NaBH4 Treatment Research Articles

A flexible electrode of TiO2 nanowire arrays modified with graphene for solid-state cable-type supercapacitors

Solid-state cable-type supercapacitors (SSCTSs) have a wide application in wearable and flexible electronic devices. The fiber-shaped electrode of fabricating TiO2 nanowire arrays (NWAs) on Ti wire is widly used in flexible electronic devices. For improving the conductivity, reduced graphene oxide (rGO) nanosheets are prepared on the surface of TiO2 NWAs by a simple electrophoretic deposition method and NaBH4 treatment. The electrochemical tests reveal that this TiO2/rGO electrode has an excellent capacitive property than pure TiO2 electrode in the optimum potential window (− 0.4~0.6 V). Two similar TiO2/rGO electrodes with Poly (vinyl alcohol)-LiCl solid-state electrolyte are assembled SSCTSs, which deliver a specific capacitance as high as 60.8 μF cm−1 at 5 μA cm−1 and a high energy density of 12.2 mWh cm−1 with a wide potential window from 0 to 1.2 V. Furthermore, this SSCTS exhibits outstanding banding performance at different state and long cycle life. These results demonstrate that fiber-shaped TiO2/rGO electrode is promising for high-performance wearable and flexible electronic devices.

NaBH4-Reduction Induced Evolution of Bi Nanoparticles from BiOCl Nanoplates and Construction of Promising Bi@BiOCl Hybrid Photocatalysts

In this work, we have synthesized BiOCl nanoplates (diameter 140–220 nm, thickness 60–70 nm) via a co-precipitation method, and then created Bi nanoparticles (diameter 35–50 nm) on the surface of BiOCl nanoplates via a NaBH4 reduction method. By varying the NaBH4 concentration and reaction time, the evolution of Bi nanoparticles was systematically investigated. It is demonstrated that with increasing the NaBH4 concentration (at a fixing reaction time of 30 min), BiOCl crystals are gradually reduced into Bi nanoparticles, and pure Bi nanoparticles are formed at 120 mM NaBH4 solution treatment. At low-concentration NaBH4 solutions (e.g., 10 and 30 mM), with increasing the reaction time, BiOCl crystals are partially reduced into Bi nanoparticles, and then the Bi nanoparticles return to form BiOCl crystals. At high-concentration NaBH4 solutions (e.g., 120 mM), BiOCl crystals are reduced to Bi nanoparticles completely with a short reaction time, and further prolong the treatment time leads to the transformation of the Bi nanoparticles into a two-phase mixture of BiOCl and Bi2O3 nanowires. The photodegradation performances of the samples were investigated by choosing rhodamine B (RhB) as the model pollutant and using simulated sunlight as the light source. It is demonstrated that an enhanced photodegradation performance can be achieved for the created Bi@BiOCl hybrid composites with appropriate NaBH4 treatment. The underlying photocatalytic mechanism was systematically investigated and discussed.

Reduced Graphene Oxide-based Covalent Hybrid Film Electrode Self-assembled with Gold Nanoparticles for the Enzyme-Free Amperometric Sensing of Serum Uric Acid.

Purine metabolism in the human body leads to the production of uric acid (UA) at the end. But an abnormal level of UA in the human body creates health problems. The sensing and quantification of UA is essentially required to prevent and diagnose hypertension, arthritis, gout, hyperuricemia or Lesch-Nyhan syndrome, etc. Herein, the development of a sensing platform for the measurement of UA using Au nanoparticle-based hybrid self-assembly is described. The self-assembling of a thiol-terminated silicate network functionalized graphene oxide hybrid on a polycrystalline Au surface yields a three-dimensional assembly. The oxygen functionalities of the self-assembly were partially reduced by an NaBH4 treatment. The free -SH groups of the self-assembly were successfully used for the immobilization of Au nanoparticles by chemisorption. The nanoparticle-based hybrid self-assembly is highly sensitive toward UA, and shows a wide linear response with a detection limit of 40 nM UA (S/N = 7) without interference from co-exiting ascorbic acid. Its practical application was demonstrated using human serum samples.

High-Performance PEDOT:PSS Flexible Thermoelectric Materials and Their Devices by Triple Post-Treatments

Searching an effective method to enhance the thermoelectric properties of flexible organic films can significantly widen the application of flexible thermoelectric devices. Tuning the microstacking structure and oxidation level can effectively optimize the thermoelectric properties of poly(3,4 ethylenedioxithiophene):poly(styrenesulfonate)(PEDOT:PSS) organic films. Here, we adopt triple post-treatments with formamide (CH3NO), concentrated sulfuric acid (H2SO4), and sodium borohydride in sequence to engineer flexible PEDOT:PSS thermoelectric films. A high power factor of 141 μWm−1 K−2 at 25 °C has been obtained for the PEDOT:PSS film. Such a high power factor stems from the high σ (1786 Scm−1) and S (28.1 μVK−1) after posttreatment with CH3NO, H2SO4, and NaBH4 in order. The increased carrier mobility resulting from both the selective removal of excess insulating PSS within the films and the conformation transition after CH3NO and H2SO4 treatments is responsible for the enhancement of σ, while the subsequent NaBH4 treatment optimize the electrical properties (σ and S) by modulating the oxidation level. A homemade thermoelectric device has also been fabricated using the as-prepared flexible PEDOT:PSS films and had a high output power density of ∼1 μWcm−2 with human arm as a heating source. This study indicates that flexible thermoelectric devices based on cheap conducting polymers have great potential in wearable electronics.

Zeolitic imidazolate frameworks derived novel polyhedral shaped hollow Co-B-O@Co3O4 electrocatalyst for oxygen evolution reaction

The development of highly effective and low-cost non-noble metal electrochemical catalysts for oxygen evolution reactions (OER) is a major challenge for overall water splitting and rechargeable metal-air batteries. In this study, we develop a novel hollow cobalt-borate modified cobalt oxide composite (denoted by Co-B-O@Co3O4) catalyst derived from zeolitic imidazolate framework-67 (ZIF-67) for electrochemical OER. The Co-B-O@Co3O4 was easily synthesized via pyrolysis of ZIF-67 in Ar and air to produce hollow Co3O4 (denoted by h-Co3O4), followed by simple NaBH4 treatment at ambient temperature for 4 h. The unique polyhedral morphology was well preserved during the NaBH4 treatment. Benefiting from its structural and compositional merit, the as-synthesized Co-B-O@Co3O4 exhibit excellent electrocatalytic activity and long-term stability for OER. Also, we conducted the OER test using a Co-B-O@Co3O4 catalyst in a neutral pH environment for further investigation. Our study can provide an insight into catalyst modification step to enhance the overall performance while keeping its physical structure simultaneously. using metal-organic framework for the electrochemical catalyst thus can be recognized as a method for producing a highly active, long-term working and novel engineered electrocatalyst for OER applications.

Deactivation and regeneration of carbon nanotubes and nitrogen-doped carbon nanotubes in catalytic peroxymonosulfate activation for phenol degradation: variation of surface functionalities.

The reuse, deactivation and regeneration of carbon nanotubes (CNT) and N-doped carbon nanotubes (NCNT) were studied in catalytic peroxymonosulfate (PMS) activation for phenol degradation. The results showed that for catalytic PMS activation, marked deactivation was observed on both CNT and NCNT, resulting in marked variation of the surface functionalities of the catalysts. Catalytic PMS activation led to markedly increased oxygen-containing functionalities and decreased points of zero charge (PZCs) of CNT and NCNT. The catalytic activity of CNT was strongly dependent on the initial PMS concentration but was independent of the initial phenol concentration. Furthermore, the dependency of the CNT activity on the initial PMS concentration closely followed the Langmuir–Hinshelwood model, indicating that the catalytic activation of adsorbed PMS was the rate controlling step. For the used CNT and NCNT, chemical reduction by NaBH4 or thermal treatment regeneration under inert atmosphere could effectively remove surface O-containing functionalities and enhance PZCs, restoring their catalytic activities; meanwhile, the N-containing functionalities of NCNT decreased with regeneration treatment, resulting in a negative impact on catalyst regeneration. The present findings indicate that surface functionalities are closely correlated with catalyst deactivation and regeneration, playing crucial roles in the catalytic activation of PMS.

Defective g-C3N4 Prepared by the NaBH4 Reduction for High-Performance H2 Production

Defects play a significant part in promoting photocatalytic activity for H2 production. Various methods such as chemical reduction have been performed to metal oxide based photocatalysts. Herein, we present the NaBH4 reduction route to introduce the defects into the graphitic carbon nitride (g-C3N4) to enhance photocatalytic activity. A new −C≡N group is observed in the FTIR spectra of treated g-C3N4 nanosheets indicating the presence of structural defects. At the same time, the B signal appears in the X-ray photoelectron spectroscopy analysis, suggesting that B is doped in the g-C3N4 during the treatment. All these results manifested that multiple types of defects are introduced in the g-C3N4 during the NaBH4 treatment. The UV–vis spectra illustrate that the absorption band edge of g-C3N4 is extended from 420 to 450 nm after NaBH4 treatment. This demonstrates that the band gap of g-C3N4 turns narrow owing to the introduction of defects. Photocatalytic H2 production of defective g-C3N4 is ∼5-fold better t...

Understanding the effect of Pd size on formic acid dehydrogenation via size-controlled Pd/C catalysts prepared by NaBH4 treatment

Herein, we investigated the effect of Pd size on a formic acid dehydrogenation (FAD) reaction. A series of size-controlled Pd/C catalysts was simply prepared by a treatment using sodium borohydride (NaBH4), which provides in-situ hydrogen in the aqueous phase. Pd particles in the catalyst were gradually agglomerated as the number of NaBH4 treatments increased, resulting in the synthesis of the size-controlled Pd/C catalysts with the Pd size from 2.5 nm to 4.8 nm. The catalytic activities of the size-controlled Pd/C catalysts continuously declined with increasing the Pd size, which was attributed to the decrease in the number of active sites of the catalyst. However, the decreasing trend of turnover frequency (TOF(h−1)) values with the Pd size at low temperature demonstrated that the intrinsic activity of the small Pd is higher than that of the large Pd. More importantly, such decreasing trends of TOF values as a function of the Pd size gradually disappeared when raising the reaction temperature. It implies that there is a thermodynamic effect of the Pd size on the FAD reaction, which was evidenced by a continuous increase in the activation energy from 44.9 kJ/mol to 63.9 kJ/mol with the Pd size. We proposed that the H2 desorption step is the rate-determining step for FAD reaction. Such proposal can explain the size-dependent catalytic activity and the increase in the activation energy of FAD with the Pd size enlargement, as the temperature programmed hydrogen decomposition (TPHD) analysis demonstrated that the large Pd particle requires a high temperature/energy to desorb hydrogen from Pd. Consequently, it is concluded that the size-dependent catalytic activity of FAD is attributed not only to the number of active sites but also to the thermodynamic factor relating to the rate-determining step.

Enhanced photoelectrochemical performance for hydrogen generation via introducing Ti3+ and oxygen vacancies into TiO2 nanorod arrays

Rutile TiO2 nanorod arrays were synthesized by a hydrothermal process, followed by NaBH4 treatment to obtain reduced TiO2 nanorods to be used as a photoanode for enhancement of photoelectrochemical (PEC) hydrogen generation. The NaBH4 treatment introduced Ti3+ and oxygen vacancy states in the TiO2 lattice, which increased the light absorption range and electrical conductivity of the photocatalyst, limiting the charge carrier recombination and thus enhancing the PEC properties performance of hydrogen generation. X-ray photoelectron spectra (XPS) and electron paramagnetic resonance (EPR) analysis confirmed the presence of Ti3+ and oxygen vacancies in the TiO2 nanorod after reducing. The optimal reduced TiO2 nanorod has been achieved after reaction with 2 M NaBH4 solution for 3 h, followed by HCl solution washing which improved the PEC performance. At 0.23 V vs Ag/AgCl (1.23 V vs RHE), the reduced TiO2 nanorod generated a photocurrent density of 4.03 mA/cm2 which is two times higher than the pristine TiO2 nanorod. Semiconductor/electrolyte interfacial charge transfer was investigated by electrochemical impedance spectra (EIS) using the Nyquist plots. So the reduced TiO2 nanorod presented a smaller resistance than that of TiO2 nanorod, thus oxygen vacancies enhanced the electrical conductivity in the reduced TiO2 nanorod. It is worth noticing that the Mott–Schottky plots revealed an increase in the donor density after NaBH4 treatment, while the reduced TiO2 remained n-type as the rutile TiO2.

Enhanced photocatalytic activity of surface disorder-engineered CaTiO3

In this work, we attempted to create surface disorder on CaTiO3 nanocuboids by NaBH4 treatment with the aim of enhancing the photocatalytic activity. The samples were systematically investigated by XRD, SEM, TEM, BET, XPS, UV–vis DRS, PL, EIS and photocurrent response. The photocatalytic activity of the samples were evaluated by degrading RhB under irradiation of simulated sunlight, UV and visible light. It is demonstrated that NaBH4-treated CaTiO3 samples exhibit an obviously enhanced photocatalytic activity. In particular, the sample treated at 0.1 M NaBH4 solution has a photocatalytic activity ca. 2.0 times higher than pristine CaTiO3. This is ascribed to the fact that the created surface disorder facilitates the separation of photogenerated electron-hole pairs, and thus more photogenerated holes are able to participate in the photocatalytic reactions.

Inorganic–Organic Hybrid 3D Redox Nanoarchitecture for the Electrocatalytic Sensing of Thiols

We demonstrate the development of a novel redox active three-dimensional (3D) functional hybrid nanoarchitecture based on reduced graphene oxide (rGO) and sol–gel derived silicate network for the mediated electrocatalytic sensing of biological thiols. First, the thiol functionalized hybrid material was synthesized by the cross condensation reaction between graphene oxide (GO) and the in situ generated silanol derived from 3-(mercaptopropyl)trimethoxysilane (MPTS). The chemisorption of the hybrid material on Au electrode and the subsequent NaBH4 treatment yield the thiol-terminated 3D hybrid inorganic–organic self-assembly. The 3D hybrid assembly was further tailored with a redox active 4-methyl catechol (MCA) or catechol (CA) moiety by taking advantage of the bias-driven Michael addition reaction between the surface-confined thiol-terminated self-assembly and electrogenerated quinone. The Michael addition of quinone was quantitatively monitored by electrochemical quartz crystal microbalance (EQCM). The redox-tailored architecture displays reversible voltammetric response corresponding to the redox reaction of catechol/quinone redox couple with standard heterogeneous rate constant of 75.74 s–1 (for CA) and 71.43 s–1 (for MCA). The MCA-tailored 3D hybrid architecture efficiently mediates the oxidation of biological thiols (cysteine, homocysteine, and glutathione). However, the CA-tailored hybrid architecture favors the Michael addition of biological thiols, as evidenced by EQCM studies. The kinetics for the mediated electrocatalytic oxidation of biological thiols on MCA-tailored assembly was studied using a rotating disk electrode. The rate constant for the oxidation of cysteine is higher than those of the other two thiols. The MCA-tailored hybrid assembly is highly sensitive, and we could achieve a very low detection limit of 0.3 nM in flow injection analysis at the potential of 270 mV. The electrode is highly stable, and only 10% decrease in the initial amperometric current was observed after 7 days.

Highly Efficient and Durable Pd Hydride Nanocubes Embedded in 2D Amorphous NiB Nanosheets for Oxygen Reduction Reaction

AbstractA highly efficient and durable electrocatalyst of Pd hydride nanocubes encapsulated within 2D amorphous Ni‐B nanosheets is reported. The PdH0.43 nanocubes are first synthesized via a simple N,N‐dimethylformamide thermal treatment. The as‐synthesized PdH0.43 nanocubes are then encapsulated in 2D amorphous NiB nanosheets by NaBH4 reduction in the presence of nickel species. During the NaBH4 treatment, the PdH0.43 can be further transformed into PdH0.706 due to the presence of endogenous H2. Electrochemical studies demonstrate that the degree of hydride of Pd nanocubes (PdHx) plays an important role in the enhancement of their oxygen reduction reaction (ORR) activity. With increasing x value, both the activity and stability increase significantly. At 0.90 V versus reversible hydrogen electrode, the ORR activity of PdH0.706 @Ni‐B reaches 1.05 A mgPd−1, which is nearly five times higher than that of the state‐of‐the‐art Pt catalysts. Accelerated durability tests show that even after 10 000 potential cycles, there is negligible shift in their half‐wave potential and no shape and structure change occurs, indicating the incorporation of amorphous 2D Ni‐B nanosheets can greatly improve their stability without compromising their activity. The present study illustrates the importance of high degree of hydride and presence of amorphous Ni‐B nanosheets on the enhancement of ORR activity for Pd‐based electrocatalyst.

NaBH4 modified TiO2: Defect site enhancement related to its photocatalytic activity

Defected TiO2 nano-powder was synthesized by applying NaBH4 assisted heat treatment (300–450 °C) on pristine TiO2 nanoparticles under argon atmosphere. By increasing the process temperature, higher defect percentage (oxygen vacancies) can be achieved. In line with the defect concentration, significant enhancement of absorption in visible light also observed. Further characterization reveal that the defect created via NaBH4 treatment is mainly bulk defect which trigger recombination of electrons and holes. The concentration of defect contributes to the photocatalytic activity. Controllable defect produced by NaBH4 reduction at 350 °C lead to the better photocatalytic activity performance of Rhodamine B degradation under simulated solar light.

Key factors improving oxygen reduction reaction activity in cobalt nanoparticles modified carbon nanotubes

Multiwall carbon nanotubes (CNTs) decorated with cobalt oxide (CoOx) nanoparticles (NPs) are prepared in various synthesis conditions to investigate their capability as oxygen reduction reaction (ORR) catalysts for fuel cells in alkaline media. The synthesis conditions include the use of protecting, reducing or complexing agents and heat treatment. Higher ORR activity is possible for smaller size of Co NPs catalysts due to the enlarged interfaces between Co species and CNTs. The addition of polyvinylpyrrolidone (PVP) as protecting agent and NaBH4 during the preparation procedure is necessary for obtaining the highest activity since it favors the formation of lower oxidation states for Co species and the incorporation of N groups which improve ORR activity. CNTs loaded with only 1wt.% of Co NPs prepared by a facile method using PVP, NaBH4 and subsequent heat treatment at 500°C under N2 atmosphere, demonstrates both similar catalytic activity and stability than Pt/Vulcan (20wt.% Pt on Vulcan). The synergic chemical coupling effects between CNTs and CoOx NPs and the presence of carbon material with pyridinic N and quaternary N groups formed from the protecting agent decomposition, seem to be the main factors responsible for the remarkable electrocatalytic activity.

Collagen fibrils in functionally distinct tendons have differing structural responses to tendon rupture and fatigue loading

In this study we investigate relationships between the nanoscale structure of collagen fibrils and the macroscale functional response of collagenous tissues. To do so, we study two functionally distinct classes of tendons, positional tendons and energy storing tendons, using a bovine forelimb model. Molecular-level assessment using differential scanning calorimetry (DSC), functional crosslink assessment using hydrothermal isometric tension (HIT) analysis, and ultrastructural assessment using scanning electron microscopy (SEM) were used to study undamaged, ruptured, and cyclically loaded samples from the two tendon types. HIT indicated differences in both crosslink type and crosslink density, with flexor tendons having more thermally stable crosslinks than the extensor tendons (higher TFmax of >90 vs. 75.1±2.7°C), and greater total crosslink density than the extensor tendons (higher t1/2 of 11.5±1.9 vs. 3.5±1.0h after NaBH4 treatment). Despite having a lower crosslink density than flexor tendons, extensor tendons were significantly stronger (37.6±8.1 vs. 23.1±7.7MPa) and tougher (14.3±3.6 vs. 6.8±3.4MJ/m3). SEM showed that collagen fibrils in the tougher, stronger extensor tendons were able to undergo remarkable levels of plastic deformation in the form of discrete plasticity, while those in the flexor tendons were not able to plastically deform. When cyclically loaded, collagen fibrils in extensor tendons accumulated fatigue damage rapidly in the form of kink bands, while those in flexor tendons did not accumulate significant fatigue damage. The results demonstrate that collagen fibrils in functionally distinct tendons respond differently to mechanical loading, and suggests that fibrillar collagens may be subject to a strength vs. fatigue resistance tradeoff. Statement of SignificanceCollagen fibrils—nanoscale biological cables—are the fundamental load-bearing elements of all structural human tissues. While all collagen fibrils share common features, such as being composed of a precise quarter-staggered polymeric arrangement of triple-helical collagen molecules, their structure can vary significantly between tissue types, and even between different anatomical structures of the same tissue type. To understand normal function, homeostasis, and disease of collagenous tissues requires detailed knowledge of collagen fibril structure-function. Using anatomically proximate but structurally distinct tendons, we show that collagen fibrils in functionally distinct tendons have differing susceptibilities to damage under both tensile overload and cyclic fatigue loading. Our results suggest that the structure of collagen fibrils may lead to a strength versus fatigue resistance tradeoff, where high strength is gained at the expense of fatigue resistance, and vice versa.

Effects of Aging on Electrocatalytic Activities of Pt and Pd Nanoparticles

Although the time dependences of the electrocatalytic activities of Pt and Pd nanoparticles during electrochemical operations have been widely studied, the time dependences under nonpolarized conditions have never been investigated in depth. This study reports the changes in the electrocatalytic activities of Pt and Pd nanoparticles with aging in air and in solution. Pt (or Pd) nanoparticle-modified electrodes are obtained by adsorbing citrate-stabilized Pt (or Pd) nanoparticles on amine-modified indium-tin oxide (ITO) electrodes, or by electrodeposition of Pt (or Pd) nanoparticles on ITO electrodes. The electrocatalytic activities of freshly prepared Pt and Pd nanoparticles in the oxygen reduction reaction slowly decrease with aging. The electrocatalytic activities decrease more slowly in solution than in air. An increase in surface contamination may cause electrocatalytic deactivation during aging. The electrocatalytic activities of long-aged Pt (or Pd) nanoparticles are significantly enhanced and recovered by NaBH4 treatment. Keywords: Pt nanoparticles, Pd nanoparticles, electrocatalytic activity, oxygen reduction reaction, aging

A remote-controlled generation of gold@polydopamine (core@shell) nanoparticles via physical-chemical stimuli of polydopamine/gold composites.

We present the synthesis of polydopamine particle-gold composites (PdopP-Au) and unique release of Au@Pdop core@shell nanoparticles (NPs) from the PdopP-Au upon external stimuli. The PdopP-Au was prepared by controlled synthesis of AuNPs on the Pdop particles. Upon near infrared (NIR) irradiation or NaBH4 treatment on the PdopP-Au, the synthesized AuNPs within the PdopPs could be burst-released as a form of Au@Pdop NPs. The PdopP-Au composite showed outstanding photothermal conversion ability under NIR irradiation due to the ultrahigh loading of the AuNPs within the PdopPs, leading to a remote-controlled explosion of the PdopP-Au and rapid formation of numerous Au@Pdop NPs. The release of the Au@Pdop NPs could be instantly stopped or re-started by off or reboot of NIR, respectively. The structure of the released Au@Pdop NPs is suitable for a catalyst or adsorbent, thus we demonstrated that the PdopP-Au composite exhibited excellent and sustained performances for environmental remediation due to its capability of the continuous production of fresh catalysts or adsorbents during the reuse.

Rapid synthesis of hybrids and hollow PdO nanostructures by controlled in situ dissolution of a ZnO nanorod template: insights into the formation mechanism and thermal stability.

Hollow nanomaterials have attracted a lot of interest by virtue of their wide range of applications that arise primarily due to their unique architecture. A common strategy to synthesize hollow nanomaterials is by nucleation of the shell material over a preformed core and subsequent dissolution of the core in the second step. Herein an ultrafast, microwave route has been demonstrated, to synthesize PdO nanotubes in a single step using ZnO as a sacrificial template. The mechanism of the nanotube formation has been investigated in detail using control experiments. By tuning the starting ratio of PdCl2 : ZnO, hollow to hybrid PdO nanostructures could be obtained using the same method. Conversion of the PdO to Pd nanotubes has been shown by simple NaBH4 treatment. The thermal stability of the PdO nanotubes has been studied. The insights presented here are general and applicable for the synthesis of hybrids/hollow structures in other systems as well.

Synthesis and magnetism of hierarchical iron oxide particles

Abstract The hierarchical polyhedral α-Fe2O3 oxide particles, and hierarchical spherical CoFe2O4 oxide particles in the microsized ranges have been successfully prepared via modified polyol methods with NaBH4 and heat treatment process. An exact comparison was presented in the soft magnetic properties and structures of new hierarchical α-Fe2O3 and CoFe2O4 oxide particles. To study Fe-based oxide microparticles, X-ray diffraction, scanning electron microscopy with energy dispersive spectroscopy, X-ray photoelectron spectroscopy, and vibrating sample magnetometer have been used to characterize their microstructures and magnetic properties according to the preparation processes. The hierarchical α-Fe2O3 and CoFe2O4 oxide microparticles with oxide grain and grain boundary textures were perfectly formed under heat treatment at high temperature without any chemical self-assembly methods. For this exciting research, the various kinds of homogeneous hierarchical Fe-based oxide particles can be successfully produced in the large amount for commercialization. It is discovered that MS of hierarchical CoFe2O4 particles is much larger than that of hierarchical α-Fe2O3 particles about 93 times. The coordination numbers of Co and Fe cations at tetrahedral and octahedral sites lead to determine its magnetic behavior. Finally, hierarchical Fe-based oxide particles are proposed for promising and potential candidates for energy and environment related technologies associated with safety and sustainability.

Glyceraldehyde-3-phosphate dehydrogenase (GAPDH) interacts with apurinic/apyrimidinic sites in DNA

Apurinic/apyrimidinic (AP) sites are some of the most frequent DNA damages and the key intermediates of base excision repair. Certain proteins can interact with the deoxyribose of the AP site to form a Schiff base, which can be stabilized by NaBH4 treatment. Several types of DNA containing the AP site were used to trap proteins in human cell extracts by this method. In the case of single-stranded AP DNA and AP DNA duplex with both 5′ and 3′ dangling ends, the major crosslinking product had an apparent molecular mass of 45kDa. Using peptide mass mapping based on mass spectrometry data, we identified the protein forming this adduct as an isoform of glyceraldehyde-3-phosphate dehydrogenase (GAPDH) called “uracil-DNA glycosylase”. GAPDH is a glycolytic enzyme with many additional putative functions, which include interaction with nucleic acids, different DNA damages and DNA repair enzymes. We investigated interaction of GAPDH purified from HeLa cells and rabbit muscles with different AP DNAs. In spite of the ability to form a Schiff-base intermediate with the deoxyribose of the AP site, GAPDH does not display the AP lyase activity. In addition, along with the borohydride-dependent adducts with AP DNAs containing single-stranded regions, GAPDH was also shown to form the stable borohydride-independent crosslinks with these AP DNAs. GAPDH was proven to crosslink preferentially to AP DNAs cleaved via the β-elimination mechanism (spontaneously or by AP lyases) as compared to DNAs containing the intact AP site. The level of GAPDH–AP DNA adduct formation depends on oxidation of the protein SH-groups; disulfide bond reduction in GAPDH leads to the loss of its ability to form the adducts with AP DNA. A possible role of formation of the stable adducts with AP sites by GAPDH is discussed.