A Library of Seed@High-Entropy-Alloy Core-shell Nanocrystals With Controlled Facets for Catalysis.

High-entropy-alloy (HEA) nanocrystals hold immense potential for catalysis, offering virtually unlimited alloy combinations through the inclusion of at least five constituent elements in varying ratios. However, general and effective strategies for synthesizing libraries of HEA nanocrystals with controlled surface atomic structures remain scarce. In this study, a transferable strategy for developing a library of facet-controlled seed@HEA nanocrystals through seed-mediated growth is presented.

Mechanistic understanding of N activation: a comparison of unsupported and supported Ru catalysts.

N dissociative adsorption is commonly the rate-determining step in thermal ammonia synthesis. Herein, we performed density functional theory (DFT) calculations to understand the N dissociation mechanism on models of unsupported Ru(0001) terraces, Ru B5 sites, and polar MgO(111)-supported Ru cluster mimicking a B5 site geometry, denoted (Ru(B5-like)/MgO(111)). The activation energy of N dissociative adsorption on the Ru(B5-like)/MgO(111) model ( = 0.

Dispersed surface Ru ensembles on MgO(111) for catalytic ammonia decomposition.

Ammonia is regarded as an energy vector for hydrogen storage, transport and utilization, which links to usage of renewable energies. However, efficient catalysts for ammonia decomposition and their underlying mechanism yet remain obscure. Here we report that atomically-dispersed Ru atoms on MgO support on its polar (111) facets {denoted as MgO(111)} show the highest rate of ammonia decomposition, as far as we are aware, than all catalysts reported in literature due to the strong metal-support interaction and efficient surface coupling reaction.

Do stoichiometric or nonstoichiometric models of a polar surface affect their structural, energetic and electronic structure properties? A DFT case study of Ru/MgO(111).

The structural, energetic and electronic structure properties of stoichiometric and nonstoichiometric slab models of bare MgO(111) and Ru/MgO(111) with different coverages of 1 monolayer (ML), 1/4 ML and 1/16 ML have been investigated using spin-polarized density functional theory. Calculated results show that the structural, energetic properties and charge transfer of both bare MgO(111) and Ru/MgO(111) are independent of the stoichiometric and nonstoichiometric models. In contrast, their density of state (DOS) profiles demonstrate metal and half-metal characters for the stoichiometric and nonstoichiometric bare MgO(111) surfaces, respectively.

Cluster Nanozymes with Optimized Reactivity and Utilization of Active Sites for Effective Peroxidase (and Oxidase) Mimicking.

Single-atom catalysts have attracted attention in the past decade since they maximize the utilization of active sites and facilitate the understanding of product distribution in some catalytic reactions. Recently, this idea has been extended to single-atom nanozymes (SAzymes) for the mimicking of natural enzymes such as horseradish peroxidase (HRP) often used in bioanalytical applications. Herein, it is demonstrated that those SAzymes without constructing the reaction pocket of HRP still undergo the OH radical-mediated pathway like most of the reported nanozymes.

Sero-evaluation of Immune Responses to in a Postelimination Setting.

Cholera remains a significant public health problem worldwide. In settings of declining incidence, serosurveillance may be used to augment clinical surveillance. We utilized dried blood spot sampling and cholera-specific antibody testing to examine the serologic profiles of vaccinated and unvaccinated children in southern Vietnam, where cholera was recently eliminated.

Rapid Disappearance of Poliovirus Type 2 (PV2) Immunity in Young Children Following Withdrawal of Oral PV2-Containing Vaccine in Vietnam.

Background: Due to global shortage of inactivated poliovirus vaccine and withdrawal of oral vaccine containing poliovirus type 2 (PV2), a PV2-containing vaccine was not used in Vietnam May 2016 to October 2018. We assessed the population immunity gap to PV2.

Methods: A cross-sectional survey in children aged 1-18 months was carried out in January 2018.

Electronic structure of CuWO: dielectric-dependent, self-consistent hybrid functional study of a Mott-Hubbard type insulator.

CuWO is a semiconducting oxide with interesting applications in photocatalysis. In this paper we present an accurate study of the electronic properties of stoichiometric and oxygen deficient CuWO based on a dielectric dependent hybrid density functional. In CuWO the Cu ions (Cu) are in a 3d configuration, so that the material must be classified as a magnetic insulator.

Electronic structure of Al, Ga, In and Cu doped ZnO/Cu(111) bilayer films.

The effect of doping with group-III metals (Al, Ga and In) and Cu free standing and Cu(111) supported ZnO bilayer films has been investigated computationally by using the DFT+U method including dispersion contributions. The changes in the electronic properties of doped ZnO and ZnO/Cu(111) films have been tested by adsorbing CO probe molecules. The replacement of a lattice Zn ion in a free-standing ZnO bilayer by a group-III element generates an extra electron whose distribution depends on the dopant.

Safety and immunogenicity of inactivated monovalent influenza A/H1N1 vaccine candidate manufactured in Vietnam.

We tested a new A/H1N1 inactivated influenza vaccine (IIV) manufactured by Institute of Vaccines and Medical Biologics (IVAC), Vietnam in 48 adults in a Phase 1, double-blinded, randomized, placebo-controlled trial. Two doses of unadjuvanted vaccine or placebo were administered three weeks apart. The vaccine was well tolerated with only transient mild local reactions and low-grade fever in a small proportion of the subjects.

Epidemiology of acute diarrhea caused by rotavirus in sentinel surveillance sites of Vietnam, 2012-2015.

A prospective, multicentre study was conducted in four sentinel surveillance hospitals to assess the trend and epidemiology of acute diarrhea caused by Rotavirus in Vietnam. During the period 2012-2015, a total 8,889 children under 5 years of age were enrolled in the surveillance, and 8689 stool samples were collected. Of these cases, Rotavirus was most common pathogen 46.

Clinical testing of an inactivated influenza A/H5N1 vaccine candidate in a double-blinded, placebo-controlled, randomized trial in healthy adults in Vietnam.

We tested an inactivated egg-grown whole virus influenza A/H5N1 vaccine candidate developed by the Institute of Vaccines and Medical Biologicals (IVAC), a state-run vaccine manufacturer in Vietnam, in a Phase 1, placebo controlled, double blinded, randomized trial. The vaccine was adjuvanted with aluminum hydroxide. The trial enrolled 75 subjects who were randomized to receive two injections of one of the following: low-dose of vaccine (7.

The effect of the zeolite pore size on the Lewis acid strength of extra-framework cations.

The catalytic activity and the adsorption properties of zeolites depend on their topology and composition. For a better understanding of the structure-activity relationship it is advantageous to focus just on one of these parameters. Zeolites synthesized recently by the ADOR protocol offer a new possibility to investigate the effect of the channel diameter on the adsorption and catalytic properties of zeolites: UTL, OKO, and PCR zeolites consist of the same dense 2D layers (IPC-1P) that are connected with different linkers (D4R, S4R, O-atom, respectively) resulting in the channel systems of different sizes (14R × 12R, 12R × 10R, 10R × 8R, respectively).

IMMUNOGENICITY AND SAFETY OF QUINVAXEM® (DIPHTHERIA, TETANUS, WHOLE-CELL PERTUSSIS, HEPATITIS B AND HAEMOPHILUS INFLUENZAE TYPE B VACCINE) GIVEN TO VIETNAMESE INFANTS AT 2 TO 4 MONTHS OF AGE.

Vietnam plans to replace the routine childhood diphtheria, pertussis and tetanus combination (DPT) vaccine with a pentavalent vaccine. The present study was performed to assess the immunogenicity and safety of the combined diphtheria, tetanus, whole-cell pertussis, hepatitis B (HepB), and Haemophilus influenzae type b (Hib) (DTwP-HepB-Hib) Quinvaxem® vaccine in children. A total of 131 infants received the Quinvaxem® vaccine at 2, 3 and 4 months.

Computational investigation of the Lewis acidity in three-dimensional and corresponding two-dimensional zeolites: UTL vs IPC-1P.

The adsorption and catalytic properties of three-dimensional zeolite UTL were investigated computationally along with properties of its two-dimensional analogue IPC-1P that can be obtained from UTL by a removal of D4R units. Adsorption properties and Lewis acidity of extra-framework Li(+) sites were investigated for both two- and three-dimensional forms of UTL using the carbon monoxide as a probe molecule. The CO adsorption enthalpies, calculated with various dispersion-corrected DFT methods, including DFT/CC, DFT-D2, and vdW-DF2, and the CO stretching frequencies obtained with the νCO/rCO correlation method are compared for corresponding Li(+) sites in 3D and 2D UTL zeolite.

Theoretical investigation of layered zeolites with MWW topology: MCM-22P vs. MCM-56.

The inter-layer interactions and the possible arrangements of MWW-type layers were investigated computationally at the non-local density functional theory level. Powder XRD patterns were simulated for structures obtained computationally and compared with experimental data. The MCM-22P material corresponds to the layers bound with relatively strong hydrogen bonds between surface silanol groups that is an energetically preferred structure in the presence of a structure directing agent (hexamethyleneimine).

Measuring the Brønsted acid strength of zeolites--does it correlate with the O-H frequency shift probed by a weak base?

Brønsted-acid zeolites are currently being used as catalysts in a wide range of technological processes, spanning from the petrochemical industry to biomass upgrade, methanol to olefin conversion and the production of fine chemicals. For most of the involved chemical processes, acid strength is a key factor determining catalytic performance, and hence there is a need to evaluate it correctly. Based on simplicity, the magnitude of the red shift of the O-H stretching frequency, Δν(OH), when the Brønsted-acid hydroxyl group of protonic zeolites interacts with an adsorbed weak base (such as carbon monoxide or dinitrogen) is frequently used for ranking acid strength.

Superparamagnetic hollow hybrid nanogels as a potential guidable vehicle system of stimuli-mediated MR imaging and multiple cancer therapeutics.

Hollow hybrid nanogels were prepared first by the coassembly of the citric acid-coated superparamagnetic iron oxide nanoparticles (SPIONs, 44 wt %) with the graft copolymer (56 wt %) comprising acrylic acid and 2-methacryloylethyl acrylate units as the backbone and poly(ethylene glycol) and poly(N-isopropylacrylamide) as the grafts in the aqueous phase of pH 3.0 in the hybrid vesicle structure, followed by in situ covalent stabilization via the photoinitiated polymerization of MEA residues within vesicles. The resultant hollow nanogels, though slightly swollen, satisfactorily retain their structural integrity while the medium pH is adjusted to 7.

Dual stimuli-responsive polymeric hollow nanogels designed as carriers for intracellular triggered drug release.

Dual stimuli-responsive hollow nanogel spheres serving as an efficient intracellular drug delivery platform were obtained from the spontaneous coassociation of two graft copolymers into the vesicle architecture in aqueous phase. Both copolymers comprise acrylic acid (AAc) and 2-methacryloylethyl acrylate (MEA) units as the backbone and either poly(N-isopropylacrylamide) (PNIPAAm) alone or both PNIPAAm and monomethoxypoly(ethylene glycol) (mPEG) chain segments as the grafts. The assemblies were then subjected to covalent stabilization within vesicle walls with ester-containing cross-links by radical polymerization of MEA moieties, thereby leading to hollow nanogel particles.

Endemic diphtheria in Ho Chi Minh City; Viet Nam: a matched case-control study to identify risk factors of incidence.

From 1999 to 2004, Ho Chi Minh City (HCMC), Vie Nam reported 401 clinically suspected and 90 laboratory-confirmed diphtheria. To identify risk factors, a matched case-control study was conducted during 2005 and 2006. In total, 88 cases that occurred in 2003 and 2004 and 352 age- and sex-matched controls were studied.