Two-dimensional core-shell donor-acceptor assemblies at metal-organic interfaces promoted by surface-mediated charge transfer.

Organic charge transfer (CT) complexes obtained by combining molecular electron donors and acceptors have attracted much interest due to their potential applications in organic opto-electronic devices. In order to work, these systems must have an electronic matching - the highest occupied molecular orbital (HOMO) of the donor must couple with the lowest unoccupied molecular orbital (LUMO) of the acceptor - and a structural matching, so as to allow direct intermolecular CT. Here it is shown that, when molecules are adsorbed on a metal surface, novel molecular organizations driven by surface-mediated CT can appear that have no counterpart in condensed phase non-covalent assemblies of donor and acceptor molecules. By means of scanning tunneling microscopy and spectroscopy it is demonstrated that the electronic and self-assembly properties of an electron acceptor molecule can change dramatically in the presence of an additional molecular species with marked electron donor character, leading to the formation of unprecedented core-shell assemblies. DFT and classical force-field simulations reveal that this is a consequence of charge transfer from the donor to the acceptor molecules mediated by the metallic substrate.

Epitaxial Templating of C60 with a Molecular Monolayer.

Commensurate epitaxial monolayers of truxenone on Cu (111) were employed to template the growth of monolayer and bilayer C60. Through the combination of STM imaging and LEED analysis we have demonstrated that C60 forms a commensurate 8 × 8 overlayer on truxenone/Cu (111). Bilayers of C60 retain the 8 × 8 periodicity of templated monolayers and although Kagome lattice arrangements are observed these are explained with combinations of 8 × 8 symmetry.

Determination of the individual atomic site contribution to the electronic structure of 3,4,9,10-perylene-tetracarboxylic-dianhydride (PTCDA).

We have studied the element and orbital-specific electronic structure of thin films of 3,4,9,10-perylene-tetracarboxylic-dianhydride (PTCDA) using a combination of synchrotron radiation-exited resonant x-ray emission spectroscopy, x-ray absorption spectroscopy, x-ray photoelectron spectroscopy, as well as density functional theory calculations. Resonant and non-resonant x-ray emission spectroscopies were used to measure the C and O 2p partial densities of state in PTCDA. Furthermore, resonant x-ray emission at the C and O K-edges is shown to be able to measure the partial densities of states associated with individual atomic sites. The flat molecular orientation of PTCDA on various substrates is explained in terms of the carbonyl O atom acting as a hydrogen-bond acceptor leading to multiple in-plane intermolecular C=O···H-C hydrogen bonding between carbonyl groups and the perylene core of the neighboring PTCDA molecules. We support this conclusion by comparison of our calculations to measurements of the electronic structure using element-, site-, and orbital-selective C and O K-edge resonant x-ray emission spectroscopy, and photoemission spectroscopy.

Standard of care therapy for malignant glioma and its effect on tumor and stromal cells.

Glioblastoma is the most common and deadly of the primary central nervous system tumors. Recent advances in molecular characterization have subdivided these tumors into at least three main groups. In addition, these tumors are cellularly complex with multiple stromal cell types contributing to the biology of the tumor and treatment response. Because essentially all glioma patients are treated with radiation, various chemotherapies and steroids, the tumor that finally kills them has been modified by these treatments. Most of the investigation of the effects of therapy on these tumors has focused on the glioma cells per se. However, despite the importance of the stromal cells in these tumors, little has been done to understand the effects of treatment on stromal cells and their contribution to disease. Understanding how current standard therapy affects the biology of the tumor and the tumor stroma may provide insight into the mechanisms that are important to the inhibition of tumor growth as well as the biology of recurrent tumors.

Open-cellular organic semiconductor thin films by vertical co-deposition using sub-100 nm nanosphere templates.

Vertical co-deposition of sub-100 nm polystyrene sphere templates with water-soluble small molecule or polymeric semiconductors, followed by solvent vapour assisted sphere removal, is shown to be an excellent method for generating porous large area organic semiconductor thin films with sub-100 nm open-cellular networks, with numerous potential applications in areas such as sensing and photovoltaics.

Using HapMap tools in pharmacogenomic discovery: the thiopurine methyltransferase polymorphism.

One purpose of the International HapMap Project is to provide a genome-wide resource to discover pharmacogenetic determinants of drug response. The thiopurine methyltransferase (TPMT) 719A>G single-nucleotide polymorphism (SNP) causes decreased TPMT activity, increased intracellular thiopurines, and drug toxicities. Using HapMap cell lines and 3.3 million SNPs, we tested whether the TPMT 719A>G SNP could be identified as predicting TPMT phenotype. Assuming TPMT was a candidate gene, five SNPs and four haplotypes predicted TPMT phenotype, two of which were in complete linkage disequilibrium with the functional 719A>G SNP. We also used a genome-wide approach to rank all 17,542 genes as predictors of TPMT activity. A TPMT haplotype, HAP1, significantly predicted TPMT phenotype; however, haplotypes of 96 genes ranked higher than TPMT. Our findings show that HapMap resources are useful for pharmacogenetic discovery when the candidate gene is known, but challenges remain for definitive gene identification when a genome-wide agnostic approach is employed.

Photophysics of PTCDA and Me-PTCDI thin films: effects of growth temperature.

The effect of deposition temperature on the photophysical properties of 3,4,9,10-perylenetetracarboxylic dianhydride (PTCDA) and N,N'-dimethylperylene-3,4,9,10-bis(dicarboximide) (Me-PTCDI) films is investigated with steady-state and time-resolved spectroscopy. Atomic force microscopy (AFM) images of the film surfaces show an increase in the dimensions of crystallites with substrate temperature, culminating in the formation of elongated crystallites on substrates held close to the sublimation temperature. In contrast, despite an improvement in the crystal quality, X-ray diffraction (XRD) studies indicate that the substrate temperature has a negligible effect on the molecular orientation; the PTCDA and Me-PTCDI molecules align parallel and tilted to the substrate surface, respectively. Both materials exhibit characteristic absorption, due to mixing between charge-transfer and Frenkel species, and broad structureless photoluminescence. Growth at elevated temperatures gives rise to increased low-energy absorption, attributed to the formation of charge-transfer species, and enhanced blue-shifted emission, although the effects are less pronounced for Me-PTCDI. Time-correlated single-photon counting data indicate that the enhancement coincides with a lengthening of the fluorescence decays, over the whole emission spectrum.

Charge recombination in CuPc/PTCDA thin films.

The recombination kinetics of photogenerated charge carriers in perylene-3, 4, 9, 10-tetracarboxylic dianhydride (PTCDA) and copper phthalocyanine (CuPc) thin films grown by organic molecular beam deposition have been studied using transient absorption spectroscopy. Optical excitation is observed to generate long-lived polaron states, which exhibit power law recombination dynamics on time scales from microseconds to milliseconds. Studies as a function of excitation density and temperature, and comparison between heterostructures and PTCDA single layers, all indicate that this power law behavior results from trapping of PTCDA- polarons in localized states, with an estimated trap state density of approximately 6 x 10(17) polarons cm(-3). This recombination behavior is found to be remarkably similar to that previously observed for polymer/fullerene blends, suggesting that it may be generic to a range of semiconducting materials.

First report of human immunodeficiency virus transmission via an RNA-screened blood donation.

BACKGROUND AND OBJECTIVES: Blood banks in the USA have recently introduced minipool nucleic acid amplification testing (MP-NAT) of blood products to reduce the transmission of human immunodeficiency virus (HIV) and hepatitis C virus (HCV) by transfusions. However, MP-NAT is limited in its ability to detect preseroconversion samples with very low viral RNA loads. MATERIALS AND METHODS: To determine whether a red blood cell unit, from an MP-NAT-negative donation, transmitted HIV when transfused to a patient, we compared the viral sequences from the blood donor and recipient. The implicated donation was also tested by commercially available NAT assays at a range of dilution factors to determine whether the infectious unit could have been detected using individual-donation NAT (ID-NAT). RESULTS: Phylogenetic linkage of HIV sequences in the blood donor and recipient confirmed the transmission of HIV by blood transfusion, the first such case identified since introduction of MP-NAT screening in 1999. Viral RNA was reliably detected by ID-NAT, but only inconsistently detected by MP-NAT. CONCLUSIONS: Even following the introduction of MP-NAT, a preseroconversion donation with a viral load of

Syringe laws and pharmacy regulations are structural constraints on HIV prevention in the US.

OBJECTIVE: To review the legal and regulatory barriers that restrict pharmacy sales of syringes to injection drug users (IDUs) and to discuss how reducing these barriers can facilitate access to sterile syringes for IDUs and improve HIV prevention. BACKGROUND: IDUs' access to sterile syringes from community pharmacies in the United States is limited by state laws and regulations governing syringe sales. Restricted availability of sterile syringes from pharmacies is a structural barrier that greatly impedes HIV prevention for IDUs, who often share and reuse syringes because they cannot obtain and possess sterile syringes. These high-risk behaviors contribute to the transmission of HIV and other blood-borne pathogens among IDUs, their sexual partners, and their children. STATE EXPERIENCES: In Connecticut, because of high HIV prevalence among IDUs, restrictive syringe laws were changed. After the legal changes in Connecticut, both pharmacy sales of syringes in areas of high drug use and purchases of syringes in pharmacies (reported by IDUs) increased, while syringe sharing (reported by IDUs) decreased. Maine and Minnesota have made similar changes in laws. CONCLUSIONS: Increasing access to sterile syringes through pharmacies requires the repeal or modification of legal barriers. Pharmacy sale of syringes to IDUs is an inexpensive HIV prevention intervention with the potential to substantially reduce HIV transmission. Further studies are needed to document how changes to legal barriers can influence HIV prevention for IDUs.

Syringe disposal options for injection drug users: a community-based perspective.

This study was a qualitative exploration of syringe disposal interventions for injection drug users (IDUs). Data were collected through in-depth interviews with 26 community members who injected drugs and 32 noninjecting community members in Atlanta, Georgia. Both groups supported syringe exchange programs as syringe disposal interventions, while noninjecting community members favored a one-way drop box. IDUs identified fear of arrest for possession of syringes as the most salient barrier to safe syringe disposal, revealing the negative consequences of drug paraphernalia laws.

Prevalence of sexual and drug-related HIV risk behaviors in the U.S. adult population: results of the 1996 National Household Survey on Drug Abuse.

CONTEXT: Data on the prevalence of HIV risk behavior that are representative of the general population are needed to help evaluate the effectiveness of prevention programs. OBJECTIVE: To use data from a large national interview survey to make estimates of the prevalence of sexual and drug-related HIV risk behaviors in the adult population of the United States. DESIGN: Nationally representative cross-sectional survey with in-person interviews collecting information on drug use and sexual behavior. SETTING AND PARTICIPANTS: 12,381 U.S. adults aged between 18 and 59 who were respondents to the 1996 National Household Survey on Drug Abuse, as part of sample of the noninstitutionalized population. Interviews took place in respondents homes using face-to-face interviewer-administered and self-administered questionnaires. RESULTS: In total, 2.8% of respondents were classified as having increased risk for HIV through sexual behavior; this represents 3.9 million persons. 1.7% reported some degree of risk through drug-related behaviors, representing 1.2 million persons. 3.5% of adults (5 million persons) were found to have some degree of HIV risk from sexual or drug-related behavior. Persons who were at risk through drug behavior were much more likely than others to be at risk through sexual behavior. Condom use was not related to HIV risk, although having a recent HIV test was found to be. Among those who reported some behaviors that placed them at increased risk for HIV infection, only 22% used a condom the last time they had sex with a regular partner. CONCLUSIONS: The high rate of sexual risk behavior on the part of drug users suggests increasing condom use for this group should be a priority goal for programs, especially condom use with main partners. Survey work needs to be continued and improved to make it possible to assess the impact of successful local prevention efforts on national rates of HIV risk behavior.

Condom use and HIV risk behaviors among U.S. adults: data from a national survey.

CONTEXT: How much condom use among U.S. adults varies by type of partner or by risk behavior is unclear. Knowledge of such differentials would aid in evaluating the progress being made toward goals for levels of condom use as part of the Healthy People 2000 initiative. METHODS: Data were analyzed from the 1996 National Household Survey of Drug Abuse, an annual household-based probability sample of the noninstitutionalized population aged 12 and older that measures the use of illicit drugs, alcohol and tobacco. The personal behaviors module included 25 questions covering sexual activity in the past year, frequency of condom use in the past year, circumstances of the last sexual encounter and HIV testing. RESULTS: Sixty-two percent of adults reported using a condom at last intercourse outside of an ongoing relationship, while only 19% reported using condoms when the most recent intercourse occurred within a steady relationship. Within ongoing relationships, condom use was highest among respondents who were younger, black, of lower income and from large metropolitan areas. Forty percent of unmarried adults used a condom at last sex, compared with the health objective of 50% for the year 2000. Forty percent of injecting drug users used condoms at last intercourse, compared with the 60% condom use objective for high-risk individuals. Significantly, persons at increased risk for HIV because of their sexual behavior or drug use were not more likely to use condoms than were persons not at increased risk; only 22% used condoms during last intercourse within an ongoing relationship. CONCLUSIONS: Substantial progress has been made toward national goals for increasing condom use. The rates of condom use by individuals at high risk of HIV need to be increased, however, particularly condom use with a steady partner.

PIP: The 1996 US National Household Survey on Drug Abuse obtained information on a comprehensive set of sex- and drug-related HIV risk behaviors. The sample was comprised of 9270 adults 18-59 years of age. A total of 21% of respondents (12.1% of married and 40.4% of unmarried adults) reported condom use in their most recent sexual encounter. Condoms were used by 19% of those whose last sexual intercourse occurred within a relationship compared with 62% of those whose last intercourse occurred outside of a relationship. Condom use in the context of a committed relationship was highest among respondents who were 18-25 years old (36.3%), Black (29.9%), low-income (24.2%), and from large metropolitan areas (21.2%) and among those with 2 or more sexual partners in the past year (35.3%). In contrast, condom use at last intercourse outside of an ongoing relationship was higher among males (65.3%), college graduates (66.2%), residents of the northeastern US (73.9%), those living in large metropolitan areas (68.9%), and those with two or more partners (65.5%). When the type of relationship was controlled, adults with HIV risk factors (homosexual sex, 6 or more partners, sex with HIV-infected persons, exchange of sex for drugs or money, use of illegal injection drugs in the past 3 years, crack cocaine use during the past year) were not significantly more likely to use condoms than those without these risk factors. Among individuals with one or more sex- or drug-related HIV risk factor, 22% used condoms during last intercourse within an ongoing relationship and 59.5% used condoms at last coitus in a casual relationship. Among adults with no such risk factors, these rates were 18.6% and 62.9%, respectively. Adoption of condom use by high-risk individuals must be increased, particularly with steady partners.

HIV risk behaviors associated with the injection process: multiperson use of drug injection equipment and paraphernalia in injection drug user networks.

This study examines drug acquisition and multiperson use of paraphernalia, drugs, and needles/syringes. Ethnographers observed 54 injection episodes in which IDUs were linked by HIV risk behaviors, and developed a typology of higher-risk, lower-risk, and nonsharing-risk networks. Multiperson use of injection paraphernalia or drug solution occurred in most injection events (94%). Serial use of syringes/needles occurred infrequently (14%) relative to "backloading" (37%) and reuse of paraphernalia (cookers 84%, cotton 77%, water 77%). Higher-risk injection networks were characterized by larger size and pooling of resources for drugs. Prevention messages must include avoiding reuse of injection paraphernalia and transfer of drug solution.

A sterile syringe for every drug user injection: how many injections take place annually, and how might pharmacists contribute to syringe distribution?

Our objectives were to estimate the annual number of injections by injection drug users (IDUs) in the United States of America, and to describe the potential role of pharmacists in providing IDUs with a sterile syringe for every injection. We estimated the number of annual injections by IDUs for the United States, selected U.S. states, and selected U.S. cities according to the following formula: number of injections per year = (number of IDUs) x (average number of injections per IDU per day) x 365. Data were obtained from published articles, personal communications with local experts, and selected national databases. We also reviewed published and unpublished studies of pharmacy kits, pharmacist attitudes, and pharmacist practices in the United States and abroad. Between 920 million and 1.7 billion injections by IDUs take place each year in the United States. We estimated 12 million injections per year in San Francisco and >80 million in New York City. A similar number of syringes would be needed to satisfy the goal of a sterile syringe for every injection. Pharmacy-based strategies, including the sale of kits for injection drug use, have provided sterile syringes to IDUs in Europe, Australia, and New Zealand. Modification of laws restricting syringe purchase and possession has led to marked increases in purchase of syringes from pharmacies and reductions in needle-sharing. In conclusion, large numbers of syringes would be required to provide a sterile syringe for every injection, but significant numbers of pharmacists seem to be willing to play a central role in syringe sale and distribution. Outreach programs should emphasize that using a sterile syringe for every injection is the optimal HIV prevention practice for IDUs who cannot or will not stop injecting. Pharmacy-based syringe sale or distribution has the potential to augment current efforts to prevent HIV infection in IDUs, their sex partners, and their children.

Arrests and incarceration of injection drug users for syringe possession in Massachusetts: implications for HIV prevention.

Multiperson use of syringes is a major risk behavior responsible for the spread of HIV-1 among injection drug users (IDUs). In Massachusetts, two laws regulate syringes: one is a prescription law prohibiting possession or purchase of syringes without a prescription, and the other makes it illegal to possess drug paraphernalia, including syringes. In 1993, Massachusetts amended the prescription law to permit the establishment of syringe exchange programs in two cities. Enrolled participants are allowed to possess syringes anywhere in the state, and about 5% of the estimated 40,000 IDUs in Massachusetts are program participants. To understand how HIV prevention efforts with active IDUs may be constrained by the enforcement of laws criminalizing possession of syringes after the amendment in the law, we reviewed data from multiple sources to assess the number of arrests for syringe possession in 10 large cities in Massachusetts to evaluate incarceration rates and lengths of sentences for those convicted of syringe possession and to estimate costs of incarceration for those convicted of syringe possession. At least 824 persons were arrested for syringe possession in 1995. In examining the data on convictions, we found that 417 persons were convicted in 1994 of syringe possession in the absence of other serious charges, and of these, 41.0% were sentenced to incarceration. The average sentence imposed was 5 months (range, 3 days-2 years). Assuming that those convicted serve about two thirds of their sentences, the cost of incarceration was estimated at $1,140,183 excluding costs for arrest, pretrial detention, prosecution, or other costs of enforcement. Costs for incarcerating persons convicted of both syringe and drug possession were not included; the total cost of incarceration of persons convicted of possession of a syringe, with or without other major charges, is probably considerably higher. Had these funds been allocated to pay for drug treatment, 1629 admissions to drug detoxification programs could have been purchased. Retaining drug paraphernalia and syringe prescription laws in Massachusetts may contribute to HIV transmission. These findings support the recommendation of the American Medical Association to modify drug paraphernalia laws so that IDUs can purchase and possess syringes without a prescription.

Injection and syringe sharing among HIV-infected injection drug users: implications for prevention of HIV transmission. Supplement to HIV/AIDS Surveillance Group.

Because HIV-infected injection drug users (IDUs) can transmit HIV infection, we investigated factors associated with sharing of syringes in the past year among IDUs infected with HIV. We analyzed data from an interview survey of 11,757 persons > or = 18 years of age with HIV or AIDS between June 1990 and August 1995 who were reported to 12 state or city health departments in the United States. Of the 1527 persons who had ever shared syringes and reported injecting in the 5 years before the interview, 786 (51%) had injected in the year before interview, and of these, 391 (50%) had shared during that year. IDUs who were aware of their HIV infection for >1 year were less likely to share (43%) than those who were aware of their infection for 1 year or less (65%, adjusted odds ratio=2.15, 95% confidence interval, 1.52-3.03). The only statistically significant time trend was that the proportion of IDUs from Connecticut who shared decreased from 71% in 1992 to 29% in 1995. This trend appears to be related to the 1992 changes in Connecticut laws that allowed purchase and possession of syringes without a prescription. Because many HIV-infected IDUs continue to inject and share, prevention efforts should be aimed at HIV-infected IDUs to prevent transmission of HIV. Early HIV diagnosis and access to sterile syringes may be important methods for reducing syringe sharing by HIV-infected IDUs.