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Humans have incorporated minerals in objects of cultural heritage importance for millennia. The surfaces of these objects, which often long outlast the humans that create them, are undeniably exposed to a diverse mixture of chemicals throughout their lifetimes. As of yet, the art conservation community lacks a nondestructive, accurate, and inexpensive flexible computational screening method to evaluate the potential impact of chemicals with art, as a complement to experimental studies. In this work, we propose periodic density functional theory (DFT) studies as a way to address this challenge, specifically for the aragonite phase of calcium carbonate, a mineral that has been used in pigments, marble statues, and limestone architecture since ancient times. Computational models allow art conservation scientists to better understand the atomistic impact of small-molecule adsorbates on common mineral surfaces across a wide variety of environmental conditions. To gain insight into the surface adsorption reactivity of aragonite, we use DFT to investigate the atomistic interactions present in small-molecule-surface interfaces. Our adsorbate set includes common solvents, atmospheric pollutants, and emerging contaminants. Chemicals that significantly disrupt the surface structure such as carboxylic acids and sulfur-containing molecules are highlighted. We also focus on comparing adsorption energies and changes in surface bonds, which allows for the identification of key features in the electronic structure presented in a projected-density-of-state analysis. The trends outlined here will guide future experiments and allow art conservators to gain a better understanding of how a wide range of molecules interact with an aragonite surface under variable conditions and in different environments.

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Purpose: A group of keratoconus subjects (KG) and a control group (CG) were evaluated for sensory and motor status. We tried to clarify the factors (best-corrected visual acuity [BCVA]), heterophorias, fusional amplitude, anisometropia, astigmatism) that may be associated with a binocular disturbance. Methods: BCVA (logMAR) was measured. Binocular vision was checked using cover tests, striate Maddox, and a 6Δ base-down prism (simultaneous perception), a prism bar (fusion and fusional convergence break point), and Titmus Fly Test (stereopsis). Results: Fifty-four subjects of the KG, 27 men (median 16 years), and 29 of the CG, 15 men (median 20 years), were evaluated. In the KG, 8 (15%) subjects had strabismus. Those whose BCVA in the worse eye was logMAR ≥0.7 had a significantly higher frequency of strabismus and absence of simultaneous perception. Spherical equivalent anisometropia ≥ 1.0 diopter (D) was significantly different in both groups as was the frequency of gross stereopsis. In comparing fine and gross stereopsis in both the KG and the CG, there was a significant difference in the frontal astigmatism between eyes in the KG (P = 0.03) and CG (P = 0.01). Conclusions: In our study, the KG presented a higher frequency of strabismus and impaired binocular vision. Frontal astigmatism was different between groups with gross and fine stereopsis, in both the CG and KG. Future studies are needed to elucidate or reinforce the factors associated with the loss of binocularity in keratoconus. Testing for stereopsis may be helpful to consider in the treatment guidelines for keratoconus.

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The practical advantages of quantifying an angle by a ratio of linear lengths instead of arcs of circles has led to the definition of the prism-diopter, a conventional unity for numbering prisms and measuring strabismic deviations. However, a major inconvenience of using prism-diopter unities to express angular measurements is the non-linearity of the scale, which reaches an infinite value for the angle of 90º, then becomes negative, with decreasing magnitudes for increasing angles between 90º and 180º. As a consequence, arithmetical operations and comparisons of angles measured by such unities present errors of very great magnitudes. In order to retain the advantages of defining an angle by straight line dimensions but to diminish the severe inconveniences of this method, a new definition of the prism-diopter is proposed. Here, instead of defining the prism-diopter by the asymmetrical condition, the conception of this new unity is based on a geometrically symmetrical condition; that of the relationship of an isosceles triangle (where the leg is perpendicular to the bisector of the angle and the bisector itself ). The condition of symmetry for the definition of the new unity represents a conceptual advance because it reproduces the already well accepted, conventional criteria for quantifying the value of a prism, that of its minimum deviation. Furthermore, it corresponds to the most commonly observed clinical conditions of binocular balance. The absolute differences between the unitary values of the prism-diopter and that of the new unity are negligible (0.0025%), but the scale of values expressed by the new unity is closer to the ideal scale of angular measurements. (With the new unity, the infinite value is only reached for an angle of 180º and the errors due to arithmetical operations are much smaller.) Numerical examples showing the advantages of using the new unity of angular measurements instead of the prism-diopter are presented. A mathematical generalization of the modifying concept (partition of an angle) with which the new unity is based is also provided.

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PURPOSE: One of the challenges in strabismus is to guarantee stability of the surgical corrections. Re-surgeries are often required even after careful diagnosis, planning, and execution. Several factors contribute to this undesired outcome and the existing management strategies are ineffective. The present alternative is to compensate for their consequences. Ocular rotations are evoked by muscular contractions and relaxations (active forces). During eye movement, periocular tissues are stretched, storing part of the kinetic energy, which may be posteriorly recovered (passive forces), whereas the remaining part of the energy is lost via friction and inelastic deformations (dissipative forces). A method for measuring the forces that cause post-surgery eye drift has not been reported. However, this may be indirectly determined as a function of the respective mechanical variables. The estimated ratio between the kinetic energies of a post-surgery eye drift and a normal pursuit eye movement is ~10(-15). Theoretically, it can be expected that the addition of continuously acting forces of such magnitudes to the oculomotor system might prevent the undesired post-surgery eye movement. METHODS: Several methods for increasing the restraining, dissipative forces to ocular rotations may be conceived. One method is to increase the friction to ocular movements, as for instance, by periocular injection of viscous substances. Another possibility is to use the forces of a magnetic field, which may stabilize the eye in a desired position without avoiding the rotations caused by greater muscular forces acting on it. It has been demonstrated that these forces neutralize the nystagmic movements, whose intensities of mechanical variables are much higher than those of a post-surgery eye drift. Some models of application of this technique are then discussed. Small magnets fixed to the orbit and metallic ferromagnetic elements fixed to the sclera to cover a suitable extension appears to be the best method for providing starting and sliding friction to the oculomotor system. RESULTS: Weak magnetic fields do not cause ocular ill effects. Additionally, the magnetic field may be confined to the elements of the circuit and may not leak. However, the magnetic materials may interfere with magnetic resonance image (MRI) examinations.

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The practical advantages of quantifying an angle by a ratio of linear lengths instead of arcs of circles has led to the definition of the prism-diopter, a conventional unity for numbering prisms and measuring strabismic deviations. However, a major inconvenience of using prism-diopter unities to express angular measurements is the non-linearity of the scale, which reaches an infinite value for the angle of 90º, then becomes negative, with decreasing magnitudes for increasing angles between 90º and 180º. As a consequence, arithmetical operations and comparisons of angles measured by such unities present errors of very great magnitudes. In order to retain the advantages of defining an angle by straight line dimensions but to diminish the severe inconveniences of this method, a new definition of the prism-diopter is proposed. Here, instead of defining the prism-diopter by the asymmetrical condition, the conception of this new unity is based on a geometrically symmetrical condition; that of the relationship of an isosceles triangle (where the leg is perpendicular to the bisector of the angle and the bisector itself ). The condition of symmetry for the definition of the new unity represents a conceptual advance because it reproduces the already well accepted, conventional criteria for quantifying the value of a prism, that of its minimum deviation. Furthermore, it corresponds to the most commonly observed clinical conditions of binocular balance. The absolute differences between the unitary values of the prism-diopter and that of the new unity are negligible (0.0025%), but the scale of values expressed by the new unity is closer to the ideal scale of angular measurements. (With the new unity, the infinite value is only reached for an angle of 180º and the errors due to arithmetical operations are much smaller.) Numerical examples showing the advantages of using the new unity of angular measurements instead of the prism-diopter are presented. A mathematical generalization of the modifying concept (partition of an angle) with which the new unity is based is also provided.

As vantagens práticas de quantificação de um ângulo pela relação de comprimentos lineares em lugar dos de arcos de círculos propiciaram a definição da dioptria- prismática, uma unidade convencional de numeração dos prismas e de medições do estrabismo. Entretanto, um grande inconveniente do uso das dioptrias- -prismáticas para exprimir medidas angulares é a não-linearidade da escala, que alcança um valor infinito para o ângulo de 90º e passa a valores negativos e com magnitudes decrescentes para ângulos crescentes entre 90º e 180º. Como consequência, operações aritméticas e comparações de ângulos com medidas angulares expressas com tais unidades apresentam erros de magnitude muito grande. Para manutenção das vantagens de definição de um ângulo pela dimensão de distâncias retas, mas reduzindo os graves inconvenientes dessa escolha, propõe-se uma nova definição para a dioptria-prismática. Ao invés da condição assimétrica pela qual a dioptria-prismática é definida, a concepção dessa nova unidade é baseada em uma condição geometricamente simétrica, a das relações de um triângulo isósceles (o cateto perpendicular à bissetriz do ângulo e essa própria bissetriz). Essa condição de simetria para a definição da nova unidade corresponde a um avanço conceitual, por reproduzir o critério convencional, já bem aceito, de quantificação do valor do prisma, o de seu desvio mínimo, além de corresponder às condições clínicas de exame do equilíbrio binocular comumente usadas. A diferença absoluta entre os valores unitários da dioptria-prismática e o da nova unidade é negligenciável (0,0025%) mas a escala dos valores expressos pela nova unidade é mais próxima da escala ideal de medidas angulares. (Com a nova unidade, o valor infinito é apenas alcançado para um ângulo de 180º e os erros devidos às operações aritméticas são muito menores.) Dão-se exemplos numéricos mostrando as vantagens de uso da nova unidade de medidas angulares em lugar da dioptria-prismática. Apresenta-se, também, uma generalização matemática do conceito de modificação (partição de um ângulo) pelo qual a nova unidade é baseada.

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Purpose: One of the challenges in strabismus is to guarantee stability of the surgical corrections. Re-surgeries are often required even after careful diagnosis, planning, and execution. Several factors contribute to this undesired outcome and the existing management strategies are ineffective. The present alternative is to compensate for their consequences. Ocular rotations are evoked by muscular contractions and relaxations (active forces). During eye movement, periocular tissues are stretched, storing part of the kinetic energy, which may be posteriorly recovered (passive forces), whereas the remaining part of the energy is lost via friction and inelastic deformations (dissipative forces). A method for measuring the forces that cause post-surgery eye drift has not been reported. However, this may be indirectly determined as a function of the respective mechanical variables. The estimated ratio between the kinetic energies of a post-surgery eye drift and a normal pursuit eye movement is ~10-15. Theoretically, it can be expected that the addition of continuously acting forces of such magnitudes to the oculomotor system might prevent the undesired post-surgery eye movement. Methods: Several methods for increasing the restraining, dissipative forces to ocular rotations may be conceived. One method is to increase the friction to ocular movements, as for instance, by periocular injection of viscous substances. Another possibility is to use the forces of a magnetic field, which may stabilize the eye in a desired position without avoiding the rotations caused by greater muscular forces acting on it. It has been demonstrated that these forces neutralize the nystagmic movements, whose intensities of mechanical variables are much higher than those of a post-surgery eye drift. Some models of application of this technique are then discussed. Small magnets fixed to the orbit and metallic ferromagnetic elements fixed to the sclera to cover a suitable ...

Objetivo: Um grande problema nos estrabismos é garantir um resultado bom e estável de suas correções cirúrgicas. A necessidade de reoperações é relativamente alta, apesar de cuidadosos procedimentos diagnósticos, planejamento cirúrgico e execução tenham sido tomados. O resultado indesejado é devido a muitos fatores que ainda não são apropriadamente controlados. A alternativa atual é, então, compensar as consequências correspondentes. Rotações oculares são evocadas por contrações e relaxamentos musculares (forças ativas). Nesses movimentos oculares, tecidos perioculares são distendidos, mantendo parte da energia cinética, que pode ser posteriormente recuperada (forças passivas), enquanto outra parte é definitivamente perdida em fricção e deformações inelásticas (forças dissipativas). Não é conhecida a medida das forças que causam um desvio ocular pós-operatório, mas ela pode ser indiretamente determinada como função das respectivas variáveis mecânicas. A relação entre as energias cinéticas de um desvio ocular pós-operatório e de um movimento ocular persecutório normal pode ser então estimada como de cerca 10-15. Teoricamente, pode-se esperar que a adição de forças dessas magnitudes ao sistema oculomotor, continuadamente atuantes, possam prevenir os movimentos pós-operatórios indesejados. Métodos: Podem ser concebidas várias possibilidades de aumento das forças dissipativas, restritivas de rotações oculares. Uma é a de aumentar a fricção aos movimentos oculares como, por exemplo, por injeções perioculares de substâncias viscoelásticas. Outra possibilidade é oferecida por forças de campos magnéticos ...

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3-Ribosylurate is a dominant feature on high performance liquid chromatography (HPLC) profiles of acid extracts of erythrocytes from cows and buffalo, but is HPLC-undetectable in acid extracts of erythrocytes from all other species examined to date. Various aspects of this unique low molecular weight substance remain unexplored since it was first identified. In this study, the mutation(s) responsible for the appearance of ribosylurate in these cells is shown to be specific to members of both tribes of the Bovinae subfamily (Bovidae family), being detectable in the erythrocytes of both the cow and the buffalo (Bovini tribe) as well as in the kudu (Strepsicerotini tribe), but not in representative species from the other subfamilies of the Bovidae family. More specifically, expression of the mutation(s) seems to be restricted to the erythrocyte lineage of these species, ribosylurate being undetectable in cow white blood cells and primary cultures of fibroblasts. Novel evidence is presented that ribosylurate has antioxidant activity. Accumulation of high levels specifically within the haemoglobin-rich milieu of circulating erythrocytes may serve to protect perfused tissues by removing pathophysiological levels of hydrogen peroxide from plasma. Maintenance of ribosylurate levels may be important in conditions associated with oxidative stress in Bovinae.

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BACKGROUND/AIMS: To compare two intraocular irrigating solutions, Balanced Salt Solution Plus (BSS Plus) versus Lactated Ringer's (Ringer), for the preservation of corneal integrity after phacoemulsification. METHODS: 110 patients undergoing phacoemulsification were randomised to either BSS Plus (n=55) or Ringer (n=55) as the irrigating solution. Patients were examined at baseline and at 1, 8, 15, 30 and 60 days postoperatively. Evaluations included specular microscopy to evaluate endothelial cell density (ECD) and endothelial cell size variability (CV), and corneal pachymetry for central corneal thickness (CCT) measurement. RESULTS: Groups were well balanced regarding baseline ECD, CV and CCT (p>0.05). There was no statistically significant difference between ECD reduction in group BSS Plus 13.1 ± 2.0% and Ringer 9.2 ± 1.9% (p<0.05) at day 60 or in any study visit. There was no statistically significant difference between CV increase in group BSS Plus 23.0 ± 3.0% and Ringer 20.2 ± 4.0% (p<0.05) at day 60 or in any study visit. CCT was significantly increased (p<0.05) at 1, 8, 15 and 30 days postoperatively, returning to baseline at 60 days in both groups. There was no significant difference in CCT increase in both groups at any visit. Interestingly, there were statistically significant correlations between ECD loss and phacoemulsification time (p<0.0001) and ECD loss and irrigation solution volume (p<0.0001) in the Ringer group, but not in the BSS Plus group. CONCLUSIONS: Ringers solution was similar to BSS Plus for corneal preservation in atraumatic cataract surgery. However, our study demonstrates that there is a trend towards lower postoperative endothelial cell density for surgeries with longer phacoemulsification time and higher irrigation volumes if Ringer is used. Trial registration number NCT00801358.

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Some particular points concerning the study of strabismus are analyzed, specially, the difficulties for definitions and the different ways it can be conceived, besides the relativity of binocular positions interpretation, and the necessary referential elements for circumscribing such questions. Then, the concept of primary position of gaze is discussed as well as the conditions for its operational attainment, leading to the conclusion that it is materially impossible to achieve this 'zero' point, from which all other measurements of strabismus or ocular movements should be done. In sequence, the construction of multiple referential systems applying the quantification of strabismus are examined. The lack of consensual agreement about which should be used as the standard system causes elementary practical implications, as the lack of agreement about how to superimpose orthogonal prisms for the measurement of associated horizontal and vertical deviations. The functional asymmetry of ocular rotations and its exceptions are commented. The accuracy that the measurements of strabismus can be performed is analyzed, leading to the conclusion that fractional figures using the commonest angular unities are improper. At last, some technical problems related to such evaluations are also commented, as operational difficulties related to prism-diopter unity, concerning the use of prisms, and prismatic effects due to the use of conventional optical glasses.

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Analisam-se particularidades inerentes ao estudo dos estrabismos, tais como as dificuldades para suas definições e os diferentes modos com os quais eles podem ser concebidos, a relatividade com que as posições binoculares possam ser interpretadas e os elementos referenciais necessários para a circunscrição dessas questões. A partir daí, discute-se o conceito de posição primária do olhar e as condições de sua operacionalização, concluindo-se pela impossibilidade de concretização desse ponto "zero", a partir do qual seriam feitas as medidas dos estrabismos e as quantificações de movimentos oculares. A seguir, passa-se ao exame da construção dos múltiplos sistemas referenciais aplicáveis à quantificação dos estrabismos, de cuja falta de consenso sobre qual deles usar decorrem implicações práticas elementares, como a falta de padronização do modo de superposição ortogonal de prismas, para a medida de desvios combinados, horizontal e vertical. Comenta-se a assimetria funcional das rotações oculares e suas exceções. Também se analisa a precisão com que se pode fazer a medida de um estrabismo, levando à conclusão sobre a impropriedade de uso de medidas fracionárias com as unidades angulares mais comumente usadas. Finalmente, são comentados alguns problemas técnicos dessas avaliações, tais como o das dificuldades operacionais relacionadas à dioptria-prismática, os subordinados ao uso de prismas e os da ocorrência de efeitos prismáticos pelo uso de lentes convencionais.

Some particular points concerning the study of strabismus are analyzed, specially, the difficulties for definitions and the different ways it can be conceived, besides the relativity of binocular positions interpretation, and the necessary referential elements for circumscribing such questions. Then, the concept of primary position of gaze is discussed as well as the conditions for its operational attainment, leading to the conclusion that it is materially impossible to achieve this "zero" point, from which all other measurements of strabismus or ocular movements should be done. In sequence, the construction of multiple referential systems applying the quantification of strabismus are examined. The lack of consensual agreement about which should be used as the standard system causes elementary practical implications, as the lack of agreement about how to superimpose orthogonal prisms for the measurement of associated horizontal and vertical deviations. The functional asymmetry of ocular rotations and its exceptions are commented. The accuracy that the measurements of strabismus can be performed is analyzed, leading to the conclusion that fractional figures using the commonest angular unities are improper. At last, some technical problems related to such evaluations are also commented, as operational difficulties related to prism-diopter unity, concerning the use of prisms, and prismatic effects due to the use of conventional optical glasses.

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