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Abstract: Programmable DNA nanostructures are excellent modules for preparing artificial cells with complex structures and functions. As a biocompatible building material, DNA nanostructures can mimic cell components on the nanoscale and serve as artificial cell structural units, such as membrane proteins, cytoskeleton, organelles, or even protocell models. The incorporation of DNA strand displacement reactions and functional nucleic acids endowed artificial cells with the capability of mimicking dynamic biological processes, such as molecular transportation, and signal transduction pathways. Herein, we focus on the recent progress in the construction of artificial cells utilizing DNA nanotechnology. DNA nanostructures used as cellular structural and functional units are summarized, and the applications of DNA-based artificial cells as biosensors or smart drug carriers are highlighted. We also discuss the perspective of DNA-based artificial cells, including the challenges in designing smart artificial cells with controllable behavior and constructing artificial cells with the cell-like function, as well as the opportunities of their potential applications.

Examples on the real-world field application of Raman spectroscopy with systematic analysis of the intensity variation of D and G bands corresponding to the change of excitation laser energy to characterize and compare coke species from various industrial processes are presented. The findings indicate the different degree of sp2 and sp3 hybridized bonding structures of amorphous carbon collected from different industrial processes as well as heavy carbonaceous deposits generated by industrial catalysts. This spectroscopic methodology is practical and highly beneficial in identifying coke formation mechanisms in industrial processes, as well as supporting design strategies to abate the undesired coke formation on industrial catalysts.

Biomolecular condensates comprised of specific proteins and nucleic acids are now recognized as one of the key organizing mechanisms in eukaryotic cells. However, the specific roles played by the nucleic acid secondary structure and sequence in biomolecular phase separation are still not clear. Here, utilizing giant membrane vesicles (GMVs) as a protocell model, we found that single-stranded DNA (ssDNA) with a parallel G-quadruplex structure could functionally cooperate with a G-quadruplex-binding protein to form speckle-like puncta inside the GMVs. The clustering behavior is dependent on the structural diversity of G-quadruplexes, and the reversible clustering behavior implicated a new pathway in dynamically regulating the formation of biomolecular condensates. This finding represents a potential link between G-quadruplex-binding proteins and the resulting G-quadruplex-mediated biomolecular phase separation, which would gain insight into a wide range of biological processes associated with nucleic acid-modulated phase separation inside living cells.

Due to its excellent programmability and biocompatibility, DNA molecule has unique advantages in cell surface engineering. Recent progresses provide a reliable and feasible way to engineer cell surfaces with diverse DNA molecules and DNA nanostructures. The abundant form of DNA nanostructures has greatly expanded the toolbox of DNA-based cell surface engineering and gave rise to a variety of novel and fascinating applications. In this review, we summarize recent advances in DNA-based cell surface engineering and its biological applications. We first introduce some widely used methods of immobilizing DNA molecules on cell surfaces and their application features. Then we discuss the approaches of employing DNA nanostructures and dynamic DNA nanotechnology as elements for creating functional cell surfaces. Finally, we review the extensive biological applications of DNA-based cell surface engineering and discuss the challenges and prospects of DNA-based cell surface engineering.

Engineering cell-derived nanovesicles with active-targeting ligands is an important strategy to enhance the targeting efficiency. However, the enhanced binding capability to targeting cells also leads to the binding with nontarget cells that share the same biomarkers. DNA-based logic gate is a kind of molecular system that responds to chemical inputs by generating output signals, and the relationship between the input and the output is based on a certain logic. Thus, the DNA-based logic gate could provide a new approach to improve the delivery efficiency of the nanovesicle. In this work, we developed a DNA logic-gated module that coupled two tumor cell-targeting factors (e.g., low pH and a tumor cell biomarker) in a Boolean manner. Immobilization of this module on the surface of the nanovesicle enables the nanovesicle to sense tumor cell-targeting factors and regard these cues as inputs AND logic gate. With the guide of DNA-based logic gate, gold carbon dots (GCDs) encapsulated within nanovesicles were delivered into target cells, and then the intracellular redox status variation was reflected by fluorescence change of GCDs. Overall, we developed DNA logic-gated nanovesicles that contract different targeting factors into a unique tag for target cells. This facile functionalization strategy can pave the way for constructing smart nanovesicles and would broaden their application in the field of precision medicine and personalized treatment.

Numerous Rh catalysts were evaluated for N2O decomposition for automotive applications. Some Rh-containing spinel materials exhibit excellent fresh activities in the absence of H2O but become inactive after hydrothermal aging or when tested in a wet feed. Rh catalysts supported on zeolites can be very active in a dry feed even after aging but are extremely sensitive to H2O. Rh/CeO2 is an exceptional catalyst for this reaction in the presence of both H2O and O2. Hydrothermal aging (750 °C/20 h) significantly increases its activity. A similar activity enhancement was found by calcining the support before Rh impregnation. XPS results show a surface enrichment of Rh species on the aged Rh/CeO2 catalyst relative to the fresh catalyst. Aberration corrected STEM images reveal that Rh is buried in the bulk on the fresh catalyst and pulled out onto the surface of the support after thermal treatments. All catalysts are inhibited by H2O with the zeolite-based Rh catalysts being the worst. The aged Rh/CeO2 catalyst is less sensitive to H2O relative to others. DRIFTS data show that H2O sensitivity is related to catalyst hydrophilicity; a high coverage of OH groups on a catalyst reduces its N2O decomposition activity. H2-TPR results show that a Rh/CeO2 catalyst can be readily reduced at

Cerium oxide (ceria, CeO2) is a technologically important material for energy conversion applications. Its activities strongly depend on redox states and oxygen vacancy concentration. Understanding the functionality of chemical active species and behavior of oxygen vacancy during operation, especially in high-temperature solid-state electrochemical cells, is the key to advance future material design. Herein, the structure evolution of ceria is spatially resolved using bulk-sensitive operando X-ray diffraction and spectroscopy techniques. During water electrolysis, ceria undergoes reduction, and its oxygen non-stoichiometry shows a dependence on the electrochemical current. Cerium local bonding environments vary concurrently to accommodate oxygen vacancy formation, resulting in changes in Ce-O coordination number and Ce3+/Ce4+ redox couple. When reduced enough, a crystallographic phase transition occurs from α to an α' phase with more oxygen vacancies. Nevertheless, the transition behavior is intriguingly different from the one predicted in the standard phase diagram of ceria. This paper demonstrates a feasible means to control oxygen non-stoichiometry in ceria via electrochemical potential. It also sheds light on the mechanism of phase transitions induced by electrochemical potential. For electrochemical systems, effects from a large-scale electrical environment should be taken into consideration, besides effective oxygen partial pressure and temperature.

Photocatalytic hydrogen production as a technology to solve energy and environmental problems exhibits great prospect and the exploration of new photocatalytic materials is crucial. In this research, the ternary composite catalyst of MoS

The need to mitigate the environmental footprints of refineries in a sustainable and economical way is widely accepted, yet there appears to be a lack of a unilateral pragmatic approach towards CO oxidation to CO2 among the refining community. In this work we share CO promoter design strategies that can afford a tangible and immediate CO conversion efficiency increase without a need for additional precious metal loading. The key focus is on the support material architecture that is essential to boost the CO conversion and reduce the NOx generation in the FCC unit. It was demonstrated that the suppression of Pt sintering as well as the enhancement of the oxygen mobility on the catalyst surface can afford an ~40% lower cost of Pt and ~20% lower usage rate compared to current industry-standard designs.

The determination of reaction mechanism for electrocatalytic CO2 reduction by experiments is still out of reach on copper catalyst, which limits its advance towards industrial implementation. Here, the Cu/CeO2 catalyst as paradigm was studied to validate the reaction intermediates and pathway. The Cu/CeO2 catalysts with different morphologies were synthesized, and it is discovered that the nanorod Cu/CeO2 catalyst exhibits high selectivity for CO2-to-CH4 with the highest turnover frequency for CH4 production among the samples. Detailed study indicates that the nanorod Cu/CeO2 possesses the largest electrochemically active surface area, higher proportion of O-vacancy sites, and better capability of CO2 adsorption and activation. The chemical nature above together contributes to its high activity. Theoretical calculations reveal that the doping of Cu into CeO2 can significantly lower the reaction energy barrier of *CO2 →*COOH and change the reaction pathway from *CHOH →*CH2OH to *CHOH →*CH, effectively improving the catalytic performance for CO2 electroreduction.

In this contribution, we present an industrial example on how tailored operando spectroscopic methodologies provide the insights needed for the development of new catalytic technologies and support their global utilization. We describe the use of operando spectroscopic methods to investigate how the CO oxidation performance of catalysts is impacted by NOx, H2, temperature, and moisture, as well as the catalyst support. This operando spectroscopic analysis provides mechanistic insights into the current diesel oxidation catalyst (DOC) system and shines light on the material and process development efforts on future DOC catalysts for low-temperature emission control to meet the new regulations. This investigation has shown that at cold-start temperatures, the nitrate growth can occupy the precious metal–alumina support interfacial sites that are critical for O2 dissociation and/or oxygen transfer and hinder CO conversion. Introduction of hydrogen on the catalyst surface can inhibit the nitrate growth, which in turn keeps these critical interfacial sites open.

Fluid Catalytic Cracking (FCC) has maintained its crucial role in refining decades after its initial introduction owing to the flexibility it has as a process as well as the developments in its key enabler, the FCC catalyst. Boron-based technology (BBT) for passivation of contaminant metals in FCC catalysts represents one such development. In this contribution we describe Fourier Transform Infrared Spectroscopy (FTIR) characterization of boron-containing catalysts to identify the phase and structural information of boron. We demonstrate that FTIR can serve as a sensitive method to differentiate boron trioxide and borate structures with a detection limit at the 1000 ppm level. The FTIR analysis validates that the boron in the FCC catalysts studied are in the form of small borate units and confirms that the final FCC catalyst product contains no detectable isolated boron trioxide phase. Since boron trioxide is regulated in some parts of the world, this novel FTIR methodology can be highly beneficial for further FCC catalyst development and its industrial application at refineries around the world. This new method can also be applied on systems beyond catalysts, since the characterization of boron-containing materials is needed for a wide range of other applications in the fields of glass, ceramics, semiconductors, agriculture, and pharmaceuticals.

Cell-derived vesicles (CDVs) have been investigated as an alternative to exosomes. Here, we generated CDVs from Prokineticin receptor 1 (PROKR1) overexpressing HEK293T cells using micro-extrusion. More than 60 billion PROKR1-enriched CDV (PROKR1Tg CDVs) particles with canonical exosome properties were recovered from 107 cells. With 25 μg/mL of PROKR1Tg CDVs, we observed delivery of PROKR1, significant reduction of apoptosis, and myotube formation in C2C12Prokr1−/− myoblasts that have lost their myogenic potential but underwent apoptosis following myogenic commitment. Expression levels of early and late myogenic marker genes and glucose uptake capacity were restored to equivalent levels with wild-type control. Furthermore, PROKR1Tg CDVs were accumulated in soleus muscle comparable to the liver without significant differences. Therefore, CDVs obtained from genetically engineered cells appear to be an effective method of PROKR1 protein delivery and offer promise as an alternative therapy for muscular dystrophy.

The purpose of the study was to design a novel octa-arginine (R8) modified lipid emulsion (LE) system for the ocular delivery of the lipophilic drug disulfiram (DSF). The influence of the particle size of the lipid emulsions and the presence of R8 on corneal permeation was studied. DSF-loaded lipid emulsions with different particle sizes (DSF-LE1, DSF-LE2, DSF-LE3) and DSF-loaded lipid emulsions modified with R8 (DSF-LE1-R8 and DSF-LE2-R8) were prepared. The Zeta potential of the lipid emulsions was changed from negative to a positive value after modification of R8. The mucoadhesion of different preparations was investigated, and DSF-LE1-R8 was found to produce the strongest mucoadhesion. The in vitro corneal penetration study and in vivo ocular distribution study showed that the R8 modified lipid emulsion (DSF-LE1-R8) with a nano particle size, exhibited the highest permeability and the largest amount of DDC distributed in ocular issues. Coumarin-6 labelled LE1-R8 displayed more homogeneous fluorescence with the deeper penetration into the cornea compared with other preparations at various times. Confocal laser scanning microscopy showed that, in addition to paracellular routes, LE-R8 could also transport across the corneal epithelium by transcellular routes as a result of increased uptake due to the R8 modification. Furthermore, the anti-cataract effect was evaluated and it was found that DSF-LE1-R8 exhibited a marked anti-cataract effect. Therefore, the lipid emulsions with nano-sized particles and modification of R8 were proposed as a potential ocular delivery system to improve the corneal penetration and ocular delivery of DSF.

Nickel, a common contaminant in crude oil, deposits on Fluid Catalytic Cracking (FCC) catalysts and induces unwanted dehydrogenation reactions. These lead to an increase in hydrogen and coke which inhibits the FCC unit from reaching its optimal operation. Modern catalyst technologies can include nickel passivation strategies to minimize such detrimental effects, and, over time, aging of the nickel on catalyst also diminishes its deleterious activity to some extent; however, reactivation of nickel due to chemical interactions within the FCC unit can retard aging and further penalize the catalytic performance. For the first time, we attempt to demonstrate and characterize the physiochemical and catalytic effects of chloride ions on contaminant nickel in the FCC environment. Equilibrium catalyst (Ecat) samples obtained from industrial FCC units are exposed to chloride ions, and changes in physicochemical characteristics, catalytic selectivity, and the reducibility of nickel are analyzed. These changes indicate the reactivation of nickel and an increase in unwanted dehydrogenation reactions following exposure to chloride ions. Spectroscopic analyses show that the interaction with chloride ions alters the electronic environment of nickel, which makes it easier to be reduced in the FCC riser, and Advanced Cracking Evaluation (ACE) studies show equilibrium catalysts that were exposed to chloride ions gave higher coke and H2 yields. These results bridge the gap between existing literature and the FCC environment by demonstrating that chloride ions can interact and reactivate nickel contaminant on FCC catalysts.

Fluid Catalytic Cracking (FCC) is a crucial refining process supplying majority of gasoline used worldwide as well as other key building blocks for chemical industry. Nickel, a contaminant in crude oil, deposits on FCC catalysts and induces unwanted dehydrogenation reactions, inhibiting the FCC unit from reaching optimal operation. We describe a new spectroscopic methodology to characterize the impact of boron interaction on nickel in FCC catalysts through a trend analysis of CO DRIFTS for FCC catalysts from boron-based technology. Results obtained by the new method provide direct spectroscopic evidence of boron effect on nickel passivation by decreasing reducibility of nickel.

Rh0.5Pd0.5/CeO2 bimetallic nanoparticles were subjected to reducing and oxidizing atmospheres at different temperatures and characterized by means of the Ambient Pressure X-Ray Photoelectron Spectroscopy (AP-XPS). The surface atomic population is calculated for all cases. By using a high temperature pre-treatment at 480 °C in H2 atmosphere, it was possible to control the surface atomic population with Pd atoms frozen at the skin layer even in an oxidizing atmosphere, which is not observed without high temperature pre-treatment (Rh atoms at the skin layer). The change of the Rh/Pd surface segregation behavior after the high temperature pre-treatment is attributed to the geometrical factor of Strong Metal Support Interaction (SMSI) effect, i.e., the occurrence of the ceria capping layer around nanoparticles.

The output side of inverter short circuit to ground is an inevitable and severe work condition. In this paper, the operation mechanism of short circuit running is analyzed in detail. The inductor current waveform is analyzed quantitatively under the traditional double loop control. Aiming at the problem that the power devices loss is large when short circuit, this paper presents a method based on the inductor current hysteresis control. The method significantly reduces the switching times of power devices which effectively decreases the loss of system in the short circuit condition. Taking the dual buck full bridge inverter topology as an example, the short circuit working modes and loss distribution of the inverter are compared under two control methods. The experimental results verify the validity of the method.

Bubble size is a key factor in froth flotation for oil-water separation. In this paper, the bubble size which impacts on oil removal efficiency for a novel oil-water separation column was researched systematically. The bubble size distribution was researched by using the photographic method and Matlab software. In addition, several operating parameters which impact on the bubble size were investigated, including circulating pressure, aeration rate, and the foaming agent. Based on the results of experimental data and image analysis, the frother consumption and aeration rate has important influence on the bubble size. The bubble size can be controlled by adjusting the operation conditions including the circulating pressure, aeration rate, and the frother consumption. The optimum operating conditions for the oil-water separation column were determined. Furthermore, the mathematical model of oil removal efficiency for the oil-water separation column was established.

A unique cyclonic static microbubble flotation column was developed for oily wastewater separation. The separation efficiency was found to be highly dependent on gas holdup and bubble size distribution. By changing the circulation pressure, gas flow rate, frother concentration, the effect of operation parameters on gas holdup and oil removal efficiency were attained. A mathematical modeling between the kinetic constant and the gas holdup was established for oily water separation process. The results show that higher gas holdup and smaller microbubble sizes are beneficial to improve oil removal efficiency. Keywords: Oily wastewater, Separation, Floatation column, Modeling

Spatially resolved ambient pressure X-ray photoelectron spectroscopy has been used to measure and visualize regions of electrochemical activity, local surface potential losses, overpotentials, and oxidation state changes on single sided ceria/yttria-stabilized zirconia (YSZ)/Pt solid oxide electrochemical cells. When hydrogen electro-oxidation (negative applied bias) or water electrolysis (positive applied bias) is promoted on the ceria electrocatalyst, the Ce3+/Ce4+ ratios shift away from equilibrium values and thereby demarcate electrochemically active regions on the ceria electrode. In addition to the ceria oxidation state shifts, inactive surface impurities with high photoelectron cross sections, such as Si, can provide local markers of activity through chemical and surface potential mappings under various electrochemical conditions. Localized removal of chemically active carbonaceous surface impurities also reveals regions of electrochemical oxidation activity on the ceria electrode. Finally, we show...

Highly diverse structures and pore sizes make metal–organic frameworks (MOFs) good candidates for the fabrication of gas separation membranes. The synthesis of continuous MOF membranes still remain...

Ambient pressure X-ray photoelectron spectroscopy was used to detect rigid shifts in photoelectron kinetic energies and material chemical states for operating solid oxide electrochemical cells. The kinetic energy shifts directly correspond to the surface electric potentials and therefore can be used to detect the local potentials / potential losses for operating cells. The ceria valence state changes under applied biases relative to equilibrium conditions (at open circuit voltage) reveal the electrochemically active regions ~150 μm away from the current collectors for ceria thin film electrodes. The results provide fundamental mechanistic information about the active length scales in ceria electrodes, the surface reaction kinetics, charge transport, as well as activities for oxidation and electrolysis on operating solid oxide electrochemical cells.

Thin-film GDC (Ce0.8Gd0.2O2-x 300 nm thick) electrodes with porous Ni or Au metal overlayers (300 nm thick) were sputter-deposited on polycrystalline YSZ substrates and tested in single-chamber cells. With a back-side Pt-counter electrode, the electrochemical cells were characterized by linear-sweep voltammetry and impedance spectroscopy between 650 to 750 ºC in mixtures of H2/H2O/Ar diluent. To complement the electro-chemical tests, ambient-pressure XPS at the Advanced Light Source was performed on active cells in H2/H2O mixtures to measure surface potential and oxidation states. The GDC electrodes showed lower resistance to H2O electrolysis than H2 oxidation with Ni and Au overlayers. XPS measurements indicated large overpotentials across the YSZ/GDC interface particularly for H2 oxidation on the GDC electrode. Increasing PH2/PH2O (up to 10) resulted in higher rates for not only H2 oxidation, but also H2O electrolysis, suggesting that H2O electrolysis activity is enhanced by increased reduction of the GDC surface.

Ambient pressure X-ray photoelectron spectroscopy (XPS) is used to measure near-surface oxidation states and local electric potentials of thin-film ceria electrodes operating in solid oxide electrochemical cells for H2O electrolysis and H2 oxidation. Ceria electrodes which are 300 nm thick are deposited on YSZ electrolyte supports with porous Pt counter electrodes for single-chamber tests in H2/H2O mixtures. Between 635 and 740 °C, equilibrium (zero-bias) near-surface oxidation states between 70 and 85% Ce3+ confirm increased surface reducibility relative to bulk ceria. Positive cell biases drive H2O electrolysis on ceria and further increase the percentage of Ce3+ on the surface over 100 μm from an Au current collector, signifying broad regions of electrochemical activity due to mixed ionic-electronic conductivity of ceria. Negative biases to drive H2 oxidation decrease the percentage of Ce3+ from equilibrium values but with higher electrode impedances relative to H2O electrolysis. Additional tests indic...

Undoped ceria with its facile redox at high-temperatures has potential as an effective material for electrolysis. This study explores the electrochemical performance of thin-film ceria electrodes for H2O electrolysis at 700 °C. The electrochemical characterization is complemented by in situ XPS measurements, which show that the highly reduced ceria surface increases in degree of reduction with electrolysis voltage. Results also show that H2O electrolysis is enhanced with increased H2 partial pressure. Analysis of electrochemical impedance spectra and voltammetric measurements show that the electrolysis reactions depend strongly on H2 pressure. These trends, which are not readily explained by simple surface kinetic models, do indicate that increased ceria surface reduction by the presence of H2 product enhances activity for H2O electrolysis. The results were used to create a microkinetic model to assess surface and subsurface processes in ceria for H2O electrolysis.

The work described here was focused on exploring the potential application of coal to purification of oily waste water. Coal was added to oily waste water as an adsorbent and then removed through a flotation process. This allowed economical and highly efficient separation of oil from the waste water. The absorption time, coal type, coal particle size distribution, pH value and oil concentration were investigated. The results indicate that oil absorption by a coal increases for a period of 1.5 h and then gradually tends toward an equilibrium value. It appears that the absorption capacity of anthracite is more than that of lean coal or lignite, given the same coal particle size distribution. The absorption capacity of a coarse coal fraction is less than that of finer coal, given the same of coal type. The absorption capacity of anthracite decreases slightly as the pH increases from 4 to 9. The adsorption of oil on anthracite follows the Freundlich isothermal adsorption law: given initial oil concentrations of 160.5 or 1023.6 mg/L the absorption capacity was 23.8 or 840.0 mg/g. The absorption mechanism consists of two kinds of absorption, a physical process assisted by a chemical one.

Heterogeneous films of ordered CeO(2)/Ni concentric nanostructures have been fabricated through template-assisted electrodeposition. The free-standing films of Ni metal (8 mum thickness) contain ordered arrays of ceria tubes (200 nm OD, 100 nm ID). Ni/CeO(2) coaxial nanotubes were also obtained by tuning experimental conditions. The interfacial contact area within the 3-dimensional oxide nanotube/nickel matrix is approximately 100 times greater than 2-dimensional thin films of nickel and ceria of the same area. The use of the film as an anode electrocatalyst/current collector is demonstrated in a solid oxide fuel cell.

Single chamber electrochemical cells were fabricated by patterning working and counter electrodes of Ni and Pt on single-crystal Y2O3-stabilized ZrO2. Cells were characterized in mixed atmospheres of H2 and H2O at ratios of 1:1 and 1:20 at nominally 923 K and 67 Pa total pressure. Potential sweep and impedance measurements were conducted simultaneously with ambient-pressure x-ray photoelectron spectroscopy (APXPS), which is a unique synchrotron-based probe designed for in-situ chemical characterization of surfaces using photoemission at gas pressures large enough to achieve realistic densities of faradic current. Electrochemically induced oxidation of Ni was observed under anodic polarization and could be reversed by applying a cathodic bias. The thin-film microstructure could also be manipulated electrochemically in that pores exposing underlying electrolyte would open through the Ni film after polarization. Application of APXPS to resolve fundamental details of high-temperature electrochemical process in-situ is discussed.

Magnetoresistance properties of Ni nanocontacts in the ballistic quantum regime are investigated in situ for several orientations between applied magnetic field and current direction. The symmetry properties of the magnetoresistance curves are similar to anisotropy magnetoresistance effects, even if the shape of the contact is modified. A change of conductance under magnetic field has a magnitude between 0.2e 2 /h and e 2 /h, varying little with the absolute conductance values ranging between e 2 /h and 100e 2 /h. We discuss possible mechanical artifacts to our magnetoresistance curves, showing that the shear of the substrate might contribute to conductance changes. However, replacing the metal used as substrate does not modify our observations.

A ZIF-9-67 hybrid membrane on α-Al(2)O(3) support was prepared using mixed-linker synthesis. The gas permeation and selectivity data demonstrate that this membrane may have potential applications for efficient CO(2) capture from several industrial mixtures.

Long-chain alkane thiols use in metal to organic self-assembled monolayer to metal junctions may be limited by orientational disorder, and photoemission studies suggest that several molecular layers may be needed for the dielectric layer to be effective. Several alkane thiols were investigated in a range of junctions areas 10–102 μm2. Top layer contact deposition, activated with Pd clusters resulted in a high yield of junctions that were not electrically shorted and are stable over a wide temperature range. Zero-bias anomalies, observed at low temperatures, are attributed to a Coulomb blockade associated with the Pd clusters.

Semiconductor selenides of MSe (M = Cd, Hg) nanocrystalline powders were synthesized through the reactions between metal chlorides and sodium selenosulfate in the ammoniacal aqueous solution at room temperature for 6–10 h. The samples were characterized by x-ray powder diffraction, transmission electron microscopy, electron diffraction, x-ray photoelectron spectroscopy, and elemental analysis. The average diameters of CdSe and HgSe nanocrystallites are 4 and 8 nm, respectively. The storage and an interesting phase transition under hydrothermal conditions have been presented. The absorption spectrum of the as-prepared samples exhibits obvious blue shift due to the size confinement.