title: A comparative study of functional monomer and crosslinker ratios in the synthesis of  catechin-selective MIPs via suspension polymerisation

authors: Pitaduwa Gamage, Sandeepa  Thathsarani Wickramasinghe

subjects: molecularly imprinted polymers

abstract: Catechin contamination in food and environmental samples presents challenges for selective extraction and analysis, requiring advanced polymeric materials with high specificity and capacity. This study investigates the synthesis of catechin-selective molecularly imprinted polymers (MIPs) using suspension polymerisation, with a systematic evaluation of crosslinker-to-monomer (CL:M) and template-to-monomer (T:M) ratios. Polymers were prepared with CL:M ratios ranging from 1:1 to 4:1 and T:M ratios from 0 to 0.5, and characterised by particle size analysis, BET surface area and pore measurements, and scanning electron microscopy (SEM). Adsorption experiments were conducted at initial catechin concentrations of 2.5–10 mg/L, and binding isotherm models were applied to interpret the adsorption mechanisms.
Polymers synthesised at CL:M ratios of 1:1 and 2:1 with T:M = 0.125 exhibited the highest adsorption capacities, consistently achieving values above 0.080 mg/g at 10 mg/L catechin. These optimal conditions also produced polymers with yields up to 94.7%, median particle diameters between 1100–1500 μm, and average pore radii approaching 10 Å. In addition, SEM analysis revealed that optimal samples displayed uniform, spherical morphology with well-developed surface porosity, whereas non-optimal samples showed increased aggregation and denser, less accessible surfaces. Notably, the Temkin isotherm provided the best fit for the adsorption data (R² = 0.9807), indicating heterogeneous binding sites and significant adsorbate–adsorbate interactions. In contrast, higher crosslinker (CL:M= 4:1 and 3:1) or template ratios (T:M= 0.375 and 0.5) led to reduced adsorption capacity and, in some cases, persistent template leaching. These results indicate that extraction conditions must be carefully optimised, such as by increasing Soxhlet extraction time or adjusting solvent parameters, to ensure complete template removal and improve polymer performance in practical applications. Overall, these findings establish suspension polymerisation, combined with carefully optimised synthesis and extraction conditions, as an effective strategy for producing catechin-selective MIPs with enhanced selectivity, capacity, and reproducibility.

text: A comparative study of functional monomer and crosslinker ratios in the synthesis of  catechin-selective MIPs via suspension polymerisation Catechin contamination in food and environmental samples presents challenges for selective extraction and analysis, requiring advanced polymeric materials with high specificity and capacity. This study investigates the synthesis of catechin-selective molecularly imprinted polymers (MIPs) using suspension polymerisation, with a systematic evaluation of crosslinker-to-monomer (CL:M) and template-to-monomer (T:M) ratios. Polymers were prepared with CL:M ratios ranging from 1:1 to 4:1 and T:M ratios from 0 to 0.5, and characterised by particle size analysis, BET surface area and pore measurements, and scanning electron microscopy (SEM). Adsorption experiments were conducted at initial catechin concentrations of 2.5–10 mg/L, and binding isotherm models were applied to interpret the adsorption mechanisms.
Polymers synthesised at CL:M ratios of 1:1 and 2:1 with T:M = 0.125 exhibited the highest adsorption capacities, consistently achieving values above 0.080 mg/g at 10 mg/L catechin. These optimal conditions also produced polymers with yields up to 94.7%, median particle diameters between 1100–1500 μm, and average pore radii approaching 10 Å. In addition, SEM analysis revealed that optimal samples displayed uniform, spherical morphology with well-developed surface porosity, whereas non-optimal samples showed increased aggregation and denser, less accessible surfaces. Notably, the Temkin isotherm provided the best fit for the adsorption data (R² = 0.9807), indicating heterogeneous binding sites and significant adsorbate–adsorbate interactions. In contrast, higher crosslinker (CL:M= 4:1 and 3:1) or template ratios (T:M= 0.375 and 0.5) led to reduced adsorption capacity and, in some cases, persistent template leaching. These results indicate that extraction conditions must be carefully optimised, such as by increasing Soxhlet extraction time or adjusting solvent parameters, to ensure complete template removal and improve polymer performance in practical applications. Overall, these findings establish suspension polymerisation, combined with carefully optimised synthesis and extraction conditions, as an effective strategy for producing catechin-selective MIPs with enhanced selectivity, capacity, and reproducibility.

year: 2025-07-05

title: A scalable approach to joint cyber insurance and security-as-a-service provisioning in cloud computing

authors: Chase, Jonathan

subjects: computer science

abstract: As computing services are increasingly cloud-based, corporations are investing in cloud-based security measures. The Security-asa- Service (SECaaS) paradigm allows customers to outsource security to the cloud, through the payment of a subscription fee. However, no security system is bulletproof, and even one successful attack can result in the loss of data and revenue worth millions of dollars. To guard against this eventuality, customers may also purchase cyber insurance to receive recompense in the case of loss. To achieve cost effectiveness, it is necessary to balance provisioning of security and insurance, even when future costs and risks are uncertain. To this end, we introduce a stochastic optimization model to optimally provision security and insurance services in the cloud. Since the model we design is a mixed integer problem, we also introduce a partial Lagrange multiplier algorithm that takes advantage of the total unimodularity property to find the solution in polynomial time. We also apply sensitivity analysis to find the exact tolerance of decision variables to parameter changes. We show the effectiveness of these techniques using numerical results based on real attack data to demonstrate a realistic testing environment, and find that security and insurance are interdependent.

text: A scalable approach to joint cyber insurance and security-as-a-service provisioning in cloud computing As computing services are increasingly cloud-based, corporations are investing in cloud-based security measures. The Security-asa- Service (SECaaS) paradigm allows customers to outsource security to the cloud, through the payment of a subscription fee. However, no security system is bulletproof, and even one successful attack can result in the loss of data and revenue worth millions of dollars. To guard against this eventuality, customers may also purchase cyber insurance to receive recompense in the case of loss. To achieve cost effectiveness, it is necessary to balance provisioning of security and insurance, even when future costs and risks are uncertain. To this end, we introduce a stochastic optimization model to optimally provision security and insurance services in the cloud. Since the model we design is a mixed integer problem, we also introduce a partial Lagrange multiplier algorithm that takes advantage of the total unimodularity property to find the solution in polynomial time. We also apply sensitivity analysis to find the exact tolerance of decision variables to parameter changes. We show the effectiveness of these techniques using numerical results based on real attack data to demonstrate a realistic testing environment, and find that security and insurance are interdependent.

year: 2017

title: Cultural identity and academic achievement among Māori undergraduate university students

authors: Bennett, Simon T.

subjects: Maori

abstract: Cultural identity and academic achievement were investigated among a nonrandom
sample of 72 undergraduate Māori university students studying at Massey
University. Student problems were examined to identify the types of difficulties
most prevalent among this population. The degree to which cultural identity
moderates the relationship between student problems and academic achievement
was then examined. Major findings were that (a) there is a consistent negative
relationship between student problems and academic achievement; and (b) cultural
identity moderates the effect of student problems on academic achievement, in that:
a high degree of problems were associated with decreases in grade point average
among respondents with low cultural identity; while among respondents with high
cultural identity, high levels of student problems had little negative effect on grade
point average. Despite the study having limitations, the findings have important
implications for Māori students, deliverers of tertiary education, tertiary education
providers, and those involved in the development and implementation of tertiary
education policy.

text: Cultural identity and academic achievement among Māori undergraduate university students Cultural identity and academic achievement were investigated among a nonrandom
sample of 72 undergraduate Māori university students studying at Massey
University. Student problems were examined to identify the types of difficulties
most prevalent among this population. The degree to which cultural identity
moderates the relationship between student problems and academic achievement
was then examined. Major findings were that (a) there is a consistent negative
relationship between student problems and academic achievement; and (b) cultural
identity moderates the effect of student problems on academic achievement, in that:
a high degree of problems were associated with decreases in grade point average
among respondents with low cultural identity; while among respondents with high
cultural identity, high levels of student problems had little negative effect on grade
point average. Despite the study having limitations, the findings have important
implications for Māori students, deliverers of tertiary education, tertiary education
providers, and those involved in the development and implementation of tertiary
education policy.

year: 2003