Conformationally Restricted Nucleocyclitols: a Study into their Conformational Preferences and Supramolecular Architecture in the Solid State

With the intent of probing the feasibility of employing annulation as a tactic to engender axial rich conformations in nucleoside analogues, two adenine-derived, ``conformationally restricted'' nucleocylitols, 9 and 10, have been conceptualized as representatives of a hitherto unexplored class of nucleic acid base-cyclitol hybrids. A general synthetic strategy, with an inherent scope for diversification, allowed rapid functionalization of indane and tetralin to furnish 9 and 10 respectively in fair yield. Single-crystal X-ray diffraction analysis revealed that the two nucleocyclitols under study, though homologous, present completely dissimilar modes of molecular packing, marked, in particular, by the nature of involvement of the adenynyl NH2 group in the supramolecular assembly. In addition, the crystal structures of 9 and 10 also exhibit two different conformations of the functionalized cyclohexane ring. Thus, while the six-membered carbocycle in cyclopenta-annulated 9 exists in the expected chair (C) conformation that in cyclohexaannulated 10, which crystallizes as a dihydrate, shows an unusual twist-boat (TB) conformation. From a close analysis of the (HNMR)-H-1 spectroscopic data recorded for 9 and 10 in CD3OD, it was possible to put forth a putative explanation for the uncanny conformational preferences of crystalline 9 and 10.

Nonlinear Control Design for an Air-breathing Engine with State Estimation

A nonlinear control design approach is presented in this paper for a challenging application problem of ensuring robust performance of an air-breathing engine operating at supersonic speed. The primary objective of control design is to ensure that the engine produces the required thrust that tracks the commanded thrust as closely as possible by appropriate regulation of the fuel flow rate. However, since the engine operates in the supersonic range, an important secondary objective is to ensure an optimal location of the shock in the intake for maximum pressure recovery with a sufficient margin. This is manipulated by varying the throat area of the nozzle. The nonlinear dynamic inversion technique has been successfully used to achieve both of the above objectives. In this problem, since the process is faster than the actuators, independent control designs have also been carried out for the actuators as well to assure the satisfactory performance of the system. Moreover, an extended Kalman Filter based state estimation design has been carried out both to filter out the process and sensor noises as well as to make the control design operate based on output feedback. Promising simulation results indicate that the proposed control design approach is quite successful in obtaining robust performance of the air-breathing system.

Reinventing Nordic Openness : Transparency and State Information in Finland

The study explores new ideational changes in the information strategy of the Finnish state between 1998 and 2007, after a juncture in Finnish governing in the early 1990s. The study scrutinizes the economic reframing of institutional openness in Finland that comes with significant and often unintended institutional consequences of transparency. Most notably, the constitutional principle of publicity (julkisuusperiaate), a Nordic institutional peculiarity allowing public access to state information, is now becoming an instrument of economic performance and accountability through results. Finland has a long institutional history in the publicity of government information, acknowledged by law since 1951. Nevertheless, access to government information became a policy concern in the mid-1990s, involving a historical narrative of openness as a Nordic tradition of Finnish governing Nordic openness (pohjoismainen avoimuus). International interest in transparency of governance has also marked an opening for institutional re-descriptions in Nordic context. The essential added value, or contradictory term, that transparency has on the Finnish conceptualisation of governing is the innovation that public acts of governing can be economically efficient. This is most apparent in the new attempts at providing standardised information on government and expressing it in numbers. In Finland, the publicity of government information has been a concept of democratic connotations, but new internationally diffusing ideas of performance and national economic competitiveness are discussed under the notion of transparency and its peer concepts openness and public (sector) information, which are also newcomers to Finnish vocabulary of governing. The above concepts often conflict with one another, paving the way to unintended consequences for the reforms conducted in their name. Moreover, the study argues that the policy concerns over openness and public sector information are linked to the new drive for transparency. Drawing on theories of new institutionalism, political economy, and conceptual history, the study argues for a reinvention of Nordic openness in two senses. First, in referring to institutional history, the policy discourse of Nordic openness discovers an administrative tradition in response to new dilemmas of public governance. Moreover, this normatively appealing discourse also legitimizes the new ideational changes. Second, a former mechanism of democratic accountability is being reframed with market and performance ideas, mostly originating from the sphere of transnational governance and governance indices. Mobilizing different research techniques and data (public documents of the Finnish government and international organizations, some 30 interviews of Finnish civil servants, and statistical time series), the study asks how the above ideational changes have been possible, pointing to the importance of nationalistically appealing historical narratives and normative concepts of governing. Concerning institutional developments, the study analyses the ideational changes in central steering mechanisms (political, normative and financial steering) and the introduction of budget transparency and performance management in two cases: census data (Population Register Centre) and foreign political information (Ministry for Foreign Affairs). The new policy domain of governance indices is also explored as a type of transparency. The study further asks what institutional transformations are to be observed in the above cases and in the accountability system. The study concludes that while the information rights of citizens have been reinforced and recalibrated during the period under scrutiny, there has also been a conversion of institutional practices towards economic performance. As the discourse of Nordic openness has been rather unquestioned, the new internationally circulating ideas of transparency and the knowledge economy have entered this discourse without public notice. Since the mid 1990s, state registry data has been perceived as an exploitable economic resource in Finland and in the EU public sector information. This is a parallel development to the new drive for budget transparency in organisations as vital to the state as the Population Register Centre, which has led to marketization of census data in Finland, an international exceptionality. In the Finnish Ministry for Foreign Affairs, the post-Cold War rhetorical shift from secrecy to performance-driven openness marked a conversion in institutional practices that now see information services with high regards. But this has not necessarily led to the increased publicity of foreign political information. In this context, openness is also defined as sharing information with select actors, as a trust based non-public activity, deemed necessary amid the global economic competition. Regarding accountability system, deliberation and performance now overlap, making it increasingly difficult to identify to whom and for what the public administration is accountable. These evolving institutional practices are characterised by unintended consequences and paradoxes. History is a paradoxical component in the above institutional change, as long-term institutional developments now justify short-term reforms.

New light on the optical equivalence theorem and a new type of discrete diagonal coherent state representation

In many instances we find it advantageous to display a quantum optical density matrix as a generalized statistical ensemble of coherent wave fields. The weight functions involved in these constructions turn out to belong to a family of distributions, not always smooth functions. In this paper we investigate this question anew and show how it is related to the problem of expanding an arbitrary state in terms of an overcomplete subfamily of the overcomplete set of coherent states. This provides a relatively transparent derivation of the optical equivalence theorem. An interesting by-product is the discovery of a new class of discrete diagonal representations.

Thermal decomposition of hydrazinium monoperchlorate in the molten state

The thermal decomposition of hydrazinium monoperchlorate (HP-1) in the molten state has been investigated using differential thermal analysis, thermogravimetric analysis, a constant volume manometric technique and mass-spectrometry. The stoichiometry of the reaction can be represented by the equation: 20 N2H5C1O4 13 NH4C1O4 + 3.5 Cl2 + 2 O2 + 13 N2 + 0.5 N2O + 0.5 H2 + + 23.5 H2O The data seem to indicate that the mechanism, which involves an associated complex, remains unchanged from 140 to 190°. Consequently, impurities capable of forming associated complexes with the hydrazinium or the perchlorate ion desensitize the thermal decomposition of HP-1, the extent of desensitization being determined by the size, the charge and the concentration of the impurity.

State Minimization of Incompletely Specified Sequential Machines

A simple procedure for the state minimization of an incompletely specified sequential machine whose number of internal states is not very large is presented. It introduces the concept of a compatibility graph from which the set of maximal compatibles of the machine can be very conveniently derived. Primary and secondary implication trees associated with each maximal compatible are then constructed. The minimal state machine covering the incompletely specified machine is then obtained from these implication trees.

On the stabilization of uniformly decoupled systems by state variable feedback

Conditions under which the asymptotic stabilization of uniformly decoupled time-varying multivariate systems is possible are explored. This is accomplished by developing a canonical form for integrator uniformly decoupled system in which the coefficient matrices have a simple structure. The procedures developed rely on certain conditions on the given system and yield explicit expressions for the stabilization compensators.

Thermodynamic characterization of the reversible, two-state unfolding of maltose binding protein, a large two-domain protein

The folding and stability of maltose binding protein (MBP) have been investigated as a function of pH and temperature by intrinsic tryptophan fluorescence, far- and near-UV circular dichroism, and high-sensitivity differential scanning calorimetric measurements. MBP is a monomeric, two-domain protein containing 370 amino acids. The protein is stable in the pH range of 4-10.5 at 25 degrees C. The protein exhibits reversible, two-state, thermal and guanidine hydrochloride-mediated denaturation at neutral pH. The thermostability of MBP is maximal at pH 6, with a Tm of 64.9 degrees C and a deltaHm of 259.7 kcal mol(-1). The linear dependence of deltaHm on Tm was used to estimate a value of deltaCp of 7.9 kcal mol(-1) K(-1) or 21.3 cal (mol of residue)(-1) K(-1). These values are higher than the corresponding deltaCp's for most globular proteins studied to date. However, the extrapolated values of deltaH and deltaS (per mole of residue) at 110 degrees C are similar to those of other globular proteins. These data have been used to show that the temperature at which a protein undergoes cold denaturation depends primarily on the deltaCp (per mol of residue) and that this temperature increases with an increase in deltaCp. The predicted decrease in stability of MBP at low temperatures was experimentally confirmed by carrying out denaturant-mediated unfolding studies at neutral pH at 2 and 28 degrees C.

Crystal state conformation of three model monomer units for the beta-bend ribbon structure

The molecular and crystal structures of three compounds, representing the repeating units of the -bend ribbon (an approximate 310-helix, with an intramolecular hydrogen-bonding donor every two residues), have been determined by x-ray diffraction. They are Boc-Aib-Hib-NHBzl, Z-Aib-Hib-NHBzl, and Z-L-Hyp-Aib-NHMe (Aib, -aminoisobutyric acid; Bzl, benzyl; Boc, t-butyloxycarbonyl; Hyp, hydroxyproline Hib, -hydroxyisobutyric acid; Z, benzyloxycarbonyl). The two former compounds are folded in a -bend conformation: type III (III) for Boc-Aib-Hib-NHBzl, while type II (II) for the Z analogue. Conversely, the structure of Z-L-Hyp-Aib-NHMe, although not far from a type II -bend, is partially open.

X-ray studies on crystalline complexes involving amino acids and peptides. XXIII. Variability in ionization state, conformation and molecular aggregation in the complexes of succinic acid with DL- and L-lysine

Crystalline complexes of succinic acid with DL- and L-lysine have been prepared and analysed by X-ray diffraction. DL-Lysine complex: C6HIsN202 + 1 2- 1 ~C4H404 .~C4H604, Mr -- 264"2, PI, a = 5"506 (4), =8.070(2), c=14.089(2) A,, a=92.02(1), /3= 100"69 (3), y = 95"85 (3) ~>, Z = 2, Dx = 1"44 g cm -3, R = 0.059 for 2546 observed reflections. Form I of the e-lysine complex: C6HIsN20-, ~ .C4H504, Mr = 264.2, P1, a = 5" 125 (2), b = 8"087 (1), c = 8"689 (1) A,, a = 112.06 (1), /3 = 99.08 (2), y = 93"77(2) °, Z--l, D,,,=1"34(3), Dx=l"34gcm 3 R = 0.033 for 1475 observed reflections. Form II of + I 2- the e-lysine complex: C6H15N202 .,iC4H404 .- 1 I ") 4C4H604.4(C4HsO4""H'"CaH404)" , Mr = 264"2, P1, a = 10.143 (4), b = 10.256 (2), c = 12"916 (3) A,, a = 105.00 (2),/3 = 99-09 (3), y = 92"78 (3)::, Z = 4, Dm= 1"37(4), D,.= 1.38gcm 3, R=0.067 for 2809 observed reflections. The succinic acid molecules in the structures exhibit a variety of ionization states. Two of the lysine conformations found in the complexes have been observed for the first time in crystals containing lysine. Form II of the L-lysine complex is highly pseudosymmetric. In all the complexes, unlike molecules aggregate into separate alternating layers. The basic element of aggregation in the lysine layer in the complexes is an S2-type head-to-tail sequence. This element combines in different ways in the three structures. The basic element of aggre gation in the succinic acid layer in the complexes is a hydrogen-bonded ribbon. The ribbons are interconnected indirectly through amino groups in the lysine layer.

Underwater Sustainability of the ``Cassie'' State of Wetting

A rough hydrophobic surface when immersed in water can result in a ``Cassie'' state of wetting in which the water is in contact with both the solid surface and the entrapped air. The sustainability of the entrapped air on such surfaces is important for underwater applications such as reduction of flow resistance in microchannels and drag reduction of submerged bodies such as hydrofoils. We utilize an optical technique based oil total internal reflection of light at the water-air interface to quantify the spatial distribution of trapped air oil such a surface and its variation with immersion time. With this technique, we evaluate the sustainability of the Cassie state on hydrophobic surfaces with four different kinds of textures. The textures studied are regular arrays of pillars, ridges, and holes that were created in silicon by a wet etching technique, and also a texture of random craters that was obtained through electrodischarge machining of aluminum. These surfaces were rendered hydrophobic with a self-assembled layer Of fluorooctyl trichlorosilane. Depending on the texture, the size and shape of the trapped air pockets were found to vary. However, irrespective of the texture, both the size and the number of air pockets were found to decrease with time gradually and eventually disappear, suggesting that the sustainability of the ``Cassie'' state is finite for all the microstructures Studied. This is possibly due to diffusion of air from the trapped air pockets into the water. The time scale for disappearance of air pockets was found to depend on the kind of microstructure and the hydrostatic pressure at the water-air interface. For the surface with a regular array of pillars, the air pockets were found to be in the form of a thin layer perched on top of the pillars with a large lateral extent compared to the spacing between pillars. For other surfaces studied, the air pockets are smaller and are of the same order as the characteristic length scale of the texture. Measurements for the surface with holes indicate that the time for air-pocket disappearance reduces as the hydrostatic pressure is increased.

Steady-state dendritic cells expressing cognate antigen terminate memory CD8+ T-cell responses

Antigen stimulation of naive T cells in conjunction with strong costimulatory signals elicits the generation of effector and memory populations. Such terminal differentiation transforms naive T cells capable of differentiating along several terminal pathways in response to pertinent environmental cues into cells that have lost developmental plasticity and exhibit heightened responsiveness. Because these cells exhibit little or no need for the strong costimulatory signals required for full activation of naive T cells, it is generally considered memory and effector T cells are released from the capacity to be inactivated. Here, we show that steadystate dendritic cells constitutively presenting an endogenously expressed antigen inactivate fully differentiated memory and effector CD8+ T cells in vivo through deletion and inactivation. These findings indicate that fully differentiated effector and memory T cells exhibit a previously unappreciated level of plasticity and provide insight into how memory and effector T-cell populations may be regulated. © 2008 by The American Society of Hematology.