Nowadays, terahertz (THz) imaging is quite promising in scientific and biomedical applications. However, the much longer wavelength degrades the resolution of obtained images compared with classical imaging at optical frequencies. Imaging is considered to be a convolution process between the object function and point spread function (PSF) of the system. Thus, how to describe the object accurately from a blurred image is an inverse problem. In this paper, we demonstrate how well such a method can function. We would illustrate how to make current facilities overcome the physical limitations in imaging, which can image at the sub-spot level. Periodical stripes with a period of 0.8 mm are resolved at 0.3 THz. The resolution is 0.32 times the physical size of the focused beam. Moreover, this method is extended to the mathematical operations in a complex domain, which is distinct from previous image studies via visible/IR light. Physically, it means that we essentially deal with phase by making use of the wave nature of THz light. For the first time, it is demonstrated that the reconstructed phase can also describe the shape of the object by applying such an approach. In addition, we have successfully measured the diameter of human hair with a relative error of less than 10% at 3 THz. As an example, we did an experiment on tissues of colorectal cancer and a better image is obtained, which would be helpful for medical diagnosis. We believe that such an approach is able to improve imaging performance at THz frequencies and many applications will gain from it.

Background Non‐coding RNAs (ncRNAs) are involved in neuropathic pain development. Herein, we systematically searched for neuropathic pain‐related ncRNAs expression changes, including microRNAs (miRNAs), long non‐coding RNAs (lncRNAs), and circular non‐coding RNAs (circRNAs). Methods We searched two databases, PubMed and GeenMedical, for relevant studies. Results Peripheral nerve injury or noxious stimuli can induce extensive changes in the expression of ncRNAs. For example, higher serum miR‐132‐3p, ‐146b‐5p, and ‐384 was observed in neuropathic pain patients. Either sciatic nerve ligation, dorsal root ganglion (DRG) transaction, or ventral root transection (VRT) could upregulate miR‐21 and miR‐31 while downregulating miR‐668 and miR‐672 in the injured DRG. lncRNAs, such as early growth response 2‐antisense‐RNA (Egr2‐AS‐RNA) and Kcna2‐AS‐RNA, were upregulated in Schwann cells and inflicted DRG after nerve injury, respectively. Dysregulated circRNA homeodomain‐interacting protein kinase 3 (circHIPK3) in serum and the DRG, abnormally expressed lncRNAs X‐inactive specific transcript (XIST), nuclear enriched abundant transcript 1 (NEAT1), small nucleolar RNA host gene 1 (SNHG1), as well as ciRS‐7, zinc finger protein 609 (cirZNF609), circ_0005075, and circAnks1a in the spinal cord were suggested to participate in neuropathic pain development. Dysregulated miRNAs contribute to neuropathic pain via neuroinflammation, autophagy, abnormal ion channel expression, regulating pain‐related mediators, protein kinases, structural proteins, neurotransmission excitatory–inhibitory imbalances, or exosome miRNA‐mediated neuron–glia communication. In addition, lncRNAs and circRNAs are essential in neuropathic pain by acting as antisense RNA and miRNA sponges, epigenetically regulating pain‐related molecules expression, or modulating miRNA processing. Conclusions Numerous dysregulated ncRNAs have been suggested to participate in neuropathic pain development. However, there is much work to be done before ncRNA‐based analgesics can be clinically used for various reasons such as conservation among species, proper delivery, stability, and off‐target effects.

A novel frequency reconfigurable microstrip antenna based on (BST) substrate is presented. Compared to the complicated structures in traditional reconfigurable antennas, our work is featured by a quite concise design. A theoretical model is proposed to calculate the initial antenna parameters. Both the simulation and the experiment indicate that the coupled aperture structure can efficiently overcome impedance mismatch of BST substrate and obtain a frequency tunability of 10% in Ku band by a DC electric field changing from 0 to 10 m. Besides, similar radiation patterns are obtained in the operating band for both the E plane and H plane. Our study shows that the using of BST material on the frequency reconfigurable antenna is promising, and can be easily extended to reconfigurable antenna arrays.Index Terms-BST substrate, DC electric field, frequency reconfigurable antenna, ku band.

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