Macroscopic Quantum Superpositions via Dynamics in a Wide Double-Well Potential.

We present an experimental proposal for the rapid preparation of the center of mass of a levitated particle in a macroscopic quantum state, that is a state delocalized over a length scale much larger than its zero-point motion and that has no classical analog. This state is prepared by letting the particle evolve in a static double-well potential after a sudden switchoff of the harmonic trap, following initial center-of-mass cooling to a sufficiently pure quantum state. We provide a thorough analysis of the noise and decoherence that is relevant to current experiments with levitated nano- and microparticles. In this context, we highlight the possibility of using two particles, one evolving in each potential well, to mitigate the impact of collective sources of noise and decoherence. The generality and scalability of our proposal make it suitable for implementation with a wide range of systems, including single atoms, ions, and Bose-Einstein condensates. Our results have the potential to enable the generation of macroscopic quantum states at unprecedented scales of length and mass, thereby paving the way for experimental exploration of the gravitational field generated by a source mass in a delocalized quantum state.

Diffusional Encounter Rate Constants for Xanthone and 2-Naphthoic Acid by Flash Photolysis Experiments and Brownian Dynamics Simulations: Substantial Effects of Polarizability of the Triplet State.

Diffusional encounter rate constants, for xanthone and 2-naphthoic acid molecules in their triplet states with xanthone or 2-naphthoic acid molecules in their triplet or singlet states, were determined using nanosecond laser flash photolysis spectroscopy. Simultaneously, Brownian dynamics simulations were used to compute these rate constants for assumed models of encountering molecules. Altogether, a global fit to transient absorption progress curves, reporting populations of triplet state xanthone and triplet state 2-naphthoic acid molecules, allowed us to determine six diffusional encounter rate constants from our experiments. The most important result of this study is the detection of substantial effects of the electric polarizability of molecules in their triplet state, visible for xanthone triplet and 2-naphthoic acid ground states, a homo triplet-triplet annihilation of 2-naphthoic acid, and a hetero triplet-triplet annihilation for xanthone and 2-naphthoic acid.

Induction of a secondary structure in the N-terminal pentadecapeptide of human protamine HP2 through Ni(II) coordination. An NMR study.

A solution structure of the Ni(II) complex with the N-terminal pentadecapeptide of human protamine HP2 (HP2(1)(-)(15)) was elucidated with the use of a range of one- and two-dimensional (1)H NMR techniques and molecular modeling. A striking double-loop conformation was found, exhibiting the interactions of the aromatic ring of the Tyr(8) residue with the Ni(II) coordination site at Arg(1), Thr(2), and His(3) residues and the side chain of the Arg(15) residue. In such a conformation, a tendency was found for all five positively charged arginine side chains to locate on one side of the molecule, making possible efficient contacts with the DNA double helix. These structural features, induced indirectly by Ni(II) coordination, are discussed in terms of a possible physiological function of the N-terminus of HP2 as a metal-binding site.

Quantum-dynamical picture of a multistep enzymatic process: reaction catalyzed by phospholipase A(2).

A quantum-classical molecular dynamics model (QCMD), applying explicit integration of the time-dependent Schrödinger equation (QD) and Newtonian equations of motion (MD), is presented. The model is capable of describing quantum dynamical processes in complex biomolecular systems. It has been applied in simulations of a multistep catalytic process carried out by phospholipase A(2) in its active site. The process includes quantum-dynamical proton transfer from a water molecule to histidine localized in the active site, followed by a nucleophilic attack of the resulting OH(-) group on a carbonyl carbon atom of a phospholipid substrate, leading to cleavage of an adjacent ester bond. The process has been simulated using a parallel version of the QCMD code. The potential energy function for the active site is computed using an approximate valence bond (AVB) method. The dynamics of the key proton is described either by QD or classical MD. The coupling between the quantum proton and the classical atoms is accomplished via Hellmann-Feynman forces, as well as the time dependence of the potential energy function in the Schrödinger equation (QCMD/AVB model). Analysis of the simulation results with an Advanced Visualization System revealed a correlated rather than a stepwise picture of the enzymatic process. It is shown that an sp(2)--> sp(3) configurational change at the substrate carbonyl carbon is mostly responsible for triggering the activation process.

[An isolated case of laryngeal sarcoidosis]. / Przypadek izolowanej sarkoidozy krtani.

Sarcoidosis is a disease of unknown etiology characterized by non-caseating granulomatous inflammation of various organs, but most frequently involving the lungs of young adults. Sarcoidosis is seldom seen by ear, nose, throat and larynx. The isolated case of sarcoidosis of the larynx is very rare. We present a case of histologically confirmed sarcoidosis of the vocal cord. The clinical aspects, diagnostic problems and therapeutical possibilities of this rare disease are described.

[A case of choanal polyp in a man with aspirin triad and pollinosis]. / Przypadek olbrzymiego polipa choanalnego u chorego z triada aspirynowa i pylkowica.

The authors describe a case of a man with a large choanal polyp descending into the hypopharynx. The man presented additional symptoms of full aspirin intolerance and pollinosis caused with grass pollen antigens. The Caldwell-Luc procedure was performed and the choanal polyp was successfully removed through the mouth. Postoperatively treatment with leukotriene antagonists and with an intranasal steroids with positive clinical effect was begun. However the patient discontinued the therapeutic process causing polyp recurrence within a short time.

A long-term follow-up of allergy to nickel among fixed prostheses wearers.

Skin allergic hypersensitivity to nickel is well known and well documented in the professional literature. Sixteen partially dentate patients with long-standing histories of recurrent hypersensitive skin reaction to nickel were entered into a clinical trial in 1979. All the patients received crowns or bridges made of an alloy containing 66% of nickel with porcelain fused to the metal framework. During the first three years, annual clinical dental and dermatological investigations were performed on all the subjects, including repeated patch tests. Follow-up examinations took place in 1988 and 1994. None of the subjects had any mucosal or systemic reaction following oral exposure to the nickel containing alloy, nor the exacerbations of skin lesions.

[Pathogenetic role of nickel in human organism]. / Patogenna rola niklu w organizmie czlowieka.

The ever increasing presence of nickel in nature and human food has made it the subject of growing interest of research workers in various medical discipline. Its allergizing, toxic, mutagenic and carcinogenic causes justified concern of those who use it in orthopaedics and stomatology. The frequency of contact allergy to nickel has called attention to its use in production of many daily utility objects. The probability of allergy is not limited only to persons with occupational exposure to this element but it becomes ever more widespread in the whole population. The role of nickel in contact allergy is well known, and a particular feature of this allergy is the character of allergens which are simple haptens with respect to their antigenic. More detailed data on the mechanism of contact allergy have been provided by the discovery of Langerhans cells which have the ability of antigen presentation. Considering the role of nickel in pathological conditions we must not forget its great physiological importance as a microelement necessary for life.

[Views on the use of nickel alloys in oral cavity]. / Poglady na temat stosowania stopów niklu w jamie ustnej.

The biological tolerance of permanent prosthetic replacements made of nickel-containing alloys has been the subject of discussions for years. In the past, allergic contact reactions in the mucosa were rarely observed, and as a rule they were always connected with present or imminent skin allergization. The studies of some authors on the frequency of nickel hypersensitivity in persons wearing prosthetic replacements containing nickel showed usually no differences in comparison with control groups having no such replacements. However, in the literature many reports were published also disqualifying these alloys in view of the allergizing effect of nickel released from them in the mouth. A survey of the literature gives thus no clear-cut conclusions concerning the use of alloys based on nickel in stomatological prosthetics.

[Remote results of prosthetic treatment of patients with nickel hypersensitivity]. / Odlegle wyniki leczenia protetycznego pacjentów uczulonych na nikiel.

Economic reasons are the cause that ever more frequently prosthetic replacements are made from alloys other than gold. The most widely used are: alloys based on nickel and chromium, and stainless steel. In some alloys the content of nickel may be over 80%. The studies carried out in early 1980s showed that these materials had a higher hardness, mechanical strength and elasticity module than gold alloys. Nickel is one of the main components of these alloys, and its compounds may exert a harmful toxic, and even more frequently, allergic effect on the human organism. In the light of a survey of the literature and own clinical, experimental and epidemiological investigations it was tried to trace the effect of dental replacements made of nickel-containing alloys on the mucous membranes and skin of subjects with confirmed hypersensitivity to nickel. The studied material comprised a group of patients selected at random from those attending the Allergology Outpatient Clinic at the Department of Dermatology, Medical Academy in Warsaw, who had verified hypersensitivity to nickel and had indications to preparation of crowns and bridges for wearing. In each case before and after prosthetic treatment and before any control stomatological examination patch tests were done for demonstrating nickel hypersensitivity. In all patients permanent prostheses were done from an allow containing up to 70% of nickel with baked porcelain. In most cases fragments of oral mucosa were taken for histological examination. The patients were examined twice yearly. The longest follow-up is presently over 8 years. In no case exacerbation of hypersensitivity reactions was noted.