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Smart materials, which exhibit shape memory behavior in response to external stimuli, have shown great potential for use in biomedical applications. In this study, an energetic composite was fabricated using a UV-assisted DIW 3D printing technique and a shape memory material (SMP) as the binder. This composite has the ability to reduce the impact of external factors and adjust gun propellant combustion behavior. The composition and 3D printing process were delineated, while the internal structure and shape memory performance of the composite material were studied. The energetic SMP composite exhibits an angle of reversal of 18 s at 70°, with a maximum elongation typically reaching up to 280% of the original length and a recovery length of approximately 105% during ten cycles. Additionally, thermal decomposition and combustion behavior were also demonstrated for the energetic SMP composite.

Flood prediction in hilly regions, characterized by rapid flow rates and high destructive potential, remains a significant challenge. This study addresses this problem by introducing a novel machine learning-based approach to enhance flood forecast accuracy and lead time in small watersheds within hilly terrain. The study area encompasses small watersheds of approximately 600 km2. The proposed method analyzes spatiotemporal characteristics in rainfall dynamics to identify historical rainfall–flood events that closely resemble current patterns, effectively “learning from the past to predict the present”. The approach demonstrates notable precision, with an average error of 8.33% for peak flow prediction, 14.27% for total volume prediction, and a lead time error of just 1 h for peak occurrence. These results meet the stringent accuracy requirements for flood forecasting, offering a targeted and effective solution for flood forecasting in challenging hilly terrains. This innovative methodology deviates from conventional techniques by adopting a holistic view of rainfall trends, representing a significant advancement in addressing the complexities of flood prediction in these regions.

Objective. Fetal growth restriction (FGR) is a significant contributor to negative pregnancy and postnatal developmental outcomes. Currently, the exact pathological mechanism of FGR remains unknown. This study aims to utilize multiomics sequencing technology to investigate potential relationships among mRNA, gut microbiota, and metabolism in order to establish a theoretical foundation for diagnosing and understanding the molecular mechanisms underlying FGR. Methods. In this study, 11 healthy pregnant women and nine pregnant women with FGR were divided into Control group and FGR group based on the health status. Umbilical cord blood, maternal serum, feces, and placental tissue samples were collected during delivery. RNA sequencing, 16S rRNA sequencing, and metabolomics methods were applied to analyze changes in umbilical cord blood circulating mRNA, fecal microbiota, and metabolites. RT-qPCR, ELISA, or western blot were used to detect the expression of top 5 differential circulating mRNA in neonatal cord blood, maternal serum, or placental tissue samples. Correlation between differential circulating mRNA, microbiota, and metabolites was analyzed by the Spearman coefficient. Results. The top 5 mRNA genes in FGR were altered with the downregulation of TRIM34, DEFA3, DEFA1B, DEFA1, and QPC, and the upregulation of CHPT1, SMOX, FAM83A, GDF15, and NAPG in newborn umbilical cord blood, maternal serum, and placental tissue. The abundance of Bacteroides, Akkermansia, Eubacterium_coprostanoligenes_group, Phascolarctobacterium, Parasutterella, Odoribacter, Lachnospiraceae_UCG_010, and Dielma were significantly enriched in the FGR group. Metabolites such as aspartic acid, methionine, alanine, L-tryptophan, 3-methyl-2-oxovalerate, and ketoleucine showed notable functional alterations. Spearman correlation analysis indicated that metabolites like methionine and alanine, microbiota (Tyzzerella), and circulating mRNA (TRIM34, SMOX, FAM83A, NAPG) might play a role as mediators in the communication between the gut and circulatory system interaction in FGR. Conclusion. Metabolites (METHIONINE, alanine) as well as microbiota (Tyzzerella) and circulating mRNA (TRIM34, SMOX, FAM83A, NAPG) were possible mediators that communicated the interaction between the gut and circulatory systems in FGR.

A multi-layer design is applied to mitigate single event effect (SEE) in a 28 nm System-on-Chip (SoC). It depends on asymmetric multiprocessing (AMP), redundancy and system watchdog. Irradiation tests utilized 70 and 90 MeV proton beams to examine its performance through comparative analysis. Via examining SEEs in on-chip memory (OCM), compared with the trial without applying the multi-layer design, the test results demonstrate that the adopted multi-layer design can effectively mitigate SEEs in the SoC.

In this work, energetic composite composed of UV curable polyurethane acrylate and RDX was used as deterrent coating for 19-perforated nitroamine propellants plasticized by nitroglycerin and 1, 5-diazido-3-nitrazpentane (DIANP). The nitroamine propellant was end-sealed with the photocurable energetic composite material by using spraying and UV curing method. Combustion behaviors including burning progressivity and temperature sensitivity were studied by performing closed bomb test on propellants with 0.74%, 1.01% and 1.15% deterrent. The inner structure detection revealed that the deterrent penetrated into the perforations during coating process. The end-sealed propellant with blocked perforations exhibited inhibition of initial gas generation rate, which was demonstrated by dynamic vivacity curves. It is inspiring that the propellants coated with 1.01% and 1.15% deterrent presented excellent consistency according to the dynamic vivacity curves between 20 °C and 50 °C. Moreover. it can be indicated that the plugs in perforations conduced to temperature independence property of propellant under ambient temperature. This benefit contributes to improvement of the firing safety at high temperatures.

This work presents highly responsive gate-controlled p-GaN/AlGaN/GaN ultraviolet photodetectors (UVPDs) on Si substrates with a high-transmittance ITO gate. The two-dimensional electron gas (2DEG) in the quantum well of the polarized AlGaN/GaN heterojunction was efficiently depleted by the p-GaN gate, leading to a high photo-to-dark current ratio (PDCR) of 3.2 × 105. The quantum wells of the p-GaN/AlGaN and AlGaN/GaN heterojunctions can trap the holes and electrons excited by the UV illumination, thus efficiently triggering a photovoltaic effect and photoconductive effect, separately. Furthermore, the prepared photodetectors allow flexible adjustment of the static bias point, making it adaptable to different environments. Compared to traditional thin-film semi-transparent Ni/Au gates, indium tin oxide (ITO) exhibits higher transmittance. Under 355 nm illumination, the photodetector exhibited a super-high responsivity exceeding 3.5 × 104 A/W, and it could even exceed 106 A/W under 300 nm illumination. The well-designed UVPD combines both the advantages of the high-transmittance ITO gate and the structure of the commercialized p-GaN/AlGaN/GaN high-electron-mobility transistors (HEMTs), which opens a new possibility of fabricating large-scale, low-cost, and high-performance UVPDs in the future.

This paper introduces a new finding regarding single event upsets (SEUs) in configuration memory, and their potential impact on enhancing the performance of deep neural networks (DNNs) on the multiprocessor system on chip (MPSoC) platform. Traditionally, SEUs are considered to have negative effects on electronic systems or designs, but the current study demonstrates that they can also have positive contributions to the DNN on the MPSoC. The assertion that SEUs can have positive contributions to electronic system design was supported by conducting fault injections through dynamic reconfiguration on DNNs implemented on a 16nm FinFET technology Zynq UltraScale+ MPSoC. The results of the current study were highly significant, indicating that an SEU in configuration memory could result in an impressive 8.72% enhancement in DNN recognition on the MPSoC. One possible cause is that SEU in the configuration memory leads to slight changes in weight or bias values, resulting in improved activation levels of neurons and enhanced final recognition accuracy. This discovery offers a flexible and effective solution for boosting DNN performance on the MPSoC platform.

Energetic particle strikes the device and induces data corruption in the configuration memory (CRAM), causing errors and even malfunctions in a system on chip (SoC). Software-based fault injection is a convenient way to assess device performance. In this paper, dynamic partial reconfiguration (DPR) is adopted to make fault injection on a Xilinx 16 nm FinFET Ultrascale+ MPSoC. And the reconfiguration module implements the Sobel and Gaussian image filtering, respectively. Fault injections are executed on the static and reconfiguration modules' bitstreams, respectively. Another contribution is that the failure modes and effects analysis (FMEA) method is applied to evaluate the system reliability, according to the obtained injection results. This paper proposes a software-based solution to estimate programmable device vulnerability.

Abstract Traumatic brain injury (TBI) is a cause of disability and death worldwide, but there are currently no specific treatments for this condition. Release of excess reactive oxygen species (ROS) in the injured brain leads to a series of pathological changes; thus, eliminating ROS could be a potential therapeutic strategy. Herein, we synthesized insulin-incubated ultrasmall palladium (Pd@insulin) clusters via green biomimetic chemistry. The Pd@insulin clusters, which were 3.2 nm in diameter, exhibited marked multiple ROS-scavenging ability testified by the theoretical calculation. Pd@insulin could be rapidly excreted via kidney-urine metabolism and induce negligible adverse effects after a long-time treatment in vivo. In a TBI mouse model, intravenously injected Pd@insulin clusters aggregated in the injured cortex, effectively suppressed excessive ROS production, and significantly rescued motor function, cognition and spatial memory. We found that the positive therapeutic effects of the Pd@insulin clusters were mainly attributed to their ROS-scavenging ability, as they inhibited excessive neuroinflammation, reduced cell apoptosis, and prevented neuronal loss. Therefore, the ability of Pd@insulin clusters to effectively eliminate ROS, as well as their simple structure, easy synthesis, low toxicity, and rapid metabolism may facilitate their clinical translation for TBI treatment.

The development of a combination of chemo/photothermal therapy could overcome the limitations of single-modality therapy and enhance therapeutic efficacy. In this study, a pH/thermal dual-responsive multifunctional drug delivery system with dual-drug loading and enhanced chemo/photothermal therapy is developed based on polydopamine-coated mesoporous silica-gold nanorods (PDA-AuNRs@MSN). Nanoscale mesoporous silica-gold nanorods encapsulating doxorubicin (DOX) are designed as a core and then modified by polydopamine. The PDA shell not only conjugates with another anticancer bortezomib (Btz) to form pH-sensitive bond through boronic acid and catechol but also acts as a gatekeeper to control the release of doxorubicin and enhance the photothermal effect. Such a nanocarrier not only acts as a contrast agent for PA imaging but also serves as a therapeutic agent for enhanced chemo/photothermal therapy. The DOX and Btz could be released in an on-demand mode under near-infrared light irradiation and acid environment. The tumor size and location could be observed via PA imaging after intravenous injection into 4T1-bearing mice. Compared with AuNRs@MSN, PDA-AuNRs@MSN exhibit an increased near-infrared (NIR) absorption at 808 nm and an enhanced photothermal effect. The integrated D/B-PDA-AuNRs@MSN nanoparticles show higher cell apoptosis and enhanced tumor treatment efficacy in vitro and in vivo in comparison with single chemotherapy or photothermal therapy. Combined together, D/B-PDA-AuNRs@MSN show pH/thermal-responsive controlled-release and synergistic chemo/photothermal therapy for tumor.

Objective To study the annual financial expenditure in blood stations with different scales, and to establish the regression equation between blood collection units and total expenditure. Methods The annual total expenditure, the per capita cost of serving population, as well as the collection units of whole blood and apheresis platelet of 24 blood stations were collected. The financial expenditure required for collecting 10 000U blood was calculated.The statistical analysis was carried out with SPSS statistical software. Results From 2017 to 2020, the total annual financial expenditure of 24 blood stations showed an upward trend. The total expenditure among blood stations was different. The per capita cost of servicing population in the areas where the 24 blood stations were located had been increasing year by year. The 24 blood stations were divided into two grades according to the blood collection volume as 50 000 U, and the relationship equation between the blood collection volume and the annual total expenditure had been established. After testing, each equation was effective(P

Abstract Background Preeclampsia (PE) is a condition of high blood pressure that is usually concurrent with proteinuria in pregnancy. PE complicates the management of both maternal and fetal health and contributes to most adverse pregnancy outcomes, but the mechanism underlying the development of PE remains unclear. In this study, we performed a case-control study to compare the gut microbiota of PE (n = 26), abnormal placental growth (APG, n = 25) and healthy pregnant women (n = 28) and analyzed the potential pathogenic role of gut microbiota in PE progression. Results The clinical pathophysiological state did not affect the bacterial diversity, while the compositions of the gut microbiota were significantly altered in both the PE and APG groups compared with healthy pregnant women. At the phylum level, TM7 was significantly increased in women with APG. Heterogeneity was observed at the genus level, especially in genera with positive LDA scores, suggesting the stage-dependent effect of gut microbiota on the development of PE. The beneficial bacterium Lactobacillus was markedly depleted in the PE and APG groups but was only correlated with blood pressure (BP) and proteinuria levels in the PE group. Two different bacterial taxa belonged to Lactobacillus showed different correlations (OTU255 and OTU784 were significantly related to PE and APG, respectively). Conclusions Our results indicated that shifts in the gut microbiota might occur from the early stages of the development of PE, which is of possible etiological and therapeutic importance.

Understanding correlations between molecular structures and macroscopic properties is critical in realising highly efficient organic photovoltaics. Here, the authors conduct a comprehensive study based on four non-fullerene acceptors revealing how the extended conjugation, asymmetric terminals and alkyl chain length can affect device performance.

The bias temperature instability (BTI) effect of p-GaN gate high-electron-mobility transistors (HEMTs) is a serious problem for reliability. To uncover the essential cause of this effect, in this paper, we precisely monitored the shifting process of the threshold voltage (VTH) of HEMTs under BTI stress by fast sweeping characterizations. The HEMTs without time-dependent gate breakdown (TDGB) stress featured a high VTH shift of 0.62 V. In contrast, the HEMT that underwent 424 s of TDGB stress clearly saw a limited VTH shift of 0.16 V. The mechanism is that the TDGB stress can induce a Schottky barrier lowering effect on the metal/p-GaN junction, thus boosting the hole injection from the gate metal to the p-GaN layer. This hole injection eventually improves the VTH stability by replenishing the holes lost under BTI stress. It is the first time that we experimentally proved that the BTI effect of p-GaN gate HEMTs was directly dominated by the gate Schottky barrier that impeded the hole supply to the p-GaN layer.

The channel temperature distribution and breakdown points are difficult to monitor for the traditional p-GaN gate HEMTs under high power stress, because the metal gate blocks the light. To solve this problem, we processed p-GaN gate HEMTs with transparent indium tin oxide (ITO) as the gate terminal and successfully captured the information mentioned above, utilizing ultraviolet reflectivity thermal imaging equipment. The fabricated ITO-gated HEMTs exhibited a saturation drain current of 276 mA/mm and an on-resistance of 16.6 Ω·mm. During the test, the heat was found to concentrate in the vicinity of the gate field in the access area, under the stress of VGS = 6 V and VDS = 10/20/30 V. After 691 s high power stress, the device failed, and a hot spot appeared on the p-GaN. After failure, luminescence was observed on the sidewall of the p-GaN while positively biasing the gate, revealing the side wall is the weakest spot under high power stress. The findings of this study provide a powerful tool for reliability analysis and also point to a way for improving the reliability of the p-GaN gate HEMTs in the future.

Five particle sizes and six dosages of polymerized aluminum chloride (PAC) residue were taken to prepare polymerized aluminum chloride residue cement mortar (PACRM). The compressive and flexural strengths were tested, and SEM analysis was performed. The results showed that the change pattern of strength of PAC waste residue mixed into cement mortar was similar to that of fly ash at the same substitution rate. However, the strength of PACRM decreased with the increase of substitution rate. The flexural and compressive strengths of PACRM reached their peak at all ages after replacing cement with PAC waste residue with particle size of 0-0.075 mm and 30% doping. Their strength ratios were greater than 62%. It does not contribute much to the early strength development of PACRM, but contributes more to the later strength development after the cement is replaced by PAC waste residue. PAC waste residue mainly acts as microaggregate and fills into the mortar pores at low substitution rate. The cracks of the matrix structure are filled by C-S-H, so the mortar structure is more dense and the material strength is enhanced. When the substitution rate increases, the water requirement of mortar increases, resulting in an uncompact structure. The internal pores increase after hardening, and the mortar strength decreases rapidly.

The aim of this work is to develop a Geiger-Muller (GM) detector system for robot to look for a radioactive source in case of a nuclear emergency or in a high radiation environment. In order to find a radiation source easily, a detector system, including 3 detectors, was designed to search γ-ray radiation sources autonomously. First, based on GEANT4 simulation, radiation dose rates in 3 Geiger-Muller (GM) counters were simulated at different source-detector distances, distances between detectors and angles. Various sensitivity analyses were performed experimentally to verify the simulated designed detector system. A mono-energetic C137s γ-ray source with energy 662 keV and activity of 1.11 GBq was used for the observation. The simulated results were compared with the experimental dose rate values and good agreements were obtained for various cases. Only based on the dose rates in three detectors, the radiation source with a specific source activity and angle was localized in the different location. A method was adopted with the measured dose rates and differences of distances to find the actual location of the lost γ-ray source. The corresponding angles of deviation and detection limits were calculated to determine the sensitivity and abilities of our designed detector system. The proposed system can be used to locate radiation sources in low and high radiation environments.

Summary: Heat is crucial to the long-term stability of perovskite solar cells (PVSCs). Herein, thermal stability of PVSCs based on metal oxide (MO) and polymer (P) was investigated. Firstly, chemical decomposition behavior of perovskite films was characterized and analyzed, revealing that chemically active MO would accelerate the decomposition of methylamine lead iodide (MAPbI3). Secondly, thermal-induced stress, resulting from the mismatched thermal expansion coefficients of different layers of PVSCs, and its effect on the mechanical stability of perovskite films were studied. Combining experiment and simulation, we conclude that “soft” (low modulus) and thick (>20 nm) interfacial layers offer better relaxation of thermal-induced stress. As a result, PVSCs employing thick polymer interfacial layer offer a remarkably improved thermal stability. This work offers not only the degradation insight of perovskite films on different substrates but also the path toward highly thermal stable PVSCs by rational design of interfacial layers. : Energy Storage; Materials Characterization Techniques; Energy Materials; Devices Subject Areas: Energy Storage, Materials Characterization Techniques, Energy Materials, Devices

Abstract Magnetic resonance imaging (MRI) is a highly valuable diagnostic tool as it is a noninvasive technique that offers high spatial resolution. The use of contrast agents (CAs) can enhance the precision and specificity of MRI for disease diagnosis, but their imaging signals are “always on” regardless of whether they interact with target tissues or cells. Hence, a poor target‐to‐background signal ratio (TBR) is inevitably produced. In contrast, activatable CAs with high performance have been used to significantly improve the TBR, thus these CAs have also received extensive attention and undergone in‐depth research. In this review, we summarized the recent advances in design strategies and principles of activatable MR CAs, including ion conversion, self‐assembly, and disassembly. Additionally, we analyzed the advantages of these strategies in biomedical applications from in vitro biodetection to in vivo disease diagnosis compared to the outcomes of conventional MR CAs. Finally, we discussed the potential limitations, proposed solutions, and future perspectives of these activatable CAs.

Propellants are the main energy source in the internal ballistic process. The use of 3D printing has promised to produce propellants with complex geometries. However, due to the degraded energy properties of propellants using an inert binder, there is a critical need to develop a printable energetic resin. In this paper, a novel energetic acrylate-terminated poly–3–nitratomethyl–3–methyloxetane (APNIMMO) oligomer was prepared and characterized. The performance of a new composite propellant composed of APNIMMO and CL-20 (Hexanitrohexaazaisowurtzitane Dodecane) was also demonstrated. The new energetic printable resin and its composites are suitable for stereolithography (SLA) 3D printing, offering not only an improved thermodynamic energy, but also a substantially improved burn rate. Compared with the inert binder, the energetic binder offers the possibility to improve the thermodynamic energy by 15% and the burn rate at 100 MPa by 480% for 3D printed propellants.

Molecular quasiparticle and excitation energies determine essentially the spectral characteristics measured in various spectroscopic experiments. Accurate prediction of these energies has been rather challenging for ground-state density functional methods, because the commonly adopted density function approximations suffer from delocalization error. In this work, by presuming a quantitative correspondence between the quasiparticle energies and the generalized Kohn–Sham orbital energies, and employing a previously developed global scaling correction approach, we achieve substantially improved prediction of molecular quasiparticle and excitation energies. In addition, we also extend our previous study on temporary anions in resonant states, which are associated with negative molecular electron affinities. The proposed approach does not require any explicit self-consistent field calculation on the excited-state species, and is thus highly efficient and convenient for practical purposes.

Herein, we report a protocol for highly efficient hypervalent iodine (III) mediated, group-assisted purification (GAP) method for the regioselectivities and stereoselective aminochlorination of electron-deficient olefins. A series of vicinal chloramines with multifunctionalities were acquired in moderate to excellent yields (45–94%), by merely mixing the GAP auxiliary-anchored substrates with dichloramine T and tosylamide as chlorine/nitrogen sources and iodobenzene diacetate as a catalyst. The vicinal chloramines were obtained without any column chromatographic purification and recrystallization simply by washing the reaction mixture with a minimum amount of common inexpensive solvents and thus avoiding wastage of silica, solvents, time, and labor. The GAP auxiliary is recyclable and reusable. This strategy is easy to handle, cost-effective, greener, sustainable, environmentally benign, and mostly suitable for the syntheses of vicinal haloamines from various electron-deficient alkenes.

Gun propellant is the energy source of barrel weapons. A 3D printed gun propellant based on “Stereolithography (SLA)” was developed to overcome the limitation of traditional extrusion technologies. A demonstration formulation composed of 50 wt% 1,3,5-Trinitro-1,3,5-triazinane (RDX), 25 wt% epoxy acrylate, 12.5 wt% N-n-butyl-N-(2-nitroxyethyl) nitramine (Bu-NENA), 12.5 wt% reactive diluent and additives were fabricated. The 3D-printed propellants were characterized in terms of inner structure, mechanical strength and combustion behavior. Finally, a ballistic assessment of multi-perforated disk (MPD) propellant was carried out using a 30 mm test gun. The results showed that no signs of porosity or defects existed in the propellant printed by the SLA technique. The compression strength and tensile strength were 21.6 MPa and 7.3 MPa, respectively. The 3D-printed propellant exhibited a relatively low linear burn rate and a high pressure exponent value of 1.46. In the gun test, a muzzle velocity of 420 m/s was achieved without crushing the MPD.

Atmospheric CO2 can be transformed into valuable hydrocarbons by reaction with H2, but CO is the favoured kinetic product. Here, Liu and co-workers show that plasmonic rhodium nanoparticles not only reduce the activation energy for CO2hydrogenation, but also photo-selectively produce methane.

Effect of grain boundary microstructure, such as the spatial distribution and the connectivity of grain boundaries with different character, on the process of fatigue crack propagation in SUS430 ferritic stainless steel was investigated using the technique combined in-situ observations of crack propagation with EBSD measurements. The ratio of intergranular fracture to the overall fracture path increased with decreasing stress intensity factor range. Particularly, the ratio of intergranular fracture reached about 60 %, when the stress intensity factor range was less than 40 MPa m1/2. Moreover, the larger deflection of crack propagation occurred by the cyclic deformation at the higher stress intensity factor range more than 50 MPa m1/2, depending on the grain boundary microstructure. The intergranular fatigue cracks mainly propagated along random boundaries, and the deflection of intergranular crack path occurred at grain boundary triple junctions, owing to the further propagation along random boundary ahead. Moreover, when the fatigue crack propagation along random boundaries was inhibited by a triple junction composed of low-∑ CSL boundaries, the branching of fatigue crack occurred at a triple junction behind and the crack subsequently propagated along another random boundary. The propagation of fatigue crack was inhibited for a while by crossing low-∑ CSL boundaries and triple junctions. The possible grain boundary microstructure for control of fatigue crack propagation in SUS430 stainless steel was discussed based on the observed results.

The effect of grain boundary character and grain boundary geometrical configuration on nucleation of intergranular fatigue crack in SUS430 ferritic stainless steel was quantitatively investigated to reveal the elementary process of high cycle fatigue fracture. The grain boundary microstructure in the pre- and post-fatigued specimen was evaluated by scanning electron microscopy/ electron backscatter diffraction (SEM/EBSD) technique. Fatigue crack nucleation occurred mainly at grain boundaries at the low stress amplitude level. On the other hand, nucleated fatigue cracks were propagated immediately to perpendicular to the stress direction at the high stress amplitude level, regardless of the grain interior or grain boundaries. In the case of low stress amplitude level, intergranular fatigue cracks preferentially nucleated at high-angle random boundaries, although the fatigue cracks never nucleated at low-angle boundaries. Fatigue cracks nucleated at low-∑ coincidence site lattice (CSL) boundaries only when the trace of grain boundaries on the specimen surface was parallel to persistent slip bands (PSBs), although the fatigue cracking at random boundaries was accelerated even when the trace of grain boundary on the specimen surface was not parallel to PSBs in neighbouring grains. Fatigue crack nucleation was hardly affected by the geometrical arrangements between the trace of grain boundary on the specimen surface and the stress axis. The grain boundary engineering for control of intergranular fatigue cracking was discussed on the basis of the results of the grain boundary character-dependent intergranular fatigue crack nucleation.

Magnetic resonance imaging (MRI) has gained wide interest in early accurate diagnoses due to the high resolution and low toxicity of magnetic nanoparticles. In order to develop potential alternatives of toxic Gd- or Mn-based chelating agents, we report the synthesis of water soluble ultra-small Fe3O4 nanoparticles by a modified co-precipitation method as T1-weighted positive contrast agents. The magnetic iron oxide nanoparticles (MIONs) were functionalized by polymer ligand dodecanthiol-polymethacrylic acid (DDT-PMAA) to enhance their colloidal stability. These MIONs have high longitudinal relaxivity (r1 = 8.18 mM−1·S−1) and exhibited good results in the in vitro and in vivo MR imaging. No toxicity was observed in cytotoxicity assay and histology toxicity analysis. The MIONs@DDT-PMAA(magnetic iron oxide nanoparticles @ dodecanthiol-polymethacrylic acid) present great potential as positive contrast agents for tumor diagnosis.