bluuebunny/crossref_metadata_2025 huggingface dataset:
Extraction of Lignosulfonate using TOA-Kerosene-PVDF in Supported Liquid Membrane Process
Authors: Ke Xian Chen , Othman Norasikin , Harruddin Norlisa , Nasruddin Nur Alina , Yi Ooi Zing
Published: April 2014

Lignosulfonate is a major byproduct from the sulphite pulping process which is the most abundant biopolymer and largely unused. Although lignosulfonate is nontoxic, it impacts brownish black colour to water and makes the water unsuitable for reuse. However, lignosulfonate have a wide range application, such as production of vanillin, animal feed pellets binder and pesticides. Therefore, an efficient separation technique of lignosulfonate from the wastewater is necessary in order to meet the wastewater treatment requirement and as a source of valuable material for industrial applications. In this study, lignosulfonate was extracted from aqueous solution through flat sheet supported liquid membrane (SLM) using trioctylamine (TOA) as carrier. SLM has great potential for the separation lignosulfonate as it offers advantages such as simultaneous extraction and stripping steps, low consumption of carrier and high selectivity. The important parameters governing the extraction process are the types of support material, types of solvents, types of stripping agent, feed phase flow rate and pH were investigated. The favorable condition for extraction was obtained by using TOA-Kerosene-PVDF membrane system, 0.5M NaOH as stripping agent, 100 mL/min of flow rate and feed at pH 2 with 37.5% of lignosulfonate removal. The result demonstrated that the membrane support remains stable for more than 9 hours, hence demonstrating promising separation technique for lignosulfonate.
Coordinated AVR-PSS for Transient Stability Using Modified Particle Swarm Optimization
Authors: Usman J. , Mustafa M. W. , Aliyu G. , Musa B. U.
Published: April 2014

This paper presents the coordination between the Automatic Voltage Regulator (AVR) and Power System Stabilizers (PSS) to increase the system damping over a wide range of systems’ operating conditions in order to improve the transient stability performance and steady state performance of the system. The coordinated design problem is formulated as an optimization problem which is solved using Iteration Particle Swarm Optimization (IPSO). The application of IPSO technique is proposed to optimize the parameters of the AVR and PSS to minimize the oscillations in power system during disturbances in a single machine infinite bus system (SMIB). The performance of the proposed IPSO technique is compared with the traditional PSO technique. The comparison considered is in terms of parameter accuracy and computational time. The results of the time domain simulations and eigenvalue analysis show that the proposed IPSO method provides a better optimization technique as compared to the traditional PSO technique.
Power Converter Design for Electric Vehicle Applications
Authors: Wangsupphaphol Aree , Idris N. R. N. , Jusoh A. , Muhamad N. D.
Published: April 2014

This paper presents the design of a power converter for electric vehicle (EV) applications energized by Li-ion battery (LiB) and supercapacitor (SC). The combination of these energy sources is a good solution for better performances of the EV. A single non-isolated bi-directional converter is proposed in order to get the lowest loss, weight and cost of total electric vehicle applications perspective. The battery voltage represents bus voltage of the power supply system connecting to the load. To control the dynamic of converter, state space averaging technique and power equation linearization are employed to get the transfer function for designing the PI controllers. In order to get the fast response of SC power energizing, the cascade controller is implemented to control current and SC voltage. MATLAB simulation is successfully verified the proposed power converter topology, configuration and controller design for EV. The result shows the capability to settling supply a significant amount of power for step load change within few milliseconds. Sudden load power demand can be drawn from SC. This can reduce the stress of battery as in case of the pure battery power supply system.
Pretesting Impact of Operational Complexity in Malaysia’s Electrical and Electronics Manufacturing Industry
Authors: Lee Abdullah Nasuha , Jamaludin Khairur Rijal , Abdul Talib Hayati Habibah
Published: April 2014

Scientific research requires data collection instrument that is valid and reliable. This paper describes the framework and operationalization of the variables before outlining the process of developing the instrument to assess the impact of operational complexity (OC) on quality management (QM) practices and operational performance (OP) relationships in Malaysia’s Electrical and Electronics (E&E) manufacturing industry. It also highlights issues of common method bias, reliability and validity of the instrument, pretest method and response rate. The pretest result is then discussed. The paper concludes that personal interviews are especially effective in detecting ambiguity in the instrument. Pilot run provides insights to the challenges ahead such as low response rate, tedious data analysis procedures and enables informed decision to be made in preparation for full-scale data collection.
Classification of Paroxysmal Atrial Fibrillation using Second Order System
Authors: Abdul-Kadir Nurul Ashikin , Mat Safri Norlaili , Othman Mohd Afzan
Published: April 2014

In this paper, we monitored and analyzed the characteristics of atrial fibrillation in patient using second order approach. Atrial fibrillation is a type of atria arrhythmias, disturbing the normal heart rhythm between the atria and lower ventricles of the heart. Heart disease and hypertension increase risk of stroke from atrial fibrillation. This study used electrocardiogram (ECG) signals from Physiobank, namely MIT-BIH Atrial Fibrillation Dataset and MIT-BIH Normal Sinus Rhythm Dataset. In total, 865 episodes for each type of ECG signal were classified, specifically normal sinus rhythm (NSR) of human without arrhythmia, normal sinus rhythm of atrial fibrillation patient (N) and atrial fibrillation (AF). Extracted parameters (forcing input, natural frequency and damping coefficient) from second order system were characterized and analyzed. Their ratios, time derivatives, and differential derivatives were also observed. Altogether, 12 parameters were extracted and analysed from the approach. The results show significant difference between the three ECGs of forcing input, and derivative of forcing input. Overall system performance gives specificity and sensitivity of 84.9 % and 85.5 %, respectively.
Design and Implementation of Flyback Converter for Electrical Discharge Machining Power Generator
Authors: Mahmud Nazriah , Yahya Azli , Andromeda Trias , Hashim Nor Liyana Safura
Published: April 2014

Electrical Discharge Machining process has been widely used for manufacturing micro components due to its contactless process. Its application has also been introduced in machining micro pits on hip implant. In this paper, a new design of power generator is proposed in order to reduce micro crack while machining take place. Flyback Switch Mode Power Supply has been chosen because of its high efficiency. The simulation of Flyback converter using LT Spice is presented. The result shows that the system achieves 95.9% of efficiency. Experimental results show that flyback converter able to produce DC voltage up to 111.6 V.
Effect of Different Light Wavelength on the Growth of Marine Microalgae
Authors: Loong Teo Chee , Idris Ani , Wahidin Suzana , Wee Lai Long
Published: April 2014

Tetraselmis sp. and Nannochloropsis sp. are common marine microalgae used as substrates for production of biodiesel which is the third generation alternative energy. Recently, wavelength of light is believed to influence the growth of marine microalgae. In this investigation, two different types of light wavelength; red and blue which can influence the production of microalgae were investigated. The marine microalgae growths were observed in terms of biomass which was then measured using the UV-vis spectrophotometer. The results showed that both Tetraselmis sp. and Nannochloropsis sp. grow better in the blue light compared to the red light indicated by the higher absorbance readings.
Enzymatic Hydrolysis of Used-Frying Oil Using Candida rugosa Lipase
Authors: Rashid Roslina , Zaharudin Nor Athirah , Idris Ani
Published: April 2014

Hydrolysis of used-frying oil had been carried out by using an immobilized lipase from Candida rugosa in solvent-free system. Used-frying oil was considered as the substrate in this study due to abundance amount of used-frying oil present in Malaysia as its disposal problem has become a very serious environmental issue.  The high free fatty acids (FFA) content in used-frying oil has raised the interest for the utilization of this waste into valuable products. Even though used-frying oil is not suitable for human consumption and being extensively used for the biodiesel production, FFA from used-frying oil could be utilized to produce various types of non-edible products. Effects of enzyme loading, water content, reaction temperature, buffer pH and agitation speeds on the hydrolysis process were investigated. The experiments were conducted at constant reaction time of 3 hours. It was found that the effect of variables were very significant on the hydrolysis process.  The hydrolysis process achieved the highest yield of fatty acids at enzyme concentration of 1.5% (w/v), buffer volume to oil volume ratio of 3:1, temperature of 40˚C, pH of 7, and agitation speed of 220 rpm. Under these described conditions, it was found that nearly 97.15±1.31% of hydrolysis degree was achieved with 2533.33±26.67 µmol/ml of fatty acids was produced.
Influence of Cutting Conditions on Surface and Sub-Surface Quality of High Speed Dry End Milling Ti-6Al-4V
Authors: Safari H. , Izman S.
Published: April 2014

Surface quality is one of the most critical restraints for determining cutting parameters and selecting of machining process in metal cutting process. In this study, the effects of cutting parameters and tool wear on the surface and sub-surface quality of high speed dry end milling Ti-6Al-4V were investigated. PVD Coated carbide tools were used under different high cutting speeds and feed rates. The quality of the machined surface and corresponding alteration on the sub-surface and entry/exit edges were characterized through scanning electron microscopy. The results showed that the better surface quality was obtained when machining at higher cutting speeds and feed rates. High speed dry end milling using the worn tool causes to plastic deformation of the alloy which is resulted in developing the lamellae on the surface and causing poor surface finish. Worn tools with the uniform tool wear land generated better surface quality compare to those with chipping and flaking on the tool edge surface. Tool wear is suggested as the other contributing factor in developing entry and exit edge damages. The results of sub-surface alteration measurement revealed that the worn tool enhanced the sub-surface alteration resulted in 45% increase in plastic deformation compare to the new tool.
Coagulation-Flocculation in Water Treatment using Calotropis Procera Leaves: A case study of River in Kaduna, Nigeria
Authors: Mohammed Danlami Jibrin , Arsad Agus , Ahmad Zaini Muhammad Abbas , Mohammed Evuti Abdullahi , Ogbole Ankeli
Published: April 2014

This research was carried out to evaluate the effectiveness Calotropis procera leaves as an alternative to the use of chemicals as coagulants in water treatment. Calotropis procera leaves were plugged, washed with distilled water, cut into small pieces and then dried in an oven to a constant weight. After which the leaves were grinded into various particle sizes of 1 mm, 2 mm and 0.71 mm. Raw water from River Kaduna at Kabala and Kakuri areas within Kaduna metropolis were treated with different samples classified based on the dried Calotropis procera leaves particle size and weight, sampling location and the treatment time. The physico-chemical characteristics of the treated samples were all within the allowable standard by World Health Organization (WHO). The results show that the treated water sample D with 0.71 mm particle size and 40 g weight of the dried Calotropis procera leaves gave the highest percentage reduction in turbidity. Treatment of the samples with Calotropis procera leaves gave a significant reduction in coliform count from 21 per 100 ml to 1 per 100 ml in treated water samples E and F. This study shows that Calotropis procera can be used as a low-cost, environmentally friendly substitute coagulant for water and wastewater treatment.
Rates of Adsorption on Hydrotalcite Pellets with Respect to Modifications of Area for Removal of CO2
Authors: Isa Nadia , Noel Fernandob W. J.
Published: April 2014

Hydrotalcite (HTC) has recently attracted the attention of researches in CO2 removal technology because of its ability to adsorb appreciable amounts of CO2 compared with many other adsorbents. It is known that pelletized forms of HTC could meet commercial applications which can be easily handled, transported and are of market appeal. The objective of this research is to study the rates of adsorption of CO2 which is an important aspect in the determination of the viability of the removal of CO2 with respect to the modifications of HTC’s surface area that have been encountered. Some modifications of HTC morphology and surface structures with adsorption of CO2 was observed based on Scanning Electron Microscopy, Thermal Gravimetric Analyzer, X-Ray Diffraction Analyzer and analysis of adsorption area of HTC towards CO2. The modifications of area could be contributed by the disintegration and/or agglomeration effects. A model based on the Langmuir rate model was developed in order to investigate the interesting behavior of HTC area towards the adsorption of CO2. Based on a cross sectional area of a mole of CO2, which is 136.4 m2/mmol as reported by Aylmore et al. [31], the monolayer areas of HTC after adsorption of CO2 is calculated to be 177.32 m2/g. This value when being compared with the Brunauer Emmett and Teller (BET) value of commercial HTC which is 110.98 m2/g, it was found that there is an increase in equivalent areas of HTC after the adsorption of CO2.
PrekotAC as Filter Aids for Efficient Dust Separation in a Fabric Filter
Authors: Hajar S. , Rashid M. , Nurnadia A. , Norelyza H. , Ammar M.
Published: April 2014

Fabric filters are extensively used as an air pollution control system for its high efficiency to collect particles from gaseous stream. The system is commonly installed in many incineration plants as the means to control dust and gaseous emissions. Unfortunately, their applications in these facilities are short lived due to wear and tear of the fabric media. This is because the fabric filter is not adequately conditioned before it is put up into service. A simple technique is to apply so called ‘pre-coat’ material to coat a layer of inert material onto the surface of the fabric as a ‘barrier’ for protection as well as to allow a uniform air flow passing through the filter media. In this regard, a newly formulated filter aids material known as PrekotAC, not merely acts as an adsorbent for flue gas cleaning but also an efficient dust separation agent in a fabric filter system. A mixture of PreKotTM:Activated Carbon of 40:60 (%weight) was found to be the most preferable combination with its particle size distribution between 75 and 600μm, which is bigger size fraction than the original materials.
Optimization of Nickel Removal from Electroless Plating Industry Wastewater using Response Surface Methodology
Authors: Ahmad Nor Azimah , Abu Hassan Mohd Ariffin , Noor Zainura Zainon , Mohammed Evuti Abdullahi , Mohammed Danlami Jibrin
Published: April 2014

Optimum pH and coagulant dosage for chemical precipitation in wastewater treatment plants is conventionally obtained through repeated jar test. In this research, optimization of the performance of polyacrylamide in the treatment of industrial wastewater was carried out using response surface methodology. The individual linear and quadratic effect of coagulant dosage and pH on the degree of removals of nickel, total suspended solids, Chemical Oxygen Demand and turbidity were investigated. The optimum pH and polyacrylamide dosage were found to be 10.5 and 1.6 ml/L respectively and the optimum percentage nickel removal was 96.9%. The model used in predicting the precipitation process gave a good fit with the experimental variables and hence the suitability of response surface methodology for the optimization of polyacrylamide performance.
The Effect of Solvents on the Soxhlet Extraction of Omega 3 from Perah Oil
Authors: Hadi Tan Nuraimi Azlan , Siddique Bazlul Mobin , Muhamad Ida Idayu , Kok Fook Seng
Published: April 2014

This study aims to investigate the influence of solvent on the Soxhlet extraction of omega 3 in perah seed oil. Three types of extraction solvent include hexane, hexane: methanol (90:10) and methanol: ethanol (70:30) were investigated. The concentration of extracted omega 3 was measured using Gas chromatography (GC), the colour of extracted oil was classified using colormeter and the total phenolic content (TPC) by Folin-Ciocalteau colorimetry. Based on the total yield extraction of the oil, the result shows that hexane solvent (57.5%) shows better performance compared to hexane-methanol (53.42%) and ethanol-methanol (34.52%). For the omega 3 concentration, hexane-methanol solvent provided highest yield at 1.41g ω-3/g oil followed by ethanol-methanol and hexane at 1.32 ω-3/g oil and 1.15 ω-3/g oil respectively. On the other hand, the extracted oil using hexane as extraction solvent was appeared to be lighter in colour as compared to other solvents studied. In addition, total phenolics content of perah oil was high with hexane solvent. As conclusion, the polar solvent of methanol and ethanol promoted the extraction of omega 3; however, it may cause a darker appearance of the extract as well as reducing the content of phenolic compounds.
Supercritical Fluid Extraction of Swietenia mahagoni Seed: Antioxidant and Antimicrobial Activities
Authors: Hartati Hartati , Md Salleh Liza , Ismail Ahmad Ramdan , Che Yunus Mohd. Azizi , Abd. Aziz Azila
Published: April 2014

Swietenia mahagoni seeds have been used as folk medicine for a treatment of hypertension, malaria and diabetes. This research was conducted to obtain extracts from the Swietenia mahagoni using supercritical fluid extraction (SFE) with pure CO2 solvent, in order to evaluate the high- pressure method in terms of process yield and biological activity. The various conditions namely flow rate of CO2 were set up at 2, 3, and 4 ml/min; at constant pressures (P) and temperature (T). The sample extracts obtained by SFE with CO2 flow rate of 4 ml/min showed the highest percentage yield (19.67%) compared to the others. The antioxidant potential of the extracts was evaluated by the DPPH method and Folin- Ciocalteu method. The solvent flow rate of 2 ml/min gave the lowest percentage of yield, but good results in antioxidant activity and total phenolic content. The antimicrobial activity of the extracts against Gram-positive (Bacillus subtilis, Staphylococcus aureus) and Gram-negative (Escherichia coli) was evaluated based on the inhibition zone using disc diffusion assay. These results ensured that Swietenia mahagoni seed extract had inhibitory effects on the growth of Bacillus subtilis, Staphylococcus aureus and Escherichia coli at concentration of 100 mg/ml.
Parameter Study of Ionized Nanosilver Recovery from Wash Water using Emulsion Liquid Membrane Process
Authors: Raja Sulaiman Raja Norimie , Othman Norasikin , Saidina Amin Nor Aishah , Mohamed Noah Norul Fatiha
Published: April 2014

Ionized nanosilver is a harmful and highly toxic owing to its association with other organic chemical especially with the aquatic organism cells. Therefore, it is crucial to treat the ionized nanosilver to preserve the environment. In this study, experiments were carried out using emulsion liquid membrane (ELM) process in order to investigate the performance of extraction and recovery of ionized nanosilver from wash water. This process involves three phase dispersion systems including external phase, membrane phase and internal phase. The ELM formulation consists of bis [2,4,4-trimethylpentyl] monothiophosphinic acid (Cyanex 302) as a carrier, Span 80 as a surfactant, kerosene as a diluent and thiourea in sulphuric acid (H2SO4) solution as stripping agent. This study has highlighted several effects of parameters including agitation speed, pH of external phase, and treat ratio. The concentration of the ionized nanosilver was measured using Atomic Absorption Spectrometry (AAS). The results have demonstrated that at optimum conditions, the percentages of extraction, stripping and recovery were 96, 84 and 80% respectively at 150 rpm of agitation speed, pH 2 and 0.33 of treat ratio.
Resonant Control of a Single-Link Flexible Manipulator
Authors: M. Abdullahi Auwalu , Mohamed Z. , Nafea M. Marwan
Published: April 2014

This paper presents resonant control of a single-link flexible manipulator based on the resonant modes frequencies of the system. A flexible manipulator system is a single-input multi-output (SIMO) system with motor torque as an input and hub angle and the tip deflection as outputs. The previous system which is modeled using the finite element method is considered, and the resonant modes of the system are determined. Two negative feedback controllers are used to control the system. The inner feedback control loop designed using the resonant frequencies adds damping to the system and suppress the vibration effect around the hub angle. For the outer feedback control loop, a proportional integral controller is designed to achieve a zero steady state error so that a precise tip positioning can be achieved. Simulation results are presented and discussed to show the effectiveness of the resonant control scheme.
Anti-Sway Control Schemes of a Boom Crane Using Command Shaping Techniques
Authors: Ishak M. H. I. , Mohamed Z. , Mamat R.
Published: April 2014

This paper presents investigations into the applications and performance of command shaping techniques for control of payload sway of a boom crane based on filtering and the input shaping technique. The mathematical dynamic model describing the motion of the boom crane is developed using the Lagrange-Euler's equation. The dynamic characteristics of the system are studied and analysed using the Matlab Simulink in time and frequency domains. Command shaping techniques based on filtering and the input shaping techniques are then developed and used to control the payload sway of the boom crane. The performance of the control techniques are studied in terms of the level of sway reduction, time response and robustness. Finally, a comparative assessment of the effectiveness of the control schemes for sway control of a boom crane is presented and discussed.
A Robust Stabilization using State Feedback with Feedforward
Authors: A. Danapalasingam Kumeresan
Published: April 2014

In a general nonlinear control system a stabilizing control strategy is often possible if complete information on external inputs affecting the system is available. Assuming that measurements of persistent disturbances are available it is shown that the existence of a smooth uniform control Lyapunov function implies the existence of a stabilizing state feedback with feedforward control which is robust with respect to measurement errors and external disturbances. Conversely, using differential inclusions parameterized as nonlinear systems with state and disturbance measurement errors, it is shown that there exists a smooth uniform control Lyapunov function if there is a robustly stabilizing state feedback with feedforward. This paper demonstrates that if there exists a smooth control Lyapunov function for a general nonlinear system with persistent disturbances for which one has previously designed a feedback controller, a feedforward always exists to be augmented for stability.
Multivariable PID Using Singularly Perturbed System
Authors: Che Razali Mashitah , Abdul Wahab Norhaliza , Samsudin Sharatul Izah
Published: April 2014

The paper investigates the possibilities of using the singularly perturbation method in a multivariable proportional-integral-derivative (MPID) controller design. The MPID methods of Davison, Penttinen-Koivo and Maciejowski are implemented and the effective of each method is tested on wastewater treatment plant (WWTP). Basically, this work involves modeling and control. In the modeling part, the original full order system of the WWTP was decomposed to a singularly perturbed system. Approximated slow and fast models of the system were realized based on eigenvalue of the identified system. The estimated models are then used for controller design. Mostly, the conventional MPID considered static inverse matrix, but this singularly perturbed MPID considers dynamic matrix inverse. The stability of the singularly perturbed system is established by using Bode analysis, whereby the bode plot of the model system is compared to the original system. The simulation results showed that the singularly perturbed method can be applied into MPID. The three methods of MPID have been compared and the Maciejowski shows the best closed loop performance.
Disease Risk Factors Identified Through Shared Genetic Architecture and Electronic Medical Records
Authors: Li Li , Ruau David J. , Patel Chirag J. , Weber Susan C. , Chen Rong , Tatonetti Nicholas P. , Dudley Joel T. , Butte Atul J.
Published: April 2014

Twenty-six traits were associated with diseases through similarities in genetic variation and validated from electronic medical records.
Modular Multiantigen T Cell Epitope–Enriched DNA Vaccine Against Human Leishmaniasis
Authors: Das Shantanabha , Freier Anja , Boussoffara Thouraya , Das Sushmita , Oswald Detlef , Losch Florian O. , Selka Melanie , Sacerdoti-Sierra Nina , Schönian Gabriele , Wiesmüller Karl-Heinz , Seifert Karin , Schroff Matthias , Juhls Christiane , Jaffe Charles L. , Roy Syamal , Das Pradeep , Louzir Hechmi , Croft Simon L. , Modabber Farrokh , Walden Peter
Published: April 2014

A DNA vaccine for the induction of cell-mediated immunity against different types of leishmaniasis was developed and successfully tested in human cell culture systems for immunogenicity and an animal model for prophylaxis.
Using Humans to Make a Human Leishmaniasis Vaccine
Authors: Kamhawi Shaden , Oliveira Fabiano , Valenzuela Jesus G.
Published: April 2014

The cellular immune response to peptide pools from conserved
Leishmania
antigens in leishmaniasis-immune individuals identified epitopes for a human DNA vaccine (Das
et al
., this issue).
Carbon Nanotubes Are Picky Hitchhikers
Authors: Stephan Matthias
Published: April 2014

A new class of nanoparticles are taken up by a subset of monocytes in vivo for imaging and therapy of cancer, cardiovascular disease, and certain autoimmune diseases.
An “Exciting” Way to Heal
Authors: Schaefer Anne
Published: April 2014

Enhancing depression-causing hyperexcitability in dopamine neurons alleviates depression-like behavior in mice.
Polymicrobial Infection and Bacterium-Mediated Epigenetic Modification of DNA Tumor Viruses Contribute to Pathogenesis
Authors: Doolittle J. M. , Webster-Cyriaque J.
Published: April 2014

The human body plays host to a wide variety of microbes, commensal and pathogenic. In addition to interacting with their host, different microbes, such as bacteria and viruses, interact with each other, sometimes in ways that exacerbate disease. In particular, gene expression of a number of viruses, including Kaposi’s sarcoma-associated herpesvirus (KSHV), Epstein-Barr virus (EBV), and human immunodeficiency virus (HIV), is known to be regulated by epigenetic modifications induced by bacteria. These viruses establish latent infection in their host cells and can be reactivated by bacterial products. Viral reactivation has been suggested to contribute to periodontal disease and AIDS. In addition, bacterium-virus interactions may play a role in cancers, such as Kaposi’s sarcoma, gastric cancer, and head and neck cancer. It is important to consider the effects of coexisting bacterial infections when studying viral diseases
in vivo
.
A Rhodobacter sphaeroides Protein Mechanistically Similar to Escherichia coli DksA Regulates Photosynthetic Growth
Authors: Lennon Christopher W. , Lemmer Kimberly C. , Irons Jessica L. , Sellman Max I. , Donohue Timothy J. , Gourse Richard L. , Ross Wilma
Published: April 2014

DksA is a global regulatory protein that, together with the alarmone ppGpp, is required for the “stringent response” to nutrient starvation in the gammaproteobacterium
Escherichia coli
and for more moderate shifts between growth conditions. DksA modulates the expression of hundreds of genes, directly or indirectly. Mutants lacking a DksA homolog exhibit pleiotropic phenotypes in other gammaproteobacteria as well. Here we analyzed the DksA homolog RSP2654 in the more distantly related
Rhodobacter sphaeroides
, an alphaproteobacterium. RSP2654 is 42% identical and similar in length to
E. coli
DksA but lacks the Zn finger motif of the
E. coli
DksA globular domain. Deletion of the RSP2654 gene results in defects in photosynthetic growth, impaired utilization of amino acids, and an increase in fatty acid content. RSP2654 complements the growth and regulatory defects of an
E. coli
strain lacking the
dksA
gene and modulates transcription
in vitro
with
E. coli
RNA polymerase (RNAP) similarly to
E. coli
DksA. RSP2654 reduces RNAP-promoter complex stability
in vitro
with RNAPs from
E. coli
or
R. sphaeroides
, alone and synergistically with ppGpp, suggesting that even though it has limited sequence identity to
E. coli
DksA (DksA
Ec
), it functions in a mechanistically similar manner. We therefore designate the RSP2654 protein DksA
Rsp
. Our work suggests that DksA
Rsp
has distinct and important physiological roles in alphaproteobacteria and will be useful for understanding structure-function relationships in DksA and the mechanism of synergy between DksA and ppGpp.

IMPORTANCE
The role of DksA has been analyzed primarily in the gammaproteobacteria, in which it is best understood for its role in control of the synthesis of the translation apparatus and amino acid biosynthesis. Our work suggests that DksA plays distinct and important physiological roles in alphaproteobacteria, including the control of photosynthesis in
Rhodobacter sphaeroides
. The study of DksA
Rsp
, should be useful for understanding structure-function relationships in the protein, including those that play a role in the little-understood synergy between DksA and ppGpp.
Bacterial Toxins—Staphylococcal Enterotoxin B
Authors: Fries Bettina C. , Varshney Avanish K.
Published: April 2014

Staphylococcal enterotoxin B is one of the most potent bacterial superantigens that exerts profound toxic effects upon the immune system, leading to stimulation of cytokine release and inflammation. It is associated with food poisoning, nonmenstrual toxic shock, atopic dermatitis, asthma, and nasal polyps in humans. Currently, there is no treatment or vaccine available. Passive immunotherapy using monoclonal antibodies made in several different species has shown significant inhibition in in vitro studies and reduction in staphylococcal enterotoxin B-induced lethal shock in in vivo studies. This should encourage future endeavors to develop these antibodies as therapeutic reagents.
Plant-Derived Monoclonal Antibodies for Prevention and Treatment of Infectious Disease
Authors: Hiatt Andrew , Whaley Kevin J. , Zeitlin Larry
Published: April 2014

Numerous monoclonal antibodies (MAbs) that recognize and neutralize infectious pathogens have been isolated and developed over the years. The fact that infectious diseases can involve large populations of infected individuals is an important factor that has motivated the search for both cost-effective and scalable methods of antibody production. The current technologies for production of antibodies in plants allow for very rapid expression and evaluation that can also be readily scaled for multikilogram production runs. In addition, recent progress in manipulating glycosylation in plant production systems has allowed for the evaluation of antibodies containing glycans that are nearly homogeneous, are mammalian in structure, and have enhanced neutralizing capabilities. Among the anti-infectious disease antibodies that have been produced in plants are included those intended for prevention or treatment of anthrax,
Clostridium perfringens
, Ebola virus, human immunodeficiency virus, herpes simplex virus, rabies, respiratory syncytial virus, staphylococcal enterotoxin, West Nile virus, and tooth decay. Animal and human efficacy data for these MAbs are discussed.
Probing Antibody-Antigen Interactions
Authors: Yang Guocheng , Velgos Stefanie N. , Boddapati Shanta P. , Sierks Michael R.
Published: April 2014

Antibodies are biological molecules generated by the host immune system in response to the invasion of foreign bodies or antigens. Therefore, antibodies must possess high specificity toward target antigens in order for the antigen to be recognized and subsequently destroyed. Because of this specificity, antibodies or antibody fragments that maintain binding specificity are heavily used in diagnostic assays and are becoming increasingly important in many therapeutic applications. Classical immunoassays such as radioimmunoassay and enzyme-linked immunosorbent assay are effective analytical techniques that have been widely used to screen and determine antibody specificity. Because of increased demands for antibodies with well-defined specificities, other techniques have been developed that facilitate generation and characterization of antibody-binding specificities under different conditions, such as when the protein is expressed on a cell surface or the target antigen is hard to isolate. Here, we describe three alternate techniques that provide unique abilities to characterize antibody-antigen binding events: (i) surface plasmon resonance, (ii) fluorescence activated cell sorting, and (iii) atomic force microscopy. These different techniques take advantage of various changes in physical and/or chemical properties of the analytes that occur upon binding, such as refractive index, surface charge, and changes in structure. These techniques provide unique powerful advantages over traditional immunoassays including real-time and label-free detection, low sample volume and concentration requirements, and molecular-level detection sensitivity. This article provides an overview of how these alternate approaches to studying antibody-antigen interactions can be used to facilitate rapid development of new antibody-based reagents for diagnostic and therapeutic applications.
Rotavirus
Authors: Franco Manuel A. , Greenberg Harry B.
Published: April 2014

Rotaviruses (RV) are ubiquitous, highly infectious, segmented double-stranded RNA genome viruses of importance in public health because of the severe acute gastroenteritis they cause in young children and many animal species. They are very well adapted to their host, with symptomatic and asymptomatic reinfections being virtually universal during the first 3 years of life. Antibodies are the major arm of the immune system responsible for protecting infants from RV reinfection. The relationship between the virus and the B cells (Bc) that produce these antibodies is complex and incompletely understood: most blood-circulating Bc that express RV-specific immunoglobulin (Ig) on their surface (RV-Ig) are naive Bc and recognize the intermediate capsid viral protein VP6 with low affinity. When compared to non-antigen-specific Bc, RV-Bc are enriched in CD27+memory Bc (mBc) that express IgM. The Ig genes used by naive RV-Bc are different than those expressed by RV-mBc, suggesting that the latter do not primarily develop from the former. Although RV predominantly infects mature villus enterocytes, an acute systemic viremia also occurs and RV-Bc can be thought of as belonging to either the intestinal or systemic immune compartments. Serotype-specific or heterotypic RV antibodies appear to mediate protection by multiple mechanisms, including intracellular and extracellular homotypic and heterotypic neutralization. Passive administration of RV-Ig can be used either prophylactically or therapeutically. A better understanding of the Bc response generated against RV will improve our capacity to identify improved correlates of protection for RV vaccines.
Antibody Structure
Authors: Stanfield Robyn L. , Wilson Ian A.
Published: April 2014

A brief outline of antibody structure is followed by highlights from several recently determined crystal structures of human, antiviral Fabs. These Fabs all have novel structural features that allow them to potently and broadly neutralize their targets.
From Pasteur to Probiotics: A Historical Overview of Cheese and Microbes
Authors: Donnelly Catherine W.
Published: April 2014

Cheese is a food which has been produced for centuries. While cheese was originally developed as a product which extended the shelf life of milk, over time distinct cheese varieties arose, being shaped by geographic, climate, cultural, and economic factors. Global demand for artisan cheeses is creating new economic opportunities. Consumers seeking distinctive products with regional flavor, or
terroir
, are becoming connoisseurs of hand-crafted cheeses with distinctive tastes and character. These demands have spurred new inquiry into microorganisms used as starter cultures and adjunct cultures, as well as the microbiological consortia of finished cheeses. Such demands have also created new concerns for food safety and international trade. New bacterial pathogens such as
Escherichia coli
O157:H7 and
Salmonella enterica
serovar Typhimurium DT104 have emerged in the food supply, causing a reevaluation of the efficacy of traditional cheesemaking procedures to control these pathogens. Similarly, pathogens such as
Listeria monocytogenes
pose problems to susceptible human populations, and cheese can be a vehicle of transmission for this deadly pathogen. With changes in sanitary requirements due to the globalization of the food industry, governments around the world are increasingly requiring assurances of cheese safety. While many governments recognize the safety of traditional artisan cheeses manufactured from raw milk, others are demanding pasteurization of all milk intended for cheesemaking to provide assurance of microbiological safety. In response, new technologies are being proposed to increase cheese safety, but these technologies fundamentally alter the traditional artisan practices and may not enhance microbiological safety. A reevaluation of the safety of traditional artisan practices, validation thereof, and communication of the scientific principles which promote safety will be necessary to enable the continued production of traditional artisan cheeses in global commerce. This also affords the opportunity to more fully explore the microbial diversity and microbial ecology of the great cheeses of the world.
Mesophilic and Thermophilic Cultures Used in Traditional Cheesemaking
Authors: Johnson Mark E.
Published: April 2014

Most cheese varieties require acidification of milk by a select group of bacteria called starters. They ferment lactose to lactic acid and in so doing aid the cheesemaker in developing the desired texture as well as acidity of the cheese. However, while other microorganisms play the major role in flavor development of cheese, it is the starter that sets the stage for quality cheese manufacture. Starters were traditionally derived from the native microflora of the milk, but this practice is almost unheard of today. With the advent of better hygienic milking practices and industrialized cheesemaking, there was a need for more uniformity and reliable sources of the starter culture. Today’s starters are produced by companies specializing in their production as well as in the development of new strains for cheesemakers. The choice of starter for the manufacture of a specific cheese is dictated by the cheesemaking protocol, but it is also governed by the need to produce cheese with desired physical attributes. The properties of the starter that make it possible to do so help drive innovation in developing new potential choices in starter cultures. Indeed, the demands for predictable and reliable rates and extent of acidification of milk for cheesemaking and flavor development are as key for successful cheesemaking today with artisanal cheesemakers as they are for larger, more industrial-scale cheesemakers.
The Good, the Bad, and the Ugly: Tales of Mold-Ripened Cheese
Authors: Marcellino O.S.B. Sister Noëlla , Benson David R.
Published: April 2014

The history of cheese manufacture is a “natural history” in which animals, microorganisms, and the environment interact to yield human food. Part of the fascination with cheese, both scientifically and culturally, stems from its ability to assume amazingly diverse flavors as a result of seemingly small details in preparation. In this review, we trace the roots of cheesemaking and its development by a variety of human cultures over centuries. Traditional cheesemakers observed empirically that certain environments and processes produced the best cheeses, unwittingly selecting for microorganisms with the best biochemical properties for developing desirable aromas and textures. The focus of this review is on the role of fungi in cheese ripening, with a particular emphasis on the yeast-like fungus
Geotrichum candidum
. Conditions that encourage the growth of problematic fungi such as
Mucor
and
Scopulariopsis
as well as Arachnida (cheese mites), and how such contaminants might be avoided, are discussed. Bethlehem cheese, a pressed, uncooked, semihard, Saint-Nectaire-type cheese manufactured in the United Sates without commercial strains of bacteria or fungi, was used as a model for the study of stable microbial succession during ripening in a natural environment. The appearance of fungi during a 60-day ripening period was documented using light and scanning electron microscopy, and it was shown to be remarkably reproducible and parallel to the course of ripening of authentic Saint-Nectaire cheese in the Auvergne region of France.
Geotrichum candidum
,
Mucor
, and
Trichothecium roseum
predominate the microbiotas of both cheese types.
Geotrichum
in particular was shown to have high diversity in different traditional cheese ripening environments, suggesting that traditional manufacturing techniques selected for particular fungi. This and other studies suggest that strain diversity arises in relation to the lore and history of the regions from which these types of cheeses arose.
Wooden Tools: Reservoirs of Microbial Biodiversity in Traditional Cheesemaking
Authors: Lortal Sylvie , Licitra Giuseppe , Valence Florence
Published: April 2014

Today, wooden shelves are used for the ripening of about 500,000 tons of cheese per year in Europe, including about 350,000 tons in France, such as most of the famous cheeses with the protected designation of origin (PDO), e.g., Comté, Reblochon, Beaufort, Munster, Cantal, and Roquefort. For some PDO cheeses, the use of wooden tools is mandatory. Many cheesemakers believe that wooden tools improve the organoleptic and typical characteristics of their final products. Wood is a natural and sustainable material which has been used for centuries in traditional cheese production in a wide variety of forms (vats, shelves, and packaging). Wood is important in the cheesemaking process, interacting with the milk in vats or with the cheeses placed on shelves for ripening. Wood is viable due to its ability to exchange water but, above all, because it is covered by a rich microbial biofilm. As wood is porous and difficult to clean, the European Commission regularly highlights the question of its safety when in contact with food and calls for deeper scientific investigation. In this review, knowledge about the multiple technological roles of wood in dairy technology is discussed. The crucial role of wood as a reservoir of microbial biodiversity for traditional cheeses is reviewed, along with results of safety assessments. As a conclusion, the numerous questions remaining about this natural inoculating system are discussed.
The Microfloras of Traditional Greek Cheeses
Authors: Litopoulou-Tzanetaki Evanthia , Tzanetakis Nikolaos
Published: April 2014

Many traditional cheeses are made in Greece. Some of them are, in fact, types of the same cheese variety, whether or not they have different cheesemaking technologies, but are known by different local names. Twenty of them have been granted protected designation of origin status. In the 8th century BCE, Homer described a cheese thought to be the ancestor of feta, the main cheese manufactured in Greece from the ancient times until today. Meanwhile, various cheese types evolved through the centuries, and almost every area in Greece has its own cheesemaking tradition. Some cheese varieties are local, handcrafted products whose production has been handed down from generation to generation, and without interest in their continued production, these varieties will disappear. Other local varieties are made at small factories from pasteurized milk and commercial rennet and starter and are very different from the traditional versions. However, some milk producers still make their cheeses at home or at small dairies from raw milk, without any starter, or sometimes from thermized milk, with traditional yogurt as the starter. Their cheeses are the basis for the information presented in this review.
Microbiological Quality and Safety Issues in Cheesemaking
Authors: D'amico Dennis J.
Published: April 2014

As the manufacture of cheese relies in part on the select outgrowth of microorganisms, such conditions can also allow for the multiplication of unwanted contaminants. Milk ultimately becomes contaminated with microorganisms originating from infection, the farm environment, and feedstuffs, as well as milking and processing equipment. Thus, poor sanitation, improper milk handling, and animal health issues can result in not only decreased yield and poor quality but also sporadic cases and outbreaks of dairy-related disease. The entry, establishment, and persistence of food-borne pathogens in dairy processing environments also present a considerable risk to products postprocessing. Food safety management systems coupled with regulatory policies and microbiological standards for milk and milk products currently implemented in various nations work to reduce risk while improving the quality and safety of cheese and other dairy products. With that, cheese has enjoyed an excellent food safety record with relatively few outbreaks of food-borne disease considering the amount of cheese produced and consumed worldwide. However, as cheese production and consumption continue to grow, we must remain vigilant in ensuring the continued production of safe, high-quality cheese.
Sigma Factors: Key Molecules in
Mycobacterium tuberculosis
Physiology and Virulence
Authors: Manganelli Riccardo
Published: April 2014

Rapid adaptation to changing environments is one of the keys to the success of microorganisms. Since infection is a dynamic process, it is possible to predict that
Mycobacterium tuberculosis
adaptation involves continuous modulation of its global transcriptional profile in response to the changing environment found in the human body. In the last 18 years several studies have stressed the role of sigma (σ) factors in this process. These are small interchangeable subunits of the RNA polymerase holoenzyme that are required for transcriptional initiation and that determine promoter specificity. The
M. tuberculosis
genome encodes 13 of these proteins, one of which—the principal σ factor σ
A
—is essential. Of the other 12 σ factors, at least 6 are required for virulence. In this article we review our current knowledge of mycobacterial σ factors, their regulons, the complex mechanisms determining their regulation, and their roles in
M. tuberculosis
physiology and virulence.