Analysis of Wavefront Data Obtained With a Pyramidal Sensor in Pseudophakic Eyes Implanted With Diffractive Intraocular Lenses.

PURPOSE: To investigate the clinical validity of using wavefront measurements obtained with a recently available pyramidal aberrometer to assess the optical quality of eyes implanted with diffractive intraocular lenses (IOLs). METHODS: Individual biometric data were used to create models of pseudophakic eyes implanted with two diffractive IOLs. Their synthetic wavefronts were calculated by ray-tracing with near infrared wavelength (0.85 µm). Comparisons of the through-focus visual acuity of 12 pseudophakic eyes were obtained with three different methods: clinical defocus curves; simulated defocus curves calculated from ray-tracing in the customized model eyes; and through-focus simulated defocus curves calculated from the wavefront data measured with a pyramidal aberrometer. RESULTS: Image quality calculated from wavefront data obtained by ray-tracing with 0.85 µm wavelength, without scaling the phase to 0.55 µm, resulted in a significantly different through-focus curve compared to the reference values. Even so, after scaling of the wavefront data to 0.55 µm, the defocus curves calculated from the wavefronts measured with the pyramidal aberrometer did not match the shape and the depth of field of the clinical defocus curves or the theoretical expected values. CONCLUSIONS: Correcting for the longitudinal chromatic aberration of the eye when measuring the wavefront of eyes implanted with diffractive IOLs under near infrared light only accounts for the best focus shift due to the longitudinal chromatic aberration, but not for the wavelength dependence of the diffractive element. The pyramidal sensor does not seem to properly sample the slopes of a wavefront measured from a pseudophakic eye implanted with a presbyopia-correcting diffractive IOL to a clinically acceptable level. [J Refract Surg. 2023;39(7):438-444.].

Complete biodegradation of 4-fluorocinnamic acid by a consortium comprising Arthrobacter sp. strain G1 and Ralstonia sp. strain H1.

A consortium of the newly isolated bacterial strains Arthrobacter sp. strain G1 and Ralstonia sp. strain H1 utilized 4-fluorocinnamic acid for growth under aerobic conditions. Strain G1 converted 4-fluorocinnamic acid into 4-fluorobenzoic acid and used the two-carbon side chain for growth, with some formation of 4-fluoroacetophenone as a dead-end side product. In the presence of strain H1, complete mineralization of 4-fluorocinnamic acid and release of fluoride were obtained. Degradation of 4-fluorocinnamic acid by strain G1 occurred through a ß-oxidation mechanism and started with the formation of 4-fluorocinnamoyl-coenzyme A (CoA), as indicated by the presence of 4-fluorocinnamoyl-CoA ligase. Enzymes for further transformation were detected in cell extract, i.e., 4-fluorocinnamoyl-CoA hydratase, 4-fluorophenyl-ß-hydroxy propionyl-CoA dehydrogenase, and 4-fluorophenyl-ß-keto propionyl-CoA thiolase. Degradation of 4-fluorobenzoic acid by strain H1 proceeded via 4-fluorocatechol, which was converted by an ortho-cleavage pathway.

Analysis of two gene clusters involved in the degradation of 4-fluorophenol by Arthrobacter sp. strain IF1.

Arthrobacter sp. strain IF1 is able to grow on 4-fluorophenol (4-FP) as a sole source of carbon and energy. To clone the 4-FP degradation genes, DNA libraries were constructed and screened with a probe obtained by PCR using primers designed on the basis of conserved regions of aromatic two-component monooxygenases. Sequencing of positive clones yielded two gene clusters, each harboring a gene encoding a monooxygenase with high sequence similarity to the oxygenase component of 4-nitrophenol and 4-chlorophenol monooxygenase systems. Both these monooxygenase genes were differentially expressed during growth on 4-FP, as revealed by Northern blotting and reverse transcription-PCR. One cluster also contained a gene for a flavin reductase. The monooxygenase and reductase were purified from Escherichia coli cells expressing the corresponding genes, and together they catalyzed NADH-dependent hydroxylation and dehalogenation of 4-halophenols. The results indicate that strain IF1 transforms 4-FP to hydroquinone by a two-component monooxygenase system of which one component provides reduced flavin adenine dinucleotide at the expense of NADH and the other catalyzes para-hydroxylation of 4-FP and other 4-substituted phenols.

Probing local effects in silica sol-gel media by fluorescence spectroscopy of p-DASPMI.

Stillbazolium salts present remarkable potential for application in several scientific areas. Their versatile behavior is explained by invoking the "twisted intramolecular charge-transfer" (TICT) mechanism, a model that describes the multiple fluorescence of DASPMI (4-(4-(dimethylamino)styryl)- N-methylpyridiniumiodine). One feature of their behavior is the sensitivity of the fluorescence lifetime to viscosity, thus identifying them as suitable probes for microheterogeneous systems, such as cells and sol-gel derived media. Because of their optical transparency, sol-gel matrices are light addressable and therefore appropriate for performing spectroscopic studies. The sol-gel process has been successfully used to produce hosts to biomolecules like proteins, for biosensor applications; however, these systems have to be optimized. Therefore, in this study modification of the matrices was performed through the incorporation of either silanes or polymers. (Aminopropyl)triethoxysilane, trimethoxypropylsilane, or (glycidyloxypropyl)triethoxysilane were added. The modification was also extended to the incorporation of the polymers poly(ethylene glycol) (molecular weight 300 and 20000) and Gelrite. The effect of these modifiers upon the gelation and aging processes was examined via the study of the photophysics of p-DASPMI by using both steady-state and time-resolved fluorescence. It was possible to discriminate the dominant dye-host interactions in each of the main steps of the preparation of modified sol-gel matrices.

Variability with xylem depth in sap flow in trunks and branches of mature olive trees.

Knowledge of sap flow variability in tree trunks is important for up-scaling transpiration from the measuring point to the whole-tree and stand levels. Natural variability in sap flow, both radial and circumferential, was studied in the trunks and branches of mature olive trees (Olea europea L., cv Coratina) by the heat field deformation method using multi-point sensors. Sapwood depth ranged from 22 to 55 mm with greater variability in trunks than in branches. Two asymmetric types of sap flow radial patterns were observed: Type 1, rising to a maximum near the mid-point of the sapwood; and Type 2, falling continuously from a maximum just below cambium to zero at the inner boundary of the sapwood. The Type 1 pattern was recorded more often in branches and smaller trees. Both types of sap flow radial patterns were observed in trunks of the sample trees. Sap flow radial patterns were rather stable during the day, but varied with soil water changes. A decrease in sap flow in the outermost xylem was related to water depletion in the topsoil. We hypothesized that the variations in sap flow radial pattern in a tree trunk reflects a vertical distribution of water uptake that varies with water availability in different soil layers.

The N-P-K soil nutrient balance of Portuguese cropland in the 1950s: The transition from organic to chemical fertilization.

Agricultural nutrient balances have been receiving increasing attention in both historical and nutrient management research. The main objectives of this study were to further develop balance methodologies and to carry out a comprehensive assessment of the functioning and nutrient cycling of 1950s agroecosystems in Portugal. Additionally, the main implications for the history of agriculture in Portugal were discussed from the standpoint of soil fertility. We used a mass balance approach that comprises virtually all nitrogen (N), phosphorus (P) and potassium (K) inputs and outputs from cropland topsoil for average conditions in the period 1951-56. We found a consistent deficit in N, both for nationwide (-2.1 kg.ha-1.yr-1) and arable crops (-1.6 kg.ha-1.yr-1) estimates, that was rectified in the turn to the 1960 decade. P and K were, in contrast, accumulating in the soil (4.2-4.6 kg.ha-1.yr-1 and 1.0-3.0 kg.ha-1.yr-1, respectively). We observed that the 1950s is the very moment of inflection from an agriculture fertilized predominantly through reused N in biomass (livestock excretions plus marine, plant and human waste sources) to one where chemical fertilizers prevailed. It is suggested that N deficiency played an important role in this transition.

Degradation of 4-fluorophenol by Arthrobacter sp. strain IF1.

A Gram-positive bacterial strain capable of aerobic biodegradation of 4-fluorophenol (4-FP) as the sole source of carbon and energy was isolated by selective enrichment from soil samples collected near an industrial site. The organism, designated strain IF1, was identified as a member of the genus Arthrobacter on the basis of 16S ribosomal RNA gene sequence analysis. Arthrobacter strain IF1 was able to mineralize 4-FP up to concentrations of 5 mM in batch culture. Stoichiometric release of fluoride ions was observed, suggesting that there is no formation of halogenated dead-end products during 4-FP metabolism. The degradative pathway of 4-FP was investigated using enzyme assays and identification of intermediates by gas chromatography (GC), GC-mass spectrometry (MS), high-performance liquid chromatography, and liquid chromatography-MS. Cell-free extracts of 4-FP-grown cells contained no activity for catechol 1,2-dioxygenase or catechol 2,3-dioxygenase, which indicates that the pathway does not proceed through a catechol intermediate. Cells grown on 4-FP oxidized 4-FP, hydroquinone, and hydroxyquinol but not 4-fluorocatechol. During 4-FP metabolism, hydroquinone accumulated as a product. Hydroquinone could be converted to hydroxyquinol, which was further transformed into maleylacetic acid and beta-ketoadipic acid. These results indicate that the biodegradation of 4-FP starts with a 4-FP monooxygenase reaction that yields benzoquinone, which is reduced to hydroquinone and further metabolized via the beta-ketoadipic acid pathway.

Degradation of fluorobenzene by Rhizobiales strain F11 via ortho cleavage of 4-fluorocatechol and catechol.

The aerobic metabolism of fluorobenzene by Rhizobiales sp. strain F11 was investigated. Liquid chromatography-mass spectrometry analysis showed that 4-fluorocatechol and catechol were formed as intermediates during fluorobenzene degradation by cell suspensions. Both these compounds, unlike 3-fluorocatechol, supported growth and oxygen uptake. Cells grown on fluorobenzene contained enzymes for the ortho pathway but not for meta ring cleavage of catechols. The results suggest that fluorobenzene is predominantly degraded via 4-fluorocatechol with subsequent ortho cleavage and also partially via catechol.