The biorefinery of lignocellulosic wastes allows decreasing the emission of greenhouse gases by the introduction of eco-friendly alternatives such as biofuels and bioproducts, reducing the cost of waste disposal and overcoming the environmental problems related to the production of first-generation biofuels by dedicated cultures. The enzymatic hydrolysis of waste biomasses is one of the crucial steps of the biorefinery process; it is aimed at obtaining fermentable sugars starting from the complex carbohydrates (cellulose and hemicellulose). Among the biomasses classified as lignocellulosic wastes, Coffee Silverskin (CSS) is one of the most abundant residues from the roasting process of the coffee industry. CSS is the external layer protecting the coffee beans and is composed almost by carbohydrates (?40% w/w) and lignin (?30% w/w). The present contribution is part of a study focused on the characterization of enzymatic hydrolysis kinetics of real wastes biomass. In particular, the initial rate of glucose production has been characterized in a bench scale stirred reactor (0.5 L) using a commercial cellulase cocktail (Cellic® CTec2). The experimental procedure included an enzyme adsorption step on CSS followed by the hydrolysis step. Initial glucose production rate was assessed at 10 and 15 min at different stirring rates, the results shows that the initial rate increased at increasing stirring speed with a more evident variability than that observed for initial hydrolysis rates assessed after 60 min in previous work (Procentese et al., 2020). This result agrees with the literature (Hou et al., 2016) because is likely due to the early changes in morphology and size of biomass granules occurring during the first hour of enzymatic conversion. Further investigation of the effect of biomass morphology and size on the initial rate of glucose production has been carried out by laser scatter analysis of particle size and scanning electron microscopy.

The use of waste lignocellulose feedstock for sugar-based biorefineries is attracting the interest of the scientific and industrial communities. The aim is to develop efficient sustainable processes to produce fuels and chemicals via the biotechnological route. However, the rational design of processes aimed at fermentable sugar recovery from lignocellulosic wastes asks for reliable quantitative data of a wide spectrum of biomass. Waste biomasses from food industries are among the most studied potential carbon sources. In the present study, the kinetics of enzymatic hydrolysis of coffee silverskin has been characterized. Coffee silverskin is one of the most abundant fractions of the coffee industry waste and it has been already used for saccharification purposes. The experimental investigation provided kinetic parameters of a semi-mechanistic model of glucose production rate from coffee silverskin catalyzed by a commercial cellulase cocktail. In addition, the adsorption of the enzymes on the solid biomass substrate has been characterized according to a Langmuir type model. The effect of enzymes adsorption on cellulose conversion and the process dynamics have been highlighted by validation tests. The optimization of biocatalyst use has been provided via a two-step hydrolysis procedure. The developed procedure can be successfully applied in the future to several biomasses to describe a wide range of possible substrates.

The calcium-looping process, relying on the reversible calcination/carbonation of CaCO3, is one of the most promising solution to perform thermochemical energy storage (TCES) for concentrating solar power (CSP) plants. Indeed, CaO precursors such as limestone can rely on the high energy density, low cost, large availability and nontoxicity. In this work, the study of the sound-assisted carbonation of fine CaO particles (< 50 mu m) for TCES-CSP has been furthered. In particular, a kinetic study has been performed to analyze the effect of the particular carbonation conditions to be used in TCES-CSP applications, i.e. involving carbonation under high CO2 partial pressure and at high temperature. All the experimental tests have been performed in a lab-scale sound assisted fluidized bed reactor applying high intensity acoustic field with proper frequency (150 dB-120 Hz). The carbonation kinetics has been analyzed by applying a simple kinetic model, able to properly describe the fast (under kinetic control) and slow (under diffusion control) stage of the reaction. In particular, the reaction rate, the intrinsic carbonation kinetic constant and the characteristic product layer thickness have been evaluated, also highlighting their dependence on the temperature between 800 and 845 degrees C; a value of 49 kJ mol(-1) has been obtained for the activation energy. Finally, a good agreement between the conversion-time profiles, evaluated from the applied kinetic models, and the experimental data has been obtained.

On-surface Ullmann coupling is an established method for the synthesis of 1D and 2D organic structures. A key limitation to obtaining ordered polymers is the uncertainty in the final structure for coupling via random diffusion of reactants over the substrate, which leads to polymorphism and defects. Here, a topotactic polymerization on Cu(110) in a series of differently-halogenated para-phenylenes is identified, where the self-assembled organometallic (OM) reactants of diiodobenzene couple directly into a single, deterministic product, whereas the other precursors follow a diffusion driven reaction. The topotactic mechanism is the result of the structure of the iodine on Cu(110), which controls the orientation of the OM reactants and intermediates to be the same as the final polymer chains. Temperature-programmed X-ray photoelectron spectroscopy and kinetic modeling reflect the differences in the polymerization regimes, and the effects of the OM chain alignments and halogens are disentangled by Nudged Elastic Band calculations. It is found that the repulsion or attraction between chains and halogens drive the polymerization to be either diffusive or topotactic. These results provide detailed insights into on-surface reaction mechanisms and prove the possibility of harnessing topotactic reactions in surface-confined Ullmann polymerization.

Dynamic thermogravimetric analysis is applied to investigate the thermal devolatilization of dry distiller's grain with solubles (DDGS), the major by-product of bioethanol plants. Compared with lignocellulosic biomass, the DDGS devolatilization occurs over a much wider temperature range and with slower rates. This reveals complex dynamics attributable to a peculiar chemical composition comprising, in addition to lignocellulose, proteins, starch and other minor components. The evolution of lumped volatile product classes is well described by a five-step reaction mechanism. The numerical solution of the ordinary differential equations together with a minimization of the objective function leads to activation energies invariant with the heating rate. The estimated values of 89, 120, 158, 102 and 113 kJ/mol are, on average, higher than those obtained under oxidative environments but still lower than those typically estimated for wood.

Saccharification of lignocellulosic biomass is a fundamental step in the biorefinery of second generation feedstock. The physicochemical and enzymatic processes for the depolymerization of biomass into simple sugars has been achieved through numerous studies in several disciplines. The present review discusses the development of technologies for enzymatic saccharification in industrial processes. The kinetics of cellulolytic enzymes involved in polysaccharide hydrolysis has been discussed as the starting point for the design of the most promising bioreactor configurations. The main process configurations--proposed so far--for biomass saccharification have been analyzed. Attention was paid to bioreactor configurations, operating modes and possible integrations of this operation within the biorefinery. The focus is on minimizing the effects of product inhibition on enzymes, maximizing yields and concentration of sugars in the hydrolysate, and reducing the impact of enzyme cost on the whole process. The last part of the review is focused on an emerging process based on the catalytic action of laccase applied to lignin depolymerization as an alternative to the consolidated physicochemical pretreatments. The laccases-based oxidative process has been discussed in terms of characteristics that can affect the development of a bioreactor unit where laccases or a laccase-mediator system can be used for biomass delignification.

Thermogravimetric curves are measured, at heating rates of 5, 10 and 20 K/min under a nitrogen flow, of industrial hemp and shives, a by-product of bast fiber production, after water retting and mechanical decortication of the plant stalk. To understand the influences of the pretreatments, measurements are also made for water-retted and water-washed hemp, and shives obtained from manual decortication. Beech wood is used for comparison. It is found that a five-component degradation scheme (in number of two, one and two, for the pseudo- hemicellulose, cellulose and lignin, in the order) provides an excellent description in all cases. The kinetic parameters are affected more by pretreatments (retting and decortication) than chemical composition (hemp stalks or shives). Moreover, in addition to the quantitative similarities between shives and beech wood, the differences between hemp and shives can be taken into account by slightly higher activation energies of the latter for the second and third component (177 and 195 kJ/mol versus 160 and 177 kJ/mol), thus describing its higher thermal stability. The performances of a standard three-component scheme are also evaluated.

Thermogravimetric curves are measured, by means of a flexible home-made (HM) system, of the oxidation of wood chars generated from packed-bed pyrolysis at 800 K. A careful control of the sample temperature and a small mass/size (4 mg mass corresponding to 140micron thick particle layer) allow a kinetic regime to be established for heating rates between 5 and 10 K/min. Good quantitative predictions are obtained based on a two-step mechanism, with activation energies affected by the hardwood or softwood origin of chars (125-143 kJ/mol and 186-207 kJ/mol for the devolatilization and oxidation reaction, respectively). The same conditions applied for a standard commercial (SC) thermogravimetric system result into remarkable self-heating leading to uncontrolled ignition and too slow oxygen diffusion rates. Only extremely small sample masses (<=1mg) and slow heating rates (<=5K/min) permit to completely eliminate heat and mass transfer intrusions but the actual limits are strictly related to the specific char reactivity.

The general principles guiding the design of molecular machines based on interlocked structures are well known. Nonetheless, the identification of suitable molecular components for a precise tuning of the energetic parameters that determine the mechanical link is still challenging. Indeed, what are the reasons of the "all-or-nothing" effect, which turns a molecular "speed-bump" into a stopper in pseudorotaxane-based architectures? Here we investigate the threading and dethreading processes for a representative class of molecular components, based on symmetric dibenzylammonium axles and dibenzo[24]crown-8 ether, with a joint experimental-computational strategy. From the analysis of quantitative data and an atomistic insight, we derive simple rules correlating the kinetic behaviour with the substitution pattern, and provide rational guidelines for the design of modules to be integrated in molecular switches and motors with sophisticated dynamic features.

Under mild acidic conditions, various metal derivatives of tetrakis(4-N-methylpyridinium)porphyrin (gold(III), AuT4; cobalt(III), CoT4; manganese(III), MnT4 and zinc(II), ZnT4) catalytically promote the supramolecular assembling process of the diacid 5,10,15,20-tetrakis(4-sulfonatophenyl)porphyrin (H2TPPS4) into J-aggregates. The aggregation kinetics have been treated according to a well-established model that involves the initial formation of a critical nucleus containing m porphyrin units, followed by autocatalytic growth, in which the rate evolves as a power of time. An analysis of the extinction time traces allows to obtain the rate constants for the auto-catalyzed pathway, kc, and the number of porphyrins involved in the initial seeding. The aggregation kinetics have been investigated at fixed H2TPPS4 concentration as a function of the added metal derivatives MT4. The derived rate constants, kc, obey a rate law that is first order in [MT4] and depend on the specific nature of the catalyst in the order AuT4 > CoT4 > MnT4 > ZnT4. Both resonance light scattering (RLS) intensity and extinction in the aggregated samples increase on increasing [MT4]. With the exception of AuT4, the final aggregated samples obtained at the highest catalyst concentration exhibit a negative Cotton effect in the J-band region, evidencing the occurrence of spontaneous symmetry breaking. The role of the nature of the metal derivative in terms of overall charge and presence of axial groups will be discussed.

34 natural bio-antioxidant and their synthetic analogues mainly of curcumin and its degradation product hava been selected for this study

The enzymatic hydrolysis of cellulose from biomass feedstock in the sugar-based biorefinery chain is penalized by enzyme cost and difficulty to approach the theoretical maximum cellulose conversion degree. As a consequence, the process is currently investigated to identify the best operating conditions with reference to each biomass feedstock. The present work reports an investigation regarding the enzymatic hydrolysis of apple pomace (AP). AP is an agro-food waste largely available in Europe that might be exploited as a sugar source for biorefinery purposes. A biomass pre-treatment step was required before the enzymatic hydrolysis to make available polysaccharides chains to the biocatalyst. The AP samples were pre-treated through alkaline (NaOH), acid (HCl), and enzymatic (laccase) delignification processes to investigate the effect of lignin content and polysaccharides composition on enzymatic hydrolysis. Enzymatic hydrolysis tests were carried out using a commercial cocktail (Cellic((R))CTec2) of cellulolytic enzymes. The effect of mixing speed and biomass concentration on the experimental overall glucose production rate was assessed. The characterization of the glucose production rate by the assessment of pseudo-homogeneous kinetic models was proposed. Data were analysed to assess kinetic parameters of pseudo-mechanistic models able to describe the glucose production rate during AP enzymatic hydrolysis. In particular, pseudo-homogeneous Michaelis and Menten, as well as Chrastil's models were used. The effect of lignin content on the enzymatic hydrolysis rate was evaluated. Chrastil's model provided the best description of the glucose production rate.

We report the biochemical and structural characterisation of a beta-carbonic anhydrase (beta-CA) fromTrichomonas vaginalis, a unicellular parasite responsible for one of the world's leading sexually transmitted infections, trichomoniasis. CAs are ubiquitous metalloenzymes belonging to eight evolutionarily divergent groups (alpha, beta, gamma, delta, zeta, eta, theta, and iota); humans express only alpha-CAs, whereas many clinically significant pathogens express only beta- and/or gamma-CAs. For this reason, the latter two groups of CAs are promising biomedical targets for novel antiinfective agents. The beta-CA fromT. vaginalis(TvaCA1) was recombinantly produced and biochemically characterised. The crystal structure was determined, revealing the canonical dimeric fold of beta-CAs and the main features of the enzyme active site. The comparison with the active site of human CA enzymes revealed significant differences that can be exploited for the design of inhibitors selective for the protozoan enzyme with respect to the human ones.

Aflatoxins (AF) are naturally occurring mycotoxins, produced by many species of Aspergillus. Among aflatoxins, Aflatoxin M1 (AFM1) is one of the most frequent and dangerous for human health. The acceptable maximum level of AFM1 in milk according to EU regulation is 50 ppt, equivalent to 152 pM, and 25 ppt, equivalent to 76 pM, for adults and infants, respectively. Here, we study a photonic biosensor based on Si 3 N 4 asymmetric Mach-Zehnder Interferometers (aMZI) functionalized with Fab' for AFM1 detection in milk samples (eluates). The minimum concentration of AFM1 detected by our aMZI sensors is 48 pM (16.8 pg/mL) in purified and concentrated milk samples. Moreover, the real-time detection of the ligand-analyte binding enables the study of the kinetics of the reaction. We measured the kinetic rate constants of the Fab'-AFM1 interaction.

Hyperpolarization-activated cyclic nucleotide-gated (HCN) channels control spontaneous electrical activity in heart and brain. Binding of cAMP to the cyclic nucleotide-binding domain (CNBD) facilitates channel opening by relieving a tonic inhibition exerted by the CNBD. Despite high resolution structures of the HCN1 channel in the cAMP bound and unbound states, the structural mechanism coupling ligand binding to channel gating is unknown. Here we show that the recently identified helical HCN-domain (HCND) mechanically couples the CNBD and channel voltage sensing domain (VSD), possibly acting as a sliding crank that converts the planar rotational movement of the CNBD into a rotational upward displacement of the VSD. This mode of operation and its impact on channel gating are confirmed by computational and experimental data showing that disruption of critical contacts between the three domains affects cAMP-and voltage-dependent gating in three HCN isoforms. © 2019, eLife Sciences Publications Ltd. All rights reserved.

We study the kinetics of hydrogen sorption in Mg-Ti-H nanoparticles prepared by gas phase condensation of mixed Mg-Ti vapors under a H-2-containing atmosphere. Four samples with different Ti contents from 14 to 63at.% Ti are examined in the 100-150 degrees C range. The hydrogen absorption kinetics coupled with the formation of MgH2 can be described by a nucleation and growth model. The activation energy is in the range 43-52 kJ/mol and the rate constant (at 150 degrees C) increases from 2710-3 s(-1) to 9210-3 s(-1) with increasing Ti content. Hydrogen desorption is well modeled by a sequence of surface-limited and contracting-volume kinetics, except at the highest Ti content where nucleation and growth is observed. The activation energy of surface-limited kinetics is approximate to 32 kJ /mol. The rate constant (at 150 degrees C) increases from 0.510-3 s(-1) to 1.210-3 s(-1) with the Ti content. These results open an unexplored kinetic window for Mg-based reversible hydrogen storage close to ambient temperature.

beta-cyclodextrin (beta-CD) and hydroxypropyl-beta-cyclodextrin (HP-beta-CD) were used to prepare insoluble polymers using epichlorohydrin as a cross-linking agent and the azo dye Direct Red 83:1 was used as target adsorbate. The preliminary study related to adsorbent dosage, pH, agitation or dye concentration allowed us to select the best conditions to carry out the rest of experiments. The kinetics was evaluated by Elovich, pseudo first order, pseudo second order, and intra-particle diffusion models. The results indicated that the pseudo second order model presented the best fit to the experimental data, indicating that chemisorption is controlling the process. The results were also evaluated by Freundlich, Langmuir and Temkin isotherms. According to the determination coefficient (R-2), Freunlich gave the best results, which indicates that the adsorption process is happening on heterogeneous surfaces. One interesting parameter obtained from Langmuir isotherm is q(max) (maximum adsorption capacity). This value was six times higher when a beta-CDs-EPI polymer was employed. The cross-linked polymers were fully characterized by nuclear magnetic resonance (NMR), Fourier transform infrared spectroscopy (FTIR), thermal gravimetric analysis (TGA). Also, morphology and particle size distribution were both assessed. Under optimized conditions, the beta-CDs-EPI polymer seems to be a useful device for removing Direct Red 83:1 (close 90%), from aqueous solutions and industrial effluents. Complementarily, non-adsorbed dye was photolyzed by a pulsed light driven advanced oxidation process. The proposed methodology is environmental and economically advantageous, considering the point of view of a sustainable recycling economy in the textile dyeing process.

The autoxidation kinetics of stripped sunflower oil (SSO), squalene (SQ), and p-cymene (p-C) initiated by 2,2'-azobis(isobutyronitrile) at 303 K were investigated under controlled conditions by differential oximetry in order to build reference model systems that are representative of the natural variability of oxidizable materials, for quantitative antioxidant testing. Rate constants for oxidative chain propagation (k(p)) and chain termination (2k(t)) and the oxidizability (k(p)/root 2k(t)) were measured using 2,6-di-tert-butyl-4-methoxyphenol, 2,2,5,7,8-pentamethyl-6-chromanol, BHT, and 4-methoxyphenol as reference antioxidants. Measured values of kp (M-1 s(-1))/2k(t) (M-1 s(-1))/oxidizability (M-1/2 s(-1/2)) at 303 K in chlorobenzene were 66.9/3.45 x 10(6)/3.6 x 10(-2), 68.0/7.40 x 10(6)/2.5 x 10(-2), and 0.83/2.87 x 10(6)/4.9 x 10(-4), respectively, for SSO, SQ, and p-C. Quercetin, magnolol, caffeic acid phenethyl ester, and 2,4,6-trimethylphenol were investigated to validate calibrations. The distinctive usefulness of the three substrates in testing antioxidants is discussed.

To elucidate the relationships between <em>Xylella fastidiosa</em> and its main European insect vector, the spittlebug <em>Philaenus spumarius</em>, experiments were conducted for two consecutive years to assess the kinetics, multiplication and persistence of the bacterium in the spittlebug. To this end, insects were first caged on infected source plants and then isolated, in groups of five, on olive or periwinkle plants at different times post-acquisition (3,7,14, 28, 56, and 72 days). Insects and recipient plants have been individually tested for <em>X. fastidiosa</em> by quantitative PCR. The bacterial load estimated in the infected insects at different times post-acquisition varied from few thousands to tens of thousands cells per insect's head. The second experiment was carried out to assess the influence of environmental factors (temperature, season) and insect age on simulated epidemics progression on olive plants. Adults of <em>P. spumarius,</em> fed on infected olive branches, were then released in cages containing 16 olive plants and collected after 3-7-14-21 days. Although , most of the diagnostic tests will be carried out only in the upcoming months, preliminary results indicate a higher acquisition efficiency in September as compared to July, and a lower acquisition efficiency from periwinkle compared to olive as source plants, but higher transmission efficiency to periwinkle compared to olive as recipient plants.

?-Glucosidase (BG) was immobilized by adsorption on wrinkled silica nanoparticles (WSNs) and on tannic acid-templated mesoporous silica nanoparticles (TA-MSNPs). The effect induced by a different morphology of the pores of the sorbent on the catalytic performance of ?-glucosidase was investigated. A complete textural and morphological characterization of the two samples was performed by Brunauer-Emmett-Teller (BET) method, Fourier Transform Infrared (FT-IR) and transmission electron microscopy (TEM). The results demonstrated that the catalytic performance of the immobilized enzyme depends on the pores size of sorbent but a key factor is the pores morphology. In fact, the BG immobilized on WSNs and TA-MSNPs (BG/WSNs and BG/TA-MSNPs) shows in both cases good catalytic performances in cellobiose hydrolysis, but the catalyst with the best performance is BG/WSNs, in which the support exhibits a central-radial pore structure and a hierarchical trimodal micro-mesoporous pore size. This peculiar morphology allows the enzyme to settle in a place where the interactions with the walls are maximized, increasing its conformational rigidity. Furthermore, the enzyme is prevalently collocated in the interior of pore so that the pores are not completely capped.