Synthesis of CuPF6‐(S)‐BINAP loaded resin and its enantioselectivity toward phenylalanine enantiomers

A type of resin‐anchored CuPF₆‐(S )‐BINAP was synthesized and identified. The PS‐CuPF₆‐(S )‐BINAP resin was used to adsorb the phenylalanine enantiomers. The results showed that the adsorption capacity of PS‐CuPF₆‐(S )‐BINAP resin toward L‐phenylalanine was higher than that of resin toward D‐phenylalanine. PS‐CuPF₆‐(S )‐BINAP resin exhibited good enantioselectivity toward L‐phenylalanine and D‐phenylalanine. The influence of phenylalanine concentration, pH, adsorption time, and temperature on the enantioselectivity of the resin were investigated. The results showed that the enantioselectivity of the resin increased with increasing the phenylalanine concentration, pH, and adsorption time, while it decreased with an increase in temperature. The causes for these influences are discussed. The highest enantioselectivity (α = 2.81) was obtained when the condition of phenylalanine concentration was 0.05 mmol/mL, pH was 8, adsorption time was 12 h, and temperature 5°C. The desorption test for removing D/L‐phenylalanine on PS‐CuPF₆‐(S )‐BINAP resin was also investigated. The desorption ratios of D‐phenylalanine and L‐phenylalanine at pH of 1 were 95.7% and 94.3%, respectively. This result indicated that the PS‐CuPF₆‐(S )‐BINAP resin could be regenerated by shaking with an acidic solution. The reusability of the PS‐CuPF₆‐(S )‐BINAP resin was also assessed and the resin exhibited considerable reusability.     

Hysteresis in poly‐2′‐deoxycytidine i‐motif folding is impacted by the method of analysis as well as loop and stem lengths

In DNA, i‐motif (iM) folds occur under slightly acidic conditions when sequences rich in 2′‐deoxycytidine (dC) nucleotides adopt consecutive dC self base pairs. The pH stability of an iM is defined by the midpoint in the pH transition (pH_T) between the folded and unfolded states. Two different experiments to determine pH_T values via circular dichroism (CD) spectroscopy were performed on poly‐dC iMs of length 15, 19, or 23 nucleotides. These experiments demonstrate two points: (1) pH_T values were dependent on the titration experiment performed, and (2) pH‐induced denaturing or annealing processes produced isothermal hysteresis in the pH_T values. These results in tandem with model iMs with judicious mutations of dC to thymidine to favor particular folds found the hysteresis was maximal for the shorter poly‐dC iMs and those with an even number of base pairs, while the hysteresis was minimal for longer poly‐dC iMs and those with an odd number of base pairs. Experiments to follow the iM folding via thermal changes identified thermal hysteresis between the denaturing and annealing cycles. Similar trends were found to those observed in the CD experiments. The results demonstrate that the method of iM analysis can impact the pH_T parameter measured, and hysteresis was observed in the pH_T and T_m values.     

Chronic voluntary ethanol intake hypersensitizes 5‐HT1A autoreceptors in C57BL/6J mice

Alcoholism is a complex disorder involving, among others, the serotoninergic (5‐HT) system, mainly regulated by 5‐HT_1A autoreceptors in the dorsal raphe nucleus. 5‐HT_1A autoreceptor desensitization induced by chronic 5‐HT reuptake inactivation has been associated with a decrease in ethanol intake in mice. We investigated here whether, conversely, chronic ethanol intake could induce 5‐HT_1A autoreceptor supersensitivity, thereby contributing to the maintenance of high ethanol consumption. C57BL/6J mice were subjected to a progressive ethanol intake procedure in a free‐choice paradigm (3–10% ethanol versus tap water; 21 days) and 5‐HT_1A autoreceptor functional state was assessed using different approaches. Acute administration of the 5‐HT_1A receptor agonist ipsapirone decreased the rate of tryptophan hydroxylation in striatum, and this effect was significantly larger (+75%) in mice that drank ethanol than in those drinking water. Furthermore, ethanol intake produced both an increased potency (+45%) of ipsapirone to inhibit the firing of 5‐HT neurons, and a raise (+35%) in 5‐HT_1A autoreceptor‐mediated stimulation of [³⁵S]GTP‐γ‐S binding in the dorsal raphe nucleus. These data showed that chronic voluntary ethanol intake in C57BL/6J mice induced 5‐HT_1A autoreceptor supersensitivity, at the origin of a 5‐HT neurotransmission deficit, which might be causally related to the addictive effects of ethanol intake.     

Fermentability of the hemicellulose‐derived sugars from steam‐exploded softwood (douglas fir)

Steam explosion ofDouglas fir wood chips under low‐severity conditions (log Ro = 3.08 corresponding to 175°C, 7.5 min, and 4.5% SO₂) resulted in the recovery of around 87% of the original hemicellulose component in the water‐soluble stream. More than 80% of the recovered hemicellulose was in a monomeric form. As the pretreatment severity increased from 3.08 to 3.76, hemicellulose recovery dropped to 43% of the original hemicellulose found in Douglas fir chips while the concentration of glucose originating from cellulose hydrolysis increased along with the concentration of sugar degradation products such as furfural and hydroxymethylfurfural. Despite containing a higher concentration of hexose monomers (mainly glucose originating from cellulose degradation), the water‐soluble fraction prepared under high‐severity conditions (log Ro = 3.73 corresponding to 215°C, 2.38 min, and 2.38% SO₂) was not readily fermented. Only the two hydrolyzates obtained at low and medium (195°C, 4.5 min, and 4.5% SO₂) severities were fermented to ethanol using a spent sulfur liquor adapted strain of Saccharomyces cerevisiae. High ethanol yields were obtained for these two hydrolyzates with 0.44 g of ethanol produced per gram of hexose utilized (86% of theoretical). However, the best results of hemicellulose recovery and fermentability were obtained for the low‐severity water‐soluble fraction which was fermented significantly faster than the fraction obtained after medium‐severity treatment probably because it contained higher amounts of fermentation inhibitors. © 1999 John Wiley & Sons, Inc. Biotechnol Bioeng 64: 284–289, 1999.     

Selection of broad‐spectrum cephalosporin‐resistant Escherichia coli in the feces of healthy dogs after administration of first‐generation cephalosporins

Although antimicrobial products are essential for treating diseases caused by bacteria, antimicrobial treatment selects for antimicrobial‐resistant (AMR) bacteria. The aim of this study was to determine the effects of administration of first‐generation cephalosporins on development of resistant Escherichia coli in dog feces. The proportions of cephalexin (LEX)‐resistant E. coli in fecal samples of three healthy dogs treated i.v. with cefazolin before castration and then orally with LEX for 3 days post‐operation (PO) were examined using DHL agar with or without LEX (50 µg/mL). LEX‐resistant E. coli were found within 3 days PO, accounted for 100% of all identified E. coli 3–5 days PO in all dogs, and were predominantly found until 12 days PO. LEX‐resistant E. coli isolates on DHL agar containing LEX were subjected to antimicrobial susceptibility testing, pulsed‐field gel electrophoresis (PFGE) genotyping, β‐lactamase typing and plasmid profiling. All isolates tested exhibited cefotaxime (CTX) resistance (CTX minimal inhibitory concentration ≥4 µg/mL). Seven PFGE profiles were classified into five groups and three β‐lactamase combinations (bla_CMY‐4‐bla_TEM‐1, bla_TEM‐1‐bla_CTX‐M‐15 and bla_TEM‐1‐bla_CTX‐M‐15‐bla_CMY‐4). All isolates exhibited identical PFGE profiles in all dogs on four days PO and subsequently showed divergent PFGE profiles. Our results indicate there are two selection periods for AMR bacteria resulting from the use of antimicrobials. Thus, continuing hygiene practices are necessary to prevent AMR bacteria transfer via dog feces after antimicrobial administration.     

Deficiency of insulin‐like growth factor 1 reduces vulnerability to chronic alcohol intake‐induced cardiomyocyte mechanical dysfunction: role of AMPK

Circulating insulin‐like growth factor I (IGF‐1) levels are closely associated with cardiac performance although the role of IGF‐1 in alcoholic cardiac dysfunction is unknown. This study was designed to evaluate the impact of severe liver IGF‐1 deficiency (LID) on chronic alcohol‐induced cardiomyocyte contractile and intracellular Ca²⁺ dysfunction. Adult male C57 and LID mice were placed on a 4% alcohol diet for 15 weeks. Cardiomyocyte contractile and intracellular Ca²⁺ properties were evaluated including peak shortening (PS), maximal velocity of shortening/relengthening (±dL/dt), time‐to‐relengthening (TR₉₀), change in fura‐fluorescence intensity (ΔFFI) and intracellular Ca²⁺ decay. Levels of apoptotic regulators caspase‐3, Bcl‐2 and c‐Jun NH2‐terminal kinase (JNK), the ethanol metabolizing enzyme mitochondrial aldehyde dehydrogenase (ALDH2), as well as the cellular fuel gauge AMP‐activated protein kinase (AMPK) were evaluated. Chronic alcohol intake enlarged myocyte cross‐sectional area, reduced PS, ± dL/dt and ΔFFI as well as prolonged TR₉₀ and intracellular Ca²⁺ decay, the effect of which was greatly attenuated by IGF‐1 deficiency. The beneficial effect of LID against alcoholic cardiac mechanical defect was ablated by IGF‐1 replenishment. Alcohol intake increased caspase‐3 activity/expression although it down‐regulated Bcl‐2, ALDH2 and pAMPK without affecting JNK and AMPK. IGF‐1 deficiency attenuated alcoholism‐induced responses in all these proteins with the exception of Bcl‐2. In addition, the AMPK agonist 5‐aminoimidazole‐4‐carboxamide‐1‐β‐D‐ribofuranoside abrogated short‐term ethanol incubation‐elicited cardiac mechanical dysfunction. Taken together, these data suggested that IGF‐1 deficiency may reduce the sensitivity to ethanol‐induced myocardial mechanical dysfunction. Our data further depicted a likely role of Caspase‐3, ALDH2 and AMPK activation in IGF‐1 deficiency induced ‘desensitization’ of alcoholic cardiomyopathy.     

Lipase‐Catalyzed Kinetic Resolution of (±)‐1‐(2‐Furyl) Ethanol in Nonaqueous Media

S‐1‐(2‐Furyl) ethanol serves as an important chiral building block for the preparation of various natural products, fine chemicals, and is widely used in the chemical and pharmaceutical industries. In this work, lipase‐catalyzed kinetic resolution of (R/S)‐1‐(2‐furyl) ethanol using different acyl donors was investigated. Vinyl esters are good acyl donors vis‐à‐vis alkyl esters for kinetic resolution. Among them, vinyl acetate was found to be the best acyl donor. Different immobilized lipases such as Rhizomucor miehei lipase, Thermomyces lanuginosus lipase, and Candida antarctica lipase B were evaluated for this reaction, among which C. antarctica lipase B, immobilized on acrylic resin (Novozym 435), was found to be the best catalyst in n‐heptane as solvent. The effect of various parameters was studied in a systematic manner. Maximum conversion of 47% and enantiomeric excess of the substrate (ee_s) of 89% were obtained in 2 h using 5 mg of enzyme loading with an equimolar ratio of alcohol to vinyl acetate at 60°C at a speed of 300 rpm in a batch reactor. From the analysis of progress curve and initial rate data, it was concluded that the reaction followed the ordered bi–bi mechanism with dead‐end ester inhibition. Kinetic parameters were obtained by using nonlinear regression. This process is more economical, green, and easily scalable than the chemical processes. Chirality 26:286–292, 2014. © 2014 Wiley Periodicals, Inc.     

Claisen–Schmidt condensation: Synthesis of (1S,6R)/(1R,6S)‐2‐oxo‐N,4,6‐triarylcyclohex‐3‐enecarboxamide derivatives with different substituents in H2O/EtOH

A simple, green, and direct three‐component condensation of acetophenone, aromatic aldehydes with 3‐oxo‐N‐phenylbutanamide (acetoacetanilide) to generate some novel (1S,6R)/(1R,6S)‐2‐oxo‐N,4,6‐triarylcyclohex‐3‐enecarboxamide derivatives was carried out over K₂CO₃ (10 mol%) with high efficiency in water/ethanol as green solvent at room temperature. This protocol proceeded via Claisen–Schmidt condensation and Michael addition. The present methodology offers several advantages, such as short reaction time, high yield, more readily available and inexpensive materials, more environmentally friendly, no need for column chromatography, simple work‐up procedure, and the absence of volatile and hazardous organic solvents.     

A Simple Method for Resolution of Endo‐/Exo‐Monoesters of Trans‐Norborn‐5‐Ene‐2,3‐Dicarboxylic Acids Into Their Enantiomers

Separation of optical isomers obtainable from trans‐norborn‐5‐ene‐2,3‐dicarboxylic acid methyl and tert‐butyl monoesters was performed by crystallization of the respective salts prepared with (R)‐ and (S)‐1‐phenylethylamine. Starting from racemic endo‐monomethyl ester of trans‐norborn‐5‐ene‐2,3‐dicarboxylic acid, prepared by partial hydrolysis of the cyclopentadiene‐dimethyl fumarate adduct, the corresponding (2R,3R)‐endo‐monoester was isolated in 97% enantiomeric excess (ee) yield after seven repeated crystallizations from tetrachloromethane. Starting from exo‐mono‐tert‐butyl ester of the same acid, prepared by alcoholysis of the cyclopentadiene‐maleic anhydride adduct followed by isomerization, (2R,3R)‐exo‐monoester was isolated in >98% ee yield after four repeated crystallizations from ethanol. Crystallization of the acids from the mother liquor containing (S)‐1‐phenylethylamine yielded products with inverse stereochemical configuration. Chirality 27:151–155, 2015. © 2014 Wiley Periodicals, Inc.     

Thieno[3,4‐c]Pyrrole‐4,6‐Dione‐Based Polymer Acceptors for High Open‐Circuit Voltage All‐Polymer Solar Cells

While polymer acceptors are promising fullerene alternatives in the fabrication of efficient bulk heterojunction (BHJ) solar cells, the range of efficient material systems relevant to the “all‐polymer” BHJ concept remains narrow, and currently limits the perspectives to meet the 10% efficiency threshold in all‐polymer solar cells. This report examines two polymer acceptor analogs composed of thieno[3,4‐c ]pyrrole‐4,6‐dione (TPD) and 3,4‐difluorothiophene ([2F]T) motifs, and their BHJ solar cell performance pattern with a low‐bandgap polymer donor commonly used with fullerenes (PBDT‐TS1; taken as a model system). In this material set, the introduction of a third electron‐deficient motif, namely 2,1,3‐benzothiadiazole (BT), is shown to (i) significantly narrow the optical gap (E _opt) of the corresponding polymer (by ≈0.2 eV) and (ii) improve the electron mobility of the polymer by over two orders of magnitude in BHJ solar cells. In turn, the narrow‐gap P2TPDBT[2F]T analog (E _opt = 1.7 eV) used as fullerene alternative yields high open‐circuit voltages (V _OC) of ≈1.0 V, notable short‐circuit current values (J _SC) of ≈11.0 mA cm⁻², and power conversion efficiencies (PCEs) nearing 5% in all‐polymer BHJ solar cells. P2TPDBT[2F]T paves the way to a new, promising class of polymer acceptor candidates.     

Redox Dynamics of Arsenic Species in the Root‐Near Environment of Juncus effusus Investigated in a Macro‐Gradient‐Free Rooted Gravel Bed Reactor

In the framework of investigating the dynamics of As species within the planted soil beds of treatment wetlands, the redox dynamics of As species particularly in the root‐near environment of the rhizosphere were investigated. For this purpose, long‐term experiments were carried out using a specially designed macro‐gradient‐free rooted gravel bed reactor, planted with Juncus effusus to treat an artificial wastewater containing As (200 μg As/L). The exceptional quality of the biofilm processes at the helophyte root‐surfaces in treatment wetlands were of special importance in this investigation. The results showed that under C‐deficient conditions, a highly efficient As immobilization (> 85 %), obviously due to adsorption and/or co‐precipitation, was attained. The addition of organic carbon immediately caused an elevated As concentration and enrichment of As(III) (nearly 80 % of total As) in the reactor. Increasing the SO₄^2– concentration in the artificial wastewater inflow facilitated a high As immobilization (> 82 %) under sulfate reducing condition. In principle, a highly efficient microbial dissimilatory sulfate reduction contributed to S^2– formation and a greater As immobilization (most likely as As₂S₃) under C surplus and reducing conditions. Significant differences in As immobilization were observed by varying the inflow of the SO₄^2– concentration (0.2, 5, 10, 25 S/L) under C surplus conditions. More As(III) precipitates (15 % less in the outflow) when the inflow of the SO₄^2– concentration was decreased from 25 mg S/L to 10 mg S/L. Immobilized As showed greater instability by releasing As(V) (up to 85 % of total As) due to changes in the dynamic redox conditions inside the reactor. Re‐oxidation of reduced sulfur into other S species (e.g. S⁰, SO₄^2–) due to plant‐root mediated O₂ release probably caused an oxidative dissolution of already precipitated insoluble As (e.g. As₂S₃) and as a consequent As remobilization. The findings of this study highlighted the significance of SO₄^2– in relation to organic C supply in planted soil beds treating As‐contaminated wastewater under constructed wetland conditions.     

Prostaglandin I2 upregulates the expression of anterior pharynx‐defective‐1α and anterior pharynx‐defective‐1β in amyloid precursor protein/presenilin 1 transgenic mice

Cyclooxygenase‐2 (COX‐2) has been recently identified to be involved in the pathogenesis of Alzheimer's disease (AD). Yet, the role of an important COX‐2 metabolic product, prostaglandin (PG) I₂, in the pathogenesis of AD remains unknown. Using human‐ and mouse‐derived neuronal cells as well as amyloid precursor protein/presenilin 1 (APP/PS1) transgenic mice as model systems, we elucidated the mechanism of anterior pharynx‐defective (APH)‐1α and pharynx‐defective‐1β induction. In particular, we found that PGI₂ production increased during the course of AD development. Then, PGI₂ accumulation in neuronal cells activates PKA/CREB and JNK/c‐Jun signaling pathways by phosphorylation, which results in APH‐1α/1β expression. As PGI₂ is an important metabolic by‐product of COX‐2, its suppression by NS398 treatment decreases the expression of APH‐1α/1β in neuronal cells and APP/PS1 mice. More importantly, β‐amyloid protein (Aβ) oligomers in the cerebrospinal fluid (CSF) of APP/PS1 mice are critical for stimulating the expression of APH‐1α/1β, which was blocked by NS398 incubation. Finally, the induction of APH‐1α/1β was confirmed in the brains of patients with AD. Thus, these findings not only provide novel insights into the mechanism of PGI₂‐induced AD progression but also are instrumental for improving clinical therapies to combat AD.     

A novel P700 redox kinetics probe for rapid,non‐intrusive and whole‐tissue determination of photosystem II functionality,and the stoichiometry of the two photosystems in vivo

We sought a rapid, non‐intrusive, whole‐tissue measure of the functional photosystem II (PS II) content in leaves. Summation of electrons, delivered by a single‐turnover flash to P700⁺ (oxidized PS I primary donor) in continuous background far‐red light, gave a parameter S in absorbance units after taking into account an experimentally determined basal electron flux that affects P700 redox kinetics. S was linearly correlated with the functional PS II content measured by the O₂ yield per single‐turnover repetitive flash in Arabidopsis thaliana expressing an antisense construct to the PsbO (manganese‐stabilizing protein in PS II) proteins of PS II (PsbO mutants). The ratio of S to z_max (total PS I content in absorbance units) was comparable to the PS II/PS I reaction‐center ratio in wild‐type A. thaliana and in control Spinacea oleracea. Both S and S/z_max decreased in photoinhibited spinach leaf discs. The whole‐tissue functional PS II content and the PS II/photosystem I (PS I) ratio can be non‐intrusively monitored by S and S/z_max, respectively, using a quick P700 absorbance protocol compatible with modern P700 instruments.     

Trace analysis of N‐acetyl‐L‐cysteine using luminol–H2O2 chemiluminescence system catalyzed by silver nanoparticles

N‐Acetyl‐L‐cysteine (NAC) can inhibit the luminol–H₂O₂, reaction, which is catalyzed by silver nanoparticles. Based on this phenomenon a new method was developed for NAC determination. Under optimum conditions, a linear relationship between chemiluminescence intensity and NAC concentration was found in the range 0.034–0.98 µg/mL. The detection limit was 0.010 µg/mL (S/N =3), and the relative standard deviation (RSD) was <5% for 0.480 µg/mL NAC (n =5). This simple, sensitive and inexpensive method has been applied to measure the concentration of NAC in pharmaceutical tablets. Copyright © 2014 John Wiley & Sons, Ltd.     

Synthesis and Olfactory Characterization of Silicon‐Containing Derivatives of the Acyclic Lily‐of‐the‐Valley Odorant 5,7,7‐Trimethyl‐4‐methylideneoctanal

5‐Methyl‐4‐methylidene‐6‐(trimethylsilyl)hexanal ( 1b ), a sila analog of the acyclic lily‐of‐the‐valley odorant 5,7,7‐trimethyl‐4‐methylideneoctanal ( 1a ), and the Si‐containing derivatives 2 – 6 were prepared in multistep syntheses, starting from Cl₃SiH and Cl₂SiMe₂, respectively. Compounds 1b, 2 – 6 , and their new precursors were characterized by elemental analyses (C, H, N) and NMR spectroscopic studies (¹H, ¹³C, ¹⁵N, and ²⁹Si). To gain more information about the structure? odor correlation in the family of lily‐of‐the‐valley or ‘muguet’ odorants, C/Si analogs 1a / 1b and derivatives 2 – 6 were evaluated for their olfactory properties.     

Alternatives for natural‐gas‐based heating systems: A quantitative GIS‐based analysis of climate impacts and financial feasibility

The heating of buildings currently produces 6% of global greenhouse gas emissions. Sustainable heating technologies can reduce heating‐related CO₂ emissions by up to 90%. We present a Python‐based GIS model to analyze the environmental and financial impact of strategies to reduce heating‐related CO₂ emissions of residential buildings. The city‐wide implementation of three alternatives to natural gas are evaluated: high‐temperature heating networks, low‐temperature heating networks, and heat pumps. We find that both lowering the demand for heat and providing more sustainable sources of heat will be necessary to achieve significant CO₂‐emission reductions. Of the studied alternatives, only low‐temperature heating networks and heat pumps have the potential to reduce CO₂ emissions by 90%. A CO₂ tax and an increase in tax on the use of natural gas are potent policy tools to accelerate the adoption of low‐carbon heating technologies.     

A colony‐to‐lawn method for efficient transformation of Escherichia coli

Aims: To develop a fast, convenient, inexpensive and efficient Escherichia coli transformation method for changing hosts of plasmids, which can also facilitate the selection of positive clones after DNA ligation and transformation. Methods and Results: A single fresh colony from plasmid‐containing donor strain is picked up and suspended in 75% ethanol. Cells are pelleted and resuspended in CaCl₂ solution and lysed by repetitive freeze–thaw cycles to obtain plasmid‐containing cell lysate. The E. coli recipient cells are scraped from the lawn of LB plate and directly suspended in the plasmid‐containing cell lysate for transformation. Additionally, a process based on colony‐to‐lawn transformation and protein expression was designed and conveniently used to screen positive clones after DNA ligation and transformation. Conclusions: With this method, a single colony from plasmid‐containing donor strain can be directly used to transform recipient cells scraped from lawn of LB plate. Additionally, in combination with this method, screening of positive clones after DNA ligation and transformation can be convenient and time‐saving. Significance and Impact of the Study: Compared with current methods, this procedure saves the steps of plasmid extraction and competent cell preparation. Therefore, the method should be highly valuable especially for high‐throughput changing hosts of plasmids during mutant library creation.     

Polysulfide‐Shuttle Control in Lithium‐Sulfur Batteries with a Chemically/Electrochemically Compatible NaSICON‐Type Solid Electrolyte

A NaSICON‐type Li⁺‐ion conductive membrane with a formula of Li_{1+ x} Y _x Zr_{2? x} (PO₄)₃ (LYZP) (x = 0–0.15) has been explored as a solid‐electrolyte/separator to suppress polysulfide‐crossover in lithium‐sulfur (Li‐S) batteries. The LYZP membrane with a reasonable Li⁺‐ion conductivity shows both favorable chemical compatibility with the lithium polysulfide species and exhibits good electrochemical stability under the operating conditions of the Li‐S batteries. Through an integration of the LYZP solid electrolyte with the liquid electrolyte, the hybrid Li‐S batteries show greatly enhanced cyclability in contrast to the conventional Li‐S batteries with the porous polymer (e.g., Celgard) separator. At a rate of C/5, the hybrid Li ||LYZP|| Li₂S₆ batteries developed in this study (with a Li‐metal anode, a liquid/LYZP hybrid electrolyte, and a dissolved lithium polysulfide cathode) delivers an initial discharge capacity of ≈1000 mA h g^?1 (based on the active sulfur material) and retains ≈90% of the initial capacity after 150 cycles with a low capacity fade‐rate of <0.07% per cycle.     

Continuous multistep versus fed‐batch production of ethanol and xylitol in a simulated medium of sugarcane bagasse hydrolyzates

Co‐cultures for simultaneous production of ethanol and xylitol were studied under different operation bioreactor modes using Candida tropicalis IEC5‐ITV and Saccharomyces cerevisiae ITV01‐RD in a simulated medium of sugarcane bagasse hydrolyzates. Xylitol and ethanol tolerance by S. cerevisiae and C. tropicalis, respectively, was evaluated. The results showed that C. tropicalis was sensitive to ethanol concentrations up to 30 g/L, while xylitol had no effect on S. cerevisiae viability and metabolism. The best condition found for simultaneous culture was S. cerevisiae co‐culture and C. tropicalis sequential cultivation at 24 h. Under these conditions, productivity and yield for ethanol were Q_EtOH = 0.72 g L^?1 h^?1 and Y_EtOH/s = 0.37 g/g, and for xylitol, Q_XylOH = 0.10 g L^?1 h^?1 and Y_XylOH/S = 0.31 g/g, respectively; using fed‐batch culture, the results were Q_EtOH = 0.87 g L^?1 h^?1 and Y_EtOH/s = 0.44 g L^?1 h^?1, and Q_EtOH = 0.27 g L^?1 h^?1 and Y_EtOH/s = 0.57 g/g, respectively. Maximum volumetric productivity in continuous multistep cultures of ethanol and xylitol was at dilution rates of 0.131 and 0.074 h^?1, respectively. Continuous multistep production, Q_EtOH increased up to 50% more than in fed‐batch culture, even though xylitol yield remained unchanged.