Phosphoric Acid Treatment Research Articles

A label-free fluorescence nanosensor based on nitrogen and phosphorus co-doped carbon quantum dots for ultra-sensitive detection of new coccine in food samples

In this paper, an innovative method for the sensitive detection of new coccine using N, P-doped carbon quantum dots (N,P-CQDs) as fluorescent nanosensor is reported for the first time. The sensing mechanism is based on the fluorescence quenching of N,P-CQDs by new coccine through inner filter effect (IFE). N,P-CQDs were prepared by simple hydrothermal treatment of citric acid, phosphoric acid and ethylenediamine. Under the optimal conditions, the new coccine has two good linear responses in the concentration range of 0.2–100 and 100–200 μM, and the detection limits are as low as 24.8 and 9.4 nM, respectively. Our developed nanosensor has been successfully used for the determination of new coccine in food samples with good precision and high accuracy. This work highlights the economic, rapid, simple, selective and ultra-sensitive for new coccine detection, and opens up a new way for the monitoring of new coccine in actual food samples.

Short-chain soluble polyphosphate fertilizers increased soil P availability and mobility by reducing P fixation in two contrasting calcareous soils.

Short-chain polyphosphate fertilizers have been increasingly applied in agriculture, but little is known about the chemical behaviors of polyphosphate in soils. Herein, a cylinder experiment was carried out to investigate the influences of different P types (i.e., mono-ammonium phosphate (MAP), phosphoric acid (PA) and ammonium polyphosphate (poly-P)) and their application methods (single vs split) on the mobility and availability of P in soil through a column millimeter-scale slice cutting method; meanwhile a soil microcosm experiment (560-day) was conducted to investigate the effects of different P types on phosphorus dynamic transformation. Polyphosphate addition significantly increased P mobility. The average distance of P downward movement (81.5 mm) in soil profile in the poly-P application treatment increased by 33.6% and 81.1%, respectively, compared to the MAP and PA treatments. Different P application methods also markedly influenced phosphorus mobility. For instance, the average distance of P vertical movement in the split P application treatment was 21.2% higher than in the single application treatment, indicating that split P addition significantly increased P downward movement. Moreover, polyphosphate application decreased soil P fixation by blocking the transformation of the applied-P from labile to recalcitrant forms (HCl-P and residual-P). Overall, our findings provide meaningful information to current phosphorus fertilization practice in increasing soil P mobility and bioavailability. We suggest that polyphosphate could be regarded as an alternative P source used in agriculture, and split polyphosphate application is recommended as an effective P fertilization strategy.

Comparative spectroscopic analysis, performance and emissions evaluation of Madhuca longifolia and Jatropha curcas produced biodiesel.

In order to fulfil the growing need to replace fossil fuels, investigations exploring the production of biodiesel from agricultural biomass have gained attention. In this study, biodiesels were produced from Madhuca longifolia and Jatropha curcas by means of pre-treatment followed by a two-step acid-base homogeneous catalyst method. These biodiesels were blended with diesel at different percentages. The efficacy of the process was examined using various characterization methods while the efficiency of the produced biodiesels was examined by their engine performance and emission tests. Both Madhuca and Jatropha-based biodiesels exhibited physiochemical properties like that of diesel. Biodiesels were produced by pre-treating with orthophosphoric acid and toluene. The second step involves acid esterification, followed by base transesterification. Raman spectra exhibited C=O stretching at 1725 cm-1 indicating conversion of Madhuca and Jatropha oil into biodiesel. Fourier transform infrared spectroscopy showed a strong presence of fatty acid profile and triglyceride ester linkage at 1744 cm-1. Ultraviolet-visible (UV) spectra confirmed the presence of conjugated dienes in the extracted biodiesels. UV absorbance at 320 nm decreased linearly with blend percentage. 1H and 13C nuclear magnetic resonance (NMR) confirmed the presence of methyl ester moiety at 3.6 δ (ppm) and methoxy carbon at 51.2 δ in biodiesel, distinguishing it from diesel. In the engine performance tests, the variations of brake specific fuel consumption, exhaust gas temperature and brake thermal efficiency versus brake power were studied. The emission tests of different blends were done in terms of carbon monoxide, nitrous oxide and unburnt hydrocarbon. The Jatropha biodiesel exhibited lower mean brake specific fuel consumption, exhaust gas temperature, emitted less carbon monoxide and unburnt hydrocarbon than Madhuca biodiesel. The average decrease in brake thermal efficiency was more in Jatropha biodiesel than Madhuca biodiesel. The present work uses for the first time treatment of ortho phosphoric acid and toluene to produce biodiesel followed by a two-step homogeneous acid-base catalyst method, drastically reducing free fatty acid value.

Recycling of Spent Reverse Osmosis Membranes for Second Use in the Clarification of Wet-Process Phosphoric Acid

Various techniques have been used to “clean-up” wet-process phosphoric acid such as precipitation, flotation and adsorption. To address the potential of membrane processes in the phosphoric acid clarification process, this study explores the benefits of membrane techniques as a green separation technique for phosphoric acid clarification in an eco-efficient way through the use of recycling spent reverse osmosis membrane. Regenerated membrane was used to study the phosphoric acid clarification at a laboratory scale. They were immersed in an oxidizer for at most seven days. The samples were characterized systematically before immersion in an oxidant media. In this study, the potential to regenerate spent membranes and application of this media to clarify the 29% P2O5 phosphoric acid was demonstrated. This study shows, through experiments, that the reverse osmosis (RO) membranes could achieve a rejection of 70% and 61% for suspended solid and organic matter, respectively. These promising results will pave the way for implementation of these membranes in phosphoric acid treatment. Moreover, besides being economically advantageous, the use of the spent membrane is likely an environmentally friendly route (no waste, no organic solvent and effluent to be regenerated later on).

The effect of universal adhesives on dentine collagen

ObjectivesThe purpose of the study was to evaluate the integrity of dentine type I collagen after self-etching (SE) treatments with strong and mild universal adhesives. MethodsCoronal dentine specimens (n=10/product) were imaged by optical microscopy and analyzed by ATR-FTIR spectroscopy before and after treatment with 32% phosphoric acid gel (PA-negative control), 17% neutral EDTA (ED-positive control) conditioners and Adhese Universal (AD), Clearfil Universal Bond Quick (CQ), G-Premio Bond (GP), Prelude One (PR) and Scotchbond Universal (SB) adhesives. From the spectroscopic analysis the following parameters were determined: a) Extent of dentine demineralization (DM%) and b) percentage area of the Amide I curve-fitted components of β-turns, 310-helix/β-turns, α-helix, random coils, β-sheets and collagen maturation (R) index. Statistical analysis was performed by one-way ANOVA (DM%), paired t-test/Wilcoxon test (Amide I components) and Spearman correlation coefficient (DM% vs Amide I components) at an a=0.05 level. ResultsPA, ED and GP removed the smear-layer and opened tubule orifices, whereas all other treatments removed only the intratubular smear-layer fraction. The ranking of the statistically significant differences in DM% was PA>GP>ED>AD, SB, CQ, PR, with AD being significantly different from PR. Regarding the Amide I components, PA demonstrated a significant reduction in β-turns, α-helices and an increase in β-sheets, GP a reduction in β-turns, AD an increase in β-turns and random coils, and CQ an increase in β-turns. PR, SB and ED showed insignificant differences in all the Amide I components. Significant correlations were found between DM%-random coils and DM%-R. SignificanceThe universal adhesives used in the SE mode induced none to minimal changes in dentine collagen structure, without evidence of the destabilization pattern observed after conventional phosphoric acid treatments.

Release Profiles of Dyes and Proteins from Calcium Phosphate Microspheres with Different Crystalline Phases

Calcium phosphate is attracting attention as a bone repair material and a controlled-release carrier of various drugs such as bone disease therapeutic agents and anticancer agents. Compared with some bioabsorbable polymers, calcium phosphates have the advantage of preventing a pH decrease in the surrounding body fluid. However, there are few studies comparing the effect of supporting substances with different physicochemical properties on the production of calcium phosphate microspheres with different crystalline phases. In this study, we investigated conditions for obtaining low crystallinity apatite and octacalcium phosphate (OCP) microspheres from calcium carbonate microspheres with different crystalline structures using a simple phosphoric acid treatment. Furthermore, we investigated the adsorption and release behavior of different dyes and proteins from the apatite and OCP microspheres. Overall, the factors governing the adsorption and release behavior are different depending on the molecular size and surface charge of the dye and protein adsorbates.

A facile synthesis of phosphorus doped Si/SiO2/C with high coulombic efficiency and good stability as an anode material for lithium ion batteries

Silicon (Si) has the drawbacks of large volume expansion and poor electronic conductivity to be overcome as the anode material for lithium ion batteries (LIBs). Herein, phosphorus (P) doped Si coated by dual layers of SiO2 and carbon (denoted as P-doped Si/SiO2/C) has been synthesized by a facile solid-state route. In that, commercial Si powder and polyvinyl butyral was used as raw material and carbon source, respectively. Importantly, the phosphoric acid was introduced as the doping agent, that also helped the formation of pure SiO2 coating layer rather than the mixture of SiO2 and less oxidized SiOx on surface of the Si material. The as-prepared P-doped Si/SiO2/C material exhibits an initial discharge capacity as high as 2860.3 mAh g−1 and an excellent inital coulombic efficiency of 86.7% at a current density of 200 mA g−1. After 150 cycles, charge capacity of 1389.8 mAh g−1 was retained, indicating the good cycle stability of P-doped Si/SiO2/C material, which is over three times higher than that of the Si/C material (449.2 mAh g−1) without phosphoric acid treatment. Additionally, a capacity enhancement of 25.7%, 40.7%, 79.1% 281.7% and 407.7% was achieved as compared to the Si/C material at the current densities of 100, 300, 600 1000 and 2000 mA g−1, respectively. The P-doping and SiO2 coating have played a significant role on the electrochemical performance by effectively improving the intrinsic electronic conductivity and further suppressing the volume expansion (~40%) of Si in charge-discharge tests respectively. It worth mentioning that the synthesis of P-doped Si/SiO2/C can be easily scaled up. Therefore, our work pave the way toward the industrilization of stable Si-based anode material with high capacity for LIBs.

Effect of amoxicillin on the enamel mineralization of SD rats

Objective: To determine whether amoxicillin had an effect on the enamel mineralization of SD rats. Methods: Eighteen SD rats were randomly divided into three groups. The rats in the control group were given distilled water. The rats in two experimental groups were administered 50 or 100 mg/kg amoxicillin by intragastric administration from day 3 to day 17 after birth. The general condition, the structure of liver and kidney, the enamel surface changes of mandibular first molars and incisors were observed. The changes of Ca/P ratio on enamel surface were analyzed by X-ray energy dispersive spectrometer (EDS). The surface morphology after phosphoric acid treatment was examined by scanning electron microscopy (SEM). Histological changes in the ameloblasts of mandibular incisors were analyzed by hematoxylin and eosin (HE) staining. Results: Compared with the control group, the general conditions as well as liver and kidney structures of SD rats in 50 and 100 mg amoxicillin groups had no significant differences. There was no obvious chalky changes on the first mandibular molars of SD rats in each group. All the incisors in 50 and 100 mg groups showed different degrees of chalkiness in the labial incisal 1/3 enamel. X-ray EDS analysis showed that the Ca/P ratios of occlusal and incisal 1/3 enamel in 50 and 100 mg groups (occlusal 1/3 of mandibular first molars: 1.51±0.03 and 1.52±0.02, incisal 1/3 of mandibular incisors: 1.46±0.01 and 1.43±0.01) was significantly lower than that in the control group (occlusal 1/3 of mandibular first molars: 1.67±0.41, incisal1/3 of mandibular incisors: 1.73±0.07) (P<0.05). However, there was no significant differences in the cervical 1/3 Ca/P ratio of mandibular first molars and incisors among the three groups (mandibular first molars: 1.56±0.04 for control group, 1.59±0.05 for 50 mg group and 1.57±0.04 for 100 mg group; incisors: 1.52±0.02 for control group, 1.47±0.01 for 50 mg group and 1.51±0.03 for 100 mg group) (P>0.05). SEM observation showed that the enamel rods of the first molars and incisors in the 50 and 100 mg group varied in size and arranged disorderly. The spaces between the enamel rods were larger than that in the control group and some areas even appeared large pits. HE staining showed that the gaps between ameloblasts in 50 and 100 mg groups were significantly wider than that in the control group. Conclusions: Intake of amoxicillin during the period of enamel development of SD rats might affect enamel mineralization.

Screening of slow pyrolysis routes for maximum biofuel production from Syzygium malaccense biomass by TGA-FSD and chemometric tools

The dependence of oil and its consequent commercial fluctuation make researchers to seek viable alternatives for their gradual replacement. The present work aims to evaluate the production of biofuels from the slow pyrolysis of the Syzygium malaccense biomass (Malay Apple) through thermogravimetric analysis (TGA-DTG), Fraser-Suzuki deconvolution and chemometric tools of multivariate analysis. Three chemical treatments (sodium hydroxide, sulfuric acid and phosphoric acid) were evaluated, as well as the variation in the heating rate and the consequent effects on the pyrolysis of biomass for the production of biofuels, totaling 16 pyrolysis routes (including the use of biomass no treatment). In the obtained data, multivariate analysis tools were used, looking for groups that presented favorable characteristics for the production of quality biofuels. Heatmap, k-means and SOM analysis indicated the routes that use phosphoric acid treatment and heating rates of 10 or 15 °C/min (Jap10 and Jap15, respectively) as relevant, because they have low lignin contents and high gaseous cellulose and hemicellulose contents.

Mitigation of ultrafine particulate matter emission from agricultural biomass pellet combustion by the additive of phosphoric acid modified kaolin

The emission of ultrafine particulate matter (PM0.2) originated from the agricultural biomass pellet combustion poses great threat to atmospheric environment and human health, which restricts its large-scale utilization. In this study, a new phosphoric acid modification method is proposed to improve the PM0.2 reduction efficiency by kaolin additive. The effects of phosphoric acid concentration and treatment time on the physicochemical properties of kaolin and on the mitigation of PM0.2 emission from the pellet combustion are investigated. Results indicate that phosphoric acid modification destroy the internal structure of kaolin by the leaching of Al cations and the formation of active free silica. Meanwhile, the pore structure increases after modification with residual P deposited on the surface, which results in better alkali capture ability of modified kaolin. With the addition of phosphoric acid modified kaolin, significant reduction of PM0.2 emission can be achieved and the reduction ratio is proportional to the acid concentration. The maximum PM0.2 emission reduction ratio reaches 64.5% for the kaolin additive modified by 12 mol/L phosphoric acid for 6 hours. Finally, the PM0.2 reduction mechanism is proposed based on the analysis results, which provides technical knowhow for the industrial application of agricultural biomass pellet combustion.

The effect of phytic acid on enzymatic degradation of dentin.

We evaluated the effect of phytic acid on matrix metalloproteinase (MMP)- or cysteine cathepsin (CC)-mediated dentin degradation. Demineralized dentin beams were divided into five groups (n=12) and treated with 1%, 2%, or 3% phytic acid or with 37% phosphoric acid. Untreated demineralized beams served as controls. After incubation for 1 or 3wk, dry mass loss was determined and aliquots of incubation media were analysed for cross-linked telopeptide of type I collagen (ICTP) fragments for MMP-mediated and c-terminal telopeptide of type I collagen (CTX) for cathepsin-k-mediated degradation. The direct effect of phytic acid was evaluated using MMP activity assay. Data were analysed using repeated-measures anova. ICTP releases with 1% and 2% phytic acid treatment were statistically significantly lower than those following phosphoric acid treatment at 3wk. The CTX release for phytic acid-treated beams at 3wk was not significantly different from that of untreated control beams, but it was significantly lower than that of phosphoric acid-treated beams. Their MMP activities at 3wk were not significantly different from those of the controls but they were significantly lower than those seen for phosphoric acid-treated beams. Compared to phosphoric acid, phytic acid treatment resulted in a reduced dentinal host-derived endogenous enzymatic activity and collagen degradation.

Solid waste sub-driven acidic mesoporous activated carbon structures for efficient uranium capture through the treatment of industrial phosphoric acid

This research study presents bio-char manufacturing from a solid waste (rice-straw) by low-temperature pyrolysis as a new trend. The as-produced char (named as BC) and its sub-driven hydrochloric and nitric acids activated carbons (labeled as HAC, and NAC respectively) were employed as adsorbents for uranium removal from a commercial grade of phosphoric acid. Morphological and structural characteristics of the presented carbonaceous structures were accomplished utilizing Fourier Transform Infrared (FTIR) Spectroscopy and Transmission Electron Microscopy (TEM). The uranium adsorption process via these three structures was then performed via the batch technique at various operating conditions. It was observed that the labeled structure as HAC has an increased adsorption capacity, compared to the other two adsorbents. Thus, it could attain a higher level of uranium species removal than both NAC and BC. Hence, HAC could be subsequently concluded as the structure of most suitability, among the three adsorbents, for uranium taking out from industrial phosphoric acid. The collected adsorption results by the three structures had been next examined by diverse kinetic and isotherm models. By all structures in this study, the presented adsorption processes were found to follow the pseudo-second-order model and perfectly match the Langmuir isotherm model. The applied three sorbents’ sorption capacity was 2.3, 2.5, and 3.3 for BC, NAC, and HAC, respectively. This confirms that the bio-char activation with hydrochloric acid has the most positive impact on bio-char’s sorption characteristics The various thermodynamics factors ( Δ H , Δ G and Δ S ) could reveal that these processes are exothermic exploits. • Conversion of a type of solid waste into carbon. • Activation of carbon by acids obtaining effective porous sorbents. • Application of these adsorbents in uranium recovery from industrial media. • Studying kinetics and thermodynamics parameters.

Functionalization of clay surface for the removal of uranium from water

A modification method of clay mineral surface was developed to improve its adsorption capacity of uranium. Uranium is a radionuclide with high toxicity and extremely long half-life, which can pollute the environment and endanger human health. This study proposes a new method of activation of clay mineral surface with phosphoric acid for rapid adsorption of uranium from aqueous solution. Compared with other modification methods, this method has the advantages of availability of raw materials, simple operation and good adsorption effects. It provides a cost-effective material to capture uranium ions from water. The essences of this new development are as following:• Activation and changes of clay minerals’ surface functionalities with the treatment of phosphoric acid• Controlled modifications of the surface properties of the clay towards the enhancement of U adsorption capacity• Rapid removal of uranium from water

Phosphoric acid and thermal treatments reveal the peculiar role of surface oxygen anions in lithium and manganese-rich layered oxides

The peculiar role of surface oxygen anions and surface reconstruction in Co-free layered Li[Li0.2Ni0.2Mn0.6]O2 is discovered by dilute phosphoric acid and thermal treatments.

The effect of Fit-checking material and various subsequent cleaning methods on the wettability of the dentin surface: an in vitrostudy

Background: GC Fit-checker is a modified polyvinyl siloxane impression material exclusively used to check the internal fit and improve the marginal fit of indirect restorations. An unpolymerized organic film is known to be leftover on the bonding surfaces after the silicone disclosing procedure. Residual silicone film being hydrophobic may alter the wettability of the cement to the tooth/metal surface, thus having a detrimental effect on the bond strength and retention of the restoration. Aim: This study aimed to evaluate the wetting of luting liquid (GIC) to tooth dentin surface after application of Fit-checker and evaluate the efficiency of various surface treatments in removing the residual silicone film. Materials and Methods: Extracted human molars were mounted on the acrylic block, and the tooth occlusal surface was ground flat till the dentin exposure. All the specimens were assigned into five groups: Group 1: without application of Fit-checker (control group); Group 2: without any surface treatment after peeling off Fit-checker; Group 3: surface treatment with wet pumice; Group 4: 37% phosphoric acid treatment; Group 5: 10% polyacrylic acid treatment. Later, Type 1 Glass Ionomer Cement (GIC) liquid drop was placed on the dentin and photographs were made horizontally using a standardized procedure. Contact angles were measured using AUTOCAD software. Obtained values were statistically analyzed using the One-way ANOVA test and Tukey’s Post hoc test. Samples of each group were examined using the scanning electron microscope. Results: Statistically significant difference was observed among all the groups except between Group 4 and Group 2 (p > 0.05). SEM images of various groups showed a significant difference in roughness patterns. Conclusion: Surface treatment with pumice and the rotary brush was an effective method among the three in cleaning the residual silicone film.

Comparison of Electropolishing of Aluminum in a Deep Eutectic Medium and Acidic Electrolyte

Research advances in electropolishing, with respect to the field of metalworking, have afforded significant improvements in the surface roughness and conductivity properties of aluminum polished surfaces in ways that machine polishing and simple chemical polishing cannot. The effects of a deep eutectic medium as an acid-free electrolyte were tested to determine the potential energy thresholds during electropolishing treatments based upon temperature, experiment duration, current, and voltage. Using voltammetry and chronoamperometry tests during electropolishing to supplement representative recordings via atomic force microscopy (AFM), surface morphology comparisons were performed regarding the electropolishing efficiency of phosphoric acid and acid-free ionic liquid treatments for aluminum. This eco-friendly solution produced polished surfaces superior to those surfaces treated with industry standard acid electrochemistry treatments of 1 M phosphoric acid. The roughness average of the as-received sample became 6.11 times smoother, improving from 159 nm to 26 nm when electropolished with the deep eutectic solvent. This result was accompanied by a mass loss of 0.039 g and a 7.2 µm change in step height along the edge of the electropolishing interface, whereas the acid treatment resulted in a slight improvement in surface roughness, becoming 1.63 times smoother with an average post-electropolishing roughness of 97.7 nm, yielding a mass loss of 0.0458 g and a step height of 8.1 µm.

Transition Metal Oxide/ Metal-Organic Framework Hybrid Structures for Efficient Bifunctional Oxygen Electrocatalysis in Alkaline Environments

Use of regenerative fuel cells (RFC) requires bifunctionality in oxygen electrocatalysis of oxygen reduction reaction (ORR) and oxygen evolution reaction (OER) to decrease weight and cost for efficient energy conversion. Many RFC based technologies have used noble metals such as Pt and its alloys (Pt/Ir or Pt/Ru) due to their efficient catalytic activity, selectivity and stability in harsh environments. However, their susceptibility to fast degradation during operation, as a result of catalyst agglomeration and poisoning, has driven research to find alternatives. Non-precious transition metal oxides (TMO) including Fe3O4, MnOx and Co3O4 have attracted significant attention as a potential candidate [1].We utilized a hybrid structure where terephthalic acid ligand, cobalt and cerium nitrate salts, and solvents are subjected to a hydrothermal process at 160ºC for 24 h, a phosphoric acid treatment, an atomic layer deposition (ALD) of titania or zirconia, and finally a heat treatment in air. The phosphate group formed by the acid treatment is believed to have formed strong anchoring sites for ALD nanodots on the novel metal organic framework (MOF)-derived structure, which also results in a dispersed distribution of catalytically active sites.The hybrid catalyst where TiO2 nanodots are uniformly anchored on phosphorylated MOF by ALD showed good ORR and OER performance in 0.1 M KOH in terms of onset/half-wave potential, electron transfer number, and current density when comparing to the performance of Pt/C (for ORR) and IrO2 (for OER). In addition, an activation of catalytic sites can be realized by a proper engineering of interfaces in each hybrid systems. Materials characterization emphasizes a strong adhesion of metal oxides upon MOF structures, thus providing ample surface interactions for favorable reaction route is important.This project was funded by NASA Advanced STEM Training and Research (ASTAR) Fellowship.

Phosphorus-doped mesoporous carbon derived from waste tires as anode for K-ion batteries

Recycling of waste tires is an important technology due to the health and environmental problems caused by them. Herein, we developed a low-cost method to prepare phosphorus-doped mesoporous carbon (PMC) by a preferred phosphoric acid treatment and high temperature calcination process of waste tires. After doping with phosphorus, the PMC electrode exhibited improved reversible capacity (181.8 mA h/g @ 100 mA/g) and good rate performance. It still delivers a specific capacity of 128.5 mA h/g when cycled under 500 mA/g. The increased performance of PMC was owing to the joint effect of phosphorus doping and mesoporous structure, which could shorten the transport path of K+ and improve the electrochemical reactivity for potassium batteries.

Activation of matrix-bound endogenous proteases by self-etch adhesives.

The study evaluated changes in total enzymatic activity and degradation of demineralized dentin following the application of universal or self-etch adhesives. The universal adhesives -Scotchbond Universal (SU) and All-Bond Universal (ABU) and self-etch adhesives -Adper Easy Bond (EB) and G-aenial Bond (GB) were used for 2 min pretreatment of the dentin beams. Phosphoric acid (PA) treatment as well as no treatment served as controls. Total enzymatic activity was analyzed before and after treatment, collagen degradation was assessed using mass loss, C-terminal telopeptide (CTX) and C-terminal-telopeptide of type I collagen (ICTP) release (24 h, 3-day, 3-week). Over three weeks of incubation, ICTP release of ABU treated beams was significantly higher than other groups (p<0.05), except for SU treated beams (p>0.05) and CTX release of GB treated beams was the highest among the groups with statistically significant difference (p<0.05). The results confirm that the universal adhesives tested have also potential to increase the enzymatic activity in dentin.

Inner filter effect as a sensitive sensing platform for detection of nitrofurantoin using luminescent drug-based carbon nanodots.

In the present paper, a sensitive and selective inner filter effect sensing platform was designed to detect nitrofurantoin (NIT) in pharmaceutical dosage form. Nitrogen and phosphorus co-doped carbon nanodots (CNDs) prepared via solvothermal treatment of folic acid and phosphoric acid. The prepared CNDs exhibit greenish fluorescence at 470nm when excited at 340nm with fluorescence quantum yield up to 40%. The CNDs exhibit high stability in various pH, temperature, and ionic strength which adds valuable merits to its pharmaceutical applications. The emission is quenched in the presence of absorber (here NIT) while the fluorophores were not quench by the presence of common pharmaceutical excipients. A fluorometric assay was fabricated to determine NIT in capsules by quenching of the CNDs. The linear response for the proposed method was from 5.0μM to 90μM with the detection limit being 1.4μM. To validate the method, the recovery of NIT in spiked sample was measured which was 96.6% -103.3%. The method was applied to the determination of NIT in pharmaceutical capsule samples, with comparable results of a reference method stated by the British Pharmacopeia (BP). Furthermore, the sub-acute toxicity studies of CNDs were investigated using normal male Balb/c mice forcefully drunk with 3 different dosages of CNDs. Animals did not produce treatment related signs of toxicity or mortality in any of the animals tested during the 28days observation period. Additionally, no significant (P>0.05) changes in the body weight, haematological and biochemical parameters compared with the control group were not revealed. Similarly, histopathological examination of the internal vital organs did not show any morphological alterations.