Photophysical Properties of Donor-Acceptor Stenhouse Adducts and Their Inclusion Complexes with Cyclodextrins and Cucurbit[7]uril.

Donor-acceptor Stenhouse adducts (DASAs) are a novel class of solvatochromic photoswitches with increasing importance in photochemistry. Known for their reversibility between open triene and closed cyclized states, these push-pull molecules are applicable in a suite of light-controlled applications. Recent works have sought to understand the DASA photoswitching mechanism and reactive state, as DASAs are vulnerable to irreversible "dark switching" in polar protic solvents.

Ultrafast ring-opening and solvent-dependent product relaxation of photochromic spironaphthopyran.

The ultrafast dynamics of unsubstituted spironaphthopyran (SNP) were investigated using femtosecond transient UV and visible absorption spectroscopy in three different solvents and by semi-classical nuclear dynamics simulations. The primary ring-opening of the pyran unit was found to occur in 300 fs yielding a non-planar intermediate in the first singlet excited state (S1). Subsequent planarisation and relaxation to the product ground state proceed through barrier crossing on the S1 potential energy surface (PES) and take place within 1.

Photochromism of Amphiphilic Dithienylethenes as Langmuir-Schaefer Films.

Surface pressure-area isotherms were recorded under different irradiation conditions for single-component Langmuir films of three photochromic amphiphilic dithienylethenes. Nonirradiated films of these photochromic amphiphiles were mechanically stable. In addition, a shift of the isotherms to larger mean molecular areas was observed for films prepared from UV-light-irradiated dithienylethenes.

Molecular Design Principles for Near-Infrared Absorbing and Emitting Indolizine Dyes.

Desirable components for dye-sensitzed solar cell (DSC) sensitizers and fluorescent imaging dyes include strong donating building blocks coupled with well-balanced acceptor functionalities for absorption beyond the visible range. We have evaluated the effects of increasing acceptor strengths and incorporation of dye morphology controlling groups on molar absorptivity and absorption breadth with indolizine donor-based dyes. Indolizine-based D-A and D-π-A sensitizers incorporating bis-rhodanine, tricyanofuran (TCF), and cyanoacrylic acid functionalities were analyzed for performance in DSC devices.

Donor-Acceptor-Donor Thienopyrazines via Pd-Catalyzed C-H Activation as NIR Fluorescent Materials.

A series of thienopyrazine-based donor-acceptor-donor (D-A-D) near-infrared (NIR) fluorescent compounds were synthesized through a rapid, palladium-catalyzed C-H activation route. The dyes were studied through computational analysis, electrochemical properties analysis, and characterization of their photophysical properties. Large Stokes shifts of approximately 175 nm were observed, which led to near-infrared emission.

Laser-Limited Signatures of Quantum Coherence.

Quantum coherence is proclaimed to promote efficient energy collection by light-harvesting complexes and prototype organic photovoltaics. However, supporting spectroscopic studies are hindered by the problem of distinguishing between the excited state and ground state origin of coherent spectral transients. Coherence amplitude maps, which systematically represent quantum beats observable in two-dimensional (2D) spectroscopy, are currently the prevalent tool for making this distinction.

Photocontrol of ion permeation in lipid vesicles with (bola)amphiphilic spirooxazines.

Three (bola)amphiphilic spirooxazines have been synthesized and their photochromism has been characterized. The large biphotochromic structure of 2 significantly affects its conformational flexibility and the rate constants for thermal ring closure are particularly dependent on the lipid phase state. Two comprehensive ion permeation studies were performed to examine the effect of spirooxazine inclusion and isomerization on membrane permeability.

Photocontrol of ion permeation in lipid vesicles with amphiphilic dithienylethenes.

The integration of photochromic dithienylethenes (DTEs) with lipid vesicles as photoresponsive membrane disruptors for ion transport applications has been examined. We have synthesized three amphiphilic DTEs 1-3 that incorporate a terminally charged alkyl chain, and contain methyl or phenylethynyl substituents at the reactive carbons. Our photochromic reactivity studies suggest that the inclusion of a single alkyl chain favors the photoactive antiparallel conformation of DTEs, given the significant improvement in the cyclization quantum yield over previous phenylethynyl derivatives.

Two-dimensional spectroscopy of a molecular dimer unveils the effects of vibronic coupling on exciton coherences.

The observation of persistent oscillatory signals in multidimensional spectra of protein-pigment complexes has spurred a debate on the role of coherence-assisted electronic energy transfer as a key operating principle in photosynthesis. Vibronic coupling has recently been proposed as an explanation for the long lifetime of the observed spectral beatings. However, photosynthetic systems are inherently complicated, and tractable studies on simple molecular compounds are needed to fully understand the underlying physics.

Assessing the decontamination efficiency of a three-component flocculating system in the treatment of oilfield-produced water.

Produced water is a complex mixture of oil, water, dissolved solids, and suspended solids. It represents the largest volume of waste associated with the oil and gas industry, and its management is a costly aspect of oil recovery. Therefore, the development of effective treatment technologies for produced water is essential from both ecological and economic standpoints.

Interruption of agitation of platelet concentrates: a multicenter in vitro study by the BEST Collaborative on the effects of shipping platelets.

Background: Transported platelets (PLTs) are not under continuous agitation. The aim of this study was to determine whether PLTs shipped between 24 and 48 hours would be able to maintain a pH(22 degrees C) value of 6.5 at the end of 7 days of storage.

In vitro pH effects on in vivo recovery and survival of platelets: an analysis by the BEST Collaborative.

Background: The pH environment of stored platelet (PLT) products is recognized as an important factor and is generally used as a key surrogate measure of PLT viability. It is the only in vitro measurement that has been translated into industry standards and regulatory rules or specifications for storage of PLT products. The objective of this study was to evaluate the effect of in vitro pH on the in vivo recovery and survival of autologous PLT products.

A critical comparison of platelet preparation methods.

Purpose Of Review: Platelet concentrates may be prepared from whole blood or by plateletpheresis. Currently, the non-evidence-based preponderance of apheresis units in the United States and the 50: 50 ratio in Europe may not optimize the gifts of whole-blood donors or minimize healthcare costs. Post-storage pooled, whole-blood-derived platelets, on the other hand, do not provide the convenience of or an equivalent level of safety as apheresis platelets.

Reevaluation of the resting time period when preparing whole blood-derived platelet concentrates with the platelet-rich plasma method.

Background: The resting of platelet (PLT) pellets during the preparation of whole blood-derived PLT concentrates (PCs) is considered an essential step. A reevaluation of the rest period was conducted because preparation and storage conditions have been modified during the past 20 years.

Study Design And Methods: A two-site in vitro study (Study 1) was conducted with rest times of 0 to 5 minutes, 1 hour, and 4 hours (n = 31-33 per rest period).

Platelet dose consistency and its effect on the number of platelet transfusions for support of thrombocytopenia: an analysis of the SPRINT trial of platelets photochemically treated with amotosalen HCl and ultraviolet A light.

Background: The SPRINT trial examined efficacy and safety of photochemically treated (PCT) platelets (PLTs). PCT PLTs were equivalent to untreated (control) PLTs for prevention of bleeding. Transfused PLT dose and corrected count increments (CIs), however, were lower and transfusion intervals were shorter for PCT PLTs, resulting in more PCT than control transfusions.

The influence of various hematology analyzers on component platelet counts.

Hematology analyzers designed to count platelets in samples of whole blood are used to enumerate the total number of platelets in components prepared for transfusion. This report addresses the issue of variability in platelet counts obtained with different models of hematology analyzers. The influence of a common calibration procedure, involving one level of porcine platelets, on the extent of variability was also evaluated.

Improving technology for collecting platelets by apheresis: five-year experience in one blood center.

Over the past decade, newly introduced methods for apheresis platelet collection have led to increased collection yields. This has resulted in "splitting," which allows transfusion of 2 patients from 1 high-yield collection. Although many small studies exist, no large studies have described the impact of methodological changes on routine blood center collections.

White particulate matter: report of the ad hoc industry review group.

Background: In January 2003, blood center personnel in the American Red Cross, Southern Region in Atlanta, noticed whitish particulate material (WPM) that had not been observed previously in several units of red blood cells (RBCs). An expert panel was formed to evaluate studies of the material and make appropriate recommendations

Study Design And Methods: The expert panel reviewed information provided by several investigations and organizations. This included: background information, and experiences relating to WPM; WPM composition; factors promoting WPM formation; risk of WPM (if any) to patients; and recommendations to prevent future occurrences.

Therapeutic efficacy and safety of platelets treated with a photochemical process for pathogen inactivation: the SPRINT Trial.

We report a transfusion trial of platelets photochemically treated for pathogen inactivation using the synthetic psoralen amotosalen HCl. Patients with thrombocytopenia were randomly assigned to receive either photochemically treated (PCT) or conventional (control) platelets for up to 28 days. The primary end point was the proportion of patients with World Health Organization (WHO) grade 2 bleeding during the period of platelet support.