Improvement in the remaining activity of freeze-dried xanthine oxidase with the addition of a disaccharide–polymer mixture

In order to improve the remaining activity of a practically important freeze-dried enzyme, xanthine oxidase (XOD), the effects of disaccharide (sucrose and trehalose), polymer (bovine serum albumin: BSA and dextran) and a mixture of them on the loss of XOD activity during freeze-drying and subsequent storage were investigated. All samples were amorphous solids and their glass transition temperatures (T_g) were evaluated by using differential scanning calorimetry. Although dextran showed no stabilizing effect on the freeze-dried XOD, the others protected XOD from the activity loss during freeze-drying to a certain extent. It was found that the mixture of disaccharide (sucrose or trehalose) and BSA improved the XOD activity synergistically. The XOD activity of the samples decreased gradually during storage at a temperature range of between 25 and 60 °C. Samples stored at temperatures below the T_g showed a lower loss of XOD activity than those stored at just the T_g.     

Shaping futures: A dialogue on chemical engineering education

Engineering as a discipline, profession, practice, and area of study continues to add substantial value in an increasingly complex world. With continually evolving complexity around the planet, such as the need for massive energy transition, global health technologies, or sustainable food systems, how might engineering education practices and theory be considered within these rapid and necessary changes? This paper presents an experiment of co-creation through experiential reflection about the state of chemical engineering education. Four chemical engineering professors engaged in a dialogue, facilitated by a researcher in education, through collaborative and actionable research. This dialogue uncovered innovative possibilities, educational themes, experiences, and opportunities for others in the profession to consider. The process of dialogue also encouraged the development of an imaginative future sense-making, known as futuring, through a collective experience. The findings reveal instructive perspectives on the shape of chemical engineering education that should be of value not only to engineers, but also other professionals, practitioners, or those in various science, technology, and math fields.     

Sintering Metal–Organic Framework Gels for Application as Structural Adhesives

Metal–organic frameworks (MOFs)/coordination polymers are promising materials for gas separation, fuel storage, catalysis, and biopharmaceuticals. However, most applied research on MOFs is limited to these functional materials thus far. This study focuses on the potential of MOFs as structural adhesives. A sintering technique is applied to a zeolitic imidazolate framework-67 (ZIF-67) gel that enables the joining of Cu substrates, resulting in a shear strength of over 30 MPa, which is comparable to that of conventional structural adhesives. Additionally, systematic experiments are performed to evaluate the effects of temperature and pressure on adhesion, indicating that the removal of excess 2-methylimidazole and the by-product (acetic acid) from the sintered material by vaporization results in a microstructure composed of large spherical ZIF-67 crystals that are densely aggregated, which is essential for achieving a high shear strength.     

Fabrication of hierarchically porous spherical particles by assembling mesoporous silica nanoparticles via spray drying

A new type of hierarchically porous materials is fabricated by assembling mesoporous nanoparticles via spray drying. Well-dispersed mesostructured silica nanoparticles (MSN), whose particle size distribution was narrow in the range of 20 nm and 50 nm, were prepared by a thermal deposition method. By spray drying a MSN suspension, MSN were assembled into spherical secondary particles. After calcination, the spherical particles have two types of mesopores, mesopores of 3 nm in size inside of calcined MSN and larger inter-nanoparticle mesopores of about 15-20 nm. This hierarchical pore system should provide nanospaces for efficient mass transport of guest species with different sizes.     

Electron-beam-induced-current investigation of GaN/AlGaN/Si heterostructures using scanning transmission electron microscopy

An electron-beam-induced-current technique has been applied to scanning transmission electron microscopy to characterize GaN/AlGaN/n-Si heterostructures. The structure was formed by metalorganic vapor phase epitaxy using AlGaN as an intermediate layer. Two samples with nominal intermediate layer thicknesses of 60 and 120 nm were studied. It was found that there is a junction in the n-type Si region underneath the nitride/Si interface irrespective of the intermediate layer thickness, whereas induced current occurred neither in the nitride region nor at the nitride/Si interface. The junction formed was found to be undulated. The sample with the thin intermediate layer had undulations of a shorter periodicity than that with the thick intermediate layer. The formation of the junction is attributed to the diffusion of Al during the nitride growth.     

Detection of six single-nucleotide polymorphisms associated with rheumatoid arthritis by a loop-mediated isothermal amplification method and an electrochemical DNA chip

An electrochemical DNA chip using an electrochemically active intercalator and DNA probe immobilized on a gold electrode has been developed for genetic analysis. In this study, the six polymorphisms associated with rheumatoid arthritis (RA), N-acetyltransferase2 (NAT2) gene polymorphisms T341C, G590A, and G857A, methylenetetrahydrofolate reductase (MTHFR) gene polymorphisms C677T and A1298C, and serum amyloid A1 (SAA1) gene promoter polymorphism C-13T were simultaneously detected by the electrochemical DNA chip and the loop-mediated isothermal amplification (LAMP) method, which is a novel technique for DNA amplification. Human genomic DNAs were extracted from blood, and the targets containing the six polymorphisms were amplified by the LAMP method. A sample containing the six LAMP products was reacted with the electrochemical DNA chip using a DNA detection system that controls hybridization reaction, washing, electrochemical detection, and data analysis automatically. A total of 31 samples were genotyped by this method, and the results were completely consistent with those determined by the polymerase chain reaction-restriction fragment length polymorphism (PCR-RFLP) analysis or the PCR direct sequence analysis. The time required for this method was only 2 h, and operations were very simple. Therefore, this method is expected to contribute to personalized medicine based on genotype.     

Development of a neutron personal dose equivalent detector

A new neutron-measuring instrument that is intended to measure a neutron personal dose equivalent, H(p)(10) was developed. This instrument is composed of two parts: (1) a conventional moderator-based neutron dose equivalent meter and (2) a neutron shield made of borated polyethylene, which covers a backward hemisphere to adjust the angular dependence. The whole design was determined on the basis of MCNP calculations so as to have response characteristics that would generally match both the energy and angular dependencies of H(p)(10). This new instrument will be a great help in assessing the reference values of neutron H(p)(10) during field testing of personal neutron dosemeters in workplaces and also in interpreting their readings.     

Coexpression of platelet-derived growth factor receptor alpha and fetal liver kinase 1 enhances cardiogenic potential in embryonic stem cell differentiation in vitro

Nascent mesodermal cells derived from EB5 embryonic stem (ES) cells were sorted in terms of cardiogenic potential on the basis of their expression levels of platelet-derived growth factor receptor alpha (PDGFRalpha) and fetal liver kinase 1 (Flk-1). The sorted cells were cocultured with OP9 stromal cells to induce terminal differentiation into contractile cardiac colonies. A significant number of cardiac colonies were found in the Flk-1+/PDGFRalpha+ fraction. The enrichment double-positive fraction produced approximately fivefold more cardiac colonies than the Flk-1+/PDGFRalpha- fraction and 10-fold more than the Flk-1-/PDGFRalpha+ fraction. To investigate the involvement of these markers in embryonic cardiogenesis, the cells that disseminated from the E7.5-7.75 embryos were fractionated and seeded on OP9 cells. The cardiogenic potential was markedly enhanced in the Flk-1+/PDGFRalpha+ fraction. These results suggest that some of the precursor cells coexpressing these markers are selectively involved in cardiogenic events, and that the identification of ES-cell-derived precursors with these markers will contribute to the effective production of cardiomyocytes for cell therapies.     

Effects of inhibitors on anaerobic microbial consortium with enhanced dechlorination activity in polychlorinated biphenyl mixture

Characterization was carried out on the anaerobic microbial consortium with enhanced degradation activity toward polychlorinated biphenyls in Kanechlor-300 and Kanechlor-400 mixtures in a burnt soil (BS) culture. The addition of molybdate to the BS culture resulted in the accumulation of less-chlorinated biphenyls such as 4,4'-dichlorinated biphenyl and 2,3',4-trichlorinated biphenyl; however, no such accumulation occurred without molybdate supplementation. No significant effect was observed in individual congeners in the BS culture supplemented with 2-bromoethane sulfonic acid. Analyses involving both the polymerase chain reaction-denaturing gradient gel electrophoresis of partial 16S rRNA genes and respiratory quinones showed that the predominant microorganisms in the BS culture were anaerobic Firmicutes, while sulfate reducers of the phyla Deltaproteobacteria, Firmicutes and Chloroflexi were absent in the culture amended with the inhibitors. No positive correlation was observed between the dechlorination activity and a PCR-based detection of gene fragments of known dechlorinating bacteria. These results suggest that sulfate reducers played an important role in the enhanced anaerobic dechlorination of PCBs in the BS culture.