3D printed dielectric rectangular waveguides, splitters and couplers for 120 GHz.

We use a 3D printer to fabricate rectangular dielectric single mode waveguides for 120 GHz. The rectangular waveguides consisting of polystyrene showed an attenuation of 6.3 dB/m, which is low enough for short devices. We also characterize 3D printed Y-splitters and a 1x3-splitter based on multimode interference. Further, we construct and measure a variable planar waveguide coupler which can be used as a 3-dB coupler, a cross-coupler and no coupler at all.

Influence of plasma pretreatment on shear bond strength of self-adhesive resin cements to polyetheretherketone.

OBJECTIVES: The aim of this study is to evaluate the adhesion between PEEK and two self-adhesive resin cements after plasma treatment. METHODS: Eight hundred sixty-four polyetheretherketone (PEEK) disks were cut and polished to silicon carbide (SIC) P4000. One half of the specimens were randomly selected and pretreated with plasma, whereas the remaining 432 specimens remained untreated. Subsequently, specimens were randomly allocated to four groups (n = 108/group): Visio.link (Bredent), Signum PEEK Bond (Heraeus Kulzer), Ambarino P60 (Creamed), and a control group without additional treatment. Half of the specimens of each group (n = 54) were then cemented with either RelyX Unicem Automix 2 (3 M ESPE) or with Clearfil SA (Kuraray). All specimens were stored in water for 24 h (37 °C). Afterwards, specimens were divided into three groups (n = 18) for different aging levels: (1) no aging (baseline measurement), (2) thermal aging for 5,000 cycles (5/55 °C), and (3) thermal aging for 10,000 cycles (5/55 °C). Thereafter, shear bond strengths (SBS) were measured, and failure types (adhesive, mixed, and cohesive) were assessed. Data were analyzed using descriptive statistics, four- and one-way ANOVA followed by a post hoc Scheffé test (p < 0.05). RESULTS: No adhesion could be established without adhesive pretreatment, irrespectively, whether plasma was applied or not. Also, no bond strength was measured when Ambarino P60 was applied. In contrast, adhesive pretreatment resulted in SBS ranging between 8 and 15 MPa. No significant differences were found between the resin cements used. In general, no cohesive failures were observed. Groups without plasma treatment combined with Visio.link or Signum PEEK Bond showed predominantly mixed failure types. Control groups, plasma treated, or treated using Ambarino P60 groups fractured predominantly adhesively. CONCLUSION: The use of methyl methacrylate (MMA)-based adhesives allows bonding between PEEK and self-adhesive resin cements. Plasma treatment has no impact on bond to resin cements. CLINICAL SIGNIFICANCE: PEEK reconstructions can be cemented using self-adhesive resin cements combined with pretreatment with MMA-based adhesives.

Glutamyl-transfer RNA: a precursor of heme and chlorophyll biosynthesis.

In green plants, archaebacteria and many eubacteria, the porphyrin ring that is common to both chlorophyll and heme is synthesized from 5-aminolevulinic acid (ALA) via an interesting pathway. This two-step process involves the unusual enzymes glutamyl-tRNA reductase and glutamate-1-semialdehyde 2,1-aminomutase. Interest in this pathway has increased since it was discovered that a tRNA cofactor was required for the formation of ALA. This tRNA(Glu) is common to the biosyntheses of both porphyrins and proteins.

Chemical-vapor deposited ultra-fast diamond detectors for temporal measurements of ion bunches.

This article reports on the development of thin diamond detectors and their characterization for their application in temporal profile measurements of subnanosecond ion bunches. Two types of diamonds were used: a 20 µm thin polycrystalline chemical vapor deposited (CVD) diamond and a membrane with a thickness of (5 ± 1) µm etched out of a single crystal (sc) CVD diamond. The combination of a small detector electrode and an impedance matched signal outlet leads to excellent time response properties with a signal pulse resolution (FWHM) of τ = (113 ± 11) ps. Such a fast diamond detector is a perfect device for the time of flight measurements of MeV ions with bunch durations in the subnanosecond regime. The scCVD diamond membrane detector was successfully implemented within the framework of the laser ion generation handling and transport project, in which ion beams are accelerated via a laser-driven source and shaped with conventional accelerator technology. The detector was used to measure subnanosecond proton bunches with an intensity of 108 protons per bunch.

Experimental discrimination of ion stopping models near the Bragg peak in highly ionized matter.

The energy deposition of ions in dense plasmas is a key process in inertial confinement fusion that determines the α-particle heating expected to trigger a burn wave in the hydrogen pellet and resulting in high thermonuclear gain. However, measurements of ion stopping in plasmas are scarce and mostly restricted to high ion velocities where theory agrees with the data. Here, we report experimental data at low projectile velocities near the Bragg peak, where the stopping force reaches its maximum. This parameter range features the largest theoretical uncertainties and conclusive data are missing until today. The precision of our measurements, combined with a reliable knowledge of the plasma parameters, allows to disprove several standard models for the stopping power for beam velocities typically encountered in inertial fusion. On the other hand, our data support theories that include a detailed treatment of strong ion-electron collisions.

Transcription complexes for various class III genes differ in parameters of formation and stability towards salt.

RNA polymerase III faithfully transcribes the genes for ribosomal 5 S RNA, tRNA(1Met) or adenovirus VA RNA in vitro in the presence of required transcription factors. These genes display distinct differences in the kinetics of transcription complex formation and in their response to excess template. In contrast to tRNA and VA RNA synthesis, 5 S RNA synthesis displays a lag phase of 15 minutes before the onset of transcription and is clearly inhibited by high concentrations of template. Once formed, transcription complexes for the RNA polymerase III genes listed can be isolated by glycerol gradient centrifugation and display a remarkable stability against transient treatment with high salt concentrations. Complexes for 5 S RNA and tRNA remain functionally active up to 2.5 M-KCl. The activity of transcription complexes for VA RNA, however, is significantly diminished after treatment with high salt concentrations. This effect is shown to be due to an irreversible loss of transcription factors. RNA polymerase III is dissociated by high salt concentrations from all the transcription complexes studied but remains part of these complexes during the normal reinitiation cycle at 60 mM-KCl. An additional method for the purification of partial transcription complexes was developed that involves equilibrium centrifugation on cesium sulfate gradients. This method completely releases TFIIIB from 5 S complexes and a core complex, composed of the 5 S RNA gene, factors IIIA and IIIC, is retained. In the case of tRNA and VA RNA, core complexes are obtained that remain partly associated with TFIIIC and TFIIIB. These results indicate a qualitatively and/or quantitatively different interaction of individual factors in different polymerase III transcription complexes.

High resolution crystal structure of a Mg2+-dependent porphobilinogen synthase.

Common to the biosynthesis of all known tetrapyrroles is the condensation of two molecules of 5-aminolevulinic acid to the pyrrole porphobilinogen catalyzed by the enzyme porphobilinogen synthase (PBGS). Two major classes of PBGS are known. Zn2+-dependent PBGSs are found in mammals, yeast and some bacteria including Escherichia coli, while Mg2+-dependent PBGSs are present mainly in plants and other bacteria. The crystal structure of the Mg2+-dependent PBGS from the human pathogen Pseudomonas aeruginosa in complex with the competitive inhibitor levulinic acid (LA) solved at 1.67 A resolution shows a homooctameric enzyme that consists of four asymmetric dimers. The monomers in each dimer differ from each other by having a "closed" and an "open" active site pocket. In the closed subunit, the active site is completely shielded from solvent by a well-defined lid that is partially disordered in the open subunit. A single molecule of LA binds to a mainly hydrophobic pocket in each monomer where it is covalently attached via a Schiff base to an active site lysine residue. Whereas no metal ions are found in the active site of both monomers, a single well-defined and highly hydrated Mg2+is present only in the closed form about 14 A away from the Schiff base forming nitrogen atom of the active site lysine. We conclude that the observed differences in the active sites of both monomers might be induced by Mg2+-binding to this remote site and propose a structure-based mechanism for this allosteric Mg2+in rate enhancement.

Selecting silicone tubing for device applications.

A number of factors are involved in selecting the most suitable silicone tubing for a given purpose. These include physical chemistry, performance properties, a supplier's quality system and regulatory compliance. This article provides a guide for device developers when selecting silicone tubing for their applications.

Complete synthesis and transcription in vitro of a gene coding for human ribosomal 5S RNA.

The gene coding for the major human ribosomal 5S RNA was chemically synthesized and cloned into a pUC13 vector. This approach was taken, because attempts to isolate the human 5S gene have thus far yielded either pseudogenes or variant 5S genes of unknown function. The synthetic human gene was transcribed by RNA polymerase III either in a crude HeLa cell extract or in a system reconstituted from partially purified transcription factors. Comparative studies with the Xenopus laevis somatic 5S gene show that the human gene is transcribed with similar fidelity and an efficiency of about 80% under optimal conditions. The time-course of transcription and optimal concentrations of template and transcription factors were found to be similar for both genes studied. The synthetic gene described may prove useful to study its interaction with human transcription factors in a homologous system.

Complex formation between glutamyl-tRNA synthetase and glutamyl-tRNA reductase during the tRNA-dependent synthesis of 5-aminolevulinic acid in Chlamydomonas reinhardtii.

The formation of a stable complex between glutamyl-tRNA synthetase and the first enzyme of chlorophyll biosynthesis glutamyl-tRNA reductase was investigated in the green alga Chlamydomonas reinhardtii. Apparently homogenous enzymes, purified after previously established purification protocols were incubated in various combinations with ATP, glutamate, tRNA(Glu) and NADPH and formed complexes were isolated via glycerol gradient centrifugation. Stable complexes were detected only after the preincubation of glutamyl-tRNA synthetase, glutamyl-tRNA reductase with either glutamyl-tRNA or free tRNA(Glu), ATP and glutamate, indicating the obligatory requirement of aminoacylated tRNA(Glu) for complex formation. The further addition of NADPH resulting in the reduction of the tRNA-bound glutamate to glutamate 1-semialdehyde led to the dissociation of the complex. Once complexed to the two enzymes tRNA(Glu) was found to be partially protected from ribonuclease digestion. Escherichia coli, Bacillus subtilis and Synechocystis 6803 tRNA(Glu) were efficiently incorporated into the protein-RNA complex. The detected complexes provide the chloroplast with a potential channeling mechanism for Glu-tRNA(Glu) into chlorophyll synthesis in order to compete with the chloroplastic protein synthesis machinery.

Transposon Tn5 mutagenesis of pseudomonas fluorescens to isolate mutants deficient in antibacterial activity.

Pseudomonas fluorescens was subjected to insertion mutagenesis studies using the transposon Tn5-GM to generate mutants deficient in antibacterial activity minus mutants. The transposon located on the temperature-sensitive plasmid pCHR84 was conjugally transferred into the non-pathogenic pseudomonad using the triparental mating procedure. Random integration of Tn5-GM into the chromosome of P. fluorescens was achieved by heat treatment of the transformed cells at 42 degrees C. Approximately 2% of transconjugants revealed an auxotrophic phenotype indicating efficient integration of the employed transposon into the chromosome of P. fluorescens. One transposon insertion mutant was obtained showing an antibacterial activity minus phenotype. This mutant (MM-7) was found to be defective in the production of an unidentified antibacterial compound against B. subtilis. These results introduce Tn5 transposon mutagenesis as a new useful tool for the molecular analysis of P. fluorescens.

The anaerobic life of Bacillus subtilis: cloning of the genes encoding the respiratory nitrate reductase system.

The Gram-positive soil bacterium Bacillus subtilis, generally regarded as an aerobe, grows under strict anaerobic conditions using nitrate as an electron acceptor and should be designated as a facultative anaerobe. Growth experiments demonstrated a lag phase of 24 to 36 hours after the shift from aerobic, to the onset of anaerobic respiratory growth. Anaerobically adapted cells grew without further lag phase after their transfer to fresh anaerobic growth medium. The cells change their morphology from rods to longer filament-like structures when moved from aerobic to anaerobic respiratory growth conditions. Surprisingly, anaerobically grown B. subtilis lost the capacity for sporulation. An investigation of the molecular basis of the switch between aerobic and anaerobic growth was initiated by the cloning of the genes encoding the respiratory nitrate reductase from B. subtilis. Oligonucleotides deduced from conserved amino acid sequence regions of eubacterial respiratory nitrate reductases and related enzymes were used for the isolation of the genes. Four open reading frames with significant homology to the E. coli respiratory nitrate reductase operons (narGHIJ, narZYWV) were isolated and termed narGHJI. A chromosomal knock-out mutation of the B. subtilis nar operon totally abolished nitrate respiration.

Vacuum-assisted suction drainage versus conventional treatment in the management of poststernotomy osteomyelitis.

OBJECTIVE: The purpose of our study was to compare vacuum-assisted suction drainage (VASD) to conventional wound management, in the treatment of poststernotomy osteomyelitis (SOM). METHODS: We included a total of 42 patients that developed poststernotomy osteomyelitis and required open wound management, between 1998 and 2000, in this study. Twenty of these patients were treated by VASD and the other 22 by conventional wound management. The patients were well comparable with regards to age, presenting postoperative day, infecting organism and risk factors for osteomyelitis. This was a retrospective study. RESULTS: The patients treated by VASD had a significantly reduced treatment duration (mean 17.2+/-5.8 vs. 22.9+/-10.8 days, P=0.009) and total hospital stay (mean 27.2+/-6.5 vs. 33.0+/-11.0 days, P=0.03). Perioperative mortality was similar, with one early death in each group. CONCLUSION: We conclude from our experience in the treatment of 42 patients with poststernotomy osteomyelitis that VASD shortened wound healing and hospital stay and thus proved to be an excellent alternative to conventional open management of these wounds.

[Laser-induced thermotherapy (LITT) of lung metastases: description of a miniaturized applicator, optimization, and initial treatment of patients]. / Laser-induzierte Thermotherapie (LITT) von Lungenmetastasen: Beschreibung eines miniaturisierten Applikators, Optimierung und erste Patientenbehandlungen.

PURPOSE: A thin-caliber applicator system was developed for introducing a laser fiber under CT guidance into lung metastases with only minimal complications. MATERIALS AND METHODS: A space-saving 5.5 French Teflon cannula with a titanium trocar and connectors for a laser light guide (2 or 3 cm Dornier Diffusor-Tip H-6111-T2 or H-6111-T3 coupled to a Dornier Medilas Fibertom 5100 laser, wavelength of 1064 nm) and a perfusion line for physiologic saline solution were developed. After puncture the laser Diffusor-Tip remains in the cannula and is cooled during its tissue passage by slowly flowing saline solution. The miniaturized applicator system (Monocath) was calibrated in nonperfused bovine liver for maximum energy supply and necessary flow of the cooling saline solution in reference to a commercially available 9 French laser catheter with an 11.5 French inducer sheath (Power-Applicator). The new applicator system was used for treating lung metastases in 10 patients over a period of 21 months. RESULTS: The size of heat coagulation in bovine liver was 24 +/- 2 ml using the miniaturized system with application of 15 W for 20 min and a saline flow of 0.75 ml/min, in comparison to a size of 29 +/- 7 ml for the commercial applicator (30 W, 20 min, 60 ml/min). All metastases could be safely approached with the miniaturized applicator, except for two metastatic lesions at the lung base in two patients. A minor pneumothorax developed in three patients and intrapulmonary bleeding in two. Contrast-enhanced CT demonstrated necrosis of the treated metastatic areas in 6 patients. Follow-up of three patients after 5, 6, and 8 months showed complete tumor regression with minimal scarring in one patient. CONCLUSION: The miniaturized applicator system enables the introduction of a laser fiber into pulmonary metastases with only minor complications. Complete ablation seems to be achievable in suitable patients with the applied laser energy and a slow cooling fluid flow rate.

Neonatal respiratory distress syndrome in the calf.

Thirty-five calves were delivered by caesarean section near to term. During the operation amniotic fluid was collected for determination of the lecithin/sphingomyelin (L/S) ratio. Clinical examination of the calves and analysis of blood gas concentration (venous blood) were carried out within the first hour of life. Fifteen out of 35 calves under examination did not show clinical or blood gas disorders in the course of the first hour of life. In these calves, the L/S ratio, which represents a measure for the maturity of the surfactant system, averaged 2.6. The other 20 calves, however, developed a respiratory distress syndrome together with a progressive respiratory and metabolic acidosis within the first hour of life. The L/S ratio in the animals affected with respiratory distress syndrome reached an average value of 1.5 which was significantly below that of the calves not suffering from respiratory distress. Eleven of the 20 calves which developed respiratory distress syndrome died within the first 60 hours of life. The most striking findings in the post mortem examinations of these animals were intracranial haemorrhages and pulmonary lesions (hyaline membranes, interstitial and alveolar oedema). On the basis of the significantly lower L/S ratio and the post mortem findings, it is to be assumed that the respiratory distress syndrome in calves, equally with that in infants, is attributable to a surfactant deficiency.

[An Experiment to calculate the theoretical temperature at the drill-cortical bone interface]. / Ein Versuch zur theoretischen Temperaturermittlung im Schneidbereich bei Bohrungen in kortikalem Knochen.

To date, analysis of temperature in the drill area of cortical bone have been limited to measurements with thermocouple systems at a certain distance from the drill hole. Many authors equate this temperature measurement with the drill--cortical bone interface temperature. In order show that there is a temperature difference, a drill hole was simulated with the aid of the "Finite Element Method". The interface temperature was calculated by the energy distribution. It was shown, that for "dry" and "watercooled" drilling, the drill hole temperature was 13 degrees C higher than the temperature measured with the thermocouple systems at a distance 0.5 mm of from the drill hole. In particular when using "watercooled" drills for bone and dental surgery, the temperature may be higher than the bone damage limit of 44 degrees C for lengthy and 50 degrees C for brief drilling.

Financing health services for children in Texas.

In Texas, children's health services are financed by a bewildering combination of private and public sources, each of which employs different eligibility rules, benefit packages, and reimbursement methods. This article describes these financing mechanisms, underscoring their complexity and the need for consolidation and reform. As private coverage for children has declined, it has become less comprehensive with increased coinsurance and deductibles. Concurrently, due to a number of federal initiatives, Medicaid coverage has increased rapidly with new benefits, also now mandated. Levels and structure of payment have influenced variable participation in the program by physicians, rural health clinics, federally qualified health centers, and children's hospitals. The Texas Department of Health and the Texas Department of Mental Health and Mental Retardation have undertaken a number of initiatives to fill in the gaps and to serve mandated categorically eligible populations. Continuity of care is difficult to achieve. Comprehensive community-based care should be promoted with the goal of expanding the role of all types of providers.

Microbiota and epigenetic regulation of inflammatory mediators in type 2 diabetes and obesity.

Metabolic syndrome is associated with alterations in the structure of the gut microbiota leading to low-grade inflammatory responses. An increased penetration of the impaired gut membrane by bacterial components is believed to induce this inflammation, possibly involving epigenetic alteration of inflammatory molecules such as Toll-like receptors (TLRs). We evaluated changes of the gut microbiota and epigenetic DNA methylation of TLR2 and TLR4 in three groups of subjects: type 2 diabetics under glucagon-like peptide-1 agonist therapy, obese individuals without established insulin resistance, and a lean control group. Clostridium cluster IV, Clostridium cluster XIVa, lactic acid bacteria, Faecalibacterium prausnitzii and Bacteroidetes abundances were analysed by PCR and 454 high-throughput sequencing. The epigenetic methylation in the regulatory region of TLR4 and TLR2 was analysed using bisulfite conversion and pyrosequencing. We observed a significantly higher ratio of Firmicutes/ Bacteroidetes in type 2 diabetics compared to lean controls and obese. Major differences were shown in lactic acid bacteria, with the highest abundance in type 2 diabetics, followed by obese and lean participants. In comparison, F. prausnitzii was least abundant in type 2 diabetics, and most abundant in lean controls. Methylation analysis of four CpGs in the first exon of TLR4 showed significantly lower methylation in obese individuals, but no significant difference between type 2 diabetics and lean controls. Methylation of seven CpGs in the promoter region of TLR2 was significantly lower in type 2 diabetics compared to obese subjects and lean controls. The methylation levels of both TLRs were significantly correlated with body mass index. Our data suggest that changes in gut microbiota and thus cell wall components are involved in the epigenetic regulation of inflammatory reactions. An improved diet targeted to induce gut microbial balance and in the following even epigenetic changes of pro-inflammatory genes may be effective in the prevention of metabolic syndrome.

Optimization of antibody fragment production in Bacillus megaterium: the role of metal ions on protein secretion.

The effect of the concentration of metal ions in minimal media has been shown to be very important for the production and secretion of the antibody fragment D1.3 scFv in Bacillus megaterium YYBm1. The best media compositions for biomass and antibody fragment formation were evaluated using a genetic algorithm. The screening was carried out in 96 microtiter deep well plates with 900 µL cultivation volume. In 7 generations, 240 different kinds of media were tested, key elements for production and secretion were detected and a 117% increase in production of antibody fragment compared to the previously used medium could be achieved. In addition, media with a higher biomass formation (+84%) or with both more biomass and a higher production of antibody fragment (Pareto-front members) were found. Interestingly the best media for protein production and secretion were different in their composition, with regards to the metal ion concentration levels. From data derived experimentally and from the genome, magnesium was shown to be one of the key components of the metal ions tested for biomass formation and especially for production and secretion of the antibody fragment D1.3 scFv.