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Co n -1 TMO n -2 + ( n = 6-8), (TM = V, Cr, Mn, and Fe) clusters are investigated using density functional theory calculations. The transition metal atoms preferentially replace one Co atom at sites where the number of metal-oxygen bonds is maximized, forming more stable structures. The evaporation of a Co atom is the most fragile dissociation channel for both pure and doped species. Bare cobalt oxide clusters exhibit parallel spin ordering, whereas both parallel and antiparallel spin ordering are observed in the doped species. Notably, a ferromagnetic-to-ferrimagnetic transition occurs in the V-doped clusters, while the ferromagnetic behavior is enhanced in the Fe-doped species., Competing Interests: The authors declare no competing financial interest., (This journal is © The Royal Society of Chemistry.)

MFe 2 O 4 (M = Co, Fe, Mn) nanoparticles were successfully formed through the chemical co-precipitation technique. X-ray diffraction, scanning electron microscopy, and energy-dispersive X-ray analysis were used to investigate samples' structural properties. The investigated structural properties included phases formed, crystallite size, cation distribution, hopping length, bond length, bond angle, edge length, and shared and unshared octahedral edge length. Scanning electron micrographs of the prepared samples demonstrated well-defined crystalline nanoparticles. The grain diameter was 15, 9, and 34 nm for CoFe 2 O 4 , Fe 3 O 4 , and MnFe 2 O 4 , respectively. The energy-dispersive X-ray analysis confirmed the existence of every element (Co, Fe, and O) and no discernible impurities in the samples. The optical properties were studied in detail through photoluminescence (PL) spectroscopy and Raman spectroscopy. The presence of active modes in Raman spectra confirmed the spinel structure of the MFe 2 O 4 nanoparticles. The direct bandgap energy estimated through UV-visible spectroscopy was about 2.59-2.64 eV, corresponding with the energy-band structures of the octahedral site (1.70 eV) and the tetrahedral site (0.9 eV). This result was further confirmed by PL emission spectra. Based on Mie theory and UV-visible and PL spectral data, the mechanism of photothermal characterization for MFe 2 O 4 nanoparticles was determined. Investigating the changes in temperature of magnetic parameters including coercivity, squareness ratio, and saturation magnetization for MFe 2 O 4 samples showed the dominant influence of ion distribution and A-A, A-B, and B-B exchange interactions. This study also showed that strong anisotropy and weak dipolar interaction tended to increase the coercivity and squareness ratio of CoFe 2 O 4 . Conversely, weaker anisotropy and stronger dipolar interaction corresponded with the small coercivity and squareness ratio of Fe 3 O 4 and MnFe 2 O 4 samples., Competing Interests: The authors confirm that there are no known conflicts of interest associated with this publication., (This journal is © The Royal Society of Chemistry.)

The electronic, magnetic, optical and elastic properties of nanomaterials are governed partially by the crystallite size and crystal defects. Here, the crystalline size of hexagonal La 1- x Sr x MnO 3 ( x = 0.3) nanoparticles was determined using various methods. Single-phase La 0.7 Sr 0.3 MnO 3 nanopowders were produced after 10 h of milling in a commercial high-energy SPEX 8000D shaker mill, and then they were heated at 700 °C and 800 °C to study the effect of calcined temperature on the crystallization of nanoparticles. The modified Scherrer, Williamson-Hall, size-strain, and Halder-Wagner methods were used to determine the crystallite sizes and the elastic properties, such as intrinsic strain, stress, and energy density, from the X-ray diffraction peak broadening analysis. The obtained results were then compared with one another. The difference in crystallite sizes calculated from the different methods was due to the different techniques., Competing Interests: The authors declare that they have no conflict of interest., (This journal is © The Royal Society of Chemistry.)

We have used the coprecipitation and mechanical-milling methods to fabricate CoFe 2 O 4 nanoparticles with an average crystallite size ( d ) varying from 81 to ∼12 nm when changing the milling time ( t m ) up to 180 min. X-ray diffraction and Raman-scattering studies have proved the samples crystalizing in the spinel structure. Both the lattice constant and residual strain tend to increase when t m ( d ) increases (decreases). The analysis of magnetization data has revealed a change in the coercivity ( H c ) towards the hard-magnetic properties. Specifically, the maximum H c is about 2.2 kOe when t m = 10 min corresponding to d ≈ 29 nm; beyond this t m ( d ) value, H c gradually decreases. Meanwhile, the increase of t m always reduces the saturation magnetization ( M s ) from ∼69 emu g -1 for t m = 0 to 35 emu g -1 for t m = 180 min. The results collected as analyzing X-ray absorption data have indicated a mixed valence state of Fe 2+,3+ and Co 2+ ions. We think that the migration and redistribution of these cations between the tetrahedral and octahedral sites together with lattice distortions and defects induced by the milling process have impacted the magnetic properties of the CoFe 2 O 4 nanoparticles., Competing Interests: The authors declare no competing financial interest., (This journal is © The Royal Society of Chemistry.)

Background: The severity of dengue infection has been reportedly associated with patients' allergic reactions. To further elucidate the role of allergy in dengue severity, we conducted a matched case-control study to assess the association between allergic background and dengue shock syndrome., Methods: This is a matched case-control study that was carried out in the Hospital for Tropical Diseases, Ho Chi Minh City, Vietnam from January to December 2017. Dengue infection was determined by non-structure protein 1 (NS1) diagnostic quick test or anti-dengue antibodies (IgM). The total and dengue-specific IgE levels were measured using ELISA. Patients' demographics, clinical, and allergic profiles were collected using a structured questionnaire., Results: A total of 572 dengue patients with positive NS1 (92.7%) or IgM antibodies (7.3%) results were included in this study. Of these patients, 143 patients developed dengue shock syndrome (case group) while the other 429 patients did not (control group). None of the baseline characteristics including age, sex, or being overweight was significantly different between the two groups (p>0.05). In multivariable analysis, having a history of dengue infection (OR=3.35, 95% CI: 1.8-6.17, p<0.001) and allergic rhinitis (OR=1.95, 95% CI: 1.11-3.4, p = 0.019) were found to be associated with dengue shock syndrome. Higher levels of dengue-specific IgE were not associated with worse outcomes in patients with allergies (p = 0.204) or allergic rhinitis (p = 0.284)., Conclusion: Dengue patients presenting with a history of a previous dengue infection or allergic rhinitis should be considered high-risk patients for the development of dengue shock syndrome., Competing Interests: Declaration of Competing Interest All authors certify that they have no affiliations with or involvement in any organization or entity with any financial interest (such as honoraria; educational grants; participation in speakers’ bureaus; membership, employment, consultancies, stock ownership, or other equity interest; and expert testimony or patent-licensing arrangements), or non-financial interest (such as personal or professional relationships, affiliations, knowledge, or beliefs) in the subject matter or materials discussed in this manuscript., (Copyright © 2022 Elsevier B.V. All rights reserved.)

Background: Despite medicinal advances, cancer is still a big problem requiring better diagnostic and treatment tools. Magnetic nanoparticle (MNP)-based nanosystems for multiple-purpose applications were developed for these unmet needs. Methods: This study fabricated novel trifunctional MNPs of Fe 3 O 4 @PLA-PEG for drug release, MRI and magnetic fluid hyperthermia. Result: The MNPs provided a significant loading of curcumin (∼11%) with controllable release ability, a high specific absorption rate of 82.2 W/g and significantly increased transverse relaxivity ( r 2  = 364.75 mM -1 s -1 ). The in vivo study confirmed that the MNPs enhanced MRI contrast in tumor observation and low-field magnetic fluid hyperthermia could effectively reduce the tumor size in mice bearing sarcoma 180. Conclusion: The nanocarrier has potential for drug release, cancer treatment monitoring and therapy.

This work investigates the structure, optical and electrical conductivity properties of BaTi 1- x Co x O 3 (0≤ x ≤0.1) ceramics prepared by the hydrothermal method. The X-ray diffraction and Raman scattering analysis demonstrates that the prepared samples have a single-phase tetragonal structure with P 4 mm symmetry. The UV-vis diffuse reflectance spectrum confirms the influence of Co concentration on the direct optical band gap of BaTi 1- x Co x O 3 ceramics. The optical band gap shifts from 3.14 eV to 3.44 eV as the Co concentration increases from 0 to 0.1. The dielectric constant increases with the depletion of frequency according to the Maxwell-Wagner and Koops model. The AC conductivity versus frequency curve indicates that the conduction mechanism is determined by using the correlated barrier hopping (CBH) model. The Cole-Cole plot of the complex impedance was investigated for the prepared samples. The compounds showed dielectric relaxation of the non-Debye type., Competing Interests: There are no conflicts to declare., (This journal is © The Royal Society of Chemistry.)

Cobalt doped magnetite nanoparticles (Co x Fe 3- x O 4 NPs) are investigated extensively because of their potential hyperthermia application. However, the complex interrelation among chemical compositions and particle size means their correlation with the magnetic and heating properties is not trivial to predict. Here, we prepared Co x Fe 3- x O 4 NPs (0 ≤ x ≤ 1) to investigate the effects of cobalt content and particle size on their magnetic and heating properties. A detailed analysis of the structural features indicated the similarity between the crystallite and particle sizes as well as their non-monotonic change with the increase of Co content. Magnetic measurements for the Co x Fe 3- x O 4 NPs (0 ≤ x ≤ 1) showed that the blocking temperature, the saturation magnetization, the coercivity, and the anisotropy constant followed a similar trend with a maximum at x = 0.7. Moreover, 57 Fe Mössbauer spectroscopy adequately explained the magnetic behaviour, the anisotropy constant, and saturation magnetization of low Co content samples. Finally, our study shows that the relaxation loss is a primary contributor to the SAR in Co x Fe 3- x O 4 NPs with low Co contents as well as their potential application in magnetic hyperthermia., Competing Interests: The authors declare no competing financial interest., (This journal is © The Royal Society of Chemistry.)

In this study, we present an experiment showing that designing multifunctional MnFe 2 O 4 -Ag nanoparticles to act as a dual hyperthermia agent is an efficient route for enhancing their heating ability. Interestingly, the specific absorption rate of the heteromeric MnFe 2 O 4 -Ag nanoparticles increased 2.7 times under simultaneous irradiation of a 100 Oe magnetic field and 0.14 W cm -2 laser compared to the action by the magnetic field alone, and more interestingly, is 30% higher than the sum of the two individual actions. The synergistic benefit of the magneto- and photo-thermal properties of the heteromeric structure can reduce the strengths of the magnetic field and laser intensities as well as their irradiation time to levels lower than those required in their hyperthermia applications individually. In vitro cytotoxicity analysis performed on HepG2 liver cancer and Hela cervical cancer cell lines showed that IC 50 values were 83 ± 5.6 μg mL -1 (for HepG2) and 122.6 ± 19.8 μg mL -1 (for Hela cells) after 48 h of incubation, therefore, the nanoparticles are moderately cytotoxic and nontoxic to HepG2 and Hela cells, respectively; which offers the potential of safe therapy., Competing Interests: The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (This journal is © The Royal Society of Chemistry.)

We investigated the coupling phenomenon between plasmonic resonance and waveguide modes through theoretical and experimental parametric analyses on the bimetallic waveguide-coupled long-range surface plasmon resonance (Bi-WCLRSPR) structure. The calculation results indicated that the multi-plasmonic coupling gives rise to the enhanced depth-to-width ratio of the reflection dip compared to that of LRSPR excited using a single set of Ag and Teflon. The optimized thickness of Ag(40 nm)/Teflon(700 nm)/Ag(5 nm)/Au(5 nm) was obtained and generated the highest plasmon intensity enhancement, which was 2.38 folds in comparison to the conventional bimetallic surface plasmon resonance (SPR) configuration (Ag/Au). 17β-Estradiol was used in the fluorescence enhancement experiment by the reflection geometry-based system, wherein the excitation light source was on the side of a WC-LRSPR chip opposite to that of the light detection unit. The phenomenon of surface plasmon-couple emission (SPCE) depends on the number of 17β-estradiol molecule promoters from female sex steroid hormones, which demonstrated a limit of detection (LOD) of 2 pg mL -1 and 1.47-fold fluorescence improvement as compared to the non-coated material on the surface of pristine glass. This enhanced WC-LRSPR can readily find application in fluorescence escalation needed in cases where a weak fluorescence signal is predicted, such as the small volume of liquid containing fluorescent dyes in biological diagnosis., Competing Interests: There are no conflicts to declare., (This journal is © The Royal Society of Chemistry.)

Magnetic inductive heating (MIH) has been a topic of great interest because of its potential applications, especially in biomedicine. In this paper, the parameters characteristic for magnetic inductive heating power including maximum specific loss power (SLP max ), optimal nanoparticle diameter (D c ) and its width (ΔD c ) are considered as being dependent on magnetic nanoparticle anisotropy (K). The calculated results suggest 3 different Néel-domination (N), overlapped Néel/Brownian (NB), and Brownian-domination (B) regions. The transition from NB- to B-region changes abruptly around critical anisotropy K c . For magnetic nanoparticles with low K (K < K c ), the feature of SLP peaks is determined by a high value of D c and small ΔD c while those of the high K (K > K c ) are opposite. The decreases of the SLP max when increasing polydispersity and viscosity are characterized by different rates of d(SLP max )/dσ and d(SLP max )/dη depending on each domination region. The critical anisotropy K c varies with the frequency of an alternating magnetic field. A possibility to improve heating power via increasing anisotropy is analyzed and deduced for Fe 3 O 4 magnetic nanoparticles. For MIH application, the monodispersity requirement for magnetic nanoparticles in the B-region is less stringent, while materials in the N- and/or NB-regions are much more favorable in high viscous media. Experimental results on viscosity dependence of SLP for CoFe 2 O 4 and MnFe 2 O 4 ferrofluids are in good agreement with the calculations. These results indicated that magnetic nanoparticles in the N- and/or NB-regions are in general better for application in elevated viscosity media.

Background: The protective or pathogenic role of T lymphocytes during the acute phase of dengue virus (DENV) infection has not been fully understood despite its importance in immunity and vaccine development. Objectives: This study aimed to clarify the kinetics of T lymphocyte subsets during the clinical course of acute dengue patients. Study design: In this hospital-based cohort study, 59 eligible Vietnamese dengue patients were recruited and admitted. They were investigated and monitored for T cell subsets and a panel of clinical and laboratory parameters every day until discharged and at post-discharge from the hospital. Results: We described for the first time the kinetics of T cell response during the clinical course of DENV infection. Severe cases showed significantly lower levels of effector CD8 + T cells compared to mild cases at day -1 ( p = 0.017) and day 0 ( p = 0.033) of defervescence. After defervescence, these cell counts in severe cases increased rapidly to equalize with the levels of mild cases. Our results also showed a decline in total CD4 + T, Th1, Th1/17 cells during febrile phase of dengue patients compared to normal controls or convalescent phase. On the other hand, Th2 cells increased during DENV infection until convalescent phase. Cytokines such as interferon-γ, IL-12p70, IL-5, IL-23, IL-17A showed tendency to decrease on day 0 and 1 compared with convalescence and only IL-5 showed significance indicating the production during acute phase was not systemic. Conclusion: With a rigorous study design, we uncovered the kinetics of T cells in natural DENV infection. Decreased number of effector CD8 + T cells in the early phase of infection and subsequent increment after defervescence day probably associated with the T cell migration in DENV infection., (Copyright © 2020 Manh, Weiss, Thuong, Mizukami, Dumre, Luong, Thanh, Thang, Huu, Phuc, Nhung, Mai, Truong, Ngu, Quoc, Ha, Ton, An, Halhouli, Quynh, Kamel, Karbwang, Huong, Huy and Hirayama.)

Objectives: This study aimed to investigate the knowledge, behaviour and attitudes towards Chagas disease (CD) among Latin American migrants in Japan and to evaluate the effectiveness of an educational activity (EA) in increasing knowledge of CD., Design: A cross-sectional, mixed-methods study employing a preknowledge and postknowledge test and focus group discussion, conducted from March 2018 to June 2018., Participants: Seventy-two participants were included, all born in Bolivia and residents in four Japanese cities. Fifty-nine of them participated in the EA., Interventions: The EA comprised showing three videos about CD and a group discussion covering different dimensions of CD and was evaluated with questionnaires to analyse the knowledge of the participants before and after., Results: Seventy-two participants were enrolled, predominantly from highly endemic CD areas of Bolivia. Though most participants were familiar with vector-borne transmission, epidemiology and symptomatology of CD, the baseline knowledge of CD was low. Less than 10% of them had been tested prior for CD. The dominant factors associated with better knowledge were living in Japan for more than 10 years (OR=8.42, 95% CI 1.56 to 48.62) and previously testing for CD (OR=11.32; 95% CI 1.52 to 105.9). The EA significantly improved the CD knowledge of the participants (p value <0.0001; 95% CI 2.32 to 3.84). The participants associated the term 'Chagas' mostly with fear and concern. The level of stigmatisation was low, in contrast to the results of other studies. The barriers encountered in care-seeking behaviour were language, the migration process and difficulties to access the healthcare system., Conclusion: EA with an integrative approach is useful to increase the knowledge of CD within the Bolivian migrant population living in Japan. The activity brings the possibility to explore not only the level of knowledge but also to reveal experiences and to understand the needs of the people at risk. Considering them as actors towards healthcare solutions could lead to better outcomes for the success of future policies and interventions aimed to decrease the global burden., Competing Interests: Competing interests: None declared., (© Author(s) (or their employer(s)) 2020. Re-use permitted under CC BY-NC. No commercial re-use. See rights and permissions. Published by BMJ.)

Background: Considerable progress has been made in dengue management, however the lack of appropriate predictors of severity has led to huge number of unwanted admissions mostly decided on the grounds of warning signs. Apoptosis related mediators, among others, are known to correlate with severe dengue (SD) although no predictive validity is established. The objective of this study was to investigate the association of plasma cell-free DNA (cfDNA) with SD, and evaluate its prognostic value in SD prediction at acute phase., Methods: This was a hospital-based prospective cohort study conducted in Vietnam. All the recruited patients were required to be admitted to the hospital and were strictly monitored for various laboratory and clinical parameters (including progression to SD) until discharged. Plasma samples collected during acute phase (6-48 h before defervescence) were used to estimate the level of cfDNA., Results: Of the 61 dengue patients, SD patients (n = 8) developed shock syndrome in 4.8 days (95% CI 3.7-5.4) after the fever onset. Plasma cfDNA levels before the defervescence of SD patients were significantly higher than the non-SD group (p = 0.0493). From the receiver operating characteristic (ROC) curve analysis, a cut-off of > 36.9 ng/mL was able to predict SD with a good sensitivity (87.5%), specificity (54.7%), and area under the curve (AUC) (0.72, 95% CI 0.55-0.88; p = 0.0493)., Conclusions: Taken together, these findings suggest that cfDNA could serve as a potential prognostic biomarker of SD. Studies with cfDNA kinetics and its combination with other biomarkers and clinical parameters would further improve the diagnostic ability for SD.

The lack of an appropriate model has been a serious concern in dengue research pertinent to immune response and vaccine development. It remains a matter of impediment in dengue virus (DENV) studies when it comes to an in vitro model, which requires adequate quantity of dendritic cells (DC) with uniform characters. Other sources of DC, mostly monocyte derived DC (moDC), have been used despite their limitations such as quantity, proliferation, and donor dependent characters. Recent development of human iPS cells with consistent proliferation for long, stable, functional characteristics and desired HLA background has certainly offered added advantages. Therefore, we hypothesised that iPS derived cells would be a reliable alternative to the traditional DCs to be used with an in vitro DENV system. To develop a DENV infection and T cell activation model, we utilised iPS cells (HLA-A*24) as the source of DC. iPS-ML-DC was prepared and DENV infectivity was assessed apart from the major surface markers expression and cytokine production potential. Our iPS-ML-DC had major DC markers expression, DENV infection efficiency and cytokine production properties similar to that of moDC. Moreover, DENV infected iPS-ML-DC demonstrated the ability to activate HLA-matched T cell (but not mismatched) in vitro as evidenced by significantly higher proportion of IFN-γ + CD69 + T cells compared to non-infected iPS-ML-DC. This affirmed the antigen-specific T cell activation by iPS-ML-DC as a function of antigen presenting cells. To conclude, maturation potential, DENV infection efficiency and T cell activation ability collectively suggest that iPS-ML-DC serves as an attractive option of DC for use in DENV studies in vitro.

There is no definitive predictor of dengue severity, and this has led to a very large number of unnecessary hospitalizations worldwide. Although mast cell mediators are believed to a play role in dengue severity, the lack of precise kinetic data demands further research on early predictors. We enrolled 111 patients with confirmed dengue and 85 with "other febrile illness" (OFI) in a hospital-based prospective study in Vietnam. Dengue patients were classified as level 1, 2, or 3 based on the clinical intervention received. Blood samples were collected from each patient every day (pre- and post-defervescence) and after discharge. Plasma chymase, total IgE, and dengue-specific IgE were measured. Dengue-specific IgE levels showed an increasing trend during the course of illness and remained high even at post-discharge, although no significant difference was observed among severity levels. Total IgE showed no such trend. The specific IgE/total IgE ratio (S/T ratio) remained constantly higher in level 3 patients compared to other levels, with a significant difference at some time points. The S/T ratio of acute phase samples (before defervescence) tended to increase with increasing severity (level 1 < 2 < 3), and was significantly higher in level 3 patients than in level 1 and OFI patients. As an early predictor of severity allowing level 3 patients to be distinguished from other dengue patients, the S/T ratio achieved a sensitivity of 75% and specificity of 68%. We describe the kinetic profiles of IgEs, their ratio, and chymase levels at different severity levels. The S/T ratio was found to be associated with dengue severity, suggesting that it could potentially be used as an early predictor of severity.

Dengue virus (DENV) replication between mosquito and human hosts is hypothesized to be associated with viral determinants that interact in a differential manner between hosts. However, the understanding of inter-host viral determinants that drive DENV replication and growth between hosts is limited. Through the use of clinical isolates, we identified an amino acid variation of Ala, Met and Val at position 116 of DENV-1 NS4B. While the proportion of virus with the NS4B-116V variant remained constantly high in serial passages in a mosquito cell line, populations of the NS4B-116M and NS4B-116A variants became dominant after serial passages in mammalian cell lines. Using recombinant DENV-1 viruses, the Val to Ala or Met alteration at position NS4B-116 (rDENV-1-NS4B-116A and rDENV-1-NS4B-116M) resulted in enhanced virus growth in human cells in comparison to the clone with Val at NS4B-116 (rDENV-1-NS4B-116V). However, the reverse phenomenon was observed in a mosquito cell line. Additionally, in a human cell line, differential levels of IFN-α/β and IFN-stimulated gene expressions (IFIT3, IFI44L, OAS1) suggested that the enhanced viral growth was dependent on the ability of the NS4B protein to hamper host IFN response during the early phase of infection. Overall, we identified a novel and critical viral determinant at the pTMD3 of NS4B region that displayed differential effects on DENV replication and fitness in human and mosquito cell lines. Taken together, the results suggest the importance of the NS4B protein in virus replication and adaptation between hosts.

Introduction: Dengue is a viral disease that spreads rapidly in the tropic and subtropic regions of the world and causes 22,000 deaths annually. In 2009, the World Health Organization (WHO) released a new classification of dengue infections, which divided them into three categories: dengue without warning sign (D), dengue with warning sign (DWS), and severe dengue (SD). However, researchers have been using different criteria to define persistent vomiting; therefore, we aimed to evaluate the ability of the number of vomiting times in early prediction of SD development among D/DWS patients., Method: A hospital-based cohort study was conducted in Ben Tre-south of Vietnam. We enrolled confirmed dengue patients with D and DWS at admission. The final classification was determined on the discharged day for every patient based on the classification of WHO 2009 without using vomiting symptom, using the receiver operating characteristic (ROC) curve to evaluate the ability of the number of vomiting times in early prediction of SD development among D/DWS patients., Result: The prevalence of vomiting symptom was higher in SD group than D/DWS group (92 versus 46 %, p = 0.006), and the median of the number of vomiting times was higher in SD group than D/DWS group (2.5 versus 0, p = 0.001). To distinguish SD from D/DWS, the ROC curve of the number of vomiting episodes showed that the area under the curve was 0.77; with the cut point of two, the sensitivity and specificity were 92 and 52 %, respectively., Discussion: The number of vomiting times could be a good clinical sign which can early predict SD from the group of D/DWS. We suggest the definition of persistent vomiting should be vomiting two times or more per day.