Search

The metal hexacyanoferrates with transition metal ions to replace ferric ions in the face center cubic structure of Prussian blue (PB) crystals are candidate adsorbents for radioactive cesium ions in waters. This study for the first time synthesized the shape stable poly(vinyl alcohol) (PVA) hydrogels with immobilized metal hexacynoferrate (PB analogue) that can be stored at dry and can efficiently adsorb cesium ions from waters after rewetting. A total of eight PB analogue particles in two families M3[Fe(III)(CN)6]2 (MFe(III)) or M4[Fe(II)(CN)6]2 (MFe(II)) with M=Zn, Ni, Cu, or Co were synthesized and were immobilized in the PVA hydrogels following boric acid and sulfate crosslinking. The produced PVA-PB analogue hydrogels are all stable in shape after dry and rewet, and the rewet hydrogels can adsorb cesium ions from waters at much higher rates. As predicted by the diffusion-reaction model, the apparent reaction constants for cesium ion adsorption are 4.2×10−4 1/s, 3.4×10−4 1/s, 3.9×10−4 1/s, 4.1×10−4 1/s, 4.1×10−4 1/s, 3.8×10−4 1/s, 1.1×10−3 1/s, and 9.6×10−4 1/s, for ZnFe(III), ZnFe(II), NiFe(III), NiFe(II), CuFe(III), CuFe(II), CoFe(III), and CoFe(II), respectively. The corresponding maximum adsorption capacities based on Langmuir isotherm model at 25 °C are 232.6 mg/g, 389.0 mg/g, 193.9 mg/g, 256.8 mg/g, 388.2 mg/g, 395.1 mg/g, 297.3 mg/g, and 391.2 mg/g, respectively. The use of PVA-CoFe(III) is the candidate for enhanced Cs removal from waters comparing the use of other PB analogues as adsorbent.

International audience; Flavin coenzymes are universally found in biological redox reactions. DNA photolyases, with their flavin chromophore (FAD), utilize blue light for DNA repair and photoreduction. The latter process involves two single-electron transfers to FAD with an intermittent protonation step to prime the enzyme active for DNA repair. Here we use time-resolved serial femtosecond X-ray crystallography to describe how light-driven electron transfers trigger subsequent nanosecond-to-microsecond entanglement between FAD and its Asn/Arg-Asp redox sensor triad. We found that this key feature within the photolyase-cryptochrome family regulates FAD re-hybridization and protonation. After first electron transfer, the FAD•- isoalloxazine ring twists strongly when the arginine closes in to stabilize the negative charge. Subsequent breakage of the arginine-aspartate salt bridge allows proton transfer from arginine to FAD•-. Our molecular videos demonstrate how the protein environment of redox cofactors organizes multiple electron/proton transfer events in an ordered fashion, which could be applicable to other redox systems such as photosynthesis.

In order to establish the mapping relationship between architectural design parameters and building performance and optimize architectural design parameters, an architectural design optimization method based on BP neural network is proposed. The selected main design parameters of building ventilation include spacing coefficient, air outlet area, and height from the bottom of the window sill to the ground. Take the comprehensive performance of building ventilation design as the main optimization objective to optimize the building design. First, nine groups of samples of building optimization design are obtained through uniform experimental design. Then, based on the architectural design sample data obtained by BP neural network training, the mapping relationship between architectural design parameters and building performance is established, and based on this mapping, the optimal design parameters of the building are calculated. The research results have a certain reference value for architectural design optimization.

Thermal error is one of the main sources of machining error of machine tools. Being a key component of the machine tool, the spindle will generate a lot of heat in the machining process and thereby result in a thermal error of itself. Real-time measurement of thermal error will interrupt the machining process. Therefore, this paper presents a machine learning model to estimate the thermal error of the spindle from its feature temperature points. The authors adopt random forests and Gaussian process regression to model the thermal error of the spindle and Pearson correlation coefficients to select the feature temperature points. The result shows that random forests collocating with Pearson correlation coefficients is an efficient and accurate method for the thermal error modeling of the spindle. Its accuracy reaches to 90.49% based on only four feature temperature points—two points at the bearings and two points at the inner housing—and the spindle speed. If the accuracy requirement is not very onerous, one can select just the temperature points of the bearings, because the installation of temperature sensors at these positions is acceptable for the spindle or machine tool manufacture, while the other positions may interfere with the cooling pipeline of the spindle.

The poly(vinyl alcohol) (PVA) and alginate hydrogels crosslinked at pH >9 with sodium tetrahydroxyborate (PVA-Bb) hydrogels are shape-stable under repeated dry–rewet cycles. Further crosslinking with sulfate ions to substitute the involved borate complex (PVA-Sb) only moderately enhanced the hydrogel stability. The B(OH)4− cores constitute the skeleton of the PVA-Bb matrix under alkaline condition, which is different from the B(OH)3 cores that are noted principally constituting the hydrogel matrix formed under acidic condition. The shape-stable PVA-Bb Prussian blue (PB) immobilized hydrogels are effective adsorbent of Cs+ ions from waters. The Cs+ permeabilities for PVA-Bb and PVA-Sb hydrogels are close.

Vibrio cholerae is the causative agent of the diarrheal disease cholera, for which biofilm communities are considered to be environmental reservoirs. In endemic regions, and after algal blooms, which may result from phosphate enrichment following agricultural runoff, the bacterium is released from biofilms resulting in seasonal disease outbreaks. However, the molecular mechanism by which V. cholerae senses its environment and switches lifestyles from the biofilm‐bound state to the planktonic state is largely unknown. Here, we report that the major biofilm scaffolding protein RbmA undergoes autocatalytic proteolysis via a phosphate‐dependent induced proximity activation mechanism. Furthermore, we show that RbmA mutants that are defective in autoproteolysis cause V. cholerae biofilms to grow larger and mechanically stronger, correlating well with the observation that RbmA stability directly affects microbial community homeostasis and rheological properties. In conclusion, our biophysical study characterizes a novel phosphate‐dependent breakdown pathway of RbmA, while microbiological data suggest a new, sensory role of this biofilm scaffolding element.

The metal hexacyanoferrates with transition metal ions to replace ferric ions in the face center cubic structure of Prussian blue (PB) crystals are candidate adsorbents for radioactive cesium ions in waters. This study for the first time synthesized the shape stable poly(vinyl alcohol) (PVA) hydrogels with immobilized metal hexacynoferrate (PB analogue) that can be stored at dry and can efficiently adsorb cesium ions from waters after rewetting. A total of eight PB analogue particles in two families M

In this study, we review our progress in micro/mini LED arrays and their numerical simulation in optical fields. The variation in substrate thickness will be included in the calculation and the results can provide detailed insight for the optimization of the micro/mini LED structures.

Manufacturing sales prediction is an important measure of national economic development trends. The plastic injection molding machine industry has its own independent R and D energy and mass production technology, with all products sold globally through international brands. However, most previous injection molding machine studies have focused on R and D, production processes, and maintenance, with little consideration of sales activity. With the development and transformation of Industry 4.0 and the impact of the global economy, Taiwan&rsquo, s injection molding machine industry growth rate has gradually flattened or even declined, with company sales and profits falling below expectations. Therefore, this study collected key indicators for Taiwan&rsquo, s export economy from 2008 to 2017 to help understand the impact of economic indicators on injection molding sales. We collected 35 indicators, including net entry rate of employees into manufacturing industries, trend indices, manufacturing industry sales volume indices, and customs export values. We used correlation analysis to select variables affecting plastic injection machine sales and artificial neural networks (ANN) were applied to predict injection molding machine sales at each level. Prediction results were verified against the correlation indicators, and seven key external economic factors were identified to predict accurate changes in company annual sales prediction, which will be helpful for effective resource and risk management.

In this study, the effects of electromigration on a solder/copper substrate due to temperature and current density stress were investigated. The copper&ndash, tin (Cu&ndash, Sn) film samples were subjected under a fixed current and various heating conditions (130 &deg, C and 180 &deg, C) and current densities (different cross-sectional areas). The micro-structural changes and intermetallic compound (IMC) formation were observed, and failure phenomena (brittle cracks, voids, bumps, etc.) on the structures of samples were discussed. The results showed that the IMC thickness increased as the temperature and current density increased. Moreover, it was found that the higher the temperature and current density was, the greater the defects that were observed. By adjusting the designs of sample structures, the stress from the current density can be decreased, resulting in reduced failure phenomena, such as signal delay, distortion, and short circuiting after long-term use of the material components. A detailed IMC growth mechanism and defect formation were also closely studied and discussed.

Sulfonated, sterically-encumbered, alternating copolymers based on poly(arylene ether) are reported. The polymers were prepared by polymerization of 9,9-bis(4-hydroxyphenyl) fluorene with a novel monomer, 4,4⁗-difluoro-3,3⁗-bistrifluoromethyl-2″,3″,5″,6″-tetraphenyl-[1,1′;4′,1″;4″,1‴;4‴,1⁗]-pentaphenyl. Subsequent sulfonation and solution casting provided membranes possessing ion exchange capacities ranging from 0.5 to 2.7 mmol/g. Proton conductivities of membranes increased with IEC and temperature to values > 260 mS/cm (at 80 °C, 95% RH). The membranes exhibited good dimensional stability upon water sorption and a resistance to swelling. Dry membranes comprised of isolated spherical aggregates of ions, which upon hydration formed highly conductive pathways, as visualized by AFM analysis. We infer that introducing a high free volume into the polymer by way of incorporating highly sulfonated, multi-phenylated moieties provides mechanically-robust and dimensionally-stable proton exchange membranes.

In this research, a regioregular poly (3-alkylthiophene) derivative had been synthesized via the post-polymerization functionalization, poly (3-hexylamine thiophene), which are soluble in water and water miscible solvents such as methanol, DMSO. The suitable energy level, good thermal stability and water/alcohol solubility of polymers which promising applied in polymer solar cells and processed by water or environmental-friendly solvents. In blend of functionalization polymers and fullerene derivative potassium [6,6]-phenyl-C61-butyrate shows significant UV absorption decay phenomenon and occur precipitates follow with time increase. To further investigate the mechanism of composite, FT-IR analysis and TEM investigate were used, the polymer would be bonded with carboxyl of fullerene derivative via hydrogen bonding in the carboxyl region and TEM images demonstration the mixture that be able to self-assembly a interpenetrating network composite.

In the decision on the pros and cons of the optical and electrical properties of organic solar cells, the morphology has proven to be very important. Easy to change the morphology via adding a small amount of additive, because proton dissociation constant is the main reason for their application. In this study, the use of poly(3-hexylthiophene) and [6,6]-phenyl C 61-butyric acid methyl ester as the donor and acceptor materials, and were subsequently doped with different quantity of 4,4′-sulfonyldiphenol, 4,4′-dihydroxybiphenyl, biphenyl-4,4′-dithiol. When the proton dissociation constant is higher and lower respectively, the morphology reveals earthworms-like and fiber-like. For the reason that when the additive is biphenyl-4,4′-dithiol, it can improve the power conversion efficiency of about 27% and the incident photon-to-current conversion efficiency of about 12%.

A series of sterically-encumbered, sulfonated, poly(arylene ether) copolymers were synthesized and their proton conductivity examined. The series was prepared by copolymerizing a novel monomer, 2″,3″,5″,6″-tetraphenyl-[1,1′:4',1″:4″,1″':4″',1″″-quinquephenyl]-4,4″″-diol, with 4,4'-difluorobenzophenone and bisphenol A. Subsequent sulfonation and solution casting provided membranes possessing ion exchange capacities of 1.9 to 2.7 mmol/g and excellent mechanical properties (Young's modulus, 0.2–1.2 GPa; tensile strength, 35–70 MPa; elongation at break, 62–231%). Water uptake ranged from 34 to 98 wt% at 80 °C/100% RH. Proton conductivities ranged between 0.24 to 16 mS/cm at 80 °C/60% RH, and 3 to 167 mS/cm at 80 °C/95% RH. TEM analysis of the polymers, in the dehydrated state, revealed isolated spherical aggregates of ions, which presumably coalesce when hydrated to provide highly conductive pathways. The strategy of using highly-encumbered polymer frameworks for the design of mechanically-robust and dimensionally-stable proton conducting membranes is demonstrated. © 2014 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2014, 52, 2579-2587

A simulation scheme was developed to explore the light distribution of full-color micron-scale light-emitting diode (LED) arrays. The influences of substrate thickness, patterning, and cutting angle of the substrate on several important features, such as light field pattern, light extraction efficiency, and color variation, were evaluated numerically. An experiment was conducted; the results were consistent with simulation results for a 225 × 125 µm2 miniLED and those for an 80 × 80 µm2 microLED. Based on the simulation results, the light extraction efficiency of LED devices with a substrate increases by 67.75% over the extraction efficiency of those without a substrate. The light extraction efficiency of LED devices with a substrate increases by 113.55% when an additional patterned design is used on green and blue chips. The calculated large angle Δu′v′ can be as low as 0.015 for miniLED devices.

So far, several studies have investigated the external factors that can cause chemical and physical changes of the molecular system and applied these factors in measurement instruments and optical lightemitting diodes (LEDs). In particular, due to their high sensitivity to external physical and chemical factors, fluorescent dyes can demonstrate multiple characteristics such as polarization, refractive rate, conductivity, andfluorescent measurement, withfluorescent measurement being the greatest concern. Thus, these characteristics are able to provide a measurement basis for precision instruments in industry, The design of the fluorescent molecule measurements for display and light is a key process in this industry, since fluorescent signals can be accurately controlled and detected by simple chemical modulation or fine-tuning of a single molecule or ion for further precision changes. Different light-emitting characteristics of fluorescent molecules in systems can be used in optical LEDs, which can be modulated by external factors such as temperature, pH, and light or redox potential. Acid is commonly used as an inducer since the proton-binding reactions are often accompanied by protonation/deprotonation processes, such as transfer of electrons, charges and transfer of energy, thereby enabling the modulation of emission properties. The two most common routes in the receptor system, namely, proton-induced electron transfer 1 and intra molecular charge transfer (ICT), 2 are often used as optical LEDs. Aromatic compounds are widely used as their fluorescence spectra are often affected by the pH value, making them suitable for use as optical LEDs. The reversible protonation reaction is a new challenge to modulating the proportion of protonation and the ICT. This study use the most widely available green fluorescent dopant, 10-(2-benzothiazolyl)-1,1,7,7-tetramethyl-2,3,6,7tetrahydro-1H,5H,1crystal 1Hbenzo[l]-pyrano [6,7,8-ij]quinolizin11-one (C545T), 3‐5 which belongs to the coumarin laser dye, for protonation following benzenesulfonic acid induction. 6 C545T can be made to generate three different types of light colors by controlling the number of protonation molecules and the ICT mechanism. The characteristics of the adjustable light-emitting spectrum can be used for the measurement of optical LEDs. Fig. 1 illustrates the protonation of C545T upon addition of benzenesulfonic acid. During our study, we conducted qualitative analysis and investigated the color changes caused by the addition of acid to C545T and the spectrum to further verification that C545T can take advantage of the pH value modulation and change the protonation characteristics of ICT, which makes C545T a potential application of optical LEDs. Furthermore, white polymer LEDs (PLEDs) have attracted our attention as they

The present study attempts to prove the spatial modes of the commercial district of the Ruins of St. Paul's methodologically with space syntax, axis analysis method. The study particularly selects three points of time — i.e., 1912, 1986, and 2015, respectively — in order to study the spatial structural changes of the district, and it attempts to predict the development tendency of this commercial district. The research discovers that the district center has been gradually shifted to its peripheral district through the on-site measure and observation, after the statistical analysis on the internal spatial structure of the district, function, traffic and the street scale: from linear blocks to block districts. The space of the district has been influenced by the peripheral sub-district, contributing to the influx of passengers and the change of the sites. This proves that the commercial district can guide the extensive development of the peripheral district. The study will forge the external guiding measures of the streets through the district coordination in the future, with the focus on the streets less understood and the historic conservation districts.

This study takes the shopping district around the Ruins of St. Paul as the scope of its study, and performs investigative research, as well as commercial analysis, of the streets and areas around the ruins. The road at the southern end of the Ruins of St. Paul contains 43 stores. Among these, 17 are souvenir item shops such as Koi Kei Bakery, Chuiheungyuen, Yingkee Tea Shop, and other well-known brands. Our study implemented a cognitive map survey. We collected 126 samples and discovered that landmark architectural structures, such as the fountain, St. Dominic's Church, the Ruins of St. Paul, and stores around one area (Senado Square): McDonalds, Sa Sa, Watsons, Koi Kei Bakery, as well as thoroughfare stores (St. Paul Street): Nike, Dairy Queen, and others, were all landmarks which people had strong impressions of and remember. Samples included 108 hand-drawn guide maps which depicted critical landmarks. For example, the relationship involved in the network of streets and stores between Senado Square and the Ruins of St. Paul, as well as the surrounding areas, allowed us to understand the overall environment and area.

A series of sterically hindered, sulfonated, poly(arylene ether) polymers were synthesized by nucleophilic polycondensation reaction using 4,4′′′′-difluoro-3,3′′′′-bistrifluoromethyl-2′′,3′′,5′′,6′′-tetraphenyl-[1,1′;4′,1′′;4′′,1′′′;4′′′,1′′′′]-pentaphenyl and 4,4′-biphenol and were prepared through postpolymerization sulfonation. The chemical structures were confirmed by1H NMR. Subsequent to sulfonation, solvent-casting membranes were provided ion exchange capacity (IEC) values ranging from 0.39 to 2.90 mmol/g. Proton conductivities of membranes ranged from 143 to 228 mS/cm at 80°C under fully humidified conditions which were higher than that of Nafion 117. The membrane also exhibited considerably dimension stability, oxidative stability, and hydrolytic stability. The microphase structure was investigated by transmission electron microscopy (TEM) and the ionic aggregation of sulfonic acid groups exhibited spherical ionic clusters with well-developed phase separated morphology. The results indicated that the membranes are promising candidates for application as proton exchange membranes. This investigation demonstrates introducing multiphenylated moieties to create a high free volume polymer that provides dimensionally stable and high proton conductivity membranes.

This work presents the CMOS micromachined capacitive sensors for ultrasound detection in water. The sensing membranes with a 60 µm diameter are released through small etchant holes of 2 µm × 2 µm by a post-CMOS metal etch and sealed with the thinnest possible silicon dioxide (type A) or parylene-D film (type B). Nine membranes form a single detection unit with a capacitance value of 292.5 fF. Convenient routing, which is desired for making a large two-dimensional array, is allowed with the detection circuits being placed directly beneath the sensing membranes. An alternating voltage bias is applied to the sensing electrodes for stabilizing the sensed signals which would otherwise attenuate over time due to trapped charges between electrodes. Resonant frequencies of type-A and type-B sensors in water are 8.8 and 5.8 MHz, with fractional bandwidths of 0.43 and 0.55, respectively. The measured sensitivities are 151.0 and 369.8 mVpp MPa−1 V−1. The equivalent noise pressures, based on the measured thermal noise, are 3.3 and 1.35 Pa Hz−1/2 at a 1 V membrane bias.

In this paper, we nano-engineered commercial atomic force microscope (AFM) probes with multi nano tip structures for high speed/resolution dynamic nanodetection. The tip radius could be shrunk down to 2.5 nm, and the time resolution could be approaching 10 ms for measuring particle movement. The multi tip AFM can be applicable for detecting the dynamic movement of bio-molecules in situ.

Structured illumination microscopy (SIM) was recently adapted to coherent imaging, named structured oblique-illumination microscopy (SOIM), to improve the contrast and resolution of a light-scattering image. Herein, we present high-resolution laterally isotropic SOIM imaging with 2D hexagonal illuminations. The SOIM is implemented in a SIM fluorescence system based on a spatial-light modulator (SLM). We design an SLM pattern to generate diffraction beams at 0° and ± 60.3° simultaneously to form a 2D hexagonal illumination, and undertake calculations to obtain optimal SLM shifts at 19 phases to yield a reconstructed image correctly. Beams of linear and circular polarizations are used to show the effect of polarization on the resolution improvement. We derive the distributions of the electric field of the resultant hexagonal patterns and work out the formulations of the corresponding coherent-scattering imaging for image reconstruction. The reconstructed images of gold nanoparticles (100 nm) confirm the two-fold improvement of resolution and reveal the effect of polarization on resolving adjacent nanoparticles. To demonstrate biological applications, we present the cellular structures of a label-free fixed HeLa cell with improved contrast and resolution. This work enables one to perform high-resolution dual-mode - fluorescence and light-scattering - imaging in a system, and is expected to broaden the applications of SOIM.

In this letter, we demonstrate the feasibility of 3-D photoacoustic imaging using a monolithic CMOS micromachined capacitive ultrasonic sensor. The sensing membranes are released by a post-CMOS metal etch and sealed by silicon dioxide. Nine membranes, each with an inner diameter of 60 μm, form a single detection unit with a capacitance value of 292.5 fF. A 6- μm carbon fiber was employed to evaluate the 3-D photoacoustic imaging capability and resolution of our sensor. A 2-D large-aperture array was emulated by 2-D mechanical scanning of a single sensing element with a scanning step of 120 μm. A 2-D synthetic aperture focusing technique was used for image reconstruction. The measured -6-dB spatial resolutions were 181 μm in axial and 448 μm in lateral, respectively, at the depth of ~ 2.4 cm. The 3-D photoacoustic image of a carbon fiber phantom was successfully produced.

Optical resolution photoacoustic microscopy (OR-PAM) has been shown as a promising tool for label-free microvascular and single-cell imaging in clinical and bioscientific applications. However, most OR-PAM systems are realized by using a bulky laser for photoacoustic excitation. The large volume and high price of the laser may restrain the popularity of OR-PAM. In this study, we attempt to develop a compact, portable, and low cost OR-PAM based on a consumer Blu-ray (405 nm) DVD pickup head for label-free micro-vascular imaging and red-blood-cell related blood examination. According to the high optical absorption of the hemoglobin at 405 nm, the proposed OR-PAM has potential to be an alternative for the conventional optical microscopy in the examinations of hematological morphology for blood routine. We showed that the Blu-ray DVD pickup head owns the required laser energy and focusing optics for OR-PAM. The firmware of a Blu-ray DVD drive was modified to allow its pickup head to generate nano-second laser pulses with a tunable pulse repetition rate of >30 kHz and a tunable pulse width ranging from 10 to 30 ns. The laser beam was focused onto the target after passing through a transparent cover slide, and then aligned to be confocal with a 50-MHz focused ultrasonic transducer in forward mode. To keep the target on focus, a scan involving auto-tracking procedure was performed. The measured maximum achievable lateral resolution was 1 μm which was mainly limited by the minimum step size of the used motorized stage. A blood smear was imaged without any staining. The red blood cells were well resolved and the biconcave structure could be clearly visualized. In addition, to verify the in vivo imaging capability of the proposed OR-PAM, the micro-vasculature of a mouse ear was imaged without any contrast agent. The results showed that it performed better than a 200x digital optical microscope in terms of image contrast and vascular morphology. In summaries, the proposed OR-PAM has been demonstrated as a promising tool for label-free blood imaging in both small animal studies and blood examinations, and potentially can be a compact and low-cost OR-PAM platform.

Ethylene is an important plant hormone that regulates developmental processes in plants. The ethylene biosynthesis pathway is a highly regulated process at both the transcriptional and post-translational level. The transcriptional regulation of these ethylene biosynthesis genes is well known. However, post-translational modifications of the key ethylene biosynthesis enzyme 1-aminocyclopropane-1-carboxylate (ACC) synthase (ACS) are little understood. In vitro kinase assays were conducted on the type III ACS, AtACS7, fusion protein and peptides to determine whether the AtACS7 protein can be phosphorylated by calcium-dependent protein kinase (CDPK). AtACS7 was phosphorylated at Ser216, Thr296, and Ser299 by AtCDPK16 in vitro. To investigate further the function of the ACS7 gene in Arabidopsis, an acs7-1 loss-of-function mutant was isolated. The acs7-1 mutant exhibited less sensitivity to the inhibition of root gravitropism by treatment with the calcium chelator ethylene glycol tetraacetic acid (EGTA). Seedlings were treated with gradient concentrations of ACC. The results showed that a certain concentration of ethylene enhanced the gravity response. Moreover, the acs7-1 mutant was less sensitive to inhibition of the gravity response by treatment with the auxin polar transport inhibitor 1-naphthylphthalamic acid, but exogenous ACC application recovered root gravitropism. Altogether, the results indicate that AtACS7 is involved in root gravitropism in a calcium-dependent manner in Arabidopsis.

In this study, we propose an intrinsic contrast based ultrasound time intensity curve (TIC) technique for monitoring the dynamic response of FUS-induced BBB opening on a rat model. Because the ultrasound backscattering coefficient of the cerebral blood is higher than that of the peripheral brain tissues at the used imaging frequency, the intensity of backscatter signal can be used as the indicator to analyze the variation of the cerebral blood flow and hemorrhage during FUS-induced BBB opening. Two considerable cases of BBB opening - with and without hemorrhage - was performed by 1-MHz FUS and monitored by the proposed TIC technique. In the case with microhemorrhage, the TIC of the sonicated area (left brain) rose immediately after the BBB opening and then gradually declined after 10 minutes. The TIC of controlled contralateral (right) brain gradually dropped. The response of the left brain was dominated by the brain hemorrhage and was suspiciously mingled with the effect of ischemia. The TIC of the right brain showed a high performance of flow auto-regulation which is the forced vasoconstriction of the right brain compensating blood to the left brain. In the case without hemorrhage, the TIC of the left brain gradually dropped; the right one was in accordance with the result of the condition with microhemorrhage. In this case, FUS induced vasoconstriction and thus caused reduction of blood volume in the left brain, and this lead to the compensation of the blood from the right brain induced by flow auto-regulation. Overall, the proposed intrinsic contrast based ultrasound TIC technique was proved to be able to quantitatively reflect the variation of the cerebral blood volume.

Three dimensional (3-D) photoacoustic imaging is demonstrated in this study by using a 4 × 4 CMOS (complementary metal oxide semiconductor) micromachined capacitive ultrasonic sensor array. The sensing membranes are fabricated by a post-CMOS metal etch and sealed by parylene with a measured resonant frequency between 3 to 5.1 MHz. The area of a single detection unit is 280 × 280 μm2. A large 2-D aperture was emulated by 2-D mechanical scanning of the array with a scanning step of 1.12 mm. The measured -6-dB spatial resolutions were 381 μm in axial and 1.3 mm in lateral, respectively, at a depth of ~2.1 cm. The 3-D photoacoustic image of a hair phantom was successfully produced.

In this study, we develop a novel photoacoustic imaging technique based on gold nanorods (AuNRs) for quantitatively monitoring focused-ultrasound (FUS) induced blood-brain barrier (BBB) opening in a rat model in vivo. This study takes advantage of the strong near-infrared absorption (peak at ∼800 nm) of AuNRs and the extravasation tendency from BBB opening foci due to their nano-scale size to passively label the BBB disruption area. Experimental results show that AuNR contrast-enhanced photoacoustic microscopy (PAM) success- fully reveals the spatial distribution and temporal response of BBB disruption area in the rat brains. The quantitative measurement of contrast enhancement has potential to estimate the local concentration of AuNRs and even the dosage of therapeutic molecules when AuNRs are further used as nano-carrier for drug delivery or photothermal therapy. The photoacoustic results also provide complementary information to MRI, being helpful to discover more details about FUS induced BBB opening in small animal models. © 2012 Society of Photo-Optical Instrumentation Engineers (SPIE).

Optical imaging of changes in total hemoglobin concentration ( HbT), cerebral blood volume ( CBV), and hemoglobin oxygen saturation ( SO 2) provides a means to investigate brain hemodynamic regulation. However, high-resolution transcranial imaging remains challenging. In this study, we applied a novel functional photoacoustic microscopy technique to probe the responses of single cortical vessels to left forepaw electrical stimulation in mice with intact skulls. Functional changes in HbT, CBV, and SO 2 in the superior sagittal sinus and different-sized arterioles from the anterior cerebral artery system were bilaterally imaged with unambiguous 36 × 65- μm2 spatial resolution. In addition, an early decrease of SO 2 in single blood vessels during activation (i.e., ‘the initial dip’) was observed. Our results indicate that the initial dip occurred specifically in small arterioles of activated regions but not in large veins. This technique complements other existing imaging approaches for the investigation of the hemodynamic responses in single cerebral blood vessels.

Optical resolution photoacoustic microscopy (OR-PAM) has been shown as a promising tool for label-free microvascular and single-cell imaging in clinical and bioscientific applications. However, most OR-PAM systems are realized by using a bulky laser for photoacoustic excitation. The large volume and high price of the laser may restrain the popularity of OR-PAM. In this study, we develop a low-cost and compact OR-PAM system based on a commercially available DVD pickup head. We showed that the DVD pickup head have the required laser energy and focusing optics for OR-PAM. The firmware of a DVD burner was modified to enable its laser diode to provide a 13-ns laser pulse with 1.3-nJ energy at 650 nm. Two excitation wavelengths at 650 and 780 nm were available. The laser beam was focused onto the target after passing through a 0.6-mm thick DVD transparent polycarbonate coating, and then aligned to be confocal with a 50-MHz focused ultrasonic transducer in forward mode. To keep the target on focus, a scan involving auto-tracking procedure was performed. The lateral resolution was verified via cross-sectional imaging of a 6-μm carbon fiber. The measured -6 dB width of the carbon fiber was 6.66 μm which was in agreement with optical diffraction limit. The proposed OR-PAM has potential as an economically viable and compact blood screening tool available outside of large laboratories due to its low cost and portability. Furthermore, a better spatial resolution could be provided by using a blue ray DVD pickup head.

Recently, photoacoustic imaging has been intensively studied for blood vessel imaging, and shown its capability of revealing vascular features suggestive of malignancy of breast cancer. In this study, we explore the feasibility of visualization of micro-calcifications using photoacoustic imaging. Breast micro-calcification is also known as one of the most important indicators for early breast cancer detection. The non-ionizing radiation and speckle free nature of photoacoustic imaging overcomes the drawbacks of current diagnostic tools - X-ray mammography and ultrasound imaging, respectively. We employed a 10-MHz photoacoustic imaging system to verify our idea. A sliced chicken breast phantom with granulated calcium hydroxyapatite (HA) - major chemical composition of the breast calcification associated with malignant breast cancers - embedded was imaged. With the near infared (NIR) laser excitation, it is shown that the distribution of ~500 μm HAs can be clearly imaged. In addition, photoacoustic signals from HAs rivals those of blood given an optimal NIR wavelength. In summary, photoacoustic imaging shows its promise for breast micro-calcification detection. Moreover, fusion of the photoacoustic and ultrasound images can reveal the location and distribution of micro-calcifications within anatomical landmarks of the breast tissue, which is clinically useful for biopsy and diagnosis of breast cancer staging.

Assessments of vascularity are important when assessing inflammation changes in tendon injuries since Achilles tendinitis is often accompanied with neovascularization or hypervascularity. In this study, we have investigated the feasibility of photoacoustic imaging in noninvasive monitoring of morphological and vascular changes in Achilles tendon injuries. Collagenase-induced Achilles tendinitis model of mice was adopted here. During collagenase-induced tendinitis, a 25-MHz photoacoustic microscopy (PAM) was used to image micro-vascular changes in Achilles tendons longitudinally up to 23 days. The positions of vessels imaged by PAM were identified by co-registration of PAM Bmode images with 25-MHz ultrasound (USM) ones. Morphological changes in Achilles tendons due to inflammation and edema were revealed by the PAM and USM images. Proliferation of new blood vessels within the tendons was also observed. Observed micro-vascular changes during tendinitis were similar to the findings in the literatures. This study demonstrates that photoacoustic imaging, owning required sensitivity and penetration, has the potential for high sensitive diagnosis and assessment of treatment performance in tendinopathy.

In this study, we report on using multi-wavelength photoacoustic microscopy to image hemodynamic changes of total hemoglobin concentration (HbT) (i.e., blood volume) and oxygenation (SO2) in rat brain cortex vessels with electrical stimulation. Electrical stimulation of the rat left forelimb was applied to evoke changes in vascular dynamics of the rat somatosensory cortex. The applied current pulses were with a pulse frequency of 3 Hz, pulse duration of 0.2 ms, and pulse amplitude of 5 mA, respectively. The imaging target of rat brains was demarcated at AP 0 - -2.5 mm and ML ± 6 mm with respect to bregma. HbT changes were probed by images acquired at 570 nm, a hemoglobin isosbestic point while SO2 changes were imaged by those acquired at 560 nm or 600 nm and their derivatives, which were normalized to those with 570 nm wavelengths. Correlation between the electrical stimulation paradigm and images acquired at 570, 560, and 600 nm in contralateral and ipsilateral vasculature was statistically analyzed, showing that the HbT and SO2 changes revealed by multi-wavelength photoacoustic images spatially correlated with contralateral vasculature.

Blood brain barrier (BBB) prevents most of the drug from transmitting into the brain tissue and decreases the treatment performance for brain disease. One of the methods to overcome the difficulty of drug delivery is to locally increase the permeability of BBB with high-intensity focused ultrasound. In this study, we have investigated the feasibility of photoacoustic microscopy of focused-ultrasound induced BBB opening in a rat model in vivo with gold nanorods (AuNRs) as a contrast agent. This study takes advantage of the strong near-infrared absorption of AuNRs and their extravasation tendency from BBB opening foci due to their nano-scale size. Before the experiments, craniotomy was performed on rats to provide a path for focused ultrasound beam. Localized BBB opening at the depth of about 3 mm from left cortex of rat brains was achieved by delivering 1.5 MHz focused ultrasound energy into brain tissue in the presence of microbubbles. PEGylated AuNRs with a peak optical absorption at ~800 nm were then intravenously administered. Pre-scan prior to BBB disruption and AuNR injection was taken to mark the signal background. After injection, the distribution of AuNRs in rat brains was monitored up to 2 hours. Experimental results show that imaging AuNRs reveals BBB disruption area in left brains while there are no changes observed in the right brains. From our results, photoacoustic imaging plus AuNRs shows the promise as a novel monitoring strategy in identifying the location and variation of focused-ultrasound BBB-opening in a rat model.

Achilles tendon injuries are common clinical problems for athletes, especially in runners. Several studies indicate that Achilles tendinopathy is accompanied with neovascularization or hypervascularity; thus, assessments of vascularity are important when assessing inflammation changes in tendon injuries. Photoacoustic imaging, taking the advantages of good ultrasonic resolution and high optical absorption contrast, has been shown a promising tool for vascular imaging. In this study, we demonstrate the potential of photoacoustic microscopy in monitoring the microvascular and morphological changes in tendon injuries in a mouse model in vivo. A 25-MHz dark-field confocal PAM was used to image microvascular changes in Achilles tendon of mice before and during collagenase-induced tendinitis. A wavelength of 532 nm was applied for photoacoustic excitation because blood vessels own strong optical absorption at this wavelength, guaranteeing that detected photoacoustic signals mainly come from vessels. Co-registration of PAM B-mode images with 25-MHz ultrasound (USM) ones was also performed. Morphological changs in Achilles tendons due to inflammation and edema were revealed by the PAM and USM images. Proliferation of new blood vessels within the tendons was also observed. Observed microvascular changes during tendinitis were similar to the findings in the literatures. Future work includes time-course assessments of microcirculation changes in tendonitis before and after treatment. More cases and histological verifications will be used to obtain statistically significant data.

A solution-processing method for obtaining graphite oxide (GO), which is used for the organic light-emitting diodes (OLEDs), is presented herein. The use of poly(arylene ether)s as the solid carbon source is demonstrated for the first time. Raman spectroscopy, Fourier transform infrared (FTIR), X-ray photoelectron spectroscopy (XPS), luminance, and electroluminescence (EL) reveal the essential properties. The respective percentages of the peak areas of sp2 C and sp3 C in the GO are calculated to be 54.47 and 37.32%. The GO had a sheet resistance of 97 Ω/square determined by the four-probe method and a conductivity of 5.538 × 101 Ω−1 cm−1 determined by the Hall-effect method.