A novel fluorescent sensor for hydrophobic amines in aqueous solution

A novel fluorescent tweezer was designed and synthesised to sense hydrophobic amines in aqueous solution. Association of the guest was driven by both hydrophobic effect and electrostatic interactions, with the hydrophobic interactions being dominant. The affinity and selectivity of the sensor for amine-based stimulants are reported.     

Nile Red and Nile Blue: Applications and Syntheses of Structural Analogues

Nile red and Nile blue are highly fluorescent and photostable organic dyes from the benzo[a]phenoxazine family. They have been used as histological stains for imaging lysosomes and lipids in vitro. The dyes’ high quantum yields and solvent‐dependent optical properties make them ideal scaffolds for the development of pH probes and local polarity indicators. Reviews of the literature in this area are scarce with only one review ever published in 2006. It has been 10 years since and the field has evolved. This review aims to expand upon topics covered by the previous reviewers and to report on recent advances in the literature. As authors, we hope to convey a sense of scope and to spark renewed interest in this useful niche of dye chemistry.     

Polydiacetylene/Anti‐HBs Complexes for Visible and Fluorescent Detection of Hepatitis B Surface Antigen on a Nitrocellulose Membrane

The immunochromatographic assay (ICA) using a nitrocellulose (NC) membrane offers several advantages. This technique is a rapid and straightforward method in contrast to other immunoassays. Polydiacetylene (PDA) vesicles have unique optical properties, displaying red color and red fluorescence at the same time. In this system, red‐phase PDA vesicles are used as a fluorescent dye as well as a surface for immobilized hepatitis B surface antibody (HBsAb). PDA has a remarkable stability compared with other fluorescent dyes. In this study, the most suitable PDA/HBsAb complexes are introduced for detecting hepatitis B surface antigen (HBsAg). Then, the PDA/HBsAb complexes affixed antibody is attached to NC membrane, which has two lines to confirm detection of HBsAg. The main advantage of this system is that the detection of HBsAg can be observed in both visible and fluorescent images due to the optical properties of polydiacetylene. Detection of HBsAg is observed up to 0.1 ng mL⁻¹ by fluorescent analysis and confirmed by red line on the NC membrane up to 1 ng mL⁻¹ (HBsAg) using the naked eye. Consequently, these results show that PDA/HBsAb complexes were successfully applied to ICA for the diagnosis of hepatitis B.     

An analytical method for measuring α‐amylase activity in starch‐containing foods

The quality of starch‐containing foods may be significantly impaired by contamination with very small amounts of α‐amylase, which can enzymatically hydrolyze the starch and cause viscosity loss. Thus, for quality control, it is necessary to have an analytical method that can measure low amylase activity. We developed a sensitive analytical method for measuring the activity of α‐amylase (from Bacillus subtilis) in starch‐containing foods. The method consists of six steps: (1) crude extraction of α‐amylase by centrifugation and filtration; (2) α‐amylase purification by desalting and anion‐exchange chromatography; (3) reaction of the purified amylase with boron‐dipyrromethene (BODIPY)‐labeled substrate, which releases a fluorescent fragment upon digestion of the substrate, thus avoiding interference from starch derivatives in the sample; (4) stopping the reaction with acetonitrile; (5) reversed‐phase solid‐phase extraction of the fluorescent substrate to remove contaminating dye and impurities; and (6) separation and measurement of BODIPY fluorescence by HPLC. The proposed method could quantify α‐amylase activities as low as 10 mU/mL, which is enough to reduce the viscosity of starch‐containing foods. Copyright © 2012 John Wiley & Sons, Ltd.     

真空冷却过程中实验条件对真空冷却速率的影响

以熟肉为实验材料,对实验条件对真空冷却速率的影响进行了理论分析和实验研究。实验结果表明:真空室有效容积越小、真空泵抽速越高,则真空冷却时间就会越短;冷阱温度对真空冷却速率有着明显的影响;当真空室内的最终压力在0.4～0.61kPa变化时,熟肉的表面温度一直在0℃以上,其真空冷却的时间随着真空室内压力的升高而增加。而真空室内的最终压力在0.3kPa左右时,熟肉的表面温度在真空冷却过程会低于0℃。     

Performance of a silicon monochromator under high heat load

The performance of a cryogenically cooled double‐crystal silicon monochromator was studied under high‐heat‐load conditions with total absorbed powers and power densities ranging from 8 to 780 W and from 8 to 240 W mm^?2, respectively. When the temperature of the first crystal is maintained close to the temperature of zero thermal expansion of silicon, the monochromator shows nearly ideal performance with a thermal slope error of 0.6 µrad. By tuning the size of the first slit, the regime of the ideal performance can be maintained over a wide range of heat loads, i.e. from power densities of 110 W mm^?2 (at total absorbed power of 510 W) to 240 W mm^?2 (at total absorbed power of 240 W).     

Condensed Mode Cooling of Ethylene Polymerization in Fluidized Bed Reactors

This review gives an overview of the evolution of the technology of condensed mode cooling, primarily for the case of ethylene polymerization on supported catalysts in fluidized bed reactors. It is well known that this mode of heat removal is quite effective in allowing polyolefin manufacturers to increase significantly production rates. What is perhaps less well understood are all of the issues that, in addition to the effect of the latent heat of vaporization of injected liquid components, also have an impact on the rate of production and behavior of the reactor. However, the liquid components injected into the reactor can vaporize rapidly under full‐scale conditions, leaving behind several heavy components (with respect to ethylene) that have numerous effects on how the particles behave, on the reaction rate, and on fluidization, fouling, and other parameters related to reactor and process performance.     

Hexanuclear 3d − 4f metal–organic cages assembled from a carboxylic acid‐functionalized tris‐triazamacrocycle for highly selective fluorescent sensing of picric acid

Two Ln^III ions are sandwiched by dinuclear Co^II building blocks derived from a tris‐triazamacrocyclic ligand bearing pendant carboxylic acid functionality, 1,3,5‐tris((4,7‐bis(2‐carboxyethyl)‐1,4,7‐triazacyclonon‐1‐yl)methyl)‐benzene (H₆L), giving rising to two nanoscale heterometallic metal–organic cages formulated as [Co₄Ln₂(LH_2.5)₂(H₂O)₄]·(ClO₄)₆·NO₃·nH₂O [Ln = Dy, n = 12 ( 1 ); Ln = Yb, n = 9 ( 2 )], whose internal cavity accommodates a guest NO₃^? anion. Their hexanuclear cage‐like architectures are maintained both in solution and solid states as confirmed by mass spectrum as well as X‐ray diffraction experiments. These two cages display ligand‐based fluorescence emissions and therefore both were chosen to be operated as fluorescent chemosensors for the detection of nitroaromatic compounds. Attractively, these metal–organic cages allow highly selective and sensitive detection of picric acid (PA) over other nitroaromatics in solution and suspension, and the fluorescence resonance energy transfer (FRET) between the cage probes and PA is mainly responsible for the remarkable detection efficiency.