Direct-write three-dimensional nanofabrication of nanopyramids and nanocones on Si by nanotumefaction using a helium ion microscope.

The recently commercialized helium ion microscope (HIM) has already demonstrated its outstanding imaging capabilities in terms of resolution, surface sensitivity, depth of field and ease of charge compensation. Here, we show its exceptional patterning capabilities by fabricating dense lines and three-dimensional (3D) nanostructures on a Si substrate. Small focusing spot size and confined ion-Si interaction volume of a high-energy helium ion beam account for the high resolution in HIM patterning. We demonstrate that a set of resolvable parallel lines with a half pitch as small as 3.5 nm can be achieved. During helium ion bombardment of the Si surface, implantation outperforms milling due to the small mass of the helium ions, which produces tumefaction instead of depression in the Si surface. The Si surface tumefaction is the result of different kinetic processes including diffusion, coalescence and nanobubble formation of the implanted ions, and is found to be very stable structurally at room temperature. Under appropriate conditions, a linear dependence of the surface swollen height on the ion doses can be observed. This relation has enabled us to fabricate nanopyramids and nanocones, thus demonstrating that HIM patterning provides a new 'bottom-up' approach to fabricate 3D nanostructures. This surface tumefaction method is direct, both positioning and height accurate, and free of resist, etch, mode and precursor, and it promises new applications in nanoimprint mold fabrication and photomask clear defect reparation.

A novel polymorphic purine complex at the 1.5 kb upstream region of the human caveolin-1 gene and risk of Alzheimer's disease; extra-short alleles and accumulated allele homozygosity.

Crucial interaction of caveolin-1 (CAV1) with beta- and gamma-secretases, and aberrant expression of the gene encoding this protein in Alzheimer's disease (AD) support a role for CAV1 in the pathophysiology of this disease. We report a novel polymorphic purine complex stretching approximately 150 bp of genomic DNA at the 1.5 kb upstream region of the human CAV1 gene, alleles and genotypes of which are associated with sporadic late-onset AD. Extra-short alleles were observed in the case group that were absent in the control subjects. Remarkably, 63% of these alleles were observed to be homozygous in length, forming 23.7% of the homozygote length compartment in the AD cases (chi(2) = 19.08, df = 1, P < 0.000007). Increased homozygosity for length was also observed at this region in the Alzheimer's cases, for the allele lengths shared by the case and control groups [(chi(2) = 30.75, df = 1, P < 0.0000000, OR = 4.54, CI 95% (2.56-8.3)]. This region contains GGAA and GAAA motifs, the consensus binding sites for the Ets and IRF family transcription factors, respectively, and is highly conserved in distantly related non-human primates in respect with location and motif sequence. The effect of this complex sequence on the expression of CAV1, and the related mechanisms in the pathophysiology of AD remain to be clarified.

No association between the DAT1 10-repeat allele and ADHD in the Iranian population.

Association studies between attention-deficit hyperactivity disorder (ADHD) and the 10-repeat allele of a polymorphism (a 40 bp variable number of tandem repeats) in the dopamine transporter gene (DAT1) have resulted in mixed findings in different populations. We performed a case/control study to clarify the contribution of this allele with ADHD in the Iranian population. No association was observed between the 10-allele and disease (chi(2) = 0.081, P < 0.9). Furthermore, no significant difference was observed in the homozygosity of this allele between the case and control groups (chi(2) = 0.022, P < 0.9). Implication of the dopamine transporter gene in the pathophysiology of ADHD warrants investigation of other functional polymorphisms within this gene in the Iranian ADHD patients.

Successful implantation and immediate activation of Vagus Nerve Stimulation (VNS) during pregnancy in a patient with intractable epilepsy: A case illustration and review of the literature.

While Vagus Nerve Stimulation (VNS) is proven to be a safe and effective adjunctive therapy in the general population with medically intractable seizures, little is published about its implantation during pregnancy. Here we illustrate the case of a 21year old primigravid woman with medically refractory seizures who underwent safe and successful VNS implantation and immediate activation of the device in her 32nd week of pregnancy, resulting in dramatically improved seizure control and subsequent delivery of a healthy baby.