Exothermic Peak Research Articles

A Comparative Study between Beeswax and Glycerol Monostearate for Food-Grade Oleogels.

With the aim to produce solid fats with a high percentage of unsaturated fatty acids, oleogels based on olive and peanut oil with different concentrations of beeswax (BW) and glycerol monostearate (GMS) as oleogelators were studied and compared. The critical oleogelator concentration for both BW and GMS was 3%. Thermal properties of the developed GMS-based oleogels pointed to a polymorphic structure, confirmed by the presence of two exothermic and endothermic peaks. All developed oleogels released less than 4% of oil, highlighting their high oil binding capacity. A morphology evaluation of oleogels showed platelet-like crystals, characterized by a cross-sectional length of 50 μm in BW-based oleogels and irregular clusters of needle-like crystals with a higher diameter in GMS-based oleogels. BW-based oleogels showed a solid fat content ranging from 1.16% to 2.27%, and no solid fat content was found at 37 °C. GMS-based oleogels reached slightly higher values of SFC that ranged from 1.58% to 2.97% at 25 °C and from 1.00% to 1.75% at 37 °C. Olive oil-based oleogels with GMS showed higher firmness compared with BW-based ones. The stronger structure network in olive oil/GMS-based oleogels provided a real physical barrier to oxidants, showing a high oxidation stability.

Influence of Al/Fe ratio on the hydration of brownmillerite in the presence of calcium sulfate

The brownmillerite, as an indispensable mineral phase in Portland cement, is actually a series of solid solution of Ca2(AlyFe(2–y))O5 (0 ≥ y ≤ 1.33). The varying values of y would significantly influence the hydration characteristic of brownmillerite. The hydration performance of brownmillerite where y = 0.9, 1.1 and 1.3 in Ca2(AlyFe(2–y))O5 in the presence of calcium sulfate, is deeply researched in this work. The brownmillerite Ca2(Al1.1Fe0.9)O5 and Ca2(Al1.3Fe0.7)O5 show a doublet of heat flow curve corresponding to formation of different amounts of ettringite while a single exothermic peak appears in Ca2(Al0.9Fe1.1)O5 due to generation of a layer of gel-like phases. Combining with density functional theory (DFT) calculations, it is concluded that the hydration reactivity of brownmillerite increases with reducing Al/Fe ratio. Fe is inclined to occupy octahedral sites as augment of Fe content in brownmillerite. Due to highly hydraulic activity of these sites, the lowest Al/Fe ratio of brownmillerite corresponds to highest hydration rate in first few hours. However, more iron hydroxide radicals aggregate in the surface of unhydrated brownmillerite and form a layer of iron-rich hydration products which would dramatically slow down the following hydration progress. In addition, this postponement to hydration will gradually recede with reduction of Fe content in brownmillerite. This finding provides a novel perspective on the understanding of Al/Fe ratio to the hydration performance of brownmillerite.

Influence of annealing temperature on microstructure, magnetic and electrical properties of Ce doped cobalt ferrite nanoparticles

Cerium doped cobalt ferrite nanoparticles with chemical formula CoFe1·9Ce0·1O4 were synthesized at different annealing temperatures (600, 700, 800, 900 and 1000C°) via sol-gel auto-combustion method. Thermal analysis for sample annealed at 1000C° was examined through differential scanning calorimetry (DSC) and revealed the presence of exothermic peak at around 500C° attributed to crystallization of prepared nanoferrites. Structural analysis such as phase formation, crystallinity and morphology was investigated by x-ray powder diffraction (XRD) and high resolution transmission electron microscope (HRTEM). XRD study revealed higher dependence of grain size growth with annealing temperatures as compared to lattice parameter. HRTEM investigation confirmed that grains have almost uniform morphology with some agglomeration and confirmed values of lattice parameters and grain sizes calculated from XRD data. Magnetic hysteresis was studied by vibrating sample magnetometer (VSM) at room temperature with an applied field of 20 kOe. The results showed an increase in saturation magnetization and remanent magnetization with increasing of annealing temperature, whereas a decline in coercivity was observed. Distribution of cations at tetrahedral and octahedral sites was investigated using x-ray and magnetic parameters which confirmed the mixed spinel ferrite nature of samples. Dielectric properties were carried out at room temperature in the range 0.1Hz–3.0 MHz. Both dielectric constant and ac conductivity decreased with rising of annealing temperature. Variation of dielectric loss tangent, impedance, electric modulus and relaxation time with temperature were also investigated. The effect of annealing temperature on the structure and its impact on magnetic and dielectric properties has been examined and discussed.

Effect of adaptive nanocrystalline behaviors on the cavitation erosion performance of Cu47.5Zr45.1Al7.4 bulk metallic glass

Amorphous alloys have attracted much attention in the field of cavitation erosion (CE) due to their good comprehensive properties. However, due to the special amorphous structures that are difficult to characterize, their micro-response behaviors and damage mechanisms during the CE process have not been well elucidated. In this paper, advanced techniques including focused ion beam (FIB) and transmission electron microscope (TEM) were used to comparatively study the microstructure evolution and volume loss rules of Cu47.5Zr45.1Al7.4 and Zr41.2Ti13.8Cu12.5Ni10Be22.5 bulk metallic glasses (BMG) under the action of cavitation load and cavitation heat to reveal their CE mechanisms. The results showed that the absence of small atoms in Cu47.5Zr45.1Al7.4 led to a large free volume, thereby compromising its hardness, modulus, and yield strength. However, this also made it more susceptible to shear banding, which in turn enhanced its energy absorption capabilities. Although Cu47.5Zr45.1Al7.4 had a higher glass transition temperature (Tg) and onset temperature of crystallization (Tx), as well as a wider supercooled liquid phase region (ΔTx), its exothermic peak was obviously pronounced and the transformation temperature range was significantly narrower. Therefore, it is more likely to adaptively form Cu-rich nanocrystals under the action of cavitation heat. Additionally, the larger free volume in the shear band was conducive to the diffusion of atoms and the occurrence of adaptive nanocrystallization behaviors in Cu47.5Zr45.1Al7.4. These nanocrystals were able to effectively force crack deflection, thereby dissipating impact energy and delaying the fatigue spallation of the material. Consequently, Cu47.5Zr45.1Al7.4 exhibited a far longer incubation period and a noticeably lower cumulative volume loss.

Calorimetric and kinetic evaluation of thermal stability and process safety in tert-butyl peroxy-2-ethylhexanoate and tert-butyl peroxybenzoate

This study evaluated the thermal stability and process safety of tert-butyl peroxybenzoate (TBPB), tert-butyl peroxy-2-ethylhexanoate (TBPO), and their mixture. Thermogravimetric (TG) analysis, differential scanning calorimetry (DSC), and accelerated rate calorimetry were used to elucidate the thermal behavior and breakdown kinetics. The TG results indicated moderate to low breakdown temperatures for all samples, demonstrating their thermal stability. DSC revealed onset temperatures for exothermic disintegration between 66.66 °C and 104.23 °C. The mixture had two distinct exothermic peaks, signifying the thermal decomposition of the mixture was such that the characteristic temperature and heat of the reaction were between those of TBPB and TBPO. Using Heat–Wait–Search methodology, the study identified thermal runaway exothermically. Under pseudoadiabatic conditions, the mixture exhibited greater increases in temperature and pressure—of 115.06 °C and 28.77 bar, respectively—compared with the individual compounds. To elucidate the apparent activation energy (Ea) and reaction kinetics, the study applied models developed by Arrhenius, Flynn-Wall-Ozawa, Friedman, Kissinger, and Starink. The Ea values obtained based on the TG, DSC, and ARC experiments were approximately 50.47, 98.19, and 99.71 kJ/mol, respectively, and were lower than those of TBPB and TBPO pure substances. The self-accelerating decomposition temperature of TBPB/TBPO decreased from 34 to 32 °C as the packaging of TBPB/TBPO was increased from 25 to 100 kg and was more than 10 °C lower than that of the individual substance. These findings offer a framework for evaluating the thermal risks associated with TBPB and TBPO, particularly when mixed. They contribute to the safe transit, storage, and handling of industrial organic peroxides, enriching our collective understanding of the stability and safety of these compounds.

Thermal behaviors and Decomposition Mechanism of PNIMMO with CL-20

To investigate the thermal decomposition mechanism between Poly(3-nitratomethyl-3- methyloxetane) (PNIMMO) and 2, 4, 6, 8, 10, 12-Hexanitrohexaazaisowurtzitane (CL-20), the thermal decomposition of PNIMMO, CL-20 and PNIMMO+CL-20 mixture under different conditions was studied using differential scanning calorimetry (DSC), thermogravimetric-differential scanning calorimetry-mass spectra-fourier transform infrared spectrometer (TG-DSC-MS/FTIR) and in-situ FTIR experiments. As a result, the exothermic peak temperature of the PNIMMO+CL-20 mixture shifts to lower values under both closed and open circumstances compared to CL-20. Different kinetic parameters and models were obtained for the three decomposition steps in the mixture. The first step follows the random chain scission model (L2) at α<0.5, and the phase boundary controlled reaction model (R3) at α>0.5. The second/third step is between the random chain scission model (L2) and the first-order reaction model (F1) at α<0.5, and conforms to the first-order reaction model (F1) at α>0.5. Thus, the decomposition of PNIMMO controls the initial speed, while the removal of the nitro group in CL-20 controls the later step. Combined with the analysis of gas products and condensed phase, PNIMMO speeds up the N—NO2 bond breaking in CL-20 but doesn’t alter its initial breakdown route.

Structural, thermal, surface, and electrical properties of Bi2O3 ceramics co–doped with Er–Ho–Tb rare earths

Face–centered cubic–Bi2O3 (δ–phase) material is a better ion conductor when compared to other types of solid electrolytes that have been declared in the literature due to its anion–defective crystal configuration, and hence it can be a promising solid electrolyte choice for intermediate temperature SOFC applications. In this research, Er–Ho–Tb co–doped Bi2O3 compounds were successfully synthesized by the solid–state reaction method and characterized using the XRD, TG & DTA, FPPT, and FE–SEM techniques. Apart from sample 4Er4Ho4Tb, each sample became stable with a cubic δ–phase at room temperature, according to XRD patterns. The DTA curves revealed no exothermic or endothermic peaks, implying a phase change in the constant heating cycle. The conductivity of Ho–rich compositions was higher than that of others, confirming the impact of cation polarizability on conductivity. In addition, at 700 °C, the sample 4Er8Ho4Tb with 1:2:1 content ratios had the highest conductivity of 0.29 S/cm. The porosity on the grain boundaries increased with doping, leading to higher grain boundary resistance, which could be responsible for the conductivity drop.

Comparison of the effects of carbon-based and inorganic nanomaterials on early cement hydration

This study delves into the impact of nanomaterials on early cement hydration, aiming to elucidate their mechanism of action. Four nanomaterials were selected, including carbon-based nanomaterials (multi-walled carbon nanotubes (CNT) and graphene oxide (GO)) and inorganic nanomaterials (nano-SiO2 and nano-CaCO3). Initially, the zeta potential was employed to examine nanomaterial adsorption on relevant ions in simulated solutions. Subsequently, SEM NMR, XRD, and TGA were utilized to assess the influence of different nanomaterials on hydration product morphology, content, and structure. Utilizing the Krstulovic-Dabic model, the hydration kinetics based on the heat of hydration in cement paste containing nanomaterials was simulated. Results revealed nanomaterials exhibited stronger Ca2+ ion adsorption than cement particles, with CNT and GO particles displaying weaker adsorption relative to SO42- ions. Conversely, nano-SiO2 and nano-CaCO3 particles exhibited a stronger adsorption capacity for Ca2+ ions than SO42- ions. This robust adsorption facilitated hydration product generation, yielding fine and regular C-S-H particles in carbon-based nanomaterial-containing cement pastes, contrasting with coarse and irregular particles in inorganic nanomaterial-containing pastes. Nanomaterial introduction increased polymerization and the average chain length of hydration products. Furthermore, it heightened exothermic peak intensity and total exothermic amount, while reducing the induction period and exothermic peak length. Hydration kinetics, simulated through the Krstulovic-Dabic model, aligned with the nucleation and growth (NG)-phase boundary reaction (I)-diffusion (D) process. In the NG stage, nanomaterials accelerated hydration by reducing reaction stages (n) and increasing the rate constant (K1'). In the I stage, hindered Ca2+ ion migration led to decreased K2', slowing hydration. Stage D witnessed a rapid decline in K3'.

The property, structure, and phase evolution of a binary cementitious material derived from sintering flue gas desulphurization ash and steel slag

The sintering flue gas desulphurization ash (DA) has emerged as the most significant solid waste, second only to granulated blast furnace slag and steel slag (SS), generated by steelmaking plants. However, its high CaSO3 content has rendered it challenging to recycle effectively. This study delves into the hydration characteristics of a low-carbon cementitious material composed of DA and SS, across different sulphur contents (3.14%, 6.28%, 9.42%, 12.56%) and water to binder (W/B) ratios (0.30, 0.35, 0.40, 0.45). The hydration products of the DASS composite cementitious material encompass C–S–H, C–A–S–H, Ca(OH)2, and K2Ca5(SO4)6·H2O. The setting time and fluidity exhibit a diminishing trend with increasing sulphur content. Notably, the hydration exothermic peak for pastes with 3.14% sulphur content emerges at 3 h, signifying a 2-h advancement compared to pure steel slag paste. The compressive strength of cured DASS paste gradually increases with sulphur content ranging from 3.14% to 9.42% over the initial 28 d, but experiences a decline with further sulphur content increases. A reduction in the W/B ratio significantly reduces setting time and achieves a two-fold increase in 28 d compressive strength. In DASS paste featuring a W/B ratio of 0.35 and a sulphur content of 9.42%, a substantial quantity of newly generated Ca(OH)2 is consumed through the pozzolanic reaction with steel slag after 60 d, leading to the production of more C–S–H to fill the interstitial voids between raw material particles. In conclusion, the recommended formulation for the DASS cementitious material should incorporate approximately 6%–9% sulphur supplied by DA, while greater mechanical properties can be attained by minimizing the W/B ratio. This innovative low-carbon cementitious material mitigates the impact of the massive amount of cement demand and promise an alternative to industrial waste management.

Thermal conversion of irradiated LLDPE waste into sustainable sponge-like compounds: a novel approach for efficient trace-level oil–water removal

The newest method for recycling waste linear low-density polyethylene (LLDPE) is the thermo-catalytic degradation technique known as catalytic pyrolysis. Typically, it is limited by 500–800 °C high temperatures. Catalytic pyrolysis releases toxins and forms harmful carbonized char. The current study is based on exposing wasted LLDPE to different gamma irradiation doses and then pyrolysis in castor oil (150–300 °C). The output product of Ir-(rLLDPE) is turned into another compound with a new structural architecture (sponge-like). SEM analysis confirms conversion, showing sponge-like spicules and layers. Ir-(rLLDPE) is sponge-like with a soft, malleable, absorbent texture. The DSC demonstrates altered thermal properties, with a melting point at 121 °C splitting into two peaks (endothermic at 117 °C and exothermic at 160 °C). The exothermic peaks signify the curing process of the sponge-like material. Ir-(rLLDPE) is assessed as an adsorbent for aqueous oils and solvents. The study examines irradiation doses, pyrolysis temperature, and time on adsorbent capacity. The oil removal obeys the Langmuir isotherm with monolayer adsorption, with a maximum adsorption capacity of 24.75 g/g of waste oil and 43 g/g of 1,1,2,2-tetrachloroethane. Squashing maintains adsorption after 20 reuses. Data shows sponges effectively clean marine oil spills and solvents.

Study on the hydration characteristics of steel slag cement

The direct use of stainless steel slag in cement presents potential weaknesses in terms of strength and the risk of cracking, which limits its large-scale utilization. Therefore, it was crucial to explore the use of stainless steel slag in clinker cement. In this study, the hydration characteristics of stainless steel slag cement (SS) and ordinary Portland cement (OPC) were compared and analyzed using isothermal calorimetry, X-ray diffraction (XRD), Fourier-transform infrared spectroscopy (FTIR), thermogravimetric analysis (TG-DTG), scanning electron microscopy (SEM), and heavy metal leaching tests. The study investigated the hydration heat, compressive strength at curing ages of 1d, 3d, 5d, 7d, and 28d, hydration products, and safety aspects of SS and OPC. Results showed that the optimum calcination temperature of stainless steel slag cement (SC) and Portland cement (PC) are 1350℃ and the holding time is 2 h. The clinker composition of the two is similar. The main minerals are dicalcium silicate (C2S), tricalcium silicate (C3S), tricalcium aluminate (C3A) and aluminum ferrite tetracalcium (C4AF). Compared with OPC, SS shows a delayed heat release peak during hydration. SS exhibited a delayed exothermic peak in the heat release during hydration compared to OPC. Furthermore, during the stable hydration period, SS produced more calcium aluminate-type solid solution, tightly encapsulating the crystal surface, and exhibited lower heat release. With an increase in curing age, the contents of acicular ettringite (AFt), C-S-H gel, and hexagonal calcium hydroxide (CH) gradually increased in both SS and OPC. Due to higher contents of C4AF, C3S, and C2S in SS, it produced more AFt and C-S-H than OPC. The compressive strength of both SS and OPC increased with curing age, reaching 55.4 MPa and 42.4 MPa at 28 days, meeting the requirements of the national standard (GB/T 21372-2008) in terms of initial and final setting times and f-CaO content. Additionally, heavy metal leaching and soluble Cr6+ tests indicated that their use is safe.

Impact of crystal polymorphism of rifaximin on dissolution behavior

IntroductionRifaximin is an intestinal antiseptic which has five (pseudo) polymorphs α, β, γ, δ and ε. These last (pseudo)polymorphs have different physicochemical properties. The objective of the study is to assess the impact of rifaximin polymorphism on its dissolution rate which could affect its bioavailability. Material and methodsThe analytical validation of dissolution assay method by UV–Visible spectrophotometry was carried out according to ICH Q2. The physicochemical characterization (solubility test, FTIR, DSC, XRD) was carried out on four active pharmaceutical ingredient (MP1, MP2, MP3, MP4). MP1 and MP2 were used by the manufacturer of generic brand 1 (G1) and MP3 and MP4 were used by the manufacturer of generic brand 2 (G2). The comparative in-vitro dissolution study was carried out on the leader brand (P), G1 and G2. ResultsThe four MPs were analyzed by XRD. The results of analysis showed that MP1 and MP4 were a mixture of α form and amorphous form. MP2 had an amorphous form and MP3 had a crystalline form β. The spectra of FTIR showed that the four MP had characteristics bands of rifaximin in the domain 4000-400 cm−1. The differences between the spectra of the four MPs were observed among the amorphous form (MP2), around the region 1800 to 1820 cm−1 which is attributed to the vibration of the CO group. An additional difference observed among the amorphous form (MP2) is around the region 1400 cm−1 which is attributed to the banding OH. The thermograms of MP1, MP2 and MP4 showed endothermic peaks which are probably attributed to the departure of water which indicate that MP1, MP2 and MP4 are pseudopolymoph (hydrate). For the four MPs, probably the melting points are interrupted by the phenomenon of phase transformations (Crystallization) which are reflected by exothermic peaks around 200°C–250 °C.Our results showed that the crystalline polymorphism of rifaximin influences its solubility. According to the results of the solubility test, the β crystal form of rifaximin (MP3) had the lowest solubility (3.47 μg/ml). MP2 had the highest solubility (8.35 μg/ml) and MP1 and MP4 had intermediate solubilities (5.47 μg/ml and 6.74 μg/ml). Comparative in vitro dissolution results showed that the dissolution profile of P was not similar to that of G1 and G2 (% dissolution (P)30min = 60%; % dissolution (G1) 30 min = 100% and % dissolution (G2) 30 min = 115%; f1(P versus G1) = 44; f1(P versus G2) = 61) in M1, while G1 and G2 had comparatively similar dissolution profiles (% dissolution (G1) 30 min = 100%; % dissolution (G1) 30 min = 110%; f1 (G1 versus G2) = 14) in M1. ConclusionThis study highlighted the impact of rifaximin polymorphism on its physico-chemical properties (crystal structure, thermal behavior, solubility) and on its dissolution behavior which could affect the rifaximin bioavailability.

Mechano-Synthesis, Structure, and Thermal and Magnetic Behaviors of the New Compound Mn1.2Co0.05Fe0.7P0.45Si0.5B0.05

The Mn1.2Co0.05Fe0.7P0.45Si0.5B0.05 compound has been systematically synthesized by mechanical alloying for 15 h, followed by annealing with two heating cycles at 1373 K for 2 h and 1073 K for 24 h. The powder that was milled for 15 h revealed the main hexagonal-Mn2P-type phase and the minor cubic-Mn3Fe2Si phase through X-ray diffraction examination. After annealing the same powder at 1373 K for 2 h and again at 1073 K for 24 h, the refined phase was the unique (Mn, Fe)2(P, Si) type with a hexagonal structure. For the mechanically alloyed powder, the final crystallite size was approximately 20 nm, and it rose to 95 nm during the annealing process. Further, a large amount of lattice microstrain was achieved as a result of high-energy milling (about 0.75%). Over the whole temperature range of 373 to 923 K, the thermal analysis showed several overlapping exothermic peaks, which indicated the improvement of the microstructure after the structural relaxation and reordering process. Moreover, the Curie temperature of the alloy was retrieved at approximately 675 K. According to an analysis of the magnetic properties, the mechanically alloyed powder exhibited an exceptional soft ferromagnetic state after 15 h of milling, and the annealed alloy showed superparamagnetic characteristics.

Effects of a novel carbon nanomaterial on hydration, mechanics, and chloride binding of cement composites

Nanomaterials have made significant progress in the field of cementitious materials, but suffer from primary problems of high cost and poor dispersity. Carbon dots (CDs) as a novel low-cost and high-dispersity nanomaterial preliminarily demonstrate their potential for cement. Nevertheless, it lacks systematic research on their effects on cement properties. For the first time, this work comprehensively investigates the effects of CDs on the hydration, mechanics, and chloride binding of cement composites. More importantly, the relevant mechanisms are revealed in depth. Specifically, cost-efficient ($0.013/g) and well-dispersed (dispersed in simulated concrete pore solution for 7 d) CDs are directly prepared by a facile microwave approach. The CDs dramatically retard the early hydration, improve later mechanical performance, and obviously enhance chloride binding. In detail, 0.2 wt% CDs reduce the second exothermic peak value by 75%, but improve the chloride binding capacity of paste by 51%. And 0.1 wt% CDs enhance the compressive/flexural strength of mortar by 17%/21%. Crucially, related influence mechanisms are uncovered. Namely, CDs create a protective barrier to retard hydration through the complexation of their abundant surface groups with Ca2+; While CDs exert the nucleation effect to boost the formation of C–S–H and Friedel's salt, thereby playing a positive impact on chloride binding; Meanwhile, CDs with suitable dosages carry out nucleation effect to counteract their air-entraining effect, thus improving later mechanical properties of cement composites. This study is expected to provide a novel low-cost and high-dispersity CDs nanomaterial to advance the development of high-performance cementitious materials.

Facile hydrothermally grown cobalt oxide (Co3O4) nanostructures and their electrochemical performances

Abstract In this study, pure cobalt oxide (Co3O4) nanoparticles were synthesized using a simple hydrothermal approach. The effect of the reducing agent and reaction temperatures of the prepared products were examined. Co3O4 is formed in the as-synthesized sample, at reaction temperature 190 °C was observed in the XRD pattern. The XPS survey scan spectrum showed the distinctive peaks of the Co and O elements and their valence states. FESEM and HRTEM revealed the particles as cubical in nature. Peak associated with the elements Co and O on the EDAX spectrum demonstrated the purity of the nanoparticles. Three electrode setups were used to measure the electrochemical properties of the synthesized nanoparticles. DTA curve corresponding exothermic peak at 225 °C and the crystallization of the final product was attributed for the third weight loss of 1.5 % in the temperature range of 280 °C to 450 °C. Formation of Co3O4 was confirmed by the observed XRD diffraction peaks at 2θ = 36.83°, 59.82°, and 65.30°, which correspond to h k l planes (311), (511) and (440), respectively. The high-resolution Co2p spectra showed two prominent spin-orbital peaks, 2p1/2 and 2p3/2, at 796.37 eV and 781.81 eV, respectively. The increase in temperature causes the particle size to grow ranges between 20 and 70 nm and the average particle size distribution in the TEM image is 42 nm. The integral area of the CV curve was measured during the CV measurement and as the as-prepared Co3O4 electrode displays specific capacitance values of 154, 126, 81, 65, and 49 Fg−1 at various scan rates of 10, 20, 50, 70, and 100 mVs−1, respectively.

Tailoring the performances of Ti-V-Al base shape memory alloys by defects engineering

In the present study, various defects such as dislocations were controlled in Ti-V-Al-based shape memory alloy by thermomechanical treatment and introduction of interstitial oxygen (O) atom to optimize the performances. The results revealed that the Ti-V-Al-O shape memory alloys gradually evolved from α” martensite phase to the β parent phase with increasing annealing temperature. Moreover, the degree of lattice distortion can be tailored by changing annealing temperatures. Upon the annealing temperature reached 900 °C, masses of ω precipitates and a nano-sized ordered domain, characteristic of strain glass, can be found. As a result of suppression effect of multiple varieties of defects to the martensitic transformation, no obvious endothermic and exothermic peaks were observed in differential scanning calorimetry curves. The yield strength and maximum tensile fracture strength of the Ti-V-Al-O shape memory alloy increased with the increase of annealing temperatures. Meanwhile, Ti-V-Al-O shape memory alloys annealed at 900 °C possessed superior strain recovery characteristics and corrosion resistance. The excellent performances in Ti-V-Al-O shape memory alloys annealed at 900 °C can be attributed to the formation nanoscale nanodomain.

PREFORMULATION STUDIES OF NIOSOMAL GEL CONTAINING DIPIVEFRIN HYDROCHLORIDE FOR ANTIGLAUCOMATIC ACTIVITY

Objective: The present study was focused on developing and characterizing niosomal gel formulations for ocular controlled delivery of an adrenergic agonist; dipivefrin HCl. In the present study, the pre-formulation studies are showed towards the development of Novel formulation. Methods: Preformulation studies of drug were carried out for identification (physical appearance, melting point and UV spectrophotometric analysis), solubility profile, lipophilicity (Partition Coefficient), compatibility studies by FTIR and thermal behavior by DSC. Results: The melting point of dipivefrin HCl was found to be 147.6±3 °C. The log P value was found to be 3.14±0.02, from which it can be interpreted that drug is highly lipophilic in nature. The scanned λmax were found to be 254 nm. No significant changes were found when FTIR spectra of the physical mixture compared with FTIR spectra of pure drug and excipients. This indicates absence of any possible interaction between the drug and excipients which confirms the identity and purity of drug. DSC thermogram of pure drug showed a sharp exothermic peak at 131.202 °C (area=1726.267 mJ, delta H=575.422 J/g), indicating the crystal melting point of the drug. Conclusion: These results suggest that the dipivefrin HCl serve as suitable candidate for ocular drug delivery system.

Influence of the Nano-Iron Oxide Adsorption-Enhanced Microstructured Charcoal Additives on the ANFO’s Properties

The article presents the results of the third research stage on the potential microstructured charcoal additives in ANFO. The charcoal powder was liquid adsorption-treated with Fe in various ratios. Adding MC-Fe to ANFO changed the exothermic peak’s position from ca. 280 °C to 250 °C due to lower activation energy, which influenced the kinetics of the reaction. Bruceton’s test indicated that the MC-Fe addition to ANFO resulted in ca. 10% lower initiation energy in comparison with pure ANFO. However, the energy level did not influence the potential applicability of the additives. The fumes analysis indicated a lower concentration of CO for all tested samples; however, the concentration of NOx rose. The thermodynamic calculations confirmed the experimental results, which could be explained by the increased positive oxygen balance. Moreover, all analyses showed that the most promising blasting properties referred to the ANFO sample containing the microstructured charcoal additive of a C:Fe ratio of 4:1. Therefore, further research will be dedicated to advanced studies between the chemical composition of this specific ANFO sample and its physicochemical and blasting properties.

Hydration characteristics and pollutant solidification mechanism of full solid waste electrolytic manganese residue super sulfate cement

In this study, electrolytic manganese residue (EMR) rich in soluble manganese, ammonia nitrogen, and sulfate was combined with carbide slag (CS) and granulated blast furnace slag (GBFS) to produce Full Solid Waste Electrolytic Manganese Residue Super Sulfate Cement (FWS-EMR-SSC). The compressive strength, hydration mechanism, microstructure, hydration kinetics, and pollutant solidification mechanism of FWS-EMR-SSC were investigated. The study revealed that the optimal ratio was 4% carbide slag, 40% EMR, and 56% GBFS, achieving a compressive strength of 38.34 MPa at 28 days. This was due to the release of OH- from carbide slag, causing EMR to dissolve large amounts of SO42- and Ca2+, while GBFS accelerated the release of Ca2+, Si2+, Al3+, leading to the formation of abundant AFt and C-(A)-S-H gel, providing strength to FWS-EMR-SSC. The heat release rate and cumulative heat of the FWS-EMR-SSC system were lower than Ordinary Portland Cement (OPC). Additionally, compared to OPC, the second exothermic peak rate was significantly reduced and delayed in the FWS-EMR-SSC system due to the exothermic release of gypsum, retarding effects, and pronounced generation of AFt. The simulation of FWS-EMR-SSC hydration kinetics using the Krstulović-Dabić model revealed that FWS-EMR-SSC underwent the NG-I-D process. Gypsum retarded the nucleation and crystal growth stages of NG, while AFt had a significant impact on the D diffusion stage. The C-(A)-S-H, AFt gel, and iron-manganese compounds (Fe2Mn(PO4)2(OH)2·(H2O)8, MnFe2O4) generated in the FWS-EMR-SSC system could undergo ion exchange and chemical precipitation with Mn2+. Meanwhile, NH3-N transformed into NH3 release, ensuring that the leaching toxicity of FWS-EMR-SSC met the Chinese standard limits of GB8978-1996 for wastewater discharge.

Development of a Sustainable Biobased Flame-Retardant Microcapsule and Its Flame-Retarding Mechanism on Asphalt Combustion.

To develop an efficient, sustainable, and eco-friendly biobased flame-retardant microcapsule suitable for the working environments of tunnel asphalt pavement and reveal its flame-retarding mechanism on asphalt combustion, microencapsulated amylopectin (MAMP) was first prepared using an in situ polymerization method. Changes in the basic properties of amylopectin (AMP) and its compatibility with asphalt after microencapsulation were studied. Then, the flame retarding efficiency and improvement effects of MAMP on the flame retardancy of asphalt were investigated. Results show that melamine formaldehyde (MF) resin is evenly coated on the AMP surface without changing the chemical composition of AMP, increasing the thermal stability of AMP and the compatibility between AMP and asphalt. MAMP reacts with ammonium polyphosphate (APP) to release a number of incombustible gases to delay asphalt combustion at early stages and subsequently dehydrates to form a stable starch-based charring layer to suppress heat and mass transfer during asphalt combustion, improving the fire safety of asphalt materials. The added 3% MAMP can reduce the total enthalpy value of all exothermic peaks of the 10% APP-modified asphalt by 43.6%. As a carbonization agent, MAMP produces a charring layer with higher heat capacity during asphalt combustion, exerting an excellent inhibition effect on heat release. This study provides a reference for the application of biobased materials in flame-retarded asphalt pavements.