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Qiang Fang

Publications and source records attributed to Qiang Fang.

18 recordsLinked to original sources
PubMed2006

[The therapeutic effects of fluid resuscitation in severe sepsis and septic shock].

OBJECTIVE: To evaluate the therapeutic effect of fluid resuscitation on severe sepsis and septic shock. METHODS: Twenty patients with severe sepsis and septic shock were given fluid resuscitation and got the following parameters in the ranges as follow: central venous pressure (CVP) 8 - 12 mm Hg (for ventilation patient: 12 - 15 mm Hg), mean artery pressure (MAP) 65 - 90 mm Hg, mixed venous oxygen saturation (SmvO(2)) > 70%. Hemodynamics, tissue perfusion and vascular endothelial cell function were measured and compared before and after fluid resuscitation. RESULTS: Pulmonary arterial wedge pressure (PAWP), cardiac index (CI), left ventricular stroke work index (LVSWI) and systemic vascular resistance index (SVRI) increased significantly after reached the goal of fluid resuscitation (P < 0.01) whereas pulmonary vascular resistance index (PVRI), lactate level in arterial blood and gastric-to-arterial carbon dioxide partial pressure gap (Pg-aCO(2)) decreased significantly (P < 0.01), and the serum levels of endothelin (ET) and von Willebrand factor (vWF) were also decreased significantly after fluid resuscitation (P < 0.05). CONCLUSIONS: Early goal-directed fluid resuscitation can improve hemodynamics, tissue perfusion and alleviate vascular endothelial cell injury in patients with severe sepsis and septic shock, it is an effective therapy for these patients.

Blood Gas Analysis↗
PubMed2006

Amphiphilic poly(L-lactide)-b-dendritic poly(L-lysine)s synthesized with a metal-free catalyst and new dendron initiators: chemical preparation and characterization.

This study presents investigations on new approaches to novel biodegradable amphiphilic poly(L-lactide)-b-dendritic poly(L-lysine)s bearing well-defined structures. First, two new Boc-protected poly(L-lysine) dendron initiators G(2)OH 4 (generation = 2) and G(3)OH 6 (generation = 3) with hydroxyl end functional groups were efficiently derived from corresponding precursors 3 and 5 via methyl ester substitution with ethanolamine. Subsequently, two series of new diblock copolymers of poly(L-lactide)-b-dendritic Boc-protected poly(L-lysine)s (S1-S2, S3-S4) were prepared in chloroform through ring-opening copolymerization of poly(L-lactide)s with a metal-free catalyst of organic 4-(dimethylamino) pyridine (DMAP) in the presence of a corresponding new poly(L-lysine) dendron initiator. Further, molecular structures of the prepared new dendron initiators as well as those of poly(L-lactide)-b-dendritic Boc-protected poly(L-lysine)s bearing different dendron blocks and PLLA lengths were examined by means of nuclear magnetic resonance spectroscopy (NMR), gel permeation chromatography (GPC), mass spectrometry (ESI-MS, MALDI-FTMS), and thermal gravimetric analysis (TGA). The results demonstrated successful formation of the synthetic precursors, functional dendron initiators, and new diblock copolymers. In addition, the very narrow molecular weight distributions (PDI = 1.10-1.14) of these poly(L-lactide)-b-dendritic Boc-protected poly(L-lysine)s further indicated their well-defined molecular structures. After the efficient Boc-deprotection for the dendron amino groups with TFA/CH(2)Cl(2), new diblock poly(L-lactide)-b-dendritic poly(L-lysine)s bearing lipophilic PLLA and hydrophilic dendritic PLL were finally prepared. It was noteworthy that the MALDI-FTMS result showed that no appreciable intermolecular chain transesterification happened during the ROP of L-lactide catalyzed by the DMAP. Moreover, self-assembly of these new biodegradable amphiphilic copolymers in diverse solvents were also preliminarily studied.

Anthracenes↗
PubMed2006

New asymmetric AB(n)-shaped amphiphilic poly(ethylene glycol)-b-[poly(l-lactide)](n) (n = 2, 4, 8) bridged with dendritic ester linkages: I. Syntheses and their characterization.

This study presents new investigations on chemical syntheses and characterization of new asymmetric AB(n)-shaped amphiphilic diblock methoxy poly(ethylene glycol)-b-[poly(l-lactide)](n), MPEG-b-(PLLA)(n) (n = 2, 4, and 8), bridged with dendritic ester linkages. First, a new series of A(OH)(n)-shaped hydroxy end-capped MPEG-(OH)(2), MPEG-(OH)(4), and MPEG-(OH)(8) bearing corresponding one- to three-generation dendritic ester moieties were efficiently derived from the starting MPEG (M(n) = 2 KDa) and 2,2'-bis(hydroxymethyl)propionic acid (Bis-HMPA) via ester coupling and a facile hydroxy protection-deprotection cycle, and then, chemical structures of these functional MPEG-(OH)(n) were characterized by nuclear magnetic resonance spectrometry (NMR) and MALDI-FTMS. Subsequently, by employing these MPEG-(OH)(n) as functional macroinitiators, new asymmetric AB(n)()-shaped amphiphilic MPEG-b-(PLLA)(2) S1, MPEG-b-(PLLA)(4) S2, and MPEG-b-(PLLA)(8) S3 bridged with dendritic Bis-HMPA ester linkages of L1-L3 as well as linear structural MPEG-b-PLLA references (R1-R3) were synthesized through the SnOct(2)-catalyzed ring-opening polymerization (ROP) of l-lactide at 130 degrees C in m-xylene solution, and their structures were further examined by NMR and gel permeation chromatography (GPC). It was demonstrated that the functional MPEG-(OH)(n) efficiently initiated the ROP of LLA, finally leading to successful formation of the AB(n)-shaped amphiphilic MPEG-b-(PLLA)(n) (n = 2, 4, and 8) with each PLLA arm weight close to 2 KDa and very narrow molecular weight distribution. Moreover, thermal history, crystallization, and spherulite morphologies were studied by means of differential scanning calorimeter (DSC), thermal gravimetric analyzer (TGA), and polarized microscope (POM) for these new structural amphiphilic S1-S3 as well as the linear R1-R3, intriguingly indicating a strong molecular architecture dependence of segmental crystallizability, spherulite morphology, and apparent crystal growth rate. Due to the favorable biodegradability and biocompatibility of the PLLA and MPEG, these results may therefore create new possibilities for these novel structural AB(n)-shaped amphiphilic MPEG-b-(PLLA)(n) as potential biomaterials.

Cross-Linking Reagents↗
PubMed2006

[Clinical study of serum lipopolysaccharide-binding protein and soluble CD14 in severe sepsis patients].

OBJECTIVE: To investigate the changes in serum lipopolysaccharide binding protein (LBP) and soluble CD14 (sCD14) levels in severe sepsis patients, and their relationship with severity and prognosis of patients. METHODS: Serum concentration of LBP and sCD14 were measured by enzyme linked immuno adsorbent assay (ELISA) at different periods after the onset of severe sepsis in 41 patients. Serum concentrations of procalcitonin (PCT) and lipopolysaccharide (LPS) were determined within 24 hours of onset of severe sepsis. The relationship between all the determinations and the clinical picture and prognosis of the patients was analyzed. RESULTS: Significantly higher than normal serum concentrations of LBP and sCD14 were found in severe sepsis patients (all P<0.01). There was no significant difference in LBP serum levels between non-survivors and survivors (all P>0.05). But sCD14 serum levels were significantly higher in non-survivors (all P<0.05). There was no correlation between serum LBP levels and PCT or acute physiology and chronic health evaluation II (APACHE II) at day 0. Serum LBP level was positively correlated with that of LPS significantly. There was significant positive correlation between serum sCD14 levels and PCT, APACHE II at day 0, but no correlation between sCD14 and LPS. CONCLUSION: Significantly elevated serum concentrations of LBP and sCD14 are found in severe sepsis patients. LBP level reflects mainly systemic inflammatory response induced by LPS, and it cannot be used as an indicator of severity of sepsis and prognosis of the patient. In contrast, serum sCD14 level may be used as a prognostic marker in severe sepsis, as it can reflect the severity of sepsis in certain degree.

Acute-Phase Proteins↗
PubMed2006

[Effects of raw rhubarb on plasma D-lactate and procalcitonin expressions in patients with sepsis].

OBJECTIVE: To investigate the effects of raw rhubarb (RR) on levels of plasma D-lactate and procalcitonin in patients with sepsis. METHODS: Forty patients with sepsis enrolled were randomly divided into two groups, the RR group (n=18, treated with RR 9 g/d) and the control group (n=22, treated with conventional treatment). Plasma procalcitonin and D-lactate were determined before and after treatment. RESULTS: Before treatment, there was no significant difference in the levels of plasma procalcitonin and D-lactate between the two groups (procalcitonin: 6.50 +/- 2.37 microg/L vs 6.98 +/- 2.89 microg/L; D-lactate: 0.18 +/- 0.05 mmol/L vs 0.19 +/- 0.06 mmol/L, P > 0.05). However, after treatment, two indexes in the RR group were significantly lower than those in the control group (procalcitonin: 4.11 +/- 1.40 microg/L vs 2.21 +/- 0.61 microg/L; D-lactate: 0.24 +/- 0.06 ng/L vs 0.09 +/- 0.03 ng/L, both P < 0.05). CONCLUSION: RR could ameliorate the intestinal permeability and reduce the shifting of intestinal bacteria, so as to ease the condition of disease in patients with sepsis.

Aged↗
PubMed2006

[Effect of fluid resuscitation on adhesion molecule and hemodynamics in patients with severe sepsis].

OBJECTIVE: To explore the effects of fluid resuscitation on adhesion molecule and hemodynamics in patients with severe sepsis. METHODS: Thirty-eight patients with severe sepsis were randomly divided into 2 groups: rapid fluid resuscitation group and general treatment group. Before and after fluid resuscitation, heart rate (HR), mean arterial pressure (MAP), central venous pressure (CVP), lactic acid content, plasma P-selection and intercellular adhesion molecule-1 (ICAM-1) contents were determined. RESULTS: There were no statistically significant differences in sex, age, resuscitation time and acute physiology and chronic health evaluation II (APACHE II) score between the two groups. Compared with general treatment group, more liquid volume but less aramine dosage were used (both P<0.05), MAP and CVP were increased after fluid resuscitation in rapid fluid resuscitation group (all P<0.05). The expression of P-selection, HR, contents of ICAM-1 and lactic acid were decreased (all P<0.05), and all of those were better than those of before fluid resuscitation. CONCLUSION: Early rapid fluid resuscitation can improve hemodynamics and decrease the expression of adhesion molecule to retard the development of sepsis.

Adult↗
PubMed2005

Evidence for multiple shared antigenic determinants within Ro60 and other lupus-related ribonucleoprotein autoantigens in human autoimmune responses.

Ab responses directed against several ribonucleoprotein (RNP) Ags are a characteristic feature of systemic lupus erythematosus (SLE). Previous work in our laboratory using mouse model systems had revealed that both epitope spreading and inherent cross-reactivity between ribonucleoproteins contributes to the observed multiple specificities in autoimmune sera. We have now extended these studies to human autoimmune responses. Using purified polyclonal and mAbs derived from SLE patients, cross-reactivity between Ro60 and SmD was demonstrated. The cross-reactive epitope was mapped to nonhomologous regions on Ro60(481-505) and SmD(88-102). Five mAbs specifically recognized apoptotic cells, demonstrated variable levels of cross-reactivity toward other nonhomologous ribonucleoprotein targets and bound multiple, nonoverlapping and nonhomologous epitopes on Ro60. Our study demonstrates that cross-reactivity between frequently targeted autoantigens is an important aspect of human systemic autoimmune responses. The presence of multiple cross-reactive epitopes on Ro60 might be important for the generation of anti-Ro60 Ab in SLE patients and in normal individuals displaying no evidence of clinical disease.

Amino Acid Sequence↗
PubMed2005

New biodegradable amphiphilic block copolymers of epsilon-caprolactone and delta-valerolactone catalyzed by novel aluminum metal complexes. II. Micellization and solution to gel transition.

In our previous study [J. Yang, L. Jia, L. Yin, J. Yu, Z. Shi, Q. Fang, A. Cao, Macromol. Biosci. 2004, 4, 1092.], new biodegradable copolymers of diblock methoxy poly(ethylene glycol)-block-poly(epsilon-caprolactone) and methoxy poly(ethylene glycol)-block-poly(delta-valerolactone), and triblock poly(epsilon-caprolactone)-block-poly(ethylene glycol)-block-poly(epsilon-caprolactone) and poly(delta-valerolactone)-block-poly(ethylene glycol)-block-poly(delta-valero-lactone) bearing narrow molecular weight distributions and well-defined block architectures were reported to be prepared with our original aluminum metal complex templates. This work will continue to report new investigations on their water solubility, and reversible thermal responsive micellization and solution to gel transition in distilled water. Among the new synthesized copolymers (P1-P23), seven diblock or triblock samples (P3, P6, P7, P11, P12, P19, and P21) with higher hydrophilic building block populations were revealed to be water soluble under ambient temperature. By means of UV spectrophotometer attached with a thermostat, important parameters as critical micellization mass concentrations (CMCs) and critical micellization temperatures (CMTs) were characterized for these new amphiphile dilute aqueous solution with the aid of an lipophilic organic dye probe of 1,6-diphenyl-1,3,5-hexatriene (DPH). Furthermore, the critical gelation temperatures (CGTs) were simultaneously investigated for these water-soluble block copolymers via a tube tilting method. It was found that the CMC, CMT, and CGT were strongly affected by the population and nature of the hydrophobic building blocks, and a higher hydrophobicity of the new amphiphilic block copolymer finally led to lower CMC and CMT, and higher CGT. In addition, the salts of KBr and NaCl were found to play as a salt-out effect on the solution to gel transition for the diblock P6 and triblock P11, exhibiting an interesting tunable gelation temperature close to 35-42 degrees C. These results will pave new possibility for the synthesized block structural amphiphiles as potential biomaterials to be applied in vivo.

Alum Compounds↗
PubMed2005

New enantiomeric polylactide-block-poly(butylene succinate)-block-polylactides: syntheses, characterization and in situ self-assembly.

In situ self-assemblies of new biodegradable triblock PLLA-b-PBS-b-PLLA and PDLA-b-PBS-b-PDLA have been investigated in acetonitrile solution. At first, two series of PLLA-b-PBS-b-PLLA and PDLA-b-PBS-b-PDLA, respectively denoted as the P and Q triblock copolyester series, were prepared with fixed PBS block ((overline) M(n,NMR) = 6.9 kDa) and diverse enantiomeric PLLA/PDLA blocks. Further, their chemical structures and thermal properties were characterized by means of titration, nuclear magnetic resonance spectroscopy (NMR), gel permeation chromatography (GPC), polarimeter, wide-angle X-ray diffraction (WAXD) and thermal analytical instruments. When mixing the synthesized enantiomeric copolyester pairs denoted as P(1)/Q(1) - P(8)/Q(8) in acetonitrile solution at 60 degrees C, in situ self-assemblies were found to happen for the P(4)/Q(4) to P(8)/Q(8) pairs, bearing longer enantiomeric PLA block lengths. DSC and WAXD analysis of the self-assembled microparticles demonstrated that PLLA/PDLA racemic crystals were formed for the P(5)/Q(5) - P(8)/Q(8) systems, as evidenced by their melting points over 200 degrees C, and a new X-ray diffraction peak detected at 2theta = 11.8 degrees . Moreover, morphological studies by scanning electron microscopy (SEM) indicated the formation of disk- or platelet-like microparticles. It was noted that the diameters of the microparticles self-assembled in situ decreased from 1.28-1.50 mum down to 480-660 nm, through tailoring the enantiomeric PLA block length. Other factors, such as a central PBS block, the enantiomeric block length and the preparation conditions were suggested to play important roles in the in situ self-assembly of these enantiomeric triblock copolyesters. These results provide a facile way to self-assemble hydrophobic, biodegradable microparticles, through tuning the important van der Waals stereocomplexation interactions between two enantiomeric blocks in solution.

Acetonitriles↗
PubMed2004

A novel approach to biodegradable block copolymers of epsilon-caprolactone and delta-valerolactone catalyzed by new aluminum metal complexes.

The chemical preparation of structurally well-defined biodegradable amphiphilic block copolymers is now of great interest for biomedical applications and the fundamental mimetic study of biomacromolecule self-assembly. For this purpose, in this study, (R,R)-N,N'-bis(3-tert-butylsalicylidene)-1,2-cyclohexanediamine 2 as a ligand was first synthesized from 1,2-cyclohexanediamine (DACH) and was allowed to further react with AlMe3, leading to a precursor compound 3. Then, the novel five-coordinated aluminum metal complexes 4-6 and 7-8 were prepared with good yields of 80-90%, bearing various molar mass monofunctional methoxy-poly(ethylene glycol) MPEG and difunctional poly(ethylene glycol) PEG as the alkoxy moieties, respectively. By means of nuclear magnetic resonance spectrometry (NMR), mass spectrometry (MALDI-FTMS) and Fourier Transform infrared spectrometry (FT-IR), new metal aluminum complexes 4-8 were characterized as having distinct chemical structures. Utilizing the synthesized metal complexes 4-8 as novel coordination polymerization catalytic templates, biodegradable amphiphilic MPEG-b-PCL, MPEG-b-PVL, PCL-b-PEG-b-PCL and PVL-b-PEG-b-PVL were synthesized with good control of the molecular weight distribution via the ring opening polymerization of epsilon-caprolactone and delta-valerolactone monomers at 100 degrees C in toluene. In addition, the chemical and crystalline structures and the thermal properties of these block biodegradable copolymers were analyzed by means of NMR, gel permeation chromatography (GPC), wide-angle X-ray diffraction (WAXD), differential scanning calorimetry (DSC) and thermal gravimetric analysis (TGA). It was found that the melting points and crystallinities of the block copolymers synthesized strongly depended on the molecular structures of the polyether and polyester building blocks. Only one glass transition stage was detected, indicating good chain/segmental miscibility between the hydrophilic MPEG/PEG and hydrophobic PCL/PVL blocks in the non-crystalline regions. Moreover, TGA analysis exhibited typical two-step decomposition profiles with the weight-loss percentages in good agreement with block compositions from NMR calculations.

Aluminum↗
PubMed2004

[Value of radiotherapy and chemotherapy after SEMS implantation operation in patients with malignant esophageal stricture].

BACKGROUND & OBJECTIVE: Owing to the lack of a systematic comparative study, it still remains a controversial issue whether a patient with malignant esophageal tumor causing dysphagia should receive radiotherapy or/and chemotherapy after the SEMS (self-expanding esophageal metal stents) implantation operation. The present paper aims at a careful study of this field. METHODS: A total of 283 specimens were divided into two groups, namely, the group merely receiving the SEMS implantation operation (Group 1, n=91) and the group receiving a combined treatment of the SEMS implantation operation followed by radiotherapy /and chemotherapy (Group 2, n=192). The survival time of the patients in the two different groups was compared and the factors associated with the survival time were analyzed by means of Cox regression method. RESULTS: The survival time of the patients in group 2 was apparently much longer than that of the patients in group 1 (499.27+/-239.7 days and 312.81+/-192.77 days, respectively, P< 0.0001). The factors associated with the survival time included the choice of treatment method, incidence of distant metastasis and lymph node metastasis, formation of esophageal fistula and the location of diseased area. Among them the relative risk of treatment method is the highest. CONCLUSION: A combined treatment of SEMS implantation operation followed by radiotherapy and chemotherapy is significantly associated with the effect of treatment and will undoubtedly prolong the life of the patients with malignant esophageal tumor causing dysphagia.

Adult↗
PubMed2003

Improved detection of Salmonella spp. in foods by fluorescent in situ hybridization with 23S rRNA probes: a comparison with conventional culture methods.

This report describes a new technique for the detection and identification of Salmonella species in food with the use of fluorescent in situ hybridization (FISH) with 23S rRNA-targeted oligonucleotide probes. Two species-specific 23S rRNA-targeted oligonucleotide probes (Sal-1 and Sal-3) were selected, and one (Sal-544) was newly designed. The relative specificities of these probes were compared with those of bacterial 23S rRNA sequences from the GenBank database and tested by in situ hybridization with bacterial cell smears of pure cultures. Fifty-one tested reference strains of Salmonella serovars belonging to subspecies I (enterica) hybridized with these probes. No cross-reactions with 46 other strains of the family Enterobacteriaceae or with another 14 bacterial strains from other families were observed. Storage of a Salmonella Panama test strain under various environmental conditions (2, 5, and 15% NaC1; -20 degrees C, 4 degrees C, and room temperature; pHs of 3.3 to 7.4) did not adversely affect the FISH method. No matrix effects were observed with 18 different kinds of foods. FISH was able to detect Salmonella spp. in 52 (probe Sal-1), 56 (probe Sal-3), and 35 (probe Sal-544) of 225 naturally contaminated food samples after 16 h of incubation in a preenrichment broth. When conventional culture and detection methods were used, Salmonella could be isolated from only 30 of these 225 samples. In contrast, FISH failed to identify Salmonella in only two of the culture-positive samples when Sal-1 and Sal-3 were used and in only three of the culture-positive samples when Sal-544 was used.

Animals↗
PubMed2003

[Factor Xa inhibitory assay to detect plasma heparin concentrations during and after cardiopulmonary bypass].

OBJECTIVE: For establishment and application of Xa Factor Inhibitory Assay to detect plasma heparin concentrations during and after cardiopulmonary bypass (CPB) and to evaluate the treatment with low-dose protamine reversal of heparin. METHODS: Venous blood samples were drawn from 25 patients with rheumatic valvular disease undergoing valvular replacement at different points (before CPB, after 5 min of heparinization, at termination of CPB, after 10 min, 1 hr and 5 hr of protamine reversal of heparin), and the plasma heparin concentrations were detected. RESULTS: The mean of plasma heparin concentration was the highest (13.16 U/ml) after 5 min of heparinization. At termination of CPB, it decreased (11.06 U/ml) and was significantly different from the concentrations at other points (P < 0.05). After 10 min of low-dose protamine reversal of heparin, the heparin concentration (0.45 U/ml) decreased to the same as that before CPB and continued to be stable at 1 hr and 5 hr; there was no significant difference in heparin concentration between these 4 points (P > 0.05). The highest batch CV in standard curves was 11.65%; the lowest was 0.37%. CONCLUSION: Factor Xa Inhibitory Assay is of good accuracy and repetition. The results from its clinical application demonstrated that the plasma heparin concentration of the patient at termination of CPB should be used for reference in determining the dose level of protamine for that every patient subjected to CPB.

Adult↗
PubMed2002

Protein sequence comparison based on the wavelet transform approach.

A protein's chemical properties, the chain conformation, the function of the protein and its species specificity are determined by the information contained in the amino acid sequence. Proteins of similar functions have at some level sequential identical amino acid sequences. The closer the phylogenetic relationship, the more similar are the sequences. To find the similarities between two or more protein sequences is of great importance for protein sequence analysis. The differences in the amino acid sequences permit the construction of a family tree of evolution. In this work, a comparison method was devised that is capable of analysing a protein sequence 'hierarchically', i.e. it can examine a protein sequence at different spatial resolutions. Based on a wavelet decomposition of protein sequences and a cross-correlation study, a sequence-scale similarity concept is proposed for generating a similarity vector, which renders the comparison of two sequences feasible at different spatial resolutions (scales). This new similarity concept is an expansion of the conventional sequence similarity, which only takes into account the local pairwise amino acid match and ignores the information contained in coarser spatial resolutions.

Amino Acid Sequence↗
PubMedDate not supplied

Preparation and crystallization kinetics of new structurally well-defined star-shaped biodegradable poly(L-lactide)s initiated with diverse natural sugar alcohols.

This study presents syntheses, structural characterization, and crystallization kinetic investigation of new structurally well-defined star-shaped poly(l-lactide)s (PLLAs). First, a series of new 3- to 6-arm star-shaped PLLAs were synthesized through SnOct(2) catalyzed ring-opening polymerization of (l)-lactide with natural sugar alcohols of glycerol, erythritol, xylitol, and sorbitol as the favorable initiators. Subsequently, their chemical structures were characterized by means of GPC, NMR, and viscometer with respect to the star-shaped structures, demonstrating the well-defined arm structures as evidenced on the g(1/2)/g' values, where g and g' denote the ratios of mean-square radius of gyration and intrinsic viscosity of a star-shaped polymer to those of a linear structural reference with similar absolute molecular weight. Furthermore, spherulite morphologies and growth rates were studied by a polarized microscopy (POM) for the synthesized star-shaped PLLAs with different molecular weights, and it was found that the more arms of a star-shaped PLLA finally resulted in a lower spherulite growth rate. With regard to the crystallization kinetics of these star-shaped PLLAs, isothermal and nonisothermal crystallization were examined by differential scanning calorimeter (DSC). It was found that Avrami exponent n values of isothermal crystallization were almost independent of the isothermal crystallization temperature T(c) for different series of star-shaped PLLAs. In contrast, the values of Avrami exponent n were observed to strongly depend on the star-shaped structures with different arms, implying their distinct nucleation mechanisms, and the more arms of a star-shaped PLLA led to a slower isothermal crystallization rate. On the basis of a modified Avrami equation, new light was shed on the nonisothermal crystallization kinetics for the star-shaped PLLAs, and the activation energies were found to vary from 146.86 kJ/mol for the linear PLLA EG-3 to 221.23 kJ/mol of the star-shaped S-3, demonstrating much decreased crystallizabilities of star-shaped PLLAs with more arms.

Biodegradation, Environmental↗