Efficacy and safety of long-acting cabotegravir compared with daily oral tenofovir disoproxil fumarate plus emtricitabine to prevent HIV infection in cisgender men and transgender women who have sex with men 1 year after study unblinding: a secondary analysis of the phase 2b and 3 HPTN 083 randomised controlled trial.

Background: Injectable cabotegravir was superior to daily oral tenofovir disoproxil fumarate plus emtricitabine for HIV prevention in two clinical trials. Both trials had the primary aim of establishing the HIV prevention efficacy of long-acting injectable cabotegravir pre-exposure prophylaxis (PrEP) compared with tenofovir disoproxil fumarate plus emtricitabine daily oral PrEP. Long-acting PrEP was associated with diagnostic delays and integrase strand-transfer inhibitor (INSTI) resistance.

Determination of HIV status and identification of incident HIV infections in a large, community-randomized trial: HPTN 071 (PopART).

Introduction: The HPTN 071 (PopART) trial evaluated the impact of an HIV combination prevention package that included "universal testing and treatment" on HIV incidence in 21 communities in Zambia and South Africa during 2013-2018. The primary study endpoint was based on the results of laboratory-based HIV testing for> 48,000 participants who were followed for up to three years. This report evaluated the performance of HIV assays and algorithms used to determine HIV status and identify incident HIV infections in HPTN 071, and assessed the impact of errors on HIV incidence estimates.

Improved Pulsed Laser Operation with Engineered Nanomaterials.

The power efficiency of a diode-pumped solid state laser was improved by encasing the Nd:YAG lasing medium with gold nanorod-doped epoxy. Gold nanorods were synthesized with a specific aspect ratio tuned to absorb at the Nd:YAG lasing wavelength of 1064 nm. The surfactant-stabilized nanorods in aqueous solution were then treated with a sequential, two-step functionalization in order to improve nanorod solubility in organic solvents.

Nano-engineering lattice dimensionality for a soft matter organic functional material.

A high performing electro-optic (EO) chromophore with covalently attached coumarin-based pendant groups exhibits intermolecular correlation of coumarin units through molecular dynamics (MD) simulations. Unique, orthogonal molecular orientations of the chromophore and coumarin units are also evident when investigated optically. Such molecular orientation translates to reduced lattice dimensionality of the bulk C1 soft matter material system, leading to increased acentric order and EO activity.

An organophosphonate strategy for functionalizing silicon photonic biosensors.

Silicon photonic microring resonators have established their potential for label-free and low-cost biosensing applications. However, the long-term performance of this optical sensing platform requires robust surface modification and biofunctionalization. Herein, we demonstrate a conjugation strategy based on an organophosphonate surface coating and vinyl sulfone linker to biofunctionalize silicon resonators for biomolecular sensing.

Measuring order in contact-poled organic electrooptic materials with variable-angle polarization-referenced absorption spectroscopy (VAPRAS).

Organic nonlinear electrooptical (ONLO) chromophores must be acentrically ordered for the ONLO material to have electrooptic (EO) activity. The magnitude of the order is characterized by the acentric order parameter, , where β is the major Euler angle between the main axis of the chromophore and the poling field which imposes the acentric order. The acentric order parameter, which is difficult to measure directly, is related to the centrosymmetric order parameter, defined as = ½(3-1), through the underlying statistical distribution.

Reduced dimensionality in organic electro-optic materials: theory and defined order.

Identification of electronic intermolecular electrostatic interactions that can significantly enhance poling-induced order is important to the advancement of the field of organic electro-optics. Here, we demonstrate an example of such improvement achieved through exploitation of the interaction of coumarin pendant groups in chromophore-containing macromolecules. Acentric order enhancement is explained in terms of lattice-symmetry effects, where constraint of orientational degrees of freedom alters the relationship between centrosymmetric and acentric order.

Modeling the optical behavior of complex organic media: from molecules to materials.

For the past three decades, a full understanding of the electro-optic (EO) effect in amorphous organic media has remained elusive. Calculating a bulk material property from fundamental molecular properties, intermolecular electrostatic forces, and field-induced net acentric dipolar order has proven to be very challenging. Moreover, there has been a gap between ab initio quantum-mechanical (QM) predictions of molecular properties and their experimental verification at the level of bulk materials and devices.

Theory-inspired development of organic electro-optic materials.

Correlated time-dependent density functional theory (TDDFT) quantum mechanical and pseudo-atomistic Monte Carlo (PAMC) statistical mechanical methods have been used to assist in the understanding of and to guide the improvement of organic electro-optic (OEO) materials, prepared by electric field poling of pi-electron chromophore-containing materials near their glass transition temperature. Theoretical treatment of the effects of dielectric permittivity and optical frequency on molecular (chromophore) first hyperpolarizabilities has been carried out as well as the analysis of the influence of spatially anisotropic intermolecular electrostatic interactions on the poling-induced noncentrosymmetric order of chromophores. Three classes of OEO materials have been considered in correlated theoretical and experimental investigations: (1) traditional chromophore/polymer composite materials, (2) chromophores covalently incorporated into polymers, dendrimers, and dendronized polymers, and (3) recently discovered materials consisting of chromophores incorporated into chromophore-containing host materials.

Rational enhancement of second-order nonlinearity: bis-(4-methoxyphenyl)hetero-aryl-amino donor-based chromophores: design, synthesis, and electrooptic activity.

Two new highly hyperpolarizable chromophores, based on N,N- bis-(4-methoxyphenyl) aryl-amino donors and phenyl-trifluoromethyl-tricyanofuran (CF3-Ph-TCF) acceptor linked together via pi-conjugation through 2,5-divinylenethienyl moieties as the bridge, have been designed and synthesized successfully for the first time. The aryl moieties on the donor side of the chromophore molecules were varied as to be thiophene and 1-n-hexylpyrrole. The linear and nonlinear optical (NLO) properties of all compounds were evaluated in addition to recording relevant thermal and electrochemical data.

Polarization selective electro-optic polymer waveguide devices by direct electron beam writing.

A novel technique for the fabrication of polarization selective electro-optic polymer waveguide devices with direct electron beam writing was described. Birefringence induced by the electric field poling in the electro-optic polymer film was erased in the electron beam exposed regions. The formed waveguides had stronger confinement for the light polarized along the poling direction.

Direct electron beam writing of electro-optic polymer microring resonators.

Electro-optic polymer waveguides in electron beam sensitive polymethyl methacrylate (PMMA) polymer matrix doped with organic nonlinear chromophores could be directly patterned by electron beam exposure with high resolution and smoothness. The polymer in the exposed regions was removed with standard electron beam resist developer and without damaging the chromophore containing polymer waveguides. Feature sizes on the order of 100 nm could be clearly resolved.

Theory-guided design and synthesis of multichromophore dendrimers: an analysis of the electro-optic effect.

Extensive experimental and theoretical study suggests that interchromophore electrostatic interactions are among the most severe impediments to the induction and stability of large electro-optic coefficients in electric-field-poled organic materials. In this report, multichromophore-containing dendritic materials have been investigated as a means to minimize unwanted attenuation of nonlinear optical (electro-optic) activity at high chromophore loading. The dendritic molecular architectures employed were designed to provide optimized molecular scaffolding for electric-field-induced molecular reorientation.