Here we report on the ion conductance through individual, small diameter single-walled carbon nanotubes. We find that they are mimics of ion channels found in natural systems. We explore the factors ...governing the ion selectivity and permeation through single-walled carbon nanotubes by considering an electrostatic mechanism built around a simplified version of the Gouy–Chapman theory. We find that the single-walled carbon nanotubes preferentially transported cations and that the cation permeability is size-dependent. The ionic conductance increases as the absolute hydration enthalpy decreases for monovalent cations with similar solid-state radii, hydrated radii, and bulk mobility. Charge screening experiments using either the addition of cationic or anionic polymers, divalent metal cations, or changes in pH reveal the enormous impact of the negatively charged carboxylates at the entrance of the single-walled carbon nanotubes. These observations were modeled in the low-to-medium concentration range (0.1–2.0 M) by an electrostatic mechanism that mimics the behavior observed in many biological ion channel-forming proteins. Moreover, multi-ion conduction in the high concentration range (>2.0 M) further reinforces the similarity between single-walled carbon nanotubes and protein ion channels.
The hydrocarbon sensing properties of CdSe semiconductor quantum dots (QDs) tailored with benzoic, phenylacetic, 4-phenylbutanoic, or 6-phenylhexanoic acids as a surface enhancement agent have been ...studied to determine their dependence on the phenyl group distance from the QD surface. QDs of roughly the same size were used to attach each of the mentioned surface agents with similar surface coverages, as determined by nuclear magnetic resonance technique, followed by drop-coating and drying of the QD solutions onto porous anodic aluminum oxide substrates for sensing tests. Results indicated that normalized photoluminescence (PL) enhancement did not vary noticeably for QDs with longer chained phenyl groups compared to those with shorter length groups upon film exposure to xylenes vapors over the range of 15 to 9400 ppm in a balance of air. The quantum yield of CdSe QDs with the 6-phenylhexanoic acid surface ligand has a higher value, 29.4%, compared to those with benzoic acid, 4.5%. Moreover, the PL sensitivity toward xylenes exposure for QDs with 6-phenylhexanoic acid versus those with the surface-bound benzoic acid was about 8 times and 16 times greater at xylenes concentrations below 2500 ppm and above 4500 ppm, respectively. These results suggest that the QDs with longer length surface-enhancing ligands are more promising for this type of hydrocarbon sensing applications.
In this study, we designed a series of experiments to determine the factors governing ion permeation through individual carbon nanotubes (CNTs) less than 1.5 nm in diameter and 20 µm in length. We ...then rationalize the experimental results by using a model, which is drawn from previous literature on protein ion channels and is centered around a simplified version of the Gouy-Chapman theory of electrical double layer. Lastly, we experimentally demonstrate and discuss the general similarities in ion permeation characteristics between CNTs and biological ion-selective pores. The role of many potential factors influencing the ion transport is assessed by taking two experimental approaches: (1) studying the effect of electrolyte concentration and composition on channel conductance and reversal potential, and (2) examining a second type of nanochannel as a parallel ion conduction pathway within the same device architecture and measurement set-up, which we refer to as leakage devices. This helps to differentiate the effect of CNT on ionic transport from any other possible source. Taken together, these two experimental methods provide strong evidence that the electrostatic potential arising from ionized carboxyl groups at the nanopore entrance has a significant effect on ionic permeation in a manner consistent with a simple electrostatic mechanism.
In this study, we designed a series of experiments to determine the factors governing ion permeation through individual carbon nanotubes (CNTs) less than 1.5 nm in diameter and 20 µm in length. We ...then rationalize the experimental results by using a model, which is drawn from previous literature on protein ion channels and is centered around a simplified version of the Gouy-Chapman theory of electrical double layer. Lastly, we experimentally demonstrate and discuss the general similarities in ion permeation characteristics between CNTs and biological ion-selective pores. The role of many potential factors influencing the ion transport is assessed by taking two experimental approaches: (1) studying the effect of electrolyte concentration and composition on channel conductance and reversal potential, and (2) examining a second type of nanochannel as a parallel ion conduction pathway within the same device architecture and measurement set-up, which we refer to as leakage devices. This helps to differentiate the effect of CNT on ionic transport from any other possible source. Taken together, these two experimental methods provide strong evidence that the electrostatic potential arising from ionized carboxyl groups at the nanopore entrance has a significant effect on ionic permeation in a manner consistent with a simple electrostatic mechanism.
Background For the first time, the present study investigated smoking trajectory and cardiometabolic profile from adolescence to young adulthood in a middle‐income developing country facing a high ...prevalence of smoking and cardiovascular disease‐related outcomes. Methods and Results Data on 1082 adolescents (12–18 years of age) who participated in the TLGS (Tehran Lipid and Glucose Study) were gathered, and participants were followed for a median of 12.5 years (baseline: 1999–2002, last follow‐up: 2014–2017). Participants were categorized as non/rare smokers, experimenters, and escalators using group‐based trajectory models. Statistical analysis was used to compare the trajectory groups' cardiometabolic components, clinical characteristics, and cardiometabolic changes due to the individuals' placement in experimenter and escalator groups compared with non/rare smokers. The smoking trajectory groups in young adulthood differ significantly in blood pressure, triglycerides, high‐density lipoprotein cholesterol, waist circumference, and body mass index, with the escalator group having the highest risk values for each component. Significant differences were observed in blood pressure ( P =0.014), triglycerides ( P <0.001), and waist circumference ( P <0.001) status after using clinical cut points. The adjusted linear regression revealed that the escalator group had 3.16 mm Hg‐lower systolic blood pressure SBP ( P =0.016), 2.69 mm Hg‐lower diastolic blood pressure ( P =0.011), and 4.42 mg/dL‐lower high‐density lipoprotein cholesterol ( P =0.002), compared with the non/rare smoker group. Conclusions Despite elevated risks in unadjusted analyses for all cardiometabolic components among smokers, our study identified a modest protective link between early smoking and blood pressure in addition to a remarkable harmful association with high‐density lipoprotein cholesterol levels exclusively in the escalator group during the developmental stage to young adulthood, using adjusted analyses.
Ceftriaxone (CFTR) is among the most commonly used antibiotics in the treatment of different types of bacterial infections and widespread pneumonias. It was also known as one of the most frequently ...prescribed antibiotics during the Corona pandemic. This drug has a longer half-life than other antibiotics. In this research, the heterogeneous magnetic nanophotocatalyst AgCoFe
2
O
4
@Chitosan(Ch)/activated carbon (AC) was synthesized by co-precipitation method under microwave waves. The catalyst structure was characterized by XRD, FTIR, FESEM, EDS, mapping, line scan, BET, VSM and DRS analyzers. Then, the effect of pH, CFTR concentration, nanophotocatalyst dose and irradiation time on the photocatalytic process efficiency was investigated. The analyses showed that the catalyst was synthesized on a nanometer scale, high surface area (60.044 m
2
/g), high magnetic strength (Ms = 10.39 emu/g) and appropriate optical activity with band gap (3.1 eV). The highest removal efficiency at pH = 3, CFTR concentration of 5 mg/L, dose of 0.24 g/L, and irradiation time of 60 min was obtained at 98.8% and 79.01% for synthetic and real wastewater samples, respectively. The reaction kinetics followed the
pseudo
-first-order and Langmuir–Hinshelwood kinetic models with
K
C
= 0.23 mg/L min and
K
L−H
= 0.168 L/mg. The recovered catalyst was able to remove CFTR with an efficiency of 80.16% after 4 reuse cycles. The results of scavenger radical tests showed that the main active radical species was
·
OH
. The obtained results from the effluent toxicity on the germination index of lettuce, watercress, radish and tomato seeds showed a significant reduction in the environmental hazards of the effluent. Due to the high efficiency, this nanophotocatalyst can be used for the treatment of pharmaceutical and hospital wastewaters, and the effluent has the least toxicity for the environment.
Following the global upward trend of cardiovascular diseases (CVD/CHD), much attention has been paid to lifestyle behaviors such as physical activity (PA). However, most of previous studies were ...conducted in developed countries and with just one measurement of physical activity. The aim of the current study is to assess the effect of changes in the PA on the incidence of CVD/CHD in middle-aged and older men and women in an Eastern-Mediterranean population, over a decade follow-up.
This study has been conducted within the framework of the Tehran Lipid and Glucose Study (TLGS) including 4073 (57% women) participants without CVD/CHD at baseline. The participants were followed up for an average period of 12 years. The Iranian version of Modified Activity Questionnaire (MAQ) was used to measure PA at baseline and at the closest follow-up to the outcome. Subsequently, participants were categorized as "compliers", "non-compliers", "adopters" and "relapsers", based on their adherence to the PA guideline recommendations. All analysis has been conducted in two separate age groups including middle-aged and elderly in both men and women. The effect of PA patterns on incidence of CVD/CHD was investigated using Cox proportional hazard model. Variables including marital status, job status, education, smoking, and family history of CVD/CHD were adjusted in the models.
Adherence to guideline recommendation increased from 63.5 to 66.6% between the two measurements. At the second measurement of PA, the percentages of compliers, non-compliers, adopters and relapsers were 48.4, 18.3, 18.2, and 15.1%, respectively. In fully adjusted models, HRs of CVD and CHD for men aged 40-60 years in the complier group were 0.58 (95% CI: 0.38-0.87, P = 0.008) and 0.58 (95% CI: 0.38-0.89, P = 0.01), respectively. HRs of CVD and CHD for men aged 40-60 years in adopter group were 0.61 (95% CI: 0.38-0.96, P = 0.03) and 0.60 (95% CI: 0.37-0.97, P = 0.04) respectively. The corresponding values were not significant in women.
Adhering to established PA recommendations have a protective effect on the incidence of CVD/CHD among middle-aged men; findings which need to be considered in reducing cardiovascular outcomes in this population.
Celotno besedilo
Dostopno za:
DOBA, IZUM, KILJ, NUK, PILJ, PNG, SAZU, SIK, UILJ, UKNU, UL, UM, UPUK
Abstract
Background
Preventing overweight in childhood and subsequent stages of life is still a global challenge. Despite numerous relevant lifestyle interventions, data on their impact on different ...BMI change pathways over time is rare. The present study aimed to investigate the effect of a multi-setting lifestyle intervention on BMI trajectories from childhood to young adulthood.
Methods
A multi-setting lifestyle intervention at the school, family, and community levels have been conducted in the Tehran Lipid and Glucose Study framework. A total of 2145 children (4–18 years, 49% boys, and 18% intervention) were recruited for the baseline assessment and were followed through five follow-up examinations during a median of 16.1 years. Using a group-based trajectory model, BMI trajectories from childhood to young adulthood were identified, and their association with the implemented intervention was assessed.
Results
Four trajectory groups of BMI from childhood to young adulthood were identified, including
Normal weight
(41%),
Young adulthood overweight
(36%),
Early childhood increasing overweight and adulthood obesity
(19%), and
Early childhood increasing obesity
(4%). Only
Young adulthood overweight
and
Early childhood increasing obesity
were affected by the intervention and were concomitant with lower BMI levels than the control group, with the highest estimated effect in the latter (β=-0.52 and p = 0.018; β=-1.48 and p < 0.001, respectively).
Conclusion
The current findings indicate the highest effectiveness of a practical, healthy lifestyle intervention on those whose obesity started in the early years of life or youth. Our results could help policymakers and planners design more targeted lifestyle modification and weight control interventions.
Trial registration
This study is registered at Iran Registry for Clinical Trials, a WHO primary registry (
http://irct.ir
). The Iran Registry for Clinical Trials ID and date are IRCTID:IRCT138705301058N1, 29/10/2008.
Celotno besedilo
Dostopno za:
DOBA, IZUM, KILJ, NUK, PILJ, PNG, SAZU, SIK, UILJ, UKNU, UL, UM, UPUK
ABSTRACT
BACKGROUND
This study assesses the long‐term effectiveness of a lifestyle intervention on cigarette, passive, and hookah smoking in adolescent boys and girls.
METHODS
One thousand one ...hundred and fifty‐nine adolescent participants of Tehran Lipid and Glucose Study (TLGS) (2001‐2004) were followed for 12 years. Participants in the intervention area received lifestyle interventions in family, schools, and community settings, with the largest part implemented in schools. After excluding those with missing baseline parental data (n = 66), complete parental data of 1093 adolescents was used for cluster analysis. Families were classified as low‐ and high‐risk. Two hundred and ninety‐six individuals who did not complete intervention/follow‐ups were excluded, GEE was performed on 797 adolescents (369 boys, 192 intervention) to assess the intervention effect on tobacco‐related habits.
RESULTS
Adolescents' mean baseline age was 15.21 ± 1.95. Those living in high‐risk families were more at risk of cigarette, passive, and hookah smoking. Intervention decreased odds of cigarette and passive smoking by 38% and 57%, respectively. Intervention did not reduce hookah smoking in adolescents. After sex‐specific analysis, the intervention reduced current cigarette smoking by 40% only in boys and passive smoking in both sexes.
CONCLUSIONS
Targeting lifestyle behaviors in school‐aged adolescents and their families reduces cigarette smoking in boys and protects both sexes from secondhand smoke.
Cigarette smoking follows a progressive pattern throughout the lifetime; most adult smokers started smoking during adolescence.
To understand the cigarette smoking trajectories and their predictors ...among adolescents and young adults in the Islamic Republic of Iran.
Using data from the Tehran Lipid and Glucose Study, we followed 1169 adolescents (12-18 years old) into their young adulthood (28-32 years old), from 2002 to 2016. We used cigarette smoking as the outcome variable for group-based trajectory modelling. After detecting the trajectories, we investigated the effects of independent variables, namely, individual employment; education; physical activity; and paternal smoking, employment and education, on the trajectories. We analysed the data using STATA version 16 and SPSS version 26.
Three trajectories were detected: non-smokers (79%), experimenters (12%) and escalators (9%). Boys were approximately 3 times (OR = 2.94, 95% CI: 2.32-3.24, P < 0.001) and 25 times (OR = 25.00, 95% CI: 23.92-26.08, P < 0.001), respectively, more likely than girls to be in the experimenter and escalator groups. Receiving a university education decreased the odds of being in the escalator trajectory for 18% (OR = 0.82, 95% CI: -0.04-0.96, P = 0.002) of the study participants. Employment after high school increased the odds by approximately two folds for the experimenter (OR = 2.00, 95% CI: 1.42-2.50, P = 0.01) and escalator (OR = 2.33, 95% CI: 1.33-2.93, P = 0.03) trajectories. Paternal smoking was associated with 1.88 and 2.23, respectively, increased odds of experimenting and escalating smoking among the adolescents.
Iranian adolescents follow 3 cigarette smoking trajectories into young adulthood: non-smokers, experimenters and escalators. Male sex, employment after high school, and living with a smoker father were associated with unfavourable smoking patterns. Findings from this study provide valuable insights for designing targeted interventions to reduce cigarette smoking among adults and adolescents in the Islamic Republic of Iran.
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