Jacob Urquidi

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Small angle neutron scattering (SANS) was used to study the structure of Avicel (FD100) microcrystalline cellulose during enzymatic digestion. Digestions were performed in either of two modes: a static, quiescent mode or a dynamic mode using a stirred suspension recycled through a flow cell. The scattering pattern for as-received Avicel in D(2)O buffer is(More)
Structural changes during annealing of high-density amorphous ice were studied with both neutron and x-ray diffraction. The first diffraction peak was followed from the high- to the low-density amorphous form. Changes were observed to occur through a series of intermediate forms that appear to be metastable at each anneal temperature. Five distinct(More)
Retail stores contain a wide range of products that can emit a variety of indoor pollutants. Among these chemicals, phthalate esters and polybrominated diphenyl ethers (PBDEs) are two important categories of semi-volatile organic compounds (SVOCs). Filters in heating, ventilation, and air-conditioning (HVAC) system collect particles from large volumes of(More)
Sterile Insect Technique (SIT) has been successfully implemented to control, and in some cases, eradicate, dipteran insect populations. SIT has great potential as a mosquito control method. Different sterilization methods have been used on mosquitoes ranging from chemosterilization to genetically modified sterile male mosquito strains; however,(More)
Our laboratory has been involved in expounding an outer neighbor molecular-level structural theory for liquid water in the supercooled and ordinary thermodynamic regimes. This theory, which depends on transformations with increasing temperature or pressure, is consistent with all the properties of this substance, including the ten or so "anomalies", and has(More)
The liquid state is the most complex phase of matter. Densities of liquids are comparable to densities of the solids, implying that the forces between particles in the liquid are of the samemagnitude as those forces present in the solid. However, there is no simplification due to the presence of a lattice and no satisfactory analytic theory of the liquid(More)
The liquid state is the most complex phase of matter. Densities of liquids are comparable to densities of the solids, implying that the forces between particles in the liquid are of the samemagnitude as those forces present in the solid. However, there is no simplification due to the presence of a lattice and no satisfactory analytic theory of the liquid(More)
As a part of the WHO Age-Associated Dementia Project, Chile has been participating in a cross-national survey on dementia frequency and determinants since 1989. In the present study, apolipoprotein E (ApoE) polymorphism genotypes have been compared in 95 patients with Alzheimer's disease (AD) (mean age 80.7; 95% CI 79.2-82.2, range 66-97) and 187 healthy(More)
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