Biomedical subjects

L W Chan

Publications and source records attributed to L W Chan.

At least 19 recordsLinked to original sources

PubMed2007

First-trimester combined screening for trisomy 21 in a predominantly Chinese population.

OBJECTIVE: To examine the effectiveness of first-trimester fetal trisomy 21 screening using a combination of maternal age, nuchal translucency thickness (NT) and maternal serum free beta-human chorionic gonadotropin (beta-hCG) and pregnancy-associated plasma protein-A (PAPP-A) levels in a predominantly Chinese population in Hong Kong. METHODS: This was a prospective study over a 1.5-year period of 2990 women who underwent combined screening for trisomy 21 between 11+0 and 13+6 weeks of gestation in a university fetal medicine unit. NT was measured according to the criteria set by The Fetal Medicine Foundation (FMF), maternal serum free beta-hCG and PAPP-A levels were measured, and the risk of trisomy 21 was calculated using The FMF's algorithm. Fetal karyotyping was advised when the risk was 1 : 300 or above. All subjects were followed up for pregnancy and fetal outcome. RESULTS: Of the 2990 women who underwent the screening program, 99% were Chinese. There were 57 twin pregnancies, giving a total of 3047 fetuses. Thirty-one percent of the women were 35 years old or above. One hundred and eighty-five (6.1%) fetuses were screen-positive; this included 14 cases of trisomy 21 and 17 cases of other chromosomal abnormalities. The positive predictive value was 16.7%. Among the 2862 screen-negative fetuses, only 18 (0.6%) cases had an unknown fetal outcome. There were no cases in which trisomy 21 was missed and the infant was liveborn. CONCLUSION: First-trimester combined screening for fetal trisomy 21 is highly effective among Chinese subjects.

Adult↗

PubMed2006

Use of swirling airflow to enhance coating performance of bottom spray fluid bed coaters.

As there is strong interest in coating increasingly smaller particles or pellets for use in compacted dosage forms, there is a need for better small particle coating systems. This study explored the use of swirling airflow to enhance the performance of the bottom spray coating system. Firstly, pellet coating in the non-swirling airflow of conventional Wurster coating was compared with that of swirling airflow in precision coating under standardized conditions. Secondly, precision coating was studied in greater details at different airflow rates (60-100m(3)/h) and partition gaps (6-22mm). Precision coating was found to have higher Reynolds numbers (Re) than Wurster coating, indicating higher turbulence. It produced coated pellets of better properties than Wurster coating, having less agglomeration and gross surface defects, more uniform coats, increased flow and tapped density, and slower drug release. Higher surface roughness did not affect the yield. In precision coating, increasing airflow rates decreased the degree of agglomeration but had minimal effect on pellet quality attributes (colour intensity, colour uniformity and surface roughness) and yields. Increasing partition gaps increased the degree of agglomeration proportionally, but this effect was small. However, greater changes in yield, surface roughness, colour intensity and colour uniformity were detected. This study showed that precision coating, while having a higher drying ability, was able to maintain the same yield and produce coated pellets with superior quality compared to Wurster coating. In precision coating, airflow rate had greater influence on the drying of pellets while partition gap had greater influence on pellet quality attributes.

Air Movements↗

PubMed2006

Comparative study of the fluid dynamics of bottom spray fluid bed coaters.

Fluid dynamics of pellets processed in bottom spray traditional Wurster coating and swirl accelerated air (precision) coating were compared with the intent to understand and facilitate improvements in the coating processes. Fluid dynamics was described by pellet mass flow rate (MFR) obtained using a pellet collection system and images captured using high speed photography. Pellet flow within the partition column was found to be denser and slower in Wurster coating than in precision coating, suggesting a higher tendency of agglomeration during the coating process. The influence of partition gap and load on the MFR indicated that the mechanism of transport of pellets into the coating zone in precision coating depended on a strong suction, whereas in Wurster coating, pellets were transported by a combination of peripheral fluidization, gravity, and weak suction pressure. In precision coating, MFR was found to increase uniformly with air flow rate and atomizing pressure, whereas MFR in Wurster coating did not correlate as well with air flow rate and atomizing pressure. This demonstration showed that transport in precision coating was air dominated. In conclusion, fluid dynamics in precision coating was found to be air dominated and dependent on pressure differential, thus it is more responsive to changes in operational variables than Wurster coating.

Capsules↗

PubMed2006

Investigation of wetting behavior of nonaqueous ethylcellulose gel matrices using dynamic contact angle.

PURPOSE: This study reports the development of a method based on dynamic contact angle to investigate the wetting behavior of non-aqueous ethylcellulose (EC) gel matrices intended for topical drug delivery. METHODS: Non-aqueous gel matrices were prepared from the three fine particle grades of EC and propylene glycol dicaprylate/dicaprate. Dynamic contact angle measurements of sessile drops of water and isopropylmyristate (IPM) on EC gel matrices were performed using a dynamic contact angle analyzer equipped with axisymmetric drop shape analysis of the sessile drop images. Gel density was determined by weighing known volumes of gel samples. RESULTS: The EC gel matrices were wetted by both water and IPM, with much higher wettability by the latter. Increased EC concentration and polymeric chain length decreased the extent and rate of wetting. Linear correlation was observed between wetting parameters and rheological as well as mechanical properties of EC gel matrices. CONCLUSIONS: The EC gel matrices exhibited both hydrophilic and lipophilic properties, with predominance of the latter. The extent and rate of wetting was governed by a balance of chemical and physical characteristics of the gel. EC gel matrices showed desirable wetting behavior in their function as a moisture-barrier, bioadhesive and vehicle for topical drug delivery.

Adhesiveness↗

PubMed2006

First-trimester maternal serum levels of placental hormones are independent predictors of second-trimester fetal growth parameters.

OBJECTIVE: To determine whether first-trimester maternal serum levels of pregnancy-associated plasma protein-A (PAPP-A) and free beta-human chorionic gonadotropin (fbeta-hCG) are independent predictors of second-trimester fetal growth parameters. METHODS: This was a cohort study over a 1-year period involving 594 Chinese women who underwent both first-trimester combined screening for Down syndrome and a routine second-trimester ultrasound examination. Maternal PAPP-A and fbeta-hCG levels (expressed in log(10) of multiples of median (MoM)), crown-rump length (CRL) (expressed in standardized Z-score (Z-CRL)), and maternal height and weight, were correlated with the Z-score of biparietal diameter (Z-BPD), femur length (Z-FL) and abdominal circumference (Z-AC) measured in the second trimester, using the Pearson test, followed by multiple regression analysis. RESULTS: Z-BPD, Z-FL and Z-AC were positively correlated with log(10) PAPP-A MoM, CRL and maternal height (all P < 0.05), while log(10) fbeta-hCG MoM was negatively correlated with Z-AC (P < 0.05). After controlling for the effects of CRL, maternal height and weight, log(10) PAPP-A MoM was found to be an independent positive predictor of Z-FL (r = 0.797, P < 0.001) and Z-AC (r = 0.305, P = 0.049), and log(10) fbeta-hCG MoM was an independent negative predictor of Z-FL (r = -0.381, P = 0.023) and Z-AC (r = -0.418, P = 0.002). Neither hormonal level was related to Z-BPD. CONCLUSIONS: First-trimester PAPP-A and fbeta-hCG are independent factors that influence subsequent fetal growth. PAPP-A level is positively correlated with FL and AC in the second trimester, while fbeta-hCG level is negatively correlated with them. However, BPD is not affected by either of the hormones.

Adult↗

PubMed2006

First-trimester maternal serum level of pregnancy-associated plasma protein-A is an independent predictor of fetal maxillary bone length.

OBJECTIVE: To derive a nomogram of fetal maxillary bone length (MAX) for a Chinese population and to study whether first-trimester maternal serum levels of pregnancy-associated plasma protein-A (PAPP-A) is an independent predictor of fetal MAX. METHODS: This was a prospective observational study over 10 months examining Chinese women with a singleton pregnancy who attended the first-trimester screening program for Down syndrome. The subjects had the fetal crown-rump length (CRL), nuchal translucency, MAX, maternal serum PAPP-A and free beta-human chorionic gonadotropin (fbeta-hCG) levels measured. A nomogram of MAX was derived using normal pregnancies with reliable dates. The correlations between MAX, CRL, PAPP-A and fbeta-hCG levels were studied, after correction for gestational dependency using Z-score transformation for the ultrasound markers (Z-MAX and Z-CRL), and logarithmic transformation of multiple of gestation-specific medians for the biochemical markers (log10PAPP-A multiples of the median (MoM) and log10fbeta-hCG MoM), using the Pearson test and multiple regression analysis. RESULTS: During the study period, 607 Chinese women met the inclusion criteria. The mean gestational age at the first-trimester screening was 12 + 4 weeks (SD, 4 days). Curve estimation analysis showed that a linear relationship fit best between MAX and CRL (MAX (mm) = -0.01 + 0.101 * CRL (mm); r = 0.826; P < 0.0001), and between MAX and gestational age (MAX (mm) = -8.465 + 0.170 * gestational age (day); r = 0.754; SD = 0.71; P < 0.0001). There were significant positive correlations between Z-MAX and Z-CRL (r = 0.627; P = < 0.0001), Z-MAX and log10PAPP-A MoM (r = 0.239; P = < 0.0001). Multiple regression analysis showed that both Z-CRL (P = < 0.0001) and log10 PAPP-A MoM (P = 0.048) were independent predictors for Z-MAX. CONCLUSION: Both CRL and maternal levels of PAPP-A are independent predictors of the fetal MAX measured during the first trimester. The positive correlation between PAPP-A levels and fetal MAX is consistent with the known biological function of PAPP-A on bone growth. This association must be adjusted for when both PAPP-A and MAX are combined for screening of Down syndrome.

Asian People↗

PubMed2006

Prediction of intrapartum Cesarean delivery for non-reassuring fetal status after a successful external cephalic version by a low pre-version pulsatility index of the fetal middle cerebral artery.

OBJECTIVE: To determine whether a pre-version Doppler assessment of fetal cerebral and umbilical blood flow can predict the ultimate need for intrapartum Cesarean delivery after a successful external cephalic version (ECV). METHODS: A prospective observational study on women undergoing ECV between 36 and 38 gestational weeks was performed over a 5-year period. The pulsatility index (PI) of the fetal middle cerebral artery (MCA) and umbilical artery, heart rate and amniotic fluid index were measured before ECV. Women who had successful ECV were then divided into three groups according to the mode of delivery: (1) vaginal delivery, (2) intrapartum Cesarean delivery for poor progress and (3) intrapartum Cesarean delivery for non-reassuring fetal status. The fetal blood flow parameters were compared between the groups. Potential predictors were further analyzed using receiver-operating characteristics curves. RESULTS: Of 174 women with successful ECV, 140 (80.5%) had vaginal delivery, 19 (10.9%) required emergency intrapartum Cesarean delivery for non-reassuring fetal status and 15 (8.6%) for poor progress. MCA-PI was significantly lower in the group with non-reassuring fetal status. MCA-PI is predictive of intrapartum Cesarean delivery (area under the curve = 0.68, P = 0.021). The sensitivity and specificity at a cut-off level of 1.4 were 62.5% and 76%, respectively, while at a cut-off level of 1.5 they were 68.8% and 63.5%, respectively. CONCLUSION: Intrapartum Cesarean delivery for non-reassuring fetal status after successful ECV is associated with a lower pre-version fetal MCA-PI.

Breech Presentation↗

PubMed2005

Development of novel nonaqueous ethylcellulose gel matrices: rheological and mechanical characterization.

PURPOSE: This study reports the rheological and mechanical characterization of novel non-aqueous ethylcellulose gel matrices intended for topical drug delivery. An attempt was also made to explain the molecular interaction within the gel systems from a molecular conformational approach. METHODS: Nonaqueous gel matrices were prepared from three fine particle grades of ethylcellulose and propylene glycol dicaprylate/dicaprate. Continuous and oscillatory shear rheometry was performed using a cone-and-plate rheometer and mechanical characterization was performed using a universal tensile tester. RESULTS: The gel matrices exhibited prominent viscoelastic behaviour, yield stress and thixotropy. Rheological and mechanical properties showed significant upward trends with increased polymeric chain length and polymer concentrations. Good linear correlations were obtained between rheological and mechanical properties. The solvent molecular conformation was found to play a role in affecting the formation of gel networks via intermolecular hydrogen bonding between ethylcellulose polymer chains. CONCLUSIONS: Ethylcellulose was successfully formulated as a nonaqueous gel with propylene glycol dicaprylate/dicaprate. The novel nonaqueous gel exhibited rheological profiles corresponding to a physically cross-linked three dimensional gel network, with suitable mechanical characteristics for use as a vehicle for topical drug delivery. Molecular conformation of the solvent was found to influence the molecular interactions associated with formation of ethylcellulose gel networks.

Adhesiveness↗

PubMed2005

Effect of oil loading on microspheres produced by spray drying.

Oil-loaded microspheres were produced by spray drying emulsions consisting of fish oil and modified starch suspensions with different oil loadings. The emulsion stability was assessed by oil droplet size analysis. Microspheres were characterized in terms of size, morphology, yield and microencapsulation efficiency. It was found that an increase in oil loading resulted in emulsions containing larger oil droplets. This corresponded with larger mean microsphere diameters and rounder microspheres. However, high oil loadings produced lower yields and affected microencapsulation efficiencies.

Desiccation↗

PubMed2005

Investigation of the release of aspirin from spray-congealed micro-pellets.

The release behaviour of aspirin from spray-congealed hydrogenated soybean oil micro-pellets of different sizes was studied. The purpose of this study was to investigate the effect of particle size of micro-pellets on the drug release profile and mechanism. Micro-pellets produced were sieved into several fractions and their drug content and dissolution profiles in two media were determined. The dissolution mechanism was studied by fitting the data to release kinetic models. Micro-pellets with high encapsulation efficiency were successfully produced. The micro-pellets were able to sustain the release of aspirin in pH 1.2 and pH 6.8 dissolution media. As particle size of micro-pellets increased, the drug release rate decreased. The drug release mechanism was affected by the size of micro-pellets. Micro-pellets in the range of 90-250 microm tended to follow the first order or Higuchi model. However, micro-pellets in the range of 250-355 microm were found to follow zero-order release model. This result showed that drug release could be modified by controlling the size of micro-pellets and that controlled release of drug might be achieved by using larger size micro-pellets.

Anti-Inflammatory Agents, Non-Steroidal↗

PubMed2005

Influence of partially cross-linked alginate used in the production of alginate microspheres by emulsification.

Spherical and discrete calcium alginate microspheres had been produced by the emulsification technique. The microencapsulation process was highly efficient, but drug release from microspheres was rapid. A more orderly chain arrangement of the polymeric chains would give rise to a stronger and less permeable matrix capable of sustaining drug release. Therefore, the potential of using partially cross-linked alginate in the production of microspheres by emulsification was explored. The size and roundness of the microspheres, its drug content and drug release property were determined. The more viscous alginate solutions when reacted with more calcium salt added resulted in larger microspheres produced. Microspheres made from partially cross-linked alginate exhibited lower drug content and higher T75% values in drug release studies. This was due to decreased flexibility of the polymer chains which were partially held together by calcium ions, reducing subsequent interaction with the calcium ions resulting in lower drug entrapment efficiency and a more permeable microsphere matrix.

Alginates↗

PubMed2005

The impact of urinary incontinence on quality of life among women in Hong Kong.

OBJECTIVE: To determine the prevalence of female urinary incontinence in Hong Kong and its impact on quality of life. DESIGN AND SETTING: Territory-wide telephone survey in Hong Kong. PARTICIPANTS: Hong Kong women aged 10 to 90 years accessed by fixed residential telephone lines between June 2001 and July 2002. MAIN OUTCOME MEASURES: The prevalence of urinary symptoms was assessed using telephone interview. The urinary symptoms investigated were as listed in a validated Chinese version of Urogenital Distress Inventory Short Form (UDI-6). The impact on quality of life was quantified using a validated Chinese version of Incontinence Impact Questionnaire Short Form (IIQ-7). RESULTS: There were 749 valid respondents (response rate, 24.4%). Urinary symptoms were reported by 52% of women (95% confidence interval, 48.9-56.0%), of whom 12% believed it impaired their quality of life. Stress urinary incontinence was reported by 34% (95% confidence interval, 28.7-38.9%). Social (5.1%; 95% confidence interval, 2.8-7.4%) and emotional (5.6%; 95% confidence interval, 3.3-7.9%) factors were the quality-of-life areas most impacted by urinary incontinence. CONCLUSIONS: Urinary symptoms are common among Hong Kong women. Quality of life is consequently impaired in 12% of affected women.

Adolescent↗

PubMed2004

Expression and functional study of estrogen receptor-related receptors in human prostatic cells and tissues.

Estrogen receptor-related receptors (ERRs; alpha, beta, gamma) are orphan nuclear receptors and constitutively active without binding to estrogen. Like estrogen receptors (ERs), ERRs bind to estrogen receptor elements and estrogen receptor element-related repeats. Growing evidence suggests that ERRs can cross-talk with ERs in different cell types via competition for DNA sites and coactivators. We hypothesize that ERRs might play regulatory roles in normal and neoplastic prostatic cells by sharing similar ER-mediated pathways or acting independently. In this study, we investigated mRNA and protein expression patterns of three ERR members in normal human prostate epithelial cells, established cell lines, cancer xenografts, and prostatic tissues. Additionally, effects of transient transfection of ERRs on prostatic cell proliferation and ER expression were also examined. RT-PCR showed that ERRalpha and ERRgamma transcripts were detected in most cell lines and xenografts, whereas ERRbeta was detected in normal epithelial cells and few immortalized cell lines but not in most cancer lines. Similar results were demonstrated in clinical prostatic specimens. Western blottings and immunohistochemistry confirmed similar expression patterns that ERR proteins were detected as nuclear proteins in epithelial cells, whereas their expressions became reduced or undetected in neoplastic prostatic cells. Transient transfection confirmed that ERRs were expressed in prostatic cells as nuclear proteins and transcriptionally active in the absence of estradiol. Transfection results showed that overexpression of ERRs inhibited cell proliferation and repressed ERalpha transcription in PC-3 cells. Our study shows that ERRs, which are coexpressed with ERs in prostatic cells, could regulate cell growth and modulate ER-mediated pathways via interference on ERalpha transcription in prostatic cells.

Adolescent↗

PubMed2004

Roller compaction of crude plant material: influence of process variables, polyvinylpyrrolidone, and co-milling.

Roller compaction of a milled botanical (Baphicacanthus cusia) with and without a binder, polyvinylpyrrolidone (PVP) was conducted. Effects of co-milling on binder function and flowability of the powder blend was also investigated. Flakes were comminuted, and the size and size distribution, friability, Hausner ratio, and Carr index of the granulations were determined. Crude herb should be reduced to a suitable size for it to be successfully roller compacted. Larger-sized and less friable granules were obtained with decreasing roller speed. Addition of PVP affected the flowability and binding capacity of the herbal powder blend, which influenced size and friability of the granules. Co-milling of PVP with the herbal powder enhanced the flow of the blends and the effectiveness of the binder, which contributed favorably to the roller-compacted product. Roller compaction is a convenient and cost-effective granulating technique suitable for milled botanicals. Co-milling can be used to improve the properties of roller-compacted products.

Apocynaceae↗

PubMed2004

Intrapartum cesarean delivery after successful external cephalic version: a meta-analysis.

OBJECTIVE: We sought to estimate whether the risk of intrapartum cesarean delivery is higher in pregnancies after successful external cephalic version. DATA SOURCES: We searched the MEDLINE, PubMed, EMBASE, and Cochrane Library databases to identify relevant studies. Abstracts of the American College of Obstetricians and Gynecologists Annual Clinical Meeting and the Society for Maternal-Fetal Medicine Annual Meeting were searched by hand. STUDY SELECTION: Studies published between 1980 and 2002 that provided data allowing us to estimate the cesarean rate in both pregnancies after successful version and spontaneous cephalic-presenting pregnancies were selected. TABULATION, INTEGRATION, AND RESULTS: Relative risks (RRs) and 95% confidence intervals (CIs) between the 2 compared groups were calculated. We used a meta-analysis to assess the heterogeneity of the studies and to combine the results from the included studies. Six eligible studies were identified. The cesarean rate was 27.6% in pregnancies after successful version and 12.5% in cephalic-presenting pregnancies. The combined RR and 95% CI was 2.04 (1.43-2.91). The increased cesarean rate in pregnancies after successful version was accounted for primarily by a higher incidence of emergency cesarean delivery for dystocia and fetal distress; the RR (95% CI) for these 2 events was 2.19 (1.38-3.48) and 2.10 (1.18-3.75), respectively. CONCLUSION: The intrapartum cesarean delivery rate after successful version is 2 times that in pregnancies where there is spontaneous cephalic presentation. Pregnancies after successful version should not be considered the same as a normal pregnancy.

Cesarean Section↗

PubMed2004

Mitochondrial DNA mutations in chemical carcinogen-induced rat bladder and human bladder cancer.

Mitochondrial (mt) DNA mutations have been described recently in different tumors, whereas similar studies focusing on bladder cancer are scarce. In an effort to understand the significance of mtDNA mutations in bladder cancer, we investigated the mtDNA alterations in both clinical human bladder cancer and in a carcinogen-induced rat bladder cancer model. Human bladder cancer tissues were obtained by radical cystectomy and transurethral resection of bladder tumors. Rat bladder tumors were induced in SD rats by treatment with N-butyl-N-(4-hydroxybutyl) nitrosamine in drinking water for 24-28 weeks. Genomic DNA was extracted from tumor specimens and microdissected normal bladder mucosae. Mitochondrial genes and D-loop region were amplified by PCR. The amplified PCR fragments were either cloned into plasmid vector or used for direct DNA sequencing. The results of DNA sequence revealed numerous point mutations in the non-coding D-loop region and different mtDNA genes in both human and rat bladder cancers. In addition, we also detected deletions of variable lengths in mononucleotide repeats in the D-loop region, ND2, ATPase 8 and COIII genes in human bladder cancer samples. Our results show that mtDNA exhibits a high rate of mutations in both human and rat bladder cancers. We also demonstrate that the repetitive sequences of mononucleotides within the mt genome are unstable and subjected to deletions. The high incidence of mtDNA mutations in bladder cancer suggests that mtDNA and mitochondria could play an important role in the process of carcinogenesis and also mtDNA could be valuable as a marker for early bladder cancer diagnosis.

Animals↗

PubMed2003

One-year urodynamic outcome and quality of life in patients with concomitant tension-free vaginal tape during pelvic floor reconstruction surgery for genitourinary prolapse and urodynamic stress incontinence.

The aim of the study was to examine the 1-year urodynamic outcome and quality of life in patients who have had concomitant tension-free vaginal tape insertion during pelvic floor reconstruction surgery. The medical notes of a retrospective cohort of 45 patients who had undergone tension-free vaginal tape together with pelvic floor reconstruction surgery were reviewed. The operative information, the results of the urodynamic studies and the change in the quality-of-life scores 1 year after surgery were examined. The quality of life was assessed with both general and disease-specific quality-of-life questionnaires (General Health Questionnaire (GHQ-12), Urogenital Distress Inventory (UDI-6), Incontinence Impact Questionnaire (IIQ-7)). Patient satisfaction was assessed with the validated Chinese version of the Client Satisfaction Questionnaire (CSQ). Forty-five patients underwent tension-free vaginal tape insertion together with pelvic floor reconstruction surgery. The overall objective cure rate was 43%. There was a significant improvement in the disease specific quality-of-life assessment (UDI-6 score 38.3-15.5; P<0.01) and (IIQ-7 score 15.0-4.0; P<0.01). The patients who had a concomitant cystocele repair had a worse objective cure rate than patients without concomitant cystocele repair (38% vs 67%; P=0.19).

Aged↗

PubMed2003

Use of a fluidized bed hammer mill for size reduction and classification: effects of process variables and starting materials on the particle size distribution of milled lactose batches.

The process capability of a fluidized bed hammer mill was investigated with respect to four process variables, namely, rotational speeds of beater system and classifier wheel, airflow rates and length of grinding zones, as well as the particle size and flow property of the starting materials. The size distributions of all the milled lactose batches could be fitted to the Rosin Rammler distribution (RRD) function. The characteristic particle size (De) and uniform coefficient (n), which were derived from the RRD function, complemented the size at the 99th percentile of the cumulative undersize distribution (D99) to characterize the lactose batches. Lower De and D99 values indicate a finer powder while a higher n value indicates a narrower size distribution. The beater speed played a critical role. Increasing the beater speed from 12000 to 21000 rpm generally resulted in an increase in n and a decrease in D99 values due to the greater amount of milling energy supplied. The particle size and flow property of the starting material also played an important role at beater speed of 12000 rpm, where the lowest amount of milling energy was supplied. When a higher amount of milling energy was provided, the effect of particle size of the starting material was less significant. The other process variables exerted varying effects. Increasing the classifier wheel speed from 5000 to 15000 rpm decreased the De and D99 and increased the n values of the milled lactose batches, provided sufficient milling energy was supplied to the lactose particles. Changing airflow rates from 80 to 90 m3/h generally resulted in larger De and D99 values and lower n values as the higher airflow rate provided greater airflow-induced kinetic energy that facilitated the passage of lactose through the classifier wheel. However, changing the long grinding zone to a short one did not significantly affect the De, D99 and n values of the milled lactose batches produced. Small lactose particles of narrow size distribution could be obtained using the fluidized bed hammer mill upon gaining a better understanding of the milling process.

Air Movements↗