Anisotropic Strain-Tailoring Nonlinear Optical Response in van der Waals NbOI2.

Two-dimensional (2D) NbOI2 demonstrates significant second-harmonic generation (SHG) with a high conversion efficiency. To unlock its full potential in practical applications, it is desirable to modulate the SHG behavior while utilizing the intrinsic lattice anisotropy. Here, we demonstrate direction-specific modulation of the SHG response in NbOI2 by applying anisotropic strain with respect to the intrinsic lattice orientations, where more than 2-fold enhancement in the SHG intensity is achieved under strain along the polar axis. The strain-driven SHG evolution is attributed to the strengthened built-in piezoelectric field (polar axis) and the enlarged Peierls distortions (nonpolar axis). Moreover, we provide quantifications of the correlation between strain and SHG intensity in terms of the susceptibility tensor. Our results demonstrate the effective coupling of orientation-specific strain to the anisotropic SHG response through the intrinsic polar order in 2D nonlinear optical crystals, opening a new paradigm toward the development of functional devices.

Non-volatile rippled-assisted optoelectronic array for all-day motion detection and recognition.

In-sensor processing has the potential to reduce the energy consumption and hardware complexity of motion detection and recognition. However, the state-of-the-art all-in-one array integration technologies with simultaneous broadband spectrum image capture (sensory), image memory (storage) and image processing (computation) functions are still insufficient. Here, macroscale (2 × 2 mm2) integration of a rippled-assisted optoelectronic array (18 × 18 pixels) for all-day motion detection and recognition. The rippled-assisted optoelectronic array exhibits remarkable uniformity in the memory window, optically stimulated non-volatile positive and negative photoconductance. Importantly, the array achieves an extensive optical storage dynamic range exceeding 106, and exceptionally high room-temperature mobility up to 406.7 cm2 V-1 s-1, four times higher than the International Roadmap for Device and Systems 2028 target. Additionally, the spectral range of each rippled-assisted optoelectronic processor covers visible to near-infrared (405 nm-940 nm), achieving function of motion detection and recognition.

Artificial ovaries constructed from biodegradable chitin-based hydrogels with the ability to restore ovarian endocrine function and alleviate osteoporosis in ovariectomized mice.

BACKGROUND: Artificial ovary (AO) is an alternative approach to provide physiological hormone to post-menopausal women. The therapeutic effects of AO constructed using alginate (ALG) hydrogels are limited by their low angiogenic potential, rigidity, and non-degradability. To address these limitations, biodegradable chitin-based (CTP) hydrogels that promote cell proliferation and vascularization were synthesized, as supportive matrix. METHODS: In vitro, follicles isolated from 10-12-days-old mice were cultured in 2D, ALG hydrogels, and CTP hydrogels. After 12 days of culture, follicle growth, steroid hormone levels, oocyte meiotic competence, and expression of folliculogenesis-related genes were monitored. Additionally, follicles isolated from 10-12-days-old mice were encapsulated in CTP and ALG hydrogels and transplanted into the peritoneal pockets of ovariectomised (OVX) mice. After transplantation, steroid hormone levels, body weight, rectal temperature, and visceral fat of the mice were monitored every two weeks. At 6 and 10 weeks after transplantation, the uterus, vagina, and femur were collected for histological examination. RESULTS: The follicles developed normally in CTP hydrogels under in vitro culture conditions. Additionally, follicular diametre and survival rate, oestrogen production, and expression of folliculogenesis-related genes were significantly higher than those in ALG hydrogels. After one week of transplantation, the numbers of CD34-positive vessels and Ki-67-positive cells in CTP hydrogels were significantly higher than those in ALG hydrogels (P < 0.05), and the follicle recovery rate was significantly higher in CTP hydrogels (28%) than in ALG hydrogels (17.2%) (P < 0.05). After two weeks of transplantation, OVX mice implanted with CTP grafts exhibited normal steroid hormone levels, which were maintained until week eight. After 10 weeks of transplantation, CTP grafts effectively ameliorated bone loss and atrophy of the reproductive organs, as well as prevented the increase in body weight and rectal temperature in OVX mice, which were superior to those elicited by ALG grafts. CONCLUSIONS: Our study is the first to demonstrate that CTP hydrogels support follicles longer than ALG hydrogels in vitro and in vivo. The results highlight the clinical potential of AO constructed using CTP hydrogels in the treatment of menopausal symptoms.

Short-term synaptic plasticity in emerging devices for neuromorphic computing.

Neuromorphic computing is a promising computing paradigm toward building next-generation artificial intelligence machines, in which diverse types of synaptic plasticity play an active role in information processing. Compared to long-term plasticity (LTP) forming the foundation of learning and memory, short-term plasticity (STP) is essential for critical computational functions. So far, the practical applications of LTP have been widely investigated, whereas the implementation of STP in hardware is still elusive. Here, we review the development of STP by bridging the physics in emerging devices and biological behaviors. We explore the computational functions of various STP in biology and review their recent progress. Finally, we discuss the main challenges of introducing STP into synaptic devices and offer the potential approaches to utilize STP to enrich systems' capabilities. This review is expected to provide prospective ideas for implementing STP in emerging devices and may promote the construction of high-level neuromorphic machines.

High-strength, antibacterial, antioxidant, hemostatic, and biocompatible chitin/PEGDE-tannic acid hydrogels for wound healing.

Natural polymer hydrogels are widely used in various aspects of biomedical engineering, such as wound repair, owing to their abundance and biosafety. However, the low strength and the lack of function restricted their development and application scope. Herein, we fabricated novel multifunctional chitin/PEGDE-tannic acid (CPT) hydrogels through chemical- and physical-crosslinking strategies, using chitin as the base material, polyethylene glycol diglycidyl ether (PEGDE) and tannic acid (TA) as crosslinking agents, and 90 % ethanol as the regenerative bath. CPT hydrogels maintained a stable three-dimensional porous structure with suitable water contents and excellent biocompatibility. The mechanical properties of hydrogels were greatly improved (tensile stress up to 5.43 ± 1.14 MPa). Moreover, CPT hydrogels had good antibacterial, antioxidant, and hemostatic activities and could substantially promote wound healing in a rat model of full-thickness skin defect by regulating inflammatory responses and promoting collagen deposition and blood vessel formation. Therefore, this work provides a useful strategy to fabricate novel multifunctional CPT hydrogels with excellent mechanical, antibacterial, antioxidant, hemostatic, and biocompatible properties. CPT hydrogels could be promising candidates for wound healing.

Ovarian tissue transplantation ameliorates osteoporosis and dyslipidaemia in ovariectomised mice.

BACKGROUND: Ovarian insufficiency frequently renders postmenopausal women susceptible to osteoporosis and dyslipidaemia. Postmenopausal transplant women are at a higher risk developing osteoporosis and dyslipidaemia due to the concomitant application of glucocorticoids and immunosuppressants after solid organ transplantation. Thus, this study aimed to explore the feasibility of ovarian tissue transplantation (OTT) as an alternative to Hormone replacement therapy (HRT) for postmenopausal women with solid organ transplant needs. RESULTS: Sixty mice were randomly divided into four groups: sham operation, ovariectomised (OVX group), ovariectomy plus oestrogen (E2 group), and ovariectomy plus OTT (OTT group). The inhibin levels in the OTT group were increased and the follicle stimulating hormone and luteinizing hormone were suppressed to normal levels, which could not be achieved in the E2 group. The femoral bone mineral density in the OTT group was significantly increased than the E2 group (P < 0.05), and the probability of fracture was reduced by 1.4-2.6 times. Additionally, the high-density lipoprotein cholesterol levels were higher in the OTT group than in the E2 group and the triglyceride levels were lower in the OTT group than in the E2 group (P < 0.05). CONCLUSION: OTT not only achieves certain endocrine effects by participating in the regulation of the hypothalamic-pituitary-ovarian feedback control loop, but also ameliorates osteoporosis and dyslipidaemia, which may be an alternative to traditional HRT for postmenopausal women with solid organ transplant needs.

Two dimensional semiconducting materials for ultimately scaled transistors.

Two dimensional (2D) semiconductors have been established as promising candidates to break through the short channel effect that existed in Si metal-oxide-semiconductor field-effect-transistor (MOSFET), owing to their unique atomically layered structure and dangling-bond-free surface. The last decade has witnessed the significant progress in the size scaling of 2D transistors by various approaches, in which the physical gate length of the transistors has shrank from micrometer to sub-one nanometer with superior performance, illustrating their potential as a replacement technology for Si MOSFETs. Here, we review state-of-the-art techniques to achieve ultra-scaled 2D transistors with novel configurations through the scaling of channel, gate, and contact length. We provide comprehensive views of the merits and drawbacks of the ultra-scaled 2D transistors by summarizing the relevant fabrication processes with the corresponding critical parameters achieved. Finally, we identify the key opportunities and challenges for integrating ultra-scaled 2D transistors in the next-generation heterogeneous circuitry.

Discovering Content through Text Mining for a Synthetic Biology Knowledge System.

Scientific articles contain a wealth of information about experimental methods and results describing biological designs. Due to its unstructured nature and multiple sources of ambiguity and variability, extracting this information from text is a difficult task. In this paper, we describe the development of the synthetic biology knowledge system (SBKS) text processing pipeline. The pipeline uses natural language processing techniques to extract and correlate information from the literature for synthetic biology researchers. Specifically, we apply named entity recognition, relation extraction, concept grounding, and topic modeling to extract information from published literature to link articles to elements within our knowledge system. Our results show the efficacy of each of the components on synthetic biology literature and provide future directions for further advancement of the pipeline.

Modulation of Spin Dynamics in 2D Transition-Metal Dichalcogenide via Strain-Driven Symmetry Breaking.

Transition metal dichalcogenides (TMDs) possess intrinsic spin-orbit interaction (SOI) with high potential to be exploited for various quantum phenomena. SOI allows the manipulation of spin degree of freedom by controlling the carrier's orbital motion via mechanical strain. Here, strain modulated spin dynamics in bilayer MoS2 field-effect transistors (FETs) fabricated on crested substrates are demonstrated. Weak antilocalization (WAL) is observed at moderate carrier concentrations, indicating additional spin relaxation path caused by strain fields arising from substrate crests. The spin lifetime is found to be inversely proportional to the momentum relaxation time, which follows the Dyakonov-Perel spin relaxation mechanism. Moreover, the spin-orbit splitting is obtained as 37.5 ± 1.4 meV, an order of magnitude larger than the theoretical prediction for monolayer MoS2 , suggesting the strain enhanced spin-lattice coupling. The work demonstrates strain engineering as a promising approach to manipulate spin degree of freedom toward new functional quantum devices.

Artificially created interfacial states enabled van der Waals heterostructure memory device.

Two-dimensional (2D) interface plays a predominate role in determining the performance of a device that is configured as a van der Waals heterostructure (vdWH). Intensive efforts have been devoted to suppressing the emergence of interfacial states during vdWH stacking process, which facilitates the charge interaction and transfer between the heterostructure layers. However, the effective generation and modulation of the vdWH interfacial states could give rise to a new design and architecture of 2D functional devices. Here, we report a 2D non-volatile vdWH memory device enabled by the artificially created interfacial states between hexagonal boron nitride (hBN) and molybdenum ditelluride (MoTe2). The memory originates from the microscopically coupled optical and electrical responses of the vdWH, with the high reliability reflected by its long data retention time over 104s and large write-erase cyclic number exceeding 100. Moreover, the storage currents in the memory can be precisely controlled by the writing and erasing gates, demonstrating the tunability of its storage states. The vdWH memory also exhibits excellent robustness with wide temperature endurance window from 100 K to 380 K, illustrating its potential application in harsh environment. Our findings promise interfacial-states engineering as a powerful approach to realize high performance vdWH memory device, which opens up new opportunities for its application in 2D electronics and optoelectronics.

Friend or Foe? The Roles of Antioxidants in Acute Lung Injury.

Acute lung injury (ALI) is an acute hypoxic respiratory insufficiency caused by various intra- and extra-pulmonary injury factors. The oxidative stress caused by excessive reactive oxygen species (ROS) produced in the lungs plays an important role in the pathogenesis of ALI. ROS is a "double-edged sword", which is widely involved in signal transduction and the life process of cells at a physiological concentration. However, excessive ROS can cause mitochondrial oxidative stress, leading to the occurrence of various diseases. It is well-known that antioxidants can alleviate ALI by scavenging ROS. Nevertheless, more and more studies found that antioxidants have no significant effect on severe organ injury, and may even aggravate organ injury and reduce the survival rate of patients. Our study introduces the application of antioxidants in ALI, and explore the mechanisms of antioxidants failure in various diseases including it.

Erratum to "The Inhibition of P-Selectin Reduced Severe Acute Lung Injury in Immunocompromised Mice".

[This corrects the article DOI: 10.1155/2020/8430465.].

Protective Effects of Estrogen on Cardiovascular Disease Mediated by Oxidative Stress.

Perimenopause is an important stage of female senescence. Epidemiological investigation has shown that the incidence of cardiovascular disease in premenopausal women is lower than that in men, and the incidence of cardiovascular disease in postmenopausal women is significantly higher than that in men. This phenomenon reveals that estrogen has a definite protective effect on the cardiovascular system. In the cardiovascular system, oxidative stress is considered important in the pathogenesis of atherosclerosis, myocardial dysfunction, cardiac hypertrophy, heart failure, and myocardial ischemia. From the perspective of oxidative stress, estrogen plays a regulatory role in the cardiovascular system through the estrogen receptor, providing strategies for the treatment of menopausal women with cardiovascular diseases.

Advances in the applications of polymer biomaterials for in vitro follicle culture.

The ovarian reserve (OR) indicates ovarian function by representing the quantity and quality of ovarian follicles, and it gradually decreases with increasing age. With the prolongation of women's lives, the protection provided by estrogen is lost for decades in postmenopausal women, and the related cardiovascular and cerebrovascular diseases, osteoporosis, and decreased immunity are the main risk factors affecting women's quality of life and longevity. Pharmacologic hormone replacement therapy (PHRT) has been controversial, and the construction of artificial ovary (AO) has attracted increasing attention. The most critical step of AO generation is the establishment of an in vitro culture (IVC) system to support the development of isolated follicles. This article mainly compares the advantages and disadvantages of different polymer biomaterials for use in follicle IVC, provides theoretical support for the development and construction of the follicle IVC system using natural biological materials, and provides a theoretical basis for establishing mature AO technology.

Dielectric Engineered Two-Dimensional Neuromorphic Transistors.

Two-dimensional (2D) materials, which exhibit planar-wafer technique compatibility and pure electrically triggered communication, have established themselves as potential candidates in neuromorphic architecture integration. However, the current 2D artificial synapses are mainly realized at a single-device level, where the development of 2D scalable synaptic arrays with complementary metal-oxide-semiconductor compatibility remains challenging. Here, we report a 2D transition metal dichalcogenide-based synaptic array fabricated on commercial silicon-rich silicon nitride (sr-SiNx) substrate. The array demonstrates uniform performance with sufficiently high analogue on/off ratio and linear conductance update, and low cycle-to-cycle variability (1.5%) and device-to-device variability (5.3%), which are essential for neuromorphic hardware implementation. On the basis of the experimental data, we further prove that the artificial synapses can achieve a recognition accuracy of 91% on the MNIST handwritten data set. Our findings offer a simple approach to achieve 2D synaptic arrays by using an industry-compatible sr-SiNx dielectric, promoting a brand-new paradigm of 2D materials in neuromorphic computing.

Engineering Spiking Neurons Using Threshold Switching Devices for High-Efficient Neuromorphic Computing.

Inspired by the human brain, the spike-based neuromorphic system has attracted strong research enthusiasm because of the high energy efficiency and powerful computational capability, in which the spiking neurons and plastic synapses are two fundamental building blocks. Recently, two-terminal threshold switching (TS) devices have been regarded as promising candidates for building spiking neurons in hardware. However, how circuit parameters affect the spiking behavior of TS-based neurons is still an open question. Here, based on a leaky integrate-and-fire (LIF) neuron circuit, we systematically study the effect of both the extrinsic and intrinsic factors of NbO x -based TS neurons on their spiking behaviors. The extrinsic influence factors contain input intensities, connected synaptic weights, and parallel capacitances. To illustrate the effect of intrinsic factors, including the threshold voltage, holding voltage, and high/low resistance states of NbO x devices, we propose an empirical model of the fabricated NbO x devices, fitting well with the experimental results. The results indicate that with enhancing the input intensity, the spiking frequency increases first then decreases after reaching a peak value. Except for the connected synaptic weights, all other parameters can modulate the spiking peak frequency under high enough input intensity. Also, the relationship between energy consumption per spike and frequency of the neuron cell is further studied, leading guidance to design neuron circuits in a system to obtain the lowest energy consumption. At last, to demonstrate the practical applications of TS-based neurons, we construct a spiking neural network (SNN) to control the cart-pole using reinforcement learning, obtaining a reward score up to 450. This work provides valuable guidance on building compact LIF neurons based on TS devices and further bolsters the construction of high-efficiency neuromorphic systems.

Hypoxia-Inducible Factor-1: A Potential Target to Treat Acute Lung Injury.

Acute lung injury (ALI) is an acute hypoxic respiratory insufficiency caused by various intra- and extrapulmonary injury factors. Presently, excessive inflammation in the lung and the apoptosis of alveolar epithelial cells are considered to be the key factors in the pathogenesis of ALI. Hypoxia-inducible factor-1 (HIF-1) is an oxygen-dependent conversion activator that is closely related to the activity of reactive oxygen species (ROS). HIF-1 has been shown to play an important role in ALI and can be used as a potential therapeutic target for ALI. This manuscript will introduce the progress of HIF-1 in ALI and explore the feasibility of applying inhibitors of HIF-1 to ALI, which brings hope for the treatment of ALI.

Optically Controllable 2D Material/Complex Oxide Heterointerface.

Heterostructures play a vital role in functional devices on the basis of the individual constituents. Non-conventional heterostructures formed by stacking 2D materials onto structurally distinct materials are of great interest in achieving novel phenomena that are both scientifically and technologically relevant. Here, a heterostructure based on a 2D (molybdenum ditelluride) MoTe2 and an amorphous strontium titanium oxide (a-STO) thin film is reported. The heterostructure functions as a high-performance photodetector, which exhibits anomalous negative photoresponse in the pristine device due to the scattering effect from the light-induced Oδ- ions. The photoresponsivity and the specific detectivity are found to be >104 AW-1 and >1013 Jones, respectively, which are significantly higher than those in standard MoTe2 devices. Moreover, through tuning the light programming time, the photodetection behavior of the MoTe2/a-STO heterostructure experiences a dynamic evolution from negative to positive. This is due to the optically controllable modulation of the interfacial states, which is further confirmed by the X-ray photoelectron spectroscopy and photoluminescence measurements. It is envisioned that the 2D material/a-STO heterostructure could be a potential platform for exploring new functional devices.

Polarized Light-Emitting Diodes Based on Anisotropic Excitons in Few-Layer ReS2.

An on-chip polarized light source is desirable in signal processing, optical communication, and display applications. Layered semiconductors with reduced in-plane symmetry have inherent anisotropic excitons that are attractive candidates as polarized dipole emitters. Herein, the demonstration of polarized light-emitting diode based on anisotropic excitons in few-layer ReS2 , a 2D semiconductor with excitonic transition energy of 1.5-1.6 eV, is reported. The light-emitting device is based on minority carrier (hole) injection into n-type ReS2 through a hexagonal boron nitride (hBN) tunnel barrier in a metal-insulator-semiconductor (MIS) van der Waals heterostack. Two distinct emission peaks from excitons are observed at near-infrared wavelength regime from few-layer ReS2 . The emissions exhibit a degree of polarization of 80% reflecting the nearly 1D nature of excitons in ReS2 .

Native Oxide Seeded Spontaneous Integration of Dielectrics on Exfoliated Black Phosphorus.

Two-dimensional (2D) semiconductors have been a central focus for next-generation electronics and optoelectronics owing to their great potential to extend the scaling limits in a silicon transistor. However, due to the lack of surface dangling bonds in most 2D semiconductors, such as graphene and transition metal dichalcogenides (TMDs), the direct growth of the high-κ film on these 2D materials via an atomic layer deposition (ALD) technique often produces dielectrics with poor quality, which hinders their integration in the modern semiconductor industry. Here, we comprehensively investigate the ALD growth of the Al2O3 layer on 2D exfoliated black phosphorus (BP). Intriguingly, we found that the 2D BP with "silicon-like" characteristics possesses a native surface oxide layer PxOy after air exposure. The PxOy-induced surface dangling bonds enable the spontaneous integration of the high-quality Al2O3 layer on the BP flake without any pretreatments to functionalize the surface. Additionally, the Al2O3 layer could effectively passivate BP to prevent its degradation in ambient conditions, which addresses the most serious problem of the BP material. Moreover, the Al2O3-encapsulated BP field-effect transistor (FET) exhibits good electrical transport performance, with a high hole mobility of ∼420 cm2 V-1 s-1 and electron mobility of ∼80 cm2 V-1 s-1. Moreover, the high-quality Al2O3 layer can also be integrated into the top-gated BP transistor and inverter. Our findings reveal the silicon-like characteristics of BP for the high-κ ALD dielectric growth technology, which promises the seamless integration of 2D BP in the modern semiconductor industry.