马来酸酐-烯丙氧基乙烯氧基羧酸共聚物去质子化程度对钙垢的影响

以马来酸酐和烯丙氧基乙烯氧基羧酸(APEA)为原料,通过自由基聚合法合成了含羧基和乙烯氧基的亲水性共聚物,通过红外光谱、核磁共振氢谱和凝胶色谱对其结构进行了表征。通过静态阻垢实验研究了聚合物的去质子化程度对抑制钙垢的影响,并通过扫描电镜和X射线衍射分析考察了聚合物的去质子化程度对碳酸钙晶体的形貌与晶型分布的影响。结果表明,随着去质子化程度的增加,聚合物对碳酸钙和硫酸钙垢的抑制效率逐渐降低,而对磷酸钙垢的抑制效率逐渐增加;阻垢剂去质子化程度的改变加速了文石和球霰石向方解石的转化,但这种转化并未明显影响碳酸钙晶体的形貌。

The molecular mechanisms of plasticity in crystal forms of theophylline

Plastic and elastic behaviors of organic crystals have profound influence on the processability of pharmaceutical substances.Analogous to metals,the identifications of molecular slip planes in organic crystals are regarded as a strategy for harnessing plasticity.In this work,we experimentally characterized the form II anhydrous theophylline(THPa)and its monohydrate(THPm)for their distinct plastic and elastic behaviors.Extensive DFT calculations were performed to model the effects of increasing lattice strains on molecular packing.We discovered that the energy barrier associated with the strain-induced molecular rearrangement would link to the plasticity of THPa,and possibly other simple aromatic compounds.Meanwhile,water molecules in THPm disrupt the stacking architecture from THPm and effectively undermine the general mechanism for plasticity.Hydrate formation would therefore be an alternative strategy to engineer the mechanical property of organic crystalline materials.

Metabolic engineering using acetate as a promising building block for the production of bio‐based chemicals

The production of biofuels and biochemicals derived from microbial fermentation has received a lot of attention and interest in light of concerns about the depletion of fossil fuel resources and climatic degeneration.However,the economic viability of feedstocks for biological conversion remains a barrier,urging researchers to develop renewable and sustainable low-cost carbon sources for future bioindustries.Owing to the numerous advantages,acetate has been regarded as a promising feedstock targeting the production of acetyl-CoA-derived chemicals.This review aims to highlight the potential of acetate as a building block in industrial biotechnology for the production of bio-based chemicals with metabolic engineering.Different alternative approaches and routes com-prised of lignocellulosic biomass,waste streams,and C1 gas for acetate generation are briefly described and evaluated.Then,a thorough explanation of the metabolic pathway for biotechnological acetate conversion,cel-lular transport,and toxin tolerance is described.Particularly,current developments in metabolic engineering of the manufacture of biochemicals from acetate are summarized in detail,with various microbial cell factories and strategies proposed to improve acetate assimilation and enhance product formation.Challenges and future development for acetate generation and assimilation as well as chemicals production from acetate is eventually shown.This review provides an overview of the current status of acetate utilization and proves the great potential of acetate with metabolic engineering in industrial biotechnology.

Correlation between multi-factor phase diagrams and complex electrocaloric behaviors in PNZST antiferroelectric ceramic system

Ferroelectric(FE)phase transition with a large polarization change benefits to generate large electrocaloric(EC)effect for solid-sate and zero-carbon cooling application.However,most EC studies only focus on the single-physical factor associated phase transition.Herein,we initiated a comprehensive discussion on phase transition in Pb_(0.99)Nb_(0.02)[(Zr_(0.6)Sn_(0.4))1−xTix]_(0.98)O_(3)(PNZST100x)antiferroelectric(AFE)ceramic system under the joint action of multi-physical factors,including composition,temperature,and electric field.Due to low energy barrier and enhanced zero-field entropy,the multi-phase coexistence point(x=0.12)in the composition–temperature phase diagram yields a large positive EC peak of maximum temperature change(ΔT_(max))=2.44 K(at 40 kV/cm).Moreover,the electric field–temperature phase diagrams for four representative ceramics provide a more explicit guidance for EC evolution behavior.Besides the positive EC peaks near various phase transition temperatures,giant positive EC effects are also brought out by the electric field-induced phase transition from tetragonal AFE(AFET)to low-temperature rhombohedral FE(FER),which is reflected by a positive-slope boundary in the electric field–temperature phase diagram,while significant negative EC responses are generated by the phase transition from AFET to high-temperature multi-cell cubic paraelectric(PEMCC)with a negative-slope phase boundary.This work emphasizes the importance of phase diagram covering multi-physical factors for high-performance EC material design.

Large electrocaloric effect over a wide temperature span in lead-free bismuth sodium titanate-based relaxor ferroelectrics

For efficient solid-state refrigeration technologies based on electrocaloric effect(ECE),it is a great challenge of simultaneously obtaining a large adiabatic temperature change(DT)within a wide temperature span(Tspan)in lead-free ferroelectric ceramics.Here,we studied the electrocaloric effect(ECE)in(1-x)(Na_(0.5)Bi_(0.5))TiO_(3)-xCaTiO_(3)((1-x)NBT-xCT)and explored the combining effect of morphotropic phase boundary(MPB)and relaxor feature.The addition of CT not only constructs a MPB region with the coexistence of rhombohedral and orthorhombic phases,but also enhances the relaxor feature.The ECE peak appears around the freezing temperature(Tf),and shifts toward to lower temperature with the increasing CT amount.The directly measured ECE result shows that the ceramic of x=0.10,which is in the MPB region,has an optimal ECE property of DTmax=1.28 K@60℃under 60 kV/cm with a wide Tspan of 65C.The enhanced ECE originates from the electric-field-induced transition between more types of polar nanoregions and long-range ferroelectric macrodomains.For the composition with more relaxor feature in the MPB region,such as x?0.12,the ECE is relatively weak under low electric fields but it exhibits a sharp increment under a sufficiently high electric field.This work provides a guideline to develop the solidestate cooling devices for electronic components.

Structural landscape investigations on bendable plastic crystals of isonicotinamide polymorphs

Three polymorphs(forms I,II and V)of isonicotinamide(INA)were mechanically flexible and exhibited one-dimensional(1 D)plasticity.Anisotropic intermolecular interactions contribute to the plasticity of single crystals:weak dispersive interactions between slip planes such as 1 D columns in forms I and II or 2 D layers in form V were stabilized by strong hydrogen bonds,allowing the layer or column's surface to glide smoothly without hindrance.The disparity of intermolecular interactions on plastic properties of INA polymorphic crystals was confirmed by energy framework analysis,nanoindentation tests and micro-Raman spectroscopy.The crystal which exhibits plastic property provides a promising application in pharmaceuticals and material sciences.