We present a scalable and facile technique for noncovalent functionalization of graphene with 1-pyrenecarboxylic acid that exfoliates single-, few-, and multilayered graphene flakes into stable aqueous dispersions. The exfoliation mechanism is established using stringent control experiments and detailed characterization steps. Using the exfoliated graphene, we demonstrate highly sensitive and selective conductometric sensors (whose resistance rapidly changes >10,000% in saturated ethanol vapor), and ultracapacitors with extremely high specific capacitance (∼ 120 F/g), power density (∼ 105 kW/kg), and energy density (∼ 9.2 Wh/kg).

BackgroundMiddle East respiratory syndrome (MERS) is caused by a coronavirus (MERS‐CoV) and is characterized by hypoxemic respiratory failure. The objective of this study is to compare the outcomes of MERS-CoV patients before and after the availability of extracorporeal membrane oxygenation (ECMO) as a rescue therapy in severely hypoxemic patients who failed conventional strategies.MethodsWe collected data retrospectively on MERS-CoV patients with refractory respiratory failure from April 2014 to December 2015 in 5 intensive care units (ICUs) in Saudi Arabia. Patients were classified into two groups: ECMO versus conventional therapy. Our primary outcome was in-hospital mortality; secondary outcomes included ICU and hospital length of stay.ResultsThirty-five patients were included; 17 received ECMO and 18 received conventional therapy. Both groups had similar baseline characteristics. The ECMO group had lower in-hospital mortality (65 vs. 100%, P = 0.02), longer ICU stay (median 25 vs. 8 days, respectively, P < 0.01), and similar hospital stay (median 41 vs. 31 days, P = 0.421). In addition, patients in the ECMO group had better PaO2/FiO2 at days 7 and 14 of admission to the ICU (124 vs. 63, and 138 vs. 36, P < 0.05), and less use of norepinephrine at days 1 and 14 (29 vs. 80%; and 36 vs. 93%, P < 0.05).ConclusionsECMO use, as a rescue therapy, was associated with lower mortality in MERS patients with refractory hypoxemia. The results of this, largest to date, support the use of ECMO as a rescue therapy in patients with severe MERS-CoV.

BackgroundIntolerance to enteral nutrition is common in critically ill adults, and may result in significant morbidity including ileus, abdominal distension, vomiting and potential aspiration events. Prokinetic agents are prescribed to improve gastric emptying. However, the efficacy and safety of these agents in critically ill patients is not well-defined. Therefore, we conducted a systematic review and meta-analysis to determine the efficacy and safety of prokinetic agents in critically ill patients.MethodsWe searched MEDLINE, EMBASE, and Cochrane Library from inception up to January 2016. Eligible studies included randomized controlled trials (RCTs) of critically ill adults assigned to receive a prokinetic agent or placebo, and that reported relevant clinical outcomes. Two independent reviewers screened potentially eligible articles, selected eligible studies, and abstracted pertinent data. We calculated pooled relative risk (RR) for dichotomous outcomes and mean difference for continuous outcomes, with the corresponding 95 % confidence interval (CI). We assessed risk of bias using Cochrane risk of bias tool, and the quality of evidence using grading of recommendations assessment, development, and evaluation (GRADE) methodology.ResultsThirteen RCTs (enrolling 1341 patients) met our inclusion criteria. Prokinetic agents significantly reduced feeding intolerance (RR 0.73, 95 % CI 0.55, 0.97; P = 0.03; moderate certainty), which translated to 17.3 % (95 % CI 5, 26.8 %) absolute reduction in feeding intolerance. Prokinetics also reduced the risk of developing high gastric residual volumes (RR 0.69; 95 % CI 0.52, 0.91; P = 0.009; moderate quality) and increased the success of post-pyloric feeding tube placement (RR 1.60, 95 % CI 1.17, 2.21; P = 0.004; moderate quality). There was no significant improvement in the risk of vomiting, diarrhea, intensive care unit (ICU) length of stay or mortality. Prokinetic agents also did not significantly increase the rate of diarrhea.ConclusionThere is moderate-quality evidence that prokinetic agents reduce feeding intolerance in critically ill patients compared to placebo or no intervention. However, the impact on other clinical outcomes such as pneumonia, mortality, and ICU length of stay is unclear.Electronic supplementary materialThe online version of this article (doi:10.1186/s13054-016-1441-z) contains supplementary material, which is available to authorized users.

BackgroundThe relative efficacy and safety of proton pump inhibitors (PPIs) compared to histamine-2-receptor antagonists (H2RAs) should guide their use in reducing bleeding risk in the critically ill.MethodsWe searched the Cochrane library, MEDLINE, EMBASE, ACPJC, clinical trials registries, and conference proceedings through November 2015 without language or publication date restrictions. Only randomized controlled trials (RCTs) of PPIs vs H2RAs for stress ulcer prophylaxis in critically ill adults for clinically important bleeding, overt gastrointestinal (GI) bleeding, nosocomial pneumonia, mortality, ICU length of stay and Clostridium difficile infection were included. We used the Grading of Recommendations Assessment, Development and Evaluation (GRADE) approach to assess our confidence in the evidence for each outcome.ResultsIn 19 trials enrolling 2117 patients, PPIs were more effective than H2RAs in reducing the risk of clinically important GI bleeding (RR 0.39; 95 % CI 0.21, 0.71; P = 0.002; I2 = 0 %, moderate confidence) and overt GI bleeding (RR 0.48; 95 % CI 0.34, 0.66; P < 0.0001; I2 = 3 %, moderate confidence). PPI use did not significantly affect risk of pneumonia (RR 1.12; 95 % CI 0.86, 1.46; P = 0.39; I2 = 2 %, low confidence), mortality (RR 1.05; 95 % CI 0.87, 1.27; P = 0.61; I2 = 0 %, moderate confidence), or ICU length of stay (mean difference (MD), –0.38 days; 95 % CI –1.49, 0.74; P = 0.51; I2 = 30 %, low confidence). No RCT reported Clostridium difficile infection.ConclusionsPPIs were superior to H2RAs in preventing clinically important and overt GI bleeding, without significantly increasing the risk of pneumonia or mortality. Their impact on Clostridium difficile infection is yet to be determined.Electronic supplementary materialThe online version of this article (doi:10.1186/s13054-016-1305-6) contains supplementary material, which is available to authorized users.

The knowledge on the influence of surface roughness and the electron-phonon (el-ph) interaction on electrical transport properties of nanoscale metal films is important from both fundamental and technological points of view. Here we report a study of the temperature dependent electron transport properties of nanoscale copper films by measuring temperature dependent electrical resistivity with thickness ranging from 4 to 500 nm. We show that the residual resistivity, which is temperature independent, can be described quantitatively using both measured vertical surface root-mean-square roughness and lateral correlation length in the nanoscale, with no adjustable parameter, by a recent quasi-classical model developed by Chatterjee and Meyerovich (2010 Phys. Rev. B 81 245409-10). We also demonstrate that the temperature dependent component of the resistivity can be described using the Bloch-Grüneisen equation with a thickness dependent el-ph coupling constant and a thickness dependent Debye temperature. We show that the increase of the el-ph coupling constant with the decrease of film thickness gives rise to an enhancement of the temperature dependent component of the resistivity.

Electron phonon (el-ph) coupling is a fundamental quantity that controls the electron transport through a conductor. We experimentally determined the el-ph coupling strength of epitaxial copper (Cu) films ranging from 5 to 1000 nm thick using both ultra-fast, optical pump-probe reflectivity and temperature-dependent resistivity measurements. An enhancement of the el-ph coupling strength was observed when the thickness of the films was reduced to below 50 nm. We suggest that this unexpected enhancement of the el-ph coupling strength is partially responsible for the observed increase of resistivity in the films below 50 nm thick.

Acetylthio-protected free base porphyrins are used to form scanning tunneling microscope-molecular break junctions. The porphyrin molecules are deprotected in situ, before the self-assembly. Two types of molecular junctions are formed in the junctions: Au-S-Por-SAc-Au and Au-S-Por-S-Au. Lower conductance values and higher conductance values are observed. Computational modeling attributes the lower conductance to the Au-S-Por-SAc-Au junctions and the higher conductance to the Au-S-Por-S-Au junctions. First-principles calculation suggests that the reduced conductance in the protected porphyrin originates from the presence of the acetyl end groups (-COCH), rather than from the elongation of the sulfur-gold (S-Au) bonds at the tip-molecule interface.

This is an open access article under the terms of the Creat ive Commo ns Attri butio n-NonCo mmerc ial-NoDerivs License, which permits use and distribution in any medium, provided the original work is properly cited, the use is non-commercial and no modifications or adaptations are made.