Giant Carrier Mobility in a Room-Temperature Ferromagnetic VSi2N4 Monolayer.

Using density functional theory (DFT), we investigate that two possible phases of VSi2N4 (VSN) may be realized, one called the "H phase" corresponding to what is known from calculation and herein the other new "T phase" being stabilized by a biaxial tensile strain of 3%. Significantly, the H phase is predicted to display a giant carrier mobility of 1 × 106 cm2 V-1 s-1, which exceeds that for most 2D magnetic materials, with a Curie temperature (TC) exceeding room temperature and a band gap of 2.01 eV at the K point. Following the H-T phase transition, the direct band gap shifts to the Γ point and increases to 2.59 eV. The Monte Carlo (MC) simulations also indicate that TC of the T phase VSN can be effectively modulated by strain, reaching room temperature under a biaxial strain of -4%. These results show that VSN should be a promising functional material for future nanoelectronics.

Lithium Orbital Hybridization Chemistry to Stimulate Oxygen Redox with Reversible Phase Evolution in Sodium-Layered Oxide Cathodes.

Searching for high energy-density electrode materials for sodium ion batteries has revealed Na-deficient intercalation compounds with lattice oxygen redox as promising high-capacity cathodes. However, anionic redox reactions commonly encountered poor electrochemical reversibility and unfavorable structural transformations during dynamic (de)sodiation processes. To address this issue, we employed lithium orbital hybridization chemistry to create Na-O-Li configuration in a prototype P2-layered Na43/60Li1/20Mg7/60Cu1/6Mn2/3O2 (P2-NaLMCM') cathode material. That Li+ ions, having low electronegativity, reside in the transition metal slabs serves to stimulate unhybridized O 2p orbitals to facilitate the stable capacity contribution of oxygen redox at high state of charge. The prismatic-type structure evolving to an intergrowth structure of the Z phase at high charging state could be simultaneously alleviated by reducing the electrostatic repulsion of O-O layers. As a consequence, P2-NaLMCM' delivers a high specific capacity of 183.8 mAh g-1 at 0.05 C and good cycling stability with a capacity retention of 80.2% over 200 cycles within the voltage range of 2.0-4.5 V. Our findings provide new insights into both tailoring oxygen redox chemistry and stabilizing dynamic structural evolution for high-energy battery cathode materials.

Silicon Nanowire Array Weaved by Carbon Chains for Stretchable Lithium-Ion Battery Anode.

To manufacture flexible batteries, it can be a challenge for silicon base anode materials to maintain structural integrity and electrical connectivity under bending and torsion conditions. In this work, 1D silicon nanowire array structures combined with flexible carbon chains consisting of short carbon nanofibers (CNFs) and long carbon nanotubes (CNTs) are proposed. The CNFs and CNTs serve as chain joints and separate chain units, respectively, weaving the well-ordered Si nanowire array into a robust and integrated configuration. The prepared flexible and stretchable silicon array anode exhibits excellent electrochemical performance during dynamic operation. A high initial specific capacity of 2856 mAh g-1 is achieved. After 1000 cycles, a capacity retention of 60% (1602 mAh g-1) is maintained. Additionally, the capacity attenuation is less than 1% after 100 bending cycles. This excellent cycling stability is obtained with a high Si loading of 6.92 mg cm-2. This novel approach offers great promise for the development of high-loading flexible energy-storage devices.

First-principles predictions of room-temperature ferromagnetism in orthorhombic MnX2 (X = O, S) monolayers.

Two-dimensional ferromagnets with high spin-polarization at ambient temperature are of considerable interest because they might be useful for making nanoscale spintronic devices. We report that even though bulk phases of MnO2 are generally antiferromagnetic with low ordering temperatures, the corresponding MnO2 and MnS2 monolayers are ferromagnetic, and MnS2 is a high temperature half metallic ferromagnet. Based on first-principles calculations, we find that the MnO2 monolayer is an intrinsic ferromagnetic semiconductor with a Curie temperature TC of ∼300 K, while the half-metallic MnS2 monolayer has a remarkably high TC of ∼1150 K. Both compounds have substantial magnetocrystalline anisotropy, out of plane in the case of MnO2 monolayers, and in plane along the b-axis of orthorhombic MnS2 monolayer. Interestingly, a metal-insulator phase transition occurs in the MnS2 monolayer when the applied biaxial strain is beyond -2%. Tuning near this metal-insulator transition offers additional possibilities for devices. The present work shows that MnX2 (X = O, S) monolayers have the properties required for ultrathin nano-spintronic devices.

High-Flow Nasal Oxygen versus Conventional Nasal Cannula in Preventing Hypoxemia in Elderly Patients Undergoing Gastroscopy with Sedation: A Randomized Controlled Trial.

Background: We aimed to compare the prevention of hypoxemia using High-flow nasal oxygen (HFNO) or regular nasal tubing (CNC) in elderly patients undergoing gastroscopy with sedation. Methods: This study was a prospective, randomized, controlled trial conducted at a single center. We included elective patients aged 65 and above who were undergoing gastroscopy with sedation. In the intervention group (HFNO), we set the oxygen flow rate to 60 liters per minute with an oxygen fraction (FiO2) of 0.6, while in the control group (CNC), it was 6 liters per minute. The primary outcome was the occurrence of hypoxemia (defined as Spo2 < 90%). Results: A total of 125 participants were enrolled (HFNO group: n = 63; CNC group: n = 62). The occurrence of hypoxemia was found to be significantly lower in the HFNO group compared to the CNC group (3.2% vs. 22.6%, p = 0.001). Additionally, a significantly shorter duration of low oxygen levels was observed in the HFNO group [0.0 seconds (0.0-13.0)] compared to the CNC group [0.0 seconds (0.0-124.0), p<0.001]. Moreover, a higher minimum Spo2 value was achieved in the HFNO group [99.0% (98.0-100.0) vs. 96.5% (91.0-99.0), p < 0.001], and a shorter recovery time was recorded [0.5 minutes (0.0-0.5) vs. 0.5 minutes (0.0-1.0), p = 0.016] in comparison to the CNC group. There were no differences in terms of comfort level [0 (0-4) vs. 0 (0-5), p = 0.268] between the two groups. Conclusions: The HFNO system was determined to be a safe and highly effective method for oxygen delivery, leading to a reduction in the occurrence of hypoxemia in elderly patients undergoing gastroscopy with sedation. It is recommended that HFNO be considered as the standard approach for management in this population.

Predicting the structural, electronic and magnetic properties of few atomic-layer polar perovskite.

Density functional theory (DFT) calculations are performed to predict the structural, electronic and magnetic properties of electrically neutral or charged few-atomic-layer (AL) oxides based on polar perovskite KTaO3. Their properties vary greatly with the number of ALs (nAL) and the stoichiometric ratio. In the few-AL limit (nAL ≤ 14), the even AL (EL) systems with the chemical formula (KTaO3)n are semiconductors, while the odd AL (OL) systems with the formula Kn+1TanO3n+1 or KnTan+1O3n+2 are half-metal except for the unique KTa2O5 case which is a semiconductor due to the large Peierls distortions. After reaching a certain critical thickness (nAL > 14), the EL systems show ferromagnetic surface states, while ferromagnetism disappears in the OL systems. These predictions from fundamental complexity of polar perovskite when approaching the two-dimensional (2D) limit may be helpful for interpreting experimental observations later.

Fast Na+ Kinetics and Suppressed Voltage Hysteresis Enabled by a High-Entropy Strategy for Sodium Oxide Cathodes.

O3-type layered transition metal cathodes are promising energy storage materials due to their sufficient sodium reservoir. However, sluggish sodium ions kinetics and large voltage hysteresis, which are generally associated with Na+ diffusion properties and electrochemical phase transition reversibility, drastically minimize energy density, reduce energy efficiency, and hinder further commercialization of sodium-ion batteries (SIBs). Here, this work proposes a high-entropy tailoring strategy through manipulating the electronic local environment within transition metal slabs to circumvent these issues. Experimental analysis combined with theoretical calculations verify that high-entropy metal ion mixing contributes to the improved reversibility of redox reaction and O3-P3-O3 phase transition behaviors as well as the enhanced Na+ diffusivity. Consequently, the designed O3-Na0.9Ni0.2Fe0.2Co0.2Mn0.2Ti0.15Cu0.05O2 material with high-entropy characteristic could display a negligible voltage hysteresis (<0.09 V), impressive rate capability (98.6 mAh g-1 at 10 C) and long-term cycling stability (79.4% capacity retention over 2000 cycles at 5 C). This work provides insightful guidance in mitigating the voltage hysteresis and facilitating Na+ diffusion of layered oxide cathode materials to realize high-rate and high-energy SIBs.

Solid-State Lithium Batteries with Ultrastable Cyclability: An Internal-External Modification Strategy.

A commonly used strategy to tackle the unstable interfacial problem between Li1.3Al0.3Ti1.7(PO4)3 (LATP) and lithium (Li) is to introduce an interlayer. However, this strategy has a limited effect on stabilizing LATP during long-term cycling or under high current density, which is due in part to the negative impact of its internal defects (e.g., gaps between grains (GBs)) that are usually neglected. Here, control experiments and theoretical calculations show clearly that the GBs of LATP have higher electronic conductivity, which significantly accelerates its side reactions with Li. Thus, a simple LiCl solution immersion method is demonstrated to modify the GBs and their electronic states, thereby stabilizing LATP. In addition to LiCl filling, composite solid polymer electrolyte (CSPE) interlayering is concurrently introduced at the Li/LATP interface to realize the internal-external dual modifications for LATP. As a result, electron leakage in LATP can be strictly inhibited from its interior (by LiCl) and exterior (by CSPE), and such dual modifications can well protect the Li/LATP interface from side reactions and Li dendrite penetration. Notably, thus-modified Li symmetrical cells can achieve ultrastable cycling for more than 3500 h at 0.4 mA cm-2 and 1500 h at 0.6 mA cm-2, among the best cycling performance to date.

Recent advances in direct seawater splitting for producing hydrogen.

Hydrogen production from electrocatalytic water splitting driven by renewable energy sources provides a promising path for energy sustainability. The current water electrolysis technologies mainly use fresh water as feedstock, which will further aggravate the shortage of water resources in the world. Seawater has an innate advantage in large-scale electrolysis hydrogen production because of its abundant reserves. However, direct seawater electrolysis without any pre-treatment faces serious challenges due to the electrode side reactions and corrosion issues caused by the complex compositions of seawater. In this review, we first discuss the basic principles of seawater electrolysis. Second, the recent progress in designing efficient direct seawater electrolysis systems is discussed in detail, including catalyst design, electrolyser assembly, membrane regulation, and electrolyte engineering. In addition, the challenges and future opportunities are highlighted for the development of seawater splitting technologies toward large-scale hydrogen production.

Analysis of clinical risk factors associated with the prognosis of severe multiple-trauma patients with acute lung injury.

BACKGROUND: Several clinical risk factors have been reported to be associated with the prognosis of acute lung injury (ALI). However, these studies have included a general trauma patient population, without singling out the severely injured multiple-trauma patient population. OBJECTIVES: To identify the potential risk factors that could affect the prognosis of ALI in multiple-trauma patients and investigate the prognostic effects of certain risk factors among different patient subpopulations. METHODS: In this retrospective cohort study, severely injured multiple-trauma patients with early onset of ALI from several trauma centers were studied. Potential risk factors affecting the prognosis of ALI were examined by univariate and multivariate logistic analyses. RESULTS: There were 609 multiple-trauma patients with ALI admitted to the emergency department and emergency intensive care unit during the study period. The nine risk factors that affected prognosis, as indicated by the unadjusted odds ratios with 95% confidence intervals, were the APACHE II (Acute Physiology and Chronic Health Evaluation II) score, duration of trauma, age, gastrointestinal hemorrhage, pulmonary contusion, disseminated intravascular coagulation (DIC), multiple blood transfusions in 6 h, Injury Severity Score (ISS), and aspiration of gastric contents. Specific risk factors also affected different patient subpopulations in different ways. CONCLUSIONS: Patients older than 65 years and with multiple (> 10 units) blood transfusions in the early stage after multiple trauma were found to be independent risk factors associated with deterioration of ALI. The other factors studied, including pulmonary contusion, APACHE II score ≥ 20, ISS ≥ 16, gastrointestinal hemorrhage, and aspiration of gastric contents, may predict the unfavorable prognosis of ALI in the early stage of trauma, with their effects attenuating in the later stage. Duration of trauma ≥ 1 h and the presence of DIC may also indicate unfavorable prognosis during the entire treatment period.

Magnetism-induced topological transition in EuAs3.

The nature of the interaction between magnetism and topology in magnetic topological semimetals remains mysterious, but may be expected to lead to a variety of novel physics. We systematically studied the magnetic semimetal EuAs3, demonstrating a magnetism-induced topological transition from a topological nodal-line semimetal in the paramagnetic or the spin-polarized state to a topological massive Dirac metal in the antiferromagnetic ground state at low temperature. The topological nature in the antiferromagnetic state and the spin-polarized state has been verified by electrical transport measurements. An unsaturated and extremely large magnetoresistance of ~2 × 105% at 1.8 K and 28.3 T is observed. In the paramagnetic states, the topological nodal-line structure at the Y point is proven by angle-resolved photoemission spectroscopy. Moreover, a temperature-induced Lifshitz transition accompanied by the emergence of a new band below 3 K is revealed. These results indicate that magnetic EuAs3 provides a rich platform to explore exotic physics arising from the interaction of magnetism with topology.

Deformation measurements and material property estimation of mouse carotid artery using a microstructure-based constitutive model.

A series of pressurization and tensile loading experiments on mouse carotid arteries is performed with deformation measurements acquired during each experiment using three-dimensional digital image correlation. Using a combination of finite element analysis and a microstructure-based constitutive model to describe the response of biological tissue, the measured surface strains during pressurization, and the average axial strains during tensile loading, an inverse procedure is used to identify the optimal constitutive parameters for the mouse carotid artery. The results demonstrate that surface strain measurements can be combined with computational methods to identify material properties in a vascular tissue. Additional computational studies using the optimal material parameters for the mouse carotid artery are discussed with emphasis on the significance of the qualitative trends observed.

First-principles prediction of a room-temperature ferromagnetic and ferroelastic 2D multiferroic MnNX (X = F, Cl, Br, and I).

Two-dimensional (2D) multiferroic materials have great potential applications in multifunctional nanoelectronics devices. Here, we construct a series of stable and isolated monolayers as 2D manganese nitrohalides MnNX (X = F, Cl, Br, and I) and systematically investigate the structural, electronic and magnetic properties using first-principles and Monte Carlo simulations. We find that ground states simultaneously show in-plane ferroelasticity and room-temperature ferromagnetic properties. We also reveal that the in-plane magnetic anisotropy can be tunable by the uniaxial ferroelastic strain. Our results will provide significant implications for future experiments and the design of new functional materials at the nanoscale.

Persistent Spin-texture and Ferroelectric Polarization in 2D Hybrid Perovskite Benzylammonium Lead-halide.

Density functional theory calculations were performed for the electronic and the ferroelectric properties of the bulk and the monolayer benzylammonium lead-halide (BA2PbCl4). Our calculations indicate that both the bulk and monolayer systems display a band gap of ∼3.3 eV (HSE06+SOC) and a spontaneous polarization of ∼5.4 µC/cm2. The similar physical properties of bulk and monolayer systems suggest a strong decoupling among the layers in this hybrid organic-inorganic perovskite. Both the ferroelectricity, through associated structure distortion, and the spin-orbit coupling, through splitting induced in the electronic bands, significantly influence the band gaps. Most importantly, we found for the first time in a two-dimensional hybrid organic-inorganic class of material, a peculiar spin texture topology such as a unidirectional spin-orbit field, which may lead to a protection against spin decoherence.

Penehyclidine hydrochloride attenuates LPS-induced acute lung injury involvement of NF-kappaB pathway.

To investigate the protective effects of penehyclidine hydrochloride (PHC) in lipopolysaccharide (LPS)-induced acute lung injury (ALI) and the underlying molecular mechanism. ALI was induced by intravenous injection of LPS (5mg/kg). Male Sprague-Dawley (SD) rats challenged with or without LPS were pretreated with varied doses of PHC 0.5h before injection of LPS or saline. Blood gas in arterial blood, lung weight gain, bronchoalveolar lavage fluid (BALF), and neutrophils sequestration were examined 6h after administration of LPS. Pathological changes of lung tissue were measured by light microscopy. Phosphorylation of mitogen-activated protein kinase (MAPK) family and NF-kappaB were detected by western blot. All animals demonstrated drops in arterial oxygen tension (PaO(2)) after LPS application, which were significantly reversed by PHC pretreatment. Administration of PHC reduced lung water gain, bronchoalveolar lavage protein content, infiltration of neutrophils, malondialdehyde (MDA) content, and lactate dehydrogenase (LDH) activity and enhanced superoxide dismutase (SOD) activity. Histopathological study also indicated that PHC treatment markedly attenuated lung histopathological changes, alveolar hemorrhage, and inflammatory cells infiltration with evidence of decreasing of myeloperoxidase (MPO) activity. Furthermore, p38MAPK, ERK, and NF-kappaB were activated in 6h after LPS treatment, which could be blunted by PHC, while JNK remained unchanged. These findings confirmed significant protection by PHC against LPS-induced lung vascular leak and inflammation and implicated inhibition of p38MAPK activation signaling a potential role for PHC in the management of ALI.

Risk factors for urban road traffic injuries in Hangzhou, China.

OBJECTIVE: To investigate factors that most influence urban road traffic injuries (RTI) mortality and morbidity. METHODS: The study used linked police and hospital records of RTI patients in the city of Hangzhou during the 3-year period 2004-2006. Three RTI outcome groups were included: (1) fatally injured; (2) severely injured; and (3) mildly injured persons. RESULTS: High risks for fatal road traffic accidents (RTA) were found on urban links, over weekend, during night hours, in male drivers who drove old vehicles without using seat belts, and at exceeding speeds, or with night time accidents and bad weather condition. In case of higher risk for all urban road users on urban junctions, the numbers on mildly injury cases were increasing. The highest combined risk for dying or being severely injured was found in male drivers driving at excessive speed, on urban links, and with night time accidents. CONCLUSIONS: Intensifying safety education of motor vehicle drivers, enhancing traffic management and keeping balance of "person-vehicle-road" system will greatly reduce the urban traffic accidents and casualties.

[Analysis of clinical risk factors in progression from acute lung injury to acute respiratory distress syndrome in severe trauma patients].

OBJECTIVES: To investigate the potential risk factors of affecting progression from acute lung injury (ALI) to acute respiratory distress syndrome in severe trauma population. METHODS: Twenty potential risk factors of affecting progression of acute lung injury were examined by univariate and multivariate logistic analyses among the severe trauma patients in a retrospective study. RESULTS: All of 375 specially severe trauma patients with ALI were included for analysis. The six risk factors that affected the progression from acute lung injury to acute respiratory distress syndrome were sepsis, duration of trauma, APACHE II score, DIC, aspiration of gastric contents, and advanced age. Specific risk factors also affected different patient subpopulations at different degrees. CONCLUSION: Impact of sepsis, DIC and duration of trauma that predict progression of ALI exists throughout the entire treatment period while aspiration of gastric contents and APACHE II score might affect aggravation of ALI only during the early period; due to deterioration of pulmonary function and severely traumatic injury, advanced age is still an independent risk factor; patients with these risk factors need aggressive supportive cares as early as possible in order to prevent further aggravations.

The analysis of risk factors of impacting mortality rate in severe multiple trauma patients with posttraumatic acute respiratory distress syndrome.

OBJECTIVE: We hypothesize that not all of the traditional risk factors of impacting mortality rate in commonly traumatic populations with posttraumatic acute respiratory distress syndrome (ARDS) are independently associated with those patient populations identified with severe multiple trauma. Rather, we postulate that there may exist significantly different impacting degrees of specific risk factors in stratified patients (surviving beyond 24 and 96 hours)--more severe multiple trauma with higher injury score and long-term mechanical ventilation as well. METHODS: This is a retrospective cohort study regarding trauma as a single cause for emergency intensive care unit admission. Twenty-two items of potential risk factors of impacting mortality rate were calculated by univariate and multivariate logistic analyses to find distinctive items in these severe multiple trauma patients. RESULTS: The unadjusted odds ratio and 95% confidence intervals of mortality rate were found to be associated with 6 (out of 22) risk factors, namely, (1) Acute Physiology and Chronic Health Evaluation II score, (2) duration of trauma factor, (3) aspiration of gastric contents, (4) sepsis, (5) pulmonary contusion, and (6) duration of mechanical ventilation. Significant results also appeared in stratified patients. CONCLUSIONS: Impact of pulmonary contusion and Acute Physiology and Chronic Health Evaluation II score contributing to prediction of mortality may exist in the early phase after trauma. Sepsis is still a vital risk factor referring to systemic inflammatory response syndrome, infection, secondary multiple organ dysfunction, etc. Discharging trauma factors as early as possible becomes the critical therapeutic measure. Aspiration of gastric contents in emergency intensive care unit admission could lead to incremental mortality rate due to aspiration pneumonia. Long-standing mechanical ventilation should be constrained because it is likely to cause severe refractory complications.

Risk factors of mortality in road traffic injury patients with acute respiratory distress syndrome.

BACKGROUND: Among the deaths due to trauma, about one half of the patients suffer from road traffic injury (RTI). Most of RTI patients complicate acute respiratory distress syndrome (ARDS) and severe multiple injuries. ARDS is a major contributor to morbidity and mortality in trauma patients. Although many injuries and conditions are believed to be associated with ARDS independent risk factors in trauma patients, their relative importance in development of the syndrome are undefined. We hypothesize that not all of the traditional risk factors impacting mortality are independently associated with patients strictly identified by traffic injury. This study aimed to sieve distinctive risk factors in our RTI population, meanwhile, we also hypothesize that there may exist significantly different risk factors in these patients. METHODS: This was a retrospective cohort study regarding RTI as a single cause for emergency intensive care unit (EICU) admission. Patients identified as severe RTI with post-traumatic ARDS were enrolled in a prospectively maintained database between May 2002 and April 2007 and observed. Twenty-three items of potential risk impacting mortality were calculated by univariate and multivariate Logistic analyses in order to find distinctive items in these severe RTI patients. RESULTS: There were 247 RTI patients with post-traumatic ARDS admitted to EICU during the study period. The unadjusted odds ratio (OR) and 95% confidence intervals (CI) of mortality were associated with six risk factors out of 23: APACHE II score, duration of trauma factor, pulmonary contusion, aspiration of gastric contents, sepsis and duration of mechanical ventilation. The adjusted ORs with 95% CI were denoted with respect to surviving beyond 96 hours EICU admission (APACHE II score, duration of trauma factor, aspiration of gastric contents), APACHE II score beyond 20 EICU admission (duration of trauma factor, sepsis, duration of mechanical ventilation) and mechanical ventilation beyond 7 days EICU admission (duration of trauma factor and sepsis). CONCLUSIONS: We have retrospectively demonstrated an adverse effect of six different risk factors out of 23 items in mortality of post-traumatic ARDS within severe RTI patients and, moreover, gained distinct outcomes in stratified patients under real emergency trauma circumstance. An impact of APACHE II score and pulmonary contusion contributing to prediction of mortality may exist in prophase after traffic injury. Sepsis is still a vital risk factor referring to systemic inflammatory response syndrome, infection, and secondary multiple organs dysfunction. Eliminating trauma factors as early as possible becomes the critical therapeutic measure. Aspiration of gastric contents could lead to incremental mortality due to severe ventilation associated pneumonia. Long-standing mechanical ventilation should be constrained on account of severe refractory complications.

Comparison of the new injury severity score and the injury severity score in multiple trauma patients.

OBJECTIVE: To assess whether these characteristics of less misclassification and greater area under receiver operator characteristic (ROC) curve of the new injury severity score (NISS) are better than the injury severity score (ISS) as applying it to our multiple trauma patients registered into the emergency intensive care unit (EICU). METHODS: This was a retrospective review of registry data from 2 286 multiple trauma patients consecutively registered into the EICU from January 1,1997 to December 31, 2006 in the Second Affiliated Hospital, Medical School of Zhejiang University in China. Comparisons between ISS and NISS were made using misclassification rates, ROC curve analysis, and the H-L statistics by univariate and multivariate logistic progression model. RESULTS: Among the 2 286 patients, 176 (7.7%) were excluded because of deaths on arrival or patients less than 16 years of age. The study population therefore comprised 2 110 patients. Mean EICU length of stay (LOS) was 7.8 days ?2.4 days. Compared with the blunt injury group, the penetrating injury group had a higher percentage of male, lower mean EICU LOS and age. The most frequently injured body regions were extremities and head/neck, followed by thorax, face and abdomen in the blunt injury group; whereas, thorax and abdomen were more frequently seen in the penetrating injury group. The minimum misclassification rate for NISS was slightly less than ISS in all groups (4.01% versus 4.49%). However, NISS had more tendency to misclassify in the penetrating injury group. This, we noted, was attributed mainly to a higher false-positive rate (21.04% versus 15.55% for ISS, t equal to 3.310, P less than 0.001), resulting in an overall misclassification rate of 23.57% for NISS versus 18.79% for ISS (t equal to 3.290, P less than 0.001). In the whole sample, NISS presented equivalent discrimination (area under ROC curve: NISS equal to 0.938 versus ISS equal to 0.943). The H-L statistics showed poorer calibration (48.64 versus 32.11, t equal to 3.305, P less than 0.001) in the penetrating injury group. CONCLUSIONS: NISS should not replace ISS because they share similar accuracy and calibration in predicting multiple blunt trauma patients. NISS may be more sensitive but less specific than ISS in predicting mortality in certain penetrating injury patients.