Room Temperature Research Articles

Comprehensive Review on Polymers Used in Insitu Gelling System

Abstract: In situ gelling formulations are drug delivery systems which typically exist in a liquid form at room temperature and change into gel state after application to the body in response to various stimuli such as changes in temperature, pH and ionic composition.[1] In situ gels have become one of the most prominent and accessible systems. These systems have several advantages like simple manufacturing, easy to use, improved adherence, and patient comfort by minimizing drug administration frequency by its unique characteristic features of sol to gel transition. In the 'sol-gel' method, the precursor goes through hydrolysis and polymerization or condensation to produce a colloidal suspension or solution. As they can administer in solution form, these in situ gelling systems undergo gelation at the achievement site. Some researchers recently developed in situ gelling systems of liposomes, microspheres, nanoemulsions, nanospheres, etc. This review mainly focused on the introduction, advantages, disadvantages, types of polymers, and suitable characteristics for preparing in situ gels.

Study on Sugarcane Bagasse Biochar in Concrete for Carbon Sequestration

Abstract: Embodied carbon from manufacturing of cement is increasing day by day as constructions are happening everywhere so the consumption of cement is increasing by default. In next decade there are much more constructions are going to takes place that will lead to Increase in GHG’s emissions from cement manufacturing. It is supposed to be a threat to climate . To reduce this increase in embodied carbon there is need to reduce cement consumption by partially replacing cement with other suitable options. biochar which is a by-product of pyrolysis of biomass and is effective in carbon sequestration activity and results in high water and carbon dioxide holding capacity. In this study Sugarcane bagasse biochar is used in concrete and mortar as partial replacement of cement for carbon sequestration. Strength characteristics of materials are supposed to be interlinked with pozzolanic activity hence pretreatment is done with 0.1 N HCl to enhance pozzolanic property activity of biochar. This pozzolanic activity is calculated by considering Ca(OH)2 fixation during the titration in chapelle test. From the study results its is observed that pretreatment with 0.1 N HCl at room temperature is sufficient to increase the pozzolanic activity of biochar also this Sugarcane bagasse biochar is observed to be sequestering carbon dioxide and it is increasing with increase in biochar. But compressive strength of concrete is decreasing with increase in sugarcane bagasse biochar. Hence it is not suitable to be used in construction work but can be used in plaster mortar where no much compressive strength is required . Sugarcane bagasse biochar can act as carbon sequestering media in concrete but it can’t be recommended in concrete or mortar for construction work.

Biochar Enriched Concrete for Carbon Sequestration

Abstract: In upcoming years , a lot of construction is going to happen leading to more cement consumption and more GHG’s emissions by default as an embodied carbon. Reduction of cement consumption is possible by partially repacing it with biochar which is a by-product of pyrolysis of biomass or adding it as an additive in cement mortar and concrete for carbon sequestration. Biochar is effective in carbon sequestration activity and results in high water and carbon dioxide holding capacity. Increase in biochar lead to increase in carbon sequestration . As pozzolanic activity lead to strength gaining characteristics and durability of concrete, this study focusses on investigating pozzolanic activity of biochar. Biomass considered in this study were walnut shells and pretreatment was done with 0.1 N HCl and and pozzolanic activity is checked by chapelle test by observing Ca(OH)2 fixation during the titration. It was observed that increase in temperature or Normality of HCl in pretreatment does not enhance pozzolanic activity of biochar . Hence pretreatment with 0.1 N HCl at room temperature for an hour is sufficient to enhance the pozzolanic activity of biochar with much high carbon dioxide sorption as compared to usual concrete without compromising with the strength of concrete. This study reclaims the potential use of biochar in concrete is reliable for carbon sequestration.

Development of Choco Dates Chocolates

Abstract: Layers of Rich Chocolate Contrasted with the Nutrient Rich Goodness of Dates Experience the unique blend of flavors as whole dates are delicately roasted, seeds removed with a small cut, and filled with luscious creamy rasmalai chocolate. Each piece is then generously coated in melted dark chocolate. Surprisingly, you only need 5 ingredients to craft these delectable treats, and they're not just delicious they're vegan and gluten free too. What sets these date chocolates apart is the protein-laden sweetness inherent in dates, enhancing the overall flavor profile. Elevate your taste experience with this health conscious and satisfying chocolate creation. A chocolate flavored with whole date was prepared by using white 32% and dark compound 20% and 45% of dates and 1.76 g of essence. The chocolates were prepared with natural dates sweetness. Both chocolates are melted (white compound at 42-45°C)and (dark compound at 50- 55°C) mixed with a essence for 2 min, and Cooling Down at room temperature for 2 min for settle down, then filling and cover the dates with fusion chocolates and Choco dates Chocolates is prepared.[Ahmed M. Hamad et al.,1987]

Influence of alkali treatment on thermal stability of polyester composites reinforced with Bambusa maculat fibers

The various species of bamboo plants cultivated in Indonesian people's plantations are apus bamboo (Gigantochloa apus) (GA), wulung bamboo (Gigantochloa atroviolacea) (GV), and tutul bamboo (Bambusa maculat) (BM). Apart from being used as a craft material and household utensils, bamboo can be made into natural fiber as a reinforcement for polyester composites. In this research, Bambusa maculat fiber was used. In this work, BM fibers were treated with Alkali with NaOH solutions with concentrations of 2, 5, and 8% by weight respectively at room temperature. The next procedure is that the BM fibers are used as composite reinforcing fibers, arranged unidirectional the polyester composites. The manufacturing technique is using hot pressing molding technique. The effect of alkali concentration on the thermal performance of polyester composites was examined using differential scanning calorimetry (DSC) and thermogravimetric (TG) analysis. As the result, the alkaline treatment of BM bamboo fiber with a NaOH concentration of 5%, causes the BM bamboo fiber as reinforcement and matrix to have a tight interface and strong interfacial bonding, allowing the composite to have the best thermal stability among other composites.

Effect Of Malted Ragi Powder On The Sensory Attributes of Carbonated RTS Functional Millet Based Whey Beverage

The present scenario focus interest in nutrition and health awareness, consumers are increasingly seeking high- quality functional products with acceptable sensory attributes. The primary objective of current research was to optimize the process for developing Carbonated Ready-to-serve (RTS) functional millet-based whey beverage malted ragi (5%,7%,9) on the sensory and physico-chemical aspects of Carbonated RTS functional millet-based whey beverage. Based on the analytical result, the functional beverage contained 5% Malted Finger Millet and was subjected for shelf-life tests. Sensory evaluation, as well as titratable acidity and pH analysis, was conducted for the samples stored at refrigeration temperature (7±1⁰C) and for those stored at room temperature (30±1⁰C) in glass bottle as the packaging material. The carbonated and non-carbonated RTS functional millet-based whey beverage and the control were found to be acceptable up to 2 days of storage at room temperature (30±1⁰C) and for 8 days stored at refrigeration temperature (7±1⁰C), respectively. The developed carbonated RTS functional millet based whey beverage is an innovative and nutritious product with enormous health benefits as it contains nutraceutical ingredient i.e. finger millet ( power house of nutrients). The developed functional millet based whey beverage can be given to all age groups and can be easily commercialized.

Unveiling the self-annealing phenomena and its effect on microstructure and texture evolution in the room temperature rolled Cu-0.13Sn-0.04Mg alloy

ABSTRACT In this study, we investigated the microstructural evolution of a Cu-0.13Sn-0.04Mg alloy that underwent heat treatment followed by room temperature rolling (RTR). Initially heat-treated specimens were rolled at room temperature (RT) with reduction ratios (RR) of 40% and 75% to perform microstructural and crystallographic textural analyses. Electron backscattered diffraction (EBSD) and transmission electron microscopy (TEM) were utilise to examine both initial and deformed microstructures. Both exhibited heterogeneous microstructural distributions. Shear bands (SBs) existed in the initial specimen and became main sites for the nucleation of new grains during heat treatment. A denser presence of SBs was noted in the RTR specimens. Remarkably, an unusual self-annealing phenomenon was observed in these specimens, culminating in the emergence of recrystallized grains at RT. A plethora of such grains was observed in the severely deformed specimens, with numerous nucleating grains appearing proximal to the SBs or deformed grain boundaries (GBs). Time dependent microstructure evolution was observed via ex-situ EBSD technique in the compressed specimens. Formation of new grains, increase in high angle grain boundaries (HAGBs), and dislocation annihilations were observed with the progress of time. The crystallographic texture evolution in the initial specimen was predominantly influenced by the S component. At lower strains, the fractions of Copper component increased, whereas at higher strains, a greater fraction of Brass and S components were induced. Following a 40% RR, a saturation in hardness value was observed, which could be potentially attributable to an accelerated rate of RT recrystallization in the case of 75% RR.

Compressible Hydrogels with Stabilized Chirality from Thermoresponsive Helical Dendronized Poly(phenylacetylene)s.

Fabrication of chiral hydrogels from thermoresponsive helical dendronized phenylacetylene copolymers (PPAs) carrying three-fold dendritic oligoethylene glycols (OEGs) is reported. Three different temperatures, i.e. below or above cloud point temperatures (Tcps) of the copolymers, and under freezing condition, were utilized, affording thermoresponsive hydrogels with different morphologies and mechanical properties. At room temperature, transparent hydrogels were obtained through crosslinking among different copolymer chains. Differently, opaque hydrogels with much improved mechanical properties were formed at elevated temperatures through crosslinking from the thermally dehydrated and collapsed copolymer aggregates, leading to heterogeneity for the hydrogels with highly porous morphology. While crosslinking at freezing temperature synergistically through ice templating, these amphiphilic dendronized copolymers formed hydrogels with highly porous lamellar structures, which exhibited remarkable compressible properties as human articular cartilage with excellent fatigue resistance. Amphiphilicity of the dendronized copolymers played a pivotal role in modulating the network formation during the gelation, as well as morphology and mechanical performance of the resulting hydrogels. Through crosslinking, these dendronized copolymers featured with typical dynamic helical conformations were transformed into hydrogels with unprecedently stabilized helicities due to the restrained chain mobilities in the three-dimensional networks.

On-demand catalysed n-doping of organic semiconductors.

A new approach to control the n-doping reaction of organic semiconductors is reported using surface-functionalized gold nanoparticles (f-AuNPs) with alkylthiols acting as the catalyst only upon mild thermal activation. To demonstrate the versatility of this methodology, the reaction of the n-type dopant precursor N-DMBI-H with several molecular and polymeric semiconductors at different temperatures with/without f-AuNPs, vis-à-vis the unfunctionalized catalyst AuNPs, was investigated by spectroscopic, morphological, charge transport, and kinetic measurements as well as, computationally, the thermodynamic of catalyst activation. The combined experimental and theoretical data demonstrate that f-AuNPs is inactive at room temperature both in solution and in the solid state, catalyst activation occurs rapidly at mild temperatures (~ 70 °C) and the doping reaction completes in few seconds affording large electrical conductivities (~ 10 - 140 S cm-1). The implementation of this methodology enables the use of semiconductor+dopant+catalyst solutions, will broaden the use of the corresponding n-doped films in opto-electronic devices such as thin-film transistors, electrochemical transistors, solar cells, and thermoelectrics well as guide the design of new catalysts.

Evaluation of Salivary Parameters and Oral Health Status in Periodontally Healthy Subjects and Chronic Periodontitis Subjects

Abstract Introduction: Periodontal disease is a chronic disease of the oral cavity that consists of a group of inflammatory disorders affecting the supporting structures of the dentition. Saliva can be used to predict the early onset of periodontitis. Several investigations have been carried out to evaluate the salivary chemical compounds that lead to the destruction and/or protection of periodontal tissues. The present study aimed to assess and compare salivary parameters and oral health status in periodontally healthy and chronic generalised periodontitis patients. Materials and Methods: This is an in vivo study designed to compare salivary parameters (albumin, urea, total proteins, amylase, glucose and pH) of unstimulated saliva and oral health status of periodontally healthy subjects (n = 65) and chronic generalised periodontitis subjects (n = 65). Human whole unstimulated saliva was collected by spitting method with the subject seated in an upright position after refraining from oral intake for 2 h before saliva collection. Approximately 5 mL of saliva was collected and stored in graduated saliva-collecting vials and refrigerated at 4°C for 1 h. The samples were centrifuged at 2800 rpm for 10 min, and the supernatant was separated from the substrate and stored at 20°C. Next, the sample was defrosted at room temperature and centrifuged at 3000 rpm. The supernatant was separated again to determine the concentrations of glucose, amylase, urea, total protein and albumin using the respective kits and analysed using an automated analyser. Salivary pH was estimated electrometrically with the help of a pH meter. Results: A significant association was found between salivary parameters (amylase and albumin total proteins) and clinical parameters (plaque index [PI], gingival index) [GI], probing depth and calculus index in generalised chronic periodontitis subjects when compared to periodontally healthy subjects. Conclusion: The increase in salivary parameters (amylase, total proteins and albumin) was statistically significant except for salivary glucose and urea (statistically non-significant) in generalised chronic periodontitis subjects compared to the healthy subjects. As the clinical parameters (probing depth, loss of attachment, PI, GI, calculus index and decay missing filled teeth) in periodontitis subjects increased, the salivary parameters also increased, suggesting a linear relationship between the generalised chronic periodontitis and salivary parameters (total proteins, albumin and amylase).

Effect of Europium and Gadolinium Alloying Elements on the Tribological Response of Low Hydrogen Content Amorphous Carbon.

Dopants and alloying elements are commonly introduced in amorphous carbon (a-C) materials to tailor their mechanical and tribological properties. While most published studies have focused on doping and alloying a-C coatings with metals or metalloids, doping a-C films with rare-earth elements has only recently been explored. Notably, our understanding of the shear-induced structural changes occurring in rare-earth-element-containing a-C films is still elusive, even in the absence of any liquid lubricants. Here, the friction response of Eu- and Gd-containing a-C films with low hydrogen content deposited by HiPIMS on silicon was evaluated in open air and at room temperature. The load-dependent friction measurements indicated that the introduction of Gd ((2.3 ± 0.1) at.%) and Eu ((2.4 ± 0.1) at.%) into the a-C matrix results in a significant reduction of the shear strength of the sliding interfaces ((41 ± 2) MPa for a-C, (16 ± 1) MPa for a-C:Gd2.3at.%, and (11 ± 2) MPa for a-C:Eu2.4at.%). NEXAFS spectromicroscopy experiments provided evidence that no stress-assisted sp3-to-sp2 rehybridization of carbon atoms was induced by the sliding process in the near-surface region of undoped a-C, while the amount of sp2-bonded carbon progressively increased in a-C:Gd2.3at.% and a-C:Eu2.4at.% upon increasing the applied normal load in tribological tests. The formation of an sp2-bonded carbon-rich surface layer in a-C:Gd2.3at.% and a-C:Eu2.4at.% films was not only proposed to be the origin for the reduced duration of the running-in period in tribological test, but was also postulated to induce shear localization within the sp2-carbon-rich layer and transfer film formation on the countersurface, thus decreasing the interfacial shear strength. These findings open the path for the use of Gd- and Eu-containing a-C even under critical conditions for nearly hydrogen-free a-C films (i.e., humid air).

New Lead-free Hybrid Layered Double Perovskite Halides: Synthesis, Structural Transition and Ultralow Thermal Conductivity.

We have synthesized three new hybrid layered double perovskites (HLDPs) with general formula (R'/R'')4/2M(III)M(I)Cl8; where R' = C3H7NH3 (i.e. 3N) and R'' = NH3C4H8NH3 (i.e. 4N4); M(III) = In3+ or Ru3+; M(I) = Cu+ by simple solution-based acid precipitation method. The structural analysis reveals that (4N4)2CuInCl8 and (4N4)2CuRuCl8 adopt the layered Dion Jacobson (DJ) structure, whereas (3N)4CuInCl8 exhibits layered Ruddlesden Popper (RP) structure.Three compounds show temperature-dependent structural phase transition where change in the staking of inorganic layer, extent of octahedral tilting and reorientation of organic spacers with temperature have noticed. We have achieved ultralow lattice thermal conductivity (kL) in the HLDPs in the 2 to 300 K range, originating from the distorted crystal structures and soft lattice. The RP-HLDP compound, (3N)4CuInCl8, demonstrates anisotropy in kL while measured parallel and perpendicular to layer stacking, showcasing ultralow kL of 0.15 Wm-1K-1 at room temperature, which is one of the lowest values obtained among Pb-free metal halide perovskite. The observed ultralow kL in three new HLDPs is attributed to significant lattice anharmonicity arising from the chemical bonding heterogeneity within the complex crystal structure, coupled with the presence of low-energy localized optical phonon modes that suppress heat-carrying acoustic phonons.

Temperature-dependent NIR-CPL spectra of chiral Yb(III) complexes.

Chiral, enantiopure Yb(III) complexes exhibit circularly polarized luminescence (CPL) in the near infrared (NIR) wavelength region. This CPL is quantified by the dissymmetry factor (glum). The excited state 2F5/2 consists of six mJ' states degenerated in three Stark levels, due to the crystal-field splitting (CFS), which are populated in accordance with the Boltzmann distribution. Consequently, room temperature CPL spectra are the sum of various - either positive or negative - contributions, that are practically impossible to quantify. To address this issue, an advanced setup enabling CPL measurements over a broad temperature range (300 to 4 K) has been developed. The interrelation of CFS, glum and temperature was explored using a pair of enantiopure Yb(III) complexes, highlighting the individual contribution of each crystal-field sublevel to the overall CPL spectrum, as anticipated by simulations performed in the framework of multireference wave-functions. Hence, the CPL spectra of chiral lanthanide complexes were found to be indeed strongly temperature-dependent, as is the glum dissymmetry factor, as a consequence of the variation in thermal sublevel population.

Preanalytical considerations for clinical assays of circulating human miRNA-451a, miRNA-423-5p and miRNA-199a-3p for diagnostic purposes.

Circulating miRNA has recently emerged as important biomolecules with potential clinical values as diagnostic markers for several diseases. However, to be used as such, it is critical to accurately quantify miRNAs in the clinic. Yet, preanalytical factors that can affect an error-free quantification of these miRNAs have not been explored. This study aimed at investigating several of these preanalytical factors that may affect the accurate quantification of miRNA-451a, miRNA-423-5p and miRNA-199a-3p in human blood samples. We initially evaluated levels of these three miRNAs in red blood cells (RBCs), white blood cells (WBCs), platelets, and plasma by droplet digital PCR (ddPCR). Next, we monitored miRNA levels in whole blood or platelet rich plasma (PRP) stored at different temperatures for different time periods by ddPCR. We also investigated the effects of hemolysis on miRNA concentrations in platelet-free plasma (PFP). Our results demonstrate that more than 97% of miRNA-451a and miRNA-423-5p in the blood are localized in RBCs, with only trace amounts present in WBCs, platelets, and plasma. Highest amount of the miRNA-199a-3p is present in platelets. Hemolysis had a significant impact on both miRNA-451a and miRNA-423-5p concentrations in plasma, however miRNA-199a levels remain unaffected. Importantly, PRP stored at room temperature (RT) or 4°C showed a statistically significant decrease in miRNA-451a levels, while the other two miRNAs were increased, at days 1, 2, 3 and 7. PFP at RT caused statistically significant steady decline in miRNA-451a and miRNA-423-5p, observed at 12, 24, 36, 48 and 72 hours. Levels of the miRNA-199a-3p in PFP was stable during first 72 hours at RT. PFP stored at -20°C for 7 days showed declining stability of miRNA-451a over time. However, at -80°C miRNA-451a levels were stable up to 7 days. Together, our data indicate that hemolysis and blood storage at RT, 4°C and -20°C may have significant negative effects on the accuracy of circulating miRNA-451a and miRNA-423-5p quantification.

Self‐Extinguishing and Low‐Cost Quasi‐Solid Polymer Electrolyte for Room Temperature Lithium Metal Batteries

Most modification strategies of polyethylene oxide (PEO)‐based solid polymer electrolyte focus on improving the room temperature ionic conductivity, while disregarding its inherent flammability that poses substantial safety hazard. Herein, a self‐extinguishing quasi‐solid‐state polymer electrolyte (PTTF‐SPE), which combines excellent room temperature electrochemical properties and high safety, has been developed by introducing triethyl phosphate (TEP) as a low‐cost and highly effective flame retardant. The cross‐linking structure derived from ‐CH2‐CH2‐O‐ segments of tetramethylene glycol dimethyl ether (TEGDME) and PEO makes a contribution to a high amorphous state of polymer. A robust solid electrolyte interphase (SEI) formed by preferential decomposition of fluoroethylene carbonate (FEC) that acts as a film‐forming additive, which can prevent TEP from degradation at lithium metal anode. The optimized PTTF‐SPE exhibits high ionic conductivity (0.54×10‐3 S/cm) and lithium transference number (0.71) at room temperature. The LiFePO4||Li battery demonstrates excellent cycle life over 500 cycles at 0.5 C with a high average discharge capacity of 131 mAh/g. A symmetric Li||Li battery that operating for 850 hours indicates a good compatibility of PTTF‐SPE towards lithium metal. This work provides a new idea for developing high‐energy‐density and high‐safety lithium‐metal batteries (LMBs) for room temperature.

Highly Sensitive Diethylamine Detection at Room Temperature Using g-C3N4 Nanosheets Decorated with CuO Hollow Polyhedral Structures.

Chemiresistive-based metal oxide semiconductor (MOS) gas sensors are widely used in gas sensing due to their advantageous properties. Graphitic carbon nitride (g-C3N4) and metal oxide heterostructure materials can improve charge transport properties, selectivity, and sensitivity in MOS gas sensor materials. Herein, for the first time, CuO hollow polyhedral structures (HPSs) were synthesized via a hydrothermal technique and annealed at different temperatures, with the 400 °C annealed (CuO-400 HPSs) demonstrating remarkable sensing capabilities for diethylamine (DEA) gas at room temperature (RT). The x-g-C3N4 nanosheets were decorated with CuO HPSs in varying amounts (x = 0.8, 1.8, 2.1, and 3.1 wt %) and then annealed at 400 °C for x-g-C3N4-CuO-400 hollow polyhedral heterostructures (HPHSs). Indeed, among the synthesized samples, the 1.8%-g-C3N4-CuO-400 HPHSs have a higher sensitivity to DEA (resistance change in gas (Rg) and air (Ra); Rg/Ra= 65 @ 20 ppm), a low detection limit (Rg/Ra= 6 @ 500 ppb), wide dynamic response (Rg/Ra= 190 @ 80 ppm), strong stability (30 days), and 21.6 times higher sensitivity than pure CuO at RT toward 20 ppm of DEA. The exceptional gas-sensing behavior can be attributed to various factors, including controlled annealing conditions that result in the formation of well-defined structures and greater porosity, efficient charge transfer properties resulting from an optimized ratio of g-C3N4 to CuO in HPHSs, an abundance of defects, unsaturated Cu sites, and synergistic effects. The study presents a universal strategy for generating sensitive and selective g-C3N4-based composite materials for low-temperature gas sensors.

Embedding Te4+ into Sn4+-Based Metal Halide To Passivate Structure Defects for High-Performance Light-Emitting Application.

Low-dimensional lead-halide hybrids are an emerging class of optical functional material but suffer the problems of toxicity and poor air stability. Among lead-free metal halides, tin(IV)-based metal halides are promising optoelectronic materials due to their robust structure and environmental friendliness. However, their photoluminescence (PL) properties are poor, and the underlying mechanisms are still elusive. Herein, a stable Sn4+-based halide hybrid, (C4H7N2)2SnCl6, was developed, which however exhibits poor PL properties at room temperature (RT) due to the lattice defects and the robust crystal structure. To enhance its PL efficiency, the Te4+ ion with a stereoactive 5s2 lone pair has been introduced into the lattice. As a result, Te4+-doped (C4H7N2)2SnCl6 displays broadband orange emission (∼640 nm) with a PL efficiency of ∼46% at RT. Interestingly, Te4+-doped (C4H7N2)2SnCl6 shows triple emission bands at 80 K, which could be due to the synergistic effect of the organic cations and the self-trapped state induced by Te4+. Additionally, high-performance white light-emitting diodes were prepared using Te4+-doped (C4H7N2)2SnCl6, revealing the potential of this material for lighting applications. This study provides new insight into the PL mechanism of Sn4+-based metal-halide hybrids and thus facilitates the design and development of eco-friendly light-emitting metal halides.

Synthesis and Properties of the Ba2PrWO6 Double Perovskite.

We report details on the synthesis and properties of barium praseodymium tungstate, Ba2PrWO6, a double perovskite that has not been synthesized before. Room-temperature (RT) powder X-ray diffraction identified the most probable space group (SG) as monoclinic I2/m, but it was only slightly distorted from the cubic structure. X-ray photoelectron spectroscopy confirmed that the initial (postsynthesis) material contained praseodymium in both 3+ and 4+ charge states. The former (Pr3+) disappeared after exposure to UV light at RT. Photoluminescence studies of Pr3+ revealed that Ba2PrWO6 is an insulator with a band gap exceeding 4.93 eV. Pressure-dependent Raman spectroscopy excluded the possibility of a phase transition up to 20 GPa; however, measurements between 8 and 873 K signified that there might be a change toward the lower symmetry SG below 200 K. Electron paramagnetic resonance spectra revealed the presence of interstitial oxygen which acts as a deep electron trap.

Preparation and performance evaluation of intelligent plugging agent for thermo‐sensitive water‐based drilling fluid

AbstractIn the process of unconventional oil and gas exploitation, the invasion of a large amount of drilling fluid into the formation is one of the most critical reasons leading to wellbore instability. A temperature‐sensitive polymer (AOS) was synthesized from acrylamide, oligo (ethylene glycol) methyl ether methacrylate (OEGMA), and sodium p‐styrene sulfonate by emulsion polymerization. The material is a solid‐free fluid with good fluidity at room temperature, after injection into the formation, the fluid is gradually transformed into hard gel above the lower critical solution temperature (LCST) (90°C), thus blocking micro‐fractures and improving wellbore stability. Infrared and NMR characterization confirmed the successful preparation of the target product. The transmittance of AOS with ambient temperature was measured by UV–vis spectrophotometer, and the LCST behavior of AOS was verified by rheological and viscoelastic measurements. The interaction mechanism between AOS and sodium bentonite was evaluated according to the American Petroleum Institute standard. The results show that after aging at 180°C, the filtration loss is reduced by 93%, and the medium permeability (100, 200 mD) formation is effectively plugged, with a plugging efficiency is as high as 74.7%.

Enhanced energy storage performance, breakdown strength, and thermal stability in compositionally designed relaxor Eu3+ substituted Na0.2K0.3Bi0.5TiO3

Lead-free Eu3+ substituted NKBT ceramics (Na0.2K0.3Bi0.5-xEuxTiO3, x = 0 (Eu 0),0.02(Eu 2),0.04(Eu 4), and 0.06(Eu 6)) were strategically designed via a local random field approach. The structural evolution had been confirmed through X-ray diffraction analysis. The observation of a broad dielectric curve supported the enhanced relaxor nature and the phenomena reflected in the P-E and S-E loops. The diffuse phase transition transforms to the plateau-type feature with excellent thermal stability with ±20 % and ± 40 % variation in dielectric constant over the temperature range of 120 to 500 °C and 90 to 500 °C, respectively in Eu 4. A large recoverable energy density of 1.7 J/cm3 with a high breakdown strength of 188 kV/cm was achieved in the Eu 2 sample at room temperature, making it a potential candidate for energy storage application. Moreover, the frequency stability (0.1 to 500 Hz range), thermal stability (45 °C to 85 °C), and fatigue measurement (10−1 to 106 cycles) were performed from the application point of view. The highest efficiency (82 %) was also achieved in the Eu 6. The negligible Sneg of Eu-rich compositions proves the existence of a relaxor state when the field is removed, and it transforms into the ergodic relaxor state. Furthermore, the SRBRF model is exploited to understand and correlate the transformation from normal to relaxor ferroelectrics with their properties. The current study provides a novel idea for compositional design for energy density, efficiency, and thermal stability ceramics by modifying and creating weakly coupled polar phases with rare earth substitution.