ABSTRACT
The microstructure of plastic bonded explosives (PBXs) is known to influence behavior during mechanical deformation, but characterizing the microstructure can be challenging. For example, the explosive crystals and binder in formulations such as PBX 9501 do not have sufficient X-ray contrast to obtain three-dimensional data by in situ, absorption contrast imaging. To address this difficulty, we have formulated a series of PBXs using octahydro-1,3,5,7-tetranitro-1,3,5,7-tetrazocine (HMX) crystals and low-density binder systems. The binders were hydroxyl-terminated polybutadiene (HTPB) or glycidyl azide polymer (GAP) cured with a commercial blend of acrylic monomers/oligomers. The binder density is approximately half of the HMX, allowing for excellent contrast using in situ X-ray computed tomography (CT) imaging. The samples were imaged during unaxial compression using micro-scale CT in an interrupted in situ modality. The rigidity of the binder was observed to significantly influence fracture, crystal-binder delamination, and flow. Additionally, 2D slices from the segmented 3D images were meshed for finite element simulation of the mesoscale response. At low stiffness, the binder and crystal do not delaminate and the crystals move with the material flow; at high stiffness, marked delamination is noted between the crystals and the binder, leading to very different mechanical properties. Initial model results exhibit qualitatively similar delamination.
ABSTRACT
A key factor to the successful treatment of HIV is good adherence to antiretroviral therapy (ART). We developed a pharmacist-managed adherence clinic and designed a study to assess the impact of the adherence interventions by measuring the proportion of patients with 95% or greater adherence to ART before and after referral to the program. HIV providers referred patients with adherence problems to a pharmacist-managed adherence clinic. Interventions included scheduled clinic visits with the HIV Clinical Pharmacist and monthly refill reminders from pharmacy staff members over a 6-month period. Those aged 18-75, prescribed an ART regimen for a minimum of 3 months, and who filled their medications exclusively at the clinic pharmacy were eligible for study participation. The Proportion of Days Covered (PDC) served as a surrogate marker of overall adherence. A total of 34 patients were referred to the pharmacy clinic for adherence counseling, of whom 28 enrolled in the study. The proportion of participants with 95% or greater adherence to their ART regimen increased from 7% at baseline to 32% postintervention (p = 0.01). A subanalysis of the PDC revealed an overall increase from a baseline adherence mean of 60% to 81% postintervention (p < 0.0001). There was a notable trend toward an increase in the proportion of participants with an undetectable HIV-1 viral load (58-73%, baseline and postintervention, respectively, p = 0.10), but no statistically significant improvement in CD4 cell count. Clinical pharmacy interventions improved overall adherence to ART regimens in these patients with HIV.
