Apparent Tilt Research Articles

Study of mode II fracture characteristics and roughness in salt rock after treatment coupled thermo-hydro-mechanical environment

It is crucial to observe the fracture characteristics and roughness of rocks subjected to thermo-hydro-mechanical (THM) coupling experiments. Previous studies have predominantly focused on investigating fracture characteristics in mode I, with comparatively less attention given to mode II fractures of rocks, especially following combined THM treatment. Therefore, this study focuses on utilizing salt rock as the primary subject, and the specimens are pretreated using a self-designed THM coupling triaxial tester. Subsequently, the three-point bending (SCB) test is conducted under ambient pressure conditions. At the peak load stage, the length of the fracture process zone is determined using the digital image correlation (DIC) technique. Additionally, macroscopic and microscopic fracture information on the fracture surface is recorded using 3D laser scanning and electron microscopy. Fracture roughness is evaluated using the apparent tilt function. The findings indicate that: 1) When subjected to various THM coupling conditions, the fracture toughness of salt rock in mode II exhibits a similar evolutionary pattern to that of mode I. However, its value experiences a rapid decrease once the temperature exceeds 500 °C. 2) With increasing temperature, the number of microcracks in salt rock and the degree of microdamage both escalate, leading to a progressive extension of the fracture process zone at the crack tip during the peak stage. 3) Gradually increasing temperature causes a progressive rise in the fracture roughness of salt rock. This is evident in the fact that the roughness along the crack propagation direction is less than that perpendicular to the crack propagation direction. The anisotropy of fracture roughness diminishes gradually.

Evidence for Ion Association at the Gas-Liquid Interface of the Mixture of 1-Butyl-3-methylimidazolium Hexafluorophosphate and Benzonitrile: A Sum Frequency Generation Spectroscopy and Surface Tension Study.

The gas-liquid interface for the mixtures of [BMIM][PF6] and benzonitrile is studied by sum frequency generation (SFG) spectroscopy and surface tension measurements as an important solute to reduce the viscosity of ionic liquids. Solvation of ionic compounds in bulk solvent is not necessarily the same as that at the surface due to the lower dielectric medium at the air/liquid interface. The results from the temperature-dependent SFG spectroscopy and surface tension study suggest that the ionic liquid in a benzonitrile solvent is associated as ion pairs at the surface rather than as dissociated─solvated─ions in the bulk solution. The influence of ionic liquids on the surface structure of benzonitrile is investigated from 0 to 1.0 mole fraction of benzonitrile. The CH stretching mode of vibration of benzonitrile in the SFG spectrum begins from a 0.2 mole fraction (x) of benzonitrile, and the intensity of the peak constantly increases on increasing the concentration of benzonitrile. However, the addition of benzonitrile does not result in extra peaks or shifting of the peak frequency to the spectra of [BMIM][PF6]. The surface tension measurements further support the presence of benzonitrile at the gas-liquid interface. The surface tension data of the mixture smoothly decrease as the benzonitrile concentration increases. The apparent tilt angle of the terminal methyl group of the cation of [BMIM][PF6] is calculated from SFG polarization spectra and shows an apparent lowering with the addition of benzonitrile. The effect of temperature on the surface structure of the binary mixture is also reported at four different temperatures between -15 and 40 °C for both the SFG spectroscopy and surface tension study. Benzonitrile shows different behavior in the mixture at higher temperatures than pure benzonitrile, as observed in the SFG spectra. In contrast, it does not show any CN peak in the mixture below 0.9 mole fraction. The temperature dependence of the interfacial tension is used to evaluate thermodynamic functions such as surface entropy and surface enthalpy. Both were found to be lowered with the increasing concentration of benzonitrile. Both spectroscopic and thermodynamic analyses indicate that the ionic liquid is highly associated as ion pairs and the benzonitrile is more ordered at the surface at concentration <0.4×.

Elucidation of the de Vries behavior in terms of the orientational order parameter, apparent tilt angle, and field-induced tilt angle for smectic liquid crystals by polarized infrared spectroscopy.

We report experimental results of the orientational order parameter, the apparent tilt angle, and the field-induced tilt angle for three chiral smectic liquid crystalline materials investigated using infrared (IR) polarized spectroscopy. The common feature in these materials is use of the core 5-methyl-2- pyrimidine benzoate as the central part of the mesogen. This core is terminated by siloxane or carbosilane chains on one of the ends and by the chiral alkoxy chains on the opposite. These compounds exhibit low concomitant layer shrinkage at the smectic A^{*} (SmA^{*}) to smectic C^{*} (SmC^{*}) transition temperature and within the SmC^{*} phase itself. The maximum layer shrinkage in SmC^{*} is observed as ∼1.5%. We calculate the apparent orientational order parameter, S_{app} in the laboratory reference frame from the observed IR absorbance for homeotropic aligned samples, and the true order parameter, S, is calculated using the measured tilt angle and is also interpolated from Iso-SmA^{*} transition temperature closer to SmC^{*} phase. The apparent tilt angle in the SmA^{*} phase calculated from a comparison of order parameters S and S_{app} is found to be significantly large. A low magnitude of S_{app} found for homeotropic aligned samples in the SmA^{*} phase indicates that the order parameter plays a vital role in determining the de Vries characteristics, especially of exhibiting larger apparent tilt angles. Furthermore there is a significant increase in the true order parameter at temperatures close to SmA^{*} to SmC^{*} transition temperature in all three compounds. The planar-aligned samples are used to study the dependence of induced tilt angle on the applied electric field. The generalized Langevin-Debye model given by Shen etal. reasonably fits the experimental data on the field-induced tilt angle. The results show that the dipole moment of the tilt correlated domain in SmA^{*} diverges as temperature is lowered to the SmA^{*}-SmC^{*} transition temperature. The generalized Langevin-Debye model is also found to be extremely effective in confirming some of the conclusions of the de Vries behavior.

A modified Langevin-Debye model for investigating the electro-optic behaviour of de Vries smectic liquid crystals

ABSTRACTAn external electric field applied across a planar-aligned cell in Smectic A* phase of de Vries smectic liquid crystal induces director redistribution over a cone, resulting in a substantial increase in the birefringence and the apparent optical tilt angle. Such an electro-optic response is modelled by Shen et al. [Y. Shen et al., Phys. Rev. E 88, 062504 (2013)], who modified their previous hollow cone with a diffuse cone model by introducing the molecular distribution function limited over a range of tilt angles, that lie in between θmin and θmax. The limits in these two tilt angles are assumed to be temperature independent though the tilt angle in between the two values can be temperature dependent. However, the high resolution measurements of birefringence and the layer thickness indicate the presence of temperature dependent diffuse cone angle in SmA* phase.. In the proposed model, we replace θmin by θT, a temperature dependent fitting parameter and the change shows that a better fit of the experimental data to the model is obtained. We determine the temperature dependence of θmin and show that this angle increases as SmA* to SmC* phase transition temperature is approached.

Synthesis of Predesigned Ferroelectric Liquid Crystals and Their Applications in Field‐Sequential Color Displays

AbstractA series of low transition temperature and fast response chiral smectic C (SmC*) liquid crystals is designed and synthesized. The phase transition behaviors and electrooptical properties of the synthesized compounds are investigated and compared with reported values. The ferroelectric phase of the liquid crystals is characterized by means of differential scanning calorimetry, polarizing optical microscopy, wide‐angle X‐ray scattering (WAXS), and electrooptical measurements. The wide SmC* phase is achieved via the induction of achiral trisiloxane and a chiral methyl‐lateral substituent onto the terminuses of the molecules. The optimized packing arrangement model is studied based on the exceptionally high apparent tilt angles (≈41°) and smectic layer spacing observed using WAXS. A fast response time of 0.3 ms in an electric field of 10 V µm−1 provides an opportunity to use the synthesized materials for field‐sequential color liquid crystal displays (FSCLCDs). An FSCLCD sample cell is fabricated using the synthesized ferroelectric liquid crystals via a red (R), green (G), and blue (B) backlight. A color‐frame frequency of more than 500 Hz (i.e., a frame frequency more than 166 Hz) is achieved. As a single material liquid crystal display cell, the synthesized ferroelectric liquid crystals show great performances at room temperature.

Clinical approach and imaging of cortical vestibular disorders

The simple classification of vestibular disorders as “peripheral” or “central” disregards a third category: “higher vestibular dysfunctions”. In analogy to disorders of higher visual functions of the “what” and “where” pathways, a new category, namely disorders of higher vestibular functions, which include cognition and other non-vestibular modalities, has been proposed. The dominance of cortical activations of the vestibular network – seen in fMRI and PET studies - reflects several supratentorial neurological disorders involving higher vestibular function. Since they include impairment of spatial orientation, attention, and balance control, they are not only based on vestibular but on integration of multisensory input (visual, vestibular, somatosensory). Four conditions may serve to further elucidate the characteristics of disorders of cortical vestibular function: spatial hemineglect, room-tilt illusion, pusher syndrome, and also impairment of spatial memory and navigation associated with hippocampal atrophy in peripheral bilateral vestibular loss. Spatial hemineglect is a disorder caused by interrupted attention to visual stimuli within one hemifield contralateral to the acute lesion - mostly of the right temporo-parietal cortex. The rare disorder of paroxysmal transient upside-down vision, called the room-tilt illusion, reflects a cortical dysfunction of visual-vestibular interaction due to lesions within the brainstem or even the peripheral labyrinths. The pusher syndrome is characterized by an apparent tilt of the perceived body position in space which the patient attempts to counteract by actively pushing or tilting the body to the contralesional side; causative lesion sites are in the thalamus and posterior part of the insula.

The effect of chiral doping in achiral smectic liquid crystals on the de Vries characteristics: smectic layer thickness, electro-optics and birefringence

ABSTRACTAn addition of chiral dopant to two achiral smectic liquid crystals from a homologous series, by varying weight percentages with known low values of layer shrinkage, leads to chiral smectic-C* phase with a finite value of the spontaneous polarisation. The electro-optical response arising from changes in the induced apparent tilt angle brought about by a weak electric field in the SmA* phase gives rise to power law dependency on the reduced temperature. The critical exponent γ of the power law depends on the dopant concentration but its value is found to be greater than the typical value of 1.32. This implies that the short-range correlation extends from two dimensions to three dimensions in these materials in the SmA phase. The layer thickness of smectic layers in the guest–host system remains unaltered up to the 15 wt % addition of the chiral dopant to two achiral smectics. The system thus retains the low layer shrinkage of the achiral smectic as evidenced by measurements of the layer thickness from X-ray scattering and thickness measurements from optical interferometry. Results on the optical birefringence and the apparent tilt angle lead us to the conclusion of having successfully obtained chiral smectic materials for devices with de Vries characteristics by chiral doping.

Chiral smectic-A and smectic-C phases with de Vries characteristics.

Infrared and dielectric spectroscopic techniques are used to investigate the characteristics of two chiral smectics, namely, 1,1,3,3,5,5,5-heptamethyltrisiloxane 1-[4^{'}-(undecyl-1-oxy)-4-biphenyl(S,S)-2-chloro-3-methylpentanoate] (MSi_{3}MR_{11}) and tricarbosilane-hexyloxy-benzoic acid (S)-4'-(1-methyl-hexyloxy)-3'-nitro-biphenyl-4-yl ester (W599). The orientational features and the field dependencies of the apparent tilt angle and the dichroic ratio for homogeneous planar-aligned samples were calculated from the absorbance profiles obtained at different temperatures especially in the smectic-A* phase of these liquid crystals. The dichroic ratios of the C-C phenyl ring stretching vibrations were considered for the determination of the tilt angle at different temperatures and different voltages. The low values of the order parameter obtained with and without an electric field applied across the cell in the Sm-A^{*} phase for both smectics are consistent with the de Vries concept. The generalized Langevin-Debye model introduced in the literature for explaining the electro-optical response has been applied to the results from infrared spectroscopy. The results show that the dipole moment of the tilt-correlated domain diverges as the transition temperature from Sm-A^{*} to Sm-C^{*} is approached. The Debye-Langevin model is found to be extremely effective in confirming some of the conclusions of the de Vries chiral smectics and gives additional results on the order parameter and the dichroic ratio as a function of the field across the cell. Dielectric spectroscopy finds large dipolar fluctuations in the Sm-A^{*} phase for both compounds and again these confirm their de Vries behavior.

Wetting behavior of patterned micro-pillar array predicted by an equivalent surface tension model

Micro-pillar array is widely applied to manipulate the wettability of surfaces. Cases where liquid has infiltrated such pillar arrays completely are drawing increased attention in miniaturized systems. An equivalent surface tension model is proposed to characterize the driving force of liquid evolution in patterned micro-pillar arrays after the Young-Laplace equation and surface energy analysis are applied on both the pillar unit and bulk liquid levels. The effects of local menisci induced from the wetting of pillars are bounded and treated as “equivalent liquid-vapor surface tension”, through which the bulk liquid profile is then obtained based on the principle of minimal surface energy. The model is found to be computationally efficient and can be easily obtained through numerical methods. A typical sample case is presented to demonstrate its advantages and simplicity. The bulk profile that considers the effects of pillar array is compared with the result without pillars. The influencing effects, including apparent tilt angle, pillar spacing, and pillar shape, are addressed.

Soviet Perspectives and Policies toward Reactionary Regimes in the Developing World

In their assessments during the 1960s and 1970s of the state of affairs of Third World “revolutionary democracies” and nations that had taken the “non-capitalist road to development,” the Soviets employed a mode of analysis based on the “correlation of forces.” Given the seeming successes of these “revolutionary democracies” and the appearance of new ones, Moscow was clearly heartened by the apparent tilt in favor of the Soviets and of “progressive” humanity more generally. These apparently positive trends were reflected in Soviet perspectives and policies on the Third World, which focused confidently on such “progressive” regimes. Nonetheless, so-called “reactionary” regimes continued to be a thorn in the side of Soviet policy makers. This study offers a fresh examination of the Soviet analyses of, and policies towards three “reactionary” Third-World regimes: the military dictatorship in Brazil, the Pinochet dictatorship of Chile, and Iran during the reign of the Shah. The article reveals that Soviet decision makers and analysts identified the state sector as the central factor in the “progressive” development of the Third World. Hence the state sector became the focal point for their analyses and the touchstone for Soviet policies; the promotion of the state sector was regarded as a key to the Soviet objective of promoting the “genuine independence” of Third World countries from imperialist domination.

Intra-unit-cell magnetic correlations near optimal doping in YBa2Cu3O6.85.

The pseudo-gap phenomenon in copper oxide superconductors is central to any description of these materials as it prefigures the superconducting state itself. A magnetic intra-unit-cell order was found to occur just at the pseudo-gap temperature in four cuprate high-Tc superconducting families. Here we present polarized neutron-scattering measurements of nearly optimally doped YBa2Cu3O6.85, carried out on two different spectrometers, that reveal several features. The intra-unit-cell order consists of finite-sized planar domains that are very weakly correlated along the c axis. At high temperature, only the out-of-plane magnetic components correlate, indicating a strong Ising anisotropy. An aditional in-plane response develops at low temperature, giving rise to an apparent tilt of the magnetic moment. The discovery of these two regimes puts stringent constraints, which are tightly bound to the pseudo-gap physics, on the intrinsic nature of intra-unit-cell order.

Target strength spectra of tracked individual fish in schools

Broadband sonar echoes received from individual fish in schools contain information that might be useful for species discrimination. The echo characteristics are closely related to the incident angle of the sound to fish body, corresponding to the apparent tilt angle of a fish from a viewpoint of a transducer. Therefore, it is necessary to isolate individual fish echoes and estimate the incident angles. In this study, a broadband split-beam echo sounder system was used to extract features from free-swimming fish schools. Echoes from individual fish in dense schools were measured and their position was estimated using the system with a downward-oriented acoustic beam. Individual fish were tracked in schools of Japanese jack mackerel Trachurus japonicus, chub mackerel Scomber japonicus, and red sea bream Pagrus major with the system. The target strength (TS) spectra of echoes ranging from 80 to 120 kHz were calculated and sorted on the basis of the incident angle, which was estimated by the tracking result. Using this approach, TS spectra were obtained from entire schools of free-swimming fish, and the obtained TS spectra were found to be dependent on fish species and the incident angles of the individual fish involved.

Characterization of SAMs Derived from Octadecyloxyphenylethanethiols by Sum Frequency Generation

Sum frequency generation (SFG) vibrational spectroscopy analyses were performed on self-assembled monolayers (SAMs) formed via the adsorption of 2-(4-(octadecyloxy)phenylethanethiol (R1ArMT), 2-(3,5-bis(octadecyloxy)phenylethanethiol (R2ArMT), and 2-(3,4,5-tris(octadecyloxy)phenyl-ethanethiol (R3ArMT) on gold. SFG spectra showed that the monolayers formed were closely packed and well ordered. It was determined, using orientation analysis, that as additional octadecyloxy chains were attached to the aromatic ring the apparent methyl group tilt increased and conformational order decreased. Aromatic C–H modes exhibited in the SFG spectra suggest the aromatic rings have a C2 axis along the surface normal. Model phenylethanethiols with different symmetries along the benzene ring were synthesized and used to identify vibrational modes and the surface orientation of the alkoxyphenylethanethiols. SAMs derived from R1ArMT exhibit aromatic C–H stretching modes due to the C2v symmetry at the ring. In contrast, SAMs derived from R2ArMT and R3ArMT exhibit no aromatic C–H stretching modes due to their low Raman cross section.

Anomalous non-isotropic temporal variation of gamma-radiation from radon (progeny) within air in confined conditions

SUMMARY New experimental results add information on the space–time variation pattern of nuclear radiation from radon in air at confined conditions. Using five gamma sensors placed around a canister containing radon in gas demonstrated temporal variation consisting of a long-term variation, which may be related to an annual variation, multiday (MD) signals and periodic daily radon (DR) signals. Separate processes drive the MD and DR signals. Both MD and DR signals exhibit inverse temporal variation patterns in the east–west and north–south directions. The MD and DR signal patterns along the vertical axis are associated with the north–south directed radiation pattern suggesting that the up–down axis of the system is actually inclined relative to the vertical axis of the canister, i.e. related to the latitude of the experiment. The relations of the time–space variations including the apparent tilt relative to a principal geographic direction imply a connection to global orientation. These results are in line with the proposition of an influence of a component of solar irradiation on variation patterns of nuclear radiation from radon.

Properties of Membrane-Incorporated WALP Peptides That Are Anchored on Only One End

Peptides of the "WALP" family, acetyl-GWW(LA)(n)LWWA-[ethanol]amide, have proven to be opportune models for investigating lipid-peptide interactions. Because the average orientations and motional behavior of the N- and C-terminal Trp (W) residues differ, it is of interest to investigate how the positions of the tryptophans influence the properties of the membrane-incorporated peptides. To address this question, we synthesized acetyl-GGWW(LA)(n)-ethanolamide and acetyl-(AL)(n)WWG-ethanolamide, in which n = 4 or 8, which we designate as "N-anchored" and "C-anchored" peptides, respectively. Selected (2)H or (15)N labels were incorporated for solid-state nuclear magnetic resonance (NMR) spectroscopy. These peptides can be considered "half"-anchored WALP peptides, having only one pair of interfacial Trp residues near either the amino or the carboxyl terminus. The hydrophobic lengths of the (n = 8) peptides are similar to that of WALP23. These longer half-anchored WALP peptides incorporate into lipid bilayers as α-helices, as reflected in their circular dichroism spectra. Solid-state NMR experiments indicate that the longer peptide helices assume defined transmembrane orientations with small non-zero average tilt angles and moderate to high dynamic averaging in bilayer membranes of 1,2-dioleoylphosphatidylcholine, 1,2-dimyristoylphosphatidylcholine, and 1,2-dilauroylphosphatidylcholine. The intrinsically small apparent tilt angles suggest that interactions of aromatic residues with lipid headgroups may play an important role in determining the magnitude of the peptide tilt in the bilayer membrane. The shorter (n = 4) peptides, in stark contrast to the longer peptides, display NMR spectra that are characteristic of greatly reduced motional averaging, probably because of peptide aggregation in the bilayer environment, and CD spectra that are characteristic of β-structure.

Too Big To Fail?: The Transatlantic Relationship from Bush to Obama

On September 11 2011 the world commemorated the tenth anniversary of one of the great tipping points in recent international affairs: the successful attacks launched by Al-Qaeda on the USA. In this article, I reflect on only one aspect of the global fallout: the impact which the ensuing ‘war on terror’ had on the transatlantic relationship. Here scholars have divided into broadly two camps, one of which insists that the ‘war’ did very little to shake the foundations of what remains a remarkably stable relationship, and another which argues that the first decade of the 21st century effectively witnessed the death of the West. Both views – as I will argue – are exaggerated. Yet, as I will also show, the relationship was clearly weakened by the fallout from 9/11. This in large part explains why Barack Obama’s election in 2008 was greeted with such enthusiasm in European capitals. Yet even his election has not dispelled worries about the long-term health of the relationship. Indeed, with the rise of China and the USA’s apparent tilt towards an economically more dynamic Asia, Europe – it seems – has become less important to the USA and the USA seemingly less interested in Europe. The relationship thus still faces some very real challenges in the years ahead – challenges that will test the intelligence and capacities of policy-makers on both sides of the Atlantic. Policy Implications • The transatlantic relationship has remained central to world order and it is critically important that policy-makers in Europe and the United States continue to recognize this. • Policy elites should draw the right lessons from the transatlantic crisis caused by the Iraq war in 2003 and try to ensure that such a rift does not occur again. • US policy-makers in their efforts to build new relationships with emerging powers in Asia should be careful not to convey the impression to their European allies that their new interest in Asia and China is the same thing as indifference towards Europe.

Accommodation of a Central Arginine in a Transmembrane Peptide by Changing the Placement of Anchor Residues

Both Trp and Arg in transmembrane protein domains make important interactions with lipids at the membrane/water interface, but at different depths. Derivatives of the designed peptide GWALP23, acetyl-GGALW(5)LALALALALALALW(19)LAGA-amide, with single Trp anchors, have proven useful for characterizing such interactions. Indeed, previous work revealed quite different effects emanating from Arg substitutions at positions 12 and 14 within GWALP23, with the R12 peptide exhibiting multiple positions and orientations with respect to DOPC bilayer membranes (Vostrikov et al. J. Am. Chem. Soc. 2010, 132, 5803-5811). To gain further understanding of the multistate behavior, we moved the Trp "anchor" residues to more outer positions 3 and 21 in GWALP23 itself, and in the R12 and R14 derivatives. The locations and orientations of the peptides with respect to lipid bilayer membranes of differing thickness were investigated by means of solid-state (2)H NMR spectroscopy, using labeled alanines, and coarse-grained molecular dynamics simulations. Interestingly, relatively intense and narrow (2)H resonances from selected backbone C(α) deuterons were observed over quite narrow ranges of frequency and sample orientation. The backbone resonances reflect dynamic complexities and at the same time provide important contributions for the analysis of peptide transmembrane orientation. With the Trp(3,21) anchors relatively far from the peptide and bilayer center, the results indicate significantly large apparent tilt angles, for example, close to 30° for the new R12 and R14 peptides with respect to the bilayer normal of DLPC membranes. The R12 side chain indeed is "rescued" to a stable position, where it is accommodated within the transmembrane helix, when the Trp anchors are moved outward and to another face of the helix. At the same time, the R14 side chain of transmembrane GW(3,21)ALP23 also retains a stable favored position.

Tyrosine Replacing Tryptophan as an Anchor in GWALP Peptides

Synthetic model peptides have proven useful for examining fundamental peptide-lipid interactions. A frequently employed peptide design consists of a hydrophobic core of Leu-Ala residues with polar or aromatic amino acids flanking each side at the interfacial positions, which serve to "anchor" a specific transmembrane orientation. For example, WALP family peptides (acetyl-GWW(LA)(n)LWWA-[ethanol]amide), anchored by four Trp residues, have received particular attention in both experimental and theoretical studies. A recent modification proved successful in reducing the number of Trp anchors to only one near each end of the peptide. The resulting GWALP23 (acetyl-GGALW(5)(LA)(6)LW(19)LAGA-[ethanol]amide) displays reduced dynamics and greater sensitivity to lipid-peptide hydrophobic mismatch than traditional WALP peptides. We have further modified GWALP23 to incorporate a single tyrosine, replacing W(5) with Y(5). The resulting peptide, Y(5)GWALP23 (acetyl-GGALY(5)(LA)(6)LW(19)LAGA-amide), has a single Trp residue that is sensitive to fluorescence experiments. By incorporating specific (2)H and (15)N labels in the core sequence of Y(5)GWALP23, we were able to use solid-state NMR spectroscopy to examine the peptide orientation in hydrated lipid bilayer membranes. The peptide orients well in membranes and gives well-defined (2)H quadrupolar splittings and (15)N/(1)H dipolar couplings throughout the core helical sequence between the aromatic residues. The substitution of Y(5) for W(5) has remarkably little influence on the tilt or dynamics of GWALP23 in bilayer membranes of the phospholipids DOPC, DMPC, or DLPC. A second analogue of the peptide with one Trp and two Tyr anchors, Y(4,5)GWALP23, is generally less responsive to the bilayer thickness and exhibits lower apparent tilt angles with evidence of more extensive dynamics. In general, the peptide behavior with multiple Tyr anchors appears to be quite similar to the situation when multiple Trp anchors are present, as in the original WALP series of model peptides.

Study on Nitrogen Shock Absorber Oil

Liquid shock absorbing system as the primary one, although it can solve the shock absorbing problem, there has been a crash or impact occurs instantaneously when the apparent tilt steering and comfort very poor phenomenon. To this end, a new study of nitrogen gas shock absorber fluid control body height at rated load automatically within the body to adjust to the optimal height designed to improve the car's shock absorber damping effect, making the car more shock absorption system safe and comfortable, with a more stable operational.

On the Combined Analysis of 2H and 15N/1H Solid-State NMR Data for Determination of Transmembrane Peptide Orientation and Dynamics

The dynamics of membrane-spanning peptides have a strong affect on the solid-state NMR observables. We present a combined analysis of 2H-alanine quadrupolar splittings together with 15N/1H dipolar couplings and 15N chemical shifts, using two models to treat the dynamics, for the systematic evaluation of transmembrane peptides based on the GWALP23 sequence (acetyl-GGALW(LA)6LWLAGA-amide). The results indicate that derivatives of GWALP23 incorporating diverse guest residues adopt a range of apparent tilt angles that span 5°–35° in lipid bilayer membranes. By comparing individual and combined analyses of specifically 2H- or 15N-labeled peptides incorporated in magnetically or mechanically aligned lipid bilayers, we examine the influence of data-set size/identity, and of explicitly modeled dynamics, on the deduced average orientations of the peptides. We conclude that peptides with small apparent tilt values (<∼10°) can be fitted by extensive families of solutions, which can be narrowed by incorporating additional 15N as well as 2H restraints. Conversely, peptides exhibiting larger tilt angles display more narrow distributions of tilt and rotation that can be fitted using smaller sets of experimental constraints or even with 2H or 15N data alone. Importantly, for peptides that tilt significantly more than 10° from the bilayer-normal, the contribution from rigid body dynamics can be approximated by a principal order parameter.