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The three-dimensional reconstruction in phase-measuring profilometry (PMP) usually involves the phase error caused by the gamma effect of the projector. In this study, the relationship between the ...

Human fecal pollution of recreational waters remains a public health concern worldwide. As a result, there is a growing interest in the application of human-associated fecal source identification quantitative real-time PCR (qPCR) technologies for water quality research and management. However, there are currently no standardized approaches for field implementation and interpretation of qPCR data. In this study, a standardized HF183/BacR287 qPCR method was combined with a water sampling strategy and a novel Bayesian weighted average approach to establish a human fecal contamination score (HFS) that can be used to prioritize sampling sites for remediation based on measured human waste levels. The HFS was then used to investigate 975 study design scenarios utilizing different combinations of sites with varying sampling intensities (daily to once per week) and number of qPCR replicates per sample (2–14 replicates). Findings demonstrate that site prioritization with HFS is feasible and that both sampling intensity and number of qPCR replicates influence reliability of HFS estimates. The novel data analysis strategy presented here provides a prescribed approach for the implementation and interpretation of human-associated HF183/BacR287 qPCR data with the goal of site prioritization based on human fecal pollution levels. In addition, information is provided for future users to customize study designs for optimal HFS performance.

A three-dimensional measurement method based on frequency-carrier computer-generated moire fringe is proposed. By projecting two sinusoidal gratings with π phase difference each other onto the measured object respectively and capturing the corresponding deformed patterns, the AC component of the deformed pattern can be extracted. When this AC component is respectively multiplied by actively designed computer-generated sinusoidal grating and cosinoidal grating with the same frequency, two new fringes containing frequency-carrier moire components can be obtained. After low-pass filtering, the frequency-carrier moire fringes can be extracted to achieve object’s phase retrieval. As long as the DC component of the actively designed sinusoidal grating and cosinoidal grating are all controlled to be zero, the effect of inaccuracy elimination of the deformed pattern’s background light component on measuring accuracy can be reduced evidently. The frequency of the actively designed grating can be determined as 1/4 lines per pixel to ensure the maximum distance between each adjacent spectrum peaks of the new generated fringe so as to get the best measurement effect. The proposed method has good application ability in the limited number of projection frames and other scenes, and can achieve high measurement accuracy by projecting only two fringe patterns. Experimental results verify the feasibility and validity of the proposed method.

Cell morphology and nucleus deformation are important when circulating tumor cells break away from the primary tumor and migrate to a distant organ. Cells are sensitive to the microenvironment and respond to the cell–material interfaces. We fabricated TiO2 nanorod arrays with mesoscopic micro–nano interfaces through a two-step hydrothermal reaction method to induce severe changes in cell morphology and nucleus deformation. The average size of the microscale voids was increased from 5.1 to 10.5 μm when the hydrothermal etching time was increased from 3 to 10 h, whereas the average distances between voids were decreased from 0.88 to 0.40 μm. The nucleus of the MCF-7 cells on the TiO2 nanorod substrate that was etched for 10 h exhibited a significant deformation, because of the large size of the voids and the small distance between voids. Nucleus defromation was reversible during the cells proliferate process when the cells were cultured on the mesoscopic micro-nano interface.This reversible process was regu...

The noise pollution in pipelines exists for a long time and can’t be ignored in modern industries. It is important to investigate the transfer mechanism of sound energy in pipelines and develop high efficiency mufflers with low penalty of pressure drop. Different with the traditional method, this study is focused on the flow and sound fields synergy principle to investigate the flow noise propagation mechanism in reactive mufflers. In this study, theoretical analysis and numerical simulation methods are coupled to investigate the noise propagation process. In the theoretical analysis aspect, the synergetic relationships between the flow and pressure gradient fields are deduced and the field synergy theory is established. In the numerical simulation aspect, the flow noise propagation process in the simple expansion chamber mufflers is studied. The results show that with the decrease of synergy between flow and sound fields, the work done by the fluid on the wall decreases, which means the exchange of sound energy between the wall and the fluid decreases.

D-1,2,4-Butanetriol (BT) is one of the important platform chemicals mainly used in the pharmaceutical and military fields. However, the content of BT in its fermentation broth is less than 1 wt%. The purification of BT by distillation is a high energy-consumption process. In this paper, a solvent desorption method was used to pre-concentrate BT with ethanol as a desorbent. This work focused on establishing a transient chromatographic column model to explore vividly the pre-concentration behaviors of BT during column adsorption/desorption processes. First, by analysis of the hydrophobicity and molecular size of the solutes and the micropore size of resin, the adsorption mechanisms were proposed as size exclusion and hydrophobic interaction, while desorption equilibrium was supposed to competitive adsorption. Secondly, the effects of the different ethanol concentrations on the enrichment of BT concentration were investigated systematically. The results showed about 1.46 bed volumes of absolute ethanol could desorb BT completely with 1.5 times BT concentration in the fixed bed system. Finally, a general rate model (GRM) was used to predict the dynamic adsorption/desorption processes successfully. The transient process of BT pre-concentration in the presence of desorbent ethanol was vividly displayed by Matlab, which revealed the individual behaviors of BT and ethanol during the adsorption/desorption process. It further proved the competitive adsorption could be the reason for the BT pre-concentration.

A new spatial phase unwrapping algorithm based on single-pixel binarized line pattern is proposed. The conventional spatial phase unwrapping method produces easily the accumulation and propagation of errors for the wrapped phase in the regions with isolated 2π jumps generated by shadow and sharp changing surfaces. In this paper, the single-pixel binarized (SPB) deformed line pattern extracted by the proposed small window retrieval (SWR) method can determine accurately the corresponding fringe order, then the wrapped phase is unwrapped point-to-point, in which the small window is adaptive for each light line. The measuring accuracy of the proposed method is closed to the quality-guided method with high precision, but it performs simultaneously higher robustness to measure the multi-object. Only one additional SPB line pattern is projected and the phase unwrapping process does not involve a time-consuming point-by-point sorting, so the proposed method can be applied to the real-time 3D measurement. The experimental results verify the feasibility and effectiveness of the proposed method.

A real-time three-dimensional(3D) shape measuring method based on dual-frequency spatial phase-shifting measuring profilometry (SPSMP) is proposed. To combine the low-frequency and high-frequency gratings into one single composite pattern, each individual grating is modulated along orthogonal direction with a distinct carrier frequency. Since the spectrum components are staggered in the spectrum of the composite deformed pattern, the low-frequency and high-frequency deformed patterns with background light can be demodulated easily. Then two groups of spatial phase-shifting deformed sub-patterns are extracted from the corresponding deformed patterns to calculate the low-frequency wrapped phase and the high-frequency wrapped phase. According to the dual-frequency phase unwrapping algorithm, the high-frequency wrapped phase is guided by the low-frequency unwrapped phase. Compared to the existing multi-frequency single-shot fringe projection, the filtering process of the proposed method is more concise, it does not involve multiple filtering and the extraction of the single spectrum component. The static and real-time experimental results show that the proposed method inherits the high accuracy of PMP, while guaranteeing single-shot feature.

In this paper, a generalized spatial-temporal phase unwrapping algorithm (STPUA) is proposed for extracting the absolute phase of the isolated objects with intricate surfaces. This proposed algorithm can eliminate thoroughly the order jumps of various temporal phase unwrapping algorithms (TPUAs), while inheriting the high measuring accuracy of quality-guided phase unwrapping algorithms (QGPUAs). Differing from the traditional phase unwrapping algorithms, wrapped phase is first divided into several regional wrapped phases, which can be extracted successively according to its areas and unwrapped individually by QGPUAs. Meanwhile, a series of reliable points from the fringe order map obtained from the code deformed patterns are selected to map the corresponding regional unwrapped phases into an absolute phase. The radii of selecting reliable points can provide the high measuring robustness compared with the classical point-to-point TPUAs for the complex surfaces and the motion blur, while keeping the same number of patterns. Therefore, the proposed STPUA combining SPUAs and TPUAs also can be employed in real-time three-dimensional (3D) reconstruction. Theoretical analysis and experimental results are performed to verify the effectiveness and capability of the proposed algorithm.

In this study, the aging of culturable FIB and DNA representing genetic markers for Enterococcus spp. (ENT1A), general Bacteroides (GB3), and human-associated Bacteroides (HF183) in freshwater sediments was evaluated. Freshwater sediment was collected from four different sites within the upper and lower reach of the Topanga Creek Watershed and two additional comparator sites within the Santa Monica Bay, for a total of six sites. Untreated (ambient) and oven-dried (reduced microbiota) sediment was inoculated with 5% sewage and artificial freshwater. Microcosms were held for a 21-day period and sampled on day 0, 1, 3, 5, 7, 12, and 21. There were substantial differences in decay among the sediments tested, and decay rates were related to sediment characteristics. In the ambient sediments, smaller particle size and higher levels of organic matter and nutrients (nitrogen and phosphorus) were associated with increased persistence of the GB3 marker and culturable Escherichia coli (cEC) and enterococci (cENT). The HF183 marker exhibited decay rates of −0.50 to −0.96 day −1 , which was 2–5 times faster in certain ambient sediments than decay of culturable FIB and the ENT1A and GB3 markers. The ENT1A and GB3 markers decayed at rates of between −0.07 and −0.28 and −0.10 to −0.44 day −1 , and cEC and cENT decayed at rates of between −0.22 and −0.81 and −0.03 and −0.40 day −1 , respectively. In the oven-dried sediments, increased persistence of all indicators and potential for limited growth of culturable FIB and the GB3 and ENT1A markers was observed. A simplified two-box model using the HF183 marker and cENT decay rates generated from the microcosm experiments was applied to two reaches within the Topanga Canyon watershed in order to provide context for the variability in decay rates observed. The model predicted lower ambient concentrations of enterococci in sediment in the upper (90 MPN g −1 ) versus lower Topanga watershed (530 MPN g −1 ) and low ambient levels of the HF183 marker (below the LLOQ) in sediments in both lower and upper watersheds. It is important to consider the variability in the persistence of genetic markers and FIB when evaluating indicators of fecal contamination in sediments, even within one watershed.

Hydrocolloids can greatly influence the structure and functionalities of modern foods, mainly due to their interactions with other components present in complex food matrices. This review outlines three main categories of hydrocolloid-food component interactions: hydrocolloid-ion, hydrocolloid-small molecule, and hydrocolloid-hydrocolloid interactions. Examples are given to illustrate the impact of the interactions on the structure, stability, functional properties of foods, and their utilizations in food technologies such as separation/purification, gelation, emulsification, and encapsulation etc.

As major equipment for implementing technological process, Shell-and-Tube Heat Exchangers are widely used in modern industries. Because the noise propagation in pipelines in shell-and-tube heat exchangers can’t be ignored, it is a key point to investigate the transfer mechanism of sound energy in pipelines and develop high efficiency mufflers with low penalty of pressure drop. Different with the traditional method, this study is focused on the flow and sound fields synergy principle to investigate the flow noise propagation mechanism in pipelines. In this study, theoretical analysis and numerical simulation methods are coupled to investigate the pipeline noise propagation process. Based on the momentum and the energy equations in the sound field, the synergetic relationship between the flow field and the pressure gradient field is deduced, and the field synergy theory is established. The flow noise propagation process of noise in the pipeline is studied by numerical simulation. The synergy is verified by analyzing the calculating results of flow and sound fields. The results show that with the increase of synergy between flow and sound fields, the work done by the fluid on the wall increases, which means the exchange of sound energy between the wall and the fluid increases.

In the three-dimensional (3D) measurement, phase measuring profilometry (PMP) requires no less than three deformed sinusoidal patterns, limiting its applications to static scenarios only. In this paper, a stroboscopic online PMP for fast rotating object with binary dithered patterns is proposed. N frames of novel circular binary grating patterns are designed to measure a rotating object. A defocused digital light projector projects the designed patterns onto the object with stroboscopic method, the corresponding deformed patterns can be “frozen” by charge-coupled device (CCD) camera. Owing to the repeatability and periodicity of rotating movement, a synchronization control unit is used to keep the object at the fixed position in each “frozen” deformed pattern. Every projected pattern is shifted from the previous pattern by a factor of 2π/N. This method makes the images of the object appear stationary in the deformed patterns. The experimental results show the accurate 3D shape of fast rotating object can be reconstructed with the proposed method.

A fast pixel matching method based on phase feature extraction in online phase-measuring profilometry is proposed, which is used to solve the problem where the object motion is along a straight line. The movement of the object results in the displacement of images in the captured deformed patterns, so pixel matching is carried out to modify the positions of images, which not only realizes the point-to-point correspondence of the object, but extracts the equivalent phase-shifting deformed patterns. So, the 3D surface shape of the object moving on the pipeline can be reconstructed successfully with an equivalent phase-shifting algorithm. The equiphase surface phase feature extracted from the phase distributions of the object obtained by Fourier transform profilometry is used to assist pixel matching in this paper. Normalization and further binarization of the phase feature extraction improve pixel matching’s accuracy and speed. The simulation and experiments verify the feasibility and validity of th...

Osteoarthritis (OA) is a complex disease that affects the whole joint, resulting from the combined influence of biomechanical factors and genetic factors. The heritable component for primary OA accounts for about 60% of variation in population liability to the disease. So far, genome-wide association studies (GWAS) and candidate gene studies have established many OA-related loci. However, these findings account for only a rather small fraction of the genetic component. To further reveal the genetic architecture of OA, we conducted this case-control study to explore the association of locus EN1 rs4144782 and knee OA susceptibility in a Chinese population. EN1 rs4144782 was significantly associated with increased risk of knee OA (OR=1.26; 95% CI: 1.05-1.50, P value=0.012). In dominant model, compared with carriers of GG genotype, those with AG or AA genotype have an 1.44-fold increased risk of OA (OR: 1.44; 95% CI: 1.10-1.88; P value=0.008). Subgroup analyses didn't change the results materially. This should be the first association study of EN1 locus on risk of OA, and our finding suggested that the EN1 rs4144782 might contribute to the susceptibility of knee OA.

Organophosphorus (OP) pesticides are primarily used as insecticides and chemical warfare agents worldwide. Due to their impact on the environment and health, it is important to develop prompt and accurate pesticide analysis method. This review addresses recent advances and new trends in nanotechnology-based biosensors for biological monitoring of exposures to OP pesticides and nerve agents. In order to determine them, we have to find the corresponding biomarkers. In 1989, the national academy of sciences (NAS)divided biomarkers into the following three categories: biomarker of exposure, biomarker of effect and biomarker of susceptibility (Figure 1A). The unique chemical and physical properties of nanomaterial have paved the way to new and improved sensing devices, in general, and electrochemical/optical biosensors, in particular. In this paper, background information and a general overview of electrochemical/immunoassay detection techniques are provided. Various nanomaterial labels are discussed. Usually nanomaterials can be roughly divided into nanometer powder, nanometer fiber, nanometer film, nanometer block and so on four classes, such as colloidal gold, semiconductor nanoparticles and carbon nanomaterial (Figure 1B). In addition, we discuss some future considerations and opportunities for advancing the use of biosensors for environmental and health studies.

A dual-frequency online phase measurement profilometry (PMP) method with phase-shifting parallel to moving direction of measured object is proposed in this paper. The high-frequency fringe is used for the better modulation patterns in pixel matching and it is not modified by the measured object’s surface. Based on the relative positive between the moving measured object and digital light processing (DLP), the high-frequency fringe in each dual-frequency deformed pattern after pixel matching is the same. As a result, the phase can be calculated directly by the improved Stoilov algorithm without filtering out the low-frequency component containing the measured object’s height information. As there is no filtering process in phase calculation, the valid information loss can be avoided so that the accuracy of the proposed method can be guaranteed. Simulations and experiments prove the method’s feasibility and precision.

In order to determine Dynamic 3-D shape with vertical measurement mode, a fast modulation measuring profilometry (MMP) with a cross grating projection and single shot is proposed. Unlike the previous methods, in our current projection system, one cross grating is projected by a special projection lens consisting of a common projection lens and a cylindrical lens. Due to the characteristics of cylindrical lens, the image of the vertical component and the horizontal component of the cross grating is separated in the image space, and the measuring range is just the space between the two image planes. Through a beam splitter, the CCD camera can coaxially capture the fringe pattern of the cross grating modulated by the testing object׳s shape. In one fringe pattern, by applying Fourier transform, filtering and inverse Fourier transform, the modulation corresponding to the vertical and horizontal components of the cross grating can be obtained respectively. Then the 3-D shape of the object can be reconstructed according to the mapping relationship between modulation and height, which was established by calibration process in advance. So the 3-D shape information can be recorded at the same speed of the frame rate of the CCD camera. This paper gives the principle of the proposed method and the set-up for measuring experiment and system calibration. The 3-D shape of a still object and a dynamic process of liquid vortex were measured and reconstructed in the experiments, and the results proved the method’s feasibility. The advantage of the proposed method is that only one fringe pattern is needed to extract the modulation distribution and to reconstruct the 3-D shape of the object. Therefore, the proposed method can achieve high speed measurement and vertical measurement without shadow and occlusion. It can be used in the dynamic 3-D shape measurement and vibration analysis.

A computer-assisted human peripheral blood leukocyte image classification method based on Siamese network is proposed. Firstly, a Siamese network with two identical convolutional neural network (CNN) sub-networks and a logistic regression for leukocyte five classification is designed, which can learn not only distinguishing features but also a similarity metric. Then for each category of the leukocytes, a typical sample is selected by the hematologist. To train the Siamese network, a leukocyte and a typical sample that belong to the same category make up a genuine pair and the leukocyte with the rest four typical samples respectively make up four impostor pairs. Obviously, the number of the genuine pairs is lesser than that of the impostor pairs. Thus, a data augmentation method suitable for leukocyte is used to enrich the amount of the genuine pairs. By training the Siamese network using the genuine pairs and impostor pairs, the Siamese network can not only shorten the similarity metric between the leukocyte and the same category of the typical sample but also increase the similarity metrics between the leukocyte and the different categories of the typical samples. Experimental results indicate that the proposed method can achieve 98.8% average testing accuracy. Graphical abstract.

Fecal microorganisms can enter water bodies in diverse ways, including runoff, sewage discharge, and direct fecal deposition. Once in water, the microorganisms experience conditions that are very different from intestinal habitats. The transition from host to aquatic environment may lead to rapid inactivation, some degree of persistence, or growth. Microorganisms may remain planktonic, be deposited in sediment, wash up on beaches, or attach to aquatic vegetation. Each of these habitats offers a panoply of different stressors or advantages, including UV light exposure, temperature fluctuations, salinity, nutrient availability, and biotic interactions with the indigenous microbiota (e.g., predation and/or competition). The host sources of fecal microorganisms are likewise numerous, including wildlife, pets, livestock, and humans. Most of these microorganisms are unlikely to affect human health, but certain taxa can cause waterborne disease. Others signal increased probability of pathogen presence, e.g., the fecal indicator bacteria Escherichia coli and enterococci and bacteriophages, or act as fecal source identifiers (microbial source tracking markers). The effects of environmental factors on decay are frequently inconsistent across microbial species, fecal sources, and measurement strategies (e.g., culture versus molecular). Therefore, broad generalizations about the fate of fecal microorganisms in aquatic environments are problematic, compromising efforts to predict microbial decay and health risk from contamination events. This review summarizes the recent literature on decay of fecal microorganisms in aquatic environments, recognizes defensible generalizations, and identifies knowledge gaps that may provide particularly fruitful avenues for obtaining a better understanding of the fates of these organisms in aquatic environments.

The latest generation of wearable devices features materials that are flexible, conductive, and stretchable, thus meeting the requirements of stability and reliability. However, the metal conductors that are currently used in various equipments cannot achieve these high performance expectations. Hence, a mussel-inspired conductive hydrogel (HAC-B-PAM) is prepared with a facile approach by employing polyacrylamide (PAM), dopamine-functionalized hyaluronic acid (HAC), borax as a dynamic cross-linker agent, and Li+ and Na+ as conductive ions. HAC-B-PAM hydrogels demonstrate an excellent stretchability (up to 2800%), high tensile toughness (42.4 kPa), self-adhesive properties (adhesion strength to porcine skin of 49.6 kPa), and good self-healing properties without any stimuli at room temperature. Furthermore, the fabricated hydrogel-based strain sensor is sensitive to deformation and can detect human body motion. Multifunctional hydrogels can be assembled into flexible wearable devices with potential applications in the field of electronic skin and soft robotics.

Amyloid fibrils have traditionally been considered only as pathological aggregates in human neurodegenerative diseases, but it is increasingly becoming clear that the propensity to form amyloid fibrils is a generic property for all proteins, including food proteins. Differently from the pathological amyloid fibrils, those derived from food proteins can be used as advanced materials in biomedicine, tissue engineering, environmental science, nanotechnology, material science as well as in food science, owing to a combination of highly desirable feature such as extreme aspect ratios, outstanding stiffness and a broad availability of functional groups on their surfaces. In food science, protein fibrillization is progressively recognized as an appealing strategy to broaden and improve food protein functionality. This review article discusses the various classes of reported food protein amyloid fibrils and their formation conditions. It furthermore considers amyloid fibrils in a broad context, from their structural characterization to their forming mechanisms and ensued physical properties, emphasizing their applications in food-related fields. Finally, the biological fate and the potential toxicity mechanisms of food amyloid fibrils are discussed, and an experimental protocol for their health safety validation is proposed in the concluding part of the review.

Currently, there are approximately 170 million hyperuricemia patients in China. Conventional drug therapy has limited clinical benefits and may induce serious side effects. Enzyme replacement therapy has attracted much attention owing to its advantages of strong specificity, small dosage, and remarkable curative effect. Uricase is an efficient oxidase, which can oxidize uric acid to allantoin and hydrogen peroxide, to reduce the uric acid level. In this study, we used a mild biomimetic method to prepare a novel uricase and horseradish peroxidase (HRP) loaded CaHPO₄ nanoflower (uricaseHRP-CaHPO₄ nanoflower). The nanoflower was then integrated with a hyaluronic acid dissolvable microneedle system (uricaseHRP-CaHPO₄ @HA MN) to achieve transdermal drug delivery for the treatment of hyperuricemia, which has high patient compliance. In this system, the stability and catalytic activity of uricase could be improved by the CaHPO₄ nanoflower, and HRP could decompose the hydrogen peroxide to accelerate the reaction of uricase. An

A dynamic phase measuring profilometry (PMP) based on tricolor binary fringe combined time-division multiplexing principle is proposed. Only one tricolor binary fringe combined by red (R), green (G), and blue (B) binary fringes with the same fringe width but without any color overlapping one another is needed and sent into the flash memory of a high-speed digital light projector (HDLP) in advance. A specialized time-division multiplexing timing sequence is designed to control the HDLP to project the tricolor binary fringe saved in the flash memory onto the measured dynamic object separately and sequentially at 234 fps, at the same time, the projected light source mode is set as monochrome mode which means that all the RGB LEDs remain lighting. Meanwhile, it also triggers a high frame rate monochrome camera synchronized with the HDLP to capture the corresponding deformed patterns in R, G and B channels. By filtering, the nearly unbroken phase-shifting sinusoidal deformed patterns for three-step PMP can be extracted from the captured deformed patterns. It is equivalent to the three-dimensional (3D) shape reconstruction of the measured dynamic object at 78 fps. Experimental results verify the feasibility and the validity of the proposed method. It is effective for measuring the dynamic object and can avoid the color cross-talk effectively.

The Southern California Bight (SCB) is a unique and valuable ecological and economic resource. It is also vulnerable to environmental pressures, with > 30 million inhabitants. Collectively since 1994, SCB dischargers, regulators, academics, and nongovernmental organizations have collaborated in a regional monitoring program to assess ocean health. In this chapter, we describe the most recent key findings and trends, focusing on sediment quality, trash, beach water quality, and ocean acidification (OA). Sediment quality in the SCB is generally good, with only 6% of the region having impacted sediment chemistry, sediment toxicity, and/or benthic infauna. However, not all habitats are in equally good condition, with embayments (i.e., marinas, estuaries) experiencing the greatest extent of impacts. Despite their impacts, SCB embayment sediment quality has improved over the past 15 years. Trash is widespread in the SCB, especially plastic, covering 25% of the seafloor. This extent has been increasing steadily for 20 years. The results are consistent with coastal SCB watershed surveys, where trash is observed in every urbanized stream sampled. This trash is subsequently discharged to the ocean during storm events. Beach water quality in the SCB is generally safe to swim. Only 3% of the SCB shoreline km-days exceed water quality standards for bacteria during the summer months, which attracts 1.75 × 108 beachgoers each year. During or immediately following wet weather, however, the extent quickly increases to 65% of the shoreline km-days exceeding standards. The SCB is vulnerable to OA owing to its narrow continental shelf, which can bring deeper corrosive water close to shore. SCB surveys observed corrosive water (defined as aragonite saturation state 100 m. Corrosive waters were most widespread in spring, consistent with regional upwelling events.

In this paper, we propose a new single-shot three-dimensional (3D) measuring method based on quaternary grating projection. In traditional binary grating phase measuring profilometry (PMP), a multi-step or color fringe pattern are usually used to extract the sinusoidal fringes. In our proposed method, by using the DLP4500’s 2-bit gray coding mode, the grayscale is quaternary. The three non-zero grayscales cyclically arranged in equal width, and the fourth grey value is 0 which is not encoded in the fringe pattern but represents the shadow information in the deformed pattern, where a quaternary grating is encoded. When the DLP4500 projects the quaternary grating onto the measured object, the charge coupled device (CCD) captures the corresponding deformed pattern synchronously. Three frames of binary deformed patterns with 1/3 duty cycle and a relative displacement of 1/3 period can be decomposed by the segmentation algorithm proposed in this paper. Three sinusoidal deformed patterns with a 2π/3 shift-phase can be obtained by extracting the fundamental frequency of the three binary deformed patterns correspondingly, and the 3D shape of the object can be reconstructed by PMP. Experimental results show the effectiveness and feasibility of the proposed method. Because the DLP4500 only needs 2-bit coded grating for projection, the refresh rate of the projected grating is as high as 1428 Hz, which will have a broad application prospect in real time and fast online measurement.

An improved computer-generated moiré profilometry (CGMP) with flat image calibration is proposed. In CGMP, the purification of the AC component plays a decisive role. While a composite grating modulated with both the sinusoidal grating and its background light substitutes for the sinusoidal grating itself, the sinusoidal deformed pattern and flat image can be demodulated from the captured pattern. It is found that the sinusoidal deformed pattern and flat image may deviate, which is caused by ambient light. So flat image calibration is conducted to obtain a purer AC component that can effectively suppress the influence of ambient light and ensure the measurement accuracy, even if spectrum aliasing exists. Experimental results show the feasibility and validity of the proposed method.

Flow-induced noise and vibration problems of tube bundles in heat-exchangers exist for a long time and often cause severe destruction, performance reduction and large maintenance charge. It is essential to study the flow-induced noise in tube bundles and develop high-efficiency noise elimination measures. The theoretical analysis and numerical simulation method are coupled to compare the aerodynamic noise and heat transfer in shell-and-tube heat exchangers with continuous helical and segmental baffles. The novelty of this paper is to compare the flow-induced noise of tube bundles in shell-and-tube heat-exchangers with continuous helical and segmental baffles. And as an initial trial, this study intends to investigate the aerodynamic noise based on the flow field and acoustic field matching perspective. The results show that the sound pressure, the pressure drop per unit tube length and the Nusselt number all increase with the increase of Reynolds number. And the average synergy angle of continuous helical baffles is 11％ lower than that of segmental baffles, which corresponds with 23-37％ lower sound pressure.

An accuracy improving method for composite grating phase measuring profilometry (CGPMP) based on mixed filtering window is proposed. When CGPMP is used to carry out three-dimensional (3D) measurement, the phase-shifting deformed patterns can be demodulated effectively from the captured composite deformed pattern by proper filters. So the selection of the filtering window is very important. By analyzing the characteristics of noises and their different effects on the spectrum components along different orientations, searching for the best filtering window of the spatial spectrum along the two mutually orthogonal directions, a mixed filtering window to improve measuring accuracy is established. Digital simulating results show that the designedly mixed filtering window has better noise suppression than rectangular, triangular, Blackman and Hanning filtering windows. The experimental results show that the measuring error using the mixed filtering window equalizing noise and spectrum leakage is the smallest, and the root mean square error (RMSE) is reduced by 9.64%, and the measuring accuracy is improved effectively.

Understanding the fate of enteric viruses in water is vital for protection of water quality. However, the decay of enteric viruses is not well characterized, and its uncertainty has not been examined yet. In this study, the decay of coliphages, an indicator for enteric viruses, was investigated in situ under both sunlit and shaded conditions as well as in summer and winter. The decay rates of coliphages and their uncertainties were analyzed using a Bayesian approach. The results from the summer experiments revealed that the decay rates of somatic coliphages were significantly higher in sunlight (1.29 ± 0.06 day–1) than in shade (0.96 ± 0.04 day–1), but the decay rates of male-specific (F+) coliphages were not significantly different between sunlight (1.09 ± 0.09 day–1) and shaded treatments (1.11 ± 0.08 day–1). The decay rates of both F+ coliphages (0.25 ± 0.02 day–1) and somatic coliphages (0.12 ± 0.01 day–1) in winter were considerably lower than those in summer. Temperature and chlorophyll a (chla) con...

A real-time tricolor phase measuring profilometry (RTPMP) based on charge coupled device (CCD) sensitivity calibration is proposed. Only one colour fringe pattern whose red (R), green (G) and blue (B) components are, respectively, coded as three sinusoidal phase-shifting gratings with an equivalent shifting phase of 2π/3 is needed and sent to an appointed flash memory on a specialized digital light projector (SDLP). A specialized time-division multiplexing timing sequence actively controls the SDLP to project the fringe patterns in R, G and B channels sequentially onto the measured object in one over seventy-two of a second and meanwhile actively controls a high frame rate monochrome CCD camera to capture the corresponding deformed patterns synchronously with the SDLP. So the sufficient information for reconstructing the three-dimensional (3D) shape in one over twenty-four of a second is obtained. Due to the different spectral sensitivity of the CCD camera to RGB lights, the captured deformed patt...

Grayscale imbalance correction in real-time phase measuring profilometry (RPMP) is proposed. In the RPMP, the sufficient information is obtained to reconstruct the 3D shape of the measured object in one over twenty-four of a second. Only one color fringe pattern whose R, G and B channels are coded as three sinusoidal phase-shifting gratings with an equivalent shifting phase of 2π/3 is sent to a flash memory on a specialized digital light projector (SDLP). And then the SDLP projects the fringe patterns in R, G and B channels sequentially onto the measured object in one over seventy-two of a second and meanwhile a monochrome CCD camera captures the corresponding deformed patterns synchronously with the SDLP. Because the deformed patterns from three color channels are captured at different time, the color crosstalk is avoided completely. But due to the monochrome CCD camera's different spectral sensitivity to R, G and B tricolor, there will be grayscale imbalance among these deformed patterns captured at R, G and B channels respectively which may result in increasing measuring errors or even failing to reconstruct the 3D shape. So a new grayscale imbalance correction method based on least square method is developed. The experimental results verify the feasibility of the proposed method.

In online 3D measurement, a new method using orthogonal two-frequency grating based on Phase Measuring Profilometry(PMP) is proposed. The modulation of the entire measured object is used to match pixels and this proposed method successfully resolves the contradiction of the demand for different frequency fringes between the extraction of the modulation information and the phase unwrapping. The high-frequency fringe is used to catch the better modulation patterns for pixel matching, and the low-frequency fringe is used to calculate the phase distribution and avoid phase unwrapping error. In addition, to extract the better modulation patterns for pixel matching, the flat filtering window replaces the circular filtering window to avoid the spectrum aliasing phenomenon. The simulations and experiments show its feasibility.

© 2016 Elsevier Ltd. Introduction: Advances in molecular methods provide new opportunities for directly measuring pathogens or host-associated markers of fecal pollution instead of relying on fecal indicator bacteria (FIB) alone for beach water quality monitoring. Adoption of new indicators depends on identifying relationships between either the presence or concentration of the indicators and illness among swimmers. Here we present results from three epidemiologic studies in which a broad range of bacterial and viral indicators of fecal contamination were measured simultaneously by either culture or molecular methods along with Enterococcus to assess whether they provide better health risk prediction than current microbial indicators of recreational water quality. Methods: We conducted prospective cohort studies at three California beaches -- Avalon Bay (Avalon), Doheny State Beach (Doheny), Surfrider State Beach (Malibu) -- during the summers of 2007, 2008 and 2009. The studies enrolled 10,785 swimmers across the beaches and recorded each swimmer's water exposure. Water and sand samples were collected several times per day at multiple locations at each beach and analyzed for up to 41 target indicators using 67 different methodologies. Interviewers contacted participants by phone 10-14 days later and recorded symptoms of gastrointestinal illness occurring after their beach visit. Regression models were used to evaluate the association between water quality indicators and gastrointestinal illness among swimmers at each beach. Results: F+ coliphage (measured using EPA Method 1602) exhibited a stronger association with GI illness than did EPA Method 1600 at the two beaches where it was measured, while a molecular method, F+ RNA Coliphage Genotype II, was the only indicator significantly associated with GI illness at Malibu. MRSA, a known pathogen, had the strongest association with GI illness of any microbe measured at Avalon. There were two methods targeting human-associated fecal anaerobic bacteria that were more strongly associated with GI illness than EPA Method 1600, but only at Avalon. No indicator combinations consistently had a higher odds ratio than EPA Method 1600, but one composite indicator, based on the number of pathogens detected at a beach, was significantly associated with gastrointestinal illness at both Avalon and Doheny when freshwater flow was high. Discussion: While EPA Method1600 performed adequately at two beaches based on its consistency of association with gastrointestinal illness and the precision of its estimated associations, F+ coliphage measured by EPA Method 1602 had a stronger association with GI illness under high risk conditions at the two beaches where it was measured. One indicator, F+ Coliphage Genotype II was the only indicator significantly associated with GI illness at Malibu. Several indicators, particularly those targeting human associated bacteria, exhibited relationships with GI illness that were equal to or greater than that of EPA Method 1600 at Avalon, which has a focused human fecal source. Our results suggest that site-speci fic conditions at each beach determine which indicator or indicators best predict GI illness.

Quantitative polymerase chain reaction (qPCR) has become a frequently used technique for quantifying enterococci in recreational surface waters, but there are several methodological options. Here we evaluated how three method permutations, type of mastermix, sample extract dilution and use of controls in results calculation, affect method reliability among multiple laboratories with respect to sample interference. Multiple samples from each of 22 sites representing an array of habitat types were analyzed using EPA Method 1611 and 1609 reagents with full strength and five-fold diluted extracts. The presence of interference was assessed three ways: using sample processing and PCR amplifications controls; consistency of results across extract dilutions; and relative recovery of target genes from spiked enterococci in water sample compared to control matrices with acceptable recovery defined as 50 to 200%. Method 1609, which is based on an environmental mastermix, was found to be superior to Method 1611, which is based on a universal mastermix. Method 1611 had over a 40% control assay failure rate with undiluted extracts and a 6% failure rate with diluted extracts. Method 1609 failed in only 11% and 3% of undiluted and diluted extracts analyses. Use of sample processing control assay results in the delta-delta Ct method for calculating relative target gene recoveries increased the number of acceptable recovery results. Delta-delta tended to bias recoveries from apparent partially inhibitory samples on the high side which could help in avoiding potential underestimates of enterococci--an important consideration in a public health context. Control assay and delta-delta recovery results were largely consistent across the range of habitats sampled, and among laboratories. The methodological option that best balanced acceptable estimated target gene recoveries with method sensitivity and avoidance of underestimated enterococci densities was Method 1609 without extract dilution and using the delta-delta calculation method. The applicability of this method can be extended by the analysis of diluted extracts to sites where interference is indicated but, particularly in these instances, should be confirmed by augmenting the control assays with analyses for target gene recoveries from spiked target organisms.

We evaluated the ability of chip-based digital PCR (dPCR) to quantify enterococci, the fecal indicator recommended by the United States Environmental Protection Agency (USEPA) for water-quality monitoring. dPCR uses Poisson statistics to estimate the number of DNA fragments in a sample with a specific sequence. Underestimation may occur when a gene is redundantly encoded in the genome and multiple copies of that gene are on one DNA fragment. When genomic DNA (gDNA) was extracted using two commercial DNA extraction kits, we confirmed that dPCR could discern individual copies of the redundant 23s rRNA gene in the enterococcal genome. dPCR quantification was accurate when compared to the nominal concentration inferred from fluorometer measurements (linear regression slope = 0.98, intercept = 0.03, R(2) = 0.99, and p value

Enzyme-based electrochemical biosensors with sufficient sensing specificity are useful analytical tools for detection of biologically important substances in complicated systems. Here, we present the design of a nano-hybrid biosensor for the specific and sensitive detection of methyl parathion (MP). The nano-hybrid sensing film was prepared via the formation of Au nanoparticals (AuNPs) on silica nanoparticles (SiNPs), mixing with multiwall carbon nanotube (MWNTs) and subsequent immobilization of methyl parathion degrading enzyme (MPD). The fabrication procedure was characterized by scanning electron images, linear scan voltammetry and electrochemical impedance spectroscopy. The combined MPD exhibited high affinity to it substrate and thus a selective, sensitive, fast and cheap method for determination of MP, quantitatively was proposed. A significant synergistic effect of nano-hybrid on the biosensor performance was observed in biosensing MP. The square wave voltammetric responses displayed well defined peaks, linearly proportional to the concentration of MP in the range from 0.001 to 5.0 μg/mL with a detection limit of 0.3 ng/mL. The proposed biosensor also showed good precision and reproducibility, acceptable stability and accuracy in garlic samples analysis. It provided a platform for the simple and fast construction of biosensors with good performance for the determination of enzyme-specific electroactive species.

This work demonstrates a bottom-up model of fabricating a honeycomb-inspired interface consisting of micro- and nanostructures for improving poly(dimethylsiloxane) (PDMS) hydrophobicity. TiO2 nanorod arrays and microsized voids were fabricated by a two-step hydrothermal reaction method. First, rutile TiO2 nanorod arrays were hydrothermally fabricated on the fluorine-doped SnO2 conductive substrates substrate. Second, microsized TiO2 voids were synthesized through HCl hydrothermal etching to obtain a honeycomb-inspired interface with tunable size. The size of the etched voids increased from 0.22 ± 0.06 to 8.0 ± 2.8 μm. The interfaces were then transferred on the PDMS surface to improve hydrophobic property. The contact angles of the corresponding positive PDMS replicas reached 140° after etching with the TiO2 nanorod arrays for 10 h. The size of mastoid structures on the PDMS surfaces was 7.5 μm, which is similar to the size of microstructures on the lotus leaf surface. The fabricated PDMS surface with tunable hydrophobicity properties can be used in the microfluidic channels in the future.

High resolution, real-time three-dimensional (3D) measurement plays an important role in many fields. In this paper, a multi-directional dynamic real-time phase measurement profilometry based on improved optical flow is proposed. In a five-step phase shifting dynamic measurement, pixel matching is needed to make the pixels one-to-one corresponding in five patterns. However, in the frequently-used pixel matching method at present, it is necessary to calculate the correlation and traverse the whole deformed pattern for the motion information of the measured object. The huge amount of computation caused by correlation computation takes up most of the time in the process of the entire 3D reconstruction, so it can not meet the requirement of real-time dynamic measurement. In order to solve the problem, the improved optical flow algorithm is introduced to replace correlation calculation in pixel matching. In one measurement, five captured patterns need to be dealt with, and the optical flow between each two adjacent frames is calculated. Then four two-dimensional vector matrices can be obtained. The vector matrices contain the complete motion information of the measured object. Experiments and simulations prove that this method can improve the efficiency of pixel matching by 42 times and 3D reconstruction by 32 times on the premise of ensuring the accuracy.

In traditional composite-structured-light profilometry, the N-frame carrier gratings and modulated phase-shifting sinusoidal gratings must share a 256-greyscale dynamic range, which is the standard for commercial digital light projectors (DLPs). Additionally, each of the demodulated phase-shift gratings must possess a 43-greyscale dynamic range. This decreases the greyscale dynamic range for each of the demodulated gratings and compresses the phase information. Consequently, measurement accuracy is a challenge, even for incomplete reconstructions. To solve this problem, we propose a new composite-structured-light profilometry using greyscale expansion. Specifically, a composite video is synthesised using three different purposefully designed patterns, each possessing a 256-greyscale dynamic range. These patterns are used as the composite-structured-light to replace the traditional static composite grating. After projecting the repetitive video onto a measured object and controlling the exposure time of the charge-coupled device camera, the deformed composite 766-greyscale pattern can be stably captured. Furthermore, after demodulation, the dynamic range of the deformed demodulated patterns can be expanded up to 229. Numerical and experimental results indicate that the proposed method can be used to divide the single 256-greyscale DLP standard and accurately reconstruct measured objects.

In multi-view fringe projection profilometry (FPP), a limitation of geometry-constraint based approaches is the reduced measurement depth range often used to reduce the number of candidate points and increase the corresponding point selection reliability, when high-frequency fringe patterns are used. To extend the depth range, a new method of high-frequency fringe projection profilometry was developed by color encoding the projected fringe patterns to allow reliable candidate point selection even when six candidate points are in the measurement volume. The wrapped phase is directly retrieved using the intensity component of the hue-saturation-intensity (HSI) color space and complementary-hue is introduced to identify color codes for correct corresponding point selection. Mathematical analyses of the effect of color crosstalk on phase calculation and color code identification show that the phase calculation is independent of color crosstalk and that color crosstalk has little effect on color code identification. Experiments demonstrated that the new method can achieve high accuracy in 3D measurement over a large depth range and for isolated objects, using only two high-frequency color-encoded fringe patterns.

A real-time computer-generated moire profilometry (CGMP) with adaptive filtering algorithm is proposed. In CGMP proposed previously, only one static sinusoidal grating needs to be projected onto the measured object and only one deformed pattern caused by the object needs to be captured, which is ideal for real-time three-dimensional (3-D) measurement. By means of generating moire fringes between the captured deformed pattern and the prestored fringe patterns on the reference plane via computer, the 3-D shape of the measured object can be reconstructed successfully. In phase calculating, this method needs to extract the DC component by filtering. If filtering operation required manual intervention each time, its real-time measuring feature may be limited. For this, an adaptive filtering algorithm based on the maximum fundamental frequency component proportion evaluation function is proposed. It can automatically retrieve an object’s phase information according to the Fourier spectrum distributions of different measured objects without any manual intervention. Experimental results demonstrate the feasibility and validity of the real-time 3-D measuring application.