阅读说明：本技术 一种含有酯化甘油的雾化剂及其制备方法和应用 (Atomization agent containing esterified glycerol and preparation method and application thereof ) 是由 黄龙 罗诚浩 刘冰 操吉学 祝浩 张璟 于 2021-09-06 设计创作，主要内容包括：本发明涉及加热不燃烧卷烟技术领域,尤其涉及一种含有酯化甘油的雾化剂及其制备方法和应用。这种雾化剂包括组分A：碳酸氢钠溶液；组分B：甘油、脂肪酸、以及甘油酯。本申请中,创造性地采用双组份雾化剂,组分A作为雾化剂的渗透剂|、用于帮助组分B渗透进入烟草原料中,组分B作为雾化剂的雾化+抗吸水剂。本申请通过组分B中作为包覆壳的组分与组分A发生反应生成气体来帮助组分B中抗吸水性组分渗透进入烟草原料中,提高烟草原料的抗吸水性的同时还提高了其雾化剂吸收率。(The invention relates to the technical field of heating non-combustible cigarettes, in particular to an atomizing agent containing esterified glycerol and a preparation method and application thereof. This nebulant comprises component a: sodium bicarbonate solution; and (B) component: glycerin, fatty acids, and glycerides. In the application, a two-component atomizing agent is creatively adopted, a component A is taken as a penetrating agent I of the atomizing agent and is used for helping a component B to penetrate into tobacco raw materials, and the component B is taken as an atomizing and water-resisting agent of the atomizing agent. According to the application, the component serving as the coating shell in the component B reacts with the component A to generate gas so as to help the water-resistant component in the component B to permeate into the tobacco raw material, so that the water-resistant property of the tobacco raw material is improved, and the absorption rate of an atomizing agent of the tobacco raw material is also improved.)

1. A nebulant comprising esterified glycerol, characterised in that: comprises the following components: sodium bicarbonate solution; and (B) component: glycerin, fatty acids, and glycerides.

2. A nebulant according to claim 1 containing esterified glycerol, characterised in that: the glyceride comprises one or more of stearic acid monoglyceride, palmitic acid monoglyceride, myristic acid monoglyceride, lauric acid monoglyceride, oleic acid monoglyceride, linoleic acid monoglyceride, and linolenic acid monoglyceride.

3. A nebulant according to claim 1 containing esterified glycerol, characterised in that: the fatty acid comprises one or more of stearic acid, palmitic acid, myristic acid, lauric acid, oleic acid, linoleic acid and linolenic acid.

4. A nebulant according to claim 1 containing esterified glycerol, characterised in that: the concentration of the sodium bicarbonate solution is 1-5%.

5. A process for preparing a nebulant according to any one of claims 1 to 4 containing esterified glycerol, characterised in that: the method comprises the following steps: s1, preparing a sodium bicarbonate solution to obtain a component A; s2, mixing fatty acid and glyceride to obtain a mixed system, dripping glycerin into the system, and homogenizing to obtain a component B.

6. A process according to claim 5 for the preparation of a nebulant comprising esterified glycerol, characterised in that: step S2 includes the following steps: mixing and dispersing fatty acid and glyceride at the rotation speed of 1000-1500r/min to obtain a mixed system; then adding glycerol into the mixed system at the rotating speed of 300-600 r/min; after the glycerol is added, the rotating speed is increased to 1000-.

7. Use of an esterified glycerol-containing nebulant according to any one of claims 1 to 4 for heating cigarettes, characterized in that: spraying the component A on the tobacco raw material, and then spraying the component B.

8. Use of an esterified glycerol containing nebulant for heating cigarettes according to claim 7, characterized in that: spraying the component A on the tobacco raw material, placing the tobacco raw material in an environment with the temperature not higher than 20 ℃ and the relative humidity not higher than 30% for balancing for 12-24h, and then spraying the component B.

9. Use of an esterified glycerol containing nebulant for heating cigarettes according to claim 7, characterized in that: spraying the component B, and standing for 1-3 h; then drying with cold air at a temperature of not higher than 20 deg.C for 5-10 min.

10. Use of an esterified glycerol containing nebulant for heating cigarettes according to claim 7, characterized in that: the mixing mass ratio of the tobacco raw material to the component A and the component B is 100: (0.1-0.3): (0.5-1).

Technical Field

The invention relates to the technical field of heating non-combustible cigarettes, in particular to an atomizing agent containing esterified glycerol and a preparation method and application thereof.

Background

Heating cigarettes (HTPs), also known as non-burning cigarettes or low temperature cigarettes, is a new strategic development direction in the tobacco industry at present. The tobacco substance is heated by an external heat source, and the atomized medium, the flavor components and the additional flavor in the tobacco substance generate smoke similar to the smoke of the traditional cigarette through heating, so that the consumers can obtain physiological satisfaction. The tobacco substances in the heated cigarette are only heated but not combusted, so that the harmful components and the biotoxicity of the smoke are greatly reduced, and the side-stream smoke and the environmental smoke are also greatly reduced, thereby being more beneficial to the health of consumers.

In order to produce a strong smoke similar to that of conventional cigarettes during the heating process of HTPs, the prior art often requires the addition of a large amount of a nebulizing agent such as glycerin and 1, 2-propanediol to the tobacco material of HTPs. Glycerol and 1, 2-propylene glycol are common additives in traditional cigarettes, and are mainly used as solvents and flavor fixatives for flavors and fragrances in traditional cigarettes, and the dosage of glycerol and 1, 2-propylene glycol is generally several thousandth of the mass of tobacco substances (mass fraction). In the heated cigarette, the glycerol and the 1, 2-propylene glycol are used as the atomizing agent, and the dosage of the glycerol and the 1, 2-propylene glycol is as high as 20-30% (mass fraction) or even more than 40% of the mass of the tobacco substances, so that the dosage of the glycerol and the 1, 2-propylene glycol in the heated cigarette is two orders of magnitude higher or even higher than that of the traditional cigarette.

However, glycerin and propylene glycol, when used as a nebulant, have the following problems: the glycerin has a certain sweet taste, and when a large amount of glycerin is used as a fogging agent, uncomfortable symptoms such as dry throat, irritation, sweet and greasy feeling and the like are often caused when a consumer sucks and heats cigarettes. The taste of propylene glycol is not suitable for some consumers, and the substitute thereof is hopefully to be found and compounded with glycerol.

To this end, patent publication No. CN104473323A discloses such an electronic cigarette aerosol. The components of the atomizing agent comprise ester compounds, water, propylene glycol and/or glycerol; the ester compound is one or a mixture of a plurality of monobasic ester compounds, dibasic ester compounds and tribasic ester compounds in any proportion. In the application, the sweet and greasy feeling brought by using a large amount of glycerin and propylene glycol in the existing atomizing agent is overcome through the ester compound, the smoking taste of the electronic cigarette is improved, the electronic cigarette is closer to the smoking taste of the traditional cigarette, and the popularization and the use of the electronic cigarette are facilitated.

However, in this application, firstly, propylene glycol or glycerin is still contained, both glycerin and propylene glycol have strong water absorption, and moisture has a significant effect on the sensory quality of the heated cigarette. In the process of the invention, the inventor finds that the tobacco material and the cigarette of the heated cigarette can continuously absorb water no matter under the environment conditions of high temperature, low temperature, high humidity and low humidity, only the water absorption rate is different, and the water absorption is slower in the low humidity environment. However, moisture in natural environment is ubiquitous, so on one hand, high requirements are put on the processing and production environment of the heated cigarette, and the processing and production environment needs to be carried out in a low-humidity environment so as to absorb moisture as little as possible; on the other hand, the production and the manufacture are difficult, the tobacco material applied with the atomizing agents such as glycerin, propylene glycol and the like is soft, and tobacco substances are agglomerated and difficult to roll up in the cigarette rolling and connecting process after water absorption; on the other hand, the quality control is difficult, and the tobacco materials and cigarettes continuously absorb moisture, so that the moisture of the heated cigarettes produced and manufactured in different seasons, different climates, different batches, different teams and different machines is difficult to control consistently, and the quality fluctuation is caused; on the other hand, higher requirements are provided for storage and transportation, the tobacco material for heating the cigarettes and the storage and transportation of the cigarettes need to reduce the exposure time in the environment, and a lower humidity environment is needed; on the other hand, the quality guarantee time of the heated cigarette is shortened, and the tobacco material and the cigarette continuously absorb moisture to cause the moisture to continuously rise and easily deteriorate, so that the quality guarantee time of the heated cigarette is shortened; on the last hand, the consumption experience of consumers is influenced, and after the cigarettes are heated and unpacked, the cigarettes which are drawn at the beginning are different from the cigarettes which are drawn at the last, and the sensory quality is different. Therefore, the method has important significance for reducing the water absorption performance of the heated cigarette. Secondly, the viscosity and surface tension of the glycerol are high, and when the glycerol is directly added into tobacco substances, particularly tobacco shreds, the glycerol is difficult to permeate into the tobacco shreds from the surfaces of the tobacco shreds, so that the loading capacity of the tobacco shreds on the glycerol is limited.

Disclosure of Invention

The invention aims to solve the problems and provides an atomizing agent containing esterified glycerol, a preparation method and application thereof.

The technical scheme for solving the problems is to provide an atomization agent containing esterified glycerol, which comprises a component A: sodium bicarbonate solution; and (B) component: glycerin, fatty acids, and glycerides.

In the application, the atomizing agent creatively adopts a two-component atomizing agent, namely, the two components are not mixed before being added into the tobacco raw material and are sequentially added when being added into the tobacco raw material. The component A is used as a penetrating agent I of the atomizing agent and is used for helping the component B to penetrate into the tobacco raw material, and the component B is used as an atomizing and water-resisting agent of the atomizing agent. The mechanism is as follows: firstly, a component A with good permeability is added into a tobacco raw material, and the component A can permeate into the tobacco raw material. Then, the component B with better water absorption resistance but poorer permeability is added. The component B can react with the component A to generate gas in the adding process, so that the gas generated by the component A which has permeated into the tobacco raw material can spread the fibers of the tobacco raw material in the process of escaping from the tobacco raw material so as to be supplied to the component B, thereby improving the absorption rate of the tobacco raw material for the atomizing agent component with good water absorption resistance.

The component A comprises a sodium bicarbonate solution, and the sodium bicarbonate solution has low viscosity and can quickly permeate into the tobacco raw materials; meanwhile, the sodium bicarbonate solution is weakly alkaline, so that the cut tobacco can be slightly corroded, the pore size of the cut tobacco is increased, and the follow-up component B is helped to enter the tobacco raw material.

Preferably, the concentration of the sodium bicarbonate solution is 1-5%.

In the component B, the glyceride refers to a product in which one of three hydroxyl groups in the molecular structure of glycerol is esterified, or/and a product in which two hydroxyl groups are esterified, or/and a product in which three hydroxyl groups are esterified. Preferably, the glyceride comprises one or more of stearic acid monoglyceride, palmitic acid monoglyceride, myristic acid monoglyceride, lauric acid monoglyceride, oleic acid monoglyceride, linoleic acid monoglyceride and linolenic acid monoglyceride. In the component B, partial glycerin is replaced by glyceride, firstly, the sweetness and greasiness of the glycerin are mainly from hydroxyl in molecules, and if the hydroxyl is partially or completely esterified, the sweetness and greasiness of the obtained glycerin are greatly reduced compared with the glycerin, so the sweetness and greasiness of the glycerin can be reduced; secondly, if the hydroxyl groups of glycerol are partially or completely esterified, the hydrogen bonding interaction between the obtained glyceride molecules is greatly reduced compared with that of glycerol, so that the viscosity and boiling point of the glyceride are generally much lower than those of the glycerol. When the composite atomizing agent of the glyceride and the glycerol is applied to heating cigarettes, the glyceride with low viscosity can effectively promote the permeation and diffusion of the glycerol with high viscosity in tobacco substances, the generation of smoke during heating is facilitated, and meanwhile, the azeotrope formed by the glyceride and the glycerol is beneficial to reducing the atomizing temperature and improving the atomizing efficiency.

The component B also comprises fatty acid, and the fatty acid is used for reacting with the sodium bicarbonate in the component A to generate gas; secondly, the fatty acids have oleophilic long carbon chains, so that the water absorption resistance of the component B can be further improved; and thirdly, fatty acid can be esterified with glycerol to obtain glyceride, so that the sweet and greasy feeling of the atomizing agent is reduced and the atomizing temperature is reduced by further increasing the content of the glyceride. Preferably, the fatty acid comprises one or more of stearic acid, palmitic acid, myristic acid, lauric acid, oleic acid, linoleic acid and linolenic acid.

It is another object of the present invention to provide a process for the preparation of a nebulant comprising esterified glycerol comprising the steps of: s1, preparing a sodium bicarbonate solution to obtain a component A; s2, mixing fatty acid and glyceride to obtain a mixed system, dripping glycerin into the system, and homogenizing to obtain a component B.

In this application, mainly in step S2, glycerin is coated with fatty acid, and glyceride serves as a connecting bridge between fatty acid and glycerin to form a fatty acid-glyceride-glycerin structure. Sodium bicarbonate is through the reaction with fatty acid in order to impel fatty acid to lead glyceride and glycerine to get into inside the tobacco raw materials, be close to sodium bicarbonate, and the fatty acid reacts and causes the fatty acid shell to break open when getting into inside the tobacco raw materials simultaneously for the structure of glyceride cladding glycerine exposes in order to distribute in the inside of tobacco raw materials, has avoided glycerine to expose through the glyceride and has absorbed water in a large amount outside.

Preferably, step S2 includes the steps of: mixing and dispersing fatty acid and glyceride at the rotation speed of 1000-1500r/min to obtain a mixed system; then adding glycerol into the mixed system at the rotating speed of 300-600 r/min; after the glycerol is added, the rotating speed is increased to 1000-.

It is a further object of the present invention to provide the use of an atomiser comprising esterified glycerol for heating cigarettes by spraying component A on tobacco material followed by spraying component B.

Preferably, the component A is sprayed on the tobacco raw material, and then the tobacco raw material is placed in an environment with the temperature not higher than 20 ℃ and the relative humidity not higher than 30% for balancing for 12-24h, and then the component B is sprayed. So as to ensure that the component A and the component B fully react in a low-temperature drying environment, and the components fully permeate into the tobacco raw materials.

Preferably, after the component B is sprayed, standing for 1-3 h; then drying with cold air at a temperature of not higher than 20 deg.C for 5-10 min. Sodium bicarbonate also generates sodium chloride and water after reaction, and the sodium chloride and the water are removed by cold air drying.

Preferably, the coating is dried with cold air, and has a thickness of 0.5-1cm and a surface area of 1m²The air volume of the tobacco raw material pile is 500-600 CMM.

Preferably, the mixing mass ratio of the tobacco raw material to the component A and the component B is 100: (0.1-0.3): (0.5-1).

Preferably, the tobacco raw material comprises one or more of cut tobacco, thin slice, cut stem, expanded cut tobacco and tobacco particles.

Preferably, the tobacco material is subjected to puffing, or/and baking, or/and steam explosion treatment before spraying component A.

The invention has the beneficial effects that:

1. in the application, the two-component atomizing agent is creatively adopted, so that the absorption of the components with high water absorption resisting performance of the tobacco raw material is improved.

2. In the application, partial glycerin is replaced by the glyceride and the fatty acid, the glyceride and the fatty acid have good surface activity, the surface tension of the atomizing agent can be effectively reduced, the fluidity is improved, the permeability on the surface of the tobacco raw material is further enhanced, and the absorption loading capacity of the tobacco raw material to the atomizing agent is increased. In addition, the throat dryness, irritation and sweet and greasy feeling which are usually caused by using a large amount of glycerin can be improved, and the smoking quality of the heated cigarette is improved. Meanwhile, the glyceride has lower atomization temperature, the heating atomization temperature for heating the cigarette can be reduced, the temperature of a required heating element is reduced, and energy is saved; and the temperature of the mainstream smoke of the heated cigarette is reduced, so that the burning feeling and the mouth burning accident during smoking are avoided.

Detailed Description

The following are specific embodiments of the present invention and further describe the technical solutions of the present invention, but the present invention is not limited to these examples.

Example 1

A nebulant comprising esterified glycerol prepared by the steps of:

preparing a component A: sodium bicarbonate; preparing a component B: 20 parts by mass of glycerin, 5 parts by mass of fatty acid, and 15 parts by mass of glycerin ester were prepared.

S1, adding sodium bicarbonate into deionized water to prepare a sodium bicarbonate solution with the concentration of 3% to obtain a component A;

s2, mixing and dispersing fatty acid and glyceride at the rotating speed of 1200r/min to obtain a mixed system; then slowly adding glycerol into the mixed system at the rotating speed of 400 r/min; after the glycerol is added, the rotating speed is increased to 1300r/min, and the mixture is homogenized for 4min, so that the component B is obtained.

Spraying the component A on the tobacco raw material, and then spraying the component B. The mixing mass ratio of the tobacco raw material to the component A and the component B is 100: 0.2: 0.8.

example 2

This embodiment is substantially the same as embodiment 1, except that:

in the spraying step, after the component A is sprayed on the tobacco raw material, the tobacco raw material is placed in an environment with the temperature of 15 ℃ and the relative humidity of 25% for balancing for 18 hours, and then the component B is sprayed. The mixing mass ratio of the tobacco raw material to the component A and the component B is 100: 0.2: 0.8.

example 3

This embodiment is substantially the same as embodiment 1, except that:

in the spraying step, after the component A is sprayed on the tobacco raw material, the component B is sprayed. Spraying the component B, and standing for 2 h; then drying with cold air at 10 deg.C for 8 min. The mixing mass ratio of the tobacco raw material to the component A and the component B is 100: 0.2: 0.8.

example 4

This embodiment is substantially the same as embodiment 1, except that:

in the spraying step, after the component A is sprayed on the tobacco raw material, the tobacco raw material is placed in an environment with the temperature of 15 ℃ and the relative humidity of 25% for balancing for 18 hours, and then the component B is sprayed. Standing for 2 h; then drying with cold air at 10 deg.C for 8 min. The mixing mass ratio of the tobacco raw material to the component A and the component B is 100: 0.2: 0.8.

example 5

A nebulant comprising esterified glycerol prepared by the steps of:

preparing a component A: sodium bicarbonate; preparing a component B: 30 parts by mass of glycerin, 2 parts by mass of fatty acid, and 8 parts by mass of glycerin ester were prepared.

S1, adding sodium bicarbonate into deionized water to prepare a sodium bicarbonate solution with the concentration of 1% to obtain a component A;

s2, mixing and dispersing fatty acid and glyceride at the rotating speed of 1000r/min to obtain a mixed system; then slowly adding glycerol into the mixed system at the rotating speed of 300 r/min; after the glycerol is added, the rotating speed is increased to 1000r/min, and the mixture is homogenized for 5min, so that the component B is obtained.

Spraying the component A on the tobacco raw material, placing the tobacco raw material in an environment with the temperature of 20 ℃ and the relative humidity of 30% for balancing for 12 hours, and then spraying the component B. Spraying the component B, and standing for 1 h; then drying with cold air at 20 deg.C for 5 min. The mixing mass ratio of the tobacco raw material to the component A and the component B is 100: 0.1: 0.5.

example 6

A nebulant comprising esterified glycerol prepared by the steps of:

preparing a component A: sodium bicarbonate; preparing a component B: 10 parts by mass of glycerin, 10 parts by mass of fatty acid, and 20 parts by mass of glycerin ester were prepared.

S1, adding sodium bicarbonate into deionized water to prepare a sodium bicarbonate solution with the concentration of 5% to obtain a component A;

s2, mixing and dispersing fatty acid and glyceride at the rotating speed of 1500r/min to obtain a mixed system; then slowly adding glycerol into the mixed system at the rotating speed of 600 r/min; after the glycerol is added, the rotating speed is increased to 1500r/min, and the mixture is homogenized for 3min, so that a component B is obtained.

Carrying out puffing treatment on a tobacco raw material: placing a tobacco material in a pressure vessel, pressurizing the interior of the pressure vessel with gaseous carbon dioxide to an impregnation pressure of at least about 4.3kg/cm 2 in gauge pressure, supplying liquid carbon dioxide from above the tobacco material while maintaining the impregnation pressure, saturating carbon dioxide gas in the pressure vessel by evaporation of the liquid carbon dioxide, holding the pressure for 10 seconds, reducing the pressure in the pressure vessel to substantially atmospheric pressure, and taking out the tobacco material from the pressure vessel; the removed tobacco material is fed to a pneumatic dryer where it is expanded by contacting it with a high temperature air stream.

Spraying the component A on the tobacco raw material, placing the tobacco raw material in an environment with the temperature of 5 ℃ and the relative humidity of 20 percent for balancing for 24 hours, and then spraying the component B. Spraying the component B, and standing for 3 h; then drying with cold air at 5 deg.C for 10 min. The mixing mass ratio of the tobacco raw material to the component A and the component B is 100: 0.3: 1.

Comparative example 1

Preparing glycerin, and directly spraying the glycerin onto the tobacco raw material at normal temperature, wherein the mixing mass ratio of the glycerin to the tobacco raw material is 100: 0.8.

Comparative example 2

This comparative example is essentially the same as example 1 except that: the fatty acid was replaced with hydrochloric acid.

Comparative example 3

20 parts by mass of glycerin, 5 parts by mass of fatty acid, and 15 parts by mass of glycerin ester were prepared.

Mixing and dispersing fatty acid and glyceride at the rotating speed of 1200r/min to obtain a mixed system; then slowly adding glycerol into the mixed system at the rotating speed of 400 r/min; after the glycerol is added, the rotating speed is increased to 1300r/min, and the mixture is homogenized for 4min, so that a mixture is obtained.

Spraying the mixture onto the tobacco material. The mixing mass ratio of the tobacco raw materials to the mixture is 100: 0.8.

Comparative example 4

A 3% strength sodium bicarbonate solution prepared in example 1 was prepared, along with 20 parts glycerol, 5 parts fatty acid, 15 parts glycerol ester.

The glycerol, the fatty acid and the glyceride are directly and uniformly mixed to obtain a mixture.

After spraying the sodium bicarbonate solution on the tobacco raw material, spraying the mixture. The mixing mass ratio of the tobacco raw material to the sodium bicarbonate solution to the mixture is 100: 0.2: 0.8.

[ anti-Water-absorption assay ]

Taking 10 weighing bottles with diameters of 50mm and heights of 50mm and covers, accurately weighing the weights of the weighing bottles respectively, and recording as M₀. The mass of the sheets or tobacco threads of examples 1 to 6 and comparative examples 1 to 4 immediately after the application of the atomizing agent was measured and recorded as M₁. Respectively placing 11 parts of tobacco raw materials into weighing bottles, opening weighing bottle caps, and placing the bottles in a constant temperature and humidity box (the temperature is 22 +/-0.5 ℃, and the relative humidity is 60 +/-1 percent) for balancing.

And timing when the sample enters the constant temperature and humidity chamber from the beginning of placement. Covering the bottle cap at regular intervals T, taking out the weighing bottle, weighing, and recording the mass as M₂. The change in sheet moisture after the equilibration time T is: (M)₂ -M₀）/ M₁X 100%. The results of the measurement calculation are shown in table 1 below.

Table 1.

[ determination of absorptivity by nebulant ]

According to the formula: (M)₁Smoke before application of nebulantMass of grass material)/mass of tobacco material prior to the application of the aerosol, the measured absorption ratio of the aerosol in the tobacco material is calculated. And simultaneously according to the formula: nebulant absorption = measured absorption/theoretical application ratio, calculated to give the nebulant absorption as shown in table 2 below.

Table 2.

As can be seen from tables 1 and 2, in comparative example 1, only glycerin is used as an atomizing agent, and since glycerin is not subjected to any viscosity reduction treatment, the viscosity is high, so that the absorption rate of the tobacco raw material to glycerin is low, and the glycerin also has the problem of poor water absorption resistance. In comparative example 2, hydrochloric acid was used instead of fatty acid, and the reaction of hydrochloric acid with sodium bicarbonate was more intense than fatty acid, so that the tobacco raw material had a higher absorption rate of the atomizing agent, but the subsequent water absorption resistance was poor due to the reduction of the addition of lipophilic molecular chains of fatty acid. In comparative example 3, sodium bicarbonate is not used as a penetrant, so that the tobacco raw material has a lower absorption rate of the atomizing agent, but the absorption effect is better than that of the mono-component glycerin in comparative example 1, which shows that the fatty acid and the glyceride can improve the permeability of the atomizing agent in the tobacco raw material to a certain extent; meanwhile, because the absorption rate of the atomizing agent is low, most of the fatty acid-coated glycerin structure is attached to the surface of the tobacco raw material, so that the water absorption resistance of the tobacco raw material is good. In comparative example 4, a simple mixture of several components was used, which was relatively poor in both the rate of absorption of the atomizing agent and the water absorption resistance, relative to the coating structure of this example.

The specific embodiments described herein are merely illustrative of the spirit of the invention. Various modifications or additions may be made to the described embodiments or alternatives may be employed by those skilled in the art without departing from the spirit or ambit of the invention as defined in the appended claims.