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This study presents an intersection of two seemingly separate areas of research frontiers, “prediction and control of thermoacoustic instability” and “stability analysis of neutral-class linear-time-invariant (LTI) and time-delayed systems (TDS)”. The former is a coveted capability which has been elusive to the scientific community over 1½ centuries. Analytical capabilities have been limited due to the complex physics invoking the “combustion” phenomenon. Most available results rely on accumulated empirical knowledge. In this paper we consider a benchmark combustion test platform, which is known as Rijke’s tube. Its representation is simplified to an LTI neutral TDS, stability of which is assessed using a recent mathematical paradigm called the Cluster Treatment of Characteristic Roots (CTCR). CTCR provides a unique non-conservative and exhaustive stability declaration for a Rijke’s tube within the space of its parameters, naturally, under some simplifying assumptions. For those operating conditions which induce instability, we also propose a conventional and simple control strategy which can recover stability. This method is also analyzed using the CTCR paradigm for the first time.Copyright © 2014 by ASME

Bladed disks in turbomachinery are commonly designed to operate within a very small clearance from the stationary shroud (casing). For variety of reasons, however, they interfere with each other during routine operation which results in undesirable vibrations. The novel idea in this paper originates from the claim that this dynamics is inherently akin to internal machining operation which uses compliant cutters (blades) with relatively rigid workpiece (casing). It is known that machining processes suffer from a phenomenon called chatter, which has been studied over decades to a considerable extend. We propose a new perspective to investigate the stability of blade-casing contact vibrations by a modeling approach borrowed from chatter literature. The mathematical model arises with a signature time-delayed dynamics for which we utilize a recent analytical tool called the Cluster Treatment of Characteristic Roots (CTCR). We present an exhaustive stability analysis and study the effects of altering damping characteristics in the casing structure.Copyright © 2014 by ASME

A combination of a thiourea tagged calixarene and L-proline is disclosed as catalyst for the aldol condensation of cyclohexanone and aromatic aldehydes.

In this paper we introduce a novel combination of Sign Inverting Control (SIC) and Delay Scheduling (DS) concepts for systems with multiple rationally independent and large delays. The combined scheme functions with a single premise that, the union of a proper choice of control and its sign inverted version (SIC) would provide a larger stable operating region in the domain of the delays. The outstanding question to properly perform this novel control strategy is the crisp knowledge of the stable operating regions for each of the two control schemes. This question is uniquely answered using the CTCR (Cluster Treatment of Characteristic Roots) paradigm. CTCR declares the stable regions very efficiently and exhaustively with no conservatism. The resulting switched operating mode renders more robust control performance against much larger delay variations vis-a-vis each of the schemes. For unstable delay compositions, a paradoxical scheme called the Delay Scheduling Control (DS) is deployed by increasing the present delays in order to regain stability. The crucial question of “how much increase in delays?” can also be answered by the CTCR without conservatism. The combination of Sign Inverting Control (SIC) and Delay Scheduling Control (DS) schemes provides previously-unexplored tools to control designers. Experimental validations of these methodologies are provided on a simple setup with a single-axis manipulator.

New aryl butenoic acid derivatives have been synthesized by combining hydroxy- or methoxy-substituted phenyl rings as the capping group, with a double bond in the short linker as well as metal binding groups, enoic ester, and salts bearing either methyl or morpholine. These compounds have been shown to possess promising histone deacetylase inhibition activities via in vitro fluorometric assay and molecular docking studies.

WOS: 000329090500017, The self-condensation reaction of benzoyl dialkyl phosphonates was developed using cyanide ion as catalyst, affording versatile tertiary O-protected alpha-hydroxy phosphonates in moderate yield.

(1S,2R)-1-amino-2-indanol, a key component of an HIV protease inhibitor is synthesized in four steps starting from indanone. The Mn(OAC)3 mediated acetoxylation of indanone followed by fungus catalyzed hydrolysis of acetoxyindanone furnished optically pure a-hydroxy indanone. Formation and enantioselective reduction of oxime ether of 2-hydroxyindanone afforded (1S, 2R)-1-amino-2-indanol in 97% {\it cis} selectivity.

A new efficient and cost-effective method for the preparation of 1,2-amino alcohols is described. The reactions of amino acids with NaBH4 in the presence of NiCl2 or MoO3 in water give 1,2-amino alcohols in high yield. When optically pure amino acids were used, optically pure 1,2-amino alcohols were obtained.

A proline–thiourea host–guest complex is described as a self-assembled organocatalyst for the enantioselective Michael addition of aldehydes to nitroolefins and for the asymmetric α-aminoxylation of both aldehydes and ketones. The Michael adducts were obtained in good yields of up to 80%, high diastereoselectivities of up to 5:95, and high enantiomeric excesses of up to 98%. The optically active aminoxy alcohols were synthesized in 60–85% yields with 94–99% enantiomeric excesses after reduction of the α-oxidation products using NaBH 4 .

The reaction of phenylhydrazines with benzene in the presence of manganese(III) acetate affords biaryls in good yields. The same reaction was carried out with similar oxidants, such as CoIII, CeIV and PbIV; among these oxidants MnIII acetate shows higher efficiency and selectivity.

The selective conversion of 2,2,2-trifluoro-1-furan-2-yl-ethanone into ( E )- and ( Z )-oximes and oxime ethers and subsequent oxazaborolidine-catalyzed enantioselective reduction using different amino alcohols furnished both enantiomers of the important chiral building block 2,2,2-trifluoro-1-furan-2-yl-ethylamine with e.e. of up to 88%. Oxidation of the furan ring afforded both enantiomers of 3,3,3-trifluoroalanine in 91–93% yields.

A chemoenzymatic synthesis of pharmacological interesting ( R )-2-hydroxypropiophenones starting from propiophenone derivatives is described. Manganese(III) acetate-mediated acetoxylation followed by fungus-mediated hydrolysis of propiophenone derivatives affords ( R )-2-hydroxypropiophenones in high enantiomeric excess.

The reaction of tetramethyldiamidophosphoric acid chloride with epoxides in the presence of a trace amount of water furnished 1,3-dienes in good yield. The conversion works with open chain and cyclic epoxides. A C–C bond cleavage reaction occurs if the epoxide contains a quaternary carbon. Application of this method to epoxy sterols afforded ring A aromatic steroids in good yield. The aromatization works via dienol-benzene rearrangements and is independent of the C-3 stereochemistry.

Chiral 2-hydroxypropanone derivatives 5a−v, 8a−d, and 10a, b were formed by benzoylformate decarboxylase (BFD) catalyzed C−C bond formation. A donor aldehyde and acetaldehyde as an acceptor were carboligated in aqueous buffer solution with remarkable ease in high chemical yield and good to high optical purity. The substrate range of this thiamin diphosphate dependent enzyme was examined to employ this benzoin condensation type reaction in stereoselective synthesis. The observed dependence of the enantiomeric excess on the substitution pattern could be exploited to design substrates resulting in high selectivity. Best substrates with regard to optical purity were meta-substituted benzaldehyde derivatives. To enable a general and convenient applicability of the BFD-catalyzed C−C bond formation, analytical batch experiments were scaled up to give (S)-2-hydroxy ketones in good to high yields on a preparative scale. Further, the solubility of some of the organic substrates in aqueous solution was increased by the use of cyclodextrin or buffer/DMSO mixtures.

The thiamin diphosphate- and Mg2+-dependent enzyme benzoylformate decarboxylase (BFD) from Pseudomonas putida was characterized with respect to its suitability to catalyze the formation of chiral 2-hydroxy ketones in a benzoin-condensation type reaction. Carboligation constitutes a side reaction of BFD, whereas the predominant physiological task of the enzyme is the non-oxidative decarboxylation of benzoylformate. For this purpose the enzyme was obtained in sufficient purity from Pseudomonas putida cells in a one-step purification using anion-exchange chromatography. To facilitate the access to pure BFD for kinetical studies, stability investigations, and synthetical applications, the coding gene was cloned into a vector allowing the expression of a hexahistidine fusion protein. The recombinant enzyme shows distinct activity maxima for the decarboxylation and the carboligation beside a pronounced stability in a broad pH and temperature range. The enzyme accepts a wide range of donor aldehyde substrates which are ligated to acetaldehyde as an acceptor in mostly high optical purities. The enantioselectivity of the carboligation was found to be a function of the reaction temperature, the substitution pattern of the donor aldehyde and, most significantly, of the concentration of the donor aldehyde substrate. Our data are consistent with a mechanistical model based on the X-ray crystallographic data of BFD. Furthermore we present a simple way to increase the enantiomeric excess of (S)-2-hydroxy-1-phenyl-propanone from 90% to 95% by skillful choice of the reaction parameters. Enzymatic synthesis with BFD are performed best in a continuously operated enzyme membrane reactor. Thus, we have established a new enzyme tool comprising a vast applicability for stereoselective synthesis.

The synthesis of (1S,2R)-1-amino-2-indanol, a key component of HIV protease inhibitor is accomplished in four steps starting from indanone efficiently and with high levels of diastereo- and enantioselectivity. The starting material is converted into 2-acetoxy-1-indanone involving Manganese (III) acetate oxidation . The 2-acetoxyketone is hydrolyzed to 2-hydroxy-1-indanone enantioselectively using Rhizopus oryzae. Selective reduction of 2-hydroxyoxime derivative, derived from the 2-hydroxyketone, gives the amino alcohol up to 98% diastereo- and enantioselectivity.

The first catalytic intermolecular aldehyde-ketone coupling via acyl phosphonate is reported. Acyl phosphonates are potent acyl anion precursors, which generate acyl anion equivalents under the influence of cyanide anion via phosphonate-phosphate rearrangement. These anions readily react with activated ketones to form acyloin type coupling in 41-95% yields.

Aromatic aldehydes are converted into benzoins by benzoylformate decarboxylase catalyzed C–C bond formation. The reaction affords ( R )-benzoins with high enantiomeric excess and in good chemical yields. A broad range of aromatic aldehydes can be used as substrates in aqueous buffer or buffer/DMSO-solutions.

A procedure was developed for the annelation of a butenolide to an aromatic ketone that highlighted a manganese(III) oxidation of an aromatic ketone. The merit of this procedure was illustrated in a synthesis of Chromolaenin (Laevigatin) (1) from 4,7-dimethyl-1-tetralone (2c). Oxidation of tetralone and indanone with manganese(III) acetate in the presence of chloro- or bromopropionic acid or their Mn(II) salts furnished a α-haloesters 3a-d. An Arbuzov reaction of haloesters with triethylphosphite and an intramolecular Horner-Watsworth-Emmons cyclization of the resulting phosphonate gave butenolide 5a, b in 77-79% yield. This methodology was also applied to 4,7-dimethyl-1-tetralone (2c), and the corresponding butenolide 6 is synthesized in 85% yield, which was then converted to Chromolaenin (1) using DIBAL-H.Key words: chromolaenin (Laevigatin), manganese(III) acetate oxidation, aromatic ketones, butenolide annelation, lactone, Horner-Watsworth-Emmons cyclization, Arbuzov reaction.

A general procedure was developed for the annelation of a butenolide to an aromatic ketone that highlighted a manganese(III) oxidation of aromatic ketones. The oxidation of aromatic ketones with manganese(III) acetate in the presence of 2-bromoacetic acid or the Mn(II) salt of this carboxylic acid provided a regioselectively convenient synthesis of 2-(2-bromoacetoxy) ketones. An Arbuzov or Wittig reaction of 2-(2-bromoacetoxy) ketones followed by cyclisation furnished 4-arylfuran-2(5H)-ones in good yield.

Mn(OAc)3 oxidation of aromatic ketones afforded the α-acetoxy ketones in good yield. Selective hydrolysis of the acetoxy ketones by the fungus Rhizopus oryzae yields (R)-hydroxy ketones in high enantiomeric excess.

d - and l -α-(2-carboxycycloprop-1-yl)glycines were synthesized from trans -1,3-di(2-furyl)propenone. Conversion of the double bond to a cyclopropane is followed by the formation of an oxime ether. Enantioselective reduction of the oxime ether, separation of diastereomers and oxidation of the furane rings gave enantiomerically pure d - and l -CCG I and CCG II. The structure of oxime 7b was determined by X-ray crystal structure analysis. The key step is the oxazaborolidine catalyzed enantioselective conversion of oxime ethers to amines.

The host–guest complex of a proline–thiourea bipyridine trifluoromethanesulfonic acid salt can catalyze organocatalytic asymmetric reactions such as aldol, Michael, and Mannich in polar protic medium with high stereoselectivities. The privileged bipyridine backbone and the thiourea motif are essential to the activity and enantioselectivity through hydrogen bonding interactions.

Different aliphatic and aromatic acyl phosphonates were synthesized using Arbuzov reaction and subjected to Oxo-Diels-Alder (ODA) reaction with 2,3-dimethyl-1,3-butadiene at -78 degrees C. AlCl3 was found the best catalyst to obtain the desired ODA products from acyl phosphonates in only 30min at low temperature, as compared to 100 degrees C-previously reported. The same reaction was repeated at room temperature but, instead of ODA, Wittig-type product was obtained. All the products were characterized by NMR spectroscopy and mass spectrometry. H-1,P-31 and C-13,P-31 couplings were observed in the NMR spectra.

A new method for the direct conversion of oximes into aldehydes and ketones by treatment with manganese triacetate is described. Manganese triacetate can be used for an effective and mild oxidizing agent for the regeneration of carbonyl compounds from oximes in good yield. Many functional groups are tolerated under the reaction conditions.

(±)-Mintlactone has been synthesized by applying a novel effective synthetic sequence. 4-Methylcyclohexanone was subjected to acetoxylation with Pb(OAc)4. Hydrolysis followed by reaction with 2-chloropropionyl chloride, then treatment with triethyl phosphite and, finally, Horner-Emmons-type intramolecular cyclization afforded (±)-Mintlactone.

5-Chloro-3-penten-2-one reacts with the amino group of homochiral amines, amino alcohols, amino acid esters to form corresponding 2-pyrrole derivatives in good yield and without racemization.

Cyclic 1,3- diketones 1 are transformed into their 2,2-dimethylhydrazones 2, which can be alkylated regio-selectively at different positions after mono-, di-, tri-, and tetrametalation. Monometalated C-2 unsubstituted hydrazones afford C-2 and N-alkylation, monometalated C-2 substituted hydrazones afford only C-2 alkylation. The regioselectivity of the alkylation of the polymetalated hydrazones follows Hauser's rule according to the sequence: NH- > C-4 Ha > C-5 > C-4 Hb. Hydrolysis of the product hydrazones 3–5 afforded mono- and polyalkylated 1,3- diketones 7 in good yields.

New catalysts have been prepared from (S)- and (R)- proline and the asymmetric borane reduction of prochiral ketones using these catalysts has been studied. The secondary alcohols were obtained in 76–95% yield with 57– 96% enantiomeric excesses.

The alkylation of l- and d-menthyl valerate with n-hexyl iodide and with (20S)-20-iodomethyl-4α-methyl-5α-pregnane gave modest levels of diastereoselection. The chirality of the ester group favoured slight degree of selectivity. The chiral centers had limited impact on diastereoselectivity

2-Substituted epichlorohydrins have been synthesized by starting with 1,2-dichloro acetone and various alkyl and aryl halides via dichlorohydrins followed by cyclization. The reactive 2-substituted epichlorohydrins were subjected to nucleophilic attacking of azide and cyanide ions to afford corresponding β-azido alcohols and α,β-unsaturated nitriles.

(±)-6-Acetoxy-3-methylcyclohex-2-en-1-one was resolved by PLE catalyzed hydrolysis to afford (+)-6-hydroxy-3-methylcyclohex-2-en-1-one in >95% e.e. (+)-6-Hydroxy-3-methylcyclohex-2-en-1-one was transformed to its ( S )-O-acetyllactyl ester derivative to determine the e.e. %.

In this study, magnetic nanoparticles (Fe3 O4 , magnetite) with immobilized metal affinity ligands (MSS) were prepared and characterized by X-ray diffraction (XRD), transmission electron microscopy (TEM), fourier transform infrared spectroscopy (FTIR), and vibrating-sample magnetometer (VSM) methods for purification and immobilization of the histidine-tagged recombinant benzoylformate decarboxylase (BFD). The MSS support was shown to be eligible for selective binding of HIS-tagged BFD by SDS-page analysis. Loading capacity of the MSS support was determined as 43.6 ± 1.1 mg/g. The regeneration ability for protein binding was also studied. An immobilized BFD was tested to catalyze benzoin condensation and representative cross acyloin reaction. Conversion and enantiomeric excess values were comparable with that of free enzyme catalyzed reactions.

In this study, magnetic nanoparticles (Fe3O4, magnetite) with immobilized metal affinity ligands (MSS) were prepared and characterized by X-ray diffraction (XRD), transmission electron microscopy (TEM), fourier transform infrared spectroscopy (FTIR), and vibrating-sample magnetometer (VSM) methods for purification and immobilization of the histidine-tagged recombinant benzoylformate decarboxylase (BFD). The MSS support was shown to be eligible for selective binding of HIS-tagged BFD by SDS-page analysis. Loading capacity of the MSS support was determined as 43.6 +/- 1.1mg/g. The regeneration ability for protein binding was also studied. An immobilized BFD was tested to catalyze benzoin condensation and representative cross acyloin reaction. Conversion and enantiomeric excess values were comparable with that of free enzyme catalyzed reactions. (C) 2013 Wiley Periodicals, Inc.

Epoxy-functionalized Fe3O4-SiO2 core-shell magnetic nanoparticles (epoxy-M-support) were prepared by modification with glycidyloxypropyltrimethoxysilane (GPTMS) and characterized by X-ray diffraction (XRD), transmission electron microscopy (TEM), and fourier transform infrared spectroscopy (FTIR) methods. Pure histidine-tagged recombinant benzaldehydelyase (BAL, EC 4.1.238) was efficiently immobilized onto the epoxy-M-support with covalent binding. An immobilized BAL epoxy-M-support system was tested to catalyze the self and cross condensation reactions of aldehydes, and the kinetic resolution of racemic acyloins. The acyloin products were obtained in high yield and with high enantiomeric excesses (>= 98% ee). The carboligation reactivity of the immobilized enzyme was comparable to that of free enzyme-catalyzed reactions. The covalent immobilization offers high enzyme activity and stability (at least 5 repeats without losing its activity). (C) 2013 Elsevier Ltd. All rights reserved.

In this work, histidine-tagged recombinant benzaldehyde lyase from Pseudomonas fluorescens Biovar I (BAL, EC 4.1.2.38) was immobilized on the magnetically responsive epoxy-chelate magnetic support following a two-step mechanism; that is, the protein is physically adsorbed and then the covalent bonding takes place. This mechanism has been exploited to combine the selectivity of metal chelate affinity chromatography with the covalent immobilization capacity of epoxy supports. In this way, it has been possible to accomplish, in a simple manner, the purification, immobilization, and stabilization of a histidine-tagged recombinant benzaldehyde lyase. To fulfill this objective we prepared and characterized a multifunctional Co 2+ -IDA-epoxy functionalized the silica coated magnetic nanoparticles (SCMPs) which are modified with glycidyloxypropyltrimethoxysilane (GPTMS) and iminodiacetic acid (IDA). To test immobilized BAL, benzoin condensation reaction was performed with this magnetically responsive biocatalyst. The results obtained from the carboligation reaction that was performed with this simple and convenient heterogeneous biocatalyst were comparable to that of free-enzyme-catalyzed reaction. Additional advantages are its reusability and it is easy to work with.

Objective: As there is continuing disagreement among the observers on the differential diagnosis between the epithelial changes/lesions and neoplasms of the gallbladder, this multicentre study was planned in order to assess the rate of the epithelial gallbladder lesions in Turkey and to propose microscopy and macroscopy protocols. Material and Method: With the participation of 22 institutions around Turkey that were included in the Hepato-Pancreato-Biliary Study Group, 89,324 cholecystectomy specimens sampled from 2003 to 2016 were retrospectively evaluated. The numbers of adenocarcinomas, dysplasias, intracholecystic neoplasms/adenomas, intestinal metaplasias and reactive atypia were identified with the review of pathology reports and the regional and countrywide incidence rates were presented in percentages. Results: Epithelial changes/lesions were reported in 6% of cholecystectomy materials. Of these epithelial lesions, 7% were reported as adenocarcinoma, 0.9% as high-grade dysplasia, 4% as low-grade dysplasia, 7.8% as reactive/regenerative atypia, 1.7% as neoplastic polyp, and 15.6% as intestinal metaplasia. The remaining lesions (63%) primarily included non-neoplastic polypoids/hyperplastic lesions and antral/pyloric metaplasia. There were also differences between pathology laboratories. Conclusion: The major causes of the difference in reporting these epithelial changes/lesions and neoplasms include the differences related to the institute’s oncological surgery frequency, sampling protocols, geographical dissimilarities, and differences in the diagnoses/interpretations of the pathologists. It seems that the diagnosis may change if new sections are taken from the specimen when any epithelial abnormality is seen during microscopic examination of the cholecystectomy materials. © 2018, Federation of Turkish Pathology Societies. All rights reserved.

This review describes the input of sol-gel chemistry to the immobilization of polyol dehydrogenases on electrodes, for applications in bioelectrocatalysis. The polyol dehydrogenases are described and their application for biosensing, biofuel cell and electrosynthesis are briefly discussed. The immobilization of proteins via sol-gel approaches is described, including a discussion on the difficulty to maintain the activity of proteins in a silica matrix and the strategies developed to offer a proper environment to the proteins by developing optimal organic-inorganic hybrid materials. Finally, the co-immobilization of the NAD + co-factor and of mediators for the elaboration of reagentless devices is presented, based on published and original data. All-in-all, sol-gel approaches appear to be a very promising for development of original electrochemical applications involving dehydrogenases in near future.

Delayed resonators (DR) are a class of active vibration absorbers, where resonance in the absorber is achieved through a delayed feedback control. Studies on DR theory so far, have focused on traditional mechanical absorber structures with proof masses. Both in linear and rotational vibration applications, a mechanical substructure is brought to resonance; which, in turn, absorbs vibration from the primary structure. This study is a departure from the existing literature in the sense that the mechanical absorber structure is replaced by an electrical circuit that resonates. The tuning is achieved by the use of piezoelectric elements, which introduce a coupling between the mechanical and electrical components in the system. The resonance and desired vibration absorption are still the objectives but with a distinct feature, 'without a proof mass'. This work unites the two fronts of research from this interesting angle, namely DR theory and piezoelectric networks, to benefit from their individual strengths.

Introduction: Breast reduction is listed among the most commonly performed operations in plastic surgery. Even so, many different techniques, pedicles, scars and approaches have been defined. A retrospective study was undertaken in our clinic to evaluate the changes in techniques and approach within the last decade. Material and Methods: For this purpose, all breast reductions surgeries performed within 2001, 2006 and 2010 were evaluated. After the demographic data was collected, a technical evaluation was done to determine the choice of pedicle, the choice of scar, and scar preference according to the pedicle in the three different time frames. Results: A total of 40 reduction mammoplasty cases were performed during 2001, while this number was 107 for 2006, and 168 for 2010. The surgical team was similar regarding the three time frames. In 2001, the main choice in pedicle was the inferior pedicle while the Wise pattern was the preferred scar of choice. In 2006, the superomedial pedicle was also highly preferred alongside the inferior pedicle while the choice in scar was the same. In 2010, the superomedial-lateral pedicles were the dominant choice in technique while there was an increase in verticolateral scars. Conclusions: Breast reduction surgeries are among the most versatile operations in plastic surgery. The reason behind this versatility is the different advantages and disadvantages that come with each technique. Furthermore, the more experienced the surgeon gets, the more likely they note these disadvantages and start to look for ways to overcome them. We believe that the changes in the three different time frames are reflective of this development.

The asymmetric Michael addition of aldehydes to nitroolefins was investigated using a combination of l -prolinamide derivatives and various acidic additives. ( S )-1,1′-Bi-2-naphthol was found to be the most effective co-catalyst and afforded the nitroaldehyde products with excellent yields (up to 95%), enantiomeric excesses (up to 99%) and diastereoselectivity ratios (up to 99:1).