Morphologically tuned CuO-ZnO-CeO2 catalyst for CO2 hydrogenation to methanol

Morphologically modified composite CuO-ZnO-CeO2 catalysts were synthesized using a single-step hydrothermal technique. The study highlights the influence of solvent on the structural and physico-chemical properties of the catalysts. Various techniques, such as XRD, FE-SEM, BET, XPS, and H2-TPR, were used to analyze the catalyst properties. Among the synthesized materials, the catalyst, prepared with a N,N-dimethyl formamide (DMF)-to-metal nitrates ratio of 20 (named as CZC-1), showed enhanced active sites in the form of surface features such as nanowire-like morphology, large surface area, low crystallite size, increased oxygen vacancies, and high CuO dispersion. A bench-scale fixed-bed flow reactor was used to examine the catalytic performance of the catalysts. At 225 °C reactor temperature, 30 bar reactor pressure, and with a space velocity of 6000 cm3 gcat-1 h-1, the CZC-1 catalyst showed 13.6% CO2 conversion and 74.1% methanol selectivity. In situ diffuse reflectance infrared Fourier transform spectroscopy (DRIFTS) analysis confirmed the carbonate-formate-methoxy reaction pathway for methanol formation using the CZC-1 catalyst.

Electro-Oxidation Reaction of Methanol over La2-xSrxNi1-y(Mn/Fe/Co)yO4+δ Ruddlesden-Popper Oxides

Solution combustion-synthesized Ruddlesden-Popper oxides La1.4Sr0.6Ni0.9(Mn/Fe/Co)0.1O4+δ were explored for the methanol electro-oxidation reaction. With optimal doping of Sr2+ in the A site and Co2+ in the B site, Ni3+ with t2g6 d x 2 - y 2 1 configuration in La1.4Sr0.6Ni0.9Co0.1O4+δ exhibited a tetragonal distortion with compression in axial bonds and elongation in equatorial bonds. This structural modification fostered an augmented overlap of d z 2 orbitals with axial O 2p orbitals, leading to a heightened density of states at the Fermi level. Consequently, this facilitated not only elevated electrical conductivity but also a noteworthy reduction in the charge transfer resistance. These effects collectively contributed to the exceptional methanol oxidation activity of La1.4Sr0.6Ni0.9Co0.1O4+δ, as evidenced by an impressive current density of 21.4 mA cm-2 and retention of 95% of initial current density even after 10 h of prolonged reaction. The presence of Ni3+ further played a pivotal role in the creation of NiOOH, a crucial intermediate species, facilitated by the presence of surface oxygen vacancies. These factors synergistically enabled efficient methanol oxidation. In summary, our present study not only yields substantial insights but also paves the way for a novel avenue to fine-tune the activity of Ruddlesden-Popper oxides for the successful electro-oxidation of methanol.

Technological solutions for NOx, SOx, and VOC abatement: recent breakthroughs and future directions

NOx, SOx, and carbonaceous volatile organic compounds (VOCs) are extremely harmful to the environment, and their concentrations must be within the limits prescribed by the region-specific pollution control boards. Thus, NOx, SOx, and VOC abatement is essential to safeguard the environment. Considering the importance of NOx, SOx, and VOC abatement, the discussion on selective catalytic reduction, oxidation, redox methods, and adsorption using noble metal and non-noble metal-based catalytic approaches were elaborated. This article covers different thermal treatment techniques, category of materials as catalysts, and its structure-property insights along with the advanced oxidation processes and adsorption. The defect engineered catalysts with lattice oxygen vacancies, bi- and tri-metallic noble metal catalysts and non-noble metal catalysts, modified metal organic frameworks, mixed-metal oxide supports, and their mechanisms have been thoroughly reviewed. The main hurdles and potential achievements in developing novel simultaneous NOx, SOx, and VOC removal technologies are critically discussed to envisage the future directions. This review highlights the removal of NOx, SOx, and VOC through material selection, properties, and mechanisms to further improve the existing abatement methods in an efficient way.

Developmental trends in CO2 methanation using various catalysts

Co₂ methanation-two edged sword to counter global warming and energy crisis.

Heterojunction ZnWO4/ZnFe2O4 composites with concerted effects and integrated properties for enhanced photocatalytic hydrogen evolution

A novel co-catalyst free ZnWO₄/ZnFe₂O₄ heterojunction composite was successfully synthesized using a facile co-precipitation method for photocatalytic H₂ evolution.

Role of Hydrogen and Oxygen Activation over Pt and Pd-Doped Composites for Catalytic Hydrogen Combustion

Removal of excess amount of hydrogen in a catalytic route is a safety measure to be implemented in fuel cell technologies and in nuclear power plants. Hydrogen and oxygen activation are crucial steps for hydrogen combustion that can be achieved by modifying supports with suitable noble metals. In the present study, Pt- and Pd-substituted Co₃O₄-ZrO₂ (CZ) were synthesized using PEG-assisted sonochemical synthesis. Ionic states of Pt and Pd in CZ supports were analyzed by X-ray photoelectron spectroscopy. Pd and Pt improved H₂ and O₂ activation extensively, which reduced the temperature of 50% conversion (T_50%) to 33 °C compared with the support (CZ). The activation energy of PdCZ catalyst was decreased by more than 2 folds (13.4 ± 1.2 kJ mol^-1) compared with CZ (34.3 ± 2.3 kJ mol^-1). The effect of oxygen vacancies in the reaction mechanism is found to be insignificant with Pt- and Pd-substituted CZ supports. However, oxygen vacancies play an important role when CZ alone was used as catalyst. The importance of hydrogen and oxygen activation as well as the oxygen vacancies in mechanism was studied by H₂-TPD, H₂-TPR, and in situ FTIR spectroscopy.

Macroporous three-dimensional graphene oxide foams for dye adsorption and antibacterial applications

Applicability of graphene oxide foams in water remediation.

Case report: Airway management of a patient with popping pedunculated subglottic laryngeal polyp

Management of airway is a great challenge to anesthesiologists. Sometimes though airway is apparently normal but lesion around it may give a concern for securing airway. Patient, 52 years, ASA grade I presented to otolaryngology clinic with important complaints of stridor and dyspnoea. There was no comorbidity. Routine investigations were normal. Indirect laryngoscopic examination revealed pedunculated mass (polyp) arising from subglottic region, with a size of 0.7 x 0.5 cm and its pedicle was around 1.5 cm long delicate structure. This polyp was not visible during inspiration but it popped out of the vocal cords during expiration. Microlaryngeal surgery was planned to remove this polyp. Intubation of trachea was a great challenge as polyp was visible only during expiration. Tracheal intubation under controlled ventilation and neuromuscular blockade might have caused rupture of polyp pedicle or dislodgement of polyp in the trachea (as its pedicle was quite thin and delicate) which would have resulted in respiratory obstruction in the patient. Fiberoptic guided awake intubation was planned during expiratory phase of spontaneous respiration in order to avoid any injury or damage to the polyp or its pedicle.

The hearing profile among learners in schools in the Western Cape, South Africa

The hearing profile amongst school learners in the Western Cape was investigated. The University of Cape Town's hearing-screening programme at 11 primary schools (n=1101) was audited and revealed a 13.8% referral rate amongst school-aged children. The possible effects of environmental noise on hearing-screening performance at 500Hz was investigated. When the hearing-screening results at 500Hz were excluded from the audit, the referral rate was reduced from 13.8% to 7.9%. The referral rate for hearing-screening failures amongst the learners in the sample was towards the high end of the range for developing countries (3.3-13.9%). More learners had unilateral than bilateral hearing failures while laterality, gender and geographical differences were minimal. This high referral rate suggests a strong need for hearing-screening of the school-aged population.

The role of inter-subunit ionic interactions in the assembly of Physalis mottle tymovirus

Physalis mottle tymovirus (PhMV) is a small spherical plant virus with its RNA genome encapsidated in a protein shell made of 180 identical coat protein (CP) subunits. The amino acid residues involved in two interfacial salt bridges, Asp-83/Arg-159 and Arg-68/Asp-150 and Lys-153, were targeted for mutagenesis with a view to delineate the role of interfacial ionic interactions in the subunit folding and assembly of the virus. R159A and D83A-R159A recombinant CP (rCP) mutants formed stable T = 3 capsids, indicating that the D83-R159 interfacial salt bridge is dispensable for the folding and assembly of PhMV. However, D150A and R68Q-D150A mutant rCPs were present in the insoluble fraction, suggesting that the R68-D150 interfacial salt bridge is crucial for subunit folding and assembly. Similarly, K153Q, D83A-K153Q, and H69A-K153Q mutant rCPs were present in the insoluble fraction. Interestingly, the R68Q-D150A, D83A-K153Q, and H69A-K153Q double mutant rCPs could be refolded into partially folded soluble heterogeneous aggregates of 14-16 S. The results further confirm our earlier observation that subunit folding and assembly are concerted events in PhMV.

Cloning of the pelA gene from Bacillus licheniformis 14A and biochemical characterization of recombinant, thermostable, high-alkaline pectate lyase

The pectate lyase gene pelA from alkaliphilic Bacillus licheniformis strain 14A was cloned and sequenced. The nucleotide sequence corresponded to an open reading frame of 1,026 bp that codes for a 39 amino acid signal peptide and a mature protein with a molecular mass of 33,451 Da. The mature PelA showed significant homology to other pectate lyases belonging to polysaccharide lyase family 1, such as enzymes from different Bacillus spp. and Erwinia chrysanthemi. The pelA gene was expressed in Escherichia coli as a recombinant fusion protein containing a C-terminal His-tag, allowing purification to near homogeneity in a one-step procedure. The values for the kinetic parameters K(m) and Vmax of the fusion protein were 0.56 g/l and 51 micromol/min, respectively. The activity of purified PelAHis was inhibited in the presence of excess substrate. Characterization of product formation revealed unsaturated trigalacturonate as the main product. The yields of unsaturated trigalacturonic acids were further examined for the substrates polygalacturonic acid, citrus pectin and sugar-beet pectin.

Biological factors predisposing to traumatic posterior dislocation of the hip. A selection process in the mechanism of injury

The factors involved in the mechanism leading to traumatic posterior dislocation of the hip are examined. In 47 adult patients who had previously suffered such a dislocation, ultrasound scans were used to measure femoral anteversion on both the affected and the uninjured side. In 36 normal adult volunteers, used as controls, similar measurements were made. Femoral anteversion on both the injured and uninjured side was significantly reduced in the patients compared with the volunteers. These findings are discussed in the light of previous work which indicates that medial rotation is a factor in the mechanism of posterior dislocation of the hip. It is suggested that reduced anteversion acts like medial rotation to make the hip more susceptible to posterior dislocation, and that the less the anteversion the more likely is the injury to be a dislocation rather than a fracture-dislocation. It is concluded that patients who suffer such dislocated hips belong at one extreme of the normal population, having either reduced femoral anteversion or even retroversion, and that this anatomical feature selects towards hip dislocation rather than to injury of the femoral shaft, knee or tibia during the appropriate type of accident.

Chronic Budd-Chiari syndrome due to obstruction of the intrahepatic portion of the inferior vena cava

Clinical features of obstruction of the intrahepatic portion of the inferior vena cava were observed in five out of the 11 patients with the Budd-Chiari syndrome seen during the last four years. These patients apparently formed a distinct group from the remaining six and resembled in clinical course, biochemical features, haemodynamic findings, and radiological investigations the patients described as cases of membranous obliteration of the intrahepatic portion of the inferior vena cava. The present study reports five such patients diagnosed with the help of venous catheterization, percutaneous hepatography, and haemodynamic studies. The value of distinguishing these patients from those with obstruction due to hepatic vein occlusion is highlighted because of the difference in the prognosis and treatment.

Portal hypertension in kala-azar

The present study records haemodynamic studies in three patients with kala-azar, a parasitic disease. All the three patients had high intrasplenic pressure, mild to moderate elevation of wedged hepatic vein pressure, and increased or normal estimated hepatic blood flow. Liver histology showed marked proliferation and swelling of Kupffer cells in the sinusoids. One patient was studied serially for nine months following treatment which showed persistent elevation of intrasplenic pressure though wedge pressure and liver blood flow touched normal levels. Liver biopsy was essentially normal at this stage. These findings may have some relevance to the role of different parasitic infections in the pathogenesis of a heterogeneous group of non-cirrhotic portal fibroses.

Management of bleeding oesophageal varices by draining lymph from the thoracic duct

The thoracic duct was cannulated in six patients who were actively bleeding from varices and had not responded to conservative treatment but draining lymph from the thoracic duct did not control bleeding in five patients. There was no drop in intrasplenic pulp pressure following this procedure when recorded in three of these patients. Bleeding stopped in one patient after lymph had been drained for nine and a half hours, and there was only a modest change in intrasplenic pressure. The therapeutic use of this technique to control oesophageal varices could not be substantiated.