The selective functionalization of carbon nanotube surfaces is crucial for many potential applications of these materials. For this purpose several oxidants, among other substances, are used. The aim ...is to reach a large degree of functionalization which depends on the oxidant character of the reagent. For this reason the functionalization of multiwall carbon nanotubes (MWCNTs) by treatment with ozone in basic solution is studied. At basic pHs, ozone results into hydroxyl radicals whose reduction potential is very high (E° = 3.06 V). The results have been compared to those obtained by ozone in gas phase and with cold oxygen plasma. The oxidation with ozone in basic solution seems to be kinetically restricted. As a consequence, the degree of oxidation in this medium is smaller than this of ozone gas, in spite of the larger oxidation capacity of the former. The oxygen-containing groups fixed by these two treatments are mainly attached to defects of the nanotubes. Moreover, no modification of the graphene layers and no porosity result from these treatments. The oxygen plasma treatment stands out in the content of oxygen groups fixed to the MWCNTs, as it is by far more effective, although some of these groups have relatively low thermal stability. Nevertheless, this treatment mainly fixes the oxygen groups on the walls of the nanotubes.
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•H2 plasma removes oxygen groups but not the sulfonyl and sulfonic groups.•Water treatment + H2 plasma treatment removes 60% of oxygen and 100% of sulfur.•This methodology removes as ...much oxygen as NaBH4 but is simpler, faster and cleaner.•The oxygen remaining after H2 plasma reduction forms labile surface groups.•Three GOs were tested rendering similar results.
We report the reduction of GO by hydrogen cold plasma as an effective alternative to the usual chemical (with harsh reducing agents) or physical (through high-temperature treatments) methods. The hydrogen plasma is generated through microwave radiation and the reduction is performed barely above room temperature, avoiding structural degradation of the graphene oxide. Three commercial GOs, with several oxygen and sulfur contents, have been used in this study. As a consequence of the exposure to the hydrogen plasma, the oxygen content is decreased in large extent while sulfur is scarcely removed. Thus a two-stage methodology consisting of a simple water treatment under reflux conditions of GO (to remove sulfur) and further treatment with H2 plasma is proposed. The combination of both steps allows the total elimination of sulfur while achieving very high degrees of reduction, lowering the initial oxygen content by more than 60%. These degrees of reduction are comparable to those obtained when the reduction is carried out by using the standard procedure with NaBH4 on the same materials. The reduction with hydrogen plasma clearly shows advantages over the conventional reduction procedures due to its simplicity: no chemicals or high temperatures are needed, and the procedure is very fast.
Metal(loid)s are common pollutants in soils, causing a significant toxicological risk to living organisms and to the ecosystems. Soil basal respiration (SBR) is broadly used as indicator of ...metal(loid) stress in polluted soils, although the correlation with toxicity gives in many cases contradictory results. In this paper, we study seven different soils with contrasting properties and with different pollution levels of As, Pb, Zn, and Cu to assess the influence of soil properties and contaminant concentration in the SBR response. In general terms, the SBR showed toxic effects in soils with low organic-matter content and acidic pH values. Low respiration rates were found in soils polluted with As even at very high contamination levels. According to our results, SBR is not a good indicator of pollution by Pb, Zn and Cu in soils rich in organic carbon or in highly carbonate soils. In As-polluted soils, SBR also showed a low sensitivity in all cases. Further studies are needed to assess the role of soil properties and the type of pollutant in the SBR tests.
•SBR test presented good sensitivity in low organic-matter content and acidic pH soils.•OC, pH, CaCO3, texture, and CEC are key factors in the pollution assessment by SBR.•SBR test is not a good indicator of Pb, Zn and Cu pollution in highly carbonate soils.•SBR test showed low sensitivity in As-polluted soils.
The continuous and dramatic increase of global demand for energy resources makes it urgent to develop affordable nanostructured materials to act as efficient electrocatalysts (ECs) in the ...energy-related reactions. Metal–organic framework (MOF) template pyrolysis for the production of nanostructured carbon-based materials is a very promising methodology to produce carbon-based ECs. Herein, we report the preparation, characterization (XPS, CHNS analysis, ICP-OES, XRD, TEM, and SEM/EDS), and application as oxygen evolution reaction (OER) and oxygen reduction reaction (ORR) ECs of a plethora of nanostructured carbon materials derived from RT-synthesized (RT, room temperature) MOF-74 with different metal compositions, Co, Ni and Co/Ni, and dopant heteroatoms, N–, S– and N/S-dual-doping. This has allowed the study of the aforementioned parameters’ influence on the OER and ORR electrocatalytic activity in alkaline medium. Highly synergetic effects have been detected in two cases: (1) when N/S-dual-doped carbon is produced from a monometallic Co-MOF-74 template, N,S–Co@C, and (2) when an undoped carbon is derived from bimetallic Co/Ni-MOF-74, Co/Ni@C. These two samples achieve OER performances with η10 = 0.41 and 0.44 V, respectively, along with Tafel slopes of 101 and 93 mV dec–1, being close to the state-of-art OER catalyst performance. In addition, ORR tests showed that the effect of heteroatom doping on ORR activity is always positive, regardless of metal composition.
Controlling the chemistry on the surface of new carbon materials is a key factor to widen the range of their applicability. In this paper we show a grafting methodology of polyalkylamines to the ...surface of carbon nanomaterials, in particular, carbon nanotubes and a carbon black. The aim of this work is to reach large degrees of covalent functionalization with hyperbranched polyethyleneimines (HBPEIs) and to efficiently preserve the strong chelating properties of the HBPEIs when they are fixed to the surface of these carbon materials. This functionalization opens new possibilities of using these carbon nanotubes-based hybrids. The results show that the HBPEIs are covalently attached to the carbon materials, forming hybrids. These hybrids emerge from the reaction of amine functions of the HBPEIs with carbonyls and carboxylic anhydrides of the carbon surface which become imine and imide bonds. Thus, due to the nature of these bonds, the pre-oxidized samples with relevant number of C=O groups showed an increase in the degree of functionalization with the HBPEIs. Furthermore, both the acid-base properties and the coordination capacity for metal ions of the hybrids are equivalent to that of the free HBPEIs in solution. This means that the chemical characteristics of the HBPEIs have been efficiently transferred to the hybrids. To reach this conclusion we have developed a novel procedure to assess the acid-base and the coordination properties of the hybrids (solids) by means of potentiometric titration. The good agreement of the values obtained for the hybrids and for the free HBPEIs in aqueous solution supports the reliability of the procedure. Moreover, the high capacity of the hybrids to capture Ni
2+
by complexation opens new possibilities of using these hybrids to capture high-value metal ions such as Pd
2+
and Pt
2+
.
Hyperbranched polyethylenimines are covalently fixed to the surface of carbon materials, so the chemical characteristics of the amines are transferred to the hybrid materials.
Summary
Background
In horses castration with primary intention healing is usually performed under balanced inhalation anaesthesia. To optimise analgesia, the use of local anaesthesia was tested.
...Objectives
To investigate the effect of local mepivacaine before castration with first intention healing under balanced medetomidine‐isoflurane anaesthesia and flunixin meglumine, morphine analgesia on perioperative cytokine levels and pain in horses.
Study design
Prospective blinded clinical study.
Methods
Twenty stallions were randomly assigned to control or mepivacaine groups. Flunixin meglumine was administered before sedation with medetomidine and followed by ketamine/diazepam intravenously (i.v.). Anaesthesia was maintained with isoflurane and 3.5 μg/kg per hour medetomidine. Mepivacaine horses were given mepivacaine 2% (3.5 mL SC, 1 mL/100 kg intrafunicularly, 2 mL/100 kg intratesticularly) on each side. For recovery, horses were given 2 μg/kg medetomidine i.v. and 0.1 mg/kg morphine i.m. and oral phenylbutazone (0.02 mg/kg q12h) for post‐operative analgesia. One hour before premedication and 4, 8 and 24 h post‐incision, pain was scored with three different pain scales (Equine Utrecht University Scale for Facial Assessment of Pain, Horse Grimace Scale, Equine Utrecht University Scale for Composite Pain Assessment) and plasma cytokines (interleukin‐6 and tumour necrosis factor alpha) were measured. Data were analysed using repeated measures ANOVA, linear regression and unpaired t‐test, significance level P≤0.05.
Results
Horses in both groups showed a significant increase in pain scores and cytokines compared to baseline. Post‐operatively the mepivacaine group exhibited significantly lower pain scores and cytokine levels. Mean heart rate during anaesthesia was significantly lower in the mepivacaine group compared to control group (28.8 ± 1 and 33.2 ± 1.7 respectively). Otherwise there were no differences between the groups.
Main limitations
The decision to provide additional analgesia was based on the attending surgeon's assessment rather than a standardised rescue analgesia plan based on pain scores. The study was only conducted for 24 h post‐castration and complications were not recorded.
Conclusion
Local mepivacaine before castration with primary wound closure improved anaesthesia quality, attenuated post‐operative increases in cytokines and reduced post‐operative pain despite balanced anaesthesia with multimodal analgesia in control horses.
This article reports a new way to covalently bond chlorine to multiwalled carbon nanotubes (MWCNTs) by using a carbon tetrachloride cold plasma treatment. Several factors controlling the efficiency ...of the plasma treatment were considered. In particular, the methodology to produce the plasma and the temperature and time of treatment were taken into account. The largest chlorine surface concentration was obtained when the MWCNTs were treated with helium plasma before the CCl4 plasma to activate the surface. Short periods of plasma treatment (5–10 min) were then sufficient to reach high degrees of chlorination (up to 19.2% by weight) much larger than those previously reported. The functionalization takes place mainly in the borders and defects of the tubes, thus preserving the conjugation existing in the graphene layers. Moreover, the treatments show no influence on the textural characteristics of the nanotubes (i.e., porosity and interlayer spacing). Therefore, the method proposed in this work is an excellent approach to introducing surface chlorine atoms, capable of acting as leaving groups, as a first step for further functionalization with more complex molecules, while preserving the morphology and mechanical properties of the nanotubes still intact.
The aim of this paper is to introduce the WIRCam Ultra Deep Survey (WUDS), a near-IR photometric survey carried out at the CFH Telescope in the field of the CFHTLS-D3 field (Groth Strip). WUDS ...includes four near-IR bands (Y, J, H and Ks) over a field of view of ∼400 arcmin2. The typical depth of WUDS data reaches between ∼26.8 in Y and J, and ∼26 in H and Ks (AB, 3σ in 1.3″ aperture), whereas the corresponding depth of the CFHTLS-D3 images in this region ranges between 28.6 and 29 in ugr, 28.2 in i and 27.1 in z (same S/N and aperture). The area and depth of this survey were specifically tailored to set strong constraints on the cosmic star formation rate and the luminosity function brighter or around L⋆ in the z ∼ 6 − 10 redshift domain, although these data are also useful for a variety of extragalactic projects. This first paper is intended to present the properties of the public WUDS survey in details: catalog building, completeness and depth, number counts, photometric redshifts, and global properties of the galaxy population. We have also concentrated on the selection and characterization of galaxy samples at z ∼ 4.5 − 7 in this field. For these purposes, we include an adjacent shallower area of ∼1260 arcmin2 in this region, extracted from the WIRCam Deep Survey (WIRDS), and observed in J, H and Ks bands. UV luminosity functions were derived at z ∼ 5 and z ∼ 6 taking advantage from the fact that WUDS covers a particularly interesting regime at intermediate luminosities, which allows a combined determination of M⋆ and Φ⋆ with increased accuracy. Our results on the luminosity function are consistent with a small evolution of both M⋆ and Φ⋆ between z = 5 and z = 6, irrespective of the method used to derive them, either photometric redshifts applied to blindly-selected dropout samples or the classical Lyman Break Galaxy color-preselected samples. Our results lend support to higher Φ⋆ determinations at z = 6 than usually reported. The selection and combined analysis of different galaxy samples at z ≥ 7 will be presented in a forthcoming paper, as well as the evolution of the UV luminosity function between z ∼ 4.5 and 9. WUDS is intended to provide a robust database in the near-IR for the selection of targets for detailed spectroscopic studies, in particular for the EMIR/GTC GOYA Survey.
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•Very low concentrations of 25C-NBOMe cause high mortality rates in Artemia salina and zebrafish.•25C-NBOMe induces changes in behavioral patterns in Artemia salina and zebrafish ...animal models.•25C-NBOMe has teratogenic effects on zebrafish development.
The NBOMe (N-2-methoxybenzyl-phenethylamines) family of compounds are synthetic hallucinogens derived from the 2C series. Although this family of compounds has been responsible for multiple cases of acute toxicity and several deaths around the world, to date there are few studies. These compounds act as potent 5-HT2A receptor agonists, including the hallucinogen 25C-NBOMe (2-(4-chloro-2,5-dimethoxyphenyl)-N-(2-methoxyphenyl)methylethanamine). In this study, we first evaluated the toxicity of 25C-NBOMe in two animal models: Artemia salina and zebrafish using the lethality test of Meyer et al. (1982) modified for Artemia salina and the Fish Embryo Toxicity test (FET) for zebrafish (Danio rerio). Subsequently, we determined the behavioral and morphological effects using different concentrations of the 25C-NBOMe. As a result, we found that this substance is highly toxic according to lethality tests in both animal models. We also observe that this hallucinogen induces alterations in swimming and motility patterns in Artemia salina. Similarly, there were alterations in the motor response to a stimulus, as well as abnormal development in the zebrafish. The developmental effects of zebrafish suggest a teratogenic potential for 25C-NBOMe. Therefore, these findings are correlated with side effects, such as motor response abnormalities and muscle deterioration, clinically reported for consumers of this recreational drug. Finally, although recent studies are addressing the neurotoxicity and cardiotoxicity of 25C-NBOMe in cell cultures, to the best of our knowledge, this is the first in vivo report for 25C-NBOMe related to toxicological parameters and their global effects on development. Therefore, it could represent an advance in the study of the substance that contributes to the understanding of the effects on behavior and development in humans.
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