Microwave-assisted extractions of active ingredients from plants

Microwave-assisted extraction (MAE) is widely employed in the analysis and the extraction of active compounds from plants. This review summarizes the research done during the last decade on the MAE of active ingredients from plants. Advances and modifications to improve the performance of MAE are presented and discussed in detail. Modified MAE such as vacuum microwave-assisted extraction (VMAE), nitrogen-protected microwave-assisted extraction (NPMAE), ultrasonic microwave-assisted extraction (UMAE), dynamic microwave-assisted extraction (DMAE) and other advancements in MAE are also detailed in this article. In addition, the microwave extraction procedures and the important parameters influencing its performance are also included, together with the advantages and the drawbacks of each MAE techniques.     

Separation of oxidized variants of a monoclonal antibody by anion-exchange

Monoclonal antibodies are subject to a variety of degradation mechanisms, therefore orthogonal techniques are required to demonstrate product quality. In this study, the three individual antibodies comprising a multi-antibody drug product, XOMA 3AB were evaluated by both cation-exchange (CEX) and anion-exchange chromatography (AEX). In contrast to CEX analysis which showed only a single, broad peak for the force-oxidized antibodies, AEX analysis of Ab-A (pI=7.6) revealed two more basic peaks. Ab-B (pI=6.7) bound but exhibited only a single major peak while Ab-C (pI=8.6) flowed through. Peptide mapping LC/MS analysis of the isolated Ab-A fractions demonstrated that the basic peaks resulted from oxidation in a complementary determining region (CDR). Differential scanning calorimetry (DSC) analysis of the oxidized Ab-A species showed a decrease in the Fab melting point for the oxidized species consistent with unfolding of the molecule. Greater/lesser surface exposure of ionic residues resulting from a conformational change provides a likely explanation for the dramatic shift in retention behavior for the Ab-A oxidized variants. Peptide mapping analysis of the Ab-B antibody showed, in contrast to Ab-A, no detectable CDR oxidation. Hence, the lack of separation of oxidized variants in Ab-B can be explained by the absence of CDR oxidation and the associated changes in secondary/tertiary structure which were observed for oxidized Ab-A. In summary, anion-exchange HPLC shows potential as an orthogonal analytical technique for assessing product quality of monoclonal antibody therapeutics. In the case of the XOMA 3AB drug product, two of the antibodies bound and one, Ab-A, exhibited separation of CDR oxidized variants.     

Application of Li2SiO3 as a heterogeneous catalyst in the production of biodiesel from soybean oil

Biodiesel was synthesized from soybean oil by transesterification over Li₂SiO₃ catalyst.The Li₂SiO₃ can be used for biodiesel production directly without further drying or thermal pretreatment,no obvious difference in the FAME conversion（92.4-96.7%） between the air-exposed catalyst（24-72 h） and the fresh one（94.2%）.This leads to important benefits when considering industrial applications of Li₂SiO₃ as a solid catalyst for storing and handling catalyst without taking special actions.     

The development of anisotropic behaviours of 3T3 fibroblasts on microgrooved patterns

3T3 fibroblasts cultured on microgrooved polydimethylsiloxane (PDMS) surfaces of two different widths (25μm and 55μm) were individually tracked using confocal microscopy with a novel live-cell staining technique over several hours without noticeable cytotoxic effects. By quantifying the cell morphology, orientation, and migration over time, we identified the timescale (about 2-4h after seeding) over which cell behaviours transitioned from isotropy to anisotropy, where the preference is in the direction parallel to the pattern. The development of anisotropy occurred more rapidly and distinctly when a narrower ridge width was used, suggesting that it is the ridge width that imposed a physical barrier on the cells' morphology and motility. Furthermore, while we found a weak but statistically significant correlation between cell orientation and morphology on the single-cell level, there is a lack of correlation on the same level between cell orientation and migratory direction. This suggests that while morphology and migration are affected anisotropically by topographical patterns in a similar way, the underlying processes giving rise to the anisotropy is slightly different in the two cases.     

Sub-single-cycle optical pulse train with constant carrier envelope phase

We describe the synthesis of periodic waveforms consisting of a train of pulses that are 0.83 cycles long and have an electric field pulse width of 0.44 fs using 7 Raman sidebands generated by molecular modulation in H2. We verify by optical correlation that the carrier-envelope phase is constant in these waveforms when they are synthesized from commensurate sidebands. The estimated overall shift of the carrier-envelope phase is less than 0.18 cycles from the first to the last pulse of nearly 10(6) pulses in the pulse train.     

Synthesis and Study of an N,N‐Disubstituted 4‐[(4‐Aminophenyl)diazenyl]benzaldehyde

An N,N‐disubstituted 4‐[(4‐aminophenyl)diazenyl]benzaldehyde (‘azo dye') with nematic phase was synthesized by reaction of the phenylpiperazine derivative with the formylbenzenediazonium salt. The salt was prepared by a simplified reaction of poly(aminobenzaldehyde) with NaNO₂ in the presence of HBF₄. The azo dye was further studied by crystallography. On the basis of molecular stacking identified from crystallography, the molecular modeling was carried out to explore the molecular interactions, and it was found that the attraction of two coplanar molecules with side‐to‐side contact is favored, and a nematic phase is thus formed during the thermal process.     

Ester–amide exchange in blends of liquid‐crystalline copolyester and polyamide 6

The kinetics of the ester–amide exchange in solution blends of the random liquid‐crystalline polyester copoly(oxybenzoate‐terephthalate) (P64) and polyamide 6 (PA6) were studied with carbon nuclear magnetic resonance. With second‐order reversible reactions assumed, the activation energy of the ester–amide interchange in 30/70, 50/50, and 70/30 P64/PA6 blends were all about 24.0 kcal/mol. The pre‐exponential factors for the ester–amide exchange in 30/70, 50/50, and 70/30 P64/PA6 blends were 2.01 × 10¹¹, 2.59 × 10¹⁰, and 2.74 × 10¹² min⁻¹, respectively. © 2000 John Wiley & Sons, Inc. J Polym Sci B: Polym Phys 38: 2124–2135, 2000