Challenges and Emerging Opportunities in High‐Mobility and Low‐Energy‐Consumption Organic Field‐Effect Transistors

Organic field‐effect transistors (OFETs) are the basic elements of organic circuits towards flexible, printable, and wearable electronics. Low‐energy‐consumption OFETs with high mobility are the prerequisite for practical applications. After 30 years of development, OFETs have progressed rapidly, from field‐effect materials to devices, and from individual device to small‐ and medium‐scale integration. Here, a brief retrospective of OFETs' development over the past decades, and the emerging opportunities and challenges from device physics, multifunctional materials to integrated application are presented.     

HS‐SPME‐GC‐FID method for detection and quantification of Bacillus cereus ATCC 10702 mediated 2‐acetyl‐1‐pyrroline

A rapid micro‐scale solid‐phase micro‐extraction (SPME) procedure coupled with gas‐chromatography with flame ionized detector (GC‐FID) was used to extract parts per billion levels of a principle basmati aroma compound “2‐acetyl‐1‐pyrroline” (2‐AP) from bacterial samples. In present investigation, optimization parameters of bacterial incubation period, sample weight, pre‐incubation time, adsorption time, and temperature, precursors and their concentrations has been studied. In the optimized conditions, detection of 2‐AP produced by Bacillus cereus ATCC10702 using only 0.5 g of sample volume was 85 μg/kg. Along with 2‐AP, 15 other compounds produced by B. cereus were also reported out of which 14 were reported for the first time consisting mainly of (E)?2‐hexenal, pentadecanal, 4‐hydroxy‐2‐butanone, n‐hexanal, 2–6‐nonadienal, 3‐methoxy‐2(5H) furanone and 2‐acetyl‐1‐pyridine and octanal. High recovery of 2‐AP (87 %) from very less amount of B. cereus samples was observed. The method is reproducible fast and can be used for detection of 2‐AP production by B. cereus. © 2014 American Institute of Chemical Engineers Biotechnol. Prog., 30:1356–1363, 2014     

Enantiopure 4‐oxazolin‐2‐ones and 4‐methylene‐2‐oxazolidinones as chiral building blocks in a divergent asymmetric synthesis of heterocycles

Enantiopure 3‐((R)‐ and 3‐((S)‐1‐phenylethyl)‐4‐oxazoline‐2‐ones were evaluated as chiral building blocks for the divergent construction of heterocycles with stereogenic quaternary centers. The N‐(R)‐ or N‐(S)‐1‐phenylethyl group of these compounds proved to be an efficient chiral auxiliary for the asymmetric induction of the 4‐ and 5‐positions of the 4‐oxazolin‐2‐one ring through thermal and MW‐promoted nucleophilic conjugated addition to Michael acceptors and alkyl halides. The resulting adducts were transformed via a cascade process into fused six‐membered carbo‐ and heterocycles. The structure of the reaction products depended on the electrophiles and reaction conditions used. Alternative isomeric 4‐methylene‐2‐oxazolidinones served as chiral precursors for a versatile and divergent approach to highly substituted cyclic carbamates. DFT quantum calculations showed that the formation of bicyclic pyranyl compounds was generated by a diastereoselective concerted hetero‐Diels‐Alder cycloaddition.     

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.     

2H‐Pyran‐2‐one and 2H‐Furan‐2‐one Derivatives from the Plant Endophytic Fungus Pestalotiopsis fici

Two new α‐pyrones (=2H‐pyran‐2‐ones), ficipyrones A and B ( 1 and 2 , resp.), and two new α‐furanones (=2H‐furan‐2‐ones), ficifuranones A and B ( 3 and 4 , resp.), together with three known metabolites, antibiotic F 0368 ( 5 ), hydroxyseiridin ( 6 ), and hydroxyisoseiridin ( 7 ), were isolated from solid cultures of the plant endophytic fungus Pestalotiopsis fici. Their structures were elucidated primarily by NMR spectroscopy, and the absolute configuration of 1 was deduced from the circular‐dichroism (CD) data. Compound 1 showed antifungal activity against the plant pathogen Gibberella zeae (CGMCC 3.2873) with an IC₅₀ value of 15.9 μM .     

Validated spectrofluorimetric method for the determination of carbamazepine in pharmaceutical dosage forms after reaction with 4‐chloro‐7‐‐nitrobenzo‐2‐oxa‐1,3‐diazole (NBD‐Cl)

A sensitive and simple spectrofluorimetric method has been developed and validated for the determination of the anti‐epileptic drug carbamazepine (CBZ) in its dosage forms. The method was based on a nucleophilic substitution reaction of CBZ with 4‐chloro‐7‐nitrobenzo‐2‐ oxa‐1,3‐diazole (NBD‐Cl) in borate buffer (pH 9) to form a highly fluorescent derivative that was measured at 530 nm after excitation at 460 nm. Factors affecting the formation of the reaction product were studied and optimized, and the reaction mechanism was postulated. The fluorescence–concentration plot is rectilinear over the range of 0.6–8 µg/mL with limit of detection of 0.06 µg/mL and limit of quantitation of 0.19 µg/mL. The method was applied to the analysis of commercial tablets and the results were in good agreement with those obtained using the reference method. Validation of the analytical procedures was evaluated according to ICH guidelines. Copyright © 2015 John Wiley & Sons, Ltd.     

Cyclic‐di‐GMP and cyclic‐di‐AMP activate the NLRP3 inflammasome

The cyclic dinucleotides 3'‐5'diadenylate (c‐diAMP) and 3'‐5' diguanylate (c‐diGMP) are important bacterial second messengers that have recently been shown to stimulate the secretion of type I Interferons (IFN‐Is) through the c‐diGMP‐binding protein MPYS/STING. Here, we show that physiologically relevant levels of cyclic dinucleotides also stimulate a robust secretion of IL‐1β through the NLRP3 inflammasome. Intriguingly, this response is independent of MPYS/STING. Consistent with most NLRP3 inflammasome activators, the response to c‐diGMP is dependent on the mobilization of potassium and calcium ions. However, in contrast to other NLRP3 inflammasome activators, this response is not associated with significant changes in mitochondrial potential or the generation of mitochondrial reactive oxygen species. Thus, cyclic dinucleotides activate the NLRP3 inflammasome through a unique pathway that could have evolved to detect pervasive bacterial pathogen‐associated molecular patterns associated with intracellular infections.     

Asymmetrically simultaneous synthesis of L‐homophenylalanine and N6‐protected‐2‐oxo‐6‐amino‐hexanoic acid by engineered Escherichia coli aspartate aminotransferase

L ‐Homophenylalanine (L ‐HPA) and N⁶‐protected‐2‐oxo‐6‐amino‐hexanoic acid (N⁶‐protected‐OAHA) can be used as building blocks for the manufacture of angiotensin‐converting enzyme inhibitors. To synthesize L ‐HPA and N⁶‐protected‐OAHA simultaneously from 2‐oxo‐4‐phenylbutanoic acid (OPBA) and N⁶‐protected‐L ‐lysine, several variants of Escherichia coli aspartate aminotransferase (AAT) were developed by site‐directed mutagenesis and their catalytic activities were investigated. Three kinds of N⁶‐protected‐L ‐lysine were tested as potential amino donors for the bioconversion process. AAT variants of R292E/L18H and R292E/L18T exhibited specific activities of 0.70±0.01 U/mg protein and 0.67±0.02 U/mg protein to 2‐amino‐6‐tert‐butoxycarbonylamino‐hexanoic acid (BOC‐lysine) and 2‐amino‐6‐(2,2,2‐trifluoro‐acetylamino)‐hexanoic acid, respectively. E. coli cells expressing R292E/L18H variant were able to convert OPBA and BOC‐lysine to L ‐HPA and 2‐oxo‐6‐tert‐butoxycarbonylamino‐hexanoic acid (BOC‐OAHA) with 96.2% yield in 8 h. This is the first report demonstrating a process for the simultaneous production of two useful building blocks, L ‐HPA and BOC‐OAHA. © 2009 American Institute of Chemical Engineers Biotechnol. Prog., 2009     

Species‐time‐area and phylogenetic‐time‐area relationships in tropical tree communities

The species‐area relationship (SAR) has proven to be one of the few strong generalities in ecology. The temporal analog of the SAR, the species‐time relationship (STR), has received considerably less attention. Recent work primarily from the temperate zone has aimed to merge the SAR and the STR into a synthetic and unified species‐time‐area relationship (STAR) as originally envisioned by Preston (1960). Here we test this framework using two tropical tree communities and extend it by deriving a phylogenetic‐time‐area relationship (PTAR). The work finds some support for Preston's prediction that diversity‐time relationships, both species and phylogenetic, are sensitive to the spatial scale of the sampling. Contrary to the Preston's predictions we find a decoupling of diversity‐area and diversity‐time relationships in both forests as the time period used to quantify the diversity‐area relationship changes. In particular, diversity‐area and diversity‐time relationships are positively correlated using the initial census to quantify the diversity‐area relationship, but weakly or even negatively correlated when using the most recent census. Thus, diversity‐area relationships could forecast the temporal accumulation of biodiversity of the forests, but they failed to “back‐cast” the temporal accumulation of biodiversity suggesting a decoupling of space and time.     

The special optical properties and application of the heterocyclic compound diethyl 6‐anilino‐5H‐2,3‐dithia‐5,7‐diazacyclopenta(cd)indene‐1,4‐dicarboxylate

The heterocyclic compound diethyl 6‐anilino‐5H‐2,3‐dithia‐5,7‐diazacyclopenta(cd)indene‐1,4‐dicarboxylate (D1) was found to form highly emissive aggregates in polar solvents, and the aggregate emission can be tuned by the simple addition of water to a dimethylsulfoxide solution. A theoretical study based on Density functional theory (DFT) calculations, shows that intermolecular interactions of D1 with solvent may be potential factors in the fluorescence change. In addition, the phenyl ring in D1 plays an important role because of its response to solvent. In the non‐aggregated state, deprotonation of the N–H of D1 can proceed easily on the addition of base, and the deprotonated compound might interact with Ag⁺, resulting in a significant change in color and fluorescence quenching, which make it a potential chemosensor for the selective detection of trace amounts of Ag⁺. Copyright © 2013 John Wiley & Sons, Ltd.     

Dual labeling with 5‐bromo‐2'‐deoxyuridine and 5‐ethynyl‐2'‐deoxyuridine for estimation of cell migration rate in the small intestinal epithelium

Small intestinal epithelium is a self‐renewing system in which the entire sequence of cell proliferation, differentiation, and removal is coupled to cell migration along the crypt‐villus axis. We examined whether dual labeling with different thymidine analogues, 5‐bromo‐2'‐deoxyuridine (BrdU) and 5‐ethynyl‐2'‐deoxyuridine (EdU), can be used to estimate cell migration rates on the villi of small intestines in rats. Rats received a single intraperitoneal injection of BrdU and EdU within a time interval, and signals in tissue sections were examined by immunohistochemistry and the “click” reaction, respectively. We successfully observed BrdU‐ and EdU‐positive cells on the epithelium with no cross‐reaction. In addition, we observed an almost complete overlapping of BrdU‐ and EdU‐positive cells in rats administered simultaneously with BrdU and EdU. By calculating the cell migration rate by dividing the distance between the median cell positions of the distribution of BrdU‐ and EdU‐positive cells by the time between the injection of BrdU and EdU, we estimated approximately 9 and 5 μm/h for the cell migration rates on the villi in the jejunum and ileum, respectively. We propose that dual labeling with BrdU and EdU within a time interval, followed by detecting with immunohistochemistry and the click reaction, respectively, is useful to estimate accurately the cell migration rate in the intestinal epithelium in a single animal.     

1‐Aminobenzocyclobutene‐1‐phosphonic Acid and Related Compounds as Inhibitors of Phenylalanine Ammonia‐Lyase

Five new geminal aminocycloalkanephosphonic acids ( 4 – 8 ) containing both an aromatic ring and a cycloalkane ring were synthesized and evaluated as potential inhibitors of buckwheat phenylalanine ammonia‐lyase (PAL). Within the set of compounds which are related to 2‐aminoindane‐2‐phosphonic acid (AIP, 3 ), a known powerful inhibitor of PAL, racemic 1‐aminobenzocyclobutene‐1‐phosphonic acid ( 4 ), was six times weaker than AIP as an in vitro inhibitor of buckwheat PAL, but six times stronger than AIP as an in vivo inhibitor of phenylalanine‐derived anthocyanin synthesis in buckwheat.     

Application of NMR spectroscopy for assignment of the absolute configuration of 8‐tert‐butyl‐2‐hydroxy‐7‐methoxy‐8‐methyl‐9‐oxa‐6‐azaspiro[4.5]dec‐6‐en‐10‐one

In order to assign the absolute configurations of 8‐tert‐butyl‐2‐hydroxy‐7‐methoxy‐8‐methyl‐9‐oxa‐6‐azaspiro[4.5]dec‐6‐en‐10‐one ( 2a , 2b ), their esters ( 5a , 5b , 5c , 5d ) with (R)‐ or (S)‐2‐methoxyphenylacetic acid ( 4a , 4b ) have been synthesized. The absolute configurations of these compounds have been determined on the basis of NOESY correlations between the protons of the tert‐butyl group and the cyclopentane fragment of the molecules. The crucial part of this analysis was assignment of the absolute configuration at C‐5. Additionally, by calculation of the chemical shift anisotropy, δ^RS, for the relevant protons, it was also possible to confirm the absolute configurations at the C‐2 centres of compounds 2a , 2b and 5a , 5b , 5c , 5d . Chirality, 25:422–426, 2013.© 2013 Wiley Periodicals, Inc.