Wyniki wyszukiwania - Biblioteka Nauki

1

The Chlorophyll-a Response of Phytoplankton to Ratio N/P in Different Coastal Waters

100%

Maslukah L. , Handoyo G. , Wulandari S. Y. , Sihite C. B. , Sarjito

Ecological Engineering & Environmental Technology

|

2023

|

tom Vol. 24, iss. 9

121--129

EN

Phytoplankton growth is influenced by the presence of nutrients N (nitrogen) and P (phosphor). Each region has a specific N/P ratio, due to the influence of anthropogenic inputs. This study aimed to assess the response of phytoplankton chlorophyll-a (Chl-a) biomass due to differences in N/P ratio by the influence of river flow in the north coast of Java; Jobokuto Bay (Jepara), the coastal waters of Semarang and the front of the Cisadane river. N-nutrients were analyzed in the form of N-NO3 (nitrate), and N-NH4+ (ammonium ions), and orthophosphate ions (P-PO42-). Nutrient analysis was spectrometric, using the reduction methods (nitrate), ammonium (indophenolblue), and phosphate (molybdenum-blue). Test for site differences using Kruskall-Wallis, followed by a posthoc test. The results showed that Semarang waters had a lower N/P (Stoichiometric) ratio than Jepara and Cisadane, which can be used to predict that P nutrient input is higher than N. This high P input impacts microalgal development (chlorophyll-a). In addition, we also found Semarang waters to have higher speciation of inorganic N in the form of ammonium, which is one of the drivers of eutrophication in these waters. The use of a ratio of N/P is very important in estimating the eutrophication process and can be used to estimate the dominance of nutrients entering the water due to anthropogenic activities in the upstream area.

2

Impact of Annealing Thin Films In(OH)xSy Growth By Solution Technique

86%

Mosiori C. O. , Magare R. , Munji M.

Path of Science

|

2017

|

tom 3

|

nr 7

3.1-3.8

EN

Indium Hydroxy Sulphide has demonstrated abundance in resources, low prices, nontoxic characteristics, radiation resistance, high temperature resistance, and chemical stability, and therefore it has become an extremely important photoelectric, photovoltaic, and light sensing thin film material. Some treatment on this material include thermal annealing which is a process used for intrinsic stress liberation, structural improving, and surface roughness to control its electro-optical properties. In a qualitative way, annealing modifies surface morphology, intrinsic parameters, and electron mobility with temperature and time. In this work, an explanation on the surface modification of In(OH)xSy thin films when subjected to an annealing process is discussed. Both electrical and optical effects caused by annealing were carried out and characterizations were performed at different annealing temperatures in nitrogen in the temperature range 373–573 K. Using optical measurements data and simulated data, Scout software was employed and the results showed that increasing annealing temperature causes a slight decrease in transmittance with a consequence of modifying the energy band gaps values between 2.79–3.32 eV. It was concluded that annealing influence optical transmittance and resistance of the film make the thin films potential for photovoltaic, and light sensing applications.

3

Nutrient stoichiometric relations and biogeochemical niche in coexisting plants species: effect of simulated climate change

86%

Penuelas J. , Sardans J. , Ogaya R. , Estiarte M.

Polish Journal of Ecology

|

2008

|

tom 56

|

nr 4

613-622

EN

Here we define a “biogeochemical niche” characterized by the species position in the multivariate space generated by its content not only of macronutrients like N, P or K, but also of micronutrients such as Mo, Mg and Ca, and trace toxic elements such as Pb and As. We then hypothesize that the flexibility of the species “biogeochemical niche” will influence the quality of plant tissue, which may have implications for herbivores, and will affect the species capacity to respond to disturbances and climate change and to adapt to the new climate conditions. We show with a simple multivariate procedure, a principal component analysis (PCA), first, that there is a strong differentiation in the total and relative (stoichiometry) content of the different elements in coexisting plant species, and, second, that there is species-specific plasticity in the response of this elemental composition to experimental climate change. The concentrations of foliar macro and micronutrients, as well as trace elements were measured in several tree species (Quercus ilex L., Phillyrea latifolia L. and Arbutus unedo L. in a Mediterranean broad leaf forest (Prades Mts) and in shrub species (Erica multiflora L., Globularia alypum L. and Dorycnium pentaphyllum Scop.) in a Mediterranean shrubland (Garraf Mts) in control plants and in plants grown in experimental drought and warming plots. The climate conditions were monitored during the period 1999–2005. During this period, in the Prades experiment the drought plots had on average a soil moisture content 9% lower than the control plots, whereas in the Garraf experiment the drought treatment led to a mean reduction in soil moisture of 21% and the warming treatment to 0.9ºC rise. The species with greater changes in biogeochemical niche under increased warming or drought, Arbutus unedo, Erica multiflora and Globularia alypum, were those that were also more affected in growth, photosynthetic capacity and other eco-physiological traits. The species differentiations indicate a strong biogeochemical niche, and that the changes in biogeochemical niche are probably an underlying factor in community structure shifts.

4

Stechiometria i kinetyka procesów metabolicznych wybranych drobnoustrojów

72%

Krzystek L.

Zeszyty Naukowe. Rozprawy Naukowe / Politechnika Łódzka

|

2002

|

tom Z. 303

5-114

PL

Podstawą ilościowej analizy metabolizmu drobnoustrojów jest formułowanie stechiometrii indywidualnych reakcji, a następnie szlaków metabolicznych, które stanowią punkt wyjścia dla przeprowadzenia bilansów masy i energii. Umożliwia to opracowywanie metod ekonomicznego planowania i kierowania procesem produkcyjnym oraz matematycznego opisu przebiegu danego procesu. W opracowaniu zawarto założenia teoretyczne oraz praktyczne zastosowanie bilansów masy i energii. Omówiona została stechiometria bioprocesów, wyprowadzono ogólne zależności dla bilansów masy i energii do opisu metabolicznego wzrostu drobnoustrojów i tworzenia produktów. Wyjaśniono znaczenie wynikających z bilansów współczynników wydajności oraz zależności między współczynnikami stechiometrycznymi a doświadczalnymi współczynnikami wydajności. Analizowano ograniczenia dla teoretycznych współczynników wydajności biomasy i produktów w bioprocesach. Przedstawiono analizę zgodności danych doświadczalnych na podstawie prostego modelu metabolicznego, uzupełnioną o zaproponowaną zależność opisującą wykorzystanie energii w postaci ATP. Przedstawiono również zastosowanie bilansów w analizie kinetycznej procesów metabolicznych. Teorie tę zilustrowano przykładami procesu wytwarzania biomasy Kluyveromyces fragilis, produkcji etanolu przez Saccharomyces cerevisiae oraz produkcji kwasu cytrynowego przez Aspergillus niger. Na podstawie przeprowadzonych badań doświadczalnych, uwzględniając specyfikę powyższych procesów, sformułowano stechiometrię, bilanse masy i energii, wyznaczono współczynniki wydajności. Sprawdzono zgodność otrzymanych wyników i prawidłowość przebiegu procesu. Wyznaczono zapotrzebowanie energii na procesy przemiany podstawowej i porównano z danymi literaturowymi. Uzyskano bardzo dobrą zgodność wyników obliczeń teoretycznych i danych doświadczalnych. Opracowano model kinetyczny opisujący przebieg procesu wytwarzania kwasu cytrynowego przez Aspergillus niger. Zaproponowana stechiometria obejmuje zarówno procesy zachodzące podczas wzrostu pleśni jak i produkcji kwasu cytrynowego. Do opisu większości szybkości reakcji zastosowano zależność Michaelis'a-Menten oraz odpowiednie równania kinetyczne uwzględniające inhibicję. Przeprowadzono obiczenia symulacyjne dla procesu okresowego i stwierdzono, że zaproponowany model matematyczny bardzo dobrze odzwierciedla charakter zmian stężeń analizowanych substratów i produktów.

EN

A quantitative analysis of the metabolism of microorganisms is based on formulation of the stoichiometry of individual reactions, and next metabolic pathways which constitute a basis for mass and energy balances. This enables a development of the methods of economic planning and management of production processes and mathematical description of particular processes. The study presents theoretical assumptions and practical applications of mass and energy balances. Stoichiometry of bioprocesses was discussed, general relationships for mass and energy balances were derived for the description of metabolic growth of microorganisms and product formation. The significance of yield coefficients resulting from the balances and relations between stoichiometric coefficients and experimental yield coefficients were explained. Restrictions for theoretical yield coefficients of biomass and products during bioprocesses were analyzed. Agreement of experimental data was analyzed using a simple metabolic model completed with a proposed relation describing the recovery of energy in the form of ATP. Applications of the balances in the kinetic analysis of metabolic processes were presented. This theory was illustrated by examples of the process of production of Kluyveromyces fragilis biomass, ethanbl production by Saccharomyces cerevisiae and citric acid production by Aspergillus niger. On the basis of experimental investigations, taking into account characteristics of these processes, the stoichiometry and mass and energy balances were formulated, and yield coefficients were determined. Agreement of the results and correctness of the process was checked. Energy demand for basic metabolic processes was determined and compared with theoretical data. Very good agreement of the results of theoretical calculations and experimental data was obtained. A kinetic model which described citric acid production by A. niger was developed. The proposed stoichiometry covers both the processes which take place during mould growth and citric acid accumulation. For the description of most reaction rates the Michaelis-Menten kinetics and relevant kinetic equations taking into account the inhibition were used. A simulation was made for a batch process and it was found that it illustrated very well the character of changes in experimental data.

5

Water- and N-induced changes in soil C:N:P stoichiometry and its implications for N limitation of a desert steppe species, Glycyrrhiza uralensis

72%

Huang J. , Yu H. , Zhang F. , Li M. , Lin H.

Polish Journal of Ecology

|

2016

|

tom 64

|

nr 2

EN

Changes in precipitation patterns and the deposition of atmospheric nitrogen (N) increase the possibility of altering soil carbon (C):N:phosphorus (P) stoichiometry through their effects on soil C and nutrient dynamics, especially in water- and N-limited ecosystems. We conducted separate 2-year watering and N addition experiments, and examined soil C:N:P stoichiometry, relative growth rate, and leaf N resorption traits of Glycyrrhiza uralensis Fisch in a desert steppe of northwestern China. Our objectives were to determine how soil C:N:P stoichiometry responded to climate change, and its indications for plant growth and N resorption. The results showed that additional water increased N loss and thus decreased N availability, resulting in high N resorption from senescing leaves of G. uralensis. N addition increased N availability, consequently reducing plant N dependence on leaf resorption. High relative growth rates occurred with intermediate N:P and C:N ratios, while high N resorption occurred with a low N:P ratio but a high C:N ratio. Our results indicate that soil C:N:P stoichiometry also could be a good indicator of N limitation for desert steppe species. Altered soil C:N:P stoichiometry affects the N strategy of plants, and will be expected to further influence the structure and function of the desert steppe community in the near future.

6

Leaf nitrogen and phosphorus stoichiometry of plants from natural and restorable communities at lands used for Qinghai-Tibet Highway Construction, China

72%

Luo M. W. , Mao L. , Guo Z. G.

Polish Journal of Ecology

|

2014

|

tom 62

|

nr 2

EN

Highway network construction is one of common factors contributing to alpine grassland degradation in the Qinghai-Tibet Plateau as well as other regions, resulting in big area land used for highway construction by abruptly removing the vegetation and topsoil on both sides of roadbed. Taking the Land Used for Qinghai-Tibet Highway Construction (LUQHC) produced in 1994 as an example, a field survey was conducted to investigate the leaf N, P stoichiometry of plants from natural communities and restorable communities by using all plants and same pairwise of species, because the natural vegetation restoration at LUQHC is driven by element availability to some extent. This study showed that plants were probably P-limited in study region and the variation of N:P ratio was closely related to leaf P concentration. Results of same pairwise of species showed that the leaf N, P and N:P ratio of plants from restorable communities were higher than those of adjacent natural communities, indicating that leaf N and P were simultaneously affected by the environment circumstance of LUQHC. However, results of all species showed that the environment factors only impacted on leaf N concentration. These showed that the plant in restorable communities suffered from more intense P-limited conditions than those in natural communities, and that the same pairwise of species sampling was better to acquire the N- or P-limitation status for plant in restorable communities than all species. This study also showed that phylogenetic variation (family and genus identity) was key factor affecting the variations of N, P stoichiometry.

7

Soil C:P ratio along elevational gradients in Picea schrenkiana forest of Tianshan Mountains

72%

Cao Y. , Wang Y. , Xu Z.

Polish Journal of Ecology

|

2018

|

tom 66

|

nr 4

EN

Forest soils potentially store a large pool of carbon and phosphorus. A deep understanding of the total carbon and phosphorus stock in forest soils is vital in the assessment of the nutrients dynamics in forest ecosystems. This study examined the effects of elevation, soil depth, and climatic variables, specifically mean annual temperature (MAT) and mean annual precipitation (MAP), on soil carbon and organic phosphorus in Schrenk's spruce (Picea schrenkiana) forest at Tianshan Mountains. Results showed that soil organic carbon (SOC) significantly increased while organic phosphorus decreased with elevation. Interestingly, carbon increased faster with increasing elevation in the alluvial horizon than in the leached horizon, demonstrating the important role of deep soils in carbon sequestration potential. SOC concentration decreased with soil depth, whereas phosphorus concentration initially decreased and then increased. SOC had no significant relationships with MAT and MAP, whereas phosphorus concentration decreased with MAT. Similar to the impacts of MAT and MAP on SOC, these two climatic variables also exerted no significant influence on C:P ratio.

8

Redox control of photosynthetic acclimation in plants

72%

Pfannschmidt T.

BioTechnologia. Journal of Biotechnology Computational Biology and Bionanotechnology

|

2013

|

tom 94

|

nr 2

9

Influence of branch death on leaf nutrient status and stoichiometry of wild apple trees (Malus sieversii) in the Western Tianshan Mountains, China

72%

Tao Y. , Nuerhailati M. , Zhang Y.-M. , Zhang J. , Yin B.-F. , Zhou X.-B.

Polish Journal of Ecology

|

2020

|

tom 68

|

nr 4

10

Impact of extra nitrogen on ecological stoichiometry of Alpine grasslands on Tibetan Plateau: meta-analysis

72%

Zhang H. R. , Sun W. , Li S. W. , Han F. S. , Yu C. Q. , Zhang X. Z. , Wang J. S. , He Y. T. , Zhong Z. M.

Polish Journal of Ecology

|

2018

|

tom 66

|

nr 4

EN

The general impact of extra nitrogen on ecological stoichiometry was examined in alpine grasslands on the Tibetan Plateau. Extra nitrogen increased the ratio of nitrogen to phosphorus (N:P ratio) in leaves and aboveground parts of plants by 43.4% and 32.7%, respectively. In contrast, extra nitrogen reduced the ratio of carbon to nitrogen (C:N ratio) in leaves by 30.6%. Extra nitrogen decreased soil C:N ratio by 9.1% in alpine meadows, but increased soil C:N ratio by 3.4% in alpine steppes. Extra urea had a stronger positive impact on aboveground vegetation N:P ratio than did extra ammonium nitrate. Extra urea rather than ammonium nitrate decreased aboveground vegetation C:N ratio and soil C:N ratio. The impact of extra nitrogen on aboveground vegetation N:P ratio was positively correlated with latitude, mean annual temperature and precipitation, nitrogen application rate and accumulated amount, but negatively correlated with elevation, duration and aboveground vegetation N:P ratio of the control plots. The impact of extra nitrogen on leaves N:P ratio was positively correlated with nitrogen application rate and accumulated amount. The impact of extra nitrogen on leaves C:N ratio was positively correlated with latitude, but negatively correlated with mean annual temperature and precipitation, nitrogen application rate, accumulated amount, duration and leaves C:N ratio of the control plots. Therefore, nitrogen enrichment caused by human activities will most likely alter element balance and alpine plants from nitrogen limitation to phosphorus limitation. This effect may weaken with time, and increase with climatic warming, increased precipitation and nitrogen input rate.

11

Influence of Branch Death on Leaf Nutrient Status and Stoichiometry of Wild Apple Trees (Malus sieversii) in the Western Tianshan Mountains, China

58%

Tao Y. , Nuerhailati M. , Zhang Y.-M. , Zhang J. , Yin B.-F. , Zhou X.-B.

Polish Journal of Ecology

|

2020

|

tom Vol. 68, nr 4

296--312

EN

The wild apple tree Malus sieversii is a tertiary relict species and a key ancestor of the commonly cultivated apple trees today. In recent years, many M. sieversii individuals have died or have severe dead branches. Whether branch death would lead to the change in nutrient stoichiometry of M. sieversii remains unclear. In this study, the nitrogen (N), phosphorous (P), and potassium (K) stoichiometric traits of M. sieversii individual trees with different proportion of dead branches divided into three classes (Class I [< 20%], Class II [40-60%], and Class III [> 80%]) during annual growth period, elemental scaling relations, and the possible influencing factors were systematically analysed. Leaf N, P, and K decreased during growing season, and N and P did not show significant differences among the three classes; however, the Class III wild apple trees had the lowest K contents in both photosynthetic and reproductive organs. Flowers had higher P and K contents than leaves, whereas fruits had low N content. The growth of M. sieversii was always limited by N due to low N:P ratio and N resorption efficiency. The scaling exponents of leaf N-P, N-K, or P-K among the three classes did not show any significant differences, revealing an inherent property of M. sieversii. Most soil variables showed weak correlations with leaf nutrient parameters (except for K). Precipitation and relative humidity, rather than temperature, showed significantly positive effects on leaf nutrients. These findings suggest that increasing water input and plant K content may be conducive to enhance the resistance and recovery ability of diseased wild apple trees.

12

Nutrient stochiometric relations and biogeochemical niche in coexisting plant species : effect of simulated climate change

58%

Penuelas J. , Sardans J. , Ogaya R. , Estiarte M.

Polish Journal of Ecology

|

2008

|

tom Vol. 56, nr 4

613-622

EN

Here we define a "biogeochemical niche" characterized by the species position in the multivariate space generated by its content not only of macronutrients like N, P or K, but also of micronutrients such as Mo, Mg and Ca, and trace toxic elements such as Pb and As. We then hypothesize that the flexibility of the species "biogeochemical niche" will influence the quality of plant tissue, which may have implications for herbivores, and will affect the species capacity to respond to disturbances and climate change and to adapt to the new climate conditions. We show with a simple multivariate procedure, a principal component analysis (PCA), first, that there is a strong differentiation in the total and relative (stoichiometry) content of the different elements in coexisting plant species, and, second, that there is species-specific plasticity in the response of this elemental composition to experimental climate change. The concentrations of foliar macro and micronutrients, as well as trace elements were measured in several tree species (Quercus ilex L., Phillyrea latifolia L. and Arbutus unedo L. in a Mediterranean broad leaf forest (Prades Mts) and in shrub species (Erica multiflora L., Globularia alypum L. and Dorycnium pentaphyllum Scop.) in a Mediterranean shrubland (Garraf Mts) in control plants and in plants grown in experimental drought and warming plots. The climate conditions were monitored during the period 1999-2005. During this period, in the Prades experiment the drought plots had on average a soil moisture content 9% lower than the control plots, whereas in the Garraf experiment the drought treatment led to a mean reduction in soil moisture of 21% and the warming treatment to 0.9 [degree]C rise. The species with greater changes in biogeochemical niche under increased warming or drought, Arbutus unedo, Erica multiflora and Globularia alypum, were those that were also more affected in growth, photosynthetic capacity and other eco-physiological traits. The species differentiations indicate a strong biogeochemical niche, and that the changes in biogeochemical niche are probably an underlying factor in community structure shifts.

13

On the defect structure of alkaline earth titanates.

58%

Komornicki S.

Inżynieria Materiałowa

|

1998

|

tom R. XIX, nr 4

819-822

EN

Nonstoichiometry in strontium titanate as an example of alkaline earth titanates was discussed in terms of Sr/Ti ratio and dopant concentration and extended defect existence. For some dopant concentrations and titanium or strontium excess a self-compensation of cation and anion vacancies could be observed, leading to unusual pressure dependencies of electrical conductivity.

14

Composition of guano produced by frugivorous, sanguivorous, and insectivorous bats

58%

Emerson J. K. , Roark A. M.

Acta Chiropterologica

|

2007

|

tom 09

|

nr 1

EN

Bat guano supports an assemblage of organisms that varies depending on the species of bat producing it. To determine whether these differences in community structure may be due to differences in guano composition, we analyzed guano from frugivorous (Pteropus rodricensis), sanguivorous (Desmodus rotundus), and insectivorous (Tadarida brasiliensis) bats. We found no differences among species in organic matter or lipid of guano. Desmodus guano contained more carbon (C) than Pteropus guano. The latter contained less nitrogen (N), and the former contained less phosphorous (P) than guano of the other two species. Pteropus guano had a higher C:N ratio, and Desmodus guano had higher N:P and C:P ratios than the other two species. These differences in guano composition suggest that guano from bats in different feeding guilds may affect ecosystem structure and dynamics differently.

15

Biomass fraction of graminoids and forbs in N-limited Alpine grasslands: N:P stoichiometry

58%

Zhang R. , Gou X. , Bai Y. , Zhao J. , Chen L. , Song X. , Wang G.

Polish Journal of Ecology

|

2011

|

tom 59

|

nr 1

EN

It is known that the dominance of graminoid species is promoted by N addition; however, there has been relatively little effort to examine the pattern induced by natural N fertility. Since nutrie nt use e fficiency (NUE) is an important trait determining plant competitive ability, we expected that the species guild with higher NUE (lower nutrient content) may be more competitive on infertile soils. We explo red t he relationships between relative forbs biomass share , soil N and productivity by the linear regressi on analysis on a natural alpine meadow in northeast of Qinghai- Tibetan Plateau (3600 m a.s.l.). To test the variety of leaf N:P stoichiometry, paired t test and general linear model multivariate (GLM) analysis were also used. We f ound that the leaf N:P ratios of the whole community were below 13 in studied sites, which may be consistent with the N limitation on the veget ation. Graminoids re tained lower concentrations of leaf N and P than forbs in community on the Nlimited grassland. Consistent with our prediction, we found that the biomass fraction of graminoids declined with soil N content and aboveground production on the grassland. Different from the pattern along fertility gradients induced by N fertilization, our results showed that gr aminoids with lower internal nutrient content w ere able to resist low levels of nutrient availability on the natural alpine grassland when compared to forbs.

16

Fuel saving index assessment on driving behavior control system of prototype model using neural network

58%

Munahar S. , Triwiyatno A. , Munadi M. , Setiavan J. D.

Archives of Transport

|

2022

|

tom Vol. 63, iss. 3

123--141

EN

Efficient fuel consumption in the world is essential in automotive technology development due to the increase in vehicle usage and the decrease in global oil production. Several studies have been conducted to increase fuel consumption savings, Fuel Cells (FCs), the application of alternative energy vehicles and the Engine Control Unit (ECU) system. FCs do not require oil energy to propel the vehicle, so this technology promises to reduce energy consumption and emissions. However, this research still leaves problems. FCs are susceptible to short circuit hazards, and ownership costs are very high. Alternative energy applications produce less power, less responsive acceleration, and insufficient energy sources to enter mass production. The ECU application still has an orientation toward achieving stoichiometry values, so the increase in fuel efficiency has the potential to be improved. Driving behavior is a variable that has a close relationship with fuel consumption efficiency. However, research on driving behavior is only studied for implementation in autonomous car-following technologies, safety systems, charging needs characteristic of electric vehicles, emission controls, and display images on invehicle information systems. Meanwhile, research on driving behavior as a control system to improve fuel efficiency has not been carried out. To that end, this study proposes the use of driving behavior for a newly designed control system to improve fuel efficiency. The control system in this research is a prototype model to be assessed using the Fuel Saving Index (FSI) analysis. An artificial neural network is used to help the recognition of driving behavior. The results showed that the newly designed control system was categorized on scale IV of FSI. On this scale, the power generated by the engine is quite optimal when it is in the eco-scheme driving behavior. The driving behavior control system can significantly improve the efficiency of fuel consumption. Air to Fuel Ratio (AFR) is achieved above the stoichiometric value.

17

Voltage activated ion channels formed by a synthetic alpha-helical peptide: - Determination of channel stoichiometry and molecular modelling of peptide conformation

58%

Mellor I. R. , Kerr I. D. , Sansom M. S. P. , Sukumar M. , Balaram P.

Cellular and Molecular Biology Letters

|

1996

|

tom 01

|

nr 3

EN

We designed and synthesized an 18 residue peptide (MS 18) similar to the channel forming fungal antibiotic alamethicin. MS18 formed ion channels in lipid bilayers exhibiting a low discrete conductance level of 55 pS and brief openings to many other conductance levels. Channel formation was markedly dependent on transbilayer voltage with macroscopic conductance increasing exponentially beyond an activation voltage. The activation voltage was higher for lower concentrations of peptide. The relationship between conductance, voltage and peptide concentration was used to calculate the mean number of peptide monomers forming the MS18 channel. This gave an estimate of 4 MS18 monomers per channel. Molecular modeling of MS18 revealed a predominantly α-helical structure.