Understanding the Surface Characteristics of Biochar and Its Catalytic Activity for the Hydrodeoxygenation of Guaiacol

Biochar (BCR) was obtained from the pyrolysis of a palm-oil-empty fruit bunch at 773 K for 2 h and used as a catalyst for the hydrodeoxygenation (HDO) of guaiacol (GUA) as a bio-oil model compound. Brunauer–Emmet–Teller surface area analysis, NH3 and CO2-temperature-programmed desorption, scanning electron microscope–dispersive X-ray spectroscopy, CHN analysis and X-ray fluorescence spectroscopy suggested that macroporous and mesoporous structures were formed in BCR with a co-presence of hydrophilic and hydrophobic sites and acid–base behavior. A combination of infrared, Raman and inelastic neutron scattering (INS) was carried out to achieve a complete vibrational assignment of BCR. The CH–OH ratio in BCR is ~5, showing that the hydroxyl functional groups are a minority species. There was no evidence for any aromatic C–H stretch modes in the infrared, but they are clearly seen in the INS and are the majority species, with a ratio of sp3–CH:sp2–CH of 1:1.3. The hydrogen bound to sp2–C is largely present as isolated C–H bonds, rather than adjacent C–H bonds. The Raman spectrum shows the characteristic G band (ideal graphitic lattice) and three D bands (disordered graphitic lattice, amorphous carbon, and defective graphitic lattice) of sp2 carbons. Adsorbed water in BCR is present as disordered layers on the surface rather than trapped in voids in the material and could be removed easily by drying prior to catalysis. Catalytic testing demonstrated that BCR was able to catalyze the HDO of GUA, yielding phenol and cresols as the major products. Phenol was produced both from the direct demethoxylation of GUA, as well as through the demethylation pathway via the formation of catechol as the intermediate followed by deoxygenation.

Hydrogen and Usability of Hydrogen Storage Technologies

Science, technology and politics agree: hydrogen will be the energy carrier of the future. It will replace fossil fuels based on a sufficient supply from sustainable energy. Since the possibilities of storing and transporting hydrogen play a decisive role here, the so-called LOHC (Liquid Organic Hydrogen Carriers) can be used as carrier materials. LOHC carrier materials can reversibly absorb hydrogen, store it without loss and release it again when needed. Since little or no pressure is required, normal containers or tanks can be used. The volume or mass-related energy densities can reach around a quarter of liquid fossil fuels. This paper is to give an introduction to the field of hydrogen storage and usage of those LOHC, in particular. The developments of the last ten years have been related to the storage and transport of hydrogen with LOHC. These are crucial to meet the future demand for energy carriers e.g. for mobile applications. For this purpose, all transport systems are under consideration as well as the decentralized supply of rural areas with low technological penetration, e.g. regions of Western Africa which are often characterized by a lack of energy supply. Hydrogen bound in LOHC can provide a hazard-free alternative for distribution. The paper provides an overview of the conversion forms as well as the chemical carrier materials. Dibenzyltoluene as well as N-ethylcarbazole - as examples for LOHC - are discussed as well as chemical hydrogen storage materials like ammonia boranes as alternatives to LOHC.

Gd3+ Complexes Conjugated to Cyclodextrins: Hydroxyl Functions Influence the Relaxation Properties

In the search for improvement in the properties of gadolinium-based contrast agents, cyclodextrins (CDs) are interesting hydrophilic scaffolds with high molecular weight. The impact of the hydrophilicity of these systems on the MRI efficacy has been studied using five β-CDs substituted with DOTA or TTHA ligands which, respectively, allow for one (q = 1) or no water molecule (q = 0) in the inner coordination sphere of the Gd3+ ion. Original synthetic pathways were developed to immobilize the ligands at C-6 position of various hydroxylated and permethylated β-CDs via an amide bond. To describe the influence of alcohol and ether oxide functions of the CD macrocycle on the relaxation properties of the Gd3+ complexes, 1H Nuclear Magnetic Relaxation Dispersion (NMRD) profiles, and 17O transverse relaxation rates have been measured at various temperatures. The differences observed between the hydroxylated and permethylated β-CDs bearing non-hydrated GdTTHA complexes can be rationalized by a second sphere contribution to the relaxivity in the case of the hydroxylated derivatives, induced by hydrogen-bound water molecules around the hydroxyl groups. In contrast, for the DOTA analogs the exchange rate of the water molecule directly coordinated to the Gd3+ is clearly influenced by the number of hydroxyl groups present on the CD, which in turn influences the relaxivity and gives rise to a very complex behavior of these hydrophilic systems.

Femtochemistry of bimolecular reactions from weakly bound complexes: computational study of the H + H'OD → H'OH + D / HOD + H' exchange reactions

A full-dimensional wavepacket propagation describing the bimolecular exchange reactions H + H'OD → H'OH + D / HOD + H' initiated by photolysis of HCl in the hydrogen-bound complex (HCl)···(HOD)...

Effects of DMSO on the Pluripotency of Cultured Mouse Embryonic Stem Cells (mESCs)

DMSO is a commonly used solvent in biological studies, as it is an amphipathic molecule soluble in both aqueous and organic media. For that reason, it is the vehicle of choice for several water-insoluble substances used in research. At the molecular and cellular level, DMSO is a hydrogen-bound disrupter, an intercellular electrical uncoupler, and a cryoprotectant, among other properties. Importantly, DMSO often has overlooked side effects. In stem cell research, the literature is scarce, but there are reports on the effect of DMSO in human embryoid body differentiation and on human pluripotent stem cell priming towards differentiation, via modulation of cell cycle. However, in mouse embryonic stem cell (mESC) culture, there is almost no available information. Taking into consideration the almost ubiquitous use of DMSO in experiments involving mESCs, we aimed to understand the effect of very low doses of DMSO (0.0001%-0.2%), usually used to introduce pharmacological inhibitors/modulators, in mESCs cultured in two different media (2i and FBS-based media). Our results show that in the E14Tg2a mESC line used in this study, even the smallest concentration of DMSO had minor effects on the total number of cells in serum-cultured mESCs. However, these effects could not be explained by alterations in cell cycle or apoptosis. Furthermore, DMSO did not affect pluripotency or differentiation potential. All things considered, and although control experiments should be carried out in each cell line that is used, it is reasonable to conclude that DMSO at the concentrations used here has a minimal effect on this particular mESC line.

Investigation of the nature of hydrogen bonds in 3,5-dimethylpyrazole

Compounds containing a pyrazole fragment in their structure are part of many medicines and have a wide range of bioactivity (for example, antimicrobial, anti-tuberculosis, etc.), and are also successfully used for the development of various synthetic anti-tumor agents. Interest in them is also caused by the presence of hydrogen bonds, which are the main motive for self-organization of molecules. A theoretical study of the nature of hydrogen bonds in various hydrogen-bound motifs in 3,5-dimethylpyrazole was performed using the DFT/B3LYP/6-31G(d,p) method. The results obtained indicate the possible existence of dimeric, trimeric, and tetrameric cyclic forms. Geometric and energy parameters of hydrogen bonds N-H...N are determined and the energies of donor-acceptor interaction in possible forms of self-organization of the molecules of the studied compound are calculated. It has been established that the hydrogen bond (H-bond) is the result of the interaction of a hybrid unshielded pair of a nitrogen atom of one molecule and a loosening natural orbital between the nitrogen atoms of one molecule and the hydrogen of another molecule (σ* N-H). The formation of the binding σ-orbital of the H-bond indicates the predominance of covalent interaction in the hydrogen bond. The study and analysis of the results showed that the formation of supramolecular systems of 3,5-dimethylpyrazole most likely structures are trimers and tetramers.

Generation of the 1H in H2O neutron thermal scattering law covariance matrix of the CAB model

The thermal scattering law (TSL) of 1H in H2O describes the interaction of the neutron with the hydrogen bound to light water. No recommended procedure exists for computing covariances of TSLs available in the international evaluated nuclear data libraries. This work presents an analytic methodology to produce such a covariance matrix-associated to the water model developed at the Atomic Center of Bariloche (Centro Atomico Bariloche, CAB, Argentina). This model is called as CAB model, it calculates the TSL of hydrogen bound to light water from molecular dynamic simulations. The performance of the obtained covariance matrix has been quantified on integral calculations at “cold” reactor conditions between 20 and 80∘ C. For UOX fuel, the uncertainty on the calculated reactivity ranges from ±71 to ±155 pcm. For MOX fuel, it ranges from ±110 to ±203 pcm.