Fluorescence lifetime standards for time and frequency domain fluorescence spectroscopy

A series of fluorophores with single-exponential fluorescence decays in liquid solution at 20 degrees C were measured independently by nine laboratories using single-photon timing and multifrequency phase and modulation fluorometry instruments with lasers as excitation source. The dyes that can serve as fluorescence lifetime standards for time-domain and frequency-domain measurements are all commercially available, are photostable under the conditions of the measurements, and are soluble in solvents of spectroscopic quality (methanol, cyclohexane, water). These lifetime standards are anthracene, 9-cyanoanthracene, 9,10-diphenylanthracene, N-methylcarbazole, coumarin 153, erythrosin B, N-acetyl-l-tryptophanamide, 1,4-bis(5-phenyloxazol-2-yl)benzene, 2,5-diphenyloxazole, rhodamine B, rubrene, N-(3-sulfopropyl)acridinium, and 1,4-diphenylbenzene. At 20 degrees C, the fluorescence lifetimes vary from 89 ps to 31.2 ns, depending on fluorescent dye and solvent, which is a useful range for modern pico- and nanosecond time-domain or mega- to gigahertz frequency-domain instrumentation. The decay times are independent of the excitation and emission wavelengths. Dependent on the structure of the dye and the solvent, the excitation wavelengths used range from 284 to 575 nm, the emission from 330 to 630 nm. These lifetime standards may be used to either calibrate or test the resolution of time- and frequency-domain instrumentation or as reference compounds to eliminate the color effect in photomultiplier tubes. Statistical analyses by means of two-sample charts indicate that there is no laboratory bias in the lifetime determinations. Moreover, statistical tests show that there is an excellent correlation between the lifetimes estimated by the time-domain and frequency-domain fluorometries. Comprehensive tables compiling the results for 20 (fluorescence lifetime standard/solvent) combinations are given.     

Transport of carnitine and acetylcarnitine by carnitine/organic cation transporter (OCTN) 2 and OCTN3 into epididymal spermatozoa

Carnitine and acetylcarnitine are important for the acquisition of motility and maturation of spermatozoa in the epididymis. In this study, we examined the involvement of carnitine/organic cation transporter (OCTN) in carnitine and acetylcarnitine transport in epididymal spermatozoa of mice. Uptake of both compounds by epididymal spermatozoa was time-dependent and partially Na(+)-dependent. Kinetic analyses revealed the presence of a high-affinity transport system in the spermatozoa, with K(m) values of 23.6 and 6.57 muM for carnitine and acetylcarnitine respectively in the presence of Na(+). Expression of OCTN2 and OCTN3 in epididymal spermatozoa was confirmed by immunofluorescence analysis. The involvement of these two transporters in carnitine and acetylcarnitine transport was supported by a selective inhibition study. We conclude that both Na(+)-dependent and -independent carnitine transporters, OCTN2 and OCTN3, mediate the supply of carnitine and acetylcarnitine to epididymal spermatozoa in mice.     

Hyperbranched CdTe nanostructures via a self-assembly route: optical properties

In this work, we report a luminescent nanobundle structure formed by a hierarchical self-assembly process of thioglycolic acid (TGA)-capped CdTe quantum dots (QDs). The luminescence intensity of CdTe nanostructures is high enough to get a clear one-photon excitation confocal image. High contrast two-photon excitation confocal images suggest that the nonlinear properties of pristine QDs are well inherited by the formed CdTe nanostructures. The controllability of the structures and inheritance of the optical properties of the building units make the self-assembled nanostructures new generation materials.     

Comparison of real-time reverse-transcription loop-mediated isothermal amplification and real-time reverse-transcription polymerase chain reaction for detection of noroviruses in municipal wastewater

The monitoring of NVs in municipal wastewater by both real-time RT-LAMP and real-time RT-PCR, and the comparison of these two methods with respect to NV detection were carried out. The change in NVs detected by real-time RT-LAMP agreed well with that detected by real-time RT-PCR. In contrast, the correlation between the copy number determined by real-time RT-PCR and the threshold time (Tt) determined by real-time RT-LAMP obtained during monitoring was not significant (0.1相似文献   

Emergency Preparedness Hub: Designing Decentralized Systems for Disaster Resilience

While advocating for designers as key contributors to disaster resilience, this article proposes an alternative infrastructural model through community-specific design. The design and prototyping of Emergency Preparedness Hubs, or PREPHubs, proposes a new model for disaster infrastructure that is dispersed, off-grid, and locally adapted, while operating as a system. Instead of single-function technocratic objects, they are designed as cultural objects and multi-use systems which provide an alternative to lifeline infrastructures that are often disrupted during natural disasters. As dual-function systems, PREPHubs operate on a daily basis as interactive public space architectures, becoming embedded in the daily lives of local communities.     

Ultrastructural and immunohistochemical studies of medullary bone calcification, with special reference to sulphated glycosaminoglycans

Histochemical, immunohistochemical and electron energy-loss spectroscopic studies were performed to examine the relationship between sulphated glycosaminoglycans and medullary bone calcification using oestrogen-injected male Japanese quail. Sulphated glycosaminoglycans, detected by high iron diamine (HID) or HID-thiocarbohydrazide-silver protein (HID-TCH-SP) methods, were distributed throughout the matrix of medullary bone, some periphery and extending tips of the trabeculae stained weakly, and the globular structures at osteoid areas were exclusively positive for HID-TCH-SP stain. Immunohistochemistry identified keratan sulphate located in the globular structures at osteoid areas and calcified matrix, but chondroitin-4 sulphate and chondroitin-6 sulphate were not detected in the matrix. Using electron spectroscopic imaging, sulphur was determined to be localized in the globular structures. These results demonstrate that medullary bone matrix accumulates keratan sulphate in the globular structures, which are the foci for calcification, and eventually in the calcified areas. This suggests that keratan sulphate containing sulphur is maintained in the calcified matrix. These results indicate a unique process of calcification exists in medullary bone.     

Simple preparation of TiO2 particles dispersed activated carbons and their photo-sterilization activity

We report a simple preparation method for TiO₂ particles dispersed activated carbons and their photo-sterilization activity for E. coli and B. subtilis. The TiO₂ particles dispersed activated carbons were readily prepared by steam activation of pitch containing titanium isopropoxide Ti(OiPr)₄ or titanium acetylacetonate TiO(acac)₃. The resulting activated carbons have high BET surface area and fine TiO₂ particles are uniformly dispersed. The photo-sterilization activities for E. coli and B. subtilis were estimated by the sterilization activity for bacteria spores by irradiation of black light to the solutions containing activated carbons. The obtained activated carbons exhibited high photo-sterilization activity for E. coli and B. subtilis with short irradiation time of 15 min.     

Bioactivity and mechanical properties of CaSiO3/high-density polyethylene (HDPE) composites prepared by a new surface loading method of CaSiO3 powder

CaSiO₃/high-density polyethylene (HDPE) composites with flexibility and biocompatibility were prepared by a new surface loading method. CaSiO₃ powder was synthesized by coprecipitation method with heating at 1300 °C for 2 h. The obtained α-CaSiO₃ powder was sieved to 45-75 μm (sample M) and 75-150 μm (sample C). Fine powder sample (sample F) was prepared by grinding the powder being the average particle size of 2.9 μm. These powders were sprinkled on the melted HDPE sheets heated at 160, 180 and 200 °C. The amounts of sprinkled powder were only <0.1 vol.% but the ratios of surface coverage area were >50% in all the samples. Apatite formation in simulated body fluid (SBF) was observed by soaking for 5 days in sample F while within 1 day in samples M and C. The sample M retained flexible properties of HDPE together with excellent biocompatible properties.