The scaling challenges of CMOS and the impact on high-density non-volatile memories

Solid-state mass storage has experienced recently an explosive growth, mainly related to digital consumer application (digital cameras, MP3 players, USB keys). The demand is not expected to slow down in the near future. Present storage technology is based on NAND Flash, and it appears that there is still margin to scale it down at least to the 45 nm node. The likely appearance of physical limits to scalability is pushing for the investigation of alternative storage technologies, and several solutions have been proposed. However, any kind of memory needs a selection mechanism, and related parasitic effects can be a severe limitation to scaling. Scaling challenges of select devices (mostly CMOS), and their impact on memory scaling will be investigated, and alternatives proposed.     

COBRA: a computational brewing application for predicting the molecular composition of organic aerosols

Atmospheric organic aerosols (OA) represent a significant fraction of airborne particulate matter and can impact climate, visibility, and human health. These mixtures are difficult to characterize experimentally due to their complex and dynamic chemical composition. We introduce a novel Computational Brewing Application (COBRA) and apply it to modeling oligomerization chemistry stemming from condensation and addition reactions in OA formed by photooxidation of isoprene. COBRA uses two lists as input: a list of chemical structures comprising the molecular starting pool and a list of rules defining potential reactions between molecules. Reactions are performed iteratively, with products of all previous iterations serving as reactants for the next. The simulation generated thousands of structures in the mass range of 120-500 Da and correctly predicted ～70% of the individual OA constituents observed by high-resolution mass spectrometry. Select predicted structures were confirmed with tandem mass spectrometry. Esterification was shown to play the most significant role in oligomer formation, with hemiacetal formation less important, and aldol condensation insignificant. COBRA is not limited to atmospheric aerosol chemistry; it should be applicable to the prediction of reaction products in other complex mixtures for which reasonable reaction mechanisms and seed molecules can be supplied by experimental or theoretical methods.     

Biomimetic Design of Protein Nanomaterials for Hydrophobic Molecular Transport

Biomaterials such as self‐assembling biological complexes have a variety of applications in materials science and nanotechnology. The functionality of protein‐based materials, however, is often limited by the absence or locations of specific chemical conjugation sites. Here a new strategy is developed for loading organic molecules into the hollow cavity of a protein nanoparticle that relies only on non‐covalent interactions, and its applicability in drug delivery is demonstrated in breast cancer cells. Based on a biomimetic model that incorporates multiple phenylalanines to create a generalized binding site, the anti‐tumor compound doxorubicin is retained and delivered by redesigning a caged protein scaffold. Using structural modeling and protein engineering, variants of the E2 subunit of pyruvate dehydrogenase with varying levels of drug‐carrying capabilities are obtained. An increasing number of introduced phenylalanines within the scaffold cavity generally results in greater drug loading capacity. Drug loading levels greater than conventional nanoparticle delivery systems are achieved. The universal strategy can be used to design de novo hydrophobic binding domains within protein‐based scaffolds for molecular encapsulation and transport and increases the ability to attach guest molecules to this class of materials.     

Short communication: Oxidative status and incidence of mastitis relative to blood α-tocopherol concentrations in the postpartum period in dairy cows

Vitamin E supplementation, when combined with high blood α-tocopherol (>6.25 μg/mL) at dry off, has been reported to unexpectedly increased the risk for clinical mastitis in dairy cows. Furthermore, higher levels of oxidative stress in the postpartum period were related to higher risk of mastitis. The objective of the present study was to determine the relationship between various serum biomarkers of oxidative status, incidence of mastitis, and blood α-tocopherol concentrations at dry off and at calving. A total of 146 dairy cows from a commercial farm were used in an observational field study. All cows were supplemented with 3,000 and 50 IU/cow per day of all-rac-α-tocopherol during the dry period and lactation, respectively. Blood samples were collected at dry off and at calving. Serum was analyzed for α-tocopherol, levels of reactive oxygen metabolites (ROM), thiol groups (SH), and ferric-reducing ability. Three α-tocopherol groups at calving were created: high (>3 μg/mL), medium (2–3 μg/mL), and low (<2 μg/mL). Three α-tocopherol groups at dry off were created: high (>6.25 μg/mL), medium (4.25–6.25 μg/mL), and low (<4.25 μg/mL). All cases of clinical mastitis that occurred during the dry period and the entire subsequent lactation were verified by a veterinarian. No differences were observed in the incidence of mastitis between the 3 α-tocopherol groups based on the serum levels at dry off. Incidence of mastitis was 4 times lower in the high and medium groups when compared with the corresponding value for the low-α-tocopherol group based on the serum levels at calving. Lower levels of ROM and SH at dry off and at calving were found in the group of cows with the highest α-tocopherol values at dry off when compared with the corresponding values in the low-α-tocopherol group. The ROM values at dry off but not at calving were lower in the group of cows with the highest α-tocopherol values at calving when compared with the corresponding values in the low-α-tocopherol group. No differences were observed in ferric-reducing ability values between the 3 α-tocopherol groups at dry off or calving. No differences were observed in all biomarkers of oxidative status between healthy cows and those with mastitis. Thus, blood α-tocopherol is inversely related to certain biomarkers of oxidative stress in the postpartum period and incidence of mastitis. However, reduction in the incidence of mastitis is not mediated through a reduction in the levels of various biomarkers of oxidative stress.     

On the applicability of the load separation criterion in determining the fracture resistance (<Emphasis Type="Italic">J</Emphasis><Subscript>Ic</Subscript>) of ductile polymers at low and high loading rates

In this work, the applicability of a procedure based on the load separation criterion in determining the fracture resistance (J _Ic) of a rubber modified polyamide 66 (PA66) was analyzed and discussed. In particular, the effects of the testing conditions, with particular reference to geometry and loading rate, on the applicability of the method were investigated. The tests were performed both at low (from 0.5 to 50 mm/min) and moderately high (0.6 m/s) loading rates, on single edge notched in bending specimens with different initial crack length to width ratios (a ₀/W), which ranged between 0.3 and 0.7. Among the various findings it is worthwhile to point out that this analysis revealed that the plastic displacement at the end of the blunting process (at fracture initiation) resulted geometry independent. A clear dependence of such a parameter on the loading rate was observed. Further, it was shown that load separation is maintained beyond the blunting phase, as observed in the experiments carried out at low rate.