High fluorescence quantum yield (QY), excellent fluorescence stability, and low toxicity are essential for a good cellular imaging fluorescent probe. Green-emissive carbon quantum dots (CQDs) with many advantages, such as unique fluorescence properties, anti-photobleaching, low toxicity, fine biocompatibility and high penetration depth in tissues, have been considered as a potential candidate in cell imaging fluorescent probes. Herein, N, S-codoped green-emissive CQDs (QY= 64.03%) were synthesized by the one-step hydrothermal method, with m-phenylenediamine as the carbon and nitrogen source, and L-cysteine as the nitrogen and sulfur dopant, under the optimum condition of 200 °C reaction for 2 h. Their luminescence was found to originate from the surface state. In light of the satisfactory photobleaching resistance and the low cytotoxicity, CQDs were used as a cell imaging probe for HeLa cell imaging. The results clearly indicate that cells can be labeled with CQDs, which can not only enter the cytoplasm, but also enter the nucleus through the nuclear pore, showing their broad application prospect in the field of cell imaging.
Recent years witnessed a growing research interest in graphene-reinforced aluminum matrix composites (GRAMCs). Compared with conventional reinforcements of aluminum matrix composites (AMCs), graphene possesses many attractive characteristics such as extremely high strength and modulus, unique self-lubricating property, high thermal conductivity (TC) and electrical conductivity (EC), and low coefficient of thermal expansion (CTE). A lot of studies have demonstrated that the incorporation of graphene into Al or Al alloy can effectively enhance mechanical and physical properties of the Al matrix. The purpose of this work is aimed to trace recent development of GRAMCs. Initially, this paper covers a brief overview of fabrication methods of GRAMCs. Then, mechanical, tribological, thermal and electrical properties of recently developed GRAMCs are presented and discussed. Finally, challenges and corresponding solutions related to GRAMCs are reviewed.
With the rapid development of wearable smart devices, many researchers have carried out in-depth research on the stretchable electrodes. As one of the core components for electronics, the electrode mainly transfers the electrons, which plays an important role in driving the various electrical devices. The key to the research for the stretchable electrode is to maintain the excellent electrical properties or exhibit the regular conductive change when subjected to large tensile deformation. This article outlines the recent progress of stretchable electrodes and gives a comprehensive introduction to the structures, materials, and applications, including supercapacitors, lithium-ion batteries, organic light-emitting diodes, smart sensors, and heaters. The performance comparison of various stretchable electrodes was proposed to clearly show the development challenges in this field. We hope that it can provide a meaningful reference for realizing more sensitive, smart, and low-cost wearable electrical devices in the near future.
Developing chemotherapy drugs with high efficacy and few side effects has been a bottleneck problem that requires an efficient solution. The active cancer treatment ingredient disulfiram (DSF), inspired by the copper(II) diethyldithiocarbamate complex (CuET), can be used in a one-pot synthesis method to construct a CuET delivery nanosystem (CuET-ZIFCu@HA). Due to the high biocompatibility, targeting of CD44 overexpressed cancer cells, and acid response of zeolitic imidazolate framework (ZIF) materials of hyaluronic acid (HA), we realized that CuET-ZIFCu@HA could become an effective and highly selective cancer treatment. Both in vivo and in vitro experiments have demonstrated that CuET-ZIFCu@HA has robust anti-tumor properties without evident side effects. This research provided a promising strategy for DSF nanosystems that involves simple preparation and high efficacy, both of which are key to reusing DSF in cancer treatment.
The synergistic effect of polyethylene glycol (PEG) and poly(2-methacryloyloxyethyl phosphorylcholine) (PMPC) can effectively reduce the protein absorption, which is beneficial to theranostics. However, PEG–PMPC-based polymers have rarely been used as nanocarriers in the theranostic field due to their limited modifiability and weak interaction with other materials. Herein, a plain method was proposed to endow them with the probable ability of loading small active agents, and the relationship between the structure and the ability of loading hydrophobic agents was explored, thus expanding their applications. Firstly, mPEG–PMPC or 4-arm-PEG–PMPC polymer was synthesized by atom transfer radical polymerization (ATRP) using mPEG-Br or 4-arm-PEG-Br as the macroinitiator. Then a strong hydrophobic segment, poly(butyl methacrylate) (PBMA), was introduced and the ability to load small hydrophobic agents was further explored. The results showed that linear mPEG–PMPC–PBMA could form micelles 50–80 nm in size and load the hydrophobic agent such as Nile red efficiently. In contrast, star-like 4-arm-PEG–PMPC–PBMA, a monomolecular micelle (10–20 nm), could hardly load any hydrophobic agent. This work highlights effective strategies for engineering PEG–PMPC-based polymers and may facilitate the further application in numerous fields.
In the past few decades, many novel non-metal doped ZnO materials have developed hasty interest due to their adaptable properties such as low recombination rate and high activity under the solar light exposure. In this article, we compiled recent research advances in non-metal (S, N, C) doped ZnO, emphasizing on the related mechanism of catalysis and the effect of non-metals on structural, morphological, optical and photocatalytic characteristics of ZnO. This review will enhance the knowledge about the advancement in ZnO and will help in synthesizing new ZnO-based materials with modified structural and photocatalytic properties.
Graphene is a remarkable material with great potential in many applications due to its chemical and physical properties. In this review we briefly present the recent research progress (2016–2018) in graphene and graphene-based nanomaterials synthesis and discuss the practical aspects of using the materials produced via these methods for different graphene-based applications.
Research on glass nanocomposites (GNCs) has been very active in the past decades. GNCs have attracted — and still do — great interest in the fields of optoelectronics, photonics, sensing, electrochemistry, catalysis, biomedicine, and art. In this review, the potential applications of GNCs in these fields are briefly described to show the reader the possibilities of these materials. The most important synthesis methods of GNCs (melt-quenching, sol-gel, ion implantation, ion-exchange, staining process, spark plasma sintering, radio frequency sputtering, spray pyrolysis, and chemical vapor deposition techniques) are extensively explained. The major aim of this review is to systematize our knowledge about the synthesis of GNCs and to explore the mechanisms of formation and growth of NPs within glass matrices. The size-controlled preparation of NPs within glass matrices, which remains a challenge, is essential for advanced applications. Therefore, a thorough understanding of GNC synthesis techniques is expected to facilitate the preparation of innovative GNCs.
Hollow mesoporous silica nanoparticles (HMSNs) have become an attractive drug carrier because of their unique characteristics including stable physicochemical properties, large specific surface area and facile functionalization, especially made into intelligent drug delivery systems (DDSs) for cancer therapy. HMSNs are employed to transport traditional anti-tumor drugs, which can solve the problems of drugs with instability, poor solubility and lack of recognition, etc., while significantly improving the anti-tumor effect. And an unexpected good result will be obtained by combining functional molecules and metal species with HMSNs for cancer diagnosis and treatment. Actually, HMSNs-based DDSs have developed relatively mature in recent years. This review briefly describes how to successfully prepare an ordinary HMSNs-based DDS, as well as its degradation, different stimuli-responses, targets and combination therapy. These versatile intelligent nanoparticles show great potential in clinical aspects.
We report a green and facile approach for the synthesis of NiFe2O4 (NF) nanoparticles with good crystallinity. The prepared materials are studied by various techniques in order to know their phase structure, crystallinity, morphology and elemental state. The BET analysis revealed a high surface area of 80.0 m2·g−1 for NF possessing a high pore volume of 0.54 cm3·g−1, also contributing to the amelioration of the electrochemical performance. The NF sample is studied for its application in supercapacitors in an aqueous 2 mol·L−1 KOH electrolyte. Electrochemical properties are studied both in the three-electrode method and in a symmetrical supercapacitor cell. Results show a high specific capacitance of 478.0 F·g−1 from the CV curve at an applied scan rate of 5 mV·s−1 and 368.0 F·g−1 from the GCD analysis at a current density of 1 A·g−1 for the NF electrode. Further, the material exhibited an 88% retention of its specific capacitance after continuous 10000 cycles at a higher applied current density of 8 A·g−1. These encouraging properties of NF nanoparticles suggest the practical applicability in high-performance supercapacitors.
Lithium–sulfur (Li‒S) battery has been considered as one of the most promising future batteries owing to the high theoretical energy density (2600 W·h·kg−1) and the usage of the inexpensive active materials (elemental sulfur). The recent progress in fundamental research and engineering of the Li‒S battery, involved in electrode, electrolyte, membrane, binder, and current collector, has greatly promoted the performance of Li‒S batteries from the laboratory level to the approaching practical level. However, the safety concerns still deserve attention in the following application stage. This review focuses on the development of the electrolyte for Li‒S batteries from liquid state to solid state. Some problems and the corresponding solutions are emphasized, such as the soluble lithium polysulfides migration, ionic conductivity of electrolyte, the interface contact between electrolyte and electrode, and the reaction kinetics. Moreover, future perspectives of the safe and high-performance Li‒S batteries are also introduced.
A chronic wound in diabetic patients is a major public health concern with socioeconomic and clinical manifestations. The underlying medical condition of diabetic patients deteriorates the wound through physiological, metabolic, molecular, and cellular pathologies. Consequently, a wound enters a vicious pathological inflammatory cycle. Many therapeutic approaches are in practice to manage diabetic wounds hence ensuring the regeneration process. Polymer-based biomaterials have come up with high therapeutic promises. Many efforts have been devoted, over the years, to build an effective wound healing material using polymers. The electrospinning technique, although not new, has turned out to be one of the most effective strategies in building wound healing biomaterials due to the special structural advantages of electrospun nanofibers over the other formulations. In this review, careful integration of all electrospinning approaches has been presented which will not only give an insight into the current updates but also be helpful in the development of new therapeutic material considering pathophysiological conditions of a diabetic wound.
Tricobalt tetroxide (Co3O4) is one of the promising anodes for lithium-ion batteries (LIBs) due to its high theoretical capacity. However, the poor electrical conductivity and the rapid capacity decay hamper its practical application. In this work, we design and fabricate a hierarchical Co3O4 nanorods/N-doped graphene (Co3O4/NG) material by a facile hydrothermal method. The nitrogen-doped graphene layers could buffer the volume change of Co3O4 nanorods during the delithium/lithium process, increase the electrical conductivity, and profit the diffusion of ions. As an anode, the Co3O4/NG material reveals high specific capacities of 1873.8 mA·h·g−1 after 120 cycles at 0.1 A·g−1 as well as 1299.5 mA·h·g−1 after 400 cycles at 0.5 A·g−1. Such superior electrochemical performances indicate that this work may provide an effective method for the design and synthesis of other metal oxide/N-doped graphene electrode materials.
The fundamental relationship between microstructure, constituent, processing and performances of separating materials is really a vital issue. Traditional preparation methods for separation membranes are complex, time-consuming and easy to be fouled. Also, the durability of conventional coatings on membrane is poor. By combination of bioinspiration from mussel adhesive and fish scales’ underwater superoleophobicity, we propose a general route to prepare organic–inorganic hybrid coatings, while no complex apparatus is needed. Specifically, based on the biomimetic adhesion of polydopamine (PDA), we used it as a binder to adhere TiO2 nanoparticles and built rough microstructure on fabric. In this way, we obtained TiO2-PDA treated fabric with special wettability. These TiO2-PDA treated samples owned superamphiphilicity in air, underwater superoleophobicity (underwater oil contact angles (OCAs)>150°), underoil superhydrophobicity (underoil water contact angles (WCAs)>150°), excellent multi-resistance; and can separate polar/nonpolar liquid mixture effectively. It also owned superaerophobicity underwater (underwater bubble contact angles (BCAs)>150°). The proposed TiO2-PDA coatings are highly expected to be employed for real situation of water pollution remediation, self-cleaning, oil extraction and harsh chemical engineering issues.
A number of industrial and biomedical fields, such as hydraulic fracturing balls for gas and petroleum exploitation and implant materials, require Mg alloys with rapid dissolution. An iron-bearing phosphate chemical conversion (PCC) coating with self-catalytic degradation function was fabricated on the Mg alloy AZ31. Surface morphologies, chemical compositions and degradation behaviors of the PCC coating were investigated through FE-SEM, XPS, XRD, FTIR, electrochemical and hydrogen evolution tests. Results indicated that the PCC coating was characterized by iron, its phosphates and hydroxides, amorphous Mg(OH)2 and Mg3−n(HnPO4)2. The self-catalytic degradation effects were predominately concerned with the Fe concentration, chemical composition and microstructure of the PCC coating, which were ascribed to the galvanic corrosion between Fe in the PCC coating and the Mg substrate. The coating with higher Fe content and porous microstructure exhibited a higher degradation rate than that of the AZ31 substrate, while the coating with a trace of Fe and compact surface disclosed a slightly enhanced corrosion resistance for the AZ31 substrate.
With the rapid improvements in nanomaterials and imaging technology, great progresses have been made in diagnosis and treatment of diseases during the past decades. Fe3O4 magnetic nanoparticles (MNPs) with good biocompatibility and superparamagnetic property are usually used as contrast agent for diagnosis of diseases in magnetic resonance imaging (MRI). Currently, the combination of multiple imaging technologies has been considered as new tendency in diagnosis and treatment of diseases, which could enhance the accuracy and reliability of disease diagnosis and provide new strategies for disease treatment. Therefore, novel contrast agents used for multifunctional imaging are urgently needed. Fe3O4 MNPs are believed to be a potential candidate for construction of multifunctional platform in diagnosis and treatment of diseases. In recent years, there are a plethora of studies concerning the construction of multifunctional platform presented based on Fe3O4 MNPs. In this review, we introduce fabrication methods and modification strategies of Fe3O4 MNPs, expecting great improvements for diagnosis and treatment of diseases in the future.
The consumer demand for emerging technologies such as augmented reality (AR), autopilot, and three-dimensional (3D) internet has rapidly promoted the application of novel optical display devices in innovative industries. However, the micro/nanomanufacturing of high-resolution optical display devices is the primary issue restricting their development. The manufacturing technology of micro/nanostructures, methods of display mechanisms, display materials, and mass production of display devices are major technical obstacles. To comprehensively understand the latest state-of-the-art and trigger new technological breakthroughs, this study reviews the recent research progress of master molds produced using nanoimprint technology for new optical devices, particularly AR glasses, new-generation light-emitting diode car lighting, and naked-eye 3D display mechanisms, and their manufacturing techniques of master molds. The focus is on the relationships among the manufacturing process, microstructure, and display of a new optical device. Nanoimprint master molds are reviewed for the manufacturing and application of new optical devices, and the challenges and prospects of the new optical device diffraction grating nanoimprint technology are discussed.
Early detection of cancer has multitude of advantages like early diagnosis, reduced risk, ease in the treatment and follow up of recurrence. New and developed techniques are always under research to control the spreading malignancy. Graphene is an emerging star in biomedical field as it exhibits exceptional thermal, electrical and optical properties. Here, we review application of graphene-based materials in developing biosensing devices for the detection of different cancer biomarkers at concentrations down to sub-toxic levels. Different analytical methodologies chosen for sensing have been undertaken and their performance and background have been discussed. The trend of use of these methodologies can also be perceived from the graphical data presented.
FeS2 has drawn tremendous attention as electrode material for sodium-ion batteries (SIBs) due to its high theoretical capacity and abundant resources. However, it suffers from severe volume expansion and dull reaction kinetics during the cycling process, leading to poor rate capacity and short cyclability. Herein, a well-designed FeS2@C/G composite constructed by FeS2 nanoparticles embedded in porous carbon nanorods (FeS2@C) and covered by three-dimensional (3D) graphene is reported. FeS2 nanoparticles can shorten the Na+ diffusion distance during the sodiation–desodiation process. Porous carbon nanorods and 3D graphene not only improve conductivity but also provide double protection to alleviate the volume variation of FeS2 during cycling. Consequently, FeS2@C/G exhibits excellent cyclability (83.3% capacity retention after 300 cycles at 0.5 A·g−1 with a capacity of 615.1 mA·h·g−1) and high rate capacity (475.1 mA·h·g−1 at 5 A·g−1 after 2000 cycles). The pseudocapacitive process is evaluated and confirmed to significantly contribute to the high rate capacity of FeS2@C/G.
In recent years, superhydrophobic coatings have received extensive attention due to their functions of waterproof, antifouling, self-cleaning, etc. However, wide applications of superhydrophobic coatings are still affected by their disadvantages of complex preparation, low mechanical properties, and poor ultraviolet (UV) resistance. In this study, cellulose nanocrystal containing a small amount of lignin (L-CNC)/SiO2 composite particles were used as the main material, polydimethylsiloxane (PDMS) as the adhesive and perfluorooctyltrichlorosilane (FOTS) as the modifier to prepare superhydrophobic coatings by a one-step spray method. The resulted coating showed excellent superhydrophobicity (water contact angle (WCA) of 161° and slide angle (SA) of 7°) and high abrasion resistance (capable of withstanding 50 abrasion cycles under the load of 50 g). Moreover, it still maintained good superhydrophobicity after 5 h of exposure to the UV light (1000 W), displaying its good UV resistance. This study provides theoretical and technical reference for the simple preparation of organic‒inorganic composite superhydrophobic coatings with high abrasion resistance and good UV resistance, which is beneficial to improving the practicability and broadening the application scope of superhydrophobic coatings.
As an excellent room temperature sensing material, polyaniline (PANI) needs to be further investigated in the field of high sensitivity and sustainable gas sensors due to its long recovery time and difficulty to complete recovery. The ZnO/PANI film with p‒n heterogeneous energy levels have successfully prepared by spraying ZnO nanorod synthesized by hydrothermal method on the PANI film rapidly synthesized at the gas‒liquid interface. The presence of p‒n heterogeneous energy levels enables the ZnO/PANI film to detect 0.1‒100 ppm (1 ppm = 10−6) NH3 at room temperature with the response value to 100 ppm NH3 doubled (12.96) and the recovery time shortened to 1/5 (31.2 s). The ability of high response and fast recovery makes the ZnO/PANI film to be able to detect NH3 at room temperature continuously. It provides a new idea for PANI to prepare sustainable room temperature sensor and promotes the development of room temperature sensor in public safety.
Magnetic nanoparticles (MNPs) have widely been synthesized through chemical processes for biomedical applications over the past few decades. Recently, a new class of MNPs, known as bacterial magnetosomes, has been isolated from magnetotactic bacteria, a natural source. These magnetosomes are magnetite or greigite nanocrystals which are biomineralized in the bacterial cell and provide magnet-like properties to it. Contrary to MNPs, bacterial magnetosomes are biocompatible, lower in toxicity, and can be easily cleared from the body due to the presence of a phospholipid bilayer around them. They also do not demonstrate aggregation, which makes them highly advantageous. In this review, we have provided an in-depth comparative account of bacterial magnetosomes and chemically synthesized MNPs in terms of their synthesis, properties, and biomedical applications. In addition, we have also provided a contrast on how magnetosomes might have the potential to successfully substitute synthetic MNPs in therapeutic and imaging applications.
An air superoleophobic/superhydrophilic composite coating with a unique structure was fabricated by oxidation and further modification of the copper mesh, and its design principle was clarified. This unique bird-nest-like configuration gives it instant superhydrophilicity due to the high surface roughness and high polar surface free energy components, while air superoleophobicity is caused by its extremely low dispersive surface free energy components. Furthermore, a water-resistance mechanism was proposed whereby a polyelectrolyte plays a critical role in improving the water-resistance of fluorosurfactants. It can separate oil–water mixtures with high efficiency (98.72%) and high flux (25185 L·m−2·h−1), and can be reused. In addition, our composite coating had certain anti-acid, anti-alkali, anti-salt and anti-sand impact performance. More importantly, after being soaked in water for a long time or being exposed to the air for a long time, it still retained ultra-high air oil contact angle and showed excellent stability, which provided the possibility for practical applications. Thus, these findings offer the potential for significant practical applications in managing oily wastewater and marine oil spill incidents.
We exploited a unique porous structure of the nano-covalent triazine polymer (NCTP) containing aggregation-induced emission (AIE) group to achieve controlled release and drug tracking in tumor acidic microenvironment. NCTP was synthesized by the Friedel–Crafts alkylation and the McMurry coupling reaction. It not only had strong doxorubicin (DOX)-loading capacity due to its high specific surface area and large pore volume, but also showed the significant cumulative drug release as a result of the pH response of triazine polymers. NCTP was induced luminescence after mass accumulation near tumor cells. Besides, it had excellent biocompatibility and obvious antineoplastic toxicity. The results demonstrate that NCTP as a utility-type drug carrier provides a new route for designing the multi-functional drug delivery platform.
The microstructural evolutions of advanced 9--12%Cr ferrite/martensite heat-resistant steels used for power generation plants are reviewed in this article. Despite of the small differences in chemical compositions, the steels share the same microstructure of the as-tempered martensite. It is the thermal stability of the initial microstructure that matters the creep behavior of these heat-resistant steels. The microstructural evolutions involved? in? 9--12%Cr ?ferrite ?heat-resistant ?steels ?are ?elabo- rated, including (1) martensitic lath widening, (2) disappearance of prior austenite grain boundary, (3) emergence of subgrains, (4) coarsening of precipitates, and (5) formation of new precipitates, such as Laves-phase and Z-phase. The former three microstructural evolutions could be retarded by properly disposing the latter two. Namely improving the stability of precipitates and optimizing their size distribution can effectively exert the beneficial influence of precipitates on microstructures. In this sense, the microstructural stability of the tempered martensite is in fact the stability of precipitates during the creep. Many attempts have been carried out to improve the microstructural stability of 9--12%Cr steels and several promising heat-resistant steels have been developed.
Self-lubricating coatings have been widely used to reduce friction in moving machine assemblies. However, the tribological performance of these coatings is strongly dependent on the service temperature. In this paper, an extensive review pertaining to the influence of operating service temperature on tribological performance of self-lubricating coatings has been carried out. Based on the effective lubricating temperature range, the self-lubricating coatings developed in the past have been divided into three groups: low temperature lubricant coating (from--200°C to room temperature), moderate temperature lubricant coating (from room temperature to 500°C) and high temperature lubricant coating (>500°C). Ideas concerning possible ways to extend the operating temperature range of self-lubricating coatings have been presented as follows: hybridized tribological coating, adaptive tribological coatings, and diffusion rate limited solid lubricant coating. In addition, a new self-lubricating coating formulation for potential application at a wide operating temperature range has been proposed.
Herein, the rational design micromilieus involved silk fibroin (SF)-based materials have been used to encapsulate the osteoblasts, forming an extracellular coated shell on the cells, which exhibited the high potential to shift the regulation of osteoblasts to osteocytes by encapsulation cues. SF coating treated cells showed a change in cell morphology from osteoblasts-like to osteocytes-like shape compared with untreated ones. Moreover, the expression of alkaline phosphatase (ALP), collagen I (Col I) and osteocalcin (OCN) further indicated a potential approach for inducing osteoblasts regulation, which typically accelerates calcium deposition and cell calcification, presenting a key role for the SF encapsulation in controlling osteoblasts behavior. This discovery showed that SF-based cell encapsulation could be used for osteoblasts behavior regulation, which offers a great potential to modulate mammalian cells’ phenotype involving alternating surrounding cues.
Currently, δ-MnO2 is one of the popularly studied cathode materials for aqueous zinc-ion batteries (ZIBs) but impeded by the sluggish kinetics of Zn2+ and the Mn cathode dissolution. Here, we report our discovery in the study of crystalline/amorphous MnO2 (disordered MnO2), prepared by a simple redox reaction in the order/disorder engineering. This disordered MnO2 cathode material, having open framework with more active sites and more stable structure, shows improved electrochemical performance in 2 mol·L−1 ZnSO4/0.1 mol·L−1 MnSO4 aqueous electrolyte. It delivers an ultrahigh discharge specific capacity of 636 mA·h·g−1 at 0.1 A·g−1 and remains a large discharge capacity of 216 mA·h·g−1 even at a high current density of 1 A·g−1 after 400 cycles. Hence disordered MnO2 could be a promising cathode material for aqueous ZIBs. The storage mechanism of the disordered MnO2 electrode is also systematically investigated by structural and morphological examinations of ex situ, ultimately proving that the mechanism is the same as that of the δ-MnO2 electrode. This work may pave the way for the possibility of using the order/disorder engineering to introduce novel properties in electrode materials for high-performance aqueous ZIBs.
Polycyclic aromatic hydrocarbons with zigzag peripheries are high perspective candidates for organic electronics. However, large fused acenes are still poorly studied due to the tedious synthesis. Herein we report a non-substituted fused bistetracene DBATT (2.3,8.9-dibenzanthanthrene) as the semiconductor on low-voltage-driven organic thin-film transistors. The systematic studies of thin-film growth on various self-assembled monolayer (SAM) modified gate dielectrics and the electrical performances were carried out. The sub-monolayer of the semiconductor film shows larger island domains on the alkyl chain SAM. This device exhibits the hole mobility of 0.011 cm2·V−1·s−1 with a current ratio of Ion/Ioff above 105.