Unveiling therapeutic efficacy of extract and multi-targeting phytocompounds from Christella dentata (Forssk.) Brownsey & Jermy against multidrug-resistant Pseudomonas aeruginosa.

Christella dentata (Forssk.) Brownsey & Jermy has been commonly used in traditional medicinal practices but its effects on multi-drug-resistant (MDR) bacteria have remained unexplored. We aimed to assess the in vitro antibacterial potential of the ethanol extract of Christella dentata (EECD) against MDR Pseudomonas aeruginosa and to identify potential multi-targeting antibacterial phytocompounds through computer-aided drug design focusing on the LasR and LpxC proteins. PPS, FT-IR and GC-MS were used for profiling of the phytocompounds in EECD. The antimicrobial activity of EECD was assessed using in vitro agar well diffusion, disc diffusion, MIC and MBC. Computer-aided drug design was used to identify multi-targeting leads from GC-MS-annotated phytocompounds. EECD exhibited dose-dependent antibacterial activity and revealed the presence of 51 phytocompounds in GC-MS analysis. Among these, three phytocompounds; (2E,4E)-N-isobutylhexadeca-2,4-dienamide (CID 6442402), bicyclo[4.3.0]nonane, 2,2,6,7-tetramethyl-7-hydroxy- (CID 536446) and 1,4-diethylbenzene (CID 7734) were identified as promising antibacterial phytocompounds as they strongly bonded with LasR and LpxC. Of them, CID 536446 and CID 7734 exhibited multiple targeting abilities with LasR and LpxC. On further screening, both CID 536446 and CID 7734 exhibited favorable drug-able, pharmacokinetics and toxicity properties. Finally, molecular dynamics (MD) simulation proved the binding stability of bicyclo[4.3.0]nonane, 2,2,6,7-tetramethyl-7-hydroxy- and 1,4-diethylbenzene to active pockets of LasR and LpxC. The results of this study offer scientific validation for the traditional use of Christella dentata in bacterial infection-related diseases. It also suggests that bicyclo[4.3.0]nonane, 2,2,6,7-tetramethyl-7-hydroxy- and 1,4-diethylbenzene from Christella dentata might be responsible for the antibacterial activity and could act as phytopharmacological leads for the development of LasR and LpxC inhibitors against MDR P. aeruginosa.

Natural defense against multi-drug resistant Pseudomonas aeruginosa: Cassia occidentalis L. in vitro and in silico antibacterial activity.

Cassia occidentalis L. is widely used in indigenous and traditional medicine, but its impact on multi-drug resistant (MDR) bacterial infections mostly remains unknown. Therefore, this study aimed to evaluate the in vitro antibacterial efficiency of methanol and ethyl acetate extracts of C. occidentalis L. leaves (MECOL and EAECOL) against multi-drug resistant Pseudomonas aeruginosa and to identify potential antibacterial agents through computational studies targeting the LasR protein. Initially, 82 compounds were identified using GC-MS analysis, and the functional groups were determined through FT-IR analysis. Both extracts of the plant exhibited dose-dependent antibacterial activity, with MICs of 104.16 ± 36.08 µg mL-1 for MECOL and 83.33 ± 36.08 µg mL-1 for EAECOL, and an MBC of 125 µg mL-1. Among the 82 compounds, 12 potential compounds were identified based on binding scores using molecular docking with the LasR protein and MM-GBSA analysis. Furthermore, screening for ADME properties, including physicochemical features, water solubility, lipophilicity, RO5 compliance, and toxicity, identified the top three compounds: methyl dihydrojasmonate, methyl benzoate, and 4a-methyl-4,4a,5,6,7,8-hexahydro-2(3H)-naphthalenone, which also demonstrated binding affinity with the active site residues of the LpxC protein of the bacteria. Additionally, molecular dynamics (MD) simulations confirmed the binding reliability of these three phytochemicals to LasR's active pocket, comparable to the protein native inhibitory ligands (C12-HSL). The study offers scientific support for the traditional use of C. occidentalis in treating bacterial infections, highlighting the potential of the three compounds as leads for developing LasR inhibitors to combat multi-drug resistant P. aeruginosa.

Correction: SARS-CoV-2 suppression depending on the pH of graphene oxide nanosheets.

[This corrects the article DOI: 10.1039/D3NA00084B.].

Climate Change, Ecological Modernization, and Disaster Management: The Coastal Embankment Project in Southwestern Bangladesh.

Climate change, one of the severest environmental threats to humankind, disproportionately affects low-income, developing countries in the Global South. Having no feasible mitigation alternatives, these countries resort to adaptation efforts to address climate perturbations. Climate change adaptation (or resilience) is primarily a localized course of action that depends on individuals, social networks, economies, ecologies, political structures, and the capabilities of all those to work collectively to absorb, learn from, and transform in the face of new realities. With a view to controlling the floods that shattered the life and economy of the then East Pakistan, which is now Bangladesh, during the mid-twentieth century, the coastal embankment project (CEP) was instituted as an adaptation strategy to natural disasters in Southwestern Bangladesh. Based on a qualitative analysis of primary and secondary data, this paper seeks to critically evaluate the efficacy of the CEP in terms of the space for feasible action and ecological modernization. The findings of this research indicate that the CEP has become an unrealistic venture that hinders the growing economic activity of shrimp aquaculture in the area. This paper is expected to contribute to generating further theoretical and empirical discourse on the evaluation of similar development projects around the globe.

Thermally stable proton conductivity from nanodiamond oxide.

Herein, we report nanodiamond oxide (NDOx), obtained from modified Hummers' oxidation of nanodiamond (ND), showing excellent proton conductivity and thermal stability. NDOx possesses hydrophilicity resulting in higher water adsorption and the retention of functional groups at elevated temperatures can be attributed to the high proton conductivity and thermal stability, respectively.

SARS-CoV-2 suppression depending on the pH of graphene oxide nanosheets.

Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) inactivation of pH-dependent graphene oxide (GO) nanosheets is presented. The observed virus inactivation using an authentic virus (Delta variant) and different GO dispersions at pH 3, 7, and 11 suggests that the higher pH of the GO dispersion yields a better performance compared to that of GO at neutral or lower pH. The current findings can be ascribed to the pH-driven functional group change and the overall charge of GO, favorable for the attachment between GO nanosheets and virus particles.

Development and validation of a modified QuEChERS method coupled with LC-MS/MS for simultaneous determination of difenoconazole, dimethoate, pymetrozine, and chlorantraniliprole in brinjal collected from fields and markets places to assess human health risk.

An effective and sensitive analytical method was developed to quantify the most common pesticide residues (difenoconazole, dimethoate, pymetrozine, and chlorantraniliprole) used for brinjal cultivation in Bangladesh. The quantification of the analytes was done using liquid chromatography-tandem mass spectrometry (LC-MS/MS). The samples were extracted using a modified QuEChERS method and followed by purification with dispersive solid phase extraction (d-SPE) sorbents (PSA, GCB, and C18). Matrix-matched calibration with a regression coefficient R2 ≥ 0.9964 were used to minimize the brinjal matrix effect. The method was validated in quintuple (n = 5) at five different spiked levels (8-400 µg/kg) having recoveries in the range of 70.3-113.2% with relative standard deviations RSDs ≤6.8%, limits of detection (LOD) and limits of quantification (LOQ) was in the range of 0.15-0.66 µg/kg and 0.4-2.0 µg/kg, respectively, for the four analytes. A total 100 samples (50 samples directly from fields of Jessore district, Bangladesh and 50 samples from local market of Dhaka, Bangladesh) were collected to analyse the pesticides residue. The result showed that pesticides residue was found in both the field and market collected samples, 54% and 38%, respectively. The overall mean residue levels of four pesticides in field samples were significantly higher than those of market samples. Moreover, 20% of the field samples and 10% of the market samples had dimethoate residues, which were the most abundant among the four analytes and it ranged from 0.017 to 0.252 mg/kg. In terms of health risk assessments, dimethoate showed the highest estimated daily intake (EDI) and hazard quotient (HQ) values that are 3.02 × 10-5 mg/kg/day and 1.51%, respectively, in field samples. Till now, there have been no regulations or guidelines for the maximum admissible pesticide residue in Bangladesh. Therefore, the above findings will be an initial step for the regulatory authorities of Bangladesh to implement regulations and guidelines for pesticide usage.

Enhanced mixed proton and electron conductor at room temperature from chemically modified single-wall carbon nanotubes.

Remarkably high mixed proton and electron conduction arising from oxidized single-wall carbon nanotubes at room temperature is demonstrated. The respective proton and electronic conductivities are 1.40 and 8.0 × 10-2 S cm-1 in the in-plane direction, and 3.1 × 10-2 and 1.1 × 10-3 S cm-1 in the out-of-plane direction, indicating their potential in a wide range of solid electrolyte membranes.

High Proton Conductivity of 3D Graphene Oxide Intercalated with Aromatic Sulfonic Acids.

The development of efficient proton conductors that are capable of high power density, sufficient mechanical strength, and reduced gas permeability is challenging. Herein, we report the development of a series of aromatic sulfonic acid/graphene oxide hybrid membranes incorporating benzene sulfonic acid (BS), naphthalene sulfonic acid (NS), naphthalene disulfonic acid (DS) or pyrene sulfonic acid (PS) using a facile freeze dried method. For out-of-plane proton conductivity, the 3DGO-BS and 3DGO-NS yielded proton conductivities of 4.4×10-2  S cm-1 and 3.1×10-2  S cm-1 , respectively; this represents a two-times higher value than that which occurs for three dimensional graphene oxide (3DGO). Additionally, the respective prepared films as membranes in a proton exchange membrane fuel cell (PEMFC) show maximum power density of 98.76 mW cm-2 for 3DGO-NS while it is 92.75 mW cm-2 for 3DGO-BS which are close to double that obtained for 3DGO (50 mW cm-2 ).

Engineering ferromagnetism in Ni(OH)2 nanosheets using tunable uniaxial pressure in graphene oxide/reduced graphene oxide.

The interlayer spaces in two dimensional (2D) layered materials such as graphene, metal oxides and metal chalcogenides can be used in a number of roles that include the trapping of gases, for ion transfer and for water purification applications. In such spaces, "inner" pressure occurs on guest species enclosed between the layers and its variation can, in principal, be used for precisely controlling particular guest properties. In this study, a mixture of two 2D materials including graphene oxide (GO) and nickel hydroxide (Ni(OH)2), was employed to yield an anisotropic GO-Ni(OH)2 hybrid 2D sheet. The inner pressure associated with this material was able to be tuned by reduction of the GO (to yield rGO) and this in turn was shown to affect the magnetic behaviour of Ni(OH)2. The ferromagnetic transition temperature (Tc) for Ni(OH)2 decreases as the interlayer distance became shorter, which is opposite to the behaviour observed for the application of hydrostatic pressure to the hybrid sheet. The uniaxial pressure affecting the interlayer of the 2D material, and generated by the reduction of GO to rGO, has the potential to not only influence the behaviour of a range of magnetic materials, but also individual properties of other types of functional materials.

Encapsulation and controlled release of an antimalarial drug using surface functionalized mesoporous silica nanocarriers.

Herein, we report the encapsulation and release of antimalarial drug quinine (QN) using three nanocarriers, including MCM-41 (1), and its 3-aminopropyl silane (aMCM-41 (2)) and 3-phenylpropyl silane (pMCM-41 (3)) surface functionalized derivatives. The pH and thermal optimization effects on QN adsorption and release from 1, 2 and 3 were investigated.

Enhanced γ-phase crystallinity of Al2O3 frameworks at the concave surface of PS-b-PEO templated spherical pores.

The crystallinity of inorganic solids like metal oxides after the porosity design is the crucial factor that should be investigated for enhancing their physicochemical properties. In most cases, metal oxide frameworks around mesopores, that are designed through the supramolecular mediated approach, are resulted to be amorphous. Accordingly, a rational guideline has been required for enhancing the crystallinity of frameworks at such concave surfaces. We have so far surveyed a crystallization behavior of alumina (Al2O3) frameworks to its γ-phase around spherical mesopores (∼40 nm) and discussed further transition to the α-phase around much larger pores (∼200 nm). In this paper, we prepared new and helpful Al2O3 powders having PS-b-PEO templated pores (∼25 nm and ∼75 nm) smaller than those of our previous case. After careful discussion of the pore size variation by considering the molecular structure of PS-b-PEO, we explained the crystallization behavior of the Al2O3 frameworks to enhance its γ-crystallinity. This knowledge is quite beneficial for designing highly porous Al2O3 powders with abundant crystallinity for use as catalyst supports, which is very useful for assessing synthetic procedures of other mesoporous metal oxides having high crystallinity.

3D porous Ni/NiOx as a bifunctional oxygen electrocatalyst derived from freeze-dried Ni(OH)2.

Bifunctional electrocatalytic properties of freeze-dried Ni/NiOx, freeze-dried NiO, and freeze-dried Ni(OH)2 are reported. Freeze-dried Ni(OH)2 was synthesized by the freeze-drying method. Freeze-dried Ni/NiOx and freeze-dried Ni were obtained from the thermal annealing of the material. Both Ni(OH)2 and Ni/NiOx could sustain with freestanding freeze-dried 3D structures without any carbon support. Freeze-dried Ni/NiOx exhibited excellent bifunctional electrocatalytic properties with the ORR performance at 0.62 V (half-wave potential) and OER at 1.47 V (η = 10 mA cm-2). Using freeze-dried metal hydroxides can be considered useful in a wide range of carbon-free applications and can improve the electrocatalytic performance. The bifunctional catalytic activities were calculated to be 0.86, 0.98 and 1.14 V for freeze-dried Ni/NiOx, freeze-dried NiO and freeze-dried Ni(OH)2, respectively. The stacking of 2D sheets into 3D mass seemed to play a vital role behind this excellent bifunctionality of freeze-dried Ni/NiOx. The material reveals possible applications in Zn-air batteries. Besides, the strategy developed herein could be justified to obtain other transition metal-oriented bifunctional electrocatalysts as alternatives to Pt- and Ir/Ru-based expensive benchmark catalysts.

Microwave aided conversion of cellulose to glucose using polyoxometalate as catalyst.

The viability of biorefining technology primarily depends on the facile cellulose conversion route with adequate conversion efficiency. Here we have demonstrated the microwave-assisted hydrolysis of cellulose to glucose using polyoxometalate (POM) clusters as acid catalysts. Two different types of POM, including Wells-Dawson and Keggin were justified as catalysts in the cellulose conversion process. In particular, the cellulose to glucose catalytic conversion using Wells-Dawson type POMs has not been reported to date. Also, even though there have been some previous reports about the catalytic biomass conversion of Keggin type POMs, the systematic study to optimize the conversion efficiency in terms of catalyst amount, reaction temperature, reaction time, and the amount of solvent is lacking. Under the experimental conditions employed, the Keggin-type catalyst showed higher cellulose conversion and glucose yield than the Wells-Dawson-type catalyst. Furthermore, the cellulose conversion efficiency and glucose yields were optimized by tuning the reaction conditions including temperature, reaction time, and the amount of solvent. Under optimized conditions, the Keggin-type POM catalyst shows a remarkably high glucose yield of 77.2% and a cellulose conversion of 90.1%. The unique complex properties of the POM catalyst, including being (i) strong acids with extremely high Brønsted and Lewis acidity and (ii) efficient microwave adsorbants which enhanced interaction between substrate and the catalyst can be attributed to the outstanding efficacy of the conversion process.

Microwave-assisted catalytic conversion of chitin to 5-hydroxymethylfurfural using polyoxometalate as catalyst.

The key challenges for converting chitin to 5-hydroxymethylfurfural (5-HMF) include the low 5-HMF yield. Moreover, the disadvantages of traditional acid-base catalysts including complex post-treatment processes, the production of by-products, and severe equipment corrosion also largely limit the large-scale conversion of chitin to 5-HMF. In this view, herein we have demonstrated a microwave aided efficient and green conversion of chitin to 5-HMF while using polyoxometalate (POM) as a catalyst and DMSO/water as solvent. Chitin treated with H2SO4 followed by ball-milling (chitin-H2SO4-BM) was selected as the starting compound for the conversion process. Four different POMs including H3[PW12O40], H3[PMo12O40], H4[SiW12O40] and H4[SiMo12O40] were used as catalysts. Various reaction parameters including reaction temperature, amount of catalyst, mass ratios of water/DMSO and reaction time have been investigated to optimize the 5-HMF conversion. The H4[SiW12O40] catalyst exhibited the highest catalytic performance with 23.1% HMF yield at optimum operating conditions which is the highest among the literature for converting chitin to 5-HMF. Significantly, the disadvantages of the state of the art conversion routes described earlier can be overcome using POM-based catalysts, which makes the process more attractive to meet the ever-increasing energy demands, in addition to helping consume crustacean waste.

Ion conduction switching between H+ and OH- induced by pH in graphene oxide.

Ion conduction through graphene oxide (GO) nanosheets that is pH-switchable between H+ (in acid) and OH- (in base) ions is demonstrated. This finding is the first observation of this type for ion conductive materials and demonstrates an example of stimuli-driven ion-conduction switching.

Neuroprotective function of Omi to α-synuclein-induced neurotoxicity.

The main pathological hallmark of Parkinson's disease (PD) is the presence of Lewy bodies, which mainly consist of aggregated α-synuclein. Based on the neurotoxicity of oligomeric α-synuclein and its significance in the aetiology of PD, there has been decades of effort to elucidate an enzyme specifically degrading oligomeric α-synuclein. Here we report an enzyme, Omi, which specifically recognizes and precisely degrades oligomeric α-synuclein but not monomeric α-synuclein. After enzymatic and functional analyses of Omi in in vitro, we developed an in vivo assay system of dual gene interaction in Drosophila to investigate further the etiological role of Omi in PD. Pan-neuronal expression of Omi rescued Parkinsonism in a Drosophila model of PD, while Knockout of Omi exacerbated Parkinsonism. Expression of Omi counteracted the α-synuclein-induced retinal degeneration, providing additional evidence for Omi's protective role oligomeric α-synuclein. This work reports identification of the catabolic pathway of oligomeric α-synuclein as well as showing how Omi functions as the key molecule in the recognition and degradation of toxic oligomeric α-synuclein, a possible cause of neurodegeneration in PD, without affecting monomeric α-synuclein which is a native essential molecule for the normal function of neurons.

Effect of the Resveratrol Rice DJ526 on Longevity.

Resveratrol is the best-known chemical for extending the lifespan of various organisms. Extensive recent research has shown that resveratrol can extend the lifespan of single-celled organisms, but its effects on the extension of animal lifespans are marginal. Despite the limited efficacy of pure resveratrol, resveratrol with the endogenous property of the DJ rice in the resveratrol rice DJ526 previously showed profound health benefits. Here, we report that the resveratrol rice DJ526 markedly extended the lifespan of the fruit fly Drosophila melanogaster by as much as 41.4% compared to that of the control. The resveratrol rice DJ526 also improved age-related symptoms such as locomotive deterioration, body weight gain, eye degeneration and neurodegeneration in D. melanogaster upon aging. This result shows the most significantly improved lifespan in animal experiments to date, meaning that the resveratrol rice DJ526 will assist in the development of a therapeutic agent for longevity or addressing age-related degeneration.

Perception of Climate Change in Shrimp-Farming Communities in Bangladesh: A Critical Assessment.

Local contexts as well as levels of exposure play a substantial role in defining a community's perception of climate and environmental vulnerabilities. In order to assess a community's adaptation strategies, understanding of how different groups in that community comprehend climate change is crucial. Public risk perception is important as it can induce or confine political, economic, and social actions dealing with particular hazards. Climate change adaptation is a well-established policy discourse in Bangladesh that has made its people more or less aware of it. Similarly, shrimp-farming communities in southwestern Bangladesh understand environmental and climate change in their own ways. In order to understand how the shrimp-farming communities in coastal Bangladesh perceive current climate instabilities, we conducted a qualitative study in shrimp-farming villages in coastal Bangladesh where about 80% of commercial shrimp of the country is cultivated. We compared farmers' perceptions of local climate change with existing scientific knowledge and found remarkable similarities. Our assessment shows that at least two factors are critical for this outcome: coastal people's exposure to and experience of frequent climate extremes; and a radical approach to defining climate regimes in Bangladesh by various stakeholders and the media, depicting anthropogenic global warming as a certainty for the country. Thus, a convergence of scientific construct and sociocultural construct construes the level of awareness of the general public about climate change.

Super Dielectric Materials of Two-Dimensional TiO2 or Ca2Nb3O10 Nanosheet Hybrids with Reduced Graphene Oxide.

High dielectric constants (εr) were observed in two-dimensional composites obtained from stacking of reduced graphene oxide (RGO) with Ca2Nb3O10 and with TiO2 nanosheets. The relative dielectric permittivity values of the composites were found to be higher than 105, an amazingly high value compared to that of similar GO composites and other common dielectric materials. As a consequence, we considered application of the hybrids as super dielectric materials in high capacitance supercapacitors. The route to high capacitance involves the variation of oxygen vacancies within the surface and in the closest bulk interior of the hybrids. The effective charges generated throughout the metal oxide and carbon-oxygen polar bonding systems within the graphene skeleton appear to highly influence dielectric polarization. Moreover, the replenishment of oxygen vacancies at the RGO and metal oxide interface also contributes to polarizability.