Preliminary Stability Research Articles

A Preliminary Stability Assessment of Three State-of-the-Art CAD/CAM Materials Under Human Gingival Cell Culture.

CAM/CAD composites are widely used as dental restoration materials due to their resistivity to wear. The purpose of this study was to determine the effect of human gingival fibroblast cells on three different computer-aided design/computer-aided manufacturing (CAD/CAM) hybrid materials with resin-based composites (RBC) and to assess their stability following cell growth. The CAM/CAD dental materials were investigated in different conditions as follows: (i) cells (human gingival fibroblasts, HFIB-Gs) incubated over the material for each sample, denoted as A; (ii) reference, the raw material, denoted as B; and (iii) materials incubated in DMEM medium, denoted as C. We employed Vicker's hardness test, EDS, SEM, and AFM measurements as well as Raman spectroscopy to carefully characterize the surface modifications and the structural integrity of the CAM/CAD materials before and after fibroblast cell culture. The analysis of the surface in terms of morphology, roughness, structure, and plastic deformation presented no significant difference after incubation in cells or in media, proving their extraordinary stability and resilience to biofilm formation.

Glycerol-Derived Water-Lean Amines for Post-Combustion CO2 Capture: The Improvement in Capacity and Viscosity.

Water-lean absorbents are regarded as a new generation of post-combustion CO2 capture technology that could significantly relieve those drawbacks posed by traditional aqueous alkanolamines. However, the exponential increase in viscosity during CO2 absorption remains an urgent issue that needs to be resolved before their practical deployment. In this work, novel water-lean amines based on biomass glycerol have been devised as single-component CO2 absorbents with low viscosity (79~110 cP at 25 oC, 29~39 cP at 40 oC) under high capacity (12~18 wt% at 25 oC, 10~17 wt% at 40 oC). The captured CO2 could be smoothly released by thermal desorption. Results from preliminary stability test and 10 absorption-desorption cycles showed that such non-aqueous absorbents had significant structural toughness as well as reusability. Spectroscopic measurements including 13C NMR and in situ FTIR were performed to gain mechanistic insights by monitoring the entire CO2 absorption and desorption process, while DSC, VLE and DFT calculations provided rational interpretation for reaction kinetics and thermodynamics. The synergistic promotion of glycerol ether group on both CO2 chemical and physical absorption was also verified under high pressure conditions.

Gel cream loaded with <i>Lafoensia pacari</i> phenolics-containing extract with antioxidant and photoprotective activities

Lafoensia pacari`s leaves have phenolic compounds which may lead to photoprotective and antioxidant properties. The aim of this study was to investigate these activities in the L. pacari phenolics-containing extract (LPE) and to obtain gel cream formulations containing LPE and that have photochemoprotective activity. Phenolic compounds and antioxidant activity were determined. Polyacrylamide & C13-14 Isoparaffin & Laureth-7 (Focus gel® 305) formulation, it added synthetic sunscreen Ethylhexyl methoxycinnamate (Eusolex 2292®) or with both Eusolex 2292® and LPE were prepared. The in vitro sun protection factor (SPF) of these formulations was determined by diffuse reflectance spectroscopy. Preliminary stability of gel creams was evaluated. Total phenols and flavonoids content were 3.31% and 0.315%, respectively. LPE showed antioxidant activity by DPPH, with an EC50 of 5.3 µg. mL-1 and by FRAP methods, in which 1g of the extract reduces 323.62 µM/L of ferrous sulfate. LPE showed an additive effect on the value of SPF when associated with Ethylhexyl methoxycinnamate, an increase of 22% in FPS of the formulation (F3). The data obtained allow us to suggest a trend towards the photoquimoprotective effect of the L. pacari phenolics-containing extract in the studied conditions.

Formulating an Innovative Emulsion Based on Poloxamer 407 Containing Oregano and Thyme Essential Oils as Alternatives for the Control of Mastitis Caused by Staphylococcus aureus

Antimicrobial resistance poses a significant challenge in human and veterinary medicine, primarily due to the overuse and misuse of antimicrobial agents. This issue is especially problematic when treating bovine mastitis, a prevalent infection in dairy cattle often caused by Staphylococcus aureus. We developed a sterile emulsion incorporating essential oils (EOs) of Origanum vulgare and Thymus vulgaris, known for their antimicrobial properties. The formulation based on poloxamer 407 was designed for intramammary or topical application on bovine teats. The most promising emulsion was subjected to preliminary stability testing at various temperature conditions over a 35-day period, during which its physicochemical characteristics, texture profile, and film-forming capacity were assessed. In vitro assays were used to evaluate its efficacy against both antimicrobial-sensitive and -resistant S. aureus strains. Thymol was identified as the predominant bioactive compound in the EOs. The formulation, containing 10% (w/w) EOs, exhibited antimicrobial activity against all tested strains and remained stable without phase separation. The emulsion demonstrated film-forming properties along with a satisfactory texture profile. These findings suggest that the emulsion has potential as an alternative therapeutic approach for the treatment of antimicrobial-resistant S. aureus infections in bovine mastitis, highlighting the potential of natural compounds in combating AMR. Further clinical studies are necessary to confirm the safety and therapeutic efficacy of the emulsion in vivo.

Direct Laser Interference Patterning of Fluorine‐Doped Tin Oxide as a Pathway to Higher Efficiency in Perovskite Solar Cells

AbstractImproving light‐trapping capabilities through surface microstructuring of transparent conductive oxides is a promising approach to enhance solar cell efficiency. This study focuses on treating fluorine‐doped tin oxide (FTO) thin films using four‐beam direct laser interference patterning (DLIP) to create dot‐like periodic surface microstructures. The surface analysis using scanning electron microscopy and confocal microscopy reveals the presence of a periodic square grid of microcraters with a spatial period of ≈700 nm and an average depth ranging between 4 and 18 nm. These structures enhance the dispersion of incoming light up to 1000% in the visible and NIR spectra. When integrated into metal halide perovskite solar cells, FTO films patterned using low fluence conditions lead to a notable increase in the power conversion efficiencies (PCEs) compared to those made using untreated FTO. Importantly, preliminary stability tests on devices based on patterned FTO substrates show significantly improved stability compared to those fabricated using reference unpatterned substrates. These findings demonstrate that a DLIP treatment of FTO substrates is a promising technique that can substantially enhance the efficiency and stability of perovskite photovoltaic devices.

(SiFA)SeFe: A Hydrophilic Silicon-Based Fluoride Acceptor Enabling Versatile Peptidic Radiohybrid Tracers.

The radiohybrid (rh) concept to design targeted (and chemically identical) radiotracers for imaging or radionuclide therapy of tumors has gained momentum. For this strategy, a new bifunctional Silicon-based Fluoride Acceptor (SiFA) moiety (SiFA)SeFe was synthesized, endowed with improved hydrophilicity and high versatility of integration into rh-compounds. Preliminary radiolabeling and stability studies under different conditions were conducted using model bioconjugate peptides. Further, three somatostatin receptor 2 (sstR2)-targeted rh-compounds ((SiFA)SeFe-rhTATE1-3, TATE = (Tyr3)-octreotate) were developed. Compound (SiFA)SeFe-rhTATE3, enables labeling with 18F for PET imaging or chelation of 177Lu for therapy. The rh-compounds possess comparable receptor binding affinity and in vitro performance as good as the clinically proven gold standards. SstR2-specificity was further shown for (SiFA)SeFe-rhTATE2 using the chicken chorioallantoic membrane (CAM) model. The biodistribution of two compounds in mice showed high accumulation in tumors and excretion via the kidneys, demonstrating the clinical applicability of the (SiFA)SeFe moiety.

Synthesis and Characterization of Carboxymethylcellulose-Functionalized Magnetite Nanoparticles as Contrast Agents for THz Spectroscopy with Applications in Oncology

This paper describes a process to obtain magnetite functionalized with carboxymethylcellulose via coprecipitation by means of a preliminary stabilization of magnetite in citric acid. The magnetite assemblies successfully passed in vitro and in vivo tests of bio-compatibility. The measured values for the dielectric loss factor are remarkably high, a prerequisite for the assemblies’ potential use as contrast agents. Broadband THz spectroscopy analysis was performed to identify the most relevant frequency bands (here, 3.2–4 THz) where the signal difference between normal cells and cancer cells is relevant for the particles’ potential use as contrast agents for THz imaging, with applications in oncology.

Optimization of Solid Lipid Nanoparticle Formulation for Cosmetic Application Using Design of Experiments, PART II: Physical Characterization and In Vitro Skin Permeation for Sesamol Skin Delivery

Our research focuses on evaluating the preliminary stability of solid lipid nanoparticles (SLNs) in order to identify an optimal formulation for studying the skin penetration of SLNs loaded with sesamol, with a view to developing potential cosmetic applications. For this study, SLNs were prepared with varying lipid and surfactant compositions and produced through homogenization and ultrasonication. The particle size (PS), polydispersity index (PDI), zeta potential (ZP), and encapsulation efficiency (EE) were analyzed for the different formulations. We identified OP2Se as the optimal formulation for skin penetration assessment due to its stable PS, PDI, ZP, and EE over time, with a Turbiscan Stability Index (TSI) below 1 after a month, indicating favorable stability conditions. The in vitro skin permeation study compared sesamol-loaded SLNs with a control sesamol hydrogel, revealing controlled release characteristics ideal for localized skin effects without significant bloodstream penetration, attributed to the SLNs’ 200 nm particle size. Further exploration could enhance skin retention and targeting, potentially extending penetration studies and reducing particle size to improve accumulation in hair follicles. Exploring SLN applications beyond sesamol, such as incorporating mineral filters for suncare, offers promising avenues, underscoring SLNs’ versatility in cosmetic formulations and skincare applications.

Development of an Antioxidant, Anti-Aging, and Photoprotective Phytocosmetic from Discarded Agave sisalana Perrine Roots

The primary source of hard fiber globally is Agave sisalana Perrine, also known as sisal. In areas where sisal is grown, the roots of the plant are usually left in the field after it has stopped producing, which leads to soil degradation and decreased sisal productivity. It is, therefore, critical to find alternatives to reuse this waste. This study explores the potential use of sisal waste in the cosmetic industry by incorporating a hydroethanolic extract (HER) into a cream–gel formulation, taking advantage of the plant’s recognized ethnopharmacological value. The study involves analyzing the extract’s phytochemical composition (flavonoids) and evaluating its cytotoxicity. Subsequently, the antioxidant and antiglycation activities of the extract and cream–gel are evaluated, as well as ex vivo ocular toxicity, photoprotective activity, and preliminary stability analyses. The HER extract showed a flavonoid composition (catechin, kaempferol, isorhamnetin, and chrysin) and maintained cell viability above 70% throughout all time points analyzed in the MTT assay. Furthermore, the extract and the formulation demonstrated proven antioxidant and antiglycation activities. The cream–gel’s UVB and UVA protection effectiveness with the HER was comparable to that of synthetic UVB/UVA sunscreens, with the samples proving nonirritating and stable. In conclusion, the extract has a significant presence of flavonoids, and the cream–gel developed with it did not present cytotoxicity and met the stability requirements, indicating phytocosmetic potential with antioxidant, antiglycation, and photoprotective properties.

Development and preliminary stability evaluation of serum with <i>Aloe vera</i> and <i>Matricaria chamomilla</i> extracts

The use of phytocosmetics has been increasing in the beauty industry, in various treatments such as anti-aging, whitening and anti-acne. Serum is a pharmaceutical form similar to a gel, with greater fluidity, as well as soothing and anti-inflammatory actives, which can be suitable candidates for acne-prone skin. Thus, the objective of this study was to carry out the development of formulations based on Natrosol® serum containing extracts of aloe vera and chamomile in five different concentrations and to evaluate their preliminary stability. For this, tests were carried out in 6 ice-thaw cycles in which the samples were subjected to temperatures of 45±2°C and 5±2°C, each for 24 hours, totaling one cycle. During the end of each cycle, the samples were evaluated according to organoleptic characteristics, pH and density, being compared with the control (which remained at room temperature). All analyzed parameters remained according to specifications throughout the test, except for odor, which showed a slight change. It is suggested that during the conditions of this study, the stability was maintained, according to the stability guide and therefore the formulations can proceed to further steps such as the long-term stability test.

Losartan potassium liquid formulation for paediatric hospital use: development and stability evaluation

ObjectivesThis study aimed to develop a liquid oral formulation containing losartan potassium, an angiotensin II receptor antagonist drug used for its antihypertensive activity, and to perform a preliminary stability assessment...

Key Technology Research and Equipment Development of Automatic Spool Feeding Device

To solve the problems of high labour intensity and low efficiency of artificial spool feeding, an automatic spool feeding device is developed. SolidWorks is used for overall structural scheme design and determination of design parameters. The kinematic equation of the chain conveyor line is established, a mathematical model is solved with MATLAB, and sprocket, and chain parameters are selected. The clamping mechanism and turnover mechanism are designed, theoretical analysis of the key structure is completed. Dynamic simulation of the chain conveyor line is carried out by ADAMS, and preliminary operational stability is determined by combining motion curves. The test prototype is developed for feeding tests and measurement of the operating parameters. The test results show that the efficiency of machine feeding is 13% higher than that of manual feeding, the average feeding time is 43% lower, the halt waiting time is 43% lower, and the operating parameters are by the theoretical design and the work is reliable. The research results can provide a reference for similar spool-feeding devices.

Physical Modelling Of Rock Bags Under Wave Attack

In 1987, rock bags were developed by Kyowa in Japan to protect against erosion from hydraulic processes in riverine, lake, coastal and marine environments. Since 2020, rock bags have been used as a temporary or emergency coastal protection unit for seawalls on some beaches in Australia (e.g. Wamberal Beach and Collaroy Beach). These structures have typically been built against a pre-existing dune or eroded dune scarp for protection of landward coastal assets. While a limited amount of hydraulic scale modelling has been undertaken for some rock bag applications, their behaviour in shallow water, coastal environments under wave forces had not previously been quantitively evaluated. A two‑stage physical modelling program was carried out to assess the behaviour of rock bags when used in this emerging erosion protection application. As a result of the scale laboratory tests for shallow water seawalls constructed from rock bags, specific results were obtained for a proposed structure at Stockton Beach (Newcastle, Australia) as well as producing generic design information that could be applied at other locations. As expected, the design wave height for rock bag damage (displacement) was found to be inversely proportional to wave period. Preliminary design stability curves were developed for rock bags under monochromatic and irregular wave attack. In addition to displacement, settlement of the rock bags was observed during the modelling, and it is recommended that consideration should be given to vertical settlement over the design life of these structures. Wave runup was also found to be high; this is also an important consideration for future rock bag seawalls in either establishing the design crest level to prevent wave overtopping or adopting and managing a permissible amount of wave overtopping during a design event.

Development of Losartan Orally Disintegrating Tablets by Direct Compression: a Cost-Effective Approach to Improve Paediatric Patient's Compliance.

The development of suitable dosage forms is essential for an effective pharmacological treatment in children. Orally disintegrating tablets (ODTs) are attractive dosage forms that avoid swallowing problems, ensure dosage accuracy and are easy to administer as they disintegrate in the oral cavity. This study aimed to develop ODTs containing losartan potassium (LP) for the treatment of arterial hypertension in children. The ODTs, produced by the cost-effective manufacturing process of direct compression, consisted of a mixture of diluent, superdisintegrant, glidant and lubricant. Five superdisintegrants (croscarmellose sodium, two grades of crospovidone, sodium starch glycolate and pregelatinized starch) were tested (at two concentrations), and combined with three diluents (mannitol, lactose and sorbitol). Thus, thirty formulations were evaluated based on disintegration time, hardness and friability. Two formulations, exhibiting the best results concerning disintegration time (< 30s), hardness and friability (≤ 1.0%), were selected as the most promising ones for further evaluation. These ODTs presented favourable drug-excipient compatibility, tabletability and flow properties. The in vitro dissolution studies demonstrated 'very rapid' drug release. Preliminary stability studies highlighted the requirement of a protective packaging. All quality properties retained appropriate results after 12months of storage in airtight containers. In conclusion, the ODTs were successfully developed and characterised, suggesting a potential means to accomplish a final prototype that enables an improvement in childhood arterial hypertension treatment.

Quick Extraction of Joint Surface Attitudes and Slope Preliminary Stability Analysis: A New Method Using Unmanned Aerial Vehicle 3D Photogrammetry and GIS Development

The present study proposes a preliminary analysis method for rock mass joint acquisition, analysis, and slope stability assessment based on unmanned aerial vehicle (UAV) photogrammetry to extract the joint surface attitude in Geographic Information Systems (GIS). The method effectively solves the difficulties associated with the above issues. By combining terrain-following photogrammetry (TFP) and perpendicular and slope surface photogrammetry (PSSP), the three-dimensional (3D) information can be efficiently obtained along the slope characteristics’ surface, which avoids the information loss involved in traditional single-lens aerial photography and the information redundancy of the five-eye aerial photography. Then, a semi-automatic geoprocessing tool was developed within the ArcGIS Pro 3.0 environment, using Python for the extraction of joint surfaces. Multi-point fitting was used to calculate the joint surface attitude. The corresponding attitude symbols are generated at the same time. Finally, the joint surface attitude information is used to perform stereographic projection and kinematic analysis. The former can determine the dominant joint group, and the latter can obtain the probability of four types of failure, including planar sliding, wedge sliding, flexural toppling, and direct toppling. The integrated stability evaluation method studied in this paper, which combines a 3D interpretation of UAV and GIS stereographic projection statistical analysis, has the advantages of being efficient and user-friendly, and requires minimal prior knowledge. The results can aid in the geological surveys of slopes and guide engineering practices.

Assessing the stability of underground caves through iSUMM (innovative, straightforward, user-friendly, mechanically-based method)

A huge number of sinkhole events has been recorded in different Italian urban areas, with an occurrence frequency largely increasing in the last decades, sometimes even causing loss of human lives. The main reason for such catastrophic events is the presence of man-made underground cavities, excavated within soft rocks, several decades ago and then abandoned, at shallow depths. Here, the possibility of interaction with overlying buildings and infrastructures and the corresponding sinkhole hazard is relatively high. In such contexts, the low mechanical properties of the soft rock formations where the cavities have been excavated, like those formed of calcarenites, which outcrop in large areas of Southern Italy, and their high susceptibility to weathering processes, represent one of the most important predisposing factors for instability. Therefore, assessing the stability of underground cavities is crucial for land management and planning purposes. The mechanically-based stability charts developed by Perrotti et al. (Int J Geomech 18(7):04018071, 2018) have proved to be a valid tool for preliminary stability assessment and, although allow to identify an eventual proneness of the cave to instability, they do not provide quantitative assessment about the safety margin itself. In that regard, this study intends to present the most recent outcomes obtained in the development of the methodology and is aimed at promoting an enhanced way for their application, so that the charts can become an operative tool for preliminary sinkhole hazard assessment in similar regions in the world.

Extraction Optimization and Qualitative/Quantitative Determination of Bioactive Abietane-Type Diterpenes from Three Salvia Species (Common Sage, Greek Sage and Rosemary) by 1H-qNMR.

The objective of this study was the optimization of the extraction process and the qualitative and quantitative determination of the bioactive metabolites: 12-O-methylcarnosic acid (12MCA), carnosic acid (CA), carnosol (CS), 7-O-methyl-epi-rosmanol (7MER) and rosmanol (RO) in infusions, decoctions, turbulent flow extracts, tinctures and oleolites from three Salvia species: Salvia officinalis L. (common sage, SO), Salvia fruticosa Mill. (Greek sage, SF) and Salvia rosmarinus Spenn (syn Rosmarinus officinalis L.) (rosemary, SR), using Quantitative Proton Nuclear Magnetic Resonance Spectroscopy (1H-qNMR). Regarding the aqueous extracts, decoctions appeared to be richer sources of the studied metabolites than infusions among the three plants. For SR, the turbulent flow extraction under heating was the most efficient one. The optimum time for the preparation of decoctions was found to be 5 min for SF and SO and 15 min for SR. It is noteworthy that SR tinctures were not stable in time due to decomposition of the abietane-type diterpenes CA and CS because of the polar solvent used for their preparation. Contrary to this finding, the oleolites of SR appeared to be very stable. Olive oil as a solvent for extraction was very protective for the contained abietane-type diterpenes. A preliminary stability study on the effect of the storage time of the SF on the abietane-type diterpenes content showed that the total quantity of abietanes decreased by 16.51% and 40.79% after 12 and 36 months, respectively. The results of this investigation also demonstrated that 1H-qNMR is very useful for the analysis of sensitive metabolites, like abietane-type diterpenes, that can be influenced by solvents used in chromatographic analysis.

A mathematical approach to calculating slope stability under physical triggering forces. Application to landscape mechanics

In the field of land management, the limit equilibrium calculation method is a mathematical method that harmonizes the complex interplay of diverse factors determining the slope stability. Rooted in mechanical and mathematical principles, this method has paramount significance for guiding the course of safe land management in mountainous regions, especially in the case of infrastructure development projects. Conventional limit equilibrium techniques, while provid- ing preliminary stability assessments, often neglect key factors that can trigger slope failure. These approaches traditionally ignore the spatial variations in soil properties, the temporal dy- namics of phenomena, the kinetic responses to external loads, the complexities of geological formations, and the influences of the hydrological and climatic conditions on slope stability. Our innovative method adopts an enriched mathematical framework that redefines the landscape of force equilibrium techniques. We meticulously tailor this framework by adapting the founda- tional relationships derived from the Mohr-Coulomb shear strength criterion to accommodate the spatially variable geomechanical parameters. This adaptation allows us to capture the nu- anced shifts in mechanical properties over the extent of the slope. Furthermore, we introduce supplementary equations that seamlessly integrate the influences of traffic-induced loads and hydraulic pressures, while also statistically quantifying the contributions of stabilizing struc- tures. To determine the efficacy of this geomatic and landscape-centric numerical tool, we have subjected it to rigorous testing on a test slope. The outcomes derived from our mathematical model reveal the primacy of traffic-related forces as the main destabilizing agents, contrasted with the strengthening effects of reinforcements in maintaining slope stability.

Preliminary Assessment of Badajo Cave (Segovia, Spain) Stability Using Empirical, Numerical and Remote Techniques

Badajo cave is a shallow cavity (hemispherical rock shelter) located in the valley of Clamores River (Segovia city, Central Spain). This small canyon carved in Cretaceous dolostones has numerous geosites, as well as a rich archaeological and historical heritage. There are dozens of rock outcrops in the valley’s cliffs and slopes, on both banks, where various types of sedimentary rocks can be easily recognized and differentiated, especially carbonates (dolostones and limestones), and mixed carbonate-detrital (dolomitic sandstones, calcareous silts, marls). The cave was formed by karstic and gravitational processes within a mixed dolomitic sandstones and limestones, and it has an important archaeological interest. This study proposes a preliminary stability analyses of the cave applying: (i) empirical approaches based on geomechanical classifications using Barton’s Q Index, Rock Mass Rating (RMR) and the recently created Cave Geomechanical Index (CGI); (ii) three-dimensional model generated with the remote photogrammetric technique Structure from Motion (SfM) to allow acquisition of data to complete values collected in the geomechanical station, and to create the numerical model of the critical sections of the cave; and (iii) numerical simulations using a 2D model based on the generalized Hoek and Brown failure criterion and a 3D wedge analysis. The results of the analysis show that the cave is stable, although it presents some places with small problems (falls of slabs and blocks) that deserve monitoring. Furthermore, the evaluation by the geomechanical classification Q and the corresponding abacus of cave stability indicates that it is located in the “transition” zone where attention is required. In addition, SfM photogrammetric technique makes possible to generate a geometric 3D model that allowed the acquisition of data that were difficult to take in situ. The geotechnical parameters obtained from the different methods complement each other, resulting in a more realistic engineering representation of the subsurface environment. As a conclusion, a graph showing the two empirical methodologies (Barton’s Q Index and CGI), and some recommendation for a future analysis are given.

Slope stability of reclaimed coal mines through a new water filling index

A common reclamation practice for closed coal surface mines is filling them with water to form pit lakes. The creation and sustainability of these lakes are significantly affected by the stability of the corresponding slopes. The present study provides a general framework for analyzing the water filling's effect on slope stability based on a new water filling index, which can indirectly consider the factors affecting the process and efficiently quantify the filling speed's influence. The assumptions of the proposed approach are thoroughly discussed, and the range of the water filling index is identified. Furthermore, the safety factor is calculated using the finite element method with the shear strength reduction technique during the filling process for various conditions (soil properties, slope geometry, hydraulic conditions, and water filling speed). Results are presented as normalized stability charts for practical use. During the water filling, the stability gradually decreases until the reservoir reaches a critical level of 10%–40% of the total height; it then increases to even more stable conditions than the initial one. Overall, the present analysis allows for the preliminary stability evaluation of a coal mine during the formation of a pit lake and the appropriate quantification of the water filling's effect.