Large Inverted Singlet-Triplet Energy Gaps Are Not Always Favorable for Triplet Harvesting: Vibronic Coupling Drives the (Reverse) Intersystem Crossing in Heptazine Derivatives.

Heptazine derivatives are promising dopants for electroluminescent devices. Recent studies raised the question whether heptazines exhibit a small regular or an inverted singlet-triplet (IST) gap. It was argued that the S ← T reverse intersystem crossing (RISC) is a downhill process in IST emitters and therefore does not require thermal activation, thus enabling efficient harvesting of triplet excitons.

Internal conversion of singlet and triplet states employing numerical DFT/MRCI derivative couplings: Implementation, tests, and application to xanthone.

We present an efficient implementation of nonadiabatic coupling matrix elements (NACMEs) for density functional theory/multireference configuration interaction (DFT/MRCI) wave functions of singlet and triplet multiplicity and an extension of the Vibes program that allows us to determine rate constants for internal conversion (IC) in addition to intersystem crossing (ISC) nonradiative transitions. Following the suggestion of Plasser et al. [J.

Acridones: Strongly Emissive HIGHrISC Fluorophores.

An acridone derivative (-methyl-difluoro-acridone, NMA-dF) is characterized with respect to its utility as an emitter in organic light emitting diodes (OLEDs). Using steady-state and time-resolved spectroscopy as well as quantum chemistry, its ability to convert singlet and triplet excitons into light was scrutinized. NMA-dF emits in the deep blue range of the visible spectrum.

Visible Light-Induced Homolytic Cleavage of Perfluoroalkyl Iodides Mediated by Phosphines.

In an effort to explain the experimentally observed variation of the photocatalytic activity of t Bu 3 P, n Bu 3 P and (MeO) 3 P in the blue-light regime [Helmecke et al., Org. Lett.

Impact of fluorination on the photophysics of the flavin chromophore: a quantum chemical perspective.

10-Methylisoalloxazine (MIA) and its mono-fluorinated derivatives (6-9F-MIA) were investigated by means of quantum chemistry, looking into the influence of fluorination on fluorescence, absorption and inter-system crossing (ISC). A maximized fluorescence quantum yield (ΦFl) of this chromophore is desirable for application as a potential fluorescence marker in biodiagnostics/photobiological studies. An enhanced triplet quantum yield ΦT on the other hand may open a perspective for photodynamic therapies (PDT) in cancer treatment.

Use of natriuretic peptides in pre-participation screening of college athletes.

Current screening methods have poor specificity and sensitivity for detecting cardiac abnormalities that predispose young athletes to sudden death. Natriuretic peptides (NPs) show promise in screening asymptomatic populations for structural heart disease, but little is known about their use in student athletes. This study sought to describe the distribution and characteristics of NP levels in a population of college athletes and determine the relationship between NPs and the pre-participation exam (PPE) and hand-held echocardiography (HHE).

Efficacy of transdermal ketoprofen for delayed onset muscle soreness.

Objective: To determine the efficacy of transdermal ketoprofen in reducing delayed-onset muscle soreness (DOMS), limiting systemic absorption, and improving postexercise function following repetitive muscle contraction.

Design: Double-blind, placebo-controlled clinical trial.

Setting: OrthoMed, University of California at San Diego, La Jolla, CA, U.

Using an experimental bicycle seat to reduce perineal numbness.

Researchers evaluated the effectiveness of an experimental seat that was designed to prevent perineal numbness and possibly erectile dysfunction in male bicyclists. A trial of the device among 15 experienced cyclists measured perineal sensation after a 1-hour stationary cycling session on a standard seat followed several days later by the same exercise protocol on the experimental bike seat. Cyclists reported more numbness with the standard seat than with the experimental seat (79% vs 14%).

How to get the most out of bone densitometry. Results can help assess fracture risk and guide therapy.

Bone densitometry has well-established usefulness in assessing fracture risk. Anyone with a condition that might reduce bone mass or accelerate bone loss should undergo testing, as should postmenopausal women and perimenopausal women who are undecided about starting estrogen replacement therapy. When stratifying a patient's risk of fracture, clinicians should consider not only BMD but also age, lifestyle, concurrent illness, and family history.

Morbidity and mortality in the wilderness.

The medical literature is limited regarding current wilderness morbidity and mortality statistics. Available studies concentrate on selected wilderness activities. This study retrospectively examines wilderness injuries, illnesses, and mortality based on case incident report files from eight National Park Service parks within California over a three-year period.

Risk factors associated with stress reactions in female Marines.

Women have a higher stress fracture rate than men in military studies, although the exact cause of this is not clear. Hyperpronation has been implicated as a potential risk factor for injury. In this prospective observational study, we measured subtalar joint range of motion in 101 women (ages 20-27 years) enrolled in Marine Corps Officer Candidate School in June 1994.

The numb arm and hand.

Trauma and compression along the course of the median, ulnar or radial nerve from the brachial plexus to the fingers may cause pain, weakness, numbness or tingling of the upper extremity. Diabetes, smoking, alcohol consumption, rheumatoid arthritis and hypothyroidism are risk factors for nerve entrapment, although these disorders typically produce bilateral symptoms. Carpal tunnel syndrome, the most common nerve entrapment condition, results from median nerve compression at the wrist.

Spinal bone loss in postmenopausal women supplemented with calcium and trace minerals.

The effects of calcium supplementation (as calcium citrate malate, 1000 mg elemental Ca/d) with and without the addition of zinc (15.0 mg/d), manganese (5.0 mg/d) and copper (2.

Coagulopathy presenting as calf pain in a racquetball player.

Most cases of lower leg pain in athletes result from musculoskeletal injury. Occasionally these patients do not respond to treatment in a timely fashion. This should alert the clinician to rethink the original diagnosis and consider more unusual causes of leg pain.

Acute injuries from mountain biking.

We questioned members of 2 southern California off-road bicycling organizations about injuries associated with the use of all-terrain bicycles. Cyclists were asked about riding and safety habits, the kind(s) of injury sustained with their most recent accident and whether they sought medical treatment, and the circumstances of the accident. Of 459 mailed surveys, 268 (58.

Effects of a preventive cardiology curriculum on behavioral cardiovascular risk factors and knowledge of medical students.

We evaluated a Preventive Cardiology Academic Award (PCAA) program designed to integrate preventive cardiology concepts into the medical school curriculum. Diet, preventive cardiology knowledge, preventive cardiology attitudes, exercise behavior, and body mass index were compared at entrance to medical school and during the graduation year. Complete data were available on 94 students (65 men and 29 women).

Cardiovascular risk factor assessment of medical students as an educational tool.

For three consecutive years, beginning in 1986, we evaluated cardiovascular disease (CVD) risk factors of medical students as part of the teaching program in a Preventive Cardiology Academic Award. Entering students in three consecutive classes were screened on the first day of orientation to medical school. The first year, we evaluated 108 students (71 men and 37 women), the second year, 99 students (75 men, 24 women), and the third year 108 students (67 men and 41 women).

Environmental and thermal injury.

The environment can have a profound impact on human performance. Over the past decade there has been considerable interest in the scientific study of the human ability of to protect oneself against heat and cold. This new knowledge has led to a better understanding of physiology and resulted in better prevention, recognition, and treatment of hyperthermia, hypothermia, and frostbite.

Spinal bone density and calcium intake in healthy postmenopausal women.

Dietary calcium intake and bone mineral density (BMD) of the lumbar spine (L2-L4) were determined in 131 healthy free-living postmenopausal women (aged 64.7 +/- 7.6 y, means +/- SD).

Chronic Shoulder Pain in a Volleyball Player.

In brief A high school girl had pain in her right shoulder when she played volleyball. X-rays revealed the cause: diffuse multiple loose calcifications throughout the synovium of the shoulder. The calcifications were removed arthroscopically, and a partial synovectomy of the shoulder joint was performed.

Long-term estrogen replacement therapy in postmenopausal women sustains vertebral bone mineral density.

The cross-sectional relationship between long-term estrogen use and vertebral (L2-4) bone mineral density (BMD) was determined in 65 postmenopausal white women between 55 and 75 years who were at least 10 years from their menopause. Long-term estrogen users began therapy within 5 years of menopause and continued for a duration of at least 10 years. The mean duration of use was 19.

A comparison of quantitative dual-energy radiographic absorptiometry and dual photon absorptiometry of the lumbar spine in postmenopausal women.

Noninvasive bone densitometry is an important aspect in the detection and management of osteoporosis and other forms of metabolic disease of calcified tissue. A system using quantitative dual-energy digital projection radiography (QDR) of the lumbar spine was systematically tested against dual-photon absorptiometry (DPA) of the lumbar spine in 131 women over 55 years of age and free from major risk factors for osteoporosis. All subjects were scanned by both QDR and DPA under the same conditions.

Hyperthermia: New Thoughts on an Old Problem.

In brief: This article reviews the causes and treatment of the common heat illnesses-heat syncope, heat exhaustion, and exertional heatstroke. The authors discuss the effectiveness of cooling heatstroke victims in ice water vs water that has been cooled to a temperature of 15° C. The latter method is more practical and has been found as effective as cooling with ice water.

First Aid and Management of Rattlesnake Bites (Part 2 of 2).

In brief: Rattlesnake bites are rarely fatal, but prevention is the best treatment. People who live in areas indigenous to rattlesnakes should take routine precautionary measures such as wearing boots and long pants. A person who encounters or is bitten by a snake should get away from it as soon as possible.