The directed self-assembly of block copolymer (BCP) offers a new route to perfect nanolithographic patterning at sub-50 nm length scale with molecular scale precision. We have explored the feasibility of using the BCP approach versus the conventional electron beam (e-beam) lithography to create highly dense dot patterns for bit-patterned media (BPM) applications. Cylinder-forming poly(styrene-b-methyl methacrylate) (PS-b-PMMA) directly self-assembled on a chemically prepatterned substrate. The nearly perfect hexagonal arrays of perpendicularly oriented cylindrical pores at a density of approximately 1 Terabit per square inch (Tb/in.(2)) are achieved over an arbitrarily large area. Considerable gains in the BCP process are observed relative to the conventional e-beam lithography in terms of the dot size variation, the placement accuracy, the pattern uniformity, and the exposure latitude. The maximum dimensional latitude in the cylinder-forming BCP patterns and the maximum skew angle that the BCP can tolerate have been investigated for the first time. The dimensional latitude restricts the formation of more than one lattice configuration in certain ranges. More defects in BCP patterns are observed when using low molecular weight BCP materials or on non-hexagonal prepatterns due to the dimensional latitude restriction. Finally, the limitations and challenges in the BCP approach that are associated with BPM applications will be briefly discussed.

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Electron beam lithography presents a great opportunity for bit-patterned media (BPM) applications due to its resolution capability and placement accuracy. However, there are still many challenges associated with this application including tool availability, resist capability, process development, and associated metrology needs. This paper will briefly discuss these challenges and show the results of sub-25 nm pitch (1 Tdots∕in.2) patterning from both a simulation and experimental perspective. The simulation results indicate that the energy contrast between the exposed and unexposed areas goes down quickly as the pitch size gets smaller and smaller, making it more difficult for image formation of high-resolution dot patterning. The strategy to overcome this issue is to optimize the development process, which aims at increasing the resist contrast and enlarging the process window. By using this approach, the authors have successfully demonstrated a pitch resolution down to 18 nm for a positive-tone resist ZEP520 and 12 nm for a negative-tone resist silsesquioxane, corresponding to the areal density of ∼2.0 and ∼4.5 Tdots∕in.2, respectively. Using the ZEP520 resist process, a Cr dot array with a pitch of 21 nm (∼1.5 Tdots∕in.2) for template fabrication is demonstrated. High-quality scanning electron microscopy and atomic force microscopy images were used as primary metrology for both the dot size uniformity and the placement accuracy analysis.

Codelivery of combinational antigenic peptides and adjuvant to antigen presenting cells is expected to amplify tumor specific T lymphocytes immune responses while minimizing the possibility of tumor escaping and reducing immune tolerance to single antigenic peptide. However, the varied hydrophobicities of these multivariant derived short antigenic peptides limit their codelivery efficiency in conventional delivery systems. Here, a facile yet effective route is presented to generate monodisperse and stable hollow mesoporous silica nanoparticles (HMSNs) for codelivering of HGP100 and TRP2 , two melanoma-derived peptides with varied hydrophobicities. The HMSNs with large pore size can improve the encapsulation efficiency of both HGP100 and TRP2 after NH modification on the inner hollow core and COOH modification in the porous channels. HGP100 and TRP2 loaded HMSNs (HT@HMSNs) are further enveloped within monophosphoryl lipid A adjuvant entrapped lipid bilayer (HTM@HMLBs), for improved stability/biocompatibility and codelivery efficiency of multiple peptides, adjuvant, and enhanced antitumor immune responses. HTM@HMLBs increase uptake by dendritic cells (DCs) and stimulate DCs maturation efficiently, which further induce the activation of both tumor specific CD8 and CD4 T lymphocytes. Moreover, HTM@HMLBs can significantly inhibit tumor growth and lung metastasis in murine melanoma models with good safety profiles. HMSNs enveloped with lipid bilayers (HMLBs) are believed to be a promising platform for codelivery of multiple peptides, adjuvant, and enhancement of antitumor efficacy of conventional vaccinations.

Nanoimprint lithography presents unique opportunities for patterned media applications due to its advantages of sub-10nm resolution capability, patterning of a whole disk in a single imprint step with reasonably high throughput, and the relatively low capital cost in comparison to other next generation lithography technologies. However, there are several critical issues that still remain very challenging. This article will briefly discuss these challenges in general and then focus on imprint lithography work including the fabrication of templates and demonstrate the imprinted results. In this work two types of polarities of high-density templates (pillar tone and hole tone) have been fabricated on fused silica substrates for the UV imprint process. The difficulties and limitations in each of the template fabrication processes will be discussed. The authors have successfully demonstrated template fabrication followed by imprinted results with a pitch of 24nm (1.1Tdots∕in.2) for both tones of templates. Initial imprinted results of dense dot patterns with a pitch as small as 18nm (2.0Tdots∕in.2) have been achieved. High-resolution scanning electron microscopy images are used as the primary metrology for both the dot size uniformity and the placement accuracy analysis. The difficulties and the limitations in template fabrication, the imprint process, and associated metrology will be discussed.

Fertilization of crops with pig manure is a common practice throughout the world. Nevertheless, due to the relatively high copper (Cu) and zinc (Zn) contents in pig manure, continuous application of pig manure could have negative effects on soil and plant. The study aimed at the impacts of long-term applying different pig manure rates (equivalently 0, 100, 250 and 500 kg total N/ha/year from 2002 to 2008 and 0, 10, 25 and 50 t fresh weight/ha/year from 2009 to 2011, respectively) on Cu and Zn accumulation in soil and plant. During the 10 years of the experiment, a total of 2.04 to 10.20 kg/ha/year for Cu, 3.15 to 15.73 kg/ha/year for Zn were applied to the soil. Results from this study showed that long-term pig manure application resulted in serious accumulation of Cu and Zn in soil, total Cu and Zn concentrations increased by 204% and 107% at high application rates, respectively. Although topsoil Cu and Zn concentrations were below concentrations considered phytotoxic to crops, according to current Chinese legislation, it would take only less time than 16 and 27 years of high application rates to reach the allowable limits. Our result also suggested that Cu and Zn leaching occurred in the tested soil. The Cu and Zn concentrations in stalks and grains were not affected by the application of pig manure, and these values were lower than the threshold values for animal and human ingestion.

As the main form of land use and human disturbance of grassland, livestock grazing has great influences on the soil resources and plant communities. This study observed the variation of soil properties and community characteristics of four treatments of different grazing intensity (no grazing, UG; light grazing, LG; moderate grazing, MG; and heavy grazing, HG) in an alpine meadow of Sichuan Province on the northeastern margin of the Tibetan Plateau. The results showed that grazing increased the pH, soil bulk density (BD), and contents of total carbon (TC) and total nitrogen (TN), and the BD increased while the others decreased with the grazing intensity. At the community level, with the increase of the grazing intensity, the vegetation coverage (R 2 = 0.61, P < 0.001), mean height of community (R 2 = 0.37, P < 0.001), aboveground biomass (R 2 = 0.54, P < 0.001), litter biomass (R 2 = 0.84, P < 0.001), and percentage of aboveground biomass of palatable grasses to total biomass (R 2 = 0.74, P < 0.001) significantly decreased, while the belowground biomass (R 2 = 0.72, P < 0.001) and the root/shoot (R/S) ratio (R 2 = 0.65, P < 0.001) increased. The species richness was the greatest at LG and the total biomass at UG. With grazing, the dominant species of the plant community shifted from palatable grasses (Gramineae and Cyperaceae) to unpalatable grasses (Compositae and Ranunculaceae). Based on the results, LG may be the optimal grassland management mode to be used in the long time in the alpine meadow of the Tibetan Plateau.