826 research outputs found
Rapid and Efficient Removal of Perfluorooctanoic Acid from Water with Fluorine-Rich Calixarene-Based Porous Polymers
On account of its nonbiodegradable nature and persistence in the environment, perfluorooctanoic acid (PFOA) accumulates in water resources and poses serious environmental issues in many parts of the world. Here, we present the development of two fluorine-rich calix[4]arene-based porous polymers, FCX4-P and FCX4-BP, and demonstrate their utility for the efficient removal of PFOA from water. These materials featured Brunauer–Emmett–Teller (BET) surface areas of up to 450 m^{2} g^{-1}, which is slightly lower than their nonfluorinated counterparts (up to 596 m^{2} g^{-1}). FCX4-P removes PFOA at environmentally relevant concentrations with a high rate constant of 3.80 g mg^{-1} h^{-1} and reached an exceptional maximum PFOA uptake capacity of 188.7 mg g^{-1}. In addition, it could be regenerated by simple methanol wash and reused without a significant decrease in performance
Co3O4 Nanocrystals on Graphene as a Synergistic Catalyst for Oxygen Reduction Reaction
Catalysts for oxygen reduction and evolution reactions are at the heart of
key renewable energy technologies including fuel cells and water splitting.
Despite tremendous efforts, developing oxygen electrode catalysts with high
activity at low costs remains a grand challenge. Here, we report a hybrid
material of Co3O4 nanocrystals grown on reduced graphene oxide (GO) as a
high-performance bi-functional catalyst for oxygen reduction reaction (ORR) and
oxygen evolution reaction (OER). While Co3O4 or graphene oxide alone has little
catalytic activity, their hybrid exhibits an unexpected, surprisingly high ORR
activity that is further enhanced by nitrogen-doping of graphene. The
Co3O4/N-doped graphene hybrid exhibits similar catalytic activity but superior
stability to Pt in alkaline solutions. The same hybrid is also highly active
for OER, making it a high performance non-precious metal based bi-catalyst for
both ORR and OER. The unusual catalytic activity arises from synergetic
chemical coupling effects between Co3O4 and graphene.Comment: published in Nature Material
Genetic Covariance Structure of Reading, Intelligence and Memory in Children
This study investigates the genetic relationship among reading performance, IQ, verbal and visuospatial working memory (WM) and short-term memory (STM) in a sample of 112, 9-year-old twin pairs and their older siblings. The relationship between reading performance and the other traits was explained by a common genetic factor for reading performance, IQ, WM and STM and a genetic factor that only influenced reading performance and verbal memory. Genetic variation explained 83% of the variation in reading performance; most of this genetic variance was explained by variation in IQ and memory performance. We hypothesize, based on these results, that children with reading problems possibly can be divided into three groups: (1) children low in IQ and with reading problems; (2) children with average IQ but a STM deficit and with reading problems; (3) children with low IQ and STM deficits; this group may experience more reading problems than the other two
Surplus Photosynthetic Antennae Complexes Underlie Diagnostics of Iron Limitation in a Cyanobacterium
Chlorophyll fluorescence from phytoplankton provides a tool to assess iron limitation in the oceans, but the physiological mechanism underlying the fluorescence response is not understood. We examined fluorescence properties of the model cyanobacterium Synechocystis PCC6803 and a ΔisiA knock-out mutant of the same species grown under three culture conditions which simulate nutrient conditions found in the open ocean: (1) nitrate and iron replete, (2) limiting-iron and high-nitrate, representative of natural high-nitrate, low-chlorophyll regions, and (3) iron and nitrogen co-limiting. We show that low variable fluorescence, a key diagnostic of iron limitation, results from synthesis of antennae complexes far in excess of what can be accommodated by the iron-restricted pool of photosynthetic reaction centers. Under iron and nitrogen co-limiting conditions, there are no excess antennae complexes and variable fluorescence is high. These results help to explain the well-established fluorescence characteristics of phytoplankton in high-nutrient, low-chlorophyll ocean regions, while also accounting for the lack of these properties in low-iron, low-nitrogen regions. Importantly, our results complete the link between unique molecular consequences of iron stress in phytoplankton and global detection of iron stress in natural populations from space
Betibeglogene Autotemcel Gene Therapy for Non-β⁰/β⁰ Genotype β-Thalassemia
BACKGROUND: Betibeglogene autotemcel (beti-cel) gene therapy for transfusion-dependent β-thalassemia contains autologous CD34+ hematopoietic stem cells and progenitor cells transduced with the BB305 lentiviral vector encoding the β-globin (βA-T87Q) gene. METHODS: In this open-label, phase 3 study, we evaluated the efficacy and safety of beti-cel in adult and pediatric patients with transfusion-dependent β-thalassemia and a non-β0/β0 genotype. Patients underwent myeloablation with busulfan (with doses adjusted on the basis of pharmacokinetic analysis) and received beti-cel intravenously. The primary end point was transfusion independence (i.e., a weighted average hemoglobin level of ≥9 g per deciliter without red-cell transfusions for ≥12 months). RESULTS: A total of 23 patients were enrolled and received treatment, with a median follow-up of 29.5 months (range, 13.0 to 48.2). Transfusion independence occurred in 20 of 22 patients who could be evaluated (91%), including 6 of 7 patients (86%) who were younger than 12 years of age. The average hemoglobin level during transfusion independence was 11.7 g per deciliter (range, 9.5 to 12.8). Twelve months after beti-cel infusion, the median level of gene therapy-derived adult hemoglobin (HbA) with a T87Q amino acid substitution (HbAT87Q) was 8.7 g per deciliter (range, 5.2 to 10.6) in patients who had transfusion independence. The safety profile of beti-cel was consistent with that of busulfan-based myeloablation. Four patients had at least one adverse event that was considered by the investigators to be related or possibly related to beti-cel; all events were nonserious except for thrombocytopenia (in 1 patient). No cases of cancer were observed. CONCLUSIONS: Treatment with beti-cel resulted in a sustained HbAT87Q level and a total hemoglobin level that was high enough to enable transfusion independence in most patients with a non-β0/β0 genotype, including those younger than 12 years of age. (Funded by Bluebird Bio; HGB-207 ClinicalTrials.gov number, NCT02906202.)
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The FIELDS Instrument Suite for Solar Probe Plus: Measuring the Coronal Plasma and Magnetic Field, Plasma Waves and Turbulence, and Radio Signatures of Solar Transients.
NASA's Solar Probe Plus (SPP) mission will make the first in situ measurements of the solar corona and the birthplace of the solar wind. The FIELDS instrument suite on SPP will make direct measurements of electric and magnetic fields, the properties of in situ plasma waves, electron density and temperature profiles, and interplanetary radio emissions, amongst other things. Here, we describe the scientific objectives targeted by the SPP/FIELDS instrument, the instrument design itself, and the instrument concept of operations and planned data products
Test-retest repeatability of child's respiratory symptoms and perceived indoor air quality - comparing self-and parent-administered questionnaires
Background: Questionnaires can be used to assess perceived indoor air quality and symptoms in schools. Questionnaires for primary school aged children have traditionally been parent-administered, but self-administered questionnaires would be easier to administer and may yield as good, if not better, information. Our aim was to compare the repeatability of self- and parent-administered indoor air questionnaires designed for primary school aged pupils. Methods: Indoor air questionnaire with questions on child's symptoms and perceived indoor air quality in schools was sent to parents of pupils aged 7-12 years in two schools and again after two weeks. Slightly modified version of the questionnaire was administered to pupils aged 9-12 years in another two schools and repeated after a week. 351 (52%) parents and 319 pupils (86%) answered both the first and the second questionnaire. Test-retest repeatability was assessed with intra-class correlation (ICC) and Cohen's kappa coefficients (k). Results: Test-retest repeatability was generally between 0.4-0.7 (ICC; k) in both self-and parent-administered questionnaire. In majority of the questions on symptoms and perceived indoor air quality test-retest repeatability was at the same level or slightly better in self-administered compared to parent-administered questionnaire. Agreement of self-and parent administered questionnaires was generally <0.4 (ICC; k) in reported symptoms and 0.4-0.6 (ICC; k) in perceived indoor air quality. Conclusions: Children aged 9-12 years can give as, or even more, repeatable information about their respiratory symptoms and perceived indoor air quality than their parents. Therefore, it may be possible to use self-administered questionnaires in future studies also with children.Peer reviewe
The Mitochondrial Ca(2+) Uniporter: Structure, Function, and Pharmacology.
Mitochondrial Ca(2+) uptake is crucial for an array of cellular functions while an imbalance can elicit cell death. In this chapter, we briefly reviewed the various modes of mitochondrial Ca(2+) uptake and our current understanding of mitochondrial Ca(2+) homeostasis in regards to cell physiology and pathophysiology. Further, this chapter focuses on the molecular identities, intracellular regulators as well as the pharmacology of mitochondrial Ca(2+) uniporter complex
Induction of Foxp3-Expressing Regulatory T-Cells by Donor Blood Transfusion Is Required for Tolerance to Rat Liver Allografts
BACKGROUND:Donor-specific blood transfusion (DST) prior to solid organ transplantation has been shown to induce long-term allograft survival in the absence of immunosuppressive therapy. Although the mechanisms underlying DST-induced allograft tolerance are not well defined, there is evidence to suggest DST induces one or more populations of antigen-specific regulatory cells that suppress allograft rejection. However, neither the identity nor the regulatory properties of these tolerogenic lymphocytes have been reported. Therefore, the objective of this study was to define the kinetics, phenotype and suppressive function of the regulatory cells induced by DST alone or in combination with liver allograft transplantation (LTx). METHODOLOGY/PRINCIPAL FINDINGS:Tolerance to Dark Agouti (DA; RT1(a)) rat liver allografts was induced by injection (iv) of 1 ml of heparinized DA blood to naïve Lewis (LEW; RT1(l)) rats once per week for 4 weeks prior to LTx. We found that preoperative DST alone generates CD4(+) T-cells that when transferred into naïve LEW recipients are capable of suppressing DA liver allograft rejection and promoting long-term survival of the graft and recipient. However, these DST-generated T-cells did not express the regulatory T-cell (Treg) transcription factor Foxp3 nor did they suppress alloantigen (DA)-induced activation of LEW T-cells in vitro suggesting that these lymphocytes are not fully functional regulatory Tregs. We did observe that DST+LTx (but not DST alone) induced the time-dependent formation of CD4(+)Foxp3(+) Tregs that potently suppressed alloantigen-induced activation of naïve LEW T-cells in vitro and liver allograft rejection in vivo. Finally, we present data demonstrating that virtually all of the Foxp3-expressing Tregs reside within the CD4(+)CD45RC(-) population whereas in which approximately 50% of these Tregs express CD25. CONCLUSIONS/SIGNIFICANCE:We conclude that preoperative DST, in the absence of liver allograft transplantation, induces the formation of CD4(+) T-cells that are not themselves Tregs but give rise directly or indirectly to fully functional CD4(+)CD45RC(-)Foxp3(+)Tregs when transferred into MHC mismatched recipients prior to LTx. These Tregs possess potent suppressive activity and are capable of suppressing acute liver allograft rejection. Understanding the mechanisms by which preoperative DST induces the generation of tolerogenic Tregs in the presence of alloantigens may lead to the development of novel antigen-specific immunological therapies for the treatment of solid organ rejection
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