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Background: Communities are wellness landscapes of geospatially and temporally bound settings where children spend their time. Improving population physical activity (PA) requires investigating available community settings for children, such as classrooms and sport teams, and the dynamic social interactions producing PA. This protocol describes a multiscale community wellness landscape monitoring and feedback system of adult-led organized group settings and PA outcomes for children. Methods: The data system assessed organized groups for third- through sixth-grade children in 2 rural communities within seasons (fall 2018–2019). Within each season, groups were identified, sampled, and recruited. Sampled group meetings were assessed for children’s PA (accelerometry) and meeting routines (video observation). A data processing protocol time-segmented data into meetings and meeting routines into smaller units (sessions). A purpose code was assigned to each meeting (eg, classroom, sport) and session (eg, academic, PA). Group accelerometer data were paired with the coded segments. Multiscale metrics (season, meeting, and session) were generated and provided to the communities in tailored reports. Results: A total of 94 groups were recruited, and 73 groups with 1302 participants were included in the data system. Data were collected from 213 meetings and 844 sessions. Most participants (83.1%) consented to link their accelerometer data with demographic data from school enrollment records. Conclusions: The community data system identified available organized group settings for children and collected video and PA data from these settings. Incorporating setting data into local data systems provides detailed accounts of whole-of-community PA social systems to inform population health improvement efforts.

Background Out-of-school time (OST) organized group youth activities (e.g., afterschool programs, clubs) can reduce health inequalities by increasing physical activity (PA). However, unlike youth sport, PA is not the primary focus of many organized activities. This study examined the association between rural children’s demographic factors and OST non-sport organized activity participation and the differences between these factors and PA. Methods During Spring 2019, children (n = 418 3rd − 6th graders, aged 8–12 years) enrolled in two rural Midwestern public schools in the United States completed the Youth Activity Profile (YAP) and supplemental National Survey of Children’s Health 2017–2018 survey questions assessing OST organized activity participation as part of the Wellscapes Project, a type 3 hybrid implementation-effectiveness community randomized trial. A subsample of 235 children (males, n = 117; females, n = 118) provided parental/guardian consent to pair YAP results with student enrollment records. Average OST moderate-to-vigorous PA (MVPA) per weekday and weekend days was estimated using an algorithm converting raw YAP scores into minutes of MVPA. Mixed models with community as a random effect examined main effects and interactions of grade, sex, and family income on OST non-sport organized activity participation and these factors and participation on MVPA. Results Most children (73.2%) participated in an OST non-sport organized activity. Males were less likely to participate in organized activities than females (OR = 0.38, 95% CI = 0.20–0.73, p = 0.004). Females and 6th graders reported lower OST MVPA on weekdays and weekends than comparison groups (p diff = -4.7 ± 2.0 minutes) and weekends (meandiff = -8.9 ± 3.8 minutes) compared with males with higher family income (p ). Conclusions Many rural children participated in OST organized activities regardless of grade and family income. However, there were inequalities in organized activity participation and OST weekday and weekend MVPA by demographic factors, including grade, sex, and family income. Designing OST organized activity settings to include PA may aid in reducing PA inequalities and promoting health equity.

ObjectivesTo examine differences in rural community children’s moderate-to-vigorous physical activity (MVPA) and participation in out-of-school activities from fall 2019 to fall 2020 and explore enacted PA opportunity modifications post initial COVID-19 disruption.DesignMixed methods study using the validated Youth Activity Profile (YAP), administrator reports and stakeholder surveys and semistructured interviews.SettingChildren and community stakeholders from one rural US Great Plains community in the state of Nebraska were recruited.ParticipantsThird through fifth graders in fall 2019 (n=144) and fall 2020 (n=174) reported MVPA and participation in out-of-school activities using the YAP. School administrators reported weekly physical education (PE) and recess minutes. Community stakeholders reported pandemic-related changes in community social structures in semistructured interviews (n=4) and surveys (n=19).ResultsAverage daily MVPA minutes increased from 2019 to 2020 (75.0 vs 81.3, SE=1.6, pConclusionsIncreased minutes of PE and recess, and decreased out-of-school activity participation may have increased children’s overall free play and MVPA during the pandemic. Free play was an important contributor to children’s PA during the pandemic and should be prioritised by educators, coaches and other leaders of child PA opportunities.Trial registration numberNCT03380143.

Background Physical activity, a high-frequency health behavior, varies by where children live, learn, and play. Children accumulate physical activity in adult-led in-school and out-of-school settings. Youth sport is a potential setting for physical activity, but there are differences in youth sport participation based on age, sex, and socioeconomic status. There is a gap in understanding demographic influences on youth sport participation and how these factors interact to influence physical activity. This study examines influences of grade, sex, and family income on youth sport participation and these factors and youth sport participation on moderate-to-vigorous physical activity of children in rural communities. Methods Children (n = 418 3rd–6th graders) living in two rural communities completed the online Youth Activity Profile as part of Wellscapes, a type 3 hybrid implementation-effectiveness community randomized trial. Mixed models with community as a random effect examined main effects and interactions of grade, sex, and family income on youth sport participation and these factors and youth sport participation on moderate-to-vigorous physical activity. Results About 80% of children engaged in youth sport, and full-pay lunch students were almost four times more likely to have youth sport participation than students with free/reduced lunch (OR = 3.91, 95% CI = 1.95, 7.8). Females and 6th graders (p p Conclusions While a fairly high percentage of children participate in youth sports, there are disparities in rural communities on youth sport participation and physical activity outcomes based on age, sex, and family income.

BackgroundPhysical activity, a high-frequency health behavior, varies by where youth live, learn, and play. Youth accumulate physical activity in adult-led in-school and out-of-school settings. Youth sport is a potential setting for physical activity, but there are differences in youth sport participation based on age, gender, and socioeconomic status. There is a gap in understanding demographic influences on youth sport participation and how these factors interact to influence physical activity. This case study examines influences of grade, gender, and family income on youth sport participation and these factors and youth sport participation on moderate-to-vigorous physical activity of youth in rural communities.MethodsYouth (n=418 3rd–6th graders) living in two rural communities completed the online Youth Activity Profile as part of Wellscapes, a type 3 hybrid implementation-effectiveness community randomized trial. Mixed models with community as a random effect examined main effects and interactions of grade, gender, and family income on youth sport participation and these factors and youth sport participation on moderate-to-vigorous physical activity. ResultsAbout 80% of youth engaged in youth sport, and full pay lunch students were almost four times more likely to have youth sport participation than students with free/reduced lunch (OR = 3.91, 95% CI = 1.95, 7.8). Females and 6th graders (p th graders, high family income had less effect on physical activity than similar 3rd-5th graders (p

The potential efficacy of gene delivery is dictated by the infectivity profile of existing vectors, which is often restrictive. In order to target cells and organs for which no efficient vector is currently available, a promising approach would be to engineer vectors with novel transduction profiles. Applications that involve injecting adenovirus (Ad) vectors into the bloodstream require that native tropism for the liver be removed, and that targeting moieties be engineered into the capsid. We previously reported that pseudotyping the Ad serotype 5 fiber for that of Ad19p results in reduced hepatic transduction. In this study we show that this may be caused, at least in part, by a reduction in the capacity of the Ad19p-based virus to bind blood coagulation factors. It is therefore a potential candidate for vector retargeting, focusing on the kidney as a therapeutic target. We used in vivo phage display in rats, and identified peptides HTTHREP and HITSLLS that homed to the kidneys following intravenous injection. We engineered the HI loop of Ad19p to accommodate peptide insertions and clones. Intravenous delivery of each peptide-modified virus resulted in selective renal targeting, with HTTHREP and HITSLLS-targeted viruses selectively transducing tubular epithelium and glomeruli, respectively. Our study has important implications for the use of genetic engineering of Ad fibers to produce targeted gene delivery vectors.

Expression of antigens in dendritic cells (DC) can stimulate protective immunity against both viral infection and tumor growth, making them important targets for gene therapy. In-vitro-generated DC are commonly used in gene delivery studies with the assumption that the results will correlate with in vivo activity. Adenovirus Type 5 (Ad5) vectors have been widely used with DC, but these cells lack the primary receptor (CAR) used by Ad5 and are poorly infected. We investigated the use of Ad5 vector particles pseudotyped with fibers from other Ad serotypes in DC targeting. Several fiber proteins, including those from Ad16 (Subgroup B) and Ad37 (Subgroup D), conferred dramatically increased in vitro infection. Surprisingly, neither dendritic cell infection nor the immune response to an Ad-delivered antigen was improved when the modified viruses were tested in vivo. These results underscore the importance of using appropriate animal models in gene delivery studies.

Adenovirus (Ad5) serotype 5 vectors are commonly used for gene transfer. Preclinical studies have shown that their application to systemic gene delivery, however, is limited by their highly efficient uptake in the liver, principally mediated by receptor-binding sites on the fiber shaft and knob domain. Using Ad to target other sites in vivo requires vectors that lack hepatic tropism. We therefore sought to exploit Ad family diversity to isolate vectors that possessed poor hepatic tropism. We pseudotyped the fibers from Ad16 (subgroup B; Ad5/16), Ad19p (subgroup D; Ad5/19p), and Ad37 (subgroup D; Ad5/37) onto Ad5 capsids and assessed infectivity profiles in vitro in multiple cell types and in vivo in rats. In rat, mouse, and human hepatocytes, Ad5/19p and Ad5/37 both possessed a striking lack of hepatic cell infectivity compared with Ad5. Both vectors were, however, able to transduce human vascular endothelial and smooth muscle cells with efficiencies equal to or greater than that of nonmodified Ad5. We evaluated liver uptake in 12-week-old male rats after intravenous injection. In contrast to a vector with the wild-type Ad5 fiber, Ad5, both Ad5/19p and Ad5/37 produced significantly less virion accumulation (measured at 1 hr and 5 days) and transgene expression in the liver. Thus, Ad5/19p and Ad5/37 may be useful platforms for the development of targeted Ad vectors.

The vascular smooth muscle cell (SMC) is integral to the pathogenesis of neointimal formation associated with late vein graft failure, in-stent restenosis, and transplant arteriopathy. Viral vectors transduce SMC with low efficiency and hence, there is a need for improvement. We aimed to enhance the efficiency and selectivity of gene delivery to human SMC. Targeting ligands were identified using phage display on primary human saphenous vein SMC with linear and cyclic libraries. Two linear peptides, EYHHYNK (EYH) and GETRAPL (GET), were incorporated into the HI loop of adenovirus (Ad) fibers and the capsid protein of adeno-associated virus-2 (AAV-2). Exposure of human venous SMC to EYH-modified (but not the GET-modified) Ad vector resulted in a significant increase in transgene expression levels at short, clinically relevant exposure times. Similarly, the EYH-modified AAV vector resulted in enhanced gene transfer to human venous SMC but not endothelial cells in a time- and dose-dependent manner. The EYH-modified AAV vector also enhanced (up to 70-fold) gene delivery to primary human arterial SMC. Hence, incorporation of EYH into Ad and AAV capsids resulted in a significant and selective enhancement in transduction of SMC and has implications for improving local gene delivery to the vasculature.

Carbon sources and the sinks have been quantified in TEXTOR and are discussed in terms of short and long range transport. The major source (22 g/h) is the graphite belt limiter, but part (10 g/h) of the carbon is directly re-deposited after short range transport. Long range transport causes flake formation on obstacles and neutralisers, but little and deuterium rich (D/C≈0.7) deposition in remote areas. The rest is leaving via the pumps in gaseous form. This behaviour is different from that in JET where large amounts of deuterium rich deposits were found in the louvers. Tungsten is favoured for the ITER divertors because of its low sputtering yield for hydrogen, but melting and erosion by carbon may be an additional concern. The short range transport of tungsten has been investigated in a well defined experiment and quantitatively re-constructed by means of the ERO-TEXTOR code. Code validation is necessary in order to increase the confidence and the applicability to JET and ITER.

Long term erosion/deposition at the plasma facing surfaces as well as the carbon transport to the remote areas are discussed. The erosion of the liner wall and the deposition at the inner walls of the pump ducts were quantified. A small net deposition of carbon was found also at the liner, but only in the vicinity of the toroidal belt limiter. A deposition of polymer like deuterium rich carbon films (D/C ≈ 0.7) took place in remote areas. Despite the minute deposition rate of ∼0.02 gC/h these deposits might be decisive in view of tritium retention in next step fusion devices.

Strategies for retargeting adenoviral (Ad) vectors have been developed, but their in vivo efficacy remains to be demonstrated. Gene delivery to specific ocular cell types represents an approach to treating many diseases that cause irreversible blindness. One of these cell types, the photoreceptor (PR), is not infected by standard Ad5-based vectors. We evaluated gene delivery after intraocular injection of Ads pseudotyped with three different fiber proteins and found three distinct patterns of infection. An intravitreally injected Ad5 vector readily infected the iris, corneal endothelium, and ciliary body, while few cells in the retina expressed transgene product. In contrast, an Ad3-pseudotyped virus selectively transduced ciliary body, of interest for treating diseases such as glaucoma. A vector pseudotyped with the fiber protein of Ad37 transduced PRs as well as ciliary body. This finding has potential application to the treatment of retinal degenerative or neovascular diseases. These studies demonstrate cell type-selective gene delivery in vivo with retargeted Ads, provide information about the cellular tropisms of several Ad serotypes, and should lead to improved strategies for preserving vision.

Ta--W twin limiter experiments had been carried out in TEXTOR-94. D β and D γ intensities were observed during discharges. As a result, the intensities from the Ta surface were less than those from the W surface. This is attributed to the release ratio of molecules and atoms from the surface, i.e. less atomic release and more molecular release from Ta. Concerning long term D retention in Ta, D distributed uniformly over the limiter and the content was about 4 × 10 5 D per Ta atom. The total amount in the Ta limiter was estimated 3 × 10 20 D in the half limiter. After exposure, the Ta bulk showed a significantly modified surface: grain growth, wrinkle like deformations and local recrystallization. However, open cracks were not observed in Ta exposed in the same condition in which W created big open crack.

Adenovirus (Ad) entry into cells is initiated by the binding of the fiber knob to a cell surface receptor. The coxsackie- and adenovirus receptor (CAR) functions as the attachment receptor for many, but not all, Ad serotypes. Ad type 37 (Ad37), a subgroup D virus that causes keratoconjunctivitis in humans, does not infect cells via CAR despite demonstrated binding of the Ad37 knob to CAR. We have pseudotyped a fiber deletion Ad5 vector with the Ad37 fiber (Ad37f), and this vector retains the ocular tropism of Ad37. Here we present a cryo-electron microscopy reconstruction of Ad37f that shows the entire Ad37 fiber, including the shaft and knob domains. We have previously proposed that Ad37 may not utilize CAR for cell entry because of the geometric constraints imposed by a rigid fiber (E. Wu, J. Fernandez, S. K. Fleck, D. Von Seggern, S. Huang, and G. R. Nemerow, Virology 279:78–89, 2001). Consistent with this hypothesis, our structural results show that the Ad37 fiber is straight and rigid. Modeling of the interaction between Ad37f and host cell receptors indicates that fiber flexibility or rigidity, as well as length, can affect receptor usage and cellular tropism.

Two different sets of long term samples (LTS) were exposed in TEXTOR-94 at the liner with boronized and siliconized wall conditions. Measured erosion/deposition rates of the coating constituents were compared with sputtering rates calculated for pure elements. D0-fluxes at the LTS locations were determined by the B2-EIRENE code. Over the whole liner, erosion of initial coatings by D0 is observed. Boron erodes at a rate of 8.4×10 13 B cm −2 s −1 , while silicon erodes at a rate of 5.6×10 13 Si cm −2 s −1 , a factor of 1.5 lower than that of boron. With boronized walls, carbon atoms initially present in the a-C/B:D layers are eroded at a rate of 7.6×10 12 C cm −2 s −1 , at the same time 1.7×1012 (Fe + Cr + Ni) cm −2 s −1 are deposited. Compared to boronized conditions where carbon erodes, deposition of carbon (1.7×10 13 cm −2 s −1 ) and of metals (3.8×10 12 cm −2 s −1 ) occurred during the Si campaign. Due to long time exposure at high wall temperature (350°C), hydrogenic isotopes desorb; (D + H)/(B + C) and (D + H)/(Si + C) ratios degrade from originally ∼0.4 to ∼0.2.

Hydrogen retention in tokamaks is due to implantation into plasma-facing materials and trapping in deposited layers. In the limiter tokamak TEXTOR-94 hydrogen-rich deposited layers with thicknesses up to 1 mm are observed on recessed parts of the limiters, areas perpendicular to the magnetic field in the scrape-off layer (SOL), neutralizer plates of the pumped limiter and inside the pumping ducts. In the divertor tokamak JET the main deposition is observed in the divertor, additional deposits are observed in the main chamber on the sides of the guard limiters. Codeposition of carbon ions with hydrogen is the major mechanism of layer growth at areas with direct plasma contact. At remote areas without direct plasma contact, sticking of neutral hydrocarbon radicals seems to play an important role for hydrogen trapping.

Siliconisation has been performed for a long period of operation as the routine wall coating procedure of TEXTOR-94. The general aim was to study the behaviour of TEXTOR-94 with a medium-Z plasma-facing material and to compare it with that under freshly boronised as well as `carbon dominated' conditions. This contribution focuses on the characteristics of Si-impurity release from the limiters, and the influence of the Si coating on the release of carbon and oxygen impurities with special emphasis on material mixing effects on the plasma-exposed surfaces.

Impurity production, hydrogen recycling and power deposition on carbon and tungsten limiters have been investigated in TEXTOR-94 using a C–W twin test limiter. Considerable differences have been observed on W and C surfaces, which can be explained by the different particle and energy reflection coefficients of hydrogen on these surfaces. The measurements show in addition that the majority of the carbon release is from recycled carbon and that only a small part (below 10%) is due to net-erosion from the bulk carbon material. The heat deposition on C and W sides differs under the same plasma conditions significantly and is typically about 30% larger on the carbon surface. The behaviour of the impurity production, recycling and power deposition for various discharge conditions is presented.

In order to investigate the impurity release and surface modification on a W/C twin test limiter, made of a half of W and the other half of C, exposed to the edge plasma of TEXTOR-94, simulation calculations of ion-surface interaction are conducted by a Monte Carlo code. According to the calculations, experimentally observed spatial distributions of WI and CII line intensities around the W side of the limiter can be explained by physical sputtering of W, reflection of bombarding C ions and physical sputtering of implanted C. The CII line emission, resulting from thermal C atoms, around the C side of the limiter is suppressed by deposition of W, and the reflection of C ions from W deposited on C causes the CII intensity to decay more slowly than that from C without the deposition. Bombardment with deuterium edge plasmas, containing impurity W, produces a thick W layer on the C side of the limiter, whereas C implanted in the W side is strongly sputtered due to impact of most constituent D ions.

Graphite-tungsten twin limiters have been used at the TEXTOR tokamak for testing of high-Z metals as plasma facing materials and, in particular, for studies of the local and global transport of tungsten. The emphasis was on the change in surface morphology of limiters: the formation and properties of multicomponent co-deposits and the trapping characteristics of fuel on carbon and high-Z substrates exposed to the plasma under various operation conditions, i.e., heating scenarios, configuration of limiters, etc. Vast quantities of tungsten have been found to be locally transported to the adjacent graphite surfaces. Ion beam analysis also indicated strong intermixing of carbon, tungsten and boron on the hottest parts of the limiters. The results are discussed in terms of various mechanisms involving the transport of tungsten-containing species, possibilities of oxide production and formation of mixed (W-C-B) compounds.

Three different types of W limiters were exposed in the TEXTOR plasma and the response of the plasma and materials performance of the limiters were investigated. 1. A W bulk limiter operated with preheating above 800 K withstood a plasma heat load of about ∼20 MW/m 2 for a few seconds with some slight surface melting during the highest heat load shot. However, it was severely damaged when operated at around 500 K. 2. A C/W twin test limiter, half made of bulk W and the other half of graphite (EK-98) gave very useful information on how low- and high-Z materials behave under conditions of simultaneous utilization as PFM such as cross-contamination and the influence of a large mass difference on hydrogen reflection and deposition. 3. Two sets of main poloidal W limiters made of vacuum vapor sprayed (VPS)-W deposited on graphite (IG-430U) with a Re interlayer could absorb about 60% of the total convection heat and the ohmic plasma with a density as high as 5 × 10 13 cm −3 was sustained. Most of the VPS-W coated limiters tolerated a heat load of ∼20 MW/m 2 . This series of W limiters experiments in TEXTOR has shown that W is applicable as a PFM, if its central accumulation is avoided by NBI and/or ICRH heating. Nevertheless, some concerns still remain, including difficulty of plasma start-up, W behavior in higher temperature plasmas, and materials' selection.

In order to investigate the effect of mutual contamination between tungsten (W) and carbon (C) and its influence on the plasma, a W–C twin test limiter, half made of W and the other half of C, was inserted into the edge plasma of TEXTOR-94 under ohmic and NBI heating conditions. The contamination process was observed by spectroscopy, and the intensity distribution of WI showed migration of W onto the C side by the successive cycles of sputtering and prompt redeposition. On the other hand, the deposition of C on the W surface was not obvious. Most of the hydrogen (deuterium) on the limiter was found to be retained in the deposited layers and that in the deposited C layer much higher than that in the deposited W layer. This indicates that tritium retention is smaller in metallic deposits above 500 K. The AES analysis conducted after the exposure of the test limiter showed that W deposited on C reacted with the substrate to form carbides at higher temperatures. The thickness of carbide layer, and/or the content of W in C were influenced by the temperature and flux distributions, and no carbide layer was formed at the limiter edge where the temperature was relatively low.

Current adenoviral (Ad) vectors cannot be targeted to specific cell types due to the widespread distribution of the Ad receptor (CAR). Moreover, CAR and/or internalization receptors (alphav integrins) are absent or present at low levels on some cell types, rendering them resistant to Ad-mediated gene delivery. To address these problems, we have developed a novel vector targeting approach that takes advantage of the common cell signaling pathways initiated by ligation of alphav integrins and growth factor receptors. Recombinant growth factor/cytokines (TNF-alpha, IGF-1, EGF) which trigger phosphatidylinositol-3-OH kinase (PI3K) activation, a signaling molecule involved in adenovirus internalization, were fused to a monoclonal antibody specific for the viral penton base. Ad vectors complexed with these bifunctional mAbs increased gene delivery 10 to 50-fold to human melanoma cells lacking alphav integrins. The bifunctional mAbs also enhanced gene delivery by fiberless adenovirus particles which cannot bind to CAR. Improved gene delivery correlated with increased virus internalization and attachment as well as PI3K activity. The use of bifunctional mAbs to trigger specific cell signaling pathways offers a widely applicable method for bypassing the normal Ad receptors in gene delivery and potentially increasing the selectivity of gene transfer.

Erosion of boron out of a thin film exposed to deuterium edge plasmas and the simultaneous carbon deposition have been investigated in the tokamak TEXTOR-94 and simulated by means of a dynamic Monte Carlo code. The calculated results are compared with some observations (colorimetry, spectroscopy and AES) during and after the exposures. The implantation of carbon impurities strongly changes the effective boron sputtering yield of the film, which results into a lowering of the film erosion and a formation of thick carbon deposits. A strong decrease in the observed BII line emission around a surface location far from the plasma edge can be explained by a carbon deposition on the film. The calculated carbon depth profiles in the film, depending on the distance of the exposed surface from the plasma edge, are in reasonable agreement with measurements by AES after the exposures. Although simultaneous surface erosion and carbon deposition can be simulated, the calculated erosion rate is larger, by a factor of 2, than the observations by colorimetry at the early stage of the exposure.

Deuterium and hydrogen containing co-deposited layers formed on plasma facing components at the TEXTOR tokamak were characterised by a number of techniques including surface analysis methods and thermal desorption spectrometry. The aim of the investigation was to determine the composition and structure of the layers prior and after their exposure to air at elevated temperatures of 300°C and 550°C. The impact of the oxidation on the deuterium content and distribution in the surface region and in the bulk of PFC was addressed. The initial deuterium-to-carbon concentration ratio was in the range 0.04–0.06 in the flaking layers on top of the PFC and up to 0.17 on their side surfaces. The oxidation at 300°C for 2 h resulted in partial removal of the deuterium, especially from thin or loosely bound layers, but the release was not accompanied by the change in the deposit structure. The content of plasma impurity atoms in the layers was also not influenced by the exposure to air. Following the oxidation at 550°C partial powderisation of thick, flaking films was observed.

Ventilation of the TEXTOR torus with oxygen at pressures between 0.007 and 0.3 mbar and at wall temperatures between 500 and 700 K has been investigated to remove redeposited carbon material and to release the incorporated hydrogen. It has been observed that a significant part of the injected oxygen adsorbs on the walls due to formation of stable oxygen compounds. Part of the oxygen reacts with CO and CO 2 . The CO reaction rate is independent of the filling pressure whereas the CO 2 production increases with increasing pressure. Plasma operation after the oxygen baking has been achieved after GDC in D 2 and He (15–30 min). The oxygen impurity content was initially about a factor of 2–3 higher than before but also showed a decreasing behaviour shot by shot.

Gradual erosion of a thin a-B:D layer on a graphite block is observed in TEXTOR-94 during 28 exposures while carbon out of the SOL has been deposited onto the surface simultaneously. The co-existence of B erosion (−0.5 nm/s) and C deposition (+0.8 nm/s) in the same area is due to non-uniform carbon redeposition of typically 10–30 μm in size. The D content is more than doubled in the co-deposit despite the considerable erosion of boron. Erosion by only neutrals could be discriminated from the erosion by D+ ions. The film lost the transparency due to temperature excursions up to 2000 K during NBI. Observations were made during the exposures (colorimetry, spectroscopy) and post-mortem.

Wall conditioning and especially wall coating procedures like boronization or siliconization are indispensable for present day machines. They are also needed for future steady state plasma devices with superconducting coils and permanent magnetic fields like ITER. However, since important standard conditioning techniques like Plasma Chemical Vapor Deposition (PCVD), based on dc-glow discharges, are not compatible with those fields, new techniques have to be developed. This paper reports on first ion cyclotron range of frequency (ICRF)-assisted in situ deposition of a boron and carbon containing layer of relevant thickness onto the first wall of a tokamak. The new method is called ion cyclotron coating (ICC) and is based on ICRF plasma production in gas mixtures containing appropriate reactive precursor molecules. The new method is compatible with the magnetic field since it depends on its presence in order to produce a plasma. The geometrical arrangement of necessary facilities and their characteristic parameters for ICC in TEXTOR-94 will be described as well as the experimental procedure. The ICC-process itself and the properties of the produced layer will be presented.

Adenoviruses (Ads) are nonenveloped DNA viruses with icosahedral symmetry. There are at least 47 known Ad serotypes, many of which are associated with respiratory, gastrointestinal, or ocular disease (23). Ad has served as a model for the study of many biological processes and is in use as a vector for clinical gene therapy (26). Of the known serotypes, the closely related Ad type 2 (Ad2) and Ad5 have been most extensively studied. A multistage pathway by which Ad2 infects epithelial cells has been described elsewhere (21, 50). The outer shell of the Ad capsid contains three major proteins, hexon, penton base, and fiber, along with several minor proteins. Cryoelectron microscopic (cryo-EM) structural studies have revealed the locations of most of these in the viral particle (42, 44) and in some cases have provided clues to their function (18). The majority of the capsid by mass is hexon, which forms the facets of the icosahedral particle (47). Each of the 12 vertices contains a complex of the penton base and fiber proteins (47). A ∼25-Å protrusion at the top of each penton base monomer contains an RGD sequence (43), which interacts with cellular αv integrins to mediate virus internalization and endosome disruption (49, 50). This interaction appears to be conserved across many Ad serotypes (31). In at least some cell types (for example, THP-1 monocytic cells), the penton base can also mediate virus attachment by binding to β2 integrins via its RGD motif (25). The homotrimeric fiber protein forms a prominent spike that protrudes from each vertex of the capsid. Fiber is anchored to the penton base by its N terminus, while its C-terminal domain mediates attachment to cellular receptors (12, 30, 34). The fibers from Ad2 or Ad5 bind to a 46-kDa protein termed CAR (coxsackievirus and adenovirus receptor), expressed on the surface of many cells (4, 45), and the Ad2 fiber protein has also been reported to bind major histocompatibility class I antigens (22). The fiber from Ad3 binds to an as yet unidentified but more widely distributed receptor (14, 41). Since all of these virus serotypes are thought to be internalized via the integrin-penton interaction (31), the fiber-receptor interaction largely determines Ad cell tropism. In addition to its role in targeting Ad infection, the fiber has been proposed to facilitate assembly or to stabilize the viral particles. A number of Ad proteins are synthesized as precursors which are then cleaved to their mature forms by the virally encoded L3 23-kDa protease (2, 3). Studies using fiber mutant viruses have suggested that a defect in the fiber protein might lead to defective proteolytic processing of proteins VI, VII, and VIII and therefore to accumulation of their uncleaved precursors (10, 15, 17). Other defects including abnormal sedimentation on CsCl gradients and incomplete packaging of viral DNA into the mutant particles were reported. These earlier studies led investigators to conclude that defective proteolysis due to lack of the fiber protein leads to a general block in virus maturation. The inability to propagate viral mutants lacking the genes that encode structural proteins has hindered study of their roles in capsid assembly. The aforementioned studies were done with either temperature-sensitive (ts) fiber mutants (10, 15) or deletion mutants that were propagated in the presence of nondefective helper virus (17). Their interpretation may therefore be clouded by leaky expression of the ts protein or by residual helper virus in the preparations. A true null mutant which is completely helper independent would be useful in studying the fiber mutant phenotype. We previously reported the generation of cell lines expressing a functional Ad5 fiber protein, which can complement fiber mutant Ads (48). In the studies reported here, we used these cell lines to generate a helper-independent gene transfer vector with E1, E3, and fiber deleted and have examined the structure and infectivity of Ad5 particles lacking the fiber protein. The fiberless virus, in combination with packaging cell systems that we have previously developed, should be useful in vector retargeting.

Adenovirus-based gene therapy vectors now in use cannot be targeted to specific cell types in vivo and are immunogenic, properties which limit their clinical utility. Improved vectors lacking the genes for viral structural proteins may overcome these limitations. We have developed cell lines which stably express the adenovirus type 5 (Ad5) fibre protein in its native trimeric form. These cells can complement an Ad5 mutant with a defect in the fibre gene, and are capable of incorporating the Ad5 fibre into particles of a different Ad serotype. As the fibre protein is responsible for the initial binding of virus to cells, packaging cell lines expressing different or modified fibre proteins will be useful in studying the mechanism by which adenovirus infects different cell types.

The paper describes the investigation of the progressive erosion of an a-B:D coated test piece during 22 pulses in the SOL of TEXTOR-94. Time resolved observations by colorimetry reveal that the erosion proceeds in steps: during an intermediate phase the rates do not exceed ∼ − 1.5 nm/s. Thereafter they jump to about −6 nm/s. This is due to carbon incorporation and triggered when the concentration approaches ∼ 40%. The changing composition may influence the ratio of the BII/CII emission near the surface. The process ends with a carbon rich layer on the remnants of the boron film. Combination of different investigations (AES, NRA, EPMA) results in a preliminary model description.

Measurements on the formation of hydrocarbons on plasma exposed surfaces performed by mass- and optical emission spectroscopy in TEXTOR is reported. The temperature dependence of hydrocarbon formation and the contribution of the hydrocarbon source to the CII ion densities near the limiter has been observed using a graphite limiter which is externally heatable up to 1400 K. It has been found that hydrocarbon formation occurs in a broad temperature region decreasing only for target temperatures above 1300 K and that hydrocarbons contribute to about 40% to the CII light. Strong methane release has been observed on copper and stainless steel limiters positioned at the LCFS while it is negligible on molybdenum and tungsten limiters under similar plasma edge conditions. Local transport and redeposition of molecules have been studied by gas injection of methane and silane through holes in the limiter surfaces and by local Monte Carlo calculations. Local deposition efficiencies between 4 and 7% have been measured for injected methane and silane. Monte Carlo calculations show, in general, a larger redeposition probability depending only little on local plasma parameters but significantly on the assumptions of the sticking and release properties of redeposited ions and radicals on the surface. For higher surface temperatures possible carbon release by radiation enhanced sublimation (RES) has been investigated. No increase of carbon release could be observed demonstrating that carbon release from RES is negligible under these conditions. Possible reasons for this behavior are discussed.

Since 1992, the boronization using B10H14 (decaborane-based boronization) has been utilized in JT-60 once or twice a year. It is very effective in reducing both the impurities, like oxygen and carbon, in the plasma and in recycling fuel particles. However, we needed ∼ 500 discharges to exchange hydrogen in the boron film for deuterium, after the boronization using only He for a dilution gas. Using a mixed-dilution gas of He and deuterium, we made the boronized film on JT-60 first wall (deuterated-boronization). A typical composition of working gas was 2% B10H14, 38% D2 and 60% He, which was used in a flow through situation. The amounts of hydrogen and deuterium in the boronized film were evaluated to be ∼ 5 and ∼ 30 at%, respectively. In addition, the deuteration factor of D(H + D) in the first plasma after the boronization increased from less than 0.2 to 0.8. Thus, we can drastically reduce the number of the conditioning discharges from ∼ 500 to ∼ 50 for the isotope-exchange before D plasma experiments.

To study local particle transport, silane was injected through a hole in a test limiter surface during discharges in TEXTOR-94. The gas injection lead to the deposition of a thin layer around the injection hole which was close to the area of the highest heat load. The layer was eroded in discharges without silane injection. The layer was not only formed by the injected silicon but also by a large amount of carbon which must originate from other plasma facing components. The preferential direction (symmetry line) of the deposition pattern is tilted by ∼ 25° relative to the magnetic field lines Calculations with the ERO-TEXTOR code recover the general shape of the Si-deposition pattern. To get accordance between the calculations and the experimental results a strong electric field parallel to B and a sticking coefficient much smaller than 1 has to be considered to reproduce the low silicon deposition efficiency, whereas the tilting of the symmetry line can be explained by the existence of a radial electric field.

Silane gas has been injected through a hole in the surface of test limiters during ohmically heated tokamak discharges in TEXTOR-94. The gas injection led to the deposition of a thin layer around the injection hole which was close to the area of the highest heat load. The layer was eroded in discharges without silane injection and spectroscopic measurements prove that the erosion of limiter material is reduced in areas where the layer is deposited. Surface analyses reveal that the layer was formed not only by the injected silicon but also by a large amount of carbon which must originate from other plasma-facing components. The preferential direction (symmetry line) of the deposition pattern is tilted by relative to the magnetic field lines. Calculations with the Monte Carlo code ERO-TEXTOR were used to interpret the data. The shape of the Si-deposition pattern can be recovered quantitatively by including an drift in a radial electric field originating from the gradient in the electron temperature profile above the limiter surface. The deposition pattern allows the `imaging' of the complex plasma flow close to the surface. To obtain agreement between calculated and experimentally observed deposition efficiencies a sticking coefficient much smaller than 1 and the influence of an electric field parallel to B have to be considered.

A limiter made from boron-doped graphite (3.5%, Carbon Lorraine) has been used in TEXTOR as a single main limiter. Additional heating by neutral beam injection (NBI) was applied resulting in heat loads up to 20 MW/m 2 on the limiter, increasing its temperature far beyond 2000 °C. At these high temperatures strong thermal sublimation of boron and carbon from the limiter was measured spectroscopically. After the set of experiments, deposits have been studied on the test limiter and in the SOL on collector probes by interference fringe analysis (IFA), Auger electron spectroscopy (AES), electron microprobe (EPMA) and energy dispersive X-ray analysis (EDX). IFA was applied to estimate the total thickness of the deposits. A very thick boron rich layer (6 μm) had grown near the tangency point of the limiter. Comparing the evaporated and deposited amount of the limiter material a high local deposition of boron and carbon of at least about 69–70% is deduced.

Surface collector probes were applied at TEXTOR for the investigation of silicon fluxes in the scrape-off layer during the first silicon-assisted (silane puffing, siliconization) operation of a tokamak. Probe exposures were made in order to measure the evolution of Si fluxes and the influence of silicon on the behaviour of other impurity fluxes like boron, oxygen and metals. Studies were performed under different conditions: heating mode, plasma density and gas filling. Comparative exposures were made before introduction of Si into the machine as well as immediately and long time after the siliconization. The exposed graphite samples were examined by surface analysis techniques, including Auger electron and Rutherford backscattering spectroscopies, nuclear reaction analysis and ultra-high resolution microscopies. The most important findings are concerned with: (i) the relation between silicon to carbon and silicon to oxygen in the deposits; (ii) the change in radial profiles of Si, B and D fluxes during consecutive stages of the silicon-assisted operation, and the retention of deuterium in the Si containing codeposited layers. The influence of plasma density on the fluxes is considered and gettering of oxygen by silicon is also addressed. Comparison is also made to the results of VUV spectroscopy signals of silicon and oxygen impurities in the plasma.

The erosion of first wall material is a serious problem in future fusion devices. A concept is suggested to compensate erosion by the local injection of reactive gases through divertor plates or limiters forming a suitable deposit on their surfaces. The technique can be implemented during plasma operation with feed back control. Initial experiments were performed in TEXTOR in which silane gas (SiD 4 ) was blown through a hole in a graphite test limiter during ohmic discharges. The gas was ionized and partly deposited in the vicinity of the interaction hole, at areas subject to the highest heat load. Without gas puffing these are erosion dominated zones. The deposition of a silicon layer over an area of about 700 mm 2 , peaked at the injection hole with a maximum thickness of about 900 nm and with a poloidal extend of about 20 mm was observed. It contained a fraction of about 4–5% of the total number of injected Si atoms. In addition, about the same quantity of carbon was co-deposited, significantly exceeding the C fluence arriving from the plasma during normal discharges. An additional local carbon source during silane injection must be invoked, caused e.g. by carbon erosion due to Frank-Condon or charge exchange atoms impinging on the limiter itself on nearby wall areas.

Pure graphite (EK 98), boron-doped graphite (3%B, 15%B, 20%B), thin boron/carbon layers (a-C/B:H films) and B4C were irradiated with energetic oxygen ions of 1–5 keV to study the erosion and retention behaviour of energetic oxygen. The reaction of O+ ions with these materials lead mainly to the formation of volatile CO and CO2 together with physically sputtered carbon, boron and boron oxide species. Compared with graphite, the retention of oxygen in the boron/carbon materials is higher and the reemission of CO and CO2 in delayed after starting the bombardment. The thermal desorption of the implanted oxygen in form of CO occurs in addition to the normal CO peak at 950 K in a second peak at about 1600 K. At these high temperatures also BO, B2O2 and B2O3 (peaked between 1200 K and 1400 K) are desorbed.

Boron-doped graphite (3.5% B in C (S2508, Carbon Lorraine), 20% B in C (GB120, Toyo Tanso)) and titanium-doped graphite (2.1% Ti in C (RGTi, supplied by Efremov Institute, St. Petersburg)) have been tested in TEXTOR as a single main limiter for typically 20–40 discharges. Convective power loads up to about 30 MW/m2 led to maximum surface temperatures between 2400–2800°C. Severe cracking has occurred on the 20% boron-doped graphite material showing that it is not applicable as plasma facing material under high heat loads. Some large cracks have also been observed on the RGTi limiter, probably caused by the strong anisotropy of the material. The 3.5% boron-doped material shows similar thermomechanical properties as a usual fine-grain graphite (EK98). Large thermal sublimation of boron and titanium has been observed starting at surface temperatures of about 2000°C and 1800°C, respectively. Very thick layers of redeposited boron or titanium (> 1 μm) were formed near the areas of high sublimation. Besides the doping species (boron, titanium) these materials sublime various (metallic) impurities at elevated temperatures. No significant increase of the emitted carbon flux has been observed below surface temperatures of 2000°C showing that radiation enhanced sublimation (RES) is significantly reduced under these conditions compared with expected values extrapolated from beam experiments.

The deposition of thin films onto the inner walls of tokamaks by plasma enhanced chemical vapor deposition (PECVD) has been proven to be a most effective conditioning technique for tokamaks. Nevertheless their application is not compatible with future long puls fusion devices (ITER > 1000 s) using permanently superconductive magnetic coils. For this reason a technique has been developed with a continuous or quasi continuous source for low- Z getter material as used in PEVCD. First experiments have been performed using this new conditioning method, named reactive gas fuelling (RGF), which allows on-line conditioning during plasma discharges. Reactive gases like borontrimethyl, silane etc. are fuelled into proceeding tokamak discharges for conditioning purposes. The plasma boundary tales over the poloidal and toroidal distribution of the reactive species, otherwise the same conditioning mechanisms are effective as in PECVD.

An empirical model equation was deduced from oxygen collection experiments made in the scrape-off layer (SOL) of TEXTOR after different conditioning procedures with boron: O( r )= S(r) OI+ G B( r )+ A D( r ). The measured oxygen retention rates, O( r ), are explained in terms of ion sticking, gettering by boron and absorption from air. The coefficients G =0.67 and A =0.087 at the measured rates B( r ) of boron and D( r ) of deuterium are independent of the radial position r in the SOL, while the empirical function S(r) relates the OI-light emission measured at r =50 cm to other radii. S(r) OI represents the sticking contribution of the ion flux. Due to the formation of stable oxides the getter term, G B( r ), contributes significantly to the oxygen collection. It keeps the oxygen content low in the plasma as long as boron is present. The term A D( r ) is understood as oxygen uptake from air during sample transport. Analyses of the deposits grown on the targets (graphite, aluminum) were made by NRA, RBS, sputter AEX, XPS, and interference fringe analysis.

In the framework of developing on-line in situ wall conditioning methods for long pulse tokamaks, the injection of reactive gases into the scrape-off layer during a discharge was investigated. Transport in the plasma scrape-off layer is used to distribute the gas atoms around the torus and condition the walls by deposition of appropriate material. Based on the experience from boronization, we use trimethylboron (TMB) as a first test gas. It is shown that significant amounts of TMB can be puffed during the flat top phase of a discharge without affecting its further evolution negatively. It is further demonstrated that the plasma can be fuelled from the very beginning, including the gas prefill, and maintained exclusively with TMB. Feed back density control is easily achieved. TMB fuelled (puffed) and D2 fuelled discharges show very similar values of Zeff, radiated power fraction, and other global parameters. The effective confinement of B and C atoms from TMB is evaluated using spectroscopic signals.

The plasma-induced deposition of amorphous boron-containing carbon films (a-C/B:H) on the plasma-exposed surfaces of fusion devices (boronization) is a powerful wall conditioning method to achieve very pure fusion plasmas. Glow discharges in a throughflow of diborane, methane and helium gas have been hitherto used in the boronization technique. The highly toxic and explosive gas diborane necessitates strict and expensive safety precautions in the complex environment of a tokamak. Experiments have been performed in laboratory simulations using the much less hazardous substances trimethyl- and triethylboron as precursors for a-C/B:H deposition. The deposition process was monitored by mass spectroscopy and measurement of the distribution of the primary plasma ions. The a-C/B:H layers were analysed by electron microprobe (EPMA) and sputter Auger electron spectroscopy (AES). Films of good quality are obtained from trimethylboron at low pressures (2.7*10-3 mbar) and high sample bias voltages (-300 V). A first application in the tokamak TEXTOR yielded a performance comparable to a-C/B:H from the conventional technique.

Starting with carbonized walls as a reference condition, the TEXTOR vessel has first been flushed with reactive diborane gas (B 2 H 6 ), later the inner plasma facing surface was boronized with a-C/B:H (∼ 100 nm). After the introduction of the boron into the machine a drastic decrease of the oxygen contamination of the plasma could be observed. Surprisingly, the amount of oxygen which has been collected on graphite targets in the scrape-off layer (SOL) showed just the opposite trend : it increased. This behaviour is explained with gettering of the oxygen ions by the simultaneously collected boron. The oxygen forms stable oxides with the boron due to energetic ion deposition keeping the plasma contamination low. The observations allow also the quantification of two other contributing terms : sticking of oxygen ions and the oxygen absorption by uptake from air. For the ex situ analysis, the graphite targets were studied by ion beam analysis (O, B, D, metals). XPS investigations showed the bonding state between oxygen and boron.