Effect of pre-heating resin composite and light-curing units on monomer conversion

The purpose of this study was to evaluate the effect of pre-heating resin composite photo-cured with light-curing units (LCU) by FT-IR. Twenty specimens were made in a metallic mold (4 mm diameter × 2 mm thick) from composite resin—Tetric Ceram® (Ivoclar/Vivadent) at room temperature (25°C) and pre-heated to 37, 54, and 60°C. The specimens were cured with halogen curing light (QTH) and light emitted by diodes (LED) during 40 s. Then, the specimens were pulverized, pressed with KBr and analyzed with FT-IR. The data were submitted to statistical analysis of variance and Kruskal-Wallis test. Study data showed no statistically significant difference to the degree of conversion for the different light curing units (QTH and LED) (p > 0.05). With the increase of temperature there was significant increase in the degree of conversion (p < 0.05). In this study were not found evidence that the light curing unit and temperature influenced the degree of conversion.     

Ether and ester glucuronic acid conjugates of lacidipine metabolites: Mass spectrometric differentiation using thermospray and particle beam techniques

Glucuronic acid conjugates of Lacidipine metabolites were analysed by high-performance liquid chromatog-raphy/mass spectrometry with different ionization techniques, viz. thermospray and chemical ionization with a particle beam interface. Analyses were performed on bile samples collected from dogs after oral administration of ¹⁴C-labelled Lacidipine. Phase II metabolites, originating from the conjugation with glucuronic acid of phase I metabolites containing free hydroxy or carboxylic functions, were isolated. Two types of glucuronides, with an ether or an ester bond, were characterized. They showed different mass Spectrometric behaviour owing to a specific interaction with the acetate in the mobile phase.     

Electronic and structural properties of black phosphorene doped with Si,B and N

The electronic and structural properties of substitutional and doped phosphorene with B, N and Si were studied using first principles calculations based on density functional theory. Moreover, electronic and structural properties of functionalized phosphorene slowly increasing the concentration of doping was investigated. Phosphorene strongly binds with doped functionalization; B doped phosphorene is the most stable configuration studied. Si doped phosphorene maintains the semiconductor characteristic. B and N doped phosphorene present n-type and p-type semiconductors, respectively. Doped phosphorene with odd number of Si is a semiconductor material, doped phosphorene with an odd number of B has n-type semiconductor characteristic, and doped phosphorene with odd number of N atoms has a p-type semiconductor behaviour. Doped phosphorene with even number of Si has a metallic characteristic, while B and N doped phosphorene with even number present a semiconductor behaviour. This work reveals that phosphorene electronic properties could be changed by introducing the dopants on the system, and the properties are affected by the increasing number of dopants on phosphorene sheet.     

Development and Validation of an LC-UV Method for Quantitation of 4-Bromo-2,5-Dimethoxyamphetamine (DOB), 4-Bromo-2,5-Dimethoxyphenetylamine (2C-B), Methylphenidate,Fenproporex and Amfepramone

A sensitive and reliable isocratic LC-UV method was developed and validated for quantification of 4-bromo-2,5-dimethoxyamphetamine (DOB), 4-bromo-2,5-dimethoxyphenetylamine (2C-B), amfepramone (diethylpropione, DEP), fenproporex (FEN) and methylphenidate (MPH). Although these substances are not usually associated, the fact that the same method could be used to analyze five different amphetamines would be very helpful in forensic analysis. The validation parameters accessed were linearity, specificity, precision, accuracy, limit of detection, limit of quantification and robustness. During the evaluation of selectivity, benzaldehyde (BZ) and N-methyl-diethanolamine (MDEA), two out of nine related substances tested, did not show good resolution from DOB and FEN, respectively. However, commercial preparations containing DEP, FEN and MPH were analyzed and no interference from their excipients was noticed. Through this method, these five amphetamine derivatives studied were simultaneously identified and quantified. The developed method is easy to implement, fast and suitable for use in routine laboratory analysis. The only limitation would be the quantitation of DOB and FEN in the presence of large amounts of BZ and MDEA, respectively.     

Influence of Er:YAG laser on surface treatment of aged composite resin to repair restoration

The purpose of this study was to investigate the effect of Er:YAG laser on surface treatment to the bond strength of repaired composite resin after aged. Sixty specimens (n = 10) were made with composite resin (Z250, 3M) and thermocycled with 500 cycles, oscillating between 5 to 55°C. The specimens were randomly separated in six groups which suffered the following superficial treatments: no treatment (GI, control), wearing with diamond bur (GII), sandblasted with aluminum oxide with 27.5 μm particles (GIII) for 10 s, 200 mJ Er:YAG laser (GIV), 300 mJ Er:YAG laser (GV), and 400 mJ Er:YAG laser (GVI), with the last 3 groups under a 10 Hz frequency for 10 s. Restoration repair was done using the same composite. The shear test was done into the Universal testing machine MTS-810. Analyzing the results through ANOVA and Tukey test, no significant differences were found (p-value is 0.5120). Average values analysis showed that superficial treatment with aluminum oxide presented the highest resistance to shear repair interface (8.91MPa) while 400 mJ Er:YAG laser presented the lowest (6.76 MPa). Fracture types analysis revealed that 90% suffered cohesive fractures to GIII. The Er:YAG laser used as superficial treatment of the aged composite resin before the repair showed similar results when used diamond bur and sandblasting with aluminum oxide particles.     

Fractionation of Raw and Parboiled Rice Husks with Deep Eutectic Solvents and Characterization of the Extracted Lignins towards a Circular Economy Perspective

In the present work, rice husks (RHs), which, worldwide, represent one of the most abundant agricultural wastes in terms of their quantity, have been treated and fractionated in order to allow for their complete valorization. RHs coming from the raw and parboiled rice production have been submitted at first to a hydrothermal pretreatment followed by a deep eutectic solvent fractionation, allowing for the separation of the different components by means of an environmentally friendly process. The lignins obtained from raw and parboiled RHs have been thoroughly characterized and showed similar physico-chemical characteristics, indicating that the parboiling process does not introduce obvious lignin alterations. In addition, a preliminary evaluation of the potentiality of such lignin fractions as precursors of cement water reducers has provided encouraging results. A fermentation-based optional preprocess has also been investigated. However, both raw and parboiled RHs demonstrated a poor performance as a microbiological growth substrate, even in submerged fermentation using cellulose-degrading fungi. The described methodology appears to be a promising strategy for the valorization of these important waste biomasses coming from the rice industry towards a circular economy perspective.     

Synthesis of new halo-containing acetylenes and their application to the synthesis of azoles

The convenient synthesis of ten halo- and an isoxazole-containing acetylenes from the reaction of acetylenes with n-butyl lithium and subsequent reaction with an electrophile agent (ethyl trichloroacetate, ethyl dichloroacetate, trifluoroacetic anhydride, 3-methylisoxazol-5-carbonyl chloride, carbon tetrachloride and 1,1,1-trifluoro-4-ethoxy-3-buten-2-one) in moderated to good yields is reported. The application of 1,1,1-trichloro-4-phenyl-3-butyn-2-one on the synthesis of two azoles is also showed.     

Bioanalytical method to detect midazolam in plasma

Midazolam (MDZ) is the first choice in palliative sedation, and commonly used in sleep induction in anesthesia, with rapid onset of action. However, monitoring of the level of sedation in patients is not accurate. We developed and validated a bioanalytical method to detect MDZ in plasma using high‐performance liquid chromatography (HPLC) coupled to a photodiode array detector (PDA) for future monitoring of sedation. MDZ was extracted by solid‐phase extraction (SPE). Analyses were performed on a C₁₈ column, using 0.05% triethylamine and acetonitrile as mobile phase, analyzing at 220 nm. Recovery was evaluated by comparing extracted and nonextracted solutions. Precision, accuracy, linearity, limits of detection (LD) and quantification (LQ), specificity and selectivity were determined. The mean recovery obtained by SPE was 101.03%. The method was linear in the range 1.0–50.0 μg/mL. The LD and LQ were, respectively, 0.43 and 1.43 μg/mL. The specificity of the MDZ peak was adequate. The method was able to detect MDZ among other drugs. Plasma anticoagulants showed no interference with the drug detection. The bioanalytical method using HPLC–PDA and SPE was successfully validated and showed linearity, precision, accuracy, specificity and high sensitivity for detection of MDZ in human plasma.     

Gas Chromatographic Method for Analysis of p-Synephrine in Citrus aurantium L. Products

A method has been developed and validated for the identification and quantification of p-synephrine in Citrus aurantium L. products. The approach comprises GC-FID analysis followed by GC-MS confirmation after clean-up by solid phase extraction with a strong cation-exchange phase and derivatization with cyclohexanone. Oxazolidine derivative of p-synephrine was subjected to analysis by nuclear magnetic resonance (¹H and ¹³C NMR), GC-FID and GC-MS. The GC method was validated and was found to be linear in the range of 125–500 mg%. Intra-day and inter-day precisions were 3.60 and 3.59%, respectively. Mean recovery from extract of C. aurantium was 78.1 ± 3.64%. The selectivity of the method was further improved by confirmation of oxazolidine derivative of p-synephrine by GC-MS.     

Gas Chromatographic Method for Analysis of p-Synephrine in Citrus aurantium L. Products

A method has been developed and validated for the identification and quantification of p-synephrine in Citrus aurantium L. products. The approach comprises GC-FID analysis followed by GC-MS confirmation after clean-up by solid phase extraction with a strong cation-exchange phase and derivatization with cyclohexanone. Oxazolidine derivative of p-synephrine was subjected to analysis by nuclear magnetic resonance (¹H and ¹³C NMR), GC-FID and GC-MS. The GC method was validated and was found to be linear in the range of 125–500 mg%. Intra-day and inter-day precisions were 3.60 and 3.59%, respectively. Mean recovery from extract of C. aurantium was 78.1 ± 3.64%. The selectivity of the method was further improved by confirmation of oxazolidine derivative of p-synephrine by GC-MS.