Upconversion-like Photolysis of BODIPY-Based Prodrugs via a One-Photon Process.

Photochemical reactions at lower energy than the absorption window are currently achieved by multi-photon processes, including two-photon absorption and photon upconversion, which have limited energy utilization efficiency. Here, we report a one-photon strategy based on triplet-triplet energy transfer (TTET) between a photosensitizer and a photocleavable molecule to achieve photolysis at low energy. To verify this concept, we chose platinum(II) tetraphenyltetrabenzoporphyrin (PtTPBP) as the photosensitizer and synthesized a boron-dipyrromethene (BODIPY)-based prodrug as the photocleavable molecule. Photolysis of the prodrug is achieved by TTET upon excitation of PtTPBP at 625 nm with a photolysis quantum yield of 2.8%. Another demonstration shows an unexpected higher photolysis quantum yield than the direct excitation at 530 nm. This strategy opens a new path for achieving photolysis at long wavelengths, benefiting the applications in biological studies, photopharmacology, and photoresponsive drug delivery.

Boston type 1 keratoprosthesis for failed keratoplasty.

The purpose of this study was to evaluate the outcomes of the Boston type 1 keratoprosthesis (Kpro-1) in eyes with failed keratoplasty. A retrospective review was performed of every patient treated with a Kpro-1 at a tertiary eye care center between January 1, 2008 and July 1, 2013. Eyes with a failed keratoplasty originally performed for corneal edema, trauma, or keratoconus were included in the statistical analysis. The main outcome measures were visual outcome, prosthesis retention, and postoperative complications. Twenty-four eyes met the inclusion criteria, including 13 eyes with corneal edema, 8 eyes with trauma, and 3 eyes with keratoconus. After a mean follow-up period of 28.9 months (range 7-63 months), the median best corrected visual acuity (BCVA) was 20/125. The BCVA was ≥ 20/40 in 4 (16.7 %) eyes, ≥ 20/70 in 9 (37.5 %) eyes, and ≥ 20/200 in 14 (58.3 %) eyes. Overall, the postoperative BCVA improved in 17 (70.9 %) eyes, was unchanged in 3 (12.5 %) eyes, and was worse in 4 (16.7 %) eyes. The initial Kpro-1 was retained in 22 (91.7 %) eyes, and was successfully repeated in the other 2 eyes. One or more serious prosthesis- or sight-threatening complications occurred in 8 (33.3 %) eyes. These included 1 case of wound dehiscence leading to prosthesis extrusion, 1 case of fungal keratitis leading to prosthesis extrusion, 4 cases of endophthalmitis, and 5 retinal detachments. The Boston Kpro-1 is associated with an excellent prognosis for prosthesis retention and satisfactory visual improvement in eyes with previous failed keratoplasty.

A combined experimental and computational study of the catalytic dehydration of glycerol on microporous zeolites: an investigation of the reaction mechanism and acrolein selectivity.

The catalytic activity and the acrolein selectivity for liquid phase glycerol dehydration on ß zeolites (HNa-ß-k) were found to be dependent on the reaction temperature as well as on the amount of acid sites on the zeolites. An increase in the reaction temperature favors the acrolein selectivity. The acrolein selectivity increases with the Na(+)/H(+) ratio and the glycerol conversion decreases with it so that a maximum acrolein yield is obtained when a certain amount of acidic sites are replaced by non-active Na(+) sites. The computational results indicate that 3-hydoxylpropanal (HPA) is an important intermediate that determines the final product selectivity. The relative rates of the different reaction pathways for HAP can be affected by the amount of water molecules involved in its homogeneous reaction. Based on the reaction mechanism proposed, it was hypothesized that smaller pores reduce activity but increase selectivity to acrolein, and results of the H-MFI zeolite were consistent with this hypothesis. Our work provides important insight into the overall landscape of the reaction mechanism and can be used to help design reaction systems that have good acrolein selectivity for the liquid phase glycerol dehydration reactions.

Stimulated emission in ZnO nanostructures: A time-resolved study.

Stimulated emission was studied using time-integrated and time-resolved photoluminescence in ZnO comb, tetrapod, and rod nanostructures. All the measurements were performed on ensembles of the nanostructures. The nanostructures were fabricated by vapor deposition (combs, tetrapods) and hydrothermal methods (rods). While stimulated emission was detected in all of the nanostructures, significant differences in the behavior of the stimulated emission, as well as the lasing threshold power, were found for different morphologies. The differences in the time evolution of the lasing spectra were particularly pronounced. The observed differences in the stimulated emission spectra of the three types of nanostructures in both exciton-exciton scattering and electron-hole plasma regimes are discussed.

Boston Type 1 Keratoprosthesis for Iridocorneal Endothelial Syndromes.

PURPOSE: To evaluate the outcome of the Boston type 1 keratoprosthesis (KPro-1) in eyes with iridocorneal endothelial syndromes and failed keratoplasties. METHODS: A retrospective review was performed of every eye with a history of iridocorneal endothelial syndrome and a failed corneal transplant that was treated with a KPro-1 at a tertiary eye care center between January 1, 2008, and July 1, 2014. The main outcome measures were visual outcome, prosthesis retention, and postoperative complications. RESULTS: Four eyes met the inclusion criteria. Two eyes had essential iris atrophy and 2 eyes had Chandler syndrome. All 4 eyes had failed corneal transplants and successful glaucoma drainage devices. The mean patient age at the time of KPro-1 surgery was 68.3 years (range, 60-80 years). The mean postoperative follow-up duration was 47 months (range, 27-69 months). Preoperatively, the best-corrected visual acuity (BCVA) was worse than 20/200 in all 4 eyes, including 2 eyes that had hand motions vision. After KPro-1, all 4 eyes initially obtained a BCVA of ≥20/70. At the most recent examination, the BCVA was still ≥20/100 in 3 eyes. The KPro-1 device was retained in all 4 eyes. Postoperative complications included glaucoma progression (1 eye), a retroprosthetic membrane (1 eye), and sterile vitritis (1 eye). CONCLUSIONS: The Boston KPro-1 may offer a better prognosis than repeat traditional keratoplasty in reestablishing corneal clarity in eyes with iridocorneal endothelial syndromes. Despite anatomic success, visual rehabilitation may be compromised by preexisting glaucomatous optic neuropathy and its postoperative progression.

Physical properties of octenyl succinic anhydride modified rice, wheat, and potato starches.

The physical properties of octenyl succinic anhydride (OSA) starches prepared from rice, wheat, and potato starches were studied. Rice and wheat OSA starches had significantly higher peak viscosity (PV), hot paste viscosity (HPV), and cool paste viscosity (CPV), but potato OSA starch had only significantly higher CPV, relative to the native starch. The gel hardness was higher with lower degree of substitution (DS) but lower with higher DS OSA compared to native starch. The swelling volumes (SV) of rice and wheat OSA starches were significantly higher compared to native starch, but the SV of potato OSA starch was slightly lower at high DS. The gelatinization temperature (GT) of rice OSA starches was sharply lower at low DS; for wheat OSA starch it was slightly lower even at high DS, but potato OSA starches had higher GT than the native starch. The enthalpy of all the OSA starches decreased gradually with increased DS. This study showed that the magnitude of changes in physical properties of OSA-modified starches depends not only on their DS but also on the botanical origin of the native starches.

Boston type 1 keratoprosthesis for chemical and thermal injury.

PURPOSE: To evaluate the outcome of the Boston type 1 keratoprosthesis (Kpro-1) in eyes with failed interventions for chemical and thermal injury. METHODS: A retrospective review was performed of every eye with chemical or thermal injury that was treated with a Kpro-1 at a tertiary eye care center between January 1, 2008 and July 1, 2013. The main outcome measures were visual outcome, prosthesis retention, and postoperative complications. RESULTS: Nine eyes met the inclusion criteria, including 7 eyes with alkali burns, 1 eye with an acid burn, and 1 eye with a thermal burn. After a mean follow-up of 40.7 months (range, 29-60 months), the median best-corrected visual acuity was 20/60 (range, 20/15 to no light perception). One eye was ≥20/20, 3 eyes were ≥20/40, and 6 eyes were ≥20/70. The initial Kpro-1 prosthesis was retained in 7 (77.7%) eyes and successfully replaced in the other 2 eyes. One or more serious complications occurred in 6 (66.7%) eyes. These included 2 cases of sterile corneal ulceration with prosthesis extrusion, 2 cases of microbial keratitis (1 bacterial and 1 fungal), 2 cases of bacterial endophthalmitis, and 2 cases of retinal detachments. These complications contributed to visual outcomes of hand motions in 2 eyes and no light perception in 1 eye. CONCLUSIONS: The Boston Kpro-1 is associated with highly satisfactory visual outcomes and prosthesis retention in most cases of severe chemical or thermal injury. Serious complications are common and may compromise the final outcome.

Which approach to anticoagulation management is best? Illustration of an interactive mathematical model to support informed decision making.

BACKGROUND: Among patients with atrial fibrillation or mechanical heart valves, determining the best approach to oral anticoagulation largely depends on comparing the costs of anticoagulation management with the costs of events (thromboembolism and bleeding) averted. The Anticoagulation Management Event/Cost Model (ACME) is an interactive mathematical model intended to help clarify these trade-offs. METHODS: The ACME is a series of linked, nested spreadsheets. At the least detailed level, the user specifies the percentage of patients falling into various management strategies (no anticoagulation, usual physician care, anticoagulation service, patient self-testing/self-management), and the ACME estimates event rates and costs. At more detailed levels the ACME performs a series of weighted average calculations combining, for example, utilization times unit price. Cost categories are divided into event-related and management-related costs (costs of management, testing, and medication). RESULTS: Regardless of how anticoagulation is subsequently managed, perhaps the greatest benefit is obtained by moving patients who are not currently receiving anticoagulation onto warfarin. Additional benefits can be obtained by eliminating outliers (extremely high or extremely low anticoagulation levels). If changing to a more intensive approach also serves to reduce the tendency for physicians to prescribe anticoagulate below the optimal range, additional savings can be anticipated. The cost calculation typically involves a trade-off between increased up-front costs of anticoagulation management versus greater down-line savings associated with a decreased number of events. To assess the quality of anticoagulation within a given organization, it is critical to know the distribution of clotting levels for the population under anticoagulation. CONCLUSIONS: Interactive mathematical models, if sufficiently well documented, can be helpful in clarifying decisions regarding costs and benefits of various methods of anticoagulation.

Photoreactions of 3-diazo-3H-benzofuran-2-one; dimerization and hydrolysis of its primary photoproduct, a quinonoid cumulenone: a study by time-resolved optical and infrared spectroscopy.

Light-induced deazotization of 3-diazo-3H-benzofuran-2-one (1) in solution is accompanied by facile (CO)-O bond cleavage yielding 6-(oxoethenylidene)-2,4-cyclohexadien-1-one (3), which appears with a rise time of 28 ps. The expected Wolff-rearrangement product, 7-oxabicyclo[4.2.0]octa-1,3,5-trien-8-ylidenemethanone (4), is not formed. The efficient light-induced formation of the quinonoid cumulenone 3 opens the way to determine the reactivity of a cumulenone in solution. The reaction kinetics of 3 were monitored by nanosecond flash photolysis with optical (lambda(max) approximately 460 nm) as well as Raman (1526 cm(-1)) and IR detection (2050 cm(-)(1)). Remarkably, the reactivity of 3 is that expected from its valence isomer, the cyclic carbene 3H-benzofuran-2-one-3-ylidene, 2. In aqueous solution, acid-catalyzed addition of water forms the lactone 3-hydroxy-3H-benzofuran-2-one (5). The reaction is initiated by protonation of the cumulenone on its beta-carbon atom. In hexane, cumulenone 3 dimerizes to isoxindigo ((E)-[3,3']bibenzofuranylidene-2,2'-dione, 7), coumestan (6H-benzofuro[3,2-c][1]benzopyran-6-one, 8), and a small amount of dibenzonaphthyrone ([1]benzopyrano[4,3-][1]benzopyran-5,11-dione, 9) at a nearly diffusion-controlled rate. Ab initio calculations (G3) are consistent with the observed data. Carbene 2 is predicted to have a singlet ground state, which undergoes very facile, strongly exothermic (irreversible) ring opening to the cumulenone 3. The calculated barrier to formation of 4 (Wolff-rearrangement) is prohibitive. DFT calculations indicate that protonation of 3 on the beta-carbon is accompanied by cyclization to the protonated carbene 2H(+), and that dimerization of 3 to 7 and 9 takes place in a single step with negligible activation energy.