Silver molybdate (Ag2MoO4) and silver tungstate (Ag2WO4) nanomaterials were prepared using two complementary methods, microwave assisted hydrothermal synthesis (MAH) (pH 7, 140 °C) and ...co-precipitation (pH 4, 70 °C), and were then used to prepare two core/shell composites, namely α-Ag2WO4/β-Ag2MoO4 (MAH, pH 4, 140 °C) and β-Ag2MoO4/β-Ag2WO4 (co-precipitation, pH 4, 70 °C). The shape and size of the microcrystals were observed by field emission scanning electron microscopy (FE-SEM), different morphologies such as balls and nanorods. These powders were characterized by X-ray powder diffraction and UV-vis (diffuse reflectance and photoluminescence). X-ray diffraction patterns showed that the Ag2MoO4 samples obtained by the two methods were single-phased and belonged to the β-Ag2MoO4 structure (spinel type). In contrast, the Ag2WO4 obtained in the two syntheses were structurally different: MAH exhibited the well-known tetrameric stable structure β-Ag2WO4, while co-precipitation afforded the metastable β-Ag2WO4 allotrope, coexisting with a weak amount of the α;-phase. The optical gap of β-Ag2WO4 (3.3 eV) was evaluated for the first time. In contrast to β-Ag2MoO4/β-Ag2WO4, the α-Ag2WO4/β-Ag2MoO4 exhibited strongly-enhanced photoluminescence in the low-energy band (650 nm), tentatively explained by the creation of a large density of local defects (distortions) at the core-shell interface, due to the presence of two different types of MOx polyhedra in the two structures.
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► This work details the efficiency of microwave solvothermal synthesis in obtaining ZnS nanocrystals. ► The structure, surface chemical composition and optical properties were ...investigated as function of the precursor. ► According to the different precursors used, the PL behavior of ZnS causes a red shift which enables the design of LEDs with different colors. ► Photoluminescence is one more interesting property for technological applications this material.
In this article, we report the development of an efficient and rapid microwave assisted solvothermal (MAS) method to prepare wurtzite ZnS nanoparticles at 413K using different precursors. The materials obtained were analyzed by X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), field emission scanning electron microscopy (FE-SEM), transmission electron microscopy (MET) ultraviolet–visible (UV–vis) and photoluminescence (PL) measurements. The structure, surface chemical composition and optical properties were investigated as a function of the precursor. In addition, effects as well as merits of microwave heating on the processing and characteristics of ZnS nanoparticles obtained are reported. The possible formation mechanism and optical properties of these nanoparticles were also reported.
Urinary tract infections (UTIs) are a significant cause of morbidity in healthcare systems and are prominently associated with applying urethral catheters, particularly in surgeries. Polyvinyl ...chloride (PVC) is extensively utilized in the fabrication of catheters. Biofilms, complex polymeric constructions, provide a protective milieu for cell multiplication and the enhancement of antibiotic resistance. Strategies to counteract biofilm development on medical apparatuses' surfaces incorporate antimicrobial agents such as N,N-dodecyl, and methyl polyethylenimine (DMPEI). This research endeavored to characterize the morphology of PVC and PVC-DMPEI surfaces utilizing Scanning Electron Microscopy (SEM) and Atomic Force Microscopy (AFM) and to gauge hydrophobicity through contact angle measurements. Employing
Escherichia coli
,
Staphylococcus aureus
, and
Candida albicans
in adhesion assays enabled the assessment of DMPEI’s efficacy in preventing microbial adherence to PVC. Butanol successfully solubilized 2 mg.mL
−1
DMPEI without altering the PVC structure. SEM results substantiated the formation of a DMPEI layer on the PVC surface, which led to decreased surface roughness, as validated by AFM, and increased hydrophilicity, as demonstrated by contact angle evaluations. E. coli, S. aureus, and C. albicans exhibited significant adhesion reduction, 89.3%, 94.3%, and 86.6% on PVC-DMPEI surfaces. SEM visualizations confirmed reduced cellular colonization on PVC-DMPEI and highlighted considerable morphological modifications in
E. coli
. Consequently, DMPEI films effectively minimize the adhesion of
E. coli, S. aureus
, and
C. albicans
on PVC surfaces. DMPEI, with its potential as a protective coating for innovative medical devices, promises to inhibit biofilm adherence effectively.
Graphical abstract
Nature employs self-assembly to fabricate the most complex molecularly precise machinery known to man. Heteromolecular, two-dimensional self-assembled networks provide a route to spatially organize ...different building blocks relative to each other, enabling synthetic molecularly precise fabrication. Here we demonstrate optoelectronic function in a near-to-monolayer molecular architecture approaching atomically defined spatial disposition of all components. The active layer consists of a self-assembled terrylene-based dye, forming a bicomponent supramolecular network with melamine. The assembly at the graphene-diamond interface shows an absorption maximum at 740 nm whereby the photoresponse can be measured with a gallium counter electrode. We find photocurrents of 0.5 nA and open-circuit voltages of 270 mV employing 19 mW cm(-2) irradiation intensities at 710 nm. With an ex situ calculated contact area of 9.9 × 10(2) μm(2), an incident photon to current efficiency of 0.6% at 710 nm is estimated, opening up intriguing possibilities in bottom-up optoelectronic device fabrication with molecular resolution.
The nickel-iron carbon monoxide dehydrogenase (CODH) enzyme uses a heterometallic nickel-iron-sulfur (NiFe
S
) cluster to catalyze the reversible interconversion of carbon dioxide (CO
) and carbon ...monoxide (CO). These reactions are essential for maintaining the global carbon cycle and offer a route towards sustainable greenhouse gas conversion but have not been successfully replicated in synthetic models, in part due to a poor understanding of the natural system. Though the general protein architecture of CODH is known, the electronic structure of the active site is not well-understood, and the mechanism of catalysis remains unresolved. To better understand the CODH enzyme, we have developed a protein-based model containing a heterometallic NiFe
S
cluster in the
(
) ferredoxin (Fd). This model binds small molecules such as carbon monoxide and cyanide, analogous to CODH. Multiple redox- and ligand-bound states of NiFe
S
Fd (NiFd) have been investigated using a suite of spectroscopic techniques, including resonance Raman, Ni and Fe K-edge X-ray absorption spectroscopy, and electron paramagnetic resonance, to resolve charge and spin delocalization across the cluster, site-specific electron density, and ligand activation. The facile movement of charge through the cluster highlights the fluidity of electron density within iron-sulfur clusters and suggests an electronic basis by which CN
inhibits the native system while the CO-bound state continues to elude isolation in CODH. The detailed characterization of isolable states that are accessible in our CODH model system provides valuable insight into unresolved enzymatic intermediates and offers design principles towards developing functional mimics of CODH.
Lipid imaging mass spectrometry (LIMS) has been tested in several pathological contexts, demonstrating its ability to segregate and isolate lipid signatures in complex tissues, thanks to the ...technique’s spatial resolution. However, it cannot yet compete with the superior identification power of high-performance liquid chromatography coupled to mass spectrometry (HPLC-MS), and therefore, very often, the latter is used to refine the assignment of the species detected by LIMS. Also, it is not clear if the differences in sensitivity and spatial resolution between the two techniques lead to a similar panel of biomarkers for a given disease. Here, we explore the capabilities of LIMS and HPLC-MS to produce a panel of lipid biomarkers to screen nephrectomy samples from 40 clear cell renal cell carcinoma patients. The same set of samples was explored by both techniques, and despite the important differences between them in terms of the number of detected and identified species (148 by LIMS and 344 by HPLC-MS in negative-ion mode) and the presence/absence of image capabilities, similar conclusions were reached: using the lipid fingerprint, it is possible to set up classifiers that correctly identify the samples as either healthy or tumor samples. The spatial resolution of LIMS enables extraction of additional information, such as the existence of necrotic areas or the existence of different tumor cell populations, but such information does not seem determinant for the correct classification of the samples, or it may be somehow compensated by the higher analytical power of HPLC-MS. Similar conclusions were reached with two very different techniques, validating their use for the discovery of lipid biomarkers.
This paper presents a novel interrogation system that combines multiple millimeter wave transmitters and receivers to create real-time high-resolution radar images for personnel security screening. ...The main novelty of the presented system is that the images can be created as the person being screened continuously moves across a corridor where the transmitters and receivers, working in a fully coherent architecture, are distributed. As the person moves, the transmitters and receivers are sequentially activated to collect data from different angles to inspect the whole body. Multiple images, similar to video frames, are created and examined to look for possible anomalies such as concealed threats. Two-dimensional (2-D) and three-dimensional (3-D) setups have been simulated to show the feasibility of the proposed system. The simulation results in 2-D have been validated using measurements.
Green, inexpensive, and robust copper‐based heterogeneous catalysts achieve 100 % conversion and 99 % selectivity in the conversion of furfural to furfuryl alcohol when using cyclopentyl‐methyl ether ...as green solvent and microwave reactors at low H2 pressures and mild temperatures. The utilization of pressurized microwave reactors produces a 3–4 fold increase in conversion and an unexpected enhancement in selectivity as compared to the reaction carried out at the same conditions using conventional autoclave reactors. The enhancement in catalytic rate produced by microwave irradiation is temperature dependent. This work highlights that using microwave irradiation in the catalytic hydrogenation of biomass‐derived compounds is a very strong tool for biomass upgrade that offers immense potential in a large number of transformations where it could be a determining factor for commercial exploitation.
Microwaved catalysts! Green, inexpensive, and robust copper‐based heterogeneous catalysts with high conversion and selectivity are developed for the conversion of furfural to furfuryl alcohol using cyclopentyl‐methyl ether as green solvent and microwave reactors at low H2 pressures and mild temperatures.
•We investigated fruit water relations and osmotic adjustment in sun injured apples.•Skin water and solutes potentials decreased with fruit development and sun damage.•Sun exposure induced sorbitol ...and glucose accumulation in the skin and flesh.•Tissue toughness increased with sun exposures although internal ethylene increased.•Sun exposure activates acclimation mechanisms, perhaps, via sugars and ethylene.
Sun-injury (=sunscald, sunburn) in fruit crops is caused by photodynamic reactions on heated fruit sections exposed to direct sunlight. There is evidence supporting the oxidative nature of this disorder. Nevertheless, there are other physiological events, typically observed in water-stressed plants, such as water relations and osmoregulation that greatly influence external and internal quality of sun-injured fruit and have poorly addressed in the literature. Apple tissues (skin and flesh) with different levels of sun exposure and sun-injury (mild, moderate (Mod), severe (Sev)) were sampled at different growing stages during 2011 and 2012, in Royal Gala and Fuji. Water, solutes, and turgor potentials, relative water content (RWC), carbohydrates concentration (sucrose, sorbitol, glucose, fructose), internal ethylene concentration (IEC), and textural curves were determined. Skin water potential decreased with fruit development and it was significantly more negative in sun-injured tissue compared to unexposed ones. Solutes potential also decreased in skin and flesh with increasing sun damage, but the opposite was found in turgor potential. Fruit RWC at harvest decreased with increasing sunburn severity. Sun exposure induced sorbitol and glucose accumulation in fruit peel and flesh. Tissue with Mod and Sev sunscald showed higher IEC early in the season. Fruit shape and firmness were also altered by sun exposure. The results might indicate that sun-exposed tissue via more negative water potentials activates an abiotic stress-response cascade, perhaps mediated by sugars and ethylene, to cope with the environmental stress caused by high irradiance and heat, whose consequences are peculiar fruit quality traits.
Assessments of the combined ecological impacts of ocean acidification and warming (OAW) and their social and economic consequences can help develop adaptive and responsive management strategies in ...the most sensitive regions. Here, available observational and experimental data, theoretical, and modelling approaches are combined to project and quantify potential effects of OAW on the future fisheries catches and resulting revenues and employment in the UK under different CO2 emission scenarios. Across all scenarios, based on the limited available experimental results considered, the bivalve species investigated were more affected by OAW than the fish species considered, compared with ocean warming alone. Projected standing stock biomasses decrease between 10 and 60%. These impacts translate into an overall fish and shellfish catch decrease of between 10 and 30% by 2020 across all areas except for the Scotland >10 m fleet. This latter fleet shows average positive impacts until 2050, declining afterwards. The main driver of the projected decreases is temperature rise (0.5–3.3 °C), which exacerbate the impact of decreases in primary production (10–30%) in UK fishing waters. The inclusion of the effect of ocean acidification on the carbon uptake of primary producers had very little impact on the projections of potential fish and shellfish catches (<1%). The <10 m fleet is likely to be the most impacted by‐catch decreases in the short term (2020–50), whereas the effects will be experienced more strongly by the >10 m fleet by the end of the century in all countries. Overall, losses in revenue are estimated to range between 1 and 21% in the short term (2020–50) with England and Scotland being the most negatively impacted in absolute terms, and Wales and North Ireland in relative terms. Losses in total employment (fisheries and associated industries) may reach approximately 3–20% during 2020–50 with the >10 m fleet and associated industries bearing the majority of the losses.
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