Sequential Displacement Research Articles

First Synthesis of N-(3-Carboxylpropyl)-5-amino-2-hydroxy-3- tridecyl-1,4-benzoquinone, an Unusual Quinone Isolated from Embelia ribes

The first synthesis of the unusual nitrogen-containing 3-alkyl-1,4-benzoquinone, N-(3-carboxylpropyl)-5-amino-2-hydroxy-3-tridecyl-1,4-benzoquinone, isolated from Embelia ribes, is reported. The key steps are a microwave-assisted combined Mitsunobu reaction-Claisen rearrangement to introduce the alkyl side chain into 2,5-dimethoxyphenol, followed by alkene reduction, oxidation to the quinone, and sequential displacement of the methoxy groups with hydroxide and GABA tert-butyl ester. Two other naturally occurring benzoquinones, O-methylrapanone and rapanone, were also prepared en route.

Automatic Measurement of Nonparticipatory Stiffness in the Perioral Complex

To detail a novel automated technology developed in the authors' laboratory to quantitatively and noninvasively measure perioral passive stiffness in order to consider the feasibility of future applications in patients with facial movement disorders. A stiffness measurement system was developed, with corresponding data sampled from a group of 8 healthy women. Perioral electromyograms were sampled to confirm nonparticipation. A specially designed linear motor servo operating under position feedback was programmed to impose sequential step displacements of the lip at the oral angles over a span of approximately 24 mm. Real-time data acquisition and analysis of resultant force and displacement provide a quantitative, rapid, index of muscle rigidity (stiffness) during a do-not-contract condition. Nonlinear regression techniques revealed that the relation between perioral stiffness and imposed displacement was highly significant. Given the probable relation between certain forms of neuromotor disease and facial rigidity, effects of bomb blast or missile injury on orofacial function, or stiffness changes due to tissue scarring after lip revision surgeries in children with clefts, it is likely that inclusion of facial stiffness measurements will be useful in the management of facial movement disorders.

N‐Isopropylidene‐N′‐2‐nitrobenzenesulfonyl Hydrazine, a Reagent for Reduction of Alcohols via the Corresponding Monoalkyl Diazenes.

AbstractChemInform 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.

N-Isopropylidene-N‘-2-nitrobenzenesulfonyl Hydrazine, a Reagent for Reduction of Alcohols via the Corresponding Monoalkyl Diazenes

The reagent N-isopropylidene-N'-2-nitrobenzenesulfonyl hydrazine (IPNBSH) is used in the reduction of alcohols via the loss of dinitrogen from transiently formed monoalkyl diazene intermediates accessed by sequential Mitsunobu displacement, hydrolysis, and fragmentation under mild reaction conditions.

DFT studies of gas-phase reaction mechanism of coordinatively unsaturated W(CO) 5 with NO

The reaction of coordinatively unsaturated W(CO) 5 with NO is investigated using density functional theory. B3LYP-based calculations with ECPs (LANL2DZ) on W and 6-311+G(2d) all-electron basis sets on C, N, and O are used to characterize transients observed in the vibrational absorption spectra of CO and NO ligands observed by a time-resolved infrared absorption spectroscopy after the 355-nm pulse laser photolysis of W(CO) 6/NO/Ar mixture [Y. Ishikawa and S. Arai, Chem. Phys. Lett. 253 (1996) 230]. The calculations suggested that, in the gas phase reaction of NO with W(CO) 5, simple coordination to form W(CO) 5(NO) does not occur but, instead, sequential concerted displacement of CO takes place to form W(CO) 3(NO) 2.

Tracking Myocardial Motion From Cine DENSE Images Using Spatiotemporal Phase Unwrapping and Temporal Fitting

Displacement encoding with stimulated echoes (DENSE) encodes myocardial tissue displacement into the phase of the MR image. Cine DENSE allows for rapid quantification of myocardial displacement at multiple cardiac phases through the majority of the cardiac cycle. For practical sensitivities to motion, relatively high displacement encoding frequencies are used and phase wrapping typically occurs. In order to obtain absolute measures of displacement, a two-dimensional (2-D) quality-guided phase unwrapping algorithm was adapted to unwrap both spatially and temporally. Both a fully automated algorithm and a faster semi-automated algorithm are proposed. A method for computing the 2-D trajectories of discrete points in the myocardium as they move through the cardiac cycle is introduced. The error in individual displacement measurements is reduced by fitting a time series to sequential displacement measurements along each trajectory. This improvement is in turn reflected in strain maps, which are derived directly from the trajectories. These methods were validated both in vivo and on a rotating phantom. Further measurements were made to optimize the displacement encoding frequency and to estimate the baseline strain noise both on the phantom and in vivo. The fully automated phase unwrapping algorithm was successful for 767 out of 800 images (95.9%), and the semi-automated algorithm was successful for 786 out of 800 images (98.3%). The accuracy of the tracking algorithm for typical cardiac displacements on a rotating phantom is 0.24 +/- 0.15 mm. The optimal displacement encoding frequency is in the region of 0.1 cycles/mm, and, for 2 scans of 17-s duration, the strain noise after temporal fitting was estimated to be 2.5 +/- 3.0% at end-diastole, 3.1 +/- 3.1% at end-systole, and 5.3 +/- 5.0% in mid-diastole. The improvement in intra-myocardial strain measurements due to temporal fitting is apparent in strain histograms, and also in identifying regions of dysfunctional myocardium in studies of patients with infarcts.

Dynamical Origins of Stereotypy: Relation of Postural Movements During Sitting to Stereotyped Movements During Body-Rocking

The relation between the movement dynamic properties of sitting still and of seated body-rocking in adults with stereotyped movement disorder and mental retardation and a contrast group of typically developing age-matched adults was examined. Continuous measurement of sequential displacements in center-of-pressure was made using a force platform while subjects were engaged in seated body-rocking and quiet sitting. Properties of movement were compared across conditions (rocking, sitting) and groups (stereotyped movement disorder, contrast). The contrast group had the same modal frequency for both movement properties. The intrinsic dynamics of the stereotyped movement disorder group were similar to those of the contrast group for body-rocking but very different for quiet sitting. Findings support the suggestion that body-rocking in stereotyped movement disorder originates partly as an adaptation to an inability to control posture in a seated position.

Efficient Synthesis of (3S,4R)‐(+)‐3‐Methyl‐6‐hepten‐4‐olide.

AbstractChemInform 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.

Extensive submacular haemorrhage in polypoidal choroidal vasculopathy managed by sequential gas displacement and photodynamic therapy: a pilot study of one‐year follow up

Polypoidal choroidal vasculopathy (PCV) with peculiar vascular lesions presents frequently as recurrent submacular haemorrhage. The best treatment is still not certain. It is the authors' objective to evaluate the 1-year safety and efficacy of photodynamic therapy (PDT) using verteporfin for persistent macular PCV after pneumatic displacement of the massive submacular haemorrhage with intravitreal perfluoropropane (C(3)F(8)). A prospective, non-comparative, interventional case series on patients with extensive and thick submacular haemorrhage secondary to PCV, which was displaced pneumatically with intravitreal pure 0.4 ml C(3)F(8). Fluorescein angiography and indocyanine green angiography were repeated 1-2 weeks later to delineate any persistent active leaking polypoidal lesions, which were then treated with PDT. Retreatment might be considered in each follow up at every 3 months. Six eyes of six patients with the mean age of 53.6 years had been recruited and completed 1-year follow up. The mean baseline Snellen equivalent best-corrected visual acuity (BCVA) was 6/92 and the mean final BCVA at 1 year was 6/17. The mean improvement in logMAR BCVA after the sequential treatments was seven lines (range +3 to +19 lines) (Wilcoxon signed-ranks test, P = 0.03). All patients had at least moderate visual gains. No patient suffered serious complications from PDT. This first report on combined treatment with intravitreal gas injection and sequential PDT on PCV seems to be a well-tolerated option. Further comparative studies with larger sample size and longer follow up are warranted.

Efficient Synthesis of (3S,4R)-(+)-3-Methyl-6-hepten-4-olide

γ-Butyrolactone functionality possesses great importance in natural product chemistry and constitutes an essential part of many molecules with pharmacological applications. The existence of γ-butyrolactone ring as a constitutional unit in many natural products attracted lots of interests on the synthesis and configurational assignments of variously substituted γ-butyrolactones. In our synthetic study of massarilactone A, trans β-methyl-γ-allyl-γ-butyrolactone (3-methyl-6-hepten-4-olide) was selected to be a suitable early material. Several routes for racemic synthesis of cis and trans β-methyl-γ-allyl-γ-butyrolactone were known. At first, synthesis of optically active 3-methyl-6-hepten-4-olide was envisaged to be similar to that of eldanolide. But some preliminary work led us to realize that more efficient synthetic pathway should be devised for a large quantity of material. Here we wish to report a short and efficient synthesis of (3S,4R)-(+)-3-methyl-6-hepten-4-olide (1). In Scheme 1, commercially available (S)-(+)-3-hydroxy2-methylpropionate (2) was silylated with TBDMSCl and its ester function was reduced to aldehyde using DIBAH. Following addition of allylmagnesium bromide to the aldehyde produced a diastereomeric mixture of alcohols 3 and 4 which was easily separated by MPLC (3 : 4 = 1 : 1.4). Alcohol 3 had a right configuration for our purpose and alcohol 4 needs to be inverted at its hydroxyl site. Alcohol 3 was converted to cyanoalcohol 5 through a series of reactions including desilylation, selective tosylation and displacement to cyanide. Sequential desilylation, bismesylation and selective displacement of alcohol 4 with NaCN generated cyanomesylate intermediate which was then smoothly inverted to its acetate 6 using CsOAc. Finally, both cyanoalcohol 5 and acetate 6 were successfully transformed into the target material (3S,4R)-(+)-3-methyl-6hepten-4-olide (1) under hydrolytic condition with c-HCl. In conclusion, (3S,4R)-(+)-3-methyl-6-hepten-4-olide (1) was efficiently synthesized from (S)-(+)-3-hydroxy-2methylpropionate (2) as a staring material by 7 steps in overall yield of 37%. This protocol can also be applied effectively to the synthesis of optically active eldanolide and related compounds.

A solid-phase approach to novel purine and nucleoside analogs

This paper describes a method for the preparation of purine analogs using the solid-phase approach. Nucleoside bases were constructed on Merrifield resin by sequential displacement of purine dichloride with amines, and after detachment, the purine analogs were condensed with d, l-ribofuranoside compounds by the Vorbrüggen method. Thereof, l-ribofuranoside was prepared from l-arabinose via the selective oxidation–reduction procedure of the 2-OH group. Some compounds exhibited moderate activity against HIV-1 in PBM cells.

Effect of feed additives on in vitro and in vivo rumen characteristics and frothy bloat dynamics in steers grazing wheat pasture

Research was conducted to determine the potential efficacy of feed additives (FA) to mitigate frothy bloat in yearling cattle grazing wheat pasture. Two experiments were conducted to: (1) quantify in vitro effect of FA on total rumen and methane gas production and foam potential and (2) quantify the influence of FA on rumen protein characteristics, bloat potential and weight gain of steers grazing wheat pasture. In Exp 1, duplicated analyses of in vitro gas production were measured as sequential plunger displacement (cc) at 0, 1, 2, 3, 4, 5, and 6 h incubation periods. In vitro rumen foam production and strength was measured at 0, 2, and 6 h incubation of minced wheat forage. In Exp 2, eight ruminally cannulated steers (386 ± 35.8 kg/steer) were randomly allocated to one of four FA treatments that included control, monensin, poloxalene, and condensed tannins (CT). Treatments were administered daily through rumen cannulla as pre-mixes with a mixed ration (300 mg/steer/day; as-fed basis). Steers grazed on wheat during a 2-week adaptation period prior to data collection from 05 March to 12 April, 2004. Rumen contents were collected 2 h post-FA infusion (1030 to 1130 h) on day −5, 0, 5, 15, and 22. Cattle were weighed at 28-days intervals. Bloat was visually scored weekly. In Exp 1, in vitro ruminal gas and methane gas production per gram of forage were similar between control and poloxalene, but were lower for monensin ( P<0.01) and CT ( P<0.05) treatments. The lowest ( P<0.01) in vitro foam strength occurred with the addition of poloxalene and the highest occurred in control and monensin treatments. CT was intermediate in rumen foam strength. Mean bloat score was lower in poloxalene and CT than that in monensin and control treatments. Among six-rumen protein components assayed, steers receiving CT after 10, 15, and 22 day had greater protein concentrations in whole rumen content, particulate matter, cheese-cloth filtrate, and protozoa and plant particle fractions than steers fed other treatments. Bacterial and cell-free supernatant protein fractions were comparable among treatments. Ruminal dry matter (DM) content, cell-free supernatant, protozoal and bacterial fractions were similar between the bloated and non-bloated steers. In bloated animals, ruminal pH was lower, and whole rumen content and cheese-cloth filtrate protein fractions tended to be greater ( P=0.08) than in non-bloated animals. Animal average daily gain (ADG) was not affected by FA during experimental period. The results of this trial suggest that wheat pasture bloat was associated with dietary protein and low ruminal pH. Feeding FA can be used to decrease either ruminal gas or foam production or both, and it may protect against the incidence of frothy bloat.

Displacement ofCO2by Xe in single-walled carbon nanotube bundles

The displacement of $\mathrm{C}{\mathrm{O}}_{2}$ by Xe on single-walled nanotube bundles is investigated with Fourier transform infrared spectroscopy (FTIR) and grand canonical Monte Carlo (GCMC) simulations. The FTIR experiments show that $\mathrm{C}{\mathrm{O}}_{2}$ physisorption at $77\phantom{\rule{0.3em}{0ex}}\mathrm{K}$ produces an infrared peak at $2330\phantom{\rule{0.3em}{0ex}}{\mathrm{cm}}^{\ensuremath{-}1}$ for endohedral physisorption and at $2340\phantom{\rule{0.3em}{0ex}}{\mathrm{cm}}^{\ensuremath{-}1}$ for groove/external surface physisorption. Exposure to Xe causes a sequential displacement of $\mathrm{C}{\mathrm{O}}_{2}$ from these sites as shown by an intensity loss of the $2330\phantom{\rule{0.3em}{0ex}}{\mathrm{cm}}^{\ensuremath{-}1}$ peak, which precedes the loss at $2340\phantom{\rule{0.3em}{0ex}}{\mathrm{cm}}^{\ensuremath{-}1}$. The GCMC simulations on heterogeneous and homogenous bundles show that $\mathrm{C}{\mathrm{O}}_{2}$ in endohedral sites is initially displaced by Xe before that in groove/external surface sites. The $\mathrm{C}{\mathrm{O}}_{2}$ populations in each site of the bundle are taken from the GCMC simulations and used to model the variation of the FTIR intensities as a function of Xe pressure. The qualitative agreement between the simulated and experimental intensity changes is good, suggesting that the intensity changes seen in the experiments are related to $\mathrm{C}{\mathrm{O}}_{2}$ displacement from the sites indicated in the simulations.

Effects of Loading Protocol on the Cyclic Response of Woodframe Shearwalls

Standard construction 2.4m×2.4m woodframe shearwalls were tested using different loading protocols. The CUREE-Caltech protocols, recently developed by Krawinkler in 2001, were compared with other previously used protocols. The following protocols were considered in the study: monotonic, CUREE-Caltech standard (CUREE), CUREE-Caltech near-fault, sequential phased displacement (SPD), and international standards organization. Findings from the research indicate that loading sequence has a significant influence on shearwall performance. Protocols with a large number of cycles (SPD) tended to produce nail fatigue fractures, which were not nearly as prevalent in protocols with lower numbers of cycles (CUREE). The research clearly showed that the nail fatigue fractures were associated with a large energy demand related to the number of cycles, which resulted in a reduced ultimate strength and deformation capacity. The initial stiffness of the specimens was relatively unaffected by the loading protocol used; howev...

Habitat selection by Lernanthropus cynoscicola (Copepoda: Lernanthropidae): host as physical environment, a major determinant of niche restriction.

As a potential ultimate cause of microhabitat restriction for ectoparasites of fish, it has been postulated that selection has favoured narrow microhabitats to facilitate mating. The evidence for this hypothesis is evaluated with males and females of the parasitic copepod Lernanthropus cynoscicola, by using methods commonly used in community ecology, and considering the influence of host ontogeny on site selection. No evidence supporting the mating hypothesis was found after comparison of niche measurements between both sexes. Furthermore, aggregation among individuals of the same sex was stronger than among males and females, and the co-occurrence of both sexes did not depart from that expected by chance; also, negative correlations between the intensity of infection of both sexes were observed. Restriction of the microhabitats cannot therefore be due to facilitation of mating. Moreover, both sexes displayed a sequential displacement over the gill arches and differential preferences by specific gill sections in response to an increasing host size, probably as a consequence of a host-size related cline of optimal conditions where fitness is improved. Thus, reproductive benefits other than increased chances of mating may have played a role in the evolution of restricted niches in parasites, and selection may have favoured a narrowing of the niche around sites where fitness is maximized.

Structural basis for sequential displacement of Ca(2+) by Yb(3+) in a protozoan EF-hand calcium binding protein.

We have studied the displacement of Ca(2+)by the trivalent lanthanide ions (Yb(3+)) in a protozoan (Entamoeba histolytica) Ca(2+)-binding protein (EhCaBP), by NMR and thermodynamics. We have demonstrated, for the first time, how one can use in a combined fashion the utility of NMR and thermodynamics to have an insight to the relative binding specificities/affinity between Ca(2+) and Yb(3+). As revealed by the titration experiments, Yb(3+) displaces Ca(2+) from the four metal binding sites present in EhCaBP in a sequential manner. The study provides a structural origin for such a sequential Ca(2+) displacement by Yb(3+) in EhCaBP.

Isoquinolinone Synthesis by SNAr Reaction: A Versatile Route to Imidazo[4,5‐h]isoquinolin‐9‐ones.

AbstractFor Abstract see ChemInform Abstract in Full Text.

DNA strand exchange stimulated by spontaneous complex formation with cationic comb-type copolymer.

Cationic comb-type copolymers (CCCs) composed of a polycation backbone and water-soluble side chains accelerate by 4-5 orders the DNA strand exchange reaction (SER) between double helical DNA and its homologous single-strand DNA. The accelerating effect is considered due to alleviation of counterion association during transitional intermediate formation in sequential displacement pathway. CCCs stabilize not only matured hybrids but also the nucleation complex to accelerate hybridization.

Isoquinolinone synthesis by SNAr reaction: a versatile route to imidazo[4,5-h]isoquinolin-9-ones

Reaction of 2-chlorobenzonitriles with β-ketoesters in an SNAr reaction, followed by cyclization in acid provides a versatile route to isoquinolones. Starting from 2,6-dichloro-3-nitrobenzonitrile 7, sequential displacement of the chlorines by an amine and a β-ketoester leads to imidazo[4,5-h]isoquinolin-9-ones 1, a new class of kinase inhibitor.

Monitoring of the metal displacement from the recombinant mouse liver metallothionein Zn 7-complex by capillary zone electrophoresis with electrospray MS detection

A solution of a Zn-complex of recombinant mouse MT-1 isoform (Zn 7–MT-1) was prepared and titrated with Cd 2+ ions. A method based on the coupling of capillary zone electrophoresis (CZE) with electrospray MS detection was developed for the analysis of the stoichiometry of the species formed during the titration. The method offered the possibility of the on-line removal of up to 100 mM Tris or phosphate buffer solutions that would otherwise suppress the electrospray signal. By allowing the determination of the metal stoichiometry of the complex species present in solution the method was shown to be complementary to circular dichroism and UV–VIS spectrophotometry conventionally used for similar studies. The titration of the Zn 7–MT complex with Cd(II) showed the sequential displacement of the Zn by Cd. The unusually high stability of the Cd 6Zn 1–MT species was observed which suggests a structural role of the remaining Zn(II) ion.