Rate Of Exchange Research Articles

2-Pyridone-Enhanced Mn-Catalysis for the Synthesis of ortho-Deuterated Aromatic Nitriles.

We herein present a method for the synthesis of ortho-deuterated aryl nitrile using Mn(CO)5Br as catalyst with CH3OD as deuteratium source, where the structure of aryl imidates is used for interconversion with a cyanide group. This method features a broad substrate range and excellent functional group tolerance, allowing late modification of various complex molecules with good yields and deuterium incorporation. Mechanistic studies suggest that 2-pyridone is crucial to the success of this chemistry, serving as an endogenous base that enhances the rate of hydrogen isotope exchange.

Thermal performance enhancement of laminar flow using compound twisted square duct and variable pitch twisted tape inserts

This study involves a computational analysis to find the effectiveness of incorporating twisted tape within a twisted square duct for improving heat transfer, focusing on laminar single-phase flow. The primary goal is to study how varying the tape pitch (y) influences the hydrothermal performance of this system. The twisted square duct pitch (S) and twist ratio (H) were kept constant. The numerical analysis is performed under conditions of uniform wall temperature, and varying the pitch ratio (y/S) across values of 0.25, 0.5,0.75, 1, 1.25, 1.5 and 1.75. The obtained findings suggest that the addition of twisted tape within the twisted square duct results in a greater rate of heat exchange and pressure drop relative to the simple twisted square duct. Research reveals that despite a higher rate of heat transfer for a pitch ratio of 0.25 the increased friction factor results in less effective thermal performance compared to the cases with pitch ratios of 0.75 and 0.5. The thermal performance factor reaches its peak at 1.32, corresponding to the Reynolds number 1000 for a pitch ratio of 0.75 case. Conversely, the lowest thermal performance factor value of 0.89 is observed at the Reynolds number 500 for pitch ratio 1.25 case.

An economic study to evaluate the rates of trade exchange between Egypt and the COMESA countries In light of recent economic changes

An economic study to evaluate the rates of trade exchange between Egypt and the COMESA countries In light of recent economic changes

Artificial intelligence assisted prediction of optimum operating conditions of shell and tube heat exchangers: A grey‐box approach

AbstractIn this study, a Grey‐box (GB) model was developed to predict the optimum mass flow rates of inlet streams of a Shell and Tube Heat Exchanger (STHE) under varying process conditions. Aspen Exchanger Design and Rating (Aspen‐EDR) was initially used to construct a first principle model (FP) of the STHE using industrial data. The Genetic Algorithm (GA) was incorporated into the FP model to attain the minimum exit temperature for the hot kerosene process stream under varying process conditions. A dataset comprised of optimum process conditions was generated through FP‐GA integration and was utilised to develop an Artificial Neural Networks (ANN) model. Subsequently, the ANN model was merged with the FP model by substituting the GA, to form a GB model. The developed GB model, that is, ANN and FP integration, achieved higher effectiveness and lower outlet temperature than those derived through the standalone FP model. Performance of the GB framework was also comparable to the FP‐GA approach but it significantly reduced the computation time required for estimating the optimum process conditions. The proposed GB‐based method improved the STHE's ability to extract energy from the process stream and strengthened its resilience to cope with diverse process conditions.

High Fluorescence of Phytochromes Does Not Require Chromophore Protonation

Fluorescing proteins emitting in the near-infrared region are of high importance in various fields of biomedicine and applied life sciences. Promising candidates are phytochromes that can be engineered to a small size and genetically attached to a target system for in vivo monitoring. Here, we have investigated two of these minimal single-domain phytochromes, miRFP670nano3 and miRFP718nano, aiming at a better understanding of the structural parameters that control the fluorescence properties of the covalently bound biliverdin (BV) chromophore. On the basis of resonance Raman and time-resolved fluorescence spectroscopy, it is shown that in both proteins, BV is deprotonated at one of the inner pyrrole rings (B or C). This protonation pattern, which is unusual for tetrapyrroles in proteins, implies an equilibrium between a B- and C-protonated tautomer. The dynamics of the equilibrium are slow compared to the fluorescence lifetime in miRFP670nano3 but much faster in miRFP718nano, both in the ground and excited states. The different rates of proton exchange are most likely due to the different structural dynamics of the more rigid and more flexible chromophore in miRFP670nano3 and miRFP718nano, respectively. We suggest that these structural properties account for the quite different fluorescent quantum yields of both proteins.

Wind speed affects the rate and kinetics of stomatal conductance.

Understanding the relationship between wind speed and gas exchange in plants is a longstanding challenge. Our aim was to investigate the impact of wind speed on maximum rates of gas exchange and the kinetics of stomatal responses. We conducted experiments in different angiosperm and fern species using an infrared gas analyzer equipped with a controlled leaf fan, enabling precise control of the boundary layer conductance. We first showed that the chamber was adequately mixed even at extremely low wind speed (<0.005 m s-1) and evaluated the link between fan speed, wind speed, and boundary layer conductance. We observed that higher wind speeds led to increased gas exchange of both water vapor and CO₂, primarily due to the increase in boundary layer conductance. This increase in transpiration subsequently reduced epidermal pressure, leading to stomatal opening. We documented that stomatal opening in response to light was 2.5 times faster at a wind speed of 2 m s-1 compared to minimal wind speed in Vicia faba, while epidermal peels in a buffer with no transpiration exhibited a similar opening rate. The increase in stomatal conductance under high wind was also observed in four angiosperm species under field conditions, but it was not observed in Boston fern (Nephrolepis exaltata), which lacks epidermal mechanical advantage. Our findings highlight the significant impact of boundary layer conductance on determining gas exchange rates and the kinetics of gas exchange responses to environmental changes.

Novel energy exchange behaviors and mechanisms in nonlinear acoustic metamaterials with multiple nonlinear resonators

Wave-wave interactions in a nonlinear metamaterial or structure with two propagating waves can induce energy exchange within the nonlinear systems. The effects of nonlinear resonators on these interactions and energy exchanges in a nonlinear acoustic metamaterial have not been extensively studied in the literature. In this paper, a nonlinear monatomic acoustic metamaterial with multiple nonlinear resonators (NMAM-MNR) is constructed to investigate the new behaviors and mechanisms introduced by these nonlinear resonators. Stability analyses reveal that stability can be tuned by adjusting the number of nonlinear resonators and by selecting different intensities or masses of the resonators and the chain. Additionally, direct numerical simulations are performed to study the novel energy exchange behaviors and mechanisms in NMAM-MNR systems. The results demonstrate that the degree and frequency of energy exchange can be tuned by altering the mass ratios, stiffness ratios, intensities, and natural frequencies of the nonlinear resonators and the chain. The influence of mass and stiffness ratios on the time taken for the B-wave magnitude to first reach its maximum value in NMAM-MNR systems is also studied, showing that the rate of energy exchange induced by wave-wave interactions can be tuned by changing the stiffness and mass ratios of multiple nonlinear resonators. These properties have potential applications in the fields of energy harvesters, waveguides, and resonant energy transfer mechanisms.

16O2 – 18O2 interface exchange study between gas phase and the BaFeO3–δ oxide

Studies of oxygen surface exchange kinetics for BaFeO3–δ oxide were performed using the oxygen isotope exchange method with pulsed supply of an isotopically enriched mixture (PIE) at the partial oxygen pressure 21.3 kPa in the temperature range of 350–600 °С. Oxygen surface exchange kinetics was considered in the framework of two-step model including two consecutive steps: dissociative adsorption of oxygen and incorporation of oxygen adatoms into the crystal lattice of the oxide. The rates of oxygen heterogeneous exchange (rH), as well as the rates of dissociative adsorption (ra) and oxygen incorporation (ri), have been calculated. The process of oxygen dissociative adsorption at the surface of BaFeO3–δ oxide was found to be the rate-determining step of the surface exchange. The appropriate models describing the oxygen exchange kinetics and possible mechanisms occurring in the system “gaseous oxygen – BaFeO3–δ oxide” were discussed.

The Determinants of Industrial Output in Pakistan: A Time Series Analysis

This study investigates the determinants of industrial growth in Pakistan through an empirical analysis of quarterly data spanning from 1970 to 2022. Industrial growth is the dependent variable, while the inflation rate, rate of exchange, foreign direct investment, gross fixed capital formation, and terms of trade are independent variables. The Autoregressive Distributed Lag (ARDL) model was employed due to the mixed stationarity, as indicated by the augmented dickey-fuller test. The results reveal a positive long-run relationship between FDI and industrial growth, as well as between gross fixed capital formation and industrial growth. Conversely, a negative relationship is observed between the exchange rate and industrial growth, and between the interest rate and industrial growth. All variables to be statistically significant, except for terms of trade. Furthermore, the inflation rate and rate of exchange show a reducing impact on industrial growth, while FDI and gross fixed capital formation contribute positively to industrial growth.

An Econometric Evaluation of the Variation effect of the Nigerian Rate of Exchange on the Economic Progression

This research work investigated an econometric evaluation of the variation effect of the Nigerian rate of exchange on the economic progression between the years 1986-2017. A secondary source of data was employed in this work, which was extracted from the National Bureau Statistical Bulletin published by the Central Bank of Nigeria. Maximum Likelihood estimation of the R-software was carried out to evaluate the parameter estimate of the multiple regression coefficients and analyzed the influence of the explanatory variables (Gross Domestic Product, Unemployment and Inflation on the rate of Exchange). It was observed that the Gross Domestic Product and Unemployment rate influenced negatively on the Exchange rate but significant with (β = -1.646, t = -2.409, sig.val = 0.0228) and (β = - 0.8602, t = -3.302, sig.val = 0.00263) respectively. Nevertheless Inflation rate had positive influence on the rate of Exchange but not significant with (β = 1.311, t = 0.852, sig.val = 0.40122). The Coefficient of determination (R2 = 82.7) implies that the variation of the Nigerian rate of exchange has significant effect on the economic progression between the years 1986-2017. However, the paper recommends the following; a control of the sequential rising of inflation so as to have a stabilized rate of exchange and a promising economy for the citizens, adequate security, effective fiscal and monetary policies, as well as the provision of infrastructural facilities so that foreign investors will be attracted to invest in Nigeria.

The exchange dynamics of biomolecular condensates.

A hallmark of biomolecular condensates formed via liquid-liquid phase separation is that they dynamically exchange material with their surroundings, and this process can be crucial to condensate function. Intuitively, the rate of exchange can be limited by the flux from the dilute phase or by the mixing speed in the dense phase. Surprisingly, a recent experiment suggests that exchange can also be limited by the dynamics at the droplet interface, implying the existence of an 'interface resistance'. Here, we first derive an analytical expression for the timescale of condensate material exchange, which clearly conveys the physical factors controlling exchange dynamics. We then utilize sticker-spacer polymer models to show that interface resistance can arise when incident molecules transiently touch the interface without entering the dense phase, i.e., the molecules 'bounce' from the interface. Our work provides insight into condensate exchange dynamics, with implications for both natural and synthetic systems.

The exchange dynamics of biomolecular condensates

A hallmark of biomolecular condensates formed via liquid-liquid phase separation is that they dynamically exchange material with their surroundings, and this process can be crucial to condensate function. Intuitively, the rate of exchange can be limited by the flux from the dilute phase or by the mixing speed in the dense phase. Surprisingly, a recent experiment suggests that exchange can also be limited by the dynamics at the droplet interface, implying the existence of an ‘interface resistance’. Here, we first derive an analytical expression for the timescale of condensate material exchange, which clearly conveys the physical factors controlling exchange dynamics. We then utilize sticker-spacer polymer models to show that interface resistance can arise when incident molecules transiently touch the interface without entering the dense phase, i.e., the molecules ‘bounce’ from the interface. Our work provides insight into condensate exchange dynamics, with implications for both natural and synthetic systems.

Using First Eye Early Vault to Determine ICL Size for the Second Eye: A Retrospective Analysis of Bilateral Phakic Intraocular Lens Implantation.

To evaluate the role of the first eye vault after the implantation of implantable collamer lens (ICL) V4c in selecting ICL size for the second eye and analyze the changing characteristics of the vault. Qingdao Eye Hospital of Shandong First Medical University. Retrospective case series. In this retrospective study, 509 patients (1018 eyes) receiving bilateral ICL V4c implants were evaluated. Surgical management method was as follows: the vault was measured at 2 hours after the first eye surgery, and we selected ICL size for the second eye based on the vault of the first eye. The bilateral vault was measured and evaluated between different periods of follow-up. The rate of ICL re-alignment or exchange due to abnormal vault was 1.47% (15/1018), with the second eye showing a significantly lower incidence (0.39%) compared to the first eye (2.55%)(P<0.01). Patients were categorized into four groups based on the vault value obtained at 2 hours postoperatively (baseline). There was significant difference in the value of vault decrease among the four groups at 1day, 1week, 1month, and 3months follow-up(all P<0.01). There was a significant positive correlation between the decrease in the vault and the baseline vault(all P < 0.01). Selecting the ICL size for the second eye based on the first eye's vault measurement 2 hours postoperatively can effectively minimize the need for further surgeries. Notably, eyes with a higher initial vault experienced a more pronounced decrease.

Institutional approach for ecotourism collaboration between South Korea and Japan: exploration of criteria for ecotourism joint-certification

ABSTRACT Domestic and international tourism, which was limited due to the pandemic, has exploded since 2023, with neighboring South Korea and Japan experiencing a high rate of mutual tourism exchanges. Ecotourism, which is differentiated from mass tourism, is receiving renewed attention. This study proposes a joint-certification standard that ensures high satisfaction and a desirable ecotourism foundation. Through stakeholder engagement and field research in representative areas, 19 certification criteria across 7 categories were developed, emphasizing resource conservation, tourist management, and community involvement. During this process, both nations proposed joint support measures for promotion and explanation and the creation of platforms for sharing expertise between regions. Importantly, the introduction of ecotourism joint-certification is expected to enhance international exchanges, increase tourist satisfaction, secure economic foundations for regions, and improve trust between countries.

Simulation of continuous thermally regenerative electrochemical flow cycle and coupled with photovoltaic/thermal system

Thermally regenerative electrochemical cycle (TREC) is an efficient, clean and feasible low-temperature thermoelectric conversion technology. Coupling it with flow battery (FB) can not only achieve continuous operation, but also can be used to realize the heat energy recovery of the photovoltaic/thermal (PV/T) system. In this paper, a continuous TREC-FB system including two charging-free cells is proposed for outputting power at both high and low temperatures. An electrochemical-thermodynamic coupling algebraic model is established to explore the effects of electrolyte flow rate, temperature difference and design parameters of heat exchanger on the power density (PTREC) and thermoelectric efficiency (ηele,TREC) of the TREC-FB. Experimental study on TREC-FB is carried out for model validation. The results show that PTREC is determined by the temperature difference and the electrolyte flow rate, which contribute to enhanced voltage and mass transfer, respectively. For specific heat source scenarios, the ηele,TREC is mainly affected by the flow rate, followed by the heat transfer area AH, and finally is the flow channel height and the thermal conductivity of the heat exchanger. Moreover, for the continuous TREC-FB-PV/T coupled system, the energy conversion efficiency reaches an average of 11 % within one day by optimizing the designed temperature difference.

Forecasting Foreign Exchange Rate with Machine Learning Techniques Chinese Yuan to US Dollar Using XGboost and LSTM Model

Predicting exchange rates is important because it affects all major markets and plays a big part in the economy. The goal of this study is to forecast future values of the Chinese Yuan (CNY) to US dollar exchange rate. One of the most crucial aspects of the economy is the rate of exchange of currencies. The currency exchange rate is required in commercial terms, such as profit and investment evaluation. The purpose of CNY rate prediction is to determine the future value of the Chinese Yuan (CNY) relative to the US dollar, which can be taken into account while making decisions and lower the chance of losing money. As a result, we require a technique that can assist in accurately assisting in business selections regarding when to execute the appropriate deals. For this research study three-year dataset is used from 25 April 2020 to 26 May 2023. For this research we used two different machine learning models and comparison between the LSTM and Xgboost models first one is Long Short-Term Memory (LSTM) and second is Extreme Gradient Boosting (XGboost). The empirical results showed that the LSTM model provided better results than XGboost. Therefore, this study suggest that the LSTM model will helpful for the government monetary policymaker, economists and other stakeholders to identify and forecast the future trend of the exchange rate and make their policies accordingly.

Contrasting regulation of leaf gas exchange of semi-arid tree species under repeated drought.

Predicting how plants respond to drought requires an understanding of how physiological mechanisms and drought response strategies occur, as these strategies underlie rates of gas exchange and productivity. We assessed the response of 11 plant traits to repeated experimental droughts in four co-occurring species of central Australia. The main goals of this study were to: (i) compare the response to drought between species; (ii) evaluate whether plants acclimated to repeated drought; and (iii) examine the degree of recovery in leaf gas exchange after cessation of drought. Our four species of study were two tree species and two shrub species, which field studies have shown to occupy different ecohydrological niches. The two tree species (Eucalyptus camaldulensis Dehnh. and Corymbia opaca (D.J.Carr & S.G.M.Carr) K.D.Hill & L.A.S.Johnson) had large reductions in stomatal conductance (gs) values, declining by 90% in the second drought. By contrast, the shrub species (Acacia aptaneura Maslin & J.E.Reid and Hakea macrocarpa A.Cunn. ex R.Br.) had smaller reductions gs in the second drought of 52 and 65%, respectively. Only A. aptaneura showed a physiological acclimatation to drought due to small declines in gs versus ᴪpd (0.08 slope) during repeated droughts, meaning they maintained higher rates of gs compared with plants that only experienced one final drought (0.19 slope). All species in all treatments rapidly recovered leaf gas exchange and leaf mass per area following drought, displaying physiological plasticity to drought exposure. This research refines our understanding of plant physiological responses to recurrent water stress, which has implications for modelling of vegetation, carbon assimilation and water use in semi-arid environments under drought.

Empirical Analysis of Vat Revenues on the Economic Growth of Albania

Objective: The presence of VAT revenues and its management to improve economic growth is crucial, very complex, and challenging. The aim is to see the influence of VAT revenue on economic growth, especially those that come from customs. Theoretical Framework: In this topic, the researchers are focused on the direct relationship between total VAT revenues and economic growth. According to the statistics of our economy, we choose to investigate the VAT revenues from customs looking to estimate their specific weight on the economic growth. Methods: In the econometric model, we introduce the VAT revenues from customs as the variable taken with precaution regarding value gain. Other variables based on the perspective of it, like CPI (inflation) and rate of exchange euro/all, are included in the model. Aggregate data presented by the official institutions are used to determine the influence of VAT on the economic growth measured by the GVA variable. This choice eliminates the duplication of the economic growth value by taxes and subsidies on products. Results and Discussion: The results underline the influence of VAT and CPI on economic growth (p&lt; 0.05). Therefore, the reduction of the inflation rate and the application of an optimal rate of VAT regarding the parameters of the economic situation in the country remains an emergency in recent days.

Protein Microarrays for High Throughput Hydrogen/Deuterium Exchange Monitored by FTIR Imaging.

Proteins form the fastest-growing therapeutic class. Due to their intrinsic instability, loss of native structure is common. Structure alteration must be carefully evaluated as structural changes may jeopardize the efficiency and safety of the protein-based drugs. Hydrogen deuterium exchange (HDX) has long been used to evaluate protein structure and dynamics. The rate of exchange constitutes a sensitive marker of the conformational state of the protein and of its stability. It is often monitored by mass spectrometry. Fourier transform infrared (FTIR) spectroscopy is another method with very promising capabilities. Combining protein microarrays with FTIR imaging resulted in high throughput HDX FTIR measurements. BaF2 slides bearing the protein microarrays were covered by another slide separated by a spacer, allowing us to flush the cell continuously with a flow of N2 gas saturated with 2H2O. Exchange occurred simultaneously for all proteins and single images covering ca. 96 spots of proteins that could be recorded on-line at selected time points. Each protein spot contained ca. 5 ng protein, and the entire array covered 2.5 × 2.5 mm2. Furthermore, HDX could be monitored in real time, and the experiment was therefore not subject to back-exchange problems. Analysis of HDX curves by inverse Laplace transform and by fitting exponential curves indicated that quantitative comparison of the samples is feasible. The paper also demonstrates how the whole process of analysis can be automatized to yield fast analyses.

The Long-Term Relationship Between the Rate of Exchange and Inflation in Iraq: An Application of the Vector Error Correction Model

This research aims to investigate whether the exchange rates and inflation in Iraq have a long-term equilibrium relationship or not. A dataset of exchange rates and inflation from 2000 to 2020 was used. Johansen’s cointegration test was employed to confirm that there is a long-term correlation between these variables. The Vector Error Correction Model (VECM) was utilized, along with Granger causality tests, to understand the long and short run connections and to determine if the causality flow is bidirectional or unidirectional. The results provided proof of a long-run equilibrium connection among inflation and rates of exchange, with strong evidence of a unidirectional causal flow from rates of exchange to inflation in Iraq.