BACKGROUND AND OBJECTIVES: The objective of this study was to quantitatively measure changes in the elastic moduli of rabbit nasal septal cartilage during laser heating. While the efficacy of laser cartilage reshaping has been established for use in nasal surgery, few studies have investigated the temperature-dependent viscoelastic behavior of cartilage. STUDY DESIGN/MATERIALS AND METHODS: Cyclic force versus displacement curves were generated during the Nd:YAG laser (lambda = 1.32 microm, 10 second exposure time, 21.22 W/cm2) irradiation of cartilage specimens secured in cantilevered geometry. Samples were irradiated three times with 30 second cooling intervals between each laser exposure. Measurements were recorded before, during, and after laser irradiation, and then following complete rehydration in normal saline (NS) for 1 hour at 25 degrees C. Elastic modulus was calculated assuming linear viscoelastic behavior. RESULTS: The elastic modulus in native tissue decreased during and after successive laser exposures from about 6 to 3.5 MPa. After rehydration, the modulus returned to near-baseline value. Surface temperature reached a maximum of 65 degrees C. CONCLUSIONS: The laser irradiation of cartilage using parameters similar to those used in reshaping does not produce significant irreversible changes in the mechanical properties of the tissue. Measurement of the elastic modulus is an effective means of characterizing alterations in cartilage mechanical behavior during and after laser heating. 相似文献
The products derived from thermo‐oxidation of poly(bisphenol A carbonate) (PC) and their related degradation pathways are investigated. PC degradation is carried out at 300 °C in air. The oxidized products are analyzed for the first time by using direct electrospray mass spectrometry (MS) and matrix‐assisted laser desorption ionization time of flight MS. Together with the formation of bisphenol A oligomers, several new structures containing biphenyl units, phenols, acetophenones, alcohols, acids, and xanthones molecules are detected. The use of thin films, instead of PC bulk, allows one to obtain precise information about mechanisms involved during thermo‐oxidative processes and to establish a new order of priorities among the renowned degradative reactions. 相似文献
Novel luminescent electrospun (ES) polymer nanofibers were successfully prepared via a two‐fluid spinneret for thermo‐tunable colorimetric sensor applications. Binary blends of conjugated rod–coil poly[2,7‐(9,9‐dihexylfluorene)]‐block‐poly(N‐isopropylacrylamide) (PF‐b‐PNIPAAm)/poly(methyl methacrylate) (PMMA) were used as the material system for preparing the ES nanofibers. In order to produce uniform ES nanofibers, the shell layer was injected with THF to retard the rapid solidification of core polymer blend solutions that occurred at the nozzle tip. The prepared ES nanofibers, with an average diameter of 500 nm, exhibited a reversible photoluminescence (PL) spectra‐shifting, as the temperature cycle varied between 20 and 40 °C. Such reversible PL switching resulted from the extended/compact structural transformation on the PNIPAAm segment, which led to different PF aggregation sizes. The thermo‐responsive sensing characteristics of the prepared ES nanofibers were significantly enhanced as the PNIPAAm coil length was increased. In particular, PF7‐b‐PNIPAAm516/PMMA ES nanofibers exhibited a blue luminescence color at 20 °C but this changed to a greenish‐blue luminescence color at 40 °C. On the other hand, the corresponding spin‐coated thin film from the blend remained in the blue luminescence. Furthermore, the temperature‐responsive wettability of the surface could be switched between hydrophobicity and hydrophilicity via temperature variations. This study demonstrated that novel ES nanofibers exhibit both reversible thermo‐responsive luminescence characteristics and wettability, suggesting their potential for application as a new kind of sensory material.
The incidence of cervical cancer in Malawi is the highest in the world and projected to increase in the absence of interventions. Although government policy supports screening using visual inspection with acetic acid (VIA), screening provision is limited due to lack of infrastructure, trained personnel, and the cost and availability of gas for cryotherapy. Recently, thermo‐coagulation has been acknowledged as a safe and acceptable procedure suitable for low‐resource settings. We introduced thermo‐coagulation for treatment of VIA‐positive lesions as an alternative to cryotherapy within a cervical screening service based on VIA, coupled with appropriate, sustainable pathways of care for women with high‐grade lesions and cancers. Detailed planning was undertaken for VIA clinics, and approvals were obtained from the Ministry of Health, Regional and Village Chiefs. Educational resources were developed. Thermo‐coagulators were introduced into hospital and health centre settings, with theoretical and practical training in safe use and maintenance of equipment. A total of 7,088 previously unscreened women attended VIA clinics between October 2013 and March 2015. Screening clinics were held daily in the hospital and weekly in the health centres. Overall, VIA positivity was 6.1%. Almost 90% received same day treatment in the hospital setting, and 3‐ to 6‐month cure rates of more than 90% are observed. Thermo‐coagulation proved feasible and acceptable in this setting. Effective implementation requires comprehensive training and provider support, ongoing competency assessment, quality assurance and improvement audit. Thermo‐coagulation offers an effective alternative to cryotherapy and encouraged VIA screening of many more women. 相似文献
Thermo‐responsive graft copolymers have been synthesized based on a poly(N‐vinylcaprolactam) (PVCL) backbone and either hydrophilic poly(ethylene oxide) (PEO) or hydrophobic poly(tetrahydrofuran) (PTHF) side chains. The phase separation behavior of the graft polymers in water was studied by transmittance measurements and compared to that of the corresponding swollen segmented polymer networks and aqueous solutions of both polymers. The influence of the concentration and length of the grafts on the cloud point temperature (TCP) has been demonstrated. PVCL‐g‐PTHF copolymers have been synthesized by using the macromonomer technique, i.e. the radical copolymerization of VCL with a PTHF macromonomer. A special feature of these amphiphilic graft copolymers is their ability to stabilize aqueous emulsions below the TCP and to suddenly break them above the TCP. PVCL‐g‐PEO copolymers were prepared by a grafting onto method. First, succinimide groups were introduced in the backbone, to which amino terminated PEO chains were grafted in the second step. This leads to di‐hydrophilic copolymers that become amphiphilic after heating their aqueous solutions above the TCP.
Malassezia species are part of the normal skin flora and are associated with a number of human and animal skin diseases. However, the mechanisms that mediate infection and host–fungal interactions are poorly understood. The haemolytic activity of several microorganisms is considered a factor that contributes to pathogenicity of the organism to humans and animals. This virulence factor was previously identified in several pathogenic fungi that cause systemic mycoses, such as Aspergillus and Candida. In this study, the haemolytic activity of six major Malassezia species, including M. furfur, M. globosa, M. pachydermatis, M. restricta, M. slooffiae and M. sympodialis, was investigated. The haemolytic activity of these species was tested on tryptone soya agar with 5% sheep blood. All the examined Malassezia species produced a halo zone of complete haemolysis. A quantitative analysis of the haemolytic activity was performed by incubating sheep erythrocytes with the extraction from culture of each Malassezia species. Interestingly, M. globosa and M. restricta showed significantly high haemolytic activity compared with the other Malassezia species. In addition, M. globosa also exhibited stable haemolytic activity after treatment at 100 °C and in the presence of some proteases, indicating that this haemolytic factor is different from those of other fungi. 相似文献