Aggregative Luminescence from CsPbBr3 Perovskite Precursors.

Understanding the properties of the precursor can provide deeper insight into the crystallization and nucleation mechanisms of perovskites, which is vital for the solution-process device performance. In this work, we conducted a detailed investigation into the photophysics properties of all-inorganic perovskite (CsPbBr3) precursors in a broad concentration and various solvents. The precursor gradually transformed from the solution state into the colloidal state and exhibited aggregation-induced emission (AIE) character as the concentration increased. The aggregative luminescence from the precursors originates from the polybromide plumbous that is formed through the coordination of solvent molecules to the lead metal center. Two adducts with monodentate (PbBr2⋅solvent) and bidentate (PbB2⋅2solvent) ligands can be obtained based on the coordination capability, accompanied by a red and green emission with photoluminescence peak at 610 and 565 nm, respectively. Furthermore, the aggregative luminescence intensity and color could be regulated by changing the solvent and precursor ratio. Besides, we discussed the difference between the molecular aggregate in the organic system and the ionic aggregate in the inorganic system. The fluorescence that is sensitive to Pb²âº coordination reported here could be applied to screen perovskite additives and judge the precursor aging.

Boosting Luminescence Efficiency of Near-Infrared-II Aggregation-Induced Emission Luminogens via a Mash-Up Strategy of π-Extension and Deuteration for Dual-Model Image-Guided Surgery.

The simultaneous pursuit of accelerative radiative and restricted nonradiative decay is of tremendous significance to construct high-luminescence-efficiency fluorophores in the second near-infrared wavelength window (NIR-II), which is seriously hindered by the energy gap laws. Herein, a mash-up strategy of π-extension and deuteration is proposed to efficaciously ameliorate the knotty problem. By extending the π-conjugation of the aromatic fragment and introducing an isotope effect to the aggregation-induced emission luminogen (AIEgen), an improved oscillator strength (f), coupled with suppressed deformation and high-frequency oscillation in the excited state, are successively implemented. In this case, a faster rate of radiative decay (kr) and restricted nonradiative decay (knr) are simultaneously achieved. Moreover, the preeminent emissive property of AIEgen in the molecular state could be commendably inherited by the aggregates. The corresponding NIR-II emissive AIEgen-based nanoparticles display high brightness, large Stokes shift, and superior photostability simultaneously, which can be applied for image-guided cancer and sentinel lymph node (SLN) surgery. This work thus provides a rational roadmap to improve the luminescence efficiency of NIR-II fluorophores for biomedical applications.

Aqueous Circularly Polarized Luminescence Induced by Homopolypeptide Self-Assembly.

Remarkable advances have been achieved in solution self-assembly of polypeptides from the perspective of nanostructures, mechanisms, and applications. Despite the intrinsic chirality of polypeptides, the promising generation of aqueous circularly polarized luminescence (CPL) based on their self-assembly has been rarely reported due to the weak fluorescence of most polypeptides and the indeterminate self-assembly mechanism. Here, we propose a facile strategy for achieving aqueous CPL based on the self-assembly of simple homopolypeptides modified with a terminal group featuring both twisted intramolecular charge transfer and aggregation-induced emission properties. A morphology-dependent CPL can be observed under different self-assembly conditions by altering the solvents. A nanotoroid-dispersed aqueous solution with detectable CPL can be obtained by using tetrahydrofuran as a good solvent for the self-assembly, which is attributed to the involvement of the terminal group in the chiral environment formed by the homopolypeptide chains. However, such a chiral packing mode cannot be realized in nanorods self-assembled from dioxane, resulting in an inactive CPL phenomenon. Furthermore, CPL signals can be greatly amplified by co-assembly of homopolypeptides with the achiral small molecule derived from the terminal group. This work not only provides a pathway to construct aqueous CPL-active homopolypeptide nanomaterials but also reveals a potential mechanism in the self-assembly for chiral production, transfer, and amplification in polypeptide-based nanostructures.

Polymeric Bowl-Shaped Nanoparticles: Hollow Structures with a Large Opening on the Surface.

Polymeric bowl-shaped nanoparticles (BNPs) are anisotropic hollow structures with large openings on the surface, which have shown advantages such as high specific area and efficient encapsulation, delivery and release of large-sized cargoes on demand compared to solid nanoparticles or closed hollow structures. Several strategies have been developed to prepare BNPs based on either template or template-free methods. For instance, despite the widely used self-assembly strategy, alternative methods including emulsion polymerization, swelling and freeze-drying of polymeric spheres, and template-assisted approaches have also been developed. It is attractive but still challenging to fabricate BNPs due to their unique structural features. However, there is still no comprehensive summary of BNPs up to now, which significantly hinders the further development of this field. In this review, the recent progress of BNPs will be highlighted from the perspectives of design strategies, preparation methods, formation mechanisms, and emerging applications. Moreover, the future perspectives of BNPs will also be proposed.

A systematic review on the flavor of soy-based fermented foods: Core fermentation microbiome, multisensory flavor substances, key enzymes, and metabolic pathways.

The characteristic flavor of fermented foods has an important impact on the purchasing decisions of consumers, and its production mechanisms are a concern for scientists worldwide. The perception of food flavor is a complex process involving olfaction, taste, vision, and oral touch, with various senses contributing to specific properties of the flavor. Soy-based fermented products are popular because of their unique flavors, especially in Asian countries, where they occupy an important place in the dietary structure. Microorganisms, known as the souls of fermented foods, can influence the sensory properties of soy-based fermented foods through various metabolic pathways, and are closely related to the formation of multisensory properties. Therefore, this review systematically summarizes the core microbiome and its interactions that play an active role in representative soy-based fermented foods, such as fermented soymilk, soy sauce, soybean paste, sufu, and douchi. The mechanism of action of the core microbial community on multisensory flavor quality is revealed here. Revealing the fermentation core microbiome and related enzymes provides important guidance for the development of flavor-enhancement strategies and related genetically engineered bacteria.

Unlocking Novel Ultralow-Frequency Band Gap: Assembled Cellular Metabarrier for Broadband Wave Isolation.

Admittedly, the design requirements of compactness, low frequency, and broadband seem to constitute an impossible trinity, hindering the further development of elastic metamaterials (EMMs) in wave shielding engineering. To break through these constraints, we propose theoretical combinations of effective parameters for wave isolation based on the propagation properties of Lamb waves in the EMM layer. Accordingly, we design compact EMMs with a novel ultralow-frequency bandgap, and the role of auxeticity in the dissociation between the dipole mode and the toroidal dipole mode is clearly revealed. Finally, under the guidance of the improved gradient design, we integrate multiple bandgaps to assemble metamaterial barriers (MMBs) for broadband wave isolation. In particular, the original configuration is further optimized and its ultralow-frequency and broadband performance are proven by transmission tests. It is foreseeable that our work will provide a meaningful reference for the application of the new EMMs in disaster prevention and protection engineering.

Design, synthesis, and in vivo evaluation of GO-SWL-Ahx-K-SWL.

In order to acquire both expanded binding ability with the EphA2 receptor and superior drug delivery capacity, we designed and synthesized the modified GO-SWL-Ahx-K-SWL conjugate as a potential targeted therapeutic drug for non-small cell lung cancer (NSCLC). Various characterization methods have confirmed that the conjugate is consistent with the theoretical peptide. The cytotoxicity test results showed that the conjugate was slightly more toxic to A549 cells than in 3 T3 cells, and the toxicity increased in a concentration-dependent manner. Single photon emission computed tomography/computed tomography (SPECT/CT) fusion imaging was performed to evaluate the conjugate binding to EphA2 receptor in vivo. The images showed obvious radioactive concentration in tumor tissues and significantly higher ratios of the tumor and muscle in the 125I-GO-SWL-Ahx-K-SWL group (10.78) than in the 125I-SWL-Ahx-K-SWL group (5.21) at all three time points (P < 0.01).

A Recurrent Neural Network-Based Method for Dynamic Load Identification of Beam Structures.

The determination of structural dynamic characteristics can be challenging, especially for complex cases. This can be a major impediment for dynamic load identification in many engineering applications. Hence, avoiding the need to find numerous solutions for structural dynamic characteristics can significantly simplify dynamic load identification. To achieve this, we rely on machine learning. The recent developments in machine learning have fundamentally changed the way we approach problems in numerous fields. Machine learning models can be more easily established to solve inverse problems compared to standard approaches. Here, we propose a novel method for dynamic load identification, exploiting deep learning. The proposed algorithm is a time-domain solution for beam structures based on the recurrent neural network theory and the long short-term memory. A deep learning model, which contains one bidirectional long short-term memory layer, one long short-term memory layer and two full connection layers, is constructed to identify the typical dynamic loads of a simply supported beam. The dynamic inverse model based on the proposed algorithm is then used to identify a sinusoidal, an impulsive and a random excitation. The accuracy, the robustness and the adaptability of the model are analyzed. Moreover, the effects of different architectures and hyperparameters on the identification results are evaluated. We show that the model can identify multi-points excitations well. Ultimately, the impact of the number and the position of the measuring points is discussed, and it is confirmed that the identification errors are not sensitive to the layout of the measuring points. All the presented results indicate the advantages of the proposed method, which can be beneficial for many applications.

Synthesis and Preclinical Evaluation of [68Ga]SP94 for Micro-PET Imaging of GRP78 Expression in Hepatocellular Carcinoma.

Glucose-regulated protein 78 (GRP78) is overexpressed in a wide variety of solid tumors, serving as a well-characterized target for tumor imaging or therapy. In this work, we developed a GRP78-responsive radiotracer (DOTA-68Ga)-Gly-Gly-Gly-Ser-Phe-Ser-Ile-Ile-His-Thr-Pro-Ile-Leu-Pro-Leu-Gly-Gly-Cys ([68Ga]SP94) for hepatocellular carcinoma (HCC) micro-PET imaging. DOTA-SP94 was synthesized by solid phase synthesis and then radiolabeled with 68GaCl3 with >99% radiochemical purity. The expression levels of GRP78 in HepG2 cells were confirmed by Western blotting. In vitro and in vivo study of [68Ga]SP94 showed high stability and high uptake in GRP78-overexpressing HepG2 cells and tumor, fast clearance, and low nontarget uptake. Micro-PET images showed excellent tumor accumulation of [68Ga]SP94 in the HepG2-implanted nude mice tumor model. Additionally, the radiotracer uptake in HepG2 tumors can be blocked by unlabeled DOTA-SP94, suggesting that the tracer uptake by HCC was receptor-mediated. We envision that our radiotracer can be used for noninvasive imaging of HCC and is worthy of further clinical investigations.

Enhanced Phytoremediation of Bisphenol A in Polluted Lake Water by Seedlings of Ceratophyllum demersum and Myriophyllum spicatum from In Vitro Culture.

Bisphenol A (BPA) is a typical endocrine disruptor that causes problems in waters all around the world. In this study, the effects of submerged macrophytes (Ceratophyllum demersum and Myriophyllum spicatum) cultured in vitro on the removal of BPA at two initial concentrations (0.5 mg L-1 vs. 5.0 mg L-1) from Donghu lake water were investigated, using different biomass densities (2 g L-1 vs. 10 g L-1) under different nutrient conditions (1.85 mg L-1 and 0.039 mg L-1 vs. 8.04 mg L-1 and 0.175 mg L-1 of the total nitrogen and phosphorus concentration, respectively), together with the effect of indigenous microorganisms in the water. The results showed that indigenous microorganisms had limited capacity for BPA removal, especially at higher BPA initial concentration when its removal rate amounted to about 12% in 12 days. Addition with plant seedlings (5 cm in length) greatly enhanced the BPA removal, which reached 100% and over 50% at low and high BPA initial concentration in 3 days, respectively. Higher biomass density greatly favored the process, resulting in 100% of BPA removal at high BPA initial concentration in 3 days. However, increases in nutrient availability had little effect on the BPA removal by plants. BPA at 10.0 mg L-1 significantly inhibited the growth of M. spicatum. Therefore, C. demersum may be a candidate for phytoremediation due to greater efficiency for BPA removal and tolerance to BPA pollution. Overall, seedlings of submerged macrophytes from in vitro culture showed great potential for use in phytoremediation of BPA in natural waters, especially C. demersum.

Dual-Tracer Assessment of Dynamic Changes in Reoxygenation and Proliferation Decrease During Fractionated Radiotherapy in Murine Tumors.

Objective: The present work aimed to assess reoxygenation and tumor inhibition during fractionated radiotherapy (FRT) in murine tumors using 18F-fluoromisonidazole (18F-FMISO) and 18F-fluorothymidine (18F-FLT) based micro positron emission tomography/computed tomography (PET/CT). Materials and Methods: A nude mouse xenograft model was established with the head and neck squamous carcinoma cell (FaDu), followed by administration of FRT. Imaging was carried out with both 18F-FMISO and 18F-FLT PET/CT, prior to FRT (Pre-FRT, 0 Gy), during FRT (Inter-FRT, 21 Gy), and after FRT (Post-FRT, 40 Gy). The maximum standardized uptake (SUVmax) and tumor-to-normal muscle ratio (TNR) were determined in regions of interest (ROIs) in 18F-FMISO and 18F-FLT PET/CT images. Then, hypoxic (HV) and proliferative tumor (PTV) volumes obtained by PET/CT were analyzed. Immunohistochemistry was performed to analyze the changes of hypoxia-inducible factor- (HIF)-1α, carbonic anhydrase 9 (CAIX), Ki67 and proliferating cell nuclear antigen (PCNA). Associations of the levels of these biomarkers with PET/CT parameters were analyzed. Results: 18F-FMISO PET/CT demonstrated markedly elevated reduction rates of SUVmax (30.3 vs. 14.5%, p = 0.012), TNR (27.9 vs. 18.3%, p = 0.032) and HV (85.0 vs. 71.4%, p = 0.047) from Pre-FRT to Inter-FRT compared with values from Inter-FRT to Post-FRT. Meanwhile, PTV reduction rate in 18F-FLT PET/CT from Pre-FRT to Inter-FRT was significantly decreased compared with that from Inter-FRT to Post-FRT (21.2 vs. 82.7%, p = 0.012). Tumor HIF-1α, CAIX, Ki67, and PCNA amounts were continuously down-regulated during radiotherapy. TNR (FMISO) showed significant correlations with HIF-1α (r = 0.692, p = 0.015) and CAIX (r = 0.801, p = 0.006) amounts in xenografts, while associations of SUVmax (FMISO) with hypoxia markers were weak (r = 0.418, p = 0.041 and r = 0.389, p = 0.037, respectively). SUVmax (FLT) was significantly correlated with Ki67 (r = 0.792, p = 0.003) and PCNA (r = 0.837, p = 0.004). Conclusions: Tumor reoxygenation occurs early during radiotherapy, while inhibition of cell proliferation by tumoricidal effects mainly takes place gradually with the course of radiotherapy. 18F-FMISO and 18F-FLT PET/CT are sensitive and non-invasive tools for the monitoring of tumor reoxygenation and proliferation during radiotherapy.

18F-HX4/18F-FMISO-based micro PET for imaging of tumor hypoxia and radiotherapy-associated changes in mice.

OBJECTIVE: The aim of this study was to evaluate the application of 18F-flortanidazole (18F-HX4)/18F-fluoromisonidazole (18F-FMISO) - based micro positron emission tomography/computed tomography (PET/CT) for imaging of tumor hypoxia and radiotherapy-associated changes in mice. MATERIALS AND METHODS: Radiotracer-based cellular uptake was performed to explore the correlation between radiotracer uptake and hypoxia state in cells. Animal models were established using subcutaneous injection of the human breast cancer line (MDA-MB-231) in a nude mouse. The effect of radiotherapy on tumor xenograft was assessed by measuring the tumor volume and mouse survival time. Meanwhile, mice with xenograft were imaged with 18F-FMISO and18F-HX4 PET/CT before and after radiotherapy. Tumor-to-normal muscle ratio (T/N) of 18F-FMISO and18F-HX4 maximum uptake was calculated by selecting a region of interest. Changes in tumor biology were assessed with immunohistochemical staining; T/N (18F-FMISO) and T/N (18F-HX4) were analyzed in relation to tumor volume, survival time, and the expression of tumor biomarkers, including hypoxia-inducible factor (HIF)-1α, glucose transporter (Glut-1) and the proliferation antigen Ki67. RESULTS: Higher tracer uptake (both 18F-FMISO and 18F-HX4) was observed in hypoxic cells compared to oxygenated cell. The in vivo study suggested that both T/N (18F-FMISO) and T/N (18F-HX4) were positively correlated with tumor hypoxia volume (p = 0.014 and p = 0.009, respectively), but negatively associated with survival time (p = 0.012 and p = 0.007, respectively). HIF-1α, Glut-1 and Ki67 expression in tumors were downregulated after radiotherapy. T/N (18F-HX4) was correlated with the expression of hypoxia marker HIF-1α in xenografts (r = 0.768, p = 0.025); while T/N (18F-FMISO) was moderately correlated with the expressions of Ki67 (r = 0.412, p = 0.041). No significant correlation was detected between Glut-1 expression and T/N (18F-FMISO) or T/N (18F-HX4) (r = 0.511, p = 0.097 and r=0.562, p = 0.126, respectively). CONCLUSIONS: Both 18F-HX4 and 18F-FMISO PET/CT can be used as biomarkers for tumor hypoxia and radiotherapy-associated changes. The clinical utilization of these two PET tracers needs to be further validated.

Ring-Opening Polymerization of N-Carboxyanhydride-Induced Self-Assembly for Fabricating Biodegradable Polymer Vesicles.

Polymerization-induced self-assembly (PISA) is regarded as one of the most important strategies in macromolecular nanotechnology, as it can create a wide range of nanoparticles at high concentrations and on a large scale. However, open-to-air PISA with biodegradable product is still a complicated challenge, as traditional PISA is usually carried out under oxygen-free conditions to afford nonbiodegradable polymers. To meet the above challenges, we propose a convenient one-pot open-to-air ring-opening polymerization (ROP) of N-carboxyanhydride (NCA)-induced self-assembly (NCA-PISA) at 10 °C, without the need for degassing, heating, catalysts, or chain transfer agents. The morphologies of nanoparticles depend on the ratio of the initiator to the monomer and the solid content. Polymer vesicles can be fabricated when the ratio and the solid content are 1:20 and 20%, respectively. Overall, this versatile one-pot NCA-PISA provides an insight into facilely fabricating biodegradable nanoparticles in air.

Polymer Vesicles: Modular Platforms for Cancer Theranostics.

As an emerging field that is receiving an increasing amount of interest, theranostics is becoming increasingly important in the field of nanomedicine. Among the various smart platforms that have been proposed for use in theranostics, polymer vesicles (or polymersomes) are among the most promising candidates for integration of designated functionalities and modalities. Here, a brief summary of typical theranostic platforms is presented with a focus on modular polymer vesicles. To highlight modularity, the different methodologies for designing therapeutic and diagnostic modules are classified and current examples of theranostic vesicles that excel in both performance and design principle are provided. Finally, future prospects for theranostic polymer vesicles that can be readily prepared with functional modules are proposed. Overall, theranostic polymer vesicles with modular modalities and functions are more promising in nanomedicine than simply being "over-engineered".

Efficient Removal of Polycyclic Aromatic Hydrocarbons, Dyes, and Heavy Metal Ions by a Homopolymer Vesicle.

It is an important challenge to effectively remove environmental pollutants such as polycyclic aromatic hydrocarbons (PAHs), dyes, and heavy metal ions at a low cost. Herein, we present a multifunctional homopolymer vesicle self-assembled from a scalable homopolymer, poly(amic acid) (PAA), at room temperature. The vesicle can efficiently eliminate PAHs, cationic dyes, and heavy metal ions from water based on π-π stacking, hydrophobic effect, and electrostatic interactions with the pollutants. The residual concentrations of PAHs, cationic dyes, and heavy metal ions (such as Ni2+) in water are lower than 0.60 and 0.30 parts per billion (ppb) and 0.095 parts per million (ppm), respectively, representing a promising adsorbent for water remediation. Furthermore, precious metal ions such as Ag+ can be recovered into silver nanoparticles by in situ reduction on the membrane of PAA vesicles to form a silver nanoparticle/vesicle composite (Ag@vesicle) that can effectively catalyze the reduction of toxic pollutants such as aromatic nitro-compounds and be recycled for more than ten times.

Intracellular Proteolytic Disassembly of Self-Quenched Near-Infrared Nanoparticles Turning Fluorescence on for Tumor-Targeted Imaging.

The design of tumor-targeting, intracellular protease-activatable near-infrared fluorescence (NIRF) nanoprobes is broadly interesting but remains challenging. In this work, we report the rational design of a NIR probe Cys(StBu)-Lys(Biotin)-Lys-Lys(Cy5.5)-CBT (1) to facilely prepare the self-quenched nanoparticles 1-NPs for tumor-targeted imaging in vitro and in vivo. The biotinylated 1-NPs could be actively uptaken by biotin receptor-overexpressing tumor cells via receptor-mediated endocytosis. Upon intracellular proteolytic cleavage, 1-NPs were disassembled to yield the small molecular probe Lys(Cy5.5)-Luciferin-Lys(Biotin)-Lys-OH (1-D-cleaved), accompanied by fluorescence "Turn-On". With this NIRF "Turn-On" property, 1-NPs were successfully applied for tumor-targeted imaging. We envision that our nanoparticles could be applied for fluorescence-guided tumor surgery in the near future.

Bisphenol A Removal by Submerged Macrophytes and the Contribution of Epiphytic Microorganisms to the Removal Process.

Bisphenol A (BPA), a typical endocrine disruptor, has been found in global aquatic environments, causing great concern. The capabilities of five common submerged macrophytes to remove BPA from water and the contributions of epiphytic microorganisms were investigated. Macrophytes removed 62%-100% of total BPA (5 mg/L) over 12 days; much higher rates than that observed in the control (2%, F = 261.511, p = 0.000). Ceratophyllum demersum was the most efficient species. C. demersum samples from lakes with different water qualities showed no significant differences in BPA removal rates. Moreover, removal, inhibition or re-colonization of epiphytic microorganisms did not significantly change the BPA removal rates of C. demersum. Therefore, the contributions of epiphytic microorganisms to the BPA removal process were negligible. The rate of BPA accumulation in C. demersum was 0.1%, indicating that BPA was mainly biodegraded by the macrophyte. Hence, submerged macrophytes, rather than epiphytic microorganisms, substantially contribute to the biodegradation of BPA in water.

Efficiency and mechanism of the phytoremediation of decabromodiphenyl ether-contaminated sediments by aquatic macrophyte Scirpus validus.

Phytoremediation is an economic and promising technique for removing toxic pollutants from the environment. Freshwater sediments are regarded as the ultimate sink of the widely used PBDE congener decabromodiphenyl ether (BDE-209) in the environment. In the study, the aquatic macrophyte Scirpus validus was selected to remove BDE-209 from three types of sediments (silt, clay, and sand) at an environmentally relevant concentration. After 18 months of phytoremediation experiment, S. validus significantly enhanced the dissipation rates of BDE-209 in all the sediments compared to the controls. Average removal rates of BDE-209 in the three treatments of silt, clay, and sandy sediments with S. validus were respectively 92.84, 84.04, and 72.22%, which were 148, 197, and 233% higher than that in the control sediments without S. validus. In the phytoremediation process, the macrophyte-rhizosphere microbe combined degradation was the main pathway of BDE-209 removal. Sixteen lower brominated PBDE congeners (di- to nona-) were detected in the sediments and plant tissues, confirming metabolic debromination of BDE-209 in S. validus. A relatively higher proportion of penta- and di-BDE congeners among the metabolites in plant tissues than that in the sediments indicated further debromination of PBDEs within plants. The populations and activities of microorganisms in the sediments were greatly promoted by S. validus. Bacterial community structure in BDE-209-contaminated rhizosphere sediments was different from that in the control rhizosphere sediment, as indicated by the dominant proportions of ß-proteobacteria, δ-proteobacteria, α-proteobacteria, Acidobacteria, and Chloroflexi in the microbial flora. All these results suggested that S. validus was effective in phytoremediation of BDE-209 by the macrophyte-rhizosphere microbe combined degradation in aquatic sediments.

Experimental study of thermal comfort on stab resistant body armor.

PURPOSE: This research aims to investigate the impacts of exercise intensity and sequence on human physiology parameters and subjective thermal sensation when wearing stab resistant body armor under daily working conditions in China [26 and 31 °C, 45-50 % relative humidity (RH)], and to investigate on the relationship between subjective judgments and objective parameters. METHODS: Eight male volunteers were recruited to complete 3 terms of exercises with different velocity set on treadmill for 90 min at 26 °C and 31 °C, 45-50 % RH. In Exercise 1 volunteers were seated during the test. In Exercise 2, volunteers walked with the velocity of 3 km/h in the first 45 min and 6 km/h in the left 45 min. In Exercise 3, volunteers walked with the velocity of 6 km/h in the first 45 min and 3 km/h in the left 45 min. The body core temperature, skin temperature and subjective judgments were recorded during the whole process. Analysis of variance was performed among all the tests. RESULTS: Individual discrepancy of Exercise 1 is larger than that of Exercise 2 and 3. On the premise of the same walking distance and environmental conditions, core temperature in Exercise 3 is about 0.2 °C lower than that in Exercise 2 in the end; and with the velocity decrease from 6 km/h to 3 km/h in the end, thermal tolerance of Exercise 3 is about 1 degree lower than that in Exercise 2. Skin temperatures of human trunk were at least 1 °C higher than that of limbs. CONCLUSIONS: Activity narrows the individual discrepancy on core temperature. Within experimental conditions, decreasing of intensity at last stage makes the core temperature lower and the whole process much tolerable. The core temperature is more sensitive to the external disturbance on the balance of the whole body, and it can reflect the subjective thermal sensation and physical exertion.

Development of a rapid method for the quantification of cellulose in tobacco by (13)C CP/MAS NMR.

A method was developed for rapid quantitative determination of cellulose in tobacco by utilizing (13)C cross polarization magic angle spinning NMR spectroscopy ((13)C CP/MAS NMR). Sample powder was loaded into NMR rotor, which was customized rotor containing a matched silicon tube as an intensity reference. (13)C CP/MAS NMR spectra of tobacco samples were processed with spectral deconvolution to obtain the area of the C-1 resonance at 105.5ppm and the internal standard at 0ppm. The ratio between the area of 105.5ppm and 0ppm of a set of standard cellulose samples was used to construct a calibration curve. The cellulose content of a tobacco sample was determined by comparison of the ratio between the area of 105.5ppm and 0ppm to the calibration curve. Results of this developed method showed good agreement with those obtained from chemical analysis. The proposed method has such advantages of accuracy, quickness and efficiency, and could be an alternative to chemical analyses of cellulose.