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1.
AIDS Behav ; 28(9): 1-12, 2024 Sep.
Article in English | MEDLINE | ID: mdl-38703339

ABSTRACT

Men who have sex with men (MSM) are at increased risk for certain types of chronic diseases and mental health problems. Despite having extended survival in the highly active antiretroviral therapy (HAART) era, MSM living with HIV contend with aging-related diseases and complications with treatment. Consequent hospitalizations incur high costs, fear, low quality of life, and frailty. Unlike heterosexual men, MSM experience more structural violence and "syndemics" of psychosocial factors that not only accelerate HIV acquisition and transmission risk but also may increase morbidity, leading to greater rates of hospitalization. We aim to examine the impact of "syndemic" psychosocial factors on the incidence of hospitalization among geographically diverse MSM in the US. Participants were 1760 MSM from the Multicenter AIDS Cohort Study (MACS) between 2004 and 2019. We examined the relationship between six psychosocial factors (depression, stimulant use, smoking, heroin use, childhood sexual abuse, and intimate partner violence) and incident hospitalization (admission to a hospital for treatment). We found a positive dose-response relationship between the number of syndemic factors and hospitalization. MSM reporting five or more syndemic factors had over twice the risk of hospitalization compared to MSM without syndemic factors [aRR = 2.14 (95% CI = 1.56, 2.94)]. Psychosocial factors synergistically increased hospitalizations over time. The positive dose-response relationship between the number of syndemic factors and hospitalization and the synergistic effects of these factors underscore the need for interventions that disentangle the syndemics to reduce hospitalization and related costs and improve the quality of life among MSM.


Subject(s)
HIV Infections , Homosexuality, Male , Hospitalization , Humans , Male , Homosexuality, Male/psychology , Homosexuality, Male/statistics & numerical data , Hospitalization/statistics & numerical data , Adult , Middle Aged , HIV Infections/psychology , HIV Infections/epidemiology , Longitudinal Studies , United States/epidemiology , Incidence , Syndemic , Risk Factors , Depression/epidemiology , Depression/psychology , Intimate Partner Violence/psychology , Intimate Partner Violence/statistics & numerical data , HIV Seropositivity/psychology , HIV Seropositivity/epidemiology , Quality of Life , Substance-Related Disorders/epidemiology , Substance-Related Disorders/psychology
2.
J Am Chem Soc ; 145(48): 26472-26476, 2023 Dec 06.
Article in English | MEDLINE | ID: mdl-37975588

ABSTRACT

The selection and design of charge integration methods remain an outstanding challenge in materials chemistry. In complex materials like electrides, this challenge is amplified by the small charge and complex shape of electride wave functions. For these reasons, popular integration methods, such as the Bader method, usually fail to assign any charge to the bare electrons in an electride. To address this challenge, we developed an algorithm that instead partitions the charge based on the electron localization function (ELF), a popular scheme for visualizing chemically important features in molecules and solids. The algorithm uses Bader segmentation of the ELF to find the electride electrons and Voronoi segmentation of the ELF to identify atoms. We apply this method, "BadELF", to the quantification of atomic radii and oxidation states in both ionic compounds and electrides. For ionic compounds, we find that the BadELF method yields radii that agree closely with Shannon crystal radii, while the oxidation states agree closely with the Bader method. When they are applied to electrides, however, only the BadELF algorithm yields chemically meaningful charges. We argue that the BadELF method provides a useful strategy to identify electrides and obtain new insight into their most essential property: the quantity of electrons within them.

3.
Curr HIV/AIDS Rep ; 20(6): 481-486, 2023 Dec.
Article in English | MEDLINE | ID: mdl-38010467

ABSTRACT

PURPOSE OF REVIEW: To explore the intersection of chatbots and HIV prevention and care. Current applications of chatbots in HIV services, the challenges faced, recent advancements, and future research directions are presented and discussed. RECENT FINDINGS: Chatbots facilitate sensitive discussions about HIV thereby promoting prevention and care strategies. Trustworthiness and accuracy of information were identified as primary factors influencing user engagement with chatbots. Additionally, the integration of AI-driven models that process and generate human-like text into chatbots poses both breakthroughs and challenges in terms of privacy, bias, resources, and ethical issues. Chatbots in HIV prevention and care show potential; however, significant work remains in addressing associated ethical and practical concerns. The integration of large language models into chatbots is a promising future direction for their effective deployment in HIV services. Encouraging future research, collaboration among stakeholders, and bold innovative thinking will be pivotal in harnessing the full potential of chatbot interventions.


Subject(s)
HIV Infections , Humans , HIV Infections/prevention & control , Privacy
4.
JNCI Cancer Spectr ; 7(6)2023 Oct 31.
Article in English | MEDLINE | ID: mdl-37982744

ABSTRACT

BACKGROUND: Adolescent and young adult cancer survivors experience mental health challenges, yet little is known about the evolution of these difficulties. This study explored mental health symptoms and utilization among long-term adolescent and young adult cancer survivors. METHODS: Using 30 432 respondents from the 2019 National Health Interview Survey, this study compared adults with a history of adolescent and young adult cancer (diagnosed when patients were between 15 and 39 years of age) to adults without adolescent and young adult cancer. Mental health symptom severity was measured using the Patient Health Questionnaire depression scale and 7-item Generalized Anxiety Disorder questionnaires. Care utilization constituted psychotherapy and mental health medication use. Inverse propensity score weights were used to balance demographics and combined with survey weights. Descriptive statistics, multivariable generalized linear models, and structural equation modeling with 2-sided tests were used for analysis. RESULTS: We compared 639 adolescent and young adult survivors with 29 793 controls. Survivors were, on average, 20.5 years (SE = 0.74) past their cancer diagnosis dates. After adjusting for survey and propensity score weights, adolescent and young adult survivors reported more severe depression (incidence rate ratio = 1.42, 95% confidence interval [CI] = 1.09 to 1.84, P < .01) and anxiety (incidence rate ratio = 1.85, 95% CI = 1.55 to 2.21, P < .001). They were more likely to use psychotherapy (odds ratio = 1.91, 95% CI = 1.16 to 3.17, P < .05) and mental health medications (odds ratio = 1.89, 95% CI = 1.15 to 3.11, P < .05). Time since diagnosis was negatively associated with symptoms and utilization. Structural equation modeling demonstrated mediation of utilization effect by symptom severity. CONCLUSIONS: Adolescent and young adult survivors experience worse mental health in late survivorship, despite small improvements over time. We highlight the importance of survivorship care that addresses the long-term mental health needs of these survivors.


Subject(s)
Cancer Survivors , Mental Disorders , Neoplasms , Humans , Adolescent , Young Adult , Mental Health , Survivors/psychology , Neoplasms/epidemiology , Neoplasms/therapy , Neoplasms/psychology
5.
J Acquir Immune Defic Syndr ; 94(3): 220-226, 2023 11 01.
Article in English | MEDLINE | ID: mdl-37643417

ABSTRACT

INTRODUCTION: Expanding HIV pre-exposure prophylaxis (PrEP) use is key to goals for lowering new HIV infections in the U.S. by 90% between 2022 and 2030. Unfortunately, youth aged 16-24 have the lowest PrEP use of any age group and the highest HIV incidence rates. METHODS: To examine the relationship between HIV seroconversion and PrEP uptake, adherence, and continuity, we used survival analysis and multivariable logistic regression on data of 895 youth at-risk for HIV infection enrolled in Adolescent Trials Network for HIV Medicine protocol 149 in Los Angeles and New Orleans, assessed at 4-month intervals over 24 months. RESULTS: The sample was diverse in race/ethnicity (40% Black, 28% Latine, 20% White). Most participants (79%) were cis-gender gay/bisexual male but also included 7% transgender female and 14% trans masculine and nonbinary youth. Self-reported weekly PrEP adherence was high (98%). Twenty-seven participants acquired HIV during the study. HIV incidence among PrEP users (3.12 per 100 person year [PY]) was higher than those who never used PrEP (2.53/100 PY). The seroconversion incidence was highest among PrEP users with discontinuous use (3.36/100 PY). If oral PrEP users were adherent using 2-monthly long-acting injectables, our estimate suggests 2.06 infections per 100 PY could be averted. CONCLUSIONS: Discontinuous use of PrEP may increase risk of HIV acquisition among youth at higher risk for HIV infection and indications for PrEP. Thus, to realize the promise of PrEP in reducing new HIV infections, reducing clinical burdens for PrEP continuation are warranted.


Subject(s)
Anti-HIV Agents , HIV Infections , HIV Seropositivity , Pre-Exposure Prophylaxis , Transgender Persons , Male , Humans , Adolescent , Female , HIV Infections/epidemiology , HIV Infections/prevention & control , HIV Infections/drug therapy , Incidence , Los Angeles/epidemiology , New Orleans , Anti-HIV Agents/therapeutic use , Homosexuality, Male , HIV Seropositivity/drug therapy , Pre-Exposure Prophylaxis/methods
6.
ChemSusChem ; 16(18): e202300486, 2023 Sep 22.
Article in English | MEDLINE | ID: mdl-37171219

ABSTRACT

Carbon is a ubiquitous additive to enhance the electrical conductivity of battery electrodes. Although carbon is generally assumed to be inert, the poor reversibility seen in some fluoride-ion battery electrodes has not been explained or systematically explored. Here, we utilize the Materials Project database to assess electrode deactivation reactions that result in the formation of a metal carbide. Specifically, we compare the theoretical potentials of MFy reduction to either the corresponding metal M or metal carbide MCx . We find that the formation of MCx is unlikely to be important in anodes that operate at modest reduction potentials, such as those made from electronegative metals like Zn, Sn, or Pb. However, in anodes that operate at extreme reduction potentials, such as alkaline earths or lanthanides, we find that formation of MCx is relevant and can emerge as a mechanism for capacity loss. Thus, side reactions of metals with carbon additives that form metal carbides possibly explain the poor reversibility of lanthanide or alkaline earth metal-based electrode materials. Finally, we highlight that the carbide formation process might be exploited for designing cheap anode systems with improved reversibility.

7.
Alcohol Alcohol ; 58(3): 238-246, 2023 May 09.
Article in English | MEDLINE | ID: mdl-36806545

ABSTRACT

BACKGROUND: To slow the spread of the COVID-19 virus, governments across the globe instituted stay-at-home orders leading to increased stress and social isolation. Not surprisingly, alcohol sales increased during this period. While most studies primarily focused on alcohol consumption among college students or adults, this study investigates alcohol misuse among marginalized youth in the USA. We examined risk factors associated with hazardous alcohol use and binge drinking including risk behaviors, life stressors and demographic characteristics. METHODS: In October 2020, youth living with or at high risk for acquiring human immunodeficiency virus (HIV), participating in community-based research to improve HIV prevention and care, were invited to complete an online survey to assess the impact of the stay-at-home orders on multiple aspects of their daily life. RESULTS: Respondents (n = 478) were on average 23 years old; cisgender (84%), not-heterosexual (86.6%), Latino or Black/African American (73%) and assigned male at birth (83%); 52% reported being employed and 14% reported living with HIV. White participants and those who use drugs had higher odds of hazardous alcohol use and binge drinking, compared with other race categories and non-drug users, respectively. CONCLUSION: Contrary to findings from adult studies, we did not observe an increase in hazardous or binge drinking among youth at risk for HIV. Hazardous alcohol use and binge drinking was more likely among White participants, those who use drugs and those who were hazardous/binge drinkers prior to the COVID-19 lockdown, which points to the importance of identifying and treating youth who misuse alcohol early to prevent future alcohol misuse.


Subject(s)
Alcoholism , Binge Drinking , COVID-19 , HIV Infections , Adult , Infant, Newborn , Humans , Male , Adolescent , Young Adult , Binge Drinking/epidemiology , Binge Drinking/prevention & control , Alcoholism/epidemiology , HIV , Los Angeles/epidemiology , New Orleans , COVID-19/epidemiology , Communicable Disease Control , Ethanol , HIV Infections/epidemiology , HIV Infections/prevention & control
8.
Sci Data ; 10(1): 90, 2023 02 11.
Article in English | MEDLINE | ID: mdl-36774371

ABSTRACT

Although lithium-ion batteries have transformed energy storage, there is a need to develop battery technologies with improved performance. Fluoride-ion batteries (FIBs) may be promising alternatives in part due to their high theoretical energy density and natural elemental abundance. However, electrode materials for FIBs, particularly cathodes, have not been systematically evaluated, limiting rapid progress. Here, we evaluate ternary fluorides from the Materials Project crystal structure database to identify promising cathode materials for FIBs. Structures are further assessed based on stability and whether fluorination/defluorination occurs without unwanted disproportionation reactions. Properties are presented for pairs of fluorinated/defluorinated materials including theoretical energy densities, cost approximations, and bandgaps. We aim to supply a dataset for extracting property and structural trends of ternary fluoride materials that may aid in the discovery of next-generation battery materials.

9.
AIDS Care ; 35(12): 1830-1835, 2023 12.
Article in English | MEDLINE | ID: mdl-36200381

ABSTRACT

Exercise can improve physical and mental health for young people at risk for and with HIV, but prevalence rates remain low. This study explored exercise preferences and barriers among young people at risk for and with HIV, and potential gender differences. A total of 129 participants (66.7% male, mean age = 23.8 [SD = 2.1; range: 19-28], 35.7% Black/African American) at-risk for or with HIV were recruited from a larger study and completed an online survey of exercise preferences and barriers. Overall, participants preferred an exercise program that takes place at a fitness center, occurs alone, has a coach/instructor present, is between 30 and 60 minutes, lasts longer than 8 weeks, and includes aerobic and resistance exercises. The fatiguing nature of exercise and cost were common barriers among all genders. Few gender differences emerged. These results should be used to design exercise programs for young adults at risk for and with HIV.


Subject(s)
Exercise , HIV Infections , Adolescent , Adult , Female , Humans , Male , Young Adult , Exercise/psychology , Exercise Therapy , Fatigue , HIV Infections/psychology
10.
R I Med J (2013) ; 105(7): 27-30, 2022 Sep 01.
Article in English | MEDLINE | ID: mdl-35930487

ABSTRACT

SARS-CoV-2 is associated with a post-infectious neurocognitive syndrome characterized by fatigue and deficits in attention, memory, and executive function. As screening cognitive testing generally remains normal, the pathophysiologic basis of these symptoms remains controversial and there is no standardized treatment paradigm. We present a clinical case demonstrative of typical neurocognitive sequelae of SARS-CoV-2 infection, highlighting medical and social factors that may have contributed to the severity of symptoms. We discuss the pathophysiologic evidence for cognitive "brain fog" following COVID-19 infection as well as lifestyle changes and rehabilitation strategies that may improve recovery. As the benefits of pharmacologic therapy remain unproven, we close with a brief discussion of medication options that might be appropriate targets for future clinical trials in the context of rehabilitative treatment.


Subject(s)
COVID-19 , COVID-19/complications , Cognition , Executive Function/physiology , Humans , Neuropsychological Tests , SARS-CoV-2
11.
J Occup Environ Med ; 64(9): e545-e549, 2022 09 01.
Article in English | MEDLINE | ID: mdl-35902373

ABSTRACT

OBJECTIVE: Workplace wellness programs can reduce cardiovascular risk and improve worker productivity; however, recruitment and adherence remain a challenge. Tailoring programs based on employee exercise preferences may address these concerns. METHODS: A total of 458 UCLA adult employees who responded to UCLA Bruin marketing e-mail completed a battery of questions regarding their exercise preferences (eg, preferred duration, intensity, type). Recruitment took place in June 2021. RESULTS: Participants prefer workplace wellness programs that (1) focus on improving multiple different aspects of physical health; (2) take place in a variety of locations; (3) were administered by a coach who is physically present; (4) occur 2-3 times per week for roughly 60 minutes each time; (5) include a range of intensities; and (6) consist of aerobic and weight training. CONCLUSIONS: Future studies should use these results to design future workplace wellness programs.


Subject(s)
Cardiovascular Diseases , Occupational Health , Adult , Cardiovascular Diseases/prevention & control , Health Promotion/methods , Heart Disease Risk Factors , Humans , Risk Factors , Workplace
12.
J Am Chem Soc ; 144(24): 10862-10869, 2022 Jun 22.
Article in English | MEDLINE | ID: mdl-35675664

ABSTRACT

Electrides are exotic materials that typically have electrons present in well-defined lattice sites rather than within atoms. Although all known electrides have an electropositive metal cation adjacent to the electride site, the effect of cation electronegativity on the properties of electrides is not yet known. Here, we examine trivalent metal carbides with varying degrees of electronegativity and experimentally synthesize Sc2C. Our studies identify the material as a two-dimensional (2D) electride, even though Sc is more electronegative than any metal previously found adjacent to an electride site. Further, by exploring Sc2C and Al2C computationally, we find that higher electronegativity of the cation drives greater hybridization between metal and electride orbitals, which opens a band gap in these materials. Sc2C is the first 2D electride semiconductor, and we propose a design rule that cation electronegativity drives the change in its band structure.

13.
Vaccines (Basel) ; 10(3)2022 Mar 09.
Article in English | MEDLINE | ID: mdl-35335045

ABSTRACT

Sexual and gender minority (SGM) and racial or ethnic minority youth at-risk for or living with HIV may have higher risk of SARS-CoV-2 infection. However, there are few data on vaccine hesitancy/acceptance and COVID-19 self-protective behaviors among this population. Youth aged 15-24 years (n = 440), predominantly African American and Latine (73%, n = 320) SGM, from Los Angeles and New Orleans reported their vaccine attitudes and COVID-19 and HIV preventive behaviors in October 2020. Latent class analyses categorized individuals into groups based on their vaccine attitudes and preventive behaviors. Relationships between these groups and other factors were analyzed using Fisher's exact tests, ANOVA, and logistic regression. Most youth had accepting vaccine attitudes (70.2%, n = 309), with 20.7% hesitant (n = 91), and 9.1% resistant (n = 40). SGM and African Americans were significantly less accepting than their cis-gender and heterosexual peers. About two-thirds (63.2%, n = 278) of the respondents reported consistent COVID-19 self-protective behaviors. Youth with pro-vaccine attitudes were most consistently self-protective; however, only 54.4% (n= 168/309) intended to take a COVID-19 vaccine. Homelessness history, race, and sexual orientation were associated with vaccine attitudes. Accepting vaccine attitudes and consistent COVID-19 self-protective behaviors were closely related. COVID-19 attitudes/behaviors were not associated with HIV risk and only loosely associated with SARS-CoV-2 vaccine intentions.

14.
J Health Psychol ; 27(10): 2446-2459, 2022 09.
Article in English | MEDLINE | ID: mdl-33106045

ABSTRACT

This systematic review assessed the relationship between exercise and ART adherence in adults living with HIV. A comprehensive search through June 2020 for relevant studies was conducted, and PRISMA guidelines were followed. To be included, studies had to meet the following criteria: (a) published in a peer-reviewed journal; and (b) examined the relationship between exercise and ART adherence. A total of 4310 studies were identified, and nine were included. The majority (five out of nine) of studies found a significant and positive relationship between exercise and ART adherence. Strengths, limitations, and future directions are discussed.


Subject(s)
HIV Infections , Medication Adherence , Adult , Anti-Retroviral Agents/therapeutic use , Exercise , HIV Infections/drug therapy , Humans
15.
AIDS Care ; 34(2): 188-192, 2022 02.
Article in English | MEDLINE | ID: mdl-34743617

ABSTRACT

The worldwide spread of COVID-19 has led to closures or reduced capacity of non-essential businesses and recreational areas and stay-at-home orders to promote social distancing. Although effective to reduce transmission, these policies may negatively impact exercise behaviors. Exercise is effective at mitigating the risk of developing or exacerbating several of underlining risk factors for a more severe COVID-19 disease course and may be particularly important for people with HIV (PWH). In this commentary, we discuss the intersection of COVID-19 and exercise with a specific focus on people living with HIV. We then provide a pragmatic, home-based exercise routine that can be performed with little to no equipment or supervision. It is important for PWH (and others) to start or maintain at least some level of exercise to reduce the risk of a severe COVID-19 disease course and to improve other health outcomes in this unfamiliar climate.


Subject(s)
COVID-19 , HIV Infections , Commerce , Exercise , HIV Infections/prevention & control , Humans , SARS-CoV-2
16.
Int J Infect Dis ; 104: 27-33, 2021 Mar.
Article in English | MEDLINE | ID: mdl-33401033

ABSTRACT

OBJECTIVES: Rates of maternal syphilis have increased five-fold in Brazil in the past decade. While penicillin remains the only appropriate treatment for maternal syphilis, we hypothesized that low non-treponemal titers (<1:16) may lead to reduced penicillin treatment in Brazil. METHODS: Using Brazilian Ministry of Health data on women diagnosed with maternal syphilis between January 1, 2010, and December 31, 2018, we conducted a random-effects logistic regression model with a cluster correction at the state level to evaluate predictive factors of penicillin treatment. RESULTS: We observed yearly increases in cases of pregnant women with syphilis from 2010 to 2018. There was significant variation by state: 52,451 cases were reported in São Paulo, followed by 26,838 in Rio de Janeiro. Among 215,937 cases of maternal syphilis, 91·3% received penicillin. In the random-effects model, a non-treponemal titer ≥1:16 was associated with 1·44 higher odds of receiving penicillin (95% confidence interval [CI]: 1·391·48), and prenatal care was associated with a 2·12 increased odds of receiving penicillin (95% CI: 2·022·21). Although there is an association between the absence of prenatal care and inadequate treatment for syphilis, 83·2% of women in this cohort who did not receive penicillin were engaged in prenatal care. CONCLUSIONS: Providers may inappropriately exclude low non-treponemal titers and thereby fail to use penicillin treatment in maternal syphilis. While the cause of the maternal syphilis epidemic in Brazil is multifactorial, we believe our findings can be used to develop targeted interventions throughout Brazil as well as shape public health initiatives globally.


Subject(s)
Anti-Bacterial Agents/therapeutic use , Penicillins/therapeutic use , Pregnancy Complications, Infectious/drug therapy , Syphilis/drug therapy , Adult , Brazil/epidemiology , Cohort Studies , Female , Humans , Pregnancy , Pregnancy Complications, Infectious/diagnosis , Pregnancy Complications, Infectious/epidemiology , Pregnant Women , Prenatal Care , Syphilis/diagnosis , Syphilis/epidemiology , Young Adult
17.
Small ; 17(1): e2004823, 2021 01.
Article in English | MEDLINE | ID: mdl-33300303

ABSTRACT

Engineering electrode materials for optoelectronic and energy storage applications requires a fundamental understanding of intercalation using spatially-resolved techniques. However, spectroscopic methods can have limited spatial resolution and low intensity since the signal passes through electrolyte. Here, a device geometry is presented in which the electrolyte is laterally separated from the area probed spectroscopically, so that the signal does not pass through the electrolyte. This geometry enables us to visualize ion transport with optical microscopy and monitor charge transfer with Raman and visible reflectance spectroscopies. In addition, vibrational changes are probed in the mid-IR, a region previously difficult to access due to electrolyte absorption. This geometry will allow many layered electrodes to be probed in situ using time- and spatially-resolved techniques, including photon and electron spectroscopies.

18.
J Med Internet Res ; 22(11): e18309, 2020 11 02.
Article in English | MEDLINE | ID: mdl-33136057

ABSTRACT

BACKGROUND: Consistent with young adults' penchant for digital communication, young adults living with HIV use digital communication media to seek out health information. Understanding the types of health information sought online and the characteristics of these information-seeking young adults is vital when designing digital health interventions for them. OBJECTIVE: This study aims to describe characteristics of young adults living with HIV who seek health information through the internet. Results will be relevant to digital health interventions and patient education. METHODS: Young adults with HIV (aged 18-34 years) self-reported internet use during an evaluation of digital HIV care interventions across 10 demonstration projects in the United States (N=716). Lasso (least absolute shrinkage and selection operator) models were used to select characteristics that predicted whether participants reported seeking general health and sexual and reproductive health (SRH) information on the internet during the past 6 months. RESULTS: Almost a third (211/716, 29.5%) and a fifth (155/716, 21.6%) of participants reported searching for general health and SRH information, respectively; 26.7% (36/135) of transgender young adults with HIV searched for gender-affirming care topics. Areas under the curve (>0.70) indicated success in building models to predict internet health information seeking. Consistent with prior studies, higher education and income predicted health information seeking. Higher self-reported antiretroviral therapy adherence, substance use, and not reporting transgender gender identity also predicted health information seeking. Reporting a sexual orientation other than gay, lesbian, bisexual, or straight predicted SRH information seeking. CONCLUSIONS: Young adults living with HIV commonly seek both general health and SRH information online, particularly those exploring their sexual identity. Providers should discuss the most commonly sought SRH topics and the use of digital technology and be open to discussing information found online to better assist young adults with HIV in finding accurate information. Characteristics associated with health information-seeking behavior may also be used to develop and tailor digital health interventions for these young adults.


Subject(s)
HIV Infections/epidemiology , Information Seeking Behavior/ethics , Adolescent , Adult , Female , Health Behavior , Humans , Longitudinal Studies , Male , United States , Young Adult
19.
J Phys Chem Lett ; 11(21): 9210-9214, 2020 Nov 05.
Article in English | MEDLINE | ID: mdl-33058726

ABSTRACT

It is widely assumed that the gain or loss of electrons in a material must be accompanied by its reduction or oxidation. Here, we report a system in which the insertion/deinsertion of an electron occurs without any reduction or oxidation. Using first-principles methods, we demonstrate this effect in the Y2CF2-[Y2C]2+(e-)2 material system, where (e-) indicates a lattice site containing a bare electron. We present a model in which Y2CF2 is in contact with a fluoride-containing electrolyte and the application of a positive voltage drives fluorination while a negative voltage reverses the process. We show that this chemistry does not change the oxidation states of the host lattice, causes no significant volume expansion, and occurs rapidly at room temperature. Finally, we demonstrate that this mechanism of ion insertion may enable a broad class of anion shuttle battery electrodes, some with gravimetric capacities nearly double those employed in intercalation-type Li-ion batteries.

20.
Science ; 368(6487): 177-180, 2020 04 10.
Article in English | MEDLINE | ID: mdl-32273466

ABSTRACT

Ratcheting effects play an important role in systems ranging from mechanical socket wrenches to biological motor proteins. The underlying principle is to convert a fluctuating, unbiased force into unidirectional motion. Here, we report the ratcheting of electrons at room temperature using a semiconductor nanowire with precisely engineered asymmetry. Modulation of the nanowire diameter creates a cylindrical sawtooth geometry with broken inversion symmetry on a nanometer-length scale. In a two-terminal device, this structure responded as a three-dimensional geometric diode that funnels electrons preferentially in one direction through specular reflection of quasi-ballistic electrons at the nanowire surface. The ratcheting effect causes charge rectification at frequencies exceeding 40 gigahertz, demonstrating the potential for applications such as high-speed data processing and long-wavelength energy harvesting.

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