Exploring the Lives of Women Rag Pickers in an Indian Metropolitan City: A Mixed-Methods Cross-Sectional Study on Social and Occupational Determinants Shaping Their Existence.

BACKGROUND: Globally, occupational hazards are a concern, especially in waste management. With 31.2% of its population in urban areas, India is confronted with escalating waste management challenges. People worldwide generate about two-thirds of a kilogram of waste daily. Effective solid waste management is crucial due to population growth, changing waste patterns, and rapid urbanisation. It profoundly impacts environmental, resident, and worker health. Rag picking is an informal profession undertaken by a marginalised population of the society, which involves collecting waste from trash cans, streets, and household waste. To assess the burden and the pattern of morbidity, and the occupational factors associated with it, as well as their health-seeking behaviour, the present study was carried out among women rag pickers in Mumbai, India. METHODOLOGY: A cross-sectional descriptive study was conducted through a mixed-method approach in Mumbai's Chembur and Govandi areas, focusing on women rag pickers aged 15 to 49 years. The research was conducted over a period of three months, during which a total of 150 female rag pickers from individual families were identified and included in the study through purposive sampling. The structured questionnaires gathered quantitative data on socio-demographics, health-seeking behaviour, morbidity, and monthly expenses. The qualitative data were collected through focus group discussions with rag pickers, analysing themes related to rag picking as occupational preference and substance usage factors. Ethical approval from the institute and informed consent from each participant were obtained prior to data collection. RESULTS: Among the cohort of 150 women rag pickers, 67.3% were aged between 15 and 30 years, with 82% belonging to the lower socio-economic class. A notable 43.4% of these women engaged in significant tobacco use, primarily through oral consumption, while about 56.7% of their family members exhibited high substance use, including pan, tobacco, and alcohol. In terms of health-seeking behaviour, 51% refrained from seeking treatment for minor ailments, 29% resorted to home remedies or self-medication, and 20% sought care at hospitals. A morbidity analysis over the past three months revealed prevalent health issues, informing potential interventions. Examination of monthly expenditure patterns unveiled an average income of 9000 INR (130 USD), with a significant 61% allocation towards food and grocery expenses. Qualitative insights indicated that the preference for rag picking was driven by limited alternatives and substance use was influenced by peers and served as a means to cope with stress. These findings underscore distinct health-seeking behaviours, and the unique needs of women rag pickers, providing valuable guidance for targeted policies to enhance their well-being. CONCLUSION: These findings underscore the need for targeted interventions to improve the well-being and socio-economic conditions of women rag pickers in India. Universal healthcare coverage, community-based initiatives, and social inclusion are vital for addressing their unique challenges and enhancing their quality of life.

Mechanical Behavior of 3D Printed Poly(ethylene glycol) Diacrylate Hydrogels in Hydrated Conditions Investigated Using Atomic Force Microscopy.

Three-dimensional (3D) printed hydrogels fabricated using light processing techniques are poised to replace conventional processing methods used in tissue engineering and organ-on-chip devices. An intrinsic potential problem remains related to structural heterogeneity translated in the degree of cross-linking of the printed layers. Poly(ethylene glycol) diacrylate (PEGDA) hydrogels were used to fabricate both 3D printed multilayer and control monolithic samples, which were then analyzed using atomic force microscopy (AFM) to assess their nanomechanical properties. The fabrication of the hydrogel samples involved layer-by-layer (LbL) projection lithography and bulk cross-linking processes. We evaluated the nanomechanical properties of both hydrogel types in a hydrated environment using the elastic modulus (E) as a measure to gain insight into their mechanical properties. We observed that E increases by 4-fold from 2.8 to 11.9 kPa transitioning from bottom to the top of a single printed layer in a multilayer sample. Such variations could not be seen in control monolithic sample. The variation within the printed layers is ascribed to heterogeneities caused by the photo-cross-linking process. This behavior was rationalized by spatial variation of the polymer cross-link density related to variations of light absorption within the layers attributed to spatial decay of light intensity during the photo-cross-linking process. More importantly, we observed a significant 44% increase in E, from 9.1 to 13.1 kPa, as the indentation advanced from the bottom to the top of the multilayer sample. This finding implies that mechanical heterogeneity is present throughout the entire structure, rather than being limited to each layer individually. These findings are critical for design, fabrication, and application engineers intending to use 3D printed multilayer PEGDA hydrogels for in vitro tissue engineering and organ-on-chip devices.

Controlled Porosity in Ferroelectric BaTiO3 Photoanodes.

The use of ferroelectric polarization to promote electron-hole separation has emerged as a promising strategy to improve photocatalytic activity. Although ferroelectric thin films with planar geometry have been largely studied, nanostructured and porous ferroelectric thin films have not been commonly used in photo-electrocatalysis. The inclusion of porosity in ferroelectric thin films would enhance the surface area and reactivity, leading to a potential improvement of the photoelectrochemical (PEC) performance. Herein, the preparation of porous barium titanate (pBTO) thin films by a soft template-assisted sol-gel method is reported, and the control of porosity using different organic/inorganic ratios is verified by the combination of scanning electron microscopy and ellipsometry techniques. Using piezoresponse force microscopy, the switching of ferroelectric domains in pBTO thin films is observed, confirming that the ferroelectric polarization is still retained in the porous structures. In addition, the presence of porosity in pBTO thin films leads to a clear improvement of the PEC response. By electrochemical poling, we also demonstrated the tuning of the PEC performance of pBTO thin films via ferroelectric polarization. Our work offers a simple and low-cost approach to control the morphology optimization of ferroelectric thin films, which could open up the development of materials with great potential for PEC applications.

Towards standardisation of contact and contactless electrical measurements of CVD graphene at the macro-, micro- and nano-scale.

Graphene has become the focus of extensive research efforts and it can now be produced in wafer-scale. For the development of next generation graphene-based electronic components, electrical characterization of graphene is imperative and requires the measurement of work function, sheet resistance, carrier concentration and mobility in both macro-, micro- and nano-scale. Moreover, commercial applications of graphene require fast and large-area mapping of electrical properties, rather than obtaining a single point value, which should be ideally achieved by a contactless measurement technique. We demonstrate a comprehensive methodology for measurements of the electrical properties of graphene that ranges from nano- to macro- scales, while balancing the acquisition time and maintaining the robust quality control and reproducibility between contact and contactless methods. The electrical characterisation is achieved by using a combination of techniques, including magneto-transport in the van der Pauw geometry, THz time-domain spectroscopy mapping and calibrated Kelvin probe force microscopy. The results exhibit excellent agreement between the different techniques. Moreover, we highlight the need for standardized electrical measurements in highly controlled environmental conditions and the application of appropriate weighting functions.

Surface-Mediated Aligned Growth of Monolayer MoS2 and In-Plane Heterostructures with Graphene on Sapphire.

Aligned growth of transition metal dichalcogenides and related two-dimensional (2D) materials is essential for the synthesis of high-quality 2D films due to effective stitching of merging grains. Here, we demonstrate the controlled growth of highly aligned molybdenum disulfide (MoS2) on c-plane sapphire with two distinct orientations, which are highly controlled by tuning sulfur concentration. We found that the size of the aligned MoS2 grains is smaller and their photoluminescence is weaker as compared with those of the randomly oriented grains, signifying enhanced MoS2-substrate interaction in the aligned grains. This interaction induces strain in the aligned MoS2, which can be recognized from their high susceptibility to air oxidation. The surface-mediated MoS2 growth on sapphire was further developed to the rational synthesis of an in-plane MoS2-graphene heterostructure connected with the predefined orientation. The in-plane epitaxy was observed by low-energy electron microscopy. Transmission electron microscopy and scanning transmission electron microscopy suggest the alignment of a zigzag edge of MoS2 parallel to a zigzag edge of the neighboring graphene. Moreover, better electrical contact to MoS2 was obtained by the monolayer graphene compared with a conventional metal electrode. Our findings deepen the understanding of the chemical vapor deposition growth of 2D materials and also contribute to the tailored synthesis as well as applications of advanced 2D heterostructures.

Detection of Ultralow Concentration NO2 in Complex Environment Using Epitaxial Graphene Sensors.

We demonstrate proof-of-concept graphene sensors for environmental monitoring of ultralow concentration NO2 in complex environments. Robust detection in a wide range of NO2 concentrations, 10-154 ppb, was achieved, highlighting the great potential for graphene-based NO2 sensors, with applications in environmental pollution monitoring, portable monitors, automotive and mobile sensors for a global real-time monitoring network. The measurements were performed in a complex environment, combining NO2/synthetic air/water vapor, traces of other contaminants, and variable temperature in an attempt to fully replicate the environmental conditions of a working sensor. It is shown that the performance of the graphene-based sensor can be affected by coadsorption of NO2 and water on the surface at low temperatures (≤70 °C). However, the sensitivity to NO2 increases significantly when the sensor operates at 150 °C and the cross-selectivity to water, sulfur dioxide, and carbon monoxide is minimized. Additionally, it is demonstrated that single-layer graphene exhibits two times higher carrier concentration response upon exposure to NO2 than bilayer graphene.

Electrical Homogeneity Mapping of Epitaxial Graphene on Silicon Carbide.

Epitaxial graphene is a promising route to wafer-scale production of electronic graphene devices. Chemical vapor deposition of graphene on silicon carbide offers epitaxial growth with layer control but is subject to significant spatial and wafer-to-wafer variability. We use terahertz time-domain spectroscopy and micro four-point probes to analyze the spatial variations of quasi-freestanding bilayer graphene grown on 4 in. silicon carbide (SiC) wafers and find significant variations in electrical properties across large regions, which are even reproduced across graphene on different SiC wafers cut from the same ingot. The dc sheet conductivity of epitaxial graphene was found to vary more than 1 order of magnitude across a 4 in. SiC wafer. To determine the origin of the variations, we compare different optical and scanning probe microscopies with the electrical measurements from nano- to millimeter scale and identify three distinct qualities of graphene, which can be attributed to the microstructure of the SiC surface.

Confocal laser scanning microscopy for rapid optical characterization of graphene.

Two-dimensional (2D) materials such as graphene have become the focus of extensive research efforts in condensed matter physics. They provide opportunities for both fundamental research and applications across a wide range of industries. Ideally, characterization of graphene requires non-invasive techniques with single-atomic-layer thickness resolution and nanometer lateral resolution. Moreover, commercial application of graphene requires fast and large-area scanning capability. We demonstrate the optimized balance of image resolution and acquisition time of non-invasive confocal laser scanning microscopy (CLSM), rendering it an indispensable tool for rapid analysis of mass-produced graphene. It is powerful for analysis of 1-5 layers of exfoliated graphene on Si/SiO2, and allows us to distinguish the interfacial layer and 1-3 layers of epitaxial graphene on SiC substrates. Furthermore, CLSM shows excellent correlation with conventional optical microscopy, atomic force microscopy, Kelvin probe force microscopy, conductive atomic force microscopy, scanning electron microscopy and Raman mapping.

Calibration of multi-layered probes with low/high magnetic moments.

We present a comprehensive method for visualisation and quantification of the magnetic stray field of magnetic force microscopy (MFM) probes, applied to the particular case of custom-made multi-layered probes with controllable high/low magnetic moment states. The probes consist of two decoupled magnetic layers separated by a non-magnetic interlayer, which results in four stable magnetic states: ±ferromagnetic (FM) and ±antiferromagnetic (A-FM). Direct visualisation of the stray field surrounding the probe apex using electron holography convincingly demonstrates a striking difference in the spatial distribution and strength of the magnetic flux in FM and A-FM states. In situ MFM studies of reference samples are used to determine the probe switching fields and spatial resolution. Furthermore, quantitative values of the probe magnetic moments are obtained by determining their real space tip transfer function (RSTTF). We also map the local Hall voltage in graphene Hall nanosensors induced by the probes in different states. The measured transport properties of nanosensors and RSTTF outcomes are introduced as an input in a numerical model of Hall devices to verify the probe magnetic moments. The modelling results fully match the experimental measurements, outlining an all-inclusive method for the calibration of complex magnetic probes with a controllable low/high magnetic moment.

Excitonic Effects in Tungsten Disulfide Monolayers on Two-Layer Graphene.

Light emission in atomically thin heterostructures is known to depend on the type of materials and the number and stacking sequence of the constituent layers. Here we show that the thickness of a two-dimensional substrate can be crucial in modulating the light emission. We study the layer-dependent charge transfer in vertical heterostructures built from monolayer tungsten disulfide (WS2) on one- and two-layer epitaxial graphene, unravelling the effect that the interlayer electronic coupling has on the excitonic properties of such heterostructures. We bring evidence that the excitonic properties of WS2 can be effectively tuned by the number of supporting graphene layers. Integrating WS2 monolayers with two-layer graphene leads to a significant enhancement of the photoluminescence response, up to 1 order of magnitude higher compared to WS2 supported on one-layer graphene. Our findings highlight the importance of substrate engineering when constructing atomically thin-layered heterostructures.

Visualization of Grain Structure and Boundaries of Polycrystalline Graphene and Two-Dimensional Materials by Epitaxial Growth of Transition Metal Dichalcogenides.

The presence of grain boundaries in two-dimensional (2D) materials is known to greatly affect their physical, electrical, and chemical properties. Given the difficulty in growing perfect large single-crystals of 2D materials, revealing the presence and characteristics of grain boundaries becomes an important issue for practical applications. Here, we present a method to visualize the grain structure and boundaries of 2D materials by epitaxially growing transition metal dichalcogenides (TMDCs) over them. Triangular single-crystals of molybdenum disulfide (MoS2) epitaxially grown on the surface of graphene allowed us to determine the orientation and size of the graphene grains. Grain boundaries in the polycrystalline graphene were also visualized reflecting their higher chemical reactivity than the basal plane. The method was successfully applied to graphene field-effect transistors, revealing the actual grain structures of the graphene channels. Moreover, we demonstrate that this method can be extended to determine the grain structure of other 2D materials, such as tungsten disulfide (WS2). Our visualization method based on van der Waals epitaxy can offer a facile and large-scale labeling technique to investigate the grain structures of various 2D materials, and it will also contribute to understand the relationship between their grain structure and physical properties.

Carrier type inversion in quasi-free standing graphene: studies of local electronic and structural properties.

We investigate the local surface potential and Raman characteristics of as-grown and ex-situ hydrogen intercalated quasi-free standing graphene on 4H-SiC(0001) grown by chemical vapor deposition. Upon intercalation, transport measurements reveal a change in the carrier type from n- to p-type, accompanied by a more than three-fold increase in carrier mobility, up to µh ≈ 4540 cm(2) V(-1) s(-1). On a local scale, Kelvin probe force microscopy provides a complete and detailed map of the surface potential distribution of graphene domains of different thicknesses. Rearrangement of graphene layers upon intercalation to (n + 1)LG, where n is the number of graphene layers (LG) before intercalation, is demonstrated. This is accompanied by a significant increase in the work function of the graphene after the H2-intercalation, which confirms the change of majority carriers from electrons to holes. Raman spectroscopy and mapping corroborate surface potential studies.

Visualisation of edge effects in side-gated graphene nanodevices.

Using local scanning electrical techniques we study edge effects in side-gated Hall bar nanodevices made of epitaxial graphene. We demonstrate that lithographically defined edges of the graphene channel exhibit hole conduction within the narrow band of ~60-125 nm width, whereas the bulk of the material is electron doped. The effect is the most pronounced when the influence of atmospheric contamination is minimal. We also show that the electronic properties at the edges can be precisely tuned from hole to electron conduction by using moderate strength electrical fields created by side-gates. However, the central part of the channel remains relatively unaffected by the side-gates and retains the bulk properties of graphene.

Standardization of surface potential measurements of graphene domains.

We compare the three most commonly used scanning probe techniques to obtain a reliable value of the work function in graphene domains of different thickness. The surface potential (SP) of graphene is directly measured in Hall bar geometry via a combination of electrical functional microscopy and spectroscopy techniques, which enables calibrated work function measurements of graphene domains in ambient conditions with values Φ1LG ~4.55 ± 0.02 eV and Φ2LG ~ 4.44 ± 0.02 eV for single- and bi-layer, respectively. We demonstrate that frequency-modulated Kelvin probe force microscopy (FM-KPFM) provides more accurate measurement of the SP than amplitude-modulated (AM)-KPFM. The discrepancy between experimental results obtained by different techniques is discussed. In addition, we use FM-KPFM for contactless measurements of the specific components of the device resistance. We show a strong non-Ohmic behavior of the electrode-graphene contact resistance and extract the graphene channel resistivity.

Express optical analysis of epitaxial graphene on SiC: impact of morphology on quantum transport.

We show that inspection with an optical microscope allows surprisingly simple and accurate identification of single and multilayer graphene domains in epitaxial graphene on silicon carbide (SiC/G) and is informative about nanoscopic details of the SiC topography, making it ideal for rapid and noninvasive quality control of as-grown SiC/G. As an illustration of the power of the method, we apply it to demonstrate the correlations between graphene morphology and its electronic properties by quantum magneto-transport.

Non-tropical chyluria: CT diagnosis.

Chyluria is commonly associated with filariasis, which is prevalent among the population of tropical and subtropical regions. Chyluria is seldom encountered in the United States and other western countries, but may occur if the flow of chyle into the thoracic duct is blocked due to inflammatory, neoplastic, or various other etiologies. We report 10 adult patients, in whom the detection of fat-urine level in their bladder on abdominal CT provided the initial diagnostic clue to the presence of chyluria. This series included 7 men and 3 women, who ranged in age from 25 to 91 years (mean: 62 years). The associated lesions included renal angiomyolipomas (2), lymphangiomas of the kidney and bladder (1), metastatic testicular cancer (1), postoperative status following partial nephrectomy for renal cell carcinoma (4), left radical nephrectomy (1), and segmental cystectomy for carcinomas (1). The clinical and radiological features of this entity are presented along with a brief review of the pertinent literature.

Attenuation of morphine withdrawal signs by intracerebral administration of 18-methoxycoronaridine.

18-Methoxyroconaridine (18-MC), a synthetic derivative of ibogaine, reduces morphine self-administration and alleviates several signs of acute opioid withdrawal in rats. Although there is already well documented evidence of the mechanism mediating 18-MC's action to reduce the rewarding effects of morphine, nothing is known about the mechanism responsible for 18-MC's attenuation of opioid withdrawal. In vitro studies have demonstrated that 18-MC is a potent antagonist of alpha3beta4 nicotinic receptors (IC50=0.75 microM), which are predominantly located in the medial habenula and interpeduncular nuclei. Previous work indicating that alpha3beta4 nicotinic receptors mediate 18-MC's effects on drug self-administration prompted us to assess whether brain areas having high or moderate densities of alpha3beta4 receptors might be involved in 18-MC's modulation of opioid withdrawal. To test this possibility, 18-MC was locally administered into the medial habenula, interpeduncular nucleus and locus coeruleus of morphine-dependent rats; this treatment was followed by naltrexone to precipitate a withdrawal syndrome. Pretreatment with various doses of 18-MC into the locus coeruleus significantly reduced wet-dog shakes, teeth chattering, burying and diarrhea, while pretreatment into the medial habenula attenuated teeth chattering, burying, and weight loss. Some doses of 18-MC administered into the interpeduncular nucleus significantly ameliorated rearing, teeth chattering, and burying, while other doses exacerbated diarrhea and teeth chattering. The present findings suggest that 18-MC may act in all three nuclei to suppress various signs of opioid withdrawal.

Is antagonism of alpha3beta4 nicotinic receptors a strategy to reduce morphine dependence?

18-Methoxycoronaridine, a synthetic iboga alkaloid congener, has been previously shown to attenuate several signs of morphine withdrawal in rats. The recently discovered action of 18-methoxycoronaridine to block alpha3beta4 nicotinic receptors may be responsible for this effect. To test this hypothesis the effects of non-selective alpha3beta4 receptor antagonists, dextromethorphan, mecamylamine, bupropion, and their combinations, were assessed on of acute naltrexone-precipitated (1 mg/kg i.p.) morphine withdrawal in rats. Dextromethorphan (5-40 mg/kg, s.c.), mecamylamine (0.25-4 mg/kg, i.p.) and bupropion (10-30 mg/kg, i.p.) alone produced variable effects on signs of withdrawal. However, two low-dose combinations, i.e., dextromethorphan (5 mg/kg, s.c.) and mecamylamine (0.25 mg/kg, i.p.), mecamylamine (0.25 mg/kg, i.p.) and bupropion (10 mg/kg, i.p.) as well as the three-drug combination significantly attenuated diarrhea and weight loss; none of the agents administered alone had these effects. The results of the present study provide evidence that alpha3beta4 nicotinic receptors are involved in the expression of at least two signs of opioid withdrawal.