[Effects of mechanical cardiopulmonary resuscitation during vertical spatial pre-hospital transport in patients with cardiac arrest: a historical cohort study].

OBJECTIVE: To analyze the effect of mechanical cardiopulmonary resuscitation (CPR) on patients with cardiac arrest with the vertical spatial pre-hospital emergency transport. METHODS: A retrospective cohort study was conducted. The clinical data of 102 patients with out-of-hospital cardiac arrest (OHCA) who were transferred to the emergency medicine department of Huzhou Central Hospital from the Huzhou Emergency Center from July 2019 to June 2021 were collected. Among them, the patients who performed artificial chest compression during the pre-hospital transfer from July 2019 to June 2020 served as the control group, and the patients who performed artificial-mechanical chest compression (implemented artificial chest compression first, and implemented mechanical chest compression immediately after the mechanical chest compression device was ready) during pre-hospital transfer from July 2020 to June 2021 served as the observation group. The clinical data of patients of the two groups were collected, including basic data (gender, age, etc.), pre-hospital emergency process evaluation indicators [chest compression fraction (CCF), total CPR pause time, pre-hospital transfer time, vertical spatial transfer time], and in-hospital advanced resuscitation effect evaluation indicators [initial end-expiratory partial pressure of carbon dioxide (PETCO2), rate of restoration of spontaneous circulation (ROSC), time of ROSC]. RESULTS: Finally, a total of 84 patients were enrolled, including 46 patients in the control group and 38 in the observation group. There was no significant difference in gender, age, whether to accept bystander resuscitation or not, initial cardiac rhythm, time-consuming pre-hospital emergency response, floor location at the time of onset, estimated vertical height, and whether there was any vertical transfer elevator/escalator, etc. between the two groups. In the evaluation of the pre-hospital emergency process, the CCF during the pre-hospital emergency treatment of patients in the observation group was significantly higher than that in the control group [69.05% (67.35%, 71.73%) vs. 61.88% (58.18%, 65.04%), P < 0.01], the total pause time of CPR was significantly shorter than that in the control group [s: 266 (214, 307) vs. 332 (257, 374), P < 0.05]. However, there was no significant difference in the pre-hospital transfer time and vertical spatial transfer time between the observation group and the control group [pre-hospital transfer time (minutes): 14.50 (12.00, 16.75) vs. 14.00 (11.00, 16.00), vertical spatial transfer time (s): 32.15±17.43 vs. 27.96±18.67, both P > 0.05]. It indicated that mechanical CPR could improve the CPR quality in the process of pre-hospital first aid, and did not affect the transfer of patients by pre-hospital emergency medical personnel. In the evaluation of the in-hospital advanced resuscitation effect, the initial PETCO2 of the patients in the observation group was significantly higher than that of the patients in the control group [mmHg (1 mmHg ≈ 0.133 kPa): 15.00 (13.25, 16.00) vs. 12.00 (11.00, 13.00), P < 0.01], the time of ROSC was significantly shorter than that in the control group (minutes: 11.00±3.25 vs. 16.64±2.54, P < 0.01), and the rate of ROSC was slightly higher than that in the control group (31.58% vs. 23.91%, P > 0.05). It indicated that continuous mechanical compression during pre-hospital transfer helped to ensure continuous high-quality CPR. CONCLUSIONS: Mechanical chest compression can improve the quality of continuous CPR during the pre-hospital transfer of patients with OHCA, and improve the initial resuscitation outcome of patients.

Revealing the growth of copper on polystyrene-block-poly(ethylene oxide) diblock copolymer thin films with in situ GISAXS.

Copper (Cu) as an excellent electrical conductor and the amphiphilic diblock copolymer polystyrene-block-poly(ethylene oxide) (PS-b-PEO) as a polymer electrolyte and ionic conductor can be combined with an active material in composite electrodes for polymer lithium-ion batteries (LIBs). As interfaces are a key issue in LIBs, sputter deposition of Cu contacts on PS-b-PEO thin films with high PEO fraction is investigated with in situ grazing-incidence small-angle X-ray scattering (GISAXS) to follow the formation of the Cu layer in real-time. We observe a hierarchical morphology of Cu clusters building larger Cu agglomerates. Two characteristic distances corresponding to the PS-b-PEO microphase separation and the Cu clusters are determined. A selective agglomeration of Cu clusters on the PS domains explains the origin of the persisting hierarchical morphology of the Cu layer even after a complete surface coverage is reached. The spheroidal shape of the Cu clusters growing within the first few nanometers of sputter deposition causes a highly porous Cu-polymer interface. Four growth stages are distinguished corresponding to different kinetics of the cluster growth of Cu on PS-b-PEO thin films: (I) nucleation, (II) diffusion-driven growth, (III) adsorption-driven growth, and (IV) grain growth of Cu clusters. Percolation is reached at an effective Cu layer thickness of 5.75 nm.

Establishment of a swine model of traumatic cardiac arrest induced by haemorrhage and ventricular fibrillation.

OBJECTIVE: To establish and evaluate a swine model of traumatic cardiac arrest (TCA) induced by haemorrhage and ventricular fibrillation. METHODS: Thirteen male pigs were divided into a sham group (n = 5) and TCA group (n = 8). Animals in the sham-operated group underwent intubation and monitoring but not haemorrhage and resuscitation, while animals in the TCA group underwent 40% blood volume haemorrhage over 20 min followed by 5 min of ventricular fibrillation and 5 min of cardiopulmonary resuscitation with fluid resuscitation. RESULTS: Restoration of spontaneous circulation was achieved in seven of eight animals in the TCA group. After resuscitation, the heart rate was significantly increased while the mean arterial pressure and ejection fraction were significantly decreased in the TCA group. The TCA group had significant cardiac and neurological injuries post-resuscitation and had higher serum creatinine and blood lactic acid levels and lower PaO2 than the sham group. Animals in the TCA group also exhibited significantly higher apoptotic indices and caspase-3 protein levels in the heart, brain and kidney than the sham group. CONCLUSION: Animals in this swine model of TCA exhibited high rates of successful resuscitation, significant vital organ injury and prolonged survival. The model is suitable for use in further TCA research.

Self-Assembly of Large Magnetic Nanoparticles in Ultrahigh Molecular Weight Linear Diblock Copolymer Films.

The development of diblock copolymer (DBC) nanocomposite films containing magnetic nanoparticles (NPs) with diameters (D) over 20 nm is a challenging task. To host large iron oxide NPs (Fe3O4, D = 27 ± 0.6 nm), an ultrahigh molecular weight (UHMW) linear DBC polystyrene-block-poly(methyl methacrylate) (PS-b-PMMA) is used as a template in the present work. Due to hydrogen bonding between the carboxylic acid ligands of the NPs and the ester groups in PMMA, the NPs show an affinity to the PMMA block. The localization of the NPs inside the DBC is investigated as a function of the NP concentration. At low NP concentrations, NPs are located preferentially at the interface between PS and PMMA domains to minimize the interfacial tension caused by the strong segregation strength of the UHMW DBC. At high NP concentrations (≥10 wt %), chain-like NP aggregates (a head-to-tail orientation) are observed in the PMMA domains, resulting in a change of the morphology from sphere to ellipsoid for part of the PMMA domains. Magnetic properties of the hybrid films are probed via superconducting quantum interference device magnetometry. All hybrid films show ferrimagnetism and are promising for potential applications in magnetic data storage.

Self-Assembly in ultrahigh molecular weight sphere-forming diblock copolymer thin films under strong confinement.

Ultrahigh molecular weight (UHMW) diblock copolymers (DBCs) have emerged as a promising template for fabricating large-sized nanostructures. Therefore, it is of high significance to systematically study the influence of film thickness and solvent vapor annealing (SVA) on the structure evolution of UHMW DBC thin films. In this work, spin coating of an asymmetric linear UHMW polystyrene-block-poly(methyl methacrylate) (PS-b-PMMA) DBC is used to fabricate thin films, which are spherically structured with an inter-domain distance larger than 150 nm. To enhance the polymer chain mobility and facilitate approaching equilibrium nanostructures, SVA is utilized as a post-treatment of the spin coated films. With increasing film thickness, a local hexagonal packing of PMMA half-spheres on the surface can be obtained, and the order is improved at larger thickness, as determined by grazing incidence small angle X-ray scattering (GISAXS). Additionally, the films with locally hexagonal packed half-spherical morphology show a poor order-order-poor order transition upon SVA, indicating the realization of ordered structure using suitable SVA parameters.

Printed Thin Diblock Copolymer Films with Dense Magnetic Nanostructure.

Thin hybrid films with dense magnetic structures for sensor applications are printed using diblock copolymer (DBC) templating magnetic nanoparticles (MNPs). To achieve a high-density magnetic structure, the printing ink is prepared by mixing polystyrene- block-poly(methyl methacrylate) (PS- b-PMMA) with a large PS volume fraction and PS selective MNPs. Solvent vapor annealing is applied to generate a parallel cylindrical film morphology (with respect to the substrate), in which the MNP-residing PS domains are well separated by the PMMA matrix, and thus, the formation of large MNP agglomerates is avoided. Moreover, the morphologies of the printed thin films are determined as a function of the MNP concentration with real and reciprocal space characterization techniques. The PS domains are found to be saturated with MNPs at 1 wt %, at which the structural order of the hybrid films reaches a maximum within the studied range of MNP concentration. As a beneficial aspect, the MNP loading improves the morphological order of the thin DBC films. The dense magnetic structure endows the thin films with a faster superparamagnetic responsive behavior, as compared to thick films where identical MNPs are used, but dispersed inside the minority domains of the DBC.

Role of Nickel Nanoparticles in High-Performance TiO2 /Ni/Carbon Nanohybrid Lithium/Sodium-Ion Battery Anodes.

Super-small sized TiO2 nanoparticles are in situ co-composited with carbon and nickel nanoparticles in a facile scalable way, using difunctional methacrylate monomers as solvent and carbon source. Good control over crystallinity, morphology, and dispersion of the nanohybrid is achieved because of the thermosetting nature of the resin polymer. The effects of the nickel nanoparticle on the composition, crystallographic phase, structure, morphology, tap density, specific surface area, and electrochemical performance as both lithium-ion and sodium-ion battery anodes are systematically investigated. It is found that the incorporation of the in situ formed nickel nanoparticles with certain content effectively enhances the electrochemical performance including reversible capacities, cyclic stability and rate performance as both lithium-ion and sodium-ion battery anodes. The experimental I-V profiles at different temperatures and theoretical calculations reveal that the charge carriers are accumulated in the amorphous carbon regions, which act as scattering centers to the carriers and lower the carrier mobility for the composite. With increasing nickel content, the mobility of the charge carriers is significantly increased, while the number of the charge carriers maintains almost constant. The nickel nanoparticles provide extra pathways for the accumulated charge, leading to reduced scatterings among the charge carriers and enhanced charge-carrier transportation.

The Effects of the Duration of Aortic Balloon Occlusion on Outcomes of Traumatic Cardiac Arrest in a Porcine Model.

Aortic balloon occlusion (ABO) facilitates the success of cardiopulmonary resuscitation (CPR) in non-traumatic cardiac arrest, and is also effective in controlling traumatic hemorrhage; however, a prolonged occlusion results in irreversible organ injury and death. In this study, we investigated the effects of ABO on CPR outcomes and its optimal duration for post-resuscitation organ protection in a porcine model of traumatic cardiac arrest (TCA).Twenty-seven male domestic pigs weighing 33 ±â€Š4 kg were utilized. Forty percent of estimated blood volume was removed within 20 min. The animals were then subjected to 5 min of untreated ventricular fibrillation and 5 min of CPR. Coincident with the start of CPR, the animals were randomized to receive either 30-min ABO (n = 7), 60-min ABO (n = 8) or control (n = 12). Meanwhile, fluid resuscitation was initiated by the infusion of normal saline with 1.5 times of hemorrhage volume in 1 h, and finished by the reinfusion of 50% of the shed blood in another 1 h. The resuscitated animals were monitored for 6 h and observed for an additional 18 h.During CPR, coronary perfusion pressure was significantly increased followed by a higher rate of resuscitation success in the 30 and 60-min ABO groups compared with the control group. However, post-resuscitation cardiac, neurologic dysfunction, and injuries were significantly milder accompanied with less renal and intestinal injuries in the 30-min ABO group than in the other two groups.In conclusion, ABO augmented the efficacy of CPR after TCA, and furthermore a 30-min ABO improved post-resuscitation cardiac and neurologic outcomes without exacerbating the injuries of kidney and intestine.

Multi-organ protection of ulinastatin in traumatic cardiac arrest model.

Background: Post-cardiac arrest syndrome, which has no specific curative treatment, contributes to the high mortality rate of victims who suffer traumatic cardiac arrest (TCA) and initially can be resuscitated. In the present study, we investigated the potential of ulinastatin to mitigate multiple organ injury after resuscitation in a swine TCA model. Methods: Twenty-one male pigs were subjected to hemodynamic shock (40% estimated blood loss in 20 min) followed by cardiac arrest (electrically induced ventricular fibrillation) and respiratory suspension for 5 min, and finally manual resuscitation. At 5 min after resuscitation, pigs were randomized to receive 80,000 U/kg ulinastatin (n = 7) or the same volume of saline (n = 9) in the TCA group. Pigs in the sham group (n = 5) were not exposed to bleeding or cardiac arrest. At baseline and at 1, 3, and 6 h after the return of spontaneous circulation, blood samples were collected and assayed for tumor necrosis factor-alpha, interleukin 6, and other indicators of organ injury. At 24 h after resuscitation, pigs were sacrificed and apoptosis levels were assessed in samples of heart, brain, kidney, and intestine. Results: One pig died in the ulinastatin group and one pig died in the TCA group; the remaining animals were included in the final analysis. TCA and resuscitation caused significant increases in multiple organ function biomarkers in serum, increases in tumor necrosis factor-alpha, and interleukin 6 in serum and increases in the extent of apoptosis in key organs. All these increases were lower in the ulinastatin group. Conclusion: Ulinastatin may attenuate multiple organ injury after TCA, which should be explored in clinical studies.

Magnetic nanoparticle-containing soft-hard diblock copolymer films with high order.

For sensor applications, superparamagnetic anisotropy is an indispensable property, which is typically achieved by employing an external field to guide the arrangement of magnetic nanoparticles (NPs). In the present investigation, the diblock copolymer polystyrene-block-poly(N-isopropylacrylamide) (PS-b-PNIPAM) is printed as a template to localize magnetic iron oxide NPs without any external field. Via microphase separation, cylindrical nanostructures of PS in a PNIPAM matrix are obtained, aligned perpendicular to the substrate. Since the magnetite NPs (Fe3O4) are functionalized with hydrophobic organic chains showing affinity to the PS blocks, they can selectively aggregate inside the PS cylinders. Moreover, solvent vapor annealing allows the achievement of nanostructures inside the hybrid system with a very high order, even at a high NP loading. Therefore, NPs can accumulate within PS domains to form perpendicularly aligned aggregates with high periodicity. The magnetic properties of the hybrid films are determined at various temperatures in two orthogonal directions (with PS cylinders vertical and parallel to the applied magnetic field). All hybrid films show superparamagnetism and a remarkable magnetic anisotropy is achieved at certain NP concentrations. This investigation shows a facile route to prepare superparamagnetic films with magnetic anisotropy and offers a novel possibility to future magnetic sensor fabrication.

Readily available titania nanostructuring routines based on mobility and polarity controlled phase separation of an amphiphilic diblock copolymer.

The amphiphilic diblock copolymer polystyrene-block-polyethylene oxide is combined with sol-gel chemistry to control the structure formation of blade-coated foam-like titania thin films. The influence of evaporation time before immersion into a poor solvent bath and polarity of the poor solvent bath are studied. Resulting morphological changes are quantified by scanning electron microscopy (SEM) and grazing incidence small angle X-ray scattering (GISAXS) measurements. SEM images surface structures while GISAXS accesses inner film structures. Due to the correlation of evaporation time and mobility of the polymer template during the phase separation process, a decrease in the distances of neighboring titania nanostructures from 50 nm to 22 nm is achieved. Furthermore, through an increase of polarity of an immersion bath the energetic incompatibility of the hydrophobic block and the solvent can be enhanced, leading to an increase of titania nanostructure distances from 35 nm to 55 nm. Thus, a simple approach is presented to control titania nanostructure in foam-like films prepared via blade coating, which enables an easy upscaling of film preparation.

Scalable in Situ Synthesis of Li4Ti5O12/Carbon Nanohybrid with Supersmall Li4Ti5O12 Nanoparticles Homogeneously Embedded in Carbon Matrix.

Li4Ti5O12 (LTO) is regarded as a promising lithium-ion battery anode due to its stable cyclic performance and reliable operation safety. The moderate rate performance originated from the poor intrinsic electron and lithium-ion conductivities of the LTO has significantly limited its wide applications. A facile scalable synthesis of hierarchical Li4Ti5O12/C nanohybrids with supersmall LTO nanoparticles (ca. 17 nm in diameter) homogeneously embedded in the continuous submicrometer-sized carbon matrix is developed. Difunctional methacrylate monomers are used as solvent and carbon source to generate TiO2/C nanohybrid, which is in situ converted to LTO/C via a solid-state reaction procedure. The structure, morphology, crystallinity, composition, tap density, and electrochemical performance of the LTO/C nanohybrid are systematically investigated. Comparing to the control sample of the commercial LTO composited with carbon, the reversible specific capacity after 1000 cycles at 175 mA g-1 and rate performance at high current densities (875, 1750, and 3500 mA g-1) of the Li4Ti5O12/C nanohybrid have been significantly improved. The enhanced electrochemical performance is due to the unique structure feature, where the supersmall LTO nanoparticles are homogeneously embedded in the continuous carbon matrix. Good tap density is also achieved with the LTO/C nanohybrid due to its hierarchical micro-/nanohybrid structure, which is even higher than that of the commercial LTO powder.

Si/Ag/C Nanohybrids with in Situ Incorporation of Super-Small Silver Nanoparticles: Tiny Amount, Huge Impact.

Silicon (Si) has been regarded as one of the most promising anodes for next-generation lithium-ion batteries (LIBs) due to its exceptional capacity, appropriate voltage profile, and reliable operation safety. However, poor cyclic stability and moderate rate performance have been critical drawbacks to hamper the practical application of Si-based anodes. It has been one of the central issues to develop new strategies to improve the cyclic and rate performance of the Si-based lithium-ion battery anodes. In this work, super-small metal nanoparticles (2.9 nm in diameter) are in situ synthesized and homogeneously embedded in the in situ formed nitrogen-doped carbon matrix, as demonstrated by the Si/Ag/C nanohybrid, where epoxy resin monomers are used as solvent and carbon source. With tiny amount of silver (2.59% by mass), the Si/Ag/C nanohybrid exhibits superior rate performance compared to the bare Si/C sample. Systematic structure characterization and electrochemical performance tests of the Si/Ag/C nanohybrids have been performed. The mechanism for the enhanced rate performance is investigated and elaborated. The temperature-dependent I-V behavior of the Si/Ag/C nanohybrids with tuned silver contents is measured. Based on the model, it is found that the super-small silver nanoparticles mainly increase charge carrier mobility instead of the charge carrier density in the Si/Ag/C nanohybrids. The evaluation of the total electron transportation length provided by the silver nanoparticles within the electrode also suggests significantly enhanced charge carrier mobility. The existence of tremendous amounts of super-small silver nanoparticles with excellent mechanical properties also contributes to the slightly improved cyclic stability compared to that of simple Si/C anodes.

Printed Thin Magnetic Films Based on Diblock Copolymer and Magnetic Nanoparticles.

Printing techniques have been well established for large-scale production and have developed to be effective in controlling the morphology and thickness of the film. In this work, printing is employed to fabricate magnetic thin films composed of polystyrene coated maghemite nanoparticles (γ-Fe2O3 NPs) and polystyrene-block-poly(methyl methacrylate) (PS-b-PMMA) diblock copolymer. By applying an external magnetic field during the print coating step, oriented structures with a high content of nanoscale magnetic particles are created. The morphology of the magnetic films and the arrangement of NPs within the polymer matrix are characterized with real and reciprocal space techniques. Due to the applied magnetic field, the magnetic NPs self-assemble into microscale sized wires with controlled widths and separation distances, endowing hybrid films with a characteristic magnetic anisotropy. At the nanoscale level, due to the PS coating, the NPs disperse as single particles at low NP concentrations. The NPs self-assemble into nanosized clusters inside the PS domains when the NP concentration increases. Due to a high loading of uniformly dispersed magnetic NPs across the whole printed film, a strong sensitivity to an external magnetic field is achieved. The enhanced superparamagnetic property of the printed films renders them promising candidate materials for future magnetic sensor applications.

Silicon Oxycarbide/Carbon Nanohybrids with Tiny Silicon Oxycarbide Particles Embedded in Free Carbon Matrix Based on Photoactive Dental Methacrylates.

A new facile scalable method has been developed to synthesize silicon oxycarbide (SiOC)/carbon nanohybrids using difunctional dental methacrylate monomers as solvent and carbon source and the silane coupling agent as the precursor for SiOC. The content (from 100% to 40% by mass) and structure (ratio of disordered carbon over ordered carbon) of the free carbon matrix have been systematically tuned by varying the mass ratio of methacryloxypropyltrimethoxysilane (MPTMS) over the total mass of the resin monomers from 0.0 to 6.0. Compared to the bare carbon anode, the introduction of MPTMS significantly improves the electrochemical performance as a lithium-ion battery anode. The initial and cycled discharge/charge capacities of the SiOC/C nanohybrid anodes reach maximum with the MPTMS ratio of 0.50, which displays very good rate performance as well. Detailed structures and electrochemical performance as lithium-ion battery anodes have been systematically investigated. The structure-property correlation and corresponding mechanism have been discussed.