Lactic Acid Solution Research Articles

Bacterial inhibition and biofilm eradication ability of low-toxic deep eutectic solvents prepared from lactic acid and quaternary ammonium compounds

In the present communication, the preparation of deep eutectic solvents (DESs) based on an aqueous solution of lactic acid (LA) and two different quaternary ammonium compounds, choline chloride (ChCl) and tetraethylammonium chloride (TEAC), is proposed for the application as an antibacterial agent. The antibacterial and cytotoxic properties of the DESs obtained were studied and found to be highly effective in inhibiting both Gram-positive and Gram-negative bacteria and eradicating bacterial biofilms. Moreover, the DESs obtained exhibited reduced cytotoxicity towards soft tissue cells compared to the aqueous LA solution. The excellent antibacterial properties and low cytotoxicity of the DESs prepared make them a promising candidate for the development of novel antimicrobial agents or antibacterial eutectogels for delivery systems and tissue engineering applications.

Bioactive Self-Polymerizing Resin with Surface Pre-Reacted Glass Ionomer Fillers for Suppressed Enamel Demineralization.

The treatment of damaged enamel surfaces involves modification of the enamel surface with artificial materials or the development of a pseudo-enamel, with research focusing on bioactive and biomimetic materials. In this study, a bioactive auto-polymerizing resin (APR) was developed by adding surface-pre-reacted glass ionomer (S-PRG) fillers of different quantities to APR. Its bioactive effects were evaluated via pH neutralization, ion release, and inhibition of enamel demineralization studies. The pH and fluoride ion release were measured using ion-specific electrodes, revealing that the APR disk with the S-PRG filler immediately neutralized the lactic acid solution (pH 4.0) through ion release. Inductively coupled plasma atomic emission spectrometry revealed that the Sr ion release peaked on the first day, with the other ions following the order F > B > Si > Al > Na, exhibiting a weekly decrease in the same order. Scanning electron microscopy was used to examine the enamel block morphology of the disks after 7 d of incubation, revealing enamel demineralization in disks without the S-PRG filler, whereas no demineralization occurred in disks with the S-PRG filler. APR containing the S-PRG filler demonstrated acid buffering suppressed enamel demineralization and bioactive properties.

Sequential application of cold plasma in chicken breast: Improvement of meat tenderness and bactericidal mechanism against histamine-producing Raoultella sp.

The feasibility of plasma-activated lactic acid solution (PALA) combined with dielectric barrier discharge (DBD) plasma treatment in chicken breast was evaluated. Results indicated that sequential plasma treatments slowed down the increase in the pH value and TVB-N value of meat during storage. Moreover, PALA treatment weakened the lipid oxidation triggered by DBD plasma treatment. Furthermore, centrifugal loss and shear force of chicken breast in the PALA-DBD group were reduced by 2.88% and 19.4%, respectively, and the myofibril fragmentation index was significantly increased compared to the control group, and PALA treatment increased free water content. Microbiological analyses showed that PALA-DBD treatment disrupted the cell membrane integrity of Raoultella sp., induced oxidative stress and reduced the activity of antioxidant enzymes (catalase and superoxide dismutase), led to the degradation of bacterial proteins and the disruption of α-helical structure.

Rapid treatment of LLZTO solid electrolyte surface impurities by lactic acid solution

Abstract LLZO solid-state electrolytes of the garnet type exhibit exceptional electrochemical stability towards lithium metal and possess a remarkable level of ionic conductivity, and thus are considered to be one of the most promising solid-state electrolytes for solid-state lithium-ion batteries. However, LLZO is unstable in humid air and reacts with H2O and CO2 in the air to form Li2CO3, which reduces the wettability with lithium metal and decreases the overall ionic conductivity of LLZO. In this paper, a novel, fast, and simple method, lactic acid treatment, is proposed. The results show that Li2CO3 on the LLZO surface can be completely removed by acid treatment for 30 seconds, resulting in a pure LLZTO surface and improved wettability with lithium metal. Meanwhile, the assembled lithium symmetric battery can be cycled stably for 240 hours at 0.2 mA/cm2.

Highly efficient p-p heterojunction Co3S4/NiS2 electrocatalyst for water splitting and electrochemical oxidation of organic molecules

Organic small molecular-assisted water splitting technology is an efficient and promising technology for hydrogen production, which can meet the needs of obtaining hydrogen energy and protecting the environment. Constructing heterojunctions to enhance the interfacial electron transfer and achieve bifunctionality represents a viable strategy for enhancing the performance of electrocatalysts. In this work, the hollow structure Co3S4/NiS2 p-p heterojunction catalyst has been successfully synthesized by one-step hydrothermal method. Only −0.184, 1.64, 1.44 and 1.56 V vs. RHE are required to drive 50 mA cm−2 for hydrogen evolution reaction (HER), oxygen evolution reaction (OER), urea oxidation reaction (UOR), oxygen evolution reaction in lactic acid solution (OER-LA), respectively. For two-electrode electrolytic process, the cell voltages only need 1.72 V, 1.51 V and 1.61 V to drive 50 mA cm−2 in 1 M KOH, 1 M KOH containing 0.5 M urea and 1 M KOH containing 0.5 M lactic acid electrolytes, and it operates continuously at 50 mA cm−2 for 200 h test without significant decay of activity in 1 M KOH containing 0.5 M lactic acid, showing excellent durability. Density functional theory (DFT) calculation reveals that the p-p heterojunction between Co3S4 and NiS2 facilitates the electron redistribution at interfaces, thereby promoting the electron migration. This work presents a strategic approach for fabricating advanced bifunctional electrocatalysts by employing metal sulfides to form heterojunction, thereby achieving enhanced electrocatalytic activities in both hydrogen production and organic molecule decontamination.

The Fatigue Behavior of Narrow Single-body Titanium Implants in Saline and Acidic Media.

The objective of this study was to examine how the saline and acidic environment affects the mechanical integrity of narrow single-body titanium implants for oral rehabilitation. Thirty titanium-base alloy implants with 2.5 mm diameter were placed into a polyacetal holder and coupled to a stainless-steel prosthetic cap for fatigue testing in three different environments, as follows: dry air; saline solution (pH at 7.6); and lactic acid solution (pH at 3.4). The fracture surfaces were analyzed using a Scanning Electron Microscope (SEM). Also, finite element analysis was carried out to estimate the maximum von Mises stresses. The fatigue resistance was higher in the group tested in dry air (60%), followed by saline solution (30%) and lactic acid (10%). Regardless of the environment, fracture occurred at the same region of the failed specimens in line with the highest stress concentration spots, according to the finite element analysis. SEM analyses revealed two distinct failure regions, both with the presence of fatigue streaks: fatigue and overload. A high incidence of secondary cracks was also noticed on the specimens exposed to the solutions. The present study revealed that both saline and acidic solutions significantly affect the fatigue resistance of narrow dental implants. Critical regions of the narrow implants were also susceptible to cracks and plastic deformation that should be taken into consideration in planning for oral rehabilitation.

Breaking barriers in pharmaceutical analysis: Streamlined UV spectrometric quantification and stability profiling of haloperidol and methylparaben in liquid formulations

This study aims to quantify haloperidol and methylparaben in a liquid pharmaceutical formulation (2 mg/ml) using UV spectrometry and the simultaneous equations method. Additionally, we explored the stability of haloperidol under various stress conditions. The UV analysis revealed maximum absorption peaks at 248 nm for haloperidol and 256 nm for methylparaben, using a 1 % (v/v) lactic acid solution as the solvent. Method validation, conducted according to ICH guidelines, affirmed the method's reliability, showing excellent results in terms of linearity, precision, accuracy, and sensitivity. The method allows direct application to finished products, enabling simultaneous quantification without extractions. Its simplicity, speed, and cost-effectiveness make it ideal for routine controls in pharmaceutical industry haloperidol solution analyses. The method extends to monitoring forced degradation, indicating photolytic and hydrolytic degradation under acidic and basic conditions, while affirming thermal and oxidative stability. This proposed UV spectrometric method serves as a compelling alternative to pharmacopeia-recommended techniques, simplifying simultaneous determination of the active ingredient and preservative. This streamlines analysis, reducing time and costs. Additionally, it proves valuable in small industries lacking sophisticated instrumentation, offering insights into active ingredient behavior during forced degradation.

Mechanical Properties of Alkasite Material with Different Curing Modes and Simulated Aging Conditions.

This study aimed to evaluate the micro-mechanical and macro-mechanical properties of self-cured and light-cured alkasite and to investigate how accelerated degradation in acidic, alkaline, and ethanol solutions affects the macro-mechanical properties of self-cured and light-cured alkasite. The specimens of the alkasite material (Cention Forte, Ivoclar Vivadent) were prepared according to the following three curing modes: (1) light-cured immediately, (2) light-cured after a 5-min delay, and (3) self-cured. Microhardness was tested before and after immersion in absolute ethanol to indirectly determine crosslink density, while flexural strength and flexural modulus were measured using a three-point bending test after accelerated aging in the following solutions: (1) lactic acid solution (pH = 4.0), (2) NaOH solution (pH = 13.0), (3) phosphate-buffered saline solution (pH = 7.4), and (4) 75% ethanol solution. The data were statistically analyzed using a two-way ANOVA and Tukey post hoc test. The results showed that the microhardness, flexural strength, and flexural modulus were significantly lower in self-cured specimens compared to light-cured specimens. A 5-min delay between the extrusion of the material from the capsule and light curing had no significant effect on any of the measured properties. A significant effect of the accelerated aging solutions on macro-mechanical properties was observed, with ethanol and alkaline solutions having a particularly detrimental effect. In conclusion, light curing was preferable to self-curing, as it resulted in significantly better micro- and macro-mechanical properties, while a 5-min delay between mixing the capsule and light curing had no negative effects.

Continuous co-digestion of sewage sludge and highly concentrated waste bioplastic hydrolyzate without shortening hydraulic retention time

Bioplastics have garnered substantial interest as alternatives to conventional petroleum-based plastics. However, their management and conversion to biogas continues to be significantly challenging. In this study, we evaluated the suitability of various plastics for hydrolysis at 160 °C for 12 h using different solvents. The biogas yield (BGY) of the monomers constituting these plastics and the obtained plastic hydrolyzates was comprehensively evaluated. When water was used as a solvent, 100 % hydrolysis of polylactic acid (PLA) and polybutylene succinate (PBS) was observed. When polybutylene adipate co-terephthalate (PBAT) and polyhydroxybutyrate (PHB) were hydrolyzed with water, the degradation ratio was approximately 30 %; however, using an aqueous lactic acid solution as a solvent improved the degradation ratio to 78 % and 100 %, respectively. In the BGY test of the plastic hydrolyzates, the biogas volumes derived from the hydrolyzates were 563, 461, 337, and 573 mL/g COD-added for PLA, PBS, PBAT, and PHB, respectively. With 1,160 gCOD/L waste PLA hydrolyzate, continuous co-digestion of sewage sludge and the hydrolyzate was conducted. Organic loading rates of sewage sludge and the hydrolyzate were 2.3 and 2.4 gCOD/L/d, respectively. The operation was stable and the methane production volume from the PLA hydrolyzate was 414 L/kgCOD-added. Using highly concentrated PLA hydrolyzate, the hydraulic retention time was 19.3 days, which was only 0.7 days shorter than that of anaerobic digestion of sewage sludge only (20 days). Therefore, highly concentrated PLA hydrolyzate maintains the retention time of normal sewage sludge digestion. Conclusively, the present study has crucial practical implications for plastic waste management.

A Novel Bio-Purification Process Employing an Engineered E. coli Strain for Downstream Processing of Lactic Acid Solutions from the Fermentation of Agro-Industrial by-Products.

This study aims to integrate a novel bio-purification process employing an engineered E. coli strain in the downstream processing of lactic acid (LA) fermentation broths from low-cost renewable biological feedstocks. Fermentation broth of candy waste and digestate mixture was used as a real biological feedstock. An engineered E. coli strain that selectively catabolize impurities without catabolizing LA was initially adapted on the biological feedstock, followed by shake flask experiments to prove the bio-purification concept. Scale-up and validation in a bench-scale bioreactor followed, before developing a semi-continuous membrane bioreactor (MBR) bio-purification process. The MBR bio-purification was assessed with biological feedstocks which simulated ultrafiltration or nanofiltration permeates. Incomplete removal of impurities and increased fouling was observed in the case of the ultrafiltration permeate. Contrarily, the nanofiltration permeate was successfully treated with MBR bio-purification, since low membrane fouling, 100% maltose and acetic acid removal, and no LA catabolism was achieved. MBR bio-purification as a post-treatment step in the downstream processing of LA was demonstrated as a promising technology for increasing the purity of LA solutions.

PENGARUH PERENDAMAN GIGI PADA KITOSAN SISIK IKAN HARUAN (Channa striata) TERHADAP PELEPASAN FOSFAT

Background: Chitosan solution from Haruan fish scales (Channa striata) can be used to maintain tooth enamel structure by reducing the rate of solubility of hydroxyapatite or tooth demineralization under acidic conditions. Chitosan haruan fish scale (Channa striata) has the potential to be an anti-demineralization agent. Objective: Analyze the effect of immersing teeth in chitosan solution of 2.5% and 5% Haruan fish scales (Channa striata) on levels of phosphate release. Method: This study used the true experimental method with a posttest-only control group design consisting of 3 treatment groups, namely the negative control, the 2.5% group and the 5% group. All groups were immersed in lactic acid solution pH 5.2. Measurement of phosphate release levels using a uv-vis spectrophotometer. Results: The results of the One Way Analysis of Variance (ANOVA) test obtained a value of p = 0.00 <0.05 which indicated that the hypothesis was accepted or that there was an effect of soaking the teeth in chitosan solution of Haruan fish scales (Channa striata) with a concentration of 2.5% and 5% on phosphate release . The Bonferroni Post Hoc Test showed that there were significant differences in all groups, namely the negative control group with the 2.5% and 5% groups, the 2.5% group and the 5% group. Conclusion: Chitosan from Haruan fish scales (Channa striata) concentrations of 2.5% and 5% are able to inhibit phosphate release on teeth and have the potential as alternative biomaterials in inhibiting tooth demineralization.Keywords: Caries, Chitosan, Demineralization, Haruan, Phosphate

Development of a hybrid bio-purification process of lactic acid solutions employing an engineered E. coli strain in a membrane bioreactor

BackgroundA potential alternative to lactic acid production through sugar fermentation is its recovery from grass silage leachate. The separation and purification of lactic acid from fermentation broths remain a key issue, as it amounts to up to 80% of its industrial production cost. In this study, a genetically engineered E. coli strain (A1:ldhA), that cannot catabolize lactic acid, has been used to selectively remove impurities from a synthetic medium comprising typical components (i.e., glucose and acetic acid) of green grass silage leachate. A systematic approach has been followed to provide a proof-of-concept for a bio-purification process of lactic acid solutions in a membrane bioreactor operating in semi-continuous mode.ResultsThe synthetic medium composition was initially optimized in shake-flasks experiments, followed by scale-up in bench-scale bioreactor. Complete (i.e., 100%) and 60.4% removal for glucose and acetic acid, respectively, has been achieved in batch bioreactor experiments with a synthetic medium comprising 0.5 g/L glucose and 0.5 g/L acetic acid as carbon sources, and 10 g/L lactic acid; no lactic acid catabolism was observed in all batch fermentation tests. Afterwards, a hybrid biotechnological process combining semi-continuous bioreactor fermentation and ultrafiltration membrane separation (membrane bioreactor) was applied to in-situ separate purified medium from the active cells. The process was assessed under different semi-continuous operating conditions, resulting in a bacteria-free effluent and 100% glucose and acetic acid depletion, with no lactic acid catabolism, thus increasing the purity of the synthetic lactic acid solution.ConclusionsThe study clearly demonstrated that a bio-purification process for lactic acid employing the engineered E. coli strain cultivated in a membrane bioreactor is a technically feasible concept, paving the way for further technological advancement.

Construction of Co3S4/MoS2 p-p heterojunction as an efficient catalyst for water splitting and electrochemical oxidation of organic molecules

Electrolysis of wastewater containing urea or small organic molecules while obtaining hydrogen energy is a promising strategy for realizing energy acquisition and environmental protection. Construction of semiconductor heterojunctions to regulate the transfer of interfacial electrons has been regarded as an efficient approach to improve the electrocatalytic performance of oxygen evolution reaction (OER) and hydrogen evolution reaction (HER) for the materials, and obtain the bifunctional electrocatalysts aiming to construct a water splitting cell using one non-precious metal material. Herein, a bifunctional Co3S4/MoS2 electrocatalyst with a p-p heterojunction and hollow structure has been successfully prepared through the precipitation-hydrothermal method, which presents the high bifunctional electrocatalytic performance due to the formed path of electron transfer in the heterojunction interface being favorable for OH- adsorption. The accelerated electron transfer in heterojunction interfaces endows Co3S4/MoS2 presenting the superior electrocatalytic performance including OER, urea oxidation reaction (UOR) and oxygen evolution reaction in lactic acid solution (OER-LA). At 50 mA cm−2, the voltages of HER, OER, UOR and OER-LA are −0.123, 1.511, 1.400, 1.440 V vs. RHE, respectively. In a two-electrode electrolytic cell using Co3S4/MoS2 as anode and cathode displays the outstanding electrocatalytic performance in 1 M KOH, 1 M KOH containing 0.5 M urea, and 1 M KOH containing 0.5 M lactic acid electrolytes, superior to the most reported materials. This research provides a strategy for the construction of advanced bifunctional electrocatalysts using metal sulfides to form heterojunction for realizing the high bifunctional catalytic activities in hydrogen production and organic molecule decontamination.

Microbiological evaluation of bovine carcasses decontaminated with lactic acid solution

Bovine meat is a nutritious food product that is highly susceptible to bacterial degradation. Organic acid spray washing can be used to reduce microbial populations in carcasses. This study aimed to examine the efficacy of lactic acid in reducing total coliforms and Escherichia coli and assess the effects of different lactic acid concentrations on meat. For this, bovine carcasses were classified into cleanliness categories and subjected to swab sampling before and after manual and automated washing with lactic acid solution at different concentrations (0, 0.5%, 1%, 2%, 3%, and 4%). Colorimetric analysis and lactic acid quantification of carcasses were performed at 0 and 24 h post mortem. The experiment followed a factorial design. Lactic acid inhibited microbial growth, particularly automated application of 3% lactic acid. Although minor changes in color were observed, lactic acid washing was beneficial from a microbial standpoint, effectively decontaminating bovine carcasses and leaving only minimum amounts of residual acid in meat.

Synthesis of L-Lactide from Lactic Acid and Production of PLA Pellets: Full-Cycle Laboratory-Scale Technology.

Lactide is one of the most popular and promising monomers for the synthesis of biocompatible and biodegradable polylactide and its copolymers. The goal of this work was to carry out a full cycle of polylactide production from lactic acid. Process conditions and ratios of reagents were optimized, and the key properties of the synthesized polymers were investigated. The influence of synthesis conditions and the molecular weight of lactic acid oligomers on the yield of lactide was studied. Lactide polymerization was first carried out in a 500 mL flask and then scaled up and carried out in a 2000 mL laboratory reactor setup with a combined extruder. Initially, the lactic acid solution was concentrated to remove free water; then, the oligomerization and synthesis of lactide were carried out in one flask in the presence of various concentrations of tin octoate catalyst at temperatures from 150 to 210 °C. The yield of lactide was 67-69%. The resulting raw lactide was purified by recrystallization in solvents. The yield of lactide after recrystallization in butyl acetate (selected as the optimal solvent for laboratory purification) was 41.4%. Further, the polymerization of lactide was carried out in a reactor unit at a tin octoate catalyst concentration of 500 ppm. Conversion was 95%; Mw = 228 kDa; and PDI = 1.94. The resulting products were studied by differential scanning calorimetry, NMR spectroscopy and gel permeation chromatography. The resulting polylactide in the form of pellets was obtained using an extruder and a pelletizer.

Development of the product for pre-milking cow-udder care on the basis of nisin and lactic acid

Nisin is a natural antibacterial substance widely used in the food industry and other spheres. As nisin has no bactericidal effect on gram-negative bacteria, it is combined with organic acids. The work aimed at developing a product for pre-milking cow udder care based on nisin and lactic acid. The bactericidal effect of the solutions of nisin and lactic acid was determined using the method of radial diffusion in agar on test cultures S. aureus (ATCC 25923), E. coli (055К59 №3912/41), and Str. uberis (field strain). In the experiment was used nisin produced by Glory Chem Co., Ltd. (China), lactic acid food 80 % solution (“Klebrig”, Belgium). The content of lactic acid in 1.5 % solution was sufficient for detecting bactericidal action on cultures S. aureus і Str. uberis, and 2 % for E. coli. Nisin solution had a lower bactericidal effect on coccal forms of micro-organisms compared to lactic acid and was ineffective for gram-negative rods. S aureus cultures were sensitive to nisin in the case of 1,5 and 2 % content in the solution, and Str. uberis – in the case of 0.5 to 2 %. The study showed that the minimal substance content in the study variant of the agent was 1 % nisin and 1 % lactic acid, to which E. coli and S. aureus cultures are sensitive, and Str. uberis – highly sensitive. In the case of 1 % nisin and 1.5 % lactic acid content, all the studied micro-organisms are sensitive to such substances combination. In the case of the content of 1 % nisin and 2 % lactic acid, they are practically susceptible. Thus, when combined, nisin and lactic acid enhance each other's bactericidal effect and are more effective when used on test cultures of micro-organisms than they are separately. We have developed the studied agent variant for pre-milking cow udder care with the content of nisin – 1 %, lactic acid – 2 %, glycerine – 4 %, allantoin – 0.5 %, and water up to 100 %. The minimum inhibitory concentration of the agent in case of 30-second exposition on test cultures S. aureus and E. coli was in case of dissolution 1:1 and for Str. uberis – in case of dissolution 1:15.

Influence of enzymatic extraction on the properties of corn starch

Corn starch played an important role in the food industries, while traditional extraction method involved using sulfur dioxide that could easily cause environmental pollution and equipment corrosion. Based on these drawbacks, the main objective of this study was to develop a feasible two-step enzymatic extraction method that could isolate starch from corn kernels and evaluate the properties of corn starch. The physicochemical components of steep liquor during enzymatic extraction were researched, the single-factor experiments and response surface methodology were used to optimize the steeping conditions. As a result, optimized steeping parameters of which the first step time was 30 h, the lactic acid solution concentration was 0.45%, the protease content was 480 U/g, the l-cysteine content was 0.45 g, and the second step time was 4 h. The corn starch yield (65.18%) with enzymatic extraction was higher than that of traditional extraction (54.73%). The solubility and swelling power of all starch samples were raised with the temperature increasing. The starch extracted using the enzymatic method had a higher amylose content (35.18%) and mean diameter (30.99 μm). Compared with commercial corn starch, the starch samples presented nearly identical FT-IR spectra, the same A-type crystalline pattern and morphology, furthermore, a higher resistant starch content was detected in corn starch obtained through extraction methods. This finding will provide useful information to food industries for extraction of corn starch.

POSS hybrid bioactive glass dental composite resin materials: Synthesis and analysis

IntroductionThis study create a dental composite by hybirding polyhedral oligo-sesquioxide nano monomers and bioactive glass BG 45S5. MethodsMake an experimental composite resin material with a 60 % filler content overall by substituting 20 % of the filler with BG 45S5. The experimental resins are grouped and named P0, P2, P4, P6 and P8 based on the reactive nanomonomer methacrylic acid-based multifaceted oligomeric sesquisiloxane (POSS) added by 2 %–8 % in the resin matrix portion of each group. Utilize a universal testing machine to analyze and compare the mechanical properties of these, then perform Fourier infrared spectrum analysis, double bond conversion analysis, and scanning electron microscope analysis. Based on this, after soaking the experimental materials artificial saliva solution or lactic acid solution for a while, the pH changes of the solution, the release of Ca2+ and PO43− ions, and the precipitation of apatite on the resin material's surface were tested and analyzed. Cell viability tests were used to assess sample cell viability and quantify the cytotoxicity of biological cells. The independent sample t-test was used to examine the group comparisons, and a difference was considered statistically significant at P<0.05. ResultsOutstanding mechanical and the double bond conversion are demonstrated by the nanocomposites when the POSS concentration hits 4 wt%. Agglomeration will cause the performance to deteriorate if the concentration beyond this threshold. In the P4 group, the double bond conversion, CS, and FS rose by a large margin, respectively, in comparison to the blank control group P0. Thankfully, the data demonstrate that adding POSS increases adhesive ability when compared to the blank group P0, however, there is no discernible difference between the other experimental groups. The acid neutralization capacity of the P4 group is essentially the same as that of the control group (P0). Ca2+ and PO43− ions are released in significant amounts following treatment with lactic acid solution, although this tendency is clearly less pronounced in artificial saliva. SEM and EDX data indicate that when the experimental resin is soaked in lactic acid solution and artificial saliva, apatite precipitation will happen on its surface. The results of the cell viability test indicated that there was no statistically significant difference between the experimental groups, and the viability of the cells increased after 24hours and 48 hours. ConclusionsPOSS was included into the composite resin along with 20% bioactive glass as a filler. When the proportion of POSS is less than 4%, the indices of composite resin materials rise in a dose-dependent way. When this value is surpassed, performance begins to deteriorate. The inclusion of POSS has no influence on the biological activity of the composites, which means that the hybrid composite resin is capable of acid neutralization, ion release, and apatite precipitation. Clinical SignificanceThe experimental composite resin can be used as an intelligent material in clinical treatment. It has the clinical application potential of preventing demineralization of tooth hard tissue, promoting remineralization, and improving edge sealing through apatite precipitation.

Enhancing the corrosion inhibition performance of Mannich base on mild steel in lactic acid solution through synergistic effect of allicin: Experimental and theoretical study

Protonated Mannich base N,N′-bis(3-oxo-3-phenylpropyl)ethane-1,2-diamine dihydrochloride (EDAM) was synthesized and its chemical structure was characterized by means of 1H NMR, 13C NMR, Fourier-transform infrared spectroscopy (FTIR) and elemental analysis. The synergistic inhibitive effect of EDAM with allicin on N80 steel in 15 % lactic acid solution at 363 K was investigated using weight loss experiments, electrochemical tests, and surface analysis techniques (including scanning electron microscopy (SEM), atomic force microscopy (AFM), X-ray Photoelectron Spectroscopy (XPS), and contact angle measurement), quantum chemical calculation and molecular dynamics (MD) simulation methods. The results show that the inhibition performance was significantly improved by combining EDAM and allicin. The inhibition efficacy (IE) reached 99.60 % at the mass ratio of 10:1 (EDAM/allicin) with total inhibitor dosage of 0.1 %. Electrochemical impedance test (EIS) proves that the charge transfer-controlled corrosion process is greatly hindered with the addition of allicin. The small changes in the corrosion potential of Tafel curves indicate that the complex system is a hybrid corrosion inhibition mechanism. SEM, AFM, XPS and contact angle surface analyses suggest that EDAM in cooperation with allicin forms a dense and strongly adsorbed protective film on the metal surface. The density functional theory (DFT) and molecular dynamics simulation (MD) calculations further elucidate the mechanism of the synergistic corrosion inhibition effect.

The Inhibitory Effect of CW CO2 Laser on Carieslike Lesion Initiation on Sound Enamel: an In Vitro Study

Although CO2 laser irradiation can decrease enamel demineralization, it has still not been clarified which laser wavelength and which irradiation conditions represent the optimum parameters for application as preventive treatment. One of the important applications of the laser is as a caries inhibition treatment of the sound dental tissues. This study aimed to assess the caries preventive potential of various CW CO2 laser parameters, and to explore the effect of laser power density, and the exposure time on the caries inhibition activity. Eighty one extracted human premolar teeth were irradiated with three output power: (1, 2, and 4) W, three spot diameter: (2, 2.83, and 4) mm, and three exposure times: (0.2, 0.4, and 0.8) sec of 10.6µm CW CO2 laser. Three teeth were used as a control group. All teeth were subjected to carieslike lesion formation by 3.5 pH lactic acid solution for 21 days. The teeth after that were sectioned into ground cross sections and the lesion depths were measured under polarizing microscope. The lesion depths of experimental samples were compared with those of the control samples. A single exposure to CW CO2 las er irradiation was found to be resulted in reduction of the carieslik e lesion depths. These reductions were up to 61%. The inhibition activity was related directly to the power density and inversely to the exposure time of CW CO2 laser radiation. The optimal parameters were 33W/cm2 power density and 0.2 exposure time. These finding should be reinforced with more laboratory, animal, and human studies with and without fluoride before clinical applications.