Changes In Surface Structure Research Articles

The effects of mutation and modification on the structure and stability of human lysozyme: A molecular link between carbamylation and atherosclerosis

Amino acid mutations in some proteins such as lysozyme lead to genetically disorder variants and adverse pathogenic consequences. Recently, amino acid modifications were known as a risk factor in many related diseases such as uremia and atherosclerosis, showing the importance of these surface-structure changes. Although the structural consequences of the hereditary proteins have been examined extensively, such effects for the protein modifications are known to a lesser extent. One drawback in the examination of protein modifications is hardness in experimental detection of modifications by techniques such as NMR and crystallography. Molecular modeling and simulation can help to understand such phenomena at the molecular levels. It is more rational that the effects of both mutation and modification can be compared in a single protein model. Here, molecular dynamics simulation is used to compare the effects of a disease-related carbamylation modification and an amyloidogenic mutation (D67H) in human lysozyme as a model protein. The results show that the carbamylation adversely effects on the tertiary structure, leading to the similar unfolding pathway to the hereditary amyloidogenic form. The carbamylation leads to the instability of the overall protein conformation, especially on the β-domain, which is a characteristic of hereditary amyloidosis in human lysozymes. The aggregation behaviors of both modified and mutant lysozyme were examined by molecular docking calculations. The results showed that the partially unfolded lysozyme might form tight protein aggregates upon carbamylation similar to the amyloidogenic variant. Both single and all-residues carbamylations impose serious conformational changes to the tertiary structure of lysozyme. It was obtained that carbamylation of lysozyme strongly effects on the stability of N-terminal β-sheet, which can produce a highly unstable conformation. The results of this study not only show the adverse structural consequences of a disease-associated post-translational modification, but it also may be very helpful to understand the molecular basis for many carbamylation-related diseases such as atherosclerosis in ESRD patients. The results show that non-native post-translational modifications may be as structurally important as hereditary mutations.

Effect of radiation damage on the migration behaviour of europium implanted into polycrystalline SiC at RT, 350 °C and 600 °C

In this work, the effect of radiation damage on the migration behaviour of europium (Eu) implanted into polycrystalline SiC was investigated. Polycrystalline Silicon Carbide (SiC) substrates were separately implanted with europium (Eu) ions of 270 keV to a fluence of 1 × 1016 cm−2 at room temperature (RT), 350 °C and 600 °C. The samples were thermally annealed at temperatures ranging from 1000 to 1400 °C in steps of 100 °C for 5 h in vacuum. The as-implanted and annealed samples were characterized by Rutherford Backscattering Spectrometry (RBS) to monitor the depth profile of the implanted Eu, Scanning Electron Microscopy (SEM) and Raman spectroscopy to monitor surface morphology and structural changes respectively. Raman results indicated that a full amorphization was achieved in the room temperature implanted samples but not in the 350 and 600 °C implanted samples. The radiation damage gradually annealed out with increasing annealing temperature in all implanted samples; however, the full re-crystallization was not achieved up to the highest temperature. The broadening of Eu depth profile indicated some diffusion mechanism taking place in the room temperature implanted sample up to 1300 °C annealing temperature was observed. The diffusion coefficients were determined as 0.015, 0.033 and 0.035 nm2/s for samples annealed at 1000 °C, 1100 °C and 1200 °C, respectively. The 350 °C implanted sample indicated a similar form of diffusion mechanism taking place after annealing at 1000 °C, with no further peak broadening taking place at higher temperatures. A diffusion coefficient of 0.019 nm2/s was obtained at this temperature. A diffusion behaviour due to broadening after annealing at 1100 °C and higher temperatures was also observed in the 600 °C implanted sample which retained most of the implanted Eu. Due to the error limit of our RBS system, no reliable diffusion coefficients could be extracted for this sample.

Correlation between surface chemistry and morphology of PtCu and Pt nanoparticles during oxidation-reduction cycle

Process conditions during catalytic reactions induce significant changes in surface chemistry and structure of bi- (mono) metallic nanoparticles leading to their deactivation, and this can ultimately affect the reactions long-term performance. Here PtCu and Pt model nanoparticles are prepared by microwave synthesis and characterized by X-ray diffraction (XRD). Surface chemical and morphological changes of the nanoparticles during high-temperature oxidation and reduction treatments cycle are correlated by near in situ X-ray photoelectron spectroscopy (XPS) and ex situ transmission electron microscopy (TEM) - energy-dispersive X-ray spectroscopy (EDS) studies. At 300 °C the surface atomic composition of the PtCu nanoparticles switches reversibly upon the cycle and at the same time their morphology and composition are maintained. At 400 °C, the surface atomic composition does not fully restore and, while the shape is maintained, the size and composition are not. This occurs by a mechanism of Cu leaching out from the nanoparticles. These data delineate potential operating conditions for stable PtCu nanocatalysts.

Geomorphology study in relation to ground subsidence on urban area with sandbox simulation

Ground subsidence on urban area are one of the major factors of disaster. in urban area such as Jakarta, ground subsidence is frequently occurred on main road and densely populated building. Study of surface elevation changes due to influence of groundwater movement have broadly discussed. In Many areas of subsidence caused by groundwater pumping have been identified and monitored. To understand more advance in subsidence process through direct experiment. The sandbox simulation of surface structure changes due to material movement. The simulation projects the surface elevation changes due to loss of mass.

Effect of drying on tensile properties and structure of tasar and muga silk

Tasar and muga silk yarns have been dried at 80ºC, 100ºC and 140ºC and the effect of temperature on tensile and structural properties is investigated. No significant effect of drying on tenacity of tasar and muga silk yarn is observed. However, elongation decreases with drying due to increase in moisture loss with temperature. Crystallinity has no effect even when dried up to 140˚C. Scanning electron micrograph study reveals that there is no significant change in surface structure with different temperature of drying.

Analytes Triggered Conformational Switch of i-Motif DNA inside Gold-Decorated Solid-State Nanopores.

The nanopore-based technique is a useful tool for single-molecule sensing and characterization. In this work, we have developed a new DNA-functionalized gold-modified nanopore, and analytes can induce the conformational switch of i-motif DNA formed on the inner surface of the nanopore. i-Motif DNA structure can be formed in the presence of silver ions (Ag+), which will result in the change in surface charge and structure of the nanopore tip and ion current rectification (ICR) ratio. The i-motif DNA structure on nanopore surface will be destroyed after the addition of glutathione (GSH) due to the strong interaction of Ag-S bond, which results in the recovery of surface charge, steric hindrance, and ICR ratio. This analyte-triggered conformational switch of i-motif DNA can help us deeply understand the DNA technology inside single nanopore and will benefit the possible applications in an ultrasensitive detection and biological/chemical analysis.

Multi-wavelength Raman microspectroscopic studies of modified monwoven carbon scaffolds for tissue engineering applications

The articular cartilage is almost a non-vascular tissue, therefore it has a very low ability to heal itself. The analyzed carbon nonwoven material, obtained by polyacrylonitrile precursor carbonization, seem to be a new option for the complementation of cartilage losses due to a unique ability of this material to restore of cartilage tissue. The analyzed carbon material may be a new option to supplement cartilage defects due to the ability of this material to restore cartilage tissue. This study presents several examples of surface modification of nonwoven carbon fibers materials forming scaffold using ceramic nanoparticles, nanosilica and nanohydroksyapatite. Surface structural changes were examined by SEM observations, composition was assessed by EDS. The results indicate that the apatite phase on the surface of nonwoven fibers is formed, and its composition depends on the type of surface. The obtained multiwavelength Raman microspectroscopy results, G-band dispersion course and also the ID/IG intensity ratio dispersion, allowed to indicate the nanocrystaline graphite organization of the fibers with the presence of certain disorder. In this way, the resulting ordering in the tested materials also indicates the material’s production parameters. All scaffolds were evaluated by examining the ability of apatite to form on the materials incubated in simulated body fluids (SBF).

Surface regulation enables high stability of single-crystal lithium-ion cathodes at high voltage

Single-crystal cathode materials for lithium-ion batteries have attracted increasing interest in providing greater capacity retention than their polycrystalline counterparts. However, after being cycled at high voltages, these single-crystal materials exhibit severe structural instability and capacity fade. Understanding how the surface structural changes determine the performance degradation over cycling is crucial, but remains elusive. Here, we investigate the correlation of the surface structure, internal strain, and capacity deterioration by using operando X-ray spectroscopy imaging and nano-tomography. We directly observe a close correlation between surface chemistry and phase distribution from homogeneity to heterogeneity, which induces heterogeneous internal strain within the particle and the resulting structural/performance degradation during cycling. We also discover that surface chemistry can significantly enhance the cyclic performance. Our modified process effectively regulates the performance fade issue of single-crystal cathode and provides new insights for improved design of high-capacity battery materials.

The R2R3-MYB transcription factor AtMYB49 modulates salt tolerance in Arabidopsis by modulating the cuticle formation and antioxidant defence.

Salt stress activates defence responses in plants, including changes in leaf surface structure. Here, we showed that the transcriptional activation of cutin deposition and antioxidant defence by the R2R3-type MYB transcription factor AtMYB49 contributed to salt tolerance in Arabidopsis thaliana. Characterization of loss-of-function myb49 mutants, and chimeric AtMYB49-SRDX-overexpressing SRDX49 transcriptional repressor and AtMYB49-overexpressing (OX49) overexpressor plants demonstrated a positive role of AtMYB49 in salt tolerance. Transcriptome analysis revealed that many genes belonging to the category "cutin, suberin and wax biosyntheses" were markedly up-regulated and down-regulated in OX49 and SRDX49 plants, respectively, under normal and/or salt stress conditions. Some of these differentially expressed genes, including MYB41, ASFT, FACT and CYP86B1, were also shown to be the direct targets of AtMYB49 and activated by AtMYB49. Biochemical analysis indicated that AtMYB49 modulated cutin deposition in the leaves. Importantly, cuticular transpiration, chlorophyll leaching and toluidine blue-staining assays revealed a link between increased AtMYB49-mediated cutin deposition in leaves and enhanced salt tolerance. Additionally, increased AtMYB49 expression elevated Ca2+ level in leaves and improved antioxidant capacity by up-regulating genes encoding peroxidases and late embryogenesis abundant proteins. These results suggest that genetic manipulation of AtMYB49 may provide a novel way to improve salt tolerance in plants.

Changes in surface structure and mechanical characteristics of Al–5 wt%Si alloy after irradiation by electron beam

The modification of Al–5 wt%Si alloy surface by electron beam in the regimes being different in the energy density of electron beam (10, 20, 30, 40 and 50 J/cm2) and the pulse duration (50 and 200 μs) was performed in the research. It was established that the maximum increase in microhardness was observed at electron beam parameters of 30 J/cm2, 200 μs and 50 J/cm2, 50 μs; and microhardness values for each regime amounted to 860 MPa and 950 MPa, respectively. The microhardness value of the cast alloy equals to 520 MPa. The irradiation surface morphology at beam parameters of 30 J/cm2, 200 μs is characterised by numerous micropores and microcracks. The irradiation regime of 50 J/cm2, 50 μs leads to complete dissolution of intermetallide and silicon particles in surface layer; the crack density per unit of sample surface decreases in comparison with the regime of 30 J/cm2, 200 μs. The surface layer is characterised by the high-speed cellular crystallization structure with dimensions from 500 to 800 nm formed in grain volume that may be the reason for the increase in strength properties of the material.

Development of Rice Straw Paper Coated with Pomelo Peel Extract for Bio-Based and Antibacterial Packaging

This study aimed to develop paper packaging from rice straw fibers with its function as antibacterial activity obtained from pomelo (Citrus maxima) peels. Paper with ca. 106.42 g/m2 basis weight, 0.34 mm thickness, 34.15 % brightness and 78.7 N.m/g tensile index was prepared from rice straw fibers and pulps. Bioactive compounds of crude pomelo peels extracted using maceration technique with 75% (v/v) ethanol were coated onto rice straw papers at concentration of 10, 15 and 20 % (w/v). The coated papers had similar thickness, and slightly lower tensile index and brightness as compared to those of control papers. Scanning electron microscopy confirmed the changes of surface and cross-section structures of coated and uncoated papers. The rice straw coated papers had relatively greater barrier property to prevent water absorption. In addition, the coated papers with pomelo peel extract showed significant antibacterial activity against food pathogenic bacteria, including Staphylococcus aureus, Bacillus cereus and Escherichia coli. This study reveals the benefits of natural by-products as a potential material for active packaging.

Structural evaluation of percolating, self-healing polyurethane–polycaprolactone blends doped with metallic, ferromagnetic, and modified graphene fillers

Composites with differently shaped micro- and nanofillers show various, unique thermal, and physicochemical properties when mixed with carefully chosen polymer matrix. Selected composition holds strategic value in achieving desired properties that is biodegradability, thermoelectric conductivity, and shape memory for organic coating. The main aim of this work is to briefly examine structural changes after reaching percolation threshold and activating healing abilities within exploited (8–2 wt ratio) polyurethane–polycaprolactone thin films mixed up with different types of metallic and ferromagnetic microfillers. They, with applicable dosages of reduced graphene oxide nanoparticles, should enhance materials’ mechanical and conductive properties. Microscopic and spectroscopic techniques accompanied by extensive thermal analysis have been chosen to provide useful information about local changes in surface structure and morphology. Moreover, pristine, percolating surface with inner-formed, metallic structures shows moderate conducting properties within exploited materials which unfortunately diminish after thermal healing stimulus is being applied. This statement is supported by observing the coverage of regional defects and nearby pores with a concise, uniform layer of blend having different PU:PCL ratio. Including the additional fact that apparent filler migration is changing local dopant composition brings up an assumption that both phenomena have negative synergy effect on each other.

Detection of Crop Seeding and Harvest through Analysis of Time-Series Sentinel-1 Interferometric SAR Data

Synthetic aperture radar (SAR) is more sensitive to the dielectric properties and structure of the targets and less affected by weather conditions than optical sensors, making it more capable of detecting changes induced by management practices in agricultural fields. In this study, the capability of C-band SAR data for detecting crop seeding and harvest events was explored. The study was conducted for the 2019 growing season in Temiskaming Shores, an agricultural area in Northern Ontario, Canada. Time-series SAR data acquired by Sentinel-1 constellation with the interferometric wide (IW) mode with dual polarizations in VV (vertical transmit and vertical receive) and VH (vertical transmit and horizontal receive) were obtained. interferometric SAR (InSAR) processing was conducted to derive coherence between each pair of SAR images acquired consecutively in time throughout the year. Crop seeding and harvest dates were determined by analyzing the time-series InSAR coherence and SAR backscattering. Variation of SAR backscattering coefficients, particularly the VH polarization, revealed seasonal crop growth patterns. The change in InSAR coherence can be linked to change of surface structure induced by seeding or harvest operations. Using a set of physically based rules, a simple algorithm was developed to determine crop seeding and harvest dates, with an accuracy of 85% (n = 67) for seeding-date identification and 56% (n = 77) for harvest-date identification. The extra challenge in harvest detection could be attributed to the impacts of weather conditions, such as rain and its effects on soil moisture and crop dielectric properties during the harvest season. Other factors such as post-harvest residue removal and field ploughing could also complicate the identification of harvest event. Overall, given its mechanism to acquire images with InSAR capability at 12-day revisiting cycle with a single satellite for most part of the Earth, the Sentinel-1 constellation provides a great data source for detecting crop field management activities through coherent or incoherent change detection techniques. It is anticipated that this method could perform even better at a shorter six-day revisiting cycle with both satellites for Sentinel-1. With the successful launch (2019) of the Canadian RADARSAT Constellation Mission (RCM) with its tri-satellite system and four polarizations, we are likely to see improved system reliability and monitoring efficiency.

Surface structure changes of nickel-based catalysts in the syngas methanation process

In order to investigate the surface structure changes of nickel-based catalysts during the syngas methanation process, nickel-based catalysts were prepared with impregnation method and the tests were carried out in a fluidized bed reactor. The test results showed that the catalytic performance declined rapidly with the reaction time. Energy dispersive spectroscopy measurements of the reacted catalyst were carried out and the results indicated that there was carbon observed on the catalysts surface. The carbon deposited on the catalyst surface was removed in a thermogravimetric analyzer to obtain the regenerated catalyst and it was found that the amount of the accumulated carbon on the catalyst surface was 2.09 wt% of the reacted catalyst. N2 adsorption–desorption measurements were conducted on the fresh catalyst, reacted catalyst and regenerated catalyst. The specific area of the reacted catalyst decreased significantly and could not restore to the original level even after removing the deposited carbon. The pore volume of reacted catalyst increased 16.67% compared to the fresh catalyst while the average pore diameter remained almost no change. The pores existing on the fresh catalyst were mainly the mesopores while the pore size distribution expanded and the macrospores came into being on the reacted catalyst. It can be concluded that a kind of stable carbon was produced on the catalyst surface after methanation process, which caused dramatic changes to the surface textural properties.

Regeneration of Reactive Pd Surfaces in Au-Pd Nanoparticles after Electrochemical Aging

One major hurdle in the development of efficient electrocatalysts is deterioration of activity, which can be caused by selective dissolution of metals [1]. The recent development of gold-palladium (Au-Pd) alloy nanoparticles outlines a contemporary strategy to impart increased stability in nanoparticles by combining a more electrochemically stable metal such as Au with lesser stable Pd [2, 3]. Unfortunately, the relative surface-reactivity of Au is poor, and as a result, there is an inevitable design constraint to form Pd-rich outer shell structure - a task that is particularly daunting considering the high dissolution tendency of Pd [4]. Here we present an electrochemical aging method that allows for increasing the Pd concentration at the surface of Au-Pd NPs by means of diffusion of Pd atoms from the particle-core to the shell. The method involves an electrochemical aging treatment in alkaline KOH media for which the choice of suitable upper vertex potential proved to be particularly very important.Au-Pd NPs synthesized by means of liquid-phase laser-ablation method [5] were used in this study, typically ranging in diameter between 14.5 nm to 22.6 nm and composition between Au/Pd: 20/80 to 80/20 ratios. The particle diameter remained homogeneous across the whole composition range, thanks to the size-selectivity of laser-ablation synthesis of alloy molar fraction series, in line with the literature [5]. This allows for excluding any size-effects on the electrochemical behaviour of alloy nanoparticles. The nominal Au/Pd compositions initially fed to the laser appeared to be well preserved down to single-nanoparticle level as confirmed by detailed analyses of the SEM/EDX and XPS spectroscopic data. Formation of Au/Pd solid-solution was also apparent from the estimation of the lattice-parameters using X-ray diffraction (XRD) that varied linearly in accordance with the change in Pd alloy content.The cyclic voltammograms recorded in 0.1M N2-saturated KOH revealed features characteristic of both Au and Pd surfaces, e.g., the reduction peaks at 0.98 V and 0.55 V vs RHE (respectively), which was reflective of a mixed Au and Pd surface-structure exposed to the electrochemical treatments. Importantly, both the peak-positions and the integrated surface-charge shifted in correspondence with the variable Pd content in the alloys, thus serving as the initial markers of the surface-state before further electrochemical treatments.Marked differences could be noted between the electrochemical behaviours in acid and the alkaline media, as well as the potential range and the number of cycles involved ( Figure 1 ). The initial H-desorption/adsorption peaks (A, B) and the PdO reduction peaks apparent at the onset of aging in 0.5M H2SO4 gradually disappeared with subsequent cycling (C1), along with the concomitant rise in the Au oxide reduction peaks (D1), indicative of gradually dissolution of Pd. Importantly, the lost Pd surface surprisingly regenerated (C2) with subsequent aging in 0.1M KOH media, particularly at sweeping potentials extending to very positive values. The regenerated Pd-rich surface is attributed to preferential diffusion of Pd from particle cores- to the surface aided by surface-reconstruction via a ‘place-exchange’ between adsorbed-oxygen and Pd. Detailed analyses of the XPS Pd-3d3/2 and Au-4f7/2 edges and the respective STEM-EDX elemental profiles are in good agreement with the changes of surface-structures proposed from the cyclic voltammetry measurements. All the alloys were simultaneously tested for oxygen reduction reaction (ORR).[1] Gasteiger, H. A., et al. (2005). Applied Catalysis B: Environmental, 56(1-2), 9-35.[2] Xu, J. B., et al. (2010). International Journal of Hydrogen Energy, 35(13), 6490-6500.[3] Sasaki, K., et al. (2010). Angewandte Chemie International Edition, 49(46), 8602-8607.[4] Rand, D. A. J., et al. (1972). Journal of Electroanalytical Chemistry and Interfacial Electrochemistry, 35(1), 209-218.[5] Reichenberger, S., et al. (2019). ChemCatChem, 11, 4489-4518. Figure 1

Influence of alkyl spacer in nanostructure shape control by templateless electropolymerization

Here, we control the shape of the resulting porous structures by templateless electropolymerization, by adjusting the alkyl spacer between thieno[3,4-b]thiophene and pyrene used as the monomer and the substituent, respectively. A huge change is observed from nanotubular structures (1D growth) without alkyl chain to huge hollow spheres (3D growth) for longer alkyl chains (≥ C4H8) passing through ribbon-like structures (2D) for short C2H4 spacer. The presence of a significant amount of water is necessary for the formation of these porous structures because it allows releasing a high amount of gas bubbles. Moreover, this change in surface structures is also observed by varying H2O content. Here, the higher hydrophobic properties with extremely high water adhesion are obtained with the presence of ribbon-like structures. This work is extremely important to investigate the effect of surface structures on surface properties for various potential applications.

An Investigation on the Effects of Surface Structure Changes on Students' Reading Comprehension

Bu çalışmanın amacı, yüzey yapı değişikliğine uğramış bilgilendirici ve hikâye edici metinler ile okuduğunu anlama becerisi açısından düşük, orta ve yüksek seviye olarak gruplandırılan 7. sınıf öğrencilerinin okuduğunu anlama becerileri arasındaki ilişkiyi belirlemektir. Bu amaç doğrultusunda, Türkçe ders kitaplarında bulunan biri bilgilendirici biri hikâye edici türde olmak üzere iki metin üzerinde yapılan yüzey yapı değişiklikleri ile öğrenci seviye gruplarında okuduğunu anlama becerileri arasındaki ilişki tespit edilmiştir. Araştırma, nicel ve nitel verilerin bir arada toplandığı karma yöntem niteliği taşımaktadır. Araştırmanın çalışma grubunu Samsun ili Atakum ve İlkadım ilçesinde bulunan Millî Eğitim Bakanlığına bağlı devlet okullarında 7. sınıfta öğrenim gören 525 öğrenci oluşturmaktadır. Araştırmanın nicel verileri SPSS 21 programında frekans, yüzde, ANOVA, Friedman Testi analizleriyle; nitel verileri ise içerik analizi ile değerlendirilmiştir. Araştırma sonunda, yüzey yapı değişiklikleri ile öğrencilerin okuduğunu anlama becerileri arasında anlamlı bir ilişki olduğu; öğrencilerin metinler üzerinde yapılan yüzey yapı değişikliklerine karşı olumlu görüş belirttikleri sonuçlarına ulaşılmıştır.

Detection of surface structural changes during adsorption events using two-trace two-dimensional (2T2D) correlation spectroscopy

We demonstrate a method by which a pair of spectra acquired using surface-sensitive second-order nonlinear vibrational spectroscopy, visible-infrared sum-frequency generation, can be analyzed in order to readily determine whether changes that occur as a result of varying environmental conditions results in a change in the population of surface molecules, or a structural rearrangement of the surface. This is accomplished via two-trace two-dimensional correlation analysis, a recently developed technique that uses spectral phase information to provide a level of comparison beyond what can be achieved by simple spectral subtraction or division. While surface reorientation and/or a change in the degree of ordering are often difficult to detect from spectra obtained in a single beam polarization, without detailed analysis of the lineshape, we show that such changes provide strong asynchronous cross peaks in the frequency correlation map.

Construction and selective removal of Cd ion based on diatom-based Cd (II) ion-imprinted composite adsorbent

The present work displays diatom as an ecofriendly material replace to the conventional costly synthetic matrixes for surface imprinting technology. In this study, novel green Cd (II) ion-imprinted composite adsorption material (SH/DE-IIP) was synthesized by surface ion-imprinting technique for selective removal of cadmium ions from aqueous solutions. Various characterization methods have confirmed the structural transformation on the diatom surface. The changes in surface morphology and structure were characterized by SEM. N2 adsorption-desorption analysis revealed the adsorption material possessed microporous structure. XRD and FTIR spectra have shown the functional monomers were successfully introduced into the surface of diatom by observing changes in characteristic functional groups. XPS spectra have shown the bonding relationship of the material with a coordination S-Cd bond, effectively utilizing the surface-active structure characteristic of diatom, and the three-dimensional cross-linked structures were presented after the cross-linking reaction. Due to the unique pore structure provided by diatoms, the mass transfer of the SH/DE-IIP was enhanced after functional modification, and SH/DE-IIP exhibited significantly improved adsorption efficiency for Cd(II) ions. Combined with XPS quantitative analysis, the calculation formula of grafting percentage for the diatoms and the functional monomers was derived, while a grafting model was constructed to evaluate the removal effect. The calculated grafting percentage indicated that the SH/DE-IIP provided a good compounding effect. The adsorption studies revealed the SH/DE-IIP possessed a good adsorption performance for Cd (II), and the adsorption equilibrium was reached in 30 min. The adsorption behaviors followed the pseudo-second-order kinetic model and the adsorption isotherms are described well by Langmuir isotherm adsorption model. The relative selectivity coefficients for Cd(II)/Ni(II), Cd(II)/Zn(II), and Cd(II)/Cu(II) were 1.56, 1.67, and 1.50, respectively. The more results showed that the SH/DE-IIP has the excellent selectivity and the good reusability. The obtained Cd ion-imprinted composite adsorption material exhibited a good directional removal performance for Cd (II) from aqueous solutions. This work not only provides a new material strategy for preparation of ion-imprinted materials, but also provides new insights into the structure of imprinted materials.

Effect of Silica Content on Support-Iridium Active Phase Interactions on the Nanocatalyst Activity

To discuss the potential role of the support for iridium catalyst, we have proceeded to prepare a series of supported catalysts with the same active phase content, but different silica content, to elucidate the changes in surface structure and the reaction process of hydrous hydrazine decomposition on catalyst. The obtained iridium catalysts contained 20 wt% of nanoparticles dispersed on spherical mesoporous alumina and aluminosilicate supports for hydrogen generation from hydrous hydrazine. Iridium nanoparticles with different morphologies and diameters could be produced over the catalyst supports depending on its nature. The iridium catalysts were characterized by some techniques such as XRD, FESEM, BET, TGA, H2-TPR, and mechanical properties. The type of catalyst support played an important role in the effectiveness of the catalyst particles, leading to different activities for hydrazine monohydrate decomposition. Under the given test conditions, the performance of the catalyst was better when using alumina granular as the catalyst support than when using aluminosilicate granular. Since the aluminosilicate support was less reactive than the alumina, hydrogen selectivity was relatively small; consequently, the reaction rate was lower when using the aluminosilicate support than when using the alumina support.