Morphological and palynological assessment of taxonomically problematic genus Paspalum based on light and scanning electron microscopy

Present research work was carried out to clarify the variations among species of genus Paspalum morphologically and palynologically as this genus is taxonomically difficult due to having multiple similar morphologically overlapping characters which make it difficult to identify. Henceforth present research work was carried out to delimit taxa within the same genus by morphological and palynological tools through light microscopy (LM) and scanning electron microscopy (SEM). Both these tools are considered as the most useful taxonomic characters for taxonomically problematic genera. The results showed a lot of variations among morphological characters. In Paspalum dilatatum, the upper glume was ovate whereas in the other two species, the upper glume was elliptic. The upper glume apex found in P. dilatatum and Paspalum scrobiculatum was obtuse whereas in Paspalum distichum, upper glume apex was acute. Glume nerves showed variation in all three species. Paspalum distichum was 3 nerved, P. scrobiculatum was 5–7 nerved, and P. dilatatum was 5–9 nerved. All three species showed variation in lemma nerves. Paspalum scrobiculatum had 3 nerved lemma whereas in P. distichum 3–5 nerved and P. dilatatum 5–9 nerved lemma were present. In polar and equatorial view, pollen grains ranged from 25 (20–30) to 37.5 (30–45) μm. Paspalum distichum appeared to be the smallest in size whereas P. dilatatum was the largest. Exine thickness ranged from 0.75 (0.5–1) to 1.35 (1.2–1.5) μm. The higher value of pollen fertility was found in P. scrobiculatum as 87.69% and the lowest value was in P. distichum as 78.08%. Morphological keys were also given for correct identification.     

Taxonomic investigation of selected rust fungi using scanning electron microscopy from Khyber Pakhtunkhwa,Pakistan

Rusts comprises the largest natural group of plant pathogens including approximately 8% of all described Fungi. Rust fungi are extremely plant pathogens responsible for great losses to agriculture productivity. Rust species belong to several genera among which more than half are Puccinia species. In Pakistan, rust causes severe damage to agriculture crops. Current study was carried out to identify and characterize different rust species common in the research area through microscopy and Scanning electron microscopy (SEM) in Khyber Pakhtunkhwa, Pakistan. Morpho-anatomical investigation of each collected rust species was carried out using different standard protocols. The dimensions of spores were measured and snapped under a stereomicroscope. SEM was used to examine the shape, size, and ornamentation of the spores of each rust fungus. Results revealed documentation of seven rust fungi, that is, Melampsora euphorbiae, Phragmidium barclayi, Puccinia nepalensis, P. exhausta, P. menthae, Uromyces capitatus, and Uromyces decorates belong to four different genera, were recorded. SEM revealed that spermogonia and Aecia were missing in most of the rust fungus studied. Uredinia was found in a scattered, irregular, lengthy, and epidermis-enclosed form. Urediniospores were found to be ovulating, elongated, echinulate, globose to sub-globose, ellipsoid to ovoid, and globose to sub-globose. Telia was found as sub-epidermal, amphigenous, dispersed, minute, and spherical cells. Teliospores ranged in form from cylindrical to oblong. The germ pores were detected in both apical (top cell) and basal (bottom cell) idiosyncratic and pedicel-attached cells. The techniques used in the current investigation will aid mycologists in rust identification and microscopic characterization.     

Structure and distribution of antennal sensilla in Pseudosymmachia flavescens (Brenske) (Coleoptera: Scarabaeidae: Melolonthinae)

Morphology, microstructure, and distribution of antennal sensilla were compared between female and male Pseudosymmachia flavescens (Brenske) (Coleoptera: Scarabaeidae: Melolonthinae). Lamellate antennae of P. flavescens were shown to have typical scape, pedicel, and flagellum segments. The flagellum consists of a four-segmented funicle and a three-segmented club. The lengths of their pedicel and funicle were found to be similar in females and males. Distinct sexual differences were observed in the length of lamellar segments. Nine types/subtypes of sensilla were identified on the antennae of both sexes, including Böhm sensilla, sensilla trichodea, sensilla basiconica (SB), and two subtypes for sensilla chaetica, sensilla coeloconica, and sensilla placodea each. Olfactory sensilla (e.g., SB and placodea) are mainly located on three lamellar segments of the antennal club. Variation was also seen in abundance of various types of antennal sensilla, with males possessing significantly more sensilla than females. Sensilla placodea were the most abundant, and their number in males was twice of that in females, showing a clear sexual dimorphism. The difference in the distribution of sensilla placodea might reflect their roles in sexual chemical communication.     

激光扫描红外热波成像技术在无损检测中的应用

对激光扫描热波成像技术与传统的闪光灯激励热波技术进行了比较,介绍了一种基于激光扫描热波成像技术的新型红外无损检测设备,通过试验对所建立的2-D理论模型进行验证,试验结果表明,当激光扫描速度在一定范围内,样品表面温度场的变化服从一维热传导模式,主要表现为厚样品的温度-时间曲线在双对数坐标中为斜率-0.5的直线,与理论模型的结果相符合。并对两种特殊涂层的人工样品进行检测,验证了激光扫描红外热波成像设备的有效性。     

激光扫描式焊接坡口信息传感方法

设计了激光扫描式焊接坡口信息传感器。采用高精度激光测距传感器在工件的坡口上方垂直于焊接方向扫描,获取传感器水平位移和距工件距离的数据二维曲线并进行数据预处理。处理后的数据经微分后得到一阶导数和二阶导数曲线,根据导数曲线的特点找出表征工件表面和坡口面的最优点集,应用最小二乘法对最优点集进行直线拟合,求直线的交点得到相应的坡口信息的特征点,从而获得坡口的信息。     

高合金化Al-Zn-Mg-Cu系7049A合金的连续冷却析出图

研究了所有有技术价值的冷却速率范围内7049A铝合金的析出行为。冷却速率从接近平衡冷却时的慢速条件变化到形成完全超饱和固溶体的高速率,跨越了7个数量级（0．0005到5000K／s）。7049A铝合金连续冷却析出行为采用差热分析（DSC）、扫描电镜（SEM）和维氏硬度测量相结合的方法记录。冷却速率在0．0005到4K／s时,对高合金化、高强度和高淬火敏感性的变形铝合金7049A从固溶温度下的淬火析出行为采用传统的DSC方法研究。在此冷却速率范围内,至少观察到了两个放热反应：一个是在很窄的温度区间430～450℃内的高温反应;另外一个是最低到200℃且范围很宽的低温反应。这两个反应的强度随着冷却速率的增高而降低。采用快速差热分析（DFSC）和差分再加热方法（DRM）对合金淬火冷却速率从慢速到数千K／s时的析出行为进行了研究。该合金不析出沉淀相时的临界淬火速率为100～300K／s。