The authors thank the DFG (Hu 997/2-2) for financial support. FS acknowledges the Hanns-Seidel-Stiftung (HSS). SKr was supported by the Elitenetzwerk Bayern in the framework of the doctorate program Material Science of Complex Interfaces. SKi thanks the SFB 863 for financial support.

<ol>
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The authors declare that they have no competing financial interests.

<html> خلال العقود الماضية، قدمت التجارب جزيء واحد رؤى غير مسبوقة في الآليات الجزيئية وتبين أن هذا النهج لا تقدر بثمن في علوم الحياة وخارجها. لتحقيق إحصاءات جيدة وذات مغزى من التجارب SMFS، من الناحية المثالية واحد ويتم استخدام نفس الجزيء على مدى كاملة من التجربة. وعلى الن?...

على مدى السنوات ال 30 الماضية، تحولت القوة الذرية المجهر (AFM) إلى أن تكون تقنية التصوير قيمة لدراسة البيولوجية 1،2 و 3 الاصطناعية المواد والأسطح لأنه يوفر القرار المكانية الجزيئي في جميع الأبعاد الثلاثة ويمكن تشغيلها في مختلف المذيبات البيئات. وبالإضافة إلى ذلك،-AFM واحد قوة جزيء الطيفي (SMFS) يتيح لقياس القوى بدءا من السندات الإذنية إلى μN النظام وأعطت نظرة غير مسبوقة على سبيل المثال إلى البروتين للطي 4،5، الفيزياء البوليمر 6-8، واحد التفاعل جزيء سطح 9 - 12. والأساس المنطقي وراء دراسة الجزيئات واحدة بدلا من الفرقة من الجزيئات هو تجنب آثار المتوسط ​​والتي غالبا ما تحجب الأحداث النادرة أو الدول الجزيئية الخفية. وعلاوة على ذلك، العديد من المعلمات الجزيئية مثل طول كفاف، وطول كوهن، الطاقة الحرة التصاق، وما يمكن أن يكونالتي تم الحصول عليها. هو مفصل في هذه الأمثلة أدناه. في تجربة AFM-SMFS نموذجية، ويقترن جزيء التحقيق إلى طرف حاد جدا عن طريق جزيء رابط. يقع في الطرف نفسها في نهاية ناتئ قابل للانحناء. إذا تم إحضار طرف في اتصال مع سطح جزيء التحقيق سوف تتفاعل مع هذا السطح. من خلال مراقبة انحراف للناتئ على التراجع من طرف، والقوة، وبالتالي الطاقة الحرة، لفصل جزيء من السطح يمكن تحديده. الحصول على إحصائيات ذات معنى، لا بد من الحصول على عدد كبير من ما يسمى منحنيات قوة بعد. وعلاوة على ذلك، لدينا تجارب جزيء واحد صحيح (أي، وذلك باستخدام واحد ونفس جزيء التحقيق خلال مدة التجربة بأكملها) يجب أن يقترن جزيء التحقيق تساهميا إلى الطرف AFM. هنا، يتم تقديم بروتوكول تجريبي لناتئ functionalization مع جزيء واحد عن طريق الرابطة التساهمية. يمكن إما أن يقترن جزيء واحد عن طريق الأمينية أو ثيول مجموعة لغيض AFM. لا يمكن أن يؤديها عملية الاقتران في مجموعة واسعة من المذيبات (العضوية والمائية) لحساب خصائص انذياب من البوليمرات المستخدمة. في الجزء الأول، وبروتوكول عام لنعلق تساهميا جزيء واحد (&quot;جزيء التحقيق&quot;) عن طريق جزيء رابط إلى طرف AFM يوصف. تحقيقا لهذه الغاية، يتم استخدام NHS- العضوية أو maleimide الكيمياء 13. جنبا إلى جنب مع بروتوكول لمدة ثلاث جزيئات سبيل المثال، يتم وصف عمليات الحصول على البيانات وتحليل البيانات ويتم توفير المراجع لمزيد من القراءة. على سبيل المثال الجزيئات هي: (الخطية) التيروزين البوليمر، البوليمر الكسب غير المشروع PI- ز -PS والبابا الدهون. وهذا يشمل اختلافات طفيفة من البروتوكول، على سبيل المثال لنعلق تساهميا cysteines. وبالإضافة إلى ذلك، وهناك قسم مخصص لإعداد الأسطح المختلفة مثل سطح الماس، وCH 3-تجميعها المتمتعة بالحكم الذاتي أحادي الطبقة وطبقات ثنائية الدهون. هذه الواجهات لها الأقليمأون بمثابة إشارات جيدة والأمثلة على ذلك.

<table border="0" cellpadding="0" cellspacing="0">
	<tbody>
		<tr>
			<td>Materials</td>
			<td></td>
			<td></td>
			<td></td>
		</tr>
		<tr>
			<td>Hellmanex III alkaline liquid concentrate (detergent solution)</td>
			<td>Hellma</td>
			<td></td>
			<td></td>
		</tr>
		<tr>
			<td>RCA (ultrapure water, hydrogen peroxide (35 %), ammonia (32%); 5:1:1(v/v/v))</td>
			<td>Sigma</td>
			<td></td>
			<td></td>
		</tr>
		<tr>
			<td>Vectabond reagent / APTES (3-Aminopropyl)triethoxysilane</td>
			<td>Vectorlabs</td>
			<td></td>
			<td></td>
		</tr>
		<tr>
			<td>Dry acetone (&#60; 50 ppm H2O)</td>
			<td>Sigma</td>
			<td></td>
			<td></td>
		</tr>
		<tr>
			<td>Dry chloroform (&#62; 99.9 %)</td>
			<td>Sigma</td>
			<td></td>
			<td></td>
		</tr>
		<tr>
			<td>Triethylamine</td>
			<td>Sigma</td>
			<td></td>
			<td></td>
		</tr>
		<tr>
			<td>Ultrapure water</td>
			<td>Biochrom, Germany</td>
			<td></td>
			<td></td>
		</tr>
		<tr>
			<td>Di-sodium tetraborate (&#62; 99.5 %)</td>
			<td>Biochrom, Germany</td>
			<td></td>
			<td></td>
		</tr>
		<tr>
			<td>Boric Acid</td>
			<td>Biochrom, Germany</td>
			<td></td>
			<td></td>
		</tr>
		<tr>
			<td>Monofunctional &#945;-methoxy-&#969;-NHS PEG, 5kDa, &#8220;methyl-PEG-NHS&#8221;</td>
			<td>Rapp, Germany</td>
			<td></td>
			<td></td>
		</tr>
		<tr>
			<td>Heterobifunctional &#945;,&#969;-bis-NHS PEG, 6 kDa, &#8220;NHS-PEG-NHS&#8221;</td>
			<td>Rapp, Germany</td>
			<td></td>
			<td></td>
		</tr>
		<tr>
			<td>Heterobifunctional &#945;-maleimidohexanoic- &#969;-NHS PEG, 5 kDa, &#8220;Mal-PEG-NHS&#8221;</td>
			<td>Rapp, Germany</td>
			<td></td>
			<td></td>
		</tr>
		<tr>
			<td>Probe molecule (polymer, lipid, etc.)</td>
			<td></td>
			<td></td>
			<td></td>
		</tr>
		<tr>
			<td></td>
			<td></td>
			<td></td>
			<td></td>
		</tr>
		<tr>
			<td>Equipment</td>
			<td></td>
			<td></td>
			<td></td>
		</tr>
		<tr>
			<td>Sufficient amount of glass crystallising dishes with spout (10 ml), glass petri dishes (500 &#181;l) and glass lids</td>
			<td>VWR International GmbH, Germany</td>
			<td></td>
			<td></td>
		</tr>
		<tr>
			<td>Laboratory oven model UF30</td>
			<td>Memmert, Germany</td>
			<td></td>
			<td></td>
		</tr>
		<tr>
			<td>Temperature controlled sonicator</td>
			<td>VWR International GmbH, Germany</td>
			<td></td>
			<td></td>
		</tr>
		<tr>
			<td>Plasma system &#34;Femto&#34;, 100 W</td>
			<td>Diener, Germany</td>
			<td></td>
			<td></td>
		</tr>
		<tr>
			<td>One separate glass syringe for each organic solvent</td>
			<td>VWR International GmbH, Germany</td>
			<td></td>
			<td></td>
		</tr>
		<tr>
			<td>Vortex mixer</td>
			<td>VWR International GmbH, Germany</td>
			<td></td>
			<td></td>
		</tr>
		<tr>
			<td>Microcentrifuge tubes (0.5 ml or 1.5 ml)</td>
			<td>Eppendorf</td>
			<td></td>
			<td></td>
		</tr>
		<tr>
			<td>Pipettes: 10-100 &#181;l, 50-200 &#181;l and 100-1000 &#181;l</td>
			<td>Eppendorf</td>
			<td></td>
			<td></td>
		</tr>
		<tr>
			<td>AFM with temperature controlled fluid cell (e.g. MFP-3D with BioHeater)</td>
			<td>Asylulm Research, Santa Barbara</td>
			<td></td>
			<td></td>
		</tr>
		<tr>
			<td>Soft SiN cantilevers cantilever, typically made from silicon nitride (SiN) (spring constant less than 100 pN/nm, e.g. MLCT)</td>
			<td>Bruker AXS, Santa Barbara</td>
			<td></td>
			<td></td>
		</tr>
	</tbody>
</table>

investigating single molecule adhesion by atomic force spectroscopy

التحليل الطيفي القوة الذرية هو أداة مثالية لدراسة الجزيئات في الأسطح والواجهات. ويرد بروتوكول تجريبي لزوجين مجموعة كبيرة ومتنوعة من الجزيئات واحدة تساهميا على تلميح AFM. في نفس الوقت وتخمل طرف AFM لمنع التفاعلات غير محددة بين طرف والركيزة، الذي هو شرط أساسي لدراسة الجزيئات واحدة تعلق على طرف AFM. تحليلات لتحديد قوة التصاق، وطول التصاق، والطاقة الحرة من هذه الجزيئات على الأسطح الصلبة والحيوية واجهات يتم عرض قريبا ويتم توفير المراجع الخارجية لمزيد من القراءة. جزيئات سبيل المثال هي بولي (حمض أميني) polytyrosine، والكسب غير المشروع البوليمر PI- ز -PS والبابا فوسفورية (1-بالميتويل-2-oleoyl- SN -glycero-3-phosphoethanolamine). والمستوعبة هذه الجزيئات من الأسطح المختلفة مثل CH 3 -SAMs والهيدروجين إنهاء الماس وبدعم طبقات ثنائية الدهون في ظل ظروف المذيبات المختلفة. وأخيرا، فإنوتناقش مزايا القوة الطيفية التجارب جزيء واحد بما في ذلك وسيلة لتقرر ما إذا كان قد تم دراستها حقا جزيء واحد في التجربة.

في ما يلي، نتائج ما سبق ووصفت جزيئات سبيل المثال، وهي بوليمرات بولي (حمض أميني) polytyrosine، والكسب غير المشروع البوليمر PI- ز -PS والبابا فوسفورية، وتعرض. أولا لكل سبيل المثال، تجربة تفاصيل محددة للحصول على البيانات وإعداد البيانات يتم توفيرها. ثم، يتم عرض نتائج نموذجي...

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Investigating Single Molecule Adhesion by Atomic Force Spectroscopy

A protocol to couple a large variety of single molecules covalently onto an AFM tip is presented. Procedures and examples to determine the adhesion force and free energy of these molecules on solid supports and bio-interfaces are provided.

التحقيق احدة جزيء التصاق بواسطة القوة الذرية الطيفي

Atomic force spectroscopy is an ideal tool to study molecules at surfaces and interfaces. An experimental protocol to couple a large variety of single ...

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10.3K Views.  Technische Universität München. A protocol to couple a large variety of single molecules covalently onto an AFM tip is presented. Procedures and examples to determine the adhesion force and free energy of these molecules on solid supports and bio-interfaces are provided.

Video: Investigating Single Molecule Adhesion by Atomic Force Spectroscopy

Compact Quantum Dots for Single-molecule Imaging

Single-molecule imaging is an important tool for understanding the mechanisms of biomolecular function and for visualizing the spatial and temporal heterogeneity of molecular behaviors that underlie cellular biology 1-4. To image an individual molecule of interest, it is typically conjugated to a fluorescent tag (dye, protein, bead, or quantum dot) and observed with epifluorescence or total internal reflection fluorescence (TIRF) microscopy. While dyes and fluorescent proteins have been the mainstay of fluorescence imaging for decades, their fluorescence is unstable under high photon fluxes necessary to observe individual molecules, yielding only a few seconds of observation before complete loss of signal. Latex beads and dye-labeled beads provide improved signal stability but at the expense of drastically larger hydrodynamic size, which can deleteriously alter the diffusion and behavior of the molecule under study.
Quantum dots (QDs) offer a balance between these two problematic regimes. These nanoparticles are composed of semiconductor materials and can be engineered with a hydrodynamically compact size with exceptional resistance to photodegradation 5. Thus in recent years QDs have been instrumental in enabling long-term observation of complex macromolecular behavior on the single molecule level. However these particles have still been found to exhibit impaired diffusion in crowded molecular environments such as the cellular cytoplasm and the neuronal synaptic cleft, where their sizes are still too large 4,6,7.
Recently we have engineered the cores and surface coatings of QDs for minimized hydrodynamic size, while balancing offsets to colloidal stability, photostability, brightness, and nonspecific binding that have hindered the utility of compact QDs in the past 8,9. The goal of this article is to demonstrate the synthesis, modification, and characterization of these optimized nanocrystals, composed of an alloyed HgxCd1-xSe core coated with an insulating CdyZn1-yS shell, further coated with a multidentate polymer ligand modified with short polyethylene glycol (PEG) chains (Figure 1). Compared with conventional CdSe nanocrystals, HgxCd1-xSe alloys offer greater quantum yields of fluorescence, fluorescence at red and near-infrared wavelengths for enhanced signal-to-noise in cells, and excitation at non-cytotoxic visible wavelengths. Multidentate polymer coatings bind to the nanocrystal surface in a closed and flat conformation to minimize hydrodynamic size, and PEG neutralizes the surface charge to minimize nonspecific binding to cells and biomolecules. The end result is a brightly fluorescent nanocrystal with emission between 550-800 nm and a total hydrodynamic size near 12 nm. This is in the same size range as many soluble globular proteins in cells, and substantially smaller than conventional PEGylated QDs (25-35 nm).

We describe the preparation of colloidal quantum dots with minimized hydrodynamic size for single-molecule fluorescence imaging. Compared to conventional quantum dots, these nanoparticles are similar in size to globular proteins and are optimized for single-molecule brightness, stability against photodegradation, and resistance to nonspecific binding to proteins and cells.

الكم النقاط المدمجة لواحدة جزيء التصوير

Single-molecule imaging is an important tool for  understanding the mechanisms of biomolecular function and for visualizing the  spatial and temporal ...

Scanning-probe Single-electron Capacitance Spectroscopy

The integration of low-temperature scanning-probe techniques and single-electron capacitance spectroscopy represents a powerful tool to study the electronic quantum structure of small systems - including individual atomic dopants in semiconductors. Here we present a capacitance-based method, known as Subsurface Charge Accumulation (SCA) imaging, which is capable of resolving single-electron charging while achieving sufficient spatial resolution to image individual atomic dopants. The use of a capacitance technique enables observation of subsurface features, such as dopants buried many nanometers beneath the surface of a semiconductor material1,2,3. In principle, this technique can be applied to any system to resolve electron motion below an insulating surface.
As in other electric-field-sensitive scanned-probe techniques4, the lateral spatial resolution of the measurement depends in part on the radius of curvature of the probe tip. Using tips with a small radius of curvature can enable spatial resolution of a few tens of nanometers. This fine spatial resolution allows investigations of small numbers (down to one) of subsurface dopants1,2. The charge resolution depends greatly on the sensitivity of the charge detection circuitry; using high electron mobility transistors (HEMT) in such circuits at cryogenic temperatures enables a sensitivity of approximately 0.01 electrons/Hz&frac12; at 0.3 K 5.

Scanning-probe single-electron capacitance spectroscopy facilitates the study of single-electron motion in localized subsurface regions. A sensitive charge-detection circuit is incorporated into a cryogenic scanning probe microscope to investigate small systems of dopant atoms beneath the surface of semiconductor samples.

المسح مسبار واحدة الإلكترون الطيفي السعة

The integration of low-temperature scanning-probe techniques and single-electron capacitance spectroscopy represents a powerful tool to study the ...

Quantum State Engineering of Light with Continuous-wave Optical Parametric Oscillators

Engineering non-classical states of the electromagnetic field is a central quest for quantum optics1,2. Beyond their fundamental significance, such states are indeed the resources for implementing various protocols, ranging from enhanced metrology to quantum communication and computing. A variety of devices can be used to generate non-classical states, such as single emitters, light-matter interfaces or non-linear systems3. We focus here on the use of a continuous-wave optical parametric oscillator3,4. This system is based on a non-linear &#967;2 crystal inserted inside an optical cavity and it is now well-known as a very efficient source of non-classical light, such as single-mode or two-mode squeezed vacuum depending on the crystal phase matching. 
Squeezed vacuum is a Gaussian state as its quadrature distributions follow a Gaussian statistics. However, it has been shown that number of protocols require non-Gaussian states5. Generating directly such states is a difficult task and would require strong &#967;3 non-linearities. Another procedure, probabilistic but heralded, consists in using a measurement-induced non-linearity via a conditional preparation technique operated on Gaussian states. Here, we detail this generation protocol for two non-Gaussian states, the single-photon state and a superposition of coherent states, using two differently phase-matched parametric oscillators as primary resources. This technique enables achievement of a high fidelity with the targeted state and generation of the state in a well-controlled spatiotemporal mode.

We describe the reliable generation of non-Gaussian states of traveling optical fields, including single-photon states and coherent state superpositions, using a conditional preparation method operated on the non-classical light emitted by optical parametric oscillators. Type-I and type-II phase-matched oscillators are considered and common procedures, such as the required frequency filtering or the high-efficiency quantum state characterization by homodyning, are detailed.

الدولة الكم هندسة الضوء مع استمرار موجة حدودي البصرية المذبذبات

Engineering non-classical states of the electromagnetic field is a central quest for quantum optics1,2. Beyond their fundamental significance, such states ...

Single Wavelength Shadow Imaging of Caenorhabditis elegans Locomotion Including Force Estimates

This study demonstrates an inexpensive and straightforward technique that allows the measurement of physical properties such as position, velocity, acceleration and forces involved in the locomotory behavior of nematodes suspended in a column of water in response to single wavelengths of light. We demonstrate how to evaluate the locomotion of a microscopic organism using Single Wavelength Shadow Imaging (SWSI) using two different examples.
The first example is a systematic and statistically viable study of the average descent of C. elegans in a column of water. For this study, we used living and dead wildtype C. elegans. When we compared the velocity and direction of nematode active movement with the passive descent of dead worms within the gravitational field, this study showed no difference in descent-times. The average descent was 1.5 mm/sec &#177; 0.1 mm/sec for both the live and dead worms using 633 nm coherent light.
The second example is a case study of select individual C. elegans changing direction during the descent in a vertical water column. Acceleration and force are analyzed in this example. This case study demonstrates the scope of other physical properties that can be evaluated using SWSI while evaluating the behavior using single wavelengths in an environment that is not accessible with traditional microscopes. Using this analysis we estimated an individual nematode is capable of thrusting with a force in excess of 28 nN.
Our findings indicate that living nematodes exert 28 nN when turning, or moving against the gravitational field. The findings further suggest that nematodes passively descend in a column of water, but can actively resist the force of gravity primarily by turning direction.

Single Wavelength Shadow Imaging of Caenorhabditis elegans Locomotion Including Force Estimates

The technique presented here measures the path of freely swimming microscopic species using single wavelength exposure. C. elegans are used to demonstrate shadow imaging as an inexpensive alternative to costly microscopes. This technique can be adapted to accommodate various orientations, environments and species to measure direction, speed, acceleration and forces.

واحد الطول الموجي الظل التصوير من<em&gt; انواع معينة ايليجانس</em&gt; تقديرات تنقل القوة بما في ذلك

This study demonstrates an inexpensive and straightforward technique that allows the measurement of physical properties such as position, velocity, ...

Atomic Force Microscopy of Red-Light Photoreceptors Using PeakForce Quantitative Nanomechanical Property Mapping

Atomic force microscopy (AFM) uses a pyramidal tip attached to a cantilever to probe the force response of a surface. The deflections of the tip can be measured to ~10 pN by a laser and sectored detector, which can be converted to image topography. Amplitude modulation or &#8220;tapping mode&#8221; AFM involves the probe making intermittent contact with the surface while oscillating at its resonant frequency to produce an image. Used in conjunction with a fluid cell, tapping-mode AFM enables the imaging of biological macromolecules such as proteins in physiologically relevant conditions. Tapping-mode AFM requires manual tuning of the probe and frequent adjustments of a multitude of scanning parameters which can be challenging for inexperienced users. To obtain high-quality images, these adjustments are the most time consuming.
PeakForce Quantitative Nanomechanical Property Mapping (PF-QNM) produces an image by measuring a force response curve for every point of contact with the sample. With ScanAsyst software, PF-QNM can be automated. This software adjusts the set-point, drive frequency, scan rate, gains, and other important scanning parameters automatically for a given sample. Not only does this process protect both fragile probes and samples, it significantly reduces the time required to obtain high resolution images. PF-QNM is compatible for AFM imaging in fluid; therefore, it has extensive application for imaging biologically relevant materials.
The method presented in this paper describes the application of PF-QNM to obtain images of a bacterial red-light photoreceptor, RpBphP3 (P3), from photosynthetic R. palustris in its light-adapted state. Using this method, individual protein dimers of P3 and aggregates of dimers have been observed on a mica surface in the presence of an imaging buffer. With appropriate adjustments to surface and/or solution concentration, this method may be generally applied to other biologically relevant macromolecules and soft materials.

A method for investigating the structure of a protein photoreceptor using atomic force microscopy (AFM) is described in this paper. PeakForce Quantitative Nanomechanical Property Mapping (PF-QNM) reveals intact protein dimers on a mica surface.

القوة الذرية الميكروسكوب من الضوء الأحمر الخلايا المستقبلة عن طريق رسم الخرائط PeakForce الكمية النانوميكانيكية الملكية

Atomic force microscopy (AFM) uses a pyramidal tip attached to a cantilever to probe the force response of a surface. The deflections of the tip can be ...

Making Record-efficiency SnS Solar Cells by Thermal Evaporation and Atomic Layer Deposition

Tin sulfide (SnS) is a candidate absorber material for Earth-abundant, non-toxic solar cells. SnS offers easy phase control and rapid growth by congruent thermal evaporation, and it absorbs visible light strongly. However, for a long time the record power conversion efficiency of SnS solar cells remained below 2%. Recently we demonstrated new certified record efficiencies of 4.36% using SnS deposited by atomic layer deposition, and 3.88% using thermal evaporation. Here the fabrication procedure for these record solar cells is described, and the statistical distribution of the fabrication process is reported. The standard deviation of efficiency measured on a single substrate is typically over 0.5%. All steps including substrate selection and cleaning, Mo sputtering for the rear contact (cathode), SnS deposition, annealing, surface passivation, Zn(O,S) buffer layer selection and deposition, transparent conductor (anode) deposition, and metallization are described. On each substrate we fabricate 11 individual devices, each with active area 0.25 cm2. Further, a system for high throughput measurements of current-voltage curves under simulated solar light, and external quantum efficiency measurement with variable light bias is described. With this system we are able to measure full data sets on all 11 devices in an automated manner and in minimal time. These results illustrate the value of studying large sample sets, rather than focusing narrowly on the highest performing devices. Large data sets help us to distinguish and remedy individual loss mechanisms affecting our devices.

Tin sulfide (SnS) is a candidate material for Earth-abundant, non-toxic solar cells. Here, we demonstrate the fabrication procedure of the SnS solar cells employing atomic layer deposition, which yields 4.36% certified power conversion efficiency, and thermal evaporation which yields 3.88%.

جعل السجلات كفاءة SNS خلايا شمسية بواسطة التبخير الحراري وترسب طبقة الذري

Tin sulfide (SnS) is a candidate absorber material for Earth-abundant, non-toxic solar cells. SnS offers easy phase control and rapid growth by congruent ...

Free-form Light Actuators &#8212; Fabrication and Control of Actuation in Microscopic Scale

Liquid crystalline elastomers (LCEs) are smart materials capable of reversible shape-change in response to external stimuli, and have attracted researchers&#39; attention in many fields. Most of the studies focused on macroscopic LCE structures (films, fibers) and their miniaturization is still in its infancy. Recently developed lithography techniques, e.g., mask exposure and replica molding, only allow for creating 2D structures on LCE thin films. Direct laser writing (DLW) opens access to truly 3D fabrication in the microscopic scale. However, controlling the actuation topology and dynamics at the same length scale remains a challenge.
In this paper we report on a method to control the liquid crystal (LC) molecular alignment in the LCE microstructures of arbitrary three-dimensional shape. This was made possible by a combination of direct laser writing for both the LCE structures as well as for micrograting patterns inducing local LC alignment. Several types of grating patterns were used to introduce different LC alignments, which can be subsequently patterned into the LCE structures. This protocol allows one to obtain LCE microstructures with engineered alignments able to perform multiple opto-mechanical actuation, thus being capable of multiple functionalities. Applications can be foreseen in the fields of tunable photonics, micro-robotics, lab-on-chip technology and others.

Here, we fabricate 3D polymeric micro/nano structures in which both the shape and the molecular alignment can be engineered with nanometer scale accuracy by the use of direct laser writing. Light induced deformation of several types of liquid crystalline elastomer microstructures can be controlled in the microscopic scale.

المحركات الخفيفة ذات شكل حر - تصنيع ومراقبة يشتغل في مقياس المجهري

Liquid crystalline elastomers (LCEs) are smart materials capable of reversible shape-change in response to external stimuli, and have attracted ...

Sub-nanometer Resolution Imaging with Amplitude-modulation Atomic Force Microscopy in Liquid

Atomic force microscopy (AFM) has become a well-established technique for nanoscale imaging of samples in air and in liquid. Recent studies have shown that when operated in amplitude-modulation (tapping) mode, atomic or molecular-level resolution images can be achieved over a wide range of soft and hard samples in liquid. In these situations, small oscillation amplitudes (SAM-AFM) enhance the resolution by exploiting the solvated liquid at the surface of the sample. Although the technique has been successfully applied across fields as diverse as materials science, biology and biophysics and surface chemistry, obtaining high-resolution images in liquid can still remain challenging for novice users. This is partly due to the large number of variables to control and optimize such as the choice of cantilever, the sample preparation, and the correct manipulation of the imaging parameters. Here, we present a protocol for achieving high-resolution images of hard and soft samples in fluid using SAM-AFM on a commercial instrument. Our goal is to provide a step-by-step practical guide to achieving high-resolution images, including the cleaning and preparation of the apparatus and the sample, the choice of cantilever and optimization of the imaging parameters. For each step, we explain the scientific rationale behind our choices to facilitate the adaptation of the methodology to every user's specific system.

We present a method for achieving sub-nanometer resolution images with amplitude-modulation (tapping mode) atomic force microscopy in liquid. The method is demonstrated on commercial atomic force microscopes. We explain the rationale behind our choices of parameters and suggest strategies for resolution optimization.

نانومتر الفرعي التصوير القرار مع السعة التشكيل الذرية المجهري القوة في السائل

Atomic force microscopy (AFM) has become a well-established technique for nanoscale imaging of samples in air and in liquid. Recent studies have shown ...

Quantitative Analysis of Vacuum Induction Melting by Laser-induced Breakdown Spectroscopy

Vacuum induction melting is a popular method for refining high purity metal and alloys. Traditionally, standard process control in metallurgy involves several steps, include drawing samples, cooling, cutting, transport to the laboratory, and analysis. The whole analysis process requires more than 30 minutes, which hinders on-line process control. Laser-induced breakdown spectroscopy is an excellent on-line analysis method that can satisfy the requirements of vacuum induction melting because it is fast and noncontact and does not require sample preparation. The experimental facility uses a lamp-pumped Q-switched laser to ablate melted liquid steel with an output energy of 80 mJ, a frequency of 5 Hz, a FWHM pulse width of 20 ns, and a working wavelength of 1,064 nm. A multi-channel linear charge coupled device (CCD) spectrometer is used to measure the emission spectrum in real time, with a spectral range from 190 to 600 nm and a resolution of 0.06 nm at a wavelength of 200 nm. The protocol includes several steps: standard alloy sample preparation and an ingredient test, smelting of standard samples and determination of the laser breakdown spectrum, and construction of the elements concentration quantitative analysis curve of each element. To realize the concentration analysis of unknown samples, the spectrum of a sample also needs to be measured and disposed with the same process. The composition of all main elements in the melted alloy can be quantitatively analyzed with an internal standard method. The calibration curve shows that the limit of detection of most metal elements ranges from 20-250 ppm. The concentration of elements, such as Ti, Mo, Nb, V, and Cu, can be lower than 100 ppm, and the concentrations of Cr, Al, Co, Fe, Mn, C, and Si range from 100-200 ppm. The R2 of some calibration curves can exceed 0.94.

During vacuum induction melting, laser-induced breakdown spectroscopy is used to perform real-time quantitative analysis of the main-ingredient elements of a molten alloy.

التحليل الكمي لذوبان الفراغ التعريفي عن طريق الليزر التي يسببها انهيار الطيفي

Vacuum induction melting is a popular method for refining high purity metal and alloys. Traditionally, standard process control in metallurgy involves ...

An Efficient Method for Selective Desalination of Radioactive Iodine Anions by Using Gold Nanoparticles-Embedded Membrane Filter

Here, we demonstrate a detail protocol for the preparation of nanomaterials-embedded composite membranes and its application to the efficient and ion-selective removal of radioactive iodines. By using citrate-stabilized gold nanoparticles (mean diameter: 13 nm) and cellulose acetate membranes, gold nanoparticle-embedded cellulose acetate membranes (Au-CAM) have easily been fabricated. The nano-adsorbents on Au-CAM were highly stable in the presence of high concentration of inorganic salts and organic molecules. The iodide ions in aqueous solutions could rapidly be captured by this engineered membrane. Through a filtration process using an Au-CAM containing filter unit, excellent removal efficiency (&gt;99%) as well as ion-selective desalination result was achieved in a short time. Moreover, Au-CAM provided good reusability without significant decrease of its performances. These results suggested that the present technology using the engineered hybrid membrane will be a promising process for the large-scale decontamination of radioactive iodine from liquid wastes.

An efficient method for the rapid and ion-selective desalination of radioactive iodine in several aqueous solutions is described by using gold nanoparticles-immobilized cellulose acetate membrane filters.

التحقيق احدة جزيء التصاق بواسطة القوة الذرية الطيفي

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