A Targeted Review of Current Progress,Challenges and Future Perspective of g-C3N4 based Hybrid Photocatalyst Toward Multidimensional Applications

The increasing demand for searching highly efficient and robust technologies in the context of sustainable energy production totally rely onto the cost-effective energy efficient production technologies. Solar power technology in this regard will perceived to be extensively employed in a variety of ways in the future ahead, in terms of the combustion of petroleum-based pollutants, CO₂ reduction, heterogeneous photocatalysis, as well as the formation of unlimited and sustainable hydrogen gas production. Semiconductor-based photocatalysis is regarded as potentially sustainable solution in this context. g-C₃N₄ is classified as non-metallic semiconductor to overcome this energy demand and enviromental challenges, because of its superior electronic configuration, which has a median band energy of around 2.7 eV, strong photocatalytic stability, and higher light performance. The photocatalytic performance of g-C₃N₄ is perceived to be inadequate, owing to its small surface area along with high rate of charge recombination. However, various synthetic strategies were applied in order to incorporate g-C₃N₄ with different guest materials to increase photocatalytic performance. After these fabrication approaches, the photocatalytic activity was enhanced owing to generation of photoinduced electrons and holes, by improving light absorption ability, and boosting surface area, which provides more space for photocatalytic reaction. In this review, various metals, non-metals, metals oxide, sulfides, and ferrites have been integrated with g-C₃N₄ to form mono, bimetallic, heterojunction, Z-scheme, and S-scheme-based materials for boosting performance. Also, different varieties of g-C₃N₄ were utilized for different aspects of photocatalytic application i. e., water reduction, water oxidation, CO₂ reduction, and photodegradation of dye pollutants, etc. As a consequence, we have assembled a summary of the latest g-C₃N₄ based materials, their uses in solar energy adaption, and proper management of the environment. This research will further well explain the detail of the mechanism of all these photocatalytic processes for the next steps, as well as the age number of new insights in order to overcome the current challenges.     

The role of phosphorylated residues in peptide-peptide noncovalent complexes formation

Electrospray mass spectrometry (ESI-MS) has become the tool of choice for the study of noncovalent complexes. Our previous work has highlighted the role of phosphorylated amino acid residues in the formation of noncovalent complexes through electrostatic interaction with arginine residues’ guanidinium groups. In this study, we employ tandem mass spectrometry to investigate the gas-phase stability and dissociation pathways of these noncovalent complexes. The only difference in the three phosphopeptides tested is the nature of the phosphorylated amino acid residue. In addition the absence of acidic residues and an amidated carboxyl terminus insured that the only negative charge came from the phosphate, which allowed for the comparison of the noncovalent bond between arginine residues and each of the different phosphorylated residues. Dissociation curves were generated by plotting noncovalent complex ion intensities as a function of the nominal energy given to the noncovalent complex ion before entering the collision cell. These results showed that noncovalent complexes formed with phosphorylated tyrosine were the most stable, followed by serine and threonine, which had similar stability.     

A study of phospholipids by ion mobility TOFMS

Combining matrix-assisted laser desorption/ionization (MALDI) mass spectrometry with ion mobility (IM) results in the fast sorting of biomolecules in complex mixtures along trend lines. In this two-dimensional (2D) analysis of biological families, lipids, peptides, and nucleotides are separated from each other by differences in their ion mobility drift times in a timescale of hundreds of microseconds. Molecular ions of similar chemical type fall along trend lines when plotted in 2D plots of ion mobility drift time as a function of m/z. In this study, MALDI-IM MS is used to analyze species from all of the major phospholipid classes. Complex samples, including tissue extracts and sections, were probed to demonstrate the effects that radyl chain length, degree of unsaturation, and class/head group have upon an ion’s cross section in the gas phase. We illustrate how these changes can be used to identify individual lipid species in complex mixtures, as well as the effects of cationization on ion cross section and ionization efficiency.     

Site-specific protein propargylation using tissue transglutaminase

Transglutaminases (TGases) catalyse the transamidation of glutamine residues with primary amines. Herein we report the first FRET-based activity assay for the direct detection of the ligation (transamidation) reaction mediated by tissue TGase (TG2). This novel assay was then used in a microtiter plate-based screen of a library of 18 potential amine substrates. From this screen it was discovered that propargyl amine serves as an excellent substrate for TG2. Subsequently, propargyl amine and 2-azidoethyl amine were validated independently as TG2 substrates with K(M) values of 44 ± 4 μM, and 0.99 ± 0.06 mM, respectively. In a proof-of-principle protein labelling experiment, the protein casein was selectively functionalized with propargyl amine using TG2 and subsequently fluorescently labelled through a dipolar cycloaddition reaction with an azido-fluorescein conjugate. This application demonstrates the strong potential of using TG2 for site-specific protein modification through a combination of enzymatic and bioorthogonal chemistry.     

Textural and adsorption characteristics of carbon xerogel adsorbents for removal of Cu (II) ions from aqueous solution

Resorcinol–formaldehyde (RF) carbon xerogels were synthesized using different resorcinol/sodium carbonate catalyst molar ratios (R/C = 50, 200, 500 and 1000) and heat treatment temperatures (HTT = 500, 600 and 700) under no external gas flow. The carbon adsorbents were extensively characterized by CHO content, FTIR, TEM and nitrogen adsorption isotherm at 77 K. The effect of R/C, HTT and oxygen content on the development of porosity within carbons was studied. Also, the adsorption capacity of these adsorbents was investigated by the removal of copper (II) ions from aqueous solution using single bottle test. The produced carbon xerogels exhibit a micro-mesopore character, but with different extents depending on the mechanism of porosity generation in relation to R/C, HTT and oxygen functional groups. Results show that the optimum conditions to obtain porous carbon xerogels were the highest R/C = 500–1000 in combination with carbonization preferably at 600 or 700 °C. Single bottle removal of Cu (II) ions indicated the developed carbons with appreciable capacity (q_u = 32–130 mg/g) which are controlled by the surface area and surface chemical nature (acidic O-functional groups). Finally, the present investigation provides a new, nanoporous type of porous carbon adsorbents with high adsorption capacity for removal of heavy metals from wastewater media.     

Cascade ultrafiltration and competing ligand exchange for kinetic speciation of aluminium, iron, and nickel in fresh water

Kinetic speciation of nickel, aluminium, and iron in fresh water has been investigated by cascade ultrafiltration followed by competing ligand exchange of the ultrafiltered fractions. Graphite furnace atomic absorption spectrometry was used to measure the kinetics of metal complex dissociation. Dissolved metal species were fractionated by cascade ultrafiltration. Metal speciation in each ultrafiltered fraction was then characterized as free metal ions, “labile” metal complexes (with dissociation rate constants ≥10⁻³ s⁻¹), “slowly labile” metal complexes (with dissociation rate constants >10⁻⁶ s⁻¹), and “inert” metal complexes (with dissociation rate constants <10⁻⁶ s⁻¹). The experimental results were compared with the predictions of a computer-based equilibrium speciation model, the Windermere humic aqueous model (WHAM) V. Cascade ultrafiltration coupled with kinetic speciation of the metal species in each molecular weight cut-off (MWCO) fraction provided a more comprehensive picture and insight into the physical and the chemical characteristics of the metal species than either ultrafiltration or measurement of dissociation kinetics alone.