Subject to the diffraction limit, the resolution of conventional optical microscopy is constrained to about 200 and 500 nm in the lateral and axial planes, respectively. The advantage of optical microscopy in the life sciences over electronic microscopy, especially fluorescence microscopy, drives scientists to develop novel "hacks" to reach nanoscale resolutions by optical means. In this review, three aspects of the techniques are discussed: (1) lateral super-resolution; (2) axial super-resolution; (3) super-resolution in three dimensions. The principles of how the methods achieve the cross-barrier resolution are discussed, and recent advances in current techniques are described. With these methods, the use of fluorescence microscopy is growing quickly toward a new era: fluorescence nanoscopy that will reveal 2 orders of magnitude more information on cellular structure and dynamics.
The emergent light distribution of a new type of contact laser scalpel is measured in three different states using a light sensor. The relationship between the angle and the light intensity is analyzed. The results show that the strongest light is emitted from two sides and the front of the scalpel. The light from the front mainly plays a role of cutting. The light from two sides contributes to stanch the wound so as to remain a clear visual field during the surgery. It also helps to increase the cutting efficiency.
Objective The optic nerve is a key component regarding research on visual prosthesis.Previous pharmacological and electrical studies has pinned down the main features of the mechanisms underlying the nerve impulse in the rat optic nerve,and this work proposed a mathematical model to simulate these phenomena.Methods The main active nodal channels：fast Na^＋,persistent Na^,slow K^＋ and a fast repolarizing K^＋（A-current）were added on a double layer representation of the axon.A simplified representation of K^＋ accumulation and clearance in the vicinity of the Ranvier node was integrated in this model.Results The model was able to generate the following features.In the presence of 4-aminopyridine （4-AP）,spike duration increased and a depolarizing afterpotential（DAP）appeared.In the presence of 4-AP and tetraethylammonium（TEA）,the DAP was followed by a hyperpolarizing afterpotential（AHP）and the amplitude of this AHP increased with the frequency of the stimulation.In normal conditions（no drugs）：DAP and AHP were absent after a single action potential（AP）and a short train of AP;there was a relative refractoriness in amplitude lasting for 30 ms after an AP;an early AHP was revealed by a continuous depolarizing current;and there was a partial spike adaptation for a long current step stimulus.Conclusion The model successfully reproduced previous experiments results including long-lasting stimulation experiment,which is known to modify nerve physiological parameter values and is a key issue for visual prosthesis research.
A control system used in high performance liquid chromatograph(HPLC) was described.The control system adopting low pressure gradient elution was tested with different initial and end volume fractions,and four types of gradient elution curves.The experimental results verified the theoretical analyses of the applied method.This self-designed control system can achieve approving accuracy,repeatability and low cost,which has a bright outlook for domestic applications.
