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1.
The India-Asia collision is an outstanding smoking gun in the study of continental collision dynamics. How and when the continental collision occurred remains a long-standing controversy. Here we present two new paleomagnetic data sets from rocks deposited on the distal part of the Indian passive margin, which indicate that the Tethyan Himalaya terrane was situated at a paleolatitude of ∼19.4°S at ∼75 Ma and moved rapidly northward to reach a paleolatitude of ∼13.7°N at ∼61 Ma. This implies that the Tethyan Himalaya terrane rifted from India after ∼75 Ma, generating the North India Sea. We document a new two-stage continental collision, first at ∼61 Ma between the Lhasa and Tethyan Himalaya terranes, and subsequently at ∼53−48 Ma between the Tethyan Himalaya terrane and India, diachronously closing the North India Sea from west to east. Our scenario matches the history of India-Asia convergence rates and reconciles multiple lines of geologic evidence for the collision.  相似文献   

2.
A simple microfluidic 3D hydrodynamic flow focusing device has been developed and demonstrated quantitative determinations of quantum dot 525 with antibody (QD525-antibody) and hemagglutinin epitope tagged MAX (HA-MAX) protein concentrations. This device had a step depth cross junction structure at a hydrodynamic flow focusing point at which the analyte stream was flowed into a main detection channel and pinched not only horizontally but also vertically by two sheath streams. As a result, a triangular cross-sectional flow profile of the analyte stream was formed and the laser was focused on the top of the triangular shaped analyte stream. Since the detection volume was smaller than the radius of laser spot, a photon burst histogram showed Gaussian distribution, which was necessary for the quantitative analysis of protein concentration. By using this approach, a linear concentration curve of QD525-antibody down to 10 pM was demonstrated. In addition, the concentration of HA-MAX protein in HEK293 cell lysate was determined as 0.283 ± 0.015 nM. This approach requires for only 1 min determining protein concentration. As the best of our knowledge, this is the first time to determinate protein concentration by using single molecule detection techniques.  相似文献   

3.
This paper describes an integrated microfluidic chip that is capable of rapidly and quantitatively measuring the concentration of a bladder cancer biomarker, apolipoprotein A1, in urine samples. All of the microfluidic components, including the fluid transport system, the micro-valve, and the micro-mixer, were driven by negative pressure, which simplifies the use of the chip and facilitates commercialization. Magnetic beads were used as a solid support for the primary antibody, which captured apolipoprotein A1 in patients'' urine. Because of the three-dimensional structure of the magnetic beads, the concentration range of the target that could be detected was as high as 2000 ng ml−1. Because this concentration is 100 times higher than that quantifiable using a 96-well plate with the same enzyme-linked immunosorbent assay (ELISA) kit, the dilution of the patient''s urine can be avoided or greatly reduced. The limit of detection was determined to be approximately 10 ng ml−1, which is lower than the cutoff value for diagnosing bladder cancer (11.16 ng ml−1). When the values measured using the microfluidic chip were compared with those measured using conventional ELISA using a 96-well plate for five patients, the deviations were 0.9%, 6.8%, 9.4%, 1.8%, and 5.8%. The entire measurement time is 6-fold faster than that of conventional ELISA. This microfluidic device shows significant potential for point-of-care applications.  相似文献   

4.
Sodium-based dual-ion batteries (Na-DIBs) show a promising potential for large-scale energy storage applications due to the merits of environmental friendliness and low cost. However, Na-DIBs are generally subject to poor rate capability and cycling stability for the lack of suitable anodes to accommodate large Na+ ions. Herein, we propose a molecular grafting strategy to in situ synthesize tin pyrophosphate nanodots implanted in N-doped carbon matrix (SnP2O7@N-C), which exhibits a high fraction of active SnP2O7 up to 95.6 wt% and a low content of N-doped carbon (4.4 wt%) as the conductive framework. As a result, this anode delivers a high specific capacity ∼400 mAh g−1 at 0.1 A g−1, excellent rate capability up to 5.0 A g−1 and excellent cycling stability with a capacity retention of 92% after 1200 cycles under a current density of 1.5 A g−1. Further, pairing this anode with an environmentally friendly KS6 graphite cathode yields a SnP2O7@N-C||KS6 Na-DIB, exhibiting an excellent rate capability up to 30 C, good fast-charge/slow-discharge performance and long-term cycling life with a capacity retention of ∼96% after 1000 cycles at 20 C. This study provides a feasible strategy to develop high-performance anodes with high-fraction active materials for Na-based energy storage applications.  相似文献   

5.
Alternating current (AC) dielectrophoresis (DEP) experiments for biological particles in microdevices are typically done at a fixed frequency. Reconstructing the DEP response curve from static frequency experiments is laborious, but essential to ascertain differences in dielectric properties of biological particles. Our lab explored the concept of sweeping the frequency as a function of time to rapidly determine the DEP response curve from fewer experiments. For the purpose of determining an ideal sweep rate, homogeneous 6.08 μm polystyrene (PS) beads were used as a model system. Translatability of the sweep rate approach to ∼7 μm red blood cells (RBC) was then verified. An Au/Ti quadrapole electrode microfluidic device was used to separately subject particles and cells to 10Vpp AC electric fields at frequencies ranging from 0.010 to 2.0 MHz over sweep rates from 0.00080 to 0.17 MHz/s. PS beads exhibited negative DEP assembly over the frequencies explored due to Maxwell-Wagner interfacial polarizations. Results demonstrate that frequency sweep rates must be slower than particle polarization timescales to achieve reliable incremental polarizations; sweep rates near 0.00080 MHz/s yielded DEP behaviors very consistent with static frequency DEP responses for both PS beads and RBCs.  相似文献   

6.
This article describes a fabrication process for the generation of a leak proof paper based microfluidic device and a new design strategy for convenient incorporation of externally prepared test zones. Briefly, a negative photolithographic method was used to prepare the device with a partial photoresist layer on the rear of the device to block the leakage of sample. Microscopy and Field Emission Scanning Electron Microscopy data validated the formation of the photoresist layer. The partial layer of photoresist on the device channel limits sample volume to 7 ± 0.2 μl as compared to devices without the partial photoresist layer which requires a larger sample volume of 10 ± 0.1 μl. The design prototype with a customized external test zone exploits the channel protrusions on the UV exposed photoresist treated paper to bridge the externally applied test zone to the sample and absorbent zones. The partially laminated device with an external test zone has a comparatively low wicking speed of 1.8 ± 0.9 mm/min compared to the completely laminated device with an inbuilt test zone (3.3 ± 1.2 mm/min) which extends the reaction time between the analyte and reagents. The efficacy of the prepared device was studied with colorimetric assays for the non-specific detection of protein by tetrabromophenol blue, acid/base with phenolphthalein indicator, and specific detection of proteins using the HRP-DAB chemistry. The prepared device has the potential for leak proof detection of analyte, requires low sample volume, involves reduced cost of production (∼$0.03, excluding reagent and lamination cost), and enables the integration of customized test zones.  相似文献   

7.
The flow of λ-DNA solutions in a gradual micro-contraction was investigated using direct measurement techniques. The effects on DNA transport in microscale flows are significant because the flow behavior is influenced by macromolecular conformations, both viscous and elastic forces dominate inertial forces at this length scale, and the fully extended length of the molecule approaches the characteristic channel length wc (L/wc ∼ 0.13). This study examines the flow of semi-dilute and entangled DNA solutions in a gradual planar micro-contraction for low Reynolds numbers (3.7 × 10−6 < Re < 3.1 × 10−1) and high Weissenberg numbers (0.4 < Wi < 446). The semi-dilute DNA solutions have modest elasticity number, El = Wi/Re = 55, and do not exhibit viscoelastic behavior. For the entangled DNA solutions, we access high elasticity numbers (7.9 × 103 < El < 6.0 × 105). Video microscopy and streak images of entangled DNA solution flow reveal highly elastic behavior evidenced by the presence of large, stable vortices symmetric about the centerline and upstream of the channel entrance. Micro-particle image velocimetry measurements are used to obtain high resolution, quantitative velocity measurements of the vortex growth in this micro-contraction flow. These direct measurements provide a deeper understanding of the underlying physics of macromolecular transport in microfluidic flow, which will enable the realization of enhanced designs of lab-on-a-chip systems.  相似文献   

8.
Systemic lupus erythematosus (SLE) is an inflammatory autoimmune disease which is characterized by dysregulation of various cytokines propagating the inflammatory processes that is responsible for tissue damage. Tumor necrosis factor alpha (TNF-α) is one of the most important immunoregulatory cytokines that has been implicated in the different autoimmune diseases including SLE. Two hundred and two patients with SLE and 318 controls were included in the study. The TNF-α gene promoter region (from − 250 to − 1000 base pairs) was analyzed by direct Sanger’s DNA sequencing method to find promoter variants associated with South Indian SLE patients. We have analyzed six TNF-α genetic polymorphisms including, − 863C/A (rs1800630), − 857C/T (rs1799724), − 806C/T (rs4248158), − 646G/A (rs4248160), − 572A/C (rs4248161) and − 308G/A (rs1800629) in both SLE patients and controls. We did not find association of TNF-α gene promoter SNPs with SLE patients. However, the − 863A (rs1800630) allele showed association with lupus nephritis phenotype in patients with SLE (OR: 1.62, 95%CI 1.04–2.53, P = 0.034). We found serum TNF-α level was significantly elevated in SLE cases as compared to control and found no association with any of the polymorphisms. The haplotype analysis revealed a significant protective association between the wild TNF-α alleles at positions − 863C, − 857C, − 806C, − 646G, − 572A and − 308G (CCCGAG) haplotype with lupus nephritis phenotype (OR 0.53, 95% CI 0.35–0.82, P = 0.004). Additionally, the TNF-α − 863 C/A (rs1800630) polymorphism and HLA-DRB1*07 haplotype showed significant differences between SLE patients and controls (OR 4.79, 95% CI 1.73–13.29, P = 0.0009). In conclusion, TNF-α − 863A allele (rs1800630) polymorphism is associated with increased risk of nephritis in South Indian SLE patients. We also found an interaction between HLA-DRB1*07 allele with TNF-α − 863 C/A promoter polymorphism giving supportive evidence for the tight linkage disequilibrium between TNF-α promoter SNPs and MHC class II DRB1 alleles.  相似文献   

9.
A biochip system imitates the oviduct of mammals with a microfluidic channel to achieve fertilization in vitro of imprinting-control-region (ICR) mice. We apply a method to manipulate and to position the oocyte and the sperm of ICR mice at the same time in our microfluidic channel with a positive dielectrophoretic (DEP) force. The positive dielectrophoretic response of the oocyte and sperm was exhibited under applied bias conditions AC 10 Vpp waveform, 1 MHz, 10 min. With this method, the concentration of sperm in the vicinity of the oocyte was increased and enhanced the probability of natural fertilization. We used commercial numerical software (CFDRC-ACE+) to simulate the square of the electric field and analyzed the location at which the oocyte and sperm are trapped. The microfluidic devices were designed and fabricated with poly(dimethylsiloxane). The results of our experiments indicate that a positive DEP served to drive the position of the oocyte and the sperm to natural fertilization (average rate of fertilization 51.58%) in our microchannel structures at insemination concentration 1.5 × 106 sperm ml−1. Embryos were cultured to two cells after 24 h and four cells after 48 h.  相似文献   

10.
Large-scale low-cost synthesis methods for potassium ion battery (PIB) anodes with long cycle life and high capacity have remained challenging. Here, inspired by the structure of a biological cell, biomimetic carbon cells (BCCs) were synthesized and used as PIB anodes. The protruding carbon nanotubes across the BCC wall mimicked the ion-transporting channels present in the cell membrane, and enhanced the rate performance of PIBs. In addition, the robust carbon shell of the BCC could protect its overall structure, and the open space inside the BCC could accommodate the volume changes caused by K+ insertion, which greatly improved the stability of PIBs. For the first time, a stable solid electrolyte interphase layer is formed on the surface of amorphous carbon. Collectively, the unique structural characteristics of the BCCs resulted in PIBs that showed a high reversible capacity (302 mAh g−1 at 100 mA g−1 and 248 mAh g−1 at 500 mA g−1), excellent cycle stability (reversible capacity of 226 mAh g−1 after 2100 cycles and a continuous running time of more than 15 months at a current density of 100 mA g−1), and an excellent rate performance (160 mAh g−1 at 1 A g−1). This study represents a new strategy for boosting battery performance, and could pave the way for the next generation of battery-powered applications.  相似文献   

11.
Hormonal imbalance, inflammation and alteration in synaptic plasticity are reported to play a crucial role in the pathogenesis of schizophrenia. The objective of the study was to assess the serum levels of brain derived neurotrophic factor (BDNF) and its association with interleukin-23 (IL-23), testosterone and disease severity in schizophrenia. 40 cases and 40 controls were included in the study. Serum levels of BDNF, IL-23 and testosterone were estimated in all the subjects. Disease severity was assessed using Positive and Negative Syndrome Scale (PANSS). The study was designed in Tertiary care hospital, South India. The results were compared between two groups using Mann–Whitney U test. Spearman Correlation analysis was used to assess the association between biochemical parameters and PANSS. Interleukin-23 and testosterone were significantly increased and BDNF was significantly reduced in schizophrenia cases when compared with controls. BDNF was negatively correlated with IL-23 (r = − 400, p = 0.011), positive symptom subscale (r = − 0.393, p = 0.012), general psychopathology score subscale (r = − 407, p = 0.009) and total symptom subscale (r = − 404, p = 0.010). There was no significant association of IL-23 and testosterone with disease severity in schizophrenia cases. BDNF was reduced in schizophrenia cases and negatively associated with interleukin-23 and disease severity scores.  相似文献   

12.
For the first time, we report on the preliminary evaluation of gold coated optical fibers (GCOFs) as three-dimensional (3D) electrodes for a membraneless glucose/O2 enzymatic biofuel cell. Two off-the-shelf 125 μm diameter GCOFs were integrated into a 3D microfluidic chip fabricated via rapid prototyping. Using soluble enzymes and a 10 mM glucose solution flowing at an average velocity of 16 mm s−1 along 3 mm long GCOFs, the maximum power density reached 30.0 ± 0.1 μW cm−2 at a current density of 160.6 ± 0.3 μA cm−2. Bundles composed of multiple GCOFs could further enhance these first results while serving as substrates for enzyme immobilization.  相似文献   

13.
A transient 106-fold concentration of double-layer counterions by a high-intensity electric field is demonstrated at the exit pole of a millimeter-sized conducting nanoporous granule that permits ion permeation. The phenomenon is attributed to a unique counterion screening dynamics that transforms half of the surface field into a converging one toward the ejecting pole. The resulting surface conduction flux then funnels a large upstream electro-osmotic convective counterion flux into the injecting hemisphere toward the zero-dimensional gate of the ejecting hemisphere to produce the superconcentration. As the concentrated counterion is ejected into the electroneutral bulk electrolyte, it attracts co-ions and produce a corresponding concentration of the co-ions. This mechanism is also shown to trap and concentrate co-ion microcolloids of micron sizes too (macroions) and hence has potential application in bead-based molecular assays.  相似文献   

14.
Activated carbon fabrics (ACF) mask prevents the absorption of lead and reduce its adverse effects of human health. Aim of this study to know the blood lead level and its effects on heme biosynthesis and hematological parameters after using 2 months activated carbon fabric mask of battery manufacturing workers (BMW). Blood lead level, heme biosynthesis and hematological parameters were measured by using standard method. Blood lead level (P < 0.001, − 13.5%) was significantly decreased, activated δ-aminolevulinic acid dehydratase (P < 0.001, 11.97%) and non-activated δ- aminolevulinic acid dehydratase (P < 0.001, 23.17%) enzyme activity were significantly increased, however, the ratio of activated to Non-activated δ- ALAD (P < 0.001, − 10.13%) was significantly decreased, urinary excretion of δ- aminolevulinic acid (P < 0.001, − 10.49%) and porphobilinogen (P < 0.001, − 7.38%) were significantly decreased after using 2 months ACF mask as compared to before using mask of BMW. Hematological parameters i.e Hb (P < 0.05, 13.42%), PCV (P < 0.05, 7.23%), MCV (P < 0.05, 1.9%) were significantly increased and total WBC count (P < 0.05, − 5.18%) was significantly decreased after using 2 months ACF mask as compared to before using mask of BMW. Two months using ACF mask reduces the blood lead level and improves the δ-ALDH activity and hematological parameters, decreases the urinary excretion of δ-ALA, PBG of battery manufacturing workers. Therefore, the regular using of ACF mask is beneficial to prevent the lead absorption and its adverse effects on human health.  相似文献   

15.
Electric field-driven separation and purification techniques, such as isoelectric focusing (IEF) and isotachophoresis, generate heat in the system that can affect the performance of the separation process. In this study, a new mathematical model is presented for IEF that considers the temperature rise due to Joule heating. We used the model to study focusing phenomena and separation performance in a microchannel. A finite volume-based numerical technique is developed to study temperature-dependent IEF. Numerical simulation for narrow range IEF (6 < pH < 10) is performed in a straight microchannel for 100 ampholytes and two model proteins: staphylococcal nuclease and pancreatic ribonuclease. Separation results of the two proteins are obtained with and without considering the temperature rise due to Joule heating in the system for a nominal electric field of 100 V/cm. For the no Joule heating case, constant properties are used, while for the Joule heating case, temperature-dependent titration curves and thermo-physical properties are used. Our numerical results show that the temperature change due to Joule heating has a significant impact on the final focusing points of proteins, which can lower the separation performance considerably. In the absence of advection and any active cooling mechanism, the temperature increase is the highest at the mid-section of a microchannel. We also found that the maximum temperature in the system is a strong function of the ΔpK? value of the carrier ampholytes. Simulation results are also obtained for different values of applied electric fields in order to find the optimum working range considering the simulation time and buffer temperature. Moreover, the model is extended to study IEF in a straight microchip where pH is formed by supplying H+ and OH−, and the thermal analysis shows that the heat generation is negligible in ion supplied IEF.  相似文献   

16.
Alternating-current (AC) electrokinetics involve the movement and behaviors of particles or cells. Many applications, including dielectrophoretic manipulations, are dependent upon charge interactions between the cell or particle and the surrounding medium. Medium concentrations are traditionally treated as spatially uniform in both theoretical models and experiments. Human red blood cells (RBCs) are observed to crenate, or shrink due to changing osmotic pressure, over 10 min experiments in non-uniform AC electric fields. Cell crenation magnitude is examined as functions of frequency from 250 kHz to 1 MHz and potential from 10 Vpp to 17.5 Vpp over a 100 μm perpendicular electrode gap. Experimental results show higher peak to peak potential and lower frequency lead to greater cell volume crenation up to a maximum volume loss of 20%. A series of experiments are conducted to elucidate the physical mechanisms behind the red blood cell crenation. Non-uniform and uniform electrode systems as well as high and low ion concentration experiments are compared and illustrate that AC electroporation, system temperature, rapid temperature changes, medium pH, electrode reactions, and convection do not account for the crenation behaviors observed. AC electroosmotic was found to be negligible at these conditions and AC electrothermal fluid flows were found to reduce RBC crenation behaviors. These cell deformations were attributed to medium hypertonicity induced by ion concentration gradients in the spatially nonuniform AC electric fields.  相似文献   

17.
A rapid and simple technique is proposed for methanol concentration detection using a PMMA (Polymethyl-Methacrylate) microfluidic chip patterned using a commercially available CO2 laser scriber. In the proposed device, methanol and methanol oxidase (MOX) are injected into a three-dimensional circular chamber and are mixed via a vortex stirring effect. The mixture is heated to prompt the formation of formaldehyde and is flowed into a rectangular chamber, to which fuchsin-sulphurous acid is then added. Finally, the microchip is transferred to a UV spectrophotometer for methanol detection purposes. The experimental results show that a correlation coefficient of R2 = 0.9940 is obtained when plotting the optical density against the methanol concentration for samples and an accuracy as high as 93.1% are compared with the determined by the high quality gas chromatography with concentrations in the range of 2 ∼ 100 ppm. The methanol concentrations of four commercial red wines are successfully detected using the developed device. Overall, the results show that the proposed device provides a rapid and accurate means of detecting the methanol concentration for a variety of applications in the alcoholic beverage inspection and control field.  相似文献   

18.
A variety of methods have been used to introduce chemicals into a stream or to mix two or more streams of different compositions using microfluidic devices. In the following paper, the introduction of cryoprotective agents (CPAs) used during cryopreservation of cells in order to protect them from freezing injuries and increase viability post thaw is described. Dimethylsulphoxide (DMSO) is the most commonly used CPA. We aim to optimize the operating conditions of a two-stream microfluidic device to introduce a 10% vol/vol solution of DMSO into a cell suspension. Transport behavior of DMSO between two streams in the device has been experimentally characterized for a spectrum of flow conditions (0.7 < Re < 10), varying initial donor stream concentrations, (1% vol/vol < Co < 15% vol/vol) and different flow rate fractions (0.23 < fq < 0.77). The outlet cell stream concentration is analyzed for two different flow configurations: one with the cell stream flowing on top of the DMSO-rich donor stream, and the other with the cell stream flowing beneath the heavy DMSO-laden stream. We establish a transition from a diffusive mode of mass transfer to gravity-influenced convective currents for Atwood numbers (At) in the range of (1.7 × 10−3 < At < 3.1 × 10−3) for the latter configuration. Flow visualization with cells further our understanding of the effect of At on the nature of mass transport. Cell motion studies performed with Jurkat cells confirm a high cell recovery from the device while underscoring the need to collect both the streams at the outlet of the device and suggesting flow conditions that will help us achieve the target DMSO outlet concentration for clinical scale flow rates of the cell suspension.  相似文献   

19.
In healthcare practice, the sedimentation rate of red blood cells (erythrocytes) is a widely used clinical parameter for screening of several ailments such as stroke, infectious diseases, and malignancy. In a traditional pathological setting, the total time taken for evaluating this parameter varies typically from 1 to 2 h. Furthermore, the volume of human blood to be drawn for each test, following a gold standard laboratory technique (alternatively known as the Westergren method), varies from 4 to 5 ml. Circumventing the above constraints, here we propose a rapid (∼1 min) and highly energy efficient method for the simultaneous determination of hematocrit and erythrocyte sedimentation rate (ESR) on a microfluidic chip, deploying electrically driven spreading of a tiny drop of blood sample (∼8 μl). Our unique approach estimates these parameters by correlating the same with the time taken by the droplet to spread over a given radius, reproducing the results from more elaborate laboratory settings to a satisfactory extent. Our novel methodology is equally applicable for determining higher ranges of ESR such as high concentration of bilirubin and samples corresponding to patients with anemia and patients with some severe inflammation. Furthermore, the minimal fabrication steps involved in the process, along with the rapidity and inexpensiveness of the test, render the suitability of the strategy in extreme point-of-care settings.  相似文献   

20.
Affinity reagents recognizing biomarkers specifically are essential components of clinical diagnostics and target therapeutics. However, conventional methods for screening of these reagents often have drawbacks such as large reagent consumption, the labor-intensive or time-consuming procedures, and the involvement of bulky or expensive equipment. Alternatively, microfluidic platforms could potentially automate the screening process within a shorter period of time and reduce reagent and sample consumption dramatically. It has been demonstrated recently that a subpopulation of tumor cells known as cancer stem cells possess high drug resistance and proliferation potential and are regarded as the main cause of metastasis. Therefore, a peptide that recognizes cancer stem cells and differentiates them from other cancer cells will be extremely useful in early diagnosis and target therapy. This study utilized M13 phage display technology to identify peptides that bind, respectively, to colon cancer cells and colon cancer stem cells using an integrated microfluidic system. In addition to positive selection, a negative selection process was integrated on the chip to achieve the selection of peptides of high affinity and specificity. We successfully screened three peptides specific to colon cancer cells and colon cancer stem cells, namely, HOLC-1, HOLC-2, and COLC-1, respectively, and their specificity was measured by the capture rate between target, control, and other cell lines. The capture rates are 43.40 ± 7.23%, 45.16 ± 7.12%, and 49.79 ± 5.34% for colon cancer cells and colon cancer stem cells, respectively, showing a higher specificity on target cells than on control and other cell lines. The developed technique may be promising for early diagnosis of cancer cells and target therapeutics.  相似文献   

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