To avoid the negative impact of plastic on the environment and on human health and to improve the circular economy, the search for new and cost-efficient methods for the depolymerization of plastic ...waste into value added compounds is extremely desirable. In recent years, reductive depolymerization has emerged as an excellent alternative methodology for the valorization of plastic waste and has gained interest as it allows plastic waste to be transformed into value-added products, which cannot be obtained by other recycling processes. Catalysts can have a fundamental role in this subject. This review aims to describe the most relevant catalytic methodologies for the reductive depolymerization of polyester, polycarbonate and polyamide waste into value-added compounds.
Reductive depolymerization allows the valorization of polyester, polycarbonate and polyamide waste in a wide variety of value-added compounds with good yields
Plastic pollution is one of the biggest problems all over the world. Beyond change/awareness of consumer behavior, there is an urgent need to search for efficient, economical and environmentally ...friendly catalysts for the valorization of plastic waste to value‐added compounds. This work describes the reductive depolymerization of several types of plastic waste into value‐added compounds, including 1,6‐hexanediol, 1,2‐propanediol, p‐xylene and tetrahydrofuran, in good yields using the eco‐friendly, air‐stable, commercially available and very cheap catalyst Zn(OAc)2 ⋅ 2H2O. This is the first example of the reductive depolymerization of polyester waste catalyzed by a zinc catalyst. Moreover, the catalytic system silane/Zn(OAc)2 ⋅ 2H2O was successfully applied to the reduction of polycaprolactone (PCL) on the gram scale with good yield and also to the selective reductive depolymerization of plastic mixtures. Finally, this work demonstrated that the catalyst Zn(OAc)2 ⋅ 2H2O can be used in at least 7 cycles with good yields.
Waste not, want not: Zn(OAc)2 ⋅ 2H2O is used as a cost‐effective catalyst for the reductive depolymerization of several types of plastic waste into value‐added compounds including 1,6‐hexanediol, 1,2‐propanediol, p‐xylene and THF.
Learning to export from neighbors Fernandes, Ana P.; Tang, Heiwai
Journal of international economics,
09/2014, Letnik:
94, Številka:
1
Journal Article
Recenzirano
Odprti dostop
This paper studies how learning from neighboring firms affects new exporters' performance. We develop a statistical decision model in which a firm updates its prior belief about demand in a foreign ...market based on several factors, including the number of neighbors currently selling there, the level and heterogeneity of their export sales, and the firm's own prior knowledge about the market. A positive signal about demand inferred from neighbors' export performance raises the firm's probability of entry and initial sales in the market but, conditional on survival, lowers its post-entry growth. These learning effects are stronger when there are more neighbors to learn from or when the firm is less familiar with the market. We find supporting evidence for the main predictions of the model from transaction-level data for all Chinese exporters over the 2000-2006 period. Our findings are robust to controlling for firms' supply shocks, countries' demand shocks, and city-country fixed effects.
•We model how learning from neighbors affects new exporters' performance.•Exporters update beliefs about foreign demand, after observing neighbors' exports.•Exporters' entry, initial sales, survival, and growth are affected by learning.•Belief updating depends on the prevalence of neighbors and their sales heterogeneity.•Transaction-level evidence for Chinese exporters largely supports the model.
The dramatic expansion of internet access in China allows us to analyze the impact of the internet on firm performance. Combining firm-level production data with province-level information on ...internet penetration, we examine how the internet rollout across Chinese provinces in 1999–2007 influenced firm export behavior. We show that the internet rollout boosted firm manufacturing exports, even before the rise of major e-commerce platforms. We take a closer look at why, addressing three questions: what aspects of firm performance were affected, what types of firm communication were facilitated, and what dimensions of the new communication medium were relevant? We find that the internet did not just enhance trade but improved overall firm performance; results are consistent with improvements in communication with both buyers and input suppliers; benefits arose not just from better communication but from establishing a visible virtual presence, and were enhanced by, but not contingent on, access to broadband.
•Internet access boosted firm exports in China even before broadband and Alibaba.•Firm output also increased, due to increases in both productivity and employment.•Communication-intensive industries benefitted more from internet access.
This paper explores a period of substantial variation in trade policy across industries in Colombia (1977–1991) to examine whether increased exposure to foreign competition generates productivity ...gains for manufacturing plants. Using an estimation methodology that addresses the shortcomings of previous studies, we find a strong positive impact of tariff liberalization on plant productivity, even after controlling for plant and industry heterogeneity, real exchange rates, and cyclical effects. The impact of liberalization is stronger for larger plants and plants in less competitive industries. Our findings are not driven by the endogeneity of protection. Similar results are obtained when using effective rates of protection and import penetration ratios as measures of protection. Productivity gains under trade liberalization are linked to increases in intermediate inputs' imports, skill intensity, and machinery investments, and to output reallocations from less to more productive plants.
While innovation matters for competitiveness, it may expose firms to survival risks. Using plant-product data for Chile and discretetime hazard models, we show mat innovating plants have a lower ...hazard of exit. However, risk has a strong impact on the innovation-exit relationship: only innovators that retain diversified sources of revenue or face lower market risk are less likely to die. Single-product innovators are at greater risk of exiting. Exposure to technical risk does not affect exit probabilities differentially. We provide tentative evidence that singleproduct innovators have higher profits, which helps to rationalize their innovation decision despite the increased risk of exit.
We present new data on the micro-structure of the export sector for 45 countries and study how exporter behavior varies with country size and stage of development. Larger countries and more developed ...countries have more exporters, larger exporters, and a greater share of exports controlled by the top 5%. The extensive margin (more firms) plays a greater role than the intensive margin (average size) in supporting exports of larger countries. In contrast, the intensive margin is relatively more important in explaining the exports of richer countries. Exporter entry and exit rates are higher and entrant survival is lower at an early stage of development. We discuss the results in light of trade theories with heterogeneous firms and the empirical literature on resource allocation, firm size, and development. An implication from our findings is that developing countries export less because the top of the firm-size distribution is truncated.
•We study how exporter behavior varies with country size and stage of development.•Larger and richer countries have more and larger exporters, exports are concentrated.•Exporter entry and exit rates are higher, survival is lower in developing countries.•Heterogeneous firm theories and literature on resource allocation support findings.•Developing countries export less because top of firm-size distribution is truncated.
OBJECTIVETo compare the analgesic effects of stimulation of the anterior cingulate cortex (ACC) or the posterior superior insula (PSI) against sham deep (d) repetitive (r) transcranial magnetic ...stimulation (TMS) in patients with central neuropathic pain (CNP) after stroke or spinal cord injury in a randomized, double-blinded, sham-controlled, 3-arm parallel study.
METHODSParticipants were randomly allocated into the active PSI-rTMS, ACC-rTMS, sham-PSI-rTMS, or sham-ACC-rTMS arms. Stimulations were performed for 12 weeks, and a comprehensive clinical and pain assessment, psychophysics, and cortical excitability measurements were performed at baseline and during treatment. The main outcome of the study was pain intensity (numeric rating scale NRS) after the last stimulation session.
RESULTSNinety-eight patients (age 55.02 ± 12.13 years) completed the study. NRS score was not significantly different between groups at the end of the study. Active rTMS treatments had no significant effects on pain interference with daily activities, pain dimensions, neuropathic pain symptoms, mood, medication use, cortical excitability measurements, or quality of life. Heat pain threshold was significantly increased after treatment in the PSI-dTMS group from baseline (1.58, 95% confidence interval CI 0.09–3.06) compared to sham-dTMS (−1.02, 95% CI −2.10 to 0.04, p = 0.014), and ACC-dTMS caused a significant decrease in anxiety scores (−2.96, 95% CI −4.1 to −1.7) compared to sham-dTMS (−0.78, 95% CI −1.9 to 0.3; p = 0.018).
CONCLUSIONSACC- and PSI-dTMS were not different from sham-dTMS for pain relief in CNP despite a significant antinociceptive effect after insular stimulation and anxiolytic effects of ACC-dTMS. These results showed that the different dimensions of pain can be modulated in humans noninvasively by directly stimulating deeper SNC cortical structures without necessarily affecting clinical pain per se.
CLINICALTRIALS.GOV IDENTIFIER:NCT01932905.
This paper investigates the effect of financing constraints following the 2008-9 financial crisis on executives’ gender inequality. We use linked employer-employee data for the universe of private ...sector firms in Portugal, and exploit pre-crisis variation in external finance dependence across industries for identification. We find that the crisis had a positive effect on female executives’ pay in exposed firms. Firms in financially more constrained industries reduce the gender pay-gap and increase the share of females in executive positions after the crisis. At the worker-level, females in exposed industries are more likely to be promoted to executive and less likely to be demoted. We discuss channels and interpretations for the effects. Our results are consistent with female managerial characteristics, such as attitudes toward risk, being more valued after the crisis in exposed firms. A reduction in preference-based discrimination cannot be discounted.
The search for new metal-efficient drugs has attracted considerable attention of the scientific community. Among them, ruthenium complexes have emerged as an excellent alternative of platinum ...complexes. This review presents a thorough and timely coverage of the synthesis, biological activity and medicinal applications of ruthenium complexes bearing carbohydrate ligands, allowing a large community of readers, in particularly the community that works in organic, inorganic, bioorganometallic and medicinal chemistry, ready access to the most relevant examples.
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