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Experimental water-to-methyl ethyl ketone partition coefficients have been determined for 34 different organic solutes at ambient room temperature based on gas–liquid chromatographic measurements. ...

The chemical structures of Co oxynitrides – in particular, interactions among N and O atoms bonded to the same cobalt – are of great importance for an array of catalytic and materials applications. X-ray diffraction (XRD), core and valence band X-ray photoelectron spectroscopy (XPS) and plane wave density functional theory (DFT) calculations are used to probe chemical and electronic interactions of nitrogen-rich CoO1−xNx (x > 0.7) films deposited on Si(100) using NH3 or N2 plasma-based sputter deposition or surface nitridation. Total energy calculations indicate that the zinc blende (ZB) structure is energetically favored over the rocksalt (RS) structure for x > ∼0.2, with an energy minimum observed in the ZB structure for x ∼ 0.8–0.9. This is in close agreement with XPS-derived film compositions when corrected for surface oxide/hydroxide layers. XRD data indicate that films deposited on Si(100) at room temperature display either a preferred (220) orientation or no diffraction pattern, and are consistent with either rocksalt (RS) or zinc blende (ZB) structure. Comparison between experimental and calculated X-ray excited valence band densities of states – also similar for all films synthesized herein – demonstrates a close agreement with a ZB, but not an RS structure. Core level XPS spectra exhibit systematic differences between films deposited in NH3 vs N2 plasma environments. Films deposited by N2 plasma magnetron sputtering exhibit greater O content as evidenced by systematic shifts in N 1s binding energies. Excellent agreement with experiment for core level binding energies is obtained for DFT calculations based on the ZB structure, but not for the RS structure. The agreement between theory and experiment demonstrates that these N-rich Co oxynitride films exhibit the ZB structure, and forms the basis of a predictive model for understanding how N and O interactions impact the electronic, magnetic and catalytic properties of these materials.

Electroless functionalization of cerium oxide nanoparticles (NPs) based on the grafting of aryl groups from the reduction of diazonium salts is presented as a useful and facile method for enhancing the properties of the NPs. For this study, 4-methyl-, 4-ethyl-, and 4- n-butyl-benzene diazonium salts were used as model molecules to demonstrate the ability to change the hydrophobic properties of the cerium oxide (CeO

A study on corrosion inhibition mechanism has been performed on rare earth containing WE43 magnesium alloy in 3.5 wt.% NaCl containing 8-hydroxyquinoline (HQ). After an initial increase in corrosion rate due to the formation of sparingly soluble MgQ2 complex, it was found to decrease owing to inhibition effect of the complex. Scanning electrochemical microscopic analysis showed a decrease in corrosion currents and enhanced resistance to pitting corrosion was observed for WE43 samples in the presence of HQ after an exposure of 48 h. With time, the MgQ2 thus generated formed a protective layer on the Mg alloy surface to prevent further corrosion. The corrosion rate of WE43 samples decreased by ~ 50% in HQ containing medium after a constant exposure of 28 days (from ~ 0.22 mg/cm2 day in no HQ to ~ 0.11 mg/cm2 day in HQ). For the WE43 samples in the presence of HQ, formation of MgO and MgQ2 was detected by x-ray photoelectron spectroscopy and x-ray diffraction. Shallower and smaller pits appeared on the magnesium alloy with HQ in the solution as compared to deeper and larger pits on the samples with no HQ in the solution. The significance of metal-complexing organic agent, hydroxyquinoline, in initial acceleration and subsequent prevention of Mg corrosion via protective MgQ2 complex layer formation is demonstrated.

This article provides a second manifestation of a new tradition by which the editors of Comments on Inorganic Chemistry wish to lead by example, whereby we start publishing original research conten...

The deterioration of metals under the influence of corrosion is a costly problem faced by many industries. Therefore, particle-reinforced composite coatings are being developed in different technological fields with high demands for corrosion resistance. This work studies the effects of nanoplatelet reinforcement on the durability, corrosion resistance, and mechanical properties of copper-nickel coatings. A 90 : 10 Cu-Ni alloy was coelectrodeposited with nanoplatelets of montmorillonite (Mt) embedded into the metallic matrix from electrolytic baths containing 0.05, 0.10, and 0.15% Mt. X-ray diffraction of the coatings indicated no disruption of the crystal structure with addition of the nanoplatelets into the alloy. The mechanical properties of the coatings improved with a 17% increase in hardness and an 85% increase in shear adhesion strength with nanoplatelet incorporation. The measured polarization resistance increased from 11.77 kΩ·cm2 for pure Cu-Ni to 33.28 kΩ·cm2 for the Cu-Ni-0.15% Mt coating after soaking in a simulated seawater environment for 30 days. The incorporation of montmorillonite also stabilized the corrosion potential during the immersion study and increased resistance to corrosion.

The effects of higher concentrations (5 and 10%) of an organic modifier, butanol, added to an aqueous electroplating solution for nickel deposition have been studied. Nickel coatings were deposited on steel substrates from a modified all-sulfate bath with 5 and 10% additions of butanol under acidic conditions, while a modified pulse potential was applied. X-ray diffraction of the resulting nickel coatings showed a preferred (220) orientation for the crystal structure. The coatings were nanocrystalline with particle sizes between 16 and 35 nm as calculated from Williamson–Hall analysis. No cracking of the films was observed in the scanning electron microscopy images, even as the percentage of butanol increased, as typically is observed in other aqueous-organic baths. Corrosion resistance of the nickel coatings in a 3.5% sodium chloride solution was best for coatings deposited from plating solutions containing 5 and 10% butanol. E corr was shifted from −0.405 V for the nickel coating from the additive-free bath to −0.234 V for the nickel coating from the 5% butanol solution. EIS results indicated a twofold improvement in charge transfer resistance for nickel coatings deposited when butanol was used in the plating bath. The advantages of using higher percentages of organic modifiers like butanol to enable the use of non-electroactive particles for production of composite coatings are discussed.

Experimental water-to-methyl isobutyl ketone partition coefficients have been determined for 27 different organic solutes based on gas chromatographic measurements. Updated Abraham model correlations were determined for describing solute transfer into methyl isobutyl ketone by combining the measured partition coefficient data determined in the present study with published experimental values taken from chemical and engineering literature. One hundred nineteen compounds were used in determining the revised Abraham model correlations. After calculations, the revised mathematical correlations were found to match the experimental data to within an overall average standard deviation of 0.21 log units.

Matrix-assisted laser desorption/ionization mass spectrometry (MALDI-MS) has been coupled to direct analyte-probed nanoextraction (DAPNe) through use of nanomanipulation for the analysis of ink chemistry on documents. DAPNe is first used to extract ink from the document and then deposits the sample on the MALDI plate. Through this method, cutting the document for MALDI-MS analysis is avoided. DAPNe extracts ink from documents with minimal to no visible destruction. Specific dyes and binding agents in the extracted ink are monitored with mass spectrometry. Different matrices, 1, 5-diaminonapthalene (DAN), 2, 5-dihydroxybenzoic acid (DHB), and silver nanoparticles, were tested to compare intensity enhancement of the mass spectra signals. The advantages of using MALDI-MS coupled to DAPNe are shown by characterizing Crystal Violet, Basic Yellow 2, Rhodamine B, and polyethylene glycol from red and blue pens, black pen, and a black inkjet printer cartridge.

The hydrophobic and corrosion resistive film of cross-linked poly(hexafluoroisopropyl methacrylate) was successfully prepared by a simple photopolymerization method. The starting materials were a monomer of 1,1,1,3,3,3-hexafluoroisopropyl methacrylate, a photoinitiator of hydroxycyclohexyl phenyl ketone, and a cross-linker of poly (ethyleneglycol diacrylate). A very simple coating technique of drop-casting was used to deposit the fluorinated polymer onto an aluminum alloy substrate (AA 3003). The polymer coating was stable over a 60-day period when exposed to an aqueous solution of 3.5% NaCl as measured by open circuit potential technique. The fluorinated polymer coating had high corrosion protection when measured by potentiodynamic polarization with a reduction of 90% in the corrosion current density for the polymer-coated aluminum alloy over the bare substrate. The corrosion current density decreased to 0.065 μA/cm2 for the aluminum alloy coated with the polymer film compared to 0.708 μA/cm2 for uncoated aluminum alloy. Fourier-transform infrared spectroscopy was used to monitor the polymerization process. The dynamic contact angle technique was used to measure the hydrophobicity for the fluorinated polymer coating and increased from 65° to 100° for the uncoated and coated substrate, respectively. Contact angle measurements before and after treatment with strong acid were carried out to confirm the chemical resistance of the polymer coating. The thermal stability of the fluorinated polymer was measured using thermogravimetric analysis showing thermal stability up to 200 °C.

Metal-organo-ceramic nanocomposite coatings were prepared via electrodeposition as corrosion protection coatings. A diazonium synthesis procedure was used to successfully graft ferrocene onto CeO2 nanoparticles. The modified nanoparticles were characterized by fourier-transform infrared spectroscopy (FTIR), solid-state NMR, electrochemical techniques, atomic absorption spectroscopy (AAS), and thermogravimetric analysis (TGA). A mixture of the grafted nanoparticles and nickel ions was added to an electrolyte plating solution for deposition of a Ni Fc-CeO2 nanocomposite coating onto steel substrate as a corrosion protection layer. The effect of CeO2 and ferrocene-CeO2 nanoparticles on the formation, morphology, composition, and corrosion resistance of the nickel coating was investigated by potentiodynamic polarization, powder x-ray diffraction (XRD), scanning electrochemical microscopy (SEM), inductively coupled plasma mass spectrometry (ICP-MS), and electrochemical impedance spectroscopy (EIS).

Silver nanoparticles were synthesized with clay mineral (montmorillonite)/PVP (polyvinyl pyrrolidone) suspensions using an electrochemical approach. The polymer and exfoliated clay mineral solution protect and prevent aggregation of the silver nanoparticles. The clay mineral component is environmentally friendly and low cost. Unlike other studies, the clay platelets are exfoliated (sheared apart to individual platelets) to expose a much larger surface area and function as supporting material and stabilizer. A prime advantage of this novel approach is that the polymer and layered silicates protected the silver nanoclusters from agglomerating, effectively immobilizing and enhancing contact with the cathode for reduction. An electrochemical approach for nanoparticle synthesis has several advantages; including control and tuning of the experimental parameters, easy set-up, and short synthesis times. Morphology of the silver nanoparticles depended on current density of the electrochemical synthesis. Transmission electron microscopy showed small spherical silver nanoparticles formed at current densities below 1.25 mA/cm2 and silver dendritic formation at current densities greater than 2.5 mA/cm2. Size distribution of nanocomposites in solution measured by dynamic light scattering was 27 nm for the silver nanoparticles. X-ray diffraction was used to measure the crystallite size of the dried powders, which ranged between 10 and 60 nm depending on the experimental parameters. Nanocomposite coatings were also formed on graphite foil electrodes. Dense uniform films of spherical silver nanoparticles were produced at low current densities ( 2.0 mA/cm2).

To improve the biocompatibility of medical implants, a chemical composition of bone-like material (e.g., hydroxyapatite) can be deposited on the surface of various substrates. When hydroxyapatite is deposited on surfaces of orthopedic implants, several parameters must be addressed including the need of rapid bone ingrowth, high mechanical stability, corrosion resistance, biocompatibility, and osseointegration induction. However, the deposition process can fail due to poor adhesion of the hydroxyapatite coating to the metallic substrate. Increasing adhesion by enhancing chemical bonding and minimizing biocoating degradation can be achieved through surface activation and pretreatment techniques. Surface activation can increase the adhesion of the biocoating to implants, providing protection in the biological environment and restricting the leaching of metal ions in vivo. This review covers the main surface activation and pretreatment techniques for substrates such as titanium and its alloys, stainless steel, magnesium alloys, and CoCrMo alloys. Alkaline, acidic, and anodizing techniques and their effects on bioapatite deposition are discussed for each of the substrates. Other chemical treatment and combination techniques are covered when used for certain materials. For titanium, the surface pretreatments improve the thickness of the TiO2 passive layer, improving adhesion and bonding of the hydroxyapatite coating. To reduce corrosion and wear rates on the surface of stainless steel, different surface modifications enhance the bonding between the bioapatite coatings and the substrate. The use of surface modifications also improves the morphology of hydroxyapatite coatings on magnesium surfaces and limits the concentration of magnesium ions released into the body. Surface treatment of CoCrMo alloys also decreased the concentration of harmful ions released in vivo. The literature covered in this review is for pretreated surfaces which then undergo deposition of hydroxyapatite using electrodeposition or other wet deposition techniques and mainly limited to the years 2000-2019.

Cerium oxide/montmorillonite nanocomposite films were synthesized electrochemically from solutions containing 0.5 to 50% Na-montmorillonite. The nanocomposites were characterized by X-ray diffraction, scanning electron microscopy, Fourier transform infrared spectroscopy, and Raman spectroscopy. Nanocomposite films synthesized from montmorillonite concentrations lower than 10% were continuous, uniform, and dense. X-ray diffraction confirmed that the nanocomposite films retain the face-centered cubic structure of cerium oxide while incorporating exfoliated platelets of the montmorillonite into the matrix. In addition, calculations from XRD data showed particle sizes ranging from 4.50 to 6.50 nm for the nanocomposite coatings. Raman and FTIR spectroscopy had peaks present for cerium oxide and the layered silicates in the coatings. Cross-sectional scanning electron microscopy and energy-dispersive X-ray spectroscopy confirmed the presence of montmorillonite throughout the cerium oxide matrix.

Forensic DNA samples may include the presence of PCR inhibitors, even after extraction and purification. Studies have demonstrated that metal ions, co-purified at specific concentrations, inhibit DNA amplifications. Metal ions are endogenous to sample types, such as bone, and can be introduced from environmental sources. In order to examine the effect of metal ions as PCR inhibitors during quantitative real-time PCR, 2800 M DNA was treated with 0.0025-18.750 mM concentrations of aluminum, calcium, copper, iron, nickel, and lead. DNA samples, both untreated and metal-treated, were quantified using the Quantifiler(®) Human DNA Quantification Kit. Quantification cycle (Cq) values for the Quantifiler(®) Human DNA and internal PCR control (IPC) assays were measured and the estimated concentrations of human DNA were obtained. Comparisons were conducted between metal-treated and control DNA samples to determine the accuracy of the quantification estimates and to test the efficacy of the IPC inhibition detection. This kit is most resistant to the presence of calcium as compared to all metals tested; the maximum concentration tested does not affect the amplification of the IPC or quantification of the sample. This kit is most sensitive to the presence of aluminum; concentrations greater than 0.0750 mM negatively affected the quantification, although the IPC assay accurately assessed the presence of PCR inhibition. The Quantifiler(®) Human DNA Quantification Kit accurately quantifies human DNA in the presence of 0.5000 mM copper, iron, nickel, and lead; however, the IPC does not indicate the presence of PCR inhibition at this concentration of these metals. Unexpectedly, estimates of DNA quantity in samples treated with 18.750 mM copper yielded values in excess of the actual concentration of DNA in the samples; fluorescence spectroscopy experiments indicated this increase was not a direct interaction between the copper metal and 6-FAM dye used to label the probe that targets human DNA in the Quantifiler(®) kit. Evidence of inhibition was observed for the human-specific assay at a lower metal concentration than detected by the IPC, for all metals examined except calcium. These results strongly suggest that determination of a "true negative" sample should not be based solely on the failure of the IPC to indicate the presence of a PCR inhibitor and indicate that amplification of all samples should be attempted, regardless of the quantification results.

The crystallization kinetics of magnesium hydroxide in low concentration solutions has been studied using an electrical conductivity method. Using various experimental relationships, several kinetic factors could be determined during the nucleation and growth process. From measurements of ion concentrations at various temperatures, the induction period of nucleation could be determined. As concentration and temperature increase, the crystallization rate increases affecting the nucleation and crystal growth of Mg(OH) 2 . The crystal-solution interfacial surface tension was also calculated and shown to be affected by the magnesium anion source. The results show that a uniform particle size distribution of nuclei is formed during the initial homogeneous nucleation process and the nucleation and crystal growth rates can be represented by a first order reaction equation. Through the study of crystallization kinetics, a control strategy is proposed to synthesize a uniform particle size distribution of magnesium hydroxide.

Zinc-nickel γ-phase alloy coatings were electrochemically deposited from a borate electrolytic bath on stainless steel substrates as protective coatings for corrosive environments. Alkaline conditions were used with a working pH range of 9.3–9.5 resulting in uniform deposits and corrosion protection. Strongly adhering deposits were obtained with smooth and even overall coverage of the substrate. The effect of borate addition was examined in relation to zinc, nickel and zinc-nickel alloy deposition. The presence of borate did not affect the anodic stripping potential of zinc in solution but did result in an anodic shift in the stripping potential of nickel with increasing borate concentration. Borate was adsorbed onto the electrode surface and shifted the onset of hydrogen evolution towards more cathodic potentials as borate concentration was increased. X-ray diffraction and atomic absorption spectroscopy confirmed the presence of the γ-phase alloy with a nickel content range of 8–15%. Pulse potential and direct potential processes were examined as deposition methods. The pulse potential method resulted in smaller grain sizes and uniform coatings as confirmed in scanning electron microscopy. The overall corrosion potential for the zinc-nickel γ-phase coatings was improved as compared to the pure nickel and zinc coatings.

Nickel–molybdenum–montmorillonite (Ni–Mo–MMT) nanocomposite coatings were prepared by electrodeposition from an alkaline citrate bath containing different concentrations of exfoliated montmorillonite. X-ray diffraction results revealed that the embedding of silicate platelets modified the texture of the Ni–Mo matrix and increased the grain size. Nanoindentation measurements showed increasing microhardness and Young's modulus for the nanocomposite coatings deposited from 1.0 g/L solutions of silicate platelets compared to pure Ni–Mo films. The potentiodynamic polarization and electrochemical impedance measurements showed that the Ni–Mo–MMT nanocomposite layers have higher corrosion resistance in 3.5% NaCl compared to pure Ni–Mo. SEM and AFM micrographs showed a slight increase in the particle size and the surface roughness of the electrodeposited film, respectively as a result of incorporation of MMT particles into the Ni–Mo alloy matrix.

A method for the extraction and analysis of ink samples was developed using microscopy with direct analyte probe nanoextraction coupled to nanospray ionization mass spectrometry (DAPNe-NSI-MS) for localized chemical analysis of document inks. Nanomanipulation can be effectively coupled to nanospray ionization mass spectrometry providing picomolar sensitivity, and the capability to analyze ultra-trace amounts of material and reduce the required sample volume to as low as 300 nL. This new and innovative technique does not leave destructive footprints on the surface of a document. To demonstrate the breadth of this technique, analysis of inks from various eras were tested, iron gall ink and modern inks, as well as the capability to detect the oxidative products of polyethylene glycol (PEG), a common binding agent. The experimental results showed that DAPNe-NSI-MS was able to chelate iron(II) and manganese(II) ions of iron gall ink and organic components of modern and carbon-based inks. Regardless of whether the ink composition is modern or ancient, organic or inorganic, this new instrumental approach is able to identify and characterize the ingredients by modifying the extraction solvent, illustrating the potential diversity of the DAPNe technique.

A stable sensor for the determination of gallic acid (GA) and caffeic acid (CA) was fabricated by electrodeposition of Zn-Al-NO3 layered double hydroxide film on a glassy carbon electrode (LDHf/GCE). A sensitive electrochemical method was achieved for the determination of GA and CA in a phosphate buffer solution (pH 3). The differential pulse voltammetry response of the LDHf/GCE to GA has a linear concentration range from 4 µM to 600 µM with a correlation coefficient of 0.9985 and the calculated detection limit of 1.6 µM at a signal-to-noise ratio of 3. The differential pulse voltammetry response of the LDHf/GCE to CA has a linear concentration range from 7 µM to 180 µM with a correlation coefficient of 0.9969 and the calculated detection limit of 2.6 µM at a signal-to-noise ratio of 3. The constructed sensor was applied to the determination of GA in commercial green tea samples.

Pure nickel and nickel-montmorillonite (Ni-MMT) composite coatings were produced using pulse current electrodeposition from Watts' type solution. Experimental results show that the codeposition of MMT particles into the Ni matrix improves the microhardness of the coatings and modifies the [100] texture of pure Ni deposits to a mixed crystal orientation through [100] and [211] axes. Ni-MMT composite coatings show improved corrosion resistance in simulated seawater as compared to pure Ni as revealed from electrochemical polarization and impedance measurements. SEM and AFM micrographs indicate a reduction in the Ni crystallite grain size and increase in the surface roughness of the film as a result of embedding of MMT particles in the Ni matrix. NPRP Grant 4-306-2-111 from the Qatar National Research Fund (a Member of The Qatar Foundation). Scopus

Nickel nanopowders were synthesized by a chemical reduction of nickel ions with hydrazine hydrate at pH ~12.5. Sonication of the solutions created a temperature of 54–65°C to activate the reduction reaction of nickel nanoparticles. The solution pH affected the composition of the resulting nanoparticles. Nickel hydroxide nanoparticles were formed from an alkaline solution (pH~10) of nickel-hydrazine complexed by dropwise titration. X-ray diffraction of the powder and the analysis of the resulting Williamson-Hall plots revealed that the particle size of the powders ranged from 12 to 14 nm. Addition of polyvinylpyrrolidone into the synthesis decreased the nickel nanoparticle size to approximately 7 nm. Dynamic light scattering and scanning electron microscopy confirmed that the particles were in the nanometer range. The structure of the synthesized nickel and nickel hydroxide nanoparticles was identified by X-ray diffraction and Fourier transform infrared spectroscopy.

The drug release rate was studied for an anti-inflammatory drug, ibuprofen, in a modified carrier polymer matrix. Nanohybrids were synthesized of layered double hydroxide functionalized with ibuprofen. The ibuprofen was tethered with the layered double hydroxide and blended into the polymer, Poly l lactic acid (PLLA). Effective weight percentages of 3 and 5% of the nanohybrids were used in the polymer producing nanocomposite films. Corresponding films of 1.2 and 2 wt.% of pure ibuprofen were used in the polymer. The cumulative drug release rate of the nanocomposite films increased from ∼10% to 60%. The mechanism for release changed from diffusion control (stage 1) to a mix diffusion/ion-exchange control (stage 2) for the nanocomposite films. There was an improvement of elastic modulus for the nanocomposite films. These results indicated that nanocomposite films showed a significant improvement over the non-nanocomposite films.

Zinc-nickel alloys with 8-15% nickel were deposited onto stainless steel for corrosion protection. Alkaline deposition conditions were utilized given that alkaline systems have been found to offer superior substrate coverage which results in better corrosion protection of the metal substrate (stainless steel) compared to acid bath depositions. This method utilizes ammonium hydroxide as the base source with a working pH range of 9-9.5. Sodium acetate was used as the complexing ligand as it was found to stabilize the metal ions in the electrolytic solution. Strongly adhering, quality deposits were obtained with electrodeposition at room temperature. Bath compositions and applied potential had an effect on morphology of the films as seen in scanning electron microscopy. Upon examination by x-ray diffraction and atomic absorption spectroscopy, all deposits were confirmed as γ phase zinc-nickel alloys with a nickel content of 8-15%. The corrosion potential for the γ-phase coatings was improved over the pure zinc coatings.

A simple method is proposed for the electrodeposition of multilayers using a modified closed flow injection system. The apparatus incorporates flowing streams of electrolyte through a closed atmosphere flow cell for deposition of multilayers. Computer and software control is used to alternate the flow of electrolyte and control the alternating current or potential of the electrochemical cell. Electrodeposition of metallic multilayers of nickel/iron, iron/copper, cobalt/copper, and nickel/copper were used to test the instrument design. X-ray diffraction was used to verify the composition and orientation of the films and scanning electron microscopy was used to examine the morphology of the deposited films. Advantages are discussed for using this type of instrumental setup for multilayer fabrication.

Hydroxyapatite coatings on stainless steel substrates were prepared by a simple spincasting technique. Nanosized hydroxyapatite powders were prepared by precipitating in an electrolytic suspension, and then added to a polylactic acid solution for spincasting. The polylactic acid gave enhanced protection from corrosion and inhibited decomposition of the hydroxyapatite coating during the sintering process in air, a significant advantage over other solution processing techniques. Characterization of the phase composition and morphology of the fabricated films on stainless steel was accomplished by X-ray diffraction, scanning electron microscopy, energy dispersive X-ray spectroscopy, and Fourier transform infrared spectroscopy.

Nanocomposite powders of montmorillonite and cerium oxide are synthesized using an electrochemical technique. X-ray diffraction of the nanocomposites shows a random orientation of the powders with particle sizes as small as 4–6 nm. The montmorillonite percentage in the nanocomposite is also shown to affect sintering rates and particle size growth as shown by X-ray diffraction. Fourier transmission infrared measurements confirm the presence of individual platelets of the montmorillonite within the nanocomposite matrix. Nanocomposites containing 1% of the montmorillonite in the matrix increase crystallization, while higher percentages of montmorillonite inhibit particle growth during sintering.

This book chapter discusses the electrochemical synthesis of lanthanum, cerium, and praseodymium oxides.

Laser ablation has been applied to redacted documents, where the text has been concealed by other ink. This technique strips the redacting ink revealing the text that was once redacted. Once removed, a nanomanipulation technique is used to extract the ink of the underlying text where mass spectrometry is then implemented to analyze its ink chemistry. In order to facilitate microscopy with direct analyte-probed nanoextraction coupled to nanospray ionization mass spectrometry (DAPNe-NSI-MS), laser ablation must be executed prior to ink extraction. Laser ablation has a nondestructive approach of stripping the ink used to redact the document. Not only does this reveal the text, it clears an area for DAPNe to directly extract ink, in miniscule amounts, from the document without inducing destruction. The redacting ink was concluded to affect the aging process of the concealed handwritten ink more than the printed text. The redacted handwritten sample obtained higher relative peak area (%) values than the control samples (text that was not redacted) and the control for the printed text produced higher amounts of low molecular weight products than the sample. Implementing laser ablation on these samples could also affect the chemical properties of the underlying ink due to the additional UV radiation and plasma heating. Results indicate by using laser ablation to remove the redacting ink, the relative peak area of the underlying ink deviates by 1.25%. The thermal degradation of binding agents such as polymethylene, polyethylene glycol, and diethylene glycol was monitored by calculating the relative peak area for five days which, in turn, tracks the oxidation process. The relative peak area values were also used to determine the chemical kinetics of polyethylene glycol, where degradation and polymerization occur.

Cerium oxide/montmorillonite layered silicate powder nanocomposites were synthesized electrochemically. The produced nanocomposites were characterized by powder X-ray diffraction, Fourier transform infrared spectroscopy and Raman spectroscopy. X-Ray diffraction shows the nanocomposites retain the face-centered cubic structure of cerium oxide while incorporating delaminated platelets of the layered silicate into the matrix. By a negative shift in the OH stretching band position, infrared spectroscopy measurements indicate the layered silicates are delaminated. Photoluminescence background in the Raman spectra also shows the incorporation of the layered silicates within the cerium oxide matrix. The thermal properties of the nanocomposites were investigated with sintering and differential scanning calorimetry. The results indicate that low concentration of layered silicate mixed into the cerium oxide increases crystal growth rate whereas high concentration retards the increase of crystallite size during the densification process.

While Si-based integrated circuits dominate the microelectronics marketplace, they cannot be fabricated with optical functionality since Si is indirect. Alternative materials have been used in such applications but the ability to integrate an optically active material directly onto a silicon substrate to co-opt the advances in Si technology and processing capabilities is the better solution. Many of the transition metals form silicides that are direct band gap semiconductors and, as such, may be integrated with Si to achieve the desired optical properties. Ion implantation of the transition metal into Si was used to form the desired silicide phase by reaction of the metal with the Si substrate. Depending upon the fluence the resulting implanted layer can consist of a two-phase region in which the silicide phase forms as isolated precipitates randomly oriented within a heavily dislocated Si matrix. Rutherford backscattering/ion channeling spectrometry was used to monitor this process as a function of temperature and time. A unique method for orienting the silicide precipitates to align them crystallographically with the Si substrate and eliminate the ion-induced dislocations that form during the initial implant is discussed. This method involves oxidation of the implanted region to segregate the silicide phase at the oxide interface. Initial results of Os − ions implanted into Si(1 0 0) are presented.

The spontaneous deposition of Pd metal particles on a conductive boron-doped diamond film supported on silicon substrate was achieved by immersing the diamond/silicon in solutions of 100 ppm Pd 2+ with various HF concentrations (0.0049–4.9%). Scanning electron microscopy showed that HF strength affects the deposition morphology (size and density) of Pd particles on polycrystalline diamond surfaces. X-ray photoelectron spectroscopy confirmed the zero valence of Pd particles. X-ray diffraction characterization of Pd particles prepared from 0.0049% HF showed significant lattice strain (| ɛ | ≥ 1.4%) compared to those from [HF] ≥ 0.049%. The unstrained Pd showed similar electrocatalytic behavior as a Pd disk. While a tensile strain along 〈1 1 1〉 and the consequent increase in the Pd interatomic spacing (to ∼2.79 A) could explain the enhanced hydrogen evolution electrocatalytic behavior of Pd metal particles prepared from 0.0049%, the same strained Pd on diamond exhibit no electrocatalytic activity toward HCHO oxidation.

Using surface flow constructed wetlands for long-term phosphorus (P) retention presents a challenge due to the fact that P is stored primarily in the sediments. Subsurface flow wetlands have the potential to greatly increase P retention; however, the substrate needs to have both high hydraulic conductivity and high P sorption capacity. The objective of our study was to assess the P retention capacity of two substrates, masonry sand and lightweight expanded shale. We used sorption/desorption isotherms, flow-through column experiments, and pilot-scale wetlands to quantify P retained from treated municipal wastewater. Langmuir sorption isotherms predicted that the expanded shale has a maximum sorption capacity of 971 mg/kg and the masonry sand 58.8 mg/kg. In column desorption and column flow-through experiments, the masonry sand desorbed P when exposed to dilute P solutions. The expanded shale, however, had very little desorption and phosphorus did not break through the columns during our experiment. In pilot cells, masonry sand retained (mean +/- standard deviation) 45 +/- 62 g P/m2/yr and expanded shale retained 164 +/- 110 g P/m2/yr. We conclude that only the expanded shale would be a suitable substrate for retaining P in a subsurface flow wetland.

Diamondlike carbon (DLC) films were electrodeposited on nickel substrates from a solution of acetylene in liquid ammonia at low temperature and low potential using a three-electrode cell. Raman spectra showed a shoulder D peak at 1365 cm−1and a broad G peak at 1558 cm−1for the films, indicating ansp3andsp2carbon mixture. The presence of a 1230 cm−1peak also indicated some four-fold-coordinated bonds of microcrystalline diamond. Fitting of the peaks in the Raman spectra specified the electrodeposited films were hydrogenated amorphous alloys, a-C:H. X-ray photoelectron spectra also pointed to the films containing a mixture ofsp3andsp2carbon. Fourier transform infrared spectra of the electrodeposited films had C-H stretching vibrations, which is consistent with hydrogenated DLC films.

In this study, the electrochemical deposition of nickel/montmorillonite nanocomposite films was investigated on stainless steel and copper substrates. Deposition variables that were investigated included electrochemical cell orientation, degree of agitation during deposition, and montmorillonite concentration in the electroplating solution. The resulting films were characterized with scanning electron microscopy, X-ray diffraction, and X-ray fluorescence techniques. By a novel electrochemical cell construction, an orderly deposition of nickel/montmorillonite nanocomposite films was ultimately achieved. Scanning electron microscopy images characterized these films with an ordered surface topography of horizontal montmorillonite platelets held in a nickel media. Profile scanning electron microscopy images further showed a heavily striated stack of aligned montmorillonite layered silicate platelets throughout the profile of the nickel/montmorillonite nanocomposite film. Also, X-ray fluorescence verified the ...

Cuprous oxide (Cu2O) nanorod arrays have been prepared via a novel templated electrodeposition process and were characterized for their photocatalytic behavior in nonaqueous photoelectrochemical cells. Zinc oxide (ZnO) nanorod films serve as sacrificial templates for the in situ formation of polymer nanopore membranes on transparent conductive oxide substrates. Nitrocellulose and poly(lactic acid) are effective membrane-forming polymers that exhibit different modes of template formation, with nitrocellulose forming conformal coatings on the ZnO surface while poly(lactic acid) acts as an amorphous pore-filling material. Robust template formation is sensitive to the seeding method used to prepare the precursor ZnO nanorod films. Photoelectrochemical cells prepared from electrodeposited Cu2O films using methyl viologen as a redox shuttle in acetonitrile electrolyte exhibit significant charge recombination that can be partially suppressed by a combination of surface passivation methods. Surface-passivated nanostructured Cu2O films show enhanced photocurrent relative to planar electrodeposited Cu2O films of similar thickness. We have obtained the highest photocurrent ever reported for electrodeposited Cu2O in a nonaqueous photoelectrochemical cell.

Layered silicates as exfoliated montmorillonite are incorporated into nickel films by electrodeposition, enhancing both corrosion resistance and hardness. Films were deposited onto stainless steel from a plating solution adjusted to pH 9 containing nickel sulfate, sodium citrate, and various concentrations of exfoliated montmorillonite. The presence of the incorporated layered silicate was confirmed by scanning electron microscopy and energy-dispersive X-ray spectroscopy. The composite films were also compact and smooth like the pure nickel films deposited under the same conditions as shown by scanning electron microscopy. X-ray diffraction results showed that incorporation of layered silicates into the film do not affect the nickel crystalline fcc structure. The nanocomposite films exhibited improved stability and adhesion. Pure nickel films cracked and peeled from the substrate when immersed in 3.5% NaCl solution within 5 days, while the nanocomposite films remained attached even after 25 days. The corrosion resistance of the nickel nanocomposites was also improved compared to nickel films. Nickel-layered silicate composites showed a 25% increase in Young's modulus and a 20% increase in hardness over pure nickel films. NPRP grant 4-306-2-111 from the Qatar National Research Fund (A Member of The Qatar Foundation). Scopus

The objective of this investigation is to determine the effects of montmorillonite layered silicates on the curing kinetics of an epoxy resin. Differential scanning calorimetry was used to probe the changes in reactivity due to the presence of montmorillonite and due to the diamine hardener. The enthalpy of polymerization was strongly affected at compositions greater than 5% (wt) montmorillonite for epoxy + montmorillonite reactions. On introduction of the hardener, epoxy + amine kinetics dominate the reaction for all compositions except for a montmorillonite concentration of 2.5 wt%. X-ray diffraction was used to determine if the reacted system was exfoliated. The results show a strong montmorillonite composition dependence on the exfoliated state. Transmission electron microscopy of the cured epoxies confirmed a mixed intercalated and exfoliated dispersion at compositions having montmorillonite greater than 2.5 wt%.

Superlattices in the Pb−Tl−O system were electrodeposited at room temperature from aqueous solution. The deposition solution was 0.005 M Tl(I) and 0.100 M Pb(II) in 5 M NaOH. The superlattices grew...

Nanometer-scale layered structures based on thallium(III) oxide were electrodeposited in a beaker at room temperature by pulsing the applied potential during deposition. The conducting metal oxide samples were superlattices, with layers as thin as 6.7 nanometers. The defect chemistry was a function of the applied overpotential: High overpotentials favored oxygen vacancies, whereas low overpotentials favored cation interstitials. The transition from one defect chemistry to another in this nonequilibrium process occurred in the same potential range (100 to 120 millivolts) in which the rate of the back electron transfer reaction became significant. The epitaxial structures have the high carrier density and low electronic dimensionality of high transition temperature superconductors.

Complete Auger electron angular distributions have been measured from a monolayer of Ag atoms (355 eV) in the presence and absence of an ordered monoatomic overlayer of iodine atoms. In the presence of the iodine overlayer, the Auger emission from the Ag monolayer is anisotropically attenuated to form a distinct hexagonal intensity distribution, and the Auger intensity does not increase relative to that observed for the bare Ag monolayer along any direction of emission. The extent of attenuation is in good agreement with gas-phase cross section measurements for Xe, which also indicate that inelastic scattering predominates over elastic scattering in this energy range

The relationship between the intrinsic structure and transport properties of lithium ions in LiFePO4 cathode materials is investigated by molecular dynamics simulations.

We report angular distributions of Auger electrons (507 and 518 eV) emitted from three distinct monolayer structures of iodine atoms on single-crystal platinum: Pt(111)(√3×√3)R30 o -I, Pt(111)(√7×√7)R19.1 o -I,and Pt(111) (3×3)-I. Each of these monolayers has been characterized by means of LEED, STM, AES, XPS, TDMS, and electrochemistry. Accordingly, these monolayers provide an opportunity to explore the nature of Auger electron angular distributions for surface atomic layers of known structure and to correlate the results with what is already known regarding these structures