The Investigation of Uniform, Monodisperse Crystalline Particles via the Evaporation of Small Droplets

Many industrial solids processes require the production of disperse particles. In industries such as food, personal care, and pharmaceuticals, particle formation is widely used to produce solid products or to separate substances in intermediate process steps. The most important characteristics known to impact the effectiveness of a solid product are purity, size, internal structure, and morphology. These characteristics are essential to maintain optimal operation of subsequent process steps and for obtaining the desired high quality product. This thesis aims to aid in the advancement of particle production technology by (1) investigating the use of a vibrating orifice aerosol generator (VOAG) for collecting data to predict particle attributes including morphology, size, and internal structure as a function of processing parameters such as solvent, solution concentration, air flow rate, and initial droplet size, as well as to (2) determine the extent to which uniform droplet evaporation can be a tool to achieve novel particle morphologies, controlled sizes, or internal structures (crystallinity and crystal form). Experimental results for succinic acid, L-serine, and L-glutamic acid suggest that particles of controlled characteristics can indeed be produced by this method. Analysis by scanning electron microscopy (SEM), nanoindentation, and X-ray diffraction (XRD) shows that various sizes, internal structures, and morphologies can be obtained using the VOAG. Furthermore, unique morphologies and unexpected internal structures were able to be achieved for succinic acid, providing an added benefit to particle formation by this method.

Performance Tuning Non-Uniform Sampling for Sensitivity Enhancement of Signal-Limited Biological NMR

Non-uniform sampling (NUS) has been established as a route to obtaining true sensitivity enhancements when recording indirect dimensions of decaying signals in the same total experimental time as traditional uniform incrementation of the indirect evolution period. Theory and experiments have shown that NUS can yield up to two-fold improvements in the intrinsic signal-to-noise ratio (SNR) of each dimension, while even conservative protocols can yield 20-40 % improvements in the intrinsic SNR of NMR data. Applications of biological NMR that can benefit from these improvements are emerging, and in this work we develop some practical aspects of applying NUS nD-NMR to studies that approach the traditional detection limit of nD-NMR spectroscopy. Conditions for obtaining high NUS sensitivity enhancements are considered here in the context of enabling H-1,N-15-HSQC experiments on natural abundance protein samples and H-1,C-13-HMBC experiments on a challenging natural product. Through systematic studies we arrive at more precise guidelines to contrast sensitivity enhancements with reduced line shape constraints, and report an alternative sampling density based on a quarter-wave sinusoidal distribution that returns the highest fidelity we have seen to date in line shapes obtained by maximum entropy processing of non-uniformly sampled data.

Health insurance coverage of Hispanic adults: An assessment of subgroup difference and the impact of immigration

This research explores the health insurance coverage of various Hispanic subgroups in comparison to non-Hispanic whites and blacks. The impact of immigration status is also considered as we hypothesize that nativity, duration, and naturalization tap a possible process of structural acculturation that increases access to insurance coverage for Hispanic groups. We find that the immigration variables impact the type of insurance reported. However, race/ethnic disparities continue to exist, with the various Hispanic subgroups more likely to report miscellaneous government health insurance or no health insurance coverage as compared to non-Hispanic whites.

Endothelial survival factors and spatial completion, but not pericyte coverage of retinal capillaries determine vessel plasticity

Pericyte loss and capillary regression are characteristic for incipient diabetic retinopathy. Pericyte recruitment is involved in vessel maturation, and ligand-receptor systems contributing to pericyte recruitment are survival factors for endothelial cells in pericyte-free in vitro systems. We studied pericyte recruitment in relation to the susceptibility toward hyperoxia-induced vascular remodeling using the pericyte reporter X-LacZ mouse and the mouse model of retinopathy of prematurity (ROP). Pericytes were found in close proximity to vessels, both during formation of the superficial and the deep capillary layers. When exposure of mice to the ROP was delayed by 24 h, i.e., after the deep retinal layer had formed [at postnatal (p) day 8], preretinal neovascularizations were substantially diminished at p18. Mice with a delayed ROP exposure had 50% reduced avascular zones. Formation of the deep capillary layers at p8 was associated with a combined up-regulation of angiopoietin-1 and PDGF-B, while VEGF was almost unchanged during the transition from a susceptible to a resistant capillary network. Inhibition of Tie-2 function either by soluble Tie-2 or by a sulindac analog, an inhibitor of Tie-2 phosphorylation, resensitized retinal vessels to neovascularizations due to a reduction of the deep capillary network. Inhibition of Tie-2 function had no effect on pericyte recruitment. Our data indicate that the final maturation of the retinal vasculature and its resistance to regressive signals such as hyperoxia depend on the completion of the multilayer structure, in particular the deep capillary layers, and are independent of the coverage by pericytes.

Uniform vascular-endothelial-cell-specific gene expression in both embryonic and adult transgenic mice

TIE2 is a vascular endothelial-specific receptor tyrosine kinase essential for the regulation of vascular network formation and remodeling. Previously, we have shown that the 1.2-kb 5' flanking region of the TIE2 promoter is capable of directing beta-galactosidase reporter gene expression specifically into a subset of endothelial cells (ECs) of transgenic mouse embryos. However, transgene activity was restricted to early embryonic stages and not detectable in adult mice. Herein we describe the identification and characterization of an autonomous endothelial-specific enhancer in the first intron of the mouse TIE2 gene. Furthermore, combination of the TIE2 promoter with an intron fragment containing this enhancer allows it to target reporter gene expression specifically and uniformly to virtually all vascular ECs throughout embryogenesis and adulthood. To our knowledge, this is the first time that an in vivo expression system has been assembled by which heterologous genes can be targeted exclusively to the ECs of the entire vasculature. This should be a valuable tool to address the function of genes during physiological and pathological processes of vascular ECs in vivo. Furthermore, we were able to identify a short region critical for enhancer function in vivo that contains putative binding sites for Ets-like transcription factors. This should, therefore, allow us to determine the molecular mechanisms underlying the vascular-EC-specific expression of the TIE2 gene.

A call for uniform reporting standards in studies assessing endovascular treatment for chronic ischaemia of lower limb arteries

Endovascular therapy is a rapidly evolving field for the treatment of patients with peripheral arterial disease, and a magnitude of studies reporting on various modern revascularization concepts have been recently published. Thus, studies assessing the efficacy of endovascular therapy of peripheral arteries do not operate with uniformly defined endpoints, rendering a direct comparison of studies difficult. The purpose of this consensus statement is to highlight differences in the terminology used in the current literature and to propose some standardized criteria that must be considered when reporting results of endovascular revascularization for chronic ischaemia of lower limb arteries.

Soft tissue dehiscence coverage around endosseous implants: a prospective cohort study

AIM: To evaluate the healing outcome of soft tissue dehiscence coverage at implant sites. MATERIAL AND METHODS: Ten patients with one mucosal recession defect at an implant site and a contralateral unrestored clinical crown without recession were recruited. The soft tissue recessions were surgically covered using a coronally advanced flap in combination with a free connective tissue graft. Healing was studied at 1, 3 and 6 months post-operatively. RESULTS: Soft tissue dehiscences were covered with a coronal overcompensation of the flap margin up to 1.2 mm after the procedure. After 1 month, the coverage shrank to a mean of 75%, after 3 months to 70% and after 6 months to 66%. CONCLUSIONS: The implant sites revealed a substantial, clinically significant improvement following coronal mucosal displacement in combination with connective tissue grafting, but in none of the sites, a could complete implant soft tissue dehiscence coverage be achieved.

Peripheral endovascular revascularization trials: high noon for uniform reporting standards

In the era of evidence based medicine, proof of clinical benefits and cost-effectiveness need to be firmly based on transparent comparisons between various therapeutic alternatives. Standards for reports are a prerequisite for comparisons across reports and should reflect the patient's perspective. According standards have been successfully introduced in many fields of modern medicine, but not yet for peripheral endovascular interventions. Given the overwhelmingly increasing importance of endovascular revascularization in patients with chronic lower limb ischemia, this report provides an updated outline of the heterogeneity of current reporting practice and highlights the need for uniform reporting standards.

Femoral morphology differs between deficient and excessive acetabular coverage

Structural deformities of the femoral head occurring during skeletal development (eg, Legg-Calvé-Perthes disease) are associated with individual shapes of the acetabulum but it is unclear whether differences in acetabular shape are associated with differences in proximal femoral shape. We questioned whether the amount of acetabular coverage influences femoral morphology. We retrospectively compared the proximal femoral anatomy of 50 selected patients (50 hips) with developmental dysplasia of the hip (lateral center-edge angle [LCE] < or = 25 degrees ; acetabular index > or = 14 degrees ) with 45 selected patients (50 hips) with a deep acetabulum (LCE > or = 39 degrees ). Using MRI arthrography we measured head sphericity, epiphyseal shape, epiphyseal extension, and femoral head-neck offset. A deep acetabulum was associated with a more spherical head shape, increased epiphyseal height with a pronounced extension of the epiphysis towards the femoral neck, and an increased offset. In contrast, dysplastic hips showed an elliptical femoral head, decreased epiphyseal height with a less pronounced extension of the epiphysis, and decreased head-neck offset. Hips with different acetabular coverage are associated with different proximal femoral anatomy. A nonspherical head in dysplastic hips could lead to joint incongruity after an acetabular reorientation procedure. LEVEL OF EVIDENCE: Level IV, retrospective comparative study. See the Guidelines for Authors for a complete description of levels of evidence.

[Coverage of pressure sores with free flaps]

INTRODUCTION: The coverage of recurrent pressure sores with unstable scar in the surrounding tissue is still an unsolved problem in the literature. Local and regional transfer of tissue often does not meet the requirements of the tissue deficit. Especially in recurrent pressure sores, the adjacent skin has already been consumed due to multiple surgeries. As a good alternative, the microsurgical transfer of flaps offers viable tissue to cover even large pressure sores. METHODS: We performed a total of six free flaps in five patients who suffered from intractable pressure sores in the hip region. The age of the patients was between 41 and 63 years. The defect size varied between 6 x 6 cm and 25 x 30 cm. Two combined myocutaneous scapula-latissimus dorsi, two myocutaneous latissimus dorsi, one anteromedial thigh, and one rectus femoris flap were used to cover the defects. RESULTS: The average follow-up time was 29 months. Flaps provided stable coverage in four of five patients at 12-month follow-up. There was one subtotal flap necrosis that was subsequently treated with split-thickness skin grafting. CONCLUSION: In this series of five patients with six free flaps, we were able to show that the microsurgical transfer of tissue is a valuable option in the treatment of difficult pressure sores. Even in older and debilitated patients, this method is a good alternative to conventional local flaps.

DEVELOPMENT OF AN IONIC LIQUID FERROFLUID ELECTROSPRAY SOURCE AND MODE SHAPE STUDIES OF A FERROFLUID IN A NON-UNIFORM MAGNETIC FIELD

An electrospray source has been developed using a novel new fluid that is both magnetic and conductive. Unlike conventional electrospray sources that required microfabricated structures to support the fluid to be electrosprayed, this new electrospray fluid utilizes the Rosensweig instability to create the structures in the magnetic fluid when an external magnetic field was applied. Application of an external electric field caused these magnetic fluid structures to spray. These fluid based structures were found to spray at a lower onset voltage than was predicted for electrospray sources with solid structures of similar geometry. These fluid based structures were also found to be resilient to damage, unlike the solid structures found in traditional electrospray sources. Further, experimental studies of magnetic fluids in non-uniform magnetic fields were conducted. The modes of Rosensweig instabilities have been studied in-depth when created by uniform magnetic fields, but little to no studies have been performed on Rosensweig instabilities formed due to non-uniform magnetic fields. The measured spacing of the cone-like structures of ferrofluid, in a non-uniform magnetic field, were found to agree with a proposed theoretical model.