Thermoacoustic tomography of in vivo rat brain

We present for the¯rst time in vivo imaging of rat brain using microwave-induced thermoacoustic tomography(TAT).The in vivo imaging of rat brain was realized through an unconventional delivery of microwave energy from the front of rat brain(while the transducer was scanned along coronal plane of the animal brain),which maximized the microwave penetration into the brain.In addition,we found that the imaging contrast was highly dependent on the direction of the electric¯eld polarization(EFP)and that more tissue structures/compositions could be revealed when both X-and Y-EFPs were used for TAT.The in vivo TAT images of rat brain obtained were compared with the 3.0 T MRI images and histological photographs,and numerous important brain anatomical structures were identi¯ed.An example of our TAT approach for imaging a foreign object embedded in a rat brain was also demonstrated.This study suggests that TAT has a great potential to be used in neuroscience studies and in noninvasive imaging of brain disorders.

A comparative study on water and dry coupling in photoacoustic tomography of the finger joints

We present a systematical study on comparison between water and dry coupling in photoacoustic tomography of the humanfinger joints.Compared to the direct water immersion of thefinger for water coupling,the dry coupling is realized through a transparent PDMSfilm-based water bag,which ensures water-free contact with the skin.The results obtained suggest that the dry cou-pling provides image quality comparable to that by water coupling while eliminating the wrin-kling of thefinger joint caused by the water immersion.In addition,the dry coupling offers more stable hemodynamic images than the water coupling as the water immersion of thefinger joint causes reduction in blood vessel size.

Recent advances in deep-learning-enhanced photoacoustic imaging

Photoacoustic imaging(PAI),recognized as a promising biomedical imaging modality for preclinical and clinical studies,uniquely combines the advantages of optical and ultrasound imaging.Despite PAI’s great potential to provide valuable biological information,its wide application has been hindered by technical limitations,such as hardware restrictions or lack of the biometric information required for image reconstruction.We first analyze the limitations of PAI and categorize them by seven key challenges:limited detection,low-dosage light delivery,inaccurate quantification,limited numerical reconstruction,tissue heterogeneity,imperfect image segmentation/classification,and others.Then,because deep learning(DL)has increasingly demonstrated its ability to overcome the physical limitations of imaging modalities,we review DL studies from the past five years that address each of the seven challenges in PAI.Finally,we discuss the promise of future research directions in DL-enhanced PAI.

Injectable melatonin-loaded carboxymethyl chitosan(CMCS)-based hydrogel accelerates wound healing by reducing inflammation and promoting angiogenesis and collagen deposition

Carboxymethyl chitosan(CMCS)-based hydrogels have antibacterial activity,and have shown the abilities of preventing wound infection,promoting cell proliferation,accelerating collagen deposition,and stimulating hyaluronic acid formation during wound healing.As a hormone produced by the pineal gland in humans and animals,melatonin promotes skin wound healing by regulating the release of inflammatory mediators and accelerating the proliferation and migration of cells,angiogenesis,and collagen deposition.However,the combined effects of CMCS and melatonin on wound healing remain unclear.Injectable CMCS-based hydrogels containing melatonin were prepared,and their healing effects were evaluated using a full-thickness cutaneous wound model in rats.Compared with the control and the hydrogel with no melatonin groups,the melatonin-loaded hydrogel significantly increased the percentage of wound closure,promoted the proliferation of granulation tissue and re-epithelialization,and accelerated collagen deposition.Additionally,the melatonin-loaded hydrogel promoted angiogenesis and vascular endothelial growth factor receptor protein expression and increased the expression of cyclooxygenase-2 and inducible nitric oxide synthase.The melatonin-loaded hydrogel also markedly increased the expression of collagen III,α-smooth muscle actin,and transforming growth factor-β1 proteins and reduced collagen I expression.These results suggest that the melatonin-loaded hydrogel promoted granulation tissue formation and accelerated wound healing by reducing inflammation and promoting angiogenesis and collagen deposition.

Normalized solutions and mass concentration for supercritical nonlinear Schrodinger equations

In this paper,we deal with the existence and concentration of normalized solutions to the supercritical nonlinear Schrodinger equation {-Δu+V(x)u=μ_(q)u+a|u|^(q)u in R^(2),∫_(R^(2))|u|^(2)dx=1,where μ_(q) is the Lagrange multiplier.We show that for q>2 close to 2,the problem admits two solutions:one is the local minimal solution u_(q) and the other one is the mountain pass solution v_(q).Furthermore,we study the limiting behavior of u_(q) and v_(q) when q→2_(+).Particularly,we describe precisely the blow-up formation of the excited state v_(q).