Mo-BiVO4 Photocatalytically Modified Ceramic Ultrafiltration Membranes for Enhanced Water Treatment Efficiency.

This study highlights the effectiveness of photocatalytically modified ceramic ultrafiltration (UF) membranes in alleviating two major drawbacks of membrane filtration technologies. These are the generation of a highly concentrated retentate effluent as a waste stream and the gradual degradation of the water flux through the membrane due to the accumulation of organic pollutants on its surface. The development of two types of novel tubular membranes, featuring photocatalytic Mo-BiVO4 inverse opal coatings, demonstrated a negligible impact on water permeance, ensuring consistent filtration and photocatalytic efficiency and suggesting the potential for maintaining membrane integrity and avoiding the formation of highly concentrated retentate effluents. Morphological analysis revealed well-defined coatings with ordered domains and interconnected macropores, confirming successful synthesis of Mo-BiVO4. Raman spectroscopy and optical studies further elucidated the composition and light absorption properties of the coatings, particularly within the visible region, which is vital for photocatalysis driven by vis-light. Evaluation of the tetracycline removal efficiency presented efficient adsorption onto membrane surfaces with enhanced photocatalytic activity observed under both UV and vis-light. Additionally, vis-light irradiation facilitated significant degradation, showcasing the versatility of the membranes. Total Organic Carbon (TOC) analysis corroborated complete solute elimination or photocatalytic degradation without the production of intermediates, highlighting the potential for complete pollutant removal. Overall, these findings emphasize the promising applications of Mo-BiVO4 photocatalytic membranes in sustainable water treatment and wastewater remediation processes, laying the groundwork for further optimization and scalability in practical water treatment systems.

Utilizing Carbonaceous Materials Derived from [BMIM][TCM] Ionic Liquid Precursor: Dual Role as Catalysts for Oxygen Reduction Reaction and Adsorbents for Aromatics and CO2.

This work presents the synthesis of N-doped nanoporous carbon materials using the Ionic Liquid (IL) 1-butyl-3-methylimidazolium tricyanomethanide [BMIM][TCM] as a fluidic carbon precursor, employing two carbonization pathways: templated precursor and pyrolysis/activation. Operando monitoring of mass loss during pyrolytic and activation treatments provides insights into chemical processes, including IL decomposition, polycondensation reactions and pore formation. Comparatively low mass reduction rates were observed at all stages. Heat treatments indicated stable pore size and increasing volume/surface area over time. The resulting N-doped carbon structures were evaluated as electrocatalysts for the oxygen reduction reaction (ORR) and adsorbents for gases and organic vapors. Materials from the templated precursor pathway exhibited high electrocatalytic performance in ORR, analyzed using Rotating Ring-Disk electrode (RRDE). Enhanced adsorption of m-xylene was attributed to wide micropores, while satisfactory CO2 adsorption efficiency was linked to specific morphological features and a relatively high content of N-sites within the C-networks. This research contributes valuable insights into the synthesis and applications of N-doped nanoporous carbon materials, highlighting their potential in electrocatalysis and adsorption processes.

Chemical characterisation of artists' spray-paints: A diagnostic tool for urban art conservation.

In this study the chemical characterisation of 24 commercial spray-paints in different colours as used in contemporary public murals, street art, and graffiti is presented. The analyses were focused on the identification of the binding media, pigments, and additives. In addition, four spray-paint samples were analysed in the form of bi-layered paint films to explore the possibility of determining the composition of multi-layered samples. The aim of the study was to provide a useful diagnostic tool for the conservation of spray-paints and the removal of overpaintings from both commissioned murals and any other form of cultural heritage. To achieve this goal, a multi-analytical approach was developed using Attenuated Total Reflectance-Fourier Transform Infrared Spectroscopy (ATR-FTIR) for the identification of the main binder, pigments, and fillers/extenders, while Raman spectroscopy and Scanning Electron Microscopy/Energy Dispersive X-ray Spectroscopy (SEM/EDS) were used as complementary tools for the determination of organic and inorganic pigments, and fillers. Five kinds of binders were detected in this work: (1) acrylic resins combined with nitrocellulose, (2) acrylic resins modified with styrene and combined with nitrocellulose, (3) alkyd resins modified with styrene and combined with nitrocellulose, (4) combined acrylic and alkyd resins modified with styrene and blended with nitrocellulose, and (5) combined polystyrene and acrylic resins. Also, a wide variety of organic pigments and inorganic components were detected.

Engineering Commercial TiO2 Powder into Tailored Beads for Efficient Water Purification.

In this study, efficient commercial photocatalyst (Degussa P25) nanoparticles were effectively dispersed and stabilized in alginate, a metal binding biopolymer. Taking advantage of alginate's superior metal chelating properties, copper nanoparticle-decorated photocatalysts were developed after a pyrolytic or calcination-sintering procedure, yielding ceramic beads with enhanced photocatalytic and mechanical properties, excellent resistance to attrition, and optimized handling compared to powdered photocatalysts. The morphological and structural characteristics were studied using LN2 porosimetry, SEM, and XRD. The abatement of an organic pollutant (Methyl Orange, MO) was explored in the dark and under UV irradiation via batch experiments. The final properties of the photocatalytic beads were defined by both the synthesis procedure and the heat treatment conditions, allowing for their further optimization. It was found that the pyrolytic carbon residuals enabled the adhesion of the TiO2 nanoparticles, acting as binder, and increased the MO adsorption capacity, leading to increased local concentration in the photocatalyst vicinity. Well dispersed Cu nanoparticles were also found to enhance photocatalytic activity. The prepared photocatalysts exhibited increased MO adsorption capacity (up to 3.0 mg/g) and also high photocatalytic efficiency of about 50% MO removal from water solutions, reaching an overall MO rejection of about 80%, at short contact times (3 h). Finally, the prepared photocatalysts kept their efficiency for at least four successive photocatalytic cycles.

Multi-Walled Carbon Nanotubes Decorated with Guanidinylated Dendritic Molecular Transporters: An Efficient Platform for the Selective Anticancer Activity of Doxorubicin.

An efficient doxorubicin (DOX) drug delivery system with specificity against tumor cells was developed, based on multi-walled carbon nanotubes (MWCNTs) functionalized with guanidinylated dendritic molecular transporters. Acid-treated MWCNTs (oxCNTs) interacted both electrostatically and through hydrogen bonding and van der Waals attraction forces with guanidinylated derivatives of 5000 and 25,000 Da molecular weight hyperbranched polyethyleneimine (GPEI5K and GPEI25K). Chemical characterization of these GPEI-functionalized oxCNTs revealed successful decoration with GPEIs all over the oxCNTs sidewalls, which, due to the presence of guanidinium groups, gave them aqueous compatibility and, thus, exceptional colloidal stability. These GPEI-functionalized CNTs were subsequently loaded with DOX for selective anticancer activity, yielding systems of high DOX loading, up to 99.5% encapsulation efficiency, while the DOX-loaded systems exhibited pH-triggered release and higher therapeutic efficacy compared to that of free DOX. Most importantly, the oxCNTs@GPEI5K-DOX system caused high and selective toxicity against cancer cells in a non-apoptotic, fast and catastrophic manner that cancer cells cannot recover from. Therefore, the oxCNTs@GPEI5K nanocarrier was found to be a potent and efficient nanoscale DOX delivery system, exhibiting high selectivity against cancerous cells, thus constituting a promising candidate for cancer therapy.

Structuring efficient photocatalysts into bespoke fiber shaped systems for applied water treatment.

In this study, structured photocatalytic systems were successfully developed by a facile method based on Alginate molds and a wet-spinning/cross-linking technique, yielding commercial photocatalyst (Degussa P25) in the form of all-ceramic hollow fibers (HFs). Taking advantage of alginate's exceptional sorption properties, copper augmented HFs were also developed. The structured photocatalysts were thoroughly characterised by a variety of techniques, including nitrogen adsorption, SEM/EDS, XRD, XPS and Raman. Synthesis and heat treatment parameters were found to affect the fibers' properties, allowing their optimization. Treatment at 600 °C under Ar was found to produce the best performing photocatalysts in terms mechanical stability, resistance to attrition and photocatalytic performance. Ca-Alginate precursors led to structures with increased mechanical stability, while Cu-Alginate decorated the surface of the photocatalyst with highly dispersed copper nanoparticles, in the state of metallic and CuO. The developed materials were photo-catalytically active, while the copper decorated ceramic HFs exhibited the highest MO adsorption and photocatalytic degradation performance, reaching a MO removal of 73.4%. The synergestic effect of adsorption on the MO degradation performance was also noticed. Moreover, the copper addition facilitated the photocatalytic process by improving the electron-hole separation and inhibiting the recombination effects. The presence of carbon residue was also beneficial, enhancing the MO sorption on the photocatalysts. It is noteworthy that the structured photocatalysts retained their efficiency for at least four photocatalytic cycles. The prepared ceramic HFs exhibited enhanced mechanical properties and excellent resistance to attrition after subsequent cycles, rendering them excellent candidates for application in industrial wastewater processes.

Cytotoxicity Effects of Water-Soluble Multi-Walled Carbon Nanotubes Decorated with Quaternized Hyperbranched Poly(ethyleneimine) Derivatives on Autotrophic and Heterotrophic Gram-Negative Bacteria.

Oxidized multi-walled carbon nanotubes (oxCNTs) were functionalized by a simple non-covalent modification procedure using quaternized hyperbranched poly(ethyleneimine) derivatives (QPEIs), with various quaternization degrees. Structural characterization of these hybrids using a variety of techniques, revealed the successful and homogenous anchoring of QPEIs on the oxCNTs' surface. Moreover, these hybrids efficiently dispersed in aqueous media, forming dispersions with excellent aqueous stability for over 12 months. Their cytotoxicity effect was investigated on two types of gram(-) bacteria, an autotrophic (cyanobacterium Synechococcus sp. PCC 7942) and a heterotrophic (bacterium Escherichia coli). An enhanced, dose-dependent antibacterial and anti-cyanobacterial activity against both tested organisms was observed, increasing with the quaternization degree. Remarkably, in the photosynthetic bacteria it was shown that the hybrid materials affect their photosynthetic apparatus by selective inhibition of the Photosystem-I electron transport activity. Cytotoxicity studies on a human prostate carcinoma DU145 cell line and 3T3 mouse fibroblasts revealed that all hybrids exhibit high cytocompatibility in the concentration range, in which they also exhibit both high antibacterial and anti-cyanobacterial activity. Thus, QPEI-functionalized oxCNTs can be very attractive candidates as antibacterial and anti-cyanobacterial agents that can be used for potential applications in the disinfection industry, as well as for the control of harmful cyanobacterial blooms.

Photocatalysis as an advanced reduction process (ARP): The reduction of 4-nitrophenol using titania nanotubes-ferrite nanocomposites.

TiO2 photocatalysis is an advanced process, employed worldwide for the oxidation of organic compounds, that leads to significant technological applications in the fields of health and environment. The use of the photocatalytic approach in reduction reactions seems very promising and can open new horizons for green chemistry synthesis. For this purpose, titanium dioxide nanotubes (TNTs) were developed in autoclave conditions using TiO2 P25 as a precursor material. Based on these nanotubular substrates, TiO2/CoFe2O4 (TCF) nanocomposites were further obtained by wet impregnation method. The materials were thoroughly characterized and their structural, textural, vibrational, optoelectronic and magnetic properties were determined. The composite materials combine absorbance in the visible optical range and high BET surface area values (˜100 m2/g), showing extremely high yield in the photocatalytic reduction of 4-nitrophenol (4-NP), exceeding 94% within short illumination time (only 35 min). The developed nanocomposites were successfully reused in consecutive photocatalytic experiments and were easily removed from the reaction medium using magnets. Both remarkable recycling ability and high-performance stability in the photocatalytic reduction of nitrophenol were observed, thus justifying the significant economic potential and industrial perspectives for this advanced reduction process.

Modified in situ antimicrobial susceptibility testing method based on cyanobacteria chlorophyll a fluorescence.

The chlorophyll a fluorescence based antimicrobial susceptibility testing (AST) method presented in a previous work was based on the measurement of Chl a fluorescence of the gram(-) cyanobacterium Synechococcus sp. PCC 7942. Synechococcus sp. PCC 7942 as a gram(-) bacterium is affected by antibacterial agents via mechanisms affecting all gram(-) bacteria, however, as an exclusively phototrophic organism it would also be affected by photosynthesis inhibitory action of an agent that otherwise has no antibacterial properties. In this report, the method is modified by replacing the exclusively phototrophic Synechococcus sp. PCC 7942 with the Synechocystis sp. PCC 6714, capable of both phototrophic and heterotrophic growth in order to add versatility and better reflect the antibacterial effects of surfaces under study towards nonphotosynthetic bacteria.

An in situ antimicrobial susceptibility testing method based on in vivo measurements of chlorophyll α fluorescence.

Up to now antimicrobial susceptibility testing (AST) methods are indirect and generally involve the manual counting of bacterial colonies following the extraction of microorganisms from the surface under study and their inoculation in a separate procedure. In this work, an in situ, direct and instrumental method for the evaluation and assessment of antibacterial properties of materials and surfaces is proposed. Instead of indirectly determining antibacterial activity using the typical gram(-) test organisms with the subsequent manual colony count or inhibition zone measurement, the proposed procedure, employs photosynthetic gram(-) cyanobacteria deposited directly onto the surface under study and assesses cell proliferation and viability by a quick, accurate and reproducible instrumental chlorophyll fluorescence spectrophotometric technique. In contrast with existing methods of determination of antibacterial properties, it produces high resolution and quantitative results and is so versatile that it could be used to evaluate the antibacterial properties of any compound (organic, inorganic, natural or man-made) under any experimental conditions, depending on the targeted application.

Intercalation study of low-molecular-weight hyperbranched polyethyleneimine into graphite oxide.

We report for the first time the intercalation of low-molecular-weight hyperbranched polyethyleneimine (PEI) into graphite oxide (GO) for the facile, bulk synthesis of novel graphene-based hybrid (GO-PEI) materials exhibiting tailored interlayer galleries. The size of the intercalant as well as the loading in GO were systematically investigated to determine their contribution to the basal spacing of the resulting materials. Powder X-ray diffraction measurements demonstrated the generation of constrained hybrid systems along the c axis that exhibit considerably increased interlayer distances compared with the starting, pristine GO. The results of X-ray photoelectron and FTIR studies are consistent with a "grafting-to" process of the intercalated PEI with the oxygen functional groups present along the GO framework. Furthermore, it was found that a great number of the nitrogen-containing groups in PEI still remain available within the newly formed, confined micro-environment of intercalated GO galleries. The increased surface area of the GO-PEI hybrids in conjunction with the remaining available active groups of intercalated PEI render the synthesised hybrids very attractive candidates as nanostructured adsorbents.

Facile synthesis of carbon supported copper nanoparticles from alginate precursor with controlled metal content and catalytic NO reduction properties.

A copper-nanoparticle-doped carbon was prepared from an alginate based precursor in a one step carbonisation-reduction procedure based on the modified polyol process. The ion exchange capacity of the precursor as well as the porosity, metal content, thermal properties, of the final product, were investigated. The preparation route leads to a porous carbon/copper composite with predefined metal loading reaching up to over 30% (w/w) of finely dispersed Cu nanoparticles of fairly uniform size. NO catalytic abatement evaluation showed high efficiency even at low temperatures compared to other recently reported carbon supported catalysts.

Metal-carboxylate interactions in metal-alginate complexes studied with FTIR spectroscopy.

FTIR spectroscopy was used in order to obtain information about metal-carboxylate interactions in metal-alginate complexes of alginic acid and sodium alginate from the brown algae Laminaria digitata after crosslinking with Ca(2+), Cu(2+), Cd(2+), Zn(2+), Ni(2+) and Pb(2+). From the frequencies of the characteristic peaks for asymmetric COO stretching vibration (nu(asym)(COO(-)) and symmetric COO stretching vibration (nu(sym)(COO(-))) a 'pseudo bridged' unidentate coordination with intermolecular hydrogen bonds is proposed for the metal-carboxylate complexes in polyguluronic regions while for the polymannuronic regions the bidentate bridging coordination was proposed. The PIB factor introduced previously as a relationship between metal sorption and frequencies of the asymmetric vibrations was found not to correlate with sorption capacity or any other physical property of the metal-alginate complexes studied.

Impairment of autonomic nervous system activity in patients with pulmonary arterial hypertension: a case control study.

BACKGROUND: Chronotropic response to exercise (CR) and heart rate recovery (HRR) immediately after exercise are indirect indices of sympathetic and parasympathetic activity, respectively. The aim of this study was to evaluate CR and HRR in patients with pulmonary arterial hypertension (PAH) in relation to disease severity. METHODS AND RESULTS: Ten PAH patients (6 females/4 males, mean age: 48+/-12 years) and 10 control subjects matched for age, gender, and body mass index (6 females/4 males, mean age: 46+/-6 years) performed a ramp incremental symptom-limited cardiopulmonary exercise test on a cycle ergometer. Main measurements included heart rate at rest (HR), CR=[(peak HR-resting HR/220-age-resting HR)x100, %], HRR(1)=HR difference from peak exercise to 1minute after, ventilatory efficiency during exercise (VE/VCO(2) slope), peak oxygen uptake (VO(2)p), and the first-degree slope of VO(2) for the first minute of the recovery period (VO(2)/t-slope). PAH patients had a significantly decreased CR (58+/-31 vs 92+/-13, %, P < .001) and HRR(1) (10+/-5 vs 29+/-6, beats/min, P < .001) as well as VO(2)p (11.9+/-3.5 vs 26.9+/-6.6, mL.kg.min) and VO(2)/t-slope (0.2+/-0.1 vs. 0.9+/-0.2, mL.kg.min(2)) compared with controls. CR and HRR(1) correlated well with VO(2)p (r=0.7; P < .001 and r=0.85; P < .001, respectively) and VO(2)/t-slope (r=0.66; P < .001 and r=0.85; P < .001, respectively) and had a significant inverse correlation with VE/VCO(2) slope (r=-0.47; P < .01 and r=-0.77; P < .001, respectively). CONCLUSIONS: PAH patients present a significant impairment of CR and HRR(1) in relation to disease severity, indicating profound autonomic nervous system abnormalities.

Amiodarone attenuates the proarrhythmic effects of dobutamine in patients with advanced congestive heart failure.

INTRODUCTION: The long-term use of positive inotropic pharmaceuticals in patients suffering from end-stage congestive heart failure (CHF) has been associated with increased mortality, presumed to be due to proarrhythmia. Oral amiodarone combined with intermittent dobutamine infusions (IDI), on the other hand, has been shown to increase survival. This study evaluated the effects of oral amiodarone on the arrhythmias caused by dobutamine in patients with advanced CHF. METHODS: Thirty patients with CHF, in New York Heart Association functional class III or IV despite optimal medical therapy, were treated with weekly 8-h infusions of dobutamine 10 Ig/kg/min. All patients were treated for 1 month with oral amiodarone, 400 mg/day, before initiation of IDI. A 24-h ambulatory electrocardiogram was recorded on the day before dobutamine infusion and repeated the next day, starting with the onset of infusion. RESULTS: The average heart rate on the 24-h ambulatory electrocardiogram was 72 +/- 14 beats/min before vs. 72 +/- 12 beats/min during IDI (p=1.000). Likewise, dobutamine did not increase the frequency of premature ventricular complexes (23 +/- 32 per h before vs. 42 +/- 69 per h during infusion, p=0.131), ventricular couplets (18 +/- 36 per 24 h vs. 17 +/- 28 per 24 h, p=0.859), or the incidence of non-sustained ventricular tachycardia (27% vs. 40%, p=0.383). No patient developed ventricular fibrillation or sustained ventricular tachycardia during or after IDI. CONCLUSIONS: Chronic low-dose oral amiodarone attenuates the proarrhythmic effects of dobutamine, increasing the safety of ambulatory IDI.

Intermittent inotropic infusions combined with prophylactic oral amiodarone for patients with decompensated end-stage heart failure.

BACKGROUND: Concern has been raised regarding the mortality and ethics related to the treatment of patients with end-stage chronic heart failure with chronic intermittent intravenous inotropic agents. We examined whether intermittent inotropic agents combined with oral amiodarone to prevent the proarrhythmic effect of inotropic agents results in better outcomes. METHODS: The study included 162 patients with decompensated end-stage chronic heart failure, who could be weaned from an initial 72-hour infusion of intravenous inotropes. Group 1 included 140 patients, who entered a 6-month program of weekly intermittent intravenous inotropic agents plus oral amiodarone, 200 mg twice a day. Group 2 included 22 patients, who were treated with optimal conventional therapy and were hospitalized for administration of intravenous medications as needed. RESULTS: The baseline characteristics of groups 1 versus 2, including New York Heart Association functional class (IV in both groups), admission systolic arterial blood pressure (99 +/- 14 vs. 97 +/- 13 mm Hg), right atrial pressure (13 +/- 6 vs. 14 +/- 6 mm Hg), pulmonary capillary wedge pressure (28 +/- 7 vs. 31 +/- 10 mm Hg), serum sodium (136 +/- 7 vs. 139 +/- 6 mEq/L) and serum creatinine (1.7 +/- 0.8 vs. 1.8 +/- 1.8 mg/dL), were similar. The 6-month (51% vs. 18%) and 1-year (36% vs. 9%) survival rates were significantly higher (P = 0.001 for both) in group 1 than in group 2. In addition, patients treated with intermittent intravenous inotropic agents improved their functional and hemodynamic status. CONCLUSIONS: Intermittent intravenous inotropic agents combined with prophylactic oral amiodarone seem to improve the outcomes of patients with end-stage chronic heart failure. Further research is warranted to elucidate whether this treatment strategy should be considered as a standard therapy in patients with refractory end-stage heart failure.

Heavy metal sorption by calcium alginate beads from Laminaria digitata.

Alginate with a high M/G ratio, extracted from Laminaria digitata, was evaluated for Cu(2+), Cd(2+) and Pb(2+) sorption in acidic solutions, in the form of calcium cross-linked beads. The high M/G ratio of alginate extracted from this algal species is most likely the determining factor for the increased adsorption capacity of the investigated metals, indicating that the mannuronic acid is responsible for the ion exchange mechanism. The data obtained from the batch experiments have been interpreted with Langmuir, Freundlich and Sips models. The Sips equation provided the best fit with the experimental results, indicating sorption sites heterogeneity for the material. The pH was found to have a significant effect on the process, with sorption capacity reaching a maximum at pH 4.5, indicating a competition mechanism between H(+) and metal ions. Kinetic experiments were performed at the optimum pH. For the interpretation of the kinetic experiments the Linear Adsorption Model was employed and diffusion coefficients were determined. The model fits the experimental data at higher concentrations, where the adsorbed quantity remains almost constant. Finally, a simplified expression of the batch kinetic adsorption model was employed. The model, predicts adequately, not only the diffusivity values, but also the concentration profiles inside the spherical particles.