The primary focus of traditional topological optimization in continuum structures is addressing stress, compliance, and other relevant factors associated with single-phase materials. However, the ...optimal design of structural buckling performance has gained increasing attention due to its significant economic loss and safety risk. Furthermore, the versatility, lightweight nature, and adjustability of composite multiple-phase materials offer significant potential for application in various fields. Therefore, this paper presents a novel methodology for optimizing multi-phase materials’ design by concurrently incorporating structural buckling criteria and compliance design. Linear buckling analysis is utilized to determine the critical buckling load of the structure, and a buckling constraint is incorporated into the topology optimization model to regulate its buckling performance. A refined material interpolation model scheme is introduced to enhance the algorithm’s robustness and eliminate pseudo-eigenmode in buckling analysis. The numerical results demonstrate that the final topology optimization design exhibits distinct and discernible boundaries for the topological configurations of multiple-phase materials. Moreover, it is possible to effectively regulate the buckling property while minimizing any compromise on stiffness.
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EMUNI, FIS, FZAB, GEOZS, GIS, IJS, IMTLJ, KILJ, KISLJ, MFDPS, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, SBMB, SBNM, UKNU, UL, UM, UPUK, VKSCE, ZAGLJ
This study aims to explore the effect of cultural capital on academic motivation in the context of involution in China. The study will employ an ecological perspective to understand the interaction ...between college students and the involuted Chinese social context and job market, and the interaction mechanism between cultural capital and academic motivation. The concept of involution refers to the decreased “effort-to-reward ratio” in the education system, which has been impacted by the COVID-19 outbreak and the popularity of internet companies for college graduates. Cultural capital, as defined by Bourdieu, refers to a form of capital that can be converted into economic capital and is institutionalized in the form of educational credentials. The study will consider the three forms of cultural capital (objectified, embodied, and institutionalized) and their impact on academic motivation at the school, family, and individual levels. The results of this study will provide insight into the complex relationship between cultural capital and academic motivation in the involuted context in China and will have implications for understanding the phenomenon of study and employment involution.
Intraoral digital impressions have been stated to meet the clinical requirements for some teeth-supported restorations, though fewer evidences were proposed for larger scanning range. The aim of this ...study was to compare the accuracy (trueness and precision) of intraoral digital impressions for whole upper jaws, including the full dentitions and palatal soft tissues, as well as to determine the effect of different palatal vault height or arch width on accuracy of intraoral digital impressions. Thirty-two volunteers were divided into three groups according to the palatal vault height or arch width. Each volunteer received three scans with TRIOS intraoral scanner and one conventional impression of whole upper jaw. Three-dimensional (3D) images digitized from conventional gypsum casts by a laboratory scanner were chose as the reference models. All datasets were imported to a specific software program for 3D analysis by "best fit alignment" and "3D compare" process. Color-coded deviation maps showed qualitative visualization of the deviations. For the digital impressions for palatal soft tissues, trueness was (130.54±33.95)μm and precision was (55.26±11.21)μm. For the digital impressions for upper full dentitions, trueness was (80.01±17.78)μm and precision was (59.52±11.29)μm. Larger deviations were found between intraoral digital impressions and conventional impressions in the areas of palatal soft tissues than that in the areas of full dentitions (p<0.001). Precision of digital impressions for palatal soft tissues was slightly better than that for full dentitions (p = 0.049). There was no significant effect of palatal vault height on accuracy of digital impressions for palatal soft tissues (p>0.05), but arch width was found to have a significant effect on precision of intraoral digital impressions for full dentitions (p = 0.016). A linear correlation was found between arch width and precision of digital impressions for whole upper jaws (r = 0.326, p = 0.034 for palatal soft tissues and r = 0.485, p = 0.002 for full dentitions). It was feasible to use the intraoral scanner to obtain digital impressions for whole upper jaws. Wider dental arch contributed to lower precision of an intraoral digital impression. It should be confirmed in further studies that whether accuracy of digital impressions for whole upper jaws is clinically acceptable.
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DOBA, IZUM, KILJ, NUK, PILJ, PNG, SAZU, SIK, UILJ, UKNU, UL, UM, UPUK
A highly sensitive and selective fluorescent “on–off–on” strategy is established for the synchronous detection of Cu
2+
and glutathione in aqueous solution. Red carbon dots (R-CDs) were prepared by ...using precursors of 4,5-difluoro-1,2-phenylenediamine and citric acid via a one-step hydrothermal strategy. R-CDs show a relatively long fluorescence lifetime of 3.47 ns under 455 nm excitation and high absolute fluorescent quantum yield of 20.1% with an excitation wavelength of 550 nm. R-CDs exhibit a marked pH-responsive fluorescence property with no significant perturbation from pH 4 to pH 13 even after five cycles. R-CDs with higher concentration of 750 μg·mL
−1
exhibit no significant cytotoxicity and good biocompatibility on HeLa cells and A549 cells after incubation for 48 h. The fluorescence of R-CDs at 619 nm (excited at 550 nm) is quenched statically by Cu
2+
and recovered by glutathione subsequently, resulting in a fluorescent “on–off–on” assay for the synchronous detection of Cu
2+
and glutathione. Under optimal conditions, the linear response covers the Cu
2+
concentration range of 1 to 50 μM and the glutathione concentration range of 1 to 70 μM. Detection limits of Cu
2+
and glutathione are 0.16 and 0.41 μM, respectively. This fluorescent probe is applied to the determination of Cu
2+
and glutathione in authentic samples with satisfying results. Such an assay broadens the potential application of CDs in environmental areas and clinical therapy fields.
Graphical abstract
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DOBA, EMUNI, FIS, FZAB, GEOZS, GIS, IJS, IMTLJ, IZUM, KILJ, KISLJ, MFDPS, NLZOH, NUK, OILJ, PILJ, PNG, SAZU, SBCE, SBJE, SBMB, SBNM, UILJ, UKNU, UL, UM, UPUK, VKSCE, ZAGLJ
A mimicking-enzyme-based colorimetric aptasensor was developed for the detection of kanamycin (KANA) in milk using magnetic loop-DNA-NMOF-Pt (m-L-DNA) probes and catalytic hairpin assembly ...(CHA)-assisted target recycling for signal amplification. The m-L-DNA probes were constructed via hybridization of hairpin DNA H1 (containing aptamer sequence) immobilized magnetic beads (m-H1) and signal DNA (sDNA, partial hybridization with H1) labeled nano Fe-MIL-88NH2-Pt (NMOF-Pt-sDNA). In the presence of KANA and complementary hairpin DNA H2, the m-L-DNA probes decomposed and formed an m-H1/KANA intermediate, which triggered the CHA reaction to form a stable duplex strand (m-H1-H2) while releasing KANA again for recycling. Consequently, numerous NMOF-Pt-sDNA as mimicking enzymes can synergistically catalyze 3,3′,5,5′-tetramethylbenzidine (TMB) for color development. The aptasensor exhibited high selectivity and sensitivity for KANA in milk with a detection limit of 0.2 pg mL–1 within 30 min. The assay can be conveniently extended for on-site screening of other antibiotics in foods by simply changing the base sequence of the probes.
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IJS, KILJ, NUK, PNG, UL, UM, UPUK
•The effect of salt content on lipid derived volatile compounds was studied.•The activities of lipases, LOX and TBARS values increased during dry-curing.•Lipids derived volatile compounds increased ...during entire stages.•Volatile compounds content is related with lipid hydrolysis and oxidation.
The effect of dry-curing salt content (4% low salt (LS), 8% high salt (HS)) on lipolysis, lipid oxidation and volatile compounds in dry-cured goose was investigated in our study. The activities of acid lipase and neutral lipase increased during dry-curing, while phospholipase reached its maximum at the end of marinating. Lipoxygenase (LOX) and thiobarbituric acid reactive substances (TBARS) values increased during dry-curing and marinating then decreased during dry-ripening. Total free fatty acids (TFFA) increased at dry-curing and dry-ripening points and decreased during marinating. Total peak area of lipids derived volatile compounds (TPALDVC) and total peak area increased during entire stages. Compared to LS, HS group has higher lipolytic and LOX activities, TBARS, TFFA, unsaturated fatty acids and TPALDVC. The higher TPALDVC in HS could be attributed to higher lipid hydrolysis and oxidation during processing.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UL, UM, UPCLJ, UPUK, ZRSKP
A convenient and ultrasensitive ratiometric fluorescent probe was innovatively developed for Hg(II) detection and trypsin activity evaluation based on carbon dots (CDs) and tetraphenylporphyrin ...tetrasulfonic acid (TPPS) using bovine serum albumin (BSA) as the substrate of trypsin. The ratiometric fluorescence signal arises from CDs (
= 506 nm) and TPPS (
= 645 nm)
an inner filter effect. Hg
can trigger the formation of TPPS-Mn
metalloporphyrin for target Hg
recycling amplification, while both TPPS-Hg
and TPPS-Mn
metalloporphyrins do not affect the fluorescence of CDs. Small amino acids and peptide fragments, which are the products of BSA under the digestion of trypsin, bind stronger with Hg
than with TPPS. The decomposition of both TPPS-Hg
and TPPS-Mn
metalloporphyrins leads to a variation in the ratiometric fluorescence signal. Under optimized conditions, this probe provided an inspiring detection limit of 0.086 nM for Hg
and 0.013 ng mL
for trypsin, which possessed acceptable sensitivity for Hg
detection and trypsin activity evaluation in authentic samples. This unprecedented CD-based ratiometric fluorescence proposal for ultrasensitive quantification of Hg
concentration and selective assessment of trypsin activity gives a new insight for designing metal ion assays or enzymatic activity bioassays under different enzymatic substrates in the near future.
A facile, economic, and portable test kit based on target-responsive hydrogel with smartphone detection was fabricated for the accurate determination of dichlorvos in tap water and food samples. ...Carbon dots (CDs) and CdTe quantum dots (QDs) embedded hydrogel were employed as indicator, and fluorescence of CdTe QDs (645 nm) was dynamically quenched by Cu
2+
while that of CDs (490 nm) were non-response for Cu
2+
, em erging a typical ratiometric fluorescence signal. Acetylcholinesterase hydrolyzed acetylthiocholine to generate thiocholine that bound with Cu
2+
strongly via S-Cu-S bond. Dichlorvos as competitive inhibitor for acetylcholinesterase prevented the generation of thiocholine, which blocked the formation of Cu-thiocholine complex and changed the ratiometric fluorescence signal. The signal of the test kit, which was recorded by smartphone’s camera, was transduced by ImageJ software into the color parameter that was linearly proportional to the logarithm of dichlorvos concentration. This portable test kit showed wide linear range of 1 to 40 ppb and low detection limit of 0.38 ppb for dichlorvos. This test kit exhibited rapid sample-to-answer detection time (50 min) of dichlorvos in tap water and food samples, and the recoveries were in the range 81.3 to 111% with relative standard deviations of less than 9.1%.
Graphical abstract
A facile and economic portable test kit based on CD-CdTe QD target-responsive hydrogel with smartphone was innovatively fabricated for the accurate determination of organophosphorus pesticides. This portable test kit showed low detection limit of 0.38 ppb for dichlorvos and rapid sample-to-answer detection time (50 min) in tap water and food samples, which offered a new sight for portable monitoring of environmental pollution and food safety.
A one-pot hydrothermal synthesis of manganese-doped carbon dots (Mn-CDs) is reported for fluorescent “on-off-on” determination of Mn(VII) and L-ascorbic acid (L-AA) in aqueous solution and living ...cells. Mn-CDs were prepared by using sulfanilic acid, tetrakis(hydroxymethyl)phosphonium chloride, and Mn(II) chloride as precursors. Mn-CDs were characterized by several spectroscopic methods and microscopic techniques. Mn-CDs show distinctly long fluorescence lifetime (12.39 ± 0.07 ns) and high absolute fluorescence quantum yield (around 37%) with excitation and emission wavelengths of 362 and 500 nm, respectively. Mn-CDs exhibit no significant cytotoxicity to human cervical carcinoma HeLa cells and human embryonic kidney HEK-293T cells at 200 μg mL
−1
level after 48 h incubation. The fluorescence of Mn-CDs at 500 nm (excited at 362 nm) is quenched efficiently by Mn(VII) and can be further recovered after the addition of L-AA, resulting in a fluorescent “on-off-on” assay for the determination of Mn(VII) and L-AA. Under optimal experimental conditions, the linear response covers the 3 to 150 μM Mn(VII) concentration range and the 3 to 140 μM L-AA concentration range. This method offers relatively low detection limits of 0.66 μM for Mn(VII) and 0.90 μM for L-AA. This strategy was applied to visual determination of Mn(VII) and L-AA in living HeLa cells with satisfying results.
Graphical abstract
Schematic presentation of bright Mn-CD-based fluorescence “on-off-on” assay for both Mn(VII) and L-AA. This fluorescent assay possessed low detection limit of 0.66 μM for Mn(VII) and 0.90 μM for L-AA. This strategy was applied for visual determination of Mn(VII) and L-AA in living HeLa cells with satisfying results.
Let
X
be a Hopf manifold with non-Abelian fundamental group and
E
be a holomorphic vector bundle over
X
, with trivial pull-back to ℂ
n
− {0}. The authors show that there exists a line bundle
L
over
...X
such that
E
⊗
L
has a nowhere vanishing section. It is proved that in case dim(
X
) ≥ 3, π*(
E
) is trivial if and only if
E
is filtrable by vector bundles. With the structure theorem, the authors get the cohomology dimension of holomorphic bundle
E
over
X
with trivial pull-back and the vanishing of Chern class of
E
.
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DOBA, EMUNI, FIS, FZAB, GEOZS, GIS, IJS, IMTLJ, IZUM, KILJ, KISLJ, MFDPS, NLZOH, NUK, OBVAL, OILJ, PILJ, PNG, SAZU, SBCE, SBJE, SBMB, SBNM, UILJ, UKNU, UL, UM, UPUK, VKSCE, ZAGLJ
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