Photochemically-Driven CO2 Release Using a Metastable-State Photoacid for Energy Efficient Direct Air Capture

One of the grand challenges underlying current direct air capture (DAC) technologies relates to the intensive energy cost for sorbent regeneration and CO₂ release, making the massive scale (GtCO₂/year) deployment required to have a positive impact on climate change economically unfeasible. This challenge underscores the critical need to develop new DAC processes with substantially reduced regeneration energies. Here, we report a photochemically-driven approach for CO₂ release by exploiting the unique properties of an indazole metastable-state photoacid (mPAH). Our measurements on simulated and amino acid-based DAC systems revealed the potential of mPAH to be used for CO₂ release cycles by regulating pH changes and associated isomers driven by light. Upon irradiating with moderate intensity light, a ≈55 % and ≈68 % to ≈78 % conversion of total inorganic carbon to CO₂ was found for the simulated and amino acid-based DAC systems, respectively. Our results confirm the feasibility of on-demand CO₂ release under ambient conditions using light instead of heat, thereby providing an energy efficient pathway for the regeneration of DAC sorbents.     

Simultaneous lipidomic analysis of three families of bioactive lipid mediators leukotrienes, resolvins, protectins and related hydroxy-fatty acids by liquid chromatography/electrospray ionisation tandem mass spectrometry

Bioactive lipid mediators derived from polyunsaturated fatty acids (PUFA) exhibit a range of tissue- and cell-specific activities in many physiological and pathological processes. Electrospray ionisation tandem mass spectrometry coupled to liquid chromatography (LC/ESI-MS/MS) is a sensitive, versatile analytical methodology for the qualitative and quantitative analysis of lipid mediators. Here we present an LC/ESI-MS/MS assay for the simultaneous analysis of twenty mono- and poly-hydroxy-fatty acid derivatives of linoleic, arachidonic, eicosapentaenoic and docosahexaenoic acids. The assay was linear over the concentration range 1-100 pg/microL, whilst the limits of detection and quantitation were 10-20 and 20-50 pg, respectively. The recovery of the extraction methodology varied from 76-122% depending on the metabolite. This system is useful for profiling a range of biochemically related potent mediators including the newly discovered resolvins and protectins, and their precursor hydroxyeicosapentaenoic and hydroxydocosahexaenoic acids, and, consequently, advance our understanding of the role of PUFA in health and disease.     

Renal replacement lipomatosis: MR findings in one case

Replacement lipomatosis of the kidney is the result of severe atrophy or destruction of the renal parenchyma, often caused by calculous disease with secondary marked proliferation of renal sinus, renal hilus, and perirenal fatty tissue. Different diagnostic tools have been used to define this entity, with ultrasonography (US), i.v. pyelography (IVP) and computed tomography (CT) used most commonly. We report MR urography and MR appearance of replacement lipomatosis in a 38-year-old man. We think that it combines the advantages of IVP, US and CT.     

AFM substantiation of the fracture behavior and mechanical properties of sol–gel derived silica packed epoxy networks

Silica packed epoxy networks are prepared in two steps via in situ, solvent free sol–gel processing of tetraethoxysilane in liquid epoxy monomer and curing the mixture with a flexible diamine afterwards. The influence of filler content and processing conditions on the mechanical properties and the fracture behavior is studied by means of the static mechanical analysis and AFM characterization of the pristine and the fractured polymer surfaces, and a mechanism to enhance polymer strength and toughness is proposed. The in–situ evolution and packing of silica nanostructures into epoxy networks influences the overall morphology and performance of polymers under high stress. It is found that smaller silica domains distributed at the molecular level cause efficient crack distribution by absorbing energy and thus improve the strength and toughness of silica packed epoxy polymers.     

Micelle directed synthesis of (C19H42N)4H3(PW11O39) nanoparticles and their catalytic efficiency for oxidative degradation of azo dye

The nanoparticles of monovacant lacunary keggin-type polyoxometalate (C₁₉H₄₂N)₄H₃(PW₁₁O₃₉) has been successfully synthesized by Micelle Directed Method using hexadecyltrimthyl ammonium bromide (CTAB) as a template. Non-ionic copolymer Pluronic F127 was used as a capping agent that helps in formation of nanoparticles by preventing the aggregation during the coating of H₃(PW₁₁O₃₉)^4- onto the counter ion (C₁₉H₄₂N)⁺. The synthesized material was characterized by Scanning electron microscope (SEM), TGA, DSC and FT-IR techniques. SEM images indicated that (C₁₉H₄₂N)₄H₃(PW₁₁O₃₉) nanoparticles possess spherical structure. FTIR results revealed that the structural integrity of monovacant lacunary keggin-type polyoxometalates (POM) was not affected when reducing the size. TGA–DSC results showed that the material was thermally stable (with 37 % weight loss) and POM encapsulates CTAB. The efficiency of synthesized material was checked by applying it as a catalyst for the oxidation of toxic mordant yellow dye i.e., potentially hazardous and non-biodegradable azo dye. The (C₁₉H₄₂N)₄H₃(PW₁₁O₃₉) nanoparticles gave 96 % dye degradation in 60 min at 60 °C temperature. Moreover, on recycling POM nanoparticles demonstrate 92 % oxidative degradation of mordant yellow dye.     

Pulsed supersonic beams with nucleobases

The dissolution of the primary nucleobases in supercritical fluids has been investigated using pulsed molecular beam mass spectrometry. Due to the low critical temperatures of ethylene and carbon dioxide, their adiabatic jet expansion permits transferring thermally sensitive solutes into the gas phase. This feature is particularly attractive for pharmaceutical and biomedical applications. In this study, adenine, guanine, cytosine, thymine, and uracil have been dissolved in supercritical ethylene with a few percent of ethanol as cosolvent. At source temperatures of 313?K, these solutions have been expanded from supercritical pressures into high vacuum using a customized pulsed nozzle. A mass spectrometer was used to monitor the relative amounts of solute, solvent, and cosolvent in the supersonic beam. The results suggest a paramount influence of the cosolvent.     

Wrapped weighted exponential distributions

We have developed a new class of circular distributions named wrapped weighted exponential distributions. The estimation of unknown parameters along with some characteristics of these distributions is also investigated. Some theorems that relate the distribution to some other circular distributions are established and we clarify their modeling potential using a classical data set on movements of sea stars.     

Role of deliquescence lowering in enhancing chemical reactivity in physical mixtures

Mixtures of deliquescent solids are susceptible to deliquescence lowering, where water vapor condensation occurs in mixtures at a lower critical relative humidity (RH(0mix)) than individual component critical relative humidities (RH(0)s). The purpose of this study was to evaluate the effect of deliquescence lowering on chemical reactivity. Sucrose, citric acid and their physical mixtures were characterized using vapor sorption analysis to determine RH(0) and RH(0mix). Acid-catalyzed sucrose hydrolysis kinetics was determined using polarimetric analysis. Physical mixtures of sucrose and citric acid crystals were prepared and stored at various relative humidities at 22 degrees C. For these physical mixtures, sucrose hydrolysis was found to occur only when the environmental RH exceeded RH(0mix). Degradation kinetics correlated with the storage RH, being fastest at higher RH. In addition, a lag period was initially observed, which was most prominent for samples stored close to RH(0mix). With exposure to RHs below RH(0mix), no sucrose degradation was detected over the experimental time period. In conclusion, mixtures of deliquescent solids showed increased water sorption at lower RHs, which caused solid dissolution and subsequently led to an increase in the chemical reactivity.     

Aldimine 2,6-bis(imino)pyridine iron(II) and cobalt(II)/methyl aluminoxane catalyst systems for polymerization of <Emphasis Type="Italic">tert-</Emphasis>butylacrylate

Aldimine 2,6-bis[(imino)methyl]pyridine iron(II) (1, 4, and 6) and cobalt(II) (3 and 5) complexes bearing bulky cycloaliphatic (bornyl and myrtanyl) or aromatic (naphthyl) terminal groups have been applied successfully, after activation with methyl aluminoxane (MAO), as catalysts for the polymerization of tert-butylacrylate. For comparison reasons, complex 2 that contains the ketimine ligand, 2,6-bis[(−)-cis-myrtanylimino)ethyl]pyridine (BMEP), has also been utilized. All studied complexes showed moderate polymerization activities, and they produced high molar mass syndiorich-atactic polymers. Surprisingly, the aldimine-based catalyst systems showed comparable activities compared with the corresponding ketimine complex (2), and they produced high molar mass polymers. In addition, complexes with bulky terminal cycloaliphatic substituents on the tridentate aldimine ligands showed higher polymerization activity compared with the aromatic ones (6). Polymerization activity and polymer molar masses are dependent on the ligand framework.     

Photostability of lasing process from water solution of Rhodamine 6G with gold nanoparticles

We report the lasing performance and photobleaching of gain material containing a water solution of Rhodamine 6G dye and gold nanoparticles (NPs). In comparison to a pure dye solution, the investigated material demonstrated both enhancement and quenching of the lasing output, depending on the relative concentration of the gold NPs. Although the presence of NPs with an optimized concentration looks preferable in terms of the lasing output enhancement, such additives deteriorate the operational resource of the gain material; i.e., the photobleaching rate speeds up.