No abstract

With the advancements in nanotechnology, studies on the synthesis, modification, application, and toxicology evaluation of nanomaterials are gaining increased attention. In particular, the applications of nanomaterials in biological systems are attracting considerable interest because of their unique, tunable, and versatile physicochemical properties. Artificially engineered nanomaterials can be well controlled for appropriate usage, and the tuned physicochemical properties directly influence the interactions between nanomaterials and cells. This review summarizes recently synthesized major nanomaterials that have potential biomedical applications. Focus is given on the interactions, including cellular uptake, intracellular trafficking, and toxic response, while changing the physicochemical properties of versatile materials. The importance of physicochemical properties such as the size, shape, and surface modifications of the nanomaterials in their biological effects is also highlighted in detail. The challenges of recent studies and future prospects are presented as well. This review benefits relatively new researchers in this area and gives them a systematic overview of nano-bio interaction, hopefully for further experimental design.

No abstract

With measurements from two ground-based Doppler radars located in northern Taiwan, this study documents the detailed aspects of intense orographic precipitation associated with Typhoon Xangsane (2000) as it moved northward immediately off the eastern coast of Taiwan, bringing strong low-level northeasterly to north-northeasterly winds impinging on the mountainous northern coast. With relatively good, persistent coverage of radar echoes on both inland and upstream regions, this particular event provides a unique description of the orographic precipitation and its relationship with orographic geometry, strong upstream oncoming flow, and the precipitation inherently associated with typhoon circulations. In this case, the heaviest precipitation was observed to occur primarily over two coastal mountain barriers: Mount Da-Tun (DT) and the Nangang-Keelung Range (NKR). Barrier DT is an approximately 3D mountain barrier, and the NKR, adjacent to the southeast of DT, is a relatively lower, narrower 2D mountain range. In particular, the distinct distribution and intensity of precipitation over the two barriers were observed. Analyses of vertical cross sections passing through the major regions of heavy precipitation over DT and NKR indicate the region of low-level heavy precipitation tended to shift downstream as the low-level oncoming flow intensified, and the precipitation exhibited a deeper, wider extent and stronger intensity at stronger oncoming flow regimes. However, changes in the location of maximum precipitation over DT (NKR) were confined mainly to regions over windward slopes (near and downstream of the mountain crest). The degree of downstream shift of low-level heaviest precipitation with respect to different magnitudes of oncoming flow was relatively limited (∼8 km) over NKR, as compared with a larger downstream shift of ∼15–17 km over DT. This contrasting aspect can be understood as a consequence of a longer “lifting section” and relatively lower fall speed of hydrometeors over the windward slope of DT. In addition, the precipitation inherently associated with the typhoon circulations was found to be an important contributor to the observed variations in precipitation intensity over DT and NKR. Stronger background typhoon precipitation and a shorter downstream shift of precipitation (i.e., a quasi-stationary precipitation feature) over NKR may explain the fact of larger precipitation accumulation observed over this narrower, lower barrier.

Using a combination of Doppler radar observations and rain gauge data, this study documents detailed aspects of the orographic precipitation associated with Typhoon Morakot (2009). Rainfall distribution over underlying topographical features and possible physical mechanisms responsible for the observed orographic enhancement are explored. The study region constitutes an approximately two-dimensional, south–north-oriented orographic barrier with higher, wider (lower, narrower) terrain features in its northern (southern) portions (i.e., the northern and southern barriers). Upstream conditions were characterized by abundant typhoon background precipitation embedded within strong, nearly saturated westerly to west-southwesterly oncoming flow. The observations show that a wide area of topographically enhanced precipitation and the rainfall maxima were confined to the windward slopes of the northern barrier, whereas the strongest rainfall tended to occur near and/or slightly downstream of the mountain crest of the southern barrier. Quantitative analysis indicates that upslope lifting may explain the observed precipitation enhancement over the northern barrier; however, this mechanism was found to be less relevant to precipitation enhancement for the southern barrier. The characteristics of the enhanced precipitation observed over the southern barrier are, instead, consistent with the theoretical prediction of the seeder–feeder process. In this context, the degree of orographic enhancement was shown to be proportional to the intensity of the typhoon background precipitation multiplied by the oncoming wind speed. The results suggest that for the tropical cyclone environment, understanding and predicting rainfall over narrow, low mountain ranges is particularly challenging because it involves complex dynamical and microphysical processes.