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To achieve efficient and safe cationic carrier-mediated gene delivery for gene therapy, the optimal ratio of carrier to DNA in formulations is a key factor and it is usually determined prior to transfection experiments. In this work, a simplified drop-and-read assay was developed for the first time using paper as a platform to estimate the equivalence ratio of cationic carriers to negatively charged DNA. By spotting a series of complexes containing varied ratios of carrier to DNA on filter paper, then allowing them to dry and finally dropping yellowish-green anionic 2',7'-dichlorofluorescein dye solution on top of the complexes, the equivalence point was detectable by the instant formation of stable pink spots as a result of the dye adsorption onto the positively charged complexes and free carriers. The method gave the same results as those determined by gel retardation assay and zeta potential measurement, however it allowed more rapid reporting of results in 5 min and required no tedious steps, harmful reagents or expensive instruments. By using paper instead of microcentrifuge tubes and omitting centrifugation, plasticware and electrical energy were no longer consumed and disposal of this degradable material was more environmentally friendly. With respect to analytical performance, filter paper inherently holding negative charge helped to trap and concentrate the complexes on the white background, enabling greater visibility of the colored spots and a lower required amount of DNA used for the assay. The method was successfully applied to estimate the equivalence ratios in a variety of gene delivery formulations containing different types of cationic carriers, i.e. polymers, dendrimers, liposomes and niosomes.

We investigated the effect that two common types of cationic polyelectrolytes used in papermaking might have on the performance of paper diagnostics using blood typing as an example. The results were analyzed in terms of red blood cells (RBC) retention and antibody–antigen specificity. Two questions were addressed: (1) can poly(amido-amine) epichlorohydrin (PAE) typically used for paper wet strength affect the diagnostic performance? (2) can high molecular weight cationic polyacrylamide (CPAM) employed as retention aid enhance or affect the selectivity and sensitivity of paper diagnostics? A series of paper varying in type of fibers and drying process were constructed with PAE and tested for blood typing performance. Residual PAE has no significant effect on blood typing paper diagnostics under normal conditions. Positives are unaffected with PAE, while negatives lose slight sharpness as some RBCs are unselectively retained. CPAM, the most common retention aid, can also be used to retain cells and biomolecules on paper. Paper towel was treated with CPAM solutions varying in polymer concentration and charge density and tested for blood typing. We found that CPAM dried on paper can retain RBC. CPAM affects the negative tests by retaining non-specifically individual RBC on fibers. RBC retention increases non-linearly with the CPAM charge density and concentration. As expected, wet CPAM retain RBCs at concentrations higher than 0.1 wt%. As paper diagnostics are becoming a reality, more realistic papers than the Whatman filter paper will be engineered. This study provides guidance on how best use the required polymeric wet-strength and retention agents.

The use of non-wood fibers in the paper industry has been an economical and environmental necessity. The application of dry-strength agents has been a successful method to enhance the strength properties of paper. The experimental results evidencing the potential of chitosan and cationic starch utilization in bagasse paper subjected to hot water pre-extraction has been presented in this paper. The research analyzes the surface properties alterations due to these dry-strength agents. Inverse gas chromatography was used to evaluate the properties of surface chemistry of the papers namely the surface energy, active sites, surface area as well as the acidic/basic character. The results of the study revealed that the handsheets process causes surface arrangement and orientation of chemical groups, which induce a more hydrophobic and basic surface. The acid-base surface characteristics after the addition of dry-strength agents were the same as the bagasse handsheets with and without hot water pre-extraction. The results showed that the dry-strength agent acts as a protecting film or glaze on the surfaces of bagasse paper handsheets.

This study examines and quantifies the effect of cationic polyelectrolyte adsorption on paper on the aggregation and retention of gold nanoparticles (AuNPs) to optimize their Surface Enhanced Raman Scattering (SERS) enhancement factor and sensitivity. Aggregation of metallic nanoparticles is known as a key factor for intense SERS enhancement. Paper substrates were treated with aqueous solutions of cationic polyacrylamide (CPAM) varying in concentration, charge density, and molecular weight to control the AuNPs' aggregate size distribution and surface coverage on paper. The Raman Enhancement Factor of AuNPs-CPAM paper was almost an order of magnitude greater than for the untreated AuNPs paper. The high loading and uniform distribution of AuNPs aggregates on CPAM pre-treated paper contributed toward the excellent SERS reproducibility, sensitivity, and high enhancement factor. This configuration of AuNP on paper was favoured by treating the substrate with CPAM solutions of higher concentrations, higher charge density, and greater molecular weight.

Journal article Cationic polymers with various structures have been widely investigated in the areas of medical diagnostics and molecular, biology because of their unique binding properties and capability to interact with biological molecules in complex biological environments.; In this work-we report the grafting of a linear cationic polymer from an atom transfer radical polymerization (ATRP) initiator bound to cellulose paper surface. We show successful binding of ATRP initiator onto cellulose paper and grafting of polymer chains from the immobilized initiator with ATRP. The cellulose paper grafted polymer was used in combination with PicoGreen (PG) to demonstrate detection of nucleic acids in the nanogram range in homogeneous solution and in a biological sample (serum). The results showed specific identification of hybridized DNA after addition of PG in both solutions. peer-reviewed

The effect of polymer on the retention and the thermal stability of bioactive enzymatic papers was measured using a colorimetric technique quantifying the intensity of the enzyme–substrate product complex. Alkaline phosphatase (ALP) was used as model enzyme. Three water soluble polymers: a cationic polyacrylamide (CPAM), an anionic polyacrylic acid (PAA) and a neutral polyethylene oxide (PEO) were selected as retention aids. The model polymers increased the enzyme adsorption on paper by around 50% and prevented enzyme desorption upon rewetting of the papers. The thermal deactivation of ALP retained on paper with polymers follows two sequential first order reactions. This was also observed for ALP simply physisorbed on paper. The retention aid polymers instigated a rapid initial deactivation which significantly decreased the longevity of the enzymatic papers. This suggests some enzyme–polymer interaction probably affecting the enzyme tertiary structure. A deactivation mathematical model predicting the enzymatic paper half-life was developed.

Instituto de Recursos Naturales y Agrobiología, CSIC, P.O. Box 1052, E-41080, Seville, Spain E-mail address: delrio@irnase.csic.es, The composition of pitch deposits occurring in pulp sheets and mill circuits during soda/anthraquinone pulping and elemental chlorine-free pulp bleaching of bast fibers of industrial hemp (Cannabis sativa) has been studied. Pitch deposits were extracted with acetone, and the extracts analyzed by gas chromatography (GC) and gas chromatography/mass spectrometry (GC/MS). Acetone extracts (15-25% of pitch deposits) were constituted by the defoamers used at the mill and by lipophilic extractives from hemp fibers. Acetone-insoluble residues (75-85% of pitch deposits) were analyzed by pyrolysis-GC/MS in the presence and absence of tetramethylammonium hydroxide. These residues were constituted by salts of fatty acids (arising from hemp fibers) with calcium, magnesium, aluminum and other cations that were identified in the deposits. It was concluded that inappropriate use of defoamer together with the presence of multivalent ions seemed to be among the causes of hemp extractives deposition in the pitch problems reported here., This study has been supported by the Spanish Ministerio de Ciencia y Tecnología (MCYT) and FEDER funds (projects 2FD97-0896-C02-02 and AGL2002-00393). A.G. acknowledges a "Ramón y Cajal" contract of the Spanish MCYT. We also thank CELESA (Tortosa, Spain) for providing the samples.

24 páginas Contiene 4 figuras y 5 tablas. 23 referencias en las páginas 441-442 Soil formation has been studied in relation with time in a 5000-year old chronosequence on volcaniclastic beach ridges of the perhumid tropical Atlantic coast of Costa Rica. All soils are under tropical rainforest. Drainage conditions change by subsidence from excessively drained in the two youngest soils to imperfectly drained in the two oldest soils. Parent material is rather homogeneous andesitic sand with a volcanic glass component of less than 10%. It has been found that under these conditions Andisols form within 2000 years. Imperfect drainage caused mottling and accumulation of iron-coatings, as well as the formation of a thin O-horizon in the oldest profiles. Sand content of the soils decreases regularly with soil age, while the amount of fine material increases concurrently. The increase in fine material and the accumulation of organic matter cause an increase of CEC and andic properties, and a decrease in bulk density and pH with soil age. Depth of biological influence increases with soil age, but soil faunal activity is hampered in the oldest three profiles, probably by imperfect drainage. Due to the extreme leaching conditions, the sum of exchangeable cations is less than 2 cmol + kg- 1 in the B-horizons of the older soils, notwithstanding the presence of a considerable amount of weatherable primary minerals.

Chemistry - a European journal 27(48), 12371 - 12379 (2021). doi:10.1002/chem.202101515, We investigated the photoionization and fragmentation of isolated metal protoporphyrin IX cations (MPPIX+ with M=Fe, Co, Zn) by means of vacuum-ultraviolet (VUV) action spectroscopy in the energy range of 8.5���35 eV. Experiments were carried out in the gas phase by interfacing an electrospray ionization tandem mass spectrometer with a synchrotron beamline. The mass spectra and partial ion yields show that photoexcitation of the precursor ions predominantly leads to .CH$_2$COOH radical side-chain losses of the macrocycle with additional methyl radical (.CH$_3$) side-chain losses. Ionization, in contrast, leads to the formation of the intact ionized precursor and various doubly charged fragments which are mostly due to side-chain cleavages. Although statistical fragmentation dominates, we found evidence for non-statistical processes such as new fragments involving for example single and double H2O losses, indicating that different relaxation mechanisms are at play upon photoionization compared to photoexcitation. The measured ionization energies were 9.6��0.2 eV, 9.4��0.2 eV and 9.6��0.2 eV for FePPIX$^+$, CoPPIX$^+$ and ZnPPIX$^+$, respectively., Published by Wiley-VCH, Weinheim

Strongly Lewis acidic cationic aluminium complexes, stabilized by β–diketiminate (BDI) ligands and free of Lewis bases, have been prepared as their B(C6F5)4 − salts and were investigated for catalytic activity in imine hydrogenation. The backbone (R1) and N (R2) substituents on the R1,R2BDI ligand (R1,R2BDI=HC[C(R1)N(R2)]2) influence sterics and Lewis acidity. Ligand bulk increases along the row Me,DIPPBDI, A series of strongly Lewis acidic cationic aluminium complexes, stabilized by β–diketiminate (BDI) ligands and free of Lewis bases, have been prepared as their B(C6F5)4 − salts. Their catalytic activity in imine hydrogenation depends strongly on the substituents in the BDI ligand. DFT calculations on the mechanism reveal two interconnected catalytic cycles. Hydrogen is activated either by Al⋅⋅⋅imine or Al⋅⋅⋅amine Frustrated‐Lewis‐Pairs.

The homospermidine synthases from P. aeruginosa and B. viridis, as well as their single-residue variants, are compared based on crystal structures and activity assays. A high structural similarity is demonstrated, suggesting the equivalent involvement of relevant residues in the reaction mechanism and catalytic dependence on cation–π interaction., Polyamines influence medically relevant processes in the opportunistic pathogen Pseudomonas aeruginosa, including virulence, biofilm formation and susceptibility to antibiotics. Although homospermidine synthase (HSS) is part of the polyamine metabolism in various strains of P. aeruginosa, neither its role nor its structure has been examined so far. The reaction mechanism of the nicotinamide adenine dinucleotide (NAD+)-dependent bacterial HSS has previously been characterized based on crystal structures of Blastochloris viridis HSS (BvHSS). This study presents the crystal structure of P. aeruginosa HSS (PaHSS) in complex with its substrate putrescine. A high structural similarity between PaHSS and BvHSS with conservation of the catalytically relevant residues is demonstrated, qualifying BvHSS as a model for mechanistic studies of PaHSS. Following this strategy, crystal structures of single-residue variants of BvHSS are presented together with activity assays of PaHSS, BvHSS and BvHSS variants. For efficient homospermidine production, acidic residues are required at the entrance to the binding pocket (‘ionic slide’) and near the active site (‘inner amino site’) to attract and bind the substrate putrescine via salt bridges. The tryptophan residue at the active site stabilizes cationic reaction components by cation–π interaction, as inferred from the interaction geometry between putrescine and the indole ring plane. Exchange of this tryptophan for other amino acids suggests a distinct catalytic requirement for an aromatic interaction partner with a highly negative electrostatic potential. These findings substantiate the structural and mechanistic knowledge on bacterial HSS, a potential target for antibiotic design.

Plastic waste in the ocean and on land in the form of nanoplastics is endangering food and drinking water supplies, raising the need for new strategies for the removal of plastic nanoparticles from complex media. In the present contribution we suggest considering ionic liquids as extractants, since they show several advantageous properties that may facilitate the design of efficient separation processes. Through varying the anion and the side chain at the cation, the interactions between the extractant and the polymer can be strengthened and tuned, and thereby the disintegration of the particle into separate polymer chains can be controlled. Oxidized moieties can also be efficiently solvated, given the amphiphilic nature of the considered ionic liquids, allowing also realistic particles to be extracted into these solvents. The phase transfer was found to be thermodynamically and kinetically possible, which is supported by the complicated structure of the ionic liquid‐water interface through the rearrangement of the interfacial ions, and the formation of a micelle around the plastic already at the edge of the aqueous phase., Hydrophobic ionic liquids are suggested as extracting solvents for the removal of nanoplastics from aqueous systems, to reduce the concentration of these potentially hazardous materials. Based on molecular modeling, comparison with molecular solvents reveal clear advantages for ionic liquids in terms of solvation and disintegration of the plastic particle, and the phase transfer mechanism. The results suggest ways of tuning and improving an extraction process.

Synthesis of mixed‐substituted tetraphosphetanes (RP−PtBu)2 (R=Ph (4), Py (5); Py=2‐pyridyl) is achieved from the condensation of dipyrazolylphosphanes RPpyr2 (R=Py (1), Ph (3); pyr=3,5‐dimethylpyrazolyl) as P1‐building block (R−P) and tBuPH2 in an equimolar ratio. Compound 5 is of special interest since the presence of two pyridyl‐substituents as well as the P4‐core allows for a rich coordination chemistry with coinage metal salts [Cu(MeCN)4][OTf], Ag[OTf] and in situ formed [Au(tht)][OTf] (tht=tetrahydrothiophene). Both tetraphosphetanes undergo alkylation reaction with MeOTf to give a series of tetraphosphetanium and tetraphosphetanediium triflate salts with additional methylation of the pyridyl‐moiety in case of 5 resulting in interesting novel cyclic trications. Harsh reaction condition and an excess of MeOTf converts 5 into the cyclic trication [‐P(MePy)PMe2P(MePy)PtBu‐]3+ (13 3+; MePy=1‐methylpyridiniumyl) through the elimination of isobutene. This salt undergoes a complicated rearrangement reaction involving a P−P/P−P bond metathesis to form trication [‐P(MePy)3PtBu‐]3+ (17 3+) when reacted with Me2PPMe2., Choose your donor: A convenient route towards mixed‐substituted tetraphosphetanes was established, enabling the synthesis of (PhP‐PtBu)2 and (PyP‐PtBu)2 (Py=2‐pyridyl) in good yields. The coordination chemistry of (PyP‐PtBu)2 was investigated by reacting it with coinage metal triflate salts. Further methylation studies on both tetraphosphetanes revealed an interesting chemistry of multiply charged, cylic polyphosphanes.

Cerium‐tungstate polyoxoanions are combined with caffeinium cations to give a hybrid organic‐inorganic material with anti‐HIV activity. Biochemical assays highlight the low cytotoxicity of the compounds together with their promising antiviral activity. Initial mechanistic studies provide information on their mode of action. Polyoxometalates (POMs), molecular metal oxide anions, are inorganic clusters with promising antiviral activity. Herein we report increased anti‐HIV‐1 activity of a POM when electrostatically combined with organic counter‐cations. To this end, Keggin‐type cerium tungstate POMs have been combined with organic methyl‐caffeinium (Caf) cations, and their cytotoxicity, antiviral activity and mode of action have been studied. The novel compound, Caf4K[β2‐CeSiW11O39]×H2O, exhibits sub‐nanomolar antiviral activity and inhibits HIV‐1 infectivity by acting on an early step of the viral infection cycle. This work demonstrates that combination of POM anions and organic bioactive cations can be a powerful new strategy to increase antiviral activity of these inorganic compounds., publishedVersion

Two different chromophores, namely a dipolar and an octupolar system, were prepared and their linear and nonlinear optical properties as well as their bioimaging capabilities were compared. Both contain triphenylamine as the donor and a triarylborane as the acceptor, the latter modified with cationic trimethylammonio groups to provide solubility in aqueous media. The octupolar system exhibits a much higher two‐photon brightness, and also better cell viability and enhanced selectivity for lysosomes compared with the dipolar chromophore. Furthermore, both dyes were applied in two‐photon excited fluorescence (TPEF) live‐cell imaging., Dipole versus octupole: Branching of a cationic triarylborane chromophore leads to a cooperative increase in the two‐photon absorption cross‐section and brightness, as well as higher selectivity towards lysosomes and better cell viability. The octupolar dye was demonstrated to be an ideal candidate for two‐photon excited fluorescence imaging of lysosomes in live cells.

Liposomes have been widely applied in bioanalytical assays. Most liposomes used bare negative charges to prevent non-specific binding and increase colloidal stability. Here, in contrast, highly stable, positively charged liposomes entrapping the fluorescent dye sulforhodamine B (SRB) were developed to serve as a secondary, non-specific label‚ and signal amplification tool in bioanalytical systems by exploiting their electrostatic interaction with negatively charged vesicles, surfaces, and microorganisms. The cationic liposomes were optimized for long-term stability (> 5 months) and high dye entrapment yield. Their capability as secondary, non-specific labels was first successfully proven through electrostatic interactions of cationic and anionic liposomes using dynamic light scattering, and then in a bioassay with fluorescence detection leading to an enhancement factor of 8.5 without any additional surface blocking steps. Moreover, the cationic liposomes bound efficiently to anionic magnetic beads were stable throughout magnetic separation procedures and could hence serve directly as labels in magnetic separation and purification strategies. Finally, the electrostatic interaction was exploited for the direct, simple, non-specific labeling of gram-negative bacteria. Isolated Escherichia coli cells were chosen as models and direct detection was demonstrated via fluorescent and chemiluminescent liposomes. Thus, these cationic liposomes can be used as generic labels for the development of ultrasensitive bioassays based on electrostatic interaction without the need for additional expensive recognition units like antibodies, where desired specificity is already afforded through other strategies. Graphical abstract Electronic supplementary material The online version of this article (10.1007/s00216-020-02612-w) contains supplementary material, which is available to authorized users.

Bioflocculant-producing bacteria were isolated from various water reservoirs and sediments of the water treatment plant. Four promising strains were identified by standard biochemical methods and 16s rRNA gene sequencing. Bioflocculants were produced in a batch bioreactor of 3 L under optimized conditions. Fourier transformed infrared spectroscopy and scanning electron microscopy (SEM) were used to confirm the chemical and morphological nature of bioflocculants. Anionic and cationic textile dyes congo red (CR) and rhodamine-B (RB) decolourization efficiency by ethanol precipitated bioflocculants were accessed under different values of pH, temperature, dose of flocculant and presence of monovalent, divalent and trivalent cations. Bioflocculants of all the four isolates were found to be highly efficient in decolourization of dye from an aqueous medium with the removal rate up to 99.56%. The removal rate of CR and RB from aqueous medium was largely influenced by the physiochemical condition of the solution viz. pH, temperature, concentration of ions and dose of flocculants. The microbial bioflocculants are biodegradable and highly stable as well as possess abroad range of pH, temperature and ions tolerance range. So, they may be economical and can be greener substitutes for the present harsh chemical-based wastewater effluent treatment methods.

Zwitterionic surface modification is a promising strategy for nanomedicines to achieve prolonged circulation time and thus effective tumor accumulation. However, zwitterion modified nanoparticles suffer from reduced cellular internalization efficiency. Methods: A polyprodrug-based nanomedicine with zwitterionic-to-cationic charge conversion ability (denoted as ZTC-NMs) was developed for enhanced chemotherapeutic drug delivery. The polyprodrug consists of pH-responsive poly(carboxybetaine)-like zwitterionic segment and glutathione-responsive camptothecin prodrug segment. Results: The ZTC-NMs combine the advantages of zwitterionic surface and polyprodrug. Compared with conventional zwitterionic surface, the ZTC-NMs can respond to tumor microenvironment and realize ZTC surface charge conversion, thus improve cellular internalization efficiency of the nanomedicines. Conclusions: This ZTC method offers a strategy to promote the drug delivery efficiency and therapeutic efficacy, which is promising for the development of cancer nanomedicines.

Ions are ubiquitous in nature. They play a key role for many biological processes on the molecular scale, from molecular interactions, to mechanical properties, to folding, to self‐organisation and assembly, to reaction equilibria, to signalling, to energy and material transport, to recognition etc. Going beyond monovalent ions to multivalent ions, the effects of the ions are frequently not only stronger (due to the obviously higher charge), but qualitatively different. A typical example is the process of binding of multivalent ions, such as Ca2+, to a macromolecule and the consequences of this ion binding such as compaction, collapse, potential charge inversion and precipitation of the macromolecule. Here we review these effects and phenomena induced by multivalent ions for biological (macro)molecules, from the “atomistic/molecular” local picture of (potentially specific) interactions to the more global picture of phase behaviour including, e. g., crystallisation, phase separation, oligomerisation etc. Rather than attempting an encyclopedic list of systems, we rather aim for an embracing discussion using typical case studies. We try to cover predominantly three main classes: proteins, nucleic acids, and amphiphilic molecules including interface effects. We do not cover in detail, but make some comparisons to, ion channels, colloidal systems, and synthetic polymers. While there are obvious differences in the behaviour of, and the relevance of multivalent ions for, the three main classes of systems, we also point out analogies. Our attempt of a comprehensive discussion is guided by the idea that there are not only important differences and specific phenomena with regard to the effects of multivalent ions on the main systems, but also important similarities. We hope to bridge physico‐chemical mechanisms, concepts of soft matter, and biological observations and connect the different communities further., Ions play an important role for a large variety of biological processes. Compared to monovalent ions, the effects of multivalent ions are often qualitatively different and can include complex phenomena such as charge inversion and precipitation of macromolecules. In this article, we review the effects of multivalent ions on biological (macro)molecules from the molecular to the global level. Our hope is to bridge physico‐chemical, soft matter and biological aspects, thereby stimulating discussions between these scientific communities.

In accordance with the opinion of the World Health Organization and the World Water Council the development of effective technologies for the treatment of wastewater from heavy metals for their discharge into water bodies or reuse is an urgent task nowadays. Phytoremediation biotechnologies is the most environmentally friendly and cheapest way of the treatment of wastewater, suitable for sustainable development principals. The main disadvantage of the phytoremediation is the slow speed of the process. A method for accelerating the process of phytoremediation by the combined effect of magnetic and weak electric fields is proposed. The purpose of this study is to determine the values of the parameters of the magnetic and weak electric fields that are most suitable for extracting cuprum ions from wastewater using the higher aqua plants (Lemna minor). A corresponding technological process based on the results of the study is proposed. The results have shown that the removal of copper cations from sulfate solutions effectively occurs in the initial period of time (1–5 hours) under the influence of a magnetic field with an intensity of H = 2 kA/m. Under the combined influence of an electrical current with density j = 240 μA/cm2 and a magnetic field (H = 2 kA/m) the highest rate of copper extraction by duckweed leaves is achieved. Under these conditions, the greatest growth and development of plant leaves occurs. The paper presents the results of determining of the parameters of the electrochemical release from the eluate of the spent phytomass of duckweed. It has been determined that the release of metal occurs at E = 0.32 V. An original scheme for wastewater treatment from copper with subsequent separation of copper from the spent phytomass of duckweed is proposed. In general, the presented results are a scientific justification of wastewater treatment technologies and a contribution to resolving the crisis in the field of fresh water supply. An important contribution in the circular economy is a technology recommendation proposed for recovering copper from duckweed after wastewater treatment.

Bis‐NHC stabilized germyliumylidenes [RGe(NHC)2]+ are typically Lewis basic (LB) in nature, owing to their lone pair and coordination of two NHCs to the vacant p‐orbitals of the germanium center. However, they can also show Lewis acidity (LA) via Ge−CNHC σ* orbital. Utilizing this unique electronic feature, we report the first example of bis‐NHC‐stabilized germyliumylidene [MesTerGe(NHC)2]Cl (1), (MesTer=2,6‐(2,4,6‐Me3C6H2)2C6H3; NHC= IMe4=1,3,4,5‐tetramethylimidazol‐2‐ylidene) catalyzed reduction of CO2 with amines and arylsilane, which proceeds via its Lewis basic nature. In contrast, the Lewis acid nature of 1 is utilized in the catalyzed hydroboration and cyanosilylation of carbonyls, thus highlighting the versatile ambiphilic nature of bis‐NHC stabilized germyliumylidenes., The versatile ambiphilic catalytic application of a bis‐NHC‐stabilized germyliumylidene enables a range of reductive functionalization reactions, with a particular emphasis on C=O reduction that is, CO2 and carbonyls.

Au2 + is a simple but crucial model system for understanding the diverse catalytic activity of gold. While the Au2 + ground state (X2Σg +) is understood reasonably well from mass spectrometry and computations, no spectroscopic information is available for its first excited state (A2Σu +). Herein, we present the vibrationally resolved electronic spectrum of this state for cold Ar‐tagged Au2 + cations. This exceptionally low‐lying and well isolated A2Σ(u) +←X2Σ(g) + transition occurs in the near‐infrared range. The observed band origin (5738 cm−1, 1742.9 nm, 0.711 eV) and harmonic Au−Au and Au−Ar stretch frequencies (201 and 133 cm−1) agree surprisingly well with those predicted by standard time‐dependent density functional theory calculations. The linearly bonded Ar tag has little impact on either the geometric or electronic structure of Au2 +, because the Au2 +⋅⋅⋅Ar bond (∼0.4 eV) is much weaker than the Au−Au bond (∼2 eV). As a result of 6 s←5d excitation of an electron from the antibonding σu * orbital (HOMO‐1) into the bonding σg orbital (SOMO), the Au−Au bond contracts substantially (by 0.1 Å)., The Au2 + cation: The high‐resolution near‐infrared spectrum of the lowest excited electronic state of this simple diatomic cation recorded by Ar‐tagging photodissociation exhibits a surprisingly simple vibronic structure. Analysis by standard TD‐DFT calculations provides the first spectroscopic information about the chemical bond in Au2 + in both the ground and excited electronic states.

A nutritional survey was conducted to study the influence of variety and rootstock on interactionamong K+, Ca++, Mg++and Na+ ions in grape during 2012-14. Soil cation contents did not correlatewith their respective contents in petioles indicating a strong antagonism among them. Quadraticrelationship of soil cations with the absorption (ratio of petiole content to soil content) of otherions revealed that the antagonism among cations was observed in case of soil K+ with Ca++ andNa+ absorption on 110R and Dog Ridge rootstocks, soil Ca+ with K+ and Mg++ and Na+ in Sonakavariety and Na+ in own rooted vines, soil Mg++ with Ca++ and Na+ also in own rooted vines; andNa++ with Ca++ and Mg++ respectively in 2A clone and Dog Ridge. Contrarily, increased absorptionof K+ by soil Ca++ on 110R, Na+ and K+ by soil Mg++ respectively in Sonaka and 110R, and Ca++by soil Na+ on Dog Ridge was also observed. All the soil cations together influenced K+ absorptionmost in Sonaka followed by Mg++ absorption in 2A clone, but Ca++ absorption on Dog Ridgefollowed by K+ on 110R.

The discharge of inadequately treated or untreated industrial wastewaters has greatly contributed to the release of contaminants into the environment, including toxic metals. Toxic metals are persistent and bioaccumulative, being their removal from wastewaters prior to release into water bodies of great concern. Literature reports the use of brown marine macroalgae for toxic metals removal from aqueous solutions as an economic and eco-friendly technique, even when applied to diluted solutions. Minor attention has been given to the application of this technique in the treatment of real wastewaters, which present a complex composition that can compromise the biosorption performance. Therefore, the main goal of this comprehensive review is to critically outline studies that: (i) applied brown marine macroalgae as natural cation exchanger for toxic metals removal from real and complex matrices; (ii) optimised the biosorption process in a fixed-bed column, which was further scaled-up to pilot plants. An overview of toxic metals sources, chemistry and toxicity, which are relevant aspects to understand and develop treatment techniques, is initially presented. The problem of water resources pollution by toxic metals and more specifically the participation of metal finishing industries in the environmental contamination are issues also covered. The current and potential decontamination methods are presented including a discussion of their advantages and drawbacks. The literature on biosorption was reviewed in detail, considering especially the ion exchange properties of cell wall constituents, such as alginate and fucoidan, and their role in metal sequestration. Besides that, a detailed description of biosorption process design, especially in continuous mode, and the application of mechanistic models is addressed.

Mycobacterium tuberculosis virulence is highly metal‐dependent with metal availability modulating the shift from the dormant to active states of M. tuberculosis infection. Rv0045c from M. tuberculosis is a proposed metabolic serine hydrolase whose folded stability is dependent on divalent metal concentration. Herein, we measured the divalent metal inhibition profile of the enzymatic activity of Rv0045c and found specific divalent transition metal cations (Cu(2+) ≥ Zn(2+) > Ni(2+) > Co(2+)) strongly inhibited its enzymatic activity. The metal cations bind allosterically, largely affecting values for k (cat) rather than K (M). Removal of the artificial N‐terminal 6xHis‐tag did not change the metal‐dependent inhibition, indicating that the allosteric inhibition site is native to Rv0045c. To isolate the site of this allosteric regulation in Rv0045c, the structures of Rv0045c were determined at 1.8 Å and 2.0 Å resolution in the presence and absence of Zn(2+) with each structure containing a previously unresolved dynamic loop spanning the binding pocket. Through the combination of structural analysis with and without zinc and targeted mutagenesis, this metal‐dependent inhibition was traced to multiple chelating residues (H202A/E204A) on a flexible loop, suggesting dynamic allosteric regulation of Rv0045c by divalent metals. Although serine hydrolases like Rv0045c are a large and diverse enzyme superfamily, this is the first structural confirmation of allosteric regulation of their enzymatic activity by divalent metals.