Alkene hydrosilylation, the addition of a silicon hydride (Si-H) across a carbon-carbon double bond, is one of the largest-scale industrial applications of homogeneous catalysis and is used in the ...commercial production of numerous consumer goods. For decades, precious metals, principally compounds of platinum and rhodium, have been used as catalysts for this reaction class. Despite their widespread application, limitations such as high and volatile catalyst costs and competing side reactions have persisted. Here, we report that well-characterized molecular iron coordination compounds promote the selective anti-Markovnikov addition of sterically hindered, tertiary silanes to alkenes under mild conditions. These Earth-abundant base-metal catalysts, coordinated by optimized bis(imino) pyridine ligands, show promise for industrial application.
The aryl-substituted bis(imino)pyridine cobalt methyl complex, (MesPDI)CoCH3 (MesPDI = 2,6-(2,4,6-Me3C6H2-NCMe)2C5H3N), promotes the catalytic dehydrogenative silylation of linear α-olefins to ...selectively form the corresponding allylsilanes with commercially relevant tertiary silanes such as (Me3SiO)2MeSiH and (EtO)3SiH. Dehydrogenative silylation of internal olefins such as cis- and trans-4-octene also exclusively produces the allylsilane with the silicon located at the terminus of the hydrocarbon chain, resulting in a highly selective base-metal-catalyzed method for the remote functionalization of C–H bonds with retention of unsaturation. The cobalt-catalyzed reactions also enable inexpensive α-olefins to serve as functional equivalents of the more valuable α, ω-dienes and offer a unique method for the cross-linking of silicone fluids with well-defined carbon spacers. Stoichiometric experiments and deuterium labeling studies support activation of the cobalt alkyl precursor to form a putative cobalt silyl, which undergoes 2,1-insertion of the alkene followed by selective β-hydrogen elimination from the carbon distal from the large tertiary silyl group and accounts for the observed selectivity for allylsilane formation.
Iron dialkyl complexes, N3Fe(CH2SiMe3)2, with three different classes of tridentate, nitrogen-based “N3” ligands, aryl-substituted bis(imino)pyridines, terpyridine, and pyridine bis(oxazoline), have ...been synthesized and evaluated in the catalytic hydrosilylation of olefins with tertiary silanes. The 2,2′:6′,2″-terpyridine (terpy) complex, (terpy)Fe(CH2SiMe3)2, was prepared either via alkylation of (terpy)FeCl2 with LiCH2SiMe3 or by pyridine displacement from (pyridine)2Fe(CH2SiMe3)2 by free terpyridine. The aryl-substituted bis(imino)pyridine compounds, (RPDI)Fe(CH2SiMe3)2 (RPDI = 2,6-(2,6-R2-C6H3NCMe)2C5H3N), with smaller 2,6-dialkyl substituents (R = Et, Me) or a 2- i Pr substituent (2‑iPrPDI)Fe(CH2SiMe3)2 (2‑iPrPDI = 2,6-(2- i Pr-C6H4NCMe)2C5H3N, are effective precursors (0.5 mol %) for the anti-Markovnikov hydrosilylation of 1-octene with (Me3SiO)2MeSiH and (EtO)3SiH over the course of 1 h at 60 °C. No hydrosilylation activity was observed with Et3SiH. The most hindered member of the series, ( iPrPDI)Fe(CH2SiMe3)2, and the pyridine bis(oxazoline) iron compound, (R,R)-( iPrPybox)Fe(CH2SiMe3)2 ( iPrPybox = 2,6-bisisopropyl-2-oxazolin-2-ylpyridine), were inactive for the hydrosilylation of 1-octene with all tertiary silanes studied. By contrast, the terpyridine precursor, (terpy)Fe(CH2SiMe3)2, reached >95% conversion at 60 °C with Et3SiH and (Me3SiO)2MeSiH. In addition, the hydrosilylation of vinylcyclohexene oxide was accomplished in the presence of 1.0 mol % (terpy)Fe(CH2SiMe3)2, demonstrating functional group compatibility unique to this compound that is absent from bis(imino)pyridine iron compounds. The electronic structures of all three classes of iron dialkyl compounds have been evaluated by a combination of X-ray diffraction, magnetochemistry, Mössbauer spectroscopy, and density functional theory calculations. All of the compounds are best described as high-spin iron(III) compounds with antiferromagnetic coupling to chelate radical anions.
Aryl-substituted bis(imino)pyridine iron dinitrogen complexes are active for the hydrosilylation of 1,2,4-trivinylcyclohexane with tertiary alkoxy silanes, a process used in the manufacture of low ...rolling resistance tires. The iron compounds exhibit unprecedented selectivity for the monohydrosilylation of the desired 4-alkene that far exceeds results obtained with commercially used platinum compounds.
Individuals with schizophrenia spectrum disorders (SSD) are at heightened risk for exposure to stressful life events which can lead to increased sensitivity to stress and a dysregulated stress ...response, which are in turn associated with poor long-term functioning. Stress reactivity is thus a promising treatment target in the early stages of SSD. Integrated-Coping Awareness Therapy (I-CAT) is a manualized intervention integrating mindfulness and positive psychology to target a dysregulated stress response in SSD. The current study is a preliminary randomized-controlled trial (RCT) comparing I-CAT (n = 18) with treatment as usual (TAU; n = 18) in individuals in the early stages of SSD. I-CAT was hypothesized to be more effective than TAU on primary outcomes: increasing positive emotions, decreasing negative emotions, reducing stress, and improving functioning and quality of life; and secondary outcomes: reducing symptoms, increasing mindfulness, and improving overall well-being. Excellent therapy attendance rates, low study attrition, and positive participant feedback demonstrated that I-CAT was a feasible and well-tolerated psychosocial intervention. Results suggest I-CAT led to greater reduction in symptoms (i.e., overall, negative, and disorganized symptoms), increased observational mindfulness, increased endorsement of a sense of purpose in life, and preservation of work abilities and school social functioning compared with TAU. Future work should replicate and extend these findings in a larger-scale RCT.
Cataract is an important cause of visual impairment in children. Data from a large pediatric cataract surgery registry can provide real-world estimates of visual outcomes and the 5-year cumulative ...incidence of adverse events.
To assess visual acuity (VA), incidence of complications and additional eye operations, and refractive error outcomes 5 years after pediatric lensectomy among children younger than 13 years.
This prospective cohort study used data from the Pediatric Eye Disease Investigator Group clinical research registry. From June 2012 to July 2015, 61 eye care practices in the US, Canada, and the UK enrolled children from birth to less than 13 years of age who had undergone lensectomy for any reason during the preceding 45 days. Data were collected from medical record reviews annually thereafter for 5 years until September 28, 2020.
Lensectomy with or without implantation of an intraocular lens (IOL).
Best-corrected VA and refractive error were measured from 4 to 6 years after the initial lensectomy. Cox proportional hazards regression was used to assess the 5-year incidence of glaucoma or glaucoma suspect and additional eye operations. Factors were evaluated separately for unilateral and bilateral aphakia and pseudophakia.
A total of 994 children (1268 eyes) undergoing bilateral or unilateral lensectomy were included (504 51% male; median age, 3.6 years; range, 2 weeks to 12.9 years). Five years after the initial lensectomy, the median VA among 701 eyes with available VA data (55%) was 20/63 (range, 20/40 to 20/100) in 182 of 316 bilateral aphakic eyes (58%), 20/32 (range, 20/25 to 20/50) in 209 of 386 bilateral pseudophakic eyes (54%), 20/200 (range, 20/50 to 20/618) in 124 of 202 unilateral aphakic eyes (61%), and 20/65 (range, 20/32 to 20/230) in 186 of 364 unilateral pseudophakic eyes (51%). The 5-year cumulative incidence of glaucoma or glaucoma suspect was 46% (95% CI, 28%-59%) in participants with bilateral aphakia, 7% (95% CI, 1%-12%) in those with bilateral pseudophakia, 25% (95% CI, 15%-34%) in those with unilateral aphakia, and 17% (95% CI, 5%-28%) in those with unilateral pseudophakia. The most common additional eye surgery was clearing the visual axis, with a 5-year cumulative incidence of 13% (95% CI, 8%-17%) in participants with bilateral aphakia, 33% (95% CI, 26%-39%) in those with bilateral pseudophakia, 11% (95% CI, 6%-15%) in those with unilateral aphakia, and 34% (95% CI, 28%-39%) in those with unilateral pseudophakia. The median 5-year change in spherical equivalent refractive error was -8.38 D (IQR, -11.38 D to -2.75 D) among 89 bilateral aphakic eyes, -1.63 D (IQR, -3.13 D to -0.25 D) among 130 bilateral pseudophakic eyes, -10.75 D (IQR, -20.50 D to -4.50 D) among 43 unilateral aphakic eyes, and -1.94 D (IQR, -3.25 D to -0.69 D) among 112 unilateral pseudophakic eyes.
In this cohort study, development of glaucoma or glaucoma suspect was common in children 5 years after lensectomy. Myopic shift was modest during the 5 years after placement of an intraocular lens, which should be factored into implant power selection. These results support frequent monitoring after pediatric cataract surgery to detect glaucoma, visual axis obscuration causing reduced vision, and refractive error.
Glaucoma can develop following cataract removal in children.
To assess the cumulative incidence of glaucoma-related adverse events (defined as glaucoma or glaucoma suspect) and factors associated ...with risk of these adverse events in the first 5 years after lensectomy prior to 13 years of age.
This cohort study used longitudinal registry data collected at enrollment and annually for 5 years from 45 institutional and 16 community sites. Participants were children aged 12 years or younger with at least 1 office visit after lensectomy from June 2012 to July 2015. Data were analyzed from February through December 2022.
Usual clinical care after lensectomy.
The main outcomes were cumulative incidence of glaucoma-related adverse events and baseline factors associated with risk of these adverse events.
The study included 810 children (1049 eyes); 443 eyes of 321 children (55% female; mean SD age, 0.89 1.97 years) were aphakic after lensectomy, and 606 eyes of 489 children (53% male; mean SD age, 5.65 3.32 years) were pseudophakic. The 5-year cumulative incidence of glaucoma-related adverse events was 29% (95% CI, 25%-34%) in 443 eyes with aphakia and 7% (95% CI, 5%-9%) in 606 eyes with pseudophakia; 7% (95% CI, 5%-10%) of aphakic eyes and 3% (95% CI, 2%-5%) of pseudophakic eyes were diagnosed as glaucoma suspect. Among aphakic eyes, a higher risk for glaucoma-related adverse events was associated with 4 of 8 factors, including age less than 3 months (vs ≥3 months: adjusted hazard ratio aHR, 2.88; 99% CI, 1.57-5.23), abnormal anterior segment (vs normal: aHR, 2.88; 99% CI, 1.56-5.30), intraoperative complications at time of lensectomy (vs none; aHR, 2.25; 99% CI, 1.04-4.87), and bilaterality (vs unilaterality: aHR, 1.88; 99% CI, 1.02-3.48). Neither of the 2 factors evaluated for pseudophakic eyes, laterality and anterior vitrectomy, were associated with risk of glaucoma-related adverse events.
In this cohort study, glaucoma-related adverse events were common after cataract surgery in children; age less than 3 months at surgery was associated with elevated risk of the adverse events in aphakic eyes. Children with pseudophakia, who were older at surgery, less frequently developed a glaucoma-related adverse event within 5 years of lensectomy. The findings suggest that ongoing monitoring for the development of glaucoma is needed after lensectomy at any age.
The Pediatric Eye Disease Investigator Group Cataract Registry provides a multicenter assessment of visual outcomes and complications after lensectomy for traumatic pediatric cataract.
To report ...visual acuity (VA) and the cumulative proportion with strabismus, glaucoma, and other ocular complications by 15 months after lensectomy for traumatic cataract among children younger than 13 years at the time of surgery.
From June 18, 2012, to July 8, 2015, 1266 eyes of 994 children from 33 pediatric eye care practices seen within 45 days after lensectomy were enrolled in a multicenter, prospective observational registry. Of these, 74 eyes of 72 participants undergoing lensectomy for traumatic cataract were included in a cohort study. Follow-up was completed by November 2, 2015, and data were analyzed from March 20, 2018, to July 7, 2020.
Lensectomy after ocular trauma.
Best-corrected VA from 9 to 15 months after lensectomy for traumatic cataract (for those 3 years or older) and the cumulative proportion with strabismus, glaucoma, and other ocular complications by 15 months.
Of 994 participants in the registry, 84 (8%) had traumatic cataract. The median age at lensectomy for 72 participants examined within 15 months after surgery was 7.3 (range, 0.1-12.6) years; 46 (64%) were boys. An intraocular lens was placed in 57 of 74 eyes (77%). In children 3 years or older at outcome, the median best-corrected VA was 20/250 (range, 20/20 to worse than 20/800) in 6 eyes with aphakia and 20/63 (range, 20/20 to 20/200) in 26 eyes with pseudophakia. Postoperative visual axis opacification was reported in 18 of 27 eyes with pseudophakia without primary posterior capsulotomy (15-month cumulative proportion, 77%; 95% CI, 58%-92%). The cumulative proportion with strabismus was 43% (95% CI, 31%-58%) in 64 participants with ocular alignment data; exotropia was present in 14 of 23 participants (61%). The cumulative proportion with glaucoma was 6% (95% CI, 2%-16%).
Trauma was not a common cause of pediatric cataract requiring surgery. For children with traumatic cataract, substantial ocular morbidity including permanent vision loss was found, and long-term eye and vision monitoring are needed for glaucoma, strabismus, and capsular opacification.
Essentials of the Exotic Pet Practice Brown, Susan A.; Nye, Richard R.
Journal of exotic pet medicine,
07/2006, Letnik:
15, Številka:
3
Journal Article
Recenzirano
Exotic pet practice is an exciting but demanding field in veterinary medicine. The decision to enter this field should be made only after careful consideration of some of the unique challenges and ...responsibilities of this type of practice. This article covers the considerations to be made when choosing species to see as patients, specific challenges for the exotic pet practitioner, legal and ethical issues regarding exotic species, sources of patients, development of a network for referral veterinarians, and a discussion of education for the veterinarian, staff, and clients. Also covered are suggestions for additions to the physical plant as well as recommendations for surgical, anesthetic, treatment, and examination equipment. There is an extensive list of additional recommended sources of information in the forms of texts, publications, organizations, and internet sites included at the end of the article.
