A quantitative study of the structure–activity relationship in hierarchical zeolites using liquid‐phase reactions

Xu, Dandan,Abdelrahman, Omar,Ahn, Sang Hyun,Guefrachi, Yasmine,Kuznetsov, Anatoliy,Ren, Limin,Hwang, Sonjong,Khaleel, Maryam,Al Hassan, Saeed,Liu, Dongxia,Hong, Suk Bong,Dauenhauer, Paul,Tsapatsis, Mi John Wiley Sons, Inc. 2019 AIChE journal Vol.65 No.3

<P>Micro/meso/macroporous (hierarchical) zeolites show remarkable catalytic performance for reactions involving bulky reactants. However, quantitative assessment of the microstructural characteristics contributing to the observed performance remains elusive. Here, structure–activity relationships are established for a set of micro/mesoporous self‐pillared pentasil (SPP) zeolites using two parallel liquid‐phase reactions (benzyl alcohol alkylation and self‐etherification) based on analysis of mass transport and reaction kinetics. A reaction–diffusion mathematical model is developed that quantitatively assigns the catalytic contributions of the external surface and micropores of SPP zeolites for these reactions. In addition, the effect of the zeolite external surface structure on the corresponding catalytic activity is quantitatively assessed by comparing SPP zeolites (with MFI structure) with MCM‐22 (with MWW structure). This work demonstrates that reaction–diffusion modeling allows quantitative description of the catalytic performance of hierarchical zeolites and provides a model reaction to assess nm‐sized characteristic diffusion lengths in MFI. © 2018 American Institute of Chemical Engineers <I>AIChE J</I>, 65: 1067–1075, 2019</P>

The Impacts of Childhood Trauma on Psychosocial Features in a Chinese Sample of Young Adults

Dandan Wang,Shaojia Lu,Weijia Gao,Zhaoguo Wei,Jinfeng Duan,Shaohua Hu,Manli Huang,Yi Xu,Lingjiang Li 대한신경정신의학회 2018 PSYCHIATRY INVESTIGATION Vol.15 No.11

Objective The aims of the present study were to explore the occurrence of childhood trauma and importantly to determine the impacts of childhood trauma on psychosocial features in a Chinese sample of young adults. Methods A survey was carried out in a group of 555 university students by using Childhood Trauma Questionnaire (CTQ), Self-rating Depression Scale (SDS), Self-rating Anxiety Scale (SAS), Dysfunctional Attitudes Questionnaire (DAS), Eysenck Personality Questionnaire (EPQ), and Social Support Rating Scale (SSRS). The moderate-severe cut-off scores for CTQ were used to calculate the prevalence of childhood trauma, and then psychosocial features were compared between individuals with and without childhood trauma. Results A proportion of 18.6% of university students had self-reported childhood trauma exposures. Subjects with childhood trauma reported higher scores of SDS, SAS, DAS, and psychoticism and neuroticism dimensions of EPQ (t=4.311–5.551, p<0.001); while lower scores of SSRS and extraversion dimension of EPQ (t=-4.061– -3.039, p<0.01). Regression analyses further revealed that scores of SAS and DAS were positively (Adjusted B=0.211–0.230, p<0.05), while scores of SSRS were negatively (Adjusted B=-0.273– -0.240, p<0.05) associated with specific CTQ scores. Conclusion Childhood trauma is still a common social and psychological problem. Individuals with childhood trauma show much more depression, anxiety, distorted cognition, personality deficits, and lower levels of social support, which may represent the social and psychological vulnerability for developing psychiatric disorders after childhood trauma experiences.

Granularity and Laxative Effect of Ultrafine Powder of Dendrobium officinale

DanDan Luo,Chao Qu,ZhenBiao Zhang,JianHui Xie,LieQiang Xu,HongMei Yang,CaiLan Li,GuoSheng Lin,HongFeng Wang,ZiRen Su 한국식품영양과학회 2017 Journal of medicinal food Vol.20 No.2

Constipation is a common disorder that is a significant source of morbidity among people around the world ranging from 2% to 28%. Dendrobium officinale Kimura et Migo is a traditional herbal medicine and health food used for tonicity of the stomach and promotion of body fluid production in China. This study aimed to prepare the ultrafine powder of Dendrobium officinale (UDO) and investigate its laxative effect and potential mechanism in mice with diphenoxylate-induced constipation. Results indicated that the mean diameter (d50) of UDO obtained by ball milling was 6.56 lm. UDO (62.5, 125, and 250 mg/kg, p.o.) could significantly enhance the gastrointestinal transit ratio and promote fecal output. Moreover, UDO treatment resulted in significant increases in the serum levels of acetylcholinesterase (AChE), gastrin (Gas), motilin (MTL), and substance P (SP), and obviously decreased serum contents of somatostatin (SS). Taken together, UDO, which can be easily obtained through milling to a satisfactory particle size, exhibited obvious laxative effect in diphenoxylate-induced constipated mice, and the mechanism might be associated with elevated levels of AChE, Gas, MTL, SP, and reduced production of SS. UDO has the potential for further development into an alternative effective diet therapy for constipation.

An Outbreak of Histomoniasis in Backyard Sanhuang Chickens

Dandan Liu,Lingming Kong,Jianping Tao,Jinjun Xu 대한기생충학열대의학회 2018 The Korean Journal of Parasitology Vol.56 No.6

Mechanical and Microscopic Properties of Copper-contaminated Soil Solidified with Calcium Carbide Residue, Metakaolin, and Desulfurization Gypsum under Freeze-thaw Cycles

Qiang Wang,Dandan Ge,Guojun Cai,Man Li,Liuyan Wu,Huangrui Xu 대한토목학회 2023 KSCE Journal of Civil Engineering Vol.27 No.2

The solidification/stabilization effect of heavy metal contaminated soils in frozen soil regions may be weakened. A novel binder comprising calcium carbide residue, metakaolin, and desulfurization gypsum was used to solidify and stabilize copper-contaminated soil subjected to freeze-thaw (F-T) cycles. The unconfined compressive strength (UCS), F-T cycles, scanning electron microscope (SEM), X-ray diffraction (XRD), and pH tests were conducted to investigate the characteristics of UCS, deformation, pH value, and microscopic mechanism of contaminated soils. The results demonstrated that the UCS of contaminated soils decreased with the increasing F-T cycles and Cu2+ concentration; the strength loss rate increased first and then decreased as the F-T cycles increased. The failure strain rose first and then reduced with the increase of F-T cycles, and increased with the rise of Cu2+ concentration. There was a considerable correlation between UCS, failure strain, and deformation modulus E50. The pH value decreased with the increasing F-T cycles and Cu2+ concentration. The microscopic characteristics indicated that the formation of hydrated calcium silicate and ettringite was the fundamental reason for the enhanced UCS. Besides, heavy metals could be solidified and stabilized by chemical precipitation, physical encapsulation, and ion exchange. The effect of F-T cycles could significantly damage the internal structure of contaminated soils, and the frost heaving force could loosen the soil skeleton structure, leading to the deterioration of the mechanical properties.

Downregulation of lysyl oxidase and lysyl oxidase-like protein 2 suppressed the migration and invasion of trophoblasts by activating the TGF-β/collagen athway in preeclampsia

Xiang-Hong Xu,Yuanhui Jia,Xinyao Zhou,Dandan Xie,Xiaojie Huang,Linyan Jia,Qian Zhou,Qingliang Zheng,Xiangyu Zhou,Kai Wang,Li-Ping Jin 생화학분자생물학회 2019 Experimental and molecular medicine Vol.51 No.-

Preeclampsia is a pregnancy-specific disorder that is a major cause of maternal and fetal morbidity and mortality with a prevalence of 6–8% of pregnancies. Although impaired trophoblast invasion in early pregnancy is known to be closely associated with preeclampsia, the underlying mechanisms remain elusive. Here we revealed that lysyl oxidase (LOX) and LOX-like protein 2 (LOXL2) play a critical role in preeclampsia. Our results demonstrated that LOX and LOXL2 expression decreased in preeclamptic placentas. Moreover, knockdown of LOX or LOXL2 suppressed trophoblast cell migration and invasion. Mechanistically, collagen production was induced in LOX- or LOXL2-downregulated trophoblast cells through activation of the TGF-β1/Smad3 pathway. Notably, inhibition of the TGF-β1/Smad3 pathway could rescue the defects caused by LOX or LOXL2 knockdown, thereby underlining the significance of the TGF-β1/ Smad3 pathway downstream of LOX and LOXL2 in trophoblast cells. Additionally, induced collagen production and activated TGF-β1/Smad3 were observed in clinical samples from preeclamptic placentas. Collectively, our study suggests that the downregulation of LOX and LOXL2 leading to reduced trophoblast cell migration and invasion through activation of the TGF-β1/Smad3/collagen pathway is relevant to preeclampsia. Thus, we proposed that LOX, LOXL2, and the TGF-β1/Smad3/collagen pathway can serve as potential markers and targets for clinical diagnosis and therapy for preeclampsia.

Circulating Current Harmonics Suppression for Modular Multilevel Converters Based on Repetitive Control

Binbin Li,Dandan Xu,Dianguo Xu 전력전자학회 2014 JOURNAL OF POWER ELECTRONICS Vol.14 No.6

Modular multilevel converters (MMCs) have emerged as the most promising topology for high and medium voltage applications for the coming years. However, one particular negative characteristic of MMCs is the existence of circulating current, which contains a dc component and a series of low-frequency even-order ac harmonics. If not suppressed, these ac harmonics will distort the arm currents, increase the power loses, and cause higher current stresses on the semiconductor devices. Repetitive control (RC) is well known due to its distinctive capabilities in tracking periodic signals and eliminating periodic errors. In this paper, a novel circulating current control scheme base on RC is proposed to effectively track the dc component and to restrain the low-frequency ac harmonics. The integrating function is inherently embedded in the RC controller. Therefore, the proposed circulating current control only parallels the RC controller with a proportional controller. Thus, conflicts between the RC controller and the traditional proportional integral (PI) controller can be avoided. The design methodologies of the RC controller and a stability analysis are also introduced. The validity of the proposed circulating current control approach has been verified by simulation and experimental results based on a three-phase MMC downscaled prototype.

Circulating Current Harmonics Suppression for Modular Multilevel Converters Based on Repetitive Control

Li, Binbin,Xu, Dandan,Xu, Dianguo The Korean Institute of Power Electronics 2014 JOURNAL OF POWER ELECTRONICS Vol.14 No.6

Modular multilevel converters (MMCs) have emerged as the most promising topology for high and medium voltage applications for the coming years. However, one particular negative characteristic of MMCs is the existence of circulating current, which contains a dc component and a series of low-frequency even-order ac harmonics. If not suppressed, these ac harmonics will distort the arm currents, increase the power loses, and cause higher current stresses on the semiconductor devices. Repetitive control (RC) is well known due to its distinctive capabilities in tracking periodic signals and eliminating periodic errors. In this paper, a novel circulating current control scheme base on RC is proposed to effectively track the dc component and to restrain the low-frequency ac harmonics. The integrating function is inherently embedded in the RC controller. Therefore, the proposed circulating current control only parallels the RC controller with a proportional controller. Thus, conflicts between the RC controller and the traditional proportional integral (PI) controller can be avoided. The design methodologies of the RC controller and a stability analysis are also introduced. The validity of the proposed circulating current control approach has been verified by simulation and experimental results based on a three-phase MMC downscaled prototype.

What do we learn from CeO₂

Shanwei HU,Dandan KONG,Qian XU,Junfa ZHU 한국진공학회 2016 한국진공학회 학술발표회초록집 Vol.2016 No.8

Study on the Mechanical Characteristics of Urban Sludge Solidified by Industrial Waste

Liuyan Wu,Qiang Wang,Dandan Ge,Huangrui Xu,Guojun Cai 대한토목학회 2023 KSCE Journal of Civil Engineering Vol.27 No.7

Urban sludge is an extensive volume with a prominent environmental impact. The researchexplored an application technology for converting urban sludge into a usable improved soilresource by using industrial waste, providing a new reference for the reuse of industrial waste. In this study, three industrial wastes, namely ground granulated blast slag, calcium carbideresidue, and desulfurized gypsum, were used as curing agents to solidify the urban sludge. Based on the unconfined compressive strength (UCS) test and chamber analysis, the effects ofcuring agent dosing and maintenance age of sludge-cured soil on the UCS and stress- strainwere studied. The results showed that with the increase of curing agent, the UCS of cured soilfirst increased and then decreased, and the breaking strain showed a decreasing trend. Theoptimum ratio of materials was sludge: calcium carbide residue: ground granulated blast slag:desulfurization gypsum = 100:15:15:5, record this material ratio as C15G15D5. Moreover,trials showed that C15G15D5 cured the sludge soil better than the cement alone, whichachieved the purpose of reusing the three industrial wastes and urban sludge. It was analyzedthat the hydrated calcium silicate (C-S-H), calcium aluminate (C-A-H) and ettringite (AFt) inthe hydration products were produced to make the soil skeleton stronger and enhance thestrength of the sludge-cured soil.