The fabrication of electrical interconnects to provide power for and communication with computers as their component complementary metal oxide semiconductor (CMOS) devices continue to shrink in size presents significant materials and processing compatibility challenges. We describe here our efforts to address these challenges using top-surface imaging and hybrid photoresist/self-assembled monolayer patterning approaches, in conjunction with selective electroless metal deposition, to develop processes capable of fabricating appropriate submicron and nanoscale metal features useful as electrical interconnects, as well as plasma-etch-resistant masks and metal diffusion barriers. Our efforts focus on the development of cost-effective methods compatible with a manufacturing environment that satisfy materials and process constraints associated with CMOS device production. We demonstrate the fabrication of approximately 50-nm-width features in metal with high fidelity and sufficient control of edge acuity to satisfy current industry design rules using our processes and discuss the challenges and opportunities for fabrication of analogous sub-10-nm metal features.

NSR1 is a yeast nuclear localization sequence-binding protein showing striking similarity in its domain structure to nucleolin. Cells lacking NSR1 are viable but have a severe growth defect. We show here that NSR1, like nucleolin, is involved in ribosome biogenesis. The nsrl mutant is deficient in pre-rRNA processing such that the initial 35S pre-rRNA processing is blocked and 20S pre-rRNA is nearly absent. The reduced amount of 20S pre-rRNA leads to a shortage of 18S rRNA and is reflected in a change in the distribution of 60S and 40S ribosomal subunits; there is no free pool of 40S subunits, and the free pool of 60S subunits is greatly increased in size. The lack of free 40S subunits or the improper assembly of these subunits causes the nsrl mutant to show sensitivity to the antibiotic paromomycin, which affects protein translation, at concentrations that do not affect the growth of the wild-type strain. Our data support the idea that NSR1 is involved in the proper assembly of pre-rRNA particles, possibly by bringing rRNA and ribosomal proteins together by virtue of its nuclear localization sequence-binding domain and multiple RNA recognition motifs. Alternatively, NSR1 may also act to regulate the nuclear entry of ribosomal proteins required for proper assembly of pre-rRNA particles.In eukaryotic cells, the nucleolus is a specialized subcompartment in which ribosome biogenesis occurs. Pre-rRNA first is transcribed from rDNA genes located in the nucleolus and then undergoes a series of modifications. Ribosomal proteins are imported from the cytoplasm and packed onto the RNA molecule. At the same time, the primary transcript goes through sequential cleavages to generate mature forms of rRNA. Finally, the newly formed ribosomal particles are exported to the cytoplasm.In the yeast Saccharomyces cerevisiae, the largest detectable transcript from the rDNA genes is a 35S pre-rRNA (17), which is rapidly processed into three molecules: the 18S rRNA assembled into 40S ribosomal subunits and the 5.8S and 25S rRNAs found in 60S subunits (Fig. 1). During or immediately after transcription of the rDNA genes, the pre-rRNA is modified, mainly by methylation (32, 34). Meanwhile, a large number of ribosomal proteins and nonribosomal components (including proteins and RNA) associate with the pre-rRNA to form a 90S preribosomal particle. This particle is then split into 66S and 43S preribosomal particles, which are the precursors of the 60S and 40S subunits, respectively (31). While the 66S particles mature completely within the nucleus, the final maturation steps of the 43S particles, including the processing of 20S to 18S rRNA, are completed in the cytoplasm (31,33).Only a few mutations that block specific steps in the pre-rRNA processing pathway have been found. One example is a temperature-sensitive mutation in a gene designated RRPJ that was shown to prevent the 27S-to-25S rRNA cleavage step specifically (1). In another mutant, CLP-8, the efficiency of the processing of 20S to 18S rRNA is greatly reduced, apparently because...

Single domain antibodies are the recombinantly expressed binding fragments derived from heavy chain antibodies found in camels and llamas. These unique binding elements offer many desirable properties such as their small size ( approximately 15 kDa) and thermal stability, which makes them attractive alternatives to conventional monoclonal antibodies. We created a phage display library from llamas immunized with ricin toxoid and selected a number of single domain antibodies. Phage selected on ricin were found to bind to either ricin A chain or the intact molecule; no ricin B chain binders were identified. By panning on B chain, we identified binders and have characterized their binding to the ricin B chain. While they have a poorer affinity than the previously described A chain binders, it was found that they performed dramatically better as capture reagents for the detection of ricin, providing a limit of detection in enzyme linked immunosorbent assay (ELISA) below 100 pg/mL and excellent specificity for ricin versus the highly related RCA 120 (1 to 10 000). We also reevaluated the previously isolated antiricin single domain antibody binding kinetics using surface plasmon resonance and found their K(d)s matched closely to those previously obtained under equilibrium binding conditions measured using the Luminex flow cytometer.

binding sites), [27] as well as with the trapping of size-selected Ag clusters of steps when the clusters are deposited at low energy. [28] The fact that the ªunpinningº temperature is not exactly the same for each pinned cluster is probably attributable to a combination of thermal statistics and the (small) range of cluster±surface impact parameters in the collision, although for clusters as large as 70 atoms in size, the latter is not expected to be a large effect. [29] In summary, the stability of pinned, size-selected gold clusters (Au 70 + ) on a graphite surface at high temperatures has been investigated. The stability of the pinned clusters against lateral diffusion to step edges (i.e., unpinning) increases with the initial cluster±surface impact energy, consistent with shallow implantation of the clusters well above the threshold energy for pinning. Size-selected cluster films which are stable even at several hundred degrees above room temperature can thus be generated, opening up potential applications in studies of physical, chemical, and biological behavior at elevated temperatures. ExperimentalThe Au 70 + clusters were produced with a magnetron-sputtering, gas-condensation cluster-beam source and lateral time-of-flight mass filter as described previously [12,22]. The clusters were deposited in a high-vacuum chamber to achieve a coverage of~1 10 11 clusters per square centimeter on freshly cleaved graphite substrates (highly oriented pyrolytic graphite) and then transferred in a vacuum suitcase to a variable-temperature scanning tunneling microscope (STM, Omicron) housed in an ultrahigh-vacuum (UHV) system. Two samples were prepared at room temperature: sample A, where the Au 70 + clusters were deposited with a kinetic energy of 1.2 keV (17 eV per atom), and sample B, where the Au 70 + cluster deposition energy was 1.7 keV (24 eV per atom). Thermal annealing was carried out for both samples in the UHV STM system by raising the temperature to a specific value for a period of two hours. During heating, the STM tip was moved away from the area of interest in order to avoid tip-induced effects. STM imaging was performed after cooling down to room temperature. The same area was scanned before and after heating wherever possible, but at high annealing temperatures, excessive thermal drift prevented the imaging of the same area. However, a sufficient number of images were taken after each annealing cycle to make sure that changes observed in different images are caused by thermal annealing and not due to regional variations. Under the imaging conditions typically applied, no tip-induced changes to the pinned clusters were observed at room temperature, which allowed us to conclude that the observed changes are primarily due to thermal effects.

New methods for antimicrobial design are critical for combating pathogenic bacteria in the post-antibiotic era. Fortunately, competition within complex communities has led to the natural evolution of antimicrobial peptide (AMP) sequences that have promising bactericidal properties. Unfortunately, the identification, characterization, and production of AMPs can prove complex and time consuming. Here, we report a peptide generation framework, PepVAE, based around variational autoencoder (VAE) and antimicrobial activity prediction models for designing novel AMPs using only sequences and experimental minimum inhibitory concentration (MIC) data as input. Sampling from distinct regions of the learned latent space allows for controllable generation of new AMP sequences with minimal input parameters. Extensive analysis of the PepVAE-generated sequences paired with antimicrobial activity prediction models supports this modular design framework as a promising system for development of novel AMPs, demonstrating controlled production of AMPs with experimental validation of predicted antimicrobial activity.