Intrinsic Nature Research Articles

Self-Assembled Biomolecule Interlayer for Enhanced Efficiency and Stability of Inverted Organic Solar Cells

Interlayers play a vital role in achieving high efficiency and stability of organic solar cells (OSCs). Zinc oxide (ZnO) has been widely used as an electron transport layer (ETL) in inverted OSCs; however, its high structural defects and intrinsic photocatalytic nature toward nonfullerene acceptors limit its applications in OSCs. Herein, a low-cost, environmentally-friendly biomolecule, potassium aspartic acid (PAA), is introduced as the interlayer on top of the ZnO ETL. Through experimental results and theoretical calculations, we find PAA not only can tune energy alignments and passivate oxygen vacancy defects and zinc interstitial dangling bonds but also can promote the π–π stacking strength of the active layer, leading to enhanced charge collection and photovoltaic performance in both IT series (e.g., PM6:IT-4F) and Y series (e.g., PM6:BTP-4F-C5-16) OSCs. Moreover, benefiting from the reduced surface defects of ZnO, OSCs based upon the ZnO/PAA ETL exhibit superior stabilities under continuous operation as well as UV-light irradiation, leading to an improved T80 lifetime of around 4 times compared to OSCs fabricated without the PAA interlayer. This work provides a universal solution to fabricate efficient and stable inverted OSCs.

Quantum phase recognition using quantum tensor networks

Machine learning (ML) has recently facilitated many advances in solving problems related to many-body physical systems. Given the intrinsic quantum nature of these problems, it is natural to speculate that quantum-enhanced machine learning will enable us to unveil even greater details than we currently have. With this motivation, this paper examines a quantum machine learning approach based on shallow variational ansatz inspired by tensor networks for supervised learning tasks. In particular, we first look at the standard image classification tasks using the Fashion-MNIST dataset and study the effect of repeating tensor network layers on ansatz’s expressibility and performance. Finally, we use this strategy to tackle the problem of quantum phase recognition for the transverse-field Ising and Heisenberg spin models in one and two dimensions, where we were able to reach \(\ge 98\%\) test-set accuracies with both multi-scale entanglement renormalization ansatz (MERA) and tree tensor network (TTN) inspired parametrized quantum circuits.

Performance and complexity study of a neural network post-equalizer in a 638-nm laser transmission system through over 100-m plastic optical fiber

In recent years, plastic optical fiber (POF) has been considered as a promising cost-effective scheme for short-distance data communications, multimedia communication in cars, and in-house networks. However, due to the intrinsic nature of the relatively large numerical aperture of POF and the high attenuation rate, implementing high data rates over 100-m POF transmission length will be a significant challenge. We propose a scheme of high-speed 100-m POF transmission system based on a visible red laser and a cascaded neural network (NN) post-equalizer. To mitigate the nonlinear distortion induced by the POF, three different NNs, i.e., convolutional NN (CNN), long and short-term memory NN (LSTM), and cascaded NN structure consisting of convolutional layers and LSTM (CNN-LSTM), are employed as the post-equalizer. Experimental results show that using three different post-equalizers can significantly improve the system performance compared with the Volterra equalizer baseline. Among them, CNN-LSTM can outperform the others in terms of the bit error rate (BER) and the system Q-factor in the low nonlinear region. When the system operating in strong nonlinear region, CNN can achieve optimal performance at a lower system overhead of complexity. Finally, we successfully demonstrated a 100-m POF transmission system using 16 quadrature amplitude modulation discrete Fourier transform-spread orthogonal frequency division multiplexing modulation format at 1.8 Gbps with BER below 3.8 × 10 − 3 by utilizing CNN-LSTM.

Revelation and experimental verification of quasi-periodic bursting, periodic bursting, periodic oscillation in third-order non-autonomous memristive FitzHugh-Nagumo neuron circuit

It has been declared that constructing physical hardware circuits with the reproduction of abundant electrical activities of neurons is significant in neuron-based engineering applications. To this end, a novel third-order non-autonomous memristive FitzHugh-Nagumo (FHN) neuron circuit is designed by employing a first-order generalized memristive-diode-bridge (MDB) emulator and an AC voltage source. The memristive FHN neuron circuit can generate abundant electrical activities since the involvement of the MDB emulator. In theoretical analysis and numerical simulation, the corresponding circuit state equations and normalized system are formulated to analyze the characteristics of the equilibrium point and investigate the dynamical behaviors related to the internal resistor of the MDB emulator. Then phase portrait, time-domain waveform, bifurcation diagram, and Lyapunov exponent spectra are numerically simulated, from which abundant non-chaotic firing activities of quasi-periodic bursting, periodic bursting, and periodic oscillation are revealed. Additionally, the 0–1 test is utilized to further distinguish the above three non-chaotic behaviors. In hardware experiment, a breadboard hardware circuit is constructed and experimental measurements are executed. It is demonstrated that the experimental results well support the numerical simulations. Studying these non-chaotic behaviors is very important to understand the intrinsic nature of neuronal firing activities. Most notably, the numerical revelation and experimental verification of quasi-periodic bursting behavior have been rarely reported in the previously published literature.

Measurement of uniaxial compression mechanical properties of thermally dried coal samples by energy and fragmentation characteristic analyses

This study aimed to determine the effects of different drying temperatures on the mechanical properties of coal samples under axial compression. Processed, screened, and water-saturated coal samples were subjected to a blast drying treatment at 25, 50, 75, 100, and 125 °C for 4 h. Uniaxial compression mechanical experiments were then performed and the fragments were collected and counted after destruction of the coal samples. Based on the above experimental results, the intrinsic nature of the changes in the mechanical properties of uniaxial compression of coal samples after thermal drying is revealed by the energy evolution and the characteristics of fragment distribution. The results show that with an increase in drying temperature, the energy storage capacity of the coal sample tended to first decrease and then increase, and the energy release capacity gradually increased after the peak. The EESERR index increased exponentially with increasing drying temperature after the uniaxial compression of the coal sample reached the damaged state. In addition, as the drying temperature increased, the brittleness of the coal sample was enhanced, the intensity of uniaxial compression damage increased significantly, the fragments tended to be distributed in smaller sizes, and the degree of fragment chaos increased.

Rapid fabrication and screening of tailored functional 3D biomaterials: Validation in bone tissue repair – Part II

Regenerative medicine strategies place increasingly sophisticated demands on 3D biomaterials to promote tissue formation at sites where tissue would otherwise not form. Ideally, the discovery/fabrication of the 3D scaffolds needs to be high-throughput and uniform to ensure quick and in-depth analysis in order to pinpoint appropriate chemical and mechanical properties of a biomaterial. Herein we present a versatile technique to screen new potential biocompatible acrylate-based 3D scaffolds with the ultimate aim of application in tissue repair. As part of this process, we identified an acrylate-based 3D porous scaffold that promoted cell proliferation followed by accelerated tissue formation, pre-requisites for tissue repair. Scaffolds were fabricated by a facile freeze-casting and an in-situ photo-polymerization route, embracing a high-throughput synthesis, screening and characterization protocol. The current studies demonstrate the dependence of cellular growth and vascularization on the porosity and intrinsic chemical nature of the scaffolds, with tuneable 3D scaffolds generated with large, interconnected pores suitable for cellular growth applied to skeletal reparation. Our studies showed increased cell proliferation, collagen and ALP expression, while chorioallantoic membrane assays indicated biocompatibility and demonstrated the angiogenic nature of the scaffolds. VEGRF2 expression in vivo observed throughout the 3D scaffolds in the absence of growth factor supplementation demonstrates a potential for angiogenesis. This novel platform provides an innovative approach to 3D scanning of synthetic biomaterials for tissue regeneration.

Experimental and Numerical Dynamic Investigation of an ORC System for Waste Heat Recovery Applications in Transportation Sector

ORC power units represent a promising technology for the recovery of waste heat in Internal Combustion Engines (ICEs), allowing to reduce emissions while keeping ICE performance close to expectations. However, the intrinsic transient nature of exhaust gases represents a challenge since it leads ORCs to often work in off-design conditions. It then becomes relevant to study their transient response to optimize performance and prevent main components from operating at inadequate conditions. To assess this aspect, an experimental dynamic analysis was carried out on an ORC-based power unit bottomed to a 3 L Diesel ICE. The adoption of a scroll expander and the control of the pump revolution speed allow a wide operability of the ORC. Indeed, the refrigerant mass flow rate can be adapted according to the exhaust gas thermal power availability in order to increase thermal power recovery from exhaust gases. The experimental data confirmed that when the expander speed is not regulated, it is possible to control the cycle maximum pressure by acting on the refrigerant flow rate. The experimental data have also been used to validate a model developed to extend the analysis beyond the experimental operating limits. It was seen that a 30% mass flow rate increase allowed to raise the plant power from 750 W to 830 W.

MACHINE LEARNING AS AN ALTERNATIVE TO 3D PHOTOMODELING EMPLOYED IN ARCHITECTURAL SURVEY AND AUTOMATIC DESIGN MODELLING

Abstract. This paper presents some experiments on the use of an alternative technique, Nerf, based on artificial intelligence, which can be used in the survey of architectural structures or parts of them. The Nvidia video cards supported by the new RTX architectures are now able to manage an enormous amount of data both in the calculation of lighting and the rendering of digital shaders, and in the management of the number of polygons that can be displayed in real time in the scene. The support of artificial intelligence has further improved the three-dimensional digitization process in order to support the hardware power of algorithms that use neural networks to optimize and reduce calculation times, improving various aspects of the graphics and also of the digital representation, also influencing the representation on “image based” 3D acquisition methods, currently the most used low-cost systems in the photomodeling of objects or three-dimensional scenes. At the current state of the art, many commercial companies and research organizations, first Nvidia with its Instant Nerf, are betting on algorithms based on the Neural Radiance Field. The paper highlights the criticalities of this new system and shows the discrete results and the expandable research scenarios that can involve the impossible survey with photomodeling methodology related to works of art or architecture, due to the intrinsic nature of the materials that they compose them or because it is impossible or very difficult to photograph them.

Canonical quasi-geodesic mappings of special pseudo-Riemannian spaces

The present paper continues the study of quasi-geodesic mappings f:(Vn, gij, Fih) → (V'n,g'ij, Fih) of pseudo-Riemannian spaces Vn, V'n with a generalized-recurrent structure Fih of parabolic type. By a generalized recurrent structure of parabolic type on Vn we mean an almost Hermitian affinor structure of parabolic type for which the covariant derivative of the structural affinor Fih satisfies the condition F(i,j)h=q(i Fj)h.
 In the previous paper by the authors [Proc. Intern. Geom. Center, 13:3 (2020) 18-32] it was proved that the class of pseudo-Riemannian spaces with generalized-recurrent structure of parabolic type is closed with respect to the considered mappings and the generalized recurrence vectors in (Vn, gij,Fih) and (V'_n, g'ij, Fih) may be distinct. In this article, it is assumed that the mapping f preserves the generalized recurrence vector qi.
 We construct geometric objects that are invariant under the quasi-geodesic mapping of generalized-recurrent spaces of parabolic type and recurrent-parabolic spaces. A number of conditions are given on these objects, which lead to the fact that a generalized-recurrent space of parabolic type admits a parabolic K-structure, and a recurrent-parabolic space admits a Kählerian structure of parabolic type.
 We study special types of these mappings that preserve some tensors of an intrinsic nature.

Flexible, high-temperature-resistant, highly conductive, and porous siloxane-based single-ion conducting electrolyte membranes for safe and dendrite-free lithium-metal batteries

High-temperature-resistant polymer electrolyte membranes with satisfactory Li-ion transference number (tLi+) and ionic conductivity is desirable for the application in safe and dendrite-proof lithium metal batteries (LMBs). In this study, siloxane-based single-ion conducting polymer electrolyte (SIPE) membranes with high porosity are fabricated by in-situ sol-gel and non-solvent induced phase separation methods. Benefiting from the well-designed three-dimensional interpenetrating polymer network, the thermal and dimensional ability of the as-developed membranes are significantly enhanced. In addition, the porous structure enabling a high liquid electrolyte uptake (468.6%) combines with the intrinsic nature of SIPE for the membranes, giving rise to much higher ionic conductivity of 1.72 × 10−3 S cm−1 and tLi+ of 0.72 compared to commercial polypropylene (PP) separators (3.56 × 10−4 S cm−1 and 0.33) at 25 °C. Such excellent electrochemical properties are beneficial to inhibiting the Li dendrites and impeding short-circuiting of batteries. As expected, the Li/Li symmetrical cells show a stable galvanostatic Li plating/stripping cycling performance with a low overpotential of more than 400 h at 2 mA cm−2. Remarkably, the LiFePO4/Li batteries using the membranes exhibit impressive rate capacity and superior cycling ability compared to the batteries assembled with PP separators. This novel design and exciting results offer tremendous potential in the construction of dendrite-free LMBs with high safety.

Highly flexible all-inorganic nanofiber networks with stress-accommodating microstructure for light-activated wearable chemiresistive sensor

Inorganic semiconductor chemiresistors have been the mainstream of well-explored gas sensing technology. However, the intrinsic fragile and rigid nature seriously impedes their future application in the thriving wearable sensing devices. Herein, we demonstrate a flexible all-inorganic semiconductor-based chemiresistive sensor through in-situ anchoring nanosheets-assembled SnO2/SnS2 sensing layer on flexible yttria-stabilized zirconia (YSZ) ceramic nanofiber networks. It is revealed that the flexible YSZ ceramic substrate possesses low section modulus in bending and good toughness that is mainly derived from its unique nanofiber structure (300 nm in diameter) and ultrafine grain size (16 nm). It is first demonstrated that nanosheets-assembled sensing layer characterized by abundant void spaces plays a pivotal role in affecting the flexibility of inorganic nanofiber networks. The void spaces between SnO2/SnS2 nanosheets, acting as stress-accommodating microstructures, could effectively releasing stress concentration, enabling abnormal mechanical flexibility of inorganic YSZ/SnO2/SnS2 network. In addition, to achieve more compatibility with wearable application and realize room-temperature gas sensing function, visible light rather than traditional high heat is employed as excitation source to activate the flexible YSZ/SnO2/SnS2 chemiresistor. This work shows the possibility of inorganic semiconductor chemiresistor for application in wearable sensing device and offers a valuable guidance for constructing flexible room-temperature inorganic chemiresistor.

Laser-induced Fano asymmetry, electron-phonon coupling, and phase transition in lanthanide sesquioxide (Ln2O3; Ln = Eu, Gd, Dy) nanoparticles: A Raman spectroscopic investigation

Laser power-dependent Raman spectroscopy is deployed to probe Fano interference in asymmetrically broadened Tg modes and the associated line shift in three technologically sound, meticulously characterized rare-earth sesquioxide systems. Group theoretical analysis is accompanied to introspect the Raman-active optic modes in cubic, monoclinic, and trigonal phases and identify the laser heating-induced local phase transitions. With increasing laser intensity, a regular redshift and larger negative asymmetry in the Raman peaks are detected, which is attributed to moderations in Fano scattering by enhanced electron–phonon coupling amid the focussed photoexcited electron plasma and is illustrated using a Feynman diagram. A quantitative study is thereby performed to unveil the intrinsic nature of discrete-continuum Fano resonance in the nanoparticles of interest emphasizing the high sensitivity of Raman spectra to the excitation strength that perturbs the generic vibrational features at the Brillouin zone center by influencing the interference conditions, force constant, and length of the associated bonds compelled by tensile stress. A rising trend of the charge–phonon coupling constant (λ) with laser power validates a stronger particle–quasiparticle coupling, whereas a shorter anharmonic phonon lifetime (τanh) indicates faster interactions. Using Allen's formalism, the charge density of states [N(εF)] at the Fermi level per spin and molecule is calculated, which pertains to a negative regression dependence in the λN(εF)−τanh dynamics.

The influence of non-radiative relaxation on the room-temperature phosphorescence of metalloporphyrin

The room-temperature phosphorescence (RTP) of metalloporphyrins, induced by the heavy atom effect (HAE), has been widely concerned in many fields, and the intense emission of RTP is highly desired. The phosphorescent transition rate ([Formula: see text] has been used to quantitatively characterize the HAE’s intrinsic nature. However, the phosphorescent intensity was not determined by [Formula: see text] alone, non-phosphorescent transition ([Formula: see text] induced by surrounding factors was also involved. In this study, the influence of [Formula: see text] on the RTP of palladium octaethylporphyrin (PdOEP), platinum octaethylporphyrin (PtOEP), and platinum tetraphenylporphyrin (PtTPP) was studied. The effect of [Formula: see text] can be quantitatively described by an introduced parameter [Formula: see text], which was defined as [Formula: see text] = [Formula: see text]/([Formula: see text]. The method is proposed for determining the [Formula: see text] of PdOEP, PtOEP, and PtTPP by the UV-visible absorption spectra, luminescence spectra, and phosphorescence dynamic curves. Our research provides a way to understand the effect of knP on the RTP, and may benefit the development and optimization of metalloporphyrins aiming at intense RTP.

Fluoroalkoxyaluminate-based ionic liquids as electrolytes for sodium-ion batteries

Ionic liquids (ILs) are a promising class of materials because of their unique properties such as high electrochemical stability window and intrinsic conductive nature, which are desirable in the development of high-performance electrolytes for energy storage applications. However, the strong Coulombic interactions between cation and anion, which contributes to the high viscosity of the ILs, are the main bottleneck in their applications as electrolytes. Weakly coordinated anions-based ILs are a class of electrolytes with high degree of charge delocalization, which leads to weak ionic interactions and improves the ionic transport. Here, we have performed molecular dynamics simulations and density functional theory calculations of imidazolium and ammonium-based ionic liquids in different Na+ mole fractions comprising the weakly coordinated fluoroalkoxyaluminate anion ([Al(Ohfip)4]−). The results have shown that the 0.8-scaled OPLS-AA based force field predicted the transport properties of neat systems with good accuracy. The Na+-[anion] pair structural and lifetime analysis suggest that the fluoroalkoxyaluminate promotes lower lifetimes and facilitates the mobility of Na+ in these systems. Although the cations provided similar transport and structural results for Na+, the theoretical electrochemical stability windows of the ammonium-derived ILs exhibited values above 5.0 eV, which indicates good performance for energy storage applications.

Opportunities beyond CO2 for climate mitigation

Opportunities beyond CO2 for climate mitigation

Safety of 6'-sialyllactose (6'-SL) sodium salt produced by derivative strains of Escherichia coli BL21 (DE3) as a novel food pursuant to Regulation (EU) 2015/2283.

Following a request from the European Commission, the EFSA Panelon Nutrition, Novel Foods and Food Allergens (NDA) was asked to deliver an opinion on 6'-sialyllactose (6'-SL) sodium salt as a novel food (NF) pursuant to Regulation (EU) 2015/2283. The NF is mainly composed of the human-identical milk oligosaccharide (HiMO) 6'-SL, but it also contains d-lactose, 6'-sialyllactulose, sialic acid, N-acetyl-d-glucosamine and a small fraction of other related oligosaccharides. The NF is produced by fermentation with two genetically modified strains of Escherichia coli BL21 (DE3), the production strain and the optional degradation strain. The information provided on the identity, manufacturing process, composition and specifications of the NF does not raise safety concerns. The applicant intends to add the NF to a variety of foods, including infant formula and follow-on formula, food for special medical purposes and food supplements. The target population is the general population. In some scenarios at the maximum use levels, the estimated intakes per kg body weight were higher than the high average natural intake of 6'-SL from human milk. However, given the intrinsic nature of human milk oligosaccharides (HMOs), the wide range of intakes from human milk, and considering that infants are naturally exposed to similar amounts of these substances, the Panelconsiders that the consumption of the NF at the proposed conditions of use does not raise safety concerns. The intake of 6'-SL in breastfed infants on a body weight basis is also expected to be safe for other population groups. The intake of other carbohydrate-type compounds structurally related to 6'-SL is also considered of no safety concern. Food supplements are not intended to be used if other foods with added 6'-SL or human milk are consumed on the same day. The Panelconcludes that the NF is safe under the proposed conditions of use.

Stable Operation of a Free-Electron Laser Driven by a Plasma Accelerator.

The breakthrough provided by plasma-based accelerators enabled unprecedented accelerating fields by boosting electron beams to gigaelectronvolt energies within a few centimeters [1-4]. This, in turn, allows the realization of ultracompact light sources based on free-electron lasers (FELs) [5], as demonstrated by two pioneering experiments that reported the observation of self-amplified spontaneous emission (SASE) driven by plasma-accelerated beams [6,7]. However, the lack of stability and reproducibility due to the intrinsic nature of the SASE process (whose amplification starts from the shot noise of the electron beam) may hinder their effective implementation for user purposes. Here, we report a proof-of-principle experiment using plasma-accelerated beams to generate stable and reproducible FEL light seeded by an external laser. FEL radiation is emitted in the infrared range, showing the typical exponential growth of its energy over six consecutive undulators. Compared to SASE, the seeded FEL pulses have energies 2 orders of magnitude larger and stability that is 3 times higher.

Autonomous waves and global motion modes in living active solids

Elastic active matter or active solid consists of self-propelled units embedded in an elastic matrix. Active solid resists deformation; the shape-preserving property and the intrinsic non-equilibrium nature make active solids a superior component for self-driven devices. Nonetheless, the mechanical properties and emergent behavior of active solids are poorly understood. Using a biofilm-based bacterial active solid, here we discovered self-sustained elastic waves with unique wave properties not seen in passive solids, such as power-law scaling of wave speed with activity. Under isotropic confinement, the active solid develops two topologically distinct global motion modes that can be selectively excited, with a surprising step-like frequency jump at mode transition. Our findings reveal novel spatiotemporal order in elastic active matter and may guide the development of solid-state adaptive or living materials.

Structural ordering, magnetic and electrical transport properties in Ni60-xFe13+xGa27 Heusler alloys

The evolutions of phase transformation, magnetic and electrical transport properties with the change of Fe concentration have been systematically investigated in a series of Ni60-xFe13+xGa27 (x = 0–10) Heusler alloys. The structure and heat flow measurements reveal every sample undergoes a disordered-ordered transition from a disordered B2 structure to a L21 ordered structure, and a first-order structural transformation from the L21 cubic structure to a L10 tetragonal structure is corresponding to the martensitic transformation (MT). With increasing Fe concentration, the disordered-ordered transition and ferromagnetic transition shift to higher temperature, while the MT shifts to lower temperature. According to phase diagram established in the present investigation, it is also found that the increase of Fe content can convert the first-order MT from a paramagnetic type to a ferromagnetic one, which is accompanying by an obvious increase of both effective and spontaneous magnetic moments. Furthermore, the calculated magnetocrystalline anisotropy constant (K1) of the studied alloys monotonically increases as Fe increases. It is evident that the magnetic degrees of freedom in these two MTs remain almost unchanged so that the electron-spin scattering doesn't change, which results in the resistivity difference between the austenitic and martensitic states is feeble. Such an intrinsic nature leads to a weak magnetoresistance (MR) and baroresistance (BR) effects in the studied samples because of only contribution of electron-lattice scattering change on the resistivity. This demonstrates from a negative perspective that the electron-spin scattering change originated from the variation in the magnetic degrees of freedom acts as a dominant role in improvement of the MR and BR effects for the Heusler system possessed the first-order MT.

The decentralization effects of entrepreneurial characteristics on corporate social responsibility.

The question of whether appropriate decentralization can solve Corporate Social Responsibility (CSR) misplacement caused by Entrepreneurial Characteristics (EC) is an interesting ethical puzzle. Because corporate behavior depends on the decision-making choices of executives whose personality characteristics affect the choice tendency, power distribution undoubtedly becomes a big boost for most businesses to work out the adverse externality problems. Based on Upper Echelons Theory, this study developed a comparative impact model linking the effects of entrepreneurial intrinsic nature and experience characteristics on CSR performance. We tested the effective mechanism with the mediator role of the Corporate Power Distribution Index (CPDI) through a sample of listed Chinese companies from 2009 to 2017. The results provide that EC, such as female Gender, Degree, and Salary, have positive effects on CSR; CPDI plays a mediator role in the relationship between EC and CSR; and is moderated by Age, Academy, and Shares. The conclusion shows that EC can improve CSR performance to optimize CPDI to reduce corporate misplacement behavior.