Values Of Na Research Articles

Examination of ionoregulatory characteristics of South American cichlids

We examined ionoregulatory traits of four cichlid species from South America, oscars (Astronotus ocellatus), Tapajos cichlids (Geophagus sp.), Macmaster's dwarf cichlids (Apistogramma macmasteri), and keyhole cichlids (Cleithracara maronii), all inhabitants of ion-poor waters. Km values for Na+ transport in fish held in 100 μmol L−1 Na+ water ranged from 49 to 143 μmol L−1, and Jmax values spanned 450 to 1205 nmol g−1 h−1. After one month in 1000 μmol L−1 Na+ water, kinetic parameters for Na+ uptake in three of the four species acclimated, but only oscars displayed the “typical” pattern of higher Km and lower Jmax values. Low pH water inhibited Na+ uptake (JinNa) in all, and stimulated Na+ efflux (JoutNa) 2.5 to 3.5-fold in three of the four species. Oscars alone had had a measurable JinNa at pH 3.5 and no stimulation of JoutNa. We measured JinNa in oscars and keyhole cichlids during exposure to 100 μmol L−1 Ethoxzolemide (EZ), an inhibitor of carbonic anhydrase, and 1 mmol L−1 NH4Cl (HEA). EZ inhibited JinNa by about 50% and HEA reduced JinNa by 80–90%. These results suggest that Na+ uptake involves H+ extrusion. Acute exposure to 1 μmol L−1 CuSO4 and 60 nmol L−1 AgNO3 inhibited JinNa in both species by 30–85%. Exposure of oscars to 5-fold higher concentrations of both metals did not further inhibit JinNa, but it did stimulate JoutNa 50–150%. The response to metals of both species are similar to other species that have been examined.

Source rock weathering and groundwater suitability for irrigation in Purna alluvial basin, Maharashtra, central India

Purna alluvial basin is characterized by low to high level groundwater salinity having adverse effect in a large area, however, the basin still lacks one-time data of any season regarding hydrogeochemistry and quality assessment for drinking and irrigation purposes. The present work is aimed to determine various weathering indices and estimation of groundwater quality for irrigation purpose. The interpretations are based on the study of total 158 samples, collected from dug wells (60) and bore wells (98) during both pre- and post-monsoon periods of the year 2009. The plots between Ca+Mg vs. SO4+HCO3, Na vs. Cl and Na vs. HCO3 reveal that most of the samples fall below the equiline that indicates prevalence of silicate weathering. The USSL diagram (Wilcox diagram) demonstrates higher concentration of points in the fields of C2S1 and C3S1 for both the aquifers, indicating high salinity and low to medium sodium water; however, a few sample points positioned in C3S4 and C4S4 fields indicate high salinity but medium to high sodium. The values of Na%, RSC, Kelley ratio and magnesium ratio for most of samples exhibit doubtful to unsuitable categories of groundwater for irrigation from both the aquifers during pre- and post-monsoon periods. The vast data bank generated for entire basin is significant for government and non-government organizations for future planning and management.

Solving [formula omitted] in [formula omitted] with [formula omitted

Let Na be the number of solutions to the equation x2k+1+x+a=0 in F2n where gcd⁡(k,n)=1. In 2004, by Bluher [2] it was known that possible values of Na are only 0, 1 and 3. In 2008, Helleseth and Kholosha [13] found criteria for Na=1 and an explicit expression of the unique solution when gcd⁡(k,n)=1. In 2010 [14], the extended version of [13], they also got criteria for Na=0,3. In 2014, Bracken, Tan and Tan [5] presented another criterion for Na=0 when n is even and gcd⁡(k,n)=1.This paper completely solves this equation x2k+1+x+a=0 with only the condition gcd⁡(n,k)=1. We explicitly calculate all possible zeros in F2n of Pa(x). New criteria for which a, Na is equal to 0, 1 or 3 are by-products of our result.

A multidisciplinary approach for sustainable management of a complex coastal plain: The case of Sibari Plain (Southern Italy)

Coastal plain environments constantly adapt to change as a result of natural processes and increasing anthropogenic pressure, as in the case of the low relief Sibari coastal plain (Calabria, southern Italy). In order to reconstruct the hydrostratigraphic framework and explain the spatial distribution of groundwater salinization of the Sibari coastal plain, an integrated hydrogeological and geochemical approach was applied to support an accurate conceptualisation and modelling of the whole plain groundwater system. Litho-hydro-stratigraphic relationships were constructed from lithologic logs obtained from exploratory boreholes whereas, the groundwater flow system has been studied using conventional hydrogeological field investigations, hydrochemistry, and isotope hydrology. Three distinct Hydrological units (HU3-shallow aquifer, HU2 aquitard and HU1-lower aquifer) were identified showing distinct geometrical, hydrochemical and isotopic signatures. With the aim of explain the origin of Na-Cl, Ca-Cl and Na-HCO 3 waters were considered the role of ion exchange processes. The results demonstrate that values of Na + , Mg 2+ , Cl and SO 4 can be attributed to seawater intrusion, where K + is probably the major pollutant of the shallow aquifer. The adopted multidisciplinary approach provides an effective tool for accurately determination of groundwater processes and can be useful for a sustainable management of water resources in coastal plain. The physically based model of the pail groundwater system was able to explain the observed groundwater salinity variations and to support a detailed long-lasting numerical simulation of variations in the quantity and quality of groundwater resources. • Hydrostratigraphy related to Quaternary coastal plain evolution. • Groundwaters are affected by salinization and freshening phenomena. • Numerical simulations show groundwater qualitative and quantitative degradation.

Interpretation of storage and retrieval major-ion chemistry, with emphasis on significant sulfate and sodium concentrations in the White River watershed, northwestern Nebraska, United States

The White River watershed encompasses four major tributaries within a basin area of 130 km2 (1595 mi2) in extreme northwestern Nebraska. An examination of the historical (1968–1975) aqueous geochemistry data (major cations and anions and total dissolved solids [TDS]) supplied by the Nebraska Department of Environmental Quality revealed that the TDS is relatively low (130–1200 mg/L), excluding Big Cottonwood Creek (BCC), with a basin-wide median of 340 mg/L. The median TDS for the BCC is 1880 mg/L (brackish); the median values for Na and SO4 are 385 and 897 mg/L, respectively. Mineralization in the river increases steadily downstream. The scatter plots of meq/L concentrations for selected anions and cations reveal the impact of silicate mineral (e.g., feldspar) weathering on the aqueous geochemistry throughout the watershed. These ubiquitous feldspar minerals most likely originated along the eastern slope of the Front Range during the Late Cretaceous and Tertiary (Laramide orogeny). Twenty-nine samples for three White River stations and the BCC exceed the US Environmental Protection Agency secondary maximum contaminant levels for TDS and/or SO4 in drinking water supplies at 500 and 250 mg/L, respectively. Uncontaminated streams that drain marine shales (typically containing S-bearing minerals) nationwide typically show an excess of Na and a deficiency of Ca and Mg. This is due in part to cation exchange of Ca in solution for Na on clay minerals. Consequently, the weathering of shale terrains commonly produces an Na-SO4 brackish surface-water runoff as is the case with BCC, which drains the Pierre Shale hills.

Desalination and heavy metal ion removal from water by new ion exchange membrane modified by synthesized NiFe2O4/HAMPS nanocomposite

Magnetic nickel ferrite (NiFe2O4) nanoparticles were synthesized and then modified by a novel hydrogel based on 2-acrylamido-2-methyl propane sulfonic acid (HAMPS). Field emission scanning electron microscopy (FE-SEM), X-ray diffraction (XRD), and Fourier-transform infrared spectroscopy (FTIR) analyses were conducted to prove the NiFe2O4/HAMPS nanocomposite formation decisively. The effect of NiFe2O4/HAMPS in the matrix of the heterogeneous cation exchange membrane on separation performance was studied. Adding of NiFe2O4/HAMPS into the membrane body up to 1%wt resulted in an increase of sodium flux obviously. The sodium flux showed a decreased trend at higher nanocomposite ratios slightly. Membrane potential, permselectivity, and transport numbers also showed improving trends. Results exhibited more value for Na+ dynamic transport numbers compared to static ones. Membrane water content and porosity increased from 13.07 to 27.7% and 9.6 to 20.2% by utilizing NiFe2O4/HAMPS, respectively. By adding NiFe2O4-HAMPS into the membrane structure a pronounced improvement in membrane mechanical resistance (~ 94%) and chemical stability was observed. Modified membrane containing 1.0%wt NiFe2O4-HAMPS showed effective separation in Pb2+ (~ 98%), Cu2+ (~ 48%), and Ni2+ (~ 34%) removal. This sample also showed highest current efficiency (78.9%) in Pb2+ removal and lowest energy consumption (6.97 W/mol) compared to others.

English

Spermidine (Spd) is one of the most important polyamines (PAs) showing important roles in growth, development and stress responses in plants. The role of Spd in regulation of a dominant glutathione S-transferase (GST, E.C.2.5.1.18) and ionic balance of Na+ and K+ in onion leaves were examined. Onion GSTs were separated from fresh bulb tissue using DEAE-cellulose chromatography. Three GSTs were eluted at 56, 120 and 169 mM of KCl. Among them, GST2 containing >60% of total activity was termed as dominant GST and it was subsequently purified using affinity chromatography S-hexylglutathione-agarose. This purified protein was used for western blotting analysis of the GST in leaves of two months onion seedlings imposed on NaCl induced 16 dSm-1 salinity with or without foliar spray of 100 µM Spd on 1st, 3rd, 5th and 7th days of stress. The results suggested that dominant GST accumulated by salinity in onion seedling with or without Spd spray. However, at early saline stress, accumulation was significantly stronger in leaves without Spd than in those with Spd. At 7th day, GST band was increased and apparently seemed to be intensified in Spd sprayed leaves than those without spray. The values of Na+/K+ suggested that Spd maintained ionic balance better at early stage of stress than late stage.   Key words: Onion glutathione S-transferases (GST), ionic balance, salt stress, spermidine.

Health Risk Associated with Some Trace and Some Heavy Metals Content of Harvested Rainwater in Yatta Area, Palestine

Rainwater is considered a dependable source for domestic purposes within rural areas in Palestine. Harvested rainwater stored in cisterns is used to leverage deficits from municipal water supplies. Harvested rainwater in areas surrounded with industrial and agricultural activities is usually contaminated with heavy and trace metals. To study the effects of human exposure to heavy and trace metals, 74 harvested rainwater samples of rain-fed cisterns were collected from different localities in the Yatta area of Palestine in the months of January and February of 2016. The water samples were analysed for Ca, Mg, Al, Fe, K, Na, Ag, Li, Co, Ba, Bi, Sr, Ga, V, Rb, Mo, Beand Tl elements utilizing ICP-MS (inductively coupled plasma mass spectrometry). The selected trace metals were found within the concentration limits of the acceptable values, in accordance with WHO and Palestinian standards, except for K and Al, which were found above the allowed limits. The potential risks of the selected trace metals on the health of the local residents, as well as the possible sources of such heavy metals, were also studied. The Chronic daily intake (CDI) of each metal and health risk indexes (HRI) were calculated for both adults and children residents. The oral ingestion pathway was studied, including exposure via drinking water. The values for CDI were found in the descending order of: Ca > Mg > Na > K > Sr > Fe > Al > Ba > Li > V > Rb > Ag > Mo > Ga > Co > Bi > TI > Be. The values of HRI were below 1 for most of the selected heavy metals, expect for Li for children, indicating potential health risk. The study also predicted that the local residents have a higher chance of developing cancer in their lifetime, especially children, with respect to the carcinogenic risk (CRing) values for Na, Mg, Al, Ba, K, Ca, Fe and Sr, which were greater than standardized limits (>10−6). The rest of the selected elements were within the acceptable limit in the five different studied locations. Furthermore, univariate, multivariate and statistical analysis depending on one-way ANOVA, inter-metal correlation, cluster analysis (CA) and principal component analysis (PCA) results revealed that geogenic and anthropogenic activities were major sources of drinking water contamination by heavy metals in the Yatta area.

To the issue of the use of sodium-lithium countertransport rate in red cell membrane as a prognostic marker of artherial hypertension mordbidity and mortality: an experience of 25-year follow up cohort study

Aim. The article discusses the results of a long-term cohort study devoted to the search for the possible relationship of arterial hypertension morbidity and mortality with the rate of sodium-lithium countertransport (Na+-Li+-СT) in red cell membrane which is a marker of the structural and functional state of the cell membrane.
 Methods. The study of the functional state of cell membranes by determining the maximal rate of Na+-Li+-CT in red cell membrane with quintiles analysis of the rate of Na+-Li+-CT. Screening clinical examination, including registration of blood pressure (BP), ECG study, the study of eyeground vessels, one- and two-dimensional echocardiography (EchoCG), the study of the lipid spectrum of the blood. Analysis of medical records.
 Results. Based on the results of long-term follow up of the aging cohort total mortality is not associated with Na+-Li+-СT rate in red cell membrane. At the average age of 50 bimodality is detected in the development of new cases of primary arterial hypertension associated with the values of Na+-Li+-СT rate of the 1st quartile (36-206 micromoles of Li per liter of cells per hour) and 3d quartile (276-347 micromoles of Li per liter of cells per hour). At the average age of cohort of 55.6±6.7 years the distribution of patients with arterial hypertension by quartiles of Na+-Li+-СT rate becomes almost identical with the statistically non-significant prevalence of 4th quartile of Na+-Li+-СT rate.
 Conclusion. The expected correlation between mortality among persons with hypertension and membrane disorders determined by the high rate of Na+-Li+-СT was not revealed. However, the tendency to the predominance of mortality at high Na+-Li+-СT rate suggests that with a much larger sample size a significant relationship may be confirmed. The necessity of studying the relationship between mortality from arterial hypertension and high rate of Na+-Li+-СT in female cohorts remains actual. Increasing difference of mortality rate among patients with and without arterial hypertension with high rate of Na+-Li+-СT can indicate the relationship between mortality from arterial hypertension and membrane disorders.

Genetic variability and relationships among Salvia ecotypes/species revealed by TRAP-CoRAP markers

In this study, target region amplification polymorphism (TRAP) and conserved region amplification polymorphism (CoRAP) markers were used for genetic diversity and relationship analysis of 25 Salvia ecotypes/species. Twelve TRAP and CoRAP primer combinations (four arbitrary primers and three fixed primers from Salvia miltiorrhiza expressed sequence tag sequences) amplified 180 loci, of which all were polymorphic. The obtained high average PIC and MI values revealed high capacity of TRAP and CoRAP primers to detect polymorphic loci among Salvia species. TRAPs and CoRAPs had similar efficiency in detecting polymorphisms with excellent ability to differentiate the closely related Salvia ecotypes. Based on both TRAP and CoRAP data, tetraploid Salvia virgata (2n = 4x = 32) showed the highest values for Na (1.17, 1.29), Ne (1.29, 1.35), Shannon index (0.26, 0.32) and heterozygosity (0.172, 0.212) in all 11 studied species. The Nei’s genetic distances with TRAPs and CoRAPs ranged from 0.23 to 0.69 and 0.19 to 0.64, respectively. The tree pattern based on combined CoRAP + TRAP data with the neighbour joining method clustered 25 Salvia species/ecotypes into five major groups that showed good alignment with the population structure analysis results. In both TRAPs and CoRAPs data analysis of molecular variance (AMOVA), the estimated variance within Salvia species was greater than that among Salvia species.

Two-Dimensional GaN: An Excellent Electrode Material Providing Fast Ion Diffusion and High Storage Capacity for Li-Ion and Na-Ion Batteries.

Identifying applicable anode materials is a significant task for Li- and Na-ion battery (LIB and NIB) technologies. We propose the GaN monolayer (2D GaN) can be a good anode candidate. The GaN monolayer manifests stable Li/Na adsorption and inherently low theoretical voltages. Most excitingly, both high storage capacity and extremely fast Li/Na diffusion can be simultaneously realized in the GaN monolayer. For Li, the storage capacity and diffusion barrier is 938 mA h g-1 and 79 meV, respectively. And, the values for Na are 625 mA h g-1 and 22 meV. Compared with known two-dimensional (2D) anode materials with similar scale of ion diffusion barriers, the GaN monolayer almost possesses the highest Li/Na storage capacity discovered to date. Our work suggests that the 2D GaN is a prospective anode material offering fast ion diffusion and high storage capacity.

MAPPING OF SALT WATER INTRUSION DURING THE DRY AND WET SEASONS IN THE FIRST COASTAL AQUIFER OF TUMPAT KELANTAN, MALAYSIA

The most prominent threats to the main water resource in north east Kelantan, is the intrusion of salt water especially in the second aquifer and part of the third aquifer. The main purpose of this work was to evaluate the salt water intrusion into the first aquifer. It was investigated using physical and chemical characteristics of ground water, which revealed that. A range of pH from 4.95 7.63, electrical conductivity (EC) 70 ̶ 2561 µs/cm, salinity 0.02 ̶ 1.21, and total dissolved solids 0.025 ̶ 1.73 mg/l. A range of calcium (Ca), sodium (Na), chloride (Cl) and sulfate (SO4) 1.51 ̶ 37.41, 2.11 ̶ 78.92, 2.84 ̶ 575.2 and 0.92 ̶ 172.82 mg/L respectively. The values of Na, Ca, SO4, Cl and EC were decrease gradually from the sea towards inland and vice versa. A variation in ground water levels between the dry and wet seasons which were in the range of 0.2 ̶ 1.97 m. Moreover, the freshwater/saltwater interface was located on the shoreline in the dry season and retreated in the wet season. Generally, the salt water intrusion was discovered in the first coastal aquifer; however, it has affected a small area. The ground water in this aquifer is fresh (except the three wells 11, 19 and 20) that considered as salty due to the high average of chloride, salinity, total dissolved solids, and electrical conductivity.

Changes in electrolytes levels in the plasma of <i>Clarias gariepinus</i> juveniles and adults reared in two grow-out facilities

Variations of some electrolytes such as Sodium (Na+), Potassium (K+), Chloride (Cl-) and Calcium (Ca2+)in the plasma of Clarias gariepinus juveniles and adults reared in grow-out concrete tanks and earthen ponds in three Agricultural Zones of Lagos State were assessed to determine the levels of osmotic impairment in fish raised using two grow-out aquaculture facilities. A total of six farms and a control farm were selected for the study based on their culture systems and production capacities (earthen ponds and concrete tanks). Sixty-four blood samples were collected from juveniles and adults of catfish reared in these farms for six months. Blood samples were analyzed by standard laboratory methods using Randox diagnostic test kit. Results from the electrolytes analyses indicated that the values of Na+ and K+ ions significantly increased (P < 0.05) in all the farms when compared to the control values. However, there was no significant difference (P > 0.05) in Cl- between the control and other farms. While significant reduction (P < 0.05) of Ca2+ were recorded in other farms when compared to the control. These alterations were more noticeable in the fish reared in MOY and TEM fish farms than other farms.Keywords: Aquaculture, stress, electrolytes, culture systems, catfish

Hypermagnesuria in Humans Following Acute Intravenous Administration of Digoxin

Background: Hypomagnesemia is a known predisposing condition for the appearance of digitalis toxicity. The detection of a genetic form of Mg urinary wasting with hypomagnesemia being caused by a mutation in the γ subunit (FXYD2) of the Na,K-ATPase, the pharmacological target of Digoxin, prompted us to investigate whether Digoxin administration increases urinary Mg excretion. Methods: Two groups of subjects, with rapid atrial fibrillation, received intravenous Digoxin (n = 9) or verapamil (n = 8), for heart rate control. During the following 4 h, blood and urinary creatinine, sodium, potassium, calcium, and magnesium levels were determined, and fractional excretion (Fex) values for Na, K, Ca, and Mg were calculated. Results: In the Digoxin group, at 60 min Fex Mg rose from 3.07 ± 1.21 to 7.58 ± 2.51% (an increase of 269 ± 107% of baseline, p < 0.001), and at 240 min to 6.05 ± 2.30% (204 ± 56% of baseline, p < 0.01). No significant change was observed for Fex Na, Fex K, and Fex Ca. A striking correlation was found between individual values of Fex Mg and serum Digoxin concentration (r = 0.678, p < 0.0001). No significant correlation was found between Fex Na or Fex K and serum Digoxin. A correlation of borderline significance was found between Fex Ca and serum Digoxin (r = 0.349, p = 0.073). Conclusions: The hypermagnesuric effect of acute Digoxin treatment is reminiscent of the effect of the missense mutation in FXYD2, which assumes that FXYD2 is a positive regulator of Na,K-ATPase in the distal convoluted tubule (DCT). The borderline calciuric effect of Digoxin may point to an additional site of action, more proximal to the DCT, that is, the thick ascending limb.

The sensitivity of Na+, K+ ATPase as an indicator of blood diseases.

Blood-related hereditary diseases are widespread in Eastern and SouthWestern regions of Saudi Arabia until recently. In this study, we used Na+, K+ATPase as an enzymatic indicator for the diagnosis of the diseases. Individuals with different blood diseases (iron deficiency (n=13), anemia (n=14), thalassemia (n=16) and sickle cell anemia (n=12) were studied for Na+, K+-ATPase activity in the plasma membrane of red blood cell and compared with those of the healthy ones (n=20) of the same age and gender living in Jeddah, Saudi Arabia. There was a significant elevation in the specific activity of Na+, K+ATPase in individuals with anemia compared with those of control (0.0094 + 0.001 nmol / mg protein/min versus 0.0061 ± 0.001). On the other hand, there was a significant reduction in enzyme activity in thalassemia (0.0028 ± 0.002 nmol / mg protein/min) and sickle cell anemia cases (0.0042 ±0.001 nmol / mg protein/min) compared to the control group. The cut off value for Na+, K+ATPase activity is 0.005 µmol Pi/min-showing 94% sensitivity and 93% specificity for the differentiation of blood abnormality. It can be recommended that the activity of Na+, K+-ATPase can be used for the diagnosis of individuals with blood diseases/disorders.

Realization of the kilogram by the XRCD method

When the kilogram is redefined in terms of the fixed numerical value of the Planck constant h, the x-ray-crystal-density (XRCD) method, among others, is used for realizing the redefined kilogram. The XRCD method has been used for the determination of the Avogadro constant NA by counting the number of atoms in a 28Si-enriched crystal, contributing to a substantial reduction of uncertainty in the values of NA and h to 2 parts in 108. This method can be therefore used reversely for the mass determination of a 1 kg sphere prepared from the crystal. This is realized by SI-traceable measurements of its lattice parameter, isotopic composition, volume, and surface properties. Details of the corresponding measurements are provided, as well as the concept of the XRCD method, isotope enrichment, crystal production, sphere manufacturing, and evaluation of impurities and self-point defects in the crystal, together with mass comparison with respect to the silicon sphere for disseminating mass standards.

Variations on Soil Salinity and Sodicity and Its Driving Factors Analysis under Microtopography in Different Hydrological Conditions

Over three million hectares of salt-affected soils characterized with high salinity and sodicity caused serious land degradation in Songnen Plain, northeast China. Soil salinity–sodicity heterogeneous distribution under microtopography is usually influenced by several environmental factors. The side direction movement of soil water driven by water from depression is the key factor that aggravates the soil salinization under microtopography in dry condition. In this study, the differences in surface soil salinity–sodicity (0–10 cm) between dry year and wet year were compared, and the relationship between soil salinity–sodicity and environment factors such as ground elevation, surface ponding time, surface ponding depth, and soil moisture at four soil layers (0–10, 10–30, 30–60, and 60–100 cm) were analyzed using redundancy analysis (RDA) and simple correlation analysis (Pearson analysis) for two different hydrological years. Analyzed soil salinity–sodicity parameters include soluble ions (Na+, K+, Ca2+, Mg2+, CO32−, HCO3−, Cl− and SO42−), salt content (SC), electrical conductivity (EC), sodium adsorption ratio (SAR), and pH. Results showed that values of SAR, Cl−, and SO42− were significantly higher in dry year than in wet year, while Ca2+, Mg2+, K+, and HCO3− showed the opposite results. Values of Na+, CO32−, and EC were significantly higher at higher ground elevation gradient (20–40 cm) in dry year than wet year. Redundancy analysis indicated that spatial distributions and variations of salinity and sodicity in surface soil layer were related with environmental factors of ponding depth, ponding time and ground elevation in wet year, and they were related with ground elevation, ponding depth, ponding time, and soil moisture at 30–60 and 60–100 cm soil layer in dry year. Ponding depth and ground elevation rank first and second as the influential factors of the spatial distribution and variation of soil salinity–sodicity in wet year. However in dry year, primary and secondary influential factors are ground elevation and soil moisture at 60–100 cm soil layer.

Key factors dominating the neural coding preference to 1/f signal

Experiments have demonstrated that cortical and sensory neurons prefer to response to signals with characteristics of long-term correlation or 1/f noise feature better than signals with no correlation like white-noise-type [1]. In order to study the underlying mechanism, we built up a cortical neuronal model [2] based on Hodgkin-Huxley theory to study the correlations between neuron kinetics and signal statistics. Interestingly, we observed that (see Figure 1a,b) white-noise-type signal (cutoff frequency >10000Hz) is hard to induce action potentials unless signals with very strong intensity while 1/f signal and low-pass filtered white noise type signal (cutoff frequency <1000Hz) can easily induce action potentials with high firing rate at low signal intensity (quantified by signal standard deviation STD), see Figure ​Figure1a.1a. Moreover, the half-height duration of action potentials is also varying with more sensitivity to 1/f signal or filtered white noise than pure white noise (Figure ​(Figure1b).1b). In addition, neural firing rate and spike duration are more sensitive to 1/f signal than filtered white noise. This is a clear positive evidence of neuronal coding preference to signals with long-term correlations. Figure 1 Interactions among neuron kinetics and signal statistics. a) Firing rate vs signal STD for white noise, filtered white noise and 1/f noise. b) Half-height duration of action potentials vs signal STD for white noise, filtered white noise and 1/f noise. ... To further reveal the key factors dominating the preference of neuronal dynamics to colored and white noise, we systematically varied the values of Na+ and K+ channel time constants and channel rate constants. Figure ​Figure1c1c showed that the firing rate doesn't change much as a function of sodium activation time constant (τm) for a given 1/f signal (STD = 1). However, the firing rate decrease dramatically with an increase of sodium inactivation time constant (τh) or potassium activation time constant (τn) for this signal. For very large τh and τn, neuronal response dynamics start to be saturate for all signals, see Figure ​Figure1d.1d. These results indicate that both sodium inactivation time constant (τh) and potassium activation time constant (τn) may be the key factors dominating neural coding preference to signals with different correlated statistic features. In sum, this study demonstrated that ionic channel time constant of sodium inactivation and potassium activation may be the dominating factors accounting for the neuronal spiking sensitivity favorable to signals with temporal correlations.

Evaluating genetic diversity and constructing core collections of Chinese Lentinula edodes cultivars using ISSR and SRAP markers.

Genetic diversity among 89 Chinese Lentinula edodes cultivars was analyzed by inter-simple sequence repeat (ISSR) and sequence-related amplified polymorphism (SRAP) markers. A 123 out of 126 ISSR loci (97.62%) and 108 out of 129 SRAP loci (83.73%) were polymorphic between two or more strains. A dendrogram constructed by cluster analysis based on the ISSR and SRAP markers separated the L. edodes strains into two major groups, of which group B was further divided into five subgroups. Clustering results also showed a positive correlation with the main agronomic traits of the strains, and that strains with similar traits clustered together into the same groups or subgroups in most cases. The average coefficient of pairwise genetic similarity was 0.820 (range: 0.576-0.988). Compared to the wild strains, Chinese L. edodes cultivars indicated a lower level of genetic diversity. Two preliminary core collections of L. edodes, Core1 and Core2, were established based on the ISSR and SRAP data, respectively. Core1 was constructed by the advanced M (maximization) strategy using the PowerCore version 1.0 software and contained 21 strains, whereas Core2 was created by the allele preferred sampling strategy using the cluster method and contained 18 strains. Both core collections were highly representative of the genetic diversity of the original germplasm, as confirmed by the values of Na (observed number of alleles), Ne (effective number of alleles), H (Nei's gene diversity) and I (Shannon's information index), as well as results of principal coordinate analysis. The loci retention ratio of Core1 (99.61%) was higher than that of Core2 (97.65%). Moreover, Core1 contained strains with more types of agronomic traits than those in Core2. This study builds the basis for further effective protection, management and use of L. edodes germplasm resource.

Evaluation of elemental quantitative values of atmospheric aerosol samples by PIXE method

In order to evaluate the quantitative values of atmospheric aerosol samples collected on filters, we investigated the effects of filter collection conditions (non-uniformity of collected particles) on analytical values and compared the quantitative values by means of PIXE and ICP-MS, using as the analytical sample PM2.5 collected on filters in a monitoring survey of atmospheric fine aerosol over the Kanto area of Japan in summer 2013. The results were as follows: (i) With respect to the uniformity of filter collection, differences in concentrations were seen for S and Cl as well as elements thought to originate in soil (Al, Si, Ti and Fe) depending on the analysis point, suggesting that collection of sulfate particles, chloride particles, and soil particles on filters was not uniform. (ii) According to a comparison of quantitative values yielded by PIXE and ICP-MS, ICP-MS values were lower than PIXE values for Mg, Al, Si, Ti and Fe, with Mg and Si being markedly lower. On the other hand, ICP-MS values were higher than PIXE values for Na, K, Ca and Zn. (iii) According to the results of measurement of NIST reference material and PM2.5 samples by means of PIXE and ICP-MS, Mg, Al, Si, Ca, Ti, Fe and Zn showed the same tendency. However, Na and K were opposite.