Investigating the role of smart technologies, financial, and environmental innovations in tackling the ecological sustainability: a global pathway toward low carbon energy transition

Since the beginning of the twenty-first century, the rapid development of modern technologies has brought unprecedented social prosperity to mankind as technologies penetrate every sector of the economy. These technologies have given a new dimension to the energy sector. The key purpose of this study is to investigate the crucial impact of technological revolutions, namely, smart grids, smart devices, financial innovations, and environmental innovations, on greenhouse gas emissions (GHGs). To this end, the study utilized data from European, Asian, Middle Eastern, and African countries and employed first- and second-generation methods, such as DOLS, FMOLS, and CS-ARDL models. The research shows that smart grids are the only factor in reducing GHGs, regardless of geographic division. Hence, linking smart grid resources to climate change goals requires short-term deployment strategies with a clear long-term vision and the fundamental goal of transforming the power structure into a net zero-emission system. The study also demonstrates that the emergence of ICT in electricity consumption has not yet reached a level that can promote environmental excellence. The study documented the critical role of financial innovation and environmental innovation in addressing environmental degradation.

Exploring Non-Toxic Lower Dimensional Perovskites for Next-Generation X-Ray Detectors

Owing to their extraordinary photophysical properties, organometal halide perovskites are emerging as a new material class for X-ray detection. However, the existence of toxic lead makes their commercialization questionable and should readily be replaced. Accordingly, several lead alternatives have been introduced into the framework of conventional perovskites, resulting in various new perovskite dimensionalities. Among these, Pb-free lower dimensional perovskites (LPVKs) not only show promising X-ray detecting properties due to their higher ionic migration energy, wider and tunable energy bandgap, smaller dark currents, and structural versatility but also exhibit extended environmental stability. Herein, first, the structural organization of the PVKs (including LPVKs) is summarized. In the context of X-ray detectors (XDs), the outstanding properties of the LPVKs and active layer synthesis routes are elaborated afterward. Subsequently, their applications in direct XDs are extensively discussed and the device performance, in terms of the synthesis method, device architecture, active layer size, figure of merits, and device stability are tabulated. Finally, the review is concluded with an in-depth outlook, thoroughly exploring the present challenges to LPVKs XDs, proposing innovative solutions, and future directions. This review provides valuable insights into optimizing non-toxic Pb-free perovskite XDs, paving the way for future advancements in the field.

Exploring the impact of public funds and eco-friendly innovations on reducing carbon pollution in North Africa

The main objective of this study is to examine the impacts of green energy and public investment on the CO2 emissions in North Africa. Moreover, the study also tests the existence of the N-shaped Environmental Kuznets Curve (EKC) hypothesis for North African countries between 1995 and 2018. These factors were analyzed using the Dynamic Ordinary Least Squares (DOLS), Fully Modified Ordinary Least Squares (FMOLS), and Pooled Mean Group (PMG) estimators to obtain estimations of heterogeneous parameters. The outcome of these tests and examinations showed that the N-shaped curve was confirmed. Secondly, The results of the study also demonstrate the effectiveness of renewable energy as an eco-friendly innovation in reducing carbon emissions. This finding highlights the positive impact that renewable energy sources can have in terms of emitting fewer carbon emissions compared to traditional energy sources. Moreover, public investment, which interprets government expenditure, and urbanization contribute to environmental degradation by increasing CO2 emissions in the case of North African countries. Furthermore, the findings also indicated a trade-off effect resulting from the correlation between CO2 emissions and economic development. Based on these findings, the study recommends that economic policymakers in North African countries prioritize transforming the structure of government expenditures to improve environmental quality, optimize the utilization of revenues from non-environmentally friendly energy resources to accelerate the energy transition, increase the exploitation of renewable energy, and promote environmental awareness in society. By implementing these recommendations, North African countries can balance economic growth and environmental quality while reducing their carbon footprint.

Extreme flood in Pakistan: Is Pakistan paying the cost of climate change? A short communication

Global warming is one of the foremost causes of changes in climate patterns around the world. Pakistan is among the top ten countries affected by global warming. Today, Pakistan is facing severe consequences of global warming in the form of an extreme flood. It affected 33 million people, destroyed 1.5 million homes, and caused $2.3 billion in crop damage. It has also damaged more than 2000 km of roads, cutting off connectivity to provinces and major cities. Thus, inflation in Pakistan has reached its highest level, i.e. 26 % - 27 %, and a severe food crisis is not far away. Recently, Pakistan noted a record temperature of 40 °C in several territories, notably 51 °C in Jacobabad. The study reported that high temperatures, melting glaciers, heavy monsoon rains, government inattention, and poor governance are the key reasons of this severe flood. Moreover, in 2080, the average temperature in Pakistan is predicted to increase by 4.38 degrees Celsius. The study suggested that Supply of cheap seeds and fertilizers to farmers, maintenance of water supply infrastructure, availability of food and medicines through domestic and foreign assistance, and reduction of electricity rates and taxes in flood-affected areas can be the solution to stop this crisis. Similarly, building dams, investing in technology and training, and educating the general public about environmental change should be included in the long-term goals to avoid future disasters.

Current crowding in graphene-silicon schottky diodes

The performance of the Graphene/Si (Gr/Si) Schottky interface and its potential in future electronics strongly relies on the quality of interconnecting contacts with external circuitry. In this work, we investigate the dominating and limiting factors of Gr/Si interfaces designed for high light absorption, paying particular attention to the nature of the contact failure under high electrostatic discharge (ESD) conditions. Our findings indicate that severe current crowding (CC) at contact edges of the graphene is the dominating factor for the device breakdown. Material degradation and electrical breakdown are systematically analyzed by atomic force, Raman, scanning electron, and energy-dispersive X-ray spectroscopies. This work enlists the robustness and limitations of Gr/Si junction in photodiode architecture under high ESD conditions that can be used as general guidelines for 2D-3D electronic and optoelectronic devices.&#xD.

Ceramic-reinforced HEA matrix composites exhibiting an excellent combination of mechanical properties

CoCrFeNi is a well-studied face centered cubic (fcc) high entropy alloy (HEA) that exhibits excellent ductility but only limited strength. The present study focusses on improving the strength-ductility balance of this HEA by addition of varying amounts of SiC using an arc melting route. Chromium present in the base HEA is found to result in decomposition of SiC during melting. Consequently, interaction of free carbon with chromium results in the in-situ formation of chromium carbide, while free silicon remains in solution in the base HEA and/or interacts with the constituent elements of the base HEA to form silicides. The changes in microstructural phases with increasing amount of SiC are found to follow the sequence: fcc → fcc + eutectic → fcc + chromium carbide platelets → fcc + chromium carbide platelets + silicides → fcc + chromium carbide platelets + silicides + graphite globules/flakes. In comparison to both conventional and high entropy alloys, the resulting composites were found to exhibit a very wide range of mechanical properties (yield strength from 277 MPa with more than 60% elongation to 2522 MPa with 6% elongation). Some of the developed high entropy composites showed an outstanding combination of mechanical properties (yield strength 1200 MPa with 37% elongation) and occupied previously unattainable regions in a yield strength versus elongation map. In addition to their significant elongation, the hardness and yield strength of the HEA composites are found to lie in the same range as those of bulk metallic glasses. It is therefore believed that development of high entropy composites can help in obtaining outstanding combinations of mechanical properties for advanced structural applications.

Ultra-Narrow Linewidth Photo-Emitters in Polymorphic Selenium Nanoflakes

Photoluminescence (PL) in state-of-the-art 2D materials suffers from narrow spectral coverage, relatively broad linewidths, and poor room-temperature (RT) functionality. The authors report ultra-narrow linewidth photo-emitters (ULPs) across the visible to near-infrared wavelength at RT in polymorphic selenium nanoflakes (SeNFs), synthesized via a hot-pressing strategy. Photo-emitters in NIR exhibit full width at half maximum (Γ) of 330 ± 90 µeV, an order of magnitude narrower than the reported ULPs in 2D materials at 300 K, and decrease to 82 ± 70 µeV at 100 K, with coherence time (τ_c ) of 21.3 ps. The capping substrate enforced spatial confinement during thermal expansion at 250 °C is believed to trigger a localized crystal symmetry breaking in SeNFs, causing a polymorphic transition from the semiconducting trigonal (t) to quasi-metallic orthorhombic (orth) phase. Fine structure splitting in orth-Se causes degeneracy in defect-associated bright excitons, resulting in ultra-sharp emission. Combined theoretical and experimental findings, an optimal biaxial compressive strain of -0.45% cm^-1 in t-Se is uncovered, induced by the coefficient of thermal expansion mismatch at the selenium/sapphire interface, resulting in bandgap widening from 1.74 to 2.23 ± 0.1 eV. This report underpins the underlying correlation between crystal symmetry breaking induced polymorphism and RT ULPs in SeNFs, and their phase change characteristics.

Dynamic correlations and portfolio implications across stock and commodity markets before and during the COVID-19 era: A key role of gold

Novel Coronavirus (COVID-19) has affected stock markets around the globe, adding serious challenges to asset allocations and hedging strategies. This investigation analyses the dynamic correlations and portfolio implications among the S&P 500 index and various commodities (gold, WTI crude oil, Brent oil, beverages, and wheat) before and during the COVID-19 era. Using multivariate asymmetric GARCH models, the results show weak correlations during the standard period. However, the correlations intensify and become more complicated during the COVID-19 era, especially between gold and S&P 500. Similarly, bidirectional return and volatility spillovers across stock-commodity markets are more pronounced during the COVID-19 outbreak. Analysis involving the optimal portfolio weights and time-varying hedge ratios indicates that a $1long position in the S&P 500 can be hedged for 15 cents in crude oil during the standard period and for 33 cents in gold during the COVID-19 era. A portfolio of S&P 500 - beverages displays the highest VaR, while a portfolio of S&P 500 - gold displays the lowest VaR, especially during the COVID-19 era. This finding suggests that gold offers better portfolio diversification benefits and downside risk reductions, which are useful in determining strategies for portfolio investors during the COVID-19 outbreak.

Antioxidants Activity Assessment and Utilization of Banana Peels to Attenuate the Diabetes Mellitus

Diabetes is the primary metabolic disorder listed among the top 10 death-causing diseases. The complete cure of diabetes is impossible, but the prevention and maintenance of glucose levels can reduce the diabetes severity. Objectives: To utilize the banana peel extracts to evaluate their antioxidant attributes and capability to attenuate diabetes. Methods: The antioxidant properties were assessed by measuring the DPPH, total phenolic contents (TPC), and total flavonoid contents (TFC) in ethanol, methanol, and acetone solutions. Moreover, the renal functional tests (Serum creatinine, serum urea, and BUN) and liver function tests (ALT, ASP, Serum Albumin, and total proteins) were also conducted during the 21 days experimental study in diabetes-induced (via Streptozotocin: 350 mg/kg) male Albino Wister rats. Results: The results indicated that the DPPH, TPC, and TFC contents were higher in methanol solution, i.e., 74.20±0.98%, 54.78±0.69mg GAE/g, and 39.48±0.37mg GAE/g respectively. Moreover, the results indicated that the unripe, ripe, and overripe significantly reduced liver and renal function parameters in diabetic rats. Conclusions: Banana peels have prominent potential to prevent diabetes-linked variables due to their higher antioxidant activity.

Polymerization kinetics of bicyclic olefins and mechanism with symmetrical ansa-metallocene catalysts associated with active center count: relationship between their activities and structure and activation path

Copolymerization of ethylene (E) with 5-vinyl-2-norbornene (VNB) catalyzed by ansa-metallocenes allows the precise control of essential polymeric properties such as comonomer incorporation, molecular weight (M_w), and polydispersity (Đ). Significant efforts have been devoted to synthesizing and developing novel catalysts, cocatalysts, and activators, although the fundamental elements of catalytic processes remain unclear. For example, it is questionable how polymeric catalysts are divided across dormant and active sites and how this distribution affects the order of monomers for the propagation rate, which widely vary in the literature. Furthermore, although the empirical correlation between the monomers and average M_w has been established in many systems, the fundamental processes of chain termination remain unknown. Furthermore, the involvement of ion-pairing in metallocene-catalyzed polymerization and the termination mechanisms are also contentious issues. In this study, we describe the use of a quenched-labeling technique based on acyl chloride to selectively quench the zirconium metal–polymeric bond, which can be used to study the kinetics, active site [Zr][C*] counting, copolymer microstructure, and molecular weight distribution (MWD) to determine the rate laws for chain initiation, chain propagation rate (R_p), propagation rate constant (k_p) and chain termination. In addition, we also predict previously unknown chemical characteristics of E/bicyclic copolymerization processes, where either a cis-endocyclic double bond with steric properties or a vinyl exocyclic double bond affects the activity, i.e., [Zr]/[*C], (R_p) and (k_p). All these properties require the implementation of a particular kinetic mechanism that assumes the low activity of the building copolymer chains incorporating a single ethylene/VNB unit, i.e., the Cp₂Zr–C₂H₅ group, in the ethylene addition process in the Cp₂Zr–C bond. Due to β-agostic stabilization, the Cp₂Zr–C₂H₅ group exhibits a distinct feature. These effects were confirmed experimentally, such as the E/VNB co-polymer activity and VNB mol%, propagation rate decrease in the polymerization time (t_p) of 120 s to 1800 s, crystalline properties, and significant increase in molecular weight. The active center [Zr]/[*C] fraction considerably increased in the initial (t_p) 840 s, and subsequently tended to the steady stage of 33%, which is lower than previously reported E homo- and E/P copolymerization. The lower [C*]/[Zr] in both the early and stable stages, decrease in VNB mol%, and R_p with t_p can be associated with the more significant fraction of Cp₂Zr–CH₂CH₃-type dormant site by the β-agostic hydrogen interaction with the Cp₂Zr metal. The t_pversus R_pE, R_pVNB, k_pE, k_pVNB, and [Zr]/[C*] count could be fitted to a model that invokes deactivation of the growing polymer chains. In the case of the thermal behavior of the copolymers (melting temperature (T_m) and crystalline temperature (ΔH_m)), T_m varied from 101 °C to 121 °C, while ΔH_m varied from 9 to 16 (J g⁻¹).

Copolymerization of ethylene (E) with 5-vinyl-2-norbornene (VNB) catalyzed by ansa-metallocenes allows the precise control of essential polymeric properties such as comonomer incorporation, molecular weight (M_w), and polydispersity (Đ).

Revisiting the EKC hypothesis by assessing the complementarities between fiscal, monetary, and environmental development policies in China

Recently, China has declared its national objective of becoming carbon neutral by 2060. Hence, mitigating carbon dioxide emissions has become an important agenda of the Chinese government. Against this backdrop, this paper aims to evaluate the effectiveness of pursuing expansionary fiscal and monetary policies on China's carbon dioxide emission figures by using annual frequency data from 1980 to 2018. Accordingly, this study considers the levels of government expenditure and broad money supply as fiscal and monetary policy instruments, respectively. Besides accounting for structural break concerns in the data, the findings from the empirical analysis reveal that there are long-run associations between carbon dioxide emissions, economic growth, and fiscal and monetary expansion in China. Moreover, the results also show that in both the short- and long-run expansionary fiscal policy trigger higher carbon dioxide emissions while expansionary monetary policy inhibits the carbon dioxide emission figures of China. Furthermore, the results invalidate the existence of the Environmental Kuznets Curve hypothesis since the relationship between China's economic growth and carbon dioxide emissions is evidenced to portray an N-shape. In line with these findings, it is recommended that China achieve environmentally sustainable economic growth by aligning the national fiscal and monetary policies with the 2060 carbon-neutrality objective.

Enhancement of lateral Casimir force on a rotating particle near hyperbolic metamaterial

Enhancement of weak Casimir forces is extremely important for their practical detection and subsequent applications in variety of scientific and technological fields. We study the lateral Casimir forces acting on the rotating particles with small radius of 50 nm as well as that with large radius of 500 nm near the hyperbolic metamaterial made of silicon carbide (SiC) nanowires. It is found that the lateral Casimir force acting on the small particle of 50 nm near hyperbolic metamaterial with appropriate filling fraction can be enhanced nearly four times comparing with that acting on the same particle near SiC bulk in the previous study. Such enhancement is caused by the coupling between the resonance mode excited by nanoparticle and the hyperbolic mode supported by hyperbolic metamaterial. The results obtained in this study provide an efficient method to enhance the interaction of nanoscale objects.

2D Heterostructures for Ubiquitous Electronics and Optoelectronics: Principles, Opportunities, and Challenges

A grand family of two-dimensional (2D) materials and their heterostructures have been discovered through the extensive experimental and theoretical efforts of chemists, material scientists, physicists, and technologists. These pioneering works contribute to realizing the fundamental platforms to explore and analyze new physical/chemical properties and technological phenomena at the micro-nano-pico scales. Engineering 2D van der Waals (vdW) materials and their heterostructures via chemical and physical methods with a suitable choice of stacking order, thickness, and interlayer interactions enable exotic carrier dynamics, showing potential in high-frequency electronics, broadband optoelectronics, low-power neuromorphic computing, and ubiquitous electronics. This comprehensive review addresses recent advances in terms of representative 2D materials, the general fabrication methods, and characterization techniques and the vital role of the physical parameters affecting the quality of 2D heterostructures. The main emphasis is on 2D heterostructures and 3D-bulk (3D) hybrid systems exhibiting intrinsic quantum mechanical responses in the optical, valley, and topological states. Finally, we discuss the universality of 2D heterostructures with representative applications and trends for future electronics and optoelectronics (FEO) under the challenges and opportunities from physical, nanotechnological, and material synthesis perspectives.

Is gold favourable than bitcoin during the COVID-19 outbreak? Comparative analysis through wavelet approach

The novel coronavirus (COVID-19) has tremendously oscillated the global financial markets. Consequently, investors feel pressured to find safe-haven investments during the pandemic crisis. Numerous studies have evaluated bitcoin's safe-haven properties during the COVID-19; however, the present study considered gold as a potential safe-haven for investors of renowned stock markets of Asia, Europe, and the US. The present investigation computed the ratio of gold to bitcoin (Gold_Bitcoin) and compared the safe-haven properties of gold in contrast to bitcoin. The present study analysed the Morlet Wavelet approach and found that most of the time during the COVID-19, gold investments proved to be more beneficial than bitcoin. Remarkably, the findings highlighted that the Gold_Bitcoin ratio increased in higher and lower frequencies combined with CAC40. In the long run, the return on investments in gold increased in contrast to bitcoin returns pooled with DAX30. Also, the Gold_Bitcoin ratio of the US stock market increased during the one-week and one-month cycles of January and August. Likewise, the Hang Seng Index caused the Gold_Bitcoin ratio to rise at a much higher frequency (i.e., the second half of January, the first half of February and April, and the first half of June and August), whereas IBEX35 surged Gold_Bitcoin at a lower frequency (i.e., during January, February, and August). In higher frequency bands, LSE increased the Gold_Bitcoin ratio (i.e., in February and March); nevertheless, Gold_Bitcoin showed a positive connection with FTSEMIB in the one-to-two month's frequency band (i.e., throughout January, February, and August). Interestingly, the returns on the Gold_Bitcoin ratio increased in the SSEC stock market in the high-frequency band (i.e., during March, May, and July 2020).

Testing the Environmental Kuznets Curve Hypotheses in Chinese Provinces: A Nexus between Regional Government Expenditures and Environmental Quality

With rapid economic growth, the Chinese government expenditures at various levels have increased adequately. At the same time, the environmental quality in China has deteriorated significantly. In this study, provincial-level data for 31 Chinese provinces during 2007-2017 are used to investigate the impacts of government expenditure on the emissions of three specific measures of environmental degradation. The main objective of this study is to examine the influence of government expenditures, economic growth per capita, environment protection expenditure, and added second-sector value on environmental quality by measuring sulfur dioxide (SO₂), chemical oxygen demand (COD), and ammonia nitrogen emissions (AN). Moreover, the study applied the generalized method of moments (GMM) and the fully modified least square (FMOLS) to estimate the co-integration relationship among the underlying factors. The results demonstrate a significant direct effect of government expenditure on improving environmental quality overall in the Chinese provinces, which increases with the level of economic growth. However, the results also confirmed the inverted N-shaped relationship between the pollution factor and economic growth per capita. Our key findings lead toward the manifestation and emphasis of the importance of appropriate policies for restoring government expenditure and, at the same time, strengthening the relationship between the industrial sector and environmental policy standards. Significantly, governments in developing countries should allocate larger budgets for environmental projects in their fiscal reforms for the sake of moving to greener and more inclusive economies with low-carbon activities.

Modeling the Dynamic Linkage between Tourism Development, Technological Innovation, Urbanization and Environmental Quality: Provincial Data Analysis of China

This study investigates the linkage between tourism development, technological innovation, urbanization and environmental degradation across 30 provinces of China. Based on data from 2001 to 2018, the study used an advanced economic methodology for the long-run estimate, the Augmented Mean Group (AMG) estimator, which accounts for heterogeneity in slope parameters and dependencies across countries. The empirical results show that tourism development degrades environmental quality, while technological innovation mitigates carbon emissions. Further, findings show that urbanization increases carbon emissions, while an inverted U-shaped relationship exists between economic growth and environmental degradation, implying the existence of EKC in China. Further, the Dumitrescu-Hurlin panel causality test shows that any policy aimed at tourism development or technological innovation would substantially contribute to environmental degradation, but not the other way round.

COVID-19 outbreak, lockdown, and air quality: fresh insights from New York City

The outbreak of the COVID-19 pandemic has adversely affected all aspects of life and poses a severe threat to human health and economic development. New York City administration enacted a strict isolation decision at the end of March 2020 to tackle the COVID-19, creating a unique opportunity to assess air quality. Therefore, we investigated the impact of the lockdown on air quality in New York City. We evaluated the air pollutants concentration, i.e., PM2.5, CO, NO2, SO2, and O3, during the lockdown and compared them with pre-COVID-19. We explored the first phase of lockdown through a spatial approach, then formulated the air quality index (AQI) of each pollutant before and during the lockdown. Our findings revealed that (1) there was a significant decline in the concentration level of PM2.5 from 10.3 to 4.0 μg/m3 during phase one of lockdown. (2) NO2 concentrations have been decreased by up to 52% in 1st phase of lockdown. (3) O3 concentration has been increased by 44.4%. (4) Brooklyn, Manhattan, Queens, and Staten Island County encountered 18.75%, 55.62%, 47.14%, and 47% diminution in AQI due to lockdown as compared to 2018, respectively. Our key findings can provide critical environmental implications for policymakers, researchers, academics, and the US government.

Does air pollution upsurge in megacities after Covid-19 lockdown? A spatial approach

The current coronavirus (COVID-19) pandemic has a high spreading and fatality rate. To control the rapid spreading of the COVID-19 virus, the government of India imposed lockdown policies, which creates a unique opportunity to analyze the impact of lockdown on air quality in the two most populous cities of India, i.e., Delhi and Mumbai. To do this, the study employed a spatial approach to examine the concentration of seven criteria pollutants, i.e., PM_2.5, PM₁₀, NH₃, CO, NO₂, O₃, and SO_2, before, during, and after a lockdown in Delhi and Mumbai. Overall, around 42%, 50%, 21%, 37%, 53%, and 41% declines in PM_2.5, PM₁₀, NH₃, CO, NO₂, and SO₂ were observed during the lockdown period as compared to previous years. On the other hand, a 2% increase in O₃ concentration was observed. However, the study analyzed the National Air Quality Index (NAQI) for Delhi and Mumbai and found that lockdown does not improve the air quality in the long term period. Our key findings provide essential information to the cities' administration to develop rules and regulations to enhance air quality.

Does air pollution upsurge in megacities after Covid-19 lockdown? A spatial approach

The current coronavirus (COVID-19) pandemic has a high spreading and fatality rate. To control the rapid spreading of the COVID-19 virus, the government of India imposed lockdown policies, which creates a unique opportunity to analyze the impact of lockdown on air quality in the two most populous cities of India, i.e., Delhi and Mumbai. To do this, the study employed a spatial approach to examine the concentration of seven criteria pollutants, i.e., PM_2.5, PM₁₀, NH₃, CO, NO₂, O₃, and SO_2, before, during, and after a lockdown in Delhi and Mumbai. Overall, around 42%, 50%, 21%, 37%, 53%, and 41% declines in PM_2.5, PM₁₀, NH₃, CO, NO₂, and SO₂ were observed during the lockdown period as compared to previous years. On the other hand, a 2% increase in O₃ concentration was observed. However, the study analyzed the National Air Quality Index (NAQI) for Delhi and Mumbai and found that lockdown does not improve the air quality in the long term period. Our key findings provide essential information to the cities' administration to develop rules and regulations to enhance air quality.

Environmental efficiency of disaggregated energy R&D expenditures in OECD: a bootstrap DEA approach

Two essential topics of Sustainable Development Goals (SDGs) are accessible which are clean energy (SDG-7) and climate change action (SDG-13). Developments and innovations in energy technologies play an essential role in achieving these goals. Therefore, any country should use energy R&D expenditures, which are the primary source of energy innovation, most optimally. This paper aims to investigate the environmental efficiency of R&D expenditures for energy efficiency, renewable energy, hydro and fuel cells, fossil energy, nuclear energy, and other power and storage technologies in OECD countries using data envelopment analysis (DEA) and bootstrap DEA. Estimation findings indicate that only the USA ensures the environmental efficiency in energy R&D expenditures among OECD countries. Although Japan, Canada, France, Germany, and Italy cannot provide environmental efficiency in energy R&D, their scores are very close to the efficiency frontier. Portugal, Hungary, and Slovak Republic are the countries with the lowest environmental efficiency in energy R&D expenditures. At the end of the investigation, this paper also provides an empirical estimation of the extent to which inefficient countries should change their R&D spending to achieve efficiency.

COVID-19 and Spillover Effect of Global Economic Crisis on the United States' Financial Stability

Due to the novel coronavirus pandemic (COVID-19), the lockdown engendered has had a vicious impact on the global economy. This analysis' prime intention is to evaluate the impact of the United States' economic and health crisis as a result of COVID-19 on its financial stability. Additionally, the investigation analyzed the spillover impact of the worldwide economic slowdown experienced by COVID-19 on the United States' financial volatility. The study applied an autoregressive distributed lag (ARDL) model and discovered that the economic and health crises that occurred in the United States portentously upset the future expectations of its investors. Conspicuously, the health crisis in Spain and Italy were ominous spillovers of the United States' financial instability in the short-run. Likewise, an economic crisis ensued in the United Kingdom because of COVID-19 causing spillover for the United States markets' financial instability. The examination evaluated that Asian and African nations' economic crises perilously affects the United States' financial stability. The study determined that financial instability occurred in the United States due to its own economic and health crises persisted for a longer period than financial disequilibrium that occurred in other nations. The analysis suggested some strategies of smart lockdown that the government of the United States and other nations should follow to restart the economic cycle through tighter controls to minimize losses by following the steps of (a) preparing a lockdown checklist, (b) monitoring completion of lockdown tasks, and (c) complete a close-down stock take or count.

INCIDENCE AND CHARACTERISTICS OF CORONARY ARTERY ECTASIA IN PATIENTS UNDERGOING CORONARY ANGIOGRAPHY AT ARMY CARDIAC CENTER LAHORE

Objective: To estimate the incidence and characteristics of coronary artery ectasia in patients undergoing coronary angiography. Study Design: A prospective analysis. Place and Duration of Study: This study was conducted at Army Cardiac Center, Lahore over a period of two years from Jan 2018 to Dec 2019. Methodology: Its prospective analysis of all coronary angiograms performed in our catheterization laboratory during study period. Markis classification was the basis to define and classify coronary artery ectasia. Demographical, clinical, and laboratory data were collected for each patient in this study. Results: A total of 172 (3.9%) out of 4,372 coronary angiograms showed coronary artery ectasia. Among coronary artery ectasia group, mean age 58 ± 10 years, 90% were male, 47% were current smokers, 32% were hypertensive, 15% had diabetes Mellitus and 37% had dyslipidemia. The most common clinical presentation was Non STsegment elevation myocardial infarction (31%), followed by Stable ischemic heart disease in 28%. Right coronary artery was the most frequent coronary artery involved (57%) while Markis Class 3 pattern was seen as most common type of coronary artery ectasia. Conclusion: The frequency of coronary artery ectasia among our patients undergoing coronary angiography was about 4%. Right coronary artery remained the most common affected artery.

The impact of COVID-19 as a necessary evil on air pollution in India during the lockdown

The study objective is to contemplate the effectiveness of COVID-19 on the air pollution of Indian territory from January 2020 to April 2020. We have executed data from European Space Agency (ESA) and CPCB online portal for air quality data dissemination. The Sentinel - 5 P satellite images elucidate that the Air quality of Indian territory has been improved significantly during COVID-19. Mumbai and Delhi are one of the most populated cities. These two cities have observed a substantial decrease in Nitrogen Dioxide (40-50%) compared to the same period last year. It suggests that the emergence of COVID-19 has been proved to a necessary evil as being advantageous for mitigating air pollution on Indian territory during the lock-down. The study found a significant decline in Nitrogen Dioxide in reputed states of India, i.e., Delhi and Mumbai. Moreover, a faded track of Nitrogen Dioxide can be seen at the Maritime route in the Indian Ocean. An upsurge in the environmental quality of India will also be beneficial for its neighbor countries, i.e., China, Pakistan, Iran, and Afghanistan.

How Investors Attitudes Shape Stock Market Participation in the Presence of Financial Self-Efficacy

The purpose of this study is to investigate how investor’s money attitudes shape their stock market participation (SMP) decisions. This study followed the theory of planned behavior (TPB), and a survey was conducted to collect the responses from active investors. Structural equation modeling (SEM) was used for the analysis of proposed relationships among the constructs, and a confirmatory factor analysis (CFA) was conducted to check the interrelation of the variables and validity of the constructs. This research has concluded that investor’s money attitudes are significant to affect their stock market participation decisions. Further, it was found that risk attitudes partially mediate the relationship between money attitudes and stock market participation. Moreover, financial knowledge and financial self-efficacy positively moderated the relationship between money attitudes and stock market participation. This research is one of the early attempts at studying the money attitudes of investors and introduces financial self-efficacy as a moderating construct between money attitudes and stock market participation. The sample size for this study was 250 respondents which can be increased in future research, and the same relationships can be tested by using a larger sample. Moreover, this study has used money attitudes as predictors of stock market participation. Still, many other variables, like personal value, can also be taken to investigate their influence on stock market participation.

COVID-19's disasters are perilous than Global Financial Crisis: A rumor or fact?

This investigation employed the Asymmetric Power GARCH model and found that COVID-19 substantially harms the US and Japan's market returns. Moreover, COVID-19 has influenced the variance of the US, Germany, and Italy's stock markets more than the Global Financial Crises (GFC). However, GFC indicated a more significant impact on the financial volatility of the Nikkei 225 index and SSEC than COVID-19. The study confirmed the leverage effect for the S&P 500, Nasdaq Composite Index, DAX 30, Nikkei 225, FTSE MIB, and SSEC. The analysis authenticated that the health crisis that befell due to COVID-19 have imperatively originated the financial crisis globally; however, the Asian markets still make available better prospects for portfolio optimization.

Investigating the Psychology of Financial Markets During COVID-19 Era: A Case Study of the US and European Markets

The novel coronavirus (COVID-19) has imperatively shaken the behavior of the global financial markets. This study estimated the impact of COVID-19 on the behavior of the financial markets of Europe and the US. The results revealed that the returns of the S&P 500 index have been greatly affected by a lockdown in the US owing to COVID-19. However, the health crisis generated due to the novel coronavirus significantly decreased the stock returns of the Nasdaq Composite index. The results also showed that the economic crisis generated from the pandemic in Spain has had more impact on the IBEX 35 as compared to the health crisis itself. On the other hand, in the long-run, Italy’s stock markets are more affected by the health crisis as contrasted with the economic crisis, while, in the short-run, both lockdown conditions and economic instability lower the stock returns of FTSE MIB. The UK stock markets witnessed that in the short-run, deficiency of health management systems imperatively damaged the stock returns of the London Stock Exchange. The investigation revealed that deficiency of health systems and lockdown conditions have imperatively damaged the structure of financial markets, inferring that sustainable development of these nations is at risk due to COVID-19. The study suggested that governments should allocate more of their budget to the health sector to overcome a health crisis in the future.

Room-temperature valleytronic transistor

Valleytronics, based on the valley degree of freedom rather than charge, is a promising candidate for next-generation information devices beyond complementary metal-oxide-semiconductor (CMOS) technology^1-4. Although many intriguing valleytronic properties have been explored based on excitonic injection or the non-local response of transverse current schemes at low temperature^4-7, demonstrations of valleytronic building blocks similar to transistors in electronics, especially at room temperature, remain elusive. Here, we report a solid-state device that enables a full sequence of generating, propagating, detecting and manipulating valley information at room temperature. Chiral nanocrescent plasmonic antennae⁸ are used to selectively generate valley-polarized carriers in MoS₂ through hot-electron injection under linearly polarized infrared excitation. These long-lived valley-polarized free carriers can be detected in a valley Hall configuration^9-11 even without charge current, and can propagate over 18 μm by means of drift. In addition, electrostatic gating allows us to modulate the magnitude of the valley Hall voltage. The electrical valley Hall output could drive the valley manipulation of a cascaded stage, rendering the device able to serve as a transistor free of charge current with pure valleytronic input/output. Our results demonstrate the possibility of encoding and processing information by valley degree of freedom, and provide a universal strategy to study the Berry curvature dipole in quantum materials.

Signifying the imperative nexus between climate change and information and communication technology development: a case from Pakistan

The globe has faced technological affluence that enormously revolutionized the lives of humankind. Today, the manufacturing process of the energy sector, production sector, agriculture sector, and service sector is exclusively or partially based on ICT tools. The key intention of this investigation is to find out the impacts of the utilization of ICT on CO₂ emission. However, this investigation also evaluates the influence of investment in ICT and the trade of ICT tools on CO₂ emission. Further, the estimation examined the subsistence of environment Kuznets curve (EKC) theory, for the nation of Pakistan. The investigation employed an autoregressive distributed lag (ARDL) model and found that the utilization of ICT has a negative impact on CO₂ emission. Moreover, the long-run results revealed that the import of ICT equipment is more beneficial for the environment quality of Pakistan. However, ICT apparatus manufactured in Pakistan might produce electronic waste due to non-utilization of green technology. The study reported bidirectional causality between ICT and CO₂ emission. These results point towards that the emergence of ICT in industries and daily life possesses a significant and positive role in climate change in Pakistan. Also, this study corroborates the veracity of EKC in Pakistan.

Graphene Hybrid Structures for Integrated and Flexible Optoelectronics

Graphene (Gr) has many unique properties including gapless band structure, ultrafast carrier dynamics, high carrier mobility, and flexibility, making it appealing for ultrafast, broadband, and flexible optoelectronics. To overcome its intrinsic limit of low absorption, hybrid structures are exploited to improve the device performance. Particularly, van der Waals heterostructures with different photosensitive materials and photonic structures are very effective for improving photodetection and modulation efficiency. With such hybrid structures, Gr hybrid photodetectors can operate from ultraviolet to terahertz, with significantly improved R (up to 10⁹ A W^-1 ) and bandwidth (up to 128 GHz). Furthermore, integration of Gr with silicon (Si) complementary metal-oxide-semiconductor (CMOS) circuits, the human body, and soft tissues is successfully demonstrated, opening promising opportunities for wearable sensors and biomedical electronics. Here, the recent progress in using Gr hybrid structures toward high-performance photodetectors and integrated optoelectronic applications is reviewed.

Gauging the air quality of New York: a non-linear Nexus between COVID-19 and nitrogen dioxide emission

The primary objective of the study is to analyse the relationship between COVID-19 and nitrogen dioxide in New York City during the global pandemic. Notably, the study has investigated the direct influence of lockdown circumstances (due to COVID-19) and plunge in the population of New York on its environmental contamination. The study utilized the Non-Linear Autoregressive Distributed Lag (NARDL) model to ascertain the asymmetric impact of COVID-19 on the environmental quality of the USA. The results reveal that lockdown has played a significant role in the environmental quality of the USA. Notably, an escalation in the registered cases of COVID-19 has a meaningful and indirect relationship with environmental pollution in the UAS. Besides, as the lockdown state goes normal, it results in an explosion in the environmental pollution in the USA. Also, deaths due to COVID-19 substantively improve the environmental quality in the short-term period as well as in the long-term period.

Approaching the Collection Limit in Hot Electron Transistors with Ambipolar Hot Carrier Transport

Hot electron transistors (HETs) containing two-dimensional (2D) materials promise great potential in high-frequency analog and digital applications. Here, we experimentally demonstrate all-2D van der Waals (vdW) HETs formed by graphene, hBN, and WSe₂, in which the polarity of carriers could be tuned by changing bias conditions. We proposed a theoretical model to distinguish hot hole and hot electron components in the ambipolar vdW HET. Importantly, both hot hole and hot electron modes are achieved with pronounced saturation behavior as well as record-high collection efficiency approaching theoretical limits (99.9%) at room temperature. The vdW HETs show a maximum output current density of 400 A/cm². The observed ambipolar hot carrier transport with high collection efficiency is promising for high-speed nanoelectronics and 2D hot electron spectroscopy.

Identification and validation of potential reference gene for effective dsRNA knockdown analysis in Chilo partellus

Chilo partellus is an invasive polyphagous pest that has not been effectively managed with chemical pesticides. To select potential dsRNAs for use in an alternate control strategy, it is crucial to identify and evaluate stable reference genes for knockdown expression studies. This study evaluates the expression stability of seven candidate reference genes in C. partellus larvae fed on crude bacterially-expressed dsRNAs and purified dsRNAs at different time intervals, as well as the developmental stages and sexes. The expression stabilities of the reference genes were evaluated with different software programmes, such as BestKeeper, NormFinder, deltaCt, geNorm, and RefFinder. The overall results rank ELF as the most stably expressed reference gene when larvae were fed with crude bacteria-induced dsRNAs and purified dsRNA. However, Tubulin and HSP70 were more stable under different developmental stages and sexes. The expression levels of larvae that were fed crude bacteria-induced dsRNAs of Chitinase and Acetylcholinesterase were normalized with the four most stable reference genes (ELF, HSP70, V-ATPase and Tubulin) and the least stable reference gene (18S and HSP70) based on the geNorm algorithm. The least stable reference gene showed inconsistent knockdown expression, thereby confirming that the validation of a suitable reference gene is crucial to improve assay accuracy for dsRNA-targeted gene selection in C. partellus.

Mesoporous zirconia nanostructures (MZN) for adsorption of As(III) and As(V) from aqueous solutions

Mesoporous zirconia nanostructures (MZN) were synthesized by hydrothermal method to efficiently remove highly mobile and toxic arsenite (As(III)) and arsenate (As(V)) from aqueous solutions. The as-synthesized MZN were characterized by Brunauer-Emmett-Teller (BET), X-Ray diffraction (XRD), scanning electron microscopy (SEM), high resolution transmission electron microscope (HRTEM), and Energy-dispersive X-ray spectroscopy (EDX) techniques. The batch adsorption experimental results showed that the As(III) and As(V) removal capacities of the MZN were 105.03 and 110.29 mg/g, respectively, under neutral pH conditions, which were better than many recently reported adsorbents. The adsorption behavior of As(III) and As(V) on the MZN could be well described by pseudo-second-order and Langmuir isotherms models. Moreover, As(III) and As(V) adsorption on the MZN was spontaneous and endothermic. Some of the common co-existing ions had slightly affected the arsenic removal proficiency of MZN. Fourier transform infrared (FTIR) spectroscopy and X-ray photoelectron spectroscopy (XPS) were used to investigate the adsorption mechanism of As(III) and As(V) on the as-synthesized MZN. The as-synthesized MZN demonstrated quite fast and good treatment of simulated real arsenic (As(III,V)) contaminated water. This study suggested that the as-synthesized MZN are potential candidate for practical applications of As(III) and As(V) removal from the aqueous solutions.

Synthesis of ultra-large ZrO2 nanosheets as novel adsorbents for fast and efficient removal of As(III) from aqueous solutions

Consumption of water having excessive arsenic (As) contamination can cause adverse health effects on human beings. In this study, novel ultra-large zirconium oxide (ZrO₂) nanosheets were successfully synthesized using graphene oxide (GO) templates and their adsorption-ability was studied for arsenite (As(III)). Owing to higher values of surface area, numbers of available hydroxyl groups and strong chemisorption binding affinity towards As(III), the synthesized novel ultra-large ZrO₂ nanosheets showed high adsorption-ability for As(III) over a wide pH range. Experimental results demonstrated that the maximum adsorption-ability of the ZrO₂ nanosheets for As(III) reached to 74.9 mg/g at pH 6. BET, zeta potential, effect of initial pH, FTIR and XPS have been used to analyze the As(III) adsorption process on the ZrO₂ nanosheets. The experiments for effects of co-existing ions indicated that ZrO₂ nanosheets possessed good anti-interference ability towards co-existing ions. Furthermore, the ZrO₂ nanosheets demonstrated very fast and excellent treatment of simulated real As(III) polluted water, consequently the effluent concentration met the standard regulated by World Health Organization. This study suggested that the as-prepared ZrO₂ nanosheets could be potentially applied in practical drinking water treatment.

Porous SnO2 nanoparticles based ion chromatographic determination of non-fluorescent antibiotic (chloramphenicol) in complex samples

Nowadays, there are rising concerns about the extensive use of the antibiotics such as chloramphenicol (CAP), has threatened the human life in the form of various vicious diseases. The limited selectivity and sensitivity of confirmatory techniques (UV and electrochemical) and non-fluorescence property of CAP make its determination a challenging task in the modern pharmaceutical analysis. In order to redeem the selective, sensitive and cost-effective fluorescence methodology, here by the dual role of synthesized porous SnO2 nanoparticles were exploited; (i) a porous sorbent in a µ-QuEChERS based sample preparation and as (ii) a stimulant for the transformation of non-fluorescent analytes namely CAP and p-nitrophenol (p-NP) into their respective fluorescent product. We report a green, simple, selective and cost effective ion chromatographic method for CAP sensitive determination in three complex matrices including milk, human urine and serum. The synthesized sorbent not only selectively adsorbed and degraded the matrix/interferences but also selectively reduced the non-fluorescent antibiotic CAP into a fluorescent species. This developed ion chromatographic method exhibited good selectivity, linearity (r2 ≥ 0.996) and limit of detection (LOD) was in the range 0.0201-0.0280 µg/kg. The inter- and intraday precisions were also satisfactory having a relative standard deviation (RSDs) less than 14.96% and excellent recoveries of CAP in the range of 78.3-100.2% were retrieved in various complex samples.

Synthesis of antibacterial poly(o-chloroaniline)/chromium hybrid composites with enhanced electrical conductivity

Electrically conductive polyorthochloroaniline/chromium nanocomposites (POC/Cr NCs) were prepared by in situ chemical oxidative polymerization of orthochloroaniline in the presence of Cr nanoparticles (Cr NPs). The load percentage of Cr nanofiller was varied in POC matrix to investigate the effect of Cr nanoparticles on the properties of the nanocomposites. The composition, structure, and morphology of POC and its composites were examined by Scanning electron microscopy, Fourier transform infrared spectroscopy, and UV–visible spectroscopic analysis. The antibacterial potential of POC and its composites was evaluated by the disc diffusion method against Escherichia coli and Bacillus subtilis. The results showed the improved antibacterial potential with the increase in the load percentage of nanofiller. The electrical conductivity of polymer and its composites was measured and correlated with the load percentage. The results showed that electrical conductivity of the composites was enhanced with the increase in load percentage of Cr nanoparticles.

Black phosphorus ink formulation for inkjet printing of optoelectronics and photonics

Black phosphorus is a two-dimensional material of great interest, in part because of its high carrier mobility and thickness dependent direct bandgap. However, its instability under ambient conditions limits material deposition options for device fabrication. Here we show a black phosphorus ink that can be reliably inkjet printed, enabling scalable development of optoelectronic and photonic devices. Our binder-free ink suppresses coffee ring formation through induced recirculating Marangoni flow, and supports excellent consistency (< 2% variation) and spatial uniformity (< 3.4% variation), without substrate pre-treatment. Due to rapid ink drying (< 10 s at < 60 °C), printing causes minimal oxidation. Following encapsulation, the printed black phosphorus is stable against long-term (> 30 days) oxidation. We demonstrate printed black phosphorus as a passive switch for ultrafast lasers, stable against intense irradiation, and as a visible to near-infrared photodetector with high responsivities. Our work highlights the promise of this material as a functional ink platform for printed devices.Atomically thin black phosphorus shows promise for optoelectronics and photonics, yet its instability under environmental conditions and the lack of well-established large-area synthesis protocols hinder its applications. Here, the authors demonstrate a stable black phosphorus ink suitable for printed ultrafast lasers and photodetectors.

A Broadband Fluorographene Photodetector

High-performance photodetectors operating over a broad wavelength range from ultraviolet, visible, to infrared are of scientific and technological importance for a wide range of applications. Here, a photodetector based on van der Waals heterostructures of graphene and its fluorine-functionalized derivative is presented. It consistently shows broadband photoresponse from the ultraviolet (255 nm) to the mid-infrared (4.3 µm) wavelengths, with three orders of magnitude enhanced responsivity compared to pristine graphene photodetectors. The broadband photodetection is attributed to the synergistic effects of the spatial nonuniform collective quantum confinement of sp² domains, and the trapping of photoexcited charge carriers in the localized states in sp³ domains. Tunable photoresponse is achieved by controlling the nature of sp³ sites and the size and fraction of sp³ /sp² domains. In addition, the photoresponse due to the different photoexcited-charge-carrier trapping times in sp² and sp³ nanodomains is determined. The proposed scheme paves the way toward implementing high-performance broadband graphene-based photodetectors.

Facile Synthesis of γ-In2 Se3 Nanoflowers toward High Performance Self-Powered Broadband γ-In2 Se3 /Si Heterojunction Photodiode

An effective colloidal process involving the hot-injection method is developed to synthesize uniform nanoflowers consisting of 2D γ-In₂ Se₃ nanosheets. By exploiting the narrow direct bandgap and high absorption coefficient in the visible light range of In₂ Se₃ , a high-quality γ-In₂ Se₃ /Si heterojunction photodiode is fabricated. This photodiode shows a high photoresponse under light illumination, short response/recovery times, and long-term durability. In addition, the γ-In₂ Se₃ /Si heterojunction photodiode is self-powered and displays a broadband spectral response ranging from UV to IR with a high responsivity and detectivity. These excellent performances make the γ-In₂ Se₃ /Si heterojunction very interesting as highly efficient photodetectors.

Flexible Dielectric Nanocomposites with Ultrawide Zero-Temperature Coefficient Windows for Electrical Energy Storage and Conversion under Extreme Conditions

Polymer dielectrics offer key advantages over their ceramic counterparts such as flexibility, scalability, low cost, and high breakdown voltages. However, a major drawback that limits more widespread application of polymer dielectrics is their temperature-dependent dielectric properties. Achieving dielectric constants with low/zero-temperature coefficient (L/0TC) over a broad temperature range is essential for applications in diverse technologies. Here, we report a hybrid filler strategy to produce polymer composites with an ultrawide L/0TC window of dielectric constant, as well as a significantly enhanced dielectric value, maximum energy storage density, thermal conductivity, and stability. By creating a series of percolative polymer composites, we demonstrated hybrid carbon filler based composites can exhibit a zero-temperature coefficient window of 200 °C (from -50 to 150 °C), the widest 0TC window for all polymer composite dielectrics reported to date. We further show the electric and dielectric temperature coefficient of the composites is highly stable against stretching and bending, even under AC electric field with frequency up to 1 MHz. We envision that our method will push the functional limits of polymer dielectrics for flexible electronics in extreme conditions such as in hybrid vehicles, aerospace, power electronics, and oil/gas exploration.

Large, Linear, and Tunable Positive Magnetoresistance of Mechanically Stable Graphene Foam-Toward High-Performance Magnetic Field Sensors

Here, we present the first observation of magneto-transport properties of graphene foam (GF) composed of a few layers in a wide temperature range of 2-300 K. Large room-temperature linear positive magnetoresistance (PMR ≈ 171% at B ≈ 9 T) has been detected. The largest PMR (∼213%) has been achieved at 2 K under a magnetic field of 9 T, which can be tuned by the addition of poly(methyl methacrylate) to the porous structure of the foam. This remarkable magnetoresistance may be the result of quadratic magnetoresistance. The excellent magneto-transport properties of GF open a way toward three-dimensional graphene-based magnetoelectronic devices.

Flexible, Low Cost, and Platinum-Free Counter Electrode for Efficient Dye-Sensitized Solar Cells

A platinum-free counter electrode composed of surface modified aligned multiwalled carbon nanotubes (MWCNTs) fibers was fabricated for efficient flexible dye-sensitized solar cells (DSSCs). Surface modification of MWCNTs fibers with simple one step hydrothermal deposition of cobalt selenide nanoparticles, confirmed by scanning electron microscopy and X-ray diffraction, provided a significant improvement (∼2-times) in their electrocatalytic activity. Cyclic voltammetry and electrochemical impedance spectroscopy suggest a photoelectric conversion efficiency of 6.42% for our modified fibers, higher than 3.4% and 5.6% efficeincy of pristine MWCNTs fiber and commonly used Pt wire, respectively. Good mechanical and performance stability after repeated bending and high output voltage for in-series connection suggest that our surface modified MWCNTs fiber based DSSCs may find applications as flexible power source in next-generation flexible/wearable electronics.

Three-dimensional macro-structures of two-dimensional nanomaterials

This review summarizes the recent progress and efforts in the synthesis, structure, properties, and applications of three-dimensional macro-structures of two-dimensional nanomaterials.