Colloidal Solution Research Articles

Encapsulation of Essential Oils Using Complex Coacervation: A Study on Microcapsule Formation and Efficiency

Encapsulation by Coacervation is a process used to create microcapsules. Coacervation is a process that has been used in the food and pharmaceutical industry to produce microspheres with an active ingredient, such as drugs, flavors or fragrances encapsulated by them. It is common in pharmacies, food preparation, cosmetics, and agriculture. This phase separation process is called Coacervation, where a colloidal (in this case polymer) solution will separate into two distinct liquid phases: a Polymer-rich phase, which we refer to as the coacervate, and the other is known as Polymer-poor or solvent-based. This can be accomplished by varying the temperature or pH of a non-solvent being introduced. In this study, essential oils of lemon and eucalyptus were encapsulated by the complex coacervation process using gum Arabic, gelatin, and chitosan as wall materials. Glutaraldehyde was used as a cross-linking agent in the methodology. FT-IR and GC characterized the essential oils used. The microcapsules were analyzed using a digital microscope, scanning electron microscopy (SEM), and thermogravimetric analysis. Conclusively, microcapsules were formed in spherical form. Encapsulation efficiencies were obtained between 75-78%. In conclusion, microencapsulated essential oils offer a technology that makes essential oils more effective, long-lasting, and customized. These advantages reveal their widespread impact, offering various uses for a variety of industries and applications.

Comparison of pulse pressure and stroke volume variations measured by three monitors in high-risk surgical patients

IntroductionDynamic indices of fluid responsiveness (FR) such as pulse pressure variation (PPV) and stroke volume variation (SVV) differ among hemodynamic monitors, which use proprietary algorithms, and vary even over a short period of time. We aimed to compare the baseline values, fluctuation and predictive value for FR of PPV and SVV measured by three minimally invasive monitors. Patients and methodsTwenty patients undergoing high-risk abdominal surgery were included and 45 fluid challenges were analysed. The patients were simultaneously monitored using Carescape B650, LiDCO Rapid and FloTrac/Vigileo system. Cardiac output (CO), PPV and SVV were recorded before and after the fluid challenge of 500ml of balanced crystalloid solution. An increase in CO ≥ 15 % defined fluid responders. Concurrently recorded arterial waveform was used for offline calculation of PPV. ResultsMean baseline values of the indices ranged between 8.6% and 13.4%. LiDCO showed higher fluctuation of indices compared to the other monitors. Area under the receiver operating characteristic curve (AUROC) ranged from 0.71 to 0.76 with optimal cut-off value between 7.5% and 13.9%. AUROC increased for all indices when FR was defined as an increase in stroke volume. Furthermore, a decrease in PPV or SVV after fluid challenge (ΔPPV, ΔSVV) proved a better marker of FR (AUROC 0.82 – 0.93) than baseline values with a uniform threshold of approximately -3%. ConclusionsAlthough a significant range of baselines variations and optimal cut-off values was observed, the predictive value of PPV and SVV from all the monitors was only moderate and comparable. Nevertheless, ΔPPV and ΔSVV appear to be a reliable and device-independent markers of FR.

Renewable Resources as Promising Materials for Obtaining Graphene Oxide-like Structures.

Currently, one of the topical directions in the field of production and application of graphene-like nanostructures is the use of renewable natural raw materials, which have unlimited resources for an economically efficient large-scale yield of a product with environmental safety. In this regard, we present the production of graphene oxide (GO) from a renewable natural raw material of plant biomass, birch activated carbon (BAC), and a comparison of the obtained physicochemical, mechanical, and electrical properties of birch activated carbon-graphene oxide (BAC-GO) and graphite-graphene oxide (G-GO) synthesized from the initial materials, BAC and graphite (G). Results obtained from this study confirm the successful oxidation of BAC, which correlates well with the physical-chemical dates of the G-GO and BAC-GO samples. Change in data after the oxidation of graphite and BAC was facilitated by the structure of the starting materials and, presumably, the location and content of functional oxygen-containing groups in the G-GO and BAC-GO chains. Based on the results, the application of a cost-effective, eco-friendly colloidal solution of nanodispersed BAC-GO from a plant biomass-based high-quality resource for producing large-scale nanostructured graphene is validated which has potential applicability in nanoelectronics, medicine, and other fields.

Liquid-phase shear exfoliation of graphite and its application as corrosion protection coating on aluminum substrate

Although aluminum (Al) or its alloys are moderately protected by a native oxide layer, the presence of chloride ions in aqueous media in direct contact causes pitting attacks and accelerates corrosion. Using graphene as a coating protector can obstruct corrosion due to its numerous chemical and physical properties. This study investigates corrosion protection of Al using graphene nanosheets (GNSs) produced by liquid phase shear exfoliation method (LPE). To do so, few layer-thick graphene nanosheet colloidal solutions were produced by a scalable eco-friendlier lower cost approach. The GNSs were thoroughly characterized using complementary characterization techniques to determine its quality. Spectroscopic and microscopic analyses indicate the synthesis of few-layers graphene (≤ 5 layers) with a high quality. Once approved, the colloidal solution of GNSs was spread over Al substrate by spray coating method, widely used in industrial manufacturing. Raman and near infrared spectroscopies, X-ray diffraction, microscopy techniques including scanning electron, transmission electron and atomic force microscopies were used to investigate morphological and structural behavior of coated GNSs films either on glass or Al substrates. Density functional theory (DFT) calculations revealed the interaction between the two materials is of the physisorption type, with almost no charge transfer and almost no effect of the number of graphene layers. Electrochemical measurements enabled to investigate the corrosion resistance of GNSs films and its stability over time in a 0.5 M sodium chloride (NaCl) solution, similar to marine surroundings. It was found that introducing a GNSs film can indeed reduce the corrosion rate and preserve Al substrate for an extended period.

Site-selective laser spectroscopy of mixed fluoride La1−x−yYxNdyF3 crystalline nanopowders

When replacing lanthanum with yttrium, mixed fluoride crystalline La1−x−yYxNdyF3 colloidal solutions and nanopowders (x = 0.1–0.3; y = 0.001, 0.01) demonstrate significant heterogeneity of the crystal structure. Therefore, the luminescence excitation and emission spectra of the Nd3+ ion are significantly inhomogeneously broadened. The spectral broadening increases with increasing yttrium concentration from 10 to 30 at.%. The measured luminescence band of Nd3+ ion with a maximum of approximately 862.5 nm includes the luminescence of three groups of optical centers OC1 − OC3. The luminescence of these OCs is quenched by OH− acceptors, which were embedded into the volume of nanoparticles (NPs) during the hydrothermal synthesis. Density functional calculations revealed three possible local positions of molecular OH− groups replacing fluorine ions. The observed difference in the luminescence quenching kinetics of the OC1 − OC3 centers is due to the different coordination of the local OH− groups around the Nd3+ ions.

Impact of tip curvature and edge rounding on the plasmonic properties of gold nanorods and their silver-coated counterparts.

Colloidal solutions of gold nanorods and silver-coated gold nanorods were prepared. The seeded growth synthesis protocols were improved by adding a flocculation purification step. The resulting populations of pure gold nanorods and Au@Ag core-shell cuboids were characterized by very low dispersion in size and shape. UV-vis-near-infrared absorption measurements were performed on several batches of well-calibrated nano-objects, supported by calculations based on the discrete dipole approximation, allowed to highlight the impact of various morphological features on the optical response. In addition to the well-known effect of the nanorod aspect ratio on the shift of the longitudinal surface plasmon resonance mode, special attention was paid to changing either the rounding of the nanorod end-caps or that of the edges of the coating silver shell. Nanorods and cuboids were modeled as superellipsoids. This approach enabled us to model precisely their complex shapes using just a few simple parameters and analyze the evolution of their extinction spectra as a function of the rounding of their tips and edges. Such nano-objects are widely used for various applications in fields such as biomedical, biosensing, or surface-enhanced Raman spectroscopy, thus making it crucial to precisely assess the impact of each morphological feature for optimizing their performance.

Intraoperative hypotension in children-Measurement and treatment

Intraoperative hypotension is acommon perioperative complication in pediatric anesthesia. Oscillometric blood pressure measurement is therefore an essential part of standard perioperative monitoring in pediatric anesthesia. The optimum measurement site is the upper arm. Attention must be paid to the correct cuff size. Blood pressure should be measured before induction. In children undergoing major surgery or in critically ill children, invasive blood pressure measurement is still the gold standard. Continuous noninvasive measurement methods could be an alternative in the future.Threshold values to define hypotension remain unknown, even in awake children. There are also little data on hypotension thresholds in the perioperative setting. The most reliable measurement parameter for estimating hypotension is the mean arterial pressure. The threshold values for intraoperative hypotension are 40 mm Hg in newborns, 45 mm Hg in infants, 50 mm Hg in young children and 65 mm Hg in adolescents. Treatment should be initiated at adeviation of 10% and intensified at adeviation of 20%.Bolus administration of isotonic balanced crystalloid solutions, vasopressors and/or catecholamines are used as treatment options. Consistent and rapid intervention in the event of hypotension appears to be crucial. So far there is no evidence as to whether this leads to an improvement in outcome parameters.

Intraoperative factors associated with unplanned return to the operating room after emergent hemorrhage control surgery.

Unplanned return to the operating room (uROR) is associated with worse outcomes and increased mortality. Little is known regarding intraoperative factors associated with uROR after emergent surgery in trauma patients. The objective of this study was to identify intraoperative factors associated with uROR after emergent hemorrhage control procedures in bleeding trauma patients. We used anesthetic record of intraoperative management to perform a retrospective study (2017-2022) of bleeding trauma patients who were taken for an emergent hemorrhage control operation. A total of 225 patients met the inclusion criteria, 46 (20%) had uROR, and 181 (80%) did not. While there was no difference in demographics, mechanism, admission physiology, or time from emergency department to operating room, the uROR patients had a higher Injury Severity Score (30 vs. 25, p = 0.007). While there was no difference in volume of crystalloid infused (3,552 ± 2,279 mL vs. 2,977 ± 2,817 mL, p = 0.20), whole blood (2.2 ± 0.9 vs. 2.0 ± 0.5, p = 0.20), or platelets (11.6 ± 8.6 vs. 9.2 ± 9.0, p = 0.14), the uROR group received more packed red blood cells (11.5 ± 10.6 vs. 7.8 ± 7.5, p = 0.006) and plasma (9.6 ± 8.3 vs. 6.5 ± 6.6, p = 0.01), and more uROR patients received ≥10 U of packed red blood cells (48% vs. 27%, p = 0.006). Damage-control surgery (DCS) was more common in uROR patients (78% vs. 45%, p < 0.0001). After logistic regression, ≥10 U of packed cells in the operating room (4.3 [1.5-12.8], p = 0.009), crystalloid (1.0 [1.0-1.001], p = 0.009), International Normalized Ratio (INR) (7.6 [1.3-45.7], p = 0.03), and DCS (5.7 [1.7-19.1], p = 0.005) were independently associated with uROR. Massive transfusion, crystalloid resuscitation, persistent coagulopathy, and DCS are the most significant risk factors for uROR. During hemorrhage control surgery in bleeding trauma patients who receive ≥10 U of blood, providers must maintain a keen focus on minimizing crystalloid and ongoing balanced resuscitation, particularly during damage-control procedures. Retrospective/Descriptive; Level IV.

Novel theoretical studies based on CIELab and deconvolution methods to characterize AuNPs aggregation processes

The study of the interaction of spherical gold nanoparticles when they undergo aggregation phenomena due to the presence of a ligand in solution is presented, based on both colorimetric parameters (using CIELab space) and traditional deconvolution analysis. The feasibility of using CIELab space for this purpose can be an important method to simplify the required instrumentation (colorimeter versus UV spectrophotometer) as well as being less time consuming compared with the traditional computational analysis. For these reasons, in this work we present the first experimental approach of the proposed methodology for its application in this field of research. The synthetized AuNPs employed in this work have been previously characterized by means of the maxima of their LSPR bands, zeta potential and electron microscopy images. The aggregation of spherical AuNPs (with a diameter of 12 nm) by an inert electrolyte (NaCl) is investigated in a first step with successfully results, allowing to obtain the characteristic CIELab parameters (a*, b* and L*). At a later stage, the color changes induced in the optical properties of the solution due to the interaction of AuNPs (with increasing diameters of 12, 25 and 33 nm) with an amino acid such as lysine at neutral pH, have been also described using the CIELab spatial framework. The obtained a*, b* and L* parameters of the CIELab space allow to characterize satisfactorily the color change from red to blue which describes the aggregation phenomena, relying on deconvolution analysis of the LSPR bands. The results obtained support the validity of the CIELab space as a valid tool for the investigation of the aggregation process of colloidal solutions. It will allow simplifying the whole process using simpler and cheaper instrumentation as well as a decrease in the required analysis time.

Synthesis of Silver Nanoparticles and Silver-Gold Binary System by Galvanic Replacement in an Ultrasonic Field

The conditions for the synthesis of colloidal solutions of silver nanoparticles by galvanic replacement in an ultrasonic field and the AgAuNP binary system by galvanic replacement have been studied. It has been shown that colloidal solutions of stabilized nanoparticles with absorption maxima at 410 nm (AgNPs) and 540...560 nm (AgAuNPs) are formed in solutions of sodium polyacrylate and metal precursors of AgNO3 and H[AuCl4]. The synthesized AgAuNPs are spherical in shape and their size does not exceed 20 nm.

Prepared copper oxide nanoparticle colloidal solution by different laser ablation energy in liquid for enhanced organic dye degradation efficiency

Prepared copper oxide nanoparticle colloidal solution by different laser ablation energy in liquid for enhanced organic dye degradation efficiency

The process of evaporation of a colloidal solution of stabilized Boron nitride nanoparticles

Purpose. Characterization of the chemical structure of boron nitride nanoparticles by IR spectroscopy during the evaporation of their colloidal system and their sizes by small-angle X-ray scattering.Methods. The solvent evaporation process from the colloidal system was studied using a Nicolet iS 50 FT-IR spectrometer in the mid-IR range (400 – 4000 cm-1), with an attenuated total reflectance accessory with a diamond crystal (incident angle of 45°) and a liquid cell (200 μL). The sizes of the colloidal particles were determined using an smallangle X-ray scattering diffractometer in linear collimation mode (resolution 0.03 nm-1, copper anode X-ray tube 2.2 kW, λ = 0.154 nm, exposure time 30 s).Results. The IR spectrum of boron nitride nanoparticles powder was measured, containing lines characteristic of cubic (952 cm-1) ) – c-BN and hexagonal crystalline phases (758, 1301, and 1372 cm-1) – h-BN. The average size of boron nitride nanoparticles in the colloidal system, according to small-angle X-ray scattering data, was 46 and 84 nm. The size of stearic acid, which acts as a stabilizing shell, was 0.8, 1.3, and 2.5 nm. Analysis of the IR spectra showed complete evaporation of the solvents (hexane and chloroform) from a drop of colloidal solution 1.2 mm thick within 30 minutes.Conclusion. In this work, the average sizes of boron nitride nanoparticles stabilized with stearic acid in a colloidal system were determined and the process of its evaporation was studied.

A Comparative Study of Infusion of Ephedrine and Phenylephrine on Hemodynamic Stability After Spinal Anesthesia in Elderly Patients Undergoing Lower Limb Orthopedic Surgeries.

Background Hypotension during spinal anesthesia occurs due to sympathetic nervous system blockade, resulting in decreased systemic vascular resistance and reduced cardiac output. Due to reduced sympathetic tone, peripheral arterial vasodilatation and blood pooling in lower limbs due to venodilatation occur, reducing preload to the heart and stroke volume. The elderly patients have reduced cardiovascular compensatory mechanisms, increasing the frequency and severity of hypotension due to sympathetic blockade after spinal anesthesia significantly. Vasopressors correct hypotension during the intraoperative period to maintain organ perfusion. Fluids can be administered, and if given excessively, can cause fluid overload and urinary retention. This study aimed to compare the effectiveness of vasopressors, phenylephrine, and ephedrine in maintaining hemodynamic stability intraoperatively through prophylactic infusion after spinal anesthesia in elderly patients for lower limb orthopedic surgeries. Methodology A total of 174 elderly patients aged 60 years and above with American Society of Anesthesiologists (ASA) Classification I and II, undergoing lower limb orthopedic surgeries, enrolled in a randomized comparative study, were allocated into three groups: Group P (phenylephrine, n=58) received 250 mcg phenylephrine in 30 ml normal saline using infusion syringe pump, Group E (ephedrine, n=58) received 30 mg ephedrine in 30 ml normal saline using infusion syringe pump, and Group C (control group, n=58) received mephentermine I/V (6 mg bolus) when the fall in blood pressure was below 30% of baseline without any placebo infusion. Hemodynamic parameters (systolic and diastolic blood pressure, mean arterial pressure (MAP), heart rate) at 15, 10, and 5-minute intervals before spinal anesthesia, and at 3, 6, 9, 12, 15, 20, 25, and 30-minute intervals after spinal anesthesia. The need for rescue doses to treat hypotension after spinal anesthesia was recorded. Result At all time intervals following spinal anesthesia, Group E reported heart rate and systolic blood pressure better than Groups P and C, significantly. At 3, 6, 9, 12, 15, and 25-minute intervals following spinal anesthesia, the diastolic blood pressure in Group E was enhanced significantlythan Groups P and C. The MAP in Group E was substantially higher than in other groups at 3, 6, 15, and 20-minute intervals following spinal anesthesia, which was statistically significant. Compared to Groups P and C, Group E required lesser rescue doses to treat intraoperative fall in hypotension 30% below baseline and lesser events of bradycardia. Conclusion Following spinal anesthesia, the preload to the heart is to be maintained with intravenous (crystalloid or colloidal) solutions to maintain cardiac output adequately. Intraoperative use of phenylephrine and ephedrine as a low-dose prophylactic infusion can be used, as it increases both systemic vascular resistance and preload without cardiac stimulation along with intravenous solutions to maintain hemodynamic parameters such as systolic and diastolic blood pressure, MAP, heart rate effectively but preferably ephedrine in elderly patients.

MODIFICATION OF GLASS IONOMER FILLING MATERIAL BY METAL NANOPARTICLES AND THEIR COMPOUNDS: EFFECT ON ANTI-MICROBIAL ACTIVITY

Background: Glass ionomer filling materials are widely used in stomatology, but do not have an antimicrobial effect that effectively prevents the development of secondary and recurrent dental caries. Researchers are attempting to modify these materials by introducing various biologically active additives into them. The aim of the study was to evaluate the antimicrobial properties of a dental ionomer filling material modified withadditives based on high–energy nanoparticles of silver, copper, titanium and their compounds. Material and methods: Colloidal aqueous and alcoholic solutions of metals and their oxides with stabilizers were obtained by the electroerosion method. Citric acid, cetylpyridinium chloride and Trilon B were used as stabilizers. The zeta potential and the distribution of particles of the dispersed phase in solutions were measured. Samples of dental glass ionomer cement "Cemion-Aqua" were impregnated with colloidal solutions of nanoparticles. The microbiological activity of glass ionomer fillings samples in relation to plaque was determined by disc diffusion and suspension methods. Results: The results showed that modification of glass ionomer cement samples with silver hydrosols in citric acid solutions with concentrations of 0.04% and 0.0025% increases the zone of radial lysis of microbial plaque colonies around the cement samples by 1.5 and 2.5 times compared with the control. By the suspension method, it was determined that silver hydrosols in a solution of citric acid and without it reduce the formation of colonies of microorganisms to several units up to 72 hours of exposure compared with the control. And copper hydrosols in solutions of cetylpyridinium chloride prevent an increase in the number of colonies of microorganisms after 24 hours of exposure compared with the control. Silver hydrosol in a solution of citric acid with a concentration of 0.0025% and silver alcohol sol reduce the number of colonies of microorganisms to several units after 3 hours of exposure.

Investigation of the regulatory mechanism of monolayer colloidal crystals prepared by gas-liquid-solid three-phase interfacial self-assembly method

In recent years, the gas-liquid interface self-assembly method has emerged as a recognized and efficient technique for preparing two-dimensional monolayer colloidal crystals. However, challenges such as limited preparation area, dependence on complex equipment, and high costs persist in the conventional preparation process. This paper proposes a straightforward, rapid, and cost-effective method to implement a gas-liquid-solid three-phase interfacial self-assembly strategy. This approach enhances the gas-liquid interfacial self-assembly method, allowing for the preparation of large-area, high-quality single-layer colloidal crystals (>10 cm2) without using any surfactant. The gas-liquid-solid three-phase interfacial self-assembly process was analyzed in detail, and it was found that the main factors affecting the quality of the monolayer colloidal crystals were the volume ratio of PS colloidal solution to ethanol and the self-assembly temperature. It was shown that the optimal self-assembly conditions were achieved after dispersion by ultrasonic dispersion in a water bath at 32 °C–30 °C at a volume ratio of 1:2.5 of PS colloidal solution to ethanol. In addition, particles of various sizes can be prepared by this method to produce tightly arranged monolayer films that can be transferred to a variety of different substrates with great versatility. The demonstrated efficiency of this self-assembly method underscores its significant potential for application in large-scale manufacturing and practical industrialization.

TBI related death has become the new epidemic in polytrauma: a 10-year prospective cohort analysis in severely injured patients.

Advances in trauma care have attributed to a decrease in mortality and change in cause of death. Consequently, exsanguination and traumatic brain injury (TBI) have become the most common causes of death. Exsanguination decreased by early hemorrhage control strategies, whereas TBI has become a global health problem. The aim of this study was to investigate trends in injury severity,physiology, treatment and mortality in the last decade. In 2014, a prospective cohort study was started including consecutive severely injured trauma patients > 15years admitted to a Level-1 Trauma Center ICU. Demographics,physiology,resuscitation, and outcome parameters were prospectively collected. Five hundred and seventy-eight severely injured patients with predominantly blunt injuries (94%) were included. Seventy-two percent were male with a median age of 46 (28-61) years, and ISS of 29 (22-38). Overall mortality rate was 18% (106/578) with TBI (66%, 70/106) being the largest cause of death. Less than 1% (5/578) died of exsanguination. Trend analysis of the 10-year period revealed similar mortality rates despite an ISS increase in the last 2years. No significant differences in demographics,and physiology in ED were noted. Resuscitation strategy changed to less crystalloids and more FFP. Risk factors for mortality were age,brain injury severity,base deficit,hypoxia,and crystalloid resuscitation. TBI was the single largest cause of death in severely injured patients in the last decade. With an aging population TBI will increase and become the next epidemic in trauma. Future research should focus on brain injury prevention and decreasing the inflammatory response in brain tissue causing secondary damage, as was previously done in other parts of the body.

Agglomeration of carbonaceous particles in a pendant water slurry droplet

Liquid spraying is used in a number of engineering applications, such as spray cooling, drying, granulation, etc., which mostly deal with colloidal solutions or slurries. Depending on the application, solid particle agglomeration can be considered a positive or negative phenomenon. Therefore, to make engineering processes reliable and stable, it is necessary take account of secondary processes affecting the size distribution of the material involved. The agglomeration of solid particles in a pendant droplet was studied experimentally. Distilled water was used as the base liquid and 60–120-μm coal particles as solid inclusions. The coal concentration in a droplet was varied in the range of 0.5–10 %. The main parameters of particle agglomeration in a droplet were recorded using the shadow method. Particle sedimentation velocities and heights of the agglomerated particle layers in a droplet were recorded as part of the experiments. These characteristics were affected by the initial liquid volume, relative particle concentration and size. Equations were obtained for the relationships determined in the experiments. These equations can help extrapolate the corresponding functions to wider variation ranges of input parameters. Recommendations have been formulated on managing the processes of slurry droplet stratification over time.

Ore Elements and Minerals in The Elements of Alaid Volcano (Kuril Island Arc)

Sublimates tested in 2013–2020 were studied. in the near-crater zone and on the slopes of the Alaid volcano, located in the Kuril Island arc. It has been established that in the near-crater zone there are native metals confined to zones of acid leaching, within which the original lavas and tuffs have been transformed into opal-like formations or rocks sharply enriched in ferric hydroxides. In these zones, the presence of native gold, palladium, silver, chromium, copper, zinc and alloys of gold and palladium, copper and zinc, copper and tungsten has been established. On the slopes of the Alaid volcano, the range of minerals in sublimates is wider, while the temperature of their formation is lower. Of the ore minerals, copper-containing ones predominate, and sublimates with vanadium-containing minerals belonging to hydrous oxides and vanadate-silicates are established. Two genetic types of slope sublimates have been identified: 1) minerals crystallizing from hydrothermal or steam-hydrothermal solutions near the outcrops of near-surface fumaroles and 2) copper and ferruginous colomorphic formations formed as a result of sedimentation from colloidal solutions in the shallow waters of drying up reservoirs, including small and large puddles.

Colloidal Stabilizer‐Mediated Crystal Growth Regulation and Defect Healing for High‐Quality Perovskite Solar Cells

AbstractHigh‐quality perovskite (PVK) films is essential for the fabrication of efficient and stable perovskite solar cells (PSCs). However, unstable colloidal particles in PVK suspensions often hinder the formation of crystalline films with low defect densities. Herein, ethylenediaminetetraacetic acid (EDTA) as a colloidal stabilizer into lead iodide (PbI2) is introduced colloidal solutions. EDTA forms chelated complexes with Pb2+, enhancing the electrostatic repulsion and steric hindrance between colloidal particles. This stabilizes the particles and inhibits disordered motion (Brownian motion) and excessive aggregation. As a result, PbI2 films with a uniform hole distribution are formed, providing ample pathways for subsequent PVK film growth and sufficient space. During the film formation process, the replacement of molecules by formamidinium iodide (FAI) and EDTA slows down crystallization, ultimately leading to PVK films with large grain sizes and low defect density. By using this approach, champion power conversion efficiencies (PCEs) of 24.05% for FA0.97Cs0.03PbI3 PSC, 11.08% for CsPbBr3 PSC, and 25.19% for FA0.945MA0.025Cs0.03Pb(I0.975Br0.025)3 PSC are achieved. Moreover, the EDTA‐based FA0.97Cs0.03PbI3 device retains over 90% of its initial PCE after 1000 h at the maximum power point (MPP) under continuous illumination.

Cerebrospinal fluid-induced stable and reproducible SERS sensing for various meningitis discrimination assisted with machine learning

Cerebrospinal fluid (CSF)-based pathogen or biochemical testing is the standard approach for clinical diagnosis of various meningitis. However, misdiagnosis and missed diagnosis always occur due to the shortages of unusual clinical manifestations and time-consuming shortcomings, low sensitivity, and poor specificity. Here, for the first time, we propose a simple and reliable CSF-induced SERS platform assisted with machine learning (ML) for the diagnosis and identification of various meningitis. Stable and reproducible SERS spectra are obtained within 30 s by simply mixing the colloidal silver nanoparticles (Ag NPs) with CSF sample, and the relative standard deviation of signal intensity is achieved as low as 2.1%. In contrast to conventional salt agglomeration agent-induced irreversible aggregation for achieving Raman enhancement, a homogeneous and dispersed colloidal solution is observed within 1 h for the mixture of Ag NPs/CSF (containing 110–140 mM chloride), contributing to excellent SERS stability and reproducibility. In addition, the interaction processes and potential enhancement mechanisms of different Ag colloids-based SERS detection induced by CSF sample or conventional NaCl agglomeration agents are studied in detail through in-situ UV–vis absorption spectra, SERS analysis, SEM and optical imaging. Finally, an ML-assisted meningitis classification model is established based on the spectral feature fusion of characteristic peaks and baseline. By using an optimized KNN algorithm, the classification accuracy of autoimmune encephalitis, novel cryptococcal meningitis, viral meningitis, or tuberculous meningitis could be reached 99%, while an accuracy value of 68.74% is achieved for baseline-corrected spectral data. The CSF-induced SERS detection has the potential to provide a new type of liquid biopsy approach in the fields of diagnosis and early detection of various cerebral ailments.