High Exchange Rate Research Articles

An Empirical Analysis of the Relationship between Key Macroeconomic Variables and Economic Growth in Nigeria (1980-2021)

This study adopts the Vector Autoregressive (VAR) model to analyze the relationship between key macroeconomic variables and economic growth in Nigeria, Using time series data sourced from the World Bank Development Indicators (WDI), for the period 1980 to 2021. The key macroeconomic variables analyzed are inflation, exchange rate and money supply. The result gives an average high R2 of 0.7000 which connotes that the overall model is a good fit. The result of the VAR analysis at lag two indicates that the variables are dynamically interacted. Starting with the growth (GDP) equation, a 1% increase in the previous year values of exchange rate, GDP, inflation, and money supply lead to a 0.3% increase, 33% increase, 3% increase, and 26% increase in current GDP respectively. Here, GDP and money are positively related. The money supply shows that a 1% increase in the previous year values of exchange rate, GDP, inflation and money supply lead to a zero per cent decrease, 8% decrease, 7% decrease and 91% increase in current money supply. The result is consistent with monetary policy given that the relationship between money supply and inflation. The equation of inflation shows that a 1% increase in the previous year values of exchange rate, GDP, inflation and money supply lead to 9% decrease, 33% decrease, 68% increase and 15% increase in the current level of inflation. The consequences of a growing inflation and high exchange rate phenomenon are so damning that Nigeria cannot afford them. Such implications are glaring in the economy of Nigeria where many negative developments were traceable to the non-availability or insufficiency of foreign exchange for businesses especially small and medium enterprises (SME’s) with a frequent rise in general price level. Therefore, the need to aptly address this ugly development by the monetary and fiscal authority cannot be overemphasized. Keywords: Money supply; economic growth; VAR model, Inflation and exchange rate. DOI: 10.7176/JESD/14-8-06 Publication date: April 30 th 2023

Stable Soil Moisture Alleviates Water Stress and Improves Morphogenesis of Tomato Seedlings

Previous studies on soil water–plant relations have mostly focused on the soil water content (SWC), while the effect of soil moisture stability on plant growth has received surprisingly little attention. Potted tomato seedlings were used to examine the effect of stable soil moisture (SM) and fluctuating soil moisture (FM) on plant growth, development, and water use efficiency (WUE) in this study. The results showed that (i) soil moisture stability significantly affected the growth and development, photosynthetic characteristics, morphological traits, root morphology, and water physiological characteristics of seedling tomatoes, with SM being more conducive for most of these indices. (ii) SM improved the leaf WUE by reducing the content of abscisic acid in plants, regulating plant osmotic substances, maintaining a high gas exchange rate, and promoting plant morphology. (iii) SM could avoid water stress on tomato seedlings; even if the SWC of SM was equal to or lower than the SWC of FM, water stress would not occur under SM, whereas it would occur under FM. Overall, compared with FM, SM promoted beneficial plant morphology, maintained a high gas exchange rate, and did not induce water stress for tomato seedlings—ultimately improving WUE. This effect was more effective under low-SWC conditions than under high-SWC conditions. These findings provide a new perspective and theoretical basis for soil water–plant relations and indicate that SM has great potential in promoting plant growth and improving WUE.

Market concentration and producer prices

This study investigates the role of sectoral market structure in the inflationary dynamics of the domestic producer prices (D-PPI) in Türkiye. We start by reporting the fact that industries with intense competition had lower producer price inflation compared to industries with low-competition in the past few years. Further investigation shows that this differentiation across industries corresponds to the years with higher exchange rate volatility. The industries characterized with low-competition have higher annual producer price inflation on average than those that are characterized with high-competition especially during the periods of high exchange rate volatility. Results are robust to a wide set of additional specifications and cast light on the role of market structure on firms’ pricing behavior in Türkiye.

Numerical and experimental study of aerosol dispersion in the Do728 aircraft cabin

The dispersion of aerosols originating from one source, the ‘index’ passenger, within the cabin of the aircraft Do728 is studied experimentally using an aerosol-exhaling thermal manikin and in Reynolds-averaged Navier–Stokes simulations (RANS). The overall aim of the present study is the experimental determination of the aerosol spreading for the state-of-the-art mixing ventilation (MV) and to evaluate the potential of alternative ventilation concepts for controlling the aerosol spreading in RANS. For MV, the experiments showed that the ratio of inhaled to exhaled aerosol particles drops below 0.06% (volume ratio) for distances larger than two seat rows from the source. However, within a single row, the observed ratio is higher. Further, the dispersion is much weaker for a standing than for a seated index passenger. High air exchange rates and a well-guided flow prevent a dispersion of the aerosols in high concentrations over larger distances. Additionally, the positive effect of a mask and an increased air flow rate, and especially their combination are shown. In the complementary conducted RANS, the advantages of floor-based cabin displacement ventilation (CDV) which is alternative ventilation concept to MV, regarding spreading lengths and the dwell time of the aerosols in the cabin were determined. The obtained results also underline the importance of the flow field for the aerosol dispersion. Further, additional unsteady RANS (URANS) simulations of the short-term process of the initial aerosol cloud formation highlighted that the momentum decay of the breathing and the evaporation processes take place within a few seconds only.

Mark-recapture estimates of seasonal abundance and survivorship for bottlenose dolphins (Tursiops truncatus) near Charleston, South Carolina, USA

The stock structure of western North Atlantic bottlenose dolphins (Tursiops truncatus) is complex, with seasonally migratory stocks often overlapping with year-round resident stocks. High rates of exchange between northernmost sites have been documented but movement and seasonal fluctuation in abundance among sites along the southern portion of the US Atlantic coast is not well understood. To better understand seasonal abundance, a three-year mark-recapture study of bottlenose dolphins in coastal and estuarine waters near Charleston, South Carolina, USA was conducted. A robust design was employed in order to minimise bias and more precisely determine seasonal estimates of abundance and concurrently examine temporary immigration/emigration and survivorship. Systematic boat-based surveys were carried out (n = 192) from January 2004 to December 2006. The entire study area was surveyed one week per month; an additional survey was conducted in the months in which seasonal abundance was estimated: January (winter), April (spring), July (summer) and October (autumn). Standard photo-identification techniques were used to accumulate sightings of 521 distinctively marked dolphins, 65% of which were sighted more than once. Pollock’s robust design was applied using MARK and the ensuing abundance estimates were adjusted for the seasonal proportion of unmarked dolphins (ranging from 0.27 to 0.40) in the population. Estimates ranged from 364 (95% CI = 305–442) in January 2004 to 910 (95% CI = 819–1018) in October 2006. Summer abundance estimates were consistently greater than those from winter months, although estimates varied considerably among years. The same model was used to calculate an annual survival rate estimate of 0.951 (95% CI = 0.882–1.00) for marked individuals within the population. A high degree of transience, demonstrated by seasonal influxes of single-sighted individuals, made it difficult to differentiate between mortality and permanent emigration. The results support the occurrence of three distinct dolphin groups found in Charleston waters: year-round residents; seasonal residents; and transients. Reporting abundance and survivorship estimates together is useful in explaining and validating results for populations in which transient individuals occur. These results provide important information for stock and viability assessment of coastal bottlenose dolphins in the western North Atlantic.

Foreign Debt and Economic Development in Nigeria (2015 - 2020)

This study carried out an empirical analysis of foreign debt and economic development in Nigeria covering the period 2015 – 2020. The study used an ex post facto research design, which is based on examining the independent and dependent variables after events have already occurred and using data that is already available in order to determine the relationship between the variables. In order to gather data for this study, a documentary method based on the examination of documents and materials was used. Documentary methods are the procedures used to classify, examine, and analyze documents, whether they are in the public or private domain. To analyze the data generated from this study, the study relied on qualitative descriptive analysis. The major findings of the study are that there are other intervening variables that affect economic growth in addition to health and poverty indicators, external debt is viewed as being harmful to a nation's ability to advance economically, and given the impact of debt to the living standard of the Nigeria people, health expenditure on economics, it could be deduced that even though health expenditure increases, it could have a negligible impact on economic growth if it is not maximized effectively to produce improved health outcomes. It is therefore the recommendation of the study that government should diversify the nation's export base so as to increase export earnings and promote industrialization in order to reduce import dependency as a high exchange rate will make our goods more attractive in the foreign market and will increase foreign exchange earnings.

Experimental and Numerical Simulations of Climatic Loads in Insulating Glass Units by Controlled Change of Pressure in the Gap

Insulating glass units (IGUs) are building components that show a particular structural behavior. Although such structures have many advantages from the point of view of thermal protection of buildings, they show particular structural behavior under climatic loads. The inability to equalize the pressure with the surrounding atmospheric air causes over- or under-pressure inside the gap. The phenomenon may result in the deformation of the panes under the influence of temporary or cyclical changes in weather conditions. This article presents the results of an experimental campaign with a representative IGU sample. The sample had dimensions of 500 mm × 500 mm and was composed of two 6 mm glass panes and a 16 mm wide spacer. The experiments were carried out using a rarely used methodology by inducing a controlled pressure change in the gap. Subsequently, analytical and numerical models were developed, and the results were compared with the experimental findings. The study found that the rapid injection/withdrawal of gas into/from the gap causes a sudden change in the pressure inside the gap, which decreases in absolute value and stabilizes after a few seconds. The decrease, on average, of 7% is due to adiabatic effects resulting from the high rate of gas exchange. The results from the numerical and analytical studies underestimate the pressure difference values obtained in the tests by an average of 8%. In terms of deflections and stresses, the results overestimate the experiments by 16% and 32%, respectively. This finding indicates the presence of a partial rotational restrain of the panes’ edges, which some researchers have also reported. This effect is usually ignored in engineering practice.

Veza kamatne stope i deviznog kursa u Kini - koeficijent unakrsne korelacije dobijen DCCA analizom primenom pristupa "kliznog prozora"

This study aims to investigate the dynamics of the interest rates and exchange rates during the pandemic-induced crisis in the Chinese economy. In the study, rolling window detrended cross-correlation analysis (DCCA) was used. The DCCA coefficient was extracted based on detrended fluctuation analysis (DFA). The data used in the study are the daily data of the period from 2/1/2019 to 7/5/2021. The results obtained in the study suggest the presence of positive cross-correlation between China's interest rate and exchange rate after the COVID-19 pandemic, and they also report the existence of weak positive cross-correlation during the initial days of the pandemic. However, the weak positive cross-correlation became stronger over time. Higher interest rates are associated with higher exchange rates after the COVID-19 pandemic. The results of the research study have policy implications in that conventional higher interest rates introduced to defend the exchange rate might fail during pandemic-induced crises.

НАУКОВІ ЗАСАДИ ТА ОСОБЛИВОСТІ КОНТРОЛІНГУ СТРАТЕГІЧНОГО УПРАВЛІННЯ ТЕЛЕКОМУНІКАЦІЙНИМИ ПІДПРИЄМСТВАМИ В УМОВАХ ЦИФРОВОЇ ЕКОНОМІКИ

Today, digital transformations change people's lives, the principles and forms of functioning of enterprises, and also have an impact on all levels of the economy. The formation and development of the digital economy necessitates the processing and transmission of a large flow of data at a high exchange rate. The authors of the article identified the key trends of strategic management of enterprises in the conditions of the digital economy and sharp changes in the external and internal environments of enterprises in these conditions. This necessity is technically and physically ensured thanks to the work of telecommunication enterprises. This situation requires constant monitoring and analysis of the external environment from telecommunication companies. Thus, the development of the digital economy determines the search by telecommunications enterprises for modern tools for identifying risks, analyzing trends, setting benchmarks, preventing adverse phenomena, and finding alternative development options for the enterprise. This becomes possible thanks to the implementation of such an economic tool as strategic management controlling, which is characterized by the use of modern digital technologies and the application of modern accounting and information processing methods. This ensures the company's survival in changing conditions and strengthens the strategic advantages of the telecommunications company and the services it provides and plans to provide in the two-term perspective. The article defines the effectiveness of the strategic management system of a telecommunications enterprise and proposes the implementation of strategic management controlling, which is a new phenomenon in the theory and practice of strategic enterprise management. The functions of the strategic management control group are outlined and the criteria that must be taken into account by enterprise management for business survival and preservation are specified. A model of the interaction of strategic controlling functions and controlling criteria for telecommunications enterprises is proposed. The necessity of using controlling as a strategic management tool, which allows forecasting and identifying risks at enterprises for timely change of strategy or its adjustment in accordance with new threats and opportunities, is emphasized.

Does Public Debt Matter for Economic Growth in Nigeria

Nigeria, as an emerging economy, has experienced significant challenges in sustaining its economic growth trajectory. The issue of excessive borrowing has become a prominent concern in recent years. This work therefore examined the impact of excessive borrowing on Nigeria’s economic growth using data from 1980-2022. The Autoregressive Distributed Lag test method of co-integration was employed for the analysis of short-run and long-run impacts of excessive borrowing on economic growth. The long-run result endorsed the findings that excessive borrowing impacts negatively on the economic growth of Nigeria. Thus, excessive borrowing depreciates the real gross domestic product of Nigeria. The study recommends that government should embark on borrowing only when there is low interest rate. Also, diversification of the economy should be the priority of the government as this will deepen the revenue sources of the nation to avoid being tempted to borrow excessively. In addition, fiscal and monetary policies should be properly harmonized to tackle macroeconomic instability which has led to high inflation rate, high interest rate and high exchange rate.

Performance Analysis of a Novel Cross-flow Solar Air Heater with Square Perforated Absorber Plate: An Experimental Study

The current study introduces and analyzes a novel square cross-flow perforated solar air heater (SAH). Since the convection mechanism in SAHs is weak, numerous methods have been suggested to address this problem and improve thermal efficiency. Perforations and cross-flow configuration generate high turbulency and, consequently, high convection rate resulted. Hence these methods have been applied to enhance thermal efficiency. To achieve this goal, an experimental setup was fabricated and tested at outdoor conditions for two air mass flow rates (mair) of 0.015 kg/s and 0.03 kg/s while several sensors monitored the collector’s heat dynamics and ambient conditions. The obtained results illustrate that outlet temperature reaches the peak values of 38 oC and 34 oC, which is only 6 oC and 7 oC lower than the maximum absorber temperature. This crucial issue proves a high heat exchange rate in the fabricated SAH that causes the absorber temperature to approach the outlet temperature due to high turbulency. The strong convection mechanism in the fabricated SAH improves daily thermal efficiency, in which its value reaches nearly 78.6% for the mass flow rate of 0.03 kg/s. In conclusion, the square cross-flow perforated SAH is an economy, applicable, compact collector, ensuring high thermal efficiency.

Bipyridil-based chelators for Gd(III) complexation: kinetic, structural and relaxation properties.

In the last 20 years, research in the field of MRI (magnetic resonance imaging) contrast agents (CAs) has been intensified due to the emergence of a disease called nephrogenic systemic fibrosis (NSF). NSF has been linked to the in vivo dissociation of certain Gd(III)-based compounds applied in MRI as CAs. To prevent the dechelation of the probes after intravenous injection, the improvement of their in vivo stability is highly desired. The inertness of the Gd(III) chelates can be increased through the rigidification of the ligand structure. One of the potential ligands is (2,2',2'',2'''-(([2,2'-bipyridine]-6,6'-diylbis(methylene))bis(azanetriyl))tetraacetic acid) (H4DIPTA), which has been successfully used as a fluorescent probe for lanthanides; however, it has never been considered as a potential chelator for Gd(III) ions. In this paper, we report the thermodynamic, kinetic and structural features of the complex formed between Gd(III) and DIPTA. Since the solubility of the [Gd(DIPTA)]- chelate is very low under acidic conditions, hampering its thermodynamic characterization, we can only assume that its stability is close to that determined for the structural analogue [Gd(FENTA)]- (H4FENTA: (1,10-phenanthroline-2,9-diyl)bis(methyliminodiacetic acid)), which is similar to that determined for the agent [Gd(DTPA)]2- routinely used in clinical practice. Unfortunately, the inertness of [Gd(DIPTA)]- is significantly lower (t1/2 = 1.34 h) than that observed for [Gd(EGTA)]- and [Gd(DTPA)]2- as a result of its spontaneous dissociation pathway during dechelation. The relaxivity values of [Gd(DIPTA)]- are comparable with those of [Gd(FENTA)]- and somewhat higher than the values characterizing [Gd(DTPA)]2-. Luminescence lifetime measurements indicate the presence of one water molecule (q = 1) in the inner sphere of the complex with a relatively high water exchange rate (k298ex = 43(5) × 106 s-1). DFT calculations suggest a rigid distorted tricapped trigonal prismatic polyhedron for the Gd(III) complex. On the basis of these results, we can conclude that the bipyridine backbone is not favourable with respect to the inertness of the chelate.

The Analysis of the Short-term Capital Movements by Using the VAR Model: The Case of Turkey

This paper investigates the relations among short-term capital inflows, government deficit, interest rate differentials, real exchange rate and some accounts of the balance of payments in Turkey in 1990s by using the vector autoregression (VAR) technique. The dynamic behaviours of each variable due to random shocks given to short-term foreign liabilities are captured by impulse response functions, and the portion of variance in the prediction for each variable in the system that is attributable to its own innovations and to shocks to other variables in the system is analysed by variance decomposition method. It is found that the policy of high interest-low exchange rate (hot money) is the main reason for the short-term capital inflows in Turkey, and we propose some main controls on capital inflows to limit some of the macroeconomic repercussions of these inflows.

Labor migration and its impact on economic status

The present study entitled Labor Migration and its Impact in Bhaktapur has been carried out with the main objective to identify the socio-economic and demographic characteristics of international labor migrants' households, This study was conducted by applying descriptive type of research by using survey based research design. International labour migration is a process which is very significant. Remittance from abroad is supporting the national economy to a great extent. Unemployment is a burning issue and foreign employment is providing employment to many from across Nepal. Foreign currency has weight and with the high exchange rate it can really be rewarding Work and Wage is mostly determined by skill, education and fluency. People are surviving and at the same time hoping that sooner or later foreign employment will be a blessing. It is just a matter of years spend abroad by the migrants that will improve the economic condition of the respective households. Level of income for migrant households has increased but expenditure also increased respectively. Standard of living and quality of food are raised of their family. Unemployment lack of agricultural land and poverty are important factors for emigration associated with origin. Likewise, high wage rate, easy availability of unskilled works and no need of higher education other important factors associated destination. Some positive and negative impacts also seem in foreign employment.

How many neurons are needed to make a short-term prediction of the Bitcoin exchange rate?

The goal of our work was to select a neural network architecture that would give the best prediction of the Bitcoin exchange rate using historical data. Our work fits into the very important topic of predicting the value of the cryptocurrency exchange rate, and makes use of recent data which, as a result of the high Bitcoin exchange rate dynamics of the last year, differs significantly from those of previous years. We propose and test a number of neural network-based architectures and conduct a discussion of the results. Unlike previous state-of-the-art works, we conducted a comprehensive comparison of three different neural network-based models: MLP (multilayer perceptron), LSTM (long short-term memory) and CNN (convolutional neural network). We tested them for a wide range of parameters. The results we present are, to the best of our knowledge, the most up to date when it comes to the application of artificial intelligence methods for the prediction of cryptocurrency exchange rates. The best-performing architectures were used for a website that gives real-time predictions of the Bitcoin exchange rate. The website is available at http://stpbtc-ii.up.krakow.pl/. Source codes of our research are available to download in order to make our experiment reproducible.

Numerical study on the thermal-induced mechanical behavior in deep energy diaphragm wall (EDW): The long-term soil elastoplastic effects

The energy diaphragm wall (EDW) attracted increasing attention due to its high energy exchange rate and low space occupation. The current research on EDW primarily focused on its heat exchange capacity and performance. The elastoplastic effects on thermal-induced mechanical behavior caused by soil were neglected, which might underestimate the wall deflections in deep EDW due to the asymmetrical surrounding pile height pressure on both sides. This paper investigated the thermal performance and the induced mechanical behavior in deep energy diaphragm wall (EDW) based on the finite element analysis method (FEA) by the COMSOL Multiphysics software. Firstly, the thermal performance of varied pipe configurations (e.g., single U-shaped; W-shaped; double-U shaped; horizontal arrangement) was studied. Then it was followed by a study of a single heating–cooling cycle with a single U-shaped pipe, where the elastoplastic impact of the soil in the deep EDW was observed. Moreover, a parametric analysis with a long operation period (30 years) perspective was proposed regarding the heat load modes, the pipe buried locations, the air temperature of the adjacent underground space, and the excavation level. Results revealed that the heat transfer process caused an obvious impact on thermal-induced mechanical behavior. Higher levels of heat injection (Case 3) and extraction (Case 2) both led to a relatively large wall deflection after 30 years. The horizontal displacements at the top of the wall under Case 3 and Case 2 were up to 30.5 mm and 25.9 mm, respectively, while 22.9 mm under balanced case (Case 1) and 21.1 mm under the no heat load case (Case 0). When the pipe was close to the side of the excavation, the plastic deformation was about 1.25 times greater than that on the soil side, where the thermal contraction effects were emphasized. Besides, the air temperature in the underground space caused a small impact on the plastic strain in the soil domain. Because of the enhancement in the heat transfer process from the air to the wall while the air temperature increased, resulting in the average wall temperature raised. In addition, the influence caused by the excavation levels was quite evident. The deeper the excavation level, the easier the plastic strain to occur. This paper proposed a new perspective for understanding thermal-induced mechanical behavior in deep EDW, especially the long-term soil elastoplastic effects, which exerted a complex impact on the deformation variation of the diaphragm wall.

Effect of economic indices on the performance of listed multinational manufacturing companies in Nigeria

This paper examines the effect of economic indices on the financial performance of multinational manufacturing firms in Nigeria from 2004-2021. The Expo facto research design was adopted along with ordinary least squares, and other econometric tests to estimate the effect of the predictor variables on the response variable. The population comprises 22 listed multination manufacturing companies and 19 companies were used as the sample size which represents 86 percent of the population. We found that the exchange rate, inflation rate, and government capital expenditure all have a correlation with return on equity (ROE) based on the regression results, but other econometric parameters showed no significant relationships between the explanatory variables and ROE because a 1 percent rise in predictor variables results in a decrease in ROE. This is a clear indication that Nigeria’s economy is bleeding profusely due to the high exchange rate and the economy is still battling inflation coupled with infrastructural challenges. We recommended that to reduce the effect of the exchange rate, the Nigerian government should make the economic environment business-friendly by encouraging mass production and patronage of made-in-Nigeria in order to curtail the increase in the importation and adopt the public-private partnership (PPP) model to harness other mineral resources for export thereby putting cost-push inflation in check and the exchange rate. Also, the electricity supply should be improved to mitigate the costs of production which will also help address the inflation rate.

Economic Crisis and Personal Financing in Nigeria

The study was carried out to find out the relationship between economic crisis and personal financing among Nigerian workers. The research work made use of both primary and secondary data. Primary data were collected through questionnaires and secondary data sourced from the Central Bank Annual Reports and Bureau of Statistics. Multivariate analysis was applied to determine the relationship between Economic crisis (proxied by inflation, exchange rate, unemployment and cost of living) and personal financing (proxied by spending, tax, savings and investment). Results from the analysis showed a significant positive relationship between economic crisis and personal savings of Nigerian workers. The results showed further that both workers' personal spending and taxes have a positive relationship with the economic crisis in Nigeria, and their relationships are statistically significant at a 5% significance level. It means all the proxied economic crisis variables jointly affect Nigerian workers' personal savings, spending and personal taxes. However, economic crisis had no significant effect on the investment of Nigerian workers. Economic crisis does not influence how Nigerian workers invest their meagre income. Therefore, the economic drivers (governments) are advised to pay more attention to tackling the problems of the high exchange rate, inflation rate, and unemployment rate bedeviling the country to reduce the overall cost of living in Nigeria.

3D Printed Thick Reduced Graphene Oxide: Manganese Oxide/Carbon Nanotube Hybrid Electrode with Highly Ordered Microstructures for Supercapacitors

AbstractHigh capacitance and good rate performance supercapacitors are needed to power sensors and miniaturized electrical devices. Thick electrodes are promising to increase the mass loading of active materials in supercapacitors, but the 3D geometries and microstructures in thick electrodes still hinder the development with high electron and ion exchange rate and accessible active sites. The scaffold 3D electrodes of reduced graphene oxide:manganese oxide/carbon nanotube (rGO:MnOx/CNT) are manufactured by material extrusion 3D printing (ME3DP), where the mass ratio of rGO to MnOx/CNT composites, thickness, and mass loading per unit area are controllable. The increasing amount of MnOx/CNT composites boosts the areal capacitance. Although the rate capability decays fast with the increasing of MnOx/CNT, it remains stable at different thicknesses (1.2, 1.6, and 2 mm). 2 mm thick rGO:MnOx/CNT (weight ratio 5:3) electrode exhibits an area capacitance of 302.13 mF cm−2 at a current density of 0.5 mA cm−2, due to the highly ordered rGO networks. Compared to the casted electrodes, the microstructures in the 3D printed electrode contribute to lower resistances for the charge and ion transportation.

The Poisoned Chalice of Evolution in Water: Physiological Novelty Versus Morphological Simplification in Marsileaceae

The Marsileaceae is a small family of semi-aquatic ferns displaying numerous traits commonly observed in angiosperms, including heterospory, sophisticated hydraulic architecture, and high rates of atmospheric gas exchange. Despite these similar traits, Marsileaceae is comparatively ecologically limited. Most species are found in Marsilea which is sister to Regnellidium and Pilularia, together these two genera include only seven species. Here we studied the anatomy and physiology of Marsileaceae to better understand the potential constraints on ecological and species diversity in this family. We focused on epidermal anatomy and stomatal responses to changes in light and water availability, which are unique amongst ferns. We found two evolutionary strategies in Marsileaceae, one of morphological simplification, physiological inflexibility, and aquatic specialization in Pilularia; which contrasts with a strategy of maximizing photosynthetic carbon gain at the expense of high rates of water loss in Marsilea and Regnellidium. We conclude that aquatic environments provide evolutionary opportunities for physiological innovation with regard to stomatal function, as well as selective pressures that drive the canalized evolution of highly specialized aquatic forms.