Electrochemical, surface analysis, computational and anticorrosive studies of novel di-imine Schiff base on X65 steel surface.

The inhibitory effect of di-imine-SB namely ((N1Z, N4E)-N1, N4-bis (4 (dimethylamino) benzylidene) butane 1,4-diamine) on X65-steel in 1 M HCl has been investigated experimentally and theoretically. The electrochemical impedance spectroscopy (EIS), potentiodynamic polarization (PDP), and weight loss outcomes display the anticorrosion properties of "di-imine- SB". The inhibitory efficiency exceeds 90% at the optimal concentration of 1 × 10-3 M "di-imine- SB". The metal surface was examined further using scanning electron microscope (SEM) and energy dispersive X-ray (EDX). The effectiveness of the di-imine-SB is returned into its adsorption on X65-steel surface and found in agreement with Langmuir adsorption isotherm. According to the standard Gibbs free energy of adsorption [Formula: see text], di-imine-SB adsorption tends to be chemical rather than physical, it increases the activation energy ([Formula: see text]) of metal dissolution reaction and makes it hard to occur. The PDP data suggested anodic and cathodic type of the di-imine-SB inhibitor. Meanwhile, increasing the resistance of X65-steel to 301 Ω cm2 after adding 1 mM of di-imine-SB confirms its protective effect. Whereas, the positive value of the fraction of electron transference (ΔN, 0.746), confirms the affinity of di-imine-SB to share electrons to the partially filed 3d-orbital of Fe forming strong protective film over X65-steel surface. Aided by Monte Carlo (MC) simulation, the calculated adsorption energy (Eads) suggests excessive adsorption affinity of di-imine-SB on metal surface over the corrosive chlorides and hydronium ions. A good correlation between the theoretical hypothesis and the experimental inhibition efficiency has been achieved. The comparative study showed the superior of the di-imine-SB as potential corrosion inhibitor compared with those reported before. Finally, global reactivity descriptors; electron affinity (A), ionization potential (I), electronegativity (χ), dipole moment (µ), global hardness ([Formula: see text]), electrophilicity index and, Fukui indices were also calculated and found well correlated to the reactivity of di-imine-SB.

Effect of Thyroxine on Transforming Growth Factor ß1, Collagen I, and V Expression in Keratoconus Corneal Fibroblasts and Keratocytes, in Vitro.

BACKGROUND: Keratoconus (KC) is a corneal disorder, associated with oxidative stress, hypoxia and as several times discussed, potentially with thyroid gland dysfunction. We aimed to investigate the effect of thyroxine on transforming growth factor ß1 (TGF-ß1), collagen I and V (Col I and V) expression in human corneal fibroblasts (HCFs) and human keratocytes of KC corneas, in vitro. METHODS: Primary human KC-keratocytes and normal keratocytes were isolated and cultured as corneal fibroblasts or keratocytes. The effect of 0.1 µg/ml and 1.0 µg/ml thyroxine on TGF-ß1, Col I and Col V expression was investigated by qPCR, Western blot, and ELISA. Proliferation assay was performed using BrdU ELISA to observe the 24h effect of 1.0 µg/ml thyroxine on keratocytes, in vitro. RESULTS: TGFB1 mRNA expression of normal keratocytes increased following 1.0 µg/ml thyroxine stimulation for 24 h (p = .036), without changes in protein expression. Col I protein expression of KC-HCFs increased following 1.0 µg/ml thyroxine stimulation for 24 h (p = .0003). Proliferation of normal and KC keratocytes increased following a 7-day growth period and 24 hours thyroxine administration (p = .018; p = .024). CONCLUSIONS: Thyroxine may affect the Col I protein expression in KC-HCFs, but not in KC keratocytes, in vitro. Thyroxine administration has no effect on TGF-ß1, collagen I and V expression of keratoconus keratocytes. Therefore, an increased thyroxine concentration alone seems not to be causally related to the development of keratoconus.

Synthesis, Conformational Analysis, Infrared, Raman and UV-Visible Spectra of Novel Schiff Bases compiled with DFT Calculations.

OBJECTIVE: Two novel Schiff bases named, 2-((2-Hydroxybenzylidene)amino)-4,5,6,7- tetrahydrobenzo[b] thiophene-3-carbonitrile (BESB1) and 2-((Furan-2-ylmethylene)amino)-4,5,6, 7-tetrahydro-benzo[b]thiophene-3-carbonitrile (BESB2) were synthesized. METHODS: The structures were characterized based on CHN elemental analysis, mid-infrared (400- 4000 cm-1), Raman (100-4000 cm-1), 1H NMR, mass and UV-Vis spectroscopic measurements. In addition, quantum mechanical calculations using DFT-B3LYP method at 6-31G(d) basis set were carried out for both Schiff bases. Initially, we have carried out complete geometry optimizations followed by frequency calculations for the proposed conformational isomers; BESB1 (A-E) and BESB2 (F-J) based on the orientations of both CN and OH groups against the azomethine lonepair (NLP) in addition to the 3D assumption. RESULTS: The computational outcomes favor conformer A for BESB1 in which the C≡N and OH moieties are cis towards the NLP while conformer G is preferred for BESB2 (the C≡N/furan-O are cis/trans towards the NLP) which was found consistent with the results of relaxed potential energy surface scan. Aided by normal coordinate analysis of the Cartesian coordinate displacements, we have suggested reliable vibrational assignments for all observed IR and Raman bands. Moreover, the electronic absorption spectra for the favored conformers were predicted in DMSO solution using TD-B3LYP/6-31G(d) calculations. Similarly, the 1H NMR chemical shifts were also estimated using GIAO approach implementing PCM including solvent effects (DMSO-d6). CONCLUSION: Proper interpretations of the observed electronic transition, chemical shifts, IR and Raman bands were presented in this study.

Trans-scleral posterior capsulorhexis in combined lens extraction and silicone oil removal.

AIM: The aim of this study was to study the safety and efficacy of posterior capsulorhexis in vitrectomized eyes undergoing combined phacoemulsification or irrigation/aspiration and silicone oil removal. METHODS: This prospective non-randomized interventional study involved 115 silicone-filled eyes of 115 previously vitrectomized patients. All patients underwent combined phacoemulsification or underwent irrigation/aspiration and silicone oil removal, followed by foldable intraocular lens implantation combined with primary posterior trans-scleral capsulorhexis. A 23-gauge trans-scleral vitrectomy probe was used to form the posterior capsulorhexis (vitrectorhexis). Patients were followed for 6 months. RESULTS: Intraocular lenses maintained good centration in the capsular bag during and after trans-scleral posterior capsulorhexis. No complications were observed in the postoperative period regarding lens centration or size of the posterior capsulorhexis. No included eyes needed YAG laser posterior capsulotomy and no recurrent retinal detachment was reported during follow-up. CONCLUSION: Performing primary trans-scleral capsulorhexis in patients undergoing combined phacoemulsification, or irrigation/aspiration and silicone oil removal, enabled achievement of an early postoperative clear visual axis and prevented the onset of dense postoperative posterior capsular opacification in previously silicone-filled eyes. This technique is reproducible and may facilitate additional intra-operative procedures and uncomplicated postoperative follow-up of retinal detachment patients without requiring YAG laser capsulotomy.

Structure/property relationship of polyvinyl alcohol/dimethoxydimethylsilane composite membrane: Experimental and theoretical studies.

A novel mixed matrix composite has been prepared using solution-casting method at different volume concentrations of polyvinyl alcohol; PVA (50, 67, 75 and 80%) and fixed amount of dimethoxydimethylsilane in air atmosphere. The hydrolyzed dimethyldisilanol acts as in-situ cross linker through a wet-out condensation between the hydroxyl moieties of SiOH and PVAOH. Such process improves the mechanical properties of composite membranes as compared to pristine PVA which has been determined as function of varied membrane components to evaluate the structure/property relationships. Furthermore, DFT (B3LYP)/6-31G(d) geometry and frequency computations were carried out for the suggested dimeric PVA structures via 1,3-diol linkage followed by condensation and hydrogen bonding interaction. Vibrational interpretations of composite membranes were proposed based on the computed wavenumbers, Cartesian coordinates displacements for the suggested hydrolyzed products involving the dominant PVA/SiOH/SiOC/SiOSi functional groups compared with those given in literatures. FTIR and EDX provide clear evidences for incorporating silicon to 3D network. Meanwhile, the infrared de-convoluted spectral interpretations ensure 17-30% cross-linked SiOC within the network of composite membranes.

Effect of single subconjunctival injection of bevacizumab on primary pterygium: clinical, histopathological and immunohistochemical study.

AIM: To evaluate the effect (clinically, histopathologically and immunohistochemically) and safety of a single intra-pterygium injection of bevacizumab. METHODS: Prospective interventional study comprised 40 eyes of 40 patients with primary fleshy pterygia who attended the Outpatient Clinic of Department of Ophthalmology, Assiut University Hospitals, Egypt from May 2015 to May 2016. Patients were randomly classified into 2 groups: the first group received a single intralesional injection of bevacizumab (Avastin; Genentech, San Francisco, CA, USA); the second group comprised patients who did not receive subconjunctival bevacizumab. Excision of pterygium and conjunctival auto graft was done in both groups. The excised pterygium tissues were subjected to histopathological and immunohistochemical evaluation. RESULTS: The study comprised 40 eyes of 40 patients (33 men, 7 women) of age range from 31-58y. The study group included 22 eyes. The control group included 18 eyes. A decrease in the vascularity of the pterygium was noted in all injected cases. The mean vessel count was higher in non-injected pterygia than that in injected pterygia and the difference was statistically significant (P=0.001). Also, the mean vessel count in both groups was significantly higher than normal conjunctive (P=0.005 and 0.001). A statistically significant difference in vascular endothelial growth factor (VEGF) expression between injected and non-injected cases was detected in the epithelial, stromal and endothelial cells (P=0.0001, 0.016, 0.014). No serious intraoperative complications occurred in both groups. CONCLUSION: The use of single intra lesional injection of Avastin in pterygium decreased vascularity and decreased VEGF expression in injected pterygium after one month. Our study proved the effect of single intra lesional injection of Avastin on pterygium. Further studies may enable limiting the need for surgery and improve quality of life for patients with pterygia.

Refractive Lens Exchange Combined with Primary Posterior Vitrectorhexis in Highly Myopic Patients.

Purpose. To evaluate efficacy and safety of primary vitrectorhexis for posterior capsulotomy in highly myopic patients undergoing refractive lens exchange. Methods. The study is a prospective nonrandomized interventional study. The study comprised 60 eyes of 60 myopic patients. All patients underwent refractive lens exchange (RLE) and foldable IOL implantation combined with primary posterior capsulotomy. We used a 23-gauge vitrectomy probe for the creation of the posterior capsule opening. We followed the patients for one year. Results. During surgery, the IOLs remained well centered in the capsular bag after creation of the capsulotomy. Postoperatively, we did not report any complications related to lens centration or changes in the posterior capsulotomy size. No eye required YAG laser posterior capsulotomy and no cases of retinal detachment (RD) occurred during the follow-up period. Conclusion. Primary posterior vitrectorhexis during RLE is an efficient method in preventing the occurrence of posterior capsular opacification (PCO) and the need for YAG laser posterior capsulotomy with its possible complications.

Raman and DRIFT spectra, vibrational assignments and quantum mechanical calculations of centrosymmetric meso-2,3-Dimercaptosuccinic acid.

The Raman spectrum (3700-100cm-1) of meso-2,3-Dimercaptosuccinic acid (meso-DMSA; C4H6O4S2) was recorded in the solid phase using 514.5 and 785nm excitation lines. Whereas, the DRIFT spectrum (4000-400cm-1) of the sample powdered in KBr was obtained. Moreover, DFT-B3LYP/6-31G(d) geometry optimization and frequency calculations were carried out for centrosymmetric trans (Ci), gauche (C1; G+/G-) and eclipsed (Cs; Ef and C1; E+/E-) rotational isomers in favor of a trans conformation, the least energy with real frequencies. However, other conformers were found at either local minima or local maxima as a result of the rotation of carboxyl, hydroxyl and thiol groups according to a potential energy surface scan. Moreover, an imaginary wavenumber was predicted; therefore, they are considered transition states. On the other hand, the mass spectrum of the sample dissolved in an acetonitrile/methanol mixture reveal 4-6% dimer through intermolecular hydrogen bonding interactions via the dicarboxylic groups. Therefore, we have modeled the complex structure obeying Ci restricted symmetry for an isolated dimer unit using DFT-B3LYP/6-31G(d) and for two molecules per unit cell in the solid phase implementing DFT-PBE functional. Thus, the meso-DMSA forms long strands in which individual molecules are bonded together at each termini through hydrogen bonding. Aided by normal coordinate analysis, complete vibrational assignments were provided herein which support Ci configuration of meso-DMSA in the solid state which found consistent with the observed broadening, composite, split bands, and the mutual exclusion rule.

Effect of intracameral triamcinolone acetonide on postoperative intraocular inflammation in pediatric traumatic cataract.

PURPOSE: To study the effect of a single intracameral injection of triamcinolone acetonide at the end of pediatric traumatic cataract surgery on postoperative inflammation. METHODS: This prospective interventional study comprised 40 eyes of children with unilateral traumatic cataract. Patients were classified into 2 groups: the study group, in which intraoperative intracameral triamcinolone acetonide (2 mg) was used at the end of surgery; and a control group, which did not receive intracameral triamcinolone acetonide. RESULTS: The study group included 20 eyes of patients with an average age of 6 ± 2.8 years. The control group included 20 eyes of patients with an average age of 6 ± 2.1 years. No serious intraoperative complications occurred. In the immediate postoperative period, 3 eyes of the control group (15.0%) developed a fibrinous anterior chamber reaction. None of the study group eyes developed a similar reaction. There were no cases of endophthalmitis. In addition, 3 eyes (15%) in the control group had obscuration of the visual axis at the last follow-up. This complication was not encountered in the study group. Posterior synechiae and cellular deposits were observed in 4 eyes (20%) in the study group and 8 eyes (40%) in the control group at 1 month and at the last follow-up. CONCLUSIONS: The use of intracameral triamcinolone decreased anterior segment inflammation postoperatively in children who had surgery for traumatic cataract.

Raman, infrared and NMR spectral analysis, normal coordinate analysis and theoretical calculations of 5-(methylthio)-1,3,4-thiadiazole-2(3H)-thione and its thiol tautomer.

Raman (3400-100 cm(-1)) and infrared (4000-200 cm(-1)) spectra of 5-(methylthio)-1,3,4-thiadiazole-2(3H)-thione (C3H4N2S3; MTT) were measured in the solid state, and the (1)H/(13)C NMR spectra were obtained in DMSO-d6. Initially, twelve structures were proposed as a result of thiol-thione tautomerism and the internal rotation about the C-S bonds. The energies and vibrational frequencies of the optimized structures were calculated using the 6-31G(d) basis set with the methods of MP2 and DFT/B3LYP with Gaussian 98 quantum calculations. Additionally, (1)H/(13)C NMR chemical shifts were predicted for the thiol (structure 5) and thione (structure 9) tautomers by means of B3LYP/6-311+G(d,p) calculations utilizing the GIAO approximation and the PCM solvation model. After complete relaxation of twelve candidate isomers, the thione tautomer (structure 9) was favored owing to its low energy and its predicted real spectral frequencies. These results agree with the recorded infrared and Raman results, in addition to the observed/calculated (1)H and (13)C NMR spectra. Aided by normal coordinate analysis and potential energy distributions (PEDs), complete vibrational assignments have been proposed for all observed fundamentals for the thione tautomer. With the aid of MP2/6-31G(d) potential surface scans, CH3, CH3S, and SH barriers to internal rotations were estimated with the optimized structural parameters from the MP2 method with the 6-31G(d) basis set. The results are discussed herein and compared with similar model compounds whenever appropriate.

Retrospective assessment of survival rate for short endosseous dental implants.

PURPOSE: The aim of this study was to determine the survival rate of short implants that were placed in a residency program. In addition, the potential influence of diabetes, smoking, sinus grafting, guided bone regeneration, and implant type on survival was analyzed. METHODS: Through a retrospective chart review, patient information and parameters for short implants being equal or less than 10 mm and regular implants being more than 10 mm were collected. The cumulative survival rate and implant and patient information from 213 consecutively placed implants from May 2002 through October 2011 were analyzed. RESULTS: The average survival time for short implants was 47.3 months, with a range of 6 to 141 months. The implant survival rate was 95.77% for short implants, which was not statistically significant from the regular implants. Smoking had a statistically significant negative effect on the survival rate of short implants. No statistical differences were found with implant survival rates for other factors. CONCLUSION: It can be concluded that short implants can be predictably placed in the mouth with a high survival rate and that smoking has a negative influence on the survival rate of the short implants.

Synthesis, antimicrobial activity, structural and spectral characterization and DFT calculations of Co(II), Ni(II), Cu(II) and Pd(II) complexes of 4-amino-5-pyrimidinecarbonitrile.

Co(II), Ni(II), Cu(II) and Pd(II) complexes of 4-amino-5-pyrimidinecarbonitrile (APC) have been synthesized and characterized using elemental analysis, magnetic susceptibility, mass spectrometry, infrared (4000-200 cm(-1)), UV-Visible (200-1100 nm), (1)H NMR and ESR spectroscopy as well as TGA analysis. The molar conductance measurements in DMSO imply non-electrolytic complexes, formulated as [M(APC)2Cl2] where M=Co(II), Ni(II), Cu(II) and Pd(II). The infrared spectra of Co(II), Ni(II) and Cu(II) complexes indicate a bidentate type of bonding for APC through the exocyclic amino and adjacent pyrimidine nitrogen as donors whereas APC coordinated to Pd(II) ion as a monodentated ligand via a pyrimidine nitrogen donor. The magnetic measurements and the electronic absorption spectra support distorted octahedral geometries for Co(II), Ni(II) and Cu(II) complexes however a square planar complex was favored for the Pd(II) complex (C2h skeleton symmetry). In addition, we carried out B3LYP and ω-B97XD geometry optimization at 6-31G(d) basis set except for Pd(II) where we implemented LanL2DZ/6-31G(d) combined basis set. The computational results favor all trans geometrical isomers where amino N, pyrimidine N and Cl are trans to each other (structure 1). Finally, APC and its divalent metal ion complexes were screened for their antibacterial activity, and the synthesized complexes were found to be more potent antimicrobial agents than APC against one or more microbial species.

Infrared and NMR spectra, tautomerism, vibrational assignment, normal coordinate analysis, and quantum mechanical calculations of 4-amino-5-pyrimidinecarbonitrile.

The infrared (4000-200 cm(-1)) spectrum for 4-amino-5-pyrimidinecarbonitrile (APC, C5H4N4) was acquired in the solid phase. In addition, the (1)H and (13)C NMR spectra of APC were obtained in DMSO-d6 along with its mass spectrum. Initially, six isomers were hypothesized and then investigated by means of DFT/B3LYP and MP2(full) quantum mechanical calculations using a 6-31G(d) basis set. Moreover, the (1)H and (13)C NMR chemical shifts were predicted using a GIAO approximation at the 6-311+G(d,p) basis set and the B3LYP method with (and without) solvent effects using PCM method. The correlation coefficients showed good agreement between the experimental/theoretical chemical shift values of amino tautomers (1 and 2) rather than the eliminated imino tautomers (3-6), in agreement with the current quantum mechanical calculations. Structures 3-6 are less stable than the amino tautomers (1 and 2) by about 5206-8673 cm(-1) (62.3-103.7 kJ/mol). The MP2(full)/6-31G(d) computational results favor the amino structure 1 with a pyramidal NH2 moiety and calculated real vibrational frequencies, however; structure 2 is considered a transition state owing to the calculated imaginary frequency. It is worth mentioning that, the calculated structural parameters suggest a strong conjugation between the amino nitrogen and pyrimidine ring. Aided by frequency calculations, normal coordinate analysis, force constants and potential energy distributions (PEDs), a complete vibrational assignment for the observed bands is proposed herein. Finally, NH2 internal rotation barriers for the stable non-planar isomer (1) were carried out using MP2(full)/6-31G(d) optimized structural parameters. Our results are discussed herein and compared to structural parameters for similar molecules whenever appropriate.

Analysis of UV and vibrational spectra (FT-IR and FT-Raman) of hexachlorocyclotriphosphazene based on normal coordinate analysis, MP2 and DFT calculations.

The Raman (1400-100 cm(-1)) and infrared (4000-400 cm(-1)) of solid hexachlorocyclotriphosphazene, P(3)N(3)Cl(6) (HCCTP) were recorded. The conformational energies were calculated using MP2 and DFT (B3LYP and B3PW91) methods utilizing a variety of basis sets up to 6-311+G(d). On the basis of D(3h) symmetry, the simulated vibrational spectra of P(3)N(3)Cl(6) from MP2 and DFT methods were in excellent agreement with those obtained experimentally. Additionally, Frontier Molecular Orbitals and electronic transitions were predicted using steady state and time dependent DFT(B3LYP)/PCM calculations respectively, each employing the 6-311+G(d,p) optimized structural parameters. The predicted wavelengths were in excellent agreement with experimental values when CH(2)Cl(2) was used as solvent. The (14)N and (31)P chemical shifts were predicted with B3LYP/6-311+G(2d,p) calculations using the GIAO technique with solvent effect modeled using the PCM method. The computed structural parameters of the planar P(3)N(3)Cl(6) (D(3h)) agree well with experimental values from both X-ray and electron diffraction data with slight distortions observed due to lattice defects in the solid phase. The experimental/computational results favor a slightly distorted D(3h) symmetry for the title compound in the gas and solid phases and in solution (τPNPN and τNPNP ranged from 0.018° to 0.90°). Aided by normal coordinate analysis, and the simulated vibrational spectra utilizing MP2, B3LYP and B3PW91 methods at 6-31G(d) basis set, revised and complete vibrational assignments for all fundamentals are provided herein.

Spectral domain anterior segment optical coherence tomography assessment of pterygium and pinguecula.

PURPOSE: To study the morphological patterns of pterygia and pingueculae using high-resolution anterior segment spectral domain optical coherence tomography (SD-OCT). METHODS: Prospective cross-sectional study of 25 eyes presented with pterygia and pingueculae was conducted, and the eyes were examined by anterior segment SD-OCT. RESULTS: We examined 25 eyes, including 13 eyes with primary pterygia, six eyes with recurrent pterygia, one case with a pseudopterygium and five eyes with pingueculae. Primary pterygia revealed elevation of the corneal epithelium by a wedge-shaped mass of tissue separating the corneal epithelium from the underlying Bowman's membrane, which became wavy and interrupted. We found satellite masses of pterygium tissue advanced under the epithelium beyond the clinically seen pterygium margins. In recurrent pterygia, we detected that the central tip of the pterygium was more advanced and creeping beneath the basal corneal epithelium than the primary pterygium. In pseudopterygium, the SD-OCT images showed that the overgrowing membrane was not really attached to the underlying cornea. In cases of pingueculae, SD-OCT revealed a wedge-shaped mass that was nearly similar in pattern to that of the pterygia but stopped at the limbal region. Immediately after removal of pterygia, we noticed many remnants of the pterygia masses over the corneal stroma in spite of the clinically clear appearance of cornea. CONCLUSIONS: SD-OCT provided us with high-resolution images of the pterygium and the pinguecula and showed clearly the anatomical relationship between the corneal tissues and these lesions. The use of this new modality of imaging may help to decrease the current recurrence rates after pterygium excision through using the anterior segment SD-OCT in the evaluation of these lesions.

Infrared, 1H and 13C NMR spectra, structural charcterization and DFT calculations of novel adenine-cyclodiphosp(V)azane derivatives.

Adenine tetrachlorocyclodiphospha(V)zane derivatives (III(a-c)) were prepared by the reaction of hexachlorocyclodiphospha(V)zane derivatives (I(a-c)) and adenine (II) as precursors. The synthesized compound's and their structures (III(a-c)) were firmly characterized (based on the presence of an inversion center) using FT-IR (4000-200 cm(-1)), UV-vis. (190-800 nm), (1)H, (13)C NMR and Mass spectral measurements in addition to C, H, N, P elemental analysis. The compounds (III(a-c)) were found to be a 1:2 molar ratio of (I(a-c)) and adenine (II) adducts, respectively. Confident and complete vibrational assignments are proposed for nearly all fundamental vibrations, along with detailed interpretation for all observed signals in both (1)H and (13)C NMR spectra of the investigated phospha(V)zanes (III(a-c)). In addition, unconstrained geometry optimization of III(a-c) were carried out by means of DFT-B3LYP/3-21G(d) calculations to provide new insight into the structural parameters and molecular geometries of compounds III(a-c). The results are reported herein and compared with similar molecules whenever appropriate.

Vibrational assignments, normal coordinate analysis, B3LYP calculations and conformational analysis of methyl-5-amino-4-cyano-3-(methylthio)-1H-pyrazole-1-carbodithioate.

The Raman and infrared spectra of solid methyl-5-amino-4-cyano-3-(methylthio)-1H-pyrazole-1-carbodithioate (MAMPC, C7H8N4S3) were measured in the spectral range of 3700-100 cm(-1) and 4000-200 cm(-1) with a resolution of 4 and 0.5 cm(-1), respectively. Room temperature 13C NMR and (1)H NMR spectra from room temperature down to -60 °C were also recorded. As a result of internal rotation around C-N and/or C-S bonds, eighteen rotational isomers are suggested for the MAMPC molecule (Cs symmetry). DFT/B3LYP and MP2 calculations were carried out up to 6-311++G(d,p) basis sets to include polarization and diffusion functions. The results favor conformer 1 in the solid (experimentally) and gaseous (theoretically) phases. For conformer 1, the two -CH3 groups are directed towards the nitrogen atoms (pyrazole ring) and CS, while the -NH2 group retains sp2 hybridization and C-CN bond is quasi linear. To support NMR spectral assignments, chemical shifts (δ) were predicted at the B3LYP/6-311+G(2d,p) level using the method of Gauge-Invariant Atomic Orbital (GIAO) method. Moreover, the solvent effect was included via the Polarizable Continuum Model (PCM). Additionally, both infrared and Raman spectra were predicted using B3LYP/6-31G(d) calculations. The recorded vibrational, 1H and 13C NMR spectral data favors conformer 1 in both the solid phase and in solution. Aided by normal coordinate analysis and potential energy distributions, confident vibrational assignments for observed bands have been proposed. Moreover, the CH3 barriers to internal rotations were investigated. The results are discussed herein are compared with similar molecules whenever appropriate.

Post-laser assisted in situ keratomileusis epithelial ingrowth and its relation to pretreatment refractive error.

PURPOSE: To assess the incidence of epithelial ingrowth after laser in situ keratomileusis and its correlation with myopic or hyperopic treatment. METHODS: This retrospective study analyzed 1000 consecutive LASIK procedures performed by 3 surgeons using identical surgical technique with a Hansatome microkeratome. Eyes that developed epithelial ingrowth were evaluated using the Machat grading system. Patients were subdivided into 2 groups (myopic or hyperopic) based on the preoperative refractive error. RESULTS: The total incidence of epithelial ingrowth was 4.7%. The incidence after primary treatment was 3.9%. The incidence after enhancement was 12.8%. The total incidence of epithelial ingrowth was 3% in the myopic group compared with 23% in the hyperopic group. After primary myopic treatment, there was a 3% incidence of epithelial ingrowth compared with 17% after primary hyperopic treatment. The incidence after enhancement was 7% in the myopic group and 43% in the hyperopic group. CONCLUSIONS: Patients undergoing hyperopic laser in situ keratomileusis have a greater incidence of epithelial ingrowth than those undergoing myopic treatment. In addition, enhancement procedures have a higher incidence than primary procedures.