Dual-signal ratiometric electrochemiluminescence biosensor based on Au NPs-induced low-potential emission of PFO Pdots and LSPR-ECL mechanism for ultra-sensitive detection of microRNA-141.

In this study, we have for the first time constructed a ratiometric ECL biosensor for the ultrasensitive detection of microRNAs (miRNAs) using gold nanoparticles (Au NPs) to trigger both the low-potential emission from conjugated polymer poly(9,9-dioctylfluorene-2,7-diyl) dots (PFO Pdots) and the LSPR-ECL effect with sulfur-doped boron nitride quantum dots (S-BN QDs). PFO Pdots were first applied to the Au NPs-modified electrode, followed by covalent binding to capture the hairpin H1. Immediately thereafter, a small amount of miRNA-141 was able to generate a large amount of output DNA (OP) by traversing the target cycle. OP, H3-S-BN QDs, and H4-glucose oxidase (H4-GOD) were then added sequentially to the Au NPs-modified electrode surface, and the hybridization chain reaction (HCR) was initiated. This resulted in the introduction of a large amount of GOD into the system, which catalyzed the in situ formation of the co-reactant hydrogen peroxide (H2O2) from the substrate glucose. Due to the electron transfer effect, the production of H2O2 led to the ECL quenching of PFO Pdots. Meanwhile, H2O2 served as a co-reactant of S-BN QDs, resulting in strong ECL emission of S-BN QDs at the cathode. Furthermore, the cathodic ECL intensity of S-BN QDs was further enhanced by an LSPR-ECL mechanism between Au NPs and S-BN QDs. By measuring the ratio of ECL intensities at two excitation potentials, this approach could provide sensitive and reliable detection of miRNA-141 in the range of 0.1 fM ∼10 nM, with a detection limit of 0.1 fM.

Activation of Peracetic Acid by CoFe2O4 for Efficient Degradation of Ofloxacin: Reactive Species and Mechanism.

Peroxyacetic acid (PAA)-based advanced oxidation processes (AOPs) have attracted much attention in wastewater treatment by reason of high selectivity, long half-life reactive oxygen species (ROS), and wider applicability. In this study, cobalt ferrite (CoFe2O4) was applied to activate PAA for the removal of ofloxacin (OFX). The degradation of OFX could reach 83.0% via the CoFe2O4/PAA system under neutral conditions. The low concentration of co-existing anions and organic matter displayed negligible influence on OFX removal. The contributions of hydroxyl radicals (·OH), organic radicals (R-O·), and other reactive species to OFX degradation in CoFe2O4/PAA were systematically evaluated. Organic radicals (especially CH3C(O)OO·) and singlet oxygen (1O2) were verified to be the main reactive species leading to OFX destruction. The Co(II)/Co(III) redox cycle occurring on the surface of CoFe2O4 played a significant role in PAA activation. The catalytic performance of CoFe2O4 remained above 80% after five cycles. Furthermore, the ecotoxicity of OFX was reduced after treatment with the CoFe2O4/PAA system. This study will facilitate further research and development of the CoFe2O4/PAA system as a new strategy for wastewater treatment.

Flame-Retarded Rigid Polyurethane Foam Composites with the Incorporation of Steel Slag/Dimelamine Pyrophosphate System: A New Strategy for Utilizing Metallurgical Solid Waste.

Rigid polyurethane (RPUF) was widely used in external wall insulation materials due to its good thermal insulation performance. In this study, a series of RPUF and RPUF-R composites were prepared using steel slag (SS) and dimelamine pyrophosphate (DMPY) as flame retardants. The RPUF composites were characterized by thermogravimetric (TG), limiting oxygen index (LOI), cone calorimetry (CCT), and thermogravimetric infrared coupling (TG-FTIR). The results showed that the LOI of the RPUF-R composites with DMPY/SS loading all reached the combustible material level (22.0 vol%~27.0 vol%) and passed UL-94 V0. RPUF-3 with DMPY/SS system loading exhibited the lowest pHRR and THR values of 134.9 kW/m2 and 16.16 MJ/m2, which were 54.5% and 42.7% lower than those of unmodified RPUF, respectively. Additionally, PO· and PO2· free radicals produced by pyrolysis of DMPY could capture high energy free radicals, such as H·, O·, and OH·, produced by degradation of RPUF matrix, effectively blocking the free radical chain reaction of composite materials. The metal oxides in SS reacted with the polymetaphosphoric acid produced by the pyrolysis of DMPY in combustion. It covered the surface of the carbon layer, significantly insulating heat and mass transport in the combustion area, endowing RPUF composites with excellent fire performance. This work not only provides a novel strategy for the fabrication of high-performance RPUF composites, but also elucidates a method of utilizing metallurgical solid waste.

Transcriptomics and protein biomarkers reveal the detoxifying mechanisms of UV radiation for nebivolol toward zebrafish (Danio rerio) embryos/larvae.

Nebivolol (NEB), a ß-blocker frequently used to treat cardiovascular diseases, has been widely detected in aquatic environments, and can be degraded under exposure to UV radiation, leading to the formation of certain transformation products (UV-TPs). Thus, the toxic effects of NEB and its UV-TPs on aquatic organisms are of great importance for aquatic ecosystems. In the present study, the degradation pathway of NEB under UV radiation was investigated. Subsequently, zebrafish embryos/larvae were used to assess the median lethal concentration (LC50) of NEB, and to clarify the sub-lethal effects of NEB and its UV-TPs for the first time. It was found that UV radiation could reduce the toxic effects of NEB on the early development of zebrafish. Transcriptomic analysis identified the top 20 enriched Kyoto Encyclopedia of Genes and Genomes (KEGG) pathways in zebrafish larvae exposed to NEB, most of which were associated with the antioxidant, nervous, and immune systems. The number of differentially expressed genes (DEGs) in the pathways were reduced after UV radiation. Furthermore, the analysis of protein biomarkers, including CAT and GST (antioxidant response), AChE and ACh (neurotoxicity), CRP and LYS (immune response), revealed that NEB exposure reduced the activity of these biomarkers, whereas UV radiation could alleviate the effects. The present study provides initial insights into the mechanisms underlying toxic effects of NEB and the detoxification effects of UV radiation on the early development of zebrafish. It highlights the necessity of considering the toxicity of UV-TPs when evaluating the toxicity of emerging pollutants in aquatic systems.

Biogenic metal nanoparticles with microbes and their applications in water treatment: a review.

Due to their unique characteristics, nanomaterials are widely used in many applications including water treatment. They are usually synthesized via physiochemical methods mostly involving toxic chemicals and extreme conditions. Recently, the biogenic metal nanoparticles (Bio-Me-NPs) with microbes have triggered extensive exploration. Besides their environmental-friendly raw materials and ambient biosynthesis conditions, Bio-Me-NPs also exhibit the unique surface properties and crystalline structures, which could eliminate various contaminants from water. Recent findings in the synthesis, morphology, composition, and structure of Bio-Me-NPs have been reviewed here, with an emphasis on the metal elements of Fe, Mn, Pd, Au, and Ag and their composites which are synthesized by bacteria, fungi, and algae. Furthermore, the mechanisms of eliminating organic and inorganic contaminants with Bio-Me-NPs are elucidated in detail, including adsorption, oxidation, reduction, and catalysis. The scale-up applicability of Bio-Me-NPs is also discussed.

Toxicity of gabapentin-lactam on the early developmental stage of zebrafish (Danio rerio).

Gabapentin-lactam (GBP-L) is a transformation product (TP) of gabapentin (GBP), a widely used anti-epileptic pharmaceutical. Due to its high persistence, GBP-L has been frequently detected in the surface water. However, the effects of GBP-L on aquatic organisms have not been thoroughly investigated. In the present study, zebrafish (Danio rerio) embryos as a model organism were used to study the impacts of GBP-L in terms of embryos LC50, spontaneous movement at 24 hpf (hours post fertilization), heartbeat rates at 48 hpf, and body length at 72 hpf, with the concentrations of GBP-L down to 0.01 µg/L, covering its environmental concentrations. Various biomarkers from nervous, antioxidant and immune systems of zebrafish larvae were analyzed, including acetylcholinesterase, acetylcholine, dopamine, gamma-aminobutyric acid, superoxide dismutase, catalase, glutathione S-transferase, C reactive protein, and lysozyme, to assess its toxicity on these systems. RT-qPCR was then used to further verify the results and explain the toxicological mechanism at the gene level. The results demonstrated that GBP-L is much more toxic than its parent compound, and could lead to adverse impacts on the aquatic organisms even at every low concentrations.

Effective and simultaneous removal of organic/inorganic arsenic using polymer-based hydrated iron oxide adsorbent: Capacity evaluation and mechanism.

In this study, resin-based hydrated iron oxide (HFOR) composites were prepared and used as a functional adsorbent for the simultaneous removal of p-Arsanilic acid (p-ASA) and arsenate (As (V)). The effects of solution pH and coexisting substances on the adsorption of different arsenic species were also investigated. Results showed that the coexisting substances slightly affected the adsorption process of two arsenic species. Analysis of the adsorption behavior, isotherm equilibrium, and adsorption kinetics, as well as that results of the X-ray photoelectron spectroscopy, zeta potential, and other analytical methods revealed that the satisfactory adsorption performance of HFOR can be attributed to the electrostatic interactions induced by the positively charged groups and the coordination of the hydrated iron oxide nanoparticles, which exhibited excellent specific adsorption for both arsenic species. Moreover, HFOR showed high acid and alkali resistance and reusability, as well as a constant co-removal performance for different arsenic species in five consecutive operating cycles (55 mg As/g of As(V) and 18 mg/g of p-ASA). Results of continuous running fixed-bed column experiments confirmed that HFOR enabled excellent simultaneous adsorption for p-ASA and As(V).

Enhanced removal of tris(2-chloroethyl) phosphate using a resin-based nanocomposite hydrated iron oxide through a Fenton-like process: Capacity evaluation and pathways.

The effective removal of organophosphorus compounds (OPs) effectively from water environment remains an important but challenging task. In this study, a resin-based nanocomposite of hydrated iron oxide (HD1) was used as Fenton-like catalyst for effectively catalyzing the decomposition of hydrogen peroxide to degrade tris(2-chloroethyl) phosphate (TCEP). The results showed that HD1 was successfully prepared, which had great versatility, catalytic performance and adsorption capacity. Besides, HD1/H2O2 was capable of degrading TCEP completely with less than 0.2 mg/L of inorganic phosphorus (IP) in the effluent at the initial TCEP of 38 mg/L, pH = 4, H2O2 dosage of 20 mM, and the Kobs could result in about 1.0530 min-1 under identical conditions. More attractively, inorganic ions (i.e., Cl-, CO32-, SO42-, NO3-, HCO3-, Ca2+, and Mg2+) exhibited moderate effect on TCEP degradation. The negative effect of natural organic matters (NOM) (i.e., HA) on the degradation of TCEP was responsible for competition for the active oxygen species. Combined with electron paramagnetic resonance (EPR) spectra, X-ray photoelectron spectroscopy (XPS) and other analytical methods and radical quenching experiments, the possible removal process of TCEP was discussed, including two processes of oxidative degradation and immobilization of IP. Besides, hydroxyl radicals (•OH) was the key active species that contributed to TCEP degradation through hydroxylation-oxidation and C-O bond cracking, and specificity adsorption of HFO on IP was revealed. Furthermore, the results showed that HD1 had desirable acid and alkali resistance. In the continuous running fixed bed column experiment, HD1 showed a satisfactory performance in cycle operations. This work proposed a new enhanced process for removing TCEP in water environment by HD1/H2O2, and the multi-functional material, HD1 was promising in treatment of water containing organic phosphorus pollutants. This will be believed that this study will provide new ideas and new materials for the treatment of organic phosphorus-based organic pollutants, and lay the foundation for further deepening and expanding the application of adsorption resins in the field of water pollution control.

Efficient removal of Cu(II) organic complexes by polymer-supported, nanosized, and hydrated Fe(III) oxides through a Fenton-like process.

In this study, a polymer-supported, nanosized, and hydrated Fe(III) oxide (HFOD) was developed as a Fenton-like catalyst for the efficient removal of metal complexes in water. HFOD was prepared through the irreversible impregnation of hydrated iron(III) oxide (HFO) nanoparticles into cation exchange resin and characterized through X-ray photoelectron spectroscopy (XPS) and ion chromatography. The mechanism of Cu(II) ion removal and the degradation pathway of Cu(II)-citrate were analyzed through UV-vis spectrophotometry (UV) and liquid chromatography-mass spectrometry (LC-MS). The optimal removal rate of Cu(II) and TOC by a Fenton-like reaction at pH 4 and 40 mM H2O2 reached 81.6 % and 75.6 %, respectively. The removal efficiency of Cu(II)-citrate was remarkably affected with the addition of humic acid. However, the addition of competitive ions did not significantly reduce the removal rate of Cu(II)-citrate, thereby proving that the Fenton-like reaction by HFOD had a certain salt tolerance. Simultaneously, hydroxyl radical (•OH) was verified as the main free radical for Cu(II)-citrate degradation in a Fenton-like reaction, and citrate degradation was a process decarboxylation. HFOD recycling experiments and stability experiments showed that HFOD had high stability with good acid/alkali resistance and showed remarkable potential in the practical application of fixed-bed as catalysts for Fenton-like reactions.

Decomposition of complexed Pb(II) and subsequent adsorption of Pb(II) with yolk-shell Fe3O4@ hydrous zirconium oxide sphere.

Purification of water containing heavy metals that are complexed by organic chelating agents remains a challenging task. In this study, a yolk-shell Fe3O4@hydrous zirconium oxide (Zr(OH)x) sphere sphere (YHZOs) nanomaterial was evaluated for its ability to remove ethylene diamine tetraacetic acid complexed Pb2+ (Pb-EDTA) from aqueous solution. Specifically, it is hypothesized that upon addition of H2O2, the Fe3O4 core of YHZOs served as a Fenton-type catalyst that results in oxidation of the Pb-complexed EDTA, and the Zr(OH)x shell acted as an adsorbent, removing the released Pb2+ from solution. From an aqueous solution containing 0.1 mM Pb-EDTA at pH 5, 0.5 g/L YHZOs, and 20 mM H2O2, TOC reduction and Pb removal were determined to be 65.3% and 89.8%, respectively. HPLC-MS, IC and continuous flow analyzer results identified major intermediates of EDTA decay to be ethylenediaminetriacetate, (ED3A), ethylenediamine-N,N'-diacetate (ED2A), nitrilotriacetate (NTA), iminodiacetate (IDA), ethylenediamine (EDA), acetic acid, formic acid, oxalic acid, ammonia, and nitrate, with the first 5 species having some affinity to remain complexed to Pb2+. The adsorption of Pb2+ onto the Zr(OH)x shells was confirmed by scanning transmission electron microscopy (STEM) with mapping and X-ray photoelectron spectra (XPS). Moreover, the Pb2+-adsorbed YHZOs could be easily recovered due to their magnetic properties, with the Pb2+ rinsed from them at low pH. Indeed, reused for five cycles showed only minor capacity loss. These findings suggest that the removal of chelated Pb2+ from water, and presumably other heavy metals, by yolk-shell Fe3O4@Zr(OH)x may prove to be a useful technology for some contaminated waters.

Modified hydrous zirconium oxide/PAN nanofibers for efficient defluoridation from groundwater.

Fluoride contamination in groundwater is a worldwide problem that is related to human health. Zirconium-based adsorbents possess satisfactory selective defluoridation capacities. However, narrow efficiency pH range, easy aggregation and difficult separation are the main obstructions in practical application. In this study, the branched polyethyleneimine (bPEI) modified hydrous zirconium oxide (HZO)/polyacrylonitrile (PAN) nanofibers (NFs) are synthesized by immobilizing bPEI-HZO into PAN nanofibers via electrospinning. The resultant bPEI-HZO/PAN NFs exhibit a wide working pH range and an excellent adsorption capacity toward fluoride (67.51 mg·g-1) even at neutral condition, indicating non-negligible superiority in the practical application of groundwater defluoridation. This enhanced adsorption performance along with extended wider working pH range are ascribed to the optimization of the adsorbents from both composition and structure. Compositionally, the modification of bPEI improves the surface property of HZO, and thus increases fluoride capacity in alkaline groundwater. Structurally, electrospinning conquers the drawbacks of nano-adsorbents for both easy aggregation and difficult separation. In addition, the effect of co-existing ions was further investigated and the X-ray photoelectron spectroscopy (XPS) as well as fourier transform infrared spectrum (FTIR) measurements were used to clarify the fluoride adsorption mechanism. Furthermore, the dynamic adsorption and regeneration performance were accomplished through the fixed-bed column experiment. All the results indicated that bPEI-HZO/PAN NFs are promising materials for defluoridation from groundwater.

Developing new adsorptive membrane by modification of support layer with iron oxide microspheres for arsenic removal.

Arsenic-contaminated water has significant adverse impacts on human health and ecosystems. We developed a new adsorptive membrane by modifying the porous support layer of a phase inversion formed membrane for arsenic removal. Iron oxide (Fe3O4) microspheres were immobilized in the support layer of the membrane by reverse filtration, followed by dopamine polymerization. The prepared adsorptive membrane was compared with a virgin membrane without Fe3O4 microspheres and a Fe3O4 blended membrane in terms of membrane structures and separation performance. The adsorptive membrane prepared by our new method had comparable water permeability and rejection performance with the virgin membrane without Fe3O4 microspheres, but higher rejection performance and dynamic adsorption capacity than the membrane prepared by the conventional blending method. Both static and dynamic adsorption modes were used to evaluate the adsorption performance of the membranes. Our new adsorptive membrane also had excellent regeneration performance. After three regeneration cycles, the membrane was still capable of treating more than 2 tons of As-contaminated water/m2. The adsorptive membrane of 1 m2 could treat over 7 tons of water to the drinking water standard in terms of arsenic concentration during three regeneration cycles. Therefore, our adsorptive membrane may pave a new way for arsenic removal from water and ensuring drinking water security.

Iron-tannin-framework complex modified PES ultrafiltration membranes with enhanced filtration performance and fouling resistance.

In this work, an iron-tannin-framework (ITF) complex was introduced to a poly (ether sulfone) (PES) casting solution as a hydrophilic additive to fabricate ITF/PES ultrafiltration (UF) membranes via non-solvent-induced phase separation (NIPS). The structure and performance of the PES membranes with ITF concentrations ranging from 0 to 0.9wt.% were systematically investigated by scanning electron microscopy, water contact angle, permeability, protein rejection and fouling resistance measurements. The results indicate that the pore structure and surface properties of PES UF membranes can be regulated by incorporating the ITF complex. Compared with classical PES membranes, ITF/PES membranes were found to have an increased hydrophilicity and porosity and reduced surface pore size. Importantly, a simultaneous enhancement of permeability and separation performance was observed for the blend membranes, which indicates that the introduction of the ITF complex can break through the trade-off between permeability and selectivity of UF membranes.When the ITF content was 0.3wt.%, the permeability reached a maximum of 319.4(L/m2h) at 0.1MPa, which is 1.6 times higher than that of the classical PES membrane. Furthermore, the BSA rejection increased from 25.9% for the PES membrane to 95.9% for the enhanced membrane. In addition, the same membrane showed an improved fouling resistance (higher flux recovery and lower adhesion force) and stable hydrophilicity (unchanged after incubation in deionized water for 30days). The simple, green and cost-effective preparation process and the outstanding filtration performance highlight the potential of ITF/PES membranes for practical applications.

Dual-Functional Ultrafiltration Membrane for Simultaneous Removal of Multiple Pollutants with High Performance.

Simultaneous removal of multiple pollutants from aqueous solution with less energy consumption is crucial in water purification. Here, a novel concept of dual-functional ultrafiltration (DFUF) membrane is demonstrated by entrapment of nanostructured adsorbents into the finger-like pores of ultrafiltration (UF) membrane rather than in the membrane matrix in previous reports of blend membranes, resulting in an exceptionally high active content and simultaneous removal of multiple pollutants from water due to the dual functions of rejection and adsorption. As a demonstration, hollow porous Zr(OH)x nanospheres (HPZNs) were immobilized in poly(ether sulfone) (PES) UF membranes through polydopamine coating with a high content of 68.9 wt %. The decontamination capacity of DFUF membranes toward multiple model pollutants (colloidal gold, polyethylene glycol (PEG), Pb(II)) was evaluated against a blend membrane. Compared to the blend membrane, the DFUF membranes showed 2.1-fold increase in the effective treatment volume for the treatment of Pb(II) contaminated water from 100 ppb to below 10 ppb (WHO drinking water standard). Simultaneously, the DFUF membranes effectively removed the colloidal gold and PEG below instrument detection limit, however the blend membrane only achieved 97.6% and 96.8% rejection for colloidal gold and PEG, respectively. Moreover, the DFUF membranes showed negligible leakage of nanoadsorbents during testing; and the membrane can be easily regenerated and reused. This study sheds new light on the design of high performance multifunction membranes for drinking water purification.

Nanosized yolk-shell Fe3O4@Zr(OH)x spheres for efficient removal of Pb(II) from aqueous solution.

In this work, Fe3O4@Zr(OH)x yolk-shell nanospheres (YSNs) were synthesized via a two-step process and further examined as adsorbents for the removal of Pb(II). To understand the hollow structure on the adsorption properties of Pb(II), another adsorbent without hollow cavities, i.e., Fe3O4@SiO2@Zr(OH)x core-shell nanospheres (CSNs), was also prepared for comparison. The adsorption results showed that Fe3O4@Zr(OH)x YSNs exhibited 41.6% higher Pb(II) adsorption capacity as compared to that of Fe3O4@SiO2@Zr(OH)x CSNs. The isotherm was well fitted to Langmuir adsorption model with qmax value of 310.8 mg/g after normalized by the weight of Zr in Fe3O4@Zr(OH)x YSNs. Scanning transmission electron microscopy (STEM) mapping results revealed that the existence of cavities between Fe3O4 cores and Zr(OH)x shells is responsible for the improved adsorption performance. XPS analysis indicated the surface hydroxyl groups played a key role in the Pb(II) adsorption. The removal efficiency of Pb(II) was maintained above 90% in five consecutive adsorption-desorption cycles.

Synthesis of MCM-22 zeolite using rice husk as a silica source under varying-temperature conditions.

In this study, rice husk, an abundant agricultural byproduct, was utilized as an alternative silica source for the synthesis of MCM-22. The zeolite with high crystalline was synthesized using a three-stage varying-temperature hydrothermal method. The prepared silica and MCM-22 were characterized by X-ray diffraction, scanning electron microscopy, and transmission electron microscopy. The results showed that the duration required for zeolite crystallization was significantly decreased under varying-temperature conditions. The MCM-22 was in the form of thin platelet-like crystals, and no amorphous material existed in the framework of the MCM-22 after calcination and ammonium exchange. Cationic brilliant red 5GN, a basic dye used in the wool and blanket factories for fiber dyeing, was selected as the adsorptive to study the adsorption performance of the MCM-22. Adsorption experiments indicated that the maximum extent of adsorption was obtained at pH of 10, contact time of 60 min, and MCM-22 dose of 1.0 g/L. The adsorption kinetic has been described by first-order and pseudo-second-order models. It was observed that the rate of dye adsorption followed pseudo-second-order model.

Facile aqueous synthesis and electromagnetic properties of novel 3D urchin-like glass/Ni-Ni(3)P/Co(2)P(2)O(7) core/shell/shell composite hollow structures.

Novel 3D urchin-like glass/Ni-Ni(3)P/Co(2)P(2)O(7) core/shell/shell composite hollow structures are fabricated for the first time by controlled stepwise assembly of granular Ni-Ni(3)P alloy and ribbon-like Co(2)P(2)O(7) nanocrystals on hollow glass spheres in aqueous solutions at mild conditions. It is found that the shell structure and the overall morphology of the products can be tailored by properly tuning the annealing temperature. The as-obtained composite core/shell/shell products possess low density (ca. 1.18 g cm(-3)) and shape-dependent magnetic and microwave absorbing properties, and thus may have some promising applications in the fields of low-density magnetic materials, microwave absorbers, etc. Based on a series of contrast experiments, the probable formation mechanism of the core/shell/shell hierarchical structures is proposed. This work provides an additional strategy to prepare core/shell composite spheres with tailored shell morphology and electromagnetic properties.

Facile preparation and characterization of glass/Fe3O4 core/shell composite hollow spheres.

Novel glass/Fe3O4 core/shell composite hollow spheres with the shell layer assembled by multi-layered wafers were successfully synthesized by reduction of a glass/alpha-Fe2O3 precursor, which was obtained through a facile solvothermal process. The effects of some reaction parameters on the morphology of the shell layers and the magnetic properties of the products were investigated.

Facile synthesis of urchin-like glass/nickel core/shell composite hollow spheres.

Novel urchin-like core/shell composite hollow spheres were fabricated by assembly of nickel nanocones on the surface of hollow glass spheres; the effects of some reaction parameters on the morphology of the shell layers and the room temperature magnetic properties of the products were investigated.