Application Of Na Research Articles

Cover Crops Affect Soil Mineral Nitrogen and N Fertilizer Use Efficiency of Maize No-Tillage System in the Brazilian Cerrado

Cover crops in no-tillage systems may alter soil mineral N and influence the N fertilizer use efficiency (NFUE) of subsequent maize. The hypothesis of this work is that no-tillage systems with cover crops affect nitrate, ammonium and maize NFUE in the Brazilian Cerrado. The objective was to evaluate the cover crop mineralization effect on soil N mineral and maize NFUE in a no-tillage system, with and without N topdressing. The experiment was arranged in a randomized block split-plot design. The plots were represented by cover crops (Cajanus cajan, Crotalaria juncea, Raphanus sativus and Mucuna aterrima). The subplots consisted of the application (WN) or non-application (NN) of N topdressing to maize. The soil was sampled in six layers (up to 60 cm) at the end (April) and at the beginning of the rainy season (November). NH4+ was lower for all cover crops and WN and NN management in April. NO3− differed between seasons and cover crops in WN and NN. The lignin concentration and N uptake of M. aterrima were the highest compared to other species. The highest NFUE was on R. sativus, showing higher fertilizer dependency. In a no-tillage system with cover crops, the N topdressing fertilization needs to be improved, considering mineralization.

Application of Na2CO3 as a Sacrificial Electrode Additive in Na‐ion Batteries to Compensate for the Sodium Deficiency in Na2/3[Fe1/2Mn1/2]O2

AbstractOwing to their high discharge capacities, P2‐type transition metal layered oxides have attracted attention for use as positive electrode materials in Na‐ion batteries. However, owing to the Na‐deficient compositions of these oxides, additional Na+ must be supplied using a Na‐metal negative electrode to attain a high capacity in a half‐cell configuration. In this study, solid Na2CO3 powder was introduced into the P2−Na2/3Fe1/2Mn1/2O2 composite positive electrode as a sacrificial salt to compensate for the Na deficiency. Na+ was supplied through the electrochemical oxidative decomposition of Na2CO3 during the initial charging process; the decomposition mechanism responsible for this process was investigated in detail. Online electrochemical mass spectrometry confirmed that Na2CO3 was oxidatively decomposed in combination with the decomposition of the ethylene carbonate electrolyte. This reaction produced CO2, wherein the carbon source was derived from both Na2CO3 and the electrolyte. Consequently, Na+ supplementation improved the reversible capacity of the Na‐ion full cell. This study offers practical insights and a mechanistic understanding of the pre‐doping technique for Na‐free negative electrodes. This approach also compensates for the irreversible reductive capacity in a process that can be easily applied to practical sodium‐ and lithium‐ion batteries and capacitors.

Effects of soil physicochemical environment on the plasticity of root growth and land productivity in maize soybean relay strip intercropping system.

Soil is a key foundation of crop root growth. There are interactions between root system and soil in multiple ways. The present study aimed to further explore the response of root distribution and morphology to soil physical and chemical environment under maize (Zea mays L.) soybean (Glycine Max L. Merr.) relay strip intercropping (MS) An experiment was carried out aiming to examine the effects of nitrogen (N) applications and interspecific distances on root system and soil environment in MS. The two N application levels, referred to as no N application (NN) and conventional N application (CN), were paired with different interspecific distances: 30, 45 and 60 cm (MS30, MS45 and MS60) and 100 cm of monoculture maize and soybean (MM/SS100). The results demonstrated that MS45 increased the distribution of soil aggregates (> 2 mm) near the crop roots and maize soil nutrients status, which increased by 20.3% and 15.6%. Meanwhile, MS reduced soil bulk density, increased soil porosity and improved soil oxygen content. Optimization of the soil environment facilitated root growth. The MS45 achieved a better result on root distribution and morphology than the other configuration and also increased land productivity. Relay intercropped soybean with maize in interspecific row spacing of 45 cm, improved soil physicochemical environment, reshaped root architecture and optimized root spatial distribution of crops to achieve greater land productivity. © 2024 Society of Chemical Industry.

Enthalpy‐Driven Room‐Temperature Superwetting of Liquid Na–K Alloy as Flexible and Dendrite‐Free Anodes

AbstractSodium (Na) metal anodes are promising candidates for various batteries with high energy density and high‐power density, however, the dendrite growth of Na metal is impeding their practical applications. The binary alloy Na–K is in the liquid state at room temperature with a wide composition range, which renders it inherently free from solid dendrite growth. Whereas the application of Na–K alloy is plagued by the lack of a wettable matrix to immobilize the liquid metal. Herein, a facile method is reported to introduce oxygen‐rich functional groups into carbon fiber cloth (O‐CFC), which is initially Na–K phobic yet turns into superwetting after the treatment. The superwetting behavior of the O‐CFC can be attributed to the favorable enthalpy changes as a result of the introduction of O‐rich functional groups. The superwetting property of the O‐CFC exhibits good universality, which can be extended to melting Na and K metals. By adopting the superwetting O‐CFC as a host for liquid Na–K alloy, the liquid metal can be well retained in the matrix and deliver a stable cycling for >1600 h. The concept of enthalpy‐driven wettability regulation can be enlightening for the host material design of other liquid metals and alloys.

Growth changes of tomato seedlings responding to sodium salt of α-naphthalene acetic acid and potassium salt of fulvic acid

In present study, sodium salt of α-naphthalene acetic acid (NA), potassium salt of fulvic acid (KF) and their combinations were applied to the growth substrates of tomato seedlings (Solanum lycopersicum L.) under chilling stress. The changes in aboveground biomass, root attributes, pigment contents, chlorophyll fluorescence, photosynthesis, osmotic regulation substances, and antioxidant enzymes activity of the tomato seedlings in response to NA and KF were investigated. The application of NA, KF and their combination could promote the growth of plant height and stem diameter of tomato seedlings under chilling stress to varying degrees, and improve root characteristics by increasing root volume, root length and root activity, and increase dry matter accumulation. In addition, the combined use of NA and KF improved the seedling leaf chlorophyll content, qP, Fv/Fm, ΦPSII , Pn and increased the activity of antioxidant enzymes in the tomato plants. The above results suggested a synergistic effect between NA and KF to stimulate the seedlings growth and to enhance the ROS scavenging ability of tomato, which has never been reported in previous research before. However, further researches are needed to explore the physiological and molecular mechanism underlying the synergistic effect between NA and KF.

A Simple and Efficient Way to Directly Synthesize Unsolvated Alkali Metal (M = Na, K) Salts of [CB11H12

Alkali metal (M = Na, K) salts of the [CB11H12]− anion have attracted increasing attention in many fields such as catalysis and all-solid-state batteries. However, tedious and low-yielding synthetic methods have seriously limited their application in these fields. We developed a facile method for the direct synthesis of the unsolvated potassium and sodium salts of the [CB11H12]− anion in 66% and 68% yields, respectively, by reactions of Na[B11H14] with NaH/NaHMDS (sodium bis(trimethylsilyl)amide), CF3SiMe3 in THF and K[B11H14] with KH, CF3SiMe3 in DME. This method avoids the exchange of cation and significantly simplifies the reaction setup, thus enabling convenient large-scale synthesis. It is believed that this method will support further application of Na[CB11H12] and K[CB11H12] as solid electrolytes for an all-solid-state battery.

The Role of Citrate Homeostasis in Merkel Cell Carcinoma Pathogenesis.

Simple SummaryMerkel cell carcinoma (MCC) is a rare but highly aggressive skin cancer. Despite important progress, overall understanding of the events that drive MCC carcinogenesis remains incomplete. We discovered that the plasma membrane citrate transporter (pmCiC) is upregulated in Merkel cell carcinoma cell lines. Cancer cells import extracellular citrate via pmCiC to support their metabolism, which is critical to support proliferation and metastatic spread. In this study, we show that inhibition of pmCiC can decrease the growth rate of Merkel cell carcinoma cell lines. Targeting pmCiC and thereby the tumor metabolism should be considered further as a potential anti-cancer therapy.Merkel cell carcinoma (MCC) is a rare but highly aggressive tumor of the skin with a poor prognosis. The factors driving this cancer must be better understood in order to discover novel targets for more effective therapies. In the search for targets, we followed our interest in citrate as a central and critical metabolite linked to fatty acid synthesis in cancer development. A key to citrate uptake in cancer cells is the high expression of the plasma membrane citrate transporter (pmCiC), which is upregulated in the different adenocarcinoma types tested so far. In this study, we show that the pmCiC is also highly expressed in Merkel cell carcinoma cell lines by western blot and human tissues by immunohistochemistry staining. In the presence of extracellular citrate, MCC cells show an increased proliferation rate in vitro; a specific pmCiC inhibitor (Na+-gluconate) blocks this citrate-induced proliferation. Furthermore, the 3D in vivo Chick Chorioallantoic Membrane (CAM) model showed that the application of Na+-gluconate also decreases Merkel cell carcinoma growth. Based on our results, we conclude that pmCiC and extracellular citrate uptake should be considered further as a potential novel target for the treatment of Merkel cell carcinoma.

Nitrogen application improved peanut yield and nitrogen use efficiency by optimizing root morphology and distribution under drought stress

Drought stress and nutrient deficiency are two main factors that restrict the growth and yield of peanut (Arachis hypogaea L.) in arid and semi-arid regions. However, the effects of N fertilizer on root growth and pod yield of peanut under different water conditions are unclear. The growth, root morphology, and pod yield of peanut were studied under different water and N combinations. Two soil water treatments were tested: Well-watered (WW, 80%-85% field capacity) and drought stress conditions (DS, 55%-60% field capacity). Three N treatments were tested: no N application (NN), moderate N (MN, 90 kg ha-1), and high N (HN, 180 kg ha-1). Results showed that pod yield of peanut was limited by drought and N deficiency. Compared with NN, peanut shoot DM and pod yield were improved by MN under DS, with an average increase range of pod yield of 16.2% in the 2 yr. The annual average root length density (RLD) in the deeper soil layer (40-100 cm) was 5.5% higher under DS-MN than DS-NN treatment. The N use efficiency (NUE) was 12.3% higher under WW than DS treatment, and the NUE of MN was significantly higher than that of HN under different water treatments. Root lengths in 40-60 and 60-80 cm soil layers were also positively correlated with pod yield (r = 0.66** and 0.47**, respectively) and NUE (r = 0.60* and 0.85**, respectively). In this study, root growth in deeper soil was improved by MN application under DS, thus increasing yield and NUE of DS conditions.

Lithium administered to pregnant, lactating and neonatal rats: entry into developing brain

BackgroundLittle is known about the extent of drug entry into developing brain, when administered to pregnant and lactating women. Lithium is commonly prescribed for bipolar disorder. Here we studied transfer of lithium given to dams, into blood, brain and cerebrospinal fluid (CSF) in embryonic and postnatal animals as well as adults.MethodsLithium chloride in a clinically relevant dose (3.2 mg/kg body weight) was injected intraperitoneally into pregnant (E15–18) and lactating dams (birth-P16/17) or directly into postnatal pups (P0–P16/17). Acute treatment involved a single injection; long-term treatment involved twice daily injections for the duration of the experiment. Following terminal anaesthesia blood plasma, CSF and brains were collected. Lithium levels and brain distribution were measured using Laser Ablation Inductively Coupled Plasma-Mass Spectrometry and total lithium levels were confirmed by Inductively Coupled Plasma-Mass Spectrometry.ResultsLithium was detected in blood, CSF and brain of all fetal and postnatal pups following lithium treatment of dams. Its concentration in pups’ blood was consistently below that in maternal blood (30–35%) indicating significant protection by the placenta and breast tissue. However, much of the lithium that reached the fetus entered its brain. Levels of lithium in plasma fluctuated in different treatment groups but its concentration in CSF was stable at all ages, in agreement with known stable levels of endogenous ions in CSF. There was no significant increase of lithium transfer into CSF following application of Na+/K+ ATPase inhibitor (digoxin) in vivo, indicating that lithium transfer across choroid plexus epithelium is not likely to be via the Na+/K+ ATPase mechanism, at least early in development. Comparison with passive permeability markers suggested that in acute experiments lithium permeability was less than expected for diffusion but similar in long-term experiments at P2.ConclusionsInformation obtained on the distribution of lithium in developing brain provides a basis for studying possible deleterious effects on brain development and behaviour in offspring of mothers undergoing lithium therapy.

Comparison of selenite and selenate in alleviation of drought stress in Nicotiana tabacum L.

Exogenous selenium (Se) improves the tolerance of plants to abiotic stress. However, the effects and mechanisms of different Se species on drought stress alleviation are poorly understood. This study aims to evaluate and compare the different effects and mechanisms of sodium selenate (Na2SeO4) and sodium selenite (Na2SeO3) on the growth, photosynthesis, antioxidant system, osmotic substances and stress-responsive gene expression of Nicotiana tabacum L. under drought stress. The results revealed that drought stress could significantly inhibit growth, whereas both Na2SeO4 and Na2SeO3 could significantly facilitate the growth of N. tabacum under drought stress. However, compared to Na2SeO3, Se application as Na2SeO4 induced a significant increase in the root tip number and number of bifurcations under drought stress. Furthermore, both Na2SeO4 and Na2SeO3 displayed higher levels of photosynthetic pigments, better photosynthesis, and higher concentrations of osmotic substances, antioxidant enzymes, and stress-responsive gene (NtCDPK2, NtP5CS, NtAREB and NtLEA5) expression than drought stress alone. However, the application of Na2SeO4 showed higher expression levels of the NtP5CS and NtAREB genes than Na2SeO3. Both Na2SeO4 and Na2SeO3 alleviated many of the deleterious effects of drought in leaves, which was achieved by reducing stress-induced lipid peroxidation (MDA) and H2O2 content by enhancing the activity of antioxidant enzymes, while Na2SeO4 application showed lower H2O2 and MDA content than Na2SeO3 application. Overall, the results confirm the positive effects of Se application, especially Na2SeO4 application, which is markedly superior to Na2SeO3 in the role of resistance towards abiotic stress in N. tabacum.

Social (–Ecological) Network Analysis in Environmental Governance: Central Publications, Important Concepts, and Areas of Application

Social and Social-Ecological Network Analysis (S(E)NA) have recently emerged as new methods in the environmental governance (EG) literature. By investigating networks of connections between actors, S(E)NA advances the understanding of who is involved in EG and how. We provide an overview of the EG literature applying S(E)NA and map 1) the citation network emerging from cross-references and 2) the similarity network emerging from word similarities between publications. We show that S(E)NA application in EG is in the process of developing into a field of research where publications frequently cite each other. We identify 20 publications which occupy positions as sources, storers or bridges of knowledge in the citation network. While we see S(E)NA applied in diverse resource contexts, these are mainly discussed on the local spatial level, with a focus on “policy” or “collaboration”. We discover that “power structures” and “the production of knowledge” are themes influencing the whole field.diverse resource contexts, these are mainly discussed on the local spatial level, with a focus on “policy” or “collaboration”. We discover that the topics “power structures” and “the production of knowledge” are themes influencing the whole field.

Dust control performance enhancement of red sand via the synergistic application of Na- and Ca-lignosulfonates

Dust control performance enhancement of red sand via the synergistic application of Na- and Ca-lignosulfonates

Sodium addition increases leaf herbivory and fungal damage across four grasslands

Abstract Sodium (Na) is an essential element for all animals, but not for plants. Soil Na supplies vary geographically. Animals that primarily consume plants thus have the potential to be Na limited and plants that uptake Na may be subject to higher rates of herbivory, but their high Na content also may attract beneficial partners such as pollinators and seed dispersers. To test for the effects of Na biogeochemistry on herbivory, we conducted distributed Na press experiments (monthly Na application across the growing season) in four North American grasslands. Na addition increased soil and plant Na concentrations at all sites. Grasses in Na addition plots had significantly higher herbivore damage by leaf miners and fungal pathogens than those in control plots. Forbs with higher foliar Na concentrations had significantly more chewing insect herbivore and fungal damage. While no pattern was evident across all species, several forb species had higher Na concentrations in inflorescences compared to leaves, suggesting they may allocate Na to attract beneficial partners. The uptake of Na by plants, and animal responses, has implications for the salinification in the Anthropocene. Increased use of road salt, irrigation with saline groundwater, rising sea levels and increasing temperatures and evapotranspiration rates with climate change can all increase inputs of Na into terrestrial ecosystems. Our results suggest increasing terrestrial Na availability will benefit insect herbivores and plant fungal pathogens. A free Plain Language Summary can be found within the Supporting Information of this article.

Governing Functionality of Silver Ion-Exchanged Photo-Thermo-Refractive Glass Matrix by Small Additives

In this study, the influence of small additives on the spectral and optical properties of Na+–Ag+ ion-exchanged silicate glass is presented. Polyvalent ions, for example, cerium and antimony, are shown to reduce silver ions to atomic state and promote the growth of photoluminescent silver molecular clusters and plasmonic silver nanoparticles. Na+–Ag+ ion-exchanged and heat-treated glasses doped with halogen ions, such as chlorine or bromine, exhibit formation of photo- and thermochromic AgCl or AgBr nanocrystals. Growth of a silver nanoisland film on the glass surface was observed in the case of undoped sample. The presented results highlight the vital role of small additives to control properties of the silver nanostructures in Na+–Ag+ ion-exchanged glasses. Possible applications of Na+–Ag+ ion-exchanged glass ceramics include but are not limited to biochemical sensors based on surface-enhanced Raman scattering phenomena, temperature and overheating sensors, white light-emitting diodes, and spectral converters.

Composite electrolytes based on electrospun PVDF and ionic plastic crystal matrices for Na-metal battery applications

Sodium ion batteries are widely considered to be a feasible, cost-effective, and sustainable energy storage alternative to Lithium, especially for large-scale energy storage applications. Next generation, safer electrolytes based on ionic liquid (IL) and organic ionic plastic crystals (OIPCs) have been demonstrated as electrochemically stable systems which show superior performance in both Li and Na applications. In particular, phosphonium‐based systems outperform most studied nitrogen‐based ILs and OIPCs. In this study triisobutyl(methyl)phosphonium bis(fluorosulfonyl)imide ([P1i444][FSI]) OIPC mixed with 20 mol% of NaFSI or NaTFSI were combined with an electrospun polyvinylidene fluoride (PVDF) support to create self-standing electrolyte membranes, and their thermal phase behaviour and ionic conductivity were investigated and compared with the bulk electrolytes. The ability of the solid-state composite electrolytes to support the cycling of sodium metal with good efficiency and without breakdown were examined in sodium metal symmetrical coin cells. The sodium transference number was determined to be 0.21. The electrochemical performance of Na/Na3V2(PO4)3 cells incorporating the composite electrolytes, including good cycling stability and rate capability, is also reported. Interestingly, the mixed anion systems appear to outperform the composite electrolyte containing only FSI anions, which may relate to electrolyte interactions with the PVDF fibres.

Exacerbation of Epilepsy by Astrocyte Alkalization and Gap Junction Uncoupling.

Seizures invite seizures. At the initial stage of epilepsy, seizures intensify with each episode; however, the mechanisms underlying this exacerbation remain to be solved. Astrocytes have a strong control over neuronal excitability and the mode of information processing. This control is accomplished by adjusting the levels of various ions in the extracellular space. The network of astrocytes connected via gap junctions allows a wider or more confined distribution of these ions depending on the open probability of the gap junctions. K+ clearance relies on the K+ uptake by astrocytes and the subsequent diffusion of K+ through the astrocyte network. When astrocytes become uncoupled, K+ clearance becomes hindered. Accumulation of extracellular K+ leads to hyperexcitability of neurons. Here, using acute hippocampal slices from mice, we uncovered that brief periods of epileptiform activity result in gap junction uncoupling. In slices that experienced short-term epileptiform activity, extracellular K+ transients in response to glutamate became prolonged. Na+ imaging with a fluorescent indicator indicated that intercellular diffusion of small cations in the astrocytic syncytium via gap junctions became rapidly restricted after epileptiform activity. Using a transgenic mouse with astrocyte-specific expression of a pH sensor (Lck-E2GFP), we confirmed that astrocytes react to epileptiform activity with intracellular alkalization. Application of Na+/HCO3- cotransporter blocker led to the suppression of intracellular alkalization of astrocytes and to the prevention of astrocyte uncoupling and hyperactivity intensification both in vitro and in vivo Therefore, the inhibition of astrocyte alkalization could become a promising therapeutic strategy for countering epilepsy development.SIGNIFICANCE STATEMENT We aimed to understand the mechanisms underlying the plastic change of forebrain circuits associated with the intensification of epilepsy. Here, we demonstrate that first-time exposure to only brief periods of epileptiform activity results in acute disturbance of the intercellular astrocyte network formed by gap junctions in hippocampal tissue slices from mice. Moreover, rapid clearance of K+ from the extracellular space was impaired. Epileptiform activity activated inward Na+/HCO3- cotransport in astrocytes by cell depolarization, resulting in their alkalization. Our data suggest that alkaline pH shifts in astrocytes lead to gap junction uncoupling, hampering K+ clearance, and thereby to exacerbation of epilepsy. Pharmacological intervention could become a promising new strategy to dampen neuronal hyperexcitability and epileptogenesis.

Potential of using a new aluminosilicate amendment for the remediation of paddy soil co-contaminated with Cd and Pb.

Cadmium (Cd) and lead (Pb) are toxic heavy metals that impact human health and biodiversity. Removal of Cd/Pb from contaminated soils is a means for maintaining environmental sustainability and biodiversity. In this study, we applied a newly modified material fly ash (NA), zeolite (ZE), and fly ash (FA) to the paddy soils and evaluated the effects of Cd/Pb accumulation in rice via a one-year field experiment. The results showed that the application of NA and ZE enhanced the soil pH and nutrients to a large extent and reduced the availability of Cd/Pb in soil. The Cd and Pb concentrations in rice grains decreased by 32.8% and 62.9%, respectively, with the NA treatments. Similarly, the application of ZE reduced the Cd and Pb concentrations in rice grains by a factor of 27.9% and 63.5%, respectively, which indicates that the amendments can promote the transfer of Cd and Pb from acid-exchangeable fraction to oxidizable and residual fractions. The Cd/Pb showed a significant positive correlation to other metal ions and a negative correlation to the nutrients. Generally, the application of NA and ZE was effective in reducing Cd/Pb accumulation and improving rice yield. Moreover, the NA was more cost-effective than ZE. Hence, this study proves that NA may be a better amendment for remediation of Cd/Pb contaminated soils.

The effect of initiating neuraxial analgesia service on the rate of cesarean delivery in Hubei, China: a 16-month retrospective study

BackgroundNo Pain Labor &Delivery (NPLD) is a nongovernmental project to increase access to safe neuraxial analgesia through specialized training. This study explores the change in overall cesarean delivery (CD) rate and maternal request CD(MRCD) rate in our hospital after the initiation of neuraxial analgesia service (NA).MethodsNA was initiated in May 1st 2015 by the help of NPLD. Since then, the application of NA became a routine operation in our hospital, and every parturient can choose to use NA or not. The monthly rates of NA, CD, MRCD, multiparous women, intrapartum CD, episiotomy, postpartum hemorrhage (PPH), operative vaginal delivery and neonatal asphyxia were analyzed from January 2015 to April 2016.ResultsThe rate of NA in our hospital was getting increasingly higher from 26.1% in May 2015 to 44.6% in April 2016 (p < 0.001); the rate of CD was 48.1% (3577/7360) and stable from January to May 2015 (p>0.05), then decreased from 50.4% in May 2015 to 36.3% in April 2016 (p < 0.001); the rate of MRCD was 11.4% (406/3577) and also stable from January to May 2015 (p>0.05), then decreased from 10.8% in May 2015 to 5.7% in April 2016 (p < 0.001). At the same time, the rate of multiparous women remained unchanged during the 16 month of observation (p>0.05). There was a negative correlation between the rate of NA and rate of overall CD, r = − 0.782 (95%CI [− 0.948, − 0.534], p<0.001), and between the utilization rate of NA and rate of MRCD, r = − 0.914 (95%CI [− 0.989, − 0.766], p<0.001). The rates of episiotomy, PPH, operative vaginal delivery and neonatal asphyxia in women who underwent vaginal delivery as well as the rates of intrapartum CD, neonatal asphyxia, and PPH in women who underwent CD remained unchanged, and there was no correlation between the rate of NA and anyone of those rates from January 1st 2015 to April 30th 2016 (p>0.05).ConclusionsOur study shows that the rates of CD and MRCD in our department were significantly decreased from May 1st 2015 to April 30th 2016, which may be due to the increasing use of NA during vaginal delivery with the help of NPLD.

Geothermometry and geochemistry of groundwater in the Continental Intercalaire aquifer, southeastern Algeria: Insights from cations, silica and SO4–H2O isotope geothermometers

Characterization of geochemistry and geothermometry of the groundwater from the Continental Intercalaire (CI) aquifer, one of the largest aquifers in the world, stretching over one million km2 surface area shared between Algeria, Tunisia and Libya, was conducted in southeastern Algeria nearby the border with Tunisia. Thirty-two water samples were collected from boreholes to analyze the physicochemical parameters and stable isotopes (δ18O(H2O), δ18O(SO4), δ 34S(SO4)) and determine the origin of water mineralization of the CI aquifer. Water temperature was assessed using several geothermometers, such as cations, silica and SO4–H2O stable isotopes. The CI aquifer displayed a discharge temperature varying from 45 to 65.1 °C due to water circulation at deeper depths ranging from 1000 to 2200 m. The Results show that CI water contains high total dissolved solids (TDS) and neutral to slightly alkaline pH. The most frequent water types were Na–Cl–SO4 and Ca–SO4 indicating the geological formation nature of CI aquifer which is mainly composed of evaporites. The application of Na–K and Na–K–Ca geothermometers yielded unreliable temperatures. However, Na–Li geothermometer resulted in relatively plausible temperatures ranging from 74.69 to 147.83 °C. Quartz and CaSO4–H2O isotope geothermometer are the most suitable methods for temperature estimation, due to their attainment of equilibrium resulting in temperatures ranging from 62 to 93 °C, and validation by the multiple mineral equilibrium approach. The present study demonstrated a successful application of CaSO4–H2O isotope geothermometer in a low enthalpy (<100 °C) geothermal system. The results corroborate previous findings on the same CI aquifer at the Tunisian side and on carbonate-evaporite geothermal reservoirs. Furthermore, geothermal potential of the CI aquifer has been highlighted suggesting its use as a source of renewable energy which could be applied in heating greenhouses and/or generating electricity.

Application of DNA Quadruplex Hydrogels Prepared from Polyethylene Glycol-Oligodeoxynucleotide Conjugates to Cell Culture Media.

Application of Na+-responsive DNA quadruplex hydrogels, which utilize G-quadruplexes as crosslinking points of poly(ethylene glycol) (PEG) network as cell culture substrate, has been examined. PEG-oligodeoxynucleotide (ODN) conjugate, in which four deoxyguanosine (dG4) residues are tethered to both ends of PEG, was prepared by modified high-efficiency liquid phase (HELP) synthesis of oligonucleotides and used as the macromonomer. When mixed with equal volume of cell culture media, the solution of PEG-ODN turned into stiff hydrogel (G-quadruplex hydrogel) as the result of G-quadruplex formation by the dG4 segments in the presence of Na+. PEG-ODN itself did not show cytotoxicity and the resulting hydrogel was stable enough under cell culture conditions. However, L929 fibroblast cells cultured in G-quadruplex hydrogel remained spherical for a week, yet alive, without proliferation. The cells gradually sedimented through the gel day by day, probably due to the reversible nature of G-quadruplex formation and the resulting slow rearrangement of the macromonomers. Once they reached the bottom glass surface, the cells started to spread and proliferate.