We developed a photoacoustic imaging system that has real-time imaging capability with optical resolution. The imaging system is capable of scanning at 20 Hz over a 9-mm range, and up to 40 Hz over a 1-mm scanning range. A focused laser beam provides a lateral resolution of 3.4 μm as measured in an optically nonscattering medium. Flows of micron-sized carbon particles or whole blood in a silicone tube and individual red blood cells (RBCs) in mouse ear capillaries were also imaged in real time, which demonstrated the capability to image highly dynamic processes in vivo at a micron-scale resolution.

We present label-free functional photoacoustic imaging of the ocular microvasculature in living animals. The anterior segment of an adult mouse was imaged with a laser exposure level well within the American National Standards Institute safety standards. Individual red blood cells traveling along the iris capillaries were clearly resolved, and the hemoglobin oxygen saturation in the iris microvasculature was imaged spectrally. We believe that photoacoustic imaging has the potential to advance the diagnosis and treatment of ocular diseases in humans.

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Optical-resolution photoacoustic microscopy (OR-PAM) has become a major experimental tool of photoacoustic tomography, with unique imaging capabilities for various biological applications. However, conventional imaging systems are all table-top embodiments, which preclude their use in internal organs. In this study, by applying the OR-PAM concept to our recently developed endoscopic technique, called photoacoustic endoscopy (PAE), we created an optical-resolution photoacoustic endomicroscopy (OR-PAEM) system, which enables internal organ imaging with a much finer resolution than conventional acousticresolution PAE systems. OR-PAEM has potential preclinical and clinical applications using either endogenous or exogenous contrast agents.

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Recently developed optical-resolution photoacoustic microscopy (OR-PAM), which is based on the detection of optical absorption contrast, is complementary to other optical microscopy modalities such as optical confocal microscopy, optical coherence tomography, and multi-photon microscopy. A hybrid optical–mechanical scanning configuration increases the imaging speed of OR-PAM significantly, enabling many demanding biomedical applications. With a high pulse-repetition-rate laser, the hybrid-scanning OR-PAM can acquire one-dimensional depth-resolved images (A-lines) at 5 kHz and two-dimensional B-scan images containing 800 A-lines at 6.25 Hz. We demonstrated in vivo in a mouse three-dimensional imaging of the iris vasculature in 128 seconds for an 800 × 800 × 200 data set and of the ear vasculature in 256 seconds for an 800 × 1600 × 200 data set.

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In arid and semiarid areas, water uptake (non-rainfall water) serves as an important water source for plants, biological soil crusts, insects and small animals. In this study, a measurement program was undertaken to investigate water uptake and its changes during formation of man-made algal crusts in the Qubqi Desert. In the study region, water uptake from the atmosphere accounted for 25.07%-39.83% of the total water uptake, and was mainly taken up by a water vapor adsorption mechanism; the proportion of water uptake from the soil substrate was much higher (60.17%-74.93%). The formation of crusts promoted water uptake, but the increased uptake did not occur immediately after inoculation or crusts formation. The water taken up from the atmosphere increased significantly from day 15 after inoculation, and the soil water content was markedly enhanced from day 20 after inoculation. It is considered that the growth of algal filaments and their secretions were the main factors increasing the amount of water uptake and water content in the crusts, and these variables increased even during dry periods when some algae are likely to have died. desert algae, biological soil crusts, water uptake, upper soil layer Citation:Lan S B, Hu C X, Rao B Q, et al. Non-rainfall water sources in the topsoil and their changes during formation of man-made algal crusts at the eastern edge of Qubqi Desert, Inner Mongolia.