Field induced assembly of particulate systems

The primary focus of the first part of this dissertation is to study the AC field-driven assembly of monodisperse silica and glass particles on liquid - liquid interface and forming a liquid film of uniform thickness having arrangement of particles on it. This liquid film with arrangement of regular particles can be converted into a solid film by curing top UV curable liquid. Here, electric field is used as a tool to facilitate AC field-driven assembly. The work describes the assembly of different size of regular particles and effective development of solid film. It is also shown that particles of two dissimilar sizes and dielectric properties can be assembled on Air-liquid interface and form assembly of dual particles with ring structure. In this work, two dissimilar particles are trapped between an interface and AC electric field is applied to particle suspensions in a gap between the top and bottom electrodes. In order to exploit the concept of dual particle assembly, mixture of glass particles and plastic latex particles are studied. It is noticeable that the lateral dipolar force leads two particles to either repel or attract. This force of repulsion and attraction between particles depend on their polarizabilities and the intensity of the force. Finally, rapid and effective formation of ring structure of dual particles is shown. The study is also extended for mixture of particles that are less than 10 μm. In all cases, it is observed that smaller particles act as the binder for larger particles and form dual particle ring structure since they have a reverse polarizability. In the third part of this dissertation, AC electric field is used to assemble the particles on the freely suspended single floating droplet on immiscible liquid. Particles on the droplet can be levitated and assembled at the pole or equator due to dielectric properties and conductivity of particles and liquid medium when low frequency is applied. Under high frequency, particles drag towards the pole or equator due to Clausius Mossotti factor of particle and droplet. The high and low frequency are distinguished by crossover frequency. Here, crossover frequency is investigated experimentally and assembly of the different particles at the pole or equator of the droplet is shown. At any initial location of the particle and considering the very low frequency, flow deceases with increase in frequency - this is studied experimentally. A diffusing particle is subjected to a variety of collisions that leads to a random or Brownian motion. Assembly of particles of various sizes with various viscous media are studied in the first and second part. It is experimentally observed that Brownian motion decreases with increase in particle size. The aim of this study is to highlight the visualization of Brownian motion and compute the transmission probability from inner to outer region under the conditions of varying viscosity, particle size and temperature. The obtained results are validated with Stokes-Einstein equation and Fang and Ning’s experimental and theoretical work. It is shown that the transmission probability increases with decrease in viscosity and particle size and increase in temperature

Enabling Secure Database as a Service using Fully Homomorphic Encryption: Challenges and Opportunities

The database community, at least for the last decade, has been grappling with querying encrypted data, which would enable secure database as a service solutions. A recent breakthrough in the cryptographic community (in 2009) related to fully homomorphic encryption (FHE) showed that arbitrary computation on encrypted data is possible. Successful adoption of FHE for query processing is, however, still a distant dream, and numerous challenges have to be addressed. One challenge is how to perform algebraic query processing of encrypted data, where we produce encrypted intermediate results and operations on encrypted data can be composed. In this paper, we describe our solution for algebraic query processing of encrypted data, and also outline several other challenges that need to be addressed, while also describing the lessons that can be learnt from a decade of work by the database community in querying encrypted data

Shifting trends of lung tumours and its diagnosis by lung biopsy: a study of 78 cases

Background: The objective of the study was to study the spectrum of pathological lesions in patients with lung mass and to study correlation between clinical findings, histopathological pattern and immunohistochemical stains in various biopsy specimen for differentiation and typing of tumors.Methods: This retrospective study was done for the period of three years at Department of Pathology, New Civil Hospital, Surat, India, which is a tertiary health care Centre. Here we studied 78 cases of lung biopsy received in formalin, which were subjected to histopathological examination. Immunohistochemistry was performed as and when required.Results: Total 78 lung biopsy specimens were examined. Out of which, 59 cases (75.6%) were neoplastic, 12 cases(15.4%) were non-neoplastic and 7 cases (9%) were inconclusive. The commonest histological type of malignancy was adenocarcinoma which is associated with peripheral mass lesion, female gender and in non-smokers. Commonest non-neoplastic lesion was tuberculosis.  Malignancy was seen quite common in patients presented with lung masses in our institute.Conclusions: Lung tumours are quite common in patients presented with mass lesion. Similar to global trend, adenocarcinoma is the commonest histological type now and associated with change in incidence among women, in non-smokers, molecular alteration and prognosis which need further investigation. Immunohistochemistry is helpful in cases which are not accurately subtyped by histomorphology alone.

An unusual case of labial fusion in a post pubertal girl

Labial fusion is defined as either partial or complete adherence of the labia minora. It is also known as vulvar fusion, labial adhesion, labial agglutination or synechia of the vulva. This condition is common in pre-pubertal girls when estrogen levels are low and commonly resolves spontaneously post-puberty. This condition is usually asymptomatic and can be treated with topical application of estrogen or betamethasone cream or by manual or surgical separation of adhesions. We present a case of labial fusion in post pubertal girl which was managed surgically

Advancing the Productivity-Selectivity Trade-off of Temperature Swing Solvent Extraction Desalination with Intermediate-Step Release

Temperature swing solvent extraction (TSSE) offers a membrane-less and nonevaporative approach to hypersaline desalination, but performance of conventional TSSE operation is restricted by an inherent trade-off between water recovery yield and salt rejection. This study presents enhanced desalination capability of TSSE with a novel intermediate release step (TSSE-IR) over a conventional (c-TSSE) single-step operation. TSSE-IR demonstrated superior performance in the hypersaline desalination of 1.0 M NaCl brines for three amines with distinct water and salt partitioning behaviors: diisopropylamine, triethylamine, and tert-octylamine. The astute introduction of the intermediate temperature step in TSSE-IR dramatically improves salt rejection while minimizing the sacrifices in water recovery yields. We show that the intermediate step does not introduce additional solvent loss compared with c-TSSE operations with the same extraction temperature for any of the three solvents examined. TSSE-IR is demonstrated to advance the productivity-selectivity trade-off that constrains c-TSSE. Finally, Hunter–Nash analysis conducted on diisopropylamine–H2O–NaCl ternary diagrams exhibits good agreement with experimental TSSE-IR results, offering a reliable platform for modeling intermediate-step release performance and informing process design. This study establishes the potential of TSSE-IR to expand the spectrum of viable solvents for hypersaline desalination to include greener chemicals that exhibit high water recovery yields but low selectivities in c-TSSE

Zero Liquid Discharge of Ultrahigh-Salinity Brines with Temperature Swing Solvent Extraction

Zero liquid discharge (ZLD) of hypersaline brines is technically and energetically challenging. This study demonstrates ZLD of ultrahigh-salinity brines using temperature swing solvent extraction (TSSE), a membrane-less and nonevaporative desalination technology. TSSE utilizes a low-polarity solvent to extract water from brine and then releases the water as a product with the application of low-temperature heat. Complete extraction of water from a hypersaline feed, simulated by 5.0 M NaCl solution (≈292 g/L TDS), was achieved using diisopropylamine solvent. Practically all of the salt is precipitated as mineral solid waste and the product water contains <5% of NaCl relative to the hypersaline feed brine. Consistent ZLD performance of high salt removals and product water quality was maintained in three repeated semibatch TSSE cycles, highlighting recyclability of the solvent. The practical applicability of the technique for actual field samples was demonstrated by ZLD of an irrigation drainage water concentrate. This study establishes the potential of TSSE as a more sustainable alternative to current thermal evaporation methods for zero liquid discharge of ultrahigh-salinity brines

Phase equilibria insights into amine-water-NaCl interactions in liquid-liquid biphasic systems for temperature swing solvent extraction desalination

This study sheds light on the fundamental phenomena governing temperature swing solvent extraction (TSSE) desalination by investigating the influence of temperature on the equilibrium partitioning of water, salt, and solvent. The distribution of components across a range of temperatures and feed salinities typical to TSSE hypersaline desalination was examined for two amine solvents. A tradeoff between selectivity and productivity is established, providing a novel framework to assess TSSE performance. Salt was shown to be a key determinant in equilibrium partitioning by diminishing the ability of the solvent to extract water at lowered temperatures and salting-out amines from the aqueous phase. Na+ and Cl− ions consistently partition into the solvent phase in equimolar ratios. Analysis further reveals a linear correlation between the natural logarithms of salt activity coefficients and water contents of the organic phase. The two collaborating results suggest that water-ion interactions are more important than amine-ion interactions in the organic phase, resolving a critical gap in the understanding of salt transport. The findings of this study can provide important insights for the informed development of temperature swing solvent extraction for hypersaline desalination

Thermomorphic Hydrophilicity Base-Induced Precipitation for Effective Descaling of Hypersaline Brines

This study presents a novel technology, termed thermomorphic hydrophilicity base-induced precipitation (THBIP), for the effective removal of hardness ions from hypersaline brines with high-scaling propensity. THBIP utilizes thermoresponsive amine bases for the controlled precipitation of scaling constituents in alkaline conditions and subsequently uses low-temperature heat to trigger the phase separation of amine from aqueous solution, thus enabling reuse of the base. Three amines exhibiting distinct water solubility and basicity, specifically, diisopropylamine (DIPA), N-ethylcyclohexylamine (ECHA), and N,N-dimethylisopropylamine (DMIPA), were examined to identify the key parameters affecting THBIP performance. The amine bases were added to solutions containing hardness ions, Mg2+ or Ca2+, to induce the precipitation of hydroxide minerals (i.e., Mg(OH)2(s) and Ca(OH)2(s)). All three amines are effective in increasing solution pH, leading to high Mg2+ removals of over 90%. But because Ca(OH)2(s) is relatively more soluble, only DIPA, which is both highly miscible in water and also the strongest base, obtained significant removal of Ca2+ ions (>33%). The observed precipitation and hardness removal are quantitatively consistent with the principles of aqueous chemistry. Using a simulated hypersaline feedwater (240 g/L total dissolved solids) of high-scaling propensity, THBIP with DIPA achieved ∼80% hardness removal. Subsequent elevation of the temperature from 15 to 70 °C triggered demixing of the thermoresponsive base from the aqueous solution, to enable liquid–liquid separation for amine reuse. The study demonstrates the proof-of-concept of using thermomorphic hydrophilicity bases as an alternative strategy to effectively reduce the scaling potential of hypersaline brines

Stability Analysis of Filtered Two-Fluid Models for Gas-Particle Flows

Solution of two-fluid models for gas-particle flows in fluidized beds produces structures on the scale of a few particle diameters. Linear stability analysis of the homogeneously fluidized state indeed predicts this. These fine structures are too computationally expensive to resolve in simulations of large-scale fluidized beds. As such, researchers have developed filtered two-fluid models, which average over fine structures smaller than a given filter size. Developing constitutive relations appropriate for these filtered two-fluid models is a topic of active research. The constitutive relations are, in general, functions of the filter size. Conceptually, solution of properly formulated filtered two-fluid models and constitutive relations should not reveal fine structures smaller than the filter size. Systematic assessment as to whether the filtered models published in the literature satisfy this requirement has not been done before and is the principal goal of this thesis. Towards this end, linear stability analysis of homogeneously fluidized states, as predicted by the filtered two-fluid models augmented with filtered constitutive relations proposed by Igci et al. (2011) and Milioli et al. (2013), has been studied here. The analysis started with a hypothesis that the wavelength corresponding to marginal stability of homogeneously fluidized states should be comparable to the filter size in the constitutive models. It was found that this expectation was met for only a narrow range of particle volume fractions. Retaining the filtered constitutive models for drag and particle phase viscosity proposed by Igci et al. (2011), an alternate model for the filtered particle phase pressure that would satisfy the above-stated hypothesis was formulated, which was then used to simplify the expression for filtered particle phase viscosity. These refined models yield qualitatively reasonable results for all particle volume fractions considered when used in conjunction with the Igci et al. (2011) filtered drag coefficient model and for dilute and intermediate beds when used in conjunction with the Milioli et al. (2013) one