Transport processes during sterilization of vertical and 5 degree horizontal dead-legs

Experimental temperature profiles and biological kill data from dead-ended tubes of various diameters and lengths commonly used in biotechnology applications were compared to those predicted by a finite element model for steam-in-place (SIP) sterilization at 122°C. Diameter was shown experimentally and numerically to have a significant effect with larger diameter tubes exhibiting greater buoyant driven convective flow and more rapid sterilization. The overall Grashof number was shown to be the significant parameter relating magnitude of convective flow to tube diameter and varied as the diameter cubed. Analysis of air/steam mixture flow patterns showed air displacement from 0.4 cm diameter tubes to be due primarily to molecular diffusion, whereas 1.0 and 1.7 cm tubes showed a two-stage convective flow pattern. There exists a critical diameter of 0.4 cm below which SIP sterilization due to buoyancy driven flow does not occur and steam bleeders should be used.     

Application of a dense gas technique for sterilizing soft biomaterials

Sterilization of soft biomaterials such as hydrogels is challenging because existing methods such as gamma irradiation, steam sterilization, or ethylene oxide sterilization, while effective at achieving high sterility assurance levels (SAL), may compromise their physicochemical properties and biocompatibility. New methods that effectively sterilize soft biomaterials without compromising their properties are therefore required. In this report, a dense-carbon dioxide (CO(2) )-based technique was used to sterilize soft polyethylene glycol (PEG)-based hydrogels while retaining their structure and physicochemical properties. Conventional sterilization methods such as gamma irradiation and steam sterilization severely compromised the structure of the hydrogels. PEG hydrogels with high water content and low elastic shear modulus (a measure of stiffness) were deliberately inoculated with bacteria and spores and then subjected to dense CO(2) . The dense CO(2) -based methods effectively sterilized the hydrogels achieving a SAL of 10(-7) without compromising the viscoelastic properties, pH, water-content, and structure of the gels. Furthermore, dense CO(2) -treated gels were biocompatible and non-toxic when implanted subcutaneously in ferrets. The application of novel dense CO(2) -based methods to sterilize soft biomaterials has implications in developing safe sterilization methods for soft biomedical implants such as dermal fillers and viscosupplements.     

Design of static mixers for inclined tubular photobioreactors

Static mixers, which improve gas-liquid mass transfer inside tubular photobioreactors and move the cells between the upper and lower parts of the tubes were designed. Each static mixer was equipped with an opening (v-cut slit) at the top (for gas dispersion) and an orifice at the lower part (for liquid circulation). When the static mixers were installed in the riser tube of an inclined tubular photobioreactor, vertical movement of the liquid was induced so that cells were moved between the surface and bottom part of the photobioreactor. The mass transfer rates in the tubular photobioreactor without static mixers decreased sharply when they were scaled up by increasing the tube diameters. However, by installation of static mixers, the mass transfer rates in 12.5-cm diameter tubes were almost as high as those of 3.8-cm tubes without static mixers. The effectiveness of the static mixers in improving the mass transfer characteristics of the tubular photobioreactors was higher in large than small diameter tubes. The ratio of the diameters of the static mixers to the diameter of the tube, the areas of the v-cut slits and the orifice were the important design parameters that affected the mass transfer characteristics. The gas hold up and and k_La were higher when the areas of the slits (v-cut) and the orifice were reduced.     

Graphical Procedure for Comparing Thermal Death of Bacillus stearothermophilus Spores in Saturated and Superheated Steam

The thermal death curve of dried spores of Bacillus stearothermophilus in saturated steam was characterized by three phases: (i) a sharp initial rise in viable count; (ii) a low rate of death which gradually increased; and (iii) logarithmic death at maximal rate. The first phase was a reflection of inadequate heat activation of the spore population. The second and third phases represented the characteristic thermal death curve of the spores in saturated steam. A jacketed steam sterilizer, equipped with a system for initial evacuation of the chamber, was examined for superheat during normal operation. Measurements of spore inactivation and temperature revealed superheat in surface layers of fabrics being processed in steam at 121 C. The high temperature of the fabric surfaces was attributed to absorption of excess heat energy from superheated steam. The superheated steam was produced at the beginning of the normal sterilizing cycle by transfer of heat from the steam-heated jacket to saturated steam entering the vessel.     

三级综合性医院压力蒸汽灭菌设备配置的探讨

从量化研究和定性分析的角度,分析探讨了三级综合性医院压力蒸汽灭菌设备的配置数量的计算,安装位置的确定与设备的选型等方法。以期为医院合理配置高压灭菌设备提供一个通用的、标准的解决方案。     

Female sterilization by Falope ring ligation.

Sterilization with the Falope Ring may be performed by means of laparoscopy of the minilaparotomy. This technique avoids the potential hazards of electrocoagulation, such as intestinal burns. Among the 825 cases reported in this paper there was only one serious complication, an ectopic pregnancy. One other patient had an undetected early pregnancy at the time of sterilization. Two patients became pregnant 4 and 42 month after the procedure. In most cases a diagnostic dilatation and curettage was done before hand. Pathological study of the fallopian tubes of one patient 28 days after the ring was applied revealed complete occlusion of the buckled segment of each tube. Falope Ring sterilization is simple, effective and safe, and the rate of subsequent pregnancy is lower than with conventional burning or clipping techniques.     

Leilani Muir versus the Philosopher King: Eugenics on trial in Alberta

The Province of Alberta in Canada was the only jurisdiction in the British Empire where a eugenic sterilization law was passed (in 1928) and vigorously implemented. The pace of sterilization orders accelerated during the Nazi era and remained high after World War II, terminating only in 1972 when the Sexual Sterilization Act was repealed. The Alberta Eugenics Board operated away from public and legislative scrutiny, and many things done in the name of eugenics were clearly illegal. Eugenics was put on trial in Alberta in 1995 and a judge of the Court of Queen's Bench ruled in 1996 that the government had wrongly sterilized Leilani Muir. After hearing evidence about the history of the eugenics movement, the origins of Alberta's Sexual Sterilization Act, the operation of the Eugenics Board, and details of Muir's life, Madam Justice Joanne B. Veit found that ‘the damage inflicted by the operation was catastrophic’, the ‘wrongful stigmatization of Ms. Muir as a moron ⋯ has humiliated Ms. Muir every day of her life’, and ‘the circumstances of Ms. Muir's sterilization were so high-handed and so contemptuous of the statutory authority to effect sterilization, and were undertaken in an atmosphere that so little respected Ms. Muir's human dignity that the community's, and the court's, sense of decency is offended’. Veit awarded Muir damages of $740,780 CAD and legal costs of $230,000 CAD. The order for Muir's sterilization was signed by John M. MacEachran, founder of the Department of Philosophy and Psychology at the University of Alberta and chairman of the Eugenics Board from 1929 to 1965. An exponent of Platonic idealism, MacEachran believed sterilization of children with a low IQ test score was a means of ‘raising and safeguarding the purity of the race’. However, the Alberta Sterilization Act was passed and implemented with cavalier disregard for the principles of genetics as well as the rights of children. This revised version was published online in August 2006 with corrections to the Cover Date.     

100～700 mL液体培养基的微波灭菌效果观察

为研究家用微波炉对少量液体培养基的灭菌效果,对100 -700 mL液体培养基采取微波分别进行灭菌,测定其灭菌时间,并对达到灭菌效果的培养基通过接种不同细菌进行质检.结果显示100、200、300、400、500、600、700 mL液体培养基分别在4.5、5.0、7.0、9.0、12.0、19.0、25.0 min达到最有效的灭菌效果.室温保存15 d仍无细菌生长.枯草杆菌黑色变种芽胞菌测试无菌生长.金黄色葡萄球菌、大肠埃希菌及普通变形杆菌在液体培养基里的生长现象、特种后细菌的菌落和形态染色特征及其生化反应均无明显差异.实验表明2 450 MHz,700 W的微波炉对100 - 700 mL的液体培养基不但能快速达到有效的灭菌效果,且营养成分不会被破坏.     

THE FISH POND EXPERIMENT: CHAPTER TWO

A tubular photobioreactor for outdoor cultivation of Spirulina platensis was successfully operated for the last two years. The reactor was made of transparent 2.4-cm diameter tubes with a total length of approximately 101-m and a volume of 124-liter. Flow was induced using an airlift pumping system. To optimize the system further, a larger tube diameter was also tested. Preliminary results have suggested that a larger tube diameter might provide increased output with reduced surface area requirements. Results of experiments comparing the productivity of the same culture volume in tubes of 2.4 cm and 5.0 cm will be presented which show a small decrease in productivity by volume, but a large increase in areal productivity. This suggests that the larger tube diameter would be an appropriate choice for larger scale systems. Additionally, data will be presented demonstrating the effectiveness of an on-line surface scatter turbidimeter for accurate measurement of Spirulina density when correlated to manual dry weight measurements.     

The responses of pollen to applied electrical fields

The growing pollen tubes of tomato and tobacco were exposed to electrical fields and the effect on the direction of growth was measured. They responded by turning toward the positive electrode (anode) and gave a detectable response in fields as small as 0.1 mV/tube diameter. The sites of germination of tobacco pollen grains were also affected by applied fields; the pollen tubes tended to emerge from the anodal side. This effect was detectable at a field of 0.4 mV/grain diameter.     

Primates Face to Face: Conservation Implications of Human–Nonhuman Primate Interconnections Edited by Agustín Fuentes and Linda D. Wolfe

ABSTRACT

Sterilization of companion animals is in most cases an expression of the caretaker's will. However, little is known about caretakers' attitudes toward pet sterilization in general—these can influence their decision to sterilize their own animals. Three hundred and twelve Romanian caretakers of non-sterilized companion animals (194 women and 118 men) were surveyed before the implementation of a pet management program in Transylvania, the North-Western part of Romania. The caretakers were administered a questionnaire that gathered demographic data and measured their general attitude toward pet sterilization and their attitude toward the sterilization of their own pet (male or female). Questionnaires were filled in by caretakers of 202 dogs and 110 cats. Romanian pet owners showed an overall level of slight disagreement toward the sterilization of companion animals. Gender-biased attitudes of the Romanian caretakers toward the sterilization of their own pets emerged only when the sex of the animals was taken into consideration, regardless of the type of pet. Romanian men disagreed with neutering male pets while Romanian women were more likely to agree with neutering male pets. No gender difference was detected regarding the spaying of female pets, with both genders showing a slight level of disagreement. The results are discussed from sociological, anthropological, and evolutionary perspectives.     

Temperature dependence of F-, D- and z-values used in steam sterilization processes

Aims:  To develop a model, based on microbiological principles, to safely optimize steam sterilization processes.
Methods and Results:  The minimum exposure time F for a decontamination process at a certain temperature is usually calculated from an empirical model with the decimal reduction time D and the temperature resistance coefficient z as parameters. These are implicitly assumed to be independent of temperature. Using a microbiological approach, it is shown that also D and z depend on temperature, indicating that the usual models provide only reliable results in a limited temperature region. The temperature dependence of F resulting from this approach describes the available experimental data very well. Safety margins to assure sterility can be included in a straightforward way.
Conclusions:  The results from the present approach can be used to safely optimize decontamination processes. The corresponding mathematical model can be implemented rather directly in process control systems.
Significance and Impact of the Study:  Our results show that for steam sterilization and disinfection processes the values of F predicted by the usual models largely underestimate the required minimum exposure times at temperatures below 120°C. This has important consequences for the optimization of such processes.     

Fast‐responding thermal‐death‐time tubes for the determination of thermal bacteria inactivation

The knowledge of thermal inactivation kinetics, usually expressed in terms of D‐ and z‐values, is of crucial importance for the design of sanitation and sterilization processes. In this study, we designed a simple, fast‐responding, and mechanically stable aluminum tube for inactivation measurements and compared these experiments with the successive‐sampling method at different temperatures. Up to 65°C, we determined a come‐up time of approximately 15 s for the tubes, which is lower than the corresponding values of other devices, presumably because of lower wall thickness, material properties, and a higher surface to volume ratio. D‐values of Escherichia coli calculated from tube inactivation experiments by first‐order kinetics were 370 s (56°C), 126 s (58°C), 53.2 s (60°C), 33.8 s (62°C), and 3.22 s (65°C), and the corresponding values determined with the successive‐sampling flask method were insignificantly different (417, 138, 48.6, and 29.1 s for 56, 58, 60, and 62°C, respectively). These data as well as those measured for Enterobacter cloacae, Pseudomonas putida, Serratia odorifera, and Yersinia rhodei were in close accordance with literature values.     

Ultrasonic Synergistic Effects in Liquid-Phase Chemical Sterilization

New methods of sterilization employing a chemical with moderate heat and ultrasonic energy have been devised. Inactivation of high-density bacterial spore suspensions is achieved by treatment with low concentration aqueous acid glutaraldehyde solutions at temperatures above or about 54 C. Low (20 kHz) or high (250 kHz) frequency ultrasonic energy is synergistic with glutaraldehyde. Rapid inactivation may also be achieved by using ultrasonic energy and aqueous alkalinized glutaraldehyde solutions at low (25 C) or moderate (55 C) temperatures. If compared to present room temperature techniques, "surface sterilization" time for contaminated objects can be reduced from hours to minutes.     

Beneficial effect of protracted sterilization of lentils on phytase production by Aspergillus ficuum in solid state fermentation

Water addition to the solid substrate preceding autoclaving increased substrate porosity and phytase production in solid state fermentation. In comparison with dry sterilization, the phytase activity increased 6‐, 8.5‐, and 10‐fold when the autoclaving time was 20, 40, and 60 min, respectively. Autoclaving increased the void space of sterilized lentils, and the increase was 16% higher when water was supplemented to the lentils before sterilization. Image analysis of SEM pictures of the solid substrate showed that water supplementation presterilization portended greater micro‐fissure surface area, which also increased with increasing the sterilization time. SEM pictures of the fermentation product showed that fungal growth into the center of the solid substrate was ubiquitous when water was supplemented before sterilization but was absent when water was supplemented post sterilization. Similarly, spore formation on the substrate surface for the presterilization water supplementation samples far exceeded spore formation for samples that received supplementation poststerilization. This evidence suggests that improved mass transfer into the solid substrate resulting from additional pore volume and the formation of micro‐fissures on the substrate surface is responsible for the observed gains in phytase productivity in solid state fermentation. © 2012 American Institute of Chemical Engineers Biotechnol. Prog., 2012     

Fine Structure of Quiescent and Germinating Aeciospores of Cronartium fusiforme

Aeciospores of the long-cycle heteroecious rust fungus, Cronartium fusiforme, were found to have an extremely thick cell wall with striking spicules protruding from it. The wall was readily degraded by commercial chitinase, but spicules were unaffected. Quiescent spores contained two nuclei with distinct nuclear membranes possessing many pores. Numerous membrane-bounded lipid bodies were found both in wild-type orange and in white mutant aeciospores. An abundance of irregularly ovoid mitochondria was present in quiescent spores. After glutaraldehydeosmium fixation, the surface of the mitochondria appeared to be covered with ribosomes or microtubules in a paracrystalline array, whereas after permanganate fixation only smooth outer mitochondrial membranes were noted. The latter fixative revealed abundant vesicular endoplasmic reticulum in the spore. Spores incubated at 20 C on agar produced one to five distinct germ tubes within 65 to 180 min. These thin-walled tubes exhibited varying degrees of branching, and reached a total hyphal length of 300 to 500 mu prior to rupturing. Emergence of germ tubes took place through a pore in the spore wall and appeared to be mainly a physical flowing of cytoplasm from the spore into the germ tube without division of nuclei or other cell organelles. On completion of germination, the protoplasm of the germ tube contained both nuclei and nearly all of the other spore contents. Mitochondria had smooth outer membranes, were greatly elongated, and possessed distinct longitudinal cristae. A limited amount of rough endoplasmic reticulum was arranged parallel to the germ tube wall. Other organelles seen in germ tubes were lipid bodies, concentric membrane figures, and numerous ribosomes. Lipid bodies appeared smaller and fewer in number than in quiescent spores.     

Opportunities for the application of real-time bacterial cell analysis using flow cytometry for the advancement of sterilization microbiology

Medical devices provide critical care and diagnostic applications through patient contact. Sterility assurance level (SAL) may be defined as the probability of a single viable micro-organism occurring on an item after a sterilization process. Sterilization microbiology often relies upon using an overkill validation method where a 12-log reduction in recalcitrant bacterial endospore population occurs during the process that exploits conventional laboratory-based culture media for enumeration. This timely review explores key assumptions underpinning use of conventional culture-based methods in sterilization microbiology. Consideration is given to how such methods may limit the ability to fully appreciate the inactivation kinetics of a sterilization process such as vaporized hydrogen peroxide (VH2O2) sterilization, and consequently design efficient sterilization processes. Specific use of the real-time flow cytometry (FCM) is described by way of elucidating the practical relevance of these limitation factors with implications and opportunities for the sterilization industry discussed. Application of FCM to address these culture-based limitation factors will inform real-time kinetic inactivation modelling and unlock potential to embrace emerging opportunities for pharma, medical device and sterilization industries including potentially disruptive applications that may involve reduced usage of sterilant.     

The effects of wall thickness, axial strain and end proximity on the pressure-area relation of collapsible tubes

Segments of silicone rubber tube were suspended between rigid pipes and subjected to slowly varying transmural pressure covering a range from slight distension to collapse with osculation. The local inside cross-sectional area at a chosen axial site was simultaneously measured via catheter by an electrical impedance method. Pressure-area relations were recorded thus at various axial sites, under varying conditions of axial tube wall tension, in tubes of two different wall thickness (0.3 and 0.4 of mean radius). Unsupported tube segment length was also varied by means of an insert device. The relations were used to calculate the variation of wave velocity with area according to Young's equation. First opposite wall contact during collapse was shown to occur at a smaller fraction of undistended circular cross-sectional area than in the thin-walled tubes investigated previously by others.     

Disinfection of drinking water by using a novel electrochemical reactor employing carbon-cloth electrodes.

A novel electrochemical reactor employing carbon-cloth electrodes was constructed for disinfection of drinking water. Escherichia coli K-12 (10(2) cells per cm3) was sterilized when a cell suspension was passed through the reactor at a dilution rate of 6.0 h-1, and a potential of 0.7 V versus a saturated calomel electrode was applied to an electrode. The survival ratio increased with increasing dilution rate but was less than 0.1% at dilution rates of less than 6.0 h-1. Although the survival ratio increased with increasing cell concentration above 10(3) cells per cm3, the disinfection rate also increased. The disinfection rate was 6.0 x 10(2) cells per cm3 per h at a cell concentration of 10(2) cells per cm3. Continuous sterilization of E. coli cells was carried out for 24 h. Sterilization is based on an electrochemical reaction between the electrode and the cell which is mediated by intracellular coenzyme A. Sterilization of drinking water by using this reactor was successfully performed, demonstrating the potential of such a reactor for clean and efficient water purification.     

Spore Discharge in Basidiomycetes: III. Spore Liberation from Narrow Hymenial Tubes

The hymenial tubes of Polyporus betulinus were shown to be approximatelycylindrical,and to have a sporulating hymenium over the greater part oftheir surface. Sporophores were tilted through measured anglesfrom the vertical in the field and in the laboratory, and theeffect on spore liberation was measured by determining the numberof spores liberated from particular tubes in standard time.All tilting caused a reduction in spore liberation. The amountof this reduction was found to compare closely with that predictedfrom calculation of the amount of hymenium lying directly abovethe orifice at various angles of tilt. It is therefore concludedthat liberation from the tube can be accounted for by the initialviolent discharge of the spore and gravitational attractionalone. An addendum corrects an earlier paper (1959) in thisseries. It shows that the variation in density of spore depositscollected from Trametes gibbosa was due to air currents in theapparatus, not to variation in sporulation rate.