Temperature Measurement by Sublimation Rate as a Process Analytical Technology Tool in Lyophilization

Product temperature (T_b) and drying time constitute critical material attributes and process parameters in the lyophilization process and especially during the primary drying stage. In the study, we performed a temperature measurement by the sublimation rate (TMbySR) to monitor the T_b value and determine the end point of primary drying. First, the water vapor transfer resistance coefficient through the main pipe from the chamber to the condenser (C_r) was estimated via the water sublimation test. The use of C_r value made it possible to obtain the time course of T_b from the measurement of pressure at the drying chamber and at the condenser. Second, a Flomoxef sodium bulk solution was lyophilized by using the TMbySR system. The outcome was satisfactory when compared with that obtained via conventional sensors. The same was applicable for the determination of the end point of primary drying. A laboratory-scale application of the TMbySR system was evidenced via the experiment using 220-, 440-, and 660-vial scales of lyophilization. The outcome was not dependent on the loading amount. Thus, the results confirmed that the TMbySR system is a promising tool in laboratory scale.     

Laboratory investigation into optimal temperature for plaster of Paris application

Objective: The present study aimed to determine the relationship between heat generated and time taken to reach maximum temperature when creating plaster of Paris casts, in relation to dipping water temperature and plaster slab thickness. Methods: The study was conducted in a laboratory setting. A standard procedure for dipping, draining, layering and covering plaster slabs was developed. A standard temperature measurement and data‐recording method was applied. Variables tested were dipping water temperature (25, 30, 40, 50°C) and plaster slab thickness (10‐ply and 15‐ply). Results: Mean maximum temperature varied between 31.9 and 41.7°C, and was proportional to dipping water temperature and plaster slab thickness. Mean time to maximum temperature varied between 1216 and 728 s, and was inversely proportional to dipping water temperature and directly proportional to plaster slab thickness. All means were significantly different (P = 0.01). Conclusion: Increasing dipping water temperature and number of layers of plaster when making plaster slabs significantly increases temperature of plaster setting. These data are important for an understanding of optimum conditions for safer cast application. The present study highlights the need for further research in this area.     

表浅血流量测量仪的研制与应用

利用热传导法测量组织表浅血流量具有灵敏、方便、无创和能够连续测量等优点,本文介绍了表浅血流量仪的结构、测量原理及其探头的制作和校正程序,还提出了该仪器应用中的注意事项。     

The effect of dentin desensitizers on thermal changes in the pulp chamber during fabrication of provisional restorations

The purpose of this study was to evaluate the effect of two dentin desensitizers on the pulp chamber temperature increase during fabrication of provisional restorations by a direct method. Sixty intact extracted mandibular third molars were prepared for a metal-ceramic complete crown. Then the teeth were randomly divided into three groups of 20 each. Group 1, no dentin desensitizer was used as the control group; group 2, a resin-based dentin desensitizer was selected; and group 3, the prepared teeth surfaces were coated with polyurethane cyanoacrylate adhesive. Each of the three groups was further divided into two polymerizing systems (autopolymerizing and a photopolymerizing) of 10 each. After insertion of the resin-filled matrix, the temperature change in the pulpal chamber was recorded with thermocouple connected to a data logger. anova indicated no significant differences for all combinations of desensitizing agents and curing methods (P > 0.05). When light cured composite or chemical curing acrylics were used to make temporary crowns, the presence of desensitizing agent did not reduce the temperature transmitted from the provisional material; the residual temperature rise transmitted was of such a magnitude as to cause concern regarding possible thermal injury to pulp.     

Studies in Phlebitis. II. Early Detection of Amiodarone-Induced Phlebitis in a Rabbit Model

Pharmaceutical Research -     

Dynamic skin cooling with an environmentally compatible alternative cryogen during laser surgery

BACKGROUND AND OBJECTIVES: Cryogen spray cooling with tetrafluoroethane (R134a) has been used to enhance epidermal protection during dermatologic laser surgery. However, R134a has a very high global warming potential (GWP = 1300). Our objective was to evaluate the cooling effectiveness of an alternative cryogen with a much lower GWP, namely liquid carbon dioxide (CO(2), GWP = 1). STUDY DESIGN/MATERIALS AND METHODS: A thin-film thermocouple deposited on an epoxy skin phantom was used to measure surface temperature (T(s)) variations induced by R134a or CO(2) sprays. The temperature distribution in the skin phantom was estimated using T(s) and Duhamel's method. Impact pressure and noise level of both cryogen sprays were measured with a dynamic sensor and sound meter, respectively. Consumption of both cryogens was also evaluated. RESULTS: For R134a sprays, T(s) was kept almost constant after 15 milliseconds. For CO(2) sprays, T(s) decreased continuously during the entire spurt of 50 milliseconds. The minimum T(s) induced by the CO(2) sprays was lower than that induced by R134a when the spurt duration was longer than 35 milliseconds. Numerical simulation shows that CO(2) sprays were able to induce very similar temperature reductions in the skin phantom as compared to R134a sprays when the spurt duration and delay time were selected appropriately. R134a sprays induced an impact pressure of 3.6 kPa, as compared to 43.1 kPa for CO(2) sprays. The maximum noise level for R134a sprays was 109 dBA as compared to 135 dBA for the CO(2) sprays. The R134a consumption for a 50 milliseconds spurt is 67 mg as compared to 225 mg for a CO(2) spurt of the same duration. CONCLUSIONS: CO(2) sprays are expected to have similar skin cooling efficacy as R134a sprays. Although the CO(2) consumption is higher than R134a, its contribution to global warming is still much less than R134a. The effects of varying spurt durations on in vivo human skin and the impact on cutaneous blood flow require further investigation.     

医学动植物实验用热电偶测温装置的设计*☆

背景：目前温度测量多为环境测量,无法准确测量胚胎发育温度和幼体发育温度。 目的：研究基于AD595芯片的医学动植物实验用热电偶测温装置的设计方案。 方法：实验设计包括信号的输入模块,信号的放大模块和信号的显示模块。信号由接插件端口送至AD595进行电阻电容网络去噪后送给AD620进行放大。放大后的信号经数模转换后送给单片机,最后通过3位8段码LED进行显示。 结果与结论：缝入动物体内的K型热电偶可以精确测量出胚胎发育温度和幼体发育温度。实验发现大明虾孵化温度为20~ 22 ℃有利于雌性化。采用AD595芯片设计的热电偶测温电路方案切实可行,效果稳定。同时可以有效降低电磁干扰和误差,便于软件的升级和改进。     

Temperature and SAR measurements in deep-body hyperthermia with thermocouple thermometry

Multisensor (7–14) thermocouple thermometry is used at our department for temperature measurement with our 'Coaxial TEM' regional hyperthermia system. A special design of the thermometry system with high resolution (0.005?C) and fast data-acquisition (all channels within 320 ms) together with a pulsed power technique allows assessment of specific absorption rate (SAR) information in patients along catheter tracks. A disadvantage of thermocouple thermometry, EM interference, is almost entirely eliminated by application of absorbing ferrite beads around the probe leads. We investigated the effect of remaining disturbance on the temperature decay after power-off, both experimentally in phantoms and in the clinic, and with numerical simulations. Probe and tissue characteristics influence the response time ?_dist of the decay of the disturbance. In our clinical practice a normal pulse sequence is 50 s power-on, 10 s power-off: a response time longer than the power-off time results in a deflection of the temperature course at the start. Based on analysis of temperature decays correction of temperature is possible. A double-pulse technique is introduced to provide an initial correction of temperature, and fast information about accuracy. Sometimes disturbance with a relatively long response time occurs, probably due to a bad contact between probe, catheter and/or tissue. Thermocouple thermometry proved to be suitable to measure the SAR along a catheter track. This is used to optimize the SAR distribution by patient positioning before treatment. A clinical example illustrates this.