1,374 research outputs found
Recyclable GO-Arginine Hybrids for CO2 Fixation into Cyclic Carbonates
New covalently modified GO-guanidine materials are realized on a gram-scale synthesis and purified via an innovative microfiltration. The use of these composites in the fixation of CO2into cyclic carbonates is demonstrated. Mild operating conditions, high yields (up to 85%), wide scope (15 examples) and recoverability/reusability (up to 5 cycle) of the material account for the efficiency of the protocol. Dedicated control experiments contributed to shed light on the activation modes exerted by the GO-Arg (Arg: arginine) during the ring-opening/closing synthetic sequence
Scalable synthesis and purification of functionalized graphene nanosheets for water remediation.
PEI modified graphene oxide (GOPEI) is prepared by tandem MW aminationâmicrofiltration and used for arsenic removal from water
Amino acid-driven adsorption of emerging contaminants in water by modified graphene oxide nanosheets
Graphene oxide nanosheets have shown promising adsorption properties toward emerging organic contaminants in drinking water. Here, we report a family of graphene oxide nanosheets covalently modified with amino acids and the study on their adsorption properties toward a mixture of selected contaminants, including pharmaceuticals, additives, and dyes. Graphene oxides modified with l-glutamic acid and l-methionine (GO-Glu and GO-Met) were synthesized and purified with a scalable and fast synthetic and purification procedure, and their structure was studied by combined X-ray photoelectron spectroscopy and elemental analysis. An amino acid loading of about 5% and a slight reduction (from 27% down to 14-20% oxygen) were found and associated with the adsorption selectivity. They were compared to unmodified GO, reduced GO (rGO), GO-lysine, and to the reference sample GO-NaOH. Each type of modified GO possesses a higher adsorption capacity toward bisphenol A (BPA), benzophenone-4 (BP4), and carbamazepine (CBZ) than standard GO and rGO, and the adsorption occurred within the first hour of contact time. The maximum adsorption capacity (estimated from the adsorption isotherms) was strictly related to the amino acid loading. Accordingly, molecular dynamics simulations highlighted higher interaction energies for the modified GOs than unmodified GO, as a result of higher van der Waals and hydrophobic interactions between the contaminants and the amino acid side chains on the nanosheet surface
Chemical Tailoring of ÎČ-Cyclodextrin-Graphene Oxide for Enhanced Per- and Polyfluoroalkyl Substances (PFAS) Adsorption from Drinking Water
We report on the synthesis of ÎČ-cyclodextrin (ÎČCD) modified graphene oxide (GO) nanosheets, having different sized alkyl linkers (GO-Cn-ÎČCD) and their exploitation as sorbent of per- and polyfluoroalkyl substances (PFAS) from drinking water. ÎČCD were functionalized with a pending amino group, and the resulting precursors grafted to GO nanosheets by epoxide ring opening reaction. Loading of ÎČCD units in the range 12 %â36 % was estimated by combined XPS and elemental analysis. Adsorption tests on perfluorobutanoic acid (PFBA), a particularly persistent PFAS selected as case study, revealed a strong influence of the alkyl linker length on the adsorption efficiency, with the hexyl linker derivative GO-C6-ÎČCD outperforming both pristine GO and granular activated carbon (GAC), the standard sorbent benchmark. Molecular dynamic simulations ascribed this evidence to the favorable orientation of the ÎČCD unit on the surface of GO which enables a strong contaminant molecules retention
JANUS: an FPGA-based System for High Performance Scientific Computing
This paper describes JANUS, a modular massively parallel and reconfigurable
FPGA-based computing system. Each JANUS module has a computational core and a
host. The computational core is a 4x4 array of FPGA-based processing elements
with nearest-neighbor data links. Processors are also directly connected to an
I/O node attached to the JANUS host, a conventional PC. JANUS is tailored for,
but not limited to, the requirements of a class of hard scientific applications
characterized by regular code structure, unconventional data manipulation
instructions and not too large data-base size. We discuss the architecture of
this configurable machine, and focus on its use on Monte Carlo simulations of
statistical mechanics. On this class of application JANUS achieves impressive
performances: in some cases one JANUS processing element outperfoms high-end
PCs by a factor ~ 1000. We also discuss the role of JANUS on other classes of
scientific applications.Comment: 11 pages, 6 figures. Improved version, largely rewritten, submitted
to Computing in Science & Engineerin
Facile high-yield synthesis and purification of lysine-modified graphene oxide for enhanced drinking water purification
Lysine-covalently modified graphene oxide (GO-Lys) was prepared by an innovative procedure. Lysine brushes promote enhanced adsorption of bisphenol A, benzophenone-4 and carbamazepine contaminants from tap water, with a removal capacity beyond the state of the art
Catching allergy by a simple questionnaire
Background: Identifying allergic rhinitis requires allergy testing, but the first-line referral for rhinitis are usually primary care physicians (PCP), who are not familiar with such tests. The availability of easy and simple tests to be used by PCP to suggest allergy should be very useful. Methods: The Respiratory Allergy Prediction (RAP) test, based on 9 questions and previously validated by a panel of experts, was evaluated in this study. Results: An overall number of 401 patients (48.6% males, age range 14-62 years) with respiratory symptoms was included. Of them, 89 (22.2%) showed negative results to SPT, while 312 (77.8%) had at least one positive result to SPT. Cohen's kappa coefficient showed that all questions had an almost perfect excellent agreement between pre and post-test. The algorithm of decision-tree growth Chi-squared Automatic Interaction Detector showed that answering yes to the question 4 (Your nasal/ocular complains do usually start or worsen during the spring?), 6 (Did you ever had cough or shortness of breath, even during exercise?) and 8 (Do you use nasal sprays frequently?) gave a probability to have a positive SPT of 85%. Conclusions: These findings show that RAP test can be proposed as an useful tool to be used by physician other than allergists when evaluating patients with rhinitis, suggesting the need of allergy testing
Defective graphene nanosheets for drinking water purification: Adsorption mechanism, performance, and recovery
Defect-rich graphene oxide (dGO) was used as sorbent for organic contaminants of emerging concern in tap water, including drugs and dyes, and the performance compared to those of lower-defects graphene types. The role of holes and carbonyl- carboxylic groups on graphene nanosheets surface on the adsorption mechanism and efficiency was investigated. dGO showed enhanced adsorption capacity toward two fluoroquinolone antibiotics (ofloxacin, OFLOX, and ciprofloxacin, CIPRO) in tap water with a maximum capacity of 650 mg/g, compared to 204 mg/g for Hummers derived commercial GO (hGO) and 125 mg/g for less defected Brodie derived GO (bGO) for OFLOX. The role of defects on the selective adsorption of OFLOX was also modelled by MD simulations, highlighting a mechanism mainly driven by the shape complementarity between the graphene holes and the molecules. Adsorption isotherms revealed different adsorption model for dGO, with a Langmuir fitting for dGO and BET fitting for all the other investigated samples. The maximum adsorption capacity of dGO for OFLOX was about six times higher than that of Granular Activated Carbon (95 mg/g), the industrial adsorption standard technology. Finally, it was also demonstrated that dGO can be recovered from treated water by ultrafiltration, this preventing secondary contamination risks and enabling safe use of graphene nanosheets for water purification
Implementation and performances of the IPbus protocol for the JUNO Large-PMT readout electronics
The Jiangmen Underground Neutrino Observatory (JUNO) is a large neutrino
detector currently under construction in China. Thanks to the tight
requirements on its optical and radio-purity properties, it will be able to
perform leading measurements detecting terrestrial and astrophysical neutrinos
in a wide energy range from tens of keV to hundreds of MeV. A key requirement
for the success of the experiment is an unprecedented 3% energy resolution,
guaranteed by its large active mass (20 kton) and the use of more than 20,000
20-inch photo-multiplier tubes (PMTs) acquired by high-speed, high-resolution
sampling electronics located very close to the PMTs. As the Front-End and
Read-Out electronics is expected to continuously run underwater for 30 years, a
reliable readout acquisition system capable of handling the timestamped data
stream coming from the Large-PMTs and permitting to simultaneously monitor and
operate remotely the inaccessible electronics had to be developed. In this
contribution, the firmware and hardware implementation of the IPbus based
readout protocol will be presented, together with the performances measured on
final modules during the mass production of the electronics
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