To investigate the nucleation behavior during the single-phased metallic solidification process,the commercial ultrapure ferritic stainless steels with no(Initial steel)and various melt treatments(R1,MR1,Y2,MY1,and M1...To investigate the nucleation behavior during the single-phased metallic solidification process,the commercial ultrapure ferritic stainless steels with no(Initial steel)and various melt treatments(R1,MR1,Y2,MY1,and M1 steels)were used to carry out the differential scanning colorimetry(DSC)and high-temperature confocal laser scanning microscope(HT-CLSM)experiments.Based on the results of DSC experiments,the equilibrium solidification process as well as the relationship among the critical undercooling degree(△T_(c)^(DSC)),latent heat of fusion/crystallization(△H_(f)/△H_(c)),equiaxed grain ratio(ER),and average grain size(△_(ave)^(ingot))was revealed.ER is increased with the decreasing△T_(c)^(DSC)and increasing△H_(f)/△H_(c);however,△_(ave)^(ingot)is decreased with them.Referring to the results of HT-CLSM experiments,the average sizes of micro-/macrostructures(d_(ave)/D_(ave)/)are decreased with the increasing cooling rate,as well as the difference between and apparent critical undercooling degree(△T_(c)^(CLSM))was revealed.The heterogeneous nucleation of the crystal nuclei occurs only if△T_(c)^(CLSM)>△T_(c)^(DSC).Combining with the interfacial wetting-lattice mismatch heterogeneous nucleation model,the dynamic mechanism of the metallic solidification was revealed.The as-cast grains of the melt-treated samples were obviously refined,owing to the much higher actual heterogeneous nucleation rates(I_(heter.,i))obtained through melt treatments,and the heterogeneous nucleation rates(I_(heter.,ij))for all samples are increased with the cooling rates,firmly confirming that the as-cast grains of each sample could be refined by the increasing cooling rates.展开更多
In the present study,roxithromycin solutions of different pH values were prepared with water,simulated gastric fluid(SGF)and simulated intestinal fluid(SIF).Stability of roxithromycin in theabove solutions were determ...In the present study,roxithromycin solutions of different pH values were prepared with water,simulated gastric fluid(SGF)and simulated intestinal fluid(SIF).Stability of roxithromycin in theabove solutions were determined separately by colorimetry,TLC and HPLC.All the three methods achievedan identical conclusion that this drug was stable in water and SIF.However,for the stability test ofroxithromycin in SGF,the results obtained by colorimetry were contrary to those by TLC and HPLC.According to the results by colorimetry,this drug was stable in SGF for as long as 168 hours.However,whentested by TLC and HPLC,decomposition of this drug was found within 2 h and 10 min separately.Accordingto the determination by HPLC,8.15%and 62.02%of roxithromycin were decomposed in 10 min and 2 h inSGF.which can be explained like this:the decomposition products reacted with H_SO,to form a solutionwith the same photo-absorptivity range as that of the original drug.Accordingly,colorimetry is not suitablefor the assay and stability test of roxithromycin in acidic solution like SGF.Similarly,we also have reason topredict that microbacterial assay is not suitable for roxithromycin in acidic solution if the decompositionproduct still has antibacterial activities.展开更多
Rapid and ultrasensitive detection of pathogen-associated biomarkers is vital for the early diagnosis and therapy of bacterial infections.Herein,we developed a close-packed and ordered Au@AgPt array coupled with a cas...Rapid and ultrasensitive detection of pathogen-associated biomarkers is vital for the early diagnosis and therapy of bacterial infections.Herein,we developed a close-packed and ordered Au@AgPt array coupled with a cascade triggering strategy for surface-enhanced Raman scattering(SERS)and colorimetric identification of the Staphylococcus aureus biomarker micrococcal nuclease(MNase)in serum samples.The trimetallic Au@AgPt nanozymes can catalyze the oxidation of 3,3’,5,5’-tetramethylbenzidine(TMB)molecules to SERS-enhanced oxidized TMB(oxTMB),accompanied by the color change from colorless to blue.In the presence of S.aureus,the secreted MNase preferentially cut the nucleobase AT-rich regions of DNA sequences on magnetic beads(MBs)to release alkaline phosphatase(ALP),which subsequently mediated the oxTMB reduction for inducing the colorimetric/SERS signal fade away.Using this“on-to-off”triggering strategy,the target S.aureus can be recorded in a wide linear range with a limit of detection of 38 CFU/mL in the colorimetric mode and 6 CFU/mL in the SERS mode.Meanwhile,the MNase-mediated strategy characterized by high specificity and sensitivity successfully discriminated between patients with sepsis(n=7)and healthy participants(n=3),as well as monitored the prognostic progression of the disease(n=2).Overall,benefiting from highly active and dense“hot spot”substrate,MNase-mediated cascade response strategy,and colorimetric/SERS dual-signal output,this methodology will offer a promising avenue for the early diagnosis of S.aureus infection.展开更多
Colorimetry often suffers from deficiency in quantitative determination,susceptibility to ambient illuminance,and low sensitivity and visual resolution to tiny color changes.To offset these deficiencies,we incorporate...Colorimetry often suffers from deficiency in quantitative determination,susceptibility to ambient illuminance,and low sensitivity and visual resolution to tiny color changes.To offset these deficiencies,we incorporate deep machine learning into colorimetry by introducing a convolutional neural network(CNN)with powerful parallel processing,self-organization,and self-learning capabilities.As a proof of concept,a plasmonic nanosensor is proposed for the colorimetric detection of glucose by coupling Benedict’s reagent with gold nanoparticles(AuNPs),which relies on the assemble of AuNPs into dendritic nanochains by Cu2O.The distinct difference of refractive index between Cu2O and Au and the localized surface plasmon resonance coupling effect among AuNPs leads to a broad spectral shift as well as abundant color changes,thereby providing sufficient data for selflearning enabled by machine learning.The CNN is then used to fully diversify the learning and training of the images from standard samples under different ambient conditions and to obtain a classifier that can not only recognize tiny color changes that are imperceptible to human eyes,but also exhibit high accuracy and excellent anti-environmental interference capability.This classifier is then compiled as an application(APP)and implanted into a smartphone with Android environment.306 clinical urine samples were detected using the proposed method and the results showed a satisfactory correlation(87.6%)with that of a standard blood glucose test method.More importantly,this method can be generalized to other applications in colorimetry,and more broadly,in other scientific domains that involve image analysis and quantification.展开更多
In this study,we developed an eff ective method to detect hypochlorite acid(HClO)by using methylene blue(MB)derivative(BPY1).BPY1 was selectively oxidized through HClO,and the solution color changed from colorless to ...In this study,we developed an eff ective method to detect hypochlorite acid(HClO)by using methylene blue(MB)derivative(BPY1).BPY1 was selectively oxidized through HClO,and the solution color changed from colorless to blue.In the presence of HClO,the ultraviolet–visible(UV–vis)spectra and concentration of HClO had a linear relationship with a detection limit of 0.5μM.Furthermore,a test paper for HClO monitoring was successfully prepared using the BPY1 probe,and the observed detection limit by the naked eye was estimated at 5μM.Additionally,using the BPY1 probe,HClO could also be detected through smartphone colorimetry,and the method showed a good recovery ranging from 98.7 to 104.0%for HClO detection in an actual water sample.Especially for developing countries,such a low-cost and highly sensitive detection method provides a simple and practical method for monitoring HClO in water.展开更多
Reliable and selective sensing of dopamine(DA)is essential for early diagnosis of mental diseases.Among the various potential methods,nanozyme-based sensing systems have demonstrated promising sensitivity and reliabil...Reliable and selective sensing of dopamine(DA)is essential for early diagnosis of mental diseases.Among the various potential methods,nanozyme-based sensing systems have demonstrated promising sensitivity and reliability.However,owing to the lack of substrate specificity,it is challenging to selectively detect DA using nanozymes.Herein,based on the reactivity of the DA oxidation intermediates,we report a cascade colorimetric sensing system for the selective detection of DA using only a single nanozyme.It was disclosed that the oxidation product of DA catalyzed by Co-N-doped carbon sheets(Co-N-C,a common oxidase-like nanozyme),dopamine quinone(DAQ),showed significant biocatalytic electron-donating activity in the reduction of O_(2)to generate O_(2)·-.Further using O_(2)·-to oxidize3,3,5,5-tetramethylbenzidine(TMB),a colorimetric sensing platform for DA was constructed with a linear detection range of 50 nmol/L to 50μmol/L and a low limit of detection of 4 nmol/L.Thanks to the reactivity of the oxidation product,without any biometric units(such as nucleic acids,enzymes,and antibodies/antigens),the reaction selectivity of DA against other interferences(e.g.,ascorbic acid,adrenaline,5-hydroxytryptamine,and glutathione)was enhanced up to 71-fold.Beyond complicated cascade systems requiring at least two nanozymes,sophisticated artificial recognition via multiple interactions was simplified by exploiting the oxidative properties of product intermediates;thus,only a single common oxidase-like nanozyme was needed.This work offers a new strategy to enhance the selectivity of nanozymes for bioanalytical applications.展开更多
This article reviews the current application status and research progress of colorimetric detection methods based on chemical colorimetry in the detection of explosives.It mainly introduced colorimetric sensors,colori...This article reviews the current application status and research progress of colorimetric detection methods based on chemical colorimetry in the detection of explosives.It mainly introduced colorimetric sensors,colorimetric sensor arrays,and chemical colorimetric sensors based on novel material substrates.The application prospect of chemical colorimetric method in the field of explosives detection was prospected.展开更多
To decrease number of samples for the implementation of color space transformation, a method for modeling the chromatic characterization of video cameras was proposed. An additional transformation was required to pred...To decrease number of samples for the implementation of color space transformation, a method for modeling the chromatic characterization of video cameras was proposed. An additional transformation was required to predict output RGB values for an input color. This additional transformation was based on spectral reflectance relationship. The transformed color coordinates were taken as inputs of a multilayer neural network. Based on network outputs, the RGB values to be predicted were calculated. Experimental results were given to illustrate the performance of the method. Even though much less number of training samples are used, this method can also perform well on this color space transformation.展开更多
Dried ground leaves of Psidium guajava L. (guava) were extracted by water and aqueous ethyl alcohol 50% (1:10) ratio, and the total phenolic content in the extracts was determined spectrophotometrically according to ...Dried ground leaves of Psidium guajava L. (guava) were extracted by water and aqueous ethyl alcohol 50% (1:10) ratio, and the total phenolic content in the extracts was determined spectrophotometrically according to Folin- Ciocalteu’s phenol method and calculated as gallic acid equivalent (GAE). Remarkably high total phenolic content 575.3 ±15.5 and 511.6±6.2 mg of GAE/g of dried weight material (for ethanol guava leaf extracts and water guava leaf extracts, respectively) were obtained. The antioxidant activity of lyophilized extracts was determined at ambient temperature by means of a 2,2-diphenyl-1-picrylhydryzyl (DPPH˙) colorimetry with detection scheme at 515 nm. The activity was evalu- ated by the decrease in absorbance as the result of DPPH˙ color change from purple to yellow. The higher the sample concentration used, the stronger was the free radical-scavenging effect. The results obtained showed that ascorbic acid was a substantially more powerful antioxidant than the extracts from guava leaf. On the other hand, the commercial guava leaf extracts and ethanol guava leaf extracts showed almost the same antioxidant power whereas water guava leaf extracts showed lower antioxidant activity. The parameter EC50 and the time needed to reach the steady state to EC50 concentration ( TEC50 ) affected the antiradical capacity of the sample. The antioxidant efficiency (AE) has been shown to be a more ade- quate parameter for selecting antioxidants than the widely used EC50. This study revealed that guava leaf extracts comprise effective potential source of natural antioxidants.展开更多
Aflatoxin B_(1)(AFB_(1))is one of the most toxic,mutagenic and carcinogenic mycotoxin,widely exists in contaminated food,grains and feedstuff products.In this study,a novel magnetic beads multicolor colorimetric immun...Aflatoxin B_(1)(AFB_(1))is one of the most toxic,mutagenic and carcinogenic mycotoxin,widely exists in contaminated food,grains and feedstuff products.In this study,a novel magnetic beads multicolor colorimetric immunoassay(MBMCIA)based on Au@Ag nanorods(Au@Ag NRs)is proposed to visual detect ultralow concentration of AFB_(1)with high-resolution by the naked-eye.To design the MBMCIA system,AFB_(1)-BSA conjugates were first coated on the surface of magnetic beads(MBs),then alkaline phosphatase(ALP)as a bridge between immunoassay a nd color reaction was used for catalytic hydrolysis of ascorbic acid-phosphate to generate reductive ascorbic acid.Finally,the yielded ascorbic acid could reduce silver ions to grow a silver coating on the surface of gold nanorods to generate Au@Ag NRs,which leads to the bule-shifted longitudinal absorption peak of Au NRs,accompanying with a series of perceptible color change.Under the optimal conditions,the proposed MBMCIA exhibited go od sensitivity and specificity for the detection of AFB_(1)with the detection limit as low as 5.7 pg/mL Meanwhile,the MBMCIA was also applied for the analysis of AFB_(1)in spiked wheat samples,the obtained recoveries range from 99.1%to 104.3%with relative standard deviation(RSD)less than 7.05%were acceptable.The proposed MBMCIA integrates separated,enriched,anti-interfe rence and signal read-out into one,which opens up a new avenue for an on-site visual food safety inspection or environmental monitoring.展开更多
The Morinda tinctoria (MT) plant leaves extract was prepared in aqueous and hydrochloric acid media and was used as corrosion inhibitor for mild steel in hydrochloric acid medium. MT is found to be an efficient inhibi...The Morinda tinctoria (MT) plant leaves extract was prepared in aqueous and hydrochloric acid media and was used as corrosion inhibitor for mild steel in hydrochloric acid medium. MT is found to be an efficient inhibitor at room temperature and the efficiency decreases with increase in temperature. Results from colorimetric studies predict the amount of iron present in the test solution and the percentage inhibition efficiency values calculated from this data fit well with the weight loss experiments. The AC impedance studies reveal that the mild steel surface is positively charged and the process of inhibition is through charge transfer. Polarisation studies indicate the mixed nature of the inhibitor. Thermodynamic parameters obtained predict that the process of inhibition is a spontaneous one.展开更多
With increasing attention to personalized healthcare,miniaturized and easily implementable devices are desired for point-of-care testing(POCT).Herein,hydrophilic patterns were designed on freestanding TiO_(2)nanotube ...With increasing attention to personalized healthcare,miniaturized and easily implementable devices are desired for point-of-care testing(POCT).Herein,hydrophilic patterns were designed on freestanding TiO_(2)nanotube arrays(Ti NTs)as nanoreactors for a naked-eye colorimetric assay.With a high aspect ratio,TiN Ts can provide a long observation length combined with a limited volume.Moreover,by combining the photocatalytic property of TiO_(2)and spatiotemporal controllability of light,hydrophilic nanoreactors were fabricated with minimal volume,and thus the indicator and analyte are limited in a confined void by the hydrophobic surroundings,thus allowing a higher sensitivity for sensing.We believe the proposed sensing platform could provide a promising strategy in developing POCT devices for routine health monitoring.展开更多
Graphitic carbon nitride(g-C3 N4),as a visible-light-active organic semiconductor,has attracted growing attentions in photocatalysis and photoluminescence-based biosensing.Here,we demonstrated the intrinsic photooxida...Graphitic carbon nitride(g-C3 N4),as a visible-light-active organic semiconductor,has attracted growing attentions in photocatalysis and photoluminescence-based biosensing.Here,we demonstrated the intrinsic photooxidase activity of g-C3 N4 and then surface molecular imprinting on g-C3 N4 nanozymes was achieved for improved biosensing.Upon blue LED irradiation,the g-C3 N4 exhibited superior enzymatic activity for oxidation of chromogenic substrate like 3,3’,5,5’-tetramethylbenzidine(TMB)without destructive H2 O2.The oxidation was mainly ascribed to ·O2^-that was generated during light irradiation.The surface molecular imprinting on g-C3 N4 can lead to an over 1000-fold alleviation in matrix-interference from serum samples,4-fold improved enzymatic activity as well as enhanced substrate specificity comparing with bare g-C3 N4 during colorimetric sensing.Also,the MIP-g-C3 N4 possesses a high affinity to TMB with a Km value of only 22 μmol/L,much lower than other comment nanozymes like AuNPs,Fe3 O4 NPs,etc.It was successfully applied for detection of cysteine in serum sample with satisfactory recoveries.展开更多
Colorimetric sensing strategies as a powerful point-of-care testing(POCT) tool have attracted significant interest in various chem/biosensing applications.Taking the excellent bare-eye-detectable signaling feature,nan...Colorimetric sensing strategies as a powerful point-of-care testing(POCT) tool have attracted significant interest in various chem/biosensing applications.Taking the excellent bare-eye-detectable signaling feature,nanozymes-based colorimetric sensors enable more potential applications and have been a new forefront in the colorimetric POCT analysis toward different target analytes.However,the low catalytic activity of nanozymes in most cases limits their practical application.Recent efforts demonstrate that the aggregation-induced nanozymes provide a general means to modulate nanozymes activity and enhance colorimetric sensing performances of some nanozymes-based colorimetric sensors.But there are few reports are explored to discuss and review such aggregation-induced nanozymes and their colorimetric sensing applications.To highlight the advances and progress in aggregation-induced nanozymes based colorimetric assays,we herein summary the fundamentals,classify and applications of this newlydeveloping field,focusing on the aggregation-induced activity enhancement of nanozymes(AIAEnanozymes) with a significant "signal-on" feature and aggregation-induced activity inhibition of nanozymes(AIAI-nanozymes) with a dramatical "signal-of" characteristics.Finally,we also propose the current challenges and the future prospects on both AIAE-nanozymes and AIAI-nanozymes.展开更多
AIM: To describe the frequency and biophysical response of sensitive skin in Mexican subjects, using the lactic acid test.METHODS: The lactic acid stinging test was applied to 250 healthy volunteers, both sexes, 18 ye...AIM: To describe the frequency and biophysical response of sensitive skin in Mexican subjects, using the lactic acid test.METHODS: The lactic acid stinging test was applied to 250 healthy volunteers, both sexes, 18 years of age or older, without any active dermatoses on the test site. Volunteers were university students, workers of public institutions, and general population from San Luis Potosi, Mexico. Participants were not excluded based on socioeconomic status. Demographic data were obtained through a questionnaire. Skin phototype was obtained through colorimetry. Subjects were randomized to receive 10% lactic acid on one nasolabial fold and placebo on the other side. The presence and intensity of adverse sensations, such as itching, burning, or stinging, was evaluated through a 10-point VisualAnalogue Scale(VAS) prior to treatment and at 3, 5, 8 and 10 min after the intervention. Subjects with a VAS of 2 or higher were considered positive for the test. A VAS lower than 2 was considered a normal response to skin manipulation. Simultaneously, biophysical changes and barrier function were assessed by colorimetry, transepidermal water loss(TEWL), and capacitance. To decrease measurement variations by skin manipulation, the nasolabial fold was segmented in four areas of 1 cm2 for each time measurement. Descriptive analyses were made using central tendency measures. Analyses of data were performed using two-tailed c2 test, Fisher's test, t-test, logistic regression, or Mann-Whitney U test for non-parametric values between groups. RESULTS: Of the included 246 subjects, 68% were women and the mean age was 32 years. The most frequent skin phototype was Ⅴ(ranges Ⅱ-Ⅴ). Thirty-six percent of the subjects identified themselves as having sensitive skin. Fifty-two percent of the subjects were positive to the lactic acid stinging test, with a mean VAS of 4.5 at 3 min. Subjects with the self-diagnosis of sensitive skin were more likely to be positive for the test(80% vs 36%, P < 0.001). Lighter skin phototypes(types Ⅱ and Ⅲ) showed a higher response to the test compared to darker skin tones(type Ⅴ; OR = 0.88, P < 0.001). There were no statistical differences in baseline biophysical measurements. At 3 min, TEWL was significantly higher in subjects positive to the test(27.5 vs 23.7, P < 0.05). At 5 min, TEWL and capacitance showed statistical differences(26.0 vs 22.4, P < 0.05, and 239 vs 179, P < 0.05, respectively). After 5 min, values tended to return to baseline levels in both groups.CONCLUSION: Sensitive skin is frequent in our population. Darker skin phototypes have a lower prevalence of this syndrome, probably due to inherent differences in skin barrier function.展开更多
The authors determined a connection between change of functional state of human with liver cirrhosis and color characteristics of blood plasma. Features of color characteristics of blood plasma of patients with liver ...The authors determined a connection between change of functional state of human with liver cirrhosis and color characteristics of blood plasma. Features of color characteristics of blood plasma of patients with liver cirrhosis as compared with those of healthy people were determined by colorimetric method, based on absorption electromagnetic radiation in visible area. The average chromaticity coordinates in the XYZ system for patients with liver cirrhosis are x = 0.352 ± 0.006, y = 0.356 ± 0.005 as compared with healthy people chromaticity coordinates x = 0.32 ± 0.001, y = 0.32 ± 0.002.展开更多
As one of the most common medical diagnosis methods, urinalysis is a highly demanded technique for screening tests or daily monitoring of various diseases. With the rapid development of POC(point-of-care) systems, a c...As one of the most common medical diagnosis methods, urinalysis is a highly demanded technique for screening tests or daily monitoring of various diseases. With the rapid development of POC(point-of-care) systems, a convenient house-using urinalysis device is widely needed. However, considering the difference of onboard systems and multiple test indicators in urinalysis, the design of such an intelligent device is still challenging. In this paper, a smartphone-based portable urinalysis system has been developed and applied for the colorimetric analysis of routine urine examination indices using an Android app. By integrating the test paper sensor in the portable device for urinalysis,our system significantly improves the instability of conventional dipstick-based manual colorimetry, and the smartphone application used for color discrimination enhances the accuracy of the visual assessment of sample strips. Using a simple operation approach that takes ~ 2 min per test, our system can be applied as rapid urinalysis for routine check-ups.展开更多
This work aims at studying the effect of hygrothermal and UV cyclic aging on the tensile properties and esthetic characteristics of non-woven composites.The composite materials were thermo-compressed from non-woven ma...This work aims at studying the effect of hygrothermal and UV cyclic aging on the tensile properties and esthetic characteristics of non-woven composites.The composite materials were thermo-compressed from non-woven mats made up of PP and flax or kenaf fibers.This works included evaluating the change in color appearance and analyzing the variations in tensile properties and damage mechanisms,depending on the aging time.The presence of the UV protection film on the composite surface showed its effectiveness against aging.From visual observations and measurement of colorimetric parameters,it has been proved effective in the reduction of the bleaching and yellowing of the composites.As regards the tensile tests,the UV protection film enabled to stabilize the Young’s modulus after 1-week aging for Kenaf/PP and after 3-weeks for Flax/PP.After 4-weeks aging,it halved the number of acoustic emission events related to interfacial decohesion and fiber slippage/pull out for Flax/PP and Kenaf/PP composites.展开更多
Enzymatic activities are important to be quantified in products as enzymatic cleaners, which are used in medical and surgical devices reprocessing. Enzymatic activities are critical for the proper chemical cleaning th...Enzymatic activities are important to be quantified in products as enzymatic cleaners, which are used in medical and surgical devices reprocessing. Enzymatic activities are critical for the proper chemical cleaning that intends to remove solid organic dirt from inaccessible sites. The most important enzyme for this purpose is the protease, which is able to dissolve the main dirt attached to medical and surgical instruments. In this context, this study contributes to the development of a new proteolytic activity quantification method and its validation. The methodology is based on colorimetry and uses a UV-Vis spectrophotometer to measure the substrate hydrolysis by the blue color intensity, employing Protazyme AK tablets as substrate.展开更多
Mobile-phones have been widely explored on colorimetric evaluations. However, their use with different built-in image systems and acquisition configuration, in an environment with non-controlled illumination, limits t...Mobile-phones have been widely explored on colorimetric evaluations. However, their use with different built-in image systems and acquisition configuration, in an environment with non-controlled illumination, limits the establishment of an accurate color analysis. To overcome this restriction, the determination of the absolute color of an object can be overlooked and a relative color value determined. In this work, we establish a new approach for spectroscopic evaluation based on cell-phone imaging, with no previous calibration, determining relative color values. The standalone relative color intensity method is evaluated under the use of four distinct mobile-phones and different illumination conditions. The capability to distinguish different color shades exploring the proposed self-referenced relative color intensity technique is appraised. Moreover, the potential use of the method is demonstrated by evaluating the chemical-adsorption process of Cysteamine molecules on gold nanoparticle surfaces. The proposed self-referenced technique can improve and expand the use of mobile-phones in spectroscopic applications.展开更多
基金supported by the National Natural Science Foundation of China(Grant Nos.52274339,52174321,52074186,and 52104337)Natural Science Foundation of Jiangsu Province(Grant No.BK20231317)China Baowu Low-Carbon Metallurgy Innovation Fund(Grant No.BWLCF202108).
文摘To investigate the nucleation behavior during the single-phased metallic solidification process,the commercial ultrapure ferritic stainless steels with no(Initial steel)and various melt treatments(R1,MR1,Y2,MY1,and M1 steels)were used to carry out the differential scanning colorimetry(DSC)and high-temperature confocal laser scanning microscope(HT-CLSM)experiments.Based on the results of DSC experiments,the equilibrium solidification process as well as the relationship among the critical undercooling degree(△T_(c)^(DSC)),latent heat of fusion/crystallization(△H_(f)/△H_(c)),equiaxed grain ratio(ER),and average grain size(△_(ave)^(ingot))was revealed.ER is increased with the decreasing△T_(c)^(DSC)and increasing△H_(f)/△H_(c);however,△_(ave)^(ingot)is decreased with them.Referring to the results of HT-CLSM experiments,the average sizes of micro-/macrostructures(d_(ave)/D_(ave)/)are decreased with the increasing cooling rate,as well as the difference between and apparent critical undercooling degree(△T_(c)^(CLSM))was revealed.The heterogeneous nucleation of the crystal nuclei occurs only if△T_(c)^(CLSM)>△T_(c)^(DSC).Combining with the interfacial wetting-lattice mismatch heterogeneous nucleation model,the dynamic mechanism of the metallic solidification was revealed.The as-cast grains of the melt-treated samples were obviously refined,owing to the much higher actual heterogeneous nucleation rates(I_(heter.,i))obtained through melt treatments,and the heterogeneous nucleation rates(I_(heter.,ij))for all samples are increased with the cooling rates,firmly confirming that the as-cast grains of each sample could be refined by the increasing cooling rates.
文摘In the present study,roxithromycin solutions of different pH values were prepared with water,simulated gastric fluid(SGF)and simulated intestinal fluid(SIF).Stability of roxithromycin in theabove solutions were determined separately by colorimetry,TLC and HPLC.All the three methods achievedan identical conclusion that this drug was stable in water and SIF.However,for the stability test ofroxithromycin in SGF,the results obtained by colorimetry were contrary to those by TLC and HPLC.According to the results by colorimetry,this drug was stable in SGF for as long as 168 hours.However,whentested by TLC and HPLC,decomposition of this drug was found within 2 h and 10 min separately.Accordingto the determination by HPLC,8.15%and 62.02%of roxithromycin were decomposed in 10 min and 2 h inSGF.which can be explained like this:the decomposition products reacted with H_SO,to form a solutionwith the same photo-absorptivity range as that of the original drug.Accordingly,colorimetry is not suitablefor the assay and stability test of roxithromycin in acidic solution like SGF.Similarly,we also have reason topredict that microbacterial assay is not suitable for roxithromycin in acidic solution if the decompositionproduct still has antibacterial activities.
基金supported by the National Natural Science Foundation of China(Grant Nos.:82373833,22177039,and 82304438)the National Key Research and Development Program of China(Grant No.:2021YFC2300400)Guangdong Basic and Applied Basic Research Foundation,China(Grant Nos.:2024A1515012204,2022A1515010300,and 2022A1515110618).
文摘Rapid and ultrasensitive detection of pathogen-associated biomarkers is vital for the early diagnosis and therapy of bacterial infections.Herein,we developed a close-packed and ordered Au@AgPt array coupled with a cascade triggering strategy for surface-enhanced Raman scattering(SERS)and colorimetric identification of the Staphylococcus aureus biomarker micrococcal nuclease(MNase)in serum samples.The trimetallic Au@AgPt nanozymes can catalyze the oxidation of 3,3’,5,5’-tetramethylbenzidine(TMB)molecules to SERS-enhanced oxidized TMB(oxTMB),accompanied by the color change from colorless to blue.In the presence of S.aureus,the secreted MNase preferentially cut the nucleobase AT-rich regions of DNA sequences on magnetic beads(MBs)to release alkaline phosphatase(ALP),which subsequently mediated the oxTMB reduction for inducing the colorimetric/SERS signal fade away.Using this“on-to-off”triggering strategy,the target S.aureus can be recorded in a wide linear range with a limit of detection of 38 CFU/mL in the colorimetric mode and 6 CFU/mL in the SERS mode.Meanwhile,the MNase-mediated strategy characterized by high specificity and sensitivity successfully discriminated between patients with sepsis(n=7)and healthy participants(n=3),as well as monitored the prognostic progression of the disease(n=2).Overall,benefiting from highly active and dense“hot spot”substrate,MNase-mediated cascade response strategy,and colorimetric/SERS dual-signal output,this methodology will offer a promising avenue for the early diagnosis of S.aureus infection.
基金the National Natural Science Foundation of China(No.21876206)the Shandong Key Fundamental Research Project(No.ZR202010280003)+1 种基金the Fundamental Research Funds for the Central Universities(No.18CX02037A)the Youth Innovation and Technology project of Universities in Shandong Province(No.2020KJC007).
文摘Colorimetry often suffers from deficiency in quantitative determination,susceptibility to ambient illuminance,and low sensitivity and visual resolution to tiny color changes.To offset these deficiencies,we incorporate deep machine learning into colorimetry by introducing a convolutional neural network(CNN)with powerful parallel processing,self-organization,and self-learning capabilities.As a proof of concept,a plasmonic nanosensor is proposed for the colorimetric detection of glucose by coupling Benedict’s reagent with gold nanoparticles(AuNPs),which relies on the assemble of AuNPs into dendritic nanochains by Cu2O.The distinct difference of refractive index between Cu2O and Au and the localized surface plasmon resonance coupling effect among AuNPs leads to a broad spectral shift as well as abundant color changes,thereby providing sufficient data for selflearning enabled by machine learning.The CNN is then used to fully diversify the learning and training of the images from standard samples under different ambient conditions and to obtain a classifier that can not only recognize tiny color changes that are imperceptible to human eyes,but also exhibit high accuracy and excellent anti-environmental interference capability.This classifier is then compiled as an application(APP)and implanted into a smartphone with Android environment.306 clinical urine samples were detected using the proposed method and the results showed a satisfactory correlation(87.6%)with that of a standard blood glucose test method.More importantly,this method can be generalized to other applications in colorimetry,and more broadly,in other scientific domains that involve image analysis and quantification.
基金the National Natural Science Foundation of China(Nos.U1404215,22074089,21804085,21675109)Innovation Scientists and Technicians Troop Construction Projects of Henan Province(No:41)Key Scientific Research Projects of Colleges and Universities in Henan Province(No:21A150043)for support。
文摘In this study,we developed an eff ective method to detect hypochlorite acid(HClO)by using methylene blue(MB)derivative(BPY1).BPY1 was selectively oxidized through HClO,and the solution color changed from colorless to blue.In the presence of HClO,the ultraviolet–visible(UV–vis)spectra and concentration of HClO had a linear relationship with a detection limit of 0.5μM.Furthermore,a test paper for HClO monitoring was successfully prepared using the BPY1 probe,and the observed detection limit by the naked eye was estimated at 5μM.Additionally,using the BPY1 probe,HClO could also be detected through smartphone colorimetry,and the method showed a good recovery ranging from 98.7 to 104.0%for HClO detection in an actual water sample.Especially for developing countries,such a low-cost and highly sensitive detection method provides a simple and practical method for monitoring HClO in water.
基金supported by the National Natural Science Foundation of China(Nos.22174014 and 22074015)。
文摘Reliable and selective sensing of dopamine(DA)is essential for early diagnosis of mental diseases.Among the various potential methods,nanozyme-based sensing systems have demonstrated promising sensitivity and reliability.However,owing to the lack of substrate specificity,it is challenging to selectively detect DA using nanozymes.Herein,based on the reactivity of the DA oxidation intermediates,we report a cascade colorimetric sensing system for the selective detection of DA using only a single nanozyme.It was disclosed that the oxidation product of DA catalyzed by Co-N-doped carbon sheets(Co-N-C,a common oxidase-like nanozyme),dopamine quinone(DAQ),showed significant biocatalytic electron-donating activity in the reduction of O_(2)to generate O_(2)·-.Further using O_(2)·-to oxidize3,3,5,5-tetramethylbenzidine(TMB),a colorimetric sensing platform for DA was constructed with a linear detection range of 50 nmol/L to 50μmol/L and a low limit of detection of 4 nmol/L.Thanks to the reactivity of the oxidation product,without any biometric units(such as nucleic acids,enzymes,and antibodies/antigens),the reaction selectivity of DA against other interferences(e.g.,ascorbic acid,adrenaline,5-hydroxytryptamine,and glutathione)was enhanced up to 71-fold.Beyond complicated cascade systems requiring at least two nanozymes,sophisticated artificial recognition via multiple interactions was simplified by exploiting the oxidative properties of product intermediates;thus,only a single common oxidase-like nanozyme was needed.This work offers a new strategy to enhance the selectivity of nanozymes for bioanalytical applications.
文摘This article reviews the current application status and research progress of colorimetric detection methods based on chemical colorimetry in the detection of explosives.It mainly introduced colorimetric sensors,colorimetric sensor arrays,and chemical colorimetric sensors based on novel material substrates.The application prospect of chemical colorimetric method in the field of explosives detection was prospected.
文摘To decrease number of samples for the implementation of color space transformation, a method for modeling the chromatic characterization of video cameras was proposed. An additional transformation was required to predict output RGB values for an input color. This additional transformation was based on spectral reflectance relationship. The transformed color coordinates were taken as inputs of a multilayer neural network. Based on network outputs, the RGB values to be predicted were calculated. Experimental results were given to illustrate the performance of the method. Even though much less number of training samples are used, this method can also perform well on this color space transformation.
文摘Dried ground leaves of Psidium guajava L. (guava) were extracted by water and aqueous ethyl alcohol 50% (1:10) ratio, and the total phenolic content in the extracts was determined spectrophotometrically according to Folin- Ciocalteu’s phenol method and calculated as gallic acid equivalent (GAE). Remarkably high total phenolic content 575.3 ±15.5 and 511.6±6.2 mg of GAE/g of dried weight material (for ethanol guava leaf extracts and water guava leaf extracts, respectively) were obtained. The antioxidant activity of lyophilized extracts was determined at ambient temperature by means of a 2,2-diphenyl-1-picrylhydryzyl (DPPH˙) colorimetry with detection scheme at 515 nm. The activity was evalu- ated by the decrease in absorbance as the result of DPPH˙ color change from purple to yellow. The higher the sample concentration used, the stronger was the free radical-scavenging effect. The results obtained showed that ascorbic acid was a substantially more powerful antioxidant than the extracts from guava leaf. On the other hand, the commercial guava leaf extracts and ethanol guava leaf extracts showed almost the same antioxidant power whereas water guava leaf extracts showed lower antioxidant activity. The parameter EC50 and the time needed to reach the steady state to EC50 concentration ( TEC50 ) affected the antiradical capacity of the sample. The antioxidant efficiency (AE) has been shown to be a more ade- quate parameter for selecting antioxidants than the widely used EC50. This study revealed that guava leaf extracts comprise effective potential source of natural antioxidants.
基金supported by the National Natural Science Foundation of China(Nos.21804022,21964003 and 81773894)the Natural Science Foundation of Jiangxi Province(No.20202BABL213019)+1 种基金the Science and Technology Project of the Education Department of Jiangxi Province of China(No.GJJ190775)the Special Graduate Student Innovation Fund of Jiangxi Province(No.CX190013)。
文摘Aflatoxin B_(1)(AFB_(1))is one of the most toxic,mutagenic and carcinogenic mycotoxin,widely exists in contaminated food,grains and feedstuff products.In this study,a novel magnetic beads multicolor colorimetric immunoassay(MBMCIA)based on Au@Ag nanorods(Au@Ag NRs)is proposed to visual detect ultralow concentration of AFB_(1)with high-resolution by the naked-eye.To design the MBMCIA system,AFB_(1)-BSA conjugates were first coated on the surface of magnetic beads(MBs),then alkaline phosphatase(ALP)as a bridge between immunoassay a nd color reaction was used for catalytic hydrolysis of ascorbic acid-phosphate to generate reductive ascorbic acid.Finally,the yielded ascorbic acid could reduce silver ions to grow a silver coating on the surface of gold nanorods to generate Au@Ag NRs,which leads to the bule-shifted longitudinal absorption peak of Au NRs,accompanying with a series of perceptible color change.Under the optimal conditions,the proposed MBMCIA exhibited go od sensitivity and specificity for the detection of AFB_(1)with the detection limit as low as 5.7 pg/mL Meanwhile,the MBMCIA was also applied for the analysis of AFB_(1)in spiked wheat samples,the obtained recoveries range from 99.1%to 104.3%with relative standard deviation(RSD)less than 7.05%were acceptable.The proposed MBMCIA integrates separated,enriched,anti-interfe rence and signal read-out into one,which opens up a new avenue for an on-site visual food safety inspection or environmental monitoring.
文摘The Morinda tinctoria (MT) plant leaves extract was prepared in aqueous and hydrochloric acid media and was used as corrosion inhibitor for mild steel in hydrochloric acid medium. MT is found to be an efficient inhibitor at room temperature and the efficiency decreases with increase in temperature. Results from colorimetric studies predict the amount of iron present in the test solution and the percentage inhibition efficiency values calculated from this data fit well with the weight loss experiments. The AC impedance studies reveal that the mild steel surface is positively charged and the process of inhibition is through charge transfer. Polarisation studies indicate the mixed nature of the inhibitor. Thermodynamic parameters obtained predict that the process of inhibition is a spontaneous one.
基金the financial support from the National Natural Science Foundation of China(Nos.21874013,22204016 and 22074013)the Fundamental Research Funds for the Central Universities(Nos.N2005027,N2105018,and N2205005)。
文摘With increasing attention to personalized healthcare,miniaturized and easily implementable devices are desired for point-of-care testing(POCT).Herein,hydrophilic patterns were designed on freestanding TiO_(2)nanotube arrays(Ti NTs)as nanoreactors for a naked-eye colorimetric assay.With a high aspect ratio,TiN Ts can provide a long observation length combined with a limited volume.Moreover,by combining the photocatalytic property of TiO_(2)and spatiotemporal controllability of light,hydrophilic nanoreactors were fabricated with minimal volume,and thus the indicator and analyte are limited in a confined void by the hydrophobic surroundings,thus allowing a higher sensitivity for sensing.We believe the proposed sensing platform could provide a promising strategy in developing POCT devices for routine health monitoring.
基金the financial support from the National Natural Science Foundation of China(No.21475013)the Sichuan Science and Technology Project(No.2018JY0466)
文摘Graphitic carbon nitride(g-C3 N4),as a visible-light-active organic semiconductor,has attracted growing attentions in photocatalysis and photoluminescence-based biosensing.Here,we demonstrated the intrinsic photooxidase activity of g-C3 N4 and then surface molecular imprinting on g-C3 N4 nanozymes was achieved for improved biosensing.Upon blue LED irradiation,the g-C3 N4 exhibited superior enzymatic activity for oxidation of chromogenic substrate like 3,3’,5,5’-tetramethylbenzidine(TMB)without destructive H2 O2.The oxidation was mainly ascribed to ·O2^-that was generated during light irradiation.The surface molecular imprinting on g-C3 N4 can lead to an over 1000-fold alleviation in matrix-interference from serum samples,4-fold improved enzymatic activity as well as enhanced substrate specificity comparing with bare g-C3 N4 during colorimetric sensing.Also,the MIP-g-C3 N4 possesses a high affinity to TMB with a Km value of only 22 μmol/L,much lower than other comment nanozymes like AuNPs,Fe3 O4 NPs,etc.It was successfully applied for detection of cysteine in serum sample with satisfactory recoveries.
基金the National Natural Science Foundation of China(Nos.21765013,21665023)Key Talent Project of Gansu Province,“Feitian Scholar”Program of Gansu Province,and the Research Projects of Universities in Gansu Province(No.2017A115)for financially supporting this research。
文摘Colorimetric sensing strategies as a powerful point-of-care testing(POCT) tool have attracted significant interest in various chem/biosensing applications.Taking the excellent bare-eye-detectable signaling feature,nanozymes-based colorimetric sensors enable more potential applications and have been a new forefront in the colorimetric POCT analysis toward different target analytes.However,the low catalytic activity of nanozymes in most cases limits their practical application.Recent efforts demonstrate that the aggregation-induced nanozymes provide a general means to modulate nanozymes activity and enhance colorimetric sensing performances of some nanozymes-based colorimetric sensors.But there are few reports are explored to discuss and review such aggregation-induced nanozymes and their colorimetric sensing applications.To highlight the advances and progress in aggregation-induced nanozymes based colorimetric assays,we herein summary the fundamentals,classify and applications of this newlydeveloping field,focusing on the aggregation-induced activity enhancement of nanozymes(AIAEnanozymes) with a significant "signal-on" feature and aggregation-induced activity inhibition of nanozymes(AIAI-nanozymes) with a dramatical "signal-of" characteristics.Finally,we also propose the current challenges and the future prospects on both AIAE-nanozymes and AIAI-nanozymes.
文摘AIM: To describe the frequency and biophysical response of sensitive skin in Mexican subjects, using the lactic acid test.METHODS: The lactic acid stinging test was applied to 250 healthy volunteers, both sexes, 18 years of age or older, without any active dermatoses on the test site. Volunteers were university students, workers of public institutions, and general population from San Luis Potosi, Mexico. Participants were not excluded based on socioeconomic status. Demographic data were obtained through a questionnaire. Skin phototype was obtained through colorimetry. Subjects were randomized to receive 10% lactic acid on one nasolabial fold and placebo on the other side. The presence and intensity of adverse sensations, such as itching, burning, or stinging, was evaluated through a 10-point VisualAnalogue Scale(VAS) prior to treatment and at 3, 5, 8 and 10 min after the intervention. Subjects with a VAS of 2 or higher were considered positive for the test. A VAS lower than 2 was considered a normal response to skin manipulation. Simultaneously, biophysical changes and barrier function were assessed by colorimetry, transepidermal water loss(TEWL), and capacitance. To decrease measurement variations by skin manipulation, the nasolabial fold was segmented in four areas of 1 cm2 for each time measurement. Descriptive analyses were made using central tendency measures. Analyses of data were performed using two-tailed c2 test, Fisher's test, t-test, logistic regression, or Mann-Whitney U test for non-parametric values between groups. RESULTS: Of the included 246 subjects, 68% were women and the mean age was 32 years. The most frequent skin phototype was Ⅴ(ranges Ⅱ-Ⅴ). Thirty-six percent of the subjects identified themselves as having sensitive skin. Fifty-two percent of the subjects were positive to the lactic acid stinging test, with a mean VAS of 4.5 at 3 min. Subjects with the self-diagnosis of sensitive skin were more likely to be positive for the test(80% vs 36%, P < 0.001). Lighter skin phototypes(types Ⅱ and Ⅲ) showed a higher response to the test compared to darker skin tones(type Ⅴ; OR = 0.88, P < 0.001). There were no statistical differences in baseline biophysical measurements. At 3 min, TEWL was significantly higher in subjects positive to the test(27.5 vs 23.7, P < 0.05). At 5 min, TEWL and capacitance showed statistical differences(26.0 vs 22.4, P < 0.05, and 239 vs 179, P < 0.05, respectively). After 5 min, values tended to return to baseline levels in both groups.CONCLUSION: Sensitive skin is frequent in our population. Darker skin phototypes have a lower prevalence of this syndrome, probably due to inherent differences in skin barrier function.
文摘The authors determined a connection between change of functional state of human with liver cirrhosis and color characteristics of blood plasma. Features of color characteristics of blood plasma of patients with liver cirrhosis as compared with those of healthy people were determined by colorimetric method, based on absorption electromagnetic radiation in visible area. The average chromaticity coordinates in the XYZ system for patients with liver cirrhosis are x = 0.352 ± 0.006, y = 0.356 ± 0.005 as compared with healthy people chromaticity coordinates x = 0.32 ± 0.001, y = 0.32 ± 0.002.
基金Projects(61922093,U1813211) supported by the National Natural Science Foundation of ChinaProjects(SGDX20201103093003017,JCYJ20200109114827177) supported by Shenzhen Key Basic Research Project,China。
文摘As one of the most common medical diagnosis methods, urinalysis is a highly demanded technique for screening tests or daily monitoring of various diseases. With the rapid development of POC(point-of-care) systems, a convenient house-using urinalysis device is widely needed. However, considering the difference of onboard systems and multiple test indicators in urinalysis, the design of such an intelligent device is still challenging. In this paper, a smartphone-based portable urinalysis system has been developed and applied for the colorimetric analysis of routine urine examination indices using an Android app. By integrating the test paper sensor in the portable device for urinalysis,our system significantly improves the instability of conventional dipstick-based manual colorimetry, and the smartphone application used for color discrimination enhances the accuracy of the visual assessment of sample strips. Using a simple operation approach that takes ~ 2 min per test, our system can be applied as rapid urinalysis for routine check-ups.
文摘This work aims at studying the effect of hygrothermal and UV cyclic aging on the tensile properties and esthetic characteristics of non-woven composites.The composite materials were thermo-compressed from non-woven mats made up of PP and flax or kenaf fibers.This works included evaluating the change in color appearance and analyzing the variations in tensile properties and damage mechanisms,depending on the aging time.The presence of the UV protection film on the composite surface showed its effectiveness against aging.From visual observations and measurement of colorimetric parameters,it has been proved effective in the reduction of the bleaching and yellowing of the composites.As regards the tensile tests,the UV protection film enabled to stabilize the Young’s modulus after 1-week aging for Kenaf/PP and after 3-weeks for Flax/PP.After 4-weeks aging,it halved the number of acoustic emission events related to interfacial decohesion and fiber slippage/pull out for Flax/PP and Kenaf/PP composites.
文摘Enzymatic activities are important to be quantified in products as enzymatic cleaners, which are used in medical and surgical devices reprocessing. Enzymatic activities are critical for the proper chemical cleaning that intends to remove solid organic dirt from inaccessible sites. The most important enzyme for this purpose is the protease, which is able to dissolve the main dirt attached to medical and surgical instruments. In this context, this study contributes to the development of a new proteolytic activity quantification method and its validation. The methodology is based on colorimetry and uses a UV-Vis spectrophotometer to measure the substrate hydrolysis by the blue color intensity, employing Protazyme AK tablets as substrate.
文摘Mobile-phones have been widely explored on colorimetric evaluations. However, their use with different built-in image systems and acquisition configuration, in an environment with non-controlled illumination, limits the establishment of an accurate color analysis. To overcome this restriction, the determination of the absolute color of an object can be overlooked and a relative color value determined. In this work, we establish a new approach for spectroscopic evaluation based on cell-phone imaging, with no previous calibration, determining relative color values. The standalone relative color intensity method is evaluated under the use of four distinct mobile-phones and different illumination conditions. The capability to distinguish different color shades exploring the proposed self-referenced relative color intensity technique is appraised. Moreover, the potential use of the method is demonstrated by evaluating the chemical-adsorption process of Cysteamine molecules on gold nanoparticle surfaces. The proposed self-referenced technique can improve and expand the use of mobile-phones in spectroscopic applications.
