FLUTE: a versatile linac-based THz source.

A new compact versatile linear accelerator named FLUTE is currently being designed at the Karlsruhe Institute of Technology. This paper presents the status of this 42 MeV machine. It will be used to generate strong (several 100 MV/m) ultra-short (~1 ps) THz pulses (up to ~4-25 THz) for photon science experiments, as well as to conduct a variety of accelerator studies. The latter range from comparing different coherent THz radiation generation schemes to compressing electron bunches and studying the electron beam stability. The bunch charge will cover a wide range (~100 pC-3 nC). Later we plan to also produce ultra-short x-ray pulses from the electron bunches, which, for example, could then be combined for THz pump-x-ray probe experiments.

The importance of cyclotorsional changes in refractive surgery.

PURPOSE: To provide evidence of the importance of a precise record of torsional alterations in all patients about to undergo refractive surgery and particularly in patients with latent strabismus that may become decompensated due to the dissociation phenomenon produced during different surgical procedures that result in fixation loss. METHODS: Using 3D-VOG video-oculography, the authors analyzed the horizontal, vertical, and torsional movements of each eye after inducing fixation loss in one and both eyes in a patient with well-compensated dissociated vertical deviation (DVD). As the dissociated techniques, Posner maneuver and the placing of Bagolini filters with increasing densities by means of the Bielschowsky phenomenon, both pathognomonic of DVD. RESULTS: The authors observed not only horizontal and vertical alterations, but also cyclotorsional alterations which may even exceed 15 degrees depending on the resulting dissociation component. CONCLUSIONS: In view of the obtained results, the authors consider it important to conduct a meticulous study of ocular motility in all patients about to undergo refractive surgery, especially in the case of high astigmatism to rule out possible latent strabismus that may condition cyclotorsional alterations important in refractive surgery.

Turkevich method for gold nanoparticle synthesis revisited.

The growth of gold nanoparticles by reduction by citrate and ascorbic acid has been examined in detail to explore the parameter space of reaction conditions. It is found that gold particles can be produced in a wide range of sizes, from 9 to 120 nm, with defined size distribution, following the earlier work of Turkevich and Frens. The reaction is initiated thermally or in comparison by UV irradiation, which results in similar final products. The kinetics of the extinction spectra show the multiple steps of primary and secondary clustering leading to polycrystallites.

Excitation of nanoscale vapor bubbles at the surface of gold nanoparticles in water.

Intense nonequilibrium femtosecond laser excitation of gold nanoparticles in water leads to a transient heating of the nanoparticles, which decays via heat transfer to the water phase. It is shown that the water temperature rises to near the critical temperature and the water undergoes an explosive evaporation in the subnanosecond range. The formation of vapor bubbles shows a threshold dependence on laser fluence. The nascent nanoscale vapor bubbles change the heat dissipation drastically. The nanoscale structure is resolved directly with a combination of x-ray scattering methods sensitive to the particle lattice expansion and the change in the water structure factor.

Recombination of photodissociated iodine: a time-resolved x-ray-diffraction study.

A time-resolved x-ray-diffraction experiment is presented that aims to study the recombination of laser-dissociated iodine molecules dissolved in CCl4. This process is monitored over an extended time interval from pico- to microseconds. The variations of atom-atom distances are probed with a milliangstrom resolution. A recent theory of time-resolved x-ray diffraction is used to analyze the experimental data; it employs the correlation function approach of statistical mechanics. The most striking outcome of this study is the experimental determination of time-dependent I-I atom-atom distribution functions. The structure of the CCl4 solvent changes simultaneously; the solvent thus appears as a reaction partner rather than an inert medium hosting it. Thermal expansion of the system is nonuniform in time, an effect due to the presence of the acoustic horizon. One concludes that a time-resolved x-ray diffraction permits real-time visualization of solvent and solute motions during a chemical reaction.

Picosecond x-ray studies of coherent folded acoustic phonons in a multiple quantum well.

Coherent folded acoustic phonons in a multilayered GaSb/InAs epitaxial heterostructure were generated by femtosecond laser pulses and studied by means of ultrafast x-ray diffraction. Coherent phonons excited simultaneously in the fundamental acoustic branch and the first back-folded branch were detected. This represents the first clear evidence for phonon branch folding based directly on the atomic motion to which x-ray diffraction is sensitive. From a comparison of the measured phonon-modulated x-ray reflectivity with simulations, evidence was found for a reduction of the laser penetration depth. This reduction can be explained by the self-modulation of the refractive index due to photogenerated free carriers.

Distribution of 125J-labeled leucopyrokinin (LPK) in rats.

The distribution in parts of the brain and internal organs of 125J-labeled leucopyrokinin (LPK), an insect myotropic peptide injected into the lateral brain ventricle was determined in rats. A high accumulation of this peptide in adrenals and in the hypothalamus and hippocampus of the brain was found. A lesser but significant LPK accumulation in other internal organs and parts of the brain was also observed. The significance of this effect for the biological activity of LPK in rats is discussed.

First investigations of the kinetics of the topochemical reaction of p-formyl-trans-cinnamic acid by time-resolved X-ray diffraction.

Under UV irradiation p-formyl-trans-cinnamic acid (p-FCA) crystals in the beta-phase dimerise irreversibly to solid 4,4'-diformyl-beta-truxinic acid. The experimental conditions were chosen in such a way (non-aqueous environment and room temperature) that the product formed is amorphous. The kinetics of this bimolecular reaction, which has not yet been characterised, was investigated by picosecond time-resolved X-ray diffraction. From the experimental results a mechanism for this topochemical reaction is proposed including two observed time constants, one less than 100 ps and another of several seconds. The feasibility of investigating this class of substances by time-resolved X-ray diffraction from third generation synchrotron sources and future free-electron lasers is discussed.

The effect of the leucopyrokinin analogue: [2-8]-leucopyrokinin on central opioid receptors in rats.

The antinociceptive effect of intracerebroventricular injections of [2-8]-leucopyrokinin (LPK), a truncated leucopyrokinin analogue, was determined in rats, by means of a tail immersion test. We found a significant antinociceptive effect of three i.c.v. doses of [2-8]-LPK: 1, 5 and 10 nmol. Pre-treating animals with naloxone hydrochloride (1 mg/kg i.p.) completely blocked the effect of two high doses of [2-8]-LPK. To determine the sub-types of opioid receptors involved in [2-8]-leucopyrokinin-induced analgesia we injected specific blockers of mu-, delta- and kappa-receptors namely, beta-funaltrexamine hydrochloride, naltrindole hydrochloride and nor-binaltorphimine dihydrochloride, respectively, prior to [2-8]-leucopyrokinin at equimolar doses. We conclude that the antinociceptive effect of [2-8]-leucopyrokinin is mediated mainly by central mu- and delta-opioid receptors.

[The effect of gamma-aminobutyric acid injected into lateral brain ventricle of rats after prenatal cadmium intoxication on flash visual evoked potentials (FVEP)]. / Wplyw kwasu gamma-aminomaslowego (GABA) podanego do komory bocznej mózgu szczurów po prenatalnej intoksykacji kadmem na odpowiedzi wzrokowych potencjalów wywolanych blyskami (FVEP).

PURPOSE: To find out any influence of gamma-aminobutyric acid (GABA) injected into lateral brain ventricle in newborn rats prenatally exposed to cadmium (Cd). METHOD: 18 white, Wistar, offspring rats were divided into 3 groups, each consisting of 6 rats (control, 5 ppm and 50 ppm of Cd in drinking water). Newborns were examined when they were 3-6 months old. FVEP were recorded before and after GABA injections. Two doses of GABA were used, 10 and 100 nmols. The statistic analysis with the test of t-Student was performed to estimate the amplitudes and latencies of the negative wave N1 and the next positive one P2. p < 0.05 was used to indicate significant difference. RESULTS: No significant changes in the latencies of peak N1 and P2 in the control and Cd 5 ppm groups (101-103%) after 10 nmols GABA were observed. However, the shortened (91-97%) of them was observed after both doses of GABA in Cd 50 ppm group. The mean value of amplitude of N1 in control rats increased to 127% after 10 nmols GABA and 142% after 100 nmols GABA. Moreover, the mean amplitude of P2 in this group increased to 108% and 146%, respectively. The high significant increase of the amplitudes of N1 (181-280%) and P2 (160-177%) waves were received after both doses of GABA in Cd groups. CONCLUSION: Cadmium increased the sensitivity of GABA-receptors in the OUN.

Influence of alternating low frequency magnetic fields on reactivity of central dopamine receptors in neonatal 6-hydroxydopamine treated rats.

The aim of this study was to evaluate the influence of extremely low frequency magnetic field (ELF MF) on the reactivity of the central dopamine D(1) receptor in rats with dopamine neurons chemically damaged by 6-hydroxydopamine (6-OHDA), an animal model of human's Parkinson's disease. The experiment was carried out on male Wistar rats. On day 3 of postnatal life, a lasting and selective chemical damage of the central dopamine system was induced in the rats by infusion of 6-OHDA HBr (133.4 microg intracerebroventricular, base form) given bilaterally into lateral ventricles of the brain. Control animals received similar treatments injecting only vehicle. At 2 months of age, both 6-OHDA treated and control rats were randomly divided into two groups. Rats from the first group were exposed to 10 Hz sinusoidal, 1.8-3.8 mT magnetic field one hour daily for 14 days. Rats of the second group were sham exposed, with the applicator solenoid turned off. On the day after the final exposure the evaluations were made of the rat's spontaneous irritability, oral activity, and catalepsy. The MF exposed rat with chemically induced dopamine neurons damage exhibited a reduction of irritability and oral activity when stimulated with SKF 38393 (the agonist of central dopamine D(1) receptor) and some increase of catalepsy after administration of SCH 23390(the antagonist of central dopamine D(1) receptor). These results indicate that ELF MF reduce the reactivity of central dopamine D(1) receptors in rats.

[The effect of serotonin on flash visual evoked potential in the rat prenatally exposed to cadmium]. / Wplyw kadmu stosowanego prenatalnie na wywolane blyskami wzrokowe potencjaly kory potylicznej mózgu potomstwa szczurów przed i po podaniu serotoniny do komory bocznej mózgu.

AIM: The purpose of this paper was to find out any influence of cadmium (Cd) on the effect of serotonin (5-HT) in the central nervous system (CNS). METHOD: 18 Wistar albino strain female rats were divided into 3 groups: 6 received 5 ppm, 6 one 50 ppm cadmium in tap water since time of conception and during next 21 days after delivery. Control group of 6 rats received tap water only. Newborns were examined when they were 3 to 6 months old. Flash visual evoked potential (FVEP) was recorded before and after injection of 10 microliters saline and then 5-HT into the right lateral brain ventricle. Two doses of 5-HT 125 and 250 nmols were used. Amplitudes of the first deep negative wave (N1) and the next positive one (P1) were measured from isoelectric line to peaks. For statistic analysis the t-test of Student was used with statistical significance by p < 0.05. RESULTS: Shortened latencies (89-99%) of the peaks N1 and P1 of FVEP in the control and Cd 50 ppm groups after both doses of 5-HT were observed, however, they slightly prolonged (103-105%) in the Cd 5 ppm group. The highly significant increase of amplitude of the waves N1 and P1 in all observed groups was received. The only differences were observed in the Cd 5 ppm group; the amplitude of P1 peak was of the same value (100-101%) after 125 nmols and decreased (91%) after 250 nmols of 5-HT compared to the initial values in this group. CONCLUSION: Cadmium increases the serotonin sensibility in the CNS.

[The long-term follow up after trabeculectomy]. / Dlugoterminowe wyniki operacyjnego leczenia jaskry metoda trabekulektomii.

THE AIM OF THE STUDY: To estimate the efficacy of trabeculectomy for primary open angle glaucoma. MATERIAL AND METHODS: Since 1990 to 2000 we observed 91 eyes of 79 patients (53 women and 26 men) aged 39-86. The results of performed surgery were valued directly after the trabeculectomy and in period of over 8 years. We carried out the examinations of visual acuity, intraocular pressure, visual field, state of optic nerve head, type of bleb following trabeculectomy and the necessity of applying additional topical treatment. The trabeculectomies were performed in a typical way. Some surgeons made a square or triangular superficial scleral flap based at the limbus, measuring from 2.5 x 3.0 to 4 x 4 mm or 3 x 3 mm. The deep block of scleral tissue with trabeculum (from 0.5 x 1.0 to 2.5 x 3.0 mm) was excised, the superficial cauterisation and the peripheral iridectomy were performed in every case. The scleral flap and conjunctiva were sutured with 10/0 Ethilon, 8/0 Vicryl or 6/0 Mersilk. RESULTS: The patients were divided into 3 groups depending on observation period: I--up to 4 years, II--from 5 to 8 years, III--over 8 years. We confirmed the normalisation of IOP in 80%, 73%, 90% and the successful control of visual field (no progress) in 82%, 77%, 70% of adequate groups. In the first and second group 45-50% of patients could resist from topical treatment, but after 8 years as many as 80% required additional pharmacological treatment. CONCLUSION: The trabeculectomy is the effective surgery in most patients with open angle glaucoma. The effectiveness of trabeculectomy can be controlled by the size of extracted deep scleral flap with trabeculum. For the stability of visual field it is necessary to keep the intraocular pressure at 13-18 mm Hg level.

Investigation of Structure and Growth of Self-Assembled Polyelectrolyte Layers by X-ray and Neutron Scattering under Grazing Angles.

The structure of self-assembled polyelectrolyte thin films on float glass has been investigated by interface sensitive X-ray and neutron scattering methods. Special emphazis was given to the adsorption process of poly (ethylene imine) and polystyrole sulfonate as an important model system which is often used as a basis for subsequent multilayer buildup. From complementary X-ray and neutron reflectivity data, the vertical film density profile was derived for various growth parameters, including kinetic effects of different adsorption times. In addition to specular reflectivity, we have for the first time employed nonspecular X-ray scattering to study lateral structure parameters in self-assembled polyelectrolyte films. Furthermore, the technique of time-resolved in situ X-ray reflectivity during film growth has been demonstrated and is discussed in view of its future potential. Copyright 2000 Academic Press.

[The effect of dopamine injected into the lateral brain ventricle on flash visual evoked potential (FVEP) after prenatal intoxication with cadmium]. / Wplyw dopaminy podawanej do komory bocznej mózgu szczurów na modulowanie odpowiedzi wzrokowych potencjalów wywolanych blyskami (FVEP) po prenatalnej intoksykacji kadmem.

PURPOSE: Earlier studies demonstrated that exposure, especially prenatal, of mammalians to cadmium (Cd) results in disorders of visual evoked potentials (FVEP). The purpose of this study is to find out any influence of cadmium intoxications on the effect of dopamine (DA) on FVEP. METHOD: 18 Wistar albino rats in 3-6 months of age were divided into 3 groups: control (drinking tap water only), prenatal exposure of 5 ppm, and 50 ppm Cd. Flash visual evoked potentials (FVEP) were recorded before and after injections of dopamine (DA) 100 and 200 nmols into the lateral brain ventricle. The amplitude and latency of N1 and P2 were statistically analysed by the test of t-Student. p < 0.05 was used to indicate significant difference. RESULTS: There were no statistical differences of mean latency of P2 waves between initial records of FVEP and after both doses of DA in all observed groups. The amplitudes of both waves increased after DA injections compared to initial values in all groups. The differences were statistically significant. The mean latencies of N1 peak were prolonged after both DA doses (106-109%) compared to the initial records (100%) in the control group; however, there were no changes of it in the Cd-treated groups before and after DA injections. CONCLUSION: Cadmium blocked the dopamine effect on the latencies of N1 and P2 of FVEP (because it prolonged them alone); however, cadmium increased the stimulative effect of dopamine on their amplitudes.

[The effect of prenatal exposure to cadmium on flash visual evoked potentials in rat offspring before and after injection of norepinephrine into the lateral brain ventricle]. / Wplyw kadmu stosowanego prenatalnie na wywolane blyskami wzrokowe potencjaly kory potylicznej potomstwa szczurów przed i po podaniu norepinefryny do komory bocznej mózgu.

AIM: It is known that norepinephrine (NE) in low doses increases the amplitude of flash visual evoked potential (FVEP). The purpose of this paper was to find out if cadmium (Cd) intoxication changes the NE effect on FVEP. MATERIAL AND METHODS: 18 Wistar albino rats were divided into 3 groups: 6 received 5 ppm, next 6 received 50 ppm cadmium in drinking water since time of conception and during 21 days after delivery and 6 as a control group received tap water only. Newborns were examined when they were 3 to 6 months old. FVEP were recorded before and after injection of 10 microliters saline and then NE into the right lateral brain ventricle. Two doses of NE 25 and 50 nmols were used. Amplitudes of the first deep negative wave (N1) and the next positive one (P2) were measured from isoelectric line to peaks. For statistic analysis the Student t-test was performed with statistical significance by p < 0.05. RESULTS: The prolongation of N1 and P2 latencies of FVEP was observed in all groups after both doses of NE, the differences were statistically significant after doses of 25 nmols NE. The amplitude of N1 increased after NE in all groups, in the control one till 205-225% and 143-151% in Cd groups. The amplitude of P2 in control group was higher (109-113%) after NE compared to initial value (100%). Cadmium caused the decrease (of 56-90%) after both doses of NE. The differences of amplitudes were statistically significant. The prenatal treatment by cadmium caused the lower sensitivity of FVEP to NE.

Insect neuropeptide leucopyrokinin analogues--synthesis and antinociceptive effect in rats.

The insect myotropic octapeptide leucopyrokinin Glp-Thr-Ser-Phe-Thr-Pro-Arg-Leu-amide (LPK or Lem-PK) (1) and its truncated analogues without the first N-terminal amino acids [2-8]-LPK (2) as well as devoid of the first, second and third N-terminal amino acids [4-8]-LPK (3) were prepared together with a series of the following modified [2-8]-LPK heptapetides such as: [Ala2] (4)-, [Ala3] (6)-, [D-Phe4] (7)-, [Ala5] (8)-, [D-Ala5] (9)-, [D-Thr5] (10)-, [Ser5] (11)-, [D-Pro6] (12)-, [Ala6] (13)- and [D-Arg7]-[2-8]-LPK (14) and [Pro1]-LPK (5). Bioassays were carried out by means of a hot-plate and a tail immersion tests in rats after i.c.v. and i.p. injections. Peptides 1 and 2 revealed prolonged high antinociceptive effects, while other peptides were practically inactive. [2-8]-LPK (2) probably crosses the blood-brain barrier in rats.

Enhanced oral activity responses to intrastriatal SKF 38393 and m-CPP are attenuated by intrastriatal mianserin in neonatal 6-OHDA-lesioned rats.

Enhanced oral activity is induced in neonatal 6-hydroxydopamine- (6-OHDA-) lesioned rats by systemic administration of the dopamine (DA) D1 receptor agonist SKF 38393 and serotonin (5-HT) 5-HT2A,2C agonist m-chlorophenylpiperazine (m-CPP). The DA D1 receptor antagonist SCH 23390 effectively attenuates the effect of SKF 38393 but not m-CPP. The 5-HT2 antagonist mianserin attenuates the effects of both m-CPP and SKF 38393, suggesting that DA agonist effects are mediated by 5-HT neurochemical systems. To test whether DA and 5-HT agonist effects and interactions might occur within the neostriatum, rats were implanted with permanent injection cannulae, with tips in the ventral striatum. One group of rats was lesioned at 3 days after birth with 6-OHDA HBr (100 micrograms salt form, in each lateral ventricle; desipramine HCl pretreatment, 20 mg/kg IP, base form, 1 h), while controls received the vehicle in place of 6-OHDA. Cannulae were implanted when rats weighed 200-250 g. During a 1-h observation session SKF 38393 (5 nmol per side) produced 74.3 +/- 19.2 oral movements in intact rats and 310.7 +/- 97.0 oral movements in 6-OHDA-lesioned rats. m-CPP (10 nmol per side) produced 72.6 +/- 15.1 and 274.5 +/- 65.0 oral movements in these respective groups. These responses were several-fold greater than the 25.3 +/- 7.3 and 41.8 +/- 9.5 oral movements in the same groups after saline (0.5 microliter per side) (P < 0.05). Mianserin (6 nmol per side) alone had no effect on oral activity but attenuated responses to both SKF 38393 and m-CPP in intact and 6-OHDA-lesioned rats.(ABSTRACT TRUNCATED AT 250 WORDS)

Enhanced quinpirole response in rats lesioned neonatally with 5,7-dihydroxytryptamine.

The ontogenic destruction of dopamine (DA) neurons in rat brain is associated with supersensitization of DA D1 receptors. This effect is attenuated when rats are cotreated in ontogeny with the serotonin (5-HT) neurotoxin, 5,7-dihydroxytryptamine (5,7-DHT). In an attempt to determine whether 5-HT fibers might have a similar modulatory role on the sensitivity of the DA D2 receptor complex, we pretreated rats with desipramine HCl (20 mg/kg, IP, base), 1 h before the DA neurotoxin, 6-hydroxydopamine (6-OHDA; 134 micrograms ICV, base) and/or 5,7-DHT (75 micrograms ICV) and/or vehicle. At about 3 months after birth dose-effect curves for quinpirole-induced oral activity were constructed for each group of rats. We found that quinpirole, an agonist for the DA D2 receptor complex, produced a dose-related increase in oral activity in all groups of rats. After a 200 micrograms/kg dose of quinpirole HCl, however, neonatal 5,7-DHT-lesioned rats had a peak oral response of 54.4 +/- 5.1 (mean and SEM) vs. 22.6 +/- 4.8 for control rats (p < 0.01). In neonatal 6-OHDA-lesioned rats this dose of quinpirole increased oral activity to 36.8 +/- 5.8 oral movements (p < 0.05 vs. control). In rats lesioned with both 5,7-DHT and 6-OHDA, the oral response was not different from control. The enhanced oral response to quinpirole in 5,7-DHT-lesioned rats was attenuated by spiperone, an antagonist for the DA D2 receptor complex.(ABSTRACT TRUNCATED AT 250 WORDS)

Prenatal ethanol diminishes reactivity of presumed dopamine D3 receptors in rats.

Ethanol abuse in pregnancy is known to produce serious damage to the developing central nervous system of mammalian species. As with several other classes of nerves, the ontogenetic influence of ethanol on dopamine (DA) nerves is long-lived. To test whether reactivity of DA receptors might be altered by prenatal ethanol administration, rats were given 10% (v/v) ethanol in their drinking water, starting 10 days before mating and continuing to the end of pregnancy. Male offspring were tested at 3 months for behavioral effects known to be induced by DA agonists acting at specific subtypes of DA receptors. The oral activity dose-effect curve for SKF 38393, a DA D1 agonist, was not altered from control. However, quinpirole-induced yawning behavior, reputedly a DA D3-associated event, was markedly impaired in the male rats that had been exposed in utero to ethanol. These findings indicate that prenatal ethanol exposure may predominately produce diminished reactivity of the DA D3, but not DA D1 subtype of DA receptor.