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Switch
Kinds of Switch Terms modified by Switch Selected AbstractsConvenient Synthesis of Tetrahydro-,-carbolines and Tetrahydroquinolines through a Chemo- and Regioselectivity Switch by a Brønsted Acid Catalyzed, One-Pot, Multicomponent ReactionEUROPEAN JOURNAL OF ORGANIC CHEMISTRY, Issue 26 2010Hong-Gang Cheng Abstract An efficient, one-pot, multicomponent reaction of aldehydes 1, p -methoxyaniline (2a), and 2-vinylindoles 3 was developed. This approach provides a practical approach to synthetically and biologically significant tetrahydro-,-carboline and tetrahydroquinoline derivatives in good yields through a chemo- and regioselectivity switch, which can be tuned by simply changing the substituent on the indole component under identical reaction conditions. [source] Comparison between objective and subjective measurements of quality of service over an Optical Wide Area networkEUROPEAN TRANSACTIONS ON TELECOMMUNICATIONS, Issue 3 2008Francesco Matera The introduction of intelligence for management and control of the quality of service (QoS) are key issues for the evolution of the next generation IP optical network based on Ethernet technology. A test bed of a core-access network was implemented to investigate such issues and in this paper, the authors report measurements concerning the QoS of multimedia services for different traffic conditions. The network was implemented with a differentiated service over Multi-Protocol Label Switch (MPLS) architecture; it consists of a real optical network based on core routers with optical Gigabit Ethernet (GBE) interfaces connected by means of long single mode fibres (about 50\,km), contained in an installed cable between Rome and Pomezia. The network is based on different access devices, but in this paper we only refer to an access based on Fibre To The building (FTTB) architecture. The QoS was investigated both in terms of network (or objective) tests that include packet loss, jitter, one way delay and throughput measurements and perceptive (or subjective) tests that conversely are based on the evaluation of user perception. The services under test mainly consisted of video streams that circulated in the network according to the switching operations based in the IP differentiated service over MPLS technique that allowed us to guarantee the QoS for some class of service, also in the presence of network overload. Particular attention was given to the correlation between objective and subjective measurements. Furthermore, in order to have a complete analysis about QoS of real networks, measurements were performed also in the presence of restoration operations for link failures; in particular we compare the results in the case of conventional IP network restoration with a procedure proposed by us and based on a link switching activated by the loss of signal command coming from the routers. Copyright © 2007 John Wiley & Sons, Ltd. [source] Design of a Multistage Optical Packet SwitchEUROPEAN TRANSACTIONS ON TELECOMMUNICATIONS, Issue 5 2000Carla Raffaelli Optical packet switching is considered as a means to achieve high speed networking in future optical multi-service networks, Optical switches of limited size are feasible with present-day photonic technology, so solutions for the design and implementation of large switches are proposed here. They are based on a multistage architecture built using small switching modules with output queuing, organised according to a Clos topology. Many degrees of freedom are available for switch design and they are exploited to achieve performance optimisation in relation to packet loss. Simulation and analytical tools are developed to evaluate switch architecture performance. Results and application examples are given to show the feasibility of the multistage architecture for optical networking. [source] Performance Evaluation of the KEOPS Wavelength Routing Optical Packet SwitchEUROPEAN TRANSACTIONS ON TELECOMMUNICATIONS, Issue 1 2000Philippe Cadro This paper presents results concerning the performance evaluation of the KEOPS wavelength routing optical transparent packetswitch. This switch solves contention using optical delay lines; these delay lines are grouped in several sets, in the first stage of the switch. Each input port has access to a few of these delay lines, and each set of delay lines has access to each output port. Non-FIFO output buffers are thus emulated using scheduling on a small number of delay lines with non-consecutive delays. Under simplifying assumptions, analytical models are derived, and checked by simulation. These models provide efficient bounds for estimating packet loss probability, under the assumption of regular, balanced input traffic. It is shown that the proposed switch architecture achieves a good performance in terms of packet loss, with a number of delay lines significantly smaller than the ones currently used in other architectures. [source] Switch to oral hypoglycemic agent therapy from insulin injection in patients with type 2 diabetesGERIATRICS & GERONTOLOGY INTERNATIONAL, Issue 4 2008Takashi Okamoto Aim: We aimed to determine the feasibility of substituting thiazolidinedione-based therapy for insulin injection therapy in patients with type 2 diabetes. Methods: Thirty-six subjects (17 men and 19 women) aged 67.8 ± 11.3 years with an average insulin dose of 0.46 ± 0.17 U/kg bodyweight, a duration of insulin therapy of 6.1 ± 8.2 years and an average hemoglobin A1c (HbA1c) of 6.8 ± 1.3% were switched from insulin injection therapy to pioglitazone, glimepiride and voglibose combination therapy. Results: The number of subjects achieving HbA1c levels of less than 7% at 4 months was 30. The success rate of switch therapy was 83% (30/36). HbA1c was significantly reduced from 6.7 ± 1.3% to 5.9 ± 0.7% at 4 months after the switch (P < 0.01) in 32 patients who completed the planned 4-month study. No adverse effects including heart failure, liver dysfunction or severe hypoglycemia were observed. The insulin dose and the maximum blood glucose on the switch day were significantly lower and the age was significantly higher in the subjects who achieved HbA1c less than 7% at 4 months compared to those who did not (P < 0.05). Conclusion: Thiazolidinedione-based oral combination therapy may efficiently and safely substitute relatively high-dose insulin injection therapy in patients with type 2 diabetes. [source] p.Gln200Glu, a putative constitutively active mutant of rod ,-transducin (GNAT1) in autosomal dominant congenital stationary night blindness,,HUMAN MUTATION, Issue 7 2007Viktoria Szabo Abstract Congenital stationary night blindness (CSNB) is a non-progressive Mendelian condition resulting from a functional defect in rod photoreceptors. A small number of unique missense mutations in the genes encoding various members of the rod phototransduction cascade, e.g. rhodopsin (RHO), cGMP phosphodiesterase ,-subunit (PDE6B), and transducin ,-subunit (GNAT1) have been reported to cause autosomal dominant (ad) CSNB. While the RHO and PDE6B mutations result in constitutively active proteins, the only known adCSNB-associa-ted GNAT1 change (p.Gly38Asp) produces an ,-transducin that is unable to activate its downstream effector molecule in vitro. In a multigeneration Danish family with adCSNB, we identified a novel heterozygous C to G transversion (c.598C>G) in exon 6 of GNAT1 that should result in a p.Gln200Glu substitution in the evolutionarily highly conserved Switch 2 region of ,-transducin, a domain that has an important role in binding and hydrolyzing GTP. Computer modeling based on the known crystal structure of transducin suggests that the p.Gln200Glu mutant exhibits impaired GTPase activity, and thereby leads to constitutive activation of phototransduction. This assumption is in line with our results of trypsin protection assays as well as previously published biochemical data on mutants of this glutamine in the GTPase active site of ,-transducin following in vitro expression, and observations that inappropriately activating mutants of various members of the rod phototransduction cascade represent one of the major molecular causes of adCSNB. © 2007 Wiley-Liss, Inc. [source] Long-term safety and efficacy of long-acting risperidone in elderly psychotic patientsHUMAN PSYCHOPHARMACOLOGY: CLINICAL AND EXPERIMENTAL, Issue 8 2007Werner Kissling Abstract This subgroup analysis of the 6-month, open-label Switch to Risperidone Microspheres (StoRMi) trial evaluated long-term safety and efficacy of a direct conversion to risperidone long-acting injectable (RLAI) in 52 elderly patients (,65 years) with psychosis stabilized on oral or depot antipsychotic. Study outcomes included adverse events, movement disorder severity, psychiatric symptoms, functional ability, quality of life and patient satisfaction. Change in the Positive and Negative Syndrome Scale at endpoint was the primary efficacy measure. The most common dosage of RLAI used at endpoint was 25,mg every 14 days (60%). The trial was completed by 81% of patients, with six patients discontinuing treatment due to an adverse event. Tolerability was good and most side effects were mild to moderate. Serious adverse events occurred in 11 patients. Two of these (suicidal attempt, n,=,1; exacerbation of disease, n,=,1) were considered possibly related to RLAI. Conversion to RLAI resulted in significant improvements in movement disorder severity, psychiatric symptoms, functional status and patient satisfaction. Mean PANSS total decreased by 15.8 at endpoint, with 23 patients (46.9%) experiencing a ,20% improvement. This post-hoc analysis supports that RLAI is well tolerated and safe in elderly patients with psychotic illnesses switched from stable antipsychotic regimens, and suggests possible efficacy, although inferences are limited. Copyright © 2007 John Wiley & Sons, Ltd. [source] System aspects of 1100 kV AC transmission technologies in JapanIEEJ TRANSACTIONS ON ELECTRICAL AND ELECTRONIC ENGINEERING, Issue 1 2009Eiichi Zaima Senior Member Abstract This paper describes the system aspects of 1100 kV AC transmission technologies with the UHV transmission project in Japan. For realization of technical and economical optimization throughout the design of the transmission line and the substation, solutions for network problems and insulation coordination specific to UHV AC transmission systems were studied in Japan. They include fast multiphase reclosing systems by HSGS (High Speed Grounding Switch) and overvoltage control by the application of surge arresters and circuit breakers with closing/opening resistors. These sophisticated technologies provide highly reliable and economical 1100 kV substations and transmission lines. Copyright © 2009 Institute of Electrical Engineers of Japan. Published by John Wiley & Sons, Inc. [source] A New Molecular Switch Based on Helical BiladienoneADVANCED MATERIALS, Issue 19 2006E. Matsui A molecular field-effect switch (FES) employing zinc biladienone as the active element is reported (see figure). The switching mechanism is investigated and a new FES switching mechanism is proposed in which the molecules separate from the electrodes and their molecular orientation changes when a gate voltage is applied. [source] A Solid-State Organic Electronic Wettability Switch,ADVANCED MATERIALS, Issue 4 2004J. Isaksson Solid-state devices based on soluble polymers on a rigid substrate, with the active surface facing the environment, have been designed and characterized. The contact angles and spreading of water droplets can be reversibly controlled by electrochemically reducing or oxidizing a polymer surface (see Figure). [source] High isolation microstrip GaN-HEMT Single-FET SwitchINTERNATIONAL JOURNAL OF RF AND MICROWAVE COMPUTER-AIDED ENGINEERING, Issue 4 2010Walter Ciccognani Abstract In this contribution an analytical approach to the design of high-isolation microwave transmission line-resonated switches is presented. Simulated and measured performance of a GaN HEMT single-FET switch cell topology and the one of a complete SPDT using the proposed approach are presented to demonstrate the approach feasibility and effectiveness. The resulting SPDT, operating at X Band, is featured by 1 dB insertion loss, isolation better than 37 dB all over the operating bandwidth and a power handling capability higher than 39 dBm. © 2010 Wiley Periodicals, Inc. Int J RF and Microwave CAE, 2010. [source] Determination of cyprodinil and fludioxonil in the fermentative process of must by high-performance liquid chromatography,diode array detectionJOURNAL OF THE SCIENCE OF FOOD AND AGRICULTURE, Issue 11 2008Luis Vaquero-Fernández Abstract BACKGROUND: A quantitative, selective and sensitive high-performance liquid chromatographic method is described for the analysis of new fungicides cyprodinil, fludioxonil and their commercial formulation Switch in model solutions of must and wine, as well as samples during alcoholic fermentation. A study of the dissipation of residues was carried out. RESULTS: The proposed method is based on liquid,liquid extraction (LLE) followed by high-performance liquid chromatography and diode array detection. Dichloromethane was the most appropriate solvent for extracting cyprodinil and fludioxonil in samples. Quality parameters of the proposed method presented good recovery (ca. 97% for almost all compounds) and precision (between 4.8% and 5.4%), and limits of quantification were lower than maximum residue limits (MRLs) in grapes. CONCLUSIONS: There is no matrix effect in the analysis of cyprodinil and fludioxonil. The application of the fermentative process on cyprodinil and fludioxonil fungicides causes a decrease in the concentrations of these compounds. This decrease is slightly higher, the higher the initial concentration, without observing the appearance of any product in degradation. Fludioxonil shows a higher reduction when the compounds are presented together in Switch. Copyright © 2008 Society of Chemical Industry [source] Design of a 3,10 GHz UWB CMOS T/R switchMICROWAVE AND OPTICAL TECHNOLOGY LETTERS, Issue 2 2008K.-H Pao Abstract A 3,10 GHz broadband CMOS T/R Switch for ultra-wideband (UWB) transceiver is proposed. This broadband CMOS transmit/receive (T/R) Switch is fabricated based on the 0.18 ,m 1P6M standard CMOS process. On-chip measurement of the CMOS T/R Switch is performed. The insertion loss of the proposed CMOS T/R Switch is about 3.1 ± 1.3 dB. The return losses at both input and output terminals are higher than 14 dB. It is also characterized with 25,34 dB isolation and 18,20 dBm input P1dB. The broadband CMOS T/R Switch shows highly linear phase and group delay of 20 ± 10 ps from 10 MHz to 15 GHz. It can be easily integrated with other CMOS RFICs to form on-chip transceivers for various UWB applications. © 2007 Wiley Periodicals, Inc. Microwave Opt Technol Lett 50: 457,460, 2008; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.23129 [source] Delayed Restoration of Atrioventricular Synchrony with Beat-to-Beat Mode SwitchPACING AND CLINICAL ELECTROPHYSIOLOGY, Issue 8 2001FRANK BODE BODE, F., et al.: Delayed Restoration of Atrioventricular Synchrony with Beat-to-Beat Mode Switch. This case report describes a patient with complete AV block and a VDD pacemaker who experienced repetitive episodes of symptomatic bradycardia. Episodes occurred due to activation of an automatic beat-to-beat mode switch algorithm. After mode switch to VDI operation, the pacemaker failed to immediately switch back to AV synchronous pacing when regular sinus rhythm (, 100 beats per minute) resumed despite adequate P wave sensing. Dizziness was felt for up to several minutes of asynchronous pacing at the lower rate limit until VDD mode was restored. Episodes were completely eliminated by programming the mode switch function from an automatic beat-to-beat algorithm to a fixed rate algorithm. [source] The Importance of Skin Cancer Prevention in Organ Transplant Patients An Editorial to Paper by Salgo: ,Switch to Sirolimus in Long-Term Renal Transplant Recipients: Reduced Premalignancies and Nonmelanoma Skin Cancer in a Controlled, Prospective, Randomized, Blinded Study'AMERICAN JOURNAL OF TRANSPLANTATION, Issue 6 2010C. Mitchell Renal transplant patients should be managed by dermatologists to prevent and manage skin cancer, a common cause of morbidity and mortality in organ transplant patients. See article by Salgo et al on page 1385. [source] Switch to a Sirolimus-Based Immunosuppression in Long-Term Renal Transplant Recipients: Reduced Rate of (Pre-)Malignancies and Nonmelanoma Skin Cancer in a Prospective, Randomized, Assessor-Blinded, Controlled Clinical TrialAMERICAN JOURNAL OF TRANSPLANTATION, Issue 6 2010R. Salgo Renal transplant recipients (RTR) have a 50,200-fold higher risk for nonmelanoma-skin cancer (NMSC) causing high rates of morbidity and sometimes mortality. Cohort-studies gave evidence that a sirolimus-based immunosuppression may inhibit skin tumor growth. This single-center, prospective, assessor-blinded, randomized trial investigated if switching to sirolimus treatment inhibits the progression of premalignancies and moreover how many new NMSC occur compared to continuation of the original immunosuppressive therapy. Forty-four RTR (mean age 59.9 years, mean duration of immunosuppression 229.5 months) with skin lesions were randomized to sirolimus or continuation of their original immunosuppression. Blinded dermatological assessment at month 6 and 12 by the same dermatologist evaluated the clinical change compared to baseline. Biopsy was performed in suspected malignancy. Already the 6-month-assessment showed significant superiority of sirolimus-therapy: a stop of progression, even regression of preexisting premalignancies (p < 0.0005). This effect was increased at month 12 (p < 0.0001). Nine patients developed histologically confirmed NMSC: one in the sirolimus group, eight in the control group, p = 0.0176. Sirolimus-based immunosuppression in RTR, even when established many years after transplantation, can delay the development of premalignancies, induce regression of preexisting lesions and decelerate the incidence of new NMSC. [source] A Water Soluble Donor,Acceptor [2]Catenane that Can Switch between a Coplanar and a Gemini-Sign Conformation,ANGEWANDTE CHEMIE, Issue 31 2010Yu Au-Yeung Im Zeichen des Zwillings: Ein Donor-Akzeptor-[2]Catenan mit schaltbarer Konformation wurde aus einer dynamischen kombinatorischen Bibliothek erhalten. In einer der Konformationen wurde eine neuartige Anordnung der ,-Einheiten beobachtet, die an das astrologische Zeichen für Zwillinge erinnert (rechts). Das Catenan kann durch thermische und chemische Stimuli oder durch Änderung der Hydrophobie seiner Umgebung zwischen der parallelen und der nichtparallelen Konformation geschaltet werden. [source] A [2]Rotaxane Flip Switch Driven by Coordination Geometry,ANGEWANDTE CHEMIE, Issue 29 2010Gregory Lieber das Zuckerbrot als die Peitsche! Eine Veränderung der Koordinationsgeometrie des Metalls in der terminalen Gruppe eines [2]Rotaxan-Liganden ergibt durch eine Reorientierung des eingeschlossenen Makrocyclus eine molekulare Schaltung. Der Schaltprozess konnte durch eine höhere Attraktivität der Koordinationsstelle hervorgerufen werden (quadratisch-planar), was jedoch durch eine verringerte Attraktivität der Koordinationsstelle nicht gelang (oktaedrisch). [source] Externally Triggered Glass Transition Switch for Localized On-Demand Drug Delivery,ANGEWANDTE CHEMIE, Issue 52 2009Ein Verfahren zur Wirkstoff-Freisetzung auf ein externes Lasersignal hin, bei dem das An/Aus-Verhältnis über 1000:1 beträgt, nutzt den Glasübergang hydrophober Polymere, bei dem sich das Diffusionsvermögen stark ändert. Die Bildung einer glasartigen Oberflächenschicht auf dem Implantat hat eine vernachlässigbare Freisetzung im Aus-Zustand zur Folge. (Die Datenpunkte geben den Ibuprofenspiegel im Blut wieder). [source] Nitro-Substituted Aryl Lithium Compounds in Microreactor Synthesis: Switch between Kinetic and Thermodynamic Control,ANGEWANDTE CHEMIE, Issue 43 2009Aiichiro Nagaki Dr. Beeil Dich oder lass Dir Zeit, je nach dem, was Du willst: Mit einer Mikroflussmethode zur Erzeugung und Umwandlung o -, m - und p -Nitro-substituierter Aryllithiumverbindungen konnte selektiv entweder das kinetisch oder das thermodynamisch begünstigte Intermediat genutzt werden. Im gezeigten Beispiel entstand bei einer Verweildauer von 0.06,s bei ,48,°C 1, während eine Verweildauer von 63,s ausschließlich 2 ergab. [source] A Light-Driven Supramolecular Optical Switch,ANGEWANDTE CHEMIE, Issue 40 2009Shin-nosuke Uno Reversibles Wechseln der Fluoreszenzemission eines DNA-basierten optischen Schalters von Blau zu Grün gelingt mit modulierendem Licht unterschiedlicher Wellenlänge (siehe Bild). Grundlage ist die Hybridisierung zweier pyrenfunktionalisierter DNA-Stränge in Gegenwart eines photochromen azobenzolhaltigen Effektorliganden, sofern dieser cis -konfiguriert vorliegt. Als Folge der Hybridisierung tritt die Excimerfluoreszenz von Pyren auf. [source] On QoS mechanism profiling in MPLS-TP transport networksBELL LABS TECHNICAL JOURNAL, Issue 4 2010Christian Addeo In the context of packet management in optical transport networks, quality of service (QoS) is playing an important role to achieve the right levels of bandwidth, latency, and general treatment for the different services carried over the network. The scope of this paper is to describe quality of service functionalities in the context of a packet transport network. This paper refers to the definition and implementation of the quality of service model in a packet transport network node, describing how this information is carried over a packet transport network. The Alcatel-Lucent 1850 Transport Service Switch (TSS) platform serves as our reference point for a packet transport node. We also include a description of classification, policing, marking, and, in particular, hierarchical scheduling and shaping. © 2010 Alcatel-Lucent. [source] Anthracene-Coupled Pyridine Amines: A New "Off-On" Switch for Molecular Recognition Studies on Dicarboxylic Acids.CHEMINFORM, Issue 35 2006Kumaresh Ghosh Abstract ChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 200 leading journals. To access a ChemInform Abstract, please click on HTML or PDF. [source] Regioselectivity Control by a Ligand Switch in the Coupling Reaction Involving Allenic/Propargylic Palladium Species.CHEMINFORM, Issue 52 2003Shengming Ma Abstract For Abstract see ChemInform Abstract in Full Text. [source] Synthesis of 3,4-Disubstituted Piperidines by Carbonyl Ene and Prins Cyclizations: A Switch in Diastereoselectivity Between Lewis and Broensted Acid Catalysts.CHEMINFORM, Issue 10 2003Jodi T. Williams Abstract For Abstract see ChemInform Abstract in Full Text. [source] ChemInform Abstract: Palladium-Catalyzed Cross-Coupling Reaction of Alkenyldimethyl(2-pyridyl)silanes with Organic Halides: Complete Switch from the Carbometalation Pathway to the Transmetalation Pathway.CHEMINFORM, Issue 38 2001Kenichiro Itami Abstract ChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 100 leading journals. To access a ChemInform Abstract of an article which was published elsewhere, please select a "Full Text" option. The original article is trackable via the "References" option. [source] Silver-Ion-Mediated DNAzyme Switch for the Ultrasensitive and Selective Colorimetric Detection of Aqueous Ag+ and CysteineCHEMISTRY - A EUROPEAN JOURNAL, Issue 14 2009Tao Li Abstract Two states, two applications! An Ag+ -mediated DNAzyme switch has been designed to detect Ag+ and cysteine with high sensitivity and selectivity. In the closed state, Ag+ turns on the switch through the formation of cytosine,Ag+,cytosine base pairs, whereas adding cysteine turns off the open switch because it competitively binds to Ag+. This feature endows the DNAzyme switch with two sensing applications. [source] An Hg2+ -Gated Chiral Molecular Switch Created by Using Binaphthalene Molecules with Two Anthracene Units and Two 1,3-Dithiole-2-thione (1,3-Dithiole-2-one) UnitsCHEMISTRY - A EUROPEAN JOURNAL, Issue 18 2008Cheng Wang Abstract By integrating the features of anthracene, 1,3-dithiole-2-thione, and binaphthalene units, (S)- 1 and its analogue (S)- 2, which contains two 1,3-dithiole-2-one units instead of 1,3-dithiole-2-thione, were studied for creating a new molecular regulation system and building a gated chiral molecular switch. The results show that the photodimerization is controlled by the remote functional-group transformation of CS into CO, thus providing an elegant example of molecular regulation. The photodimerization of two anthracene units induces circular dichroism (CD) spectral variation. Overall, the CD spectrum can be remotely modulated by Hg2+ in (S)- 1, which leads to an Hg2+ -gated chiral molecular switch. [source] Towards a Tunable Tautomeric Switch in Azobenzene Biomimetics: Implications for the Binding Affinity of 2-(4,-Hydroxyphenylazo)benzoic Acid to StreptavidinCHEMISTRY - A EUROPEAN JOURNAL, Issue 7 2008Joan-Antoni Farrera Dr. Abstract The tautomeric equilibria of 2-(4,-hydroxyphenylazo)benzoic acid (HABA) and 2-(3,,5,-dimethyl-4,-hydroxyphenylazo)benzoic acid (3,,5,-dimethyl-HABA) have been studied by a combination of spectroscopic and computational methods. For neutral HABA in solvents of different polarity (toluene, chloroform, DMSO, DMF, butanol, and ethanol) the azo tautomer (AT) is largely predominant. For monoanionic HABA, the hydrazone tautomer (HT) is the only detected species in apolar solvents such as toluene and chloroform, while the AT is the only detected species in water and a mixture of both tautomers is detected in ethanol. Comparison of the results obtained for HABA and its 3,,5,-dimethylated derivative shows that dimethylation of the hydroxybenzene ring shifts the tautomeric preferences towards the hydrazone species. These findings have been used to examine the differences in binding affinity to streptavidin, as the lower affinity of HABA can be explained in terms of the larger energetic cost associated with the tautomeric shift to the bioactive hydrazone species. Overall, these results suggest that a balanced choice of chemical substituents, embedding environment, and pH can be valuable for exploitation of the azo,hydrazone tautomerism of HABA biomimetics in biotechnological applications. [source] A Dendrimer Chiroptical Switch Based on the Reversible Intramolecular Photoreaction of Anthracene and Benzene RingsCHEMISTRY - AN ASIAN JOURNAL, Issue 8 2010Wenjie Liu Dr. Abstract A series of Fréchet-type dendrimers with 9-benzyloxymethylanthracene cores were synthesized and characterized. The chiral source for the dendrimers was an (S)-2-methyl-1-butoxy group in the 3-position of the benzene ring. Irradiation at 366,nm of a dilute benzene solution led to the formation of two diastereomers (1:1) through a quantitative intramolecular [4,+4,] cycloaddition between the central anthracene ring and the neighboring benzene ring. The process can be reversed with 254,nm UV light or heat. The benzene rings in the dendrons work as a light-harvesting system. The optical rotation values measured for the reversible process showed fatigue resistance. Thus, a promising new type of chiroptical switch has been created that has optical rotation values as output signals. 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