Solar light-driven reduction of crystal violet by a composite of g-C3N4, β-Ag2Se, γ-Fe2O3 and graphite

Abstract

In this work, a new g-C₃N₄-based Z-scheme with γ-Fe₂O₃ and β-Ag₂Se both n-type semiconductors, and graphite to favor electron exchange is presented. The composite material was studied by XRD, FTIR, UV-Vis, TEM, XPS, TGA, DSC and TOF-SIMS, and the ability of this photocatalytic system to act as a photo-reductant was assessed using crystal violet (CV⁺) dye. Solar light driven photo-reduction of CV⁺ in the presence of tri-sodium citrate evidenced a synergistic enhancement of the activity of the composite toward reduction, with ～20 times higher conversion rates per unit of surface area than those of g-C₃N₄. Photo-oxidation experiments under Xe lamp irradiation in the presence of H₂O₂ also showed that the AgFeCN composite featured a higher activity (～8×) than g-C₃N₄. This Z-scheme may deserve further study as a photo-reductant to obtain hydrogen or hydrogenated compounds. Moreover, the use of CV⁺ may represent a facile procedure that can aid in the selection of new photocatalysts to be used in hydrogen production.     

Crosslinking reactions and swelling behavior of matrices based on N-acryloyl-TRIS(hydroxymethyl)aminomethane

Summary In this study, new hydrogels in rod shape were prepared from N-acryloyl-TRIS(hydroxymethyl)aminomethane (NAT) using ethylene glycol dimethacrylate (EGDMA) or N,N’methylenebisacrylamide (BIS) as crosslinking agent, dimethylformamide (DMF) as solvent and benzoyl peroxide (BPO) as initiator. In most cases, 2-hydroxyethyl methacrylate (HEMA), acrylamide (Aam) or acrylic acid (Aac) were used as co-monomers. The polymeric matrices obtained by free radical polymerization exhibited different properties by changing crosslinker, crosslinker concentration, co-monomer and initial NAT/co-monomer mole ratio. Besides, hydrogels from HEMA, Aam and Aac with BIS in absence of NAT were prepared under the same experimental reaction conditions in order to compare the properties of these products with those synthesized from NAT and the respective co-monomers. Some of the final products were selected to perform urea release assays, conducted through swelling-controlled release. Urea was chosen as “model” plant fertilizer agent.     

A new FMS architecture based upon networked DSP servo technology

This paper presents a critical evaluation of existing FMS architectures and the academic and industrial design and development strategies used during their formulation. The paper seeks to address the need for, and value of, existing architectures within the industrial arena. More importantly however, this paper puts forward a new two-tier distributed control architecture for FMS based upon new (real-time) networkable DSP servo control methodologies developed by one of the authors for Softronics in Australia. The ramifications of these methodologies are substantial, not only in terms of FMS control, but in the overall simplification of such systems and the development of flexible fixturing devices over the coming decade. This paper also postulates on how new FMS architectures can be developed from such technologies and details why such architectures could be more appropriate to industry needs than those that are currently in existence.     

Multiple time-scale diffusion models of starfish and coral state changes over the whole great barrier reef

A model is developed to investigate starfish and coral dynamics at the macro-scale of the whole Great Barrier Reef. This stochastic near-equilibrium theory is consistent with all available data for the mean rates of change of reef-state relative to abundances of the starfishAcanthaster planci and the scleractinian corals upon which it preys. This result is in striking contrast to the stably cyclic behaviour which dominates the meso-scale of individual reefs as reported previously by the authors. For the first time, a number of important numerical estimates have been made and are reported here. Generally, the starfish dynamics is dominated by randomness, being indistinguishable from Brownian motion in the state-space. On the other hand, the coral process is embedded in a drift field which is always directed towards the low coral state. In fact, the high coral state is inaccessible on the Great Barrier Reef.     

Synthesis and Evaluation of Blends Formed by Polymeric Crown Ethers and a Fullerene-Containing Primary Ammonium Salt in Organic Thin Films

The synthesis of a series of polymers and cyclopolymers bearing crown ethers of differing structure and affinities towards primary ammonium ions is discussed. These polymers have been tested in their efficiency to form structurally homogeneous thin films when blended with an amphiphilic C₆₀ compound containing a primary ammonium ion functional group. The X-ray reflectivity characterization of the films revealed that the polymer bearing the crown ether with the least affinity for primary ammonium ions, but having the highest degree of polymerization, is the most effective in forming structurally homogeneous thin films.     

From "macro" to "micro" manipulation: models and experiments

This paper addresses various problems related to manipulation in the micro domain, a field which is increasingly important for research and application. Grasping and manipulating parts with size ranging between a few micrometers and about 1 millimeter (defined in this paper as "micro parts") are required for an increasing number of applications: the assembly of micro systems and micro machines; and the operation in tiny and unpredictable environments, such as for inspection and interventions in pipes and for micro surgery. The aim of this work is to find out similarities and differences between traditional manipulation and micro manipulation, by investigating which requirements are still valid and which must be redefined when the object size scales down. The similarities between the two application domains "macro" and "micro" are pointed out along with the differences, and both are taken into account for the evaluation of different grasping typologies. Dedicated models for the adhesion forces arising at the micro level are presented, preliminarily tested, and discussed.     

Computing the energy balance of a statue of bronze: The San Marco's horses as a case study

The energy balance is discussed for the complex case of bronze or marble statuary horses and particularly the four horses of San Marco in Venice. Having computed the coefficient of exchange between bronze and the atmosphere, the daytime overheating is evaluated for different seasons and orientations of the statues. The equations can be solved with reasonable approximation and both the past and future overheatings can be evaluated as a function of the growing surface weathering and blackening. Therefore, the present analysis points out the chief characteristics of both the diurnal cycle and the variation over the centuries of the response of the bronzes to atmospheric variables.     

Statistics of the DGD in PMD emulators

We give the statistics of the differential group delay at the output of a polarization-mode dispersion emulator made of a chain of fiber sections with constant birefringence, fixed and arbitrarily selected lengths, and randomly oriented polarization controllers in between.     

Low-cost, redundant proximity sensor system for spatial sensing andcolour perception

The authors describe their approach to the design of redundant proximity sensor systems that are capable of extracting geometrical information about the surrounding environment and perceiving other relevant features of the reflecting objects, e.g. colour. Potential applications of the proposed sensorial systems are in the field of robotics and autonomous mobility