Evaluation of mandibular growth in a prepubertal Class I and Class II population: a longitudinal analysis.

OBJECTIVE: This study aims to identify the presence, timing, and magnitude of a prepubertal mandibular growth spurt in a Class I and Class II population. METHODS: From the Burlington and Iowa Growth study of the AAOF Craniofacial Growth Legacy Collection, 83 Class I subjects (37 females and 46 males) and 32 Class II subjects (18 males and 14 females) were identified, as having at least seven consecutive annual lateral cephalograms taken from 5 to 11 years of age. Only subjects with a normodivergent facial pattern were considered. A customized cephalometric analysis was performed, and total mandibular length, defined as the distance between Condylion (Co) and Gnathion (Gn), was calculated. RESULTS: Overall, a significant early peak of mandibular growth was present in all the subjects analysed both in Class I (4.69 mm for males and 4.18 mm for females; P < .05) and in Class II (5.85 mm for males and 4.05 mm for females; P < .05). No differences between males and females were found for the timing of this peak (7 years for Class I and Class II females and 7 years for Class I and 6.5 years for Class II males). In males, a significantly larger peak was observed in Class II than Class I subjects (P = .007). LIMITATIONS: The main limitations of this study were the impossibility of using a suitable growth indicator to identify the timing of the early mandibular growth peak and the limited Class II records retrievable. CONCLUSION: This investigation suggests that a prepubertal mandibular growth peak is consistently present in both Class I and Class II males and females of clinically significant magnitude. Despite that, chronological age confirms to be unsuitable to identify this peak.

Organofunctionalized Amazon smectite for dye removal from aqueous medium--kinetic and thermodynamic adsorption investigations.

The objective of this study is to examine the adsorption behavior of Sumifix Brilliant Orange 3R textile dye from aqueous solution on smectite sample, an abundant Amazon clay. The original smectite clay mineral has been collected from Amazon region, Brazil. The compound 2-aminomethylpyridine was anchored onto smectite surface by heterogeneous route. The ability of these materials to remove the Sumifix Brilliant Orange 3R textile dye from aqueous solution was followed by a series of adsorption isotherms, using a batchwise process. The maximum number of moles adsorbed was determined to be 1.26 and 2.07 mmol g(-1) for natural and modified clay samples, respectively. The energetic effects caused by dye cations adsorption were determined through calorimetric titrations. Thermodynamics indicated the existence of favorable conditions for such dye-nitrogen interactions.

Adsorption of methylene blue on raw and MTZ/imogolite hybrid surfaces: effect of concentration and calorimetric investigation.

The synthetic imogolite sample was used for organofunctionalization process with 2-mercaptothiazoline (MTZ). The compound 2-mercaptothiazoline was anchored onto imogolite surface by heterogeneous route. Due to the increment of basic centers attached to the pendant chains the dye adsorption capability of the final chelating material, was found to be higher than is precursor. The ability of these materials to remove methylene blue from aqueous solution was followed by a series of adsorption isotherms at room temperature and pH 4.0. The maximum number of moles adsorbed was determined to be 40.32×10(-2) and 65.13×10(-2) mmol g(-1) for IMO and IMO(MTZ), respectively. The energetic effects caused by dye cations adsorption were determined through calorimetric titrations. Thermodynamics indicated the existence of favorable conditions for such methylene blue-nitrogen and sulfur interactions.

Amazon kaolinite functionalized with diethylenetriamine moieties for U(VI) removal: thermodynamic of cation-basic interactions.

The compound N-[3-(trimethoxysilyl)propyl]diethylenetriamine (MPDET) was anchored onto Amazon kaolinite surface (KLT) by heterogeneous route. The modified and natural kaolinite clay samples were characterized by transmission electron microscopy (TEM), scanning electron microscopic (SEM), N(2) adsorption, powder X-ray diffraction, thermal analysis, ion exchange capacities, and nuclear magnetic nuclei of (29)Si and (13)C. The well-defined peaks obtained in the (13)C NMR spectrum in the 5.0-62.1 ppm region confirmed the attachment of organic functional groups as pendant chains bonded into the porous clay. The adsorption of uranyl on natural (KLT) and modified (KLT(MPDET)) kaolinite clays was investigated as a function of the solution pH, metal concentration, temperature, and ionic strength. The ability of these materials to remove U(VI) from aqueous solution was followed by a series of adsorption isotherms adjusted to a Sips equation at room temperature and pH 4.0. The maximum number of moles adsorbed was determined to be 8.37 x 10(-3) and 13.87 x 10(-3) mmol g(-1) for KLT and KLT(MPDET) at 298 K, respectively. The energetic effects (Delta(int)H, Delta(int)G, and Delta(int)S) caused by metal cations adsorption were determined through calorimetric titrations.

Adsorption of arsenic ions on Brazilian sepiolite: effect of contact time, pH, concentration, and calorimetric investigation.

The original sepiolite clay mineral has been collected from Amazon region, Brazil. The compound 2-aminomethylpyridine (AMP) was anchored onto Amazon sepiolite surface by heterogeneous route. The natural (SPT) and modified (SPT(AMP)) sepiolite samples were characterized by elemental analysis, SEM, N(2) adsorption, and nuclear magnetic nuclei of (29)Si and (13)C. The well-defined peaks obtained in the (13)C NMR spectrum in the 0-160 ppm region confirmed the attachment of organic functional groups as pendant chains bonded into the porous clay. The ability of these materials to remove As(V) from aqueous solution was followed by a series of adsorption isotherms at room temperature and pH 4.0. The maximum number of moles adsorbed was determined to be 7.26×10(-2) and 11.70×10(-2) mmol g(-1) for SPT and SPT(AMP), respectively. In order to evaluate the clay samples as adsorbents in dynamic system, a glass column was fulfilled with clay samples (1.0 g) and it was fed with 2.0×10(-2) mmol dm(-3) As(V) at pH 4.0. The energetic effects caused by metal cations adsorption were determined through calorimetric titrations. Thermodynamics indicated the existence of favorable conditions for such As(V)-nitrogen interactions.

Modification of hectorite by organofunctionalization for use in removing U(VI) from aqueous media: thermodynamic approach.

A Hectorite sample (H) has been chemically modified with N-propyldiethylenetrimethoxysilane and bis[3-(triethoxysilyl)propyl]tetrasulfide. The resulting materials (H(3TPT) and H(NPTM)) have been characterized through elemental analysis, X-ray diffractometry, carbon nuclear magnetic resonance in the solid state, textural analysis, and thermogravimetric analysis. The adsorption experiments were performed under batch process with pH, ionic strength, contact time, and uranyl concentration as variables. The attached basic centers adsorbed uranyl cation to give maxima adsorption capacity of 5.55+/-0.21, 14.86+/-0.05, and 18.99+/-0.05 x 10(-3) mmol g(-1) for H, H(3TPT), and H(NPTM), respectively. From calorimetric determinations the quantitative thermal effects for UO(2)(2+)/center interactions gave exothermic enthalpy (Delta(int)H=-6.90 to -7.88 kJ mol(-1)), negative Gibbs free energy (Delta(int)G=-22.34 to -24.56 kJ mol(-1)), and positive entropy (Delta(int)S=51.80-56.00 JK(-1)mol(-1)). These thermodynamic data confirmed the energetically favorable condition of such interaction solid/liquid for all systems.

Application of natural and modified hectorite clays as adsorbents to removal of Cr(VI) from aqueous solution--thermodynamic and equilibrium study.

A hectorite (H) clay sample has been modified with 2-mercaptobenzimidazole (MBI) using homogeneous and heterogeneous routes. Both modification methodologies resulted in similar products, named H(HOM) and H(HET), respectively. These materials were characterized by CO(2) gas adsorption, elemental analysis, nuclear magnetic nuclei of carbon-13 and silicon-29. The effect of two variables (contact time and metal concentration) has been studied using batch technique at room temperature and pH 2.0. After achieving the best conditions for Cr(VI) adsorption, isotherms of this adsorbate on using the chosen adsorbents were obtained, which were fitted to non-linear Sips isotherm model. The maximum number of moles adsorbed was determined to be 11.63, 12.85 and 14.01 mmol g(-1) for H, H(HOM) and H(HET), respectively, reflecting the maximum adsorption order of H(HET)>H(HOM)>H. The energetic effects (Delta(int)H degrees , Delta(int)G degrees and Delta(int)S degrees ) caused by chromium ion adsorption were determined through calorimetric titrations.

Layer silicates modified with 1,4-bis(3-aminopropyl)piperazine for the removal of Th(IV), U(VI) and Eu(III) from aqueous media.

Natural montmorillonite (M) and synthetic kanemite (K) have been functionalized with 1,4-bis(3-aminopropyl)piperazine reacted with methylacrylate to yield new inorganic-organic chelating materials. The original and modified materials were characterized by X-ray diffractometry, textural analysis, SEM and nuclear magnetic nuclei of carbon-13 and silicon-29. The chemically modified clay samples (M-APPMA and K-APPMA) showed modification of its physical-chemical properties including: specific area 45.0m(2)g(-1) (M) to 978.8 m(2)g(-1) (M-APPMA) and 23.5m(2)g(-1) (K) to 898.9 m(2)g(-1) (K-APPMA). The ability of these materials to remove thorium(IV), uranyl(VI) and europium(III) from aqueous solution was followed by a series of adsorption isotherms, which were fitted to non-linear Sips adsorption isotherm model. To achieve the best adsorption conditions the influence of pH and variation of metal concentration were investigated. The energetic effects (Delta(int)H degrees , Delta(int)G degrees and Delta(int)S degrees ) caused by metal ions adsorption were determined through calorimetric titrations.

Immobilization of 5-amino-1,3,4-thiadiazole-thiol onto kanemite for thorium(IV) removal: thermodynamics and equilibrium study.

The compound 5-amino-1,3,4-thiadiazole-thiol (ATT) was anchored onto an Amazon kanemite surface (K) by homogeneous and heterogeneous routes. Both kanemite modification methodologies resulted in similar products, named K(CTT) and K(ATT), respectively. The modified and natural kanemite samples were characterized by textural analysis, FT-Raman, and nuclear magnetic nuclei of (29)Si and (13)C. Elemental analysis proved that the matrix K(ATT) presented a higher ATT immobilization than K(CTT), with values 1.42 and 1.38 mmol g(-1), respectively. NMR and FT-Raman confirmed the immobilization of ATT on both surfaces. The ability of these materials to remove thorium(IV) from aqueous solution was followed by a series of adsorption isotherms adjusted to a Sips equation at room temperature and pH 4.0. The maximum number of moles adsorbed was determined to be 7.48x10(-3), 9.82x10(-3), and 12.94x10(-3) mmol g(-1) for K, K(CTT), and K(ATT), respectively. The energetic effects (Delta(int)H(o), Delta(int)G(o), and Delta(int)S(o)) caused by metal cation adsorption were determined through calorimetric titrations.

Designed pendant chain covalently bonded to analogue of heulandite for removal of divalent toxic metals from aqueous solution: thermodynamic and equilibrium study.

An analogue of heulandite was synthesized by using inorganic salts as a source for silicon and aluminum in the hydrothermal synthesis of the material. The resulting solid was modified by organofunctionalization with 1,4-bis(3-aminopropyl)piperazine and subsequent reaction with methylacrylate in a heterogeneous route. The original (HEU) and modified silicate (HEU(APPMA)) samples were characterized by textural analysis, SEM, and nuclear magnetic nuclei of (29)Si and (13)C. The chemically modified silicate sample showed modification of its physical-chemical properties including specific area 459.0-978.8 m(2) g(-1). The ability of this material to remove nickel(II), cobalt(II), and copper(II) from aqueous solutions was followed by a series of adsorption isotherms adjusted to a Sips equation. The quick adsorption process reached the equilibrium before 10, 15, and 20 min for Cu(II), Ni(II), and Co(II), respectively, with maximum adsorptions at pH 4.0. Based on the capacity of adsorption of HEU(APPMA) to interact with metal ions, the following results were obtained 12.9, 9.8, and 7.5 mmol g(-1) for Cu(II), Ni(II), and Co(II), respectively, reflecting a maximum adsorption order of Cu(II)>Ni(II)>Co(II). The energetic effects caused by metal cation adsorption were determined through calorimetric titrations.

Adsorption of thorium cation on modified clays MTTZ derivative.

Diquite (D) and bentonite (B) mineral samples from the Amazon region, Brazil, were modified by MTTZ derivative (5-mercapto-1-methyltetrazole) using heterogeneous route. These materials were characterized by textural and elemental analysis, transmission electron microscopy (TEM), power X-ray diffraction and (13)C NMR spectroscopy. The chemically modified clay (D(MTTZ) and B(MTTZ)) samples showed modification of its physical-chemical properties including: specific area 41.4 (B) to 398.5m(2)g(-1) (B(MTTZ)) and 25.0 (D) to 178.8m(2)g(-1) (D(MTTZ)). The adsorption experiments performed under batch process with Th(IV) concentration, pH and contact time as variables. The ability of these materials to remove thorium from aqueous solution was followed by a series of adsorption isotherms adjusted to a Sips equation at room temperature and pH 2.0, with variable concentration of Th(IV). The maximum number of moles adsorbed was determined to be 10.45 x 10(-2) and 12.76 x 10(-2)mmol g(-1) for D(MTTZ) and B(MTTZ), respectively. The energetic effects (Delta(int)H degrees , Delta(int)G degrees and Delta(int)S degrees ) caused by thorium cation adsorption were determined through calorimetric titrations.

Kinetic and thermodynamic uranyl (II) adsorption process into modified Na-Magadiite and Na-Kanemite.

The compound 2-mercaptopyrimidine (MPY) was attached onto synthetic Na-Magadiite (M) and Na-Kanemite (K) samples by homogeneous route. The final matrices named M(MPY) and K(MPY) have been characterized through X-ray powder diffraction and scanning electron microscopy (SEM). The resulted materials were submitted to process of adsorption with uranyl solution at pH 2.0 and 298+/-1K. The kinetic parameters were analyzed by the Lagergren and Elovich models of adsorption and demonstrated to be good fit for all experiments. From calorimetric determinations the quantitative thermal effects for uranyl(II)/basic center interactions gave exothermic enthalpy, negative Gibbs free energy, and positive entropy. These thermodynamic data confirmed the energetically favorable condition of such interactions at the solid/liquid interface for all systems.

Adsorption of arsenic(V) into modified lamellar Kenyaite.

The synthetic Kenyaite sample was used for organofunctionalization process with N-propyldiethylenetrimethoxysilane and bis[3-(triethoxysilyl)propyl]tetrasulfide. The resulted materials were submitted to process of adsorption with arsenic solution at pH 2.0 and 298+/-1K. The adsorption isotherms were adjusted using a modified Langmuir equation with regression non-linear; the net thermal effects obtained from calorimetric titration measurements were adjusted to a modified Langmuir equation. The adsorption process was exothermic (Delta(int)H=-4.08 to -5.94 kJ mol(-1)) accompanied by increase in entropy (Delta(int)S=41.29-62.09 J K(-1)mol(-1)) and Gibbs energy (Delta(int)G=-22.33 to -24.45 kJ mol(-1)). The energetic effect caused by metal cation adsorption was determined through calorimetric titration at the solid-liquid interface and gave a net thermal effect that enabled the calculation of the exothermic values and the equilibrium constant.

Kinetics and modified clay thermodynamic from the Brazilian amazon region for lead removal.

Modified Brazilian smectite-bearing clay samples displayed ability for lead adsorption. The structure modification of smectite were obtained through pillaring process and functionalization with [3-(2-aminoethylamino)propyl]trimethoxysilane. The chemical modification process increases the basal spacing of the natural smectite from 1.354 to 2.364 nm. The Langmuir model was fitted to experimental data in linear regression. Kinetic studies showed an equilibrium adsorption time of 700 min on the modified clay. The experimental data were correlated with two distinct kinetic models were used: (i) external mass transfer diffusion and (ii) intraparticular mass transfer diffusion. However, the intraparticle mass transfer diffusion model gave a better fit to these experimental data. The energetic effects caused by lead interactions were determined through calorimetric titration at the solid-liquid interface and gave a net thermal effect that enabled the calculation of the exothermic values and the equilibrium constant.

Adsorptive, thermodynamic and kinetic performances of Al/Ti and Al/Zr-pillared clays from the Brazilian Amazon region for zinc cation removal.

Smectite clay samples from the Amazon region, Brazil, were pillarized by intercalating the species obtained from the chemical reactions: (i) AlCl3.6H2O/NaOH, (ii) titanium ethoxide in hydrochloric acid and (iii) direct use of ZrOCl2.8H2O solution. The natural matrices and the pillaring solutions were maintained under vigorous stirring at 298 K for 3 h and then subjected to calcination at temperatures of 723 and 873 K. Natural and pillared matrices were characterized by XRD, FTIR, TG-DTG and nitrogen adsorption-desorption isotherms. The resulting materials were used for zinc adsorption from aqueous solution at room temperature. The Langmuir, Freundlich and Temkin adsorption isotherm models have been applied to fit the experimental data and the Freundlich model is limited for higher concentrations. The pillaring process increases the thermal stability, the basal spacing of the natural clay sample (A1) from 1.55 to 2.06 nm and the surface area from 44.30 to 223.73 m2 g(-1). Kinetic studies demonstrated an equilibrium time of 180 min for zinc adsorption on the pillared matrices. Pseudo-first-order, Lagergren pseudo-second-order and Elovich equations demonstrated a better agreement with second-order kinetics was obtained with K2=4.17-10.43 x 10(-3)g mg(-1)min(-1) for the A1 sample.