Preparation, thermal storage properties and application of sodium acetate trihydrate/expanded graphite composite phase change materials

The development of energy storage technology is beneficial for the efficient use of energy and sustainable development. As an effectual approach for storing and transporting thermal energy, latent heat storage using phase change materials (PCMs) has attracted tremendous attention. However, low thermal conductivity, poor stability, and leakages are considerable challenges to the widespread application of solid-liquid PCMs. Composite phase change materials (CPCMs) were prepared by combining expanded graphite (EG) and sodium acetate trihydrate (CH3COONa·3H2O, SAT). EG as a supporting material plays a crucial part in both enhancing the thermal conductivity and preventing the melted PCMs from leakage. The chemical structure, micromorphology, thermal stability, thermal conductivity, phase change behavior and heat storage performance of SAT/EG CPCMs have been extensively investigated by scanning electron microscopy (SEM), Fourier transform infrared spectroscopy (FTIR), X-ray diffraction (XRD), thermal conductivity analysis, differential scanning calorimetry (DSC), and cycling stability measurement. The results of SEM indicate that EG with a loose and porous layered structure has a good molding effect and can adsorb SAT well. XRD and FTIR results show that only a simple physical combination between EG and SAT exists, and no new substances have been produced. Compared with pure SAT, thermal conductivity and supercooling tests show that the supercooling degree of the CPCMs was decreased and the thermal conductivity was increased by 205.1%. In addition, the addition of 2 wt% of disodium hydrogen phosphate dodecahydrate (Na2HPO4·12H2O, DHPD) as a nucleating agent and 0.5 wt% of gelatin as a thickening agent to SAT could reduce the supercooling degree and inhibit the phase separation well. Based on SAT/EG-8% CPCMs, an oven with phase change energy storage was designed and the heat storage/release performance of the oven was investigated under different operating conditions.

Low-intensity open-field blast exposure effects on neurovascular unit ultrastructure in mice

Mild traumatic brain injury (mTBI) induced by low-intensity blast (LIB) is a serious health problem affecting military service members and veterans. Our previous reports using a single open-field LIB mouse model showed the absence of gross microscopic damage or necrosis in the brain, while transmission electron microscopy (TEM) identified ultrastructural abnormalities of myelin sheaths, mitochondria, and synapses. The neurovascular unit (NVU), an anatomical and functional system with multiple components, is vital for the regulation of cerebral blood flow and cellular interactions. In this study, we delineated ultrastructural abnormalities affecting the NVU in mice with LIB exposure quantitatively and qualitatively. Luminal constrictive irregularities were identified at 7 days post-injury (DPI) followed by dilation at 30 DPI along with degeneration of pericytes. Quantitative proteomic analysis identified significantly altered vasomotor-related proteins at 24 h post-injury. Endothelial cell, basement membrane and astrocyte end-foot swellings, as well as vacuole formations, occurred in LIB-exposed mice, indicating cellular edema. Structural abnormalities of tight junctions and astrocyte end-foot detachment from basement membranes were also noted. These ultrastructural findings demonstrate that LIB induces multiple-component NVU damage. Prevention of NVU damage may aid in identifying therapeutic targets to mitigate the effects of primary brain blast injury.

Traumatic Brain Injury in Cameroon: A Prospective Observational Study in a Level I Trauma Centre

Background and Objective: About 14 million people will likely suffer a traumatic brain injury (TBI) per year by 2050 in sub-Saharan Africa. Studying TBI characteristics and their relation to outcomes can identify initiatives to improve TBI prevention and care. The objective of this study was to define the features and outcomes of TBI patients seen over a 1-year period in a level-I trauma centre in Cameroon. Materials and Methods: Data on demographics, causes, clinical aspects, and discharge status were collected over a period of 12 months. The Glasgow Outcome Scale-Extended (GOSE) and the Quality-of-Life Questionnaire after Brain Injury (QoLIBRI) were used to evaluate outcomes six months after TBI. Comparisons between two categorical variables were done using Pearson's chi-square test. Results: A total of 160 TBI patients participated in the study. The age group 15-45 years was most represented (78%). Males were more affected (90%). A low educational level was seen in 122 (76%) cases. Road traffic incidents (RTI) (85%), assaults (7.5%), and falls (2.5%) were the main causes of TBI, with professional bike riders being frequently involved (27%). Only 15 patients were transported to the hospital by ambulance, and 14 of these were from a referring hospital. CT-imaging was performed in 78% of cases, and intracranial traumatic abnormalities were identified in 64% of cases. Financial constraints (93%) was the main reason for not performing a CT scan. Forty-six (33%) patients were discharged against medical advice (DAMA) due to financial constraints. Mortality was 14% (22/160) and high in patients with severe TBI (46%). DAMA had poor outcomes with QoLIBRI. Only four patients received post-injury physical therapy services. Conclusions: TBI in Cameroon mainly results from RTIs and commonly affects young adult males. Lack of pre-hospital care, financial constraints limiting both CT scanning and medical care, and a lack of acute physiotherapy services likely influenced care and outcomes adversely.

Association between Cerebrospinal Fluid and Serum Biomarker Levels and Diagnosis, Injury Severity, and Short-Term Outcomes in Patients with Acute Traumatic Spinal Cord Injury

Acute traumatic spinal cord injury (SCI) is recognized as a global problem that can lead to a range of acute and secondary complications impacting morbidity and mortality. There is still a lack of reliable diagnostic and prognostic biomarkers in patients with SCI that could help guide clinical care and identify novel therapeutic targets for future drug discovery. The aim of this prospective controlled study was to determine the cerebral spinal fluid (CSF) and serum profiles of 10 biomarkers as indicators of SCI diagnosis, severity, and prognosis to aid in assessing appropriate treatment modalities. CSF and serum samples of 15 SCI and ten healthy participants were included in the study. The neurological assessments were scored on admission and at discharge from the hospital using the American Spinal Injury Association Impairment Score (AIS) grades. The CSF and serum concentrations of SBDP150, S100B, GFAP, NF-L, UCHL-1, Tau, and IL-6 were significantly higher in SCI patients when compared with the control group. The CSF GBDP 38/44K, UCHL-L1, S100B, GFAP, and Tau levels were significantly higher in the AIS A patients. This study demonstrated a strong correlation between biomarker levels in the diagnosis and injury severity of SCI but no association with short-term outcomes. Future prospective controlled studies need to be done to support the results of this study.

Demographics, Causes, and Outcome of Traumatic Brain Injury among Trauma Cases in Cameroon: A Multi-Center Five Year's Retrospective Study

Traumatic brain injury (TBI) is a huge public health challenge worldwide. Epidemiological monitoring is important to inform healthcare policy. We aimed at determining the prevalence, outcome, and causes of TBI in Cameroon by conducting a 5-year retrospective study in three referral trauma centers. Data on demographics, causes, injury mechanisms, clinical aspects, and discharge status were recorded. Comparisons between two categorical variables were done using Pearson's chi-square test or Fisher's exact test. A total of 6248 cases of TBI were identified of 18,151 trauma cases, yielding a prevalence of 34%. The number of TBI cases increased across the years (915 in 2016, 1406 in 2020). Demographic data and causes of TBI were available for 6248 subjects and detailed data on clinical characteristics on 2178 subjects. Median age was 30.0 (24.0, 41.0) years. Males were more affected (80%). Road traffic incidents (RTIs; 75%) was the main cause of TBI, with professional bike riders being more affected (17%). Computed tomography (CT) imaging was performed in 67.7% of cases. Of the 597 (27.4%) cases who did not undergo neuroimaging, 311 (52.1%) did not have neuroimaging performed because of financial constraints, among which 7% were severe TBI cases. A total of 341 (19.6%) patients were discharged against medical advice, of which 83% had financial limitations. Mortality was 10.3% (225 of 2178) in the overall population, but disproportionately high in patients with severe TBI (55%) compared to those in high-income settings (27%). TBI occurrence is high in Cameroon, and RTIs are the main causes. Disparities in care provision were identified as attributable to financial constraints regarding CT scanning and continuation of care. The data presented can inform preventive interventions to improve care provision and transport policies. Implementation of a universal health insurance may be expected to improve hospital care and reduce the adverse effects of TBI among Cameroonians.

[Epidemiological characteristics and the establishment and evaluation of a risk prediction model for nosocomial infection in burn patients]

Objective: To find the epidemiological characteristics of nosocomial infection in burn patients, to establish a risk prediction model for nosocomial infection in burn patients based on the screened independent risk factors of the infection, and to analyze its predictive value. Methods: A retrospective case series study was conducted. From May 2016 to December 2019, 3 475 burn patients who were admitted to the Department of Burns of Affiliated Hospital of Jiangnan University met the inclusion criteria, including 2 290 males and 1 185 females, aged from 1 to 94 years. The incidence of nosocomial infection, the detection site and specific composition of pathogenic bacteria were counted. The patients were randomly divided into training group (2 434 cases) and verification group (1 041 cases) in R 4.1.3 statistic software with a ratio of about 7∶3. Factors including gender, age, total burn area, combination of full-thickness burn/inhalation injury/shock/diabetes on admission, admission to intensive care unit (ICU), status of central venous catheterization/endotracheal intubation/urethral catheter indwelling/surgery, nosocomial infection status, days of antibiotic use, and days of hospital stay of patients were compared between the two groups. According to the occurrence of nosocomial infection, the patients were divided into nosocomial infection group (102 cases) and non-nosocomial infection group (3 373 cases), and in addition to the aforementioned data, non-nosocomial infection related data, the season of admission and types of antibiotics used were compared between the two groups. The above-mentioned data were statistically analyzed with one-way analysis of independent sample t test, chi-square test, and Mann-Whitney U test, and the indicators with statistically significant differences between nosocomial infection group and non-nosocomial infection group were included as variables in multivariate logistic regression analysis to screen independent risk factors for the development of nosocomial infection in 3 475 burn patients. On the basis of independent risk factors and important clinical characteristics, a nomogram prediction model was constructed for the risk of developing nosocomial infection of burn patients in training group. In both training group and verification group, receiver operating characteristic (ROC) curves for prediction of nosocomial infection by the prediction model were plotted, and the area under the ROC curve was calculated; calibration curves were plotted to evaluate the conformity between the predicted results of the prediction model and the actual situation; clinical decision curves were plotted to evaluate the clinical utility of the prediction model. Results: The incidence of nosocomial infection of patients included in this study was 2.94% (102/3 475); pathogens were detected from 212 specimens, mainly wound (78 cases, accounting for 36.79%) and blood (64 cases, accounting for 30.19%) specimens; 250 strains of pathogenic bacteria were detected, mainly gram-negative bacteria (153 strains, accounting for 61.20%). All clinical characteristics of patients between training group and verification group were similar (P>0.05). There were statistically significant differences between patients in nosocomial infection group and non-nosocomial infection group in the aspects of age, total burn area, days of antibiotic use, antibiotic use type, days of hospital stay, combination of full-thickness burn, combination of inhalation injury, combination of shock, ICU admission status, central venous catheterization status, endotracheal intubation status, urethral catheter indwelling status, surgery status (with Z values of 4.41, 14.95, 15.70, 650.32, and 13.73, χ2 values of 151.09, 508.30, 771.20, 955.79, 522.67, 967.40, 732.11, and 225.35, respectively, P<0.01). ICU admission, endotracheal intubation, urethral catheter indwelling, and days of hospital stay were independent risk factors for developing nosocomial infection by 3 475 burn patients (with odds ratios of 5.99, 3.39, 9.32, and 6.21, 95% confidence intervals of 2.25-15.99, 1.56-7.39, 2.77-31.31, and 2.48-15.92, respectively, P<0.01). In training group and verification group, the area under ROC curves of the nosocomial infection prediction model based on independent risk factors, total burn area, and central vein catheterization were both 0.97 (with both 95% confidence intervals being 0.95-0.99); the calibration curve analysis showed that the prediction results of the prediction model were in good agreement with the actual situation; the clinical decision curve analysis showed that the prediction model had good clinical utility. Conclusions: The nosocomial infection in burn patients is mainly caused by gram-negative bacteria, with wound as the main infection site, and the independent risk factors including ICU admission, endotracheal intubation, urethral catheter indwelling, and days of hospital stay. Based on independent risk factors and important clinical features, the risk prediction model for nosocomial infection has a good ability to predict nosocomial infection in burn patients.

[A single-center retrospective analysis of 77 traumatic arterial injuries of lower extremities]

Objective: To analyze the treatment and clinical prognosis of lower extremity arterial injury caused by trauma. Methods: The clinical data of 77 patients with traumatic lower extremity arterial injury admitted to Department of Vascular Surgery,Yichang Central People's Hospital from January 2013 to June 2021 were collected. There were 65 males and 12 females, with an average age of 47.4 years (range: 7 to 75 years). Among the 77 patients, 56 (72.7%) had open injury and 21 (27.3%) had closed injury. Iliac artery was injured in 9 cases (11.7%), common femoral artery in 7 cases (9.1%), superficial femoral artery in 1 case (1.3%), popliteal artery in 11 cases (14.3%) and inferior knee artery in 49 cases (63.6%). The treatment methods and clinical effects were analyzed. Results: One patient with pelvic fracture combined the internal iliac artery injury and 1 patient with multiple injuries involving the common femoral artery died of circulatory failure before surgery. Seventy-five patients received vascular-related operations, including arterial ligation in 24 cases, arterial reconstruction in 40 cases, stent graft implantation in 1 case, primary amputation in 2 cases, and arterial embolization in 8 cases. The overall mortality rate was 6.5% (5/77), all of which were closed injuries. Except for 2 patients who died before surgery, 3 patients with pelvic fracture combined the internal iliac artery injury died of multiple organ failure after internal iliac artery embolization. There were 8 patients received amputation (10.4%, 8/77), 5 patients with closed injury and 3 patients with open injury. In addition to 2 patients with primary amputation, 6 patients underwent secondary amputation due to ischemia-reperfusion injury after revascularization (4 cases with popliteal artery injury and 2 cases with subpatellar artery injury). The average followed-up time was 17 months (range: 2 months to 8 years). One patient with femoral artery injury underwent autologous great saphenous vein bypass, and lower limb artery CT angiography was re-examined 6 months after the operation, and 30% distal anastomotic stenosis was found. Ankle brachial index<0.8 was found in two patients 1 year after popliteal artery repair, but none of the patients had intermittent claudication symptoms, and no further intervention was performed. Five patients suffered delayed healing due to severe lower limb injury, fracture and skin injury. Among them, 2 patients had poor wound healing at the stump of amputation, which gradually healed 3 to 5 months after several debridements. The other 3 vascular injury combined with tibial fracture patients had delayed tibial healing after surgery, but no symptoms of vascular ischemia occurred. All the other patients recovered well and no other serious complications occurred. Conclusions: The proportion of death and disability in patients with lower limb artery injury caused by trauma is high. Active and orderly surgical repair according to the site and type of injury can reduce the mortality, save the function of the affected limb, and promote the healing of injury.

[Evidence-based progress for the risk events of paclitaxel devices in treatment of peripheral artery disease]

With the development of endovascular technology for peripheral arterial diseases, paclitaxel drug-eluting stents and drug-coated balloons have been widely used in recent years. It has been proved that paclitaxel-coated devices have good clinical effects in reducing vascular restenosis. However, the clinical safety of paclitaxel devices has encountered challenges, some of the studies have shown that paclitaxel-coated devices may increase long-term mortality. In addition, some studies have confirmed the effectiveness and safety of paclitaxel devices, leading to this topic becoming the focus and hot spot of global attention. Whether paclitaxel-coated devices increase the risk of long-term death, whether paclitaxel doses are related to mortality, and the pharmacokinetics of paclitaxel devices should be examined.

Three phytotoxins produced by Neopestalotiopsis clavispora, the causal agent of ring spot on Kadsura coccinea

Phytotoxins are widely found in plant pathogens. In recent years, many diseases caused by Neopestalotiopsis clavispora have been reported. To better understand the pathogenicity of N. clavispora, a solid fermentation strategy was employed to isolate and identify virulence factors afritoxinone B, afritoxinone A and oxysporone. The phytotoxic activities of these toxins were evaluated. Oxysporone exhibited high levels of phytotoxic activity after 72 h and the lesion area ranged from 21.5-84.3 mm2 after 9 days of treatment. The phytotoxic activities of the other two compounds were lower than that for oxysporone. The phytotoxic activity towards non-host organisms was also assessed for the three analyzed compounds; phytotoxic activity was observed in each case. Based on these results, we conclude that oxysporone is the main virulence factor in N. clavispora. We also suggest that each of the three compounds were non-host-specific toxins (NHST). To our knowledge, this is the first study to analyze phytotoxins produced by N. clavispora.

Dynamics of Kresling origami deployment

Origami-inspired structures have a rich design space, offering new opportunities for the development of deployable systems that undergo large and complex yet predictable shape transformations. There has been growing interest in such structural systems that can extend uniaxially into tubes and booms. The Kresling origami pattern, which arises from the twist buckling of a thin cylinder and can exhibit multistability, offers great potential for this purpose. However, much remains to be understood regarding the characteristics of Kresling origami deployment. Prior studies have been limited to Kresling structures' kinematics, quasistatic mechanics, or low-amplitude wave responses, while their dynamic behaviors with large shape change during deployment remain unexplored. These dynamics are critical to the system design and control processes, but are complex due to the strong nonlinearity, bistability, and potential for off-axis motions. To advance the state of the art, this research seeks to uncover the deployment dynamics of Kresling structures with various system geometries and operating strategies. A full, six-degrees-of-freedom model is developed and employed to provide insight into the axial and off-axis dynamic responses, revealing that the variation of key geometric parameters may lead to regions with qualitatively distinct mechanical responses. Results illustrate the sensitivity of dynamic deployment to changes in initial condition and small variations in geometric design. Further, analyses show how certain geometries and configurations affect the stiffness of various axial and off-axis deformation modes, offering guidance on the design of systems that deploy effectively while mitigating the effects of off-axis disturbances. Overall, the research outcomes suggest the strong potential of Kresling-based designs for deployable systems with robust and tunable performance.

Metastable modular metastructures for on-demand reconfiguration of band structures and nonreciprocal wave propagation

We present an approach to achieve adaptable band structures and nonreciprocal wave propagation by exploring and exploiting the concept of metastable modular metastructures. Through studying the dynamics of wave propagation in a chain composed of finite metastable modules, we provide experimental and analytical results on nonreciprocal wave propagation and unveil the underlying mechanisms that facilitate such unidirectional energy transmission. In addition, we demonstrate that via transitioning among the numerous metastable states, the proposed metastructure is endowed with a large number of bandgap reconfiguration possibilities. As a result, we illustrate that unprecedented adaptable nonreciprocal wave propagation can be realized using the metastable modular metastructure. Overall, this research elucidates the rich dynamics attainable through the combinations of periodicity, nonlinearity, spatial asymmetry, and metastability and creates a class of adaptive structural and material systems capable of realizing tunable bandgaps and nonreciprocal wave transmissions.

Origami-based earthworm-like locomotion robots

Inspired by the morphology characteristics of the earthworms and the excellent deformability of origami structures, this research creates a novel earthworm-like locomotion robot through exploiting the origami techniques. In this innovation, appropriate actuation mechanisms are incorporated with origami ball structures into the earthworm-like robot 'body', and the earthworm's locomotion mechanism is mimicked to develop a gait generator as the robot 'centralized controller'. The origami ball, which is a periodic repetition of waterbomb units, could output significant bidirectional (axial and radial) deformations in an antagonistic way similar to the earthworm's body segment. Such bidirectional deformability can be strategically programmed by designing the number of constituent units. Experiments also indicate that the origami ball possesses two outstanding mechanical properties that are beneficial to robot development: one is the structural multistability in the axil direction that could contribute to the robot control implementation; and the other is the structural compliance in the radial direction that would increase the robot robustness and applicability. To validate the origami-based innovation, this research designs and constructs three robot segments based on different axial actuators: DC-motor, shape-memory-alloy springs, and pneumatic balloon. Performance evaluations reveal their merits and limitations, and to prove the concept, the DC-motor actuation is selected for building a six-segment robot prototype. Learning from earthworms' fundamental locomotion mechanism-retrograde peristalsis wave, seven gaits are automatically generated; controlled by which, the robot could achieve effective locomotion with qualitatively different modes and a wide range of average speeds. The outcomes of this research could lead to the development of origami locomotion robots with low fabrication costs, high customizability, light weight, good scalability, and excellent re-configurability.

Dynamics of a bistable Miura-origami structure

Origami-inspired structures and materials have shown extraordinary properties and performances originating from the intricate geometries of folding. However, current state of the art studies have mostly focused on static and quasistatic characteristics. This research performs a comprehensive experimental and analytical study on the dynamics of origami folding through investigating a stacked Miura-Ori (SMO) structure with intrinsic bistability. We fabricate and experimentally investigated a bistable SMO prototype with rigid facets and flexible crease lines. Under harmonic base excitation, the SMO exhibits both intrawell and interwell oscillations. Spectrum analyses reveal that the dominant nonlinearities of SMO are quadratic and cubic, which generate rich dynamics including subharmonic and chaotic oscillations. The identified nonlinearities indicate that a third-order polynomial can be employed to approximate the measured force-displacement relationship. Such an approximation is validated via numerical study by qualitatively reproducing the phenomena observed in the experiments. The dynamic characteristics of the bistable SMO resemble those of a Helmholtz-Duffing oscillator (HDO); this suggests the possibility of applying the established tools and insights of HDO to predict origami dynamics. We also show that the bistability of SMO can be programmed within a large design space via tailoring the crease stiffness and initial stress-free configurations. The results of this research offer a wealth of fundamental insights into the dynamics of origami folding, and provide a solid foundation for developing foldable and deployable structures and materials with embedded dynamic functionalities.

Plant-inspired adaptive structures and materials for morphing and actuation: a review

Plants exhibit a variety of reversible motions, from the slow opening of pine cones to the impulsive closing of Venus flytrap leaves. These motions are achieved without muscles and they have inspired a wide spectrum of engineered materials and structures. This review summarizes the recent developments of plant-inspired adaptive structures and materials for morphing and actuation. We begin with a brief overview of the actuation strategies and physiological features associated to these plant movements, showing that different combinations of these strategies and features can lead to motions with different deformation characteristics and response speeds. Then we offer a comprehensive survey of the plant-inspired morphing and actuation systems, including pressurized cellular structures, osmotic actuation, anisotropic hygroscopic materials, and bistable systems for rapid movements. Although these engineered systems are vastly different in terms of their size scales and intended applications, their working principles are all related to the actuation strategies and physiological features in plants. This review is to promote future cross-disciplinary studies between plant biology and engineering, which can foster new solutions for many applications such as morphing airframes, soft robotics and kinetic architectures.

Self-locking degree-4 vertex origami structures

A generic degree-4 vertex (4-vertex) origami possesses one continuous degree-of-freedom for rigid folding, and this folding process can be stopped when two of its facets bind together. Such facet-binding will induce self-locking so that the overall structure stays at a pre-specified configuration without additional locking elements or actuators. Self-locking offers many promising properties, such as programmable deformation ranges and piecewise stiffness jumps, that could significantly advance many adaptive structural systems. However, despite its excellent potential, the origami self-locking features have not been well studied, understood, and used. To advance the state of the art, this research conducts a comprehensive investigation on the principles of achieving and harnessing self-locking in 4-vertex origami structures. Especially, for the first time, this study expands the 4-vertex structure construction from single-component to dual-component designs and investigates their self-locking behaviours. By exploiting various tessellation designs, this research discovers that the dual-component designs offer the origami structures with extraordinary attributes that the single-component structures do not have, which include the existence of flat-folded locking planes, programmable locking points and deformability. Finally, proof-of-concept experiments investigate how self-locking can effectively induce piecewise stiffness jumps. The results of this research provide new scientific knowledge and a systematic framework for the design, analysis and utilization of self-locking origami structures for many potential engineering applications.

Uncovering the deformation mechanisms of origami metamaterials by introducing generic degree-four vertices

Origami-based design holds promise for developing new mechanical metamaterials whose overall kinematic and mechanical properties can be programmed using purely geometric criteria. In this article, we demonstrate that the deformation of a generic degree-four vertex (4-vertex) origami cell is a combination of contracting, shearing, bending, and facet-binding. The last three deformation mechanisms are missing in the current rigid-origami metamaterial investigations, which focus mainly on conventional Miura-ori patterns. We show that these mechanisms provide the 4-vertex origami sheets and blocks with new deformation patterns as well as extraordinary kinematical and mechanical properties, including self-locking, tridirectional negative Poisson's ratios, flipping of stiffness profiles, and emerging shearing stiffness. This study reveals that the 4-vertex cells offer a better platform and greater design space for developing origami-based mechanical metamaterials than the conventional Miura-ori cell.

Recoverable and Programmable Collapse from Folding Pressurized Origami Cellular Solids

We report a unique collapse mechanism by exploiting the negative stiffness observed in the folding of an origami solid, which consists of pressurized cells made by stacking origami sheets. Such a collapse mechanism is recoverable, since it only involves rigid folding of the origami sheets and it is programmable by pressure control and the custom design of the crease pattern. The collapse mechanism features many attractive characteristics for applications such as energy absorption. The reported results also suggest a new branch of origami study focused on its nonlinear mechanics associated with folding.

Role of IL-8 gene polymorphisms in glioma development in a Chinese population

This case-control study aimed to investigate the role of -251 T>A (rs4073) and -781 C>T (rs2227306) polymorphisms in the interleukin-8 (IL-8) gene in the development of glioma in a Chinese population. One hundred and twenty-seven glioma patients and 284 healthy control subjects were recruited to this study between February 2013 and December 2014. The IL-8 -251 T>A (rs4073) and -781 C>T (rs2227306) polymorphisms were genotyped by polymerase chain reaction coupled with restriction fragment length polymorphism. The patients and control subjects were comparable by gender (X² = 1.24, P = 0.27), tobacco smoking status (X² = 0.80, P = 0.37), alcohol consumption status (X² = 0.97, P = 0.32), and family history of cancer (X² = 1.54, P = 0.22). The age of glioma patients was statistically lower than that of control subjects (t = 2.87, P = 0.002). The chi-square test revealed the lack of any statistically significant differences in the genotype distributions of IL-8 rs4073 (X² = 0.89, P = 0.64) and rs2227306 (X² = 2.58, P = 0.28) between the glioma patients and control subjects. Unconditional logistic regression analysis revealed that the IL-8 rs4073 and rs2227306 gene polymorphisms did not contribute to the development of glioma. In conclusion, we determined that there is a lack of evidence suggesting a significant association between the IL-8 rs4073 and rs2227306 gene polymorphisms and the development of glioma in a Chinese population.

Fluidic origami with embedded pressure dependent multi-stability: a plant inspired innovation

Inspired by the impulsive movements in plants, this research investigates the physics of a novel fluidic origami concept for its pressure-dependent multi-stability. In this innovation, fluid-filled tubular cells are synthesized by integrating different Miura-Ori sheets into a three-dimensional topological system, where the internal pressures are strategically controlled similar to the motor cells in plants. Fluidic origami incorporates two crucial physiological features observed in nature: one is distributed, pressurized cellular organization, and the other is embedded multi-stability. For a single fluidic origami cell, two stable folding configurations can coexist due to the nonlinear relationships among folding, crease material deformation and internal volume change. When multiple origami cells are integrated, additional multi-stability characteristics could occur via the interactions between pressurized cells. Changes in the fluid pressure can tailor the existence and shapes of these stable folding configurations. As a result, fluidic origami can switch between being mono-stable, bistable and multi-stable with pressure control, and provide a rapid 'snap-through' type of shape change based on the similar principles as in plants. The outcomes of this research could lead to the development of new adaptive materials or structures, and provide insights for future plant physiology studies at the cellular level.

Phase coordination and phase-velocity relationship in metameric robot locomotion

This research proposes a new approach for the control of metameric robot locomotion via phase coordination. Unlike previous studies where global wave-like rules were pre-specified to construct the actuation sequence of segments, this phase coordination method generates robot locomotion by assigning the actuation phase differences between adjacent segments without any global prerequisite rules. To effectively coordinate the phase differences, different symmetry properties are introduced. Optimization is then carried out on various symmetrically coordinated phase-difference patterns to maximize the average steady-state velocity of the robot. It is shown that the maximum average velocity is always achieved when the reflectional symmetry is included in the phase-difference pattern, and the identical-phase-difference (IPD) pattern is preferred for implementation because it reduces the number of independent phase variables to only one without significant loss in locomotion performance. Extensive analytical investigations on the IPD pattern reveal the relationship between the average locomotion velocity and some important parameters. Theoretical findings on the relationship between the average velocity and the phase difference in the IPD pattern are verified via experimental investigations on an 8-segment earthworm-like metameric robot prototype. Finally, this paper reveals an interesting result that the optimized phase-difference pattern can naturally generate peristalsis waves in metameric robot locomotion without global prerequisite wave-like rules.

Dipteran wing motor-inspired flapping flight versatility and effectiveness enhancement

Insects are a prime source of inspiration towards the development of small-scale, engineered, flapping wing flight systems. To help interpret the possible energy transformation strategies observed in Diptera as inspiration for mechanical flapping flight systems, we revisit the perspective of the dipteran wing motor as a bistable click mechanism and take a new, and more flexible, outlook to the architectural composition previously considered. Using a representative structural model alongside biological insights and cues from nonlinear dynamics, our analyses and experimental results reveal that a flight mechanism able to adjust motor axial support stiffness and compression characteristics may dramatically modulate the amplitude range and type of wing stroke dynamics achievable. This corresponds to significantly more versatile aerodynamic force generation without otherwise changing flapping frequency or driving force amplitude. Whether monostable or bistable, the axial stiffness is key to enhance compressed motor load bearing ability and aerodynamic efficiency, particularly compared with uncompressed linear motors. These findings provide new foundation to guide future development of bioinspired, flapping wing mechanisms for micro air vehicle applications, and may be used to provide insight to the dipteran muscle-to-wing interface.

The influence of nanofiller alignment on transverse percolation and conductivity

Nanocomposites have unprecedented potential for conductivity-based damage identification when used as matrices in structural composites. Recent research has investigated nanofiller alignment in structural composites, but because damage identification often requires in-plane measurements, percolation and conductivity transverse to the alignment direction become crucial considerations. We herein contribute indispensable guidance to the development of nanocomposites with aligned nanofiller networks and insights into percolation trends transverse to the alignment direction by studying the influence of alignment on transverse critical volume fraction, conductivity, and rate of transition from non-percolating to percolating in three-dimensional carbon nanotube composite systems.

Multiplex polymerase chain reaction assay for the detection of minute virus of mice and mouse parvovirus infections in laboratory mice

Mouse parvoviruses are among the most prevalent infectious pathogens in contemporary mouse colonies. To improve the efficiency of routine screening for mouse parvovirus infections, a multiplex polymerase chain reaction (PCR) assay targeting the VP gene was developed. The assay detected minute virus of mice (MVM), mouse parvovirus (MPV) and a mouse housekeeping gene (α-actin) and was able to specifically detect MVM and MPV at levels as low as 50 copies. Co-infection with the two viruses with up to 200-fold differences in viral concentrations can easily be detected. The multiplex PCR assay developed here could be a useful tool for monitoring mouse health and the viral contamination of biological materials.

The interfacial strength of carbon nanofiber epoxy composite using single fiber pullout experiments

Carbon nanotubes and nanofibers are extensively researched as reinforcing agents in nanocomposites for their multifunctionality, light weight and high strength. However, it is the interface between the nanofiber and the matrix that dictates the overall properties of the nanocomposite. The current trend is to measure elastic properties of the bulk nanocomposite and then compare them with theoretical models to extract the information on the interfacial strength. The ideal experiment is single fiber pullout from the matrix because it directly measures the interfacial strength. However, the technique is difficult to apply to nanocomposites because of the small size of the fibers and the requirement for high resolution force and displacement sensing. We present an experimental technique for measuring the interfacial strength of nanofiber-reinforced composites using the single fiber pullout technique and demonstrate the technique for a carbon nanofiber-reinforced epoxy composite. The experiment is performed in situ in a scanning electron microscope and the interfacial strength for the epoxy composite was measured to be 170 MPa.

A new method of chaining carbon nanofibers in epoxy

In this paper, a new and innovative process for assembling chains of carbon nanofibers (CNFs) in epoxy, uniquely different from those generally used for chaining particles in a liquid medium, is presented. Chains of aligned CNFs are assembled in a region rich in CNFs and extended into regions where there are no CNFs. A physical explanation of the process is provided based on the conductive nature of the CNFs. By contacting the chains with the electrodes, the process of chain growth is expedited and well-ordered parallel chains with equal spacing are grown over distances of 2 cm.

An enzymatic route to produce pyruvate from lactate

A bacterial strain of Acinetobacter sp., which was capable of enzymatic production of pyruvate from lactate, was cultured in a 5-l reactor with a basal salt medium. After 14 h of fed-batch fermentation, 9.56 g l(-1) cell concentration in the broth was obtained with 20 g l(-1) (178 mM) sodium lactate and 4 g l(-1) NH(4)Cl in the medium; and the biotransformation ability was 2.51 units ml(-1). The cells were harvested from one reactor and then used for pyruvate production from lactate in the same reactor. l-lactate at a concentration about 527 mM was almost stoichiometrically converted to pyruvate in 28 h. After a total 42 h of cell culture and biotransformation, the transformative yield was about 0.72 g g(-1) pyruvate from lactate and the rate of pyruvate production was calculated as 1.33 g l(-1) h(-1) during the process. The results suggested this simple enzymatic production of pyruvate from lactate should be a promising process and may bring a yield higher than that by microbial fermentation. By this process, the recovery of pyruvate from such a simple reaction liquid is relatively easy and inexpensive to perform.

Sequence and function of the two P domain potassium channels: implications of an emerging superfamily

A new superfamily of K+ channels has emerged in the past 2 years. Notable for possessing two pore-forming P domains in each subunit, members of the superfamily have been recognized through phylogeny from micro-organisms to humans. Four subfamilies of two P domain channels have been isolated thus far; among these are the first cloned examples of outward rectifier and open rectifier (or leak) K+ channels. The two P domain K+ channels offer a new perspective from which to glimpse the molecular basis for function and dysfunction of K+-selective ion channels.

A minK-HERG complex regulates the cardiac potassium current I(Kr)

MinK is a widely expressed protein of relative molecular mass approximately 15K that forms potassium channels by aggregation with other membrane proteins. MinK governs ion channel activation, regulation by second messengers, and the function and structure of the ion conduction pathway. Association of minK with a channel protein known as KvLQT1 produces a voltage-gated outward K+ current (I[sK]) resembling the slow cardiac repolarization current (I[Ks]). HERG, a human homologue of the ether-a-go-go gene of the fruitfly Drosophila melanogaster, encodes a protein that produces the rapidly activating cardiac delayed rectifier (I[Kr]). These two potassium currents, I(Ks) and I(Kr), provide the principal repolarizing currents in cardiac myocytes for the termination of action potentials. Although heterologously expressed HERG channels are largely indistinguishable from native cardiac I(Kr), a role for minK in this current is suggested by the diminished I(Kr) in an atrial tumour line subjected to minK antisense suppression. Here we show that HERG and minK form a stable complex, and that this heteromultimerization regulates I(Kr) activity. MinK, through the formation of heteromeric channel complexes, is thus central to the control of the heart rate and rhythm.

MinK potassium channels are heteromultimeric complexes

MinK is a transmembrane protein of 130 amino acids found in the kidney, heart, and vestibular system of mammals. Its expression in Xenopus laevis oocytes induces a voltage-dependent potassium current similar to that seen in vivo. Indirect evidence has fueled speculation that function requires association of MinK and another protein endogenous to oocytes and native tissues. In this report, we show that direct covalent modification of an oocyte membrane protein alters properties of the MinK ion conduction pore; modified channels exhibit decreased potassium conduction and increased permeability to sodium and cesium. The modifying reagents, two membrane-impermeant, sulfhydryl-specific methanethiosulfonate derivatives, react only from the extracellular solution at rates that are determined by the conformational state of the channel. These findings indicate that MinK is intimately associated with an oocyte protein whose exposure to the external solution changes during channel gating and which acts with MinK to establish ion conduction pore function.

MinK residues line a potassium channel pore

MinK has neither the P region nor signature sequence that characterizes pore-forming subunits of all known K+ channels. A specific minK region has now been identified that affects external blockade by 2 common probes of K+ channel pores. When mutated to cysteine, residues in this region render minK susceptible to covalent blockade by methanethiosulfonate ethylsulfonate and alter reversible inhibition by tetraethylammonium. The 2 blockers are found to share overlapping binding site determinants and to interact. Since inhibition by external tetraethylammonium is sensitive to voltage and to the internal concentration of permeant ions, we argue that tetraethylammonium blocks by occluding the external end of a water-filled transmembrane pore. These findings support the view that minK is directly involved in forming a K+-selective ion conduction pathway.

Biodegradation of mixed wastes in continuously operated cyclic reactors

The problem of simultaneous biodegradation of two dissimilar substrates in a continuously operated cyclic reactor was studied both at the theoretical and experimental levels using a simple model system. The system involved media containing mixtures of glucose and phenol as carbon sources. A pure culture of Pseudomonas putida (ATCC 17514) was employed. Independent kinetic experiments have revealed that glucose and phenol are involved in a crossinhibitory uncompetitive kinetic interaction. The dynamics of a cyclically operated reactor were analyzed using the principles of bifurcation theory for forced systems. Experimental results have confirmed the theoretical predictions. Implications of the results for the design of waste-treating facilities are discussed.

Subunit composition of minK potassium channels

Expression of minK protein in Xenopus oocytes induces a slowly activating, voltage-dependent, potassium-selective current. Point mutations in minK that alter current gating kinetics, ion selectivity, pharmacology, and response to protein kinase C all support the notion that minK is a structural protein for a channel-type transporter. Yet, minK has just 130 amino acids and a single transmembrane domain. Though larger cloned potassium channels form functional channels through tetrameric subunit association, the subunit composition of minK is unknown. Subunit stoichiometry was determined by coexpression of wild-type minK and a dominant lethal point mutant of minK, which reaches the plasma membrane but passes no current. The results support a model for complete minK potassium channels in which just two minK monomers are present, with other, as yet unidentified, non-minK subunits.

Ion binding constants for gramicidin A obtained from water permeability measurements

Gramicidin A pores are permeable to water and small monovalent cations. For K, Rb, and Cs there is good evidence from conductances and permeability ratios that a second ion can enter a pore already occupied by another, but for Na this evidence is inconclusive and comparison of tracer fluxes and single channel conductances suggests that second ion entries are prohibited. Partly as a result of the complications of second ion entry there have been widely differing estimates for the dissociation constants for the first ion in the channel. Dani and Levitt (1981, Biophys. J. 35: 485-499) introduced a method for calculating ion binding constants from simultaneous measurements of water fluxes and membrane conductance. They found no evidence for second ion binding and calculated dissociation constants of 115 mM for Li, 69 mM for K, and 2 mM for Tl. It is shown here that the two-ion, four-state model predicts a dependence of water permeability on ion concentration that is difficult to distinguish from the predictions of block by a single ion. Using a modified technique that allows measurement of higher conductances, the first ion dissociation constants have been determined as 80 mM for Na, 40 mM for Rb and 15 mM for Cs. These values and those of Dani and Levitt fall in a smooth sequence. The dissociation constant for Cs is consistent with single channel conductances and flux ratios. There is a discrepancy between this constant for Na and the value, 370 mM, calculated from the single channel conductances and the assumption that a second ion cannot enter or affect an occupied pore. The dissociation constant for Rb is intermediate between those for K and Cs whereas tracer flux measurements (Schagina, Grinfeldt & Lev, 1983. J. Membrane Biol. 73: 203-216) have suggested that Rb interacts much more strongly with the channel than Cs.

An upper limit for the effect of low frequency magnetic fields on ATP-sensitive potassium channels

Currents have been recorded for ATP-sensitive potassium channels in excised patches of membranes from an insulin secreting cell line, CRI-G1. The multi-channel records have been analyzed to reveal the single-channel conductance, the frequency and duration of bursts and the frequency of flickers (with periods between 0.5 and 5 ms). Control records in the absence of applied magnetic fields are similar to those reported by others. Patches have been exposed to parallel static and low frequency magnetic fields including a combination satisfying the 'cyclotron resonance' condition. The fields were applied for 30 s periods interleaved with 30 s controls. No significant differences in channel properties were observed between the control and field exposed periods. The largest change in position of the peak of the distribution of opening and closing transitions was 3%.

Absence of effects of low-frequency, low-amplitude magnetic fields on the properties of gramicidin A channels

The effects of static and low-frequency magnetic fields on gramicidin A channels have been investigated using bilayer patch clamp recording and a bridge technique capable of detecting 0.3% changes in the conductance of glyceryl monooleate membranes containing many channels. In the bridge technique the conductance was assessed using 10-ms voltage pulses applied at 10 Hz. Measurements were made for LiCl, KCl, and CsCl using magnetic fields of 50, 100, 500, and 5000 microT with the frequency scanned from 10-200 Hz. The combinations of static and low-frequency fields employed include the "cyclotron resonance" conditions at which effects had been predicted to occur. In no case was there any detectable change in conductance when the magnetic fields were applied or changed. Potassium currents through single gramicidin channels have been recorded for patches in which several channels may be open at once. Fields were applied for 2 min periods interleaved with 2 min controls. Methods have been developed to analyze the multichannel records to reveal the amplitude and duration of the channels together with the frequency, depth, and apparent period of flickers. No significant differences were observed between the control and field-exposed recording periods. The peak of the distribution of opening and closing transitions always coincided for fields on and off within the resolution, 0.4%, of the recordings. There are at least two types of flicker, one with typical period less than 0.1 ms, the other with typical period from 0.3-0.8 ms. Most of the latter were not complete closures with the conductance during a flicker 15-20% above the level for a full closure.

The effect of a 5-month supervised program of physical activity on anthropometric indices, fat-free mass, and resting energy expenditure in obese male military recruits

Studies using mainly dietary restriction have shown that weight loss is associated with a decrease in fat-free mass (FFM) and resting energy expenditure (REE). The aim of this study was to investigate the effects of a weight-loss program relying solely on increased physical activity on FFM and REE. Forty-two overweight male military recruits (12 with initial body mass index [BMI] between 25.0 and 29.9 kg/m2, group 1; 14 with BMI between 30.0 and 34.9 kg/m2, group 2; and 16 with BMI of at least 35 kg/m2, group 3) completed a 5-month program of supervised physical activity that included both aerobic and muscle-strengthening components. All subjects lost significant amounts of weight (group 1, 8.6 kg; group 2, 15.7 kg; group 3, 22.0 kg). This weight loss was accompanied by a significant reduction in the waist to hip ratio (WHR) in all groups. FFM was maintained in all groups. REE tended to decline in all groups (group 1, from 1,595.0 +/- 46.9 to 1,511.7 +/- 53.2 kcal/d; group 2, from 1,751.4 +/- 56.0 to 1,680.0 +/- 63.1 kcal/d; group 3, from 1,901.9 +/- 93.7 to 1,740.0 +/- 67.3 kcal/d), but this decline reached statistical significance only when all 42 subjects were considered. REE normalized for FFM did not decrease except in group 1. Furthermore, differences between the slopes and intercepts of the regression lines relating REE with FFM before and at completion of the 5-month program were not statistically significant, suggesting that the relationship between REE and FFM was maintained after weight loss.(ABSTRACT TRUNCATED AT 250 WORDS)

Metabolic abnormalities in young non-obese males with hypertension

Essential hypertension has been shown by various studies to be an insulin-resistant state. However, most of these studies have included obese and elderly patients. We were interested to know the extent of insulin resistance in a group of young, non-obese patients with hypertension. A total of 59 male patients with essential hypertension and 31 controls matched for age, sex and body mass index were studied. All the subjects were under 35 years old and had a body mass index of less than 27 kg/m2. Our results showed that such patients with hypertension had significantly higher fasting insulin, total insulin after glucose challenge, insulin/glucose ratio and higher triglycerides than the control subjects.

Hyperinsulinaemia in non-obese subjects with hypertriglyceridaemia: a preliminary report

It has been known for some time that hyperinsulinaemia is associated with hypertriglyceridaemia. However, previous studies looking at the relationship between hyperinsulinaemia and hypertriglyceridaemia have included overweight subjects. The effect of obesity on the insulin status of hypertriglyceridaemic patients is uncertain. We investigated the insulin status of hypertriglyceridaemic subjects in the absence of confounding factors such as obesity, hypertension and diabetes mellitus. Our results demonstrate that basal insulin levels as well as the insulin response after an intravenous glucose challenge are higher in moderately hypertriglyceridaemic patients when compared to age and body mass index matched controls. Hyperinsulinaemia may have pathogenetic significance for hypertriglyceridaemia as well as other features of a constellation of metabolic derangements such as obesity, hypertension and glucose intolerance.

Manifestations and outcome of treatment of thyrotoxicosis: a clinical study

We studied a series of 89 consecutive patients who presented with thyrotoxicosis at a medical unit. Clinical parameters and laboratory abnormalities were recorded. Treatment was initiated and response in terms of side-effects, clinical and laboratory remissions were monitored. The frequency of the various clinical manifestations, cardiovascular and neurological complications were documented. Laboratory data on electrolytes, haematological changes and thyroid antibodies were noted. The treatment outcome revealed a relapse of 37.7% in patients with 6 months of treatment (90% occurred within the first year). We also noted that 6.7% of patients developed skin reaction. A treatment default rate of 30% was noted.

Oral glucose tolerance test--can the reflectance meter replace laboratory-based methods?

Sixteen national servicemen detected to have glycosuria on routine medical examination were subjected to 3 successive oral glucose tolerance tests. Capillary blood glucose was measured by reflectance meter in the first test (oGTT1), venous whole blood glucose by Beckman Synchron CX3 Analyser in the second (oGTT2) and by both methods in the third (oGTT3). In oGTT1, 1 subject was classified as diabetic and 15 as Impaired Glucose Tolerance (IGT). In oGTT3, using capillary blood glucose, 1 was diabetic, 8 IGT and 7 normal. Using venous whole blood, in oGTT2, 1 was diabetic, 3 IGT and 12 normal as compared to 1 diabetic, 4 IGT and 11 normal in oGTT3. There is considerable variation in classification as a result of using capillary blood glucose measured by reflectance meter as compared to the laboratory-based method. Capillary blood glucose measurement for oral glucose tolerance test cannot be recommended.

Epidemiology of diabetes mellitus in the Asia-Pacific region

The complex interaction between genetic and environmental factors in the causation of diabetes mellitus is well illustrated by the epidemiology of diabetes in the Asia-Pacific region. Among the Chinese, the prevalence of diabetes is uniformly higher among Chinese living outside China than in the Chinese in The People's Republic of China. Similarly among the Indians, the prevalence of diabetes is universally higher in those who have settled outside India than in Indians in India. In the Pacific populations, diabetes is much commoner among the Nauruans and Fiji Indians. Throughout the Asia-Pacific countries, economic progress and urbanisation have a uniformly deleterious effect on diabetes. A better understanding of the hereditary and environmental factors in the causation of diabetes is required to halt and reverse the rising prevalence of diabetes in the Asia-Pacific region.

A study of non-toxic goitre

A population study showed a prevalence of 2.8% for nontoxic goitres. The clinical significance of non-toxic goitres were not previously defined. This study examined 64 patients with non-toxic goitres which were classified clinically as diffuse (gp1), lobular (gp2) and nodular (gp3). They were studied in terms of thyroid antibodies, radioisotope scanning, ultrasonography and fine-needle aspiration cytology. The goitres were mainly nodular (69%), the rest were diffuse and lobular in equal numbers. Seventy percent of the nodular goitres had 1 nodule. One case of diffuse goitre and half the lobular goitres had multinodularity demonstrated on imaging. Antithyroid antibodies were detected in 20% of gp2, 7% of gp3 and none in gp1. Malignancy was found in 2% of gp2, 11% of gp3 and nil in gp1. A management strategy for non-toxic goitre was discussed.

Management and outcome of gestational diabetes in Alexandra Hospital, Singapore

We analysed 216 patients with gestational diabetes over a 3 year period. These patients were managed by a diabetic team under a standardised protocol. Forty percent of these patients required insulin therapy. The incidence of pregnancy hypertension was 14.4%, macrosomia 8.8% and major congenital malformation 3.7%. The Caesarean Section rate was 34% and the overall Perinatal Mortality Rate was 1.9%. However, neonatal morbidity rate remained high--44% of infants have had one neonatal complication and 17.6% had 2 or more complications. Pregnancy outcome was further analysed among patients with different degrees of glucose intolerance at diagnosis. We noted that both macrosomic rate, neonatal morbidity rate, as well as proportion of patients requiring insulin were higher in the group with a higher degree of glucose intolerance. There was, however, no difference in incidence of hypertension or hydramnios in the different subgroups.

Accelerated synthesis and release of angiotensin II in the rat brain during electroacupuncture tolerance

Behavioural studies suggested that cerebral angiotensin II (AII) plays an important role in the development of tolerance to electroacupuncture (EA) analgesia. Observations made in this study revealed an increase in AII immunoreactivity (AII-ir) in both CSF and brain as well as an increase in the cerebral content of AI-ir in rats rendered tolerant to EA. The extracts of brain from rats receiving EA for 1h and 3h were subjected to gel filtration and the elution profile was compared with that of normal brain extract. There was a marked right shift of the AII peak from the large molecule precursor to the small molecule AII-ir. The latter peak showed the same retention time in HPLC system as that of AII. The results suggest that the acceleration of the synthesis and release of AII during a long-term EA stimulation might constitute one of the mechanisms for EA tolerance.

Alcohol consumption in Chinese, Malays and Indians in Singapore

A population based survey has measured alcohol consumption by questionnaire in persons aged 18 to 69 years in Singapore. The majority were "occasional/none" drinkers, being males (Chinese 87%, Malays 99% and Indians 80%) and females (Chinese 98%, Malays 100% and Indians 100%). "Heavy" consumption was uncommon in males (Chinese 0.6%, Malays 0% and Indians 1.3%) and absent in females, while "heavy/moderate" drinking was males (Chinese 5.7%, Malays 0.5% and Indians 3.8%) and females (Chinese 0.3%, Malays 0% and Indians 0%). For males, "light" drinking was highest in Indians (15.9%), then Chinese (7.8%) and then Malays (0.5%). This survey indicates that alcohol consumption is not yet a major public health problem in Singapore.

Physical activity in Chinese, Malays and Indians in Singapore

A population based survey has measured levels of physical activity by questionnaire in persons aged 18 to 69 years in Singapore. Levels of physical activity were classified into high, medium and low based on activity in leisure and at work. The only ethnic difference was that for males a higher proportion were classified as "high" activity in Malays (24.8%) than Chinese (16.0%) and Indians (18.1%). For the overall 18 to 69 age group, it was found that for males, the proportions in the "low" category were Chinese 80%, Malays 70% and Indians 75% while for females it was 95% in all three ethnic groups. As physical activity of sufficient intensity is important in disease prevention and health promotion, more needs to be done on educating the public in Singapore about the benefits of regular exercise.

Obesity and body mass indices in Chinese, Malays and Indians in Singapore

A population based cross-sectional survey has measured body mass indices (BMIs) in Singapore and compared their means and the proportions who are overweight and obese amongst Chinese, Malays and Indians. For males there was little ethnic differences; for the 18-69 age group, the age-adjusted mean BMIs being Chinese 22.3, Malays 23.1 and Indians 22.5. However for females, Malays and Indians were considerably more obese than Chinese; for the 18-69 age group the age-adjusted mean BMIs in Malays (25.1) and Indians (24.6) were significantly greater (p less than 0.001) than in Chinese (22.2). The proportions categorised as overweight or obese (BMI equal to or more than 26 in males and 25 in females) were males (Chinese 16.7%, Malays 22.4%, and Indians 14.0%) and females (Chinese 21.2%, Malays 51.5%, and Indians 42.0%). Health education on the harmful effects of obesity should be targeted especially on Malay and Indian females.

Cardiovascular diseases in Chinese, Malays, and Indians in Singapore. II. Differences in risk factor levels

STUDY OBJECTIVE

The aim of the study was to examine cardiovascular risk factors to see how these might explain differences in cardiovascular disease mortality among Chinese, Malays, and Indians in the Republic of Singapore.

DESIGN

The study was a population based cross sectional survey. Stratified systematic sampling of census districts, reticulated units, and houses was used. The proportions of Malay and Indian households were increased to improve statistical efficiency, since about 75% of the population is Chinese.

SETTING

Subjects were recruited from all parts of the Republic of Singapore.

SUBJECTS

2143 subjects aged 18 to 69 years were recruited (representing 60.3% of persons approached). There were no differences in response rate between the sexes and ethnic groups.

MEASUREMENTS AND MAIN RESULTS

Data on cardiovascular risk factors were collected by questionnaire. Measurements were made of blood pressure, serum cholesterol, low and high density lipoprotein cholesterol, fasting triglycerides and plasma glucose. In males the age adjusted cigarette smoking rate was higher in Malays (53.3%) than in Chinese (37.4%) or Indians (44.5%). In both sexes, Malays had higher age adjusted mean systolic blood pressure: males 124.6 mm Hg v 121.2 mm Hg (Chinese) and 121.2 mm Hg (Indians); females 122.8 mm Hg v 117.3 mm Hg (Chinese) and 118.4 mm Hg (Indians). Serum cholesterol, low density lipoprotein cholesterol and triglyceride showed no ethnic differences. Mean high density lipoprotein cholesterol in males (age adjusted) was lower in Indians (0.69 mmol/litre) than in Chinese (0.87 mmol/litre) and Malays (0.82 mmol/litre); in females the mean value of 0.95 mmol/litre in Indians was lower than in Chinese (1.05 mmol/litre) and Malays (1.03 mmol/litre). Rank prevalence of diabetes for males was Indians (highest), Malays and then Chinese; for females it was Malays, Indians, Chinese.

CONCLUSIONS

The higher mortality from ischaemic heart disease found in Indians in Singapore cannot be explained by the major risk factors of cigarette smoking, blood pressure and serum cholesterol; lower high density lipoprotein cholesterol and higher rates of diabetes may be part of the explanation. The higher systolic blood pressures in Malays may explain their higher hypertensive disease mortality.