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Introduction Cycling is associated with a greater risk of traumatic brain injury (TBI) than other recreational activities. This study aimed to investigate the epidemiology of sports-related TBI in Hong Kong and to examine predictors for recreational cycling-induced intracranial haemorrhage. Methods This retrospective multicentre study included patients diagnosed with sports-related TBI in public hospitals in Hong Kong from 2015 to 2019. Computed tomography scans were reviewed by an independent assessor. The primary endpoint was traumatic intracranial haemorrhage. The secondary endpoint was an unfavourable Glasgow Outcome Scale (GOS) score at discharge from hospital. Results In total, 720 patients were hospitalised with sports-related TBI. The most common sport was cycling (59.2%). The crude incidence of cycling-related TBI was 1.1 per 100 000 population. Cyclists were more likely to exhibit intracranial haemorrhage and an unfavourable GOS score, compared with patients who had TBI because of other sports. Although 47% of cyclists had intracranial haemorrhage, only 15% wore a helmet. In multivariate analysis, significant predictors for intracranial haemorrhage were age ≥60 years, antiplatelet medication, moderate or severe TBI, and skull fracture. Among 426 cyclists, 375 (88%) had mild TBI, and helmet wearing was protective against intracranial haemorrhage, regardless of age, antiplatelet medication intake, and mechanism of injury. Of 426 cyclists, 31 (7.3%) had unfavourable outcomes on discharge from hospital. Conclusions The incidence of sports-related TBI is low in Hong Kong. Although cycling-related head injuries carried greater risks of intracranial haemorrhage and unfavourable outcomes compared with other sports, most cyclists experienced good recovery. Helmet wearing among recreational cyclists with mild TBI was protective against intracranial haemorrhage and skull fracture.

Topological spin textures can be found in both two-dimensional and three-dimensional nanostructures, which are of great importance to advanced spintronic applications. Here we report the current-induced skyrmion tube dynamics in three-dimensional synthetic antiferromagnetic (SyAF) bilayer and multilayer nanostructures. It is found that the SyAF skyrmion tube made of thinner sublayer skyrmions is more stable during its motion, which ensures that a higher speed of the skyrmion tube can be reached effectively at larger driving current. In the SyAF multilayer with a given total thickness, the current-induced deformation of the SyAF skyrmion tube decreases with an increasing number of interfaces; namely, the rigidity of the SyAF skyrmion tube with a given thickness increases with the number of ferromagnetic (FM) layers. For the SyAF multilayer with an even number of FM layers, the skyrmion Hall effect can be eliminated when the thicknesses of all FM layers are identical. Larger damping parameter leads to smaller deformation and slower speed of the SyAF skyrmion tube. Larger fieldlike torque leads to larger deformation and a higher speed of the SyAF skyrmion tube. Our results are useful for understanding the dynamic behaviors of three-dimensional topological spin textures and may provide guidelines for building SyAF spintronic devices., Comment: 8 pages, 6 figures

Magnetic skyrmions are potential building blocks for future information storage and computing devices. Here, we computationally study the skyrmion dynamics in a cross structure made of two ferromagnetic nanotracks. We show that by controlling the skyrmion motion in the cross structure using spin currents, it is possible to realize the transcription of skyrmion at the intersection of the cross structure at certain conditions. Based on the transcription of skyrmion, we computationally demonstrate the AND, OR and NOT logical gates using the cross structures with modified geometries and appropriate magnetic parameters. Our results may provide guidelines to design future three-dimensional spintronics devices based on magnetic skyrmions.

The coexistence of polarization and the Rashba effect in ferroelectrics enables the electrical control of spin degree of freedom. Here, we explore the Rashba effect in 2D ferroelectric LiAlTe2, which has been predicted recently based on the global structure search by the particle optimization algorithm. Based on the density functional theory calculations, we have studied the electronic structures and spin textures driven by spin–orbit coupling and demonstrated a large Rashba spin splitting around the bottom of conduction bands. Further, the magnitude of the Rashba parameter is tunable by polarization switching. The physical mechanism of the Rashba effect is well analyzed within the k · p Hamiltonian model using the method of invariants. Our results add additional functionality to 2D LiAlTe2.

In recent years, it is evidenced that the individuals newly infected HIV are transmitting the virus prior to knowing their HIV status. Identifying individuals that are early in infection with HIV antibody negative (window period) remains problematic. In the newly infected individuals, HIV antigen p24 is usually present in their serum or plasma 7-10 days before the HIV antibody. After antibody production initiates, the p24 antigen is bound into immune complexes. That means the detectable p24 antigens in serum/plasma are short-lived. Thus, a rapid quantitative bio-detection system is required to achieve early disease diagnosis. Magnetoresistive (MR) biosensor with ultra-high sensitivity possesses great potential in this area. In this study, a p24 detection assay using MgO-based magnetic tunnel junction (MTJ) sensor and 20-nm magnetic nanoparticles is reported.

Display Omitted Pit-patterned PDMS substrates were fabricated.Effect of bi-directional topographical cues on cellular behavior of HeLa cells was investigated.The pit-patterned substrates with rectangular pits could promote cell alignment.Cell elongation was reduced on the pit-patterned substrates.The HeLa cells responded to the patterns in a coordinated manner. The study of cell migration is valuable for the understanding of various physiological and pathological processes. Microgrooved/microridged substrates have been intensively studied to reveal the effect of single topographical cues on cellular behavior. However, cells in vivo are usually surrounded by multidirectional topography signals. This study investigated the effect of bi-directional topographical cues on cellular behavior of mammalian cells. In this study, bi-directional pit patterned poly(dimethylsiloxane) (PDMS) substrates were fabricated with different sizes but same depth (1µm). The fabricated patterns were then used to study cellular response to bi-directional cues of mammalian cell line, in this case HeLa cells. After seeding cells for 48h, the PDMS substrates were examined by SEM. Cell alignment angle and aspect ratio were measured from the SEM images. The results show that the cells on the patterned substrates with square pits did not align along either x- or y-axis. However the patterns with rectangular pits could promote cell alignment along the longer sides of pits. Moreover, comparing to the cell elongation on the control flat substrate, the elongation of cells was decreased on all the patterned substrates. These results are helpful for a deeper understanding of the mechanism of bi-directional topographical cues on cellular behavior of mammalian cell line.

Gold/iron oxide nanocomposites offer the promise of combining the unique traits of both gold and iron oxide nanomaterials to enable new applications. In this work, a simple and safe method has been established whereby the morphology of gold material in gold/iron oxide nanocomposites can be controlled to be nanowire or nanosphere by adjusting the initial molar ratio of citrate-coated iron oxide nanoparticles to auric acid. Gold/iron oxide nanowires and nanospheres were synthesized through this method. Their structural, optical, and magnetic properties were characterized by transmission electron microscopy (TEM), energy-dispersive X-ray spectroscopy (EDS), dynamic light scattering (DLS), ultraviolet-visible spectroscopy (UV-Vis), and vibrating sample magnetometry (VSM). These materials substantially maintained the optical properties of gold nanomaterials and magnetic features of iron oxide magnetic nanoparticles.

Octahedron-like Au/Fe3O4 magnetic nanoparticles are synthesized using decomposition of FeO(OH) and HAuCl4 with the presence of oleic acid in 1-octadecene solvent. In the octahedron-like hybrid particles, Fe3O4 mainly displayed the octahedral morphology and spherical Au nanoparticles partially embedded into one side of Fe3O4 octahedron. The size of particle could be tuned from 25 to 240 nm for the whole particle (mainly for Fe3O4) and 10 to 40 nm for Au by changing the proportion of the starting materials. The hybrid particles showed the magnetic properties of Fe3O4 with dependence on the size of Fe3O4 octahedron composite and the proportion of Fe3O4 to Au. Coercivity is observed in the hybrid Au/Fe3O4 octahedron-like nanoparticles (55 Oe for 25 nm, 135 Oe for 100 nm, and 159 Oe for 240 nm) at room temperature. These size-controllable hybrid Au/Fe3O4 magnetic octahedron-like particles, inheriting the advantages of Au and Fe3O4 nanoparticles, may evolve as useful building blocks for nano- and micro-electronic applications.

Dextran-coated magnetic iron oxide nanoparticles (DMNPs) have attracted significant attention for their many applications in biomedical area such as diagnostic magnetic resonance imaging (MRI), and gene therapy. For biomedical applications, nanoparticles must be sterile, and several terminal sterilization methods can be used. However, very little is known regarding the effect of sterilization methods on the properties of DMNPs. It is crucial to find out whether the DMNPs are affected by the sterilization process. This paper reported the influences on the physicochemical properties of DMNPs from four different methods: autoclaving, sterile filtration, UV irradiation and chemical sterilization with ethanol. In addition, cell viability was also studied. Our results indicate that filter sterilization changes the iron oxide/dextran ratio in DMNPs sample significantly. Besides, the autoclaving and ethanol treatment affected the polydispersity index of DMNPs sample. Thus, caution must be taken when choosing an appropriate method to perform sterilization for DMNPs.

Material surface topography is an important factor for regulating cellular behaviour. Understanding the mechanism of how surface topography influences mammalian cells is critical for the development of medical implants and tissue engineering. In this study, we investigated the influences of nanoporous and microgrooved substrates on the morphology and migration of hepatic cell line, BEL-7402 cells. Cells were cultured on nanoporous (140nm in diameter) anodized alumina membrane (AAM), nanoporous (140nm in diameter) polydimethylsiloxane (PDMS), and microgrooves (10@mm, 30@mm, and 50@mm in width, and 2@mm in depth) patterned PDMS, then imaged by fluorescent microscopy, time-lapse microscopy, and scanning electron microscopy (SEM). Cell morphology and migration were investigated through image analysis. The results suggest that the nanoporous and microgrooved surface structure induced totally different changes on BEL-7402 cells. Compared to the well-spread cells on the flat surface plate, the cells formed spheroids on the nanoporous AAM surface and nanoporous PDMS surface with no elongation and alignment, while the cells grew with elongated and aligned morphology along the microgrooves on the PDMS substrates. The BEL-7402 cell migration speed was significantly higher on the nanoporous substrates than on the flat surfaces. On the microgrooved PDMS substrates, the cells migrated along the groove direction and showed relatively small difference of the overall velocity compared to the cells on the flat PDMS surface. Our findings provide insights into the control of cell morphological features and migratory behaviour by using artificial nanoporous or microgrooved substrates, which can benefit the research on hepatocellular carcinoma metastasis, tissue engineering, and medical implant design.

Citric acid is a widely accepted coating material in nanoparticle fabrication for biomedical applications while iron oxide is one popular magnetic material with excellent properties for use in nanoparticle form. However, the effect of synthesis conditions on the properties of iron oxide nanoparticles is not sufficiently understood. Here, citric-acid coated iron oxide nanoparticles were synthesized based on the co-precipitation method through both one-step and two-step process, respectively. The citric acid was added at different stages, and various coating temperatures were used in the two-step process. The nanoparticles were characterized by multiple techniques including Fourier transform infrared spectroscopy, transmission electron microscopy, dynamic light scattering, thermogravimetric analysis, and vibrating sample magnetometry. It was found that the addition of citric acid at different stages can alter the nanoparticle core size, while the coating temperature affects citric acid adsorption around nanoparticles surface and alters the nanoparticle hydrodynamic size. The effect of citric-acid coating on the magnetic behavior was also investigated on 9nm and 25nm iron oxide nanoparticles.

We demonstrated the use of exchange-biased giant magnetoresistance (GMR) sensors in Wheatstone bridge for the detection of 10-nm superparamagnetic iron oxide nanoparticles (SPIONs). The SPIONs were synthesized via coprecipitation method, exhibiting a superparamagnetic behavior with saturation magnetization of 57 emu/g. The output voltage signal of the Wheatstone bridge exhibits log-linear function of the concentration of SPIONs (from 10 ng/ml to 0.1 mg/ml), making the sensors suitable for use as a SPION concentration detector. Thus the combination of 10 nm SPIONs and the exchange-biased GMR sensors has potential to be used in the bio-detection applications where ultra-small bio-labels are needed.

Magnetic iron oxide nanoparticles (MIONPs) must be biocompatible, and a thorough knowledge on their potential cytotoxicity is crucial for their biomedical applications. However, the detailed study about the effects of iron oxide nanoparticles on cell viability, cell morphology, and cellular uptake of different mammalian cells is still insufficient. In this paper, comparative cytotoxicity study of uncoated magnetite nanoparticles at different concentrations was performed on human cervical cancer cell line (HeLa) and immortalized normal human retinal pigment epithelial cell line (RPE). The size, structure, and magnetic behavior of the MIONPs were characterized using transmission electron microscopy (TEM), X-ray diffractometry (XRD), and vibrating sample magnetometry (VSM) respectively. After 24-hour incubation with the MIONPs, the cell viability was determined by live/dead assay, the cell morphology at high magnification was observed under scanning electron microscopy (SEM), and the cellular uptake of MIONPs was measured under TEM and verified by energy-dispersive X-ray spectroscopy (EDX) analysis. Our results indicate that the uncoated MIONPs at a high concentration (0.40 mg/ml) were toxic to both HeLa and RPE cells. However, the cytotoxicity of uncoated MIONPs at low concentrations was cell-type specific, and RPE cells were more susceptible to these MIONPs than HeLa cells. The effects of the MIONPs on cell morphology and the nanoparticles uptake also showed different features between these two cell lines. Hence cell type should be taken into consideration in the in vitro cytotoxicity study of uncoated MIONPs. Additionally, it should be noticed that the cell morphological changes and the uptake of nanoparticles can take place even though no toxic effect of these MIONPs at low concentrations was reflected in the traditional cell viability assay.

Magnetic nanoparticles functionalized with carboxyl-group have considerable potential to be used as bio-labels due to their conjugation abilities with proteins. Here, we synthesized the iron oxide nanoparticles functionalized with carboxyl groups through self-assembled monolayer coating using citric acid and self-assembled bilayer coating using fatty acids. Their dimension, hydrodynamic size, surface property, and magnetic behavior were characterized through transmission electron microscopy, dynamic light scattering, Fourier transform infrared spectroscopy, thermal gravimetric analysis, and vibrating sample magnetometry. We also confirmed the binding ability of these nanoparticles with bovine serum albumin on thin gold film.

Objective: To explore the differential outcome of schizophrenia in developed and developing countries. The 15–year outcome of patients with schizophrenia in Hong Kong is reported. Method: In a 15-year retrospective outcome study, 100 patients with first-onset schizophrenia in 1977–1978 were randomly selected for outcome assessment from a pool of 797 patient files. The patterns of outcome were assessed by the same set of instruments and methodology as in other centres, since Hong Kong is 1 of the World Health Organization (WHO) centres for the International Study of Schizophrenia (ISoS). Results: Nineteen subjects were untraceable, and 10 subjects committed suicide. More than one-half of the subjects had a good symptomatic outcome, while about 20% of the subjects were rated as having a good psychosocial adjustment. Over the entire 15-year period, 96% of the subjects were maintained on medications, and 79% were living with family members. Conclusion: Despite Hong Kong's developed economy, its schizophrenia outcome is similar to that in developing countries. The existence of good family support and active follow-up treatment may be important contributory factors to better outcome.

OBJECTIVE To evaluate the optimal timing for initiating antiretroviral therapy in patients with human immunodeficiency virus (HIV)-associated tuberculosis in Hong Kong. DESIGN Historical cohort. SETTING. Tuberculosis and Chest Service and Special Preventive Programme, Public Health Service Branch, Centre for Health Protection, Department of Health, Hong Kong. PATIENTS Consecutive patients with HIV-associated tuberculosis in a territory-wide TB-HIV registry encountered from 1996 to 2009. RESULTS Of the 260 antiretroviral therapy-naive patients with HIV-associated tuberculosis, 32 (12%) had antiretroviral therapy initiated within 2 months after starting anti-tuberculosis treatment (early antiretroviral therapy). Early antiretroviral therapy was associated with a more favourable outcome (cure or treatment completion without relapse) at 24 months (91% vs 67%; P=0.007) than those with antiretroviral therapy started later or not initiated, and remained an independent predictor of a favourable outcome after adjustment for potential confounders. Adverse effects from anti-tuberculosis drugs tended to occur more frequently in patients with early antiretroviral therapy (13/32 or 41%) compared with the remainder (59/228 or 26%; P=0.08). A significantly higher proportion of patients in the former group experienced immune reconstitution inflammatory syndrome than in the latter group (7/32 or 22% vs 9/228 or 4%; P