258 research outputs found
Deceleration of a supersonic beam of SrF molecules to 120 m/s
We report on the deceleration of a beam of SrF molecules from 290 to 120~m/s.
Following supersonic expansion, the molecules in the (, )
low-field seeking states are trapped by the moving potential wells of a
traveling-wave Stark decelerator. With a deceleration strength of 9.6 km/s
we have demonstrated the removal of 85 % of the initial kinetic energy in a 4
meter long modular decelerator. The absolute amount of kinetic energy removed
is a factor 1.5 higher compared to previous Stark deceleration experiments. The
demonstrated decelerator provides a novel tool for the creation of highly
collimated and slow beams of heavy diatomic molecules, which serve as a good
starting point for high-precision tests of fundamental physics
Circumventing antivector immunity: potential use of nonhuman adenoviral vectors
Adenoviruses are efficient gene delivery vectors based on their ability to transduce a wide variety of cell types and drive high-level transient transgene expression. While there have been advances in modifying human adenoviral (HAdV) vectors to increase their safety profile, there are still pitfalls that need to be further addressed. Preexisting humoral and cellular immunity against common HAdV serotypes limits the efficacy of gene transfer and duration of transgene expression. As an alternative, nonhuman AdV (NHAdV) vectors can circumvent neutralizing antibodies against HAdVs in immunized mice and monkeys and in human sera, suggesting that NHAdV vectors could circumvent preexisting humoral immunity against HAdVs in a clinical setting. Consequently, there has been an increased interest in developing NHAdV vectors for gene delivery in humans. In this review, we outline the recent advances and limitations of HAdV vectors for gene therapy and describe examples of NHAdV vectors focusing on their immunogenicity, tropism, and potential as effective gene therapy vehicles
Binary Mixtures of SH- and CH3-Terminated Self-Assembled Monolayers to Control the Average Spacing Between Aligned Gold Nanoparticles
This paper presents a method to control the average spacing between organometallic chemical vapor deposition (OMCVD) grown gold nanoparticles (Au NPs) in a line. Focused ion beam patterned CH3-terminated self-assembled monolayers are refilled systematically with different mixtures of SH- and CH3-terminated silanes. The average spacing between OMCVD Au NPs is demonstrated systematically to decrease by increasing the v/v% ratio of the thiols in the binary silane mixtures with SH- and CH3-terminated groups
Silicon-hydroxyapatite bioactive coatings (Si-HA) from diatomaceous earth and silica. Study of adhesion and proliferation of osteoblast-like cells
The aim of this study consisted on investigating
the influence of silicon substituted hydroxyapatite (SiâHA)
coatings over the human osteoblast-like cell line (SaOS-2)
behaviour. Diatomaceous earth and silica, together with
commercial hydroxyapatite were respectively the silicon
and HA sources used to produce the SiâHA coatings. HA
coatings with 0 wt% of silicon were used as control of the
experiment. Pulsed laser deposition (PLD) was the selected
technique to deposit the coatings. The SiâHA thin films
were characterized by Fourier Transformed Infrared
Spectroscopy (FTIR) demonstrating the efficient transfer of
Si to the HA structure. The in vitro cell culture was
established to assess the cell attachment, proliferation and
osteoblastic activity respectively by, Scanning Electron
Microscopy (SEM), DNA and alkaline phosphatase (ALP)
quantification. The SEM analysis demonstrated a similar
adhesion behaviour of the cells on the tested materials and
the maintenance of the typical osteoblastic morphology
along the time of culture. The SiâHA coatings did not
evidence any type of cytotoxic behaviour when compared
with HA coatings. Moreover, both the proliferation rate
and osteoblastic activity results showed a slightly better
performance on the SiâHA coatings from diatoms than on
the SiâHA from silica.This work was supported by the UE-Interreg IIIA (SP1.P151/03) Proteus project and Xunta de Galicia ( Projects: 2006/12 and PGIDITO5PXIC30301PN)
Prenatal Correction of X-Linked Hypohidrotic Ectodermal Dysplasia.
Genetic deficiency of ectodysplasin A (EDA) causes X-linked hypohidrotic ectodermal dysplasia (XLHED), in which the development of sweat glands is irreversibly impaired, an condition that can lead to life-threatening hyperthermia. We observed normal development of mouse fetuses with Eda mutations after they had been exposed in utero to a recombinant protein that includes the receptor-binding domain of EDA. We administered this protein intraamniotically to two affected human twins at gestational weeks 26 and 31 and to a single affected human fetus at gestational week 26; the infants, born in week 33 (twins) and week 39 (singleton), were able to sweat normally, and XLHED-related illness had not developed by 14 to 22 months of age. (Funded by Edimer Pharmaceuticals and others.)
Steering hyper-giants' traffic at scale
Large content providers, known as hyper-giants, are responsible for sending the majority of the content traffic to consumers. These hyper-giants operate highly distributed infrastructures to cope with the ever-increasing demand for online content. To achieve 40 commercial-grade performance of Web applications, enhanced end-user experience, improved reliability, and scaled network capacity, hyper-giants are increasingly interconnecting with eyeball networks at multiple locations. This poses new challenges for both (1) the eyeball networks having to perform complex inbound traffic engineering, and (2) hyper-giants having to map end-user requests to appropriate servers. We report on our multi-year experience in designing, building, rolling-out, and operating the first-ever large scale system, the Flow Director, which enables automated cooperation between one of the largest eyeball networks and a leading hyper-giant. We use empirical data collected at the eyeball network to evaluate its impact over two years of operation. We find very high compliance of the hyper-giant to the Flow Directorâs recommendations, resulting in (1) close to optimal user-server mapping, and (2) 15% reduction of the hyper-giantâs traffic overhead on the ISPâs long-haul links, i.e., benefits for both parties and end-users alike.EC/H2020/679158/EU/Resolving the Tussle in the Internet: Mapping, Architecture, and Policy Making/ResolutioNe
Decreased Pre-existing Ad5 Capsid and Ad35 Neutralizing Antibodies Increase HIV-1 Infection Risk in the Step Trial Independent of Vaccination
<div><h3>Background</h3><p>The Step trial raised the possibility that uncircumcised men with pre-existing Ad5 neutralizing antibodies carried an increased risk of HIV infection after vaccination. Thus, understanding Ad seropositivity in humans is important to the development of an AIDS vaccine. Here, we analyze the impact of different Ad5-specific neutralizing antibodies on immune function and clinical outcome.</p> <h3>Methods and Findings</h3><p>Ad seropositivity in the Step trial volunteers was analyzed using chimeric rAd5/35 vectors to characterize their specificity for Ad5 fiber and non-fiber external (capsid) proteins. Immune responses and HIV seropositivity were correlated with the specificity of Ad5-neutralizing antibodies. Neutralizing antibodies induced by the vaccine in Ad5 seronegative subjects were directed preferentially to Ad5 capsid proteins, although some fiber-neutralizing antibodies could be detected. Pre-vaccination Ad5 serostatus did not affect the capsid-directed response after three vaccinations. In contrast, anti-fiber antibody titers were significantly higher in volunteers who were Ad5 seropositive prior to vaccination. Those Ad5 seropositive subjects who generated anti-capsid responses showed a marked reduction in vaccine-induced CD8 responses. Unexpectedly, anti-vector immunity differed qualitatively in Ad5 seropositive participants who became HIV-1 infected compared to uninfected case controls; Ad5 seropositive participants who later acquired HIV had lower neutralizing antibodies to capsid. Moreover, Ad35 seropositivity was decreased in HIV-infected subjects compared with uninfected case controls, while seroprevalence for other serotypes including Ad14, Ad28 and Ad41 was similar in both groups.</p> <h3>Conclusions</h3><p>Together, these findings suggest that the case subjects were less immunologically responsive prior to infection. Subjects infected during the Step trial had qualitative differences in immunity that increased their risk of HIV-1 infection independent of vaccination.</p> </div
Biological response to pre-mineralized starch based scaffolds for bone tissue engineering
It is known that calcium-phosphate (Ca-P) coatings are able not only to improve the bone
bonding behaviour of polymeric materials, but at the same time play a positive role on
enhancing cell adhesion and inducing the differentiation of osteoprogenitor cells. Recently
an innovative biomimetic methodology, in which a sodium silicate gel was used as a
nucleative agent, was proposed as an alternative to the currently available biomimetic
coating methodologies. This methodology is especially adequate for coating biodegradable
porous scaffolds. In the present work we evaluated the influence of the referred to
treatment on the mechanical properties of 50/50 (wt%) blend of corn starch/ethylene-vinyl
alcohol (SEVA-C) based scaffolds. These Ca-P coated scaffolds presented a compressive
modulus of 224.6 ± 20.6 and a compressive strength of 24.2 ± 2.20. Cytotoxicity evaluation
was performed according ISO/EN 10993 part 5 guidelines and showed that the biomimetic
treatment did not have any deleterious effect on L929 cells and did not inhibit cell growth.
Direct contact assays were done by using a cell line of human osteoblast like cells (SaOS-2).
3 Ă 105 cells were seeded per scaffold and allowed to grow for two weeks at 37 âŠC in a
humidified atmosphere containing 5% CO2. Total protein quantification and scanning
electron microscopy (SEM) observation showed that cells were able to grow in the
pre-mineralized scaffolds. Furthermore cell viability assays (MTS test) also show that cells
remain viable after two weeks in culture. Finally, protein expression studies showed that
after two weeks osteopontin and collagen type I were being expressed by SaOS-2 cells
seeded on the pre-mineralized scaffolds. Moreover, alkaline phosphatase (ALP) activity was
higher in the supernatants collected from the pre-mineralized samples, when compared to
the control samples (non Ca-P coated). This may indicate that a faster mineralization of the
ECM produced on the pre-mineralized samples was occurring. Consequently, biomimetic
pre-mineralization of starch based scaffolds can be a useful route for applying these
materials on bone tissue engineering
Protecting tropical forests from the rapid expansion of rubber using carbon payments
Expansion of Hevea brasiliensis rubber plantations is a resurgent driver of deforestation, carbon emissions, and biodiversity loss in Southeast Asia. Southeast Asian rubber extent is massive, equivalent to 67% of oil palm, with rapid further expansion predicted. Results-based carbon finance could dis-incentivise forest conversion to rubber, but efficacy will be limited unless payments match, or at least approach, the costs of avoided deforestation. These include opportunity costs (timber and rubber profits), plus carbon finance scheme setup (transaction) and implementation costs. Using comprehensive Cambodian forest data, exploring scenarios of selective logging and conversion, and assuming land-use choice is based on net present value, we find that carbon prices of 51 per tCO2are needed to break even against costs, higher than those currently paid on carbon markets or through carbon funds. To defend forests from rubber, either carbon prices must be increased, or other strategies are needed, such as corporate zero-deforestation pledges, and governmental regulation and enforcement of forest protection
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