The use of x-ray imaging in medicine and other research is well known. Generally, the image quality is proportional to the total flux, but high photon energy could severely damage the specimen, so how to decrease the radiation dose while maintaining image quality is a fundamental problem. In "ghost" imaging, an image is retrieved from a known patterned illumination field and the total intensity transmitted through the object collected by a bucket detector. Using a table-top x-ray source we have realized ghost imaging of plane and natural objects with ultra-low radiation on the order of single photons. Compared with conventional x-ray imaging, a higher contrast-to-noise ratio is obtained for the same radiation dose. This new technique could greatly reduce radiation damage of biological specimens.

It has been an outstanding challenge to achieve implantable energy modules that are mechanically soft (compatible with soft organs and tissues), have compact form factors, and are biodegradable (present for a desired time frame to power biodegradable, implantable medical electronics). Here, we present a fully biodegradable and bioabsorbable high-performance supercapacitor implant, which is lightweight and has a thin structure, mechanical flexibility, tunable degradation duration, and biocompatibility. The supercapacitor with a high areal capacitance (112.5 mF cm−2 at 1 mA cm−2) and energy density (15.64 μWh cm−2) uses two-dimensional, amorphous molybdenum oxide (MoOx) flakes as electrodes, which are grown in situ on water-soluble Mo foil using a green electrochemical strategy. Biodegradation behaviors and biocompatibility of the associated materials and the supercapacitor implant are systematically studied. Demonstrations of a supercapacitor implant that powers several electronic devices and that is completely degraded after implantation and absorbed in rat body shed light on its potential uses.

Ga2O3, as an emerging optoelectronic material, is very appealing for the detection of ionizing radiation because of its low cost, wide band gap (4.5–5.0 eV) and radiation hardness. In this work, a flexible X-ray detector using amorphous Ga2O3 (a-Ga2O3) thin film is demonstrated. The a-Ga2O3 thin film was deposited on polyethylene naphthalate (PEN) substrate with delicately control of the oxygen flux during the radio frequency (RF) magnetron sputtering process. Metal/semiconductor/metal-structured photodetectors with coplanar interdigital electrodes were fabricated on this a-Ga2O3 film. Temporal response measurements under X-ray illumination indicate that a larger photocurrent occurs on the film deposited with smaller oxygen flux. A model combined with theoretical calculation is proposed to explain the enhancement of the X-ray photoresponsivity, which involves the slowing down of the annihilation rate caused by the neutralization of more ionized oxygen vacancy (Vo) states. No significant degradation of the device performance under UV and X-ray radiation is observed after the flexibility test. This finding informs a novel way to design the flexible X-ray and other ionizing radiation detectors based on amorphous oxide materials.

are new types of semiconductors in which adjacent layers are held by van der Waals force. [1] TMDs have many rich physical properties such as extremely weak phonon-assisted photoluminescence (PL) in bulk structures, relatively strong PL yield in monolayer structures, [2][3][4][5] strong valley-dependent absorption in visible range, [6][7][8] and strong nonlinear optical response. [9][10][11][12] By taking advantage of these properties, significant progresses have been made in the development of electronic and optoelectronic technologies by these materials, [13,14] such as photodetectors, [15] field-effect transistors, [16][17][18] solar cells, [19,20] light-emitting diodes, [21,22] valleytronics, [8,23] integrated circuits, [24] and so on.The exciton binding energy in the monolayer TMDs has been observed in the range of 0.1-1.1 eV, [25][26][27][28] which is larger than that in traditional bulk semiconductors and traditional quantum well. [29,30] This rich excitonic state makes it possible to observe the complex exciton dynamics at room temperature, [31] such as charged and neutral phase of carriers, [32] trions, [33] and biexciton. [34] Meanwhile, bounded exciton could not only dominate the optical response but also play an important role in the optoelectronic processes, such as photocurrent generation and photoconduction in TMD semiconductors. [33,35,36] As a typical TMD material, the bulk WSe 2 has an indirect bandgap of 1.2 eV, and it would transform to the ≈1.65 eV direct bandgap as decreasing to monolayer. [37,38] WSe 2 has been widely used in optoelectronic devices due to its high absorption coefficients in the visible range. Field-effect transistors based on single crystal WSe 2 have been achieved and a carrier mobility comparable to silicon at room temperature was demonstrated. [39] Besides, WSe 2 can also play an important role in the development of van der Waals heterostructures, [40][41][42] in which long-lived interlayer excitons have been observed.Recently, ultrafast time-resolved photoexcited carrier dynamics has been studied in layered TMDs by the most widely used tools, such as optical-pump optical-probe spectroscopy, [43] PL spectroscopy, [38] photocurrent spectroscopy, [36] and electroluminescence. [35,44] The prevalentThe dynamics of photoexcited species is quite important for the development of next-generation ultrafast optoelectronic devices based on transition metal dichalcogenides (TMDs). Herein, time-resolved optical pump terahertz (THz) probe spectroscopy, which is sensitive to both bounded excitons and free electrons/holes, is employed to study the dynamics of photo-induced carriers in the typical layered TMDs crystal tungsten diselenide (WSe 2 ). Initial photoexcitation could generate both free carriers and excitons. The free carriers decay followed by phonon-assistance (≈30 ps) and defect-assistance (≈200-280 ps). The excitons decay followed by the phonon-assisted recombination (≈100 ps) and the defect-induced exciton separation (≈40-200 ps). With the increasing of pump fluence, more f...

Postoperative adhesion is a common complication of abdominal surgery, which always has many adverse effects in patients. At present, there is still a lack of effective treatment measures and materials to prevent adhesion in the clinics. Herein, we report the potential use of J-1-ADP hydrogel formed by natural antimicrobial peptide jelleine-1 (J-1) self-assembling in adenosine diphosphate (ADP) sodium solution to prevent postsurgery adhesion formation. J-1-ADP hydrogel was found to have good antimicrobial activity against the bacteria and fungi tested and can be used to prevent tissue infection, which was thought to be one of the incitements of adhesion. Due to ADP being a platelet-activating factor, J-1-ADP hydrogel showed significant hemostatic activity in vitro verified by whole blood coagulation, plasma coagulation, platelet activation, and platelet adhesion assays. Further, it showed potent hemostatic activity in a mouse liver hemorrhage model. Bleeding was believed to be a cause of the formation of postsurgery adhesion. J-1-ADP hydrogel had a significant antiadhesion effect in a rat side wall defect–cecum abrasion model. In addition, it had good biocompatibility and degradation properties. So the present study may provide an alternative strategy for designing antimicrobial peptide hydrogel material to prevent postoperative adhesion formation in the clinic.

Molecular analogues of the green fluorescent protein (GFP) fluorophore have been designed by these authors (see Figure, X=NC4H9 or O). It is shown that by varying the donor and acceptor groups of the oxazolone (X=O) analogue the fluorescence emission can be tuned from blue to green to orange. The utility of these artificial fluorophores is explored by incorporating them into organic LEDs.

Hydrogel-based flexible electronics have caused widespread interest in recent years. However, current hydrogel electronics have its limitations, such as poor biocompatibility, non-reusability, low electrical response to deformation and functionally single....

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