کتاب 2014 با موضوع سمیت نانو

کتاب 2014 با موضوع نانوتکنولوژی در سیستم های امنیتی

ترکیب سل‌ژل و اسیدچرب برای ساخت خازن

@nanotech1
محققان با استفاده از لایه نازکی از جنس اسید چرب و ترکیب آن با هیدروژل، موفق به ساخت خازنی با دانسیته جریان بالا شدند. این خازن می‌تواند در خودروهای برقی استفاده شود.
محققان با استفاده از ترکیب سل‌ژل با ترکیبات تک‌لایه خودآرا از جنس اسید چرب موفق به ساخت ماده دی‌الکتریکی جدیدی برای خازن‌ها شدند. با استفاده از این ماده جدید هم امکان تولید دانسیته انرژی بالایی وجود دارد و هم دانسیته توان بالایی ایجاد می‌شود.
در صورتی که ساخت این ماده تجاری‌سازی شود آنگاه می‌توان ظرفیت خازن‌ها را تا حدی بالا برد که بتوان از آن در خودروهای برقی استفاده کرد. خازن‌ها مکمل باتری‌ها هستند و مزیت آنها، امکان ایجاد سریع جریان بالا است.
این ماده جدید از جنس لایه نازک سل‌ژل سیلیکا بوده که حاوی گروه‌های قطبی است که به اتم‌های سیلیکون لینک شده‌است. همچنین تک لایه خودآرا از جنس اسید استیل‌فسفونیک در این ساختار استفاده شده‌است که نقش ماده عایق را ایفا می‌کند.
ژوزف پری از محققان موسسه فناوری جرجیا می‌گوید: «سل‌ژل با گروه‌های آلی بسیار شناخته شده هستند، همچنین اسیدهای چربی نظیر اسید فسفونیک نیز برای محققان آشنا است. اما این اولین باری است که این دو ماده با هم ترکیب شده و در دستگاه ذخیره انرژی با دانسیته بالا استفاده می‌شود.»
نتایج این پروژه در قالب مقاله‌ای با عنوان Bilayer Structure with Ultra-high Energy/Power Density Using Hybrid Sol-Gel Dielectric and Charge Blocking Monolayer در نشریه Advanced Energy Materials منتشر شده‌‌است.
نیاز به مواد با کارایی بالا برای ذخیره انرژی الکتریکی در حال رشد است. مواد دی الکتریکی امکان شارژ و تخلیه سریع را فراهم می‌کنند. اما این که بتوان ماده‌ای یافت که هم نفوذپذیری بالایی داشته باشد، مستحکم باشد و امکان ایجاد دانسیته انرژی بالایی را داشته باشد بسیار دشوار است.
این گروه تحقیقاتی به دنبال ساخت ماده‌ای با این شرایط برای استفاده در خازن‌ها هستند. این هیبرید سل‌ژل دارای پتانسیل بالایی برای به کارگیری در ذخیره انرژی است؛ به همین دلیل، محققان تصمیم گرفتند تا از آن در ساخت خازن استفاده کنند.
این گروه با استفاده از فیلم آلومینیومی حاوی پوششی از این سل‌ژل اقدام به ساخت خازنی کردند که دانسیته جریان بسیار بالایی ایجاد کرده و کاملا انعطاف‌پذیر است. این ابرخازن نشت جریان داشت که برای حل آن محققان از تک لایه‌های خودآرا از جنس اسید چرب استفاده کردند؛ لایه‌ای که ضخامت یک نانومتری دارد. از این لایه به‌عنوان عایق در این پروژه استفاده شد. http://news.nano.ir/51566/1

کتاب 2012 با عنوان nano antimicrobials

Scanning near-field optical microscopy (SNOM) uses nanoscale metal tips to scan a surface.

Read more: Blow-up: The startling landscapes of

Scanning near-field optical microscopy (SNOM) uses nanoscale metal tips to scan a surface. Here, a standard tip has been modified and sharpened to increase its precision. The tip in the middle of this structure measures a few tens of nanometers.

Read more: Blow-up: The startling landscapes of nanotechnology

AFM tip

Developing new instruments to be able to "see" at the nanoscale is a research field in itself. Shown here is the tip of an atomic force microscope (AFM), one of the foremost tools for imaging, measuring and manipulating matter at the nanoscale. Here, a platinum electrode measuring one hundredth of a nanometer has been deposited on the tip of this pyramid shaped AFM tip via focused ion beam (FIB) deposition.

Read more: Blow-up: The startling landscapes of nanotechnology

Top view of a hole carved in a polyethylene surface.

Top view of a hole carved in a polyethylene surface. During a series of experiments the use of a FIB has proven to be very versatile and capable of carving various materials, including plastic.

Read more: Blow-up: The startling landscapes of nanotechnology

کنفرانس سیستم‌های بس‌ذره‌ای (کپه‌ای و نانو مقیاس) -مورد حمایت ستاد نانو

گزیده ای از مقالات اخرین جلد ژورنال ACS NANO:

@nanotech1 We propose a semiconductor–insulator–semiconductor (SIS) heterojunction diode consisting of monolayer (1-L) MoS2, hexagonal boron nitride (h-BN), and epitaxial p-GaN that can be applied to high-performance nanoscale optoelectronics. The layered materials of 1-L MoS2 and h-BN, grown by chemical vapor deposition, were vertically stacked by a wet-transfer method on a p-GaN layer. The final structure was verified by confocal photoluminescence and Raman spectroscopy. Current–voltage (I–V) measurements were conducted to compare the device performance with that of a more classical p–n structure. In both structures (the p–n and SIS heterojunction diode), clear current-rectifying characteristics were observed. In particular, a current and threshold voltage were obtained for the SIS structure that was higher compared to that of the p–n structure. This indicated that tunneling is the predominant carrier transport mechanism. In addition, the photoresponse of the SIS structure induced by the illumination of visible light was observed by photocurrent measurements. http://pubs.acs.org/doi/abs/10.1021/acsnano.5b04233

In metal-enhanced fluorescence (MEF), the localized surface plasmon resonances of metallic nanostructures amplify the absorption of excitation light and assist in radiating the consequent fluorescence of nearby molecules to the far-field. This effect is at the base of various technologies that have strong impact on fields such as optics, medical diagnostics, and biotechnology. Among possible emission bands, those in the near-infrared (NIR) are particularly intriguing and widely used in proteomics and genomics due to its noninvasive character for biomolecules, living cells, and tissues, which greatly motivates the development of effective and, eventually, multifunctional NIR-MEF platforms. Here, we demonstrate NIR-MEF substrates based on Au nanocages micropatterned with a tight spatial control. The dependence of the fluorescence enhancement on the distance between the nanocage and the radiating dipoles is investigated experimentally and modeled by taking into account the local electric field enhancement and the modified radiation and absorption rates of the emitting molecules. At a distance around 80 nm, a maximum enhancement up to 2–7 times with respect to the emission from pristine dyes (in the region 660–740 nm) is estimated for films and electrospun nanofibers. Due to their chemical stability, finely tunable plasmon resonances, and large light absorption cross sections, Au nanocages are ideal NIR-MEF agents. When these properties are integrated with the hollow interior and controllable surface porosity, it is feasible to develop a nanoscale system for targeted drug delivery with the diagnostic information encoded in the fluorophore. @nanotech1 http://pubs.acs.org/doi/abs/10.1021/acsnano.5b03624

Two-dimensional (2D) materials present many unique materials concepts, including material properties that sometimes differ dramatically from those of their bulk counterparts. One of these properties, piezoelectricity, is important for micro- and nanoelectromechanical systems applications. Using symmetry analysis, we determine the independent piezoelectric coefficients for four groups of predicted and synthesized 2D materials. We calculate with density-functional perturbation theory the stiffness and piezoelectric tensors of these materials. We determine the in-plane piezoelectric coefficient d11 for 37 materials within the families of 2D metal dichalcogenides, metal oxides, and III–V semiconductor materials. A majority of the structures, including CrSe2, CrTe2, CaO, CdO, ZnO, and InN, have d11 coefficients greater than 5 pm/V, a typical value for bulk piezoelectric materials. Our symmetry analysis shows that buckled 2D materials exhibit an out-of-plane coefficient d31. We find that d31 for 8 III–V semiconductors ranges from 0.02 to 0.6 pm/V. From statistical analysis, we identify correlations between the piezoelectric coefficients and the electronic and structural properties of the 2D materials that elucidate the origin of the piezoelectricity. Among the 37 2D materials, CdO, ZnO, and CrTe2 stand out for their combination of large piezoelectric coefficient and low formation energy and are recommended for experimental exploration. @nanotech1 http://pubs.acs.org/doi/abs/10.1021/acsnano.5b03394

We report on the facile fabrication of a stretchable array of highly sensitive pressure sensors. The proposed pressure sensor consists of the top layer of Au-deposited polydimethylsiloxane (PDMS) micropillars and the bottom layer of conductive polyaniline nanofibers on a polyethylene terephthalate substrate. The sensors are operated by the changes in contact resistance between Au-coated micropillars and polyaniline according to the varying pressure. The fabricated pressure sensor exhibits a sensitivity of 2.0 kPa–1 in the pressure range below 0.22 kPa, a low detection limit of 15 Pa, a fast response time of 50 ms, and high stability over 10000 cycles of pressure loading/unloading with a low operating voltage of 1.0 V. The sensor is also capable of noninvasively detecting human-pulse waveforms from carotid and radial artery. A 5 × 5 array of the pressure sensors on the deformable substrate, which consists of PDMS islands for sensors and the mixed thin film of PDMS and Ecoflex with embedded liquid metal interconnections, shows stable sensing of pressure under biaxial stretching by 15%. The strain distribution obtained by the finite element method confirms that the maximum strain applied to the pressure sensor in the strain-suppressed region is less than 0.04% under a 15% biaxial strain of the unit module. This work demonstrates the potential application of our proposed stretchable pressure sensor array for wearable and artificial electronic skin devices. @nanotech1 http://pubs.acs.org/doi/abs/10.1021/acsnano.5b03510