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Lightweight materials that are both highly compressible and resilient under large cyclic strains can be used in a variety of applications 1 , 2 , 3 , 4 , 5 , 6 , 7 , 8 . Carbon nanotubes offer a combination of elasticity, mechanical resilience and low density 9 , and these properties have been exploited in nanotube-based foams 10 , 11 , 12 , 13 , 14 and aerogels 15 , 16 . However, all nanotube-based foams and aerogels developed so far undergo structural collapse 15 or significant plastic deformation with a reduction in compressive strength 10 , 11 , 13 , 14 when they are subjected to cyclic strain. Here, we show that an inelastic aerogel made of single-walled carbon nanotubes can be transformed into a superelastic material by coating it with between one and five layers of graphene nanoplates. The graphene-coated aerogel exhibits no change in mechanical properties after more than 1 × 10 6 compressive cycles, and its original shape can be recovered quickly after compression release. Moreover, the coating does not affect the structural integrity of the nanotubes or the compressibility and porosity of the nanotube network. The coating also increases Young's modulus and energy storage modulus by a factor of ∼6, and the loss modulus by a factor of ∼3. We attribute the superelasticity and complete fatigue resistance to the graphene coating strengthening the existing crosslinking points or ‘nodes’ in the aerogel. A mechanically fragile aerogel made of single-walled carbon nanotubes can be transformed into a superelastic material by coating it with graphene.

ObjectivesUtility of CT coronary angiography (CTA) and coronary artery calcium (CAC) scoring in risk stratification prior to non-cardiac surgery is unclear. Although current guidelines recommend stress testing in intermediate-high risk individuals, over one-third of perioperative major adverse cardiovascular events (MACE) occur in patients with a negative study. This systematic review and meta-analysis evaluates the value of CTA and CAC score in preoperative risk prognostication prior to non-cardiac surgery.MethodsMEDLINE, PubMed and EMBASE databases were searched for articles published up to June 2018. Summary ORs for degree of coronary artery disease (CAD) and perioperative MACE were pooled using a random-effects model.ResultsEleven studies were included. Two hundred and fifty-two (7.2%) MACE occurred in 3480 patients. Risk of perioperative MACE rose with the severity and extent of CAD on CTA (no CAD 2.0%; non-obstructive 4.1%; obstructive single-vessel 7.1%; obstructive multivessel 23.1%, p<0.001). Multivessel disease (MVD) demonstrated the greatest risk (OR 8.9, 95% CI 5.1 to 15.3, p<0.001). Increasing CAC score was associated with higher perioperative MACE (CAC score: ≥100 OR 5.1, ≥1000 OR 10.4, both p<0.01). In a cohort deemed high risk by established clinical indices, absence of MVD on CTA demonstrated a negative predictive value of 96% (95% CI 92.8 to 98.4) for predicting freedom from MACE.ConclusionsSeverity and extent of CAD on CTA conferred incremental risk for perioperative MACE in patients undergoing non-cardiac surgery. The ‘rule-out’ capability of CTA is comparable to other non-invasive imaging modalities and offers a viable alternative for risk stratification of patients undergoing non-cardiac surgery.Trial registration numberCRD42018100883

Premelting is the localized loss of crystalline order at surfaces and defects at temperatures below the bulk melting transition. It can be thought of as the nucleation of the melting process. Premelting has been observed at the surfaces of crystals but not within. We report observations of premelting at grain boundaries and dislocations within bulk colloidal crystals using real-time video microscopy. The crystals are equilibrium close-packed, three-dimensional colloidal structures made from thermally responsive microgel spheres. Particle tracking reveals increased disorder in crystalline regions bordering defects, the amount of which depends on the type of defect, distance from the defect, and particle volume fraction. Our observations suggest that interfacial free energy is the crucial parameter for premelting in colloidal and atomic-scale crystals.

Caffeine is commonly used in Dictyostelium to inhibit the synthesis of the chemoattractant cAMP and, therefore, its secretion and the autocrine stimulation of cells, in order to prevent its interference with the study of chemoattractant-induced responses. However, the mechanism through which caffeine inhibits cAMP synthesis in Dictyostelium has not been characterized. Here, we report the effects of caffeine on the cAMP chemoattractant signaling network. We found that caffeine inhibits phosphatidylinositol 3-kinase (PI3K) and mechanistic target of rapamycin complex 2 (mTORC2). Both PI3K and mTORC2 are essential for the chemoattractant-stimulated cAMP production, thereby providing a mechanism for the caffeine-mediated inhibition of cAMP synthesis. Our results also reveal that caffeine treatment of cells leads to an increase in cAMP-induced RasG and Rap1 activation, and inhibition of the PKA, cGMP, MyoII, and ERK1 responses. Finally, we observed that caffeine has opposite effects on F-actin and ERK2 depending on the assay and Dictyostelium strain used, respectively. Altogether, our findings reveal that caffeine considerably affects the cAMP-induced chemotactic signaling pathways in Dictyostelium, most likely acting through multiple targets that include PI3K and mTORC2.

The normal modes and the density of states (DOS) of any material provide a basis for understanding its thermal and mechanical transport properties. In perfect crystals, normal modes are plane waves, but they can be complex in disordered systems. We have experimentally measured normal modes and the DOS in a disordered colloidal crystal. The DOS shows Debye-like behavior at low energies and an excess of modes, or Boson peak, at higher energies. The normal modes take the form of plane waves hybridized with localized short wavelength features in the Debye regime but lose both longitudinal and transverse plane-wave character at a common energy near the Boson peak.

Hypertension is mainly asymptomatic and remains undiagnosed until the disease progresses. The objective of the study was to determine the prevalence of and risk factors for hypertension in rural Bangladesh. Using a population-based cluster random sampling strategy, 3096 adults aged ⩾30 years were recruited from a rural district in Bangladesh. Data collected included two blood pressure (BP) measurements, fasting blood glucose, socio-demographic and anthropometric measurements. Hypertension was defined as systolic BP (SBP) ⩾140 mm Hg or diastolic BP (DBP) ⩾90 mm Hg or self-reported diagnosed hypertension. Logistic regression techniques were used for data analyses. The crude prevalence of hypertension was 40% (95% confidence interval (CI) 38–42%) of which 82% were previously undiagnosed. People from lower socio-economic status (SES) had a significantly higher percentage of undiagnosed hypertension compared with people with higher SES ( P <0.001). There was no significant gender difference in severity of hypertension. Males with higher education level compared with no education had a higher prevalence of hypertension (odds ratio 2.34, 95% CI 1.49–3.69). Older age and waist circumference in both genders, and diabetes, lack of physical activity in females were found to be associated with higher prevalence of hypertension. Our research suggests the prevalence of undiagnosed hypertension was higher in the rural area in Bangladesh than that reported from the rural area in neighbouring India and China. Lower SES was associated with a higher risk of undiagnosed hypertension. Public health programs at the grass-roots level must emphasise the provision of primary care and preventive services in managing this non-communicable disease.

OBJECTIVE:--To examine the relationship of retinal vascular caliber with diabetes, glycemia, and diabetic retinopathy. RESEARCH DESIGN AND METHODS--Population-based study using data from the Multi-Ethnic Study of Atherosclerosis (MESA), comprising 5,976 individuals (whites, blacks, Hispanics, and Chinese) residing in six U.S. communities who were free of clinical cardiovascular disease at baseline. Retinal vascular caliber was measured from digital retinal photographs. RESULTS:--There were 4,585 individuals with normal fasting glucose (NFG), 499 with impaired fasting glucose (IFG), 165 with diabetes with retinopathy signs, and 727 with diabetes without retinopathy signs. After multivariate analysis, retinal arteriolar caliber increased from 143.8 μm in subjects with NFG to 144.5 μm in IFG and 146.1 μm in diabetes (P < 0.001 for trend). Retinal venular caliber increased from 214.4 μm in NFG to 216.7 μm in IFG and 218.0 μm in diabetes (P < 0.001 for trend). Retinal venular caliber was significantly larger with increasing levels of fasting glucose and A1C. In a subgroup analysis by ethnicity, the association between wider arteriolar caliber and diabetes was evident in whites only, whereas wider venular caliber and diabetes was evident in Hispanics and Chinese only. In people with diabetes, eyes with retinopathy had larger retinal venular but not arteriolar caliber. CONCLUSIONS:--Retinal arteriolar and venular calibers are larger in individuals with diabetes, but the pattern of associations appears to vary by ethnicity. Retinal venular caliber is additionally associated with retinopathy signs. These findings add further to the concept that variations in retinal vascular caliber may reflect early diabetic microvascular damage.

Escalating antibiotic resistance presents a notable worldwide dilemma, pointing a large involvement of general population. The objective of this study was to assess knowledge, attitudes, and practices regarding the utilization of antibiotics among Bangladeshi residents. A cross-sectional study, conducted from January 01 to April 25, 2022, included 1,947 Bangladeshi adults with a history of antibiotic use, via online surveys and face-to-face interviews using a pretested semi-structured questionnaire. Descriptive statistics, Chi-square tests, and multivariate linear regression models were employed. Mean scores for knowledge, attitudes, and practices were 6.59±1.20, 8.34±1.19, and 12.74±2.59, with correct rates of 73.22%, 92.67%, and 57.91%. Positive predictors for knowledge included being unmarried (β = 0.10, p = 0.001), higher education (College: β = 0.09, p = 0.025; Bachelor: β = 0.22, p<0.001; Master or above: β = 0.14, p<0.001), various professions (student: β = 0.57, p<0.001; housewife: β = 0.33, p<0.001; employee: β = 0.53, p<0.001; businessman: β = 0.31, p<0.001; unemployed: β = 0.15, p<0.001), and residing in semi-urban (β = 0.32, p<0.001) or urban areas (β = 0.15, p<0.001). Positive predictors for attitudes included being married (β = 0.18, p<0.001), specific professions (student: β = 1.06, p<0.001; housewife: β = 0.33, p<0.001; employee: β = 0.86, p<0.001; businessman: β = 0.37, p<0.001; unemployed: β = 0.47, p<0.001), higher SES (Lower-middle: β = 0.22, p<0.001; Middle: β = 0.26, p<0.001), and residing in semi-urban areas (β = 0.18, p<0.001); negative predictors included higher education (College: β = -0.12, p = 0.001; Master or above: β = -0.09, p = 0.008) and being rich (β = -0.13, p<0.001). Positive predictors for practices included being married (β = 0.18, p<0.001), specific professions (student: β = 0.32, p<0.001; employee: β = 0.43, p<0.001; businessman: β = 10, p = 0.034; unemployed: β = 0.11, p = 0.009), and higher SES (Lower-middle: β = 0.14, p = 0.009; Middle: β = 0.38, p<0.001; Higher-middle: β = 0.15, p = 0.008); negative predictors included higher education (College: β = -0.21, p<0.001), being rich (β = -0.12, p<0.001), residing in semi-urban (β = -0.14, p<0.001) or urban areas (β = -0.16, p<0.001). Participants exhibited adequate knowledge and positive attitudes but lagged behind in proper practice of antibiotic use. Proper initiatives should be tailored to enhance prudent antibiotic use and mitigate the risk of antimicrobial resistance.

OBJECTIVE: There are conflicting data regarding relationships of systemic biomarkers of inflammation, hemostasis, and homocysteine with diabetic retinopathy. We examined these relationships in the Multi-Ethnic Study of Atherosclerosis. RESEARCH DESIGN AND METHODS: A total of 921 participants with diabetes were included. Diabetic retinopathy was graded from retinal photographs. We defined two outcomes: any diabetic retinopathy and vision-threatening diabetic retinopathy (severe nonproliferative diabetic retinopathy or worse). Systemic markers analyzed were C-reactive protein, homocysteine, fibrinogen, plasmin-α₂-antiplasmin complex (PAP), interleukin-6, D-dimer, factor VIII, serum creatinine, and urinary albumin-to-creatinine (UAC) ratio. RESULTS: Prevalence of diabetic retinopathy was 33.2% and vision-threatening diabetic retinopathy 7.1%. After adjusting for established risk factors (diabetes duration, A1C, systolic blood pressure, waist-to-hip ratio, and use of diabetes medications), fibrinogen (odds ratio 1.14 [95% CI 1.01-1.32], P = 0.05) and PAP (1.25 [1.05-1.50], P = 0.01) were associated with any diabetic retinopathy, while PAP (1.54 [1.13-2.11], P = 0.007) and homocysteine (1.57 [1.16-2.11], P = 0.003) were associated with vision-threatening diabetic retinopathy. Only PAP remained significant after additional adjustment for serum creatinine and UAC ratio. Area under receiver-operator characteristic curve (AUROC) for diabetic retinopathy was constructed for established and novel risk factors. Established risk factors accounted for a 39.2% increase of the AUROC, whereas novel markers (fibrinogen, PAP, homocysteine, serum creatinine, and UAC ratio) only accounted for an additional 2.2%. CONCLUSIONS: There were few associations of novel markers of inflammation, hemostasis, and homocysteine with diabetic retinopathy after controlling for established risk factors. These data suggest that there is limited clinical use of these biomarkers for prediction of diabetic retinopathy.

To examine the prospective association of retinal vascular fractal dimension with diabetic retinopathy risk in young people with type 1 diabetes. This was a hospital-based prospective study of 590 patients aged 12-20 years with type 1 diabetes free of retinopathy at baseline. All patients had seven-field retinal photographs taken of both eyes. Incident retinopathy was ascertained from retinal photographs taken at follow-up visits. Fractal dimension was measured from baseline photographs using a computer-based program following a standardized protocol. Over a mean +/- SD follow-up period of 2.9 +/- 2.0 years, 262 participants developed mild nonproliferative diabetic retinopathy (15.0 per 100 person-years). After adjusting for age, sex, diabetes duration, A1C, and other risk factors, we found no association between retinal vascular fractal dimension and incident retinopathy. Retinal vascular fractal dimension was not associated with incident early diabetic retinopathy in this sample of children and adolescents with type 1 diabetes.