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Synergism during the co-pyrolysis of microalgae (CC), municipal solid waste (MSW), and their blends (CC/MSW) (w/w %), 25/75 (CM-1), 50/50 (CM-2), and 75/25 (CM-3), was evaluated based on thermal decomposition pattern, evolved gases, rate and extent of thermal decomposition, and kinetic parameters. Three stages of devolatilization attributed to dehydration, devolatilization of major structural compounds of biomass and decomposition of solid residues were noticed during the co-pyrolysis of biomass samples. The main pyrolysis stages for CC, MSW, CM-1, CM-2 and CM-3 were 175–520, 151-523, 164-504,168-510, 160–501 °C, respectively. Microalgae, CC, appeared to be thermally resistant, while MSW is noticed to be thermally sensitive. The kinetics analysis was studied by deconvoluting the DTG profile into independent stages, followed by application of isoconversional methods to evaluate the activation energy and the pre-exponential factor. Furthermore, the reaction mechanism of each stage was determined by using the master plot method. The semi-quantitative method was used to evaluate the evolved gases and CO, CO2 and H2 were noticed to be the dominant gas species. The obtained thermal and kinetic data for co-pyrolysis of microalgae and MSW can serve are basis for scale-up and reactor design of pyrolysis process for similar kind of waste streams.

Strongly balanced repeated measurements designs are useful to balance out the residual effects. These designs are widely used in medicine, pharmacology, animal sciences and psychology. The situations where minimal strongly balanced repeated measurements designs cannot be constructed, strongly partially-balanced repeated measurements designs are preferred. This paper deals with the construction of circular strongly partially-balanced repeated measurements designs through method of cyclic shifts. MSC: 05B05, 62K10, 62K05, Keywords: Circular strongly balanced repeated measurements designs, Circular strongly partially-balanced repeated measurements designs, Method of cyclic shifts, Repeated measurements designs, Residual effects

Pakistan is experiencing a slow uptake of grid-tied residential PV generation Systems (GTRPVGS); despite of steep fall in PV module price, higher solar irradiation and enactment of Net-metering by the Government. This slow uptake is attributed to the lack of awareness of four major stakeholders, namely the house hold, utility, financier and the policy-maker. This paper presents a coherent framework that addresses the concerns of the stakeholders using four country-specific parameters i.e. the local solar irradiation, PV system costs, borrowing and discount rates, and electricity tariffs; to compute NPV, IRR, payback period and levelized cost of electricity (LCOE). Assuming net-metering, we model the economic payoffs on self-consumption and sale of PV electricity at varying net-metering rates, system sizes, load-to-generation profiles, borrowing and discount rates. Findings suggest economic competitiveness of PV electricity, with an IRR and payback averaging around 28% and 5 years respectively. Moreover, the LCOE is also found to be significantly lower than the retail rates. The findings inform the household and financier on the economic yield; utility on efficient tariff setting; and government on sustainable policy design. Finally, we argue that GTRPVGS bears huge potential for Pakistan, suffering from energy deficit, unsustainable cost, transmission losses and environmental hazards.

The efficient conversion of solid carbon fuels into energy by reducing the emission of harmful gases is important for clean environment. In this regards, direct carbon fuel cell (DCFC) is a system that converts solid carbon directly into electrical energy with high thermodynamic efficiency (100%), system efficiency of 80% and half emission of gases compared to conventional coal power plants. This can generate electricity from any carbonaceous fuel such as charcoal, carbon black, carbon fiber, graphite, lignite, bituminous coal and waste materials. In this paper, ternary carbonate-samarium doped ceria (LNK-SDC) electrolyte has been synthesized via co-precipitation technique, while LiNiCuZnFeO (LNCZFO) electrode has been prepared using solid state reaction method. Due to significant ionic conductivity of electrolyte LNK-SDC, it is used in DCFC. Three types of solid carbon (lignite, bituminous, sub-bituminous) are used as fuel to generate power. The X-ray diffraction confirmed the cubic crystalline structure of samarium doped ceria, whereas XRD pattern of LNCZFO showed its composite structure. The proximate and ultimate coal analysis showed that fuel (carbon) with higher carbon content and lower ash content was promising fuel for DCFC. The measured ionic conductivity of LNK-SDC is 0.0998 Scm−1 and electronic conductivity of LNCZFO is 10.1 Scm−1 at 700 °C, respectively. A maximum power density of 58 mWcm−2 is obtained using sub-bituminous fuel.

Neighbor balanced designs are useful to balance out the neighbor effects in field of agriculture, serology, agro forestry, industry, etc. In most of the agriculture experiments blocks are formed in a line and therefore, neighbor balanced designs are required in linear blocks. In this article some classes of first order neighbor balanced designs are presented in linear blocks of size three and four. A method to construct the second order neighbor balanced designs through two minimal first order neighbor balanced designs in linear binary blocks of size three is also developed here. Keywords: Neighbor effects, Linear blocks, First order neighbor balanced designs, Second order neighbor balanced designs, Minimal designs, MSC (2000): 05B05, 62K10

The present study investigates the optimization of HNO3 leaching of Cu from old AMD Athlon processors under the effect of nitric acid concentration (%), temperature (°C) and ultrasonic power (W). The optimization study is carried out using response surface methodology with central composite rotatable design (CCRD). The ANOVA study concludes that the second degree polynomial model is fitted well to the fifteen experimental runs based on p-value (0.003), R2 (0.97) and Adj-R2 (0.914). The study shows that the temperature is the most significant process variable to the leaching concentration of Cu followed by nitric acid concentration. However, ultrasound power shows no significant impact on the leaching concentration. The optimum conditions were found to be 20% nitric acid concentration, 48.89 °C temperature and 5.52 W ultrasound power for attaining maximum concentration of 97.916 mg/l for Cu leaching in solution.

Neighbor balanced designs are robust to neighbor effects, therefore, these designs are used to balance out the neighbor effects. If a large number of experimental material is required for combinatorial neighbor balance then partially neighbor balanced designs should be recommended. In this study, some useful generators are developed to obtain the partially neighbor balanced designs in linear blocks of sizes 3–7. Keywords: Linear block, Neighbor effects, Neighbor balanced designs, Partially neighbor balanced designs

Temperature is probably the most important outdoor variable that affects the photovoltaic performance of the dye sensitized solar cells (DSSCs). Overall stability of DSSCs depends on the properties of charge mediator (electrolyte) between photoanode and counter electrode. The liquid electrolytes show high power efficiency owing to their high dielectric constants to dissolve many ionic salts and additives. However, they may limit the outdoor applications in high temperature region, due to their low boiling points (highly volatile). The objective of this study is to highlight the prospects of solid state dye-sensitized solar cells and its benefit in higher temperature environment. The current review is comprised of four sections. In the first section (introduction), the effect of temperature on the conventional and solid-sate DSSCs is briefly described. In the second section, the mechanism of solid-state DSSCs is explained. Third section we covered recent advances in ss-DSSCs in detail. Finally, the scope of DSSCs in high temperature environment critically analyzed in section four.

With rapidly growing industrial development worldwide, the need for a new class of nanoparticles and techniques for treating wastewater remains a major concern to protect the environment. Layered double hydroxides and particularly LDH-containing hybrids are emerging as potential nano-sized adsorbents for water treatment. Recent studies have demonstrated LDH-containing hybrids as promising multifunctional materials for potential utilization in various applications such as, photo-catalysis, energy storage, nanocomposites and water purification. This article reviews the recent applications of LDH-containing hybrids as adsorbents for water remediation. The maximum adsorption capacities of various toxic heavy metals and dyes on different LDH hybrids were reported as 483 mg/g for Pb2 +, 95 mg/g for Cd2 +, 181 mg/g for Cu2 +, 649 mg/g for Cr6 +, 180 mg/g As5 +, 813 mg/g for Hg2 +, 450 for Ag+, 277 mg/g for U6 +, 1062 mg/g for methyl orange, 185 mg/g for methylene blue, and 1250 mg/g for Congo red, which is comparatively higher than other commercial adsorbents. This review discusses the adsorption performance of manifold LDH-containing hybrids for treating various pollutants such as heavy metals and dyes. The mechanisms of interaction of LDH-containing hybrids with pollutants and the influence of key adsorption parameters such as pH, contact time, adsorbent dose and temperature have been comprehensively discussed. Moreover, the regeneration potential and reuse of spent LDH-containing hybrids and its toxicity effects have also been reviewed.

Meeting the ever-increasing global energy demands is one of the serious challenges of the 21st century. It is estimated that about 80% of the global energy demand is supplied by the fossil fuels which in turn promote global warming upon their consumption and cause harmful effects on the environment. One of the major causes of global warming is the excessive accumulation of CO2 into the atmosphere. An important way for mitigating the excessive amount of CO2 is to transform it into the hydrocarbons (HC) fuels. In this article, we have addressed various issues aroused by CO2 emission and their possible solutions. Various routes for CO2 upgrading into HC fuels are comprehensively elaborated. Furthermore, we have focused on the heterogeneous catalysis for CO2 conversion to value-added HC fuels by utilizing zeolite and non-zeolite based catalysts. The role of noble metals-based catalysts (such as Rh and Ru) and the transition metals containing Ni-species supported on zeolites in CO2 conversion to (HC) fuels is discussed. In addition, the role of Fe- and MOFs based non-zeolite based catalysts for the generation of HC fuels via the CO2 hydrogenation is also discussed. Finally, this review article highlights the prospective areas for research and technology advances. In brief, this review is focused on zeolite and non-zeolite based catalytic route for CO2 to HC fuel and reflects its importance for both the industries and academia.

A hybrid nanomaterial, low crystallinity graphite-layered double hydroxide, was used as a support for zirconocene catalyst. The hybrid nanomaterial graphite-NiAl layered double hydroxides (G/LDH) were synthesized by the co-precipitation method. The synthesized nanomaterial was used as a support for zirconocene catalyst. The polymerization reactions were carried out for ethylene polymerization. The synthesized polyethylene (PE) was analyzed by using differential scanning calorimetry (DSC), Crystallization analysis & fractionation (CRYSTAF), and thermogravimetric analysis for its thermal and microstructural characteristics. The crystallization kinetics were studied by the Ozawa and combined Ozawa and Avrami models. It was found that the presence of G/LDH from the catalyst support nucleated the PE crystallization and shifted the crystallization onset temperature to a higher value. However, the overall crystallization rate was slowed by the presence of the nanomaterial due to growth impingement. Moreover, the PE synthesized by G/LDH supported catalyst possessed higher thermal stability than PE synthesized by unsupported zirconocene catalyst. The integral isoconversional method was used to evaluate the activation energy of thermal degradation and crystallization kinetics. The degradation mechanism was validated by the application of the integral master plot technique. The degradation mechanism of neat PE resembled phase boundary controlled mechanism second and third-order, i.e. (R2, R3), while PE synthesized by G/LDH supported catalyst had a shift in degradation mechanism from (R2, R3) to a diffusion-limited mechanism at the later stages of degradation.

Hybrids of graphene (G) and layered double hydroxides (LDHs) are promising nanomaterials due to their versatile properties and the large number of composition/preparation variables available for fine-tuning. Several techniques are available for the synthesis of these novel G/LDHs nanocomposites. This article reviews the recent developments in their synthesis and applications in the oxygen evolution reaction, supercapacitors, hybrid sensors, adsorption, catalysis, water purification, and flame retardant materials.

Poly (styrene-co-methyl methacrylate) [P(st-mma)] composite containing 0.1 wt% modified graphene (MG) was prepared via melt blending. MG was prepared by oxidation method using nitric acid. The P(st-mma) and P(st-mma)MG composite were irradiated using microwave radiation. The degradation mechanism and thermal stability of the irradiated and un-irradiated samples was analyzed by TGA. P(st-mma)MG showed high thermal stability. The average activation energy of thermal degradation was found to be 200 kJ/mol for P(st-mma), 214 kJ/mol for P(st-mma)MG. The activation energy was highest for 10 min irradiated nanocomposites indicating an improvement in stability. The degradation mechanism was investigated by comparing the master plots constructed using the experimental data with theoretical master plots of various kinetic models. The thermal degradation of P(st-mma) and P(st-mma)MG composite before and after irradiation governs the random scission mechanism. SEM and TEM micrographs showed improved interactions and degradation of composites after 10 min and 20 min irradiation respectively.

High density polyethylene/graphene nanocomposites were synthesized via in-situ polymerization technique using metallocene catalyst and methylaluminoxane (MAO) as co-catalyst. The non-isothermal crystallization of the nanocomposites was studied using differential scanning calorimetry (DSC). Modified Avrami, Ozawa and the model proposed by Mo et al. were applied in the analysis. The activation energy (ΔE) was calculated using the iso-conversional method proposed by Vyazovkin. The effect of degree of transformation and temperature on ΔE was analyzed. It was found that graphene nucleates the crystallization of HDPE by lowering ΔE as well as increasing the crystallization onset temperature (Ton). However, at later stages of crystallization, excess amount of graphene hinder the crystal growth rate thereby retarding overall rate of crystallization, observed from increase of t1/2 and degree of super cooling.

Neighbor balanced designs are used to remove the neighbor effects but most of these designs require a large number of blocks. To neutralize the neighbor effects in such situations, GN2-designs are most desirable. This article deals with the (i) refinement of some series of GN2-designs constructed by Zafaryab et al. (2010) and (ii) construction of some new series of GN2-designs in circular blocks of equal size.

Neighbor designs have their own importance in the experiments to remove the neighbor effects where the performance of a treatment is affected by the treatments applied to its adjacent plots. If each pair of distinct treatments appears exactly once as neighbors, neighbor designs are called minimal. Most of the neighbor designs require a large number of blocks of equal sizes. In this situation minimal neighbor designs in unequal block sizes are preferred to reduce the experimental material. In this article some series are presented to construct minimal neighbor designs in circular blocks of unequal sizes.

Generalized neighbor designs relax the condition of constancy on the number of times two treatments occur as neighbors in a design. In this paper, we constructed generalized neighbor designs in circular blocks of equal size. Catalogs of these designs for block size 5, 7 and 9 are also compiled. All the designs given here are binary.