Gas-Phase Photocatalytic Coprocessing of CO2 - H2O(v) to Energy Products Promoted by the n,n-Junction In2O3@g-C3N4 under VIS-Light.

Carbon dioxide capture and utilization is a strategic technology for moving away from fossil-C. The conversion of CO2 into fuels demands energy and hydrogen that cannot be sourced from fossil-C. Co-processing of CO2 and water under solar irradiation will have a key role in the long-term for carbon-recycling and energy products production. This article discusses the synthesis, characterization and application of the two-phase composite photocatalyst, In2O3@g-C3N4, formed by thermal condensation of melamine in the presence of indium(III)nitrate. The composite exhibits a n,n-heterojunction between two n-type semiconductors, g-C3N4 and In2O3, leading to a more efficient charge separation. The composite has a flat band potential enabling it to effectively catalyze the reduction of CO2 in the gas phase to produce CO, CH4 and CH3OH. While the composite's overall photocatalytic efficiency is comparable to that of neat g-C3N4, its ability to promote multielectron-transfer and Proton Coupled to Electron Transfer (PCET) suggests that there is a potential for further optimization of its properties. The use of labelled 13CO2 has allowed us to clearly exclude that the reduced species are derived from the photocatalyst decomposition or the degradation of contaminants.

Improving the Enzymatic Cascade of Reactions for the Reduction of CO2 to CH3OH in Water: From Enzymes Immobilization Strategies to Cofactor Regeneration and Cofactor Suppression.

The need to decrease the concentration of CO2 in the atmosphere has led to the search for strategies to reuse such molecule as a building block for chemicals and materials or a source of carbon for fuels. The enzymatic cascade of reactions that produce the reduction of CO2 to methanol seems to be a very attractive way of reusing CO2; however, it is still far away from a potential industrial application. In this review, a summary was made of all the advances that have been made in research on such a process, particularly on two salient points: enzyme immobilization and cofactor regeneration. A brief overview of the process is initially given, with a focus on the enzymes and the cofactor, followed by a discussion of all the advances that have been made in research, on the two salient points reported above. In particular, the enzymatic regeneration of NADH is compared to the chemical, electrochemical, and photochemical conversion of NAD+ into NADH. The enzymatic regeneration, while being the most used, has several drawbacks in the cost and life of enzymes that suggest attempting alternative solutions. The reduction in the amount of NADH used (by converting CO2 electrochemically into formate) or even the substitution of NADH with less expensive mimetic molecules is discussed in the text. Such an approach is part of the attempt made to take stock of the situation and identify the points on which work still needs to be conducted to reach an exploitation level of the entire process.

Zebrafish Paralogs brd2a and brd2b Are Needed for Proper Circulatory, Excretory and Central Nervous System Formation and Act as Genetic Antagonists during Development.

Brd2 belongs to the BET family of epigenetic transcriptional co-regulators that act as adaptor-scaffolds for the assembly of chromatin-modifying complexes and other factors at target gene promoters. Brd2 is a protooncogene and candidate gene for juvenile myoclonic epilepsy in humans, a homeobox gene regulator in Drosophila, and a maternal-zygotic factor and cell death modulator that is necessary for normal development of the vertebrate central nervous system (CNS). As two copies of Brd2 exist in zebrafish, we use antisense morpholino knockdown to probe the role of paralog Brd2b, as a comparative study to Brd2a, the ortholog of human Brd2. A deficiency in either paralog results in excess cell death and dysmorphology of the CNS, whereas only Brd2b deficiency leads to loss of circulation and occlusion of the pronephric duct. Co-knockdown of both paralogs suppresses single morphant defects, while co-injection of morpholinos with paralogous RNA enhances them, suggesting novel genetic interaction with functional antagonism. Brd2 diversification includes paralog-specific RNA variants, a distinct localization of maternal factors, and shared and unique spatiotemporal expression, providing unique insight into the evolution and potential functions of this gene.

Chemical recycling of poly-(bisphenol A carbonate) by diaminolysis: A new carbon-saving synthetic entry into non-isocyanate polyureas (NIPUreas).

The present study describes an unprecedented approach to valorize potentially hazardous poly-(bisphenol A carbonate) (PC) wastes. In THF, under non-severe conditions (120 °C), the reaction of PC with long-chain diamines H2NRNH2 (2 equivalents) provided a tool to regenerate the monomer bisphenol A (BPA; 83-95%, isolated) and repurpose waste PC into [-NHRNHCO-]n polyureas (PUs; 78-99%, isolated) through a non-isocyanate route. Basic diamines (1,6-diaminohexane, 4,7,10-trioxa-1,13-tridecanediamine, meta-xylylenediamine, para-xylylenediamine) reacted with PC without any auxiliary catalyst; less reactive aromatic diamines (4,4'-diaminodiphenylmethane, 2,4-diaminotoluene) required the assistance of a base catalyst (1,8-diazabicyclo[5.4.0]undec-7-ene, NaOH). The formation of [-NHRNHCO-]n goes through a carbamation step affording BPA and carbamate intermediates H[-OArOC(O)NHRNHC(O)-]nOArOH (Ar=4,4'-C6H4C(Me)2C6H4-) that, in a subsequent step, convert into [-NHRNHCO-]n and more BPA. All the PUs were characterized in the solid state by CP/MAS 13C NMR (δ(CO) = 152-161 ppm) and IR spectroscopy. The positions of ν(N-H) and ν(CO) absorptions are typical of "hydrogen-bonded ordered" bands suggesting the presence of H-bonded groups in network structures characterized by some degree of order or regularity. DSC and TGA analyses showed that the PUs are thermally stable (Td,5%: 212-270 °C) and suitable for being processed since their degradation begins at temperatures about 100 °C higher than their Tg or Tm.

The Future of Carbon Dioxide Chemistry.

The utilization of carbon dioxide as building block for chemicals or source of carbon for energy products has been explored for over 40 years now, with varying allure. In correspondence with oil-crises, the use of CO2 has come into the spotlight, soon set aside when the crisis was over due to the low price of fossil carbon and the convenience of using established technologies. Nowadays, there is a continuous shift from fossil-C-based to perennial (solar, wind, geothermal, hydro-power) energy-driven processes that will also have a great potential to convert large amounts of carbon dioxide. The integration of biotechnology and catalysis will be a key player towards the utilization of CO2 in several different applications, reducing both the extraction of fossil carbon and the carbon transfer to the atmosphere.

The Validation of the Free Fantasy Questionnaire for Children and Adolescents: From Imaginary Playmate to "Dreamtime".

Fantasy in children is a precocious and important skill. In normal subjects some imaginative events, very close to hallucinations (perception-like experiences), have been found. Therefore, a better knowledge on both fantasy and the difference between imagination and the external world is needed. The aims of this study are: (a) to validate a new questionnaire for fantasy in children and adolescents; (b) to test its clinical application in ADHD children. 1.707 participants aged 8-18 years were enrolled: 1557 were recruited from a survey in six schools, whereas 150 participants were recruited in an ADHD Center. They filled out a new questionnaire, the Free Fantasy Questionnaire for Children and Adolescents, FFQ. Statistical analyses were performed to validate the FFQ and to study five parameters of fantasy. Analyses showed good properties of the FFQ as regards factor structure and reliability. Descriptive analysis showed that: 10% of the adolescents frequently have fantasy with paracosmos and 9.5% sometimes have a fantasy with imaginary relatives. Moreover, in the 64.3% of participants of primary school, in the 34.5% of lower-secondary, and in the 27.4% of upper-secondary school Perception-like experiences, involving invisible but real personages, were found. Quality of fantasy and Lack of control on imagination are correlated with a high score in the Reality/Unreality Dimension and Perception-like experiences. As regards ADHD participants, the 40% of the group showed Perception-like experiences: the 21.66% of them reported a very high score in the dimension Reality/Unreality, have some dissociative symptoms, and the 3.33% presented a clear dissociative identity disorder. All were free from psychosis or neurologic disorders. A new questionnaire to study fantasy in children and adolescents was validated. Many children and adolescents of the general population declared Perception-like experiences. These events seem to be specific, and probably normal, features of the mind; they could be better named as "Dreamtime," whereas only in extreme conditions they could represent a risk for dissociation.

Selective Aerobic Oxidation of 5-Hydroxymethylfurfural to 2,5-Diformylfuran or 2-Formyl-5-furancarboxylic Acid in Water by using MgO⋠CeO2 Mixed Oxides as Catalysts.

Mixed oxides based on MgO⋅CeO2 were used as efficient catalysts in the aerobic oxidation of 5-hydroxymethylfurfural (5-HMF) to afford, with very high selectivity, either 2,5-diformylfuran (DFF, 99 %) or 2-formyl-5-furancarboxylic acid (FFCA, 90 %), depending on the reaction conditions. 5-Hydroxymethyl-2-furancarboxylic acid (HMFCA, 57-90 %) was formed only at low concentration of 5-HMF (<0.03 m) or in presence of external bases. The conversion of 5-HMF ranged from a few percent to 99 %, according to the reaction conditions. The oxidation was performed in water, with O2 as oxidant, without any additives. The surface characterization of the catalysts gave important information about their acid-base properties, which drive the selectivity of the reaction towards DFF. FFCA was formed from DFF at longer reaction times. Catalysts were studied by XPS and XRD before and after catalytic runs to identify the reason why they undergo reversible deactivation. XRD showed that MgO is hydrated to Mg(OH)2 , which, even if not leached out, changes the basic properties of the catalyst that becomes less active after some time. Calcination of the recovered catalyst allows recovery of its initial activity. The catalyst is thus recoverable (>99 %) and reusable. The use of mixed oxides allows tuning of the basicity of the catalysts, avoiding the need for external bases for efficient and selective conversion of 5-HMF and waste formation, resulting in an environmentally friendly, sustainable process.

Chilling causes perivitelline granule formation in activated zebrafish oocytes.

Chilling sensitivity in oocytes of the zebrafish represents a potential obstacle to their successful cryopreservation. Here, we report the first cryomicroscopic observations of the response of zebrafish oocytes to chilling conditions. In activated stage V oocytes that had been exposed to hypothermic temperatures, we observed a latent effect of chilling, manifesting as a granular precipitate that appeared in the perivitelline fluid upon return to 28.5 °C. The granules were visible in unstained oocytes under transmitted light microscopy, and the resulting perivitelline turbidity increased in a dose-dependent manner with decreasing chilling temperature (p < 0.001), as well as with increasing time of hypothermic exposure (p < 0.0001). The change in appearance of the perivitelline space in oocytes that had been chilled and rewarmed became statistically significant after a 7-min exposure to 10 °C and after only 30 s at 1 °C (p < 0.05). Thus, even moderate chilling exposures can lead to detectable changes in activated zebrafish oocytes.

Sustainable Synthesis of Oxalic and Succinic Acid through Aerobic Oxidation of C6 Polyols Under Mild Conditions.

The sustainable chemical industry encompasses a shift from the use of fossil carbon to renewable carbon. The synthesis of chemicals from nonedible biomass (cellulosic or oil) represents one of the key steps for "greening" the chemical industry. In this paper, we report the aerobic oxidative cleavage of C6 polyols (5-HMF, glucose, fructose and sucrose) to oxalic acid (OA) and succinic acid (SA) in water under mild conditions using M@CNT and M@NCNT (M=Fe, V; CNT=carbon nanotubes; NCNT=N-doped CNT), which, under suitable conditions, were recoverable and reusable without any loss of efficiency. The influence of the temperature, O2 pressure (PO2 ), reaction time and stirring rate are discussed and the best reaction conditions are determined for an almost complete conversion of the starting material and a good OA yield of 48 %. SA and formic acid were the only co-products. The former could be further converted into OA by oxidation in the presence of formic acid, resulting in an overall OA yield of >62 %. This process was clean and did not produce organic waste nor gas emissions.

Selective Oxidation of 5-(Hydroxymethyl)furfural to DFF Using Water as Solvent and Oxygen as Oxidant with Earth-Crust-Abundant Mixed Oxides.

5-Hydroxymethylfurfural (5-HMF) can be considered a prominent building block: because of the presence of the alcohol and aldehyde moieties, it can be used to generate useful molecules as chemicals of industrial interest with high added value, monomers for polymers, and even fuels. This article shows how building up mixed oxides of different complexities and properties may drive the selectivity toward one of the possible products generated from 5-HMF. In particular, mixed oxides based on cerium and other metals abundant on the earth-crust perform the selective oxidation of 5-HMF to 2,5-diformylfuran (94%), using oxygen as oxidant and water as solvent. The roles of the reaction conditions (temperature, reaction time, oxygen pressure, concentration of the substrate), the chemical composition, the acidic/basic properties, and redox properties of the catalysts are discussed.

Biocatalytic and Bioelectrocatalytic Approaches for the Reduction of Carbon Dioxide using Enzymes.

In the recent decade, CO2 has increasingly been regarded not only as a greenhouse gas but even more as a chemical feedstock for carbon-based materials. Different strategies have evolved to realize CO2 utilization and conversion into fuels and chemicals. In particular, biological approaches have drawn attention, as natural CO2 conversion serves as a model for many processes. Microorganisms and enzymes have been studied extensively for redox reactions involving CO2. In this review, we focus on monitoring nonliving biocatalyzed reactions for the reduction of CO2 by using enzymes. We depict the opportunities but also challenges associated with utilizing such biocatalysts. Besides the application of enzymes with co-factors, resembling natural processes, and co-factor recovery, we also discuss implementation into photochemical and electrochemical techniques.

Knockdown of epigenetic transcriptional co-regulator Brd2a disrupts apoptosis and proper formation of hindbrain and midbrain-hindbrain boundary (MHB) region in zebrafish.

Brd2 is a member of the bromodomain-extraterminal domain (BET) family of proteins and functions as an acetyl-histone-directed transcriptional co-regulator and recruitment scaffold in chromatin modification complexes affecting signal-dependent transcription. While Brd2 acts as a protooncogene in mammalian blood, developmental studies link it to regulation of neuronal apoptosis and epilepsy, and complete knockout of the gene is invariably embryonic lethal. In Drosophila, the Brd2 homolog acts as a maternal effect factor necessary for segment formation and identity and proper expression of homeotic loci, including Ultrabithorax and engrailed. To test the various roles attributed to Brd2 in a single developmental system representing a non-mammalian vertebrate, we conducted a phenotypic characterization of Brd2a deficient zebrafish embryos produced by morpholino knockdown and corroborated by Crispr-Cas9 disruption and small molecule inhibitor treatments. brd2aMO morphants exhibit reduced hindbrain with an ill-defined midbrain-hindbrain boundary (MHB) region; irregular notochord, neural tube, and somites; and abnormalities in ventral trunk and ventral nerve cord interneuron positioning. Using whole mount TUNEL and confocal microscopy, we uncover a significant decrease, then a dramatic increase, of p53-independent cell death at the start and end of segmentation, respectively. In contrast, using qualitative and quantitative analyses of BrdU incorporation, phosphohistone H3-tagging, and flow cytometry, we detect little effect of Brd2a knockdown on overall proliferation levels in embryos. RNA in situ hybridization shows reduced or absent expression of homeobox gene eng2a and paired box gene pax2a, in the hindbrain domain of the MHB region, and an overabundance of pax2a-positive kidney progenitors, in knockdowns. Together, these results suggest an evolutionarily conserved role for Brd2 in the proper formation and/or patterning of segmented tissues, including the vertebrate CNS, where it acts as a bi-modal regulator of apoptosis, and is necessary, directly or indirectly, for proper expression of genes that pattern the MHB and/or regulate differentiation in the anterior hindbrain.

Synthesis and Characterization of Fe0 (2,2'-bipyridine) (2-aminoethyl-pyridine) and its Reaction with Dihydrogen.

Fe0 (bpy)(pyea) (2; bpy=2,2'-bipyridine, pyea=2-aminoethyl-pyridine), a 16-electron species, was synthesized by reduction of FeCl2 (bpy)(pyea) (1) using Na-strips. It is a diamagnetic low-melting solid (m.p. 295 K) stable under N2 and easily decomposed by radiations even at low temperature. It was fully characterized by elemental analyses and multinuclear NMR. Complex 2 acts as an active hydrogenation catalyst, but has a very short lifetime. In fact, it reacts with H2 (0.1-1 MPa) at room temperature in toluene and affords in a few minutes a new Fe0 complex characterized as Fe0 (bpy)(η6 -picoline) (3), inactive to hydrogenation. Picoline is derived from the sp3 -sp3 C-C bond cleavage of the aminoethyl arm of the pyea ligand. The rapid evolution of the putative intermediate FeH2 (bpy)(pyea) (4) has not allowed the isolation such Fe-hydrido species. The interaction of H2 with 2 has been studied by DFT, which has allowed to demonstrate that 3 is lower in energy than 2+H2 , justifying the fact that the intermediate dihydride was not isolated. Interestingly, 3 was also obtained by reaction of 1 with NaBH4 or with glycerol-KOH. Complex 2 is one of the rare examples of Fe0 complex stabilized by a set of only N-donor atoms. The reaction with glycerol confirms the potential role of Fe in catalytic hydrogenation reactions using bio-glycerol as a H-source.

Across the Board: Angela Dibenedetto.

In this series of articles, the board members of ChemSusChem discuss recent research articles that they consider of exceptional quality and importance for sustainability. This entry features Prof. Angela Dibenedetto, who highlights the differences between natural and artificial photosynthesis, suggesting that solar chemistry may be the most appropriate terminology to describe these closely related solar-to-chemical energy conversion processes.

Photocatalytic Carbon Dioxide Reduction at p-Type Copper(I) Iodide.

A p-type semiconductor, CuI, has been synthesized, characterized, and tested as a photocatalyst for CO2 reduction under UV/Vis irradiation in presence of isopropanol as a hole scavenger. Formation of CO, CH4 , and/or HCOOH was observed. The photocatalytic activity of CuI was attributed to the very low potential of the conduction band edge (i.e., -2.28 V vs. NHE). Photocurrents generated by the studied material confirm a high efficiency of the photoinduced interfacial electrontransfer processes. Our studies show that p-type semiconductors may be effective photocatalysts for CO2 reduction, even better than extensively studied n-type titanium dioxide, owing to the low potential of the conduction band edge.

Selective Aerobic Oxidation of 5-(Hydroxymethyl)furfural to 5-Formyl-2-furancarboxylic Acid in Water.

A simple, cheap, and selective catalyst based on copper/cerium oxides is described for the oxidation of 5-(hydroxymethyl)furfural (5-HMF) in water. An almost quantitative conversion (99 %) with excellent (90 %) selectivity towards the formation of 5-formyl-2-furancarboxylic acid, a platform molecule for other high value chemicals, is observed. The catalyst does not require any pretreatment or additives, such as bases, to obtain high yield and selectivity in water as solvent and using oxygen as oxidant. When a physical mixture of the oxides is used, low conversion and selectivity are observed. Air can be used instead of oxygen, but a lower conversion rate is observed if the same overall pressure is used, and the selectivity remains high. The catalyst can be recovered almost quantitatively and reused. Deactivation of the catalyst, observed in repeated runs, is due to the deposition of humins on its surface. Upon calcination the catalyst almost completely recovers its activity and selectivity, proving that the catalyst is robust.

The need to implement an efficient biomass fractionation and full utilization based on the concept of "biorefinery" for a viable economic utilization of microalgae.

In the present work, microalgae strains, such as Scenedesmus obliquus and Phaeodactylum tricornutum grown in indoor/outdoor photobioreactors (PBRs) and in open ponds (this is the first study on such strains cultivated in the local Southern Italy climatic conditions), were fully analyzed for their protein content, carbohydrates, lipids, and fatty acid profile in order to assess their potential use for the production of biofuels, chemicals, and omega-3, and as animal feed and human food. They are compared with Nannochloropsis sp. (commercial sample) which was fully analyzed in our laboratory and Chlorella (literature data). An economic evaluation was carried out, demonstrating that the cultivation of microalgae for the production of only biofuels will not match the economic standards. Conversely, if chemicals are also produced applying the biorefinery concept and using wastewater as a source of nutrients, it will be possible to have a good positive return from microalgae.

Organic Carbonates: Efficient Extraction Solvents for the Synthesis of HMF in Aqueous Media with Cerium Phosphates as Catalysts.

We describe a process for the selective conversion of C6 -polyols into 5-hydroxymethylfurfural (5-HMF) in biphasic systems of organic carbonate/water (OC/W), with cerium(IV) phosphates as catalysts. Different reaction parameters such as the OC/W ratio, catalyst loading, reaction time, and temperature, were investigated for the dehydration of fructose. Under the best reaction conditions, a yield of 67.7 % with a selectivity of 93.2 % was achieved at 423 K after 6 h of reaction using [(Ce(PO4)1.5 (H2 O)(H3 O)0.5 (H2 O)0.5)] as the catalyst. A maximum yield of 70 % with the same selectivity was achieved after 12 h. At the end of the reaction, the catalyst was removed by centrifugation, the organic phase was separated from water and evaporated in vacuo (with solvent recovery), and solid 5-HMF was isolated (purity >99 %). The recovery and reuse of the catalyst and the relationship between the structure of the OC and the efficiency of the extraction are discussed. The OC/W system influences the lifetime of the catalysts positively compared to only water.