Na2SiO3浓度对碳化法制备纳米白炭黑粉体性能影响研究*

二氧化碳碳化法制备纳米白炭黑, Na2SiO3浓度是非常重要的影响因素,本文通过对的纳米白炭黑粉体结构、形态、表面活性等性能研究,寻找该因素对纳米白炭黑性能的影响规律。通过从20g/l到80g/l调整Na2SiO3浓度,得到二氧化硅粉体的一次颗粒粒径和平均孔隙介于5-25nm和4.345-98.55nm,粉体的粒径、孔径和孔体积都随Na2SiO3浓度的增加变大;而比表面积与Na2SiO3浓度呈反比趋势,从376.744 m2/g降到250.7m2/g。通过对粉体进行的TG热重分析观察并结合红外光谱（IR）对白炭黑的表面有机结构的观察分析,发现粉体表面羟基密度与Na2SiO3的浓度也呈递减关系,而且加热失重率和主要的失重温度区间也有所不同也显示了粉体表面不同羟基群的密度也有差异。     

豆豉中抗真菌性芽胞杆菌的筛选及抑菌能力测定

从豆豉中分离得到一株芽胞杆菌，经鉴定属于枯草芽胞杆菌。命名为kjc-3，它对各种真菌有拮抗作用，冀发酵液在柑桔伤口表面可以拮抗青霉病和绿霉病。     

Lysozyme as a barrier to growth of Bacillus anthracis strain Sterne in liquid egg white, milk and beef

In this study, we investigated the role of lysozyme on the viability of Bacillus cereus, Bacillus subtilis, Bacillus pumilus and Bacillus anthracis (Sterne) in egg white (EW), ground beef and milk. At 35 °C in EW, growth rates (GR) for B. cereus, B. subtilis, B. pumilus and B. anthracis were 0.005, −0.018, −0.028 and −0.029 OD₆₀₀/h, respectively. Heat-treating EW at 55 and 60 °C reduced the inactivating effect of EW by 3.1 and 10.5-fold, respectively. Addition of lysozyme (2 mg/ml) to 60 °C-treated EW increased the inactivation rate 5.76-fold, indicating involvement of lysozyme in B. anthracis inactivation. B. anthracis inactivation was influenced by pH, as shown by a progressive increase in inactivation rate from 0.25 to −4.42 logs CFU/h over a pH range of 6.0-8.5. Adding 2 mg/ml lysozyme to milk and ground beef also suppressed the growth of B. anthracis 3.3 and 6.5-fold, respectively. These data indicate that lysozyme, as a natural component of EW or potential additive in other foods, could reduce biothreat risks presented by bioterror agents.     

Thermo-structural studies of spores subjected to high temperature gas environments

One of the major mechanisms of deactivating spores is to expose them to elevated temperatures. Experiments carried out in an exposure tube to study the effects on spores in a high temperature gas environment provide evidence of spore deactivation, although the deactivation mechanism is not clear. Numerical studies have been performed to complement the experimental work and to study the effects of various parameters, such as gas temperature, exposure time, and internal pressure on spore survivability. The laminar and turbulent flow fields of a sudden expansion inside the thermal exposure system were simulated by computational fluid dynamics. A thermo-structural model with wall porosity was developed to take into account the dynamic response of the spore wall structure to the internal pressure exerted by the heated vapor on the spore wall. Finally, the results of the transient heat transfer and the thermo-structural models are discussed in the context of the uncertainties in biological system parameters and spore survivability.     

Addition of ethanol to supercritical carbon dioxide enhances the inactivation of bacterial spores in the biofilm of Bacillus cereus

Supercritical carbon dioxide (SC-CO₂) was used to inactivate Bacillus cereus spores inside biofilms, which were grown on stainless steel. SC-CO₂ treatment was tested using various conditions, such as pressure treatment (10–30 MPa), temperature (35–60 °C), and time (10–120 min). B. cereus vegetative cells in the biofilm were completely inactivated by treatment with SC-CO₂ at 10 MPa and at 35 °C for 5 min. However, SC-CO₂ alone did not inactivate spores in biofilm even after the treatment time was extended to 120 min. When ethanol was used as a cosolvent with SC-CO₂ in the SC-CO₂ treatment using only 2–10 ml of ethanol in 100 ml of SC-CO₂ vessel for 60–90 min of treatment time at 10 MPa and 60 °C, B. cereus spores in the biofilm were found to be completely inactivated in the colony-forming test. We also assessed the viability of SC-CO₂-treated bacterial spores and vegetative cells in the biofilm by staining with SYTO 9 and propidium iodide. The membrane integrity of the vegetative cells was completely lost, while the integrity of the membrane was still maintained in most spores. However, when SC-CO₂ along with ethanol was used, both vegetative cells and spores lost their membrane integrity, indicating that the use of ethanol as a cosolvent with SC-CO₂ is efficient in inactivating the bacterial spores in the biofilm.     

增强免疫力的灵芝孢子保健胶囊的研制

研究了灵芝孢子粉灭菌的工艺条件,以灵芝孢子粉为主要功能原料,辅以VC研制出具有增强免疫力的灵芝孢子胶囊.在胶囊生产工艺中,以淀粉和乙醇作为粘合剂制得流动性好且装量稳定的颗粒.并对产品进行安全性毒理学、增强免疫力功能的评价.     

The formation of thermophilic spores during the manufacture of whole milk powder

A survey was undertaken at a whole milk powder manufacturing plant to determine the origin and the rate of spore formation of thermophilic bacteria. Spores were generally not detected (< 10 cfu/mL) in either the pasteurization process or the pasteurized milk directed into the powder plant. The predominant sites of spore formation were the preheater plate heat exchanger and the evaporator. Spores began to be detected approximately 9 h into an 18-h manufacturing run. Spore isolates were identified as Anoxybacillus flavithermus and Geobacillus species. A. flavithermus predominated in the preheat section, whereas a mix of both organisms was present in the later manufacturing stages.     

Determination of fungal spore release from wet building materials

The release and transport of fungal spores from water-damaged building materials is a key factor for understanding the exposure to particles of fungal origin as a possible cause of adverse health effects associated to growth of fungi indoors. In this study, the release of spores from nine species of typical indoor fungi has been measured under controlled conditions. The fungi were cultivated for a period of 4-6 weeks on sterilized wet wallpapered gypsum boards at a relative humidity (RH) of approximately 97%. A specially designed small chamber (P-FLEC) was placed on the gypsum board. The release of fungal spores was induced by well-defined jets of air impacting from rotating nozzles. The spores and other particles released from the surface were transported by the air flowing from the chamber through a top outlet to a particle counter and sizer. For two of the fungi (Penicillium chrysogenum and Trichoderma harzianum), the number of spores produced on the gypsum board and subsequently released was quantified. Also the relationship between air velocities from 0.3 to 3 m/s over the surface and spore release has been measured. The method was found to give very reproducible results for each fungal isolate, whereas the spore release is very different for different fungi under identical conditions. Also, the relationship between air velocity and spore release depends on the fungus. For some fungi a significant number of particles smaller than the spore size were released. The method applied in the study may also be useful for field studies and for generation of spores for exposure studies.     

Assessment of the aerosolization potential for fungal spores in moldy homes

The airborne fungal concentration measured with air samplers during specific time intervals may not adequately represent the indoor air quality because of the sporadic nature of spore release from sources. The conventional source evaluation (e.g. swab and tape sampling) characterizes the mold source but does not relate to the fraction of spores that can be aerosolized from a contaminated material. As an alternative to these methods, we have recently developed and laboratory-tested a novel Fungal Spore Source Strength Tester (FSSST). It allows assessing the potential of aerosolization of fungal spores from contaminated surfaces under the most favorable release conditions. In this study, the FSSST was used to characterize the release of spores from four building materials in mold-problem homes. The spores of different species were efficiently aerosolized by the FSSST, exhibiting a total spore release rate ranging approximately from 10(2) to 10(3) cm2/min. For all tested materials, <2% of the spores on the contaminated surface were released during the tests. The airborne spore concentration estimated from the release rate data was found in most cases to be significantly greater than the concentration actually measured in these environments with simultaneous air sampling. The results suggest that the FSSST can be used for the assessment of maximum potential exposure to airborne spores released from identified sources in homes. PRACTICAL IMPLICATIONS: A recently developed FSSST was found to be suitable to measure the aerosolization potential of indoor fungal sources at the most favorable release conditions. The FSSST generates the data that allows assessing the strength of mold sources in homes with respect to their maximum ability to contaminate indoor air with fungi. The novel approach bridges two conventional methods, the air sampling and the direct source evaluation (e.g. swab sampling), thus providing a better representation of the airborne fungal exposure than these methods individually. The device prototype can be used for evaluating the effectiveness of environmental interventions by taking samples before and after the intervention. As a broader application, the FSSST can be utilized for assessing the release of various hazardous biological and non-biological particles from contaminated surfaces.     

一株芽孢乳酸杆菌TQ33产芽孢特性及抗性的研究

报道了一株同型发酵乳酸杆菌ＴＱ３３的产芽孢特性及其它抗性，寻找到产芽孢的最佳培养基，获得了Ｋ￣＋、Ｎａ￣＋对ＴＱ３３菌芽孢的产生无明显的促进作用。Ｍｎ￣（２＋）在０．００５％～０．１０％范围内对芽孢的生成有明显的促进作用；ＴＱ３３菌对热、酸和高渗透压有较强的抗性。制成了含活菌数达１０￣７～１０￣８的小样。