Levels Of Charges Research Articles

Energy density source levels of underwater explosive charges

This paper presents experimental measurements of energy density source levels of small explosive charges for high frequencies to 18 kHz. The experiments were carried out using Signals Underwater Sound (SUS) charges deployed at a deep water site in a coastal fiord north of Vancouver BC. The waveform of an underwater explosion is characterized by a high intensity shock wave signal followed by a series of bubble pulses of decreasing intensity. The bubble pulses dominate the SUS energy density spectrum at frequencies below 1 kHz, but at higher frequencies the spectrum is dominated by the characteristics of the decay envelope of the shock wave signal. The explosive material in SUS charges is packed in a thin cylindrical cavity, resulting in a non-uniform decay envelope with secondary pulses when detonated, and a non-spherical distribution of the radiated sound. The impact of the cylindrical charge shape on energy density source level was investigated experimentally. Data were recorded for SUS deployments that generated in-line and broadside sound propagation to the receiver with respect to the axis of the cylindrical charge. Experimental measurements indicate significant differences in the high frequency SUS energy density spectrum depending upon the SUS and receiver geometry.

Comparative dynamics analysis of the environmental policy efficacy in a nonlinear Cournot duopoly with differentiated goods and emission charges

The price and the exchanged quantity volatility observed in real-world markets may be explained, according to the existing empirical literature, in terms of the endogenous fluctuations generated by the presence of nonlinearities. We then replace with a sigmoid adaptive best response mechanism the linear partial adjustment best response rule considered in Mamada and Perrings (2020), where the effect produced by quadratic emission charges on the dynamics of a Cournot duopoly model with homogeneous goods was investigated. Moreover, the sigmoid nonlinearity, in addition to being well suited to describe the bounded output variations caused by physical, historical and institutional constraints, makes the model able to generate interesting, non-divergent dynamic outcomes, despite the linearity of the demand function and of marginal costs. Additionally, following the suggestion in Mamada and Perrings (2020), we deal with the more general case of differentiated products. Beyond analytically studying the stability of the unique steady state, coinciding with the Nash equilibrium, and the effect produced by the main parameters on the stability region, we perform two comparative dynamics investigations which allow to evaluate the environmental policy efficacy when the Nash equilibrium is not stable and thus the standard comparative statics technique does not fit for the purpose. In particular, the former analysis, which is based on a comparison of emissions for different levels of charges, shows that, also in case the Nash equilibrium is not stable, the considered environmental policy may be effective both with complements and with substitutes. The latter investigation, consisting in a comparison of emissions along non-stationary trajectories and along the equilibrium path, in the proposed experiments highlights that emissions are larger along non-stationary trajectories. This gives us the opportunity to show how to act on the level of the asymptotes of the sigmoid adjustment mechanism to reduce output variations, reaching at one time a complete stabilization of the system and limiting pollution.

Spermidine enhances heat tolerance of rice seeds during mid-filling stage and promote subsequent seed germination.

Heat stress is a vital factor which restricts rice seed quality and yield. However, the response mechanism to heat stress in the mid filling stage of rice seed is unclear. In the present study we integrated phenotypic analysis with biochemical, hormone, and gene expression analysis in order to explore technologies for improving rice seeds heat tolerance and subsequent seed germination. Spermidine (Spd) application effectively alleviated the damage of heat stress treatment during mid-filling stage (HTM, 12-20 days after pollination) on seed development, promoted subsequent seed germination and seedlings establishment. Spd significantly increased seed dry weight, starch and amylose contents during seed development under heat stress, and improved seed germinate, seedlings establishment and seedling characteristics during germination time. Biochemical analysis indicated that, HTM significantly decreased the activities of several starch synthase enzymes and led to a decrease in starch content. While Spd treatment significantly enhanced the activities of ADP-glucose pyrophosphorylas and granule-bound starch synthase, as well as the corresponding-genes expressions in HTM rice seeds, resulting in the increases of amylose and total starch contents. In addition, Spd significantly increased the catalase and glutathione reductase activities together with corresponding-genes expressions, and lowered the overaccumulation of H2O2 and malondialdehyde in HTM seeds. In the subsequent seed germination process, HTM+Spd seeds exhibited dramatically up-regulated levels of soluble sugars, glucose, ATP and energy charges. Consistently, HTM+Spd seeds showed significantly increased of α-amylose and α-glucosidase activities as well as corresponding-genes expressions during early germination. Moreover, HTM evidently increased the abscisic acid (ABA) content, decreased the gibberellin (GA) content, and accordingly significantly declined the GA/ABA ratio during early rice seeds germination. However, Spd treatment did not significantly affect the metabolism of GA and ABA in seed germination stage. The present study suggested that Spd treatment could effectively alleviate the negative impact of HTM on seed development and the subsequent seed germination, which might be closely correlated with starch synthesis and antioxidant defense during seed filling period, starch decomposition and energy supply in seed germination period.

Probing the energy levels of organic bulk heterojunctions by varying the donor content

The performance of organic solar cells is strongly governed by the properties of the photovoltaic active layer. In particular, the energetics at the donor (D)–acceptor (A) interface dictate the properties of charge transfer (CT) states and limit the open-circuit voltage. More generally, energetic landscapes in thin films are affected by intermolecular, e.g., van der Waals, dipole, and quadrupole, interactions that vary with D:A mixing ratio and impact energy levels of free charges (ionization energy, electron affinity) and excitons (singlet, CT states). Disentangling how different intermolecular interactions impact energy levels and support or hinder free charge generation is still a major challenge. In this work, we investigate interface energetics of bulk heterojunctions via sensitive external quantum efficiency measurements and by varying the D:A mixing ratios of ZnPc or its fluorinated derivatives and C60. With increasing donor fluorination, the energetic offset between FxZnPc and C60 reduces. Moving from large to low offset systems, we find qualitatively different trends in device performances with D:C60 mixing ratios. We rationalize the performance trends via changes in the energy levels that govern exciton separation and voltage losses. We do so by carefully analyzing shifts and broadening sEQE spectra on a linear and logarithmic scale. Linking this analysis with molecular properties and device performance, we comment on the impact of charge–quadrupole interactions for CT dissociation and free charge generation in our D:C60 blends. With this, our work (1) demonstrates how relatively accessible characterization techniques can be used to probe energy levels and (2) addresses ongoing discussions on future molecular design and optimal D–A pairing for efficient CT formation and dissociation.

Mark-Up Trends in Contemporary Medicare Primary and Revision Total Joint Arthroplasty

BackgroundUnderstanding mark-up ratios (MRs), the ratio between a healthcare institution’s submitted charge and the Medicare payment received, for high-volume orthopaedic procedures is imperative to inform policy about price transparency and reducing surprise billing. This analysis examined the MRs for primary and revision total hip and knee arthroplasty (THA and TKA) services to Medicare beneficiaries between 2013 and 2019 across healthcare settings and geographic regions. MethodsA large dataset was queried for all THA and TKA procedures performed by orthopaedic surgeons between 2013 and 2019, using Healthcare Common Procedure Coding System (HCPCS) codes for the most frequently used services. Yearly MRs, service counts, average submitted charges, average allowed payments, and average Medicare payments were analyzed. Trends in MRs were assessed. We evaluated 9 THA HCPCS codes, averaging 159,297 procedures a year provided by a mean of 5,330 surgeons. We evaluated 6 TKA HCPCS codes, averaging 290,244 procedures a year provided by a mean of 7,308 surgeons. ResultsFor knee arthroplasty procedures, a decrease was noted for HCPCS code 27438 (patellar arthroplasty with prosthesis) over the study period (8.30 to 6.62; P = .016) and HCPCS code 27447 (TKA) had the highest median (interquartile range [IQR]) MR (4.73 [3.64 to 6.30]). For revision knee procedures, the highest median (IQR) MR was for HCPCS code 27488 (removal of knee prosthesis; 6.12 [3.83-8.22]). While no trends were noted for both primary and revision hip arthroplasty, median (IQR) MRs in 2019 for primary hip procedures ranged from 3.83 (hemiarthroplasty) to 5.06 (conversion of previous hip surgery to THA) and HCPCS code 27130 (total hip arthroplasty) had a median (IQR) MR of 4.66 (3.58-6.44). For revision hip procedures, MRs ranged from 3.79 (open treatment of femoral fracture or prosthetic arthroplasty) to 6.10 (revision of THA femoral component). Wisconsin had the highest median MR by state (>9) for primary knee, revision knee, and primary hip procedures. ConclusionThe MRs for primary and revision THA and TKA procedures were strikingly high, as compared to nonorthopaedic procedures. These findings represent high levels of excess charges billed, which may pose serious financial burdens to patients and must be taken into consideration in future policy discussions to avoid price inflation.

Comparison of gold and PEDOT:PSS contacts for high-resolution gastric electrical mapping using flexible printed circuit arrays.

Motility of the stomach is governed by an electrophysiological event termed gastric slow waves. High-resolution (HR) bioelectrical mapping involves placing array of electrodes over the surface of the stomach to record gastric slow waves. Conductive polymer materials have recently been applied to great effect in cardiology and neurophysiology due to its compliant and biocompatible properties. The aim of this study was to quantify the performance of poly(3,4-ethylenedioxythiophene) doped with poly(styrenesulfonate) (PEDOT:PSS) deposited on a flexible print circuit electrode array for gastric slow wave HR mapping. The Au electrodes were coated with PEDOT:PSS at 1 V and different levels of charges (0.3-1.2 mC). HR mapping alongside standard Au electrodes was performed in three anesthetized pigs. Overall, the PEDOT:PSS electrodes detected both antegrade and retrograde slow wave propagations, with comparable frequency, velocity and signal-to-noise ratio to the Au electrodes. Differences between the two electrodes were noted in terms of amplitude and downstroke gradient. The findings of this study will inform designs of future stretchable and implantable HR mapping electrode arrays for gastrointestinal recording and stimulation therapies.

Generation and characterization of electrostatically charged radiolabelled aerosols for lung scintigraphy

Particles and droplets produced from pharmaceutical inhaler devices are naturally charged. Previous in silico and in vitro studies have shown that the levels of these electrostatic charges may pote...

Reflective Roofing Use on Commercial Buildings in the United States: An Energy Type and Cost Analysis

Reflective roof membranes have been shown to lower air conditioning costs by reducing the influx of thermal energy through a roof assembly and into the building. However, there have been studies suggesting that reflective roofs in cold climates give rise to increased winter heating costs, due to the lack of absorption of solar thermal energy. Such studies could be used to justify continued use of dark, absorptive roof membranes even in areas that are striving to reduce urban heat island effects and/or lower contributions to global warming. In a prior modeling study, by this author and others, based on gas heat, it was found that reflective roofing provides net annual energy savings so long as air conditioning was used. Studies by others have suggested that when electric heat is used, the winter heating cost savings associated with non-reflective roofing outweigh summer air conditioning cost savings with reflective roofing. However, these studies did not take into account electric demand charges. Therefore, this present study modeled the energy efficiency of commercial buildings in order to compare the effect of gas versus electric heat with varying levels of demand charge included, on the net energy efficiency. Four different levels of demand charges were compared, along with three levels of solar reflectance for thirteen cities located throughout the US. In every studied case, when gas heat was assumed, net annual energy savings were predicted for reflective membranes. For electric heat, net energy savings were achieved in most cases even when demand charges were zero. In three northernmost cities, this was the case provided that demand charges exceeded a relatively small minimum. This finding suggests that reflective roofing provides for net energy efficiency improvements in most US cities and all cities when demand charges exceed USD 6.25 Therefore, efforts by cities to encourage reflective roofing as part of urban heat island effect mitigation programs should not be reduced.

System-level performance optimization of molten-salt packed-bed thermal energy storage for concentrating solar power

Molten-salt packed-bed thermal energy storage using thermocline technology is more cost-competitive than the conventional two-tank thermal energy storage, due to its integrated design and the employment of a low-cost packed-bed. However, such a storage configuration suffers the main drawback of a low capacity factor when applied to concentrating solar power because of the adoption of conservative cut-off temperatures. The present work evaluates the feasibility of taking less conservative cut-off temperatures to improve the utilization of the packed-bed thermal energy storage from the perspectives of a system-level operation and storage economy. The investigations are carried out on two levels. The first-level investigation reveals the effects of both the charging and discharging cut-off temperature on the thermal performance of the packed-bed thermal energy storage under ideal operating conditions. Three typical packed-bed configurations are involved. The results show that the capacity factor of the packed-bed thermal energy storage increases as the charging cut-off temperature increases and the discharging cut-off temperature decreases, especially for the configurations using latent-heat when the adopted cut-off temperatures jump over the phase change points of the encapsulated phase change materials. The second-level investigation discusses the impacts of different levels of deep charges (using high charging cut-off temperatures) on the scale design of the packed-bed thermal energy storage, the daily operation of the low temperature molten-salt pump (LT-pump) and the central receiver of a 100 MWe conventional concentrating solar power tower plant. The results indicate that a deeper charge operation is always accompanied with a smaller required packed-bed size as well as a higher required delivery capacity and higher pressure head of the LT-pump and that it always results in a larger daily pumping consumption, a higher peak inlet temperature ramping rate and a higher receiver pressure drop. The maximum allowable charging cut-off temperature is identified to be 500 °C for each packed-bed configuration, according to the operating limitations on the pump and receiver. Moreover, a cost analysis is carried out to obtain the optimum charging cut-off temperature for each packed-bed configuration. The obtained results show that performing deep charges with the cost-optimized charging cut-off temperatures can effectively improve the cost competitiveness of the molten-salt packed-bed TES integrated into concentrating solar power plants.

A study on the triboelectric charging of display glass during the roller transfer process–modeling and characterization

Glass substrates for displays are insulating materials capable of generating and maintaining high levels of triboelectric charges posing a risk of electrostatic discharge (ESD) damage to electronic display components. In this work, an apparatus for triboelectric charging characterization of display glass during the roller transfer process was designed and fabricated. In order to establish the reliability of the characterization, the triboelectric charge and the electrostatic potential distribution measurement system was automated. The preconditioning process of the glass and the rollers was also addressed. In order to analyze the measurements' results, a multiphysics model that considered both electrical and mechanical properties was proposed. The test parameters that were expected to affect the triboelectric charging characteristics are defined and discussed, as well as some of the characterization results such as the effects of acceleration/deceleration and maximum velocity, relative humidity and moisture on the glass and the rollers, and the conductivity of the rollers. The peak-to-peak deviation of the de-embedded triboelectric charges, due to a steady-state velocity period with different combinations of acceleration/deceleration and maximum velocities, was 14.2%. The triboelectric charges increased as the relative humidity increased from 30% to 50% with the same temperature. They also increased when the insulating rollers were replaced with dissipative rollers.

DEVELOPMENT OF THE ENERGY EFFICIENT THERMOELECTRIC HEAT PUMP OF SPIRAL TYPE

Abstract. The necessity to intensify the process of heat transfer in the heat pump is justified. The possibility of heat pumps using for liquid cooling in the engine pipe is shown. The new heat pump design of spiral type with LED ring semiconductor structures, powered by magnetic induction is proposed. The efficiency of LED ring semiconductor structures that operate at low temperatures due to the difference in the levels of energy charges in p- and n-regions isrevealed. The mathematical model for the electrical and thermal parameters calculating of energy-efficient thermoelectric heat pump of the spiral type is developed. The diagram of coolant temperature dependence at the outlet of energy-efficient thermoelectric heat pump of spiral type on the supply current is built. The efficiency of spiral type thermoelectric heat pump application for cooling of the internal combustion engine is proven.

An Examination of Women Ex-Offenders With Methadone Histories.

Criminal (drug and prostitution) charges, employment levels (weekly hours), recent substance use in the past 6 months, and primary sources of income were examined among a sample ( n = 106) of women ex-offenders who had opioid use disorders with and without methadone histories. A general linear model was tested to examine differences in relation to methadone use history. Results from a one-way MANCOVA found that those with methadone histories reported significantly higher levels of drug and prostitution charges than those without any methadone history, but no significant differences in terms of weekly hours of employment or recent substance use were observed between groups. Women ex-offenders with methadone histories reported various sources of income beyond employment, and proportionally, more of these women reported prostitution as a primary source of income. Findings suggest that methadone maintenance treatments are not sufficient in meeting the needs of women ex-offenders.

Water services asset management: an international perspective

This paper illustrates how the development of asset management for water utilities across the globe has been initiated by recognition of the need to maintain the assets and levels of service at an economic cost and develop sound accounting practices. In the UK, consolidation of water services and developments in sewer surveying and computer modelling were key factors in the early growth of asset management. The paper goes on to draw lessons from the past 30 years in quantifying water utility assets, assessing their condition and performance and developing business plans, with the aim of providing a satisfactory level of service at an economic cost. The impact of privatisation on water services in England and Wales and of economic regulation across the UK are considered in relation to the development of asset management, capital investment, levels of service, customers and charges.

AC corona neutralization of positively and negatively charged polypropylene non-woven fabrics

The insulating materials can acquire high levels of electric charges, which are susceptible to generate electrostatic discharges. The present article aims at evaluating the efficiency of AC corona as neutralization mechanism for positively- and negativelycharged polypropylene non-woven fabrics. The samples were charged for 10 s, in ambient air, using a triode-type corona electrode system of positive polarity in the first set and negative polarity in the second set of experiments. In all experiments, the neutralization was performed 180 s after the charging process, with the samples moving at constant speed (3 cm/s) in the AC corona discharge zone generated by a dual-type corona electrode. The electric potential distribution at the surface of the samples was measured both before and after the neutralization. The experimental results show that the efficiency of neutralization depends on the amplitude and the frequency of the sinusoidal high-voltage that energizes the corona electrode. The negative charge proves to be more difficult to neutralize than the positive one.

Why Quantile Regression Makes Good Sense for Analyzing Economic Outcomes in Medical Research

Why Quantile Regression Makes Good Sense for Analyzing Economic Outcomes in Medical Research

Health policy reform in tough times: The case of Portugal

The financial rescue plan for the Portuguese economy details a number of adjustments to be made in the National Health Service. We review the changes on user charges. The requirement of the rescue plan on user charges is twofold: structure of user charges and the levels of user charges. Adoption of measures occurred within the timeframe required.The first part, structure of user charges, is already present in the Portuguese NHS and has been for a decade. The crucial decisions are therefore on the level of user charges. Increases in levels of user charges were substantial (roughly doubling their previous levels) although exemptions also expanded considerably the fraction of the population that is not required to pay user charges. The net effect is not clearly predictable.

Nanocontact Electrification: Patterned Surface Charges Affecting Adhesion, Transfer, and Printing

Contact electrification creates an invisible mark, overlooked and often undetected by conventional surface spectroscopic measurements. It impacts our daily lives macroscopically during electrostatic discharge and is equally relevant on the nanoscale in areas such as soft lithography, transfer, and printing. This report describes a new conceptual approach to studying and utilizing contact electrification beyond prior surface force apparatus and point-contact implementations. Instead of a single point contact, our process studies nanocontact electrification that occurs between multiple nanocontacts of different sizes and shapes that can be formed using flexible materials, in particular, surface-functionalized poly(dimethylsiloxane) (PDMS) stamps and other common dielectrics (PMMA, SU-8, PS, PAA, and SiO(2)). Upon the formation of conformal contacts and forced delamination, contacted regions become charged, which is directly observed using Kelvin probe force microscopy revealing images of charge with sub-100-nm lateral resolution. The experiments reveal chemically driven interfacial proton exchange as the dominant charging mechanism for the materials that have been investigated so far. The recorded levels of uncompensated charges approach the theoretical limit that is set by the dielectric breakdown strength of the air gap that forms as the surfaces are delaminated. The macroscopic presence of the charges is recorded using force-distance curve measurements involving a balance and a micromanipulator to control the distance between the delaminated objects. Coulomb attraction between the delaminated surfaces reaches 150 N/m(2). At such a magnitude, the force finds many applications. We demonstrate the utility of printed charges in the fields of (i) nanoxerography and (ii) nanotransfer printing whereby the smallest objects are ∼10 nm in diameter and the largest objects are in the millimeter to centimeter range. The printed charges are also shown to affect the electronic properties of contacted surfaces. For example, in the case of a silicon-on-insulator field effect transistors are in contact with PDMS and subsequent delamination leads to threshold voltage shifts that exceed 500 mV.

Abstract 2262: Dendrimer nanoparticle effects on the microenvironment: Examination of cellular motility, mitosis and inflammation

Abstract Background: The use of nanomaterials in biomedical applications is increasing exponentially, with multiple devices being explored for cancer imaging and therapy. For them to enter the clinic, however, it is very important that the toxicity as well as other effects on the tumor microenvironment is assessed accurately over time. In this study, we investigated the cell motility and the cell mitosis of proliferating human endothelial cells, critical components of the tumor microenvironment, while they are treated with PAMAM dendrimer nanoparticles using time-lapsed video microscopy. Conventional in vitro cytotoxicity assays give a cumulative result of the whole cell population whereas the time-lapsed video microscopy allows one to visualize continuously and analyze each cell separately for the cytotoxicity effect of the treatments. We also assess another critical component of the microenvironment, the “irritability” or inflammability of nanoparticles toward human lung macrophages using rocket immuno-electrophoresis, a powerful and quantitative immuno-analytical technique consists of a two-dimensional immunoelectrophoresis with a combination of conventional electrophoretic separation and electro-immunodiffusion. Purpose: Assessment of key tumor microenvironment in the cells exposed to PAMAM dendrimer nanoparticles Experimental: (a). HUVEC were treated with PAMAM generation-5 parent dendrimer nanoparticle and analyzed frame-by-frame using time-lapse video microscopy against the untreated cells. (b) Human lung macrophage cells were treated with PAMAM generation-5 dendrimers of different levels of surface positive charges or positive control turpentine. After 24 hours, the conditioned macrophage medium was added onto rat hepatoma cells. After 24 hours, the medium is removed and analyzed by rocket immunoelectrophoresis for inflammation markers, α1-acid glycoprotein and haptoglobin, two well known acute phase reactants whose levels in the serum increase following inflammatory stimuli. Results and Conclusions: (a) time-lapse video microscopy permitted the quantitative assessment of cell death and mitosis in treated and untreated endothelial cells. (b) In inflammation assays, fully positive surface-charged dendrimers, expected to have the most toxicity, were safe even at high physiologic concentrations (at or below 0.1 μM level) and did not exhibit any detectable toxicity (cell kill) or have any inflammatory effect on human lung macrophages in these concentrations. Neutralization of amino groups made these materials completely non-toxic, even at non-physiologic concentrations (1 μM) and none showed any significant inflammation effect compared to well known irritant turpentine, based on acute phase reactants α1-acid glycoprotein and haptoglobin levels whose levels in the serum increase following inflammatory stimuli. Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the 101st Annual Meeting of the American Association for Cancer Research; 2010 Apr 17-21; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2010;70(8 Suppl):Abstract nr 2262.

How do green charges transform industrial behaviour? An explorative case study of institutionalisation and transition in post-Communist Poland

Based on three explorative case studies of industrial environmental practices in Poland, this paper examines how green charges alter the situated knowledge of companies' environmental managers. The study illustrates that following the Communist collapse, companies began to take the environmental authorities seriously because more severe enforcement and higher levels of green charges were implemented. However, the study also develops the hypothesis that environmental managers' comprehension of environmental problems is determined by the chemicals imposed with a duty.

SDS-PAGE Focusing: Preparative Aspects

As a followup of our previous report (Zilberstein, G.; Korol, L.; Antonioli, P.; Righetti, P. G.; Bukshpan, S. Anal. Chem. 2007, 79, 821-827) on analytical SDS-PAGE focusing, a novel method is here reported for small-scale prefractionation of complex protein mixtures, for subsequent proteome analysis, based on mass separation of SDS-protein micelles not in a gel matrix, but in liquid cationic polymers assembled in a multicompartment electrolyzer (MCE) in a stepwise fashion at discrete and increasing levels of positive charges (from 3 to 28 mM), the neighboring chambers being separated by neutral agarose membranes. Unlike conventional SDS-PAGE, in which separation by mass of SDS-laden polypeptide chains is obtained in constant concentration or porosity gradient gels, the present method of SDS-PAGE focusing exploits a "steady-state" process by which the SDS-protein micelles are driven to stationary zones along the migration path and trapped into different compartments of the MCE device via interaction (and subsequent charge neutralization) with cationic polymers of fixed (but increasing from chamber to chamber from cathode to anode) charge density. Minimization of migration of the liquid cationic polymers is obtained via use of low voltage and by arranging for a buffer conductivity gradient along the migration path. The present setup has the advantage of high protein recoveries (up to 90%) without any contamination from ungrafted monomers and catalysts, as occurring in proteins recovered by passive elution from gel matrixes. Additionally, resolution can be fine-tuned by selecting cationic polymers of varying charge density in microstep increments. The cationic polymers, of desired charge density and proper viscosity, are prepared by standard polymerization conditions, can be easily precipitated and washed free of monomeric contaminants, and stored in a dry form for subsequent use.