Effects of exogenous hydrogen sulfide on brain metabolism and early neurological function in rabbits after cardiac arrest

Purpose

Some of the neuroprotective effects of hydrogen sulfide (H₂S) have been attributed to systemic hypometabolism and hypothermia. However, systemic metabolism may vary more dramatically than brain metabolism after cardiac arrest (CA). The authors investigated the effects of inhaled exogenous hydrogen sulfide on brain metabolism and neurological function in rabbits after CA and resuscitation.

Methods

Anesthetized rabbits were randomized into a sham group, a sham/H₂S group, a CA group, and a CA/H₂S group. Exogenous 80?ppm H₂S was administered to the sham/H₂S group and the CA/H₂S group which suffered 3?min of untreated CA by asphyxia and resuscitation. Effects on brain metabolism (cerebral extraction of oxygen (CEO₂), arterio-jugular venous difference of glucose [AJVD(glu)] and lactate clearance), S100B, viable neuron counts, neurological dysfunction score, and survival rate were evaluated.

Results

CEO₂, AJVD(glu), and lactate increased significantly after CA. Inhalation of 80?ppm H₂S significantly increased CEO₂ (25.04?±?7.11 vs. 16.72?±?6.12?%) and decreased AJVD(glu) (0.77?±?0.29 vs. 1.18?±?0.38?mmol/L) and lactate (5.11?±?0.43 vs. 6.01?±?0.64?mmol/L) at 30?min after resuscitation when compared with the CA group (all P?<?0.05). In addition, neurologic deficit scores, viable neuron counts, and survival rate were significantly better whereas S100B was decreased after H₂S inhalation.

Conclusions

The present study reveals that inhalation of 80?ppm H₂S reduced neurohistopathological damage and improves early neurological function after CA and resuscitation in rabbits. The increased CEO₂ and decreased AJVD(glu) and enhanced lactate clearance may be involved in the protective effects.     

An effective H2S sensor based on SnO2 nanowires decorated with NiO nanoparticles by electron beam evaporation

The highly toxic hydrogen sulphide (H₂S) present in air can cause negative effects on human health. Thus, monitoring of this gas is vital in gas leak alarms and security. Efforts have been devoted to the fabrication and enhancement of the H₂S-sensing performance of gas sensors. Herein, we used electron beam evaporation to decorate nickel oxide (NiO) nanoparticles on the surface of tin oxide (SnO₂) nanowires to enhance their H₂S gas-sensing performance. The synthesised NiO–SnO₂ materials were characterised by field-emission scanning electron microscopy, transmission electron microscopy and energy dispersive spectroscopy analysis. H₂S gas-sensing characteristics were measured at various concentrations (1–10 ppm) at 200–350 °C. The results show that with effective decoration of NiO nanoparticles, the H₂S gas-sensing characteristics of SnO₂ nanowires are significantly enhanced by one or two orders compared with those of the bare material. The sensors showed an effective response to low-level concentrations of H₂S in the range of 1–10 ppm, suitable for application in monitoring of H₂S in biogas and in industrial controls. We also clarified the sensing mechanism of the sensor based on band structure and sulphurisation process.

NiO nanoparticles decorated on the surface of the on-chip grown SnO₂ nanowires exhibited excellent response to highly toxic hydrogen sulphide (H₂S) in air.     

Oxygen deficit and H2S in hemorrhagic shock in rats

Introduction

Hemorrhagic shock induced O₂ deficit triggers inflammation and multiple organ failure (MOF). Endogenous H₂S has been proposed to be involved in MOF since plasma H₂S concentration appears to increase in various types of shocks and to predict mortality. We tested the hypothesis that H₂S increases during hemorrhagic shock associated with O₂ deficit, and that enhancing H₂S oxidation by hydroxocobalamin could reduce inflammation, O₂ deficit or mortality.

Methods

We used a urethane anesthetized rat model, where 25 ml/kg of blood was withdrawn over 30 minutes. O₂ deficit, lactic acid, tumor necrosis factor (TNF)-alpha and H₂S plasma concentrations (Siegel method) were measured before and after the bleeding protocol in control animals and animals that received 140 mg/kg of hydroxocobalamin. The ability to oxidize exogenous H₂S of the plasma and supernatants of the kidney and heart homogenates was determined in vitro.

Results

We found that withdrawing 25 ml/kg of blood led to an average oxygen deficit of 122 ± 23 ml/kg. This O₂ deficit was correlated with an increase in the blood lactic acid concentration and mortality. However, the low level of absorbance of the plasma at 670 nm (A₆₇₀), after adding N, N-Dimethyl-p-phenylenediamine, that is, the method used for H₂S determination in previous studies, did not reflect the presence of H₂S, but was a marker of plasma turbidity. There was no difference in plasmatic A₆₇₀ before and after the bleeding protocol, despite the large oxygen deficit. The plasma sampled at the end of bleeding maintained a very large ability to oxidize exogenous H₂S (high μM), as did the homogenates of hearts and kidneys harvested just after death. Hydroxocobalamin concentrations increased in the blood in the μM range in the vitamin B12 group, and enhanced the ability of plasma and kidneys to oxidize H₂S. Yet, the survival rate, O₂ deficit, H₂S plasma concentration, blood lactic acid and TNF-alpha levels were not different from the control group.

Conclusions

In the presence of a large O₂ deficit, H₂S did not increase in the blood in a rat model of untreated hemorrhagic shock. Hydroxocobalamin, while effective against H₂S in vitro, did not affect the hemodynamic profile or outcome in our model.     

Effects of Hydrogen-rich Saline on Rats with Acute Carbon Monoxide Poisoning

Background

Studies have shown that inhalation of hydrogen gas, which acts as an antioxidant, can protect the brain against free radicals in rats with ischemia-reperfusion. The neuronal damage caused by acute carbon monoxide (CO) poisoning is partly free radical mediated. We hypothesize that hydrogen may prevent neurological damage from CO poisoning.

Objectives

This study is designed to test whether hydrogen (H₂)-rich saline will have a protective effect on rats with acute CO poisoning.

Methods

Male Sprague-Dawley rats were subjected to CO poisoning. H₂-rich saline was administered by peritoneal injection (6 mL/kg/24 h). We used the Morris water maze and the open field test to determine cognitive function. After cognitive function studies, rats were decapitated and the levels of trace elements copper (Cu), zinc (Zn), and iron (Fe) in serum and brain were assessed by flame atomic absorption spectrometry. Necrosis, apoptosis, and autophagy of neurons were assessed by H-E staining and immunohistochemical staining in another group of rats.

Results

H₂-rich saline treatment improved the cognitive deficits and reduced the degree of necrosis, apoptosis, and cell autophagy in rats. Additionally, H₂-rich saline decreased the content of Fe in serum and brain in these rats, and increased the content of serum Cu related to free radical metabolism.

Conclusions

H₂-rich saline may effectively protect the brain from injury after acute CO poisoning. The mechanism of this protection may be related to lessening oxidative damage by affecting trace elements in vivo.     

Facile synthesis of size-controlled Fe2O3 nanoparticle-decorated carbon nanotubes for highly sensitive H2S detection

Hydrogen sulfide (H₂S) is one of the most plentiful toxic gases in a real-life and causes a collapse of the nervous system and a disturbance of the cellular respiration. Therefore, highly sensitive and selective H₂S gas sensor systems are becoming increasingly important in environmental monitoring and safety. In this report, we suggest the facile synthesis method of the Fe₂O₃ particles uniformly decorated on carbon nanotubes (Fe₂O₃@CNT) to detect H₂S gas using oxidative co-polymerization (pyrrole and 3-carboxylated pyrrole) and heat treatment. The as prepared Fe₂O₃@CNT-based sensor electrode is highly sensitive (as low as 1 ppm), selective and stable to H₂S gas at 25 °C, which shows promise for operating in medical diagnosis and environment monitoring. Excellent performance of the Fe₂O₃@CNT is due to the unique morphology of the nanocomposites made from uniformly dispersed Fe₂O₃ nanoparticles on the carbon surface without aggregation.

Fe₂O₃ uniformly dispersed on carbon nanotubes are synthesized using facile oxidative co-polymerization of monomers followed by heat treatment to apply electrode materials for a highly sensitive H₂S chemical sensor system.     

Dip-coating decoration of Ag2O nanoparticles on SnO2 nanowires for high-performance H2S gas sensors

SnO₂ nanowires (NWs) are used in gas sensors, but their response to highly toxic gas H₂S is low. Thus, their performance toward the effective detection of low-level H₂S in air should be improved for environmental-pollution control and monitoring. Herein, Ag₂O nanoparticle decorated SnO₂ NWs were prepared by a simple on-chip growth and subsequent dip-coating method. The amount of decorated Ag₂O nanoparticles on the surface of SnO₂ NWs was modified by changing the concentration of AgNO₃ solution and/or dipping times. Gas-sensing measurements were conducted at various working temperatures (200–400 °C) toward different H₂S concentrations ranging within 0.1–1 ppm. The selectivity of Ag₂O-decorated SnO₂ NW sensors for ammonia and hydrogen gases was tested. Results confirmed that the Ag₂O-decorated SnO₂ NW sensors had excellent response, selectivity, and reproducibility. The gas-sensing mechanism was interpreted under the light of energy-band bending by sulfurization, which converted the p–n junction into n–n, thereby significantly enhancing the sensing performance.

Ag₂O nanoparticles decorated on the surface of on-chip growth SnO₂ nanowires by a dip-coating method possessed excellent sensing performance for H₂S gas.     

A UiO-66 3D photonic crystal optical sensor for highly efficient chlorobenzene vapor detection

Chlorobenzene (C₆H₅Cl) is a flammable liquid with high vapor activity, which is a severe threat to the environment and human health. Therefore, it is essential to develop a highly efficient sensor to detect C₆H₅Cl vapor. Herein, we developed a UiO-66 three-dimensional photonic crystal (3D PC) optical sensor and investigated its sensing properties toward the C₆H₅Cl vapor. The UiO-66 3D PCs optical sensor shows a high sensitivity of C₆H₅Cl vapor, in the concentrations range of 0–500 ppm, the reflectance intensity response to be 0.06% ppm with a good linear relationship, detection limit can reach 1.64 ppm and the quality factor is 10.8. Additionally, the UiO-66 3D PC optical sensor demonstrated great selectivity with the values of selectivity (S) varying from 2.24 to 10.65 for the C₆H₅Cl vapor as compared with carbon tetrachloride (CCl₄), dichloromethane (CH₂Cl₂), 1,1,2-trichloroethane (C₂H₃Cl₃), benzene (C₆H₆), deionized water (H₂O), ethanol (C₂H₅OH) and methyl alcohol (CH₃OH) vapors. Moreover, the UiO-66 3D PC optical sensor shows an ultrafast optical response time and recovery times of 0.5 s and 0.45 s with exceptional stability and repeatability to 500 ppm C₆H₅Cl vapor. These excellent sensing properties are attributed to the efficacy of signal transduction, increased porosity and gas adsorption sites, which are intrinsically endowed by the design of the 3D optical structure. The design and fabrication of this UiO-66 3D PC optical sensor might open up potential applications for the detection of the C₆H₅Cl vapor.

Chlorobenzene (C₆H₅Cl) is a flammable liquid with high vapor activity, which is a severe threat to the environment and human health.     

Ultrasensitive detection of low-ppm H2S gases based on palladium-doped porous silicon sensors

In this study, the sensing properties of palladium-doped porous silicon (Pd/p-Si) substrates for low-ppm level detection of toxic H₂S gas are investigated. A Si substrate with dead-end pores ranging from nano- to macroscale was generated by a combined process of metal-assisted chemical etching (MacE) and electrochemical etching with tuned reaction time, in which nano-Pd catalysts were decorated by E-beam sputtering deposition. The sensing properties of the Pd/p-Si were enhanced as the thickness of the substrate layer increased; along with the resulting variation in surface area, this resulted in superior H₂S sensing performances in the low-ppm range (less than 3 ppm), with a detection limit of 300 ppb (sensitivity 30%) at room temperature. Furthermore, the sensor displayed excellent selectivity toward the hazardous H₂S molecules in comparison with various other reducing gases, including NO₂, CO₂, NH₃, and H₂, showing its potential for application in workplaces or environments affected by other toxic gases. The enhancement in sensing performance was possibly due to the increased dispersion and surface area of Pd nano-catalysts, which led to an increase in chemisorption sites of adsorbate molecules.

In this study, the sensing properties of palladium-doped porous silicon (Pd/p-Si) substrates for low-ppm level detection of toxic H₂S gas are investigated.     

Suspended animation inducer hydrogen sulfide is protective in an in vivo model of ventilator-induced lung injury

Purpose

Acute lung injury is characterized by an exaggerated inflammatory response and a high metabolic demand. Mechanical ventilation can contribute to lung injury, resulting in ventilator-induced lung injury (VILI). A suspended-animation-like state induced by hydrogen sulfide (H₂S) protects against hypoxia-induced organ injury. We hypothesized that suspended animation is protective in VILI by reducing metabolism and thereby CO₂ production, allowing for a lower respiratory rate while maintaining adequate gas exchange. Alternatively, H₂S may reduce inflammation in VILI.

Methods

In mechanically ventilated rats, VILI was created by application of 25 cmH₂O positive inspiratory pressure (PIP) and zero positive end-expiratory pressure (PEEP). Controls were lung-protective mechanically ventilated (13 cmH₂O PIP, 5 cmH₂O PEEP). H₂S donor NaHS was infused continuously; controls received saline. In separate control groups, hypothermia was induced to reproduce the H₂S-induced fall in temperature. In VILI groups, respiratory rate was adjusted to maintain normo-pH.

Results

NaHS dose-dependently and reversibly reduced body temperature, heart rate, and exhaled amount of CO₂. In VILI, NaHS reduced markers of pulmonary inflammation and improved oxygenation, an effect which was not observed after induction of deep hypothermia that paralleled the NaHS-induced fall in temperature. Both NaHS and hypothermia allowed for lower respiratory rates while maintaining gas exchange.

Conclusions

NaHS reversibly induced a hypometabolic state in anesthetized rats and protected from VILI by reducing pulmonary inflammation, an effect that was in part independent of body temperature.     

Inhalation of NO during myocardial ischemia reduces infarct size and improves cardiac function

Purpose

Bioactive NO carriers in circulating blood formed during NO inhalation selectively distribute blood flow to areas in need, and may thus improve collateral perfusion to the area-at-risk in acute myocardial infarction (AMI). Here, we tested the hypothesis that NO inhalation during the ischemic phase of AMI may improve left ventricular function and reduce infarct size in rats.

Methods

Following left anterior descending coronary artery (LAD) occlusion, rats received 50?ppm NO for 2?h of ischemia, during subsequent 3?h of reperfusion, or for 5?h of ischemia and reperfusion. Effects of inhaled NO were compared to those of intravenous nitrite as a putative carrier formed during NO inhalation. Downstream signaling via soluble guanylate cyclase was tested by inhibition with 1H-[1,2,4]oxadiazolo[4,3-a]quinoxalin-1-one (ODQ).

Results

NO inhalation during myocardial ischemia increased left ventricular systolic pressure, contractility, relaxation, and cardiac output, and reduced myocardial infarction size and area-at-risk as compared to untreated controls. NO inhalation during the reperfusion phase caused a comparable protective effect. Combined inhalation during ischemia and reperfusion did not further improve left ventricular hemodynamics, but had an additive protective effect on the myocardial area-at-risk. NO inhalation increased circulating nitrite levels, and mimicking of this effect by intravenous nitrite infusion achieved similar protection as NO inhalation during myocardial ischemia, while ODQ blocked the protective NO effect.

Conclusions

Inhalation of NO during myocardial ischemia improves left ventricular function and reduces infarct size by mechanisms that increase levels of circulating nitrite and involve soluble guanylate cyclase. NO inhalation may represent a promising early intervention in AMI.     

A highly sensitive ppb-level H2S gas sensor based on fluorophenoxy-substituted phthalocyanine cobalt/rGO hybrids at room temperature

The peripheral and non-peripheral substitution of 4-trifluoromethylphenoxy groups in the design of gas sensing phthalocyanine cobalt/reduced graphene oxide (rGO) hybrids with two different positions of the substituents was realized. Tetra-α(β)-(4-trifluoromethylphenoxy)phthalocyanine cobalt/reduced graphene oxide (3(4)-cF₃poPcCo/rGO) hybrids were prepared through noncovalent interaction, and were analyzed by FT-IR, UV-vis, TGA and SEM. The gas sensing performance of the cF₃poPcCo/rGO hybrid gas sensors towards ppb hydrogen sulfide (H₂S) was measured at room temperature. The results show that the 4-cF₃poPcCo/rGO sensor has better sensitivity, selectivity and reproducibility than the 3-cF₃poPcCo/rGO sensor, as well as a perfect linear response to the concentration of H₂S. For the 4-cF₃poPcCo/rGO sensor, the response sensitivity to 1 ppm H₂S is as high as 46.58, the response and recovery times are 600 s and 50 s for 1 ppm H₂S, and the detection limit is as low as 11.6 ppb. This is mainly due to the loose and porous structure of the cF₃poPcCo/rGO hybrids, the fact that graphene is an excellent conductive agent, and the fact that the electron-withdrawing capability of the trifluoromethyl group can increase the holes of rGO and PcCo. In addition, through electrochemical impedance spectroscopy (EIS) and I–V curves, and density functional theory, the influence of different positions of the substituents of cF₃poPcCo/rGO on the sensing performance and the sensing mechanism for improving sensitivity were discussed and confirmed in detail.

Highly sensitive gas sensing materials are of great importance for environmental pollution monitoring.     

A biotin-guided hydrogen sulfide fluorescent probe and its application in living cell imaging

Hydrogen sulfide (H₂S), a well-known signaling molecule, exerts significant regulatory effects on the cardiovascular and nervous systems. Therefore, monitoring the metabolism of H₂S offers a potential mechanism to detect various diseases. In addition, biotin is significantly used as a targeting group to detect cancer cells exclusively. In this work, a biotin-guided benzoxadizole-based fluorescent probe, NP-biotin, was developed for H₂S detection and evaluated in normal liver cell (LO2) and liver cancer cell (HepG2) lines. Results reveal that NP-biotin can detect cellular H₂S with high sensitivity and selectivity. Moreover, NP-biotin has been confirmed to possess the ability to target cancer cells under the guidance of the biotin group.

A biotin-guided hydrogen sulfide fluorescent probe has been shown clearly to possess the ability to target cancer cells.     

A highly selective and sensitive H2S sensor at low temperatures based on Cr-doped α-Fe2O3 nanoparticles

Cr-doped α-Fe₂O₃ nanoparticles were synthesized by a low-cost and environmentally friendly hydrothermal route. Their gas sensing properties were investigated and the sensor showed high sensitivity and selectivity to H₂S gas. Different Cr doping levels from 0 to 8.0 wt% were studied, and the sensor of 4.0 wt% Cr-doped α-Fe₂O₃ showed the largest response, with a response of 213 to 50 ppm H₂S at 100 °C. The incorporation of Cr ions within α-Fe₂O₃ nanocrystals increases the specific surface area, and promotes the oxidation of H₂S and oxygen adsorption in the air. Thus, the doping of Cr into α-Fe₂O₃ nanostructures would be a promising method for designing and fabricating high performance H₂S gas sensors.

Cr-doped α-Fe₂O₃ nanoparticles were synthesized by one-step hydrothermal reaction and showed high sensitivity and selectivity to H₂S at low temperature.     

High‐density lipoprotein from end‐stage renal disease patients exhibits superior cardioprotection and increase in sphingosine‐1‐phosphate

Background

Chronic kidney disease (CKD) exacerbates the risk of death due to cardiovascular disease (CVD). Modifications to blood lipid metabolism which manifest as increases in circulating triglycerides and reductions in high‐density lipoprotein (HDL) cholesterol are thought to contribute to increased risk. In CKD patients, higher HDL cholesterol levels were not associated with reduced mortality risk. Recent research has revealed numerous mechanisms by which HDL could favourably influence CVD risk. In this study, we compared plasma levels of sphingosine‐1‐phosphate (S1P), HDL‐associated S1P (HDL‐S1P) and HDL‐mediated protection against oxidative stress between CKD and control patients.

Methods

High‐density lipoprotein was individually isolated from 20 CKD patients and 20 controls. Plasma S1P, apolipoprotein M (apoM) concentrations, HDL‐S1P content and the capacity of HDL to protect cardiomyocytes against doxorubicin‐induced oxidative stress in vitro were measured.

Results

Chronic kidney disease patients showed a typical profile with significant reductions in plasma HDL cholesterol and albumin and an increase in triglycerides and pro‐inflammatory cytokines (TNF‐alpha and IL‐6). Unexpectedly, HDL‐S1P content (P = .001) and HDL cardioprotective capacity (P = .034) were increased significantly in CKD patients. Linear regression analysis of which factors could influence HDL‐S1P content showed an independent, negative and positive association with plasma albumin and apoM levels, respectively.

Discussion

The novel and unexpected observation in this study is that uremic HDL is more effective than control HDL for protecting cardiomyocytes against oxidative stress. It is explained by its higher S1P content which we previously demonstrated to be the determinant of HDL‐mediated cardioprotective capacity. Interestingly, lower concentrations of albumin in CKD are associated with higher HDL‐S1P.     

Tolerability and Pharmacokinetic Properties of Ciprofloxacin Dry Powder for Inhalation in Patients With Cystic Fibrosis: A Phase I,Randomized, Dose-Escalation Study

Background

Inhaled antibacterial agents are used to manage chronic pulmonary infections in cystic fibrosis (CF) and non-CF bronchiectasis. However, established nebulized preparations impose a substantial time burden on patients. A dry powder formulation of ciprofloxacin for inhalation (ciprofloxacin DPI) has been developed using PulmoSphere™ (Novartis, Pharma AG, Basel, Switzerland) technology (administered using a T-326 inhaler) to maximize antibacterial activity and convenience.

Objective

This study investigated the tolerability and pharmacokinetic properties of multiple-dose once-daily and twice-daily ciprofloxacin DPI in adults with CF.

Methods

A Phase I, randomized, single-blind, placebo-controlled, dose-escalation study in patients with CF (median age 29.0 years [19–40]), stable pulmonary status, and chronic Pseudomonas aeruginosa colonization. Sequential cohorts received ciprofloxacin DPI 32.5 mg qd (1 capsule for inhalation; n = 6), 65 mg qd (2 capsules for inhalation; n = 6), or 32.5 mg (n = 6) bid for 7 days. Each group was placebo controlled.

Results

Twenty-five patients were enrolled (12 men; median age, 29.0 years [range, 19–40 years]; 6, 6, 6, and 7 patients in the ciprofloxacin DPI 32.5 mg qd, 65 mg qd, and 32.5 mg bid and placebo groups, respectively). No serious treatment-emergent adverse events or clinically relevant changes in tolerability parameters, including lung function measurements, were reported. Twenty-one patients (ciprofloxacin, n = 17; placebo, n = 4) experienced 29 mild drug-related treatment-emergent adverse events, including bitter taste (ciprofloxacin, 17 patients; placebo, 2) and bronchospasm (ciprofloxacin, 3; placebo, 2). Ciprofloxacin DPI was absorbed rapidly after inhalation. Systemic exposure to ciprofloxacin was low and comparable between single and multiple dosing in all 3 dose groups, suggesting an absence of substantial drug accumulation. The geometric mean AUCs after the last dose were 0.383, 1.472, and 0.781 mg · h/L with ciprofloxacin DPI 32.5 mg qd, 65 mg qd, and 32.5 mg bid, respectively. The range of geometric mean t_½ in plasma was 3.4 to 9.5 hours. Sputum concentrations of ciprofloxacin were high, with substantial variability. Geometric mean ciprofloxacin concentrations (%CV) in induced sputum were 57.7 (118.2), 177.5 (53.4), and 149.7 (249.7) mg/L 0.75 hours after the last dose of ciprofloxacin DPI 32.5 mg qd, 65 mg qd, and 32.5 mg bid, respectively.

Conclusions

Ciprofloxacin DPI was well tolerated, especially with respect to lung function, with minimal systemic exposure compared with data from previous studies of oral and intravenous administration, and with no apparent accumulation at steady state. Sputum ciprofloxacin concentrations above 100-times the minimum inhibitory concentration for P aeruginosa were detected. Ciprofloxacin DPI may be effectively delivered to the lungs at microbiologically active concentrations while minimizing the risk for systemic intolerabilities. Eudra clinical trial identifier: 2006-003690-26.     

Efficient separation of rare earths recovered by a supported ionic liquid from bauxite residue leachate

Bauxite residue (BR) contains substantial concentrations of rare-earth elements (REEs), but their recovery is a challenge. Acidic BR leachates typically comprise much higher concentrations of base elements (g L⁻¹) than those of the REEs (ppm). Thus, adsorbents that are highly selective for the REEs over the base elements are required for the separation. The novel supported ionic liquid phase (SILP) betainium sulfonyl(trifluoromethanesulfonylimide) poly(styrene-co-divinylbenzene) [Hbet-STFSI-PS-DVB] was evaluated for the uptake of REEs (Sc, Y, Nd, Dy) in the presence of base elements (Ca, Al, Fe) from BR leachates. Breakthrough curves from acidic nitrate and sulfate media were investigated, as both HNO₃ and H₂SO₄ are commonly used for leaching of BR. The SILP exhibited a superior affinity for REEs in both media, except in the case of Sc(iii) from the sulfate feed. The recovery rates of the trace amounts of REEs from the real nitrate feed were remarkably high (71.7–100%) via a simple chromatography separation, without requiring complexing agents or a pretreatment for the removal of interfering elements. The REEs were purified from the base elements and separated into three sub-groups (scandium, light REEs and heavy REEs) by an optimized elution profile with H₃PO₄ and HNO₃ in a single chromatographic separation step.

Rare earths are separated from base metals in bauxite residue leachate by a supported ionic liquid phase.     

Synthesis and antibacterial activity of iron manganite (FeMnO3) particles against the environmental bacterium Bacillus subtilis

Nanocrystalline iron manganite powder was synthesized using the sol–gel combustion process, with glycine as fuel. It was further calcined at 900 °C for 8 h, resulting in the formation of a loose cubic FeMnO₃ powder with a small specific surface area, net-like structure and plate-like particles as confirmed by XRD, N₂ physisorption, FESEM and TEM analyses. The metal ion release was studied by ICP-OES and showed that less than 10 ppb of Fe or Mn ions were released by leaching in water, but 0.36 ppm Fe and 3.69 ppm Mn was found in LB (Luria–Bertani) bacterial medium. The generation of reactive oxygen species (ROS) was monitored in distilled water and bacterial medium and showed that FeMnO₃ particles do not generate O₂˙⁻ ions with or without UV irradiation, but synthesize H₂O₂ and show an antioxidative effect. Besides the higher stability of FeMnO₃ particles in aqueous solution they showed an inhibitory effect on Bacillus subtilis growth in LB medium even at low concentrations (0.01 mg ml⁻¹), but not in BHI medium even at 1 mg ml⁻¹. This study points out that the mechanism of antibacterial action of engineered metal oxides needs continued investigation and specific experimental controls.

Iron manganite (FeMnO₃) particles express antibacterial activity against Bacillus subtilis, together with H₂O₂ release and Fe, Mn-ion release in LB bacterial medium.     

Effect of histamine-2-receptor antagonists versus sucralfate on stress ulcer prophylaxis in mechanically ventilated patients: a meta-analysis of 10 randomized controlled trials

Introduction  

We conducted a meta-analysis in order to investigate the effect of histamine-2-receptor antagonists (H₂RA) versus sucralfate on stress ulcer prophylaxis in mechanically ventilated patients in the intensive care unit (ICU).     

Pd-loaded SnO2 hierarchical nanospheres for a high dynamic range H2S micro sensor

Herein, a high dynamic range H₂S micro gas sensor was achieved using hierarchical Pd-loaded SnO₂ nanostructures as a sensing material. SnO₂ nanospheres were synthesized using a hydrothermal method without any surfactants or templates, followed by Pd nanoparticle decoration via a facile method. A hierarchical nanostructure of Pd-loaded SnO₂ was formed, and its sensing abilities were compared with those of pure SnO₂ nanosphere-based sensors. The Pd-loaded SnO₂ hierarchical nanostructures showed an ultra-sensitive H₂S detection ability down to 10 ppb, a high dynamic range (4 orders of magnitude) up to 200 ppm, and a low working temperature (150 °C). Thus, this micro gas sensor based on Pd-loaded SnO₂ hierarchical nanostructures has promising applications in universal H₂S detection. The fabrication method presented herein is simple, renewable and operable and thus may be extended to synthesize other types of metal oxide-based semiconductor micro sensors for application in various fields.

The sensitivity of Pd-loaded SnO₂ nanosphere sensor to H₂S gas: micro gas sensors based on Pd-loaded SnO₂ nanospheres have credible gas detection abilities down to 10 ppb and 4 orders of magnitude concentration detection ranges.     

H2S detection at low temperatures by Cu2O/Fe2O3 heterostructure ordered array sensors

2D heterostructures are promising gas sensor materials due to their surface/interface effects and hybrid properties. In this research, Cu₂O/Fe₂O₃ heterostructure ordered arrays were synthesized using an in situ electrodeposition method for H₂S detection at low temperatures. These arrays possess a periodic long range ordered structure with horizontal multi-heterointerfaces, leading to superior gas sensitivity for synergistic effects at the heterointerfaces. The sensor based on the Cu₂O/Fe₂O₃ heterostructure ordered arrays exhibits a dramatic improvement in H₂S detection at low temperatures (even as low as −15 °C). The response is particularly significant at room and human body temperatures since the conductivity of the arrays can change by up to three orders of magnitude in a 10 ppm H₂S atmosphere. These good performances are also attributed to the formation of metallic Cu₂S conducting channels. Our results imply that the Cu₂O/Fe₂O₃ heterostructure ordered arrays are promising candidates for high-performance H₂S gas sensors that function at low temperatures as well as breath analysis systems for disease diagnosis.

Cu₂O/Fe₂O₃ heterostructure ordered arrays exhibit excellent H₂S sensitivity at low temperatures based on the mechanism of surface absorption/desorption and the sulphurization of Cu₂O.