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Self-assembled peptides gain increasing interest as biocompatible and biodegradable scaffolds for tissue engineering. Rationally designed self-assembling building blocks that carry cell adhesion motifs such as Arg-Gly-Asp (RGD) are especially attractive. We have used a combination of theoretical and experimental approaches toward such rational designs, especially focusing on modular designs that consist of a central ultrashort amphiphilic motif derived from the adenovirus fiber shaft. In this study, we rationally designed RGDSGAITIGC, a bifunctional self-assembling amyloid peptide which encompasses cell adhesion and potential cysteine-mediated functionalization properties through the incorporation of an RGD sequence motif and a cysteine residue at the N- and C- terminal end, respectively. We performed replica exchange MD simulations that suggested that the key factor determining cell adhesion is the total solvent accessibility of the RGD motif and also that the C-terminal cysteine is adequately exposed. The designer peptides self-assembled into fibers that are structurally characterized with Transmission Electron Microscopy, Scanning Electron Microscopy and X-ray fiber diffraction. Furthermore, they supported cell adhesion and proliferation of a model cell line. We consider that the current bifunctional properties of the RGDSGAITIGC fibril-forming peptide can be exploited to fabricate novel biomaterials with promising biomedical applications. Such short self-assembling peptides that are amenable to computational design offer open-ended possibilities toward multifunctional tissue engineering scaffolds of the future.

The development of high power gyrotrons for plasma physics research needs properly matched calorimetric loads able to absorb and measure the power, which nowadays is foreseen to be as high as 2 MW during CW operations. To this end IFP/CNR has developed a family of matched loads useful in the mm-wave frequency band for applications ranging from a few ms to CW in pulse length. The different loads in the family, made of an integrating sphere with a partially reflecting coating on the inner wall, are characterized by having the same absorbing geometry for the incoming beam and a different heat removal system for the specific application. Some important advances have been recently achieved from the point of view of the uniformity of power distribution on the absorbing wall and of the load construction. With the high precision achieved in the coating thickness a better control of the heating power distribution is possible by proper shaping of the local reflectivity, in addition to the shaping of the mirror dispersing the input beam. A more sophisticated model describing the power distribution has been developed, taking into account a variable thickness of the absorbing coating, the proper shape of the spreading mirror, the frequency of the incoming radiation and the shape of the input beam. Lower coating thickness is shown to be preferable, for a given local reflectivity, from the point of view of a lower peak temperature and thermal stress. The paper describes a load with variable coating thickness along the meridian of the sphere, showing a uniform power deposition on the inner walls. The cooling pipe is completely electroformed on the spherical copper shell, ensuring the maintenance of the correct curvature of the inner surface and fast heat conduction from the absorbing coating to the water through the thin copper body. For CW use all heated parts of the load must be cooled and this is achieved with 16 electroformed spiral channels. Both short pulse loads (0.1–1 s) and the CW version at 2 MW, 170 GHz, are described in the paper. High power tests on short-pulse loads have been done using a double frequency gyrotron, 105 GHz/600 kW for 0.5 s and 140 GHz/800 kW for 1 s. Also a method for emulating 2 MW conditions while using 1 MW gyrotron has been applied to test the load to be used for the European 2 MW coaxial cavity gyrotron development programme.

Dielectronic recombination cross sections for U{sup 28+} are calculated in the distorted-wave approximation and compared with measurements obtained using an electron-ion merged beams apparatus. Although the experiment covered energies between 0 and 420 eV, the theoretical calculations were restricted to energies below 180 eV, where the most important resonance structures occur. The theoretical cross sections involving {Delta}n=0 excitations from the 5s{sup 2}5p{sup 2} ground configuration are found to be equally well described using either semirelativistic wave functions, as found in the AUTOSTRUCTURE codes, or fully relativistic wave functions, as found in the HULLAC codes. The main features of the experimental spectrum are well identified for the 80{endash}180 eV energies, although complicated by the possible presence of unknown fractions of metastable levels. However, the resonance structures observed at the energies less than 80 eV, in the vicinity of a huge zero-energy peak, remain largely unexplained. {copyright} {ital 1998} {ital The American Physical Society}

New recombination experiments with merged cold beams of electrons and atomic ions have been carried out at the storage ring facilities TSR in Heidelberg, ESR in Darmstadt, and CRYRING in Stockholm. A brief overview is given on the recent activities in which the Giessen group was engaged. Topics of this research were dielectronic recombination (DR) of astrophysically relevant ions, recombination of highly charged ions with respect to cooling losses in storage rings, field effects on DR, search for interference effects in photorecombination of ions, correlation effects in DR of low-Z ions, spectroscopy of high-Z ions by DR, and lifetimes of metastable states deduced from DR experiments.

A first temperature measurement of the expanded electron beam from a super-conducting magnet in the cooler of CRYRING is reported. It is based on detection of a dielectronic recombination resonance in C2+. For this measurement C3+ was stored in the ring at 3 rm{MeV/amu} energy. A fit to the resonance with free transverse and longitudinal temperatures gave 3.9 × 10-3 eV and 4.5 × 10-5 eV, respectively. The result is also compatible with the values of 10-3 eV for the transverse and 6.7 ×10-5 eV for the longitudinal component, in good agreement with expected values.

Recent advances in studies of electron-ion recombination processes at low relative energies with the electron cooler of the heavy-ion storage ring CRYRING are shown. Through the use of an adiabatically expanded electron beam, collisions down to 10-4eV relative energies were measured with highly charged ions stored in the ring at around 15 MeV/amu energies. Examples of recombination measurements for bare ions of D+, He2+, N7+, Ne10+ and Si14+ are presented. Further on, results of an experiment measuring laser-induced recombination (LIR) into n=3 states of deuterium with polarized laser light are shown.

The enhancement of dielectronic recombination by applied electric fields has been observed and measured for the first time in a wide range of controlled and measurable fields using multiply charged ions. The heavy ion storage ring, CRYRING, at Stockholm University was used to store a beam of Si11+ and collide it with a cold electron target. The observation of a substantial monotonic increase of the rate coefficient for the group of higher Rydberg states is in puzzling disagreement with theoretical calculations of electric field enhanced dielectronic recombination.

The origin of the widely observed enhancement of rates for electron-ion recombination at very low energies is still unknown. We investigated the recombination of Au25+ with free electrons in a merged-beams experiment at the UNILAC accelerator of the GSI in Darmstadt. At Erel= 0 eV we found an enormous enhancement factor of 365 compared to the theory of radiative recombination. An increase of the electron density by a factor of 10 had not much influence on the measured rate coefficient.

The enhancement of dielectronic recombination by applied electric fields has been observed and measured for the first time in a wide range of controlled and measurable fields using multiply charged ions. The heavy ion storage ring, CRYRING, at Stockholm University was used to store a beam of Si11+ and collide it with a cold electron target. The observation of a substantial monotonic increase of the rate coefficient for the group of higher Rydberg states is in puzzling disagreement with theoretical calculations of electric field enhanced dielectronic recombination.

We have measured electron - ion recombination rates for bare ions of , , , and in a storage ring. For the multi-charged ions an unexpected energy dependence was found, showing a strong increase of the measured rates over the calculated radiative recombination rate for electron beam detuning energies below the electron beam transverse temperature. The measured enhanced rates increase approximately as with the charge state Z. A comparison of these rates with theoretical predictions for collisional - radiative recombination in the cold magnetized electron plasma, in particular three-body recombination including radiative de-excitation of electrons in Rydberg levels, is made.

In two separate experiments at the ESR recombination of 230 MeV/u Bi80+ and 170 MeV/u U89+ ions was studied. The analysis of these experiments has been carried on in order to extract information about radiative recombination (RR) of very highly charged ions exposed to electrons with a density of few 106 cm-3. In the light of the recombination rate enhancement seen in almost all recent experiments at a relative energy Erel = 0 eV, a surprising result is found for the very highly charged ions, which could add some confusion to an already puzzling picture: in spite of the high charge state of the investigated ions there is no evidence of enhanced recombination beyond the expected RR rate. This observation appears to be supported by other experimental findings at the ESR as well. We suspect, however, that this is a consequence of excessive transverse magnetic field components in the ESR cooler (which have meanwhile been corrected for) causing variable degrees of angular mismatch between the ion beam and the electron beam occurring when the ring settings are tuned for optimum cooling.

Recombination of multiply charged ions with electrons at very low relative energies has become a major topic of interest, due to the observation of rates which are enhanced beyond the expectations for radiative recombination. We present results for Ar16+ and Ar18+ ions from systematic measurements along the argon isonuclear sequence using a high density cold electron beam target (ne = 7 × 109 cm-3) at the UNILAC of GSI. The transverse and longitudinal temperatures of the electron beam were determined from DR resonance features observed with metastable Ar16+ (23S) ions. The rate at Erel = 0 for radiative recombination of completely stripped Ar18+ calculated with electron beam temperatures kT∥ = 0.002 eV, kT⊥ = 0.2 eV amounts to α = 10-9 cm3 s-1. This is exceeded by nearly a factor of 10 by the rate measured in experiments with Ar18+ ions.

The measurement of dielectronic recombination (DR) with high energy resolution provides a unique tool for precision spectroscopy of intermediate doubly excited states of very highly charged ions. One of our experimental goals at the experimental storage ring (ESR) of GSI is the determination of the 2 s 1 2 -2 p 1 2 energy splitting e in high-Z Li-like ions. This requires electron-ion center-of-mass energies for DR measurements up to about 300 eV, which is not easily accessible with the cooling device of the ESR as long as it has to guarantee the cooling of the stored ion beam. In a new experiment with 150 MeV/u Au76+ we were able to extend the accessible energy range to a maximum of about 300 eV, which requires a variation of the electron laboratory energy of up to 10 keV. New experimental data for recombination of U89+ and Au76+ ions were obtained. In particular, the group of ( 2 p 3 2 6l ) resonances in e + Au76+(1s22s) collisions could be completely observed with good energy resolution. In addition, the first resonances of the ( 2 p 1 2 n l ) Rydberg sequence with n = 20 to n = 26 were measured. By an extrapolation of the resonance energies to n = ∞, i.e. to the series limit, the energy e can be determined.

Absolute rates and cross sections for dielectronic recombination and ionization of Na-like Fe15+ (1s22s22p63s) ions were measured at electron impact energies between 0 and 1030 eV using the Heidelberg heavy ion storage ring TSR with the cooling device as an electron target. In the region where excitation-autoionization and related resonant processes are relevant, variations of the ionization cross sections below 0.5% were observed with an energy resolution of 4 to 5 eV FWHM. The theoretical calculations are in good overall agreement with the measured cross sections but do not reproduce all the details of the rich resonance structures revealed by our experiment. In the lower energy range we made use of the magnetically expanded electron beam with a transverse temperature corresponding to only kT⊥ = (15 ± 3) meV. This resulted in an excellent energy resolution in the measurements of dielectronic recombination associated with 3s → 3p, 3d, 4l core excitations. Here, theory and experiment are in very good agreement.

Dielectronic recombination (DR) of Ar15+(1s22s) ions was studied in a single-pass merged-beams experiment at the UNILAC (universal linear accelerator) of GSI. Absolute recombination rates and cross sections were measured for electron-ion center-of-mass energies from 0 to 580 eV. A number of Rydberg states formed by DR with 2s → 2p (Δn=0) and 2s → 3l (Δn=1) core excitations and even individual terms in the 1s23l3l′ configuration could be resolved. Theoretical calculations of DR cross sections are in good overall agreement with the data. In the calculations for Δn=0 transitions, effects of electric fields have to be included to reproduce the magnitude of the measured DR rates at the limit of the 2p1/2l and 2p3/2l Rydberg series. Discrepancies between theory and experiment are observed at the series limits of the (1s23lnl′) Rydberg series.

This paper reports a measurement of radiative recombination rates for U28+ ions and free electrons at energies from 0 to 2 e V. The results appear to contradict known theories.

We have calculated a large grid of hydrogen-rich supernova photospheres, in which radii, effective temperatures, density profiles, and expansion velocities have been varied. Spherical geometry, radiative equilibrium and LTE level populations are assumed. In the quasi-exact radiative transfer, the dilution of the radiation field, and scattering as well as absorption (by all relevant continuous processes and up to 150 000 lines in some models) are accurately considered. Good agreement can be obtained with the UV and IR spectra of supernovae 1979C, 1980K, and 1987A as observed during the coasting phase. Potential methods of parameter determinations for SN II are briefly discussed.

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Model atmospheres for supernovae of type II have been calculated taking into account the effects of sphericity and velocity fields. We obtain a good fit for the energy distribution of the recent supernovae SN 1980 K and SN 1987 A.

Laser induced radiative recombination (LIR) to the n=3 states of deuterium was studied at the storage ring CRYRING. The aim of this work is to better understand the origin of the below threshold gain observed in such experiments. A beam of 23 MeV/amu D+ ions was stored and phase-space cooled in the storage ring. The rate of radiative recombination into the n=3 states of deuterium was enhanced over the spontaneous rate by overlaping linearly polarized laser radiation from a one-state optical parametric oscillator (OPO) system to the ion-electron interaction region in the cooler. To probe for directional effects in the below threshold gain we rotated the polarization direction of the laser with respect to the direction of an induced transverse electric field obtained by displacing the center of the electron beam from that of the ion beam.

Recombination of highly charged ions with electrons is studied by accelerator based merged-beams experiments. In most measurements excessively high recombination rates are observed at low relative energies which cannot be explained by ordinary radiative recombination. The enhanced rates lead to serious losses of ions during the electron cooling process in ion storage rings. Another type of rate enhancement, known from previous experiments on dielectronic recombination, is related to external fields in the electron-ion collision region. By introducing controlled electric fields in the cooler of a storage ring it has been possible for the first time to obtain quantitative results for effects of electric fields on dielectronic recombination of highly charged ions.

In a single‐pass merged‐beams experiment employing a dense cold electron target recombination of highly charged ions is studied. Unexpected high recombination rates are observed at low energies Ecm in the electron‐ion center‐of‐mass frame. In particlar, theoretical estimates for radiative recombination are dramatically exceeded by the experimental recombination rates at Ecm=0 eV for U28+ and for Au25+ ions. Considerable rate enhancement is also observed for Ar15+. This points to a general phenomenon which has to be interpreted as a consequence of high electron densities, low electron beam temperatures, high ion charge states and presence of strong magnetic fields.

We report measurements on radiative and dielectronic recombination (RR and DR) of very highly charged ions at energies Ecm=0 to 50 eV. Novel techniques were employed at the heavy ion storage ring ESR to obtain absolute recombination rates of Au76+(1s22s). The increase of the RR rate for Ecm→0 could be recorded and single DR resonances in Au75+(1s22p3/26lj) resolved. The experimental data are compared to theoretical results for RR and DR. The calculations for RR are based on the Bethe‐Salpeter approach for completely stripped ions corrected to match Stobbe’s theory and corrected for the presence of several core electrons in the ions studied here. The theoretical RR rates are combined with results for DR from perturbative‐relativistic, semi‐relavistic and fully relativistic theories. There is remarkable agreement between theory and experiment. Nevertheless the high quality of the experimental data allows one to distinguish between the different theoretical approaches to DR.

Dielectronic recombination (DR) of AR15+(1s22s) ions was studied in a single‐pass merged‐beams experiment at the UNILAC accelerator of GSI. Absolute recombination rates and cross sections were measured for electron‐ion center‐of‐mass energies from 0 to 580 eV. A number of Rydberg states formed by DR with Δn=0 and Δn=1 core transistions and even individual terms in the 1s23l3l’ configuration could be resolved. Theoretical calculations of DR cross sections are in good overall agreement with the data. In the calculations for Δn=0 transitions effects of electric fields have to be included to reproduce the magnitude of the measured DR rates at the limit of the 2p1/2nl and 2p3/2nl Rydberg series. Discrepancies between theory and experiment are observed at the series limits of the (1s23lnl’) Rydberg series.

We report the first measurements on radiative and dielectronic recombination (RR and DR) of very highly charged ions at energies ${\mathit{E}}_{\mathrm{cm}}$ as low as 0 to 50 eV. Novel techniques were employed at the heavy-ion storage ring ESR to obtain absolute recombination rates of ${\mathrm{Au}}^{76+}$(1${\mathit{s}}^{2}$2s). The increase of the RR rate for ${\mathit{E}}_{\mathrm{cm}}$\ensuremath{\rightarrow}0 could be recorded and single DR resonances in ${\mathrm{Au}}^{75+}$(1${\mathit{s}}^{2}$2${\mathit{p}}_{3/2}$6${\mathit{l}}_{\mathit{j}}$) resolved. The experimental data allow sensitive judgement of calculations based on the Bethe-Salpeter approach to RR combined with results for DR from perturbative-relativistic, semirelativistic, and fully relativistic theories. Significant discrepancies are found only in the energy region of the 2${\mathit{p}}_{3/2}$6${\mathit{l}}_{3/2}$ resonances.

In the absence of clinically positive regional nodes, any value of prophylactic dissection in malignant melanomas depends on accurate preoperative determination of the pathway of lymphatic drainage. We report on the use of noninvasive radionuclide lymphoscintigraphy in the determination of regional patterns of lymph node drainage in patients with melanomas. Ten patients were studied; treatment was altered by test results in 2. Eleven node groups were excised in 7 patients. There have been no metastatic melanomas found in any nodal basins not detected by lymphoscintigraphy 23 to 42 months after operation.

Recombination of highly charged ions and free electrons is studied in interacting‐beam experiments. Beside direct recombination into bound states by radiative capture a variety of resonant recombination phenomena is observed. Resonant recombination produces a highly excited, usually short lived electron‐ion compound which can stabilize by the emission of photons and/or electrons. Depending on this emission, the final charge state of the ion can be one less than the parent charge state, but it can also be higher and thus a net single or multiple ionization of the ion is observed after the initial recombination.

• Patients with a rising serum carcinoembryonic antigen level and no clinical or roentgenographic evidence of recurrent or metastatic cancer present a treatment dilemma. Eleven such patients, 10 with a previously treated colorectal carcinoma and 1 with a previously treated breast carcinoma, received an injection of the anticarcinoembryonic antigen monoclonal antibody ZCE-025 labeled with the radioisotope indium 111. Nuclear scintigraphy was performed on days 3 and 5 through 7 to detect potential sites of tumor recurrence. The monoclonal antibody scan accurately predicted the presence or absence of occult malignancy in 7 (64%) patients. Second-look laparotomy confirmed the monoclonal antibody scan results in the patients with colorectal cancer, and magnetic resonance imaging confirmed metastatic breast cancer. This study demonstrates that In-ZCE-025 can localize occult carcinoma and may assist the surgeon in facilitating the operative exploration. In-ZCE-025 assisted in the initiation of adjuvant therapy for the patient with breast cancer. ( Arch Surg . 1990;125:866-870)

This paper reports a measurement of radiative recombination rates for U28+ ions and free electrons at energies from 0 to 2 eV. The results appear to contradict known theories.

Recombination of Au25+-ions has been investigated in a single-pass merged-beams experiment at the UNILAC of GSI in Darmstadt. Very low energies in the electron-ion center-of-mass frame were particularly addressed. At Erel = 0 eV we found a recombination rate exceeding the expectations by a factor of 365. For further investigation of this enhancement, the electron density and the magnetic field guiding the electron beam were varied. While an increase of the electron density by a factor of 10 had little influence, the measured rate coefficient increased significantly with the magnetic field strength.

The enhancement of dielectronic recombination of multiply charged ions by external electric fields has been studied under controlled conditions. The heavy ion storage rings CRYRING at Stockholm University and the heavy ion storage ring TSR at the Max-Planck-Institut in Heidelberg were used to store beams of Si11+ (ion energy 280 MeV) and Cl14+ (ion energies 250 MeV and 110 MeV), respectively. Recombination in the electron cooler has been measured over energy ranges covering all resonances due to 2s → 2p core exitation. External electric fields up to 183 V/cm at CRYRING and up to 379 V/cm at the TSR have been applied. In the TSR experiment the influence of different magnetic guiding fields as well as the influence of different electron densities in the electron cooler on the recombination rate was investigated. A significant rate enhancement was found for 1s22pnl Rydberg resonances with n > 25 for Si11+ ions and n > 20 for Cl14+ ions.

The photoluminescence is investigated of n-type glow-discharge prepared a-Si:H, where the doping is varied by in- and out-diffusion of Li. The appearance of a luminescence band at 0.8 eV is due to the decrease of the high-energy (1.2 eV) band which is explained by generation of defects. The intensity of the high-energy band can be restored by annealing without changing the doping state of the Si films. Die Photolumineszenz von amorphen, n-dotierten Si: H-Schichten wird untersucht. Dabei wird die Dotierung durch Ein- und Ausdiffusion von Li verandert. Das Auftreten einer zusatzlichen Lumineszenzbande bei 0,8 eV mit wachsender Dotierung ruhrt von einer Abnahme der 1.2 eV-Bande her. Diese Abnahme wird dadurch erklart, das durch Dotierung Netzwerkdefekte erzeugt werden. Durch Tempern kann die ursprungliche Intensitat der 1.2 eV-Bande wieder erreicht werden, ohne den Dotierungszustand der Schicht wesentlich zu verandern.

A review of the literature reveals a paucity of reported instances of distant intentional or non-intentional transplantation of carcinoma in the same patient. Such a phenomenon differs from local recurrence following operation, and also from distant metastasis. Again it is unlike the interesting case, described by Lecene and Lacassagne (1), of a medical student who, while aspirating serum from the wound following a radical mastectomy, accidentally injected some of the fluid into the deep tissues of the palm of his hand. Two years later a carcinoma appeared at the site of the inoculation, and despite the lack of microscopic resemblance, was regarded as being in all probability a transplanted mammary carcinoma. Cornil (2) speaks of an instance where a spindle-cell sarcoma of one breast was transplanted to the opposite breast. When the transplant had attained the size of an almond it was removed and histologically confirmed as the original process. This seems to be the only case on record where such a transplantation was deliberately made. Ewing (3) states: “From the period when vaccine treatment was very widely employed, I have learned of four cases in which tumors grew from injected unkilled cells in the vaccine…. The study of spontaneous tumor metastases removes the necessity of experimental evidence in this field.”

One hundred fifty-eight patients with aseptic meningitis were studied electroencephalographically during the acute phase of the illness. Slow activity was more common among children below 10 years of age (44%) than among adults (10%). With the exception of two cases, the electroencephalogram either normalized quickly after recovery from the acute illness or returned to what was believed to be the pre-illness abnormality. In one of the two persons who developed persistent abnormalities, slow activity continued long after the acute phase of the illness was over, and in the other the slow activity was complicated by the development of 6-per-second positive spike discharges. See figure in the PDF.file See table in the PDF.file See figure in the PDF.file Slow activity in the acute phase of the illness was more common when the infection was caused by ECHO virus (26%) than when it was caused by Coxsackie (14%). The sporadic cases of aseptic meningitis that were usually caused by a nonidentifiable agent were associated with a slightly higher electroencephalographic morbidity than the cases occurring in epidemics of known etiology. From the electroencephalographic as well as from the clinical point of view, aseptic meningitis is relatively benign. It is associated with less disorder than measles, which produces slow activity in 50% of cases. About as many patients developed slow activity during the acute phase of aseptic meningitis (33%) as mumps, but like mumps (and various other virus infections) aseptic meningitis can be followed by persistent electroencephalographic abnormalities. Because the viruses that cause aseptic meningitis may produce lasting brain disorder, they cannot be considered innocuous or inconsequential.

Serial electroencephalograms were done on 189 patients having measles with no clinical evidence of involvement of the nervous system. Using stringent criteria, 74 patients had considerable abnormality of the electroencephalogram. These findings could not attributed to any complications. Only one patient under 1 year of age (11 months) had evidence of electroencephalographic abnormality. The abnormalities observed were qualitatively and normalities observed were qualitatively and quantitatively similar to those seen in measles encephalitis, in most cases reverting to normal within 1 week. Approximately 4% had some residual electroencephalographic abnormality.