SMEs are drivers of economic growth and job creation in developing countries. It is paramount to determine the factors that hinder their growth. This paper uses the Enterprise Survey from the World ...Bank which covers data from 119 developing countries to investigate the biggest obstacles SMEs are confronting and the determinants that influence the obstacles as perceived by enterprise managers. The results show that SMEs perceive access to finance as the most significant obstacle which hinders their growth. The key determinants among firms' characteristics are size, age and growth rate of firms as well as the ownership of the firm. The latter – the role of the state in financing SME – is particularly intriguing. External reasons for the financing dilemma are also examined. It is shown that the main barriers to external financing are high costs of borrowing and a lack of consultant support.
The health-threatening air pollution, especially from particulate matter (PM), has triggered increasing demands for developing low-cost and long-service-life air-cleaning technologies. In the present ...contribution, a range of high-efficiency textiles/metal–organic framework (MOF) composites (MOFs@textiles) air filters with excellent washable reusability is presented. By processing MOFs onto textile substrates via an eco-friendly solvent-free method to enable the microporous feature and also strong PM adhesion, we develop flexible, highly effective air filters with >95.00% PM removal efficiency (e.g., MiL-53(Al)@Aramid, PM2.5: 95.30%, PM10: 96.11%) under harmful air quality conditions (average PM2.5 mass concentration > 280 μg m–3 and PM10 > 360 μg m–3). Therefore, these MOFs@textiles are promising composites for producing efficient and recyclable out-/indoor air purifiers.
•Moderate high intensity ultrasound (HIU) could affect the structure of proteins positively.•Potential mechanisms of HIU on functionality of proteins are elucidated clearly.•HIU combined with other ...methods can achieve synergistic modification effects.•Multi-mode HIU devices can overcome the shortcomings of traditional HIU devices.
High intensity ultrasound (HIU) is an efficient and green technology that has recently received enormous research attention for modification of food proteins. However, there are still several knowledge gaps in the possible mechanisms, synergistic effects of HIU with other strategies and improvement of HIU equipment that contribute to its application in the food industry. This review focuses on the recent research progress on the effects and potential mechanisms of HIU on the structure (including secondary and tertiary structure) and functionality (including solubility, emulsibility, foamability, and gelability) of proteins. Furthermore, the combination methods and innovations of HIU equipment for proteins modification in recent years are also detailed. Meanwhile, the possible future trends of food proteins modification by HIU are also considered and proposed.
Signal decomposition is a classical problem in signal processing, which aims to separate an observed signal into two or more components, each with its own property. Usually, each component is ...described by its own subspace or dictionary. Extensive research has been done for the case where the components are additive, but in real-world applications, the components are often non-additive. For example, an image may consist of a foreground object overlaid on a background, where each pixel either belongs to the foreground or the background. In such a situation, to separate signal components, we need to find a binary mask which shows the location of each component. Therefore, it requires solving a binary optimization problem. Since most of the binary optimization problems are intractable, we relax this problem to the approximated continuous problem and solve it by alternating optimization technique. We show the application of the proposed algorithm for three applications: separation of text from a background in images, separation of moving objects from a background undergoing global camera motion in videos, and separation of sinusoidal and spike components in 1-D signals. We demonstrate in each case that considering the non-additive nature of the problem can lead to a significant improvement.
We derive a new approximate version of the alternating direction method of multipliers (ADMM) which uses a relative error criterion. The new version is somewhat restrictive and allows only one of the ...two subproblems to be minimized approximately, but nevertheless covers commonly encountered special cases. The derivation exploits the long-established relationship between the ADMM and both the proximal point algorithm (PPA) and Douglas–Rachford (DR) splitting for maximal monotone operators, along with a relative-error of the PPA due to Solodov and Svaiter. In the course of analysis, we also derive a version of DR splitting in which one operator may be evaluated approximately using a relative error criterion. We computationally evaluate our method on several classes of test problems and find that it significantly outperforms several alternatives on one problem class.
Adsorption technology based on ethane‐selective materials is a promising alternative to energy‐intensive cryogenic distillation for separating ethane (C2H6) and ethylene (C2H4). We employed a pore ...engineering strategy to tune the pore environment of a metal–organic framework (MOF) through organic functional groups and boosted the C2H6/C2H4 separation of the MOF. Introduction of amino (−NH2) groups into Tb‐MOF‐76 not only decreased pore sizes but also facilitated multiple guest‐host interactions in confined pores. The NH2‐functionalized Tb‐MOF‐76(NH2) has increased C2H6 and C2H4 uptakes and C2H6/C2H4 selectivity. The results of experimental and simulated transient breakthroughs reveal that Tb‐MOF‐76(NH2) has significantly improved one‐step separation performance for C2H6/C2H4 mixtures with a high C2H4 (>99.95 %) productivity of 17.66 L kg−1 compared to 7.53 L kg−1 by Tb‐MOF‐76, resulting from the suitable pore confinement and accessible −NH2 groups on pore surfaces.
By virtue of a pore engineering strategy based on isoreticular chemistry, an amino‐functionalized metal–organic framework (MOF) with suitable pore confinement and more binding sites improved the ethane/ethylene separation performance compared to the parent MOF.
One‐step C2H4 purification from ternary C2H6/C2H4/C2H2 mixtures by a single adsorbent is of great industrial significance, but few adsorbents achieve this separation. Herein, we report a robust ...metal–organic framework (MOF) that possesses methyl‐decorated nonpolar pores and shows one‐step C2H4 purification (purity >99.9 %) from binary C2H6/C2H4 mixtures and ternary C2H6/C2H4/C2H2 mixtures. The methyl groups in pores provide a suitable pore environment to simultaneously enhance the adsorption capacity for C2H2 and C2H6 compared to C2H4. Simulations revealed the multiple interactions between C2H6 or C2H2 molecules and the pore wall, while the interactions with C2H4 molecules are weak and also unfavorable due to the repulsion from methyl groups in pores. The MOF displays high C2H6 and C2H2 uptakes and benchmark C2H6/C2H4 selectivity (2.2), surpassing all of the reported MOFs for one‐step C2H4 purification from ternary C2H6/C2H4/C2H2 mixtures.
The combination of nonpolar pore environment and accessible active sites in a metal–organic framework affords benchmark C2H6/C2H4 selectivity and realizes one‐step C2H4 purification from ternary C2H6/C2H4/C2H2 mixtures.
•A high molecular weight polysaccharide (PL-N) was degraded by ultrasound.•Ultrasound decreased the intrinsic viscosity and molecular weight of PL-N.•The degradation behavior of PL-N under ultrasound ...was fitted to (1/Mt−1/M0)=k·t.•Ultrasound degradation did not change the primary structure of PL-N.•Ultrasound can effectively enhance antioxidant activities of polysaccharides.
In this study, a high-molecular-weight polysaccharide PL-N isolated from the alkaline extract of Phellinus linteus mycelia was degraded by ultrasound. Results showed that ultrasound treatment at different ultrasonic intensities decreased the intrinsic viscosity and molecular weight of PL-N, as well as narrowed the molecular weight distribution. A larger reduction in intrinsic viscosity and molecular weight was caused by a higher ultrasonic intensity. The degradation kinetics model was fitted to (1/Mt−1/M0)=k·t, and the reaction rate constant (k) increased with increasing ultrasonic intensity. Ultrasound degradation did not change the primary structure of PL-N, and scanning electron microscopy analysis indicated that the morphology of the original PL-N was different from that of degraded PL-N fractions. Antioxidant activity assays in vitro indicated that the degraded PL-N fraction with low molecular weight had stronger hydroxyl radical scavenging capacity and higher TEAC and FRAP values.
•Ultrasound modes had effects on the structure of myofibrillar proteins (MPs).•Dual-frequency 20/40 kHz ultrasound thawing (DUT) was best thawing method.•DUT can effectively minimized the changes in ...MPs structure during thawing process.•MPs pretreated by DUT had less aggregation and degradation.•DUT protect the rheological behavior during the thawing process.
The influence of multi-frequency combined ultrasound thawing on primary, secondary, and tertiary structures, electrophoresis pattern, particle size distribution, zeta potential values, thermal stability, rheological behavior, and microstructure of small yellow croaker myofibrillar proteins (MPs) were studied. Four treatments were used for thawing small yellow croakers: flow water thawing (FWT), mono-frequency ultrasonic thawing (MUT), dual-frequency ultrasonic thawing (DUT), and tri-frequency ultrasonic thawing (TUT). Compared with fresh samples (FS), the MPs of the sample pretreated by DUT had non-significant effect on protein primary (including free amino groups and surface hydrophobicity), secondary, tertiary structures, electrophoresis pattern, and microstructure. MPs pretreated by DUT had less aggregation and degradation. Besides, DUT treatment increased the thermal stability of MPs. The ultrasound had significant effects on the rheological properties of MPs. Overall, DUT effectively minimized the changes in MPs structure and protected the protein thermal stability and rheological behavior during the thawing process.
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