Search

A quick and solvent-free mechanochemical method was employed for the post-synthetic modification of a Ni-MOF. The Ni-MOF was utilized as an electrocatalyst for oxygen evolution and reduction, and biomass conversion applications.

The human gastrointestinal tract (GIT) is a well-recognized hub of microbial activities. The microbiota harboring the mucus layer of the GIT act as a defense against noxious substances, and pathogens including Clostridium difficile, Enterococcus faecium, Escherichia coli, Salmonella Typhimurium. Toxins, pathogens, and antibiotics perturb the commensal floral composition within the GIT. Imbalanced gut microbiota leads to dysbiosis, manifested as diseases ranging from obesity, diabetes, and cancer to reduced lifespan. Among the bacteria present in the gut microbiome, the most beneficial are those representing Firmicutes and Bacteroidetes. Recent studies have revealed the emergence of a novel biotherapeutic agent, Akkermansia, which is instrumental in regaining eubiosis and conferring various health benefits.

In this study, the medium requirements to increase the production of xylitol by using Candida tropicalis (CT) have been investigated. The technique of single addition or omission of medium components was applied to determine the nutritional requirements. The addition of amino acids such as Asp, Glu, Gln, Asn, Thr, and Gly had no significant effect on CT growth. However, in the absence of other metal ions, there was a higher concentration of cell growth and xylitol production when only Zn(2+) was present in the medium. The analysis of various vitamins unveiled that biotin and thiamine were the only vitamins required for the growth of CT. Surprisingly, when only biotin was present in the medium as a vitamin, there was less growth of CT than when the medium was complete, but the amount of xylitol released was significantly higher. Overall, this study will increase the xylitol production using the single omission or addtion technique.

Bioactive molecules of microbial origin are finding increasing biotechnological applications. Their sources range from the terrestrial, marine, and endophytic to the human microbiome. These biomolecules have unique chemical structures and related groups, which enable them to improve the efficiency of the bioprocesses. This review focuses on the applications of biomolecules in bioremediation, agriculture, food, pharmaceutical industries, and human health.

Herein, we disclose the synthesis of new D–π–A push–pull chromophores (10 examples; 2a–2j) by tethering tetracyanoquinodimethane (TCNQ) as an auxiliary group instead of previously reported tetracyanoethylene (TCNE). This molecular engineering strategy of incorporating TCNQ on the D–π–A backbone permits a much-extended optical absorption in the near-infra red region compared to TCNE derived analogues. The impact of a dicyanoquinodimethane (DCNQ) moiety on the optoelectronic and electrochemical properties was calculated and correlated with density functional theory/time-dependent density functional theory (DFT/TD-DFT) calculations. The computations revealed an appropriate optical band gap as well as energy levels of the highest occupied molecular orbital (HOMO) and lowest unoccupied molecular orbital (LUMO) matching the requirement of donor materials for organic solar cells (OSC). Bulk heterojunction (BHJ) solar cells by exploring the synthesized chromophores as donor components along with phenyl-C61-butyric acid methyl ester (PCBM) as the acceptor showed power conversion efficiencies ranging between 5.22 and 7.09%. This boosted device efficiency based on TCNQ chromophores compared to TCNE counterparts (1.95 to 3.33%) is ascribed to the favourable molecular structure of the former to contribute for extended light absorption, elevated HOMO energies and better molecular parameters. With respect to cell fabrication, the best performed donor 2j in a 1 : 1 blend ratio with PCBM seems to be optimal as it exhibits good interdigitated nanostructures and film quality. Processing the best blend (2j:PCBM-1 : 1 wt/wt) by solvent vapour annealing (SVA) results in better surface morphology, self-ordered structure and charge transport properties to enhance the efficiency up to 7.79%. Overall, this paper validates the influence of the TCNQ acceptor in controlling the physical properties of D–π–A dipolar chromophores for enhanced OSC performance and could inspire the logical selection of this acceptor as an approach to boost the photovoltaic efficiency.

Titanium dioxide-based systems are the preferred photo-catalytic materials. Among this the commercial P25 has been consistently employed for Photo-catalytic and PEC applications. This system ( ~20% Rutile and ~80% anatase) possibly crystallizes in a core shell configuration and the relevance of this. patterning for the observed photo-catalytic or Photo-electrochemical (PEC) activity is examined.

Conjugated chromophores possessing π-twisted functionality such as tetracyanobutadiene (TCBD) have emerged as promising active layer materials for organic photovoltaics (OPVs). In this study, we disclose the synthesis of two azulenyl chromophores containing one and two TCBD groups. The symmetrical and unsymmetrical structural characteristics of these molecules inflict dissimilar optoelectronic and electrochemical properties. Based on molar absorptivity, aggregation behavior, HOMO-LUMO energies and other quantum chemical parameters, the symmetrical molecule (TATC2) appears to be a better non-fullerene acceptor (NFA) compared to its unsymmetrical counterpart (TATC1). For instance, higher absorptivity and deeper HOMO-LUMO levels for TATC2 (23950 M-1 cm-1 ; -6.01 eV/-3.86 eV) over TATC1 (12200 M1 cm-1 ; -5.46 eV/-3.64 eV) was observed. Validating this structure-property relationship on solar cell prototypes exhibited higher photovoltaic parameters (VOC =0.54 V, FF=0.48, JSC =6.42 mA/cm2 ) for TATC2 than TATC1 (VOC =0.47 V, FF=0.38, JSC =5.77 mA/cm2 ). Though the device parameters are not high, this work uncovers the intrinsic properties of azulene-tethered twisted chromophores as potential π-semiconductor choice for NFA solar cells. In particular, this report explores the utility of azulene-based π-twisted semiconductors as acceptor material for OPVs with cell efficiencies of 1.70 and 1.04 % for TATC2 and TATC1 respectively.

Using Taguchi design of experiments (DoE), experiments were conducted with 3 factors and 3 levels. The factors were the depth of cut, spindle speed, and feed. The responses were surface roughness, flank wear, material removal rate, and spindle vibration along [Formula: see text] ([Formula: see text]), [Formula: see text] ([Formula: see text]), and [Formula: see text] ([Formula: see text]) axis. To convert the multi-response optimization problem into a single response optimization problem, the technique for order of preference by similarity to ideal solution (TOPSIS) was applied. The S/N of the closeness coefficients from TOPSIS was calculated and optimum machining conditions were obtained. Further, analysis of variance (ANOVA) was performed to verify which input parameter significantly affects the output responses. From TOPSIS optimization, the responses like surface roughness and flank wear were decreased by 0.99% and 2.55%. The vibration in [Formula: see text], [Formula: see text], and [Formula: see text]-axis decreased by 3.84%, 16.87% and 12.48% respectively. This optimization significantly enhances the machining characteristics.

Three new π-conjugated semiconductors of the type D–π–D, A–π–A (symmetric), and D–π–A (asymmetric) were constructed on fluoreno-thiophene spacer by permutation of the lateral groups such as diphenylaminostyryl and dicyanovinyl as electron donor (D) and acceptor (A), respectively. The influence of the asymmetric push–pull effect (as in D–π–A) on the optical as well as the electrochemical properties has been evaluated and compared with the symmetrical D–π–D and A–π–A systems. Theoretical investigation of the molecular properties using DFT/TD-DFT calculations was found to be in good agreement with the experimental results. The chromophore with an asymmetric push–pull architecture emerged as a better candidate for organic solar cell fabrication in terms of its optical band gap, HOMO–LUMO energy level, surface morphology, crystallinity, and charge carrier mobility. The photovoltaic performance of the synthesized chromophores in the bulk heterojunction solar cells revealed a power conversion efficiency of 2.01% for the asymmetric chromophore (D–π–A), which is better than the symmetrical counterparts (D–π–D and A–π–A). Overall, this work demonstrates the impact of symmetric and asymmetric push–pull switch within the fluoreno-thiophene π-molecular backbone on the modulation of the optoelectronic properties.

We report direct overall pure water splitting by visible light excited graphitic carbon nitride incorporated with conjugated aromatic rings without using sacrificial agents. We fabricated modified graphitic carbon nitride polymer samples by copolymerization of melamine with 2,4,6-triaminopyrimidine and 1,3,5-triaminobenzene, containing few-carbon (pyrimidine) to all-carbon (benzene) aromatic rings. Solid state 13C NMR shows that the core molecular skeleton of g-C3N4 remained intact even after the incorporation of benzene and pyrimidine aromatic rings into the g-C3N4 chemical structure. Upon substitution of benzene aromatic rings in the place of triazine rings, the optical band gap energy of g-C3N4 is reduced down from 2.8 eV to 2.1 eV with negative shifts of valence and conduction bands due to the formation of defects like nitrogen vacancies. DFT calculations predict that the benzene doped carbon nitride polymer has localized charge densities over valence band maxima and conduction band minima in different parts of heptazine rings, which assist in reducing the recombination rate of the charge carriers. The benzene ring incorporated carbon nitride photoelectrode shows higher photocurrent with less charge transfer resistance than the parent g-C3N4 and pyrimidine doped g-C3N4 polymers. This demonstrates the importance of the extended conjugation in g-C3N4 due to the presence of aromatic benzene rings. This is further corroborated by photoluminescence and electron paramagnetic resonance measurements. As a result, the benzene ring incorporated carbon nitride is more active than the pyrimidine ring incorporated carbon nitride for solar water splitting. The benzene ring incorporated carbon nitride polymer directly splits water and generates about 7 μmol h−1 of hydrogen with an apparent quantum yield of 1.6% at 450 nm in the absence of sacrificial reagents, achieving a turnover number of 1.6.

FTIR spectroscopic studies has been carried out on pure toluene (TOL), propionitrile (PN) and their equimolar binary solution at room temperature. DFT calculations (using B3LYP functional with the Grimme's dispersion correction D3 and ωB97XD with the D2 version of Grimme's dispersion) have also been carried out on PN dimers and various TOL-BN heteroassociated networks that are supposed to exist in neat PN and binary solution, respectively, on the basis of the shifts suffered by the fundamental absorptions of TOL and PN upon mixing with each other. Formation of ( m e t h y l ) C − H ⋯ N ≡ C and ( m e t h y l e n e ) C − H ⋯ N ≡ C hydrogen bonded dimers in neat PN has been identified. The dominant interaction forces that stabilize the 1:2 (TOL: PN) complex formed in the binary solution are ( T O L m e t h y l ) C − H ⋯ N ≡ C and ( T O L r i n g ) C − H ⋯ N ≡ C intermolecular H-bonds.

Enhanced covalent immobilization of xylanase from Chaetomium globosum (XylCg) onto SiO2 nanoparticles was achieved by the modification of surface residues. The mutation of surface residues to lysine by site-directed mutagenesis increased the immobilization efficiency (IE) and immobilization yield (IY). The immobilized mutant XylCg (N172K-H173K-S176K-K133A-K148A) exhibited an IY of 99.5% and IE of 135%, which were 1.8- and 4.3-fold higher than immobilized wildtype (WT). Regarding the catalytic properties, the kcat and kcat/Km values were 1850 s−1 and 2030 mL mg−1 s−1 for the immobilized mutant, and 331 s−1 and 404 mL mg−1 s−1 for the immobilized WT, respectively. Additionally, the immobilized mutant exhibited four times higher thermal stability than the immobilized WT at 60 °C. These results suggest that surface-mutated lysine residues confer good stability and orientation on the support matrix, thus improving the overall performance of xylanase.

Metal oxides have been used as supports and promoters to enhance the electrocatalytic activity of Pt/C for methanol oxidation reaction (MOR). In this work, Gd2O3 prepared by simple precipitation method (Gd2O3(PC)) and polymer-assisted method (Gd2O3(PL)) is examined as support for Pt/C. The Gd2O3 samples are characterized by FTIR, HR-SEM, and PXRD. The ease of surface oxygen exchange and formation of surface –OH groups are better in the case of Gd2O3(PC) for MOR activity. The microwave-assisted polyol reflux method is used to prepare Pt-Gd2O3(PC)/C and Pt-Gd2O3(PL)/C) electrocatalysts. Electrocatalysts are characterized by XPS, ICP, TEM, PXRD, and examined by cyclic voltammetry (CV), CO stripping experiments, chronopotentiometry (CP), and chronoamperometry (CA) in acidic media. The MOR activity of Pt-Gd2O3(PC)/C is found to be 2.8 times higher than commercial Pt/C with good anti-poisoning activity. This result is further corroborated by the first principle calculations which show that there is significant electron transfer from Pt/Gd2O3 to adsorbed CO. This electron transfer reduces the Gibbs free energy for CO adsorption and decreases the CO poisoning. The overall benefit of Gd2O3 is to increase the performance of Pt electrocatalyst for methanol oxidation.

Plastics are an integral part of most of the daily requirements. Indiscriminate usage and disposal have led to the accumulation of massive quantities of waste. Their non-biodegradable nature makes it increasingly difficult to manage and dispose them. To counter this impending disaster, biodegradable polymers, especially polyhydroxy-alkanoates (PHAs), have been envisaged as potential alternatives. Owing to their unique physicochemical characteristics, PHAs are gaining importance for versatile applications in the agricultural and medical sectors. Applications in the medical sector are more promising because of their commercial viability and sustainability. Despite such potential, their production and commercialization are significant challenges. The major limitations are their poor mechanical strength, production in small quantities, costly feed, and lack of facilities for industrial production. This article provides an overview of the contemporary progress in the field, to attract researchers and stakeholders to further exploit these renewable resources to produce biodegradable plastics on a commercial scale.

The hybrid molecular materials [Fe(C5H5)2]3[PW12O40]·(H2O)4 and [Fe(C5H5)2]3[PMo12O40]·(H2O)6, denoted respectively as FcPW and FcPMo, are synthesized via a co-precipitation method under acidic conditions (pH: ∼2–3). The molecular properties of these compounds are investigated via various analytical methods. UV-vis diffuse reflectance and photoluminescence studies confirm that these compounds are charge-transfer salts. Stainless steel plates (SS, 316 grade) coated with these hybrid compounds and dipped in 0.5 M H2SO4 and Ringer's solutions show significantly inhibited corrosion. The corrosion inhibition properties of these materials are studied via weight loss, electrochemical impedance spectroscopy, and potentiodynamic polarization studies. The reproducibility of the corrosion inhibition results is ensured via repeat measurements, and error values are reported. The surfaces of the corroded steel plates are examined via scanning electron and atomic force microscopy techniques. It is found that the corrosion is of uniform type. The Tafel extrapolation method shows that the inhibition efficiency is 74% for SS@FcPMo and 65% for SS@FcPW. The corrosion inhibition mechanism is explained based on the redox nature of the hybrid materials. The experimental results are corroborated through computational studies carried out using a first principles approach with the optimized geometries and frontier molecular orbitals of the hybrid molecular materials.

Type I (Methylomicrobium album) and II (Methyloferula stellata) methanotrophs were encapsulated by alginate and polyvinyl alcohol (PVA) to improve methanol production from simulated biogas [methane (CH4) and carbon dioxide (CO2)] in the presence of CH4 vector. Polymeric matrix alginate (2%) and PVA (10%) were found to be optimum for the immobilization of both the methanotrophs, with a relative efficiency of methanol production up to 80.6 and 88.7%, respectively. The stability of methanol production by immobilized cells was improved up to 13.2-fold under repeated batch-culture over free cells. The addition of CH4 vectors showed 1.7-fold higher methanol production on using simulated biogas than in the control. The maximum methanol production of 7.46 and 7.14 mmol/L was noted for PVA-encapsulated M. album and M. stellata, respectively. This study successfully established the beneficial effects of CH4 vectors on methanol production by methanotrophs from greenhouse gases that can be applied for real biogas feedstock.

Neutral phosphine oxide (P[double bond, length as m-dash]O) donor-based organometallic complexes [{Re(CO)3O[double bond, length as m-dash]PCy3}{μ-DHBQ}{Re(CO)3O[double bond, length as m-dash]PCy3}] (1), [{Re(CO)3O[double bond, length as m-dash]PPh3}{μ-DHBQ}{Re(CO)3O[double bond, length as m-dash]PPh3}] (2), [{Re(CO)3O[double bond, length as m-dash]PCy3}{μ-THQ}{Re(CO)3O[double bond, length as m-dash]PCy3}] (3), [{Re(CO)3O[double bond, length as m-dash]PPh3}{μ-THQ}{Re(CO)3O[double bond, length as m-dash]PPh3}] (4), [{Re(CO)3O[double bond, length as m-dash]PCy3}{μ-CA}{Re(CO)3O[double bond, length as m-dash]PCy3}] (5), and [{Re(CO)3O[double bond, length as m-dash]PPh3}{μ-CA}{Re(CO)3O[double bond, length as m-dash]PPh3}] (6) were assembled from phosphine/phosphine oxide, a dihydroxybenzoquinone donor and Re2(CO)10via a one-pot solvothermal approach. The soft phosphine donor was transformed into a hard phosphine oxide donor during the formation of 1, 3, 4, 5, and 6. The complexes 1-6 were air and moisture stable and were soluble in polar organic solvents. The complexes were characterized by elemental analysis, FT-IR, and NMR spectroscopic methods. The molecular structures of 1, 2, 4, and 6 were analyzed by single-crystal X-ray diffraction analysis. The UV-Visible absorption studies indicated that 1-6 in THF display strong visible light absorption in the range of ∼350-700 nm.

In the present study strontium oxide/graphitic carbon nitride (SrO 2 /g-C 3 N 4 ) nanohybrids was successfully synthesized by a facile simple dry synthesis and used for the photocatalytic degradation of organic contaminants for the very first time. The SrO 2 /g-C 3 N 4 nanohybridsare having a superior crystallinity and crystallite size was ∼7.1 nm. The photodegradation efficiency of nanohybrids was tested on the degradation of RhB dye solution under visible light irradiation. The SrO 2 /g-C 3 N 4 nanohybrids exhibited excellent photocatalytic activity, which may be attributed to the improved charge separation and complete degradation of the dye solution is achieved within 60 min. Moreover, the synthesized nanohybrids exhibited a good stability towards the photodegradation of RhB dye. Finally, the possible mechanism for the charge separation in thephoto degradationprocess wasexplored. Therefore, the nanohybrids are possessing potential interest in waste water treatment and environmental remediation under visible light irradiation.

FTIR spectra of neat acetonitrile (AN), dimethyl sulphoxide (DMSO) and their binary solutions at various mole fractions have been recorded at room temperature. Theoretical calculations have also been carried out on acetonitrile (monomer, dimer), dimethyl sulphoxide (monomer, dimer) and AN – DMSO complex molecules. 1:2 (AN:DMSO) and 2:1 complexation through the red shifting ( A N ) C − H ⋯ O = S ( D M S O ) and blue shifting ( D M S O ) C − H ⋯ N ≡ C ( A N ) hydrogen bonds has been identified. The experimental and theoretical studies favour the presence of both the monomer and dimer in liquid AN, but only closed dimers in DMSO. The dipole-dipole interactions existed in AN and DMSO dimers disappear in the complex molecules. Partial π bond between S and O atoms, and three lone pair of electrons on oxygen atom of DMSO have been noticed theoretically.

Dielectric studies using Time Domain Reflectometry method has been carried out on the binary solution of Ethyl acetate (EA) with Chlorobenzene (CBZ) over the entire composition range. Spectroscopic (FTIR and 13C NMR) signatures of neat EA, CBZ and their equimolar binary solution have also been recorded. The results of the spectroscopic studies favour the presence of (CBZ) C H ⋯ O C (EA), (EA) methylene C H ⋯ π electrons (CBZ) and (EA) methyl C H ⋯ Cl (CBZ) contacts which have been validated using quantum chemical calculations. Dimerization of CBZ has been identified. Presence of β-clusters has been identified in all the solutions. Although EA and CBZ molecules have nearly equal molar volumes, CBZ molecules experience larger hindrance for the rotation than EA molecules. Very small excess dielectric constant (eE) values may be correlated with weak heteromolecular forces and/or closed heteromolecular association.

FTIR spectra of neat acetone, ethanol and their binary solutions at the molar ratios 0.2:0.8 (ethanol: acetone), 0.4:0.6, 0.6:0.4 and 0.8:0.2 have been recorded at room temperature. Theoretical calculations have also been made on acetone (monomer and dimer), ethanol monomer, dimer, trimer, tetramer, pentamer, hexamer and ethanol - acetone complex molecules. 4:1 (ethanol:acetone), 5:1 and 6:2 complexation through the classical C O⋯H O and (acetone) C H⋯O C(ethanol ) hydrogen bonds has been identified. Ethanol rich solutions may consist of ethanol multimers such as tetramer, pentamer and hexamer along with 4:1, 5:1 and 6:2 complex molecules depending upon ethanol concentration. Acetone seems to exist as a mixture of monomer and dimer.

Metal cluster, at sub-nanometer level has a unique property in the activation of small molecules, in contrast to that of bulk surface. In the present work, singly exposed active site of copper metal cluster at sub-nanometer level was designed to arrive at the energy minimised configurations, binding energy, electrostatic potential map, frontier molecular orbitals and partial density of states. The ab initio molecular dynamics was carried out to probe the catalytic nature of the cluster. Further, the stability of the metal cluster and its catalytic activity in the electrochemical reduction of CO 2 to CO were evaluated by means of computational hydrogen electrode via calculation of the free energy profile using DFT/B3LYP level of theory in vacuum. The activity of the cluster is ascertained from the fact that the copper atom, present in a two coordinative environment, performs a more selective conversion of CO 2 to CO at an applied potential of −0.35 V which is comparatively lower than that of higher coordinative sites. The present study helps to design any sub-nano level metal catalyst for electrochemical reduction of CO2 to various value added chemicals.

β-Glucosidases (BGL) are key members of the cellulase enzyme complex that determine efficiency of lignocellulosic biomass degradation, which have shown great functional importance to many biotechnological systems. A previous reported BGL from Neosartorya fischeri (NfBGL) showed much higher activity than other BGLs. Screening the important residues based on sequence alignment, analyzing a homology model, and subsequent alteration of individually screened residues by site-directed mutagenesis were carried out to investigate the molecular determinants of the enzyme's high catalytic efficiency. Tyr320, located in the wild-type NfBGL substrate-binding pocket was identified as crucial to the catalytic function of NfBGL. The replacement of Tyr320 with aromatic amino acids did not significantly alter the catalytic efficiency towards p-nitrophenyl β-d-glucopyranoside (pNPG). However, mutants with charged and hydrophilic amino acids showed almost no activity towards pNPG. Computational studies suggested that an aromatic acid is required at position 320 in NfBGL to stabilize the enzyme-substrate complex formation. This knowledge on the mechanism of action of the molecular determinants can also help rational protein engineering of BGLs.

The production of food is an intensive source of environmental impact. In aquaculture, one source of impact is solid waste, which contains high concentrations of minerals, other nutrients, and metals. The larvae of Hermetia illucens are capable of consuming this material, but applying technology that is based on these larvae for managing waste streams, like those from aquaculture, requires careful examination of safety risks. A study is performed examining the growth performance of larvae that were fed on solid aquaculture waste. Subsequently, a thorough analysis of safety risks from inorganics, with detailed the results on microelements that have previously received little attention in the literature, is performed to serve as a guideline for how to assess the safety of waste streams such as these. Findings confirm existing results in the literature that Cd is bioaccumulative, but also that other elements, including Hg, Mn, and especially K, are bioaccumulative. To the authors&rsquo, knowledge, this is the first research where the accumulation of Ag is also tested. The results of these tests are explained within the context of regulations in various countries where Hermetia illucens is cultivated, serving as a reference for practitioners to rigorously screen out high risk feed streams that they may consider using as feed sources. It is intended that these references and the demonstrated accumulation of a range of elements motivate comprehensive industry safety practices when evaluating new feed sources.