Strip silicon waveguide for code synchronization in all-optical analog-to-digital conversion based on a lumped time-delay compensation scheme

An all-optical analog-to-digital converter （ADC） based on the nonlinear effect in a silicon waveguide is a promising candidate for overcoming the limitation of electronic devices and is suitable for photonic integration. In this paper, a lumped time-delay compensation scheme with 2-bit quantization resolution is proposed. A strip silicon waveguide is designed and used to compensate for the entire time-delays of the optical pulses after a soliton self-frequency shift （SSFS） module within a wavelength range of 1550 nm-1580 nm. A dispersion coefficient as high as -19800 ps/（km.nm） with ＋0.5 ps/（km.nm） variation is predicted for the strip waveguide. The simulation results show that the maximum supportable sampling rate （MSSR） is 50.45 GSa/s with full width at half maximum （FWHM） variation less than 2.52 ps, along with the 2-bit effective- number-of-bit and Gray code output.

Design of a 20-Gsps 12-bit time-interleaved analog-to-digital conversion system

The time-interleaved analog-to-digital conversion(TIADC)technique is an effective method for increasing the sampling rate in a waveform digitization system.In this study,a 20-Gsps TIADC system was designed.A wide-bandwidth performance was achieved by optimizing the analog circuits,and a sufficient effective number of bits(ENOB)performance guaranteed using the perfect reconstruction algorithm for mismatch error correction.The proposed system was verified by tests,and the results indicated that a-3 dB bandwidth of 6 GHz and the ENOB performance of 8.7 bits at 1 GHz and 7.6 bits at6 GHz were successfully achieved.

Code synchronization based on lumped time-delay compensation scheme with a linearly chirped fiber Bragg grating in all-optical analog-to-digital conversion

We propose a novel lumped time-delay compensation scheme for all-optical analog-to-digital conversion based on soliton self-frequency shift and optical interconnection techniques. A linearly chirped fiber Bragg grating is optimally designed and used to compensate for the entire time-delays of the quantized pulses precisely. Simulation results show that the compensated coding pulses are well synchronized with a time difference less than 3.3 ps, which can support a maximum sampling rate of 151.52 GSa/s. The proposed scheme can efficiently reduce the structure complexity and cost of all-optical analog-to-digital conversion compared to the previous schemes with multiple optical time-delay lines.

Analog-to-digital conversion of information in the retina

We considered the physiological mechanisms of functioning of the retina’s neural network. It is marked that the primary function of a neural network is an analog-to-digital conversion of the receptor potential of photoreceptor into the pulse-to-digital signal to ganglion cells. We showed the role of different types of neurons in the work of analog-to-digital converter. We gave the equivalent circuit of this converter. We researched the mechanism of the numeric coding of the receptor potential of the photoreceptor.

Optical Analog-to-digital Conversion Scheme Based on Tunable Fabry-Perot Resonator

Proposed is an interference type of optical analog-to-digital conversion(ADC). The refractive index of Fabry-Perot cavity changes with different voltages. The Fabry-Perot resonator converts electronic intensity into light wavelength through selecting lights of different wavelengthes. The parameters of the scheme are acquired with the transmission matrix of optical element and the time of steady-state light field. The maximum sampling speedes of 4-bit, 6-bit, 7-bit, 8-bit and 9-bit(ADC) are 1.695×1010 count/s, 4.33×109 count/s, 2.38×109 count/s, 1.24×109 count/s and 5.9×108 count/s, respectively.

Enabling heterogeneous catalysis to achieve carbon neutrality: Directional catalytic conversion of CO_(2) into carboxylic acids

The increase in anthropogenic carbon dioxide(CO_(2))emissions has exacerbated the deterioration of the global environment,which should be controlled to achieve carbon neutrality.Central to the core goal of achieving carbon neutrality is the utilization of CO_(2) under economic and sustainable conditions.Recently,the strong need for carbon neutrality has led to a proliferation of studies on the direct conversion of CO_(2) into carboxylic acids,which can effectively alleviate CO_(2) emissions and create high-value chemicals.The purpose of this review is to present the application prospects of carboxylic acids and the basic principles of CO_(2) conversion into carboxylic acids through photo-,electric-,and thermal catalysis.Special attention is focused on the regulation strategy of the activity of abundant catalysts at the molecular level,inspiring the preparation of high-performance catalysts.In addition,theoretical calculations,advanced technologies,and numerous typical examples are introduced to elaborate on the corresponding process and influencing factors of catalytic activity.Finally,challenges and prospects are provided for the future development of this field.It is hoped that this review will contribute to a deeper understanding of the conversion of CO_(2) into carboxylic acids and inspire more innovative breakthroughs.

Pathologically successful conversion hepatectomy for advanced giant hepatocellular carcinoma after multidisciplinary therapy:A case report and review of literature

BACKGROUND Hepatocellular carcinoma(HCC)is one of the leading causes of death due to its complexity,heterogeneity,rapid metastasis and easy recurrence after surgical resection.We demonstrated that combination therapy with transcatheter arterial chemoembolization(TACE),hepatic arterial infusion chemotherapy(HAIC),Epclusa,Lenvatinib and Sintilimab is useful for patients with advanced HCC.CASE SUMMARY A 69-year-old man who was infected with hepatitis C virus(HCV)30 years previously was admitted to the hospital with abdominal pain.Enhanced computed tomography(CT)revealed a low-density mass in the right lobe of the liver,with a volume of 12.9 cm×9.4 cm×15 cm,and the mass exhibited a“fast-in/fast-out”pattern,with extensive filling defect areas in the right branch of the portal vein and an alpha-fetoprotein level as high as 657 ng/mL.Therefore,he was judged to have advanced HCC.During treatment,the patient received three months of Epclusa,three TACE treatments,two HAIC treatments,three courses of sintilimab,and twenty-one months of lenvatinib.In the third month of treatment,the patient developed severe side effects and had to stop immunotherapy,and the Lenvatinib dose had to be halved.Postoperative pathological diagnosis indicated a complete response.The patient recovered well after the operation,and no tumor recurrence was found.CONCLUSION Multidisciplinary conversion therapy for advanced enormous HCC caused by HCV infection has a significant effect.Individualized drug adjustments should be made during any treatment according to the patient's tolerance to treatment.

Two-photon live imaging of direct glia-to-neuron conversion in the mouse cortex

Over the past decade,a growing number of studies have reported transcription factor-based in situ reprogramming that can directly conve rt endogenous glial cells into functional neurons as an alternative approach for n euro regeneration in the adult mammalian central ne rvous system.Howeve r,many questions remain regarding how a terminally differentiated glial cell can transform into a delicate neuron that forms part of the intricate brain circuitry.In addition,concerns have recently been raised around the absence of astrocyte-to-neuron conversion in astrocytic lineage-tra cing mice.In this study,we employed repetitive two-photon imaging to continuously capture the in situ astrocyte-to-neuron conversion process following ecto pic expression of the neural transcription factor NeuroD1 in both prolife rating reactive astrocytes and lineage-tra ced astrocytes in the mouse cortex.Time-lapse imaging over several wee ks revealed the ste p-by-step transition from a typical astrocyte with numero us short,tapered branches to a typical neuro n with a few long neurites and dynamic growth cones that actively explored the local environment.In addition,these lineage-converting cells were able to migrate ra dially or to ngentially to relocate to suitable positions.Furthermore,two-photon Ca2+imaging and patch-clamp recordings confirmed that the newly generated neuro ns exhibited synchronous calcium signals,repetitive action potentials,and spontaneous synaptic responses,suggesting that they had made functional synaptic connections within local neural circuits.In conclusion,we directly visualized the step-by-step lineage conversion process from astrocytes to functional neurons in vivo and unambiguously demonstrated that adult mammalian brains are highly plastic with respect to their potential for neuro regeneration and neural circuit reconstruction.

Dealuminated Hβ zeolite for selective conversion of fructose to furfural and formic acid

The fructose-to-furfural transformation is facing major challenges in the selectivity and high efficiency. Herein, we have developed a simple and effective approach for the selective conversion of fructose to furfural using Hβ zeolite modified by organic acids for dealuminization to regulate its textural and acidic properties. It was found that citric acid-dealuminized Hβ zeolite possessed high specific surface areas, wide channels and high Brønsted acid amount, which facilitated the selective conversion of fructose to furfural with a maximum yield of 76.2% at433 K for 1 h in the γ-butyrolactone(GBL)-H_(2)O system, as well as the concomitant formation of 83.0% formic acid. The^(13)C-isotope labelling experiments and the mechanism revealed that the selective cleavage of C1–C2 or C5–C6 bond on fructose was firstly occurred to form pentose or C5 intermediate by weak Brønsted acid, which was then dehydrated to furfural by strong Brønsted acid. Also this dealuminized Hβ catalyst showed the great recycling performance and was active for the conversion of glucose and mannose.

Oxygen functionalization-assisted anionic exchange toward unique construction of flower-like transition metal chalcogenide embedded carbon fabric for ultra-long life flexible energy storage and conversion

The metal-organic framework(MOF)derived Ni–Co–C–N composite alloys(NiCCZ)were“embedded”inside the carbon cloth(CC)strands as opposed to the popular idea of growing them upward to realize ultrastable energy storage and conversion application.The NiCCZ was then oxygen functionalized,facilitating the next step of stoichiometric sulfur anion diffusion during hydrothermal sulfurization,generating a flower-like metal hydroxysulfide structure(NiCCZOS)with strong partial implantation inside CC.Thus obtained NiCCZOS shows an excellent capacity when tested as a supercapacitor electrode in a three-electrode configuration.Moreover,when paired with the biomass-derived nitrogen-rich activated carbon,the asymmetric supercapacitor device shows almost 100%capacity retention even after 45,000 charge–discharge cycles with remarkable energy density(59.4 Wh kg^(-1)/263.8μWh cm^(–2))owing to a uniquely designed cathode.Furthermore,the same electrode performed as an excellent bifunctional water-splitting electrocatalyst with an overpotential of 271 mV for oxygen evolution reaction(OER)and 168.4 mV for hydrogen evolution reaction(HER)at 10 mA cm−2 current density along with 30 h of unhinged chronopotentiometric stability performance for both HER and OER.Hence,a unique metal chalcogenide composite electrode/substrate configuration has been proposed as a highly stable electrode material for flexible energy storage and conversion applications.

Reversible solid-liquid conversion enabled by self-capture effect for stable non-flow zinc-bromine batteries

Non-flow aqueous zinc-bromine batteries without auxiliary components(e.g.,pumps,pipes,storage tanks)and ion-selective membranes represent a cost-effective and promising technology for large-scale energy storage.Unfortunately,they generally suffer from serious diffusion and shuttle of polybromide(Br^(-),Br^(3-))due to the weak physical adsorption between soluble polybromide and host carbon materials,which results in low energy efficiency and poor cycling stability.Here,we develop a novel self-capture organic bromine material(1,10-bis[3-(trimethylammonio)propyl]-4,4'-bipyridinium bromine,NVBr4)to successfully realize reversible solid complexation of bromide components for stable non-flow zinc-bromine battery applications.The quaternary ammonium groups(NV^(4+)ions)can effectively capture the soluble polybromide species based on strong chemical interaction and realize reversible solid complexation confined within the porous electrodes,which transforms the conventional“liquid-liquid”conversion of soluble bromide components into“liquid-solid”model and effectively suppresses the shuttle effect.Thereby,the developed non-flow zinc-bromide battery provides an outstanding voltage platform at 1.7 V with a notable specific capacity of 325 mAh g^(-1)NVBr4(1 A g^(-1)),excellent rate capability(200 mAh g^(-1)NVBr4 at 20 A g^(-1)),outstanding energy density of 469.6 Wh kg^(-1)and super-stable cycle life(20,000 cycles with 100%Coulombic efficiency),which outperforms most of reported zinc-halogen batteries.Further mechanism analysis and DFT calculations demonstrate that the chemical interaction of quaternary ammonium groups and bromide species is the main reason for suppressing the shuttle effect.The developed strategy can be extended to other halogen batteries to obtain stable charge storage.

Conversion therapy of a giant hepatocellular carcinoma with portal vein thrombus and inferior vena cava thrombus:A case report and review of literature

BACKGROUND The prognosis of hepatocellular carcinoma(HCC)combined with portal and hepatic vein cancerous thrombosis is poor,for unresectable patients the combination of targeted therapy and immune therapy was the first-line recommended treatment for advanced HCC,with a median survival time of only about 2.7-6 months.In this case report,we present the case of a patient with portal and hepatic vein cancerous thrombosis who achieved pathologic complete response after conversion therapy.CASE SUMMARY In our center,a patient with giant HCC combined with portal vein tumor thrombus and hepatic vein tumor thrombus was treated with transcatheter arterial chemoembolization(TACE),radiotherapy,targeted therapy and immunotherapy,and was continuously given icaritin soft capsules for oral regulation.After 7 months of conversion therapy,the patient's tumor shrank and the tumor thrombus subsided significantly.The pathology of surgical resection was in complete remission,and there was no progression in the postoperative follow-up for 7 months,which provided a basis for the future strategy of combined conversion therapy.CONCLUSION In this case,atezolizumab,bevacizumab,icaritin soft capsules combined with radiotherapy and TACE had a good effect.For patients with hepatocellular carcinoma combined with hepatic vein/inferior vena cava tumor thrombus,adopting a high-intensity,multimodal proactive strategy under the guidance of multidisciplinary team(MDT)is an important attempt to break through the current treatment dilemma.

Photonic Analog-to-Digital Conversion of Time-Continuous Signals using a TDM Switching-Wavelength Sampling Source

A 20 Gsample/s photonic analog-to-digital converter is constructed using a 4-switching-wavelength repetitive sampling pulse source. The signal-to-noise and distortion ratio (SINAD) is measured to be 44.5 dB and corresponds to 7 effective number of bits.

Electronic structure engineering of transition metal dichalcogenides for boosting hydrogen energy conversion electrocatalysts

Electrocatalytic water splitting for hydrogen production is an appealing strategy to reduce carbon emissions and generate renewable fuels.This promising process,however,is limited by its sluggish reaction kinetics and high-cost catalysts.The two-dimensional(2D)transition metal dichalcogenides(TMDCs)have presented great potential as electrocatalytic materials due to their tunable bandgaps,abundant defective active sites,and good chemical stability.Consequently,phase engineering,defect engineering and interface engineering have been adopted to manipulate the electronic structure of TMDCs for boosting their exceptional catalytic performance.Particularly,it is essential to clarify the local structure of catalytically active sites of TMDCs and their structural evolution in catalytic reactions using atomic resolution electron microscopy and the booming in situ technologies,which is beneficial for exploring the underlying reaction mechanism.In this review,the growth regulation,characterization,particularly atomic configurations of active sites in TMDCs are summarized.The significant role of electron microscopy in the understanding of the growth mechanism,the controlled synthesis and functional optimization of 2D TMDCs are discussed.This review will shed light on the design and synthesis of novel electrocatalysts with high performance,as well as prompt the application of advanced electron microscopy in the research of materials science.

Ultra-broadband and wide-angle reflective terahertz polarization conversion metasurface based on topological optimization

Terahertz polarization conversion devices have significant potential applications in various fields such as terahertzimaging and spectroscopy.In this paper,we utilize genetic algorithms to topologically optimize the metasurface unit cellsand design a reflective linear polarization conversion metasurface with ultra-broadband and wide-angle characteristics.By partitioning the metallic pattern layer into quadrants,the encoding length is effectively reduced,resulting in a shorteroptimization time.The research results indicate that the converter possesses a polarization conversion efficiency ratio higherthan 90%and a relative bandwidth ratio of 125%in a range of 0.231-0.995 THz.Meanwhile,it can maintain excellentpolarization conversion properties when the incident angle of terahertz waves is less than 45°and the polarization angle isless than 15°,demonstrating excellent practicality.New insights are provided for the design of terahertz wide-angle ultrawidebandpolarization conversion devices,and the proposed metasurfce has potential applications in terahertz polarizationimaging,spectroscopy and communication fields.

1.42-fold enhancement of formate selectivity by linker conversion on the Zn-based metal organic framework catalyst

Electro-reduction of carbon dioxide(ERCO_(2)) is considered an effective method to alleviate the greenhouse effect and produce value-added chemicals.Achieving the dominant selectivity of Zn-based catalysts for formate remains a challenge.In this article,the ZnIn-E_(12) catalyst is successfully prepared by solvent assisted ligand exchange(SALE) method to convert organic ligands,achieving a Faradaic efficiency of 72.28% for formate at-1.26 V vs.RHE(V_(RHE)),which is 1.42 times higher than the original catalyst.Evidence shows that the successful conversion of organic ligands can transform the catalyst from the original large size polyhedron to cross-linked network of particles with a diameter of about 30 nm.The increased specific surface area can expose more active sites and facilitate the electrocatalytic conversion of CO_(2) to formate.This work is expected to provide inspiration for the regulation of formate selectivity and catalyst size in Zn-based catalysts.

Intrinsic polarization conversion and avoided-mode crossing in X-cut lithium niobate microrings

Compared with well-developed free space polarization converters, polarization conversion between TE and TM modes in the waveguide is generally considered to be caused by shape birefringence, like curvature, morphology of waveguide cross section and scattering. Here, we study the polarization conversion mechanism in 1-THz-FSR X-cut lithium niobate microrings with multiple-resonance condition, that is the conversion can be implemented by birefringence of waveguides,which will also introduce an avoided-mode crossing. In the experiment, we find that this mode crossing results in severe suppression of one sideband in local nondegenerate four-wave mixing and disrupts the cascaded four-wave mixing on this side. Simultaneously, we propose one two-dimensional method to simulate the eigenmodes(TE and TM) in X-cut microrings, and the mode crossing point. This work will provide one approach to the design of polarization converters and simulation for monolithic photonics integrated circuits, and may be helpful to the studies of missed temporal dissipative soliton formation in X-cut lithium niobate rings.

Hollow Metal-Organic Framework/MXene/Nanocellulose Composite Films for Giga/Terahertz Electromagnetic Shielding and Photothermal Conversion

With the continuous advancement of communication technology,the escalating demand for electromagnetic shielding interference(EMI)materials with multifunctional and wideband EMI performance has become urgent.Controlling the electrical and magnetic components and designing the EMI material structure have attracted extensive interest,but remain a huge challenge.Herein,we reported the alternating electromagnetic structure composite films composed of hollow metal-organic frameworks/layered MXene/nanocellulose(HMN)by alternating vacuum-assisted filtration process.The HMN composite films exhibit excellent EMI shielding effectiveness performance in the GHz frequency(66.8 dB at Kaband)and THz frequency(114.6 dB at 0.1-4.0 THz).Besides,the HMN composite films also exhibit a high reflection loss of 39.7 dB at 0.7 THz with an effective absorption bandwidth up to 2.1 THz.Moreover,HMN composite films show remarkable photothermal conversion performance,which can reach 104.6℃under 2.0 Sun and 235.4℃under 0.8 W cm^(−2),respectively.The unique micro-and macrostructural design structures will absorb more incident electromagnetic waves via interfacial polarization/multiple scattering and produce more heat energy via the local surface plasmon resonance effect.These features make the HMN composite film a promising candidate for advanced EMI devices for future 6G communication and the protection of electronic equipment in cold environments.

Insight into structure evolution of carbon nitrides and its energy conversion as luminescence

A series of carbon nitride(CN)materials represented by graphitic carbon nitride(g-C_(3)N_(4))have been widely used in bioimaging,biosensing,and other fields in recent years due to their nontoxicity,low cost,and high luminescent quantum efficiency.What is more attractive is that the luminescent properties such as wavelength and intensity can be regulated by controlling the structure at the molecular level.Hence,it is time to summarize the related research on CN structural evolution and make a prospect on future developments.In this review,we first summarize the research history and multiple structural evolution of CN.Then,the progress of improving the luminescence performance of CN through structural evolution was discussed.Significantly,the relationship between CN structure evolution and energy conversion in the forms of photoluminescence,chemiluminescence,and electrochemiluminescence was reviewed.Finally,key challenges and opportunities such as nanoscale dispersion strategy,luminous efficiency improving methods,standardization evaluation,and macroscopic preparation of CN are highlighted.

Enhancing I^(0)/I^(-)Conversion Efficiency by Starch Confinement in Zinc-lodine Battery

The redox couple of I^(0)/I^(-)in aqueous rechargeable iodine–zinc(I^(2)-Zn)batteries is a promising energy storage resource since it is safe and cost-effective,and provides steady output voltage.However,the cycle life and efficiency of these batteries remain unsatisfactory due to the uncontrolled shuttling of polyiodide(I_(3)^(-)and I_(5)^(-))and side reactions on the Zn anode.Starch is a very low-cost and widely sourced food used daily around the world.“Starch turns blue when it encounters iodine”is a classic chemical reaction,which results from the unique structure of the helix starch molecule–iodine complex.Inspired by this,we employ starch to confine the shuttling of polyiodide,and thus,the I^(0)/I^(-)conversion efficiency of an I^(2)-Zn battery is clearly enhanced.According to the detailed characterizations and theoretical DFT calculation results,the enhancement of I^(0)/I^(-)conversion efficiency is mainly originated from the strong bonding between the charged products of I_(3)^(-)and I_(5)^(-)and the rich hydroxyl groups in starch.This work provides inspiration for the rational design of high-performance and low-cost I^(2)-Zn in AZIBs.