Fabrication of free-standing lithium niobate nanowaveguides down to 50 nm in width

Nonlinear optical nanoscale waveguides are a compact and powerful platform for efficient wavelength conversion. The free-standing waveguide geometry opens a range of applications in microscopy for local delivery of light, where in situ wavelength conversion helps to overcome various wavelength-dependent issues, such as biological tissue damage. In this paper, we present an original patterning method for high-precision fabrication of free-standing nanoscale waveguides based on lithium niobate, a material with a strong second-order nonlinearity and a broad transparency window covering the visible and mid-infrared wavelength ranges. The fabrication process combines electron-beam lithography with ion-beam enhanced etching and produces nanowaveguides with lengths from 5 to 50 μm, widths from 50 to 1000 nm and heights from 50 to 500 nm, each with a precision of few nanometers. The fabricated nanowaveguides are tested in an optical characterization experiment showing efficient second-harmonic generation.

Enhancing second harmonic generation in gold nanoring resonators filled with lithium niobate

Plasmonic nanorings provide the unique advantage of a pronounced plasmonic field enhancement inside their core. If filled with a polarizable medium, it may significantly enhance its optical effects. Here, we demonstrate this proposition by filling gold nanorings with lithium niobate. The generated second harmonic signal is compared to the signal originating from an unpatterned lithium niobate surface. Measurements and simulation confirm an enhancement of about 20. Applications requiring nanoscopic localized light sources like fluorescence spectroscopy or quantum communication will benefit from our findings.

High-frequency stimulation of the subthalamic nucleus inhibits the firing of juxtacellular labelled 5-HT-containing neurones

High-frequency stimulation (HFS) of the subthalamic nucleus (STN) is an established neurosurgical therapy for movement disability in advanced Parkinson's disease (PD), but some patients experience psychiatric side-effects like depression. In a previous electrophysiological study, we observed that HFS of the STN inhibited a population of neurones in the rat dorsal raphe nucleus (DRN), with firing properties characteristic of 5-HT neurones. The present study extended these findings to a second population of neurones, and combined extracellular recording with juxtacellular-labelling to investigate the chemical identity of the neurones affected by HFS. Bilateral HFS (130 Hz, 100-200 μA, 5 min) of the STN inhibited (26.0±2.9%) the firing of 37/74 DRN neurones displaying a slow, regular firing pattern. Slower firing neurones were more strongly inhibited than those firing faster. Importantly, 10 inhibited DRN neurones were juxtacellular-labelled with neurobiotin, and all neurones contained 5-HT as shown by post-mortem 5-HT immunocytochemistry. A minority of slow firing DRN neurones (18/74) were activated by STN HFS (37.9±8.3%) which was not observed previously. Of these neurones, three were juxtacellular-labelled and one was 5-HT immunopositive. Also a small number of DRN neurones (19/74) did not respond to HFS, four of which were juxtacellular-labelled and all contained 5-HT. These data show that individual chemically-identified 5-HT-containing neurones in the DRN were modulated by STN HFS, and that the majority were inhibited but some were activated and some failed to respond. These data extend previous findings of modulation of the 5-HT system by STN HFS but suggest a destabilisation of the 5-HT system rather than simple inhibition as indicated previously. Although the mechanism is not yet known, such changes may contribute to the psychiatric side-effects of STN stimulation in some PD patients.

Ultrathin membranes in x-cut lithium niobate

Ion-beam enhanced etching is used to pattern a bulk lithium niobate crystal with ultrathin membranes. By the implementation of an air gap beneath the membrane, high index contrast is achieved. A buried amorphous layer, created by irradiation with He ions, is removed by means of wet chemical etching in hydro-fluoric acid. Membranes having thicknesses down to 200 nm are fabricated. The etched air gaps and the membranes exhibit a uniform thickness over the entire etched area, and their widths can be purposefully adjusted over a wide range by choosing appropriate ion energies and fluences as well as annealing conditions.

Fabrication of ridge waveguides in zinc-substituted lithium niobate by means of ion-beam enhanced etching

We present results on the fabrication and characterization of ridge waveguides in zinc-substituted lithium niobate. High-quality waveguides were fabricated by a combination of liquid-phase epitaxy and multiple applications of ion-beam enhanced etching. The two major demands on ridge waveguides, a very low side-wall roughness and a rectangle shape with side-wall angles close to 90 degrees , were realized simultaneously by using this technique. Single-mode waveguiding at a wavelength of 1064 nm was demonstrated with attenuation values of 0.9 dB/cm.

Effects of essential oils from fennel (Foeniculi aetheroleum) and caraway (Carvi aetheroleum) in pigs

The ban of antibiotics as a feed additive requires alternatives to stabilize the health and performance particularly of the young animals. Essential oils obtained from fennel seed (Foeniculi aetheroleum) and caraway seed (Carvi aetheroleum) were tested in diets for weaned piglets in comparison with either a diet without feed additive or with a combination of formic acid and copper (positive control). Four groups of sixteen piglets (live weight 7 kg, age 26 days) received diets without (1) or with supplements of 7.5 g formic acid + 160 mg Cu/kg (2), 100 mg fennel oil/kg (3) or 100 mg caraway oil/kg (4) during 3 weeks after weaning. In the subsequent 4 weeks, all piglets were fed a diet without these additions. Fennel oil contained almost 2/3 anethol, approximately 1/5 fenchon and the remaining part consisting of alpha + beta-pinen, limonen (p-mentha-1,8-dien) and estragol. In the caraway oil, half of the contents was represented by limonen and the other half by carvon. There were no piglet losses and only few cases of diarrhoea. The combination of formic acid and copper increased feed consumption by 27% and daily weight gain by 25%. There were no differences in the performance between the group fed fennel oil and the control without additives. Piglets fed caraway oil tended to consume less feed and to gain approximately 10% less. In feed choice experiments, pigs consumed the same two diets from two troughs with 50% of total feed amount, as expected. The diets containing fennel or caraway oils were consumed at less than 50%. If the diet contained 100 mg fennel oil/kg, the decrease of percentual feed intake was significant. The results of the feeding experiment and of the feed choice experiment question the classification of fennel and caraway oils as flavour additives or as 'appetite promoters' in diets for weaned piglets.

Characterizing the mechanisms of progression in multiple sclerosis: evidence and new hypotheses for future directions

Major advancements have been achieved in our ability to diagnose multiple sclerosis (MS) and to commence treatment intervention with agents that can favorably affect the disease course. Although MS exacerbations and the emergence of disability constitute the more conspicuous aspects of the disease process, evidence has confirmed that most of the disease occurs on a constitutive and occult basis. Disease-modifying therapies appear to be modest in the magnitude of their treatment effects, particularly in the progressive stage of the disease. Therapeutic strategies currently used for MS primarily target the inflammatory cascade. Several potential mechanisms appear to be involved in the progression of MS. Characterizing these mechanisms will result in a better understanding of the various forms of the disorder and how to effectively treat its clinical manifestations. It is our objective within this 2-part series on progression in MS to offer both evidence-based observations and hypothesis-driven expert perspectives on what constitutes the cause of progression in MS. We have chosen areas of inquiry that appear to have been most productive in helping us to better conceptualize the landscape of what MS looks like pathologically, immunologically, neuroscientifically, radiographically, and genetically. We have attempted to advance hypotheses focused on a deeper understanding of what contributes to the progression of this illness and to illustrate new technical capabilities that are catalyzing novel research initiatives targeted at achieving a more complete understanding of progression in MS.

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Since 2003 bread and fine bakery products must not contain more than 350 μg Deoxynivalenol (DON). As a prerequisite for the label "Geprüfte Qualität"-Thüringen [proved quality Thuringia] and since coming into force of the respective evaluation prescription a total of 25 breads and 41 fine bakery products was investigated by ELISA with regard of this compound. In the 66 samples of the year 2003 no DON concentrations above the limit were detected and in the preparation period 2001/2002 only one sample exceeded the maximum. In several samples, most narrow to the maximum limit, an additional determination by HPLC was performed which resulted in lower DON-concentrations as compared to the values analyzed by ELISA.

Analyse der Fettsäurenzusammensetzung des Rohfettes von Prüffutter für Schweine (Kurzmitteilung)

Abstract. Title of the paper: Analysis of the fatty acid composition of the raw fat from the feed of pigs which are examined to her performance (short communication) The raw fat of 14 examining feeds from 13 German performance testing centres for pigs was extracted 2001 and analysed for the fatty acid composition by means of gas chromatography. Besides a great variation of the raw fat content (s % = 42) was to state that with 14.4 g/kg feed on average the content of polyunsaturated fatty acids (PUFA) was high. Examinations of the raw fat of wheat, rye and barley showed that the high proportions in linoleic and linolenic acid are brought in the fattening rations primarily by the cereal components. A limitation of the PUFA proportions below 15 g/kg feed therefore doesn't seem to be practicable in the examining feed of performance testing centres for pigs. The additional variation in the fatty acid composition of examining feeds caused by added fats or oils should however be limited according to a better standardization.

Erhebungen zur Fettsäurenzusammensetzung von Rückenfett bei Thüringer Schweinen sowie zum Fett von Thüringer Knackwürsten aus dem Einzelhandel

Abstract. Title of the paper: Examinations to the fatty acid composition of backfat at Thuringian pigs as well as to the fat of Thuringian cracking sausages from the retail trade The fat from the outer back bacon of Thuringian pigs (n = 751) was examined several years with regard to their fatty acid composition. The content of polyunsaturated fatty acids (PUFA) ranged at the backfat from 7.3 to 12.7% and the relationship of the n-6 and n-3 fatty acids varied from 4.4 to 11.3. PUFA contents in the backfat > 12 % were explained by high C18:2 or C18:3 contents of the food. Examination of the fatty acid composition of the fat of 21 fresh cracking sausages from the Thuringian retail trade on a random basis yielded, that the contents of PUFA and linolenic acid ranged from 6.2 to 15.8 % respectively from 0.8 to 2.0 % as well as the quotient of n-6 to n-3 fatty acids varied from 3.6 to 10.3.

Effects of rapeseed-press cake glucosinolates and iodine on the performance, the thyroid gland and the liver vitamin A status of pigs

Rapeseed press cake (per kg DM 181 g EE, 341 g CP and 23.3 mmol glucosinolates) was tested in a long-term experiment with a total of sixty pigs (live weight range 24 to 104 kg). The 3 x 2 factorial design consisted of three rapeseed press cake levels (no rapeseed press cake--control, 75 g or 150 g rapeseed press cake per kg diet) each with two iodine dosages (125 or 250 micrograms supplementary iodine per kg diet). Reduced feed intake and depressed weight gain were found in groups receiving 150 g rapeseed press cake per kg diet, which correspond to 3.2 mmol glucosinolates per kg diet. At an inclusion level of 75 g rapeseed-press cake per kg diet no differences in feed intake and growth intensity were recorded in comparison to the rape feed free control. The rapeseed-press cake diet increased the weight of thyroid gland and liver and decreased the serum thyroxine (T4) concentration. Higher iodine dosage increased the serum T4 concentration of pigs receiving 75 g rapeseed press cake per kg diet (= 1.6 mmol glucosinolates per kg diet) to the level of the control group and retarded the enlargement of the thyroid gland. Intake of rapeseed products lowered the iodine content of the thyroid gland, however, there was no significant difference between groups given 1.6 and 3.2 mmol glucosinolates per kg diet. The vitamin A content of the whole liver and the vitamin A serum concentration were not influenced by the diets tested. However, rapeseed press cake and the glucosinolates, respectively, decreased the vitamin A concentration per gram liver due to the organ enlargement and the resulting dilution effect.

Erhebungen zum Hämpigmentgehalt, zu Reflexionswerten sowie zum Fettsäurenmuster des intramuskulären Fettes vom <i>Musculus longissimus dorsi</i> (M.l.d.) Thüringer Rinder in Abhängigkeit von Mastform und Rassetyp

Abstract. Title of the paper: Investigations into the haem pigment content, reflection results as well as into the fatty acid pattern of the intramuscular fat of the Musculus longissimus dorsi (M.l.d.) Thuringian cattle, dependent on fattening system and genotype Haem pigment content, the reflection in visible range and the fatty acid pattern of intramuscular fat (imf) from minced musculus longissimus dorsi (m.l.d.) at the 8th / 9th dorsal vertebra of the right half of the carcass were determined in 35 cattle groups with bulls, steers and heifers, representing 19 different genotypes. The cattle were fattened indoors and/or outdoors at eight farms in Thuringia. The mean values of the haem pigment content varied between the animal groups from 6.3 to 13.1 mg/g fresh meat. A clearly lower variation was found in the maxima of reflectance at 415, 545 and 580 nm. The fatty acid composition of the imf was determined mainly by the fattening system. Fattening on pasture favoured high proportions of polyunsaturated fatty acids as well as a ratio of n6- to n3-fatty acids of < 10. The imf-content was positive correlated to the proportion of C18:1 and monounsaturated fatty acids (R = 0.4** / 0.5**) as well as negative to the proportion of polyunsaturated fatty acids (R = −0.7**).

Monitoring of fusarium toxins in cereals and feed-stuffs from thuringia (1998 - 2001)

From 1998 to 2001 a total of about 1172 conventionally and organically produced samples of wheat, rye, barley and triticale were examined for the presence of deoxynivalenol (DON) and zearalenone (ZON). Furthermore, feedstuffs for pigs were included in the monitoring of Fusarium toxins. DON and ZON analyses were performed using ELISA or HPLC. The incidences and levels of toxins varied from year to year. Overall contamination levels were highest in wheat and triticale, followed by rye and barley. The highest DON contaminations were found in 1998. The probes of the years 1999-2001 showed lower incidences of Fusarium toxins. The second examined mycotoxin ZON was detected at lower levels in cereals. Similar results were observed in the monitoring of feedstuffs.