食品级惰性粉对土耳其扁谷盗成虫的致死作用及体壁形态结构的影响

为明确食品级惰性粉对仓储害虫土耳其扁谷盗成虫的致死作用,采用拌粮法研究不同剂量食品级惰性粉对土耳其扁谷盗成虫的致死效果,结合扫描电镜观察惰性粉对其体壁形态结构的影响。结果表明,惰性粉对土耳其扁谷盗成虫有较强的致死作用,且随着使用剂量的增加和处理时间的延长,土耳其扁谷盗成虫的死亡率逐渐上升。当处理时间分别为24、48、72 h时,惰性粉的致死中量分别为8.3、5.6、4.1 mg/kg。扫描电镜观察结果表明,惰性粉能对土耳其扁谷盗成虫体壁形态结构造成明显的物理损伤。经惰性粉处理的土耳其扁谷盗成虫体表均匀粘附有惰性粉颗粒,体表刚毛出现损伤、缺失,体节及相关附肢关节,如头部与前胸、前胸与中胸、足的基节窝等处,发生明显的缢缩、间隙闭合。而对照组虫体体壁干净,各体节连接处舒展、正常。     

惰性粉处理稻谷防治锈赤扁谷盗的效果研究

研究了经食品级惰性粉处理的稻谷中锈赤扁谷盗的生存时间,并在实仓验证了散装稻谷仓粮堆表层应用惰性粉拌粮的防治效果。用纯惰性粉处理锈赤扁谷盗的生存时间为0.8 d,采用150 mg/kg惰性粉拌粮法处理的稻谷中锈赤扁谷盗生存时间为0.9 d;无惰性粉处理的活虫样和稻谷样中锈赤扁谷盗的生存时间分别为13.3 d和18.6d。研究表明,惰性粉拌粮对锈赤扁谷盗有显著的防治效果,实仓试验中应用惰性粉可以减少锈赤扁谷盗的数量,但其应用技术有待进一步研究。     

电子束辐照防治扁甲科害虫及对小麦品质影响

采用电子加速器对长角扁谷盗、锈赤扁谷盗和土耳其扁谷盗成虫及小麦进行辐照处理,研究了0~1 000 Gy的电子束辐照对这3种试虫的致死效应,分析了它们对辐照的敏感性,以及0~5 000 Gy剂量辐照下小麦的加工品质。结果表明,辐照剂量越高,3种试虫的死亡速度越快;100 Gy的剂量辐照后,试虫在18 d内全部死亡;3种试虫对辐照的敏感性差异不显著,辐照后第12天,长角扁谷盗、锈赤扁谷盗和土耳其扁谷盗成虫的LD_(99)分别为280.2、260.4、281.3 Gy。电子束辐照对小麦的出粉率、湿面筋含量影响不显著(P0.05),但经2 000 Gy以上剂量辐照的小麦粉的面团形成时间和稳定时间显著下降(P0.05)。因此,100~2 000 Gy辐照剂量可以作为辐照防治扁甲科储粮害虫的适宜剂量。     

实验室条件下惰性粉对海南地区高抗性扁谷盗系害虫的致死效应评价

本研究比较了惰性粉对7种海南地区高抗性扁谷盗系害虫的致死效果,并探讨了不同条件下惰性粉对海南地区扁谷盗系害虫的防治效果影响.结果表明:惰性粉对海南地区7种高抗性的扁谷盗系害虫的防治效果相近,均具有良好的杀虫效果;惰性粉含量的增加、环境温度的升高、环境湿度的的下降、粮食水分的下降都有利于提高惰性粉对7种高抗性扁谷盗系害虫...     

蛇床子素粉剂对5种储粮害虫生物活性研究

蛇床子素粉剂对5种主要储粮害虫的生物活性研究结果表明:蛇床子素粉剂具有很好的防治效果,在最高剂量1.6 mg/kg下,对这5种害虫的校正死亡率达98.00%以上,所需处理时间从2～15 d不等.对玉米象、长角扁谷盗、锯谷盗成虫处理2 d后,校正死亡率分别为98.89%、100.00%、98.84%,致死中量LD50分别为0.19、0.20、0.26 mg/kg;对谷蠹、赤拟谷盗成虫处理15 d后,校正死亡率均为100.00%,致死中量LD50分别为0.03、0.23 mg/kg.蛇床子素粉剂1.6 mg/kg剂量对玉米象、谷蠹、赤拟谷盗和锯谷盗成虫的防治效果好于商业防护剂谷虫净(1 000 mg/kg)和防虫磷(10 mg/kg);对长角扁谷盗成虫的防治效果好于谷虫净,与防虫磷防治效果间没有显著差异性.     

极端温度对三种扁谷盗属储粮害虫的致死作用

分析了42～62 ℃的极端高温、10～25 ℃的常规温度和-5～-15 ℃的极端低温对三种扁谷盗属害虫的致死作用,研究了极端低温下锈赤扁谷盗、长角扁谷盗和土耳其扁谷盗对温度的敏感差异性,评估了控温储粮技术防治扁谷盗害虫的可行性。在极端高温下, 54 ℃处理75 min、58 ℃处理60 min、62 ℃处理45 min能够完全杀灭锈赤扁谷盗成虫。在常规温度下,锈赤扁谷盗幼虫12 d死亡率低于30%,其死亡数量随时间的延长而增大。在极端低温下,长角扁谷盗对极端低温较为敏感,其次为土耳其扁谷盗、锈赤扁谷盗。极端温度防治害虫的有效性取决于有效的温度、足够的暴漏时间和处理物料的安全性。极端低温通常比极端高温需要更长的暴露时间,但长时间暴露在极端温度下被处理商品受损的风险将进一步增大。     

电子束辐照防治3种扁甲科储粮害虫及对小麦加工品质的影响

针对储粮害虫的磷化氢抗性问题,采用电子加速器对长角扁谷盗、锈赤扁谷盗和土耳其扁谷盗成虫及小麦进行辐照处理,研究了0-1000 Gy的电子束辐照对这三种害虫的致死效应,分析了它们对辐照的敏感性,并研究了0-5000 Gy剂量辐照下小麦的加工品质。结果表明,电子束辐照处理对三种害虫的致死规律大致相同,其对电子束的敏感性存在差异,但差异不显著。电子束辐照对小麦的出粉率、湿面筋含量影响不显著(p＞0.05),但面团的流变学特性变化明显。与对照相比,经3000 Gy及以上剂量辐照的小麦粉的面团形成时间和稳定时间显著下降(p<0.05)。因此,100-2000 Gy辐照剂量可以作为辐照防治扁甲科储粮害虫的适宜剂量。     

空仓内干法喷施食品级惰性粉杀虫效果评价

针对目前用于防治储粮害虫的空仓杀虫剂效果差,易增加储粮害虫的抗药性,对操作人员身体危害大等问题,在空仓环境内进行了国内自行研制移动式喷粉机干法喷施食品级惰性粉对谷蠹、玉米象、锯谷盗、赤拟谷盗和锈赤扁谷盗等5种储粮害虫成虫的防治效果测试。结果表明,喷粉机施药效果好,药剂形成尘雾分散均匀,在仓房各个方位无明显差异,形成的药膜可在3天内100%杀死供试的储粮害虫成虫。     

中温热处理对酒曲害虫杀灭效果的研究

通过设置不同温度和不同时间的热处理条件,研究咖啡豆象、土耳其扁谷盗两种酒曲害虫在裸露条件下和在酒曲介质存在条件下的致死情况。在 45 ℃、50 ℃及55 ℃热处理条件下,裸露条件下咖啡豆象校正死亡率达到100%的时间分别为180 min、20 min、9 min;土耳其扁谷盗校正死亡率达到100%的时间分别为750 min、60 min、12 min;酒曲介质存在条件下,咖啡豆象校正死亡率达到100%的时间分别为720 min、400 min、160 min;土耳其扁谷盗校正死亡率达到100%的时间分别为3 960 min、600 min、200 min。同时通过Logistics 模型分析发现,在相同的热处理条件下,咖啡豆象的半致死时间要短于土耳其扁谷盗的半致死时间。     

掌叶苹婆种子提取物对三种主要储粮害虫的毒力测定

采用索氏提取法,以丙酮作为有机溶剂制备掌叶苹婆种子提取物,并利用滤纸药膜法研究了掌叶苹婆种子提取物对玉米象、谷蠹和锈赤扁谷盗3种试虫成虫的触杀作用。结果表明,掌叶苹婆种子丙酮提取物对玉米象、谷蠹和锈赤扁谷盗3种试虫成虫具有很强的触杀作用,且触杀作用随着处理时间延长和处理剂量增加而显著增强。在浓度3.923 mg/cm2处理剂量下处理96 h后提取物对3种试虫的触杀作用校正死亡率均达到100%。掌叶苹婆种子丙酮提取物对玉米象、谷蠹和锈赤扁谷盗成虫的触杀毒力LD50值分别为:0.875、0.716和1.389 mg/cm2。3种试虫成虫对提取物的敏感性为谷蠹>玉米象>锈赤扁谷盗。     

Morphological transitions of Bacillus subtilis in the presence of food-grade lipidic nanoemulsions

The present study aims to study the antibacterial activity of food-grade lipidic nanoemulsion (noncationized/cationized) against Bacillus subtilis (BS). Bactericidal activity was ascertained by studying the morphological transitions on BS using transmission electron microscopy (TEM), atomic force microscopy (AFM), and scanning electron microscopy (SEM). Morphological changes were witnessed by cell wall breakage, oozing out of cellular contents, loss of cell turgidity and contour. Furthermore, aggregation of cationic nanoemulsion (CaNM) was preferentially observed at apical side of BS construing comparatively more electrostatic attraction between electronegative apical side and CaNM. Resistance response of BS exhibited by apical cell-wall thickening was not able to protect the bacteria due to leakage of cellular content. AFM corroborated its importance in bacteriology, wherein the fragmented cell wall can be “piece-by-piece” identified and sutured back to its appropriate vacant places, thereby, completing the cell wall contour of the ghost cell. Such postmortem analysis of bacterial cell using AFM studies can throw light toward mechanism of cell fragmentation of bacterial cells. SEM study also demonstrated the deformed, fragmented, and amorphous nature of BS construing the bactericidal effect of prepared nanoemulsion.     

惰性粉气溶胶防虫技术在横向通风粮仓中应用研究

为了解惰性粉气溶胶防虫技术在横向通风系统仓房使用中,惰性粉随气流在粮堆中的扩散和分布状态,采用称重和显微镜、电子显微镜观察等方法对粮堆不同部位采集的粉尘样本进行检测。研究结果显示,在施粉阶段,施粉对侧主风道内能够检测到惰性粉气溶胶浓度约为0.039 mg/L,表明惰性粉气溶胶能够在粮堆中粮粒的空隙间扩散,可以穿透21米粮堆,到达对侧主风道。施粉结束后,检测粮堆内粮粒沾粉情况,结果发现紧挨喷粉侧的粮粒沾粉率较高,最高可达6.9%。而沿着气流向粮堆内流动的方向,粮堆中沾粉粮粒的百分率逐渐降低。     

Combination of NMR and MRI Techniques for Non-invasive Assessment of Sea Cucumber (<Emphasis Type="Italic">Stichopus japonicas</Emphasis>) Tenderization During Low-Temperature Heating Process

The purpose of this study was to develop and test the combination of nuclear magnetic resonance (NMR) and magnetic resonance imaging (MRI) method to assess the proton changes of sea cucumber body wall during low-temperature heating process. NMR relaxometry and MRI measurements indicated a significant proton change in the internal structure for sea cucumber body wall when the heating temperature increased from 45 to 55 °C. Differential scanning calorimetry (DSC) analysis revealed that the denaturation temperature of sea cucumber body wall was in the range of 45–55 °C with an endothermic peak at 51 °C, which is in accordance with the result observed in NMR and MRI. Rheological study showed similar trend to the DSC thermogram. The band change in amide I region of Fourier transform infrared (FTIR) spectra indicated the decrease in α-helix content and possible formation of other secondary structures. Scanning electron microscopy (SEM) further confirmed that the low-temperature heating did induce microstructure changes. The analysis of the Ringer?s soluble fraction (RSF), enzyme-labile fraction (ELF), and total unaltered fraction (TUF) for sea cucumber body wall during low-temperature heating provided more detailed information on the cause of structure change observed in NMR and MRI. The NMR parameters were highly correlated with the rheology storage modulus (G′), relative enzymatic assay parameters, RSF, ELF, and TUF. All these results demonstrated that it could be possible to use NMR and MRI to assess sea cucumber tenderization during low-temperature heating process.     

CELL WALL DEGRADATION IN ENDOSPERM OF BARLEY DURING GERMINATION

The breakdown of the endosperm cell walls during germination of barley has been investigated by fluorescence microscopy, and scanning and transmission electron microscopy. The border between cell wall modified and unmodified endosperm is very clear-cut. Even though fluorescence microscopy of Calcofluor stained sections seems to show the cell wall to be completely degraded, scanning and transmission electron microscopy reveal remnants of the cell wall after the front of cell wall degrading enzymes has passed. Ultra-thin sections indicate that these remnants consist of the middle lamella containing fibrillar material, which is degraded slowly during germination.     

Microscopic Structure of Opalescent and Nonopalescent Pecans

ABSTRACT: The ultrastructure of pecans was investigated using light microscopy, environmental scanning electron microscopy, scanning electron microscopy, and transmission electron microscopy. Specific methodology for the sample preparation of pecans for electron microscopy investigations was developed. Electron microscopy of the ultrastructure of opalescent (discoloration of the interior) and nonopalescent kernels revealed that cellular damage was occurring in opalescent kernels. The damage was due to cell wall and membrane rupture, which accounted for the release of oil throughout the kernel. This rupture is due to the lower level of calcium in the cell membranes of opalescent pecans, as shown by energy dispersive X-ray spectrometry, making them more susceptible to damage.     

微波强化浸取天然色素机理的探讨

利用扫描电子显微技术和透射电了显微技术，分析了微波强化浸取天然色素和传统加热浸取天然色素过程中的柚皮细胞结构，发现微波强化浸取的机理与传统加热浸取的机理不同，在此研究的基础上提出了细胞壁的“电穿孔”机理。     

肉桂精油对成团泛菌和腐生葡萄球菌的抑菌活性及其机理

本文利用滤纸片法和二倍稀释法分别测定了肉桂精油对成团泛菌及腐生葡萄球菌的抑菌圈直径、最小抑菌浓度(MIC)以及最小杀菌浓度(MBC)来评估肉桂精油对其的抑菌活性,通过扫描电镜、透射电镜探究肉桂精油对成团泛菌和腐生葡萄球菌的形态影响,以及通过测定细胞膜的通透性、细胞膜的完整性和膜电位来共同阐释肉桂精油对两种菌活性抑制的机理。结果表明肉桂精油对成团泛菌和腐生葡萄球菌的生长均有较强的抑制作用,且对腐生葡萄球菌的抑菌作用明显强于成团泛菌的抑制作用;肉桂精油改变细胞的形态、增加膜的通透性、破坏了膜的完整性、并造成了细胞内容物的泄露、膜电位的降低,从而导致细菌的死亡。      

Distribution of microorganisms with particular reference to encapsulated bacteria in kefir grains

Propagable and non-propagable kefir grains in a form resembling cauliflower florets were observed by scanning electron microscopy (SEM) and light microscopy. In propagable grains short and long rod-shaped bacteria and yeasts formed separate colonies on the outside surface and inside. Internally, filaments which derived from capsules around the cells extended radially from a population of long rod-shaped bacteria. In non-propagable grains long rod-shaped bacteria with filamentous appendages were not observed, but only short rod-shaped bacteria and yeasts. Indian ink preparations showed presence of encapsulated bacteria in propagable grains and absence of these in non-propagable ones. The above results suggest that encapsulated bacteria are responsible for propagation of kefir grains.