Tb^(3+)-nucleic acid probe-based label-free and rapid detection of mercury pollution in food

Mercury is a threatening pollutant in food,herein,we developed a Tb^(3+)-nucleic acid probe-based label-free assay for mix-and-read,rapid detection of mercury pollution.The assay utilized the feature of light-up fluorescence of terbium ions(Tb^(3+))via binding with single-strand DNA.Mercury ion,Hg^(2+)induced thymine(T)-rich DNA strand to form a double-strand structure(T-Hg^(2+)-T),thus leading to fluorescence reduction.Based on the principle,Hg^(2+)can be quantified based on the fluorescence of Tb^(3+),the limit of detection was 0.0689μmol/L and the linear range was 0.1-6.0μmol/L.Due to the specificity of T-Hg^(2+)-T artificial base pair,the assay could distinguish Hg^(2+)from other metal ions.The recovery rate was ranged in 98.71%-101.34%for detecting mercury pollution in three food samples.The assay is low-cost,separation-free and mix-to-read,thus was a competitive tool for detection of mercury pollution to ensure food safety.

Understanding the catalytic performance and deactivation behaviour of second-promoter doped Pt/WO_(χ)/γ-Al_(2)O_(3) catalysts in the glycerol hydrogenolysis for selective and cleaner production of 1,3-propanediol

The selective aqueous-phase glycerol hydrogenolysis is a promising reaction to produce commercially useful 1,3-propanediol(1,3-PDO).The Pt-WOx bifunctional catalyst can catalyse the glycerol hydrogenol-ysis but the catalyst deactivation via sintering,metal leaching,and coking can predominantly occur in the aqueous phase reaction.In this work,the effect of reaction temperature,pressure and second promoter(Cu,Fe,Rh,Mn,Re,Ru,Ir,Sn,B,and P)on catalytic performance and deactivation behaviour of Pt/WOx/-Al2O3 was investigated.When doped with Rh,Mn,Re,Ru,Ir,B,and P,the second promoter boosts catalytic activity by promoting great dispersion of Pt on support and increasing Pt surface area.The increased Bronsted acid sites lead to selective synthesis of 1,3-PDO than 1,2-propanediol(1,2-PDO).The characterization studies of fresh and spent catalysts reveal that the main cause of catalyst deactivation is the Pt sintering,as interpreted based on XRD,CO chemisorption,and TEM analyses.The Pt sintering is affected depending on the second promoter that can either or reduce the interaction between Pt,WO_(χ)/γ and Al_(2)O_(3).As an electron acceptor of Pt in Pt/WO_(χ)/γ-Al_(2)O_(3),Re and Mn as second promoters resulted in increased Pt^(2+) on the catalytic surface,which strengthens the contact between Pt andγ-Al_(2)O_(3) and WO_(χ),resulting in a decrease in Pt sintering.The metal leaching and coking are not affected by the presence of second promoter.The catalyst modified with a second promoter possesses improved catalytic activity and 1,3-PDO production,however the stability continues to remain a challenge.The present work unrav-elled the determining parameters of catalytic activity and deactivation,thus providing a promising pro-tocol toward effective catalysts for glycerol hydrogenolysis.

Synthesis of crystalline g-C_(3)N_(4) with rock/molten salts for efficient photocatalysis and piezocatalysis

Graphitic carbon nitride(g-C_(3)N_(4))is emerging as a promising visible-light photocatalyst while the low crystallinity with sluggish charge separation/migration dynamics significantly restricts its practical applications.Currently,synthesizing highly crystalline g-C_(3)N_(4) with sufficient surface activities still remains challenging.Herein,different from using alkali molten salts which is commonly reported,we propose an approach for synthesis of highly crystalline g-C_(3)N_(4) with FeCl3/KCl rock/molten mixed salts.The rock salt can serve as the structure-directing template while molten salt provides the required liquid medium for re-condensation.Intriguingly,the synthesized photocatalyst showed further enhanced crystallinity and improved surface area along with high p/p*excitation compared with crystalline C_(3)N_(4) prepared from conventional molten-salt methods.These catalytically advantageous features lead to its superior photocatalytic and piezocatalytic activities with a high reactivity for overall water splitting that is not commonly reported for C_(3)N_(4).This work provides an effective strategy for structural optimization of organic semiconductor based materials and may inspire new ideas for the design of advanced photocatalysts.

A Novel High Temperature Apparatus for in situ Synchrotron X-ray Diffraction Studies of Molten Salt

This study demonstrates the design and application of a novel high temperature rotatory apparatus for insitu synchrotron X-ray diffraction studies of molten salts,facilitating investigation into the interaction between various structural materials and molten salts.The apparatus enables accurate detection of every phase change during hightemperature experiments,including strong reaction processes like corrosion.Molten salts,such as chlorides or fluo⁃rides,together with the structure materials,are inserted into either quartz or boron nitride capillaries,where X-ray diffraction pattern can be continuously collected,as the samples are heated to high temperature.The replacement re⁃action,when molten ZnCl2 are etching Ti3AlC2,can be clearly observed through changes in diffraction peak intensity as well as expansion in c-axis lattice parameter of the hexagonal matrix,due to the larger atomic number and ionic ra⁃dius of Zn2+.Furthermore,we investigated the high-temperature corrosion process when GH3535 alloy is in FLiNaK molten salt,and can help to optimize its stability for potential applications in molten salt reactor.Additionally,this high temperature apparatus is fully compatible with the combined usage of X-ray diffraction and Raman technique,providing both bulk and surface structural information.This high temperature apparatus has been open to users and is extensively used at BL14B1 beamline of the Shanghai Synchrotron Radiation Facility.

Chemically Mediated Interactions between Grapevine, Aphid, Ladybird, and Ant in the Context of Insect Chemical Ecology

This study simplifies the complex relationship among grapevine plants,aphids,ladybirds,and ants,which is essential for effective pest management and ecological balance.This study investigated the impact of aphid attacks and the presence of ants and ladybirds on the volatile compounds profile released into the chemosphere of the community consisting of the common vine Vitis vinifera,the aphid Aphis illinoisensis,the ladybird Cocci-nella undecimpunctata-and the ant Tapinoma magnum.This study aims to analyze the volatile compounds emitted by the grapevine and surrounding insects in response to these intricate interactions.The extraction of volatile organic compounds(VOCs)was carried out using closed-loop stripping(CLS)and then analyzed via gas chromatography-mass spectrometry(GC-MS)and principles coordinated analysis(PCA)was performed.The grapevine was exposed to different types and order of treatments,including non-infested,aphid-infested,aphid-infested with ant,aphid-infested with ladybird,and various combinations of ant and ladybird.After the aphid attack,the outcomes uncovered massive alterations in the volatile compound profiles.Infested grapevine displayed distinct emissions of germacrene D,an alcohol,and an alkene compared to non-infested plants.The characteristic VOC profile was the share of infested grapes in the presence of ants,with benzene derivatives and sesquiterpenes dominating the components.The coexistence of ladybirds with ants and aphids resulted in a dif-ferent volatile profile characterized by elevated levels of aldehydes,ketones,α-farnesene,and its hydroxy deriva-tive.It was concluded that the emission of VOCs into the chemosphere of the grapevine communities varied qualitatively and quantitatively depending on the level of the relationship complexity within each community in response to the infestation of grapevines by aphids,the presence of ladybirds as natural predators,and the presence of ant as protector.The grapevine’s status-dependent compounds can serve as indicators of infestation status and contribute to non-destructive early-stage diagnosis of the aphid.

A Review of Rechargeable Zinc-Air Batteries:Recent Progress and Future Perspectives

Zinc-air batteries(ZABs)are gaining attention as an ideal option for various applications requiring high-capacity batteries,such as portable electronics,electric vehicles,and renewable energy storage.ZABs offer advantages such as low environmental impact,enhanced safety compared to Li-ion batteries,and cost-effectiveness due to the abundance of zinc.However,early research faced challenges due to parasitic reactions at the zinc anode and slow oxygen redox kinetics.Recent advancements in restructuring the anode,utilizing alternative electrolytes,and developing bifunctional oxygen catalysts have significantly improved ZABs.Scientists have achieved battery reversibility over thousands of cycles,introduced new electrolytes,and achieved energy efficiency records surpassing 70%.Despite these achievements,there are challenges related to lower power density,shorter lifespan,and air electrode corrosion leading to performance degradation.This review paper discusses different battery configurations,and reaction mechanisms for electrically and mechanically rechargeable ZABs,and proposes remedies to enhance overall battery performance.The paper also explores recent advancements,applications,and the future prospects of electrically/mechanically rechargeable ZABs.

Coverage Dependent Dissociative Adsorption of HCl on Au(111)

Dissociative adsorption of HCl on Au(111)has become one of unsolved puzzles in surface chemistry.Despite tremendous efforts in the past years,varioustheoretical models still greatly overestimate the zero-coverage initial sticking probabilities(So).To find the origin of the large experiment-theory discrepancy,we have revisited the dissociative adsorption of HCl on Au(111)with a newly designed molecular beam-surface apparatus.The zero-coverage So derived from Cl-coverage measurements with varying HCl doses agree well with previous ones.However,we notice a sharp change of the coverage/dose slope with the HCl dosage at the low coverage regime,which may result in some uncertainties to the fitted So value.This seems consistent with a coverage-dependence of the dissociation barrier predicted by density functional theory at low Cl-coverages.Our results reveal the potential inconsistency of utilizing simulations with finite coverage to compare against experimental data with zero coverage in this system,and provide guidance for improving both experiment and theory in this regard.

Isolation of Microcrystalline Cellulose from Wood and Fabrication of Polylactic Acid(PLA)Based Green Biocomposites

An innovative microcrystalline cellulose(MCC)natural fibre powder-reinforced PLA biocomposite was investigated using the hand lay-up technique.The polymer matrix composite(PMC)samples were prepared by varying the weight percentages(wt.%)of both PLA matrix and MCC reinforcement:pure PLA/100:0,90:10,80:20,70:30,60:40 and 50:50 wt.%,respectively.From the results obtained,MCC powder,with its impressive aspect ratio,proved to be an ideal reinforcement for the PLA,exhibiting exceptional mechanical properties.It was evident that the 80:20 wt.%biocomposite sample exhibited the maximum improvement in the tensile,flexural,notched impact,compressive strength and hardness by 28.85%,20.00%,91.66%,21.53%and 35.82%,respectively compared to the pure PLA sample.Similarly,during the thermogravimetric analysis(TGA),the same 80:20 wt.%biocomposite sample showed a minimum weight loss of 20%at 400℃,among others.The morphological study using Field Emission Scanning Electron Microscopy(FE-SEM)revealed that the uniform distribution of cellulose reinforcement in the PLA matrix actively improved the mechanical properties of the biocomposites,especially the optimal 80:20 wt.%sample.Importantly,it was evident that the optimal PLA/cellulose biocomposite sample could be a suitable and alternative sustainable,environmentally friendly and biodegradable material for semi/structural applications,replacing synthetic and traditional components.

An Investigation into Forced Convection of a Nanofluid Flowing in a Rectangular Microchannel under the Influence of a Magnetic Field

In line with recent studies,where it has been shown that nanofluids containing graphene have a stronger capacity to boost the heat transfer coefficient with respect to ordinary nanofluids,experiments have been conducted using water with cobalt ferrite/graphene nanoparticles.In particular,a circular channel made of copper subjected to a constant heatflux has been considered.As nanoparticles are sensitive to the presence of a magneticfield,different conditions have been examined,allowing both the strength and the frequency of such afield to span relatively wide ranges and assuming different concentrations of nanoparticles.According to thefindings,the addition of nanoparticles to thefluid causes its rotation speed to increase by a factor of two,whereas ultraviolet radiation plays a negligible role.The amount of time required to attain the maximum rotation speed of the nanofluid and the Nusselt number have been measured under both constant and alternating magneticfields for a ferrofluid with a concentration of 0.5%and atflow Reynolds number of 550 and 1750.

Low-Density Microplastics in Recreational Parks of Al Ain, United Arab Emirates: Abundance, Composition, and Potential Effects on Soil Health

Microplastics (MPs) have been an emerging concern due to their harmful effects on the ecosystem and are ubiquitous in various habitats, from marine to terrestrial environments. However, studies on the presence of MPs in recreational areas are limited. One of the previous works has reported that urban recreational parks are considered “sinks” for plastic debris, including MPs. In this study, low-density MPs (LD-MPs) in soil samples collected from recreational parks of Al Ain, United Arab Emirates (UAE) were isolated by density flotation method. Results showed that these parks have varying levels of LD-MPs caused by various anthropogenic activities, such as sludge use and application of reclaimed water from wastewater treatment facilities in those areas. These plastic particles were isolated in 87% of the soil samples, with an average concentration of 1550 ± 340 MPs/kg. Predominantly, these comprised large LD-MPs (300 - 5000 μm), with red and blue being the most common colors. Fourier transform infrared (FTIR) spectroscopy identified possible synthetic polymers, including polyethylene and polypropylene. Additionally, a negative correlation was observed between LD-MP concentration and soil pH and moisture content, indicating potential adverse effects on soil health. These findings highlight the need for monitoring and managing microplastic pollution in urban recreational areas to mitigate its ecological impacts.

MXene@c-MWCNT Adhesive Silica Nanofiber Membranes Enhancing Electromagnetic Interference Shielding and Thermal Insulation Performance in Extreme Environments

A lightweight flexible thermally stable composite is fabricated by com-bining silica nanofiber membranes(SNM)with MXene@c-MWCNT hybrid film.The flexible SNM with outstanding thermal insulation are prepared from tetraethyl orthosilicate hydrolysis and condensation by electrospinning and high-temperature calcination;the MXene@c-MWCNT_(x:y)films are prepared by vacuum filtration tech-nology.In particular,the SNM and MXene@c-MWCNT_(6:4)as one unit layer(SMC_(1))are bonded together with 5 wt%polyvinyl alcohol(PVA)solution,which exhibits low thermal conductivity(0.066 W m^(-1)K^(-1))and good electromagnetic interference(EMI)shielding performance(average EMI SE_(T),37.8 dB).With the increase in func-tional unit layer,the overall thermal insulation performance of the whole composite film(SMC_(x))remains stable,and EMI shielding performance is greatly improved,especially for SMC_(3)with three unit layers,the average EMI SET is as high as 55.4 dB.In addition,the organic combination of rigid SNM and tough MXene@c-MWCNT_(6:4)makes SMC_(x)exhibit good mechanical tensile strength.Importantly,SMC_(x)exhibit stable EMI shielding and excellent thermal insulation even in extreme heat and cold environment.Therefore,this work provides a novel design idea and important reference value for EMI shielding and thermal insulation components used in extreme environmental protection equipment in the future.

Variability in Quantity and Salinity of Produced Water from an Oil Production in South Kuwait

Produced water (PW) is the largest waste stream in the oil and gas industry. Water remains trapped for millions of years in the reservoir with oil and gas. When a hydrocarbon reservoir is infiltrated by a production well, the produced fluids commonly contain water. The understanding of this water’s constituents and volumes is vital for the sustainable continuity of production operations, as PW has a number of negative impacts on the infrastructure integrity of the operation. On the other hand, PW can be an alternative source of irrigation water as well as of industrial salt. Interestingly, both the quantity as well as the quality of PW do not remain constant but can vary, both progressively and erratically, even over short periods of time. This paper discusses such a situation of variable PW in an oil and gas operation in the State of Kuwait.

Emerging trends of electrocatalytic technologies for renewable hydrogen energy from seawater:Recent advances,challenges,and techno-feasible assessment

Hydrogen has been regarded as a promising renewable and green energy source to meet energy needs and attain net-zero carbon emissions.The electrolysis of seawater to make hydrogen is one of the fascinating developments of the twenty-first century.This method uses abundant and relatively inexpensive seawater,as opposed to freshwater,which is rare and can be prohibitively expensive.In recent years,significant research and advancements have been made in direct seawater electrolysis technology for hydrogen production.However,producing highly effective and efficient electrocatalysts with long-term viability under harsh corrosive conditions remains a challenging and severe topic for large-scale seawater electrolysis technology.There is still a large accomplishment gap in understanding how to improve seawater electrolysis to increase hydrogen yields and prolong stability.It is,therefore,crucial to have a condensed knowledge of the tunable and inherent interactions between various electrocatalysts,covering electrolyzer types and paying particular attention to those with high efficiency,chemical stability,and conductivity.The extensive discussion is structured into a progression from noble metals to base metal compounds such as oxides,alloys,phosphides,chalcogenides,hydroxides,and nitrides,MXene-based complexes with a concise examination of hybrid electrocatalysts.In addition,proton exchange membranes,anion exchange membranes,alkaline water electrolyzers,and high-temperature water electrolyzers were potential contributors to seawater’s electrolysis.An extensive assessment of the techno-feasibility,economic insights,and future suggestions was done to commercialize the most efficient electrocatalytic systems for hydrogen production.This review is anticipated to provide academics,environmentalists,and industrial researchers with valuable ideas for constructing and modifying seawater-based electrocatalysts.

Solvent-free fabrication of broadband WS2 photodetectors on paper

Paper-based devices have attracted extensive attention due to the growing demand for disposable flexible electronics.Herein,we integrate semiconducting devices on cellulose paper substrate through a simple abrasion technique that yields high-performance photodetectors.A solvent-free WS_(2) film deposited on paper favors an effective electron-hole separation and hampers recombination.The as-prepared paper-based WS2 photodetectors exhibit a sensitive photoresponse over a wide spectral range spanning from ultraviolet(365 nm)to near-infrared(940 nm).Their responsivity value reaches up to~270 mA W^(−1) at 35 V under a power density of 35 mW cm^(−2).A high performance photodetector was achieved by controlling the environmental exposure as the ambient oxygen molecules were found to decrease the photoresponse and stability of the WS_(2) photodetector.Furthermore,we have built a spectrometer using such a paperbased WS_(2) device as the photodetecting component to illustrate its potential application.The present work could promote the development of cost-effective disposable photodetection devices.

Design of ZnSe-CoSe heterostructure decorated in hollow N-doped carbon nanocage with generous adsorption and catalysis sites for the reversibly fast kinetics of polysulfide conversion

Although lithium-sulfur batteries(Li SBs)are regarded as one of the most promising candidates for the next-generation energy storage system,the actual industrial application is hindered by the sluggish solid–liquid phase conversion kinetics,severe shuttle effect,and low sulfur loadings.Herein,a zeolitic imidazolate framework(ZIF)derived heterogeneous ZnSe-CoSe nanoparticles encapsulated in hollow N-doped carbon nanocage(ZnSe-CoSe-HNC)was designed by etching with tannic acid as a multifunctional electrocatalyst to boost the polysulfide conversion kinetics in LiSBs.The hollow structure in ZIF ensures large inner voids for sulfur and buffering volume expansions.Abundant exposed ZnSe-CoSe heterogeneous interfaces serve as bifunctional adsorption-catalytic centers to accelerate the conversion kinetics and alleviate the shuttle effect.Together with the highly conductive framework,the ZnSe-CoSeHNC/S cathode exhibits a high initial reversible capacity of 1305.3 m A h g-1at 0.2 C,high-rate capability,and reliable cycling stability under high sulfur loading and lean electrolyte(maintaining at 745 m A h g-1after 200 cycles with a high sulfur loading of 6.4 mg cm-2and a low electrolyte/sulfur ratio of 6μL mg^(-1)).Theoretical calculations have demonstrated the heterostructures of ZnSe-CoSe offer higher binding energy to lithium polysulfides than that of ZnSe or CoSe,facilitating the electron transfer to lithium polysulfides.This work provides a novel heterostructure with superior catalytic ability and hollow conductive architecture,paving the way for the practical application of functional sulfur electrodes.

Towards superior permeability and antifouling performance of sulfonated polyethersulfone ultrafiltration membranes modified with sulfopropyl methacrylate functionalized SBA-15

A non-solvent induced phase separation(NIPS)process was used to fabricate a series of sulfonated polyethersulfone(SPES)membranes blending with different concentrations of SBA-15-g-PSPA with the applications in the ultrafiltration(UF)process.SBA-15 was modified with 3-methacrylate-propyltrime thoxysilane(MPS)to form SBA-15-g-MPS.It was further modified with the charge tailorable polymer chains by reacting with 3-sulfopropyl methacrylate potassium salt.The nanoparticles were uniformly dispersed and finger-like channels were developed within the membrane.The adding of surface modified SBA-15-g-PSPA nanoparticles has significantly improved membrane water permeability,hydrophilicity,and antifouling properties.The pure water fluxes of the composite SPES membranes were significantly higher than the pristine SPES membrane.For the membrane containing 5%(mass)of SBA-15-g-PSPA(MSSPA5),the pure water flux was increased dramatically to 402.15 L
m^(-2)·h^(-1),which is ~1.5 times that of MSSPA0(268.0 L
m^(-2)·h^(-1)).The high flux rate was achieved with 3%(mass)of SBA-15 nanoparticles with retained high rejection ratio 98%for natural organic matter.The results indicate that the fashioned composite membrane comprising SBA-15-g-PSPA nanoparticles have a promising future in ultrafiltration applications.

Multicomponent synthesis and designing of tetrasubstituted imidazole compounds catalyzed via ionic-liquid for acid steel corrosion protection:Experimental exploration and theoretical calculations

Five new tetrasubstituted imidazoles were designed with outstanding yields(83%-92%) in the occurrence of ionic liquid-based-pyridinium as a catalyst. The constructions of all synthesized derivatives were established by spectral tools and their purities were verified using thin-layer chromatography(TLC), displaying single-spot. The performance of corrosion protection of the prepared imidazole derivatives was examined theoretically and practically for acid steel corrosion. The experimental study was conducted by electrochemical(electrochemical impedance spectroscopy(EIS) and Tafel polarization(PPS)) tools.The findings from the used approaches concluded that the synthesized compounds were wellorganized inhibitors with an efficiency of 90.7%-98.5% at 50℃ and 0.7 mmol·L^(-1). The Tafel polarization results indicate the protective action of the additives was under mixed-monitoring. The additive adsorption on the electrode interface performed as a distinguished aspect for protection. The surface exploration on the blank and protected metal was completed by field emission scanning electron microscopy(FESEM). Computational studies by Monte Carlo(MC) simulation and quantum chemical calculation(DFT)were related to practical findings. The corrosion protection adsorption mechanism was reinforced by the preferable fitted Langmuir isotherm model. All findings from the applied-inspected approaches alternately confirm each other.

Synergy mechanism of defect engineering in MoS_(2)/FeS_(2)/C heterostructure for high-performance sodium-ion battery

MoS_(2) is a promising anode material in sodium-ion battery technologies for possessing high theoretical capacity.However,the sluggish Na^(+) diffusion kinetics and low electronic conductivity hinder the promises.Herein,a unique MoS_(2)/FeS_(2)/C heterojunction with abundant defects and hollow structure(MFCHHS)was constructed.The synergy of defect engineering in MoS_(2),FeS_(2),and the carbon layer of MFCHHS with a larger specific surface area provides multiple storage sites of Na^(+)corresponding to the surface-controlled process.The MoS_(2)/FeS_(2)/C heterostructure and rich defects in MoS_(2) and carbon layer lower the Na^(+) diffusion energy barrier.Additionally,the construction of MoS_(2)/FeS_(2) heterojunction promotes electron transfer at the interface,accompanying with excellent conductivity of the carbon layer to facilitate reversible electrochemical reactions.The abundant defects and mismatches at the interface of MoS_(2)/FeS_(2) and MoS_(2)/C heterojunctions could relieve lattice stress and volume change sequentially.As a result,the MFCHHS anode exhibits the high capacity of 613.1 mA h g^(-1)at 0.5 A g^(-1) and 306.1 mA h g^(-1) at 20 A g^(-1).The capacity retention of 85.0%after 1400 cycles at 5.0 A g^(-1) is achieved.The density functional theory(DFT)calculation and in situ transmission electron microscope(TEM),Raman,ex-situ X-ray photon spectroscopy(XPS)studies confirm the low volume change during intercalation/deintercalation process and the efficient Na^(+)storage in the layered structure of MoS_(2) and carbon layer,as well as the defects and heterostructures in MFCHHS.We believe this work could provide an inspiration for constructing heterojunction with abundant defects to foster fast electron and Na^(+) diffusion kinetics,resulting in excellent rate capability and cycling stability.

Fabrication and Characterization of Lanthanide-TiO2 Nanotube Composites

Titanium dioxide (TiO2) doped with neodymium (Nd) and/or Gadolinium (Gd) rare-earth elements were fabricated into nanotubes via the hydrothermal method in a KOH solution and in-situ doping. Titanium dioxide nanotubes (TNTs) and in-situ Nd-doped and/or Gd-doped TNTs were characterized with transmission and scanning electron microscopy, energy-dispersive X-ray analysis, X-ray diffraction, Raman spectroscopy, and Fourier-transform infrared spectroscopy. Morphologies indicated a network of aggregated nanotubes. The phase and composition analyses revealed that the lanthanide TNTs had anatase phases with Nd and/or Gd nanoparticles in the TNT lattice. The nanoparticles were uniformly deposited on the surface because of hydroxyl groups on the TNT surfaces, resulting in a very high loading density. The outer diameter and the length of the TNTs increased with doping. The mechanisms for the formation of multiwall TNTs are discussed.

An Evaluation to the Performance of Evacuated Tube Solar Heaters for Arid and Hot Areas

Solar energy applications could be the best alternative to the conventional fuels for the purposes of domestic,water and space heating and some industries in the sunny,arid,and hot areas.In the present study,the performance of an evacuated tube solar heater for water heating for months of February and March was experimentally investigated.This was performed in a hot and arid area(Nasiriya City,South of Iraq).A solar heater with ten evacuated tube solar collectors with a capacity of 100 liter was used in the experiments.Each evacuated tube had a length of 1.8m with an outside diameter of 8 cm.It was observed that for the two selected months,water temperature of the solar heater reached a maximum more than 70°C during sunny days with no heat extraction from the tank of the solar heater.Moreover,heat was extracted from the solar collector with four different flowrates 0.5,0.75,1,and 1.25 l/min,respectively.The results showed that temperature of the solar heater behaved differently from the static situation.When the heat extraction begun,there was a gradual and noticeable decrease in the water temperature of the heater.The observed decrease was slight with the lowest flowrate(0.25 l/m)and becomes sharp with the highest flowrate(1.25 l/min).However,water temperature of the solar heater remained higher than 40°C for the investigated flowrates except the case of 1.25 l/min.The results showed that evacuated tube solar heater can work efficiently in arid and hot areas in winter and spring seasons when the conditions of solar radiation are suitable.