for producing flexible materials with tunable microstructures. This paper reviews the laboratory research progress of flexible MXene and its composite materials for supercapacitors. And introduces the general synthesis method of MXene, as well as the preparation and properties of flexible MXene. By analyzing the current research status, the electrochemical reaction mechanism of MXene was explained from the perspectives of electrolyte and surface terminating groups. This review particularly emphasizes the composite methods of freestanding flexible MXene composite materials. The review points out that the biggest problem with flexible MXene electrodes is severe self-stacking, which reduces the number of chemically active sites, weakens ion accessibility, and ultimately lowers electrochemical performance. Therefore, it is necessary to composite MXene with other electrode materials and design a good microstructure. This review affirms the enormous potential of flexible MXene and its composite materials in the field of supercapacitors. In addition, the challenges and possible improvements faced by MXene based materials in practical applications were also discussed.

Dexamethasone Pretreatment Potentiates a Folic Acid-Functionalized Delivery System for Enhanced Lung Cancer Therapy.

Folic acid (FA) has been widely engineered to promote the targeted delivery of FA-modified nanoparticles (NPs) by recognizing the folate receptor α (FRα). However, the efficacy of FA-targeted therapy significantly varied with the abundance of FRα and natural immunoglobulin levels in different tumors. Therefore, a sequential therapy of dexamethasone (Dex)-induced FRα amplification and immunosuppression combined with FA-functionalized doxorubicin (DOX) micelles to synergistically suppress tumor proliferation was proposed in this study. In brief, a pH/reduction-responsive FA-functionalized micelle (FCSD) was obtained by grafting FA, derivatization-modified cholesterol, and 2,3-dimethylmaleic anhydride onto a chitosan oligosaccharide. The obtained FCSD/DOX NPs can effectively deliver DOX in tumors, and their targeting efficiency can be further improved with Dex pretreatment to decrease the immunoglobulin M (IgM) content in serum and amplify FRα levels on the surface of M109 cells. After internalization, charge reversal and disulfide bond breakage of FCSD vectors under the stimulation of tumor extracellular pH (pHe) and intracellular glutathione (GSH) would contribute to the disintegration of vectors and the rapid release of DOX. The sequential therapy that combined Dex pretreatment and targeted chemotherapy by FCSD/DOX NPs demonstrated superior tumor suppression compared with monotherapy, which is expected to provide a potential strategy for FRα-positive lung cancer patients.

Purple acid phosphatase 10c encodes a major acid phosphatase that regulates plant growth under phosphate-deficient conditions in rice.

Whilst constitutive overexpression of particular acid phosphatases (APases) can increase utilization of extracellular organic phosphate, negative effects are frequently observed in these transgenic plants under conditions of inorganic phosphate (Pi) sufficiency. In this study, we identified rice purple acid phosphatase 10c (OsPAP10c) as being a novel and major APase that exhibits activities associated both with the root surface and with secretion. Two constructs were used to generate the OsPAP10c-overexpression plants by driving its coding sequence with either a ubiquitin promoter (UP) or the OsPAP10c-native promoter (NP). Compared with the UP transgenic plants, lower expression levels and APase activities were observed in the NP plants. However, the UP and NP plants both showed a similar ability to degrade extracellular ATP and both promoted root growth. The growth performance and yield of the NP transgenic plants were better than the wild-type and UP plants in both hydroponic and field experiments irrespective of the level of Pi supply. Overexpression of APase by its native promoter therefore provides a potential way to improve crop production that might avoid increased APase activity in untargeted tissues and its inhibition of the growth of transgenic plants.

Unique Structures and Vibrational Spectra of Protic Ionic Liquids Confined in TiO2 Slits: The Role of Interfacial Hydrogen Bonds.

The ionic liquid (IL)/titanium dioxide (TiO2) interface exists in many application systems, such as nanomaterial synthesis, catalysis, and electrochemistry systems. The nanoscale interfacial properties in the above systems are a common issue. However, directly detecting the interfacial properties of nanoconfined ILs by experimental methods is still challenging. To help better learn about the interfacial issue, molecular dynamics simulations have been performed to explore the structures, vibration spectra, and hydrogen bond (HB) properties at the IL/TiO2 interface. Ethylammonium nitrate (EAN) ILs confined in TiO2 slit pores with different pore widths were studied. A unique vibrational spectrum appeared for EAN ILs confined in a 0.7 nm TiO2 slit, and this phenomenon is related to interfacial hydrogen bonds (HBs). An analysis of the HB types indicated that the interfacial NH3+ group of the cations was in an asymmetric HB environment in the 0.7 nm TiO2 slit, which led to the disappearance of the symmetric N-H stretching mode. In addition, the significant increase in the HB strength between NH3+ groups and the TiO2 surface slowed down the stretching vibration of the N-H bond, resulting in one peak in the vibrational spectra at a lower frequency. For the first time, our simulation work establishes a molecular-level relationship between the vibrational spectrum and the local HB environment of nanoconfined ILs at the IL/TiO2 interface, and this relationship is helpful for interface design in related systems.

OsPAP26 Encodes a Major Purple Acid Phosphatase and Regulates Phosphate Remobilization in Rice.

During phosphate (Pi) starvation or leaf senescence, the accumulation of intracellular and extracellular purple acid phosphatases (PAPs) increases in plants in order to scavenge organic phosphorus (P). In this study, we demonstrated that a PAP-encoding gene in rice, OsPAP26, is constitutively expressed in all tissues. While the abundance of OsPAP26 transcript is not affected by Pi supply, it is up-regulated during leaf senescence. Furthermore, Pi deprivation and leaf senescence greatly increased the abundance of OsPAP26 protein. Overexpression or RNA interference (RNAi) of OsPAP26 in transgenic rice significantly increased or reduced APase activities, respectively, in leaves, roots and growth medium. Compared with wild-type (WT) plants, Pi concentrations of OsPAP26-overexpressing plants increased in the non-senescing leaves and decreased in the senescing leaves. The increased remobilization of Pi from the senescing leaves to non-senescing leaves in the OsPAP26-overexpressing plants resulted in better growth performance when plants were grown in Pi-depleted condition. In contrast, OsPAP26-RNAi plants retained more Pi in the senescing leaves, and were more sensitive to Pi starvation stress. OsPAP26 was found to localize to the apoplast of rice cells. Western blot analysis of protein extracts from callus growth medium confirmed that OsPAP26 is a secreted PAP. OsPAP26-overexpressing plants were capable of converting more ATP into inorganic Pi in the growth medium, which further supported the potential role of OsPAP26 in utilizing organic P in the rhizosphere. In summary, we concluded that OsPAP26 performs dual functions in plants: Pi remobilization from senescing to non-senescing leaves; and organic P utilization.

Mg2+-Channel-Inspired Nanopores for Mg2+/Li+ Separation: The Effect of Coordination on the Ionic Hydration Microstructures.

The separation behaviors of Mg2+ and Li+ were investigated using molecular dynamics. Two functionalized graphene nanopore models (i.e., co_5 and coo_5) inspired by the characteristic structural features of Mg2+ channels were used. Both nanopores exhibited a higher preference to Mg2+ than to Li+, and the selectivity ratios were higher for coo_5 than for co_5 under all the studied transmembrane voltages. An evaluation of the effect of coordination on the ionic hydration microstructures for both nanopores showed that the positioning of the modified groups could better fit a hydrated Mg2+ than a hydrated Li+, as if Mg2+ was not dehydrated according to hydrogen bond analysis of the ionic hydration shells. This condition led to a lower resistance for Mg2+ than for Li+ when traveling through the nanopores. Moreover, a distinct increase in hydrogen bonds occurred with coo_5 compared with co_5 for hydrated Li+, which made it more difficult for Li+ to pass through coo_5. Thus, a higher Mg2+/Li+ selectivity was found in for coo_5 than for co_5. These findings provide some design principles for developing artificial Mg2+ channels, which have potential applications as Mg2+ sensors and novel devices for Mg2+/Li+ separation.

CO2 Absorption in the Ionic Liquids Immobilized on Solid Surface by Molecular Dynamics Simulation.

Based on our previous experimental research, we studied the absorption of CO2 in the ionic liquid, 1-hexyl-3-methylimidazolium bis(trifluoromethylsulfonyl)imide ([hmim][Tf2N]), immobilized on TiO2 [rutile (110) ] with different thickness by molecular dynamics simulation. The effects of the properties (hydrophobicity and hydrophilicity) of solid interfaces were also studied with IL immobilized on graphite and TiO2, respectively. We studied the influence of the thickness of IL immobilized on TiO2 on the absorption of CO2 via structural and dynamical properties. The results show that the self-diffusion coefficients of IL and CO2 increase as the thickness of immobilized IL decreases. And the CO2 absorption capacity increases as the thickness of immobilized IL decreases as well. Additionally, more CO2 molecules are absorbed in the region near the solid interface as the thickness of IL decreases. For IL immobilized on graphite, the self-diffusion coefficients of cations and anions are larger than that of IL immobilized on TiO2 with the same thickness. They are also larger than nonimmobilized cations and anions.Besides, the CO2 absorption capacity of IL immobilized on TiO2 is the largest compared with IL immobilized on graphite and nonimmobilized IL with the same thickness. From our simulation work, we try to explore the microscopic mechanism that is unexplored by experimental work, and we found the important role of IL/solid interface for CO2 absorption in immobilized ILs.

Effect of Adsorbed Alcohol Layers on the Behavior of Water Molecules Confined in a Graphene Nanoslit: A Molecular Dynamics Study.

With the rapid development of a two-dimensional (2D) nanomaterial, the confined liquid binary mixture has attracted increasing attention, which has significant potential in membrane separation. Alcohol/water is one of the most common systems in liquid-liquid separation. As one of the most focused systems, recent studies have found that ethanol molecules were preferentially adsorbed on the inner surface of the pore wall and formed an adsorbed ethanol layer under 2D nanoconfinement. To evaluate the effect of the alcohol adsorption layer on the mobility of water molecules, molecular simulations were performed to investigate four types of alcohol/water binary mixtures confined under a 20 Å graphene slit. Residence times of the water molecules covering the alcohol layer were in the order of methanol/water < ethanol/water < 1-propanol/water < 1-butanol/water. Detailed microstructural analysis of the hydrogen bonding (H-bond) network elucidated the underlying mechanism on the molecular scale in which a small average number of H-bonds between the preferentially adsorbed alcohol molecules and the surrounding water molecules could induce a small degree of damage to the H-bond network of the water molecules covering the alcohol layer, resulting in the long residence time of the water molecules.

Molecular Interactions of Protein with TiO2 by the AFM-Measured Adhesion Force.

Understanding the interactions between porous materials and biosystems is of great important in biomedical and environmental sciences. Upon atomic force microscopy (AFM) adhesion measurement, a new experimental approach was presented here to determine the molecular interaction force between proteins and mesoporous TiO2 of various surface roughnesses. The interaction force between each protein molecule and the pure anatase TiO2 surface was characterized by fitting the adhesion and adsorption capacity per unit contact area, and it was found that the adhesion forces were approximately 0.86, 2.63, and 4.41 nN for lysozyme, myoglobin, and BSA, respectively. Moreover, we reported that the molecular interaction force was independent of the surface topography of the material but the protein type is a factor of the interaction. These experimental results on the molecular level provide helpful insights for stimulating model calculation and molecular simulation studies of protein interaction with surfaces.

OsPAP10c, a novel secreted acid phosphatase in rice, plays an important role in the utilization of external organic phosphorus.

Under phosphate (Pi ) starvation, plants increase the secretion of purple acid phosphatases (PAPs) into the rhizosphere to scavenge organic phosphorus (P) for plant use. To date, only a few members of the PAP family have been characterized in crops. In this study, we identified a novel secreted PAP in rice, OsPAP10c, and investigated its role in the utilization of external organic P. OsPAP10c belongs to a monocotyledon-specific subclass of Ia group PAPs and is specifically expressed in the epidermis/exodermis cell layers of roots. Both the transcript and protein levels of OsPAP10c are strongly induced by Pi starvation. OsPAP10c overexpression increased acid phosphatase (APase) activity by more than 10-fold in the culture media and almost fivefold in both roots and leaves under Pi -sufficient and Pi -deficient conditions. This increase in APase activity further improved the plant utilization efficiency of external organic P. Moreover, several APase isoforms corresponding to OsPAP10c were identified using in-gel activity assays. Under field conditions with three different Pi supply levels, OsPAP10c-overexpressing plants had significantly higher tiller numbers and shorter plant heights. This study indicates that OsPAP10c encodes a novel secreted APase that plays an important role in the utilization of external organic P in rice.

Molecular Dynamics Study of Mg2+/Li+ Separation via Biomimetic Graphene-Based Nanopores: The Role of Dehydration in Second Shell.

Residual Mg2+ reduces the performance of lithium-ion batteries. However, separating Mg2+ and Li+ is difficult because of their similar ionic properties. Inspired by the high selectivity of biological Mg2+ channels, this work utilizes atomistic simulations to investigate the ability of graphene-based nanopores with diameters of 0.789, 1.024, and 1.501 nm to separate Mg2+ and Li+ under a series of transmembrane voltages. We analyzed the spatial distribution of molecules in the nanopores' vicinity, structure properties of ionic hydration, and potential of mean force of ions traveling through the nanopores. Separation was mainly caused by the difference in dehydration between the second hydration shells of Mg2+ and Li+. When ions traveled through nanopores, Li+ had to overcome a greater energy barrier than Mg2+ because it had to shed more water molecules and break more hydrogen bonds in the second hydration shell compared with Mg2+. Moreover, the ionic Coulomb blockade of Mg2+ occurred near the pore mouth, impeding Li+ transport and increasing selectivity when the pore diameter decreased to subnanometer.

Exploring phlebotomy technique as a pre-analytical factor in proteomic analyses by mass spectrometry.

Multiple reaction monitoring mass spectrometry (MRM-MS) is an emerging technology for blood biomarker verification and validation; however, the results may be influenced by pre-analytical factors. This exploratory study was designed to determine if differences in phlebotomy techniques would significantly affect the abundance of plasma proteins in an upcoming biomarker development study. Blood was drawn from 10 healthy participants using four techniques: (1) a 20-gauge IV with vacutainer, (2) a 21-gauge direct vacutainer, (3) an 18-gauge butterfly with vacutainer, and (4) an 18-gauge butterfly with syringe draw. The abundances of a panel of 122 proteins (117 proteins, plus 5 matrix metalloproteinase (MMP) proteins) were targeted by LC/MRM-MS. In addition, complete blood count (CBC) data were also compared across the four techniques. Phlebotomy technique significantly affected 2 of the 11 CBC parameters (red blood cell count, p = 0.010; hemoglobin concentration, p = 0.035) and only 12 of the targeted 117 proteins (p < 0.05). Of the five MMP proteins, only MMP7 was detectable and its concentration was not significantly affected by different techniques. Overall, most proteins in this exploratory study were not significantly influenced by phlebotomy technique; however, a larger study with additional patients will be required for confirmation.

Functional characterization of AcWRKY94 in response to Pseudomonas syringae pv. actinidiae in kiwifruit.

WRKY transcription factors are essential for coping with various biotic stresses. Pseudomonas syringae pv. actinidiae (Psa)-induced kiwifruit canker is a major problem restricting kiwifruit yield. Nevertheless, it's unclear how the kiwifruit WRKY genes respond to Psa. Through genome-wide identification, 112 WRKY members were found in 'Hongyang' genome in this work. Promoter analysis revealed that there were many cis-acting elements associated with stress responses in the AcWRKY gene's promoter region. According to transcriptomic analysis, 90 of the AcWRKY genes were differently expressed following Psa, salicylic acid (SA), or methyl jasmonate (MeJA) treatments. Almost all group III WRKYs were responsive to at least one of these treatments, with tissue-specific expression patterns. Quantitative RT-PCR study provided more evidence that Psa and SA treatments significantly induced the expression of the group III WRKY gene AcWRKY94, whereas MeJA treatment repressed it. AcWRKY94 was a transcriptionally active protein localized in the nucleus. Transient overexpression of AcWRKY94 in the leaves of 'Hongyang' enhanced the resistance of kiwifruit to Psa. Overexpression of AcWRKY94 in kiwifruit callus remarkably promoted the expression of PR and JAZ genes associated with SA and JA signals, respectively. These data imply that AcWRKY94 controls the signaling pathway dependent on SA and JA, thereby enhancing resistance to Psa. Taken together, this study establishes the basis for functional research on WRKY genes and provides important information for elucidating the resistance mechanism of kiwifruit canker disease.

Removal of Pb(II) and phosphorus in water by γ-Al2O3/biochar.

In this work, we synthesized activated alumina biochar composites (γ-Al2O3/BC) by sol-gel method, which improved the problem that the surface charge of γ-Al2O3 was not conducive to the removal of heavy metal cation in a neutral solution, and then explored the feasibility of removing Pb(II) by γ-Al2O3/BC as well as reusing Pb-laden waste sludge to remove phosphorus (P) and its micro-adsorption mechanisms. The results show that the maximum adsorption capacity of γ-Al2O3/BC for Pb(II) is 182.48 mg/g, and the removing capacity of recycled Pb-laden slag for P also reaches 87.13 mg/g. It was found that the presence of Pb in the slag makes P removal more effective. In addition, in the process of P removal, the Pb in the slag will not be released, which will not cause secondary pollution to the water. The micro-adsorption mechanism of Pb(II) and P on the composites was investigated by XPS, XRD, and FTIR. It demonstrates that special functional groups such as hydroxy-aluminum, hydroxyl, and carboxyl groups can remove Pb(II) through strong surface complexation and electrostatic attraction. Furthermore, the removal mechanism of P from Pb-laden sludge includes chemisorption and complexation, and the precipitation of P and Pb on the adsorbent surface is the main reason for the removal of P. Therefore, it is feasible to further effectively remove P by using the waste biochar containing Pb. The idea of this paper provides a potential method for the reuse of waste adsorbent.

Tumor immunosuppression relief via acidity modulation combined PD-L1 siRNA for enhanced immunotherapy.

The efficacy of immune checkpoint therapy is limited by the immunosuppressive tumor microenvironment (TME), and lactate, the most universal component of TME, has been rediscovered that plays important roles in the regulation of metabolic pathways, angiogenesis, and immunosuppression. Here, a therapeutic strategy of acidity modulation combined with programmed death ligand-1 (PD-L1) siRNA (siPD-L1) is proposed to synergistically enhance tumor immunotherapy. The lactate oxidase (LOx) is encapsulated into the hollow Prussian blue (HPB) nanoparticles (NPs) prepared by hydrochloric acid etching followed by the modification with polyethyleneimine (PEI) and polyethylene glycol (PEG) via sulfur bonds (HPB-S-PP@LOx), siPD-L1 is loaded via electrostatic adsorption to obtain HPB-S-PP@LOx/siPD-L1. The obtained co-delivery NPs can accumulate in tumor tissue with stable systemic circulation, and simultaneous release of LOx and siPD-L1 in intracellular high glutathione (GSH) environment after uptake by tumor cells without being destroyed by lysosome. Moreover, LOx can catalyze the decomposition of lactate in the hypoxic tumor tissue with the aid of oxygen release by the HPB-S-PP nano-vector. The results show that the acidic TME regulation via lactate consumption can improve the immunosuppressive TME, including revitalizing the exhausted CD8+ T cells and decreasing the proportion of immunosuppressive Tregs, and synergistically elevating the therapeutic effect of PD1/PD-L1 blockade therapy via siPD-L1. This work provides a novel insight for tumor immunotherapy and explores a promising therapy for triple-negative breast cancer.

Molecular behavior of water in TiO2 nano-slits with varying coverages of carbon: a molecular dynamics simulation study.

It is well known that titanium dioxide (TiO(2)) is biocompatible and environmentally friendly. Consequently, TiO(2) is widely applied in many fields, such as implant materials, photocatalysis, pigments, cosmetic additives, etc. Mesoporous TiO(2) finds many industrial applications, because of its high surface area and stable structure. However, the strong interaction between TiO(2) and water molecules sometimes limits its application to solution environments. Our previous computational work showed that changes to the surface chemistry of TiO(2) can affect the hydrogen bond network of water molecules on the TiO(2) surface, and so influence the diffusion of water in the slits. Thus, a carbon-modified TiO(2) surface could be an alternative way to avoid this limitation. In this work, a slit pore model with a modified TiO(2) surface (pore widths 1.2 nm, 1.6 nm and 2.0 nm) with varying carbon coverages (0%, 7%, 47%, 53%, 93% and 100%) was presented. Molecular dynamics (MD) simulations were then performed to investigate the sorption and diffusion of water in these slits. Simulation results showed that the interfacial water molecules on bare TiO(2) regions were little affected by the neighboring carbon, and they have the same properties as those on bare TiO(2) surfaces. However, the diffusion of water molecules in the center of the slit was enhanced on increase of carbon coverage, because the carbon layer broke the hydrogen bond network between the interfacial water molecules and those on the bare TiO(2) surface. It was found that in the slits (>1.2 nm) fully covered by carbon the diffusion coefficients of water are larger than that of bulk water. Moreover, large pore sizes caused an increase in the mobility of water molecules in carbon-modified TiO(2), in agreement with previous experimental work.

DFT study of coverage-depended adsorption of NH3 on TiO2-B (100) surface.

A previous study showed that TiO(2)-B (100) surface is very unique. It is characterised by high activity and a loose structure. In this study, we studied the adsorption of ammonia on TiO(2)-B (100) surface at coverages ranging from 1/6 ML to 1 ML using ab initio density functional calculations. We also investigated the adsorption of an isolated ammonia molecule on TiO(2)-B (001) surface to compare the different activities of TiO(2)-B (100) and (001) surfaces towards NH(3). The results showed that the TiO(2)-B (100) surface is more reactive towards NH(3) molecule than TiO(2)-B (001) surface, and the Lewis acid site on TiO(2)-B (100) surface is more acidic. The decrease rate of the average molecular adsorption energy of NH(3) with coverage on TiO(2)-B (100) surface is substantially lower than that on a rutile (011) surface above 1/2 ML coverage due to the open structure of TiO(2)-B (100) surface. The average molecular adsorption energy shows a linear dependence on the coverage of y = 111.0 - 36.3x on TiO(2)-B (100) surface. The possibility of NH(3) molecule onto the Ti(5c) site is nearly equal to forming a dimer with adsorbed NH(3) on TiO(2)-B (100) surface at 5/6 ML coverage.

Removal of Cd2+ from water containing Ca2+ and Mg2+ using titanate nanotubes modified by carbon.

Calcium and magnesium ions usually exist in natural water. When Cd2+ is removed from water by adsorption, it will be inhibited by these two ions. Titanate nanotubes (TNTs) have an effective adsorption capacity for Cd2+ due to extraordinary ion exchange property. However, TNTs also adsorb Ca2+ and Mg2+ in water. In this study, carbon-modified TNT (TNT/C) and TNT/C further treated with acid (TNT/HC) were synthesized by hydrothermal synthesis. The transmission electron microscope (TEM) images show that TNT/C or TNT/HC still keep nanotube morphology. The experimental results show the order of adsorption amount to Cd2+ is TNT (171.56 mg/g) > TNT/C (166 mg/g) > TNT/HC (159.88 mg/g) when there is no Ca2+ or Mg2+. But when there is 0.1 M Ca2+ or Mg2+ in the water, the order of Cd2+ adsorption capacity becomes TNT/HC (44.28, 49.04 mg/g) > TNT/C (58.84, 69.32 mg/g) > TNT (65.52, 70.6 mg/g). It indicates that the surface carbon modification can alleviate the hindrance of Ca2+ or Mg2+ to Cd2+ removal. This is because the carbon on the surface of TNT captured part of Ca2+ or Mg2+; it made more Cd2+ be successfully absorbed by TNT through ion exchange. This mechanism was confirmed by the X-ray photoelectron spectroscopy (XPS) spectra analysis. The results of this paper can provide ideas for the adsorption and removal of Cd2+ in water in the presence of Ca2+ or Mg2+.

A shortcut for evaluating activities of TiO2 facets: water dissociative chemisorption on TiO2-B (100) and (001).

By means of density functional theory (DFT) calculations, we study the water adsorption behavior on two common surfaces, (001) and (100) TiO(2)-B, which maintains the monoclinic structure as high as approximately 550 degrees C or higher in ambient conditions. The two surfaces show totally different activity for water dissociation. The dissociative chemisorption of water on TiO(2)-B (100) is identified at both submonolayer and monolayer coverages, which indicates considerable reactivity. In contrast, the non-dissociative molecular adsorption of water is the most stable state on TiO(2)-B (001) which suggests no special activity. Furthermore, we compare the structural features of different surfaces with diverse crystal structures, such as rutile, anatase, brookite, TiO(2)-B etc. Keeping a close eye on the exposed atoms on the surface, we conclude a more general criterion for a quick evaluation of reactivities of different TiO(2) surfaces merely based on local surface structure features.

Molecular dynamics simulation study of ionic hydration in negatively charged single-walled carbon nanotubes.

Molecular dynamics simulation is applied to study the surface charge effects on the hydration of Na+ and K+ confined in pristine and negatively charged carbon nanotubes (CNTs). The CNTs are modified through negative charges. The structural characteristics of the coordination shells of Na+ and K+ including the ion-oxygen radial distribution functions (RDFs), the coordination numbers and the orientation distributions of the water molecules are studied. The simulation results show that the orientation distributions of the water molecules in the first coordination shell of K+ are more sensitive to the wall charge than those of Na+. The electric field effects produced by the wall charge dominate in the CNTs with large diameter. On contrary, in the narrow CNTs, the confinement effects dominate.