Stable model categories are categories of modules

A stable model category is a setting for homotopy theory where the suspension functor is invertible. The prototypical examples are the category of spectra in the sense of stable homotopy theory and the category of unbounded chain complexes of modules over a ring. In this paper we develop methods for deciding when two stable model categories represent ‘the same homotopy theory’. We show that stable model categories with a single compact generator are equivalent to modules over a ring spectrum. More generally stable model categories with a set of generators are characterized as modules over a ‘ring spectrum with several objects’, i.e., as spectrum valued diagram categories. We also prove a Morita theorem which shows how equivalences between module categories over ring spectra can be realized by smashing with a pair of bimodules. Finally, we characterize stable model categories which represent the derived category of a ring. This is a slight generalization of Rickard's work on derived equivalent rings. We also include a proof of the model category equivalence of modules over the Eilenberg-Mac Lane spectrum HR and (unbounded) chain complexes of R-modules for a ring R.     

Product Integration Rules at Clenshaw-Curtis and Related Points: A Robust Implementation

Product integration rules generalizing the Fej?r, Clenshaw-Curtis,and Filippi quadrature rules respectively are derived for integralswith trigonometric and hyperbolic weight factors. The Chebyshevmoments of the weight functions are found to be given by well-conditionedexpressions, in terms of hypergeometric functions ₀F₁. An a priori error estimator is discussed which is shown bothto avoid wasteful invocation of the integration rule and toincrease significantly the robustness of the automatic quadratureprocedure. Then, specializing to extended Clenshaw-Curtis (ECC) rules,three types of a posteriori error estimates are considered andthe existence of a great risk of their failure is demonstratedby large scale validation tests. An empirical error estimator,superseding them for slowly varying integrands, is found toresult in a spectacular increase in the output reliability. Finally, enhancements in the control of the interval subdivisionstrategy aiming at increasing code robustness is discussed.Comparison with the code DQAWO of QUADPACK, with about a hundredthousand solved integrals, is illustrative of the increasedrobustness and error estimate reliability of our computer codeimplementation of the ECC rules.     

Nucleophilic substitution in 5,6,7,8-tetrafluoro- and 6,7-difluoro-1,2,3,4-tetrahydro-9-alkenyl-1,4-methanonaphthalenes and related compounds. A search for homoallylic conjugation

The second-order rate constants for the nucleophilic replacement of fluorine by isopropoxide in 5,6,7,8-tetrafluoro- and 6,7,-difluoro-1,2,3,4-tetrahydro-9-alkenyl-1,4-methanonaphthalenes and related 9-alkyl systems have been measured. A factor of 6 - 7 separates the most reactive compounds [the 9- (4′-trifluoromethylbenzylidene) derivatives] from the least reactive compounds [the syn-9-isopropyl derivatives] in both the tetrafluoro- and difluoro-series. It is concluded for these small reactivity differences.     

A preliminary observation of additive thermodynamic contribution of pendant arms to the complexation of calixarene derivatives with mercury(II)

An additive thermodynamic contribution of pendant arms to the complexation of calixarene derivatives with mercury(II) in acetonitrile is for the first time demonstrated.     

A facile approach to architecturally defined nanoparticles via intramolecular chain collapse

A novel approach is presented for the controlled intramolecular collapse of linear polymer chains to give well-defined single-molecule nanoparticles whose structure is directly related to the original linear polymer. By employing a combination of living free radical polymerization and benzocyclobutene (BCB) chemistry, nanoparticles can be routinely prepared in multigram quantities with the size being accurately controlled by either the initial degree of polymerization of the linear chain or the level of incorporation of the BCB coupling groups. The latter also allows the cross-link density of the final nanoparticles to be manipulated. In analogy with dendritic macromolecules, a significant reduction of up to 75% in the hydrodynamic volume is observed on going from the starting random coil linear chains to the corresponding nanoparticles. The facile nature of the living free radical process also permits wide variation in monomer selection and functional group incorporation and allows novel macromolecular architectures to be prepared. Furthermore, the use of block copolymers functionalized with benzocyclobutene groups in only one of the blocks gives, after intramolecular collapse, a hybrid architecture in which a single linear polymer chain is attached to the globular nanoparticle.     

Optical-optical double-resonance spectroscopy of BaO: The low-lying states

Optical-optical double-resonance (OODR) induced photoluminescence into the lowest excited electronic states of BaO—a³Σ⁺, A¹Σ⁺, b³Π, and $\text{A′}{}^1\text{Π}$—from C¹Σ⁺ is described. These low-lying states are deperturbed to obtain spectroscopic constants and potential energy curves:

     

7.

Hydrogen and deuterium diffusion in non-stoichiometric spinel     

Geoffrey D. Bromiley  Jennifer Brooke  Simon C. Kohn 《高压研究》2017,37(3):360-376

High pressure/temperature annealing experiments are used to determine diffusivities of H⁺ and D⁺ in non-stoichiometric spinel, a low-pressure analogue for nominally anhydrous minerals in Earth’s mantle. Data are fitted to the following Arrhenius law: Diffusivity (m²/s)?=?4?±?1?×?10^?12 exp(?54?±?2 kJ?mol^?1/RT). At low temperatures, H⁺ and D⁺ diffusion in non-stoichiometric spinel is charge balanced by flux of O vacancies, with infrared data consistent with protonation of both octahedral and tetrahedral O–O edges in non-stoichiometric spinel, and additional fine structure due to Mg–Al mixing and/or coupling of structurally incorporated H⁺ with cation vacancies. Absence of changes in the fine structure of O–H absorption bands indicates that H⁺ can become locally coupled and uncoupled to other defects during bulk diffusion. As such, proton conductivity in spinel group minerals, arising from faster flux of uncoupled H⁺, can only be calculated from H⁺ mobility data if the extent of defect coupling is constrained.     

8.

Automated peak width measurements for targeted analysis of ion mobility unresolved species     

Matthew R. Brantley  Michael E. PettitBrett Harper  Brooke BrownTouradj Solouki 《Analytica chimica acta》2016

Peak broadening in ion mobility (IM) is a relatively predictable process and abnormally broad peaks can be indicative of the presence of unresolved species. Here, we introduce a new ion mobility peak fitting (IM_FIT) software package for automated and systematic determination of traveling wave ion mobility (TWIM) unresolved species. To identify IM unresolved species, the IM_FIT software generates a trend line by plotting ions' mobility peak widths as a function of their arrival times. Utilizing user-defined thresholds, IM_FIT allows for automated and rapid detection of ions that deviate from the peak width trend line. To demonstrate the advantages of IM_FIT for automated detection of IM unresolved species, IM-mass spectrometry (IM-MS) data from a sample mixture containing polypropylene glycol and multiple peptides were analyzed. A total of 14 out of the 34 observed singly-charged IM peaks above 5% relative abundance (i.e., signal-to-noise ratios above ∼200) were tagged as potentially co-eluting ions by IM_FIT. Subsequently, the 14 IM peaks tagged as potentially unresolved (presumably, peaks corresponding to co-eluting compounds), were further analyzed by automated IM deconvolution (AIMD), liquid chromatography-IM-MS (LC-IM-MS), and/or ultra-high resolution mass spectrometry. Using the aforementioned techniques, more than 85% of the tagged IM peaks (12 out of 14) were confirmed to contain co-eluting ions. As an additional new finding, IM_FIT facilitated the discovery of an unexpected sequence-scrambled y-type fragment ion.     

9.

Thermodynamic clarification of the curious ferric/potassium ion exchange accompanying the electrochromic redox reactions of prussian blue, iron(III) hexacyanoferrate(II)     

Rosseinsky DR  Glasser L  Jenkins HD 《Journal of the American Chemical Society》2004,126(33):10472-10477

The recent Glasser-Jenkins method for lattice-energy prediction, applied to an examination of the solid-state thermodynamics of the cation exchanges that occur in electrochromic reactions of Prussian Blue, provides incisive thermodynamic clarification of an ill-understood ion exchange that accompanies particularly the early electrochromic cycles. A volume of 0.246 +/- 0.017 nm(3) formula unit(-1) for the ferrocyanide ion, Fe(II)[(CN)(6)],(4-) is first established and then used, together with other formula unit-volume data, to evaluate the changes of standard enthalpy, entropy, and Gibbs energy in those ion-exchange reactions. The results impressively show by how much the exchange of interstitial Fe(3+) ions by alkali metal ions, usually exemplified by K+, is thermodynamically favored.     

10.

Inhibition of Chymotrypsin by a Self‐Assembled DNA Quadruplex Functionalized with Cyclic Peptide Binding Fragments     

Jianfeng Cai  Brooke A. Rosenzweig  Andrew D. Hamilton Prof. 《Chemistry (Weinheim an der Bergstrasse, Germany)》2009,15(2):328-332

     

1 [2] [3] [4] [5] [6] [7] [8] [9] [10] [11] 下一页 » 末  页»

	$\text{a}{}^3\text{Σ}{}^{\mathrm{+}}$	$\text{A}{}^1\text{Σ}{}^{\mathrm{+}}$	$\text{b}{}^3\text{Π}$	$\text{A′}{}^1\text{Π}$
$\text{T}{}_{\mathrm{<mtext>e</mtext>}}\text{(}\text{cm}{}^{\mathrm{?1}}\text{)}$	16 596(3)	16 807.345(10)	17 502.6(10)	17 619.7(2)
$\text{ω}{}_{\mathrm{<mtext>e</mtext>}}\text{(}\text{cm}{}^{\mathrm{?1}}\text{)}$	469.0(7)	499.620(19)	447.62(8)	447.95(22)
$\text{ω}{}_{\mathrm{<mtext>e</mtext>}}\text{x}{}_{\mathrm{<mtext>e</mtext>}}\text{(}\text{cm}{}^{\mathrm{?1}}\text{)}$	1.48(4)	1.716(8)	2.287(12)	2.139(8)
$\text{ω}{}_{\mathrm{<mtext>e</mtext>}}\text{y}{}_{\mathrm{<mtext>e</mtext>}}\text{× 10}{}^2\text{(}\text{cm}{}^{\mathrm{?1}}\text{)}$		2.14(9)		1.02(3)
$\text{B}{}_{\mathrm{<mtext>e</mtext>}}\text{(}\text{cm}{}^{\mathrm{?1}}\text{)}$	0.2594(5)	0.2583908(26)	0.22426(16)	0.22385(16)
$\text{α}{}_{\mathrm{<mtext>e</mtext>}}\text{× 10}{}^3\text{(}\text{cm}{}^{\mathrm{?1}}\text{)}$	1.44(5)	1.111(3)	1.18(4)	1.15(4)
$\text{γ}{}_{\mathrm{<mtext>e</mtext>}}\text{× 10}{}^6\text{(}\text{cm}{}^{\mathrm{?1}}\text{)}$		7.0(7)		?4.0(21)
$\text{R}{}_{\mathrm{<mtext>e</mtext>}}\text{(}\text{A}\text{?}\text{)}$	2.1294(20)	2.133512(11)	2.2901(8)	2.2922(8)

Hydrogen and deuterium diffusion in non-stoichiometric spinel

High pressure/temperature annealing experiments are used to determine diffusivities of H⁺ and D⁺ in non-stoichiometric spinel, a low-pressure analogue for nominally anhydrous minerals in Earth’s mantle. Data are fitted to the following Arrhenius law: Diffusivity (m²/s)?=?4?±?1?×?10^?12 exp(?54?±?2 kJ?mol^?1/RT). At low temperatures, H⁺ and D⁺ diffusion in non-stoichiometric spinel is charge balanced by flux of O vacancies, with infrared data consistent with protonation of both octahedral and tetrahedral O–O edges in non-stoichiometric spinel, and additional fine structure due to Mg–Al mixing and/or coupling of structurally incorporated H⁺ with cation vacancies. Absence of changes in the fine structure of O–H absorption bands indicates that H⁺ can become locally coupled and uncoupled to other defects during bulk diffusion. As such, proton conductivity in spinel group minerals, arising from faster flux of uncoupled H⁺, can only be calculated from H⁺ mobility data if the extent of defect coupling is constrained.     

Automated peak width measurements for targeted analysis of ion mobility unresolved species

Peak broadening in ion mobility (IM) is a relatively predictable process and abnormally broad peaks can be indicative of the presence of unresolved species. Here, we introduce a new ion mobility peak fitting (IM_FIT) software package for automated and systematic determination of traveling wave ion mobility (TWIM) unresolved species. To identify IM unresolved species, the IM_FIT software generates a trend line by plotting ions' mobility peak widths as a function of their arrival times. Utilizing user-defined thresholds, IM_FIT allows for automated and rapid detection of ions that deviate from the peak width trend line. To demonstrate the advantages of IM_FIT for automated detection of IM unresolved species, IM-mass spectrometry (IM-MS) data from a sample mixture containing polypropylene glycol and multiple peptides were analyzed. A total of 14 out of the 34 observed singly-charged IM peaks above 5% relative abundance (i.e., signal-to-noise ratios above ∼200) were tagged as potentially co-eluting ions by IM_FIT. Subsequently, the 14 IM peaks tagged as potentially unresolved (presumably, peaks corresponding to co-eluting compounds), were further analyzed by automated IM deconvolution (AIMD), liquid chromatography-IM-MS (LC-IM-MS), and/or ultra-high resolution mass spectrometry. Using the aforementioned techniques, more than 85% of the tagged IM peaks (12 out of 14) were confirmed to contain co-eluting ions. As an additional new finding, IM_FIT facilitated the discovery of an unexpected sequence-scrambled y-type fragment ion.     

Thermodynamic clarification of the curious ferric/potassium ion exchange accompanying the electrochromic redox reactions of prussian blue, iron(III) hexacyanoferrate(II)

The recent Glasser-Jenkins method for lattice-energy prediction, applied to an examination of the solid-state thermodynamics of the cation exchanges that occur in electrochromic reactions of Prussian Blue, provides incisive thermodynamic clarification of an ill-understood ion exchange that accompanies particularly the early electrochromic cycles. A volume of 0.246 +/- 0.017 nm(3) formula unit(-1) for the ferrocyanide ion, Fe(II)[(CN)(6)],(4-) is first established and then used, together with other formula unit-volume data, to evaluate the changes of standard enthalpy, entropy, and Gibbs energy in those ion-exchange reactions. The results impressively show by how much the exchange of interstitial Fe(3+) ions by alkali metal ions, usually exemplified by K+, is thermodynamically favored.