Dermal surface morphology in wound healing. An experimental scanning electron microscope study

The authors observed, with a scanning electron microscope, the dermal surfaces of experimental wounds, following the enzymatic digestion with trypsin of the dermo-epidermal junction. Cut lesions showed an early reconstitution of the basement membrane and progressive convergence of the margins. A peculiar arrangement of the dermal crests was also observed. In wounds with loss of substance, the complete coating by newly formed basement membrane took longer. There was an early deformation of the holes of hair follicles in the undamaged dermis surrounding the lesion, as well as the appearance of creases that moved toward the center. This process was over within a few days; then the lesion became very small and the holes of the hair follicles reappeared. The results suggest a force of traction bound toward the center of the lesion and acting on the surface, the effects of which on the basement membrane are most evident between the eighth and the 15th days.     

人体血液体外电击致血细胞穿孔的扫描电镜观察

目的探讨血细胞体外电击时细胞膜的结构变化。方法对成人血液分别分组通过220V交流电电击5,10,20,30s和1min后,用扫描电镜观察血细胞膜的变化。结果电击后,即可以观察到红细胞与白细胞的细胞膜穿孔,其中红细胞穿孔可为一个或多个,形状多为圆形或卵圆形,白细胞穿孔则为多个,呈筛网状;穿孔细胞数随电击时间延长而增多;电击5s时为6%左右,以后逐渐增加,至电击1min时,穿孔细胞数可达40%左右。结论电流作用可以使血细胞膜发生穿孔,穿孔细胞数随通电时间延长而增多。     

Identification of wires and the cutting tool by scanning electron microscope

The cut ends of aluminium and copper wires made by different pliers have been compared under the scanning electron microscope to correlate the two pieces of a wire and to identify the cutting tool. The mechanism of producing the cut ends has been discussed. Matching of extrusion marks and correspondence of breakages at the edges of the cut ends were observed. Correspondence between the fine striations was observed on the opposite faces. These features are put forward for assigning a cut wire to a source.The ends produced by repeatedly cutting a wire by the same portion of the edge of a pair of pliers have been compared. It was found that the striations and fracture zones were reproduced on the respective surfaces of the consecutive cut ends. To identify the cutting tool in wire theft cases, it is suggested that the trial cut ends can be made by cutting the wire with successive portions of the edge of the suspected tool and compare the surface features with that on the questioned ones.     

环境扫描电镜在法庭科学中的应用与展望

环境扫描电镜（ESEM）在法庭科学的研究和实践工作中,有着重要的作用,它不仅具有普通扫描电镜的各类功能,还可以调整样品室内的气压和湿度,并且可在环境条件下对二次电子成像,因此,ESEM能够直接观察非导电导热样品表面的超微结构。这些特点使得ESEM在法庭科学中有着广阔的应用前景。     

Registration of fingertip pattern with dental impression materials: A scanning electron microscope study

A scanning electron microscope (SEM) study has been made on fingerprints taken with three dental impression materials and a replica tape. A comparative analysis of the impression materials revealed that clearest SEM images were obtained with a Kerr wax-based, type I Compound. Other advantages of this material are its low cost and convenience in handling. Impression plaster was found to be somewhat inferior to Compound due mainly to the porosity of this material. Xantopren, a silicon-based material, gave excellent resolution. However, this was associated with many artefacts that rendered the specimen difficult to interpret. The replica tape was inappropriate for use with specimens as large as whole fingertips. The advantages of examination with SEM are its three dimensional images and the option of using an image inversion mode for accurate reconstruction of the actual fingertip pattern.     

扫描电镜/能谱观察溺死和死后入水的法医学应用研究

目的探讨扫描电镜/能谱分析在溺死的法医学鉴定中的作用。方法实验选用20例已知生前入水尸体,11例已知的死后入水尸体和2例陆地死亡尸体。在每个肺叶各取3个切面,每个切面用扫描电镜取样台胶面与肺叶的切面充分接触,另在落水地点取水样一份,进行对比。扫描电镜取样台胶在切面上充分接触后封闭取材盒,真空干燥后,直接在扫描电镜下进行观察。结果20例生前入水尸体在肺组织中均检出异物颗粒,并且与对照水样中检出的异物颗粒相吻合;而死后入水的尸体和在陆地上死亡的尸体肺组织中均未检出明显的异物颗粒,3者比较P<0.0001。在肺组织支气管切面中,生前入水的20例中有15例检出异物颗粒,在边缘肺切面及中间切面中分别有13例检出异物颗粒,统计学无明显差异。结论本实验建立的肺脏内异物颗粒取材方法准确可靠实用。对综合判断案件的性质,判断溺死尸体入水地点的具有积极意义。较好地解决了实验室检验中的污染问题。腐败尸体对检测结果无影响。     

广东珠江水域硅藻种类调查

目的应用扫描电镜对广东珠江水域水中硅藻进行观察,获得珠江水域硅藻种类情况及分布状况,结果有助于法医学水中尸体死亡原因及落水水域的推断。方法收集了广东省珠江水域19个取水点的水样,采用勒福特王水进行消解,并应用扫描电镜进行观察。结果 (1)19个采样点共检出直链藻、卵形藻、小环藻、菱板藻、菱形藻、双菱藻、针杆藻、冠盘藻、舟形藻、曲壳藻、圆筛藻、短缝藻、桥弯藻、海链藻、布纹藻、波缘藻、等片藻、辐节藻、双壁藻、异极藻和羽纹藻21种硅藻,分属于羽纹纲和中心纲。(2)获得19个采样点硅藻分布数据资料。结论 (1)珠江水域硅藻种类具有一定的特点。(2)不同河域硅藻种类、数量的差异有助于法医学推断溺死落水地点。     

Scanning electron microscope study of the lung in drowning

The authors describe the results obtained using the scanning electron microscope (SEM) to study drowned lungs and control lungs. Results are compared with a previous study carried out using laboratory animals. The results from both studies are analogous, in the absence of chronic pulmonary emphysema. The diagnosis of chronic pulmonary emphysema is simple with the SEM even when dealing with autoptic material obtained 24 to 48 h after death, but the diagnosis of drowning becomes difficult in lungs with chronic emphysema.     

Visualization of latent fingerprints using fluorescence lifetime imaging on paper emitting strong fluorescence

Latent fingerprints were successfully visualized using fluorescence lifetime imaging (FLIM) on paper which emits strong fluorescence with a lifetime close to that of fingerprints and thus from which it is difficult for time-resolved spectroscopy to visualize fingerprints. Latent fingerprint samples on paper were excited using a 450 nm or 532 nm nanosecond pulsed-laser, and time-resolved fluorescence images were obtained at a delay time of 6–16 ns in intervals of 1 ns, to the excitation pulse. The excitation beam was expanded using a lens, and the fluorescence from the fingerprints was captured using an intensified CCD camera. Because of the large fluorescence intensity of the background paper of approximately two to four orders of magnitude larger than that of the fingerprint, the fingerprint was not visualized on each fluorescence image by time-resolved spectroscopy. However, the fingerprint was visualized in a FLIM image constructed using a series of the fluorescence images for the case with the fluorescence intensity of the background paper being four orders of magnitude larger than that of the fingerprint. The difference in fluorescence lifetime in the FLIM image of the visualized fingerprint and background paper was in the order of 0.1 ns, which was an order of magnitude smaller than the inherent fluorescence lifetime of a few nanoseconds for the fingerprints and paper. It was demonstrated that, at a background fluorescence intensity with a certain order of magnitude larger than that of fingerprints, FLIM has the potential to visualize latent fingerprints which cannot be visualized by time-resolved spectroscopy.